Tech Briefs

SIVO-PyD: A Python Distribution for Scientific Computing Visualization

Goddard Space Flight Center, Greenbelt, Maryland SIVO-PyD gathers and automatically installs (in various computing platforms) a collection of Python-related packages for scientific computing and visualization. All of the packages in distribution are accessible within the Python framework. The distribution is self-contained and can be extended with minimal work.

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iPhone App to Facilitate Airborne Radar Operations

NASA’s Jet Propulsion Laboratory, Pasadena, California The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is an Earth imaging radar that flies on a Gulf-Stream Jet. Its mission is to collect data for NASA scientists who are using Synthetic Aperture Radar to develop methods for monitoring changes in the Earth’s surface. As with many other technologies, there is always the possibility of technological or human errors. Since smartphones are mobile, common, and powerful devices, they can be used to reduce the possibility of operator error when the radar is being configured for flight.

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Spherical Empirical Mode Decomposition

Goddard Space Flight Center, Greenbelt, Maryland The spherical empirical mode decomposition algorithm is an adaptation in the spherical space of the 2D empirical mode decomposition in Euclidian space. This algorithm is a signal analysis method for any spherical data, such as orbital measurements. The two primary advantages of this innovation are the absence of edge effects in the results, and the computational efficiency of the processing.

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Database Design for Storing Software Entity Metadata, User Identification, and License Terms

NASA’s Jet Propulsion Laboratory, Pasadena, California The NASA Space Telecommunications Radio System (STRS) specification cites a plan for an application repository, similar to an “app store,” but with a wide variety of licensing restrictions on access to different applications, and even different parts of an application package (for instance, wide access to descriptive documentation but limited access to source code). A method is needed to coordinate application artifact storage, license terms, and user access rights.

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Geometry Manipulation Protocol for CFD Applications, V1.0

Ames Research Center, Moffett Field, California Geometry Manipulation Protocol (GMP) is a library that serializes data types between XML and ANSI C data structures to support computational fluid dynamics (CFD) applications. This library currently provides a description of geometric configurations, general moving-body scenarios (prescribed and/or 6-DOF), and control surface settings. The interface consists of a general set of datatypes, along with rules for their interaction, and is designed to be flexible in order to evolve as future needs dictate. The specification is currently implemented with an XML file format, which is portable across platforms and applications. The motion specification is capable of describing general rigid body motions, and eliminates the need to write and compile new code within the application software for each dynamic configuration, allowing client software to automate dynamic simulations.

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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.

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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.

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