Tech Briefs

High-Temperature Silicon Carbide Power Module for Military Hybrid Electric Vehicles

The ever-increasing electrical power, power density, and cooling requirements of present and future military platforms are pushing silicon-based power electronics systems to their operational limits. To address future needs, wide bandgap semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) were developed for electronic applications. Using these semiconductor materials, a new generation of wide bandgap power devices is being developed.

Posted in: Briefs, Materials, Power electronics, Materials properties, Semiconductors, Hybrid electric vehicles, Military vehicles and equipment

Prognostic Health Management for Avionics System Power Supplies

Electronic systems such as electronic controls, onboard computers, communications, navigation, and radar perform many critical functions onboard military and commercial aircraft. All of these systems depend on electrical power supplies for direct current (DC) power at a constant (regulated) voltage to drive solid-state electronics. With these power supplies playing an important role in the operation of aircraft systems and subsystems, flight and ground crews need health state awareness and prediction tools that diagnose faults accurately, predict failures, and project life remaining of these components.

Posted in: Briefs, Electronics & Computers, Avionics, Electronic equipment, Electric power, Prognostics, Commercial aircraft, Military aircraft

Energy-Scalable Protocols for Battery Operated Micro Sensor Networks

Networks of microsensors can greatly improve environment monitoring for many civil and military applications. Multiple sensors provide fault tolerance and can provide valuable inferences about the physical world to the end user. In order to prolong the lifetimes of wireless sensors, all aspects of a sensor system should be energy efficient. To maximize battery lifetimes of distributed wireless sensors, network protocols and data fusion algorithms should be designed with low-power techniques. Network protocols minimize energy by using localized communication and control and by exploiting computation/communication tradeoffs. A sensor network system that uses a localized clustering protocol and beamforming data fusion was developed to enable energy-efficient collaboration.

Posted in: Briefs, Electronics & Computers, Mathematical models, Architecture, Sensors and actuators, Surveillance, Energy consumption

Fabrication of Carbon Nanotube Channels on Three- Dimensional Building Blocks

Single-wall carbon nanotubes (SWNTs) are the most attractive material in the fields of nanoscience and nanotechnology due to their chemical, physical, and electrical properties. Carbon nanotubes (CNTs) are being applied in various kinds of nano devices such as transistors, electrodes, sensors, and filters because of the semiconducting, metallic, optical, and structural properties. To date, CNTs are mainly synthesized, grown, and dispersed on a two-dimensional substrate. However, it is not easy to fabricate and manipulate CNTs on a particularly structured substrate for various applications. In the case of CNTs on planar substrates, it is hard to get high conductivity and sensitivity because of physical disconnection and low surface areas due to randomly oriented two-dimensional structure.

Posted in: Briefs, Manufacturing & Prototyping, Fabrication, Nanomaterials, Nanotechnology

Wide-Field Imaging System and Rapid Direction of Optical Zoom

A breadboard system has been developed for demonstrating nonmechanical zoom using flexible thin films. The project consists of three major task areas: material characterization, diagnostic system development, and imaging system development. The material characterization phase involves two components: development of modeling tools, and measurement of material properties for use in the tools. The diagnostic system development phase will apply the tools and knowledge developed in the first phase to build algorithms for modeling and testing one-dimensional films with multiple actuators. These models will then be compared to experimental results and modified as needed. The imaging system development phase will conclude the effort by building a sensor system with variable zoom based on optical-quality PVDF films.

Posted in: Briefs, Electronics & Computers, Imaging, Sensors and actuators, Diagnostics, Product development, Systems engineering, Materials properties

Reactive Structure and Smart Armor for Future Ground Vehicles

AReactive Structure Technology (RST) is a new class of smart structure that can react to external excitations (such as blast or ballistic impacts) in a carefully designed way using the energy pre-stored internally or from the external excitations to counteract the hazardous loading or perform other desired tasks. A reactive structure deflects an incoming projectile in order to protect a vehicle body. When a projectile hits the face plate (armor), the embedded sensors feed the impact signal to a control unit, and actuators are triggered to move the faceplate. The movement of the faceplate deflects the projectile and significantly reduces the possibility of penetration in the back plate.

Posted in: Briefs, Mechanical Components, Sensors and actuators, Active safety systems, Protective structures, Military vehicles and equipment

Distributed, Collaborative Human- Robotic Networks for Search, Identify, and Track

A human-robotic system is under development that can map an unknown environment, as well as discover, track, and neutralize several static and dynamic objects of interest. In addition, the robots can coordinate their individual tasks with one another without overly burdening a human operator. The testbed utilizes the Segway RMP platform, with lidar, vision, inertial, and GPS sensors. The software draws from autonomous systems research, specifically in the areas of pose estimation, target detection and tracking, motion and behavioral planning, and human robot interaction.

Posted in: Briefs, Physical Sciences, Architecture, Computer software / hardware, Surveillance, Human machine interface (HMI), Product development, Robotics

Software System for Microbial Genome Sequence Annotation

The annotation of genomes from next-generation sequencing platforms needs to be rapid, high-throughput, and fully integrated and automated. Although a few Web-based annotation services have recently become available, they may not be the best solution for researchers that need to annotate a large number of genomes, possibly including proprietary data, and store them locally for further analysis.

Posted in: Briefs, Software, Computer software / hardware, Biological sciences, Medical equipment and supplies, Test equipment and instrumentation

Tunable Infrared Material System

The objective of this work was to lay the groundwork for the development of a new tunable II-VI infrared (IR) material system using mature III-V semiconductors as lattice-matched substrates. Mercury cadmium selenide (HgCdSe) was studied as an alternative to mercury cadmium telluride (HgCdTe) as an IRdetecting material.

Posted in: Briefs, Materials, Optics, Nanomaterials, Semiconductors

Nonlinear Acoustic Metamaterials for Sound Attenuation Applications

An acoustic crystal composed of tightly packed spherical particles can exhibit a wide spectrum of acoustic properties with responses varying from linear to highly nonlinear regimes. The physical attractiveness of these crystals resides in the controllability of such acoustic responses by simple manipulation of static pre-compression applied to the material.

Posted in: Briefs, Materials, Materials properties, Acoustics, Noise

Transparent Ceramics for High-Energy Laser Systems

When a high-energy laser (HEL) beam transmits through a window material, a part of the laser energy is absorbed by the material and causes optical aberrations. This absorbed energy results in material heating in the local exposed region, changing its refractive index based on the material’s thermo-optic coefficient, thermal expansion coefficient, and stress optic coefficient. These changes result in beam distortion and loss of output power, measured as optical path distortion (OPD), which has a severe impact on system performance.

Posted in: Briefs, Materials, Windows and windshields, Lasers, Ceramics, Heat resistant materials

Fabrication of Novel Transparent PMMA Composites for Optical Tagging

The emerging threats caused by improvised explosive devices (IEDs) have drastically increased concerns about soldier survivability. The ability to identify “friend vs. foe” of any approaching vehicles clearly, quickly, and from a distance, is invaluable to ensure a soldier’s safety, as well as critical to providing protection of facilities at strategic locations. The current state-of-the-art uses externally applied coatings or markings onto vehicles that are not seen in the visible light spectrum, yet are detectable with the use of an ultraviolet (UV) or infrared (IR) interrogation device. However, coatings can wear off or wash off, and are susceptible to being counterfeited or tempered.

Posted in: Briefs, Manufacturing & Prototyping, Optics, Identification, Composite materials, Polymers, Military vehicles and equipment

Multifunctional Vehicle Structural Health Monitoring with Piezoelectric Wafer Active Sensors

A novel structural health monitoring (SHM) concept of embedded nondestructive evaluation with piezoelectric wafer active sensors (PWAS) has been developed. PWAS can be structurally embedded as both individual probes and phased arrays. They can be placed inside closed cavities during fabrication/ overhaul (such as wing structures), and then be left in place for the life of the structure. The embedded nondestructive evaluation (NDE) concept opens new horizons for performing insitu damage detection and structural health monitoring of a multitude of thin-wall structures.

Posted in: Briefs, Physical Sciences, On-board diagnostics, Vehicle health management, Product development, Non-destructive tests

Acoustic Detection Using Reverberation

Acoustic detection of undersea objects is difficult due to the uncertain environment and even more difficult when the objects are buried in the seabed. First, sediments generate high backscattering noise due to heterogeneous scatters within the sediments, clouding the object.

Posted in: Briefs, Physical Sciences, Remote sensing, Soils, Acoustics, Noise, Marine vehicles and equipment

Evolutionary Data Mining Approach to Creating Digital Logic

When required to reverse-engineer a product, engineers often do not have design specifications for the system, and the machine may not be disassembled or invasively examined. The engineer might attempt to find the correct signal through trial and error, but this would be very time-consuming, and access to experimental resources is very expensive. To deal with this problem, a genetic program (GP)-based data mining (DM) procedure has been invented.

Posted in: Briefs, Information Technology, Mathematical models, Artificial intelligence, Big data, Systems engineering

Precision Targeting with a Tracking Adaptive Optics Scanning Laser Ophthalmoscope

Adaptive optics (AO) has become increasingly utilized in research ophthalmic diagnostic instruments since their first use nearly ten years ago. Integration of adaptive optics in scanning laser ophthalmoscopy (SLO) is a flying-spot technique whereby scattered light in images is blocked by placement of an aperture at a back conjugate focal plane. Adaptive optics systems sense perturbations in the detected wavefront and apply corrections to an optical element that flattens the wavefront and allows near diffraction-limited focus.

Posted in: Briefs, Medical, Adaptive control, Lasers, Medical equipment and supplies

Trustworthy Hardware for 3D Circuit-Level Integration

Three-dimensional (3D) integration is a promising technology for designing high-performance, low-power systems by stacking multiple integrated circuit dies and connecting them at the circuit level with conductive posts. Most current efforts are at the electromechanical level of getting 3D to work efficiently and cost effectively.

Posted in: Briefs, Electronics & Computers, Connectors and terminals, Integrated circuits, Microelectricmechanical device

Open Network Architecture for Army Vehicle Electronics

Army vehicle electronics networking is complex and challenging due to vendor-specific devices and interfaces. Military vehicles require 100% network uptime and security. The network must reduce vehicle clutter, focus on saving soldiers’ lives, and provide minimum latency. Battle requirements change frequently, and vehicle electronics are added ad-hoc to the existing network. This work introduces an open-standard architecture approach that offers non-proprietary solutions with good interoperability, security, scalability, performance benefits, and cost savings.

Posted in: Briefs, Electronics & Computers, Architecture, Reliability, Military vehicles and equipment

Data Fusion of Geographically Dispersed Information for Test and Evaluation

Test and evaluation relies on computer collection and manipulation of data from a myriad of sensors and sources. More computing power allows for increases in the breadth and depth of the information collected. The same computing power must assist in identifying, ordering, storing, and providing easy access to that data. Fast networking allows large clusters of high-performance computing resources to be brought to bear on test and evaluation. This increase in fidelity has correspondingly increased the volumes of data that tests are capable of generating.

Posted in: Briefs, Information Technology, Data exchange, Data management, Test procedures

Microelectromechanical System (MEMS) Switch Test

Analyzing microelectromechanical system (MEMS) switch behavior is a new field of study that guides the production of MEMS switches. One issue of primary importance is the degradation of contact resistance over the lifetime of the device, and whether small variations in the resistance initially can be prognostically used to predict future performance. Unfortunately, commercially available equipment is limited by its data collection rate, and is not a realistic option to examine every cycle of a switch expected to potentially survive for several trillion cycles. In addition, these tests must be performed on tens to hundreds of switches, necessitating the need for a parallel measurement solution.

Posted in: Briefs, Electronics & Computers, Microelectricmechanical device, Switches, Test procedures

Test and Evaluation Uses of Heterogeneous Computing

T est and evaluation of current systems is a time-consuming process that reflects both the intricacies of the object of the test and the range of equipment, personnel, and environments required. Many argue that this process consumes far too much of the time that it takes to put new systems into the hands of the warfighters, and uses way too many resources without much obvious benefit for those in combat.

Posted in: Briefs, Electronics & Computers, CAD / CAM / CAE, Computer simulation, Test procedures, Military aircraft, Military vehicles and equipment

Process for Testing Aeromedical Equipment

Medical devices are designed to function in environmentally controlled locations, such as stationary hospitals, and not within the harsh, dynamic aircraft environment. Yet, the same medical devices used to care for patients in a hospital environment are often the most capable devices for patient care during transport from one facility to another. These missions are called aeromedical evacuation (AE) missions, and they provide life-sustaining care for a vast array of patients. However, because the devices are designed for a controlled environment, concerns they may adversely affect the operation of aircraft systems must be addressed. Conversely, the aircraft may adversely affect the proper operation and efficacy of the medical equipment. Failure of medical devices during in-flight medical care may result in exposing patients and aircrew to hazardous situations.

Posted in: Briefs, Physical Sciences, Architecture, Medical equipment and supplies, Aircraft operations, Risk assessments, Safety testing and procedures, Rescue and emergency vehicles and equipment

Gallium Nitride High-Power Electronics

Gallium nitride (GaN) high-power electronic (HPE) devices have the potential to outperform those made from 4H-silicon carbide (SiC), the polytype used for HPE devices, because it has a larger critical electric field, ξC, the field at which the device breaks down – 3.5 versus 2.5 MV/cm. This is due primarily to GaN’s larger energy gap, EG – 3.39 eV versus 3.25 eV. GaN also has a slightly larger electron mobility, μ – 930 versus 900 cm2/V·s.

Posted in: Briefs, Electronics & Computers, Electronic equipment, High voltage systems, Performance upgrades, Conductivity, Materials properties

Room-Temperature Sub-Diffraction-Limited Plasmon Laser

Lasers present the means to deliver powerful, coherent, and directional high-frequency electromagnetic energy. However, the diffraction limit of light imposes fundamental constraints on how compact such photonic devices can be and their potential for integration with electronic circuits, which are orders of magnitude smaller.

Posted in: Briefs, Photonics, Downsizing, Architecture, Integrated circuits, Lasers

Rare-Earth-Doped Soft Glass Optical Fibers for Coherent Wavelength Sources Above 2 Microns

Rare-earth-doped soft glass optical fibers were developed and characterized for fiber lasers emitting at wavelengths longer than 2 microns to allow efficient narrow line-width emission in the atmospheric window for coherent detection and LIDAR and DIAL sensing.

Posted in: Briefs, Photonics, Fiber optics, Lasers, Fibers, Glass

Ultrasonic Guided Wave Analysis for Detecting and Classifying Damage in a Thin Metallic Plate

A ircraft and rotorcraft structures are being redesigned with new lower weight materials; however, older metallic structures continue to be used. These older structures need monitoring and characterization of damage for con-

tinued operation. The use of ultrasonic guided waves is one nondestructive technique that can be used to interrogate such structures. Typically, large cracks or geometric variations can be found by examining signal amplitude,

but smaller damage that can suddenly grow in size and cause serious damage cannot be detected.

Posted in: Briefs, Physical Sciences, Aircraft structures, Aluminum, Fatigue, Acoustics, Inspections

Disposable Chemical Sensor and Wireless Communication Device

A disposable chemical sensor and temperature device has been developed that may be dropped into building rubble or other areas not accessible by rescue personnel to test the environment in the rubble. The system also provides wireless two-way communication and control to obtain information concerning the environment prior to disturbing an area under the rubble, and gives an indication of the likelihood that the area is a candidate for finding survivors. In addition, it would provide two-way communication between a survivor trapped in the rubble and a surface rescue worker, such that a survivor can be alerted to the fact that he or she should make a sound to make his or her presence known.

Posted in: Briefs, Physical Sciences, Sensors and actuators, Wireless communication systems, Chemicals, Rescue operations

360-Degree Visual Detection and Target Tracking on an Autonomous Surface Vehicle

Operation of autonomous surface vehicles (ASVs) poses a number of challenges, including vehicle survivability for long-duration missions in hazardous and possibly hostile environments, loss of communication and/or localization due to environmental or tactical situations, reacting intelligently and quickly to highly dynamic conditions, re-planning to recover from faults while continuing with operations, and extracting the maximum amount of information from onboard and offboard sensors for situational awareness. Coupled with these issues is the need to conduct missions in areas with other possible adversarial vessels, including the protection of high-value fixed assets such as oil platforms, anchored ships, and port facilities.

Posted in: Briefs, Information Technology, Imaging, Durability, Reliability, Autonomous vehicles, Military vehicles and equipment

Environmental Awareness of Sensor and Emitter Employment

Many Army missions rely on effective sensing capabilities that provide intelligence on the adversary, and protect friendly forces from enemy detection. Sensors that are stationary (microphones, geophones, and ground-based radars) and moving (cameras on unattended aerial vehicles and ground vehicles) assist operations such as persistent surveillance of small, forward-operating bases, and rapid covert troop maneuvers in the air and on the ground. When advantageous, sensing is often performed in multiple signal modalities including visible, infrared, acoustic, seismic, radiofrequency, chemical, and biological.

Posted in: Briefs, Software, Optics, Sensors and actuators, Noise, Military vehicles and equipment

Optical Properties of Aligned Carbon Nanotube Mats for Photonic Applications

Carbon nanotubes possess unique electronic properties that are very useful for building electro-optical devices at nanometer scales. In optoelectronic applications, a large number of carbon nanotubes will be assembled in a desired form.

Posted in: Briefs, Materials, Electronic equipment, Optics, Nanomaterials