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Organizing Compression of Hyperspectral Imagery to Allow Efficient Parallel Decompression

Higher compression factors can be attained. A family of schemes has been devised for organizing the output of an algorithm for predictive data compression of hyperspectral imagery so as to allow efficient parallelization in both the compressor and decompressor. In these schemes, the compressor performs a number of iterations, during each of which a portion of the data is compressed via parallel threads operating on independent portions of the data. The general idea is that for each iteration it is predetermined how much compressed data will be produced from each thread.

Posted in: Briefs, TSP, Electronics & Computers

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Protograph-Based Raptor-Like Codes

The proposed codes have the advantage of low-complexity encoder and decoder implementation. Theoretical analysis has long indicated that feedback improves the error exponent but not the capacity of point-to-point memoryless channels. The analytic and empirical results indicate that at short blocklength regime, practical rate-compatible punctured convolutional (RCPC) codes achieve low latency with the use of noiseless feedback. In 3GPP, standard rate-compatible turbo codes (RCPT) did not outperform the convolutional codes in the short blocklength regime. The reason is the convolutional codes for low number of states can be decoded optimally using Viterbi decoder. Despite excellent performance of convolutional codes at very short blocklengths, the strength of convolutional codes does not scale with the blocklength for a fixed number of states in its trellis.

Posted in: Briefs, Electronics & Computers

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Data Quality Screening Service

A report describes the Data Quality Screening Service (DQSS), which is designed to help automate the filtering of remote sensing data on behalf of science users. Whereas this process often involves much research through quality documents followed by laborious coding, the DQSS is a Web Service that provides data users with data pre-filtered to their particular criteria, while at the same time guiding the user with filtering recommendations of the cognizant data experts.

Posted in: Briefs, TSP, Electronics & Computers

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Spatial Statistical Data Fusion (SSDF)

The approach models the spatial covariance function of the underlying geophysical field using linear combinations of multi-resolution spatial basis functions of low dimensionality. As remote sensing for scientific purposes has transitioned from an experimental technology to an operational one, the selection of instruments has become more coordinated, so that the scientific community can exploit complementary measurements. However, technological and scientific heterogeneity across devices means that the statistical characteristics of the data they collect are different. The challenge addressed here is how to combine heterogeneous remote sensing data sets in a way that yields optimal statistical estimates of the underlying geophysical field, and provides rigorous uncertainty measures for those estimates. Different remote sensing data sets may have different spatial resolutions, different measurement error biases and variances, and other disparate characteristics.

Posted in: Electronics & Computers, Briefs, Electronics & Computers, Data Acquisition

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Commercial Non-Dispersive Infrared Spectroscopy Sensors for Sub-Ambient Carbon Dioxide Detection

Carbon dioxide produced through respiration can accumulate rapidly within closed spaces. If not managed, a crew’s respiratory rate increases, head aches and hyperventilation occur, vision and hearing are affected, and cognitive abilities decrease. Consequently, development continues on a number of CO2 removal technologies for human spacecraft and spacesuits. Terrestrially, technology development requires precise performance characterization to qualify promising air revitalization equipment. Onorbit, instrumentation is required to identify and eliminate unsafe conditions. This necessitates accurate in situ CO2 detection.

Posted in: Briefs, TSP

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Predicting Aircraft Ice Formation with Simulation

Using simulation during the design process maintains safety and reduces testing costs. Aircraft performance can be compromised when ice forms on aircraft surfaces such as the wings, nacelles, sensors, and control systems. This can cause safety issues due to significant changes in the aerodynamic performance of the aircraft if larger pieces of ice detach and strike other parts of the aircraft, if they enter the engine causing damage, or if sensors begin to malfunction.

Posted in: Briefs

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Educational NASA Computational and Scientific Studies (enCOMPASS)

This project bridges the gap between computational objectives and needs of NASA’s scientific research, missions, and projects, and academia’s latest advances in applied mathematics and computer science. Educational NASA Computational and Scientific Studies (enCOMPASS) is an educational project of NASA Goddard Space Flight Center aimed at bridging the gap between computational objectives and needs of NASA’s scientific research, missions, and projects, and academia’s latest advances in applied mathematics and computer science. enCOMPASS achieves this goal via bidirectional collaboration and communication between NASA and academia. Using developed NASA Computational Case Studies in university computer science/engineering and applied mathematics classes is a way of addressing NASA’s goals of contributing to the Science, Technology, Education, and Math (STEM) National Objective. The enCOMPASS Web site at http://encompass.gsfc.nasa.gov provides additional information.

Posted in: Briefs, TSP

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