Tech Briefs

Carbon Nanotube Purification

This non-invasive method cleans and purifies carbon nanotubes without the use of toxic chemicals.

Development of carbon nanotubes (CNTs), including single-wall and multi-wall nanotubes and nanofibers, into useful devices requires fabrication of CNTs that are relatively free from process residues such as amorphous carbon and metallic particles that are not part of a CNT array grown on a (coated) substrate. Conventional techniques for removal of amorphous carbon and other residues often use one of several techniques. One technique uses post-growth thermal or plasma cleaning of the amorphous carbon with Ox (x=2), which non-selectively attacks the CNT material as well as the amorphous carbon. Metal contaminants are removed using an acid bath, which is again a non-selective process and requires disposal of the strong acids and contaminant removal byproducts. A second technique uses certain toxic gases, such as halogens, to remove the amorphous carbon and other residues. This approach requires disposal of one or more hazardous substances and often requires many hours to complete. A third approach requires holding the amorphous carbon and CNTs in a heated Ox atmosphere for several hours, in order to limit the damage to the CNTs.

Posted in: Briefs, TSP, Mechanical Components

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, Imaging, Imaging and visualization, Imaging, Imaging and visualization, Thermodynamics, Thermodynamics, Defense industry, Missiles

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, Integrated circuits, Lasers, Integrated circuits, Lasers, Fabrication, Materials properties, Semiconductors

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, Sensors and actuators, Sensors and actuators, Water, Defense industry, Conductivity, Hazardous materials, Marine vehicles and equipment, Missiles

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, Charge coupled devices, Imaging, Imaging and visualization, Charge coupled devices, Imaging, Imaging and visualization, Defense industry, Inspections, Missiles

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, Cartography, Imaging, Imaging and visualization, Radar, Cartography, Imaging, Imaging and visualization, Radar, Terrain

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, Amplifiers, Electronic equipment, Lasers, Sensors and actuators, Spectroscopy, Amplifiers, Electronic equipment, Lasers, Sensors and actuators, Spectroscopy, Acoustics, Acoustics

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, Water, Biological sciences, Robotics, Drag, Marine vehicles and equipment

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, Wings, Mathematical models, Aerodynamics

ISO 26262 & Automotive Electronics Development

Compliance standards, especially those that involve relatively new functional safety elements, will likely add additional requirements to the development process. But ISO 26262, in particular, will add more than new requirements to the product life cycle for automotive hardware-software systems. This Functional Safety standard will act as a framework impacting integrated requirements traceability, risk management, validation, verification, documentation and collaboration throughout the systems engineering “V” model life cycle process (see Figure). ISO 26262 will also require the qualification of tools used to create automotive systems. This paper examines the impact of the standard on the development process and support tool chains for automotive electronics.

Posted in: Briefs, TSP, Electronics & Computers, Information Sciences, Semiconductors & ICs, Software, Computer software / hardware, Computer software and hardware, Computer software / hardware, Computer software and hardware, Life cycle analysis, Safety regulations and standards

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