Jamming-Resistant Adaptive Radio System

Developing smart antennas for jam-resistant cognitive or software-defined radio systems entails a number of challenging issues. Researchers at the University of Texas are investigating methods to locate jamming signals and then take evasive action to maintain a communication link. Their work involves the use of large arrays of miniaturized, tunable antennas and adaptive filters to protect the system. The goal is to design a resilient communication system resistant to jamming signals in a wide spectrum of frequencies.

Posted in: Application Briefs, RFM Catchall, Antennas, Communication protocols, Radio equipment, Reliability

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

Modern Military Energy Storage Technology

The risk of human casualties associated with fuel convoys, combined with the long-term cost issues of unreliable technologies, has the military exploring greener, more sustainable options with the goal of increasing energy efficiencies, lowering fuel consumption, and lessening the risk of lost lives. Advanced battery technology continues to be validated as a viable solution to lowering fuel demands. For example, today’s advanced energy storage systems can store energy from portable solar arrays to power essential electronic systems at forward operating bases (FOBs) — instead of using a vehicle’s idling engine power or diesel generators — significantly reducing fuel consumption, costs, and risk.

Posted in: Articles, Aerospace, Batteries, Energy storage systems, Military vehicles and equipment

Choosing a Capacitor for Use as a Switch-Mode Power Supply Filter

Input filter caps need to be able to supply a quick burst of energy and to suppress noise generated in the switch circuit. Important considerations for the input filter cap are ESR, ESL, and ripple current. High CV density is preferred in the input filter caps to reduce board space, although it is more critical for the output filter caps.

Posted in: Articles, Aerospace, Electronic Components, Power Management, Power Supplies, Capacitors, Switches, Parts

Inside the Navy’s Quiet Water Tunnel Facility

When water flows over an acoustic sensor, non-acoustic pressure fluctuations caused by turbulence can decrease the signal-to-noise ratio and make it difficult to sense incoming acoustic waves. The Quiet Water Tunnel Facility at the Naval Undersea Warfare Center in Newport, RI is a unique test facility capable of investigating these pressure fluctuations and evaluating new and existing technologies aimed at reducing flow noise and drag due to skin friction. These technologies include modifications to the surface itself, such as riblets or compliant coatings, or modifications to the flow, such as suction or injection of water into the boundary layer.

Posted in: Articles, Aerospace, Water, Acoustics, Test facilities, Marine vehicles and equipment

Chemically Bonded Phosphate Ceramics Stop Corrosion

Corrosion of steel, aluminum, and other structural metals erodes the safety and financial stability of industries and countries alike. Fighting corrosion in ships, tanks, planes, and equipment costs the Pentagon $22.9 billion a year. Corrosion costs advanced industrialized nations about 3.5% of GDP to replace damaged material and components, plus a similar amount due to lost production, environmental impact, disrupted transportation, injuries, and fatalities.

Posted in: Application Briefs, Ceramics, Corrosion, Steel