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Development of Free Molecule Flow Equations from a Transient, Asymmetric Source

Molecular flow model is explored as a tool to describe an unusual variety of plume interaction issues. Goddard Space Flight Center, Greenbelt, Maryland The analysis and simulation of gases expanding from sources such as rocket nozzles into vacuum, or the effects plumes from these sources create when they interact with solid surfaces, present a considerable challenge to the scientific and engineering communities. As a plume expands into vacuum, density levels, and hence collision rates, decrease rapidly by many orders of magnitude. The main difficulty lies in accurately describing a flow field extending from continuum flow at the nozzle exit, through the transition regime, and reaching free molecule behavior within a relatively short distance downstream. For thrusters, flow at the nozzle exit is usually characterized by high exit velocities and relatively high Mach numbers. Even in regions where significant intermolecular collision rates occur, relative velocity levels are low, and little thermal scattering occurs normal to the mainly radial streamlines. Such observations lead one to consider describing the expansion under certain circumstances using free molecule theory.

Posted in: Briefs, TSP, Electronics & Computers

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Formal Validation of Model-Based Fault Management Design Solutions

A number of advantages of modeling fault protection logical design, executing the model, and running a model checker are identified. NASA’s Jet Propulsion Laboratory, Pasadena, California Model-Based System Engineering is becoming widely adopted at JPL and in industry because model-centric systems introduce improved methods of system engineering. As systems with ever-increasing complexity are developed at JPL, model-centric engineering be comes essential for design, test, and validation. Validation of FP designs is historically problematic, with many examples of inadequate resources (people, time, and budget) and/or unexpected problems. Many factors contribute to these issues, but the problem can be traced to a lack of appreciation of system complexity. When considering a system, there are significantly more ways the system can fail (contingency paths) than ways it can succeed (nominal paths). As NASA continues to develop more complex and capable spacecraft, the behavior state space will increase, stressing the ability of teams to properly understand system behavior.

Posted in: Briefs, TSP, Electronics & Computers

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Fast Block Transforms on Large Binary Datasets in the Cloud Using Hadoop Streaming

NASA’s Jet Propulsion Laboratory, Pasadena, California A software framework on top of Hadoop Streaming enables both the processing of binary data in the cloud, and the freedom for the developer to implement his or her mapper and reducer programs in any language, rather than re-implementing existing solutions in Java, or repackaging existing binary data into a text format. Binary data is partitioned into chunks that are kept in a persistent data storage medium. A textual list of filenames for these chunks is piped into a Hadoop Streaming mapper program, which then reads the corresponding files, computes block transforms locally, and writes the results back to persistent data storage. The mapper program is stored on all compute nodes, and the filenames are distributed in parallel across the cluster, so that the workload is evenly distributed and the end-to-end block transform speedup is roughly given by the number of nodes in the cluster.

Posted in: Briefs, TSP, Electronics & Computers

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Web Application: Ground Hardware Management Tool

John F. Kennedy Space Center, Florida An integrated ground support equipment (GSE) tracking and management tool is designed for tracking and managing GSE data used in support of KSC/Ground Systems Development and Operations (GSDO) planning and launch campaigns. This software (the Ground Hardware Management Tool, GHMT) will be fully integrated with the Ground Operations Planning Database (GOPDb) to provide a complete ground operations planning solution.

Posted in: Briefs, Electronics & Computers

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Bird Vision System

This system is applicable to commercial airports and military airfields where the likelihood of bird strikes is high, and for environmental studies. John F. Kennedy Space Center, Florida About 2.5 seconds after the launch of STS-114, the first Return to Flight launch after the Columbia accident, a large bird struck the external tank and fell into the exhaust plume. While this particular bird strike did not threaten the vehicle because it did not strike the orbiter, it did raise awareness of the threat of avian fauna present at launch. In response to the avian threat, a Bird Radar system was developed to detect birds above the launch pad. Because of interference with launch systems, the radar system could not span closer than a few hundred feet above the pad. There was a gap region that would not be visible with the radar.

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Fully Implicit Ablation and Thermal Analysis Program, Version 3 (FIAT v3)

The program is very stable and robust for application to both robotic and crewed vehicles entering a planetary atmosphere from space. Ames Research Center, Moffett Field, California FIAT v3 simulates one-dimensional thermal energy transport through a multilayer stack of thermal protection materials, bonding materials, metallic or composite structures, air gaps, and/or insulations. The outer surface encounters aerothermal heating from hypersonic flow, and the inner surface may have various boundary conditions such as assigned temperature history, insulated, or convective cooling. The heated outer surface can ablate, and materials can decompose (pyrolyze) in-depth.

Posted in: Briefs, Electronics & Computers

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CFD Utility Software Library

Ames Research Center, Moffett Field, California Originating as the Aerodynamics Division Software Library of the 1980s and -90s, this software is a collection of more than 100 software applications, many of them for manipulating the grids and flow solutions associated with computational fluid dynamics (CFD). Underlying these applications are about 30 libraries containing more than 1,200 subroutines, functions, or modules, mostly written in Fortran [90] with a small collection of C translations. Wherever possible, the software is generalized with reuse and portability in mind. These tools often operate on files in PLOT3D and/or Tecplot format, which represent de facto standards at many sites within academia, NASA, and industry. Utilities for treating unstructured data are also included along with a collection of programming tools for manipulating character data. Library names such as geomlib, interplib, optlib, and searchlib suggest the scope of numerics covered, while I/O packages such as tecplot_io, triangulation_io, and xyzq_io can ease development of new applications.

Posted in: Briefs, Electronics & Computers

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