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arXiv 2020年

作者： Beaver, Logan E. Dorothy, Michael Kroninger, Christopher Malikopoulos, Andreas A. Department of Mechanical Engineering University of Delaware NewarkDE United States Combat Capabilities Development Command Army Research Laboratory MD United States

As robotic swarm systems emerge, it is increasingly important to provide strong guarantees on energy consumption and safety to maximize system performance. One approach to achieve these guarantees is through constraint-driven control, where agents seek to minimize energy consumption subject to a set of safety and task constraints. In this paper, we provide a sufficient and necessary condition for an energy-minimizing agent with integrator dynamics to have a continuous control input at the transition between unconstrained and constrained trajectories. In addition, we present and analyze barycentric motion and collision avoidance constraints to be used in constraint-driven control of swarms. Copyright © 2020, The Authors. All rights reserved.

关键词： Energy utilization

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Classification of VR-gaming difficulty induced stress levels using physiological (EEG & ECG) signals and machine learning

TechRxiv

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TechRxiv 2021年

作者： Pratiher, Sawon Radhakrishnan, Ananth Sahoo, Karuna P. Alam, Sazedul Kerick, Scott E. Banerjee, Nilanjan Ghosh, Nirmalya Patra, Amit The Department of Electrical Engineering Indian Institute of Technology Kharagpur West Bengal721302 India The Computer science and Electrical engineering University of Maryland-Baltimore County BaltimoreMD14701 United States The U.S. Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving Ground MD United States

Physiological sensing has long been an indispensable fixture for virtual reality (VR) gaming studies. Moreover, VR-induced stressors are increasingly being used to assess the impact of stress on an individual’s health and well-being. This study discusses the results of experimental research comprising multimodal physiological signal acquisition from 31 participants during a Go/No-Go VR-based shooting exercise where participants had to shoot the enemy and spare the friendly targets. The study encompasses multiple sessions, including orientation, thresholding, and shooting. The shooting sessions consist of tasks under low & high difficulty induced stress conditions with in-between baseline segments. Machine learning (ML) performance with heart rate variability (HRV) from electrocardiogram (ECG) and electroencephalogram (EEG) features outperform the prevalent methods for four different VR gaming difficulty-induced stress (GDIS) classification problems (CPs). Further, the significance of the HRV predictors and different brain region activations from EEG is deciphered using statistical hypothesis testing (SHT). The ablation study shows the efficacy of multimodal physiological sensing for different gaming difficulty-induced stress classification problems (GDISCPs) in a VR shooting task. © 2021, CC BY.

关键词： Electrocardiograms

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Correlation between Cation Order/Disorder and the Electrocaloric Effect in Relaxor Ferroelectrics

SSRN

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SSRN 2022年

作者： Yan, Yongke Geng, Liwei D. Cheng, Li-Qian Li, Xiaotian Leng, Haoyang Wang, Ke Poudel, Bed Nozariasbmarz, Amin Sanghadasa, Mohan Trolier-McKinstry, Susan Zhang, Qi-Ming Wang, Yu U. Priya, Shashank Department of Materials Science and Engineering Pennsylvania State University University ParkPA16802 United States Department of Materials Science and Engineering Michigan Technological University HoughtonMI49931 United States Materials Research Institute Pennsylvania State University University ParkPA16802 United States School of Electrical Engineering and Computer Science Pennsylvania State University University ParkPA16802 United States U.S. Army Combat Capabilities Development Command Aviation & Missile Center Redstone ArsenalAL35898 United States

The physical properties (dielectric, ferroelectric, piezoelectric, etc.) of relaxor ferroelectric complex perovskites depend on the degree of order/disorder and the scale of the ordered domains. In this study, the electrocaloric (EC) properties of three representative relaxors,Pb(Mg1/3Nb2/3)O3-8PbTiO3 (PMN-8PT), 1mol% Sm-doped Pb(Mg1/3Nb2/3)O3-8PbTiO3 (1SPMN-8PT) and Pb(Sc1/2Ta1/2)O3 (PST) are evaluated. Multi-layer ceramic capacitors (MLCCs) with identical structural configurations were fabricated for these three compounds, and their EC properties were characterized by direct measurement using a thermocouple. The EC temperature change ∆T of PMN-8PT, 1S-PMN-8PT and PST MLCCs under 20 V μm−1 at room temperature were found to be 1.42 K, 1.54 K, and 3.10 K, respectively. X-ray diffraction and high-resolution transmission electron microscopy data suggests that the high EC performance of PST is related to the ordering of B-site cations (Sc3+ and Ta5+) with the ordering parameter S = 0.82 and a long coherence length of ~100 nm, such that the sample transitioned from a relaxor ferroelectric to a normal ferroelectric. These results provide pathway towards design of high performance EC materials required for solid state refrigeration and air-conditioning technologies. © 2022, The Authors. All rights reserved.

关键词： Perovskite

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Integrated silicon photonic true-time delay beam-former for wide-band phased-array antenna

Integrated silicon photonic true-time delay beam-former for ...

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Electronic Components and Technology Conference (ECTC)

作者： Stephen Anderson A. Begović A. Chen Z. R. Huang W. Zhou G. Sun Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute Troy NY USA Army Research Laboratory Combat Capabilities Development Command Adelphi MD USA

ISBN: (数字)9781728161808

ISBN: (纸本)9781728161815

Conventional electronically-steerable phased-array antenna systems suffer from increasingly complicated control schemes to allow for narrowband RF steering. A phased array antenna architecture was previously presented which provides for wideband steering using a simplified control scheme requiring only one analog control parameter for steering along one dimension. A cascaded architecture of slow-light-based true-time delay gratings within an silicon photonic integrated circuit (PIC) enable the C-band optical carrier wavelength to serve as this control parameter for an X-band radio-frequency signal. Fabrication of this beamformer PIC was carried out using the American Institute for Manufacturing (AIM) Photonics foundry. Thermal sensitivity of the slow-light gratings and directional couplers on the PIC were investigated, and packaging solutions were evaluated, including integrated doped-silicon heaters to compensate for fabrication variations. A homodyne phase-tracking technique is employed to further characterize the slow-light performance of the beamformer, allowing for phase-sensitive measurements near the band-edge of the slow-light gratings.

关键词： Heating systems Couplings Gratings Directional couplers Silicon Delays Optical waveguides

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development of a new aeroelastic tiltrotor wind tunnel testbed

Development of a new aeroelastic tiltrotor wind tunnel testb...

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AIAA Scitech Forum, 2019

作者： Kreshock, Andrew R. Kang, Hao Yeo, Hyeonsoo Acree, C.W. U.S. Army Research Laboratory Vehicle Technology Directorate Hampton VA United States Aberdeen Proving Ground MD United States Development and Engineering Center Research Development and Engineering Command Ames Research Center Moffett Field CA United States NASA Ames Research Center Moffett Field CA United States

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Disorder-Induced Degradation of Vertical Carrier Transport in Strain-Balanced Antimony-Based Superlattices

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Physical Review Applied 2021年第5期16卷 054028-054028页

作者： E. Bellotti F. Bertazzi A. Tibaldi J. Schuster J. Bajaj M. Reed Department of Electrical and Computer Engineering (ECE) Boston University 8 Saint Mary’s Street Boston Massachusetts 02215 USA Department of Electronics and Telecommunications (DET) Politecnico di Torino and IEIIT-CNR Torino 10129 Italy U.S. Army Combat Capabilities Development Command (DEVCOM) Army Research Laboratory (ARL) 2800 Powder Mill Road Adelphi Maryland 20783-1138 USA

We investigate carrier transport in gallium-free strained-balanced InAs/InxAs1−xSb type-II superlattices in the presence of positional and compositional disorder. We use a rigorous nonequilibrium Green’s function model based on fully nonlocal scattering self-energies computed in the self-consistent Born approximation and a multiband description of the electronic structure. Layer-thickness fluctuations, nonuniform antimony composition, and segregation throughout the superlattice stack lead to as-grown disordered structures that are quite different from the abrupt interface ideal superlattices. We find that regardless of its nature and cause, disorder significantly affects vertical-carrier-transport properties, by impeding the coherent propagation of carriers in the minibands. In particular, the minority-carrier hole mobility is fundamentally limited by the nonideal properties of the superlattice, namely the layer-thickness fluctuation and the nonuniform antimony distribution. Furthermore, upon reducing the temperature, holes become fully localized and transport occurs by hopping, which explains published measured detector data that demonstrates the quantum efficiency, exhibiting a very strong temperature dependence that degrades as the temperature is reduced. As a result, photodetectors that employ holes as minority carriers will be limited in performance, especially for long-wavelength infrared applications at low temperature. However, we find that minority-carrier electron mobility is largely unaffected by disorder, indicating the p-type absorbing layer as the preferred option.

关键词： Carrier dynamics Electrical conductivity Optoelectronics III-V semiconductors Optical sources & detectors Superlattices Infrared techniques Sample preparation

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A Polyurethane-Urea Elastomer at Low to Extreme Strain Rates

SSRN

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SSRN 2022年

作者： Lee, Jaehee Cho, Hansohl Veysset, David Hsieh, Alex J. Rutledge, Gregory C. Department of Aerospace Engineering Korea Advanced Institute of Science and Technology Daejeon34141 Korea Republic of Institute for Soldier Nanotechnologies Massachusetts Institute of Technology CambridgeMA02139 United States Hansen Experimental Physics Laboratory Stanford University StanfordCA94305 United States U.S. Army Combat Capabilities Development Command Army Research Laboratory FCDD-RLW-MG Aberdeen Proving GroundMD21005-5069 United States Department of Chemical Engineering Massachusetts Institute of Technology CambridgeMA02139 United States

A finite strain nonlinear constitutive model is presented to study the extreme mechanical behavior of a polyurethane-urea well suited for many engineering applications. The micromechanically and thermodynamically based constitutive model captures salient features in resilience and dissipation in the material from low to extreme strain rates. The extreme deformation features are further elucidated by laser-induced micro-particle impact tests for the material, where an ultrafast strain rate (> 10^6 s^-1) incurs. Numerical simulations for the strongly inhomogeneous deformation events are in good agreement with the experimental data, supporting the predictive capabilities of the constitutive model for the extreme deformation features of the PUU material over at least 9 orders of magnitude in strain rates (10^-3 to 10^6 s^-1). © 2022, The Authors. All rights reserved.

关键词： Constitutive models

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Evolution of High Strain Rate Mechanical Properties of SAC-R with High Temperature Storage at 50°C with High and Low Operating-Temperatures

Evolution of High Strain Rate Mechanical Properties of SAC-R...

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Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITHERM)

作者： Pradeep Lall Mrinmoy Saha Jeff Suhling Ken Blecker Department of Mechanical Engineering Auburn University NSF-CAVE3 Electronic Research Center Auburn AL US Army Combat Capabilities Development Command ‐ Armament Center

ISBN: (数字)9781728197647

ISBN: (纸本)9781728197654

Previous published literature on material constitutive behavior for SAC-R lead-free solder alloys is restricted to either low strain-rates or room temperature storage (25°C). For the material (SAC-R), high strain-rate data is not available for the storage at high or low operating temperatures. In this experiment, SAC-R has been tested and analyzed at various surrounding temperatures starting from 25°C up to 200°C, with high strain-rates and high aging-temperature as well as low surrounding temperatures from 0°C to -65°C. Storage times of 30-days and 60 days have been studies for a storage temperature of 50°C. Multiple replicates have been tested at each of the conditions and averaged curves reported in the paper. Stress-strain curves have been plotted for a wide range of strain rates and operating temperatures for pristine specimen to aged specimen which have been made using reflow profiles representative of solder-joint production assemblies. The experimental data has been fit into the Anand Viscoplasticity model for (SAC-R) and the Anand constants have been computed by forecasting the measured stress-strain behavior for large ranges of operating temperatures and strain rates. Predictions are compared with the experimentally measured values.

关键词： Strain Temperature measurement Temperature Aging Mathematical model Stress Metals

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Visualizing Plasmon Mediated Metal Deposition and Gold Nanorod Reshaping with Liquid Phase Transmission Electron Microscopy

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Microscopy and Microanalysis 2024年第SUPPLEMENT_1期30卷

作者： Chen, Amy Leff, Asher Li, Zhenpu Ríos Ocampo, Carlos A Boltersdorf, Jonathan Woehl, Taylor Department of Materials Science and Engineering University of Maryland College Park MD United States U.S. Army Combat Capabilities Development Command – Army Research Laboratory Adelphi MD United States General Technical Services LLC Wall Township New Jersey United States Department of Chemical and Biomolecular Engineering University of Maryland College Park MD United States

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Silk fibroin as an additive for cell-free protein synthesis

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Synthetic and Systems Biotechnology 2020年第3期5卷 145-154页

作者： Marilyn S.Lee Chia-Suei Hung Daniel A.Phillips Chelsea C.Buck Maneesh K.Gupta Matthew W.Lux US Army Combat Capabilities Development Command Chemical and Biological Center 8567 Ricketts Point RoadAberdeen Proving GroundMD21010USA US Air Force Research Laboratory 217912th St.B652/R122 Wright-Patterson Air Force BaseOH45433USA US Naval Research Laboratory Center for Bio/Molecular Science and Engineering Bldg.42Room 3034555 Overlook Ave.WashingtonDC 20375UES Inc.4401 Dayton Xenia Rd.BeavercreekOH 45432USA

Cell-free systems contain many proteins and metabolites required for complex functions such as transcription and translation or multi-step metabolic *** into expanding the delivery of these systems by drying or by embedding into other materials is enabling new applications in sensing,point-of-need manufacturing,and responsive ***,silk fibroin from the silk worm,Bombyx mori,has received attention as a protective additive for dried enzyme formulations and as a material to build biocompatible hydrogels for controlled localization or delivery of biomolecular *** this work,we explore the effects of silk fibroin as an additive in cell-free protein synthesis(CFPS)*** of silk fibroin on CFPS activity and stability after drying,as well as the potential for incorporation of CFPS into hydrogels of crosslinked silk fibroin are *** find that simple addition of silk fibroin increased productivity of the CFPS reactions by up to 42%,which we attribute to macromolecular crowding ***,we did not find evidence that silk fibroin provides a protective effects after drying as previously described for purified ***,the enzymatic crosslinking transformations of silk fibroin typically used to form hydrogels are inhibited in the presence of the CFPS reaction *** attempts did not impact CFPS activity,but did yield localized protein aggregates rather than a *** discuss the mechanisms at play in these results and how the silk fibroin-CFPS system might be improved for the design of cell-free devices.

关键词： Cell-free systems Cell-free protein synthesis CFPS Silk fibroin Preservation

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