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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Develop and test fuel cell powered on-site integrated total energy systems: Phase 3, full-scale power plant development

A 25 cell stack of the 13 inch x 23 inch cell size (about 4kW) remains on test after 6000 hours, using simulated reformate fuel. A similar stack was previously shut down after 7000 hours on load. These tests were carried out for the purpose of assessing the durability of fuel cell stack components developed through the end of 1983. In light of the favorable results obtained, a 25kW stack that will contain 175 cells of the same size is being constructed using the same technology base. The components for the 25kW stack have been completed. A methanol steam reformer with a design output equivalent to 50kW has been constructed to serve as a hydrogen generator for the 25kW stack. This reformer and the balance of the fuel processing sub system are currently being tested and debugged. The stack technology development program focused on cost reduction in bipolar plates, nonmetallic cooling plates, and current collecting plates; more stable cathode catalyst support materials; more corrosion resistant metal hardware; and shutdown/start up tolerance.

Kaufman, A.↗
NASA NTRS1985

DAB user's guide

Use of the Display AButments (DAB) which plots PAN AIR geometries is presented. The DAB program creates hidden line displays of PAN AIR geometries and labels specified geometry components, such as abutments, networks, and network edges. It is used to alleviate the very time consuming and error prone abutment list checking phase of developing a valid PAN AIR geometry, and therefore represents a valuable tool for debugging complex PAN AIR geometry definitions. DAB is written in FORTRAN 77 and runs on a Digital Equipment Corporation VAX 11/780 under VMS. It utilizes a special color version of the SKETCH hidden line analysis routine.

Trosin, J.↗
NASA NTRS1985

Experiences with Cray multi-tasking

The issues involved in modifying an existing code for multitasking is explored. They include Cray extensions to FORTRAN, an examination of the application code under study, designing workable modifications, specific code modifications to the VAX and Cray versions, performance, and efficiency results. The finished product is a faster, fully synchronous, parallel version of the original program. A production program is partitioned by hand to run on two CPUs. Loop splitting multitasks three key subroutines. Simply dividing subroutine data and control structure down the middle of a subroutine is not safe. Simple division produces results that are inconsistent with uniprocessor runs. The safest way to partition the code is to transfer one block of loops at a time and check the results of each on a test case. Other issues include debugging and performance. Task startup and maintenance (e.g., synchronization) are potentially expensive.

Miya, E. N.↗
NASA NTRS1987

Programs To Aid FORTRAN Programming

Program-development time decreased while program quality increased. FORTRAN Programming Tools are series of programming tools used to support development and maintenance of FORTRAN 77 source codes. Included are debugging aid, central-processing-unit time-monitoring program, source-code maintenance aids, print utilities, and library of useful, well-documented programs. Tools assist in reducing development time and encouraging high-quality programming. Although intended primarily for FORTRAN programmers, some tools used on data files and other programming languages. Written in FORTRAN 77.

Ragosta, Arthur E.↗
NASA NTRS1986

Free vibration and dynamic response analysis of spinning structures

The proposed effort involved development of numerical procedures for efficient solution of free vibration problems of spinning structures. An eigenproblem solution procedure, based on a Lanczos method employing complex arithmetic, was successfully developed. This task involved formulation of the numerical procedure, FORTRAN coding of the algorithm, checking and debugging of software, and implementation of the routine in the STARS program. A graphics package for the E/S PS 300 as well as for the Tektronix terminals was successfully generated and consists of the following special capabilities: (1) a dynamic response plot for the stresses and displacements as functions of time; and (2) a menu driven command module enabling input of data on an interactive basis. Finally, the STARS analysis capability was further improved by implementing the dynamic response analysis package that provides information on nodal deformations and element stresses as a function of time. A number of test cases were run utilizing the currently developed algorithm implemented in the STARS program and such results indicate that the newly generated solution technique is significantly more efficient than other existing similar procedures.

Source record↗
NASA NTRS1985

Calculation of water drop trajectories to and about arbitrary three-dimensional lifting and nonlifting bodies in potential airflow

Subsonic, external flow about nonlifting bodies, lifting bodies or combinations of lifting and nonlifting bodies is calculated by a modified version of the Hess lifting code. Trajectory calculations can be performed for any atmospheric conditions and for all water drop sizes, from the smallest cloud droplet to large raindrops. Experimental water drop drag relations are used in the water drop equations of motion and effects of gravity settling are included. Inlet flow can be accommodated, and high Mach number compressibility effects are corrected for approximately. Seven codes are described: (1) a code used to debug and plot body surface description data; (2) a code that processes the body surface data to yield the potential flow field; (3) a code that computes flow velocities at arrays of points in space; (4) a code that computes water drop trajectories from an array of points in space; (5) a code that computes water drop trajectories and fluxes to arbitrary target points; (6) a code that computes water drop trajectories tangent to the body; and (7) a code that produces stereo pair plots which include both the body and trajectories. Accuracy of the calculations is discussed, and trajectory calculation results are compared with prior calculations and with experimental data.

Norment, H. G.↗
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

Workstations take over conceptual design

Workstations provide sufficient computing memory and speed for early evaluations of aircraft design alternatives to identify those worthy of further study. It is recommended that the programming of such machines permit integrated calculations of the configuration and performance analysis of new concepts, along with the capability of changing up to 100 variables at a time and swiftly viewing the results. Computations can be augmented through links to mainframes and supercomputers. Programming, particularly debugging operations, are enhanced by the capability of working with one program line at a time and having available on-screen error indices. Workstation networks permit on-line communication among users and with persons and computers outside the facility. Application of the capabilities is illustrated through a description of NASA-Ames design efforts for an oblique wing for a jet performed on a MicroVAX network.

Kidwell, George H.↗
NASA NTRS1987

Color graphics, interactive processing, and the supercomputer

The development of a common graphics environment for the NASA Langley Research Center user community and the integration of a supercomputer into this environment is examined. The initial computer hardware, the software graphics packages, and their configurations are described. The addition of improved computer graphics capability to the supercomputer, and the utilization of the graphic software and hardware are discussed. Consideration is given to the interactive processing system which supports the computer in an interactive debugging, processing, and graphics environment.

Smith-Taylor, Rudeen↗
NASA NTRS1987

Verification of FANTASTIC integrated code

FANTASTIC is an acronym for Failure Analysis Nonlinear Thermal and Structural Integrated Code. This program was developed by Failure Analysis Associates, Palo Alto, Calif., for MSFC to improve the accuracy of solid rocket motor nozzle analysis. FANTASTIC has three modules: FACT - thermochemical analysis; FAHT - heat transfer analysis; and FAST - structural analysis. All modules have keywords for data input. Work is in progress for the verification of the FAHT module, which is done by using data for various problems with known solutions as inputs to the FAHT module. The information obtained is used to identify problem areas of the code and passed on to the developer for debugging purposes. Failure Analysis Associates have revised the first version of the FANTASTIC code and a new improved version has been released to the Thermal Systems Branch.

Chauhan, Rajinder Singh↗
NASA NTRS1987

CLIPS: An expert system tool for delivery and training

The C Language Integrated Production System (CLIPS) is a forward chaining rule-based language. The requirements necessary for an expert system tool which is used for development, delivery, and training are examined. Because of its high portability, low cost, and ease of integration with external systems, CLIPS has great potential as an expert system tool for delivery and training. In addition, its representation flexibility, debugging aids, and performance, along with its other strengths, make it a viable alternative for expert system development.

Riley, Gary↗
NASA NTRS1987

Trimodal interpretation of constraints for planning

Constraints are used in the CAMPS knowledge based planning system to represent those propositions that must be true for a plan to be acceptable. CAMPS introduces the make-mode for interpreting a constraint. Given an unsatisfied constraint, make evaluation mode suggests planning actions which, if taken, would result in a modified plan in which the constraint in question may be satisfied. These suggested planning actions, termed delta-tuples, are the raw material of intelligent plan repair. They are used both in debugging an almost-right plan and in replanning due to changing situations. Given a defective plan in which some set of constraints are violated, a problem solving strategy selects one or more constraints as a focus of attention. These selected constraints are evaluated in the make-mode to produce delta-tuples. The problem solving strategy then reviews the delta-tuples according to its application and problem-specific criteria to find the most acceptable change in terms of success likelihood and plan disruption. Finally, the problem solving strategy makes the suggested alteration to the plan and then rechecks constraints to find any unexpected consequences.

Krieger, David↗
NASA NTRS1988

Comprehensive analysis of helicopters with bearingless rotors

A modified Galerkin method is developed to analyze the dynamic problems of multiple-load-path bearingless rotor blades. The development and selection of functions are quite parallel to CAMRAD procedures, greatly facilitating the implementation of the method into the CAMRAD program. A software is developed implementing the modified Galerkin method to determine free vibration characteristics of multiple-load-path rotor blades undergoing coupled flapwise bending, chordwise bending, twisting, and extensional motions. Results are in the process of being obtained by debugging the software.

Murthy, V. R.↗
NASA NTRS1988

Heat exchanger demonstration expert system

A real-time expert system intended for detecting and diagnosing faults in a 20 kW microwave transmitter heat exchanger is described. The expert system was developed on a LISP machine, Incorporated (LMI), Lambda Plus computer using Process Intelligent Control (PICON) software. The Heat Exhanger Expert System was tested and debugged. Future applications and extensions of the expert system to transmitters, masers, and antenna subassemblies are discussed.

Bagby, D. G.↗
NASA NTRS1987

Sensing and perception research for space telerobotics at JPL

PIFLEX is a pipelined-image processor that can perform elaborate computations whose exact nature is not fixed in the hardware, and that can handle multiple images. A wire-wrapped prototype PIFEX module has been produced and debugged, using a version of the convolver composed of three custom VLSI chips (plus the line buffers). A printed circuit layout is being designed for use with a single-chip convolver, leading to production of a PIFEX with about 120 modules. A high-level language for programming PIFEX has been designed, and a compiler will be written for it. The camera calibration software has been completed and tested. Two more terms in the camera model, for lens distortion, probably will be added later. The acquisition and tracking system has been designed and most of it has been coded in Pascal for the MicroVAX-II. The feature tracker, motion stereo module and stereo matcher have executed successfully. The model matcher is still under development, and coding has begun on the tracking initializer. The object tracker was running on a different computer from the VAX, and preliminary runs on real images have been performed there. Once all modules are working, optimization and integration will begin. Finally, when a sufficiently large PIFEX is available, appropriate parts of acquisition and tracking, including much of the feature tracker, will be programmed into PIFEX, thus increasing the speed and robustness of the system.

Gennery, Donald B.↗
NASA NTRS1989

Examining The Subroutine Structure Of A VAX Image

Command program analyzes executable components of another program. SCANEXE, a command program for DEC VAX computer used to scan VMS run-time image and print information about routines it uses. Lists each routine, with entry point, and how many times called. Information on progress of program printed at user's option as analyzing various executable components. Relies on "debug" records included by default in ".EXE" files. If image linked with "/NOTRACEBACK" option, cannot provide necessary information. Written in C (83 percent), FORTRAN 77 (13 percent), and Assembler (4 percent).

Scott, Peter J.↗
NASA NTRS1988

PC-CUBE: A Personal Computer Based Hypercube

PC-CUBE is an ensemble of IBM PCs or close compatibles connected in the hypercube topology with ordinary computer cables. Communication occurs at the rate of 115.2 K-band via the RS-232 serial links. Available for PC-CUBE is the Crystalline Operating System III (CrOS III), Mercury Operating System, CUBIX and PLOTIX which are parallel I/O and graphics libraries. A CrOS performance monitor was developed to facilitate the measurement of communication and computation time of a program and their effects on performance. Also available are CXLISP, a parallel version of the XLISP interpreter; GRAFIX, some graphics routines for the EGA and CGA; and a general execution profiler for determining execution time spent by program subroutines. PC-CUBE provides a programming environment similar to all hypercube systems running CrOS III, Mercury and CUBIX. In addition, every node (personal computer) has its own graphics display monitor and storage devices. These allow data to be displayed or stored at every processor, which has much instructional value and enables easier debugging of applications. Some application programs which are taken from the book Solving Problems on Concurrent Processors (Fox 88) were implemented with graphics enhancement on PC-CUBE. The applications range from solving the Mandelbrot set, Laplace equation, wave equation, long range force interaction, to WaTor, an ecological simulation.

Ho, Alex↗
NASA NTRS1988

Estimating residual fault hitting rates by recapture sampling

For the recapture debugging design introduced by Nayak (1988) the problem of estimating the hitting rates of the faults remaining in the system is considered. In the context of a conditional likelihood, moment estimators are derived and are shown to be asymptotically normal and fully efficient. Fixed sample properties of the moment estimators are compared, through simulation, with those of the conditional maximum likelihood estimators. Properties of the conditional model are investigated such as the asymptotic distribution of linear functions of the fault hitting frequencies and a representation of the full data vector in terms of a sequence of independent random vectors. It is assumed that the residual hitting rates follow a log linear rate model and that the testing process is truncated when the gaps between the detection of new errors exceed a fixed amount of time.

Lee, Larry↗