Physical Sciences

Circuit Models for Robust, Adaptive Neural Control

This project seeks to reproduce the neural circuits used by the nematode Caenorhabditis elegans for locomotion. Caenorhabditis elegans is a small (~1.2 millimeter) nematode found in rotting fruit in many parts of the world. It feeds on bacteria and is neither parasitic nor pathogenic. Although capable of sexual reproduction, most laboratory strains reproduce primarily as self-fertilizing hermaphrodites, with each adult hermaphrodite producing approximately 300 progeny (Figure 1).

Posted in: Briefs, Aerospace, Physical Sciences, Instrumentation, Test & Measurement

New Grasses Neutralize Toxic Pollution From Bombs and Munitions

On military live fire training ranges, troops practice firing artillery shells, drop bombs on old tanks or derelict buildings and test the capacity of new weapons. But those explosives and munitions leave behind toxic compounds that have contaminated millions of acres of U.S. military bases — with an estimated cleanup bill ranging between $16 billion and $165 billion. However, University of Washington and University of York researchers recently described new transgenic grass species that can neutralize and eradicate RDX — a toxic compound that has been widely used in explosives since World War II.

Posted in: News, Defense, Environmental Monitoring, Recycling Technologies, Physical Sciences

Detecting Trace Levels of Explosives Using Vibrational Sum Frequency Spectroscopy

The threat of improvised explosive devices (IEDs) to human life is grave, and countering this threat is a high priority for force protection during military operations. Remote, standoff detection of in-place IEDs would be a significant step forward in mitigating the threat posed by these weapons.

Posted in: Briefs, Aerospace, Defense, Physical Sciences, Sensors and actuators, Military vehicles and equipment

Next-Generation Spectrometers for Rapid Analysis of Complex Mixtures

Molecules have internal motions that are characteristic of their structure and identity. These motions can be studied by spectroscopy in different regions of the electromagnetic spectrum. Molecular spectra can be used as a “fingerprint” to unambiguously state whether or not a particular chemical is present and in what amount. As such, small portable spectrometers are frequently used as components of chemical sensors.

Posted in: Briefs, Aerospace, Defense, Physical Sciences, Sensors and actuators, Medical, health, and wellness, Chemicals, Hazardous materials, Test equipment and instrumentation

Analysis of an In-Ear Dosimeter for a Single Hearing Protection Device

US national and many international hearing conservation programs (HCPs) have adopted a noise exposure criterion of 85 dBA for a time-weighted average of 8 hours, with a 3 dB per doubling exchange rate (safe exposure duration was cut in half for each 3 dB increase in noise level). Military personnel who work in extreme noise environments require high attenuation from hearing protection in order to complete a normal duty day without risk of permanent hearing loss. Improvements to both hearing protection and noise dose monitoring have been consistently recommended and pursued as a means to reduce risk for noise-induced hearing loss.

Posted in: Briefs, Aerospace, Defense, Physical Sciences, Noise, Noise measurement, Protective equipment

Automatic-Alignment Fiber Optic Coupling System for Optimal Signal Transmission

Using the current method of characterizing waveguides manufactured for research in optical communications, it can take up to 8 hours to characterize the waveguides on a single silicon wafer. Using the automatic computer automation system developed, the characterization process has been reduced to less than an hour. After the silicon wafer containing the waveguides is manufactured, the waveguides must be evaluated to determine the optical characteristics of the various waveguides on the silicon wafer.

Posted in: Briefs, Physical Sciences, Optics, Waveguides

Detecting Maritime Radiological/Nuclear Threats with Hybrid Imaging

The SuperMISTI detection system is a hybrid detection, identification, and imaging system for sources of gamma-ray radiation at stand-off distances. The system is based on the Mobile Imaging and Spectroscopic Threat Identification (MISTI) system designed for the Department of Homeland Security. The SuperMISTI system uses the high-resolution spectra of high-purity germanium (HPGe) detectors to detect and identify gamma-ray sources as well as coded aperture technology, and lower-cost NaI detectors to image and localize the detected sources. The system utilizes a modular design to allow the detection/identification and the imaging/ localization portions to be used separately or together, depending on the situation.

Posted in: Briefs, Physical Sciences, Imaging, Marine vehicles and equipment

Testing Particle Counters for Detection of Fuel Contamination

Fuel quality assurance is accomplished by conducting periodic fuel sampling for the condition monitoring of aviation fuel by detecting, measuring, and reporting the levels of contaminants in the fuel. Current methods have several drawbacks including operator subjectivity, lack of detailed analysis, limitations in providing reliable data, and the turnaround time needed to get the test results.

Posted in: Briefs, Physical Sciences, Aviation fuels, Quality assurance, Test procedures

Simultaneous Vibration Suppression and Energy Harvesting

The goal of this work was to investigate the concept of using harvested energy to directly control the vibration response of flexible aerospace systems. Small, lightweight, flexible micro air vehicles (MAVs) operate near flutter, providing both harvesting opportunities and vibration suppression requirements. The possibility that the ambient energy might be harnessed and recycled to provide energy to mitigate the vibrations through various control laws was investigated. The goal was to integrate harvesting, storage, control, and computation into one multifunctional structure.

Posted in: Briefs, Physical Sciences, Vibration, Unmanned aerial vehicles

Cascading Failures in Coupled Distributed Power Grids and Communication Networks

Emerging distributed power grid systems will integrate tightly coupled networks, namely a power grid and a communication network, to provide distributed power monitoring and control. While distributing power monitoring and control away from a central site enhances the robustness of the power grid to multiple, dispersed failures and attacks, such communication-based distributed control schemes can introduce complex cascading failure scenarios in the face of large-scale weapons of mass destruction (WMD) attacks.

Posted in: Briefs, Physical Sciences, Telecommunications, Electric power grid, Hazards and emergency management