Spintronic Effects in Semiconductor Nanostructures

Progress has been made in calculation of spintronic effects in semiconductor nanostructures. The calculations contribute to the body of theoretical knowledge complementing recent experimental advances in generating, transporting, and detecting coherent spin-polarized populations of electron and nuclear spins in semiconductors. The experimental advances have demonstrated that spintronic effects could be harnessed as the basis of novel nanoscale devices. Theoretical advances are needed to understand and extend the experimental advances by enabling inference of previously unknown phenomena from results of experiments and incorporation of these phenomena into realistic models of operation and performance of spintronic devices, including devices that could be used in quantum computation.

Posted in: Briefs, Physical Sciences, Nanotechnology, Semiconductors

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

Application of CFD to a Slender-Bodied, Finned Projectile

In an application of computational fluid dynamics (CFD), flow fields about a slender-bodied finned projectile and the resulting aerodynamic forces and moments on the projectile were computed. The size and shape of the projectile (a blunt-nosed, ogivecylinder body, 316.7 mm long, 23.5 mm in diameter, with four tail fins) are representative of a preliminary design of a future air-defense projectile. The computations are exemplary of those needed for predicting aerodynamic performances in order to optimize designs of advanced projectiles, missiles, and rockets in general.

Posted in: Briefs, Information Technology, Computational fluid dynamics, Missiles

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

Simulations of Stall and Stall Control in Turbocompressors

Anumerical-simulation study of stall and stall control in radial and axial compressor stages of gas turbine engines has been performed. This and other similar studies are needed because even though the adverse consequences of stall are well known and rudimentary stall-warning and stall-control systems are in use, the scientific basis for predicting and mitigating stall is not yet established.

Posted in: Briefs, Mechanical Components, Simulation and modeling, Compressors, Gas turbines

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