Electrical/Electronics

Anomaly Detection in Large Sets of High-Dimensional Symbol Sequences (sequenceMiner)

Ames Research Center, Moffett Field, California SequenceMiner was developed to address the problem of detecting and describing anomalies in large sets of high-dimensional symbol sequences. sequenceMiner works by performing unsupervised clustering (grouping) of sequences using the normalized longest common subsequence (LCS) as a similarity measure, followed by a detailed analysis of outliers to detect anomalies. sequenceMiner utilizes a new hybrid algorithm for computing the LCS that has been shown to outperform existing algorithms by a factor of five. sequenceMiner also includes new algorithms for outlier analysis that provide comprehensible indicators as to why a particular sequence was deemed to be an outlier. This provides analysts with a coherent description of the anomalies identified in the sequence, and why they differ from more normal sequences.

Posted in: Briefs

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Time-Scaled Activity Diagram Simulator

NASA’s Jet Propulsion Laboratory, Pasadena, California The Time-Scaled Activity Diagram Simulator software simulates and animates time-tagged events as an overlay on activity and internal block diagrams in MagicDraw as a plugin application. “Events” are quite generic and include atomic actions, compound actions, signal and message exchanges, invocations, and more. Events are specified in a schedule in a text file, which is ingested by the plug-in application. Concurrent and synchronized execution specified in the event schedule is illustrated within and across diagrams. Events correspond to nodes and edges of hierarchical activity models and corresponding structural decomposition. This software can be used to visually communicate the execution and timeline of any collection of scheduled events, including business, software, and spacecraft processes and procedures, and is applicable to most if not all missions.

Posted in: Briefs

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General-Use Nodal Network Solver (GUNNS)

GUNNS is a flow system modeling software package that combines nodal analysis and the hydraulic-electric analogy to simulate fluid, electrical, and thermal systems. Lyndon B. Johnson Space Center, Houston, Texas Crewed space vehicle training has always required highfidelity models of vehicle systems. Many of these systems, particularly of the “flow” variety, benefit from modeling the system as a whole, rather than relying only on the interactions between individual components. In general, system properties (temperatures, voltages, flow rates, etc.) are modeled both internal to and between physical components (valves, batteries, etc.). Lacking knowledge of the system atlarge, integration of flows between individual components is extremely difficult without incurring model instability and errors. The same analogous problem applies among fluid, thermal, and electrical systems. Nodal analysis is a method commonly used in industry to avoid this problem by representing these systems as a simultaneous system of equations.

Posted in: Briefs, TSP

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Modularized SIR-to-NetCDF Conversion Command-Line Tool

NASA’s Jet Propulsion Laboratory, Pasadena, California This innovation reads in a proprietary formatted binary data format known as Scatterometer Image Reconstruction (SIR), and converts these data files to netCDF-classic format. This software is provided as a command-line tool for Linux/UNIX-based systems, and includes built-in regression testing and command line options. The software is configured to output the netCDF files using a metadata conformance to Attribute Convention for Dataset Discovery (ACDD) and Climate and Forecasting (CF) version 1.6. This software is initially tested and designed for SIR files created for datasets originating from QuikSCAT and SeaWinds on ADEOS-II.

Posted in: Briefs

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Optimizing Performance with Technology Embedded Apparel

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Posted in: White Papers

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Fault Recovery for Multi-Phase Power Converters

This method has application in power converters for thin film deposition to prevent loss of expensive silicon wafer products. John H. Glenn Research Center, Cleveland, Ohio A fault recovery method for multiphase power converters enables delivery of reduced output power of as much as 66% of normal power in the event of a shorted power switch component. The need for redundant power converters in conventional multi-phase space power systems is reduced, if not eliminated. Fault recovery includes detecting a shorted power switch fault, providing short circuit current protection, providing isolation of the shorted power switch, and reconfiguring the remaining undamaged power switches.

Posted in: Briefs, TSP, Power Management

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Isolated Bidirectional DC Converters for Distributed Battery Energy Applications

This development is applicable to electric propulsion systems of vehicles. John H. Glenn Research Center, Cleveland, Ohio Power systems are the core heartbeat of any advanced vehicle. Reliability and flexibility of these systems are of the highest priority. This innovation is a highly efficient and modular isolated bidirectional DC converter for battery energy applications that has been translated into high-priority NASA power system applications, demonstrating transferability, robustness, and scalability.

Posted in: Briefs, TSP, Power Management

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