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At least 253 records · Page 14

An Extensible, Interchangeable and Sharable Database Model for Improving Multidisciplinary Aircraft Design

Crucial to an efficient aircraft simulation-based design is a robust data modeling methodology for both recording the information and providing data transfer readily and reliably. To meet this goal, data modeling issues involved in the aircraft multidisciplinary design are first analyzed in this study. Next, an XML-based. extensible data object model for multidisciplinary aircraft design is constructed and implemented. The implementation of the model through aircraft databinding allows the design applications to access and manipulate any disciplinary data with a lightweight and easy-to-use API. In addition, language independent representation of aircraft disciplinary data in the model fosters interoperability amongst heterogeneous systems thereby facilitating data sharing and exchange between various design tools and systems.

Lin, Risheng↗

TRANSTRAIN: A program to compute strain transformations in composite materials

Over the years, the solid rocket motor community has made increasing use of composite materials for thermal and structural applications. This is particularly true of solid rocket nozzles, which have used carbon phenolic and, increasingly, carbon-carbon materials to provide structural integrity and thermal protection at the high temperatures encountered during motor burn. To evaluate the degree of structural performance of nozzles and their materials and to verify analysis models, many subscale and full-scale tests are run. These provide engineers with valuable data needed to optimize design and to analyze nozzle hardware. Included among these data are strains, pressures, thrust, temperatures, and displacements. Recent nozzle test hardware has made increasing use of strain gauges embedded in the carbon composite material to measure internal strains. In order to evaluate strength, these data must be transformed into strains along the fiber directions. The fiber-direction stresses can then be calculated. A computer program written to help engineers correctly manipulate the strain data into a form that can be used to evaluate structural integrity of the nozzle is examined.

Ahmed, Rafiq↗

Simulation of three-dimensional compressible viscous flow on the Illiac IV computer

Complicated three-dimensional viscous transonic flows about bodies at high angles of attack are solved on the Illiac IV computer. It is shown that certain approximate forms of the compressible Reynolds-averaged Navier-Stokes equations can be computed about realistic three-dimensional geometries with relative ease on the Illiac IV. The ease and efficiency with which this can be done depend on the approximations made in the basic equations, the choice of the numerical algorithm used for the solution, and the data-base system that controls the data management and identifies and manipulates the vectors. A pencil data-base system is found to be particularly suitable for the approximations and numerical method chosen to produce the results presented. In addition, some comparisons are made of computer predictions with experimental results for various lows about hemisphere-cylinders in both subsonic and supersonic free streams. The same viscous model and numerical model are used, showing good qualitative agreement in the location of separation lines and pressure distributions.

Pulliam, T. H.↗

In search of meta-knowledge

Development of an Intelligent Information System (IIS) involves application of numerous artificial intelligence (AI) paradigms and advanced technologies. The National Aeronautics and Space Administration (NASA) is interested in an IIS that can automatically collect, classify, store and retrieve data, as well as develop, manipulate and restructure knowledge regarding the data and its application (Campbell et al., 1987, p.3). This interest stems in part from a NASA initiative in support of the interagency Global Change Research program. NASA's space data problems are so large and varied that scientific researchers will find it almost impossible to access the most suitable information from a software system if meta-information (metadata and meta-knowledge) is not embedded in that system. Even if more, faster, larger hardware is used, new innovative software systems will be required to organize, link, maintain, and properly archive the Earth Observing System (EOS) data that is to be stored and distributed by the EOS Data and Information System (EOSDIS) (Dozier, 1990). Although efforts are being made to specify the metadata that will be used in EOSDIS, meta-knowledge specification issues are not clear. With the expectation that EOSDIS might evolve into an IIS, this paper presents certain ideas on the concept of meta-knowledge and demonstrates how meta-knowledge might be represented in a pixel classification problem.

Lopez, Antonio M., Jr.↗

Software for Displaying High-Frequency Test Data

An easy-to-use, intuitive computer program was written to satisfy a need of test operators and data requestors to quickly view and manipulate high-frequency test data recorded at the East and West Test Areas at Marshall Space Flight Center. By enabling rapid analysis, this program makes it possible to reduce times between test runs, thereby potentially reducing the overall cost of test operations. The program can be used to perform quick frequency analysis, using multiple fast- Fourier-transform windowing and amplitude options. The program can generate amplitude-versus-time plots with full zoom capabilities, frequency-component plots at specified time intervals, and waterfall plots (plots of spectral intensity versus frequency at successive small time intervals, showing the changing frequency components over time). There are options for printing of the plots and saving plot data as text files that can be imported into other application programs. The program can perform all of the aforementioned plotting and plot-data-handling functions on a relatively inexpensive computer; other software that performs the same functions requires computers with large amounts of power and memory.

Elmore, Jason L.↗

Comparison of modal test methods on the Voyager payload

A comparison of the performance of modern modal data analysis methods on test data from the Voyager Jupiter/Saturn payload is presented. Four different test/data-analysis combinations are compared - multiple-point sine excitation tests, single-point random-excitation tests using two different techniques of manipulating Fourier transform data, and a time-domain method for analyzing random data. Results indicate that all four methods can give comparable results. Of the four, the time-domain approach detects more modes in the test data and, at the same time, shows the greatest promise for reducing the time and cost of modal testing.

Hanks, B. R.↗

AOIPS - An interactive image processing system

The Atmospheric and Oceanographic Information Processing System (AOIPS) was developed to help applications investigators perform required interactive image data analysis rapidly and to eliminate the inefficiencies and problems associated with batch operation. This paper describes the configuration and processing capabilities of AOIPS and presents unique subsystems for displaying, analyzing, storing, and manipulating digital image data. Applications of AOIPS to research investigations in meteorology and earth resources are featured.

Bracken, P. A.↗

Video Guidance Sensor Flight Experiment Results

NASA's Marshall Space Flight Center flew on the STS-87 mission an active sensor system, the Video Guidance Sensor (VGS), to demonstrate its functioning in space and to collect performance data. The VGS was designed to provide near-range sensor data as part of an automatic rendezvous and docking system. The sensor determines the relative positions and attitudes between the active sensor and the passive target. The VGS uses laser diodes to illuminate retro-reflectors in the target, a solid-state camera to detect the return from the target, and a frame grabber and digital signal processor to convert the video information into the relative positions and attitudes. The system is designed to operate with the target within a relative azimuth of +/- 9.5 degrees and a relative elevation of +/- 7.5 degrees. The system will acquire and track the target within that field-of-view anywhere from 1.5 meters to 110 meters range, and is designed to acquire at relative attitudes of +/- 10 degrees in pitch and yaw and at any roll angle. The data is output from the sensor at 5 Hz, and the target and sensor software have been designed to permit two independent sensors to operate simultaneously (in order to allow for redundancy). The data from the flight experiment includes raw video data from the VGS camera, relative position and attitude measurements from the VGS to the target, independent hand-held laser ranges from the Shuttle Aft Flight Deck to the target, and Remote Manipulator System position data to correlate with the VGS data. The experiment was quite successful and returned much useful information. The experience gained from the design and flight of this experiment will lead to improved video sensors in the future.

Howard, Richard T.↗

The integration of a LANDSAT analysis capability with a geographic information system

The integration of LANDSAT data was achieved through the development of a flexible, compatible analysis tool and using an existing data base to select the usable data from a LANDSAT analysis. The software package allows manipulation of grid cell data plus the flexibility to allow the user to include FORTRAN statements for special functions. Using this combination of capabilities the user can classify a LANDSAT image and then selectivity merge the results with other data that may exist for the study area.

Nordstrand, E. A.↗

Improved Skin Friction Interferometer

An improved system for measuring aerodynamic skin friction which uses a dual-laser-beam oil-film interferometer was developed. Improvements in the optical hardware provided equal signal characteristics for each beam and reduced the cost and complexity of the system by replacing polarization rotation by a mirrored prism for separation of the two signals. An automated, objective, data-reduction procedure was implemented to eliminate tedious manual manipulation of the interferometry data records. The present system was intended for use in two-dimensional, incompressible flows over a smooth, level surface without pressure gradient, but the improvements discussed are not limited to this application.

Westphal, R. V.↗

Collection Of Software For Computer Graphics

Ames Research Graphics System (ARCGRAPH) collection of software libraries and software utilities assisting researchers in generating, manipulating, and visualizing graphical data. Defines metafile format containing device-independent graphical data. File format used with various computer-graphics-manipulation and -animation software packages at Ames, including SURF (COSMIC Program ARC-12381) and GAS (COSMIC Program ARC-12379). Consists of two-stage "pipeline" used to put out graphical primitives. ARCGRAPH libraries developed on VAX computer running VMS.

Hibbard, Eric A.↗

Stackfile Database

This software provides storage retrieval and analysis functionality for managing satellite altimetry data. It improves the efficiency and analysis capabilities of existing database software with improved flexibility and documentation. It offers flexibility in the type of data that can be stored. There is efficient retrieval either across the spatial domain or the time domain. Built-in analysis tools are provided for frequently performed altimetry tasks. This software package is used for storing and manipulating satellite measurement data. It was developed with a focus on handling the requirements of repeat-track altimetry missions such as Topex and Jason. It was, however, designed to work with a wide variety of satellite measurement data [e.g., Gravity Recovery And Climate Experiment -- GRACE). The software consists of several command-line tools for importing, retrieving, and analyzing satellite measurement data.

deVarvalho, Robert↗

Integrating computer programs for engineering analysis and design

The design of a third-generation system for integrating computer programs for engineering and design has been developed for the Aerospace Vehicle Interactive Design (AVID) system. This system consists of an engineering data management system, program interface software, a user interface, and a geometry system. A relational information system (ARIS) was developed specifically for the computer-aided engineering system. It is used for a repository of design data that are communicated between analysis programs, for a dictionary that describes these design data, for a directory that describes the analysis programs, and for other system functions. A method is described for interfacing independent analysis programs into a loosely-coupled design system. This method emphasizes an interactive extension of analysis techniques and manipulation of design data. Also, integrity mechanisms exist to maintain database correctness for multidisciplinary design tasks by an individual or a team of specialists. Finally, a prototype user interface program has been developed to aid in system utilization.

Wilhite, A. W.↗

An investigation of the relationship between tree water potential and dielectric constant

An experiment that has been performed to verify the relationship between the dielectric constant of several tree species and their respective water potentials is described. The water potential, xylem flow and dielectric properties of five tree species were continuously monitored while simultaneously manipulating canopy transpiration and water status. An analysis of the data recorded during these manipulations is presented. Results of this analysis demonstrate a clear coincidence of change in dielectric constant and water status. The implication of this relationship for the utilization of remotely sensed data to study canopy water relations is explored. Preliminary backscatter modeling results demonstrate that the changes in dielectric constant that occur as a result of changes in water status are significant enough to be observable with microwave radar.

Mcdonald, Kyle C.↗

Aircraft stress sequence development: A complex engineering process made simple

Development of stress sequences for critical aircraft structure requires flight measured usage data, known aircraft loads, and established relationships between aircraft flight loads and structural stresses. Resulting cycle-by-cycle stress sequences can be directly usable for crack growth analysis and coupon spectra tests. Often, an expert in loads and spectra development manipulates the usage data into a typical sequence of representative flight conditions for which loads and stresses are calculated. For a fighter/trainer type aircraft, this effort is repeated many times for each of the fatigue critical locations (FCL) resulting in expenditure of numerous engineering hours. The Aircraft Stress Sequence Computer Program (ACSTRSEQ), developed by Southwest Research Institute under contract to San Antonio Air Logistics Center, presents a unique approach for making complex technical computations in a simple, easy to use method. The program is written in Microsoft Visual Basic for the Microsoft Windows environment.

Schrader, K. H.↗

Users Guide to the JPL Doppler Gravity Database

Local gravity accelerations and gravimetry have been determined directly from spacecraft Doppler tracking data near the Moon and various planets by the Jet Propulsion Laboratory. Researchers in many fields have an interest in planet-wide global gravimetric mapping and its applications. Many of them use their own computers in support of their studies and would benefit from being able to directly manipulate these gravity data for inclusion in their own modeling computations. Pubication of some 150 Apollo 15 subsatellite low-altitude, high-resolution, single-orbit data sets is covered. The doppler residuals with a determination of the derivative function providing line-of-sight-gravity are both listed and plotted (on microfilm), and can be ordered in computer readable forms (tape and floppy disk). The form and format of this database as well as the methods of data reduction are explained and referenced. A skeleton computer program is provided which can be modified to support re-reductions and re-formatted presentations suitable to a wide variety of research needs undertaken on mainframe or PC class microcomputers.

Muller, P. M.↗

Comparing Level-2 and Level-3 Satellite Ocean Color Retrieval Validation Methodologies

Many ocean color data applications leverage global spatially composited Level-3(L3) satellite data, because of their regular Earth-grid frame of reference. However, ocean color satellite retrieval performance is routinely evaluated on Level-2 (L2) data at the native satellite swath resolution and geometries. This study assesses how accurately binned and gridded L3 data represent L2 satellite data products via satellite-to-in situ match-up activities.L2 and L3 satellite data retrievals of the photosynthetic pigment chlorophyll-a are compared with a common in situ data set, revealing similar L2 and L3 satellite-to-in situ performance for both MODIS-Aqua and VIIRS-SNPP. This agreement implies that L2 validation results are generally applicable to L3 data. However, uncertainties are introduced during the generation of L3 data from L2 data. L3 data comparisons introduce a wider temporal window between the time of in situ measurement and the time of the satellite observation, which can unintentionally reflect on the quality of the satellite retrieval or algorithm performance. The choice of L3 map projection may introduce additional uncertainty by spatially distorting the true location of the satellite retrievals. Each manipulation of satellite data beyond theinstrument's native spatio temporal reference (L2) reduces the applicability of L2 validation results to higher data processing levels.

Ocean Color↗

Packaging printed circuit boards: A production application of interactive graphics

The structure and use of an Interactive Graphics Packaging Program (IGPP), conceived to apply computer graphics to the design of packaging electronic circuits onto printed circuit boards (PCB), were described. The intent was to combine the data storage and manipulative power of the computer with the imaginative, intuitive power of a human designer. The hardware includes a CDC 6400 computer and two CDC 777 terminals with CRT screens, light pens, and keyboards. The program is written in FORTRAN 4 extended with the exception of a few functions coded in COMPASS (assembly language). The IGPP performs four major functions for the designer: (1) data input and display, (2) component placement (automatic or manual), (3) conductor path routing (automatic or manual), and (4) data output. The most complex PCB packaged to date measured 16.5 cm by 19 cm and contained 380 components, two layers of ground planes and four layers of conductors mixed with ground planes.

Perrill, W. A.↗