Special Coverage

Self-Healing Wire Insulation
Thermomechanical Methodology for Stabilizing Shape Memory Alloy (SMA) Response
Space Optical Communications Using Laser Beams
High Field Superconducting Magnets
Active Response Gravity Offload and Method
Strat-X
Sonar Inspection Robot System
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Adaptive Refinement Tools for Tetrahedral Unstructured Grids

This software can potentially be used in aerospace, aviation, and automotive applications. NASA’s Langley Research Center engineers have developed a new software package for more facile computational fluid dynamics. The software’s fast user run time, robustness, and efficiency have enabled its extensive use in space shuttle modeling. Adaptive Refinement Tool (ART) permits the computational modeling of flow, including jet or rocket plumes, wakes, and shocks via unstructured tetrahedral grids. Commercially available software packages often struggle to sufficiently and quickly model such complex examples of flow. ART also allows cells to be divided into two, four, or eight cells as compared to traditional software, which allows cell division only in units of eight. This is advantageous as it allows the user to control cell division more succinctly. ART executes commands via colloquial English, and has built-in internal statistical programming that increases its ease of use. ART allows the user the choice of alternate variables such as temperature or pressure at will, which facilitates modeling unusual or unlikely occurrences.

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Self-Stabilizing, Byzantine-Fault-Tolerant Clock Synchronization System and Method

Initially developed for wired applications, the technology could also be applied to wireless systems. NASA’s Langley Research Center has developed a portfolio of technologies regarding clock synchronization in distributed systems. Distributed synchronous systems that need to provide globally coordinated operations require each component (node) in the system to be precisely synchronized. Such systems could include electronic components within an aircraft or automobile, or large-scale networks of components that communicate with each other (e.g. multiple aircraft or automobiles). NASA’s technologies provide for very quick synchronization while tolerating various faults. These protocols provide distributed autonomous synchronization (i.e. no master clock signal required) and do not rely on any assumptions regarding the initial state of the system or internal status of the nodes.

Posted in: Briefs, Software

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Method of Performing Computational Aeroelastic Analyses

This technology can be used for dynamic behavioral models of large buildings, bridges, dams, and towers. NASA’s Langley Research Center has developed unsteady aerodynamic Reduced-Order Models (ROMs) that significantly improve computational efficiency compared to traditional analyses of aeroelastic and other complex and unsteady systems. Traditional methods rely on the repetitive use of aeroelastic computational fluid dynamics (CFD) codes, and the iteration between the structural and nonlinear aerodynamic models of the aeroelastic CFD code for predicting the aeroelastic response of flight vehicles is very time-consuming and computationally expensive. The new ROMs are quite different from the traditional aeroelastic analysis tools, and enable the computational aeroelastic analysis of flight vehicles at a fraction of the time and cost.

Posted in: Briefs, Software

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Fourier Transform Spectrometer Performance Modeling

This software models the performance of a Fourier transform spectrometer (FTS). More specifically, it is able to add a number of noise/error sources to the interferogram and transform the errors back to the spectral domain.

Posted in: Briefs, Software

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Mesh Adaptation Module for Cartesian Meshes with Embedded Boundaries

Future applications include rapid prototyping, computer-based imaging and visualization, and semiconductor device modeling. This work extends the mesh generation capability of NASA’s Cart3D flow simulation software package to permit cell-by-cell mesh enrichment. Cart3D allows users to perform automated Computational Fluid Dynamics (CFD) analysis on a complex geometry. It includes utilities for geometry import, surface modeling and intersection, mesh generation, flow simulation, and post-processing of results. Geometry enters into Cart3D in the form of surface triangulations that may be generated from within Computer-Aided Design (CAD) packages, from legacy surface triangulations, or from structured surface grids. Cart3D uses adaptively refined Cartesian grids to discretize the space surrounding geometry, and cuts the geometry out of the set of cut-cells that actually intersects the surface triangulation.

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How to Manage Heat in Modular, COTS Enclosures

As components shrink, embedded systems have made their way into smaller and more mobile applications. Systems need to withstand more intense vibration, shock and EMI parameters and still function effectively. All of this affects the ruggedization of enclosures.

Posted in: White Papers, Defense, Electronics, Manufacturing & Prototyping

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New Phosphors and Next-Generation Lighting

Researchers from KU Leuven in Belgium, the University of Strasbourg, and CNRS have discovered a new phosphor that could make next-generation fluorescent and LED lighting even cheaper and more efficient. The team used highly luminescent clusters of silver atoms and the porous framework of minerals known as zeolites. Silver clusters consist of just a few silver atoms and have remarkable optical properties. However, current applications are limited, because the clusters tend to aggregate into larger particles, thus losing the interesting optical properties. But researchers have found a way to keep the silver clusters apart by inserting them into the porous framework of zeolites. The result: stable silver clusters that maintain their unique optical properties. Zeolites are minerals that are either found in nature or produced synthetically on an industrial scale. The minerals have a very rigid and well-defined framework of small molecular-sized channels, pores, and cages. They're commonly used in domestic and industrial applications such as washing detergent and water treatment. Using advanced techniques, researchers found that the structural, electronic, and optical properties of the zeolites were strongly influenced by the silver clusters. That's how they discovered that the shape of the silver clusters is essential to obtain the right fluorescence properties. Professor Johan Hofkens explains: "Clusters of silver atoms can assemble into different shapes, including a line or a pyramid. This pyramid shape is what we need to obtain the best fluorescence properties. Heating up the silver ions in the zeolite framework makes them adopt this shape. Because they are 'trapped', as it were, in the cages of the zeolites, they can only form a pyramid with up to four silver atoms. That is exactly the shape and size in which the silver cluster emits the largest amount of fluorescent light, with an efficiency close to 100%." These findings have great potential for the development of next-generation fluorescent and LED lighting and for biological imaging. After all, the new phosphors not only emit a large amount of light, they are also cheap to produce.

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