Integrated System Health Management Development Toolkit

This software toolkit is designed to model complex systems for the implementation of embedded Integrated System Health Management (ISHM) capability, which focuses on determining the condition (health) of every element in a complex system (detect anomalies, diagnose causes, and predict future anomalies), and to provide data, information, and knowledge (DIaK) to control systems for safe and effective operation.

Posted in: Briefs, Information Sciences, Computer software and hardware, On-board diagnostics, On-board diagnostics (OBD), Systems management

TCP/IP Interface for the Satellite Orbit Analysis Program (SOAP)

The Transmission Control Protocol/Internet protocol (TCP/IP) interface for the Satellite Orbit Analysis Program (SOAP) provides the means for the software to establish real-time interfaces with other software. Such interfaces can operate between two programs, either on the same computer or on different computers joined by a network. The SOAP TCP/IP module employs a client/server interface where SOAP is the server and other applications can be clients. Real-time interfaces between software offer a number of advantages over embedding all of the common functionality within a single program. One advantage is that they allow each program to divide the computation labor between processors or computers running the separate applications. Secondly, each program can be allowed to provide its own expertise domain with other programs able to use this expertise.

Posted in: Briefs, Information Sciences, Architecture, Communication protocols, Computer software and hardware, Satellites

High-Performance Algorithm for Solving the Diagnosis Problem

Computation time is reduced substantially.

An improved method of model-based diagnosis of a complex engineering system is embodied in an algorithm that involves considerably less computation than do prior such algorithms. This method and algorithm are based largely on developments reported in several NASA Tech Briefs articles: “The Complexity of the Diagnosis Problem” (NPO-30315), Vol. 26, No. 4 (April 2002), page 20; “Fast Algorithms for Model-Based Diagnosis” (NPO-30582), Vol. 29, No. 3 (March 2005), page 69; “Two Methods of Efficient Solution of the Hitting-Set Problem” (NPO-30584), Vol. 29, No. 3 (March 2005), page 73; and “Efficient Model-Based Diagnosis Engine” (NPO-40544), on the following page.

Posted in: Briefs, TSP, Information Sciences, Mathematical models, Diagnosis, Prognostics

Efficient Method for Optimizing Placement of Sensors

This systematic method supplants ad hoc placement and exhaustive-search optimization methods.

A computationally efficient method has been developed to enable optimization of the placement of sensors for the purpose of diagnosis of a complex engineering system (e.g., an aircraft or spacecraft). The method can be used both in (1) designing a sensor system in which the number and positions of sensors are initially not known and must be determined and (2) adding sensors to a pre-existing system to increase the diagnostic capability.

Posted in: Briefs, TSP, Information Sciences, Optimization, Sensors and actuators

Truncation Depth Rule-of-Thumb for Convolutional Codes

The new rule is more accurate and tight at high signal-to-noise ratios.

In this innovation, it is shown that a commonly used rule of thumb (that the truncation depth of a convolutional code should be five times the memory length, m, of the code) is accurate only for rate 1/2 codes. In fact, the truncation depth should be 2.5 m/(1 – r), where r is the code rate. The accuracy of this new rule is demonstrated by tabulating the distance properties of a large set of known codes. This new rule was derived by bounding the losses due to truncation as a function of the code rate.

Posted in: Briefs, TSP, Information Sciences, Mathematical models, Product development

Multibeam Altimeter Navigation Update Using Faceted Shape Model

The model is applicable to a body having almost any complex shape.

A method of incorporating information, acquired by a multibeam laser or radar altimeter system, pertaining to the distance and direction between the system and a nearby target body, into an estimate of the state of a vehicle upon which the system is mounted, involves the use of a faceted model to represent the shape of the target body. In the original intended application, the vehicle would be a spacecraft and the target body would be an asteroid, comet, or similar body that the spacecraft was required to approach. The method could also be used in navigating aircraft at low altitudes over terrain that is rough and/or occupied by objects of significant structure.

Posted in: Briefs, Information Sciences, Mathematical models, Altimeters, Flight guidance systems, Lasers, Radar

MODIS Atmospheric Data Handler

A number of science data sets are derived from the observations of the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard NASA’s Terra and Aqua satellites. These data typically contain information on retrieval techniques, quality-control flags, and geo-referencing information. These datasets, distributed in HDF (Hierachical Data Format), must be further processed to extract relevant information for weather analysis studies and numerical models input. The MODIS-Atmosphere Data Handler software converts the HDF data to ASCII format, and outputs: (1) atmospheric profiles of temperature and dew point and (2) total precipitable water. Quality-control data are also considered in the export procedure.

Posted in: Briefs, Information Sciences, Imaging and visualization, Data management, Quality control, Satellites

Reducing Surface Clutter in Cloud Profiling Radar Data

Radar data can be processed to study clouds closer to the surface.

An algorithm has been devised to reduce ground clutter in the data products of the CloudSat Cloud Profiling Radar (CPR), which is a nadir-looking radar instrument, in orbit around the Earth, that measures power backscattered by clouds as a function of distance from the instrument. Ground clutter contaminates the CPR data in the lowest 1 km of the atmospheric profile, heretofore making it impossible to use CPR data to satisfy the scientific interest in studying clouds and light rainfall at low altitude.

Posted in: Briefs, Information Sciences, Mathematical models, Radar, Test equipment and instrumentation

Specialized Color Function for Display of Signed Data

This Mathematica script defines a color function to be used with Mathematica’s plotting modules for differentiating data attaining both positive and negative values. Positive values are shown as shades of blue, and negative values are shown in red. The intensity of the color reflects the absolute value of the data value.

Posted in: Briefs, Information Sciences, Mathematical models, Displays, Identification

Spatial and Temporal Low-Dimensional Models for Fluid Flow

A document discusses work that obtains a low-dimensional model that captures both temporal and spatial flow by constructing spatial and temporal four-mode models for two classic flow problems. The models are based on the proper orthogonal decomposition at two reference Reynolds numbers. Model predictions are made at an intermediate Reynolds number and compared with direct numerical simulation results at the new Reynolds number.

Posted in: Briefs, TSP, Information Sciences, Simulation and modeling

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