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At least 1,405 records · Page 78

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NASA NTRS1985

Space Station Advanced Development Program

The Space Station Advanced Development Program has the objective to transform promising new techniques into mature proven concepts to enable design options for the initial Space Station. It is pointed out that the options should improve system performance and reduce operational costs. Attention is given to the approach employed in the implementation of the program, the technology issues, aspects of Space Station evolution and growth, a Space Station technology overview, and subsystem technologies. The Advanced Development Power Program is considered along with the advanced development of auxiliary propulsion, the program dealing with attitude control and stabilization, and developments related to data management. Other developments are concerned with communication, system operation, manned systems technology, structures, and environmental control and life support.

Carlisle, R. F.↗

NASA NTRS1985

The Caltech Concurrent Computation Program - Project description

The Caltech Concurrent Computation Program wwhich studies basic issues in computational science is described. The research builds on initial work where novel concurrent hardware, the necessary systems software to use it and twenty significant scientific implementations running on the initial 32, 64, and 128 node hypercube machines have been constructed. A major goal of the program will be to extend this work into new disciplines and more complex algorithms including general packages that decompose arbitrary problems in major application areas. New high-performance concurrent processors with up to 1024-nodes, over a gigabyte of memory and multigigaflop performance are being constructed. The implementations cover a wide range of problems in areas such as high energy and astrophysics, condensed matter, chemical reactions, plasma physics, applied mathematics, geophysics, simulation, CAD for VLSI, graphics and image processing. The products of the research program include the concurrent algorithms, hardware, systems software, and complete program implementations.

Fox, G.↗

NASA NTRS1987

Star-Tracker Computer Program

Image-analyzing pointing systems aimed to high precision. Star-tracker program, STRACKER, developed to solve algorithm-design problems for area-array tracking and pointing systems operating at accuracies of 0.001 to 0.01 picture element. Includes auxiliary programs for reformatting point-spread data from commercial ACCOSV lens-design program. Other optical-analysis program data reformatted by use of utility routines included in package. Written in FORTRAN 77.

Glavich, Thomas↗

NASA NTRS1986

Alternative mathematical programming formulations for FSS synthesis

A variety of mathematical programming models and two solution strategies are suggested for the problem of allocating orbital positions to (synthesizing) satellites in the Fixed Satellite Service. Mixed integer programming and almost linear programming formulations are presented in detail for each of two objectives: (1) positioning satellites as closely as possible to specified desired locations, and (2) minimizing the total length of the geostationary arc allocated to the satellites whose positions are to be determined. Computational results for mixed integer and almost linear programming models, with the objective of positioning satellites as closely as possible to their desired locations, are reported for three six-administration test problems and a thirteen-administration test problem.

Reilly, C. H.↗

NASA NTRS1987

Surface flaw reliability analysis of ceramic components with the SCARE finite element postprocessor program

The SCARE (Structural Ceramics Analysis and Reliability Evaluation) computer program on statistical fast fracture reliability analysis with quadratic elements for volume distributed imperfections is enhanced to include the use of linear finite elements and the capability of designing against concurrent surface flaw induced ceramic component failure. The SCARE code is presently coupled as a postprocessor to the MSC/NASTRAN general purpose, finite element analysis program. The improved version now includes the Weibull and Batdorf statistical failure theories for both surface and volume flaw based reliability analysis. The program uses the two-parameter Weibull fracture strength cumulative failure probability distribution model with the principle of independent action for poly-axial stress states, and Batdorf's shear-sensitive as well as shear-insensitive statistical theories. The shear-sensitive surface crack configurations include the Griffith crack and Griffith notch geometries, using the total critical coplanar strain energy release rate criterion to predict mixed-mode fracture. Weibull material parameters based on both surface and volume flaw induced fracture can also be calculated from modulus of rupture bar tests, using the least squares method with known specimen geometry and grouped fracture data. The statistical fast fracture theories for surface flaw induced failure, along with selected input and output formats and options, are summarized. An example problem to demonstrate various features of the program is included.

Gyekenyesi, John P.↗

NASA NTRS1986

Line plotting program using DI-3000/Grafmaker routines

A line plotting program has been developed using the DI-3000 graphics libraries and incorporates Grafmaker subroutines. The program allows multiple lines on a frame and multiple frames per run. Options such as automatic scaling, linear or single-cycle log graphs, and plot text such as titles, legends and axis labels are incorporated in the program. Greek and other fonts can be used in the plot text as well as upper and lower case text. Plot inputs are specified through a control file. The program also allows display of multiple independent data sets on a single graph.

Poppen, William A., Jr.↗

NASA NTRS1987

The Air Force concentrating photovoltaic array program

A summary is given of Air Force solar concentrator projects beginning with the Rockwell International study program in 1977. The Satellite Materials Hardening Programs (SMATH) explored and developed techniques for hardening planar solar cell array power systems to the combined nuclear and laser radiation threat environments. A portion of program dollars was devoted to developing a preliminary design for a hardened solar concentrator. The results of the Survivable Concentrating Photovoltaic Array (SCOPA) program, and the design, fabrication and flight qualification of a hardened concentrator panel are discussed.

Geis, Jack W.↗

NASA NTRS1987

A Functional Programming Interpreter

Functional Programming (FP) sup BAC87 is an alternative to conventional imperative programming languages. This thesis describes an FP interpreter implementation. Superficially, FP appears to be a simple, but very inefficient language. Its simplicity, however, allows it to be interpreted quickly. Much of the inefficiency can be removed by simple interpreter techniques. This thesis describes the Illinois Functional Programming (IFP) interpreter, an interactive functional programming implementation which runs under both MS-DOS and UNIX. The IFP interpreter allows functions to be created, executed, and debugged in an environment very similar to UNIX. IFP's speed is competitive with other interpreted languages such as BASIC.

Arch Douglas Robison↗

NASA NTRS1987

Traditional versus rule-based programming techniques: Application to the control of optional flight information

To the software design community, the concern over the costs associated with a program's execution time and implementation is great. It is always desirable, and sometimes imperative, that the proper programming technique is chosen which minimizes all costs for a given application or type of application. A study is described that compared cost-related factors associated with traditional programming techniques to rule-based programming techniques for a specific application. The results of this study favored the traditional approach regarding execution efficiency, but favored the rule-based approach regarding programmer productivity (implementation ease). Although this study examined a specific application, the results should be widely applicable.

Ricks, Wendell R.↗

NASA NTRS1986

Introduction to GRASP - General rotorcraft aeromechanical stability program - A modern approach to rotorcraft modeling

The General Rotorcraft Aeromechanical Stability Program (GRASP), which is a hybrid between finite element programs and spacecraft-oriented multibody programs, is described in terms of its design and capabilities. Numerical results from GRASP are presented and compared with the results from an existing, special-purpose coupled rotor/body aeromechanical stability program and with experimental data of Dowell and Traybar (1975 and 1977) for large deflections of an end-loaded cantilevered beam. The agreement is excellent in both cases.

Hodges, D. H.↗

NASA NTRS1986

The NASA automation and robotics technology program

The development and objectives of the NASA automation and robotics technology program are reviewed. The objectives of the program are to utilize AI and robotics to increase the probability of mission success; decrease the cost of ground control; and increase the capability and flexibility of space operations. There is a need for real-time computational capability; an effective man-machine interface; and techniques to validate automated systems. Current programs in the areas of sensing and perception, task planning and reasoning, control execution, operator interface, and system architecture and integration are described. Programs aimed at demonstrating the capabilities of telerobotics and system autonomy are discussed.

Holcomb, Lee B.↗

NASA NTRS1987

Surface flaw reliability analysis of ceramic components with the SCARE finite element postprocessor program

Gyekenyesi, J. P.↗

NASA NTRS1987

NAVSIM 2: A computer program for simulating aided-inertial navigation for aircraft

NAVSIM II, a computer program for analytical simulation of aided-inertial navigation for aircraft, is described. The description is supported by a discussion of the program's application to the design and analysis of aided-inertial navigation systems as well as instructions for utilizing the program and for modifying it to accommodate new models, constraints, algorithms and scenarios. NAVSIM II simulates an airborne inertial navigation system built around a strapped-down inertial measurement unit and aided in its function by GPS, Doppler radar, altimeter, airspeed, and position-fix measurements. The measurements are incorporated into the navigation estimate via a UD-form Kalman filter. The simulation was designed and implemented using structured programming techniques and with particular attention to user-friendly operation.

Bjorkman, William S.↗

NASA NTRS1987

Research reports: 1987 NASA/ASEE Summer Faculty Fellowship Program

For the 23rd consecutive year, a NASA/ASEE Summer Faculty Fellowship Program was conducted at the Marshall Space Flight Center (MSFC). The program was conducted by the University of Alabama in Huntsville and MSFC during the period 1 June to 7 August 1987. Operated under the auspices of the American Society for Engineering Education, the MSFC program, as well as those at other NASA Centers, was sponsored by the Office of University Affairs, NASA Headquarters, Washington, D.C. The basic objectives of the program are: (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of the participant's institutions; and (4) to contribute to the research objectives of the NASA Centers. This document is a compilation of Fellow's reports on their research during the Summer of 1987.

Karr, Gerald R.↗

NASA NTRS1988

High-speed assembly language (80386/80387) programming for laser spectra scan control and data acquisition providing improved resolution water vapor spectroscopy

An assembly language program using the Intel 80386 CPU and 80387 math co-processor chips was written to increase the speed of data gathering and processing, and provide control of a scanning CW ring dye laser system. This laser system is used in high resolution (better than 0.001 cm-1) water vapor spectroscopy experiments. Laser beam power is sensed at the input and output of white cells and the output of a Fabry-Perot. The assembly language subroutine is called from Basic, acquires the data and performs various calculations at rates greater than 150 faster than could be performed by the higher level language. The width of output control pulses generated in assembly language are 3 to 4 microsecs as compared to 2 to 3.7 millisecs for those generated in Basic (about 500 to 1000 times faster). Included are a block diagram and brief description of the spectroscopy experiment, a flow diagram of the Basic and assembly language programs, listing of the programs, scope photographs of the computer generated 5-volt pulses used for control and timing analysis, and representative water spectrum curves obtained using these programs.

Allen, Robert J.↗

NASA NTRS1987

On acquisition of programming knowledge

For the evolving discipline of programming, acquisition of programming knowledge is a difficult issue. Common knowledge results from the acceptance of proven techniques based on results of formal inquiries into the nature of the programming process. This is a rather slow process. In addition, the vast body of common knowledge needs to be explicated to a low enough level of details for it to be represented in the machine processable form. It is felt that this is an impediment to the progress of automatic programming. The importance of formal approaches cannot be overstated since their contributions lead to quantum leaps in the state of the art.

Amin, Ashok T.↗

NASA NTRS1988

Advanced composite airframe program: Today's technology

The Advanced Composite Airframe Program (ACAP) was undertaken to demonstrate the advantages of the application of advanced composite materials and structural design concepts to the airframe structure on helicopters designed to stringent military requirements. The primary goals of the program were the reduction of airframe production costs and airframe weight by 17 and 22 percent respectively. The ACAP effort consisted of a preliminary design phase, detail design, and design support testing, full-scale fabrication, laboratory testing, and a ground/flight test demonstration. Since the completion of the flight test demonstration programs follow-on efforts were initiated to more fully evaluate a variety of military characteristics of the composite airframe structures developed under the original ACAP advanced development contracts. An overview of the ACAP program is provided and some of the design features, design support testing, manufacturing approaches, and the results of the flight test evaluation, as well as, an overview of Militarization Test and Evaluation efforts are described.

Good, Danny E.↗

NASA NTRS1988

A visual programming environment for the Navier-Stokes computer

The Navier-Stokes computer is a high-performance, reconfigurable, pipelined machine designed to solve large computational fluid dynamics problems. Due to the complexity of the architecture, development of effective, high-level language compilers for the system appears to be a very difficult task. Consequently, a visual programming methodology has been developed which allows users to program the system at an architectural level by constructing diagrams of the pipeline configuration. These schematic program representations can then be checked for validity and automatically translated into machine code. The visual environment is illustrated by using a prototype graphical editor to program an example problem.

Tomboulian, Sherryl↗