Multi-Scale Model of Failure in a Composite Material

An adaptive concurrent multilevel computational model of failure in a heterogeneous-material structure has been developed. As used here, "concurrent" is a term of art characterizing a class of structural/material models that (1) incorporate submodels representing material substructures at different spatial scales from macroscopic to microscopic, (2) the equations of the various models are solved simultaneously, and (3) the solutions at the various scales are coupled. The present model applies, more specifically, to a unidirectionalfiber/ matrix composite material structure. The model can be used to simulate and analyze the initiation and growth of damage, starting from microstructural damage in the form of debonding at fiber/matrix interfaces.

Posted in: Briefs, Information Technology, Failure analysis, Simulation and modeling, Composite materials

Adaptive Quantum Design of Semiconductor Devices

The term "adaptive quantum design" denotes a methodology for systematically seeking robust, manufacturable designs of semiconductor devices — especially semiconductor optoelectronic devices having nanoscale or even atomic- scale features. This methodology has been developed to complement advances in fabrication capabilities that make it possible to tailor semiconductor devices ever more precisely, such that it likely will soon be possible to routinely control the positions of features as small as atoms and molecules within devices. Because the number of atom configurations that could, potentially, be fabricated is almost unimaginably large and quantum fluctuations and collective quantum phenomena become important at molecular and atomic scales, traditional design methods and traditional models of device physics based on classical physics and semiclassical approximations of quantum phenomena are not adequate for exploration of the vast space of design options.

Posted in: Briefs, Electronics & Computers, Design processes, Semiconductor devices

Real-Time Simulation and Semiautomated Design of Complex ICs

A project called “System on a Chip Real-Time Emulation” (SOCRE) was undertaken to develop and demonstrate a methodology of simulation of operation and semiautomated design of complex mixed-signal (analog/digital) integrated circuits (ICs). The methodology includes the use of a simulation engine (consisting of computer hardware and software) for real-time emulation of a designed IC, in conjunction with an automated design flow that enables automated or semiautomated synthesis of a final design and automated or semiautomated fabrication of the ICs of the designed IC without need for manual reentry of a description of the design.

Posted in: Briefs, Electronics & Computers, CAD / CAM / CAE, Integrated circuits, Test procedures

A Study of Two Ferrocene-Based Molecular Electronic Devices

Acomputational-simulation study of two ferrocene-based molecular electronic devices was performed as part of a continuing effort to develop a capability for ab initio design of metallocene-based electronic devices in general. In addition to the obvious technological advantage for realization of the potential of molecular electronic devices, such a capability would afford an economic advantage by enabling avoidance of the cost of synthesis of many organic molecules that subsequent testing would show to be unpromising for electronic-device applications.

Posted in: Briefs, Electronics & Computers, Simulation and modeling, Electronic equipment

Continuous-Wave Atom Laser

Progress has been made toward realization of a continuous-wave, phase-andamplitude- stable atom laser based on magnetic guiding, magnetic compression, and continuous distributed evaporative cooling of a sparse cloud of 87Rb atoms. This apparatus is intended to serve as a prototype of sources of coherent matter waves for future atom-interferometric field and motion sensors.

Posted in: Briefs, Photonics, Lasers, Sensors and actuators

Adaptive Optoelectronic Eyes

Aprogram of research has built a technological foundation for further development of systems that could be characterized, variously, as "smart" cameras or adaptive optoelectronic eyes. A system according to this concept would function in an optimal manner to capture images under a variety of lighting conditions and would be capable of semi-autonomous recognition of objects.

Posted in: Briefs, Photonics, Imaging, Optics

Innovations Pertaining to Carbon-Based Materials

Some notable innovations in the design and manufacture of carbonbased materials have been made in a continuing program of basic research on carbon- based materials for use in propulsion systems of aircraft and spacecraft. The research has ranged over diverse topics that have included fabrication of carboncarbon composite-material components, protection of carbon against oxidation, microelectromechanical devices, and surface- tension phenomena.

Posted in: Briefs, Materials, Composite materials, Aircraft, Spacecraft

Polymeric “Smart” Skin Materials

"Smart” skin materials based, variously, on polymers, dendrimers, carbon nanotubes, and/or other tailored molecular components are being developed for use as conformal coating surfaces of mechanical structures, including those of aircraft, to impart enhanced functionality to the coated surfaces. As used here, “smart” signifies that a material so characterized exhibits a useful physical response (e.g., a change in color) to a change in some aspect of its environment (e.g., temperature or pressure) or to a control or actuation signal. It is envisioned that smart skin materials could be used for diverse purposes, including sensing surface flow conditions and altering surface optical properties to enable detection, concealment, or display. It is further envisioned that smart skin materials could be integrated with microscopic electronic, optoelectronic, electro-optical, and microelectromechanical devices to obtain smart skins exhibiting even more varieties and higher degrees of functionality.

Posted in: Briefs, Materials, Coatings Colorants and Finishes, Smart materials

Nanoparticle AlxMoyOz/Al Thermites

Research on the microstructures, chemical compositions, and reactivities of thermites that consist of or contain mixtures of MoO3 and Al particles has led to development of a process for making thermites that consist of or contain mixtures of AlxMoyOz and Al nanoparticles. The reactivities of the AlxMoyOz/Al thermites can be tailored through choices of ingredients at critical process steps. The findings of this and related research and development efforts may lead to the use of AlxMoyOz/Al thermites as components of insensitive weapon ignition systems.

Posted in: Briefs, Materials, Nanomaterials

Aptamer-Based Sensors for Detection of Proteins

Molecular aptamer beacons (MABs) are being investigated for use as rapid-signaling probe compounds for detecting specific proteins of interest (target proteins). In the MAB approach, one exploits a combination of (1) the molecular- recognition capability and high affinity of aptamers (defined below) with respect to molecules of interest and (2) the fluorescent- signaling transduction method of molecular beacon probes (also defined below) to enable real-time monitoring of target proteins. MABs could help to satisfy the increasing need for rapid, sensitive biosensing in diverse endeavors that include medical diagnosis, discovery of drugs, and homeland security. For example, rapid biosensing could enable early diagnosis and treatment of disease or rapid response to a chemical or biological attack.

Posted in: Briefs, Medical, Sensors and actuators, Medical equipment and supplies