Tech Briefs

Sensitivity Simulation of Compressed Sensing Based Electronic Warfare Receiver Using Orthogonal Matching Pursuit Algorithm

Calculate the sensitivity of a CS based EW receiver using two modulation schemes.

Electronic Intelligence Receiver (ELINT) is an important component in electronic warfare (EW) and layer sensing. The information it provides by constant surveillance can be used to detect, track and classify signals across the electromagnetic spectrum. The proper identification and reaction to the threat can avoid disaster and assure spectrum dominance for Air Force systems.

Posted in: Briefs, Aerospace, Electronics & Computers
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The Impact of Video Compression on Remote Cardiac Pulse Measurement Using Imaging Photoplethysmography

Remote physiological measurement technique leverages digital cameras to recover the blood volume pulse from the human body

Remote measurement of physiological signals has a number of advantages over traditional contact methods. It allows the measurement of vital signals unobtrusively and concomitantly. In recent years, a number of approaches for imaging-based measurement of physiology using digital cameras have been proposed. Imaging photoplethysmography (iPPG) captures variations in light reflected from the body due to blood volume changes in microvascular tissue. It has been demonstrated that sub-pixel variations in color channel measurements from a digital single lens reflex (DSLR) camera, when aggregated, could be used to recover the blood volume pulse. Subsequently, it was shown that iPPG methods can allow accurate measurement of heart rate, heart rate variability, breathing rate, blood oxygenation and pulse transit time.

Posted in: Briefs, Aerospace, Test & Measurement
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Subjective Mapping of Dust-Emission Sources by Using MODIS Imagery

Accurate dust-source characterizations are critical for effectively modeling dust storms and their associated hazards.

Dust storms (5 to 100 km across) often originate from multiple dust-emission sources (1 to 10 km across). Remote-sensing-based dust-source identification is a challenge. A previous study developed a subjective approach for mapping dust sources by using enhanced MODIS satellite imagery; therefore, this study conducted mapping exercises to assess the reproducibility of this technique amongst multiple analysts and in different regions.

Posted in: Briefs, Aerospace, Test & Measurement
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Custom Data Logger for Real-Time Remote Field Data Collections

Compact, energy efficient instruments have the same functionality as a personal computer.

The U.S. Army Corps of Engineers (USACE), CHL, FRF, had a need for a remote real-time data collection system to control instruments and log and communicate data from five observing stations in the Currituck Sound Estuary, NC1. These stations, referred to as the Currituck Sound Array (CSA), collect a suite of meteorological and oceano-graphic data including wind, air temperature, humidity, incoming solar radiation (above and below water), waves, currents, water level, salinity, and water temperature, as well as turbidity and many other water quality parameters. This array of instruments has a variety of control commands, sample routines, and output data formats. Additionally, the CSA was designed to act as a natural laboratory for estuarine research and as an instrument and model test bed. These capabilities required a reliable and flexible system that would allow easy modification of sampling schemes, the ability to log as many as 15 instruments with a single logger, and allow the incorporation of additional and novel instrumentation with minimal effort and expense.

Posted in: Briefs, Aerospace, Test & Measurement
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Initial Validation of Ballistic Shock Accelerometers

A Test Operations Procedure (TOP) describing methods and instrumentation used in the initial validation of accelerometers to be used in both Ballistic Shock testing and crew/vehicle survivability Live Fire Test and Evaluation (LFT&E).

Method 522.2 of MIL-STD-810G CN1 defines ballistic shock as “a high-level shock that generally results from the impact of projectiles or ordnance on armored combat vehicles”. Typical engagements of interest also include Kinetic Energy projectiles, land mines, and improvised explosive devices. For the purposes of this TOP, ballistic shock is generally referred to as the sudden high-rate loading resulting from under body blast (UBB) testing designed to assess the crew-survivability of military vehicles. Historical testing conducted in both areas have proven the relative similarities between the two environments.

Posted in: Briefs, Aerospace, Sensors
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Topology Control in Aerial Multi-Beam Directional Networks

Comparing the performance of a centralized algorithm that retains robust connectivity and reduced throughput to a distributed algorithm that offers higher throughput but fewer network nodes.

In multi-beam directional networks, nodes are able to simultaneously transmit to all neighbors or receive from all neighbors. This spatial reuse allows for high throughputs, but in dense networks can cause significant interference. Topology control (i.e., selecting a subset of neighbors to communicate with) is vital to reduce the interference. Good topology control balances the number of links utilized to achieve fewer collisions while maintaining robust network connectivity.

Posted in: Briefs, Aerospace, Test & Measurement
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Hydrodynamic Drag Force Measurement of a Functionalized Surface Exhibiting Superhydrophobic Properties

Comparing the skin friction drag effects of a superhydrophobic flat plate to an untreated flat plate of the same material and geometry.

With superhydrophobic properties being extended to a variety of metallic substrates through the process of ablation due to femto-second laser surface processing (FLSP), it is important to understand the hydrodynamic benefits of such a material, as well as its resiliency. This research focuses on the skin friction drag effects of a superhydrophobic flat plate compared to an untreated flat plate of the same material and geometry. The resiliency of this material will also be tested through the use of an accelerated corrosion fog chamber using both treated and untreated aluminum samples.

Posted in: Briefs, Aerospace
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