Validation of Hazardous Air Pollutant (HAP)-Free Torque Seal Inspection Lacquer

The Army uses numerous adhesives and sealants, among other coating materials, that contain significant amounts of hazardous air pollutants (HAPs). This work examines laboratory and field demonstration/validation of one sealant, Torque Seal. A HAP-free alternative to Torque Seal containing ethanol as the carrier solvent has been identified. Laboratory testing including adhesion, resistance to fluids, resistance to humidity, and drying time validated that the HAP-free sealant performs very similarly to the baseline Torque Seal containing methanol (HAP). Furthermore, a demonstration study at Fort Rucker, AL, using a UH-1 helicopter rotor, shows that the HAP-free sealant performed as well as the Torque Seal.

Posted in: Briefs, Materials, Air pollution, Adhesives and sealants, Performance tests, Test procedures, Military aircraft, Military vehicles and equipment

Optimized Robust Adaptive Networks in Supervisory Control and Data Acquisition Systems

The Electric Power and Communica - tion Synchronizing Simulator (EPOCHS) system could provide great benefits to private industry and Department of Defense (DoD) power systems infrastructure by allowing simultaneous, synchronous simulation of communication and power system simulators to better understand the power grid under anomalous situations. Supervisory Control and Data Acquisition (SCADA) systems and the power grid infrastructure have recently been the focus of attention given the recent disclosure of potential cyber attacks. Applying Special Protection Schemes like the one used by the EPOCHS systems could provide a solution not only to cyber attack, but to possible cascading failures typical to power systems on current high-load demands. Utilizing an Internet-like architecture to implement such a backup and communication system is likely to be the most logical solution to providing a power grid intranet.

Posted in: Briefs, Information Technology, Computer simulation, Failure modes and effects analysis, Architecture, Cyber security, Telecommunications systems, Electric power grid

Evolvable Approaches to Software Verification and Validation

Research was conducted to integrate and advance current techniques in compilers, hardware architectures, and security to develop novel techniques to protect against physical attacks on encrypted embedded systems. The innovation in the approach was in exploiting the power of integrated software-hardware methods that do not require processor re-design. The hardware side of the innovation comes from using reconfigurable logic to implement security techniques in hardware. The reconfigurable logic in hardware, when combined with the ability of the compiler to instrument the code, can be used in powerful ways to strengthen the security of computing platforms. Several techniques were proposed and designed to address these objectives.

Posted in: Briefs, Information Technology, Computer software / hardware, Cryptography, Cyber security, Research and development, Quality assurance

Developing Fleets of Autonomous Underwater Vehicles

Autonomous underwater vehicles (AUVs) have a demonstrated capability to collect valuable data for scientific and military purposes. Historically, individual vehicles have been used. To reduce the overall time and cost of acquiring data over large areas, multiple vehicles must be used. A fleet of five AUVs, capable of underwater commendation, was fabricated. These AUVs include small submarines, referred to as “swimmers,” and small, two-tracked vehicles, referred to as “crawlers.” The control and communication algorithms developed in this work will enable AUVs to use formations to search for mines and to communicate with each other in order to implement cooperative behavior. Languages and logics were developed to enable collaborative operations among the vehicles.

Posted in: Briefs, Mechanical Components, Communication protocols, Electronic control systems, Fleet management, Autonomous vehicles, Marine vehicles and equipment

Stability Analysis of Distributed Engine Control Systems

Full Authority Digital Engine Control (FADEC), based on a centralized architecture framework, is being widely used for gas turbine engine control. However, current FADEC is not able to meet the increased burden imposed by the advanced intelligent propulsion system concepts. This has necessitated development of the Distributed Engine Control (DEC) system. FADEC based on Distributed Control Systems (DCS) offers modularity, improved control sys-tem prognostics, and fault tolerance, along with reducing the impact of hardware obsolescence.

Posted in: Briefs, Mechanical Components, Architecture, Performance upgrades, Engine control systems, Gas turbines

Wireless Network Cocast: Location-Aware Cooperative Communications with Linear Network Coding

In wireless networks, reducing aggregate transmit power and having even power distribution increase the network lifetime. The conventional direct transmission (DTX) scheme results in high aggregate transmit power and uneven power distribution. In conventional DTX, where mobile units directly transmit their information to a common destination, the distant mobile units require more transmit power to provide a comparable quality of service (QoS) to that of the closer ones. Consequently, high aggregate transmit power (the sum of all transmit power of individual mobile units) and uneven power distribution among the units exist in the network. These two issues result in low network lifetime, which is defined as the time until the first mobile unit dies. It is wellknown that diversity techniques such as time diversity, frequency diversity, and spatial diversity result in reduction of transmit power and thus can be used to improve network lifetime. Three location- aware cooperation-based schemes considered in this work are immediateneighbor cooperation (INC), maximal cooperation (MAX), and wireless network cocast (WNC) that achieve spatial diversity to reduce aggregate transmit power and even power distribution.

Posted in: Briefs, Electronics & Computers

High Assurance Virtualization Engine (HAVEN)

Virtualization technology has been around since the late 1960s. Initially, it was conceived to maximize utilization of expensive hardware by running multiple instances of an operating system (OS) using virtual machines (VM). In the past decade, virtualization has become popular due to its cost and space-saving advantages.

Posted in: Briefs, Electronics & Computers, Virtual reality, Architecture, Computer software / hardware

Memory-Based, Structured, Application-Specific Integrated Circuit (ASIC)

For air, space, and ground-based systems, there is a clear need for highperformance, lightweight, low-power, highly reliable computing on data-intensive applications. A data-intensive application is one in which there is a very large volume of data, which is often accessed in irregular patterns. Yet, despite the fact that application-specific integrated circuits (ASICs) are becoming more memory- intensive, commodity memory and ASIC design and manufacturing technologies are still on divergent paths.

Posted in: Briefs, Electronics & Computers, Design processes, Integrated circuits, Data management, Fabrication

Solid-State, High-Energy Lasers Based on Rare-Earth Doped Gallium Nitride

Laser-based directed-energy weapons (DEW) are important components for future Army missile defense systems. The diode-pumped, rare-earth (RE)-doped, solid-state laser is a very promising path towards achieving a DEW-sufficient level of average power from a reasonably compact device. Even so, the extreme pump power densities, combined with the inevitable non-radiative losses in the pump-lase process, introduce severe thermal loading in the gain medium. Regardless of the sophistication of the heat removal technique and its efficiency, the gain medium itself is the bottleneck for non-distortive heat removal due to the low thermal conductivity of known gain media compared to that of heat-sinking materials. The bestknown laser hosts, e.g., yttrium aluminum garnet (YAG), possess thermal conductivities (10–11 W/(m-K)) that are ~1.5 orders of magnitude lower than those of known heat-sinking materials. In order to eliminate this technical hurdle, an innovative gain medium with a thermal conductivity on the same order as copper (~390 W/(m- K)) had to be engineered.

Posted in: Briefs, Photonics, Lasers, Thermal management, Military vehicles and equipment, Missiles

Analysis of Analog Photonic Links Employing Multiple-Channel (Arrayed) Receivers

Analog optical links are finding increased application in commercial and military systems ranging from radio-over-fiber applications, antenna remoting, and optical signal processing. As the performance of an analog link improves with received photocurrent, optical amplifiers — predominantly erbium-doped fiber amplifiers (EDFAs) — have been readily incorporated into a variety of systems. It is known that the addition of an optical amplifier (EDFA) raises the electrical noise floor in both digital and analog applications due to the presence of amplified spontaneous emission (optical) noise. To mitigate this additional noise in systems employing EDFAs prior to modulation, dualoutput optical modulators and balanced detection are frequently employed. This technique has been utilized alone to achieve the first multi-gigahertz bandwidth analog optical link with a noise figure

Posted in: Briefs, Photonics, Amplifiers, Architecture, Noise