Tech Briefs

Target Detection and Classification Using Seismic and PIR Sensors

Unattended ground sensors (UGS) are widely used in industrial monitoring and military operations. Such UGS systems are usually lightweight devices that automatically monitor the local activities in-situ, and transfer target detection and classification reports to the processing center at a higher level of hierarchy. Commercially available UGS systems make use of multiple sensing modalities (e.g., acoustic, seismic, passive infrared, magnetic, electrostatic, and video). Efficacy of UGS systems is often limited by high false alarm rates because the onboard data processing algorithms may not be able to correctly discriminate different types of targets (e.g., humans from animals). For example, discriminating human footstep signals from other targets and noise sources is a challenging task, because the signal-to-noise ratio (SNR) of footsteps decreases rapidly with the distance between the sensor and the pedestrian.

Posted in: Briefs, Physical Sciences, Mathematical models, Security systems, Sensors and actuators
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Component Identification in Multi-Chemical Mixtures with Swept-Wavelength Resonant-Raman Spectroscopy

The utilization of ultraviolet resonance Raman spectroscopy for the detection and identification of chemical, biological, and nuclear hazards is of great interest due to the sensitivity and specificity afforded by this technique. Detection by means of optical probing is a fast, non-contact method that requires little to no sample preparation and can be performed remotely by an operator. In addition, this method is also well suited for use by an automated monitor or a mobile autonomous system, such as an in-situ environmental detector or a sensorequipped unmanned vehicle. In addition, this technique offers the ability for a single detector to identify multiple species of targets. However, for Raman detection to become practicable as a forensic tool, the method must demonstrate the ability to distinguish the target elements while operating in a complex environment.

Posted in: Briefs, Physical Sciences, Remote sensing, Spectroscopy, Chemicals, Materials identification, Biohazards, Radiation
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Analysis of Mine Impulse Data Using Stereo-Digital Image Correlation

Improvised explosive devices (IEDs) and other traditional under-body blast weapons are a significant threat to military ground vehicle systems. Engineers and scientists attempting to analyze the effects of under-body blast events have an array of commercial and internally developed tools at their disposal, each with its own set of limitations. Finite element (FE) models offer the capability to evaluate the entire event sequence from the detonation of the buried explosive to the response of the occupant. However, FE models for full system-level mine events require significant time for input preparation, debugging, and computation.

Posted in: Briefs, Information Technology, Finite element analysis, Imaging, Defense industry, Hazards and emergency management, Military vehicles and equipment
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Wheel Force Transducer for Field Testing

This project endeavors to develop, validate, and calibrate cost-effective field test equipment for measuring tire characteristics on vehicles while driving off-road. The four wheel force transducers are designed for use on the High Mobility Multipurpose Wheeled Vehicle (HMMWV or Humvee).

Posted in: Briefs, Physical Sciences, Wheels, Test equipment and instrumentation, Off-highway vehicles and equipment
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Thermal Mechanical Fatigue Crack Growth Testing

Turbines in aircraft turbojet engines are being subject to increasingly higher temperatures to improve fuel efficiency. High turbine efficiency requires the ability of turbine blades to withstand gas temperature of the order of 1350 to 1550 °C. In polycrystalline materials, these increased temperatures would cause creep strains along grain boundaries that would be unacceptable. Even single-crystal materials must be pushed to their limits to insure that engine performance is maximized. Airfoils in modern gas turbine aircraft use a systems approach for cooling to achieve required component life. There are three basic components to these systems: a cast nickel single-crystal superalloy in combination with thermal barrier coatings, and a sophisticated cooling scheme consisting of intricately designed channels and holes through the core and surface of the airfoil.

Posted in: Briefs, Physical Sciences, Fatigue, Turbojet engines, Test procedures, Thermal testing
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Evaluation of Three Extremity Armor Systems

The US Marine Corps and the US Army have been engaged in efforts to evaluate improved body armor, including armor to protect the extremities. These efforts are focused on both body armor performance (i.e., ballistic protection) and armor effects on the physical performance of personnel (e.g., body flexibility, mobility, and agility).

Posted in: Briefs, Physical Sciences, Kinematics, Defense industry, Protective clothing, Military vehicles and equipment
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Low-Power Distributed Jammer Network

The Distributed Jammer Network (DJN) is composed of a large number of tiny, low-power jammers, which are distributed inside a target network and emit radio energy to disrupt its communications. Recent advancement in microelectromechanical system (MEMS) technology makes it possible to make jammers sufficiently small that a DJN can take the form of a dust suspending in the air, thus the name Jamming Dust. Miniaturization of jammers should be less challenging than that of wireless sensors since jammers just emit noise signal without requiring complex modulation, filtering, and other signal processing functions. Therefore, new miniature devices such as nanotube radio may find their first application in jamming dust.

Posted in: Briefs, Electronics & Computers, Microelectricmechanical device, Radio equipment, Telecommunications
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