Tech Briefs

Imaging Detonations of Explosives

Using high-speed camera pyrometers to measure and map fireball/shock expansion velocities.

An effort has been made within the US Army Research Laboratory (ARL) to extract quantitative information on explosive performance from high-speed imaging of explosions. Explosive fireball surface temperatures are measured using imaging pyrometry (2-color 2-camera imaging pyrometer; full-color single-camera imaging pyrometer). Framing cameras are synchronized with pulsed laser illumination to measure fireball/shock expansion velocities, enabling calculation of peak air-shock pressures. Multicamera filtering at different wavelengths enables visualization of light emission by some reactant species participating in energy release during an explosion. Measurement of incident and reflected shock velocities is used to calculate shock energy on a target.

Posted in: Briefs, TSP, TSP, Aerospace, Imaging
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Laser Integration on Silicon Photonic Circuits Through Transfer Printing

New fabrication approach allows the massively parallel transfer of III-V coupons to a silicon photonic target wafer.

The purpose of this project was to develop a transfer printing process for the massively parallel integration of III-V lasers on silicon photonic integrated circuits. Silicon has long offered promise as the ultimate platform for realizing compact photonic integrated circuits (PICs). That promise stems in part from the material's properties: the high refractive-index contrast of silicon allows strong confinement of the optical field, increasing light-matter interaction in a compact space—a particularly important attribute for realizing efficient modulators and high-speed detectors.

Posted in: Briefs, TSP, TSP, Aerospace, Photonics
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Determining Detection and Classification Potential of Munitions Using Advanced EMI Sensors in the Underwater Environment

Electromagnetic induction could be used to locate and characterize potentially dangerous sunken metallic objects.

Hazardous ordnance items are present along coastlines and in rivers and lakes in waters shallow enough to cause concerns for human recreational and industrial activities. The presence of water makes it difficult to detect and remove these hazardous legacies induced from wars, military training and deliberate disposal. Various techniques have been proposed to detect and characterize Unexploded Ordnances (UXO) and discarded military munitions (DMM) in the underwater environment including acoustic waves, magnetometery, and electromagnetic induction (EMI).

Posted in: Briefs, TSP, TSP, Aerospace, Sensors
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High Energy Computed Tomographic Inspection of Munitions

Inspection system provides additional level of quality assurance for R&D, reverse engineering, and malfunction investigations.

An advance computed tomography (CT) system was recently built for the U.S. Army Armament Research, Development and Engineering Center, Picatinny Arsenal, NJ, for the inspection of munitions. The system is a charged coupled device (CCD) camera based CT system designated with the name “experimental Imaging Media” (XIM). The design incorporated shielding for use up to 4MeV x-ray photons and integrated two separate cameras into one single field of view (FOV). Other major distinguishing characteristics include its processing functions to digitally piece the two cameras together, use of advanced artifact reduction principles, performing reconstruction simultaneously during acquisition, and its development in accurate beam hardening corrections through digital means.

Posted in: Briefs, TSP, TSP, Aerospace, Photonics
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Terahertz (THz) Radar: A Solution For Degraded Visibility Environments (DVE)

Operating at higher frequencies than other types of radar produces tighter beams and finer resolution.

An accurate view of the physical world is frequently vital. For example, rotary wing aircraft pilots must have knowledge of the terrain in order to safely fly their aircraft. Therefore, systems capable of generating images of the environment of sufficient quality to facilitate the decision process are necessary. The product of such a system is illustrated in Figure 1.

Posted in: Briefs, TSP, TSP, Aerospace, Imaging
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Development of Photoacoustic Sensing Platforms

Research focuses on sensor miniaturization and detection of chemical targets both proximally and at range.

In recent years, photoacoustic spectroscopy (PAS) has emerged as an attractive and powerful technique well suited for sensing applications. The development of high-power radiation sources and more sophisticated electronics, including sensitive microphones and digital lock-in amplifiers, have allowed for significant advances in PAS. Furthermore, photoacoustic (PA) detection of IR absorption spectra using modern tunable lasers offers several advantages, including simultaneous detection and discrimination of numerous molecules of interest. Successful applications of PAS in gases and condensed matter have made this a notable technique and it is now studied and employed by scientists and engineers in a variety of disciplines.

Posted in: Briefs, TSP, TSP, Aerospace, Photonics
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Experimental Confirmation of an Aquatic Swimming Motion Theoretically of Very Low Drag and High Efficiency

Researchers used an anguilliform swimming robot to replicate an idealized “wakeless” swimming motion.

It has been established theoretically that self-propulsion of deformable bodies in ideal fluid can occur with a careful specification of the deformation mode shape. With the fluid assumed ideal, vortex shedding, rotational wake, and induced drag would not occur. The implication is that for a real fluid, provided the existence of a thin boundary layer, similarly configured bodies with the same deformation mode shape self-propel without vortex shedding, rotational wake, and induced drag. Only viscous drag effects, due to the existence of the thin boundary layer, are present and unavoidable. The motion mode in question is the little-exploited anguilliform mode exhibited in some aquatic animal swimming. The Anguilla includes the snake, eel, lamprey, and leach, among others.

Posted in: Briefs, TSP, TSP, Aerospace, Automation
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Gesture-Based Controls for Robots: Overview and Implications for Use by Soldiers

Developing a more effective means to communicate with robotic devices.

Afuture vision of the use of autonomous and intelligent robots in dismounted military operations is for soldiers to interact with robots as teammates, much like soldiers interact with other soldiers. Soldiers will no longer be operators in full control of every movement, as the autonomous intelligent systems will have the capability to act without continual human input. However, soldiers will need to use the information available from, or provided by, the robot. One of the critical needs to achieve this vision is the ability of soldiers and robots to communicate with each other. One way to do that is to use human gestures to instruct and command robots.

Posted in: Briefs, TSP, Aerospace, Automation, Robotics
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A Guide for Developing Human-Robot Interaction Experiments in the Robotic Interactive Visualization and Experimentation Technology (RIVET) Simulation

Using computer gaming technology to improve the interaction between humans and unmanned ground vehicles.

ARL's Intelligent Systems Enterprise vision is to enable the teaming of autonomous intelligent systems with soldiers in dynamic, unstructured combat environments, as well as in non-combat military installations and base operations. To accomplish this vision for interdependent soldier-robot teaming, there has been a paradigm shift in robotic research conducted by ARL from the current instantiation of fielded remote-controlled or teleoperated robots to systems with increased intelligence, decision-making capability, and autonomy. This type of teaming is needed for future joint, interdependent, network-enabled operations.

Posted in: Briefs, TSP, Aerospace, Automation
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Identifying the Flow Physics and Modeling Transient Forces on Two-Dimensional Wings

Using mathematics and modeling to understand the flow physics of aircraft wings undergoing highly unsteady maneuvers.

The main objective of this research was to better understand the flow physics of aircraft wings undergoing highly unsteady maneuvers. Reduced-order models play a central role in this study, both to elucidate the overall dynamical mechanisms behind various flow phenomena (such as dynamic stall and vortex shedding), and ultimately to guide flight control design for vehicles for which these unsteady phenomena are important.

Posted in: Briefs, TSP, TSP, Aerospace, Automation, Robotics
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