Tech Briefs

Multicore ROCKSTER

NASA’s Jet Propulsion Laboratory, Pasadena, California ROCKSTER (Rock Segmentation Through Edge Regrouping) is a rock detection algorithm that analyzes 2D geologic scenes and identifies rocks and other targets of interest. A multicore ROCKSTER enables long-range autonomous rover traverse science to be performed efficiently and to make use of multicore or parallel computing capabilities.

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Non-Binary Protograph-Based LDPC Codes with Near-Capacity Thresholds

Protograph methods allow the design of LDPC codes that are modular, easy to encode, and have excellent performance. NASA’s Jet Propulsion Laboratory, Pasadena, California Binary protograph codes are state-of-the-art codes over the binary field Galois Field GF(2). These codes were invented by JPL in 2003 and proposed to CCSDS (Consultative Committee for Space Data Systems) recently as a channel-coding standard for space communications. It is expected that the proposed codes for non-binary signaling such as M-PSK (M-ary phase-shift keying), M-QAM (multi-level quadrature amplitude modulation), and PPM (pulse position modulation) will have better performance. The predicted advantage is based on gap to capacity, larger minimum distance based on GV bound, and larger girth in their graph representation for improved iterative decoding performance. Similar to Reed-Solomon codes (RS is a non-binary code but cannot be soft-decoded using BP (Belief Propagation), these codes will outperform the binary protograph codes on burst error and burst era-sure channels.

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Dynamically Configurable Pipeline

Hardware resource utilization is increased and power consumption is reduced. Lyndon B. Johnson Space Center, Houston, Texas The Dynamically Configurable Pipeline is a concept for the rapid implementation of pipelined computational algorithms in configurable hardware such as field programmable gate arrays (FPGAs). The approach, especially in its phase-coherent incarnation, allows a high level of sharing of floating-point resources among multiple computations. The concept features a simple tag-based control scheme and a sparse-pipeline allocation approach that enables all the stages of an arithmetic pipeline to be processing simultaneously, with multiple computations allocated to the same pipeline. Thus, the approach increases hardware resource utilization and reduces power consumption.

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Frame Synchronization Without Attached Sync Markers

A means has been developed to detect the positions of code words directly. NASA’s Jet Propulsion Laboratory, Pasadena, California In communications systems, there must be a method to identify the beginning of a message at the receiving end, to know when the data stream of a specified structure begins. This is conventionally done by inserting attached sync markers (ASMs) between codewords, and looking for these ASMs in the transmitted data. Instead, a means has been developed to detect the positions of codewords directly, using the decoder to partially process a decoder attempt at each candidate synchronization position. A short decoding operation can successfully synchronize codewords in about two seconds in software.

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Scalable ParaView for Extreme Scale Visualization

Goddard Space Flight Center, Greenbelt, Maryland Work has been focused on identifying bottlenecks in visualization pipelines that make the visualization and analysis of large datasets in real time difficult to attain. The innovators leveraged ParaView, an open-source visualization application and framework, to provide custom solutions for users of NASA’s high-performance computing (HPC) resources instead of conducting high-risk research. Issues regarding different types of data (grid-based and particle-based) have been addressed, and overheads dealing with challenging multivariate data from global 3D full particle simulations were addressed by working closely with ParaView users.

Posted in: Briefs, TSP, Electronics & Computers, Simulation Software

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Explicit Filtering Leading to Grid-Spacing-Independent and Discretization-Order-Independent Large Eddy Simulation Solutions

Two-phase volumetrically dilute flow with evaporation is addressed. NASA’s Jet Propulsion Laboratory, Pasadena, California Numerical simulations for turbulent flows using the most promising methodology, Large Eddy Simulation (LES), are grid-spacing and discretization-order dependent. This means that the solution is not trustworthy and cannot be compared with experiments to determine the validity of the mathematical model.

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Explicit Filtering Leading to Grid-Independent and Discretization-Order-Independent Large Eddy Simulation

The re-formulation involves explicit filtering of the conservation equations. NASA’s Jet Propulsion Laboratory, Pasadena, California To validate simulations, one must trust that they are independent of the numerical aspects. A very promising, relatively new methodology for simulating turbulent flows, called Large Eddy Simulation (LES), has some issues in this respect. The issues stem from the aspect that modeling and numerics are totally intertwined, resulting in the fact that the results are grid-dependent and discretization-order-dependent. These issues were described in the preceding article. These issues prevent LES validation with experiments since one can always make adjustments to agree with data, which is not validation.

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