22.B Solicitation Topics

A22B-T001 Novel, High-Energy-Density, Lithium-Air Reserve Batteries

RT&L Focus Area(s): General Warfighting Requirements

Technology Area(s): Weapons

ITAR: The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

Objective: Develop lithium-air reserve batteries for munitions, offering >3× the energy density of current liquid reserve batteries and operating across the military temperature range of -55°C to 125°C.

Description: The Army’s new Bottom Attack (BA) munitions for the Close Terrain-Shaping Obstacles (CTSO) program requires reserve batteries with 3-4 times higher specific energy density than that of currently available reserve batteries. Current lithium-metal-based reserve batteries used in munitions, such as those that employ lithium thionyl chloride chemistry, rely on the supply of a liquid electrolyte to the cathode electrode at the time of activation. This design requires storage of the liquid electrolyte separately from the rest of the battery inside a bulky glass ampoule that must be ruptured during the activation process. The extra weight and volume, coupled with the complexity of the glass ampoule, significantly reduces the practical specific energy density of these batteries.

Gas-activated batteries have the advantage eliminating liquid in the activation process. Lithium-air batteries have the highest theoretical energy density of all lithium metal batteries at 3,860 mA/g[1], based on the weight of lithium. A primary reserve Li-air battery has the potential of outperforming all existing commercial liquid reserve batteries in terms of energy density, activation times, and simplicity of the activation mechanism. However, some critical barriers to the practical implementation of Li-air batteries remain. Among the challenges are sluggish oxygen reduction reaction (ORR) kinetics[2], the deactivation of the porous cathode electrode by discharge products[3], electrolyte decomposition[3], lithium metal corrosion by air contaminants (e.g. H2O, N2, and CO2) and the liquid electrolyte, and slow mass transfer rates[4]. All these challenges significantly limit the practically achievable energy density and rate capacity of Li-air batteries. This topic seeks solutions to overcome these limitations to enable the design and demonstration of a primary reserve Li-air battery that is more energy dense than existing liquid reserve battery technologies, that can perform across a temperature range of -55°C to 125°C, and that has a shelf life of 20 years or more. The developed lithium-air reserve batteries must be capable of being hardened for gun-firing setback accelerations of up to 70,000 Gs.

Phase I: Model the proposed solutions to determine their potential to address the challenges of developing high-energy-density lithium-air reserve batteries for munitions applications, and select candidate technologies for phase I experimentation. Technologies that yield successful experimental data are to be demonstrated through proof-of-concept assemblies under appropriate discharge conditions. A conceptual design concept is to be delivered.

Phase II: The innovative solutions selected during phase I are to be optimized and implemented in battery prototypes to be designed, fabricated, and tested during phase II. These prototypes will be tested to demonstrate performance and energy density. Prototypes will include single cells and multiple cell battery packs. The offeror will work with the Army to define the most relevant discharge profiles and environmental testing conditions. The prototypes must demonstrate higher energy density than and comparable rate capacity to currently available liquid reserve batteries. A detailed cost analysis and a technology transition plan to scale up and commercialize the technology must also be prepared.

Phase III Dual Use Applications: Phase III will primarily entail refinement of the designs developed during phase II in preparation for a pre-production prototype. The effort will be coordinated with stakeholders during all phases, which will facilitate requirements definition and transition of the technology. Strategic partnerships will be developed to further the commercialization potential of the technology.

References:

Z. Zhou et al., “Lithium-air batteries: Challenges coexist with opportunities”, APL Materials, 7, 040701, (2019).;
J. Christensen et al., “A Critical Review of Li/Air Batteries”, Journal of The Electrochemical Society, 159 (2), R1-R30 (2012).;
S. D. Beattie, D. M. Manolescu and S. L. Blair, "High Capacity Lithium-Air Cathodes," Journal of Electrochemical Society, vol. 156, pp. A44-A47, 2009.;
E. Yoo and H. S. Zhou, "Li-Air Rechargeable Battery based on Metal-free Graphene Nanosheet Catalysts," ACS Nano, vol. 2011, no. 5, pp. 3020-3026, 2011.;
A. Nomura, K. Ito and Y. Kubo, "CNT Sheet Air Electrode for the Development of Ultra-high Cell Capacity in Lithium-Air Batteries," Nature Scientific Reports, pp. 1-8, 2017.;
M. Mirzaeian and P. J. Hall, "Preparation of controlled porosity carbon aerogels for energy storage in rechargeable lithium oxygen batteries," Electrochim. Acta, vol. 54, pp. 7444-7451, 2009.
J. Uddin, V. S. Bryantsev, V. Giordani, W. Walker and G. V. Chase, "Lithium nitrate as regenerative SEI stabilizing agent for rechargeable Li/O2 batteries," Physical Chemistry Letters, vol. 4, pp. 3760-3765, 2013.
J. Read , K. Mutolo, M. Ervin, W. Behl, J. Wolfenstine, A. Driedger and D. Foster, "Oxygen transport properties of organic electrolytes and performance of lithium/oxygen battery," Journal of the Electrochemical Society, vol. 150, no. 10, pp. A1351-A1356, 2003.

Keywords: Lithium-Air, Batteries, Energy Density

A22B-T002 Verification, Validation, Assurance, and Trust of Machine Learning

Models and Data for Safety-Critical Applications in Armaments Systems

RT&L Focus Area(s): Artificial Intelligence/Machine Learning, Cybersecurity

Technology Area(s): Weapons, Information Systems

Objective: To establish fundamental methodologies to verify and validate data sources and AI/ML models that require high assurance in safety-critical functions of armaments systems.

Description: Significant advances have been achieved in the field of machine learning (ML), spurring proliferation of the technology in the public and private sectors. This topic seeks to develop these technologies to achieve battlefield overmatch, intelligent analysis of combat information, and real-time decision-making to more rapidly achieve mission goals.

To achieve this mission capability, numerous fundamental complexities and challenges must be overcome to assure the developed technologies will operate within their operational and mission bounds safely and reliably. Some of these challenges include the following:

• Inability to view the model decision process • Inability to obtain training data or information after model development; • Lack of validated certification processes for models; • Inability to understand existing training (transfer learning); • Inability to fully capture the environmental noise and inputs that may influence decisions and actions.

Ultimately, to field products the Army must demonstrate they are safe, suitable, and supportable through the materiel release process as defined in AR-770-3. This project seeks to lay the groundwork for how ML based technologies will be qualified, particularly for Armaments Center applications, in which lethality capabilities require high-assurance and safety-critical qualifications. These technologies could utilize computer vision, signal processing, natural language, and regression, but other applications may be possible.

Phase I: Phase I will be the research and development of fundamental metrics and measures that can be used in the certification and qualification of training data sets and models, both combined and separate. Armaments Center must clearly understand the provenance, characteristics, and limitations of training data sets, the capabilities of models, how the two may be adapted or augmented to meet potential needs, and the potential risks associated with armaments system integration. Research to identify means of measurement of data sets and models will establish risk indicators for stakeholders and evaluators. Phase I will culminate in delivery of a detailed report outlining the proposed metrics and measures and the value of each to evaluating and mitigating risks associated with employing data sets or models in armaments systems, enabling end product qualification with items deemed safe, suitable, and supportable for materiel release to the field.

Phase II: Develop a process to effectively measure training data sets and models in accordance with previously derived key metrics and measures. Products of phase two would be process and procedures that align with current guidance and justify any deviations that may be required due to the unique nature of the technologies under study. This process must include the means and methods of evaluating the metrics and measures identified in phase I across different data types (images, tabular data, time series data) to address the concerns and uniqueness of safety-critical functions in the armament system’s applications and complex operating environments. In addition to following existing precepts for materiel release, develop risk reduction and evaluation techniques for situations in which no detailed requirements have been established earlier in the lifecycle (S&T, R&D phases) to aid in the development and design of products for assurance. Phase II will culminate with a documented process and procedures showcased in pilot demonstration.

Phase III Dual Use Applications: A fundamental product or process that can be leveraged to assess training data sets and models developed by and for Armaments Center prior to integration and formal testing with armaments systems. Training data sets to be assessed may include images, video, time series, and tabular data, depending on the application and the technology leveraged. The solution will allow Armaments Center to evaluate training data sets and model suitability for intended applications early in the lifecycle to accommodate any necessary corrective action, to provide a means to collect and document the key metrics and measures, and to communicate risks and concerns to assurance stakeholders. Ultimately the use of this product will enable materiel release stakeholders to clearly understand the risks and limitations of the data and associated models developed. The end product will help shape and inform the assurance model for AI/ML-enabled armaments systems critical to delivering lethality overmatch through enhanced speed and accuracy while meeting crucial standards for safety.

References:

E. Schmidt, R. Work, et.al., “Final Report: National Security Commission on Artificial Intelligence, Chapter 7 Establishing Justified Confidence in AI Systems” 2021.;
Department of the Army, “Army Regulation 770-3, Type Classification and Materiel Release,” July 2021;
Department of Defense, “MIL-STD-882E, Department of Defense Standard Practice System Safety,” May 2012;

Safety Critical Systems Club, Data Safety Initiative Working Group, “Data Safety Guidance,” SCSC-127F, February 2021.

Keywords: Artificial intelligence, machine learning, trust, assurance, test, evaluation, verification, validation, data

A22B-T003 Integration of Innovative, Safe Methods of Low-G Activation of Munitions

RT&L Focus Area(s): General Warfighting Requirements (GWR), Hypersonics

Technology Area(s): Weapons

Objective: Miniaturized, gun-hardened devices to be incorporated in reserve batteries and initiation trains addressing high-G loading and vibration during transportation and flight for shoulder-fired munitions, terrain shaping munitions, missiles, and rockets.

Description: In recent years, highly reliable inertial igniters have been successfully developed for use in gun-fired munitions and mortars that differentiate prescribed all-fire events from accidental events such as drops on hard surfaces and vibration during transportation. Such inertial igniters detect prescribed firing acceleration and differentiate it from accidental events by ensuring that minimum prescribed firing setback acceleration magnitude and duration have been experienced by the munition before activation. Such inertial igniters are employed to activate reserve batteries and initiation trains in gun-fired munitions, in which the projectile is subjected to high setback accelerations ranging from 1000 Gs to several thousand Gs with durations from several milliseconds to fifteen milliseconds. Reliable inertial igniters, however, do not currently exist for applications such as shoulder-fired munitions, terrain shaping munitions, missiles, and rockets, in which the firing setback accelerations are in tens of Gs, with durations as long as 100 milliseconds. Current technology mostly employs onboard power sources such as primary batteries or other power sources to power sensors such as accelerometers to detect a firing event and differentiate it from accidental events via onboard microprocessors. Onboard primary batteries introduce issues related to shelf life, safety, and reliability. As a result, eliminating onboard power sources is a highly desirable aim. To integrate the inertial activation devices into the reserve batteries is likewise very desirable. The primary objective of this SBIR project is the development of novel methods to design and integrate inertial initiation devices into reserve batteries and initiation trains that can be miniaturized to prevent unwanted activation for low-G and long duration setback acceleration applications such as shoulder-fired munitions, terrain shaped munitions, missiles, and rockets, particularly small and low power reserve batteries. The proposed concepts must eliminate the need for onboard power sources and sensory and processing devices for firing event detection. The proposed concepts must be capable of being readily integrated into reserve batteries. The proposed innovative inertial initiator concepts must be capable of being produced at relatively low cost and must provide reliability on the order of 99.9% with a 95% confidence level. It must also enable a shelf life of over 20 years. The proposed innovative inertial initiator concepts must be capable of being designed for activation at as low as 10-20 G shock loading magnitudes with 100-150 millisecond duration, while being capable of withstanding up to 5,000 G (preferably higher) accidental shock loading with 1 millisecond (preferably longer) duration. Scalability of the proposed innovative inertial initiators to various reserve battery sizes is highly desirable. The designs selected to proceed to phase II need to have a 20 year shelf-life, operation across the entire military temperature range (-55C to 125C), and the ability to withstand accidental shock loading up to 20,000 Gs with 1 millisecond duration.

Phase I: Design novel inertia-based miniature initiator concepts for reserve batteries and initiation trains for applications such as shoulder-fired munitions, terrain shaping munitions, missiles, and rockets, which are subjected to relatively low G but long duration setback accelerations but must be protected from high-G but short duration accidental accelerations. Develop analytical models of the dynamics of the inertial mechanisms of the proposed initiator concepts for determining the feasibility of each developed concept and simulate its performance under various firing and accidental drops conditions and for optimal selection of their various design parameters.

Phase II: For the selected reserve batteries, develop prototypes of the best igniter concepts developed during phase I, and perform laboratory tests demonstrating their capabilities. Prepare plans for phase III of the project, including identification of the demonstrator round, prototype design, integration, and test plans (progressing from air gun testing to live-fire testing), and design for manufacturing.

Phase III Dual Use Applications: The prototype technology will be demonstrated initially for PM-CCS, PdD Combat Armaments and Protection Systems to showcase successful non-electrical initiation capability. The proposer, along with the Armaments Center proponents, will engage with JPEO A&A and PEO M&S, and their prime contractors, to integrate the non-electrical initiation system into a broader range of munitions.

References:

Mamahan, W., “RDECOM Power & Energy IPT Thermal Battery Workshop – Overview, Findings, and Recommendations,” Redstone Arsenal, U.S. Army, Huntsville, AL, April 30 (2004).;
Cooper, P. W., "Explosives Engineering," Wiley-VCH, New York, NY, 1996.;
Klapötke, T. M., "Chemistry of High-Energy Materials, 2nd Edition," Walter de Gruyter GmbH & Co., Berlin, 2012.;
Federoff, B. T., "Encyclopedia of Explosives and Related Items," U.S. Army ARDEC, Picatinny Arsenal, NJ, 1960.
Agrawal, J. P., "High Energy Materials: Propellants, Explosives, and Pyrotechnics," Wiley-VCH, Weinheim, 2010.

Keywords: Activation mechanisms, passive, miniaturize

A22B-T004 Multi-Phase Blast Munition

RT&L Focus Area(s): General Warfighting Requirements

Technology Area(s): Weapons

Objective: To develop and demonstrate the next-generation of multi-phase blast munitions by taking advantage of the synergistic integration of high-explosives and reactive materials to provide battlefield superiority through increased lethality.

Description: The US Army is developing new munitions that require more space for electronics, sensors, and rocket motors in order to increase range and accuracy. As a result, these munitions have less room for payload and lethal mechanisms while still requiring the same performance or in some cases, increased performance. There are several Long Range Precision Fires (LRPF) projects on-going that require significantly longer range munitions, particularly in the 155mm size (XM1113 & XM1155). These munitions will have notably smaller payload volumes and therefore decreased lethality unless new warhead technologies are implemented in these systems.

The Army is interested in developing the next-generation of blast munitions that will provide overmatch capabilities on the battlefield, in line with Army Modernization Priorities. The introduction of metals into explosive formulations constitutes the basis of thermobaric munitions and provides the baseline for blast performance. The addition of aluminum or other metals to high explosives (HEs) enables in increase in the overall detonation temperatures, provides an improvement of Gurney energy output and significantly enhances the overall blast performance compared to HEs alone. Based on the type of munition, further improvement of performance can be obtained by the incorporation of reactive materials (RM) in the surrounding casings of HE charges. The benefits of this type of configuration are numerous, and include an ease of incorporation of these RM liners into existing systems, along with the ability to maintain munition design specifications while improving performance. Since this approach does not require the requalification of HEs, the replacement of inert casing materials with RM liners offers an easier path to transition the technology into fielded systems. Another benefit of this approach is the ability to produce blast performance attributes beyond simple metallized explosives. While the metal content of HE formulations is limited, an RM liner can easily supply a larger mass of the metal additive, thus enhancing blast performance.

Further changes in the integration of both HE and RM within a munition has led to a variety of novel, high-energy blast explosive configurations. Although these innovative combinations of HEs and RMs provide enhanced blast effects, scaling effects still need to be demonstrated. Independent of configuration, the performance of blast munitions is currently limited by the incomplete combustion of the metal additives, either within the HE formulations or as part of RM liners. Beyond variation of HE-RM configurations, the next level of lethality will rely upon the intimate understanding of the kinetic and thermodynamic interactions between high explosive energetic releases and RM combustion events. Accordingly, understanding the relationship between HE detonation pressure and temperature on the ignition and propagation attributes of RMs holds the potential to increase the efficiency of metal and metal-based formulations.

This topic leverages Army’s on-going Advanced Warheads Technology (AWT) and Advanced Propulsion & Explosives (APEX) projects.

Phase I: Develop correlations between coupled HE and RM performance attributes through experimental testing of RM formulations of interest, provided to the Army for quantification of energy release and overall blast performance.

Phase II: Further develop and optimize the HE-RM synergistic interactions established in Phase I using thermodynamic analysis to achieve the optimal combinations of energy release properties. Scale up the manufacturing process and produce prototypes in at least three (3) configurations of interest to the Army and deliver five (5) prototypes from each configuration to the Army. Conduct field tests to demonstrate performance.

Phase III Dual Use Applications: Transition the developed materials and related technology to a major manufacturer for incorporation of this technology into next-generation munitions for the Long Range Precision Fires (LRPF), Next Generation Combat Vehicle (NGCV), & Air and Missile Defense (AMD) Cross Functional Teams (CFTs). To further exploit the benefits of the developed technology, form partnerships with other manufacturers for applications within civilian sectors, such as the oil and construction industries. This technology can also be leveraged for mining applications and applications related to underwater blasting and demolition, breaking log jams, breaking ice jams, initiating avalanches, timber or tree cutting, the perforation of arctic sea-ice or permafrost, glacier blasting, ice breaking, etc.

References:

Klapötke, T.M. Chemistry of High-Energy Materials, 2nd ed., Walter de Gruyter & Co.: Berlin, 2012. 257 pp. ISBN 978-311027358-8.;
Yen, N.H., Wang, L.Y., Reactive Metals in Explosives, Propellants, Explosives and Pyrotechnics 2012, 37(2), 143-155.;

Peiris, S.M. Enhancing Energy in Future Conventional Munitions using Reactive Materials, AIP Conference Proceedings 1979, 020002 (2018).;
R. Zaharieva and S. Hanagud, “Preliminary Design of Multifunctional Structural-Energetic Materials for High Density, High Strength and Release of High Enthalpic Energy,” Inter. J. of Sci. Eng. and Tech, vol. 3, pp. 1189–1192, 2014.;
DoD Joint Enhance Munitions Technology Program (JEMTP)

Keywords: High explosive, reactive materials, multi-phase blast, combustion efficiency, blast munitions, detonation pressure, detonation temperature

A22B-T005 Metal Injection Molding for Improved Tungsten Fragmentation Warheads

RT&L Focus Area(s): General Warfighting Requirements

Technology Area(s): Weapons, Materials

Objective: Investigate and demonstrate tungsten medium caliber fragmentation warheads made with Metal Injection Molding (MIM) for improved performance and reduced cost.

Description: Tungsten is being used to improve the lethality of warheads due to its higher density. Because it is difficult to machine, tungsten powder is being pressed and sintered into preformed fragments, and then cast into warheads using a resin or metal matrix. There are many steps and there is significant labor involved, resulting in much higher costs for the increase in performance.

Injection molding is one of the lowest cost manufacturing processes due to the very high throughput and consistency. Metal injection molding utilizes the same process to injection mold metal powders with a resin binder into small complex parts which can then be debinded to remove the resin and sintered into a solid metal part. These steps are largely automated in batch or conveyor processes. It is most cost effective for making small, complex, difficult to machine parts with high cost materials in large quantities. MIM could be utilized to make tungsten medium caliber warheads with internal features to optimize fragmentation for increased performance at a lower cost than other methods.

One technical challenge is the possible need for a pusher plate to contain the explosive reaction as the warhead expands, to optimize the transfer of the energy into the fragments instead of between them. Forming the fragment body with the pusher plate into a monolithic structure could provide an additional cost and performance improvement.

Phase I: During Phase I, MIM tungsten samples will be procured to perform feasibility testing. Testing will determine if MIM tungsten has the physical properties to properly fragment, if a pusher plate is required to achieve the desired performance, or if MIM tungsten is inappropriate for this application. Test results and further material analysis of the MIM tungsten will drive initial design work for a MIM tungsten warhead to be fabricated in Phase II.

Based on test results, material evaluation, Picatinny's ability to load warheads, and upcoming programs which may be leveraged, a warhead will be selected for MIM tungsten prototyping (most likely 40mm grenade, 30mm autocannon, or smaller).

Also during Phase I, existing DOTC contractors will be prepared to support Phase II of the effort. Work on forming the fragmentation body with the pusher plate may start if DOTC work orders are prepared in time.

Phase II: During phase II, the contractor will fabricate warhead prototypes in accordance with government specifications. The government will load and perform static detonation testing to evaluate performance. The government will optimize designs for a full-up round. In parallel, the contractor will investigate forming the fragmentation body with the pusher plate.

Phase III Dual Use Applications: During Phase III, contractors will fabricate optimized warhead prototypes. The government will load and perform static detonation testing to confirm performance improvements. The government will then integrate the warheads into full up rounds for live fire testing. Work on forming the fragmentation body with the pusher plate may continue in this phase.

A business study will be performed to evaluate the cost and performance enhancements of transitioning the technology.

References:

An overview of the Metal Injection Moulding process; Powder Injection Molding International; https://www.pim-international.com/metal-injection-molding/an-overview-of-the-metal-injection-moulding-process/;
A Mathematical Model of Penetration of Chunky Projectiles in a Gelatin Tissue Simulant, Larry M Sturdivan, ARCSL-TR-78055; https://apps.dtic.mil/sti/pdfs/ADA063525.pdf;
Metal Injection Molding of Tungsten Heavy Alloys: SBIR Phase I, Gary M Allen, MTL TR 91-37; https://apps.dtic.mil/sti/pdfs/ADA242742.pdf;
Enhanced Fragmentation Modeling, Peter Rottinger; https://apps.dtic.mil/sti/pdfs/ADA504428.pdf

Keywords: Tungsten, Fragment, Warhead, Medium Caliber, Metal Injection Molding, MIM

A22B-T006 Limited-view/sparse-angle computed tomography software for efficient CT reconstruction

RT&L Focus Area(s): General Warfighting Requirements

Technology Area(s): Sensors

Objective: Limited-view/sparse-angle CT software reducing time/dose required for 3D reconstruction compared to the filtered back projection. Reconstruction quality within industry standards & compatibility with image parameters for X-radiography & neutron radiography.

Description: The Armaments Center’s Radiography Laboratory is used to determine in a nondestructive way a product’s actual internal construction and composition as compared to the specification with which its construction parameters were set. The results of this nondestructive evaluation are then used to confirm a product’s quality and integrity (safety, lethality, ruggedness and survivability), and to verify claims of operational limits and prepare assets for reliable field operations.

Computed Tomography (CT) is a computational method in nondestructive evaluation that produces a 3D reconstruction from a series of 2D images. To produce a CT, the item under inspection is placed between an X-ray source and detector. The object (or in some cases the source-detector pair) is rotated for a series of image acquisitions at varying angles. The collected images are supplied to software that uses one of several mathematical methods to convert the 2D images into a 3D reconstruction. In the context of nondestructive testing, X-rays and neutrons are most commonly used in the context of industrial manufacturing.

Filtered back projection (FBP) is the most common method for CT reconstruction. This method produces accurate 3D reconstructions using minimal computing power at the cost of increased projections. In medical imaging, the Hounsfield scale is used to measure a material’s opacity to X-ray radiation, where a higher value indicates more opacity. Muscle tissue has a Hounsfield unit (HU) value of 10-40 HU, whereas steel has a value of 20,000 HU. An FBP CT of industrial manufactured parts could require from several hundred to thousands of projections, necessitating acquisition times on the order of tens of minutes (usually 15-45 minutes.). For this reason, CT is restricted to R&D environments and is only used as a last resort in production processes. CT data provides complete knowledge of the position of relevant indications within a manufactured part. In the medical field, faster acquisition times are desired to reduce the dose delivered to a patient while industry is driven not by dose but by acquisition times while maintaining stringent requirements for contrast and resolution. Limited-view CT promises a reduced overall time by minimizing X-ray time at the cost of modestly increasing computing time. Current advances in CT algorithms make such a reconstruction method possible. The literature indicates limited view CT is a developing method that has successfully been applied case by case.

Certain items possess density gradients that make them inaccessible to X-rays, demanding interrogation by neutrons. Limited-view CT can be particularly helpful in neutron radiography, where acquisition time per image can be considerably longer than X-rays. In addition to our current x-ray CT capability, our laboratory is on schedule to gain an in-house neutron radiography capability in a few years, and this installation will most likely evolve into a neutron radiography CT capability. Since no off-the-shelf software package allows for reliable, limited-view CT reconstruction, this project aims to produce the first such package for use with items relevant to the Army and apply it to both X-ray CT and neutron radiography CT.

Phase I: Develop the mathematical and software methods for limited-view/sparse-angle CT. The possibility of a vast reduction in image acquisition requirements while maintaining sufficient image quality should be theoretically established.

Phase II: Develop and demonstrate prototype limited-view/sparse-angle CT software that successfully reconstructs an item of sufficient complexity while meeting quality and acquisition objectives.

Phase III Dual Use Applications: The US Army can use this system for faster X-ray CTs and more robust neutron radiography CTs. Industry could use this system to increase speed of nondestructive evaluation, increasing total production. This system could also be used in the medical field for high-fidelity CTs of patients while delivering minimal X-ray doses.

References:

Hu, Z., Gao, J., Zhang, N. et al. An improved statistical iterative algorithm for sparse-view and limited-angle CT image reconstruction. Sci Rep 7, 10747 (2017);
G.A. Jones, P. Huthwaite. Limited view X-ray tomography for dimensional measurements. NDT & E International, Volume 93 Pages 98-109, ISSN 0963-8695 (2018);

Hu, Z. et al. Image reconstruction from few-view CT data by gradient-domain dictionary learning. J Xray Sci Technol 24, 627–638 (2016);
Freeman, Timothy. The Mathematics of Medical Imaging: A Beginner’s Guide. Springer Texts in Mathematics and Technology 2nd Edition (2015)

Keywords: Nondestructive Evaluation (NDE); Computed Tomography (CT); Limited-View/Sparse-Angle CT; X-Ray; Neutron Radiography (NR); CT Reconstruction

A22B-T007 Chip-scale directed energy with single-mode laser beam combining

RT&L Focus Area(s): Microelectronics, Directed Energy

Technology Area(s): Electronics, Weapons

Objective: To create chip-scale directed energy microsystems that perform beam combining of single mode lasers with high beam quality and high brightness output.

Description: Edge-emitting laser diodes bars have reached power levels of kilowatts with only centimeter width and several millimeter lengths [1, 2]. However, vertical cavity surface emitting lasers (VCSELs) hold potential for higher beam quality and higher brightness. Wall-plug efficiencies for both regimes exceed 50% - a level needed to power scale systems to directed energy levels for miniaturization and thermal management considerations. How one can coherently beam combine diode lasers has been a long-standing Holy Grail for direct diode kilowatt systems for decades, starting full bore in the late 1990s [2]. Some success has been achieved by use of Talbot cavities to coherently combine edge emitting arrays [2, 3] as well as VCSEL arrays [4, 5]. However, to create high beam quality outputs, the individual emitters must be single mode (transverse single-lobed spatial profile), which requires a small cross-sectional area. VCSELs have been developed using oxide apertures to control the spatial mode; however, they also cause significant heating, limiting the performance and even becoming unreliable and detrimental below 3 micron diameters. Vertical cavity lasers are sought to overcome this bottleneck by removing this oxide barrier, the thermal insulator inherent to the poor high power performance [6]. In addition, monolithic beam combining cavities are sought to fully miniaturize coherent beam combining and produce high brightness. Alternative approaches that couple in-plane lasers that can be beam combined, either spectrally (called wavelength beam combining) or coherently could be relevant here – depending on the coupling efficiency and thermal management considerations. Particular concerns are related to thermo-optic refractive index effects causing loss of coherence across the chip. Regardless, chip-scale directed energy systems should be pursued toward higher brightness, higher power levels for next generation DOD systems. The key considerations include low coupling loss of the individual lasers to the chip (diode or fiber lasers can be considered), thermal management related to heat concentration on the chip or adjoining it, and the means of beam combining to attain a high beam quality output. The preferable approach is to explore having the lasers and the beam combining all on one chip. The coupling between the lasers and the beam combining part of the system is likely a key part of the desired investigation. Both the minimization of loss going from the laser to combining section and the way light is coupled to the other lasers will likely need intensive study. This will need explained and depends on the proposed architecture.

Phase I: Pursue chip-scale directed energy beam combining techniques using high efficiency diode or fiber lasers (exceeding 50% wall-plug efficiency each with 0.9-2.1 micron wavelengths that are oxide-free (at least near the active region) to enable high power operation, with high reliability. Design coherent beam combining architecture for either vertical cavity arrays or in-plane laser beam combining. Use of monolithic cavities or chip-scale solutions should be pursued both to demonstrate minimal footprint and show a path toward combining larger numbers of lasers. Additional design considerations should be investigated for the incorporation of effective liquid cooling of arrays to pursue maximum power achievable.

Brightness levels of 1000 MW/cm2*sr should be shown to be feasible along with power scaling to > 100 W/cm2 – without coherent combining, but to show thermal heat dissipation design considerations. A demonstration of coherent combining of arrays at multi-Watt levels (uncooled peak power) from 10 or more individual lasers that shows promise to proceed to phase II. Specifically, based upon phase I results, commercialization potential for arrays with increased brightness and high beam quality should be assessed with a particular eye toward fiber laser pump diodes and free-space laser communications – along with the eventual goal of higher power level directed energy applications. (If edge coupling to the chip is used, approaches that minimize size, weight, and power are most highly desired, i.e. toward fully monolithic chip-scale systems).

Phase II: Continue implementation of beam combining designs. Pursue 100 Watt peak power, uncooled coherently combined arrays and designs for higher power, cooled arrays. Brightness levels of 1000 MW/cm2*sr should be demonstrated that achieve combining efficiencies of 80% or more for the chip-scale architecture.

Optimization of the arrays and studies on minimal spacing between individual lasers for the nominal power target level and within the beam combining architecture should continue along with needed studies to explore power scaling with larger arrays. Demonstration of chip-scale systems that achieve > 100 W peak power with designs that can scale to over a KW. An assessment of cooling for the array to achieve continuous wave operation should be made toward phase III demonstrations. Eventually, cooled arrays of > 100 W/cm2 average power are desired.

Phase III Dual Use Applications: Pursue further optimization of array cooling and power scaling with refined chip designs. In addition, multi-stage architectures should be pursued to combine lower power arrays to achieve kW power level output. Monolithic cavities should be pursued for at least the first stage of combining with secondary combining by either external cavities or secondary monolithic cavities. Interfacing of the arrays with fiber lasers for effective pumping to multi-kW levels are sought for development. Other consideration to utilize techniques to create lower power arrays (still multi-Watt) for LIDAR, free-space laser communications, and beam scanning and surveillance LIDAR should be made. Particular consideration for phased arrays should be considered for beam steering and adaptive optical beam control to mitigate atmospheric turbulence to achieve maximum power on target.

References:

M. T. Knapczyk; J. H. Jacob; H. Eppich; A. K. Chin; K. D. Lang; J. T. Vignati; R. H. Chin, “70% efficient near 1kW single 1-cm laser-diode bar at 20°C,” Proc. SPIE, vol. 7918, 2011;
PILOT diode beam combining program, U.S. Congress 1998-2003.;

R. Liu, Y. Liu, Y. Braiman, “Coherent beam combining of high power broad area laser diode array with a closed-V-shape external Talbot cavity,” Optics Express, Vol. 18, No. 7, 29 March 2010.;
J.-F. Seurin, G. Xu, Q. Wang, B. Guo, R. Van Leeuwen, A. Miglo, P. Pradhan, J. D. Wynn, V. Khalfin, C. Ghosh, “High brightness pump sources using 2D VCSEL arrays,” Proc. of SPIE Vol. 7615, Vertical-Cavity Surface-Emitting Lasers XIV, 76150F (2010); doi: 10.1117/12.842492.;
D. Zhou, J.-F. Seurin, G. Xu, P. Zhao, B. Xu, et al, “Progress on high-power high brightness VCSELs and applications,” Proc. SPIE Vol. 9381, Vertical-Cavity Surface-Emitting Lasers XIX,9 3810B (4 March 2015); doi: 10.1117/12/2080145.;
J. Leshin, M. Li, J. Beadsworth, X. Yang, Y. Zhang, F. Tucker, L. Eifert, and D.G. Deppe , "Lithographic VCSEL array multimode and single mode sources for sensing and 3D imaging," Image Sensing Technologies: Materials, Devices, Systems, and Applications III, Proc. of SPIE Vol. 9854, 2016; doi: 10.1117/12.2222911.

Keywords: Directed energy, Integrated photonics, laser diode, coherent beam combining, beam forming

A22B-T008 Rapid Optimization and Trade Space Framework for Adapting Aero-Structures

RT&L Focus Area(s): Autonomy

Technology Area(s): Air Platform

Objective: Design, develop, and demonstrate a rapid aero-structural assessment framework for finding the optimal three dimensional solution of the design trades associated with adaptation, material performance, mass, and energy cost.

Description: Army air vehicles are designed as a compromise among the optimal configurations for the various expected missions in which they will perform. Most air vehicles cannot structurally adapt to various mission segments, unlike biological analogs, such as insects or birds [Reich; Lentink; Rosen]. Ideally, platforms could adapt to achieve the optimal configuration for each segment of the mission, e.g. configurations in which the vehicle has high maneuverability and endurance, and is collapsible/foldable for storage. Fluid dynamics simulations and experiments demonstrate that vehicle shape changes enable improvements in aerodynamic performance; however, these efforts typically do not consider structural complexity, cost, and material stiffness/strength with the associated trades [Faber; Vocke; Vale].

The goal is to create an assessment framework for platform adaptation that incorporates the given structural and aerodynamic conditions for an Army relevant problem. An example mission could be a small UAS that is capable of deploying from a collapsed configuration, dashing, and then loitering on station all the while adapting itself to perform optimally in each segment. The tool is expected to inform the required material properties of the morphing structure, for example: specific stiffness, strength, and activation energies. The work will also need to include consideration of the fluid structure interaction (FSI) [Barcelos; Gursul], which typically requires large amounts of computational power and is not viable for optimization without the use of novel uncoupling schemes [Scholten; White]. An effort will need to be made to reduce the computational time by use of similar parallelization or uncoupling schemes to explore the design space and optimize on a complex three dimensional structure. The framework will need to show that it can assess a FSI problem and return the best solution and trades with an aerodynamic and structural accuracy of at least 90% compared to other computational methods. Use of unlicensed or free-license software by the framework is desirable as it adds to the potential parallelization by not requiring multiple licenses to be purchased and maintained.

The framework will need to focus on the assessment of adaptation in terms of the potential benefit to mission performance. Instead of static boundary conditions representing one state, the framework would need to accept two or more potential mission states (e.g. dashing, loitering, etc.) for which an internally consistent best structural solution can be found. Finally, the mission performance improvement would need to be weighed against the design trades associated with the weight and energy required for adaptation. The framework would likely determine the requirements of stimulus sensitive materials [Mabe; Jayasankar] and actuation across various Army relevant vehicle size scales and applications. At a minimum, the framework should be demonstrated against three different Army use cases and compared with a baseline representing a non-adapting configuration that is a compromise of the optimal configurations for each mission or mission segment.

If successful, this effort would enable new tools for the Future Vertical Lift Army modernization priority by computing design trades and solutions for penetration through congested environments via extended maneuverability and range with respect to existing platforms.

Phase I: Design, develop, and validate an assessment framework that demonstrates the ability to rapidly simulate the design space of and perform trades on performance, mass, and other characteristics associated with a relevant Army aero-structure and mission. As an example, teams might consider a Class 1-2 UAS capable of adapting shape from a stowed configuration to perform a mission at low altitude within a congested environment. It is expected that teams will consult with the government in order to determine an appropriately bounded problem. Individual simulations should handle relatively large deformations associated with low-mass solutions. The framework should utilize computational techniques which reduce the typical computational time (100-1000x) associated with three dimensional coupled fluid structure interactions, such as parallelization. The goal of phase 1 is to demonstrate an ability to interrogate the trade space associated with bounds on a FSI problem to find the optimal design. The simulation should have an accuracy compared to slower analyses of at least 90%.

Further, define the complete proof-of-concept optimization and trade space framework that will be developed in Phase 2, including a technically viable path for including potential adaptations. Adaptation technologies include stimulus sensitive materials, actuators, etc., which are internally consistent within the structure for different mission segments (dash, maneuver, endurance, etc.) but provide increased aerodynamic performance, for example, by modifying camber or span to increase lift. Typically there will be a point in design where mission segments need to be sufficiently numerous or different in order for adaptation to be viable, which should be computable in Phase 2.

Phase II: Design, develop, and validate an assessment framework that demonstrates the ability to rapidly simulate the design space of and perform trades on performance, mass, and energy associated with structural adaptation cost. In addition to the accuracy requirements of the Phase 1 effort, the framework should be able to identify which potential structural adaptations are viable for given mission requirements defined as structural and aerodynamic bounds. Assessment across mission requirements will need to be consistent internally for structural performance computation. The framework should also address user competency and likelihood of accurate solution generation.

Phase III Dual Use Applications: Currently, the Army relies on researcher experience to experimentally assess vehicle designs and determine the viability of the concept. Maturity of the rapid optimization and trade space framework will allow Army engineers to determine the trade space associated with various basic science technologies developed in academia, industry, and research institutions. A vehicle that is able to adapt itself can respond optimally to Soldier needs; this tool will be able to accept mission requirements and provide technical trades and solutions. For example, a mission space may require a UAS to be Soldier- or air vehicle-borne, penetrate a congested space, and then loiter on station for an extended time. The end state of the framework would provide a tool for rapid assessment of the technology required to construct a vehicle that is fully collapsible, is able to shorten its planform to maneuver through forests or trees undetected, and then lengthen its planform to loiter at extended duration.

References:

Reich G and Sanders B, Introduction to Morphing Aircraft Research. Journal of Aircraft 2007, 44(4): 1049-1059.;
Lentink D et al., How Swifts Control Their Glide Performance With Morphing Wings. Nature 2007, 446(7139): 1082-1085.;
Rosen M and Hedenstrom A, Gliding Flight in a JackDaw: A Wind Tunnel Study. Journal of Experimental Biology 2001, 204(6): 1153-1166.;
Faber JA, Arrieta AF, and Studart AR, Bioinspired Spring Origami. Science 2018, 359(6382): 1386-1391.;
Vocke III RD et al., Development and Testing of a Span-Extending Morphing Wing. Journal of Intelligent Material Systems and Structures 2011, 22(9): 879-890.;

Vale J et al., Aero-Structural Optimization and Performance Evaluation of a Morphing Wing with Variable Span and Camber. Journal of Intelligent Material Systems and Structures 2011; 22(10): 1057-1073.;
Barcelos M, Bavestrello H, and Maute K, A Schur-Newton-Krylov Solver For Steady-State Aeroelastic Analysis and Design Sensitivity Analysis. Computer Methods in Applied Mechanics and Engineering 2006, 195(17-18): 2050-2069.;
Gursul I, Cleaver D, and Wang Z, Control of Low Reynolds Number Flows by Means of Fluid-Structure Interactions. Progress in Aerospace Sciences 2014, 64: 17-55.;
Scholten W and Hartl DJ, An Uncoupled Method for Fluid-Structure Interaction Analysis with Application to Aerostructural Design. AIAA Scitech Forum 2020, 1635.;
White T et al., Uncoupled Method for Massively Parallelizable 3D Fluid-Structure Interaction Analysis and Design. AIAA Aviation Forum 2020.;
Mabe J, Variable Area Jet Nozzle for Noise Reduction Using Shape Memory Alloy Actuators. Journal of Acoustical Society of America 2008, 123(5): 3871.;
Jayasankar et al., Smart Aerodynamic Surface for a Typical Military Aircraft Using Shape Memory Elements. Journal of Aircraft 2011, 48(6): 1968-1977.

Keywords: Unmanned aerial system, UAS, fluid structure interaction, optimization, morphing vehicle, adaptive structure

A22B-T009 Solid Oxide Fuel Cell CPOX Reforming of Biogas

RT&L Focus Area(s): General Warfighting Requirements

Technology Area(s): Materials

Objective: Demonstrate Catalytic Partial Oxidation of time varying gaseous hydrocarbon fuels.

Description: To meet the Army’s energy sustainability strategy goals, power sources that can utilize alternative fuels are needed. The goal is to improve our use of energy assets by optimizing use of available energy resources. Solid Oxide Fuel Cells (SOFC) have the potential to provide this power from a wide variety of fuels including complex hydrocarbons, which are generally not amenable for use with other fuel cell technologies. However, current SOFC systems are optimized for a single fuel and are generally not fuel flexible. A small scale, 1kW fuel cell operating on, or augmented with, bio-generated gas would provide additional capability and reduced supply chain dependence. Critical to development of a fieldable power system is a robust catalytic partial oxidation (CPOX) fuel processor capable of converting biogas to solid oxide fuel cell reactants (hydrogen and carbon monoxide) without additional process water. The fuel processor must be capable of operating over wide ranges of bio-gas composition with operating conditions being optimized on the fly will demonstrate on of the critical technologies to enable fuel flexibility.

Phase I: Design, construct, and evaluate component and subscale CPOX assemblies using time varying gaseous fuels to include methane, propane, and biogas. These results should support the potential to develop a system capable of less than 30 minute start times with varying hydrocarbon fuels. Provide a detailed conceptual design of a CPOX assembly capable for providing syngas for a 1-3 kW power system, with a start-up time less than 20 minutes a volume below 150 cm3/kW, a weight less than 1 kg/kW, cyclic durability in excess of 100 cycles, and a design capable of withstanding MIL-SPEC-810 vibration levels. based upon the results generated in this effort.

Phase II: In phase II, based on the results from the successful phase I program, design, construct, and evaluate a full scale brass-board CPOX system capable for providing syngas for a 1-3kW SOFC system using time varying gaseous fuels from 100% methane, propane, and biogas. CPOX should be capable of start-up within 15 minutes, have a volume below 100 cm3/kW and a weight less than 0.5 kg/kW, cyclic durability in excess of 2000 cycles, and a design capable of withstanding MIL-SPEC-810 vibration levels.

Phase III Dual Use Applications: Robust SOFC power systems with dynamic fuel flexibility will significantly impact both military and commercial applications, accelerating product development, particularly for lightweight portable power devices and domestic use.. Because the market and the number of devices in the commercial sector is much larger than the military market, widespread usage of this technology will drive down the cost of devices for the military. Demonstrate achievements from the SBIR effort to show applicability to field conditions and compatibility with biogas. Likely sources of funding if the phase III program if successful include: CERDEC, PEO Soldier and PEO Combat Support and Combat Service Support Product Manager Mobile Electric Power Systems.

References:

Multi-Fuel Capability of Solid Oxide Fuel Cells; K. Sasaki, K. Watanabe, K. Shiosaki, K. Susuki & Y. Teraoka, Journal of Electroceramics, volume 13, pages 669-675(2004).;
Solid Oxide Fuel Cell as a Mutli-fuel Applicable Power Generation Device; R. Kikuchi, K. Eguchi, Journal of the Japanese Petroleum Institute, 47 (4), 225-238 (2004).;
Fuel Flexibility: A Key Challenge for SOFC Technology; M. Lo Faro, V. Antonucci, P.I. Antonucci, A. C. Arico, Fuel, 102, 554-559 (2012)

Keywords: SOFC, CPOX, fuel flexibility, multifuel

A22B-T010 Agile Machine Learning in Dynamic Environments for Complex Event Processing

RT&L Focus Area(s): Artificial Intelligence/Machine Learning

Technology Area(s): Information Systems

Objective: Develop a system to detect and classify complex events that can be quickly retrained for different operating environments using sparse training data by leveraging human domain expertise.

Description: Effective network command, control, communications and intelligence in MDO environments requires situational understanding across multiple domains in order to achieve overmatch against the adversary. In the fight against a peer adversary, it is anticipated that such overmatch will require short decision cycles in the order of minutes or less. To this end, fully autonomous solutions are needed to ingest sensor data and contextual information across the battlespace to provide actionable recommendations to the decision maker. Today, automated solutions for target detection and classification are beginning to appear to be possible across the cyber and various physical (land, air, sea, space) domains. However, intelligence analysts would still be needed to interpret these warnings and indicators to correlate the observed movements of various entities across domains into coordinated adversarial tactics, techniques, and procedures (TTPs). Such coordination represents a sequence of atomic activities across fairly large scales of time and space and broadly speaking fall under the guise of complex events in the data science literature [1]. For instance, the amalgamation of many coordinated atomic loitering and movement activities of vehicles and dismounts can represent a single red force reconnaissance complex event. It is desirable for automated systems to report as many true complex events as possible while limiting the number of unique false events reported per an extended interval of time, e.g., hours.

Deep learning methods have successfully classified simple activities that span short time intervals and are localized such as sports and daily activities [2-3]. However, deep learning has yet to provide satisfactory solutions for complex event processing [4]. Furthermore, the rapidly changing and unpredictable MDO environment means that limited data will be available for training, and thus, it is expected that a purely end-to-end deep learning solution would be inadequate. Recently, it has been demonstrated that human domain expertise can be combined with deep learning to recognize complex events [5] and that neuro-symbolic machine learning can adapt data-driven machine learning to recognize atomic concepts without explicit labels using limited data with only the complex events labeled [6-7]. While these results are promising, the complex event processing methods have yet to be developed and evaluated for recognition of existing and emerging TTPs in the MDO setting.

The goal of this topic is to advance and demonstrate the state of complex event processing systems to enable reliable classification over a large set of possible TTPs that span over various domains. To this end the performer will need (1) define a set of relevant complex events that can capture the richness and variability of possible workflows for each event, (2) collect data for such complex events across multiple domains in a variety of operational environments (e.g., weather conditions, operational tempos, etc.), (3) develop complex event processing solutions that incorporate both domain expertise and data-driven learning, and (4) demonstrate classification performance over the complex event processing solution. For the purposes of feasibility, it is expected that the data collection will fully leverage synthetic data generation technologies for at least phases I and II.

Phase I: Define at least three complex events that entail data collected from one domain. Each complex event must entail at least three atomic activities separated in time by the order of minutes and in space such that the field of view of a single sensor is unable to detect the event. The data collection should represent at least two different operating environments and contain background atomic activities that are not correlated to any of the three complex events. The complex event classification systems should be trained over large amounts of data for one operating condition, and then adapted for the second operating condition using a significantly smaller fraction of training data. Overall, the complex event classification system should exhibit a probability of detection of at least 0.9 with a false report rate of one per hour. Furthermore, the probability of correct classification should exceed 0.9 for the full trained operating condition while still achieving a probability of correct classification of 0.8 for the adapted operating condition.

Phase II: Define at least ten complex events that entail data collected from two or more domains. Each complex event must entail at least ten atomic activities and at least one complex event must exhibit a timespan of one hour. Furthermore, five of the complex events must be separated in space such that more than three spatially disparate sensors are required to detect these events. The data collection should represent at least three different operating environments and contain background atomic activities that are not correlated to any of the three complex events, but much of the background activities must be correlated to normal civilian activities such as commuting to work, running errands, etc. The complex event classification systems should be trained over large amounts of data for one operating condition, and then adapted for the two other operating condition using a significantly smaller fraction of training data. Overall, the complex event classification system should exhibit a probability of detection of at least 0.9 with a false report rate of one per hour. Furthermore, the probability of correct classification should exceed 0.9 for the fully trained operating condition while still achieving a probability of correct classification of 0.8 for the adapted operating conditions.

Phase III Dual Use Applications: The complex event processing system should be able to allow domain experts to quickly define adversarial TTPs across any domain and the system should be able to train over modest amounts of labeled data. Such technology should benefit the civilian sector by enabling law enforcement to detect and classify emerging complex events by foreign and domestic terrorist groups using open source signals collected over social media as well as monitoring attacks of various infrastructure systems in the cyber domain.

References:

Flouris, I., Giatrakos, N., Deligiannakis, A., Garofalakis, M., Kamp, M., & Mock, M. "Issues in complex event processing: Status and prospects in the big data era." Journal of Systems and Software 127 (2017): 217-236.;
Wu, Z., Wang, X., Jiang, Y. G., Ye, H., & Xue, X. "Modeling spatial-temporal clues in a hybrid deep learning framework for video classification." In Proceedings of the 23rd ACM international conference on Multimedia, pp. 461-470. 2015.;
Herath, S., Harandi, M., & Porikli, F.. "Going deeper into action recognition: A survey." Image and vision computing 60 (2017): 4-21.;
Alevizos, E., Skarlatidis, A., Artikis, A., & Paliouras, G. "Probabilistic complex event recognition: A survey." ACM Computing Surveys (CSUR) 50, no. 5 (2017): 1-31.;
Liu, X., Ghosh, P., Ulutan, O., Manjunath, B. S., Chan, K., & Govindan, R. "Caesar: cross-camera complex activity recognition." In Proceedings of the 17th Conference on Embedded Networked Sensor Systems, pp. 232-244. 2019.;
Xing, T., Garcia, L., Vilamala, M. R., Cerutti, F., Kaplan, L., Preece, A., & Srivastava, M. "Neuroplex: Learning to detect complex events in sensor networks through knowledge injection." In Proceedings of the 18th Conference on Embedded Networked Sensor Systems, pp. 489-502. 2020.;
Vilamala M.R., Xing T., Taylor H., Garcia L., Srivastava M., Kaplan L. Preece A., Kimmig A., Cerutti F. Using DeepProbLog to perform Complex Event Processing on an Audio Stream. In Proceedings of the Tenth International Workshop on Statistical Relational AI (https://arxiv.org/abs/2110.08090). 2021.

Keywords: artificial intelligence, machine learning, complex event processing, situational understanding, classification, detection

A22B-T011 High-Temperature, Low-Voltage Operation Avalanche Photodetectors (APD) in the Extended Short Wavelength Bands

RT&L Focus Area(s): Quantum Sciences

Technology Area(s): Electronics

Objective: Develop and demonstrate high-sensitivity at near-room-temperature avalanche photodetector (APD) that operates at low voltage with high gain in the extended short-wave infrared (e-SWIR) spectrum range of 2 to 2.5 µm.

Description: Photodetectors with high sensitivity operating in high-temperature, low-voltage regime in the e-SWIR spectrum range of ~ 2 to 2.5 µm are in high demand [1,2]. A number of approaches have been explored in the recent years in pursue of this goal, but the current performance metrics do not yet meet the stringent requirements for the desired applications. The Army is seeking innovative approaches in next-generation e-SWIR detector technology to significantly improve sensitivity and response time. These innovations include, but are not limited to, novel structures to achieve low-voltage operation and low-dark current APDs covering e-SWIR band for image sensing and communication systems with small size, weight, power and cost (SWaP-C) requirements.

A range of APD technologies have been developed in the past and even achieved single photon sensitivity, which explains why the APD is preferred for many applications. However, there are still many application constraints, such as cost, power consumption, reliability, robustness of operating environment and response time. Silicon APD based photoreceivers have state-of-the-art noise-equivalent-power of 40 fW/rt(Hz) with a bandwidth of 140 MHz and proven performance in various applications. However, at wavelengths beyond 1.1 µm, silicon becomes transparent to infrared light. Commercially available III-V APDs (e.g. InGaAs APDs) at 1.55 µm applicable for fiber communications [3-4] cannot be used in applications beyond 1.7 µm. Standard APDs with spectral responsivity to 2 µm and beyond show increased dark current and excess noise factor, which limit the gain and hence the signal-to-noise ratio (SNR) of the detection system [5]. In addition, many of these standard technologies (e.g. HgCdTe APDs) are not viable for many field applications due to their need for cryogenic cooling, resulting in high SWaP-C.

Furthermore, conventional APDs apply a variable reverse-bias voltage across the device junction to create a variable avalanche gain during APD operation, which in turn optimizes the sensitivity of the receiver. However, to achieve satisfactory levels of avalanche gain, many APDs require high reverse-bias voltages in the 40V to 60V range, and some require voltages exceeding 80V [6]. In addition, the APD avalanche gain depends on temperature and varies with the manufacturing process. Thus, for typical systems in which the APD must operate at constant gain, the high-voltage bias must vary to compensate for the temperature effects. To achieve constant gain in a typical APD supply, the temperature coefficient must be maintained at approximately +0.2%/°C, which corresponds to 100mV/°C. The latter makes the device energy consumption inefficient and incompatible with current CMOS IC technology supply voltages, requiring additional high bias circuit in the read-out.

It is highly desirable to design a next-generation APD for e-SWIR photoreceivers to overcome the deficiencies of the standard APD available today. Novel APD solutions are desired that simultaneously enable low-voltage (e.g. <20V) data-preserve-html-node="true" APD operations, reduce dark current, and exhibit low excess noise factor to achieve high gain and enhanced SNR at or near room temperature. Novel APDs technologies focused on structure design, providing high bandwidth, high gain and high quantum efficiency, are sought rather than based on material composition changes.

Phase I: Develop a novel APD device structure with material(s) system enabling detection in extended-SWIR spectral range (2-2.5 µm). Theoretically model and simulate APD design, operating at e-SWIR wavelength that is scalable from single element to arrays, e.g. VGA format and beyond. Design, model and simulate essential electrical and optical characteristics for an APD device that meets the performance requirements for low-voltage operation, low excess noise and low dark-current at or near room temperature. A maximum gain is needed at low biasing voltage (e.g. <20V), data-preserve-html-node="true" with low dark current density of a few nA/cm2 at unity gain at or near room temperature. Deliver the simulation and design results.

Phase II: Fabricate, evaluate and optimize a prototype of single element APD as well as an APD array of 4 x 4 elements or larger. Demonstrate low-voltage biased APD operation on single element devices. Demonstrate spectral cut-off wavelengths at e-SWIR wavelength bands as high as 2.5 µm. Explore option(s) for readout integration and processing e-SWIR APD. Demonstrate functionality and mechanical integrity over the military temperature range and background-limited infrared photo-response against calibrated illumination. A proof of concept FPA is desirable, but not required.

Phase III Dual Use Applications: Demonstrate APD array integrated into a system for field testing. APD arrays with extended sensitivity to the e-SWIR range are desirable for identifying, tracking, and targeting hostile forces and communicating covertly in applications such as micro air vehicle (MAV) sensors, laser target tracking, laser radar, missile tracking, persistent surveillance and 3D imaging, satellite imaging and interceptors. The detector arrays are also expected to enable measurement and characterization of transient phenomena that have an e-SWIR spectral content, such as a missile signature, flashes, or measuring and characterizing unknown emission signatures in the battlefield. In addition, the commercialization of this technology is expected to provide low cost, high performance imagers for potential uses in variety of commercial applications including automobile, security and surveillance, medical imaging, machine vision, agriculture, scientific imaging including astronomy, mapping, weather monitoring, as well as border patrol and various homeland security applications.

References:

Michael A. Krainak, Xiaoli Sun, Guangning Yang, and Wei Lu, “Comparison of linear-mode avalanche photodiode lidar receivers for use at one-micron wavelength”, SPIE 7681-34, 2010;
Xiaogang Bai, Ping Yuan, etc.; “GHz low noise short wavelength infrared (SWIR) photoreceivers” Proc. SPIE Laser Radar Technology and Applications XVI, 803717-1 (2011).;
Achyut. K. Dutta, M. Takechi, R. S. Virk, M. Kobayashi, K. Araki, K. Sato, M. Gentrup, and R. Ragle, IEEE J. Lightwave Technology, 20, pp. 2229-2238(2002).;
Achyut K. Dutta, Editors: “WDM Technology: Active Optical Components”, Vol. I, Academic Press, Boston, 2005.;
R.J. McIntyre, 1966, “Multiplication noise in uniform avalanche photodiodes,” IEEE Trans. Electron Devices, ED-13:164.R.J. McIntyre, 1999, “A new look at impact ionization – Part I: A theory of gain, noise, breakdown probability and frequency response,” IEEE Trans Electron Devices 46: 1623.;
Maxim Integrated, “Low-Noise APD Bias Circuit,” Application Note 1831, 07 Jan, 2003.

Keywords: Avalanche Photodiode, APD, multi-color, detectors, extended SWIR, e-SWIR, bias voltage, noise factor, ROIC, sensors, FPA, multispectral sensor; LADAR; High Bandwidth; Dark current, Laser Radar, Imaging, bio-sensing

A22B-T012 High-Fidelity Design Tools for Electromagnetic Scattering Over Hypersonic Vehicles

RT&L Focus Area(s): Hypersonics

Technology Area(s): Weapons

Objective: To develop new mathematical constructs and high-fidelity design tools to predict time-accurate electromagnetic signatures of morphing hypersonic vehicles.

Description: The Army is interested in designing next-generation hypersonic flight vehicles with enhanced system speed, reach, and lethality addressing Army’s and DoD’s Priorities in Long Range Precision Fires and Hypersonics. Revolutionary systems must meet new tactical requirements for performance, reach, and lethality, while simultaneously mitigating the strong electromagnetic signatures emitted. New concepts will include the ability of controlling hypersonic vehicle performance and maneuverability based on morphing structures in external and internal aerothermodynamics by time-varying the angle of attack (AOA). The presence of an AOA results in significant differences of the surface temperatures as well as in emissions of electromagnetic characteristics in intensity and spectral band. Historically, computational fluid dynamics has played a central role in the design and development of hypersonic vehicles, largely due to the prohibitive cost associated with testing facilities. However, existing simulation approaches are limited in its ability to predict hypersonic aerothermodynamics and its interactions solving complex fluid, thermal, kinetic, and structural problems using tightly-coupled approaches. Hypersonic modeling under realistic flight conditions is complicated by the nonlinearity and multiphysics nature present that acts across a wide range of scales [1-2]. Variations in atmospheric conditions, chemical kinetics, vibrational excitation, ablation products, and gas-surface interactions further complicate the high enthalpy plasma system [3]. The Army is therefore seeking high-fidelity design approaches to predict the flight environment of a hypersonic vehicle, along with gas-flow chemistry, shock induced heating, and material-response, including thermoacoustics transport, and full-spectrum EM propagation capabilities. Solutions will include novel capabilities for modeling time-varying morphing structures coupled with aerothermochemistry and electromagnetic wave propagation. Electromagnetic frequency ranges of interest include X-band, Ka-band, and also IR/RF. In solving the system of PDEs, the solution must also include accurate physics-based closures for processes including turbulent shear stress and heat transfer fluxes, particle laden flows, and chemical kinetics for any unresolved physics. This research will lead to new solutions to PDEs with faster and greater accuracy. The new tools should be able to handle realistic glide body, missile geometries, and scramjet propulsion systems for sustained powered flight in the Mach 6 to 20 range. Tools must have the ability to be deployed in traditional/emerging high performance computing architectures (CPU GPU) efficiently and demonstrate improved scalability over the state-of-the-art. In-situ visualization and data extraction techniques must be available to provide end users the ability to seamlessly navigate the sea of data encountered in real-time analysis.

Phase I: Develop 3D high-fidelity modeling concepts to predict aero-thermal effects and EM signatures that include both RF/IR signature responses for morphing vehicles and adaptive structures and demonstrate benefits over low fidelity approaches. High fidelity approaches for reacting turbulence and fluid structure interaction should be based on LES and finite rate chemical kinetics. The company should identify strengths/weaknesses associated with alternative solutions, methods, and new concepts. Demonstrate theoretical credibility of proposed computational and include EM experimental validation targets. Computational vetting and demonstration of concepts to be conducted using canonical blunt-nose single or double cone hypersonic shapes and beyond is suitable in this phase.

Phase II: During Phase-II, the framework developed in Phase-I will be extended and validated to support hypersonic morphing vehicles for potential applications in air-breathing missiles, boost-glide missiles, and high-maneuver interceptors with EM signature analysis. Tools should demonstrate ability to model complex aerothermochemistry, thermoacoustics, shock induced heating, structural material response, and broad spectrum EM propagations (e.g., X-band, K-band, IR./RF), using high-fidelity LES approaches. The tools will capture in detail non-equilibrium processes including boundary layer transition to turbulence, onset of material ablation, finite-rate non-equilibrium chemistry, and gas-surface interactions responsible for surface deformation. It shall consider material dielectric properties including RF permittivity, absorptance, reflectance and thermal conductivity. Demonstrate time-accurate predictions based on tightly-coupled fluid structure interaction for time-varying AOA in morphing internal and external hypersonic vehicles. Complete model, executable code, and deploy on state-of-the-art high performance computing systems with demonstrable performance on existing or emerging computing architectures.

Demonstrate model validation by comparison with reference DNS databases, EM experimentation in the open literature, or data from the Army or DoD laboratories. The high-fidelity model should demonstrate at least 10% improved accuracy in capturing transients over existing approaches based on RANS or empirical correlations. The complete software package shall be available to ARL during all phases of the project to conduct independent assessment and vetting of the developed tools. Coordinate development efforts with the government, and potential prime-contractor partners, to ensure product relevance and compatibility with missile defense projects and government modeling and simulation systems. The developed complete computational tool sets along with user guide(s) at the end of Phase-II shall be delivered to ARL for government use on HPC platforms to conduct mission projects.

Phase III Dual Use Applications: Collaborate with simulation model developer(s) and/or user(s) on integration of product(s) into a missile defense application. Optimize toolset to accommodate new advances in the technology of tracking and prediction of glide body or cruise missile flight. Transition the technology to an appropriate government or defense contractor for integration and testing. Integrate and validate the functional signature tools into a real-world missile defense application.

References:

Candler, G.V., “Rate effects in hypersonic flows”, Annual Review of Fluid Mechanics, vol. 51, pp. 379-402, 2019.;
D’Ambrosio, D., Giordano, D., “Electromagnetic Fluid Dynamics for Aerospace Applications”, Journal of Thermophysics and Heat Transfer, vol. 21 (2), 2007.;
Bisek, N. J., Boyd, I.D., Poggie, J., "Numerical Study of Plasma-Assisted Aerodynamic Control for Hypersonic Vehicles", AIAA J. Spacecraft and Rockets, vol. 46 (3), 2009

Keywords: Hypersonics, aerothermochemistry, morphing systems, computational fluid dynamics

A22B-T013 Mapping Strain in Composite Materials using Terahertz Metamaterials

RT&L Focus Area(s): Microelectronics

Technology Area(s): Electronics

Objective: Design and demonstrate a methodology to detect and map regions of incipient failure in opaque composite materials using terahertz metamaterial laminates whose polarimetric response is sensitive to local strain.

Description: Military platforms are increasingly composed of composite materials because they are lighter and less expensive than metals, but their failure is more difficult to predict or detect. It is often the case that regions of high strain go undetected before catastrophic failure, so a means to detect these incipient failures is of critical importance. Recently, a promising solution to this challenge has been proposed [1,2]: metamaterial laminates with a strain-dependent polarimetric response [3,4] may be adhered onto or embedded within a composite, and their polarimetric response may be spectroscopically probed in transmission or reflection geometries. Spatially mapping the polarimetric signature of the metamaterial laminate will reveal the local strain fields within the composite, which will be permanently recorded if the metamaterials break under sufficient stress. Indeed, metamaterial arrays or layers of metamaterial laminates may be designed with different threshold stress responses, so that the amount of strain historically experienced by the composite may be recovered and spatially mapped, thus revealing regions of incipient failure. For other applications which require dynamic monitoring of evolving composite strain fields in real time, self-healing deformable metamaterials are of interest because they can record current levels of strain while reversibly returning to an unstrained signature when the stress is released. Metamaterials operating within the terahertz spectral region (0.1-3 THz) provide a nearly optimal compromise of spatial resolution and material penetration depth in a manner that depends on the unique properties of the composite host. Application of these terahertz metamaterials for non-destructive testing could become a transformative approach to maintenance that will enable longer operating times for systems beyond the current conservative maintenance schedules, increase operational readiness, and at the same time increase safety and confidence.

Phase I: Design and quantitatively assess the synergistic electromagnetic and mechanical performance of a terahertz metamaterial laminates adhered onto or embedded within an opaque composite host, whose polarimetric response is sensitive to the local strain and may be mapped in reflection (preferable) or transmission geometries. Of interest are two types of metamaterials, those with permanently severable break junctions for quantitatively recovering the amount of strain experienced historically, and those that are reversibly deformable for quantitatively recovering the amount of strain currently experienced by the composite. The objective is to demonstrate the feasibility of the concept through a detailed design of both the polarimetric metamaterial laminates and the instrument that will rapidly map the locally-sensed strain fields between 0.1 - 5%. The design must include a quantitative estimate of the achievable spatial resolution (must be less than 5 mm) and strain sensitivity (within 10% of actual strain) for a variety of opaque host materials of practical interest for military platforms.

Phase II: Construct, demonstrate, and deliver the sensor design and exemplar composites containing strain-dependent terahertz metamaterial laminates designed in Phase I. Opaque hosts must be at least 1000 square centimeters in size, and the strain mapping, preferably in a reflection geometry, must be accomplished in less than an hour. The spatial resolution (must be less than 5 mm) and strain sensitivity (within 10% of actual strain) must be demonstrated and quantitatively assessed as a function of at least three opaque host materials in order to ascertain the universality of the technique. Of particular interest is the mapping of strain field extrema, both for historical strain fields using break junction metamaterials and for current strain fields using reversibly deformable metamaterials, spanning the range between 0.1 - 5% for metamaterial laminates adhered onto or embedded within composite material hosts of specific military interest.

Phase III Dual Use Applications: These metamaterials will enable the development of a laminate that can be added to any composite material to provide a fast, low cost, high resolution non-destructive test capability using a compact hand-held sensor. It will find military application via industrial fabrication capability applied to most military vehicle and aircraft programs of record. Adoption by industry will be stimulated by the advantages for commercial vehicles, aircraft, and composite structures. This technology will significantly reduce operating cost, life-cycle costs, and accident costs.

References:

H.O. Everitt et al., “Strain Sensing with Metamaterial Composites”, Adv. Opt. Mat., DOI:10.1002/adom.201801397 (2019).;
A.A. Zadeh et al., “Enlightening force chains: a review of photoelasticimetry in granular matter”, arXiv:1902.11213, (2019).;
J. Li et al., “Mechanically tunable terahertz metamaterials”, Appl. Phys. Lett. 102, p. 121101 (2013).;
Khatib et al. , "Mapping active strain using terahertz metamaterial laminates", APL Photonics 6, 116105 (2021).

Keywords: Strain mapping, metamaterial, terahertz, composite material

A22B-T014 Terahertz Radar-on-Chip

RT&L Focus Area(s): Autonomy

Technology Area(s): Electronics

Objective: To develop low cost radar-on-chip operating at the terahertz frequencies with millimeter range resolution and low power consumption based on integrated circuit technologies.

Description: The terahertz part of the electromagnetic spectrum from 0.3 to 1 THz has unique advantages for radar applications, including large bandwidths for improving range resolution and small antenna apertures [1]. It will enable new radar systems for autonomous navigation, security surveillance and screening, biometric vital sign detection, human-machine interfaces, and much more. Prototype THz radar systems mostly using GaAs Schottky diode technology have shown impressive results. However, they are bulky and expensive, and mostly limited to laboratory demonstrations.

The aggressive scaling of CMOS integrated circuit (IC) technology driven by Moore’s Law has resulted in miniaturization of computational devices. On the analog side, the transistor cutoff frequency fmax has increased steadily to ~350 GHz for 45 nm CMOS nodes [2][3]. However, further scaled nodes (< 45 nm) has not seen more improvement because of increased gate and wiring resistances. In the meantime, SiGe HBT technology has emerged as a viable solution in the THz band with commercial SiGe HBT technology achieving 500 GHz fmax, and 700-GHz fmax for the next technology node. SiGe HBT technology is enabling fundamentally operated circuits above 300 GHz. Furthermore, the speed of SiGe HBT devices is projected to continue to improve with transistor scaling. Theoretical analysis of the performance limits of SiGe HBTs indicates that their operating frequencies should reach 1 THz and beyond.

On the system side, these advances have enabled the commercialization of various millimeter-wave systems such as automotive radars. Building on low power RF-CMOS technology, low cost single-chip collision avoidance radars at 77 GHz have become widely available [4]. Besides offering high range resolution, they also include multiple transmitters and receivers in a single-chip form factor that can be electronically configured into coherent beam forming mode for long range detection or MIMO (multiple-input, multiple-output) radar mode for enhanced angular resolution.

Based on the above developments, the use of silicon based IC technologies for single-chip THz radars at frequencies greater than 300 GHz is also promising and feasible [5]. The large bandwidth available at the THz frequencies will provide range resolution down to millimeter range that would be impossible to achieve with microwave and millimeter-wave radar systems, and potentially enable new applications such as high-precision secure perimeter tracking and remote gesture recognition [6]. However, past research has shown that systems operating at the THz frequencies cannot be a simple scaling of classic RF design techniques to the higher frequencies because the new operating frequencies are close to or higher than the device fmax. Novel circuit architectures will be required to overcome the device limitations. This STTR topic will explore innovative circuit design techniques in order to enable THz radar-on-chip.

Phase I: Identify IC technology nodes with device characteristics suitable for terahertz frequency operation. The technologies being considered could be silicon-based (CMOS or SiGe), III-V based (GaN or InP), or heterogeneous integration of different technologies. Perform device characterization and modeling of the IC technology nodes. Develop radar system parameters and perform trade study between system size, architecture, operating frequency, antenna structure, range, power consumption, etc. Develop overall system-level models based on optimized parameters selected from the trade study. Design initial circuits implement against the identified technology nodes and develop initial antenna design for the radar system. The radar system should contain 1 transmitter and 1 receiver, and has the following targeted system parameters: >300 GHz, 2% instantaneous bandwidth, 0 dbm TX power, 15 dB RX noise figure, -70 dBc/Hz phase noise at 1 MHz offset. Phase I study should determine the feasibility of developing a THz radar-on-chip.

Phase II: Perform detailed circuit design and IC fabrication against the foundry technology nodes chosen in Phase I. The targeted system parameters should include the following: >300 GHz, 10% instantaneous bandwidth, 3 transmitters (5 dBm TX power each) and 4 receivers (10 dB RX noise figure) in a single chip, -90 dBc/Hz phase noise at 1 MHz offset. Explore use of the spread spectrum modulation code waveforms in addition to convention frequency-modulated continuous wave (FMCW). The detection range should be >100m (or maximum achievable range within the power and noise constraints of the overall system) and range resolution ~1 mm. The IC design should include option to allow multiple chips to operate in parallel and synchronously to improve detection range and angle resolution. Fabricate the ICs through a multi-project wafers service within the STTR budget constraint. Construct a prototype radar system based on the ICs and demonstrate its performance.

Phase III Dual Use Applications: It is expected that THz radar-on-chip will enable a wide range of radar applications including autonomous navigation, security surveillance and screening, biometric vital sign detection, human-machine interfaces, and much more. Low cost of terahertz radar-on-chip ICs will be a key enabler for these applications.

References:

K.B. Cooper, “THz Imaging Radar for Standoff Personnel Screening,” IEEE Transactions on Terahertz Science and Technology, Vol. 1, No. 1, pp. 169-182, September, 2011.;
P. Hillger et al, “Terahertz Imaging and Sensing Applications With Silicon-Based Technologies,” IEEE Transactions on Terahertz Science and Technology, Vol. 9, No. 1, pp. 1-19, January, 2019.;
K. Sengupta et al, “Terahertz integrated electronic and hybrid electronic–photonic systems,” Nature Electronics, Vol. 1, pp. 622-635.;
http://www.ti.com/sensors/mmwave/overview.html;
J. Grzyb et al, “A 210–270-GHz Circularly Polarized FMCW Radar With a Single-Lens-Coupled SiGe HBT Chip,” IEEE Transactions on Terahertz Science and Technology, Vol. 6, No. 6, pp. 771-783, November, 2016.;

J. Lien et al, “Soli: ubiquitous gesture sensing with millimeter wave radar,” ACM Transactions on Graphics, Vol. 35, No. 4, Article 142, July 2016.

Keywords: Radar, sub-millimeter wave, terahertz, integrated circuits, CMOS, SiGe, GaN, InP, MIMO, autonomous navigation, human-machine interface

A22B-T015 Canine VO2Max Measurement System

RT&L Focus Area(s): Biotechnology

Technology Area(s): Bio Medical

Objective: Develop a canine respiratory mask system capable of reliably measuring VO2Max in Military Working Dogs in treadmill-based exercise studies.

Description: Military Working Dogs (MWDs) have proven to be a vital component in the execution of warfighter missions. The optimization of an MWD’s ability to perform at very high levels for long durations and to process the operational environment under high levels of stress and distraction will significantly improve their operational effectiveness and recovery. Aerobic potency is a critical component of overall performance and is improved through canine conditioning. Improved aerobic potency leads to enhanced cardiovascular and respiratory capacity to help increase work capacity and overall performance. Measurement of VO2Max is a non-invasive way to measure fitness and cardiovascular health and track improvements over time. Currently there are no reliable canine systems that capable of measuring VO2Max in Military Working Dogs. The goal of this topic is to develop a canine VO2Max measurement system addressing the following requirements:

Provides a complete seal so reliable measurements can be made
Able to be used in MWDs in treadmill-based exercise studies
End users able to use during routine conduction of fitness evaluations

Research conducted under this topic must comply with Federal and Department of Defense Regulations, and Public Law (in particular, Animal Welfare Act 4 and amendments) regarding the treatment of dogs.

Phase I: Design an appropriate canine respiratory mask system capable of reliably measuring VO2Max that will meet the requirements outlined above. Threshold and objective quantitative health requirements including physiological, anatomical and behavioral will be defined after consulting with both military and commercial sources. Provide a detailed description of the operation of the system and mechanism of air sampling to support reliable measurements from a complete seal. Identify components and/or develop technical specifications for components that, when integrated, will meet the performance goals. Conduct necessary calculations on the design and performance of the components to demonstrate the feasibility and practicality of the proposed Canine VO2Max Measurement System. Demonstrate a prototype system or primary components of a prototype system at TRL 3+.

Phase II: Optimize and construct working prototypes at TRL 4-5 as designed in Phase I to meet or exceed stated objectives. Conduct laboratory tests to validate all specifications. Conduct field tests if appropriate. Develop final product specification documents that include a list of all system components and their requirements and instructions for deployment and stowage. In addition, an investigation of potential alternative applications should be conducted in conjunction with a market assessment.

Phase III Dual Use Applications: Any materials and technology developed under this project could be incorporated for use in other applications for MWDs. Proposed system could be introduced into the civilian marketplace for use in canine conditioning studies and other research. The system would also be applicable to federal, state and local law enforcement agencies that utilize working dogs.

References:

Bansel HE, Sidesl RH, Ruby BC, and Bayly WM (2007). Effects of endurance training on VO2max and submaximal blood lactate concentrations of untrained sled dogs. Equine Comp Exer Physiol 4: 89-94;
Seeherman HJ, Taylor CR, Maloiy GMO and Armstrong RB (1981). Design of the mammalian respiratory system. II. Measuring maximum aerobic capacity. Respiratory Physiology 44: 11–23;

Lucas A, Therminarias A and Tanche M (1980). Maximum oxygen consumption in dogs during muscular exercise and cold exposure. Pflugers Archive 388: 83–87.;
Katz LM, Bayly WM, Roeder MJ, Kingston JK and Hines MT (2000). Effects of training on maximum oxygen consumption of ponies. American Journal of Veterinary Research 61: 986–991.;
Alves J, Santos A, Brites P, Ferreira-Dias G. Evaluation of physical fitness in police dogs using an incremental exercise test. Comp Exerc Physiol. 2012;8:219–26.;
Steiss J, Ahmad HA, Cooper P, Ledford C. Physiologic responses in healthy Labrador Retrievers during field tidal training and competition. J Vet Intern Med. 2004;18:147–51;

Lee HS, Lee SH, Kim JW, Lee YS, Lee BC, Oh HJ, et al. Development of novel continuous and interval exercise programs by applying the FITTVP principle in dogs. Sci World J. 2020;3029591:1–9.;
Moraes VS, Soares JKI, Cabidelli JF, Fadini ANB, Ribeiro PA, Pinheiro RM, et al. Effects of resistance training on electrocardiographic and blood parameters of police dogs. Comp Exerc Physiol. 2017;13: 217–26.;

Nye CJ, Musulin SE, Hanel RM, Mariani CL. Evaluation of the Lactate Plus monitor for plasma lactate concentration measurement in dogs. J Vet Emerg Crit Care. 2017;27:66–70.;
Santos POPR, Santos EA, Reis AC, Santos AMMR, Kuster MCC, Trivilin LO, et al. Effect of exercise on cardiovascular parameters in search and rescue-trained dogs. Arq Bras Med Vet Zootec. 2018;70:1036–44.

Keywords: Military Working Dog, Canine Conditioning, Canine Physiology, Canine VO2Max

A22B-T016 Explainable AI for Complex Decision Making for Command and Control in MDO

RT&L Focus Area(s): Artificial Intelligence/Machine Learning

Technology Area(s): Information Systems

Objective: Develop Explainable AI (XAI) middle layer to adequately explain and develop novel AIs for complex reasoning for Command and Control (C2) decision aids for Multi-Domain Operation (MDO) wargaming.

Description: Artificial intelligence (AI) is fundamental to realizing the full potential of Multi-Domain Operations (MDO) in the future joint force (TRADOC TP 525-3-1, 2018). The U.S. Army must develop and leverage AI solutions to account for the complexity and scale of dynamic MDO against a variety of adversarial threats. AI-enabled systems can create and exploit potential windows of superiority through deliberate planning, convergence, and synchronization of effects (MCoE, 2021). However, AI-enabled systems resemble black boxes that mysteriously convert incoming data to predicted outcomes. The need for explainable AI (XAI) is especially critical for military domain analysts and command staff decision makers who must rely on the AI-generated recommendations for neutralizing emerging kinetic and non-kinetic threats. AI system-produced learning models and resulting predictions must be both understandable and appropriately trusted by the human decision makers using the system. Outcomes of the system should resonate with decision makers’ own expertise and intuitions (tacit knowledge) as well as integrate and enhance the cognitive and psychological factors that contribute to theories of complex adaptive decision-making and interdisciplinary approaches to complex reasoning.

An XAI middle layer opens the black box by communicating the internal representations, processes, predictions, and surprises to human decision makers in an understandable and trust-building manner supporting effective human-AI collaborative decision-making. The process to increase the explainability of complex decision-making often involves directly or implicitly enumerating all key possible outcomes that come as a consequence of a particular choice. In the past, this enumeration step often involved speculation and extrapolation built upon a combination of historical pattern analysis and human experience. The decision-maker's level of understanding of the predictions was in part determined by the information presented, and upon the resonance or dissonance of that information with the decision-maker's own experiences and intuitions. Today, both simulation science and data science have augmented the outcome prediction step. Although the use of mathematical and statistical predictors based upon a combination of first-principle modeling and data-driven science is now ubiquitous and has often replaced human intuition as the generator of possible future outcomes, how the decision-maker engages with these analytical processes has not changed—it remains predicated on understanding the complex decision. As AI-enabled systems and tools move to the forefront of options used by today’s decision-makers to create data-driven outcome predictions, it is important to develop novel XAI approaches.

The XAI middle layer will interface with a variety of U.S. Army AI applications to enable fully interactive analysis, exploration, and development of the AI algorithms through multimodal interfaces to the tacit knowledge, decision, and action spaces characteristic of C2 battlespace platforms. The XAI middle layer will generate new decision-making representations on available visualization ecologies or augment existing battlespace representations with additional XAI information. Development of novel interactive visualization and advanced interrogation approaches to XAI interfaces will play an important role in enabling overall understanding and development of the AI reasoning towards explainability.

Phase I: Develop a conceptual design for a XAI middle layer utilizing the following: inputs about game states, AI sensing, and AI actionable choices for one or more AI-predicted future states, and an initial capability to integrate with associated 2D/3D C2 display representations (e.g. Battlespace Visualization and Interaction, BVI). The conceptualization should combine the above elements into a workflow for use in a human-AI team decision-making context with simplified geospatial battlespace capabilities, so that the human understands how the AI’s assumptions and predictions drive its decision suggestions, and so that the AI can leverage human choice behavior and tacit reasoning to learn to produce better predictions in complex decision-making. Proposers are encouraged to build on top of DARPA XAI outcomes, leveraging previous DoD investment in that program (https://xaitk.org, https://onlinelibrary.wiley.com/toc/26895595/2021/2/4). Deliverables include a report or presentation demonstrating the conceptual design and a path forward for Phase II.

Phase II: Develop and demonstrate a proof-of-concept prototype system based on the preliminary design from Phase 1. The prototype should display the AI models’ perceived current states and anticipated future states of friendly and hostile units, and demonstrate a moderate-depth (2 to 4 sequential choices) decision tree for simplified MDO scenarios for complex decision-making for one or more of the following: game theory, meta-reasoning, and deception. Proposers are encouraged to use ARL’s AI testbeds and their associated 2D and 3D resources (https://github.com/USArmyResearchLab/ARL_Battlespace is an ARL wargaming AI testbed that is transitioning to a new testbed Simple Yeho, a 1024x1024 3D grid environment and API for an NGCV scenario with multiple layers for foliage, roads, and visibility, and their associated uncertainties, that is being developed under ARL’s Human Autonomy Teaming ERP), to develop the XAI middle layer and demonstrate integration with the underlying AI and AI development. Examples of AI predictions and AI-guided choice behaviors will be provided for XAI development. Developers who choose to base on ARL’s API will be provided access to use and modify the AI code from the testbed to generate their own simulations and predictions. Performance metrics will be based on a series of progressively harder problems in terms of the effective depth of the decision guidance (e.g. in terms of progressively increasing the number of factors displayed, the depth of sequentially dependent choices explained, progressively increasing uncertainty in the state observation, and how these relate to human+AI team performance against an AI opponent in a wargame across a variety of mission scenarios), depth of integration with the development of novel AI for complex reasoning, and 3rd party user feedback on the XAI performance (e.g. as measured via NASA TLX).

Phase III Dual Use Applications: Expected outcome is a software product for an XAI middle layer, deployable for a variety of human-AI collaborative complex decision making applications. The path for transition is to mature the prototype developed in Phase 2 by delivering phased incremental improvement until a fully operational XAI middle layer capability is achieved. Work with the government and industry partners to demonstrate the system to user groups in an operational setting. The overall scale goal should address tactical as well as C2. Incorporation of user feedback into the system is important. A real-world implementation analysis should be conducted to establish a process for integrating the prototype XAI middle layer into a program of record. For example, results should demonstrate translation of the XAI from the ARL AI testbed’s grid space to real-world wargaming maps (e.g. One World Terrain), including different terrain and/or environment types, for displaying alternative Courses of Action (COAs). Results should also extend the depth of the decision-making to include multiple factors or units (e.g. 3 or more unit action combinations) and/or sequential choices (5 or more ) or domains (3 or more, one of which should include cyber deception). The new XAI middle layer technology will support Mission Command Battle Lab - Mission Command CDID’s Tacit Reasoning AI development task, in coordination with ARL Futures Division Advancing Concepts Office. It will also support efforts to assess and place Soldiers who are technically fluent and adaptive (e.g. ARI’s T-SAVVY program).

References:

U.S. Army Training and Doctrine Command (TRADOC) Pamphlet 525-3-1 (2018). The U.S. Army in Multi-Domain Operations 2028. Army Publishing Directorate. Fort Belvoir, VA.;
Maneuver Center of Excellence (MCoE). Maneuver Warfighting Function FY21. Science and Technology Priorities. (Presentation Oct 15, 2021).;

Hare JZ, Rinderspacher BC, Kase S, Su S & Hung CP (2021) Battlespace: using AI to understand friendly vs. hostile decision dynamics in MDO. Proc. SPIE 11746, Artificial Intelligence and Machine Learning for Multi-Domain Operations Applications III. 1174615 (12 April 2021); https://doi.org/10.1117/12.2585785.;

Su S, Kase S, Hung C, Hare JZ, Rinderspacher BC & Amburn C (2021) Mixed Reality Visualization of Friendly vs Hostile Decision Dynamics. In: Chen J.Y.C., Fragomeni G. (eds) Virtual, Augmented and Mixed Reality. HCII 2021. Lecture Notes in Computer Science, vol 12770, Springer, Cham. https://link.springer.com/chapter/10.1007/978-3-030-77599-5_37;

The Fourth Paradigm: Data-Intensive Scientic Discovery. Editors: Tony Hey, Kristin MicheleTolle and Stewart Tansley. Publisher: Microsoft Research, 2009.;

Wei Xing, Shireen Y. Elhabian, Vahid Keshavarzzadeh and Robert M. Kirby, \Shared-GP: Learning Interpretable Shared 'Hidden' Structure Across Data Spaces for Design Space Analysis and Exploration", Journal of Mechanical Design, Volume 142, Issue 8, 081707, 2020.;

Shusen Liu, Zhimin Li, Tao Li, Vivek Srikumar, Valerio Pascucci and Peer-Timo Bremer, \NL-IZE: A Perturbation-Driven Visual Interrogation Tool forAnalyzing and Interpreting Natural Language Inference Models", IEEE Transactions on Visualization and Computer Graphics, volume 25, 1, 2019.

Keywords: Mission command, command and control, decision making, explainable AI, wargaming, course of action, game theory, deception

A22B-T017 Thermal Lensing-Free Chalcogenide Windows

RT&L Focus Area(s): Directed Energy

Technology Area(s): Materials

Objective: Design chalcogenide window with a thermo-optic coefficient dn/dT = 0 and a low absorption coefficient at wavelengths near λ=1.064 μm, while remaining optically transparent in the MWIR and LWIR regions.

Description: Recently, chalcogenide optics have been developed with thermo-optic coefficients dn/dT near zero in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) regions [Gleason], where n is the optical index of refraction and T is temperature. Currently, no such materials have been developed that accomplish this in the 1030 nm to 1070 nm, which covers Yb:YAG to Nd:YAG fiber lasers. We believe that the development of such a glass will have no thermal lensing at these wavelengths and thus, a higher damage threshold than chalcogenides currently available. Such optics will have to maintain a low absorption coefficient at 1 micron as well as good optical imaging quality like those chalcogenides currently on the market.

The primary goal of this STTR is to develop methods for manufacturing chalcogenide glasses with optimal thermo-optical properties that can perform in harsh environments. The glass should have a temperature coefficient of refractive index dn/dT = 0 and low absorption coefficient around 1.064 μm (1030-1070 nm), and optical transparency and high transmission in the MWIR and LWIR spectral regions while maintaining good optical imaging quality. The glass should be capable of handling high optical power densities without damage and should not degrade with exposure to light, humidity, etc. Fabrication techniques needed to realize the proposed chalcogenide designs should be clearly defined in the Phase I effort and an optical window manufactured. Such structures should be scalable for optics with a diameter up to 4 inches. It is expected that any such designs will require multiple glass compositions to be manufactured to fine tune to the appropriate composition.

Key findings in Gleason et al. indicate that “trends in refractive index and dn/dT were found to be related to the atomic structure present within the glassy network, as opposed to the atomic percentage of any individual constituent.” Because of this additional degree of freedom, chalcogenide optics can be fabricated based on “compositional design” allowing for on demand glass properties including the thermal – optical response as well as mechanical properties for environmental robustness. Such optics are useful for commercial applications that transmit over the MWIR and LWIR spectral regions. The chalcogenide optics will provide uninterrupted, enhanced force protection and day/night situational awareness. Military applications for this technology include laser safety devices for Mounted/Dismounted Ground System thermal sensors, and for thermal imaging systems on manned aircraft, unmanned aerial vehicles, and unattended ground sensors.

Phase I: Fabricate a chalcogenide glass that has a temperature coefficient of refractive index dn/dT = 0 around 1.064 μm and zero or negative dn/dT in the range 1030-1070 nm. The glass must have transmission greater than 63.5%, in the MWIR and LWIR spectral regions and a low absorption coefficient, less than 0.05/cm, around 1.064 μm. It must also maintain good optical imaging quality in the MWIR and LWIR spectral regions: 3-5 µm and 7-10 µm (ideally up to 14 µm), respectively. Such glass should be capable of handling optical power densities up to 1 MW/cm2 in the range 1030-1070 nm without out damage, enabled by the low absorption coefficient and dn/dT of zero. The glass should be stable over time and not degrade or experience a change of properties with exposure to light, humidity, etc. [Frantz] Environmental specifications include an operating temperature of -40°C to +71°C, storage temperature and temperature shock from -51°C to +71°C, and an operating/storage humidity of -40°C to +71°C and 95% relative humidity (RH). It should be noted that designing such an optic will likely require the fabrication of multiple glass compositions to approach the desired material. The deliverables shall include a detailed design, fabrication plan, and multiple 1-inch diameter optical windows (coupons) with measurement results of the refractive index, absorption coefficient, thermal properties, transmittance and reflection spectra spanning the full spectral range (400 nm through 14 µm), and dn/dT measurements. Coupons should be scalable to 4 inches in diameter. Designs that meet all of the specs, especially the damage threshold and transmission, but not the temperature coefficient of refractive index of zero, will be considered.

Phase II: Fabricate a chalcogenide glass, which meets all the phase 1 requirements, with an improved (higher) damage threshold targeting 10 MW/cm2 by focusing on other parameters (i.e. homogeneity enhancement, precision annealing profiles, reduction of absorption coefficient through different compositions or other methods) that may increase the damage threshold. The absorption coefficient and other parameters should meet phase 1 requirements. Damage testing will be conducted at the U.S. Army Research Laboratory with a 200 µm to 900 µm laser beam spot size. The expected deliverables are a write-up of the results of the fabrication study varying other parameters (and their effect on the various properties) and at least four one-inch chalcogenide windows with the improved damage threshold that meet the specs of phase 2. Such windows should be scalable to four inches in Phase 3. Additionally, potential commercial and military transition partners for a Phase 3 effort shall be identified.

Phase III Dual Use Applications: Chalcogenides such as these can be used in systems which use thermal systems. Potential commercial applications include thermal security cameras for use in Homeland Security applications (perimeter security at airports, coastal ports, nuclear power installations), UAV sensors, as well as satellite sensors. The possibility to incorporate these structures into current sensors could also be explored, for the potential use in both ground vehicles and aircrafts. Additionally, selenide-based chalcogenide glasses are already widely employed in the athermal imaging systems, especially in the low-cost IR system of auto navigation. [Lin] Finally, such optics may be used to increase the thermal stability of SWIR cameras.

References:

B. Gleason, L. Sisken, C. Smith and K. Richardson, "Designing mid-wave infrared (MWIR) thermo-optic coefficient (dn/dT) in chalcogenide glasses," Proc. SPIE 9822, Advanced Optics for Defense Applications: UV through LWIR, 982207 (17 May 2016); https://doi.org/10.1117/12.2229056;
J. Frantz, J. Myers, R. Bekele, C. Spillmann, J. Kolacz, H. Gotjen, V. Nguyen, C. McClain, and J. Sanghera, "Arsenic selenide thin film degradation and its mitigation," Opt. Mater. Express 8, 3659-3665 (2018).;

J. E. McElhenny, "Continuous Wave Laser Induced Damage Threshold of Ge28Sb12Se60 at 1.07 microns," in Frontiers in Optics / Laser Science, OSA Technical Digest (Optical Society of America, 2018), paper JW4A.5.;
J.E. McElhenny, N.K. Bambha, "Continuous wave laser-induced damage threshold of Schott IRG-24, IRG-25, and IRG-26 at 1.07 microns," Proc. SPIE 11173, Laser-induced Damage in Optical Materials 2019, 111731I (20 November 2019); https://doi.org/10.1117/12.2532062;

Gleason, B., Richardson, K., Sisken, L. and Smith, C. (2016), Refractive Index and Thermo‐Optic Coefficients of Ge‐As‐Se Chalcogenide Glasses. Int J Appl Glass Sci, 7: 374-383. doi:10.1111/ijag.12190;
C. Lin, C. Rüssel and S. Dai, “Chalcogenide glass-ceramics: Functional design and crystallization mechanism,” Progress in Materials Science, 93, 1-44 (April 2018).;

B. Gleason, P. Wachtel, J. D. Musgraves, A. Qiao, N. Anheier, K. Richardson, "Compositional-tailoring of optical properties in IR transparent chalcogenide glasses for precision glass molding," Proc. SPIE 8884, Optifab 2013, 888417 (15 October 2013); https://doi.org/10.1117/12.2029215

Keywords: high power, continuous wave, chalcogenide, 1 micron, optics, infrared, visible, high transmission, MWIR (mid wave infrared), LWIR (long wave infrared), absorption coefficient

A22B-T018 Optical Management of Digital Sensor Data using Cryogenic Photonics

RT&L Focus Area(s): Control and Communications, Microelectronics, Network Command

Technology Area(s): Electronics, Information Systems, Materials, Sensors

Objective: Effort seeks to examine and utilize photonic components available today for application in cryogenic environments of high performance infrared sensor arrays.

Description: Data rate demands of high performance Army imaging sensors have historically increased exponentially and are expected to continue doing so. Infrared sensors are being tasked with performing multiple functions simultaneously and at ever increasing pixel counts. Higher frame rates allow for additional applications but come with the cost of increased power usage. Army sensors today currently rely on electrical outputs for data transmission of scene imagery information to downstream electronics. Electrical output lines can only output so much data per channel, and thus the number of output lines have increased dramatically creating additional power consumption. An alternative solution to an impending data management bottleneck is conversion of digital read-out integrated circuit (ROIC) output signals to an optical data stream harnessing commercially matured photonic components. An optical output link ensures that future high performance imaging data rate demands can be easily met and is scalable to match sensor application demands. Additionally, optical data outputs enable flexible system design, are not susceptible to EMI interference, and exhibit excellent energy efficiency.

Optical signal processing has been adopted by datacom and telecom industries to provide enormous data rates with superior energy efficiency to electrical transmission. Modulation and transceiver components have matured significantly but the photonic components that are offered commercially today are typically designed for room temperature application and their performance at the cryogenic temperatures required for the highest performance infrared sensors is undocumented. Furthermore, foundry offerings vary in terms of the types of photonic modulators available, whether components are custom or incorporated into the foundry Process Design Kits (PDKs), their compatibility with mixed signal design elements, and their degree of integration. In order to overcome the engineering challenge of harnessing photonic components, there is a need to document the performance and integration level being offered today so that future programs can reduce the technical risk of converting to optical outputs.

The barrier to making the switch from electronics to photonic interconnects has yet to be overcome. Programs of record for infrared focal plane array (IRFPA) sensors often elect to settle for smaller evolutionary improvements in cryogenic electronic communications, instead of the leap-ahead capabilities available with high-speed, low energy cryogenic photonic links. IRFPA sensor development programs need compelling evidence to fully motivate the transition to this new technology. This project aims to inform Army sensor programs of the most suitable approach for incorporating these optical components. By testing pathways today, we can determine the readiness level of the various foundry offerings moving forward. In addition to a comprehensive study of available offerings, this work will also demonstrate the most suitable optical output link in a laboratory setting using appropriate transmission protocols. This demonstration will be performed at cryogenic temperature and will have a satisfactorily low bit-error rate.

Phase I: In Phase I performers will evaluate potentially feasible schemes to implement optical modulation in a cryogenic environment. In addition to evaluation, performers will begin preliminary work in acquiring hardware and software required for conversion of digital data to optical output link. All solutions must be compatible with current and future read-out integrated circuit technology, including necessary interface transmission protocols, practical signal modulation driving, and compact floorplan of integration. Solution must be suitable for use alongside sensor read-outs used in relevant Army programs. With the goal of maximizing system integration, team will preliminarily assess and design elements based upon viable foundry offerings or epilayer vendor procurement. Evaluation and design in Phase I should not be limited to a single source but should cover the commercial landscape to include all reasonably feasible solutions that can provide error-free performance. Bit error-rates must be lower than 1E-10 with the goal of being equal to or lower than 1E-12. In all cases, energy per bit and total system energy costs should be minimized and data transmission solution scheme must be able to reach modulation efficiency of less than 600 fJ per bit. By the end of Phase I, performers are expected to have comprehensively presented solutions to meet program expectations, began component design, clearly presented on the level of integration and energy usage analysis, provided a detailed test characterization plan, and initiated dialogue with foundry and/or material vendor business departments for acquiring components in Phase II.

Phase II: In Phase II, performers will acquire necessary photonic components from commercial foundries and begin systematic performance testing of various modulation schemes at cryogenic temperatures. Test temperatures must be relevant to high performance infrared sensor arrays. Coupling, insertion, and chip-to-chip losses will be documented alongside component power consumption to better understand system energy budget. On-off keying and tunability at cryogenic temperatures will be fully reported. A comprehensive performance and energy report detailing component results from different foundries will also include realistic configuration analysis of integrating alongside existing ROIC technologies. Development and integration of photonic components should be as monolithic as possible. Following presentation of performance and integration report for all explored foundry and scheme solutions, a single optical modulation scheme will be selected for laboratory demonstration at cryogenic temperature to include bit error rate testing. Demonstration effort should replicate infrared camera system as much as possible.

Phase III Dual Use Applications: This project is expected to significantly mature the engineering and integration challenges of converting digital sensor data to optical data transmission outputs. The findings of this effort will inform future high performance sensor programs on best practices to lower technology risk and give Army sensor programs confidence to implement this revolutionary change to sensor data management moving forward. This project naturally pairs with the highest data demanding sensors with broad applications in surveillance, wide field-of-view sensors, fast-event detection, targeting, and tracking. Near term transition pathways include airborne sensor packages with targeting and tracking requirements, such as Apache and Future Vertical Lift, which would benefit from being operated at higher frame rates than are currently possible. Superior energy efficiency of optical data outputs will also lower dewar cooler assembly energy budget, thus increasing system lifecycle, and appeal to sensor programs with moderate data rates and volume units, such as PM GS and PM TS sensors.

References:

Chakraborty, U., Carolan, J., Clark, G., Bunandar, D., Gilbert, G., Notaros, J., ... & Englund, D. R. (2020). Cryogenic operation of silicon photonic modulators based on the DC Kerr effect. Optica, 7(10), 1385-1390.;
Eltes, F., Villarreal-Garcia, G. E., Caimi, D., Siegwart, H., Gentile, A. A., Hart, A., ... & Abel, S. (2020). An integrated optical modulator operating at cryogenic temperatures. Nature Materials, 19(11), 1164-1168.;

Estrella, S. B., Dorch, T. P., Cooper, T. M., Renner, D. S., & Schow, C. L. (2021, June). Novel Link Architecture Minimizing Thermal Energy Dissipation for Cryogenic Optical Interconnects. In Optical Fiber Communication Conference (pp. F2E-3). Optical Society of America.;
Fard, E. M., Long, C. M., Lentine, A. L., & Norwood, R. A. (2020). Cryogenic C-band wavelength division multiplexing system using an AIM Photonics Foundry process design kit. Optics Express, 28(24), 35651-35662.;

Fu, W., Wu, H., Wua, D., Feng, M., & Deppe, D. (2021). Cryogenic Oxide-VCSEL for PAM-4 Optical Data Transmission over 50 Gb/s at 77 K. IEEE Photonics Technology Letters;
Fu, W., Wang, H. L., Wu, H., Srinivasa, A., Srinivasa, S., Feng, M., & Deppe, D. (2020, September). Cryogenic 50 GHz VCSEL for sub-100 fJ/bit Optical Link. In 2020 IEEE Photonics Conference (IPC) (pp. 1-2). IEEE.;

Gehl, M., Long, C., Trotter, D., Starbuck, A., Pomerene, A., Wright, J. B., ... & DeRose, C. (2017). Operation of high-speed silicon photonic micro-disk modulators at cryogenic temperatures. Optica, 4(3), 374-382.;
Georgas, M., Leu, J., Moss, B., Sun, C., & Stojanović, V. (2011, September). Addressing link-level design tradeoffs for integrated photonic interconnects. In 2011 IEEE Custom Integrated Circuits Conference (CICC) (pp. 1-8). IEEE.;

Johnston, A. R., Liu, D. T. H., Forouhar, S., Lutes, G. F., Maserjian, J. L., & Fossum, E. R. (1993, October). Optical links for cryogenic focal plane array readout. In Infrared Detectors and Instrumentation (Vol. 1946, pp. 375-383). International Society for Optics and Photonics.;
Wright, J. B., Trotter, D. C., Zortman, W. A., Lentine, A. L., Shaner, E. A., Watts, M. R., ... & Peckerar, M. (2012, June). Cryogenic operation of silicon photonic modulators. In Integrated Photonics Research, Silicon and Nanophotonics (pp. IM2A-5). Optical Society of America. Keywords: Sensors, Photonics, Optical Modulators, Digital Read-outs, Cryogenic, Data Transmission

A22B-T019 Synthetic Platform for Device-Agnostic Quantum Dot IR Photodectors

RT&L Focus Area(s): Quantum Sciences, Microelectronics

Technology Area(s): Electronics, Materials, Sensors

Objective: Develop a ‘synthetic platform’ and design rules to produce device-agnostic semiconductor nanocrystal (quantum dot/QD) absorbers for infrared sensors.

Description: Current infrared (IR) sensors typically use epitaxial semiconductors or microbolometers as optoelectronic absorbers. Epitaxial semiconductor sensors achieve high speed and sensitivity, but are expensive and typically operate at cryogenic temperatures. Microbolometer cameras may operate uncooled, but operate only in the long-very long wave IR (LWIR-VLWIR) range with limited sensitivity and speed.

Quantum dots are already widely employed for photonic applications such as LEDs. Using QDs as IR absorbers requires control of the optoelectronic properties (e.g. charge transfer) of QD assemblies, which remain poorly understood [1-7]. Current approaches to QD-based sensors require developing QD materials in parallel with a sensor ‘scaffold’ (e.g. readout integrated circuit/ROIC). Only recently have advances in electronics and materials enabled a commercial IR sensor featuring a QD absorber [7,8].

Improved understanding and control of optoelectronic properties of QD assemblies would allow QDs to be optimized to a chosen sensor design, without the need to develop sensor scaffolds and QD absorbers in parallel. Such ‘device-agnostic’ QDs would be compatible with the variety of QD image sensor designs (e.g. photoconductive, photovoltaic, bulk or low dimensional absorbers…) already in development.

This STTR targets ‘leap-ahead’ innovation to mature QD IR absorber technology as an alternative to microbolometers or epitaxial semiconductors. QD-based IR sensors could enable low-cost, high-speed, lightweight uncooled infrared detectors across the short- to long-wave infrared (SWIR-LWIR) regions. Additionally, QD absorbers could enable uncooled mid-wave IR (MWIR) cameras, a current technology gap [2-5,9,10]. The advantages of QD-based IR detectors compared to current technologies (e.g. microbolometers or epitaxial semiconductors) are a result of quantum confinement phenomena in QDs and simple processing.

Due to quantum confinement effects, QD absorbers may bypass performance-limiting thermal noise issues encountered in bulk semiconductors and operate with little/no cooling. Wavelengths including SWIR-LWIR can be achieved by controlling QD size and composition. As photodetectors, QD devices are capable of high sensitivity and high response speeds compared to microbolometer-based systems [1-5,8].

QDs are prepared in simple liquid suspensions, which may be painted, printed, dropped or spun onto a sensor scaffold such as a ROIC. This processing enables rapid, low-cost synthesis of large volumes of QDs (>1m2 absorber/day for <$1K data-preserve-html-node="true" materials) [3,4,7,8].

A successful synthetic platform for applying QD absorbers in IR cameras will result in improved sensor performance and stability, lower costs and faster development times compared to current technologies. This will require:

identification and understanding of the phenomena determining the final properties of QD-based absorbers,
accurate screening methods to characterize the relevant properties of as-synthesized QDs,
model(s) capable of predicting sensor/absorber performance from QD screening results, and
synthetic protocols and processes to control the QD properties that determine final sensor performance.

The product of this STTR will be a platform to produce QDs designed and optimized based on specifications for a given image sensor. QDs would be compatible with the variety of QD infrared image sensor designs already in development. Further, a single sensor design could be optimized for various wavelengths by choosing the appropriate QD to apply to the basic scaffold.

Phase I: Determine the feasibility of synthesizing device-agnostic QDs for IR absorption. The Phase I deliverable is a report. In the Phase I report the performer should: A) Identify class(es) of QDs of interest (e.g. II-VI, III-V, perovskite…) and relevant QD properties for investigation (e.g. size distribution, surface chemistry, photoluminescence…). Identify synthetic approach(es) for QDs of interest. Identify existing methods and/or propose testing methods to measure the QD properties of interest. B) Identify potential uncooled QD absorber sensor formats of interest and relevant sensor performance metrics for prediction/evaluation (e.g. detectivity, responsivity, stability, quantum efficiency…). Identify existing and/or propose test device(s) to characterize sensor performance metrics. For identified metrics, determine ranges of performance that would be competitive with current industry-standard technologies and allow comparison between QD devices and current uncooled technologies. C) Propose a systematic approach to develop and demonstrate relations between properties identified in A) and performance metrics identified in B).

Phase II: Execute systematic investigations into QD properties and sensor performance outlined in Phase I report. Validate QD characterization methods identified in Phase I. Synthesize and characterize QDs with variable properties of interest (as identified in Phase I). Verify synthetic control of QD properties of interest.

Fabricate and validate test device(s) for sensor characterization identified in Phase I. Apply synthesized QDs to test devices and identify correlations and/or causal relationships between QD properties and final sensor performance.

Based on experimental results, identify the primary QD properties governing final sensor performance. Construct predictive model(s) for relating QD synthesis/QD properties to sensor performance.

Successful Phase II results will clarify basic design rules for QD-absorbers and devices. Phase II deliverables should include design rule(s)/model(s) for predicting and optimizing at least one sensor metric to match or exceed the ‘industry competitive’ range identified in Phase I. Other successful outcomes could include demonstrating design-optimization models for multiple metrics in one sensor design, or one metric in multiple sensor designs. Rules/Models should be accompanied by a ‘library’ of synthetic protocols to control the relevant QD properties.

Phase III Dual Use Applications: The ultimate product of the proposed STTR will be a synthetic platform comprising design rules for QD-based absorbers and a set of synthetic protocols for implementing said design rules. Recent and ongoing developments in sensor scaffolds for QDs have demonstrated and continue to optimize multiple sensor designs. A device-agnostic synthetic platform for QDs, as envisioned here, will enable broad application of QD-based sensors tailored to specific missions. Combining the appropriate sensor scaffold with the optimal QDs accesses a broad design envelope to provide interchangeable ‘plug-and-play’ IR sensors with optimized wavelength, resolution and size, weight, power and cost (SWaP-C) parameters.

Potential applications for QD-based IR imagers include wearable sensors with comparable or better SWaP-C than current microbolometers and improved speed and sensitivity. Such sensors are ideal for the Army Integrated Visual Augmentation System (IVAS), for example. Small drones and autonomous vehicles operating in degraded visual environments would also benefit from the low cost and tailorable performance of QD imagers.

Current applications for QD absorbers are based on the designs of conventional IR cameras. Another ‘leap-ahead’ enabled by determining design rules for QD-absorber fabrication is commercialization of novel camera designs using large-scale detectors and/or novel geometries (e.g. curved, flexible sensors) not possible with current technologies.

References:

Hao, Q., Tang, X., Cheng, Y., & Hu, Y. (2020). Development of flexible and curved infrared detectors with HgTe colloidal quantum dots. Infrared Physics and Technology, 108(April), 103344. https://doi.org/10.1016/j.infrared.2020.103344;
Wu, J. Z. (2020). Explore uncooled quantum dots/graphene nanohybrid infrared detectors based on quantum dots/graphene heterostructures. In G. F. Fulop, L. Zheng, B. F. Andresen, & J. L. Miller (Eds.), Infrared Technology and Applications XLVI (Vol. 1140706, p. 7). SPIE. https://doi.org/10.1117/12.2556930;
García De Arquer, F. P., Armin, A., Meredith, P., & Sargent, E. H. (2017). Solution-processed semiconductors for next-generation photodetectors. Nature Reviews Materials, 2(3). https://doi.org/10.1038/natrevmats.2016.100;
[4] Zhang, S., Hu, Y., & Hao, Q. (2020). Advances of sensitive infrared detectors with HgTe colloidal quantum dots. Coatings, 10(8). https://doi.org/10.3390/COATINGS10080760;
[5] Livache, C., Martinez, B., Goubet, N., Ramade, J., & Lhuillier, E. (2018). Road map for nanocrystal based infrared photodetectors. Frontiers in Chemistry, 6(NOV), 1–11. ;
https://doi.org/10.3389/fchem.2018.00575;

[6] Gong, M., Liu, Q., Goul, R., Ewing, D., Casper, M., Stramel, A., … Wu, J. Z. (2017). Printable Nanocomposite FeS2-PbS Nanocrystals/Graphene Heterojunction Photodetectors for Broadband Photodetection. ACS Applied Materials and Interfaces, 9(33), 27801–27808. https://doi.org/10.1021/acsami.7b08226;
Ackerman, M. M. (2020). Bringing colloidal quantum dots to detector technologies. Information Display, 36(6), 19–23. https://doi.org/10.1002/msid.1165;

Palomaki, P., & Keuleyan, S. (2020). IMAGE SENSORS IN CAMERA-TOWN Snapshots by Quantum Dots. IEEE Spectrum, 25–29.;
Keuleyan, S., Lhuillier, E., & Guyot-Sionnest, P. (2011). Synthesis of colloidal HgTe quantum dots for narrow mid-IR emission and detection. Journal of the American Chemical Society, 133(41), 16422–16424. https://doi.org/10.1021/ja2079509;
Cryer, M. E., & Halpert, J. E. (2018). 300 nm Spectral Resolution in the Mid-Infrared with Robust, High Responsivity Flexible Colloidal Quantum Dot Devices at Room Temperature. ACS Photonics, 5(8), 3009–3015. https://doi.org/10.1021/acsphotonics.8b00738

Keywords: Quantum Dot, Nanocrystal, Infrared Detector, Infrared Absorber, Long Wavelength Infrared (LWIR), Uncooled, Sensor, Low-dimensional materials

A22B-T020 Multi-Domain Operations Logistics Reduction through Integrated Phosphine Sensors within Materiel Storage Containers

RT&L Focus Area(s): General Warfighting Requirements (GWR)

Technology Area(s): Sensors, Materials

ITAR The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 3.5 of the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

Objective: To vastly improve logistics in Multi-Domain Operations (MDO) through a low-cost phosphine sensor which can be integrated onto existing storage containers housing Red Phosphorus (RP)-related materiel.

Description: MDO in contested EW (electronic warfare) environments require technologies and weapon systems capable of delivering payloads on target and on time. EM (electromagnetic) attenuating aerosols play a crucial role in protecting the Warfighter MDO by decreasing or modifying electromagnetic signatures detectable by various sensors, seekers, trackers, targeting and optical enhancement devices, and the human eye. RP remains the highest performing fielded visible obscurant, capable of generating the highest-yielding aerosol on a volume and weight basis. Leveraging the exceptional performance of RP is critical when considering payload and load-out constrained systems, such as a rocket warheads. While efforts are underway to modify RP to be less reactive to water, stockpile material is still subject to degradation resulting in the release of highly toxic phosphine gas within the storage containers of RP munitions (Pepelko 2004). Of particular interest, the PA150 (NSN: 8140-01-451-7538) / PA154 (NSN: 8140–01–380–5857) / PA157 (NSN: 8140–01–354–0766) could be outfitted with these sensors. Existing commercially-available sensors are very expensive and not easily integrated onto munition containers, their use would require “breaking the seal” of storage containers, thereby potentially exposing those involved to the toxic phosphine (Brabec 2019). The goal of this program would be a sensor that would not break the seal of either the inner or outer packs of the container. State-of-the-art sensor technologies are frequently based upon electrochemical or semiconductor sensing media that can directly interact with an analyte, has been p- or n-modified, or has been functionalized by an inorganic or organic moiety capable of direct analyte interaction. Several state-of the-art approaches include: monolayer materials, such as Al2C (Rahimi 2021), self-assembled monolayers (Xia 2013); reduced graphene oxide (Furue 2017), nitrogenated graphene (Yar 2019) which can provide significant signal response enabled by very thin monolayers while providing very high surface areas for analyte interaction; nanoporous and nanostructured silicon (Ozdemir 2010), providing both high surface areas due to nanoporosity and the ability to tune conduction through charge carrier modification or nanostructure growth; and, organic sensing media functionalized with specific moieties (Kim 2020). Sensors based upon these sensing media may function by measuring changes in conductivity induced by variations in charge carriers (electron and hole) when analytes sorb or desorb from the surface, or cause displacement of previously adsorbed species, such as oxygen. Although considered state-of-the-art, these approaches require direct contact of the sensing media and their electronic circuits with the analyte of interest, such as phosphine. Using these sensor technologies with munitions could create significant hazards in the presence of corrosive environments, causing corrosion of circuits and potentially leading to local heating, sparking, or other unintended initiation sources for phosphine, di-phosphine, or the payload. This topic seeks to develop technologies able to monitor phosphine concentrations within munition containers while eliminating any potential for unintended ignition of gases generated by degradative processes, or munition payloads. This low-cost sensor could be fitted upon all existing storage containers to provide an immediate and reliable on-demand read-out of phosphine concentration relative to action level, vastly improving logistics in MDOs.

Phase I: Develop and fabricate a sensor that incorporates all necessary components to function, including both the non-electronic (interior), interface, sensor components (breadboard scale), self-calibration and zeroing, and reliably measures low-level concentrations of phosphine 0.01 ppm ± 0.02 ppm (an order of magnitude below the OSHA TWA) and high-level concentrations of phosphine to 100 ppm (± 2 ppm). Successful proposals will include any assumptions, along with the expected sensitivity and specificity of the proposed approach. While phosphine is the only pnictogen hydride anticipated to be present as a degradation byproduct, proposed solutions should indicate if the approach will show sensitivity toward phosphine over other pnictogen hydrides. Proposed designs should avoid the use of microheaters that could contribute to unintended ignition. This sensor shall be integrated onto existing munition containers with little to no modification to said containers. At most, two adjacent small sampling holes would be permitted, provided they do not compromise the form, fit or function of the container. Offeror shall coordinate their proposed integration locations and design with the technical points of contact to ensure proper form, fit and function is retained. All components and technological approaches shall be selected in a way to ensure a minimum 15-year uninterrupted service life, and the device shall be serviceable to extend the service life by an additional 15 years, assuming intermittent on-demand usage. Sensor shall incorporate features to maintain calibration, prevent signal drift as a function of time or phosphine saturation. Design approach shall incorporate features to prevent fouling or saturation by other substances, and reliably function when the phosphine saturation limit is reached. Paper study to ensure capability of being miniaturized and cost no more than $15 per unit, assuming 10,000 units of production. Given the low cost of simple circuitry (e.g. dollar store calculators) it is assumed that the cost of the integrated sensor should not exceed the specified per-unit cost at production quantities. Approaches exist to potentially lower manufacturing costs (Prajesh 2015), however awareness of Ph II requirements should be taken to ensure the prototype, once miniaturized, will meet environment/vibrational requirements (ruggedness), as well as any industry and regulatory standards for sensors of toxic materials. Efforts should be made to ensure recovery, reusability, and refurbishment of sensors. Presumed components and parts list, along with shelf and use lifespans shall be provided as a deliverable to Phase I.

Phase II: Miniaturize according to Ph I paper study. Demonstrate the required per-unit cost can be achieved by direct in-house fabrication or through partnerships with commercial electronics fabricators. Must meet all ruggedness (cold and hot conditioning, logistic vibration, drop testing) parameters for the munitions containing RP (MIL-STD-810H, others) while installed on an operationally relevant container. Budget should include all components necessary to meet the requirements, including operationally relevant containers. All production hardware required to produce 10,000 units per year, such as dies, molds, etc., shall be produced and made available during Ph II. All molds, dies, tooling, software, and components shall be a Phase II deliverable. All enclosures and components shall withstand storage and field conditions for a minimum of 30 years. Any seals (e.g. elastomers) incorporated into the design shall withstand storage and field conditions without leakage or other failure for a minimum of 30 years or a minimum of 15 years if the seals are serviceable. Sensor shall retain full functionality and meet all performance requirements for a minimum of 30 years. All energy sources shall provide enough power for full operation for a minimum of 30 years, or shall provide enough power for full operation for a minimum of 15 years and shall be serviceable to extend the service life by an additional 15 years. Full technical data package describing the production unit, components, sourcing, repair protocols, and replacement parts shall be a Phase II deliverable.

Phase III Dual Use Applications: Produce no less than 10,000 units and in integrate into existing RP munition storage containers. Lotting will be in accordance with MIL-STD-1168.

References:

MIL-DTL-211 Revision F, Phosphorus, Red, Technical Detail Specification;
MIL-STD-810H;

Pepelko, Seckar, Harp, Kim, Gray, Anderson; Worker Exposure Standard for Phosphine Gas; Society for Risk Analysis; 2004; p1201-13.;
Davies, N; Red Phosphorus for Use in Screening Smoke Compositions; DTIC ADA372367; 1999;

Griffiths, T.; Charslety, E.; Goodall, S.; Barnes, P.; Stability Studies of Red Phosphorus using Heat Flow Microcalorimetry; CPIAC-2002-06570; 2002;
Furue, R.; Koveke, P.; Sugimoto, S.; Shudo, Y.; Hayami, S.; Ohira, S-I.; Toda, K. Arsine gas sensor based on gold-modified reduce graphene oxide. Sensors and Actuators B. 2017, 240, pp 657-663.;

Ozdemir, S.; Gole, J. A phosphine detection matrix using nanostructure modified porous silicon gas sensors. Sensors and Actuators B. 2010, 151, pp 274-280.;
Brabec, D.; Campbell, J.; Arthur, F.; Casada, M.; Tilley, D.; Bantas, S. Evaluation of Wireless Phosphine Sensors for Monitoring Fumigation Gas in Wheat Stored in Farm Bins. Insects. 2019, 10, pp 121.;

Rahimi, R.; Solimannejad, M. Sensing ability of 2D Al2C monolayer toward toxic pnictogen hydrides: A first-principles perspective. Sensors and Actuators A. 2021, 331, pp 113000.;
Prajesh, R.; Jain, N.; Agarwal, A. Low cost packaging for gas sensors. Microsyst. Technol. 2015, 21, pp 2265-2269.;
Yar, M.; Hashmi, M.; Ayub, K. Nitrogenated holey graphene (C2N) surface as highly selective electrochemical sensor for ammonia. Journal of Molecular Liquids. 2019, 296, pp 111929.;

Kim, C-Y.; Lee, H-H. Phosphine Electrochemical Sensor Using Gold-Deposited Polytetrafluoroethylene Membrane. Journal of Nanoscience and Nanotechnology. 2020, 20, pp 5654-5657.;
Xia, N.; Ma, F.; Zhao, F.; He, Q.; Du, J.; Li, S.; Chen, J.; Liu, L. Comparing the performances of electrochemical sensors using p-aminophenol redox cycling by different reductants on gold electrodes modified with self-assembled monolayers. Electrochimica Acta. 2013, 109, pp 348-354.

Keywords: RP, Phosphine, Detection, Spectroscopy, MOPP, Obscurant

A22B-T021 MOF Sponges for Enhanced Soldier Lethality

RT&L Focus Area(s): General Warfighting Requirements (GWR)

Technology Area(s): Chem Bio Defense

Objective: The Army seeks innovative solutions for engineering metal-organic frameworks into composite sponges and foams for use in personal protective equipment (PPE).

Description: This topic seeks to develop MOF-polymer composites in the form of sponges and foams for enhanced personal protection equipment (PPE). MOFs offer enhanced protection against chemical warfare agents (CWAs)1-3 and toxic industrial chemicals (TICs)4-6. Sponges and foams can be useful for small footprint filters when used with a mask, ballistic protection if integrated into a helmet, and/or small scale portable decontamination of contaminated areas. In For each of these areas, a combined MOF-sponge composite can lead to enhancements in comparison to currently fielded equipment for improved Soldier Lethality.

MOF sponges (and/or foams) will be developed using available techniques that incorporate high mass loadings of MOF (threshold of 50 wt%, objective above 80 wt%). A variety of techniques can be used to make composites resulting in structures such as high internal phase emulsions (polyHIPE) and aerogels.7-9 Composites may be fabricated from pre-existing sponges/foams, with in situ growth of the MOF onto the polymer, or by making the sponge/foam with pre-synthesized MOF.

The resulting composite sponges/foams should be mechanically robust, with MOFs adhered to the surface without shedding and the overall structure free-standing. The foams will be compressible and not fully rigid. Composites should withstand/hold up against most common solvents without dissolving.

MOFs will be accessible within the sponge/foam composites as assessed by nitrogen porosimetry and chemical activity. Composites will be evaluated for toxic vapor uptake and reactivity, including vapor threats (e.g., ammonia, chlorine, DMMP) and chemical warfare agents/simulants (e.g., DMNP, DFP, GB, GD, HD).

Phase I: Demonstrate the ability to make sponges/foams with multiple MOFs, including HKUST-1, UiO-66-NH2, and MOF-808, at loadings exceeding 50 wt%. MOFs will be accessible to toxic chemicals. Demonstrate the ability to control loading of MOF. The composite will be free-standing and compressible without shedding MOF particles. Composites will be fabricated and delivered to CBC in approximately 3” x 3” x 1” swatches.

Phase II: Optimize composite sponge/foam with respect to mechanical and chemical properties. Understand additional potential benefits of technology, including ballistic/shock protection. Understand the effects of environmental conditions and contaminants on the composite. Scale the process to make commercial-type sponges. Tune processing techniques to understand trade-offs associated with flexibility, hardness, MOF content, MOF shedding, chemical performance, etc. Collect data on composite activity (toxic gas adsorption, breakthrough, permeation, and/or reactivity).

Phase III Dual Use Applications: Collaborate with industry partners to develop technologies, to include novel filter designs, decontamination sponges/wipes, air storage devices, and more.

References:

Son, F.; Wasson, M. C.; Islamoglu, T.; Chen, Z. J.; Gong, X. Y.; Hanna, S. L.; Lyu, J. F.; Wang, X. J.; Idrees, K. B.; Mahle, J. J.; Peterson, G. W.; Farha, O. K., Uncovering the Role of Metal-Organic Framework Topology on the Capture and Reactivity of Chemical Warfare Agents. Chemistry of Materials 2020, 32 (11), 4609-4617.;
Peterson, G. W.; Moon, S. Y.; Wagner, G. W.; Hall, M. G.; DeCoste, J. B.; Hupp, J. T.; Farha, O. K., Tailoring the Pore Size and Functionality of UiO-Type Metal-Organic Frameworks for Optimal Nerve Agent Destruction. Inorganic Chemistry 2015, 54 (20), 9684-9686.;
Moon, S. Y.; Proussaloglou, E.; Peterson, G. W.; DeCoste, J. B.; Hall, M. G.; Howarth, A. J.; Hupp, J. T.; Farha, O. K., Detoxification of Chemical Warfare Agents Using a Zr-6-Based Metal-Organic Framework/Polymer Mixture. Chemistry-a European Journal 2016, 22 (42), 14864-14868.;

DeCoste, J. B.; Browe, M. A.; Wagner, G. W.; Rossin, J. A.; Peterson, G. W., Removal of chlorine gas by an amine functionalized metal-organic framework via electrophilic aromatic substitution. Chemical Communications 2015, 51 (62), 12474-12477.;
Peterson, G. W.; Mahle, J. J.; DeCoste, J. B.; Gordon, W. O.; Rossin, J. A., Extraordinary NO2 Removal by the Metal-Organic Framework UiO-66-NH2. Angew Chem Int Edit 2016, 55 (21), 6235-6238.;

Peterson, G. W.; Wagner, G. W.; Balboa, A.; Mahle, J.; Sewell, T.; Karwacki, C. J., Ammonia Vapor Removal by Cu(3)(BTC)(2) and Its Characterization by MAS NMR. Journal of Physical Chemistry C 2009, 113 (31), 13906-13917.;
Jin, P.; Tan, W. L.; Huo, J.; Liu, T. T.; Liang, Y.; Wang, S. Y.; Bradshaw, D., Hierarchically porous MOF/polymer composites via interfacial nanoassembly and emulsion polymerization. Journal of Materials Chemistry A 2018, 6 (41), 20473-20479.;
Mazaj, M.; Logar, N. Z.; Zagar, E.; Kovacic, S., A facile strategy towards a highly accessible and hydrostable MOF-phase within hybrid polyHIPEs through in situ lmetal-oxide recrystallization. Journal of Materials Chemistry A 2017, 5 (5), 1967-1971.

Keywords: Chemical warfare agent, toxic industrial chemical, filtration, protection, metal-organic framework, MOF, foam, sponge, decontamination

A22B-T022 A Novel Pre-Compression Kolsky Tension Bar Technique for Brittle Materials

RT&L Focus Area(s): Hypersonics

Technology Area(s): Materials, Weapons

Objective: Develop an innovative Kolsky tension bar system to characterize the dynamic tensile behavior of brittle materials at high strain rates.

Description: Tension-induced dynamic fragmentation is often observed on the back side of the penetration/perforation targets as a result of stress wave reflection from the free surface. Tensile/spall damage generated during the fragmentation process significantly compromises the penetration resistance of the target material, which leads to reduced protection capability. This unique challenge is further exacerbated by the lack of a reliable dynamic tensile characterization system for brittle materials. Over the past several decades, some efforts have been made to develop a Kolsky bar-based dynamic tensile testing technique using the ideas of spall tension [1,2], split tension [3,4], and direct tension [5,6]. A common draw back of all these techniques is that the specimens rarely reach the state of stress equilibrium or constant strain-rate deformation at the time of fracture due to extremely small tensile failure strain for most of the brittle materials.

The goal of this topic is to develop a Kolsky tension bar system capable of extending the tensile strain of brittle specimens during dynamic tests through the implementation of a pre-compression mechanism. This idea leverages the relatively large compressive failure strain for brittle materials to effectively provide additional time for the tensile specimens to achieve dynamic stress equilibrium and constant strain-rate deformation. The proposed new Kolsky tension bar technique needs to provide a wide range of adjustable pre-compressive stresses to accommodate different types of brittle materials (high-strength concrete, armor glass/ceramics, composites, etc.) for the Army’s applications.

Phase I: Demonstrate the design concept for the new Kolsky tension bar system, and the unique mechanism of applying/controlling the static pre-compressive stress to tensile specimens. Develop a reliable specimen attachment technique to ensure 1. rigid, steady specimen/bar connection, and 2. smooth and continuous transition from compressive to tensile loading conditions. Demonstrate the feasibility of tailoring the dynamic loading wave to achieve stress equilibrium and constant strain rate deformation for the test specimen. Deliver a report documenting the research and development efforts along with a detailed description of the proposed prototype Kolsky tension bar. Phase I focuses on the conceptual design of the prototype. Only the most effective and promising design that addresses all the aforementioned requirements will be given consideration for a Phase II award.

Phase II: Manufacture a prototype of the Kolsky tension bar system proposed in Phase I. Demonstrate the pre-compression mechanism at several designated stress levels, and the loading wave tailoring capability aimed at achieving desired dynamic stress equilibrium and constant strain rate deformation. Demonstrate the specimen attachment technique that is capable of handling the rapid transition from compression to tension. Phase II will also require live demonstration tests using the prototype system. The materials of choice are fiber-reinforced and non-reinforced high-strength concrete, or other brittle material with limited tensile strain capacity and clear applications for the Army. These materials are chosen due to their extremely low tensile failure strength (and strain) compared to other brittle materials.

Reporting and documentation: (1) the CAD drawings, operation manual, and safety guideline for the prototype system; (2) the verification procedure that demonstrates the experimental results meet the desired testing conditions. In addition to the reporting and documentation, Phase II also requires delivery of a well-tuned, fully functioning pre-compression Kolsky tension bar system

Phase III Dual Use Applications: The development of a pre-compression Kolsky tension bar system benefits a broad range of military applications such as vehicular/body armor design, testing of high-strength/ultra-high-strength concrete for impact and blast protection, development of composite gun barrel for light-weight gun system, etc. This new technique also has potential to satisfy the needs of academic research on dynamic tensile behavior of other emerging brittle materials, and clear applications for the Army through the various materials R&D efforts in support of several modernization priorities through the CFTs.

References:

Klepaczko JR, Brara A (2001) An experimental method for dynamic tensile testing of concrete by spalling. Int J Impact Eng 25:387-409;
Erzar B, Forquin P (2010) An experimental method to determine the tensile strength of concrete at high rates of strain. Exp Mech 50:941-955;

John R, Antoun T, Rajendran AM (1992) Effect of strain rate and size on tensile strength of concrete. In: Shock Compression of Condensed Matter 1991 (S.C. Schmidt, R.D. Dick, J.W. Forbes, D.G. Tasker, eds.), Proceedings of the American Physical Society Topical Conference, pp. 501-504;
Ross CA, Tedesco JW, Kuennen ST (1995) Effects of strain rate on concrete strength. ACI Mat J 92:37-47;

Birkimer DL, Lindemann R (1971) Dynamic tensile strength of concrete materials. ACI J, January 47-49;
Goldsmith W, Sackman JL, Ewert C (1976) Static and dynamic fracture strength of Barre granite. Int J Rock Mech Min Sci & Geomech Abstr 13:303-309

Keywords: split Hopkinson bar, brittle material, Kolsky tension, dynamic tensile behavior

A22B-T024 To develop a portable and automated device: enabling precise and multiplexed detection of metabolites and/or chemicals

RT&L Focus Area(s): Biotechnology

Technology Area(s): Bio Medical

Objective: To develop a portable, automated, and easy to use in vitro diagnostic (IVD) device for rapid detection of metabolites and/or chemicals from minimally invasive biomatrices.

Description: Metabolite ﬁngerprints are used to discover biomarkers of diseases by providing comprehensive information on the physiological state. These typical end products of biofunctions are used to comprehend the upstream molecular perturbations and can inform the disease dynamics. The metabolites detection is facilitated by methods including capillary electrophoresis mass spectrometry (MS), nuclear magnetic resonance MS, liquid chromatography (LC) and gas chromatography (GC) MS. In recent years, FDA has approved multiple MS based in vitro diagnostic (IVD) tools for newborn screening, tacrolimus detection (LC-MS/MS platform) and microbial identification (MALDI-TOF based detection). There are several laboratory-developed tests available to monitor drug abuse or pain, quantify steroids or vitamin D and its derivatives (Cheng et al. 2017). Emerging studies converge on establishing metabolites for the elucidation of biochemical pathways to improve diagnosis and therapeutic capabilities, enhancing Military readiness. Studies have identified metabolic/inflammation pathways and biomarkers for Alzheimer’s disease, Parkinson’s disease, and PTSD (Melon et al. 2019; Dean et al. 2019; Kinney et al. 2018, Lian et al. 2019). For instance, patients suffering from PTSD are typically susceptible to the disturbances in somatic pathology in inflammation, metabolic syndrome, and mitochondrial dysfunction. These metabolites, such as Global Arginine Bioavailability Ratio and lactate/citrate, outperformed the combined individual components (Dean et al. 2019), emphasizing the need for a targeted multiplexing capability to detect the metabolite profile. Current instrumentation for metabolite detection is expensive and rely on complicated upstream handling of large biological samples. The above criteria raises a challenge to deploy such systems in austere conditions and bed side clinics. Although there are some portable and field-rugged mass spectrometers available commercially, they lack end-to-end analytical methods or clinical accuracy. Integrated microfluidic devices for sample preparation, separation and/or introduction are emerging in the field of bioanalysis, requiring further exploration. The efforts are in development of point-of-care (PoC) tests, with the ideal version for this test being an independent and self-sustainable operation allowing a non-trained operator to load samples into the instrument and obtain informative results with minimal user intervention. Fully integrated device as one system will significantly advance PoC decisions. This topic seeks to develop a portable, automated, rapid, easy to use device for sample testing that is effective for the detection and screening of targeted metabolites to determine any user-defined clinical landmark(s) or distinguish the disease states (e.g. identify healthy cohorts from diseases cohorts or vice versa). Improving the mass analyzers in a portable format along with chromatography and/or electrophoresis have the potential to revolutionize biomedical science and would offer benefits in multiplexing. The targeted molecules could be related to metabolism (e.g. shortchain fatty acids, amino acids, lipid, phenolic/indolic compounds) and/or hormones/precursors (e.g. GABA, dopamine, serotonin). The proposed technology can use blood or other non-invasive biological fluids (urine, saliva and sweat). It should have a low footprint and an enabled multiplexing capability to be used onsite, bedside, or at minimally supervised clinics. This device will raise the possibility of: identifying the metabolomics differences associated with PTSD; contribute to personalized biomarker-based monitoring; and treating underlying pathophysiology in PTSD.

Phase I: Provide experimental evidence indicating the potential for this assay to be applied effectively using either existing, modified, or novel field-rugged mass spectrometry systems. Use of human or animal subjects is not intended or expected, in order to establish/achieve the necessary proof-of-concept in Phase I. At the end of this phase, a working prototype of the assay(s) should be completed with some demonstration of feasibility, integration, and/or operation of the prototype. In addition, descriptions of data analysis and interpretations concept and concerns should be outlined. Phase I should also include the detailed development of Phase II testing plan.

Phase II: During this phase, the integrated system should undergo testing. Here, we will develop suitable initial small molecule compound libraries and demonstrate the end-to-end analytical method, sufficient to indicate the operations in the final device. Accuracy, reliability, and usability should be assessed. Capabilities that are sought herein should preferably encompass an end-to-end method to include low (or minimally) invasive biospecimen collection and an automated assay followed by simple sample analysis. This testing should be controlled and rigorous. The preferred method shall be in an easy-to-use format, not too technically demanding, and require instrumentation with minimal analytics. To note, solicited capability excludes any antibody-based enzyme-linked immunosorbent assay (ELISA) or primer-based polymerized chain reaction (PCR) method. Statistical power should be adequate to document initial efficacy and feasibility of the assay. This phase should also demonstrate evidence of commercial viability of the tool. Accompanying the application should be standard protocols and procedures for its use and integration into ongoing programs.

Phase III Dual Use Applications: Phase III efforts should include a focus on technology transition, preferably commercialization of STTR research and development. The product developed is intended to be suitable for use and potential procurement by all of the Services. Realization of a dual-use technology applicable to both the military and civilian use is preferred. Therefore, the successful transition path of the technology is expected to include close engagement with military medical acquisition program managers (USAMMDA) during product commercialization to ensure appropriate product applicability for military field deployment. During this phase, expand the compound library and range of analytical methods for testing and evaluation of the operation and effectiveness of utilizing an integrated system. Accuracy, reliability, and usability should be assessed. This testing should be controlled and rigorous. Statistical power should be adequate to document initial efficacy and feasibility of the assay. This phase should also demonstrate evidence of commercial viability of the tool. Accompanying the application should be standard protocols and procedures for its use and integration into ongoing programs.

References:

Kinney JW, Bemiller SM, Murtishaw AS, Leisgang AM, Salazar AM, Lamb BT. Inflammation as a central mechanism in Alzheimer's disease. Alzheimers Dement (N Y). 2018;4:575-590. Published 2018 Sep 6. doi:10.1016/j.trci.2018.06.014;
Lian TH, Guo P, Zuo LJ, et al. Tremor-Dominant in Parkinson Disease: The Relevance to Iron Metabolism and Inflammation. Front Neurosci. 2019;13:255. Published 2019 Mar 27. doi:10.3389/fnins.2019.00255;

Mellon SH, Bersani FS, Lindqvist D, et al. Metabolomic analysis of male combat veterans with post traumatic stress disorder. PLoS One. 2019;14(3):e0213839. Published 2019 Mar 18. doi:10.1371/journal.pone.0213839;
Susan Cheng, , Chair, Svati H. Shah, Elizabeth J. Corwin, Oliver Fiehn, Robert L. Fitzgerald, Robert E. Gerszten, Thomas Illi, Eugene P. Rhee, Pothur R. Srinivas, Thomas J. Wang, and Mohit Jain, on behalf of the American Heart Association Council on Functional Genomics and Translational Biology; Council on Cardiovascular and Stroke Nursing; Council on Clinical Cardiology; and Stroke Council Potential Impact and Study Considerations of Metabolomics in Cardiovascular Health and Disease: A Scientific Statement From the American Heart Association

Keywords: Mass spectrometry, liquid chromatography, gas chromatography, multiplex assay, portable device, small molecules, metabolomics, metabolites, chemicals, biomarker, in vitro diagnostics tool

A22B-T025 Novel food Ingredient with very high levels of Essential Amino Acids (EAA) (>80% by mass)

RT&L Focus Area(s): General Warfighting Requirements (GWR)

Technology Area(s): Human Systems

Objective: Develop novel food ingredient with >80% content by mass essential amino acids in proportions similar to whey protein, which is rapidly bioavailable, flavorless, and shelf stable for incorporation into rations.

Description: Essential amino acids (EAAs) must be obtained through dietary protein and are the limiting factor for muscle protein synthesis in the body. During combat operations, warfighters engage in sustained physical activity with few opportunities to eat which can lead to negative energy and protein balances. This is a common occurrence in austere environments, such as the arctic, where the average daily energy expenditure is 6000 kcal, with potential energy deficits exceeding 40% of what is required for energy balance. To sustain metabolism during negative protein balance, the warfighter’s skeletal muscle is catabolized leading to losses in lean body mass. This makes the warfighter less effective at accomplishing their mission and overmatching the enemy. In scenarios where energy deficit is unavoidable, strategies to support performance and improve recovery should focus on providing the highest quality nutrition provision that mitigates detrimental effects and aids in warfighter recovery.

Unfortunately, most food proteins do not contain high levels of EAA. “Gold standard” proteins (whey, casein, egg) contain only 40-50% EAA by mass, and are difficult to incorporate into combat rations in high levels. Direct fortification of combat rations with free amino acids has been unsuccessful due to the bitterness of free amino acids. In addition, free amino acids tend to react with other compounds in the food to produce non-nutritive off flavors and colors. These irreversible reactions (e.g., Maillard browning), reduce amino acid content and bioavailability of EAA within the food. Organoleptic quality of combat rations is of the utmost importance so that Soldiers will be motivated to consume the rations even when stressed. Maintaining the formulated nutritional profile across storage and deployment is imperative to support performance and recovery.

This topic seeks a novel food ingredient that can be a “blank canvas” for ration developers to create the next generation of compact, tasty and nutritious combat rations. The ideal ingredient would have greater than 80% content of EAA, neutral flavor, provide essential amino acids in proportions similar to whey protein, release EAA into the blood stream at a rate which approaches that of consuming free crystalline amino acids, be stable/maintain protein quality over storage at high temperatures, not react with reducing sugars in the food, and be easy to incorporate into a wide variety of combat rations ranging from bars to complete entrees.

Phase I: Depending on the nature of the technology proposed, phase I deliverables may consist of a technical report, and/or proof of concept experiments, and/or the preparation of a small sample (5-500g) of the novel ingredient for evaluation by Army scientists. Successful offerors will demonstrate the technology is feasible, and scalable past benchtop level.

Any ingredient samples provided must be food safe and contain only GRAS/Food grade materials. Offerors should plan to address the food safety concerns inherent in producing food ingredients (e.g., microbiological quality, allergenicity, quality control/GMP) with a view to obtaining GRAS status for the novel food ingredient. Offerers should plan to address the Army’s concerns with both the organoleptic and nutritional stability of the ingredient during deployment in combat rations. Combat rations are tested for stability using accelerated storage studies of 1 month at 120F, 6 months at 100F, and 3 years at 80*F.

Offerors should compare their ingredient to gold standard protein sources and propose appropriate analytical strategies for verifying and validating the quality and suitability of the ingredient for combat rations.

Phase II: Phase II will involve scale up and deployment of the technology used to create the novel ingredient, with a target of supplying between 2-20kg of food safe, ready to use powdered ingredient for evaluation by DEVCOM SC food technologists by the end of phase II.

Successful offerors will demonstrate the capability to scale up the technology to low-rate initial production, and a technology path towards the production of the food ingredient in larger amounts (1-100 tons/year) suitable for supply to DoD combat ration suppliers.

Offerors will conduct the activities needed to support applying for GRAS status of the ingredient in Phase II, which will support transition to Phase III.

Offerors will demonstrate successful execution of the analytical strategies proposed in phase I, for verifying and validating the quality and suitability of the ingredient for combat rations, including stability under accelerated storage test conditions.

In lieu of human/animal trials (all cases to be conducted in compliance with IACUC or IRB-approved protocols, and with the coordination and approval of the COR), offerors may demonstrate the bioaccessibility of the ingredient by appropriate chemical analysis procedures.

Offerors may demonstrate their food ingredient being used in a variety of food formulations, with a special interest in products besides bars/beverages, e.g. retorted entrées or baked goods. Ideally the product could be incorporated in significant amounts into combat rations with both high (retort entrée's) and low water activities (baked goods, bars).

Phase III Dual Use Applications: The end state for this project is the creation of a novel food ingredient with very high essential amino acid content, that can be used to create shelf stable combat rations with greater levels of high-quality protein/EAA while being more compact and palatable than existing rations.

After successful verification/validation studies by Army scientists, the most likely pathway for transition is judged to be supply of the raw ingredient to 3rd party manufacturers of combat rations. Ration suppliers could be asked to make combat rations which will be specified to contain the ingredients that meet performance specifications for EAA content, or to contain protein quality levels which can be achieved using the technology of this STTR.

Outside of the military market, it is anticipated that there would be interest in this ingredient by the food/nutrition industry because an ingredient with a very high EAA content could be used to valorize low quality cheaper protein sources by converting them to high quality complete proteins. Alternatively, the ingredient could be used to create sports nutrition products that sustain muscle growth/recovery by supplying EAA.

References:

Nutrient Composition of Rations for Short-Term, High-Intensity Combat Operations. National Academies Press. (https://www.nap.edu/catalog/11325/nutrient-composition-of-rations-for-short-term-high-intensity-combat-operations);
AR40-25 Nutrition and Menu Standards for Human Performance Optimization (https://armypubs.army.mil/epubs/DR_pubs/DR_a/pdf/web/AR40-25_WEB_Final.pdf);

Essential Amino Acids and Protein Synthesis: Insights into Maximizing the Muscle and Whole-Body Response to Feeding. Nutrients. 2020 Dec 2;12(12):3717. doi: 10.3390/nu12123717. PMID: 33276485; (https://pubmed.ncbi.nlm.nih.gov/33276485/);
The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption. J Nutr. 2015 Sep;145(9):1981-91. doi: 10.3945/jn.114.204305. Epub 2015 Jul 29. PMID: 26224750. (https://pubmed.ncbi.nlm.nih.gov/26224750/)

Keywords: Essential Amino Acid, Combat Ration, Protein, Food Technology, Combat Feeding, Muscle