SEARCH · Engineering Papers

Results for “program processors”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39

All sources NASA NTRS DOE OSTI

NASA NTRS1978

Data Management Symposium, Huntsville, Ala., October 18, 19, 1977, Proceedings

The transfer, processing, and use of satellite data are discussed. Topics relating to simulation and processing techniques include computer design assessments through simulation, data system dynamic simulation, and future timing accuracy requirements and procedures for data processing. Subjects relevant to data base management systems and users and their needs include an image-based information system architecture for correlation satellite and topological data base, efficient searching and sorting applications using an associative array processor, analysis of user's needs for a large technical data base, and variable length data formats. The technology development outlook was considered with attention to data systems technology outlook for supporting NASA programs, a user-oriented interactive information extraction system, and flow control and sorting techniques for telemetry packets.

Castelli, A.↗

NASA NTRS1990

Expert system for multidisciplinary analysis and optimization using ASTROS

This paper discusses the framework of a Knowledge Based Expert System (KBES) environment to design aerospace structures under structural and aerodynamic constraints using ASTROS (Automated Structural Optimization program). ASTROS is a synthesis tool built around the NASTRAN finite element program. The knowledge base capabilities are discussed for synthesizing in statics, normal mode, steady and unsteady aerodynamic disciplines. A description of the two ASTROS advisor modules the Editor/Bulk Data generator and Post-processor is included. Experiences and issues involved in hierarchical representation of knowledge as menu options at different levels of abstraction are presented. A brief overview of Knowledge Based Systems and the shell CLIPS (C Language Integrated Production System) used to develop the ASTROS Advisor are discussed. Illustrative examples of the advisor in designing airframe structures are also included.

Sarma, Hari K.↗

NASA NTRS1994

Advanced End-to-end Simulation for On-board Processing (AESOP)

Developers of data compression algorithms typically use their own software together with commercial packages to implement, evaluate and demonstrate their work. While convenient for an individual developer, this approach makes it difficult to build on or use another's work without intimate knowledge of each component. When several people or groups work on different parts of the same problem, the larger view can be lost. What's needed is a simple piece of software to stand in the gap and link together the efforts of different people, enabling them to build on each other's work, and providing a base for engineers and scientists to evaluate the parts as a cohesive whole and make design decisions. AESOP (Advanced End-to-end Simulation for On-board Processing) attempts to meet this need by providing a graphical interface to a developer-selected set of algorithms, interfacing with compiled code and standalone programs, as well as procedures written in the IDL and PV-Wave command languages. As a proof of concept, AESOP is outfitted with several data compression algorithms integrating previous work on different processors (AT&T DSP32C, TI TMS320C30, SPARC). The user can specify at run-time the processor on which individual parts of the compression should run. Compressed data is then fed through simulated transmission and uncompression to evaluate the effects of compression parameters, noise and error correction algorithms. The following sections describe AESOP in detail. Section 2 describes fundamental goals for usability. Section 3 describes the implementation. Sections 4 through 5 describe how to add new functionality to the system and present the existing data compression algorithms. Sections 6 and 7 discuss portability and future work.

Mazer, Alan S.↗

NASA NTRS1995

Communication overhead on the Intel Paragon, IBM SP2 and Meiko CS-2

Interprocessor communication overhead is a crucial measure of the power of parallel computing systems-its impact can severely limit the performance of parallel programs. This report presents measurements of communication overhead on three contemporary commercial multicomputer systems: the Intel Paragon, the IBM SP2 and the Meiko CS-2. In each case the time to communicate between processors is presented as a function of message length. The time for global synchronization and memory access is discussed. The performance of these machines in emulating hypercubes and executing random pairwise exchanges is also investigated. It is shown that the interprocessor communication time depends heavily on the specific communication pattern required. These observations contradict the commonly held belief that communication overhead on contemporary machines is independent of the placement of tasks on processors. The information presented in this report permits the evaluation of the efficiency of parallel algorithm implementations against standard baselines.

Bokhari, Shahid H.↗

NASA NTRS1996

Development of a low-cost virtual reality workstation for training and education

Virtual Reality (VR) is a set of breakthrough technologies that allow a human being to enter and fully experience a 3-dimensional, computer simulated environment. A true virtual reality experience meets three criteria: (1) it involves 3-dimensional computer graphics; (2) it includes real-time feedback and response to user actions; and (3) it must provide a sense of immersion. Good examples of a virtual reality simulator are the flight simulators used by all branches of the military to train pilots for combat in high performance jet fighters. The fidelity of such simulators is extremely high -- but so is the price tag, typically millions of dollars. Virtual reality teaching and training methods are manifestly effective, but the high cost of VR technology has limited its practical application to fields with big budgets, such as military combat simulation, commercial pilot training, and certain projects within the space program. However, in the last year there has been a revolution in the cost of VR technology. The speed of inexpensive personal computers has increased dramatically, especially with the introduction of the Pentium processor and the PCI bus for IBM-compatibles, and the cost of high-quality virtual reality peripherals has plummeted. The result is that many public schools, colleges, and universities can afford a PC-based workstation capable of running immersive virtual reality applications. My goal this summer was to assemble and evaluate such a system.

Phillips, James A.↗

NASA NTRS2000

Applications of Parallel Process HiMAP for Large Scale Multidisciplinary Problems

HiMAP is a three level parallel middleware that can be interfaced to a large scale global design environment for code independent, multidisciplinary analysis using high fidelity equations. Aerospace technology needs are rapidly changing. Computational tools compatible with the requirements of national programs such as space transportation are needed. Conventional computation tools are inadequate for modern aerospace design needs. Advanced, modular computational tools are needed, such as those that incorporate the technology of massively parallel processors (MPP).

Guruswamy, Guru P.↗

NASA NTRS1990

Implementing real-time robotic systems using CHIMERA II

A description is given of the CHIMERA II programming environment and operating system, which was developed for implementing real-time robotic systems. Sensor-based robotic systems contain both general- and special-purpose hardware, and thus the development of applications tends to be a time-consuming task. The CHIMERA II environment is designed to reduce the development time by providing a convenient software interface between the hardware and the user. CHIMERA II supports flexible hardware configurations which are based on one or more VME-backplanes. All communication across multiple processors is transparent to the user through an extensive set of interprocessor communication primitives. CHIMERA II also provides a high-performance real-time kernel which supports both deadline and highest-priority-first scheduling. The flexibility of CHIMERA II allows hierarchical models for robot control, such as NASREM, to be implemented with minimal programming time and effort.

Stewart, David B.↗

NASA NTRS1988

Proceedings of the First NASA Ada Users' Symposium

Ada has the potential to be a part of the most significant change in software engineering technology within NASA in the last twenty years. Thus, it is particularly important that all NASA centers be aware of Ada experience and plans at other centers. Ada activity across NASA are covered, with presenters representing five of the nine major NASA centers and the Space Station Freedom Program Office. Projects discussed included - Space Station Freedom Program Office: the implications of Ada on training, reuse, management and the software support environment; Johnson Space Center (JSC): early experience with the use of Ada, software engineering and Ada training and the evaluation of Ada compilers; Marshall Space Flight Center (MSFC): university research with Ada and the application of Ada to Space Station Freedom, the Orbital Maneuvering Vehicle, the Aero-Assist Flight Experiment and the Secure Shuttle Data System; Lewis Research Center (LeRC): the evolution of Ada software to support the Space Station Power Management and Distribution System; Jet Propulsion Laboratory (JPL): the creation of a centralized Ada development laboratory and current applications of Ada including the Real-time Weather Processor for the FAA; and Goddard Space Flight Center (GSFC): experiences with Ada in the Flight Dynamics Division and the Extreme Ultraviolet Explorer (EUVE) project and the implications of GSFC experience for Ada use in NASA. Despite the diversity of the presentations, several common themes emerged from the program: Methodology - NASA experience in general indicates that the effective use of Ada requires modern software engineering methodologies; Training - It is the software engineering principles and methods that surround Ada, rather than Ada itself, which requires the major training effort; Reuse - Due to training and transition costs, the use of Ada may initially actually decrease productivity, as was clearly found at GSFC; and real-time work at LeRC, JPL and GSFC shows that it is possible to use Ada for real-time applications.

Source record↗

NASA NTRS1986

Rapid prototyping facility for flight research in artificial-intelligence-based flight systems concepts

The Dryden Flight Research Facility of the NASA Ames Research Facility of the NASA Ames Research Center is developing a rapid prototyping facility for flight research in flight systems concepts that are based on artificial intelligence (AI). The facility will include real-time high-fidelity aircraft simulators, conventional and symbolic processors, and a high-performance research aircraft specially modified to accept commands from the ground-based AI computers. This facility is being developed as part of the NASA-DARPA automated wingman program. This document discusses the need for flight research and for a national flight research facility for the rapid prototyping of AI-based avionics systems and the NASA response to those needs.

Duke, E. L.↗

NASA NTRS1989

A rapid prototyping facility for flight research in advanced systems concepts

Duke, Eugene L.↗

NASA NTRS1990

Parallelized reliability estimation of reconfigurable computer networks

A parallelized system, ASSURE, for computing the reliability of embedded avionics flight control systems which are able to reconfigure themselves in the event of failure is described. ASSURE accepts a grammar that describes a reliability semi-Markov state-space. From this it creates a parallel program that simultaneously generates and analyzes the state-space, placing upper and lower bounds on the probability of system failure. ASSURE is implemented on a 32-node Intel iPSC/860, and has achieved high processor efficiencies on real problems. Through a combination of improved algorithms, exploitation of parallelism, and use of an advanced microprocessor architecture, ASSURE has reduced the execution time on substantial problems by a factor of one thousand over previous workstation implementations. Furthermore, ASSURE's parallel execution rate on the iPSC/860 is an order of magnitude faster than its serial execution rate on a Cray-2 supercomputer. While dynamic load balancing is necessary for ASSURE's good performance, it is needed only infrequently; the particular method of load balancing used does not substantially affect performance.

Nicol, David M.↗

NASA NTRS2004

Linearized Aeroelastic Solver Applied to the Flutter Prediction of Real Configurations

A fast-running unsteady aerodynamics code, LINFLUX, was previously developed for predicting turbomachinery flutter. This linearized code, based on a frequency domain method, models the effects of steady blade loading through a nonlinear steady flow field. The LINFLUX code, which is 6 to 7 times faster than the corresponding nonlinear time domain code, is suitable for use in the initial design phase. Earlier, this code was verified through application to a research fan, and it was shown that the predictions of work per cycle and flutter compared well with those from a nonlinear time-marching aeroelastic code, TURBO-AE. Now, the LINFLUX code has been applied to real configurations: fans developed under the Energy Efficient Engine (E-cubed) Program and the Quiet Aircraft Technology (QAT) project. The LINFLUX code starts with a steady nonlinear aerodynamic flow field and solves the unsteady linearized Euler equations to calculate the unsteady aerodynamic forces on the turbomachinery blades. First, a steady aerodynamic solution is computed for given operating conditions using the nonlinear unsteady aerodynamic code TURBO-AE. A blade vibration analysis is done to determine the frequencies and mode shapes of the vibrating blades, and an interface code is used to convert the steady aerodynamic solution to a form required by LINFLUX. A preprocessor is used to interpolate the mode shapes from the structural dynamics mesh onto the computational fluid dynamics mesh. Then, LINFLUX is used to calculate the unsteady aerodynamic pressure distribution for a given vibration mode, frequency, and interblade phase angle. Finally, a post-processor uses the unsteady pressures to calculate the generalized aerodynamic forces, eigenvalues, an esponse amplitudes. The eigenvalues determine the flutter frequency and damping. Results of flutter calculations from the LINFLUX code are presented for (1) the E-cubed fan developed under the E-cubed program and (2) the Quiet High Speed Fan (QHSF) developed under the Quiet Aircraft Technology project. The results are compared with those obtained from the TURBO-AE code. A graph of the work done per vibration cycle for the first vibration mode of the E-cubed fan is shown. It can be seen that the LINFLUX results show a very good comparison with TURBO-AE results over the entire range of interblade phase angle. The work done per vibration cycle for the first vibration mode of the QHSF fan is shown. Once again, the LINFLUX results compare very well with the results from the TURBOAE code.

Reddy, Tondapu S.↗

NASA NTRS1977

Implicit finite difference simulation of flow about arbitrary geometries with application to airfoils

Finite difference procedures are used to solve either the Euler equations or the 'thin layer' Navier-Stokes equations subject to arbitrary boundary conditions. An automatic grid generation program is employed, and because an implicit finite difference algorithm for the flow equations is used, time steps are not severely limited when grid points are finely distributed. Computational efficiency and compatibility to vectorized computer processors is maintained by use of approximate factorization techniques. Computed results for both inviscid and viscous flow about airfoils are described and compared to various known solutions.

Steger, J. L.↗

NASA NTRS1977

RINA: An interactive system for the rapid interpretation of NASTRAN results

RINA is a general post-processor system which performs data reduction, post processing and post analysis of NASTRAN results. RINA can be run in either batch or time-sharing mode. The system, which is an expansion of the NASDAT program, performs the following tasks: (1) scan of extreme values for displacements, forces, stresses and margins of safety, (2) computations of envelopes for displacements, forces, stresses and margins of safety, (3) computations of allowables and margins of safety; and (4) generation of NASTRAN tables needed for reanalysis computations. Usage of all these options provides the analyst with an efficient tool for the study and interpretation of NASTRAN analysis results and their presentation for project documentation.

Raibstone, A. I.↗

NASA NTRS1988

Definition of an auxiliary processor dedicated to real-time operating system kernels

In order to increase the efficiency of process control data processing, it is necessary to enhance the productivity of real time high level languages and to automate the task administration, because presently 60 percent or more of the applications are still programmed in assembly languages. This may be achieved by migrating apt functions for the support of process control oriented languages into the hardware, i.e., by new architectures. Whereas numerous high level languages have already been defined or realized, there are no investigations yet on hardware assisted implementation of real time features. The requirements to be fulfilled by languages and operating systems in hard real time environment are summarized. A comparison of the most prominent languages, viz. Ada, HAL/S, LTR, Pearl, as well as the real time extensions of FORTRAN and PL/1, reveals how existing languages meet these demands and which features still need to be incorporated to enable the development of reliable software with predictable program behavior, thus making it possible to carry out a technical safety approval. Accordingly, Pearl proved to be the closest match to the mentioned requirements.

Halang, Wolfgang A.↗

NASA NTRS1992

Flight Testing

It is considered by the Flight Mechanics Panel of AGARD as vitally important that the NATO flight test community meet regularly so that new techniques for flight test, instrumentation and data analysis and lessons learned from past and on-going programs be disseminated to ensure that safe efficient cost-effective and timely testing is accomplished. There are many new systems being tested or planned for testing in the near future. These include programmable signal processor radars, integrated flight, fire and propulsion control systems, thrust vectoring, low observable technologies, multifunction pilot displays and multisensor integration. Acquisition and processing of large quantities of avionics multiplex data are challenges that must be met. There is a need for greater use of simulators and other hardware-in-the-loop ground test facilities.

Source record↗

NASA NTRS1993

Future directions in flight simulation: A user perspective

Langley Research Center was an early leader in simulation technology, including a special emphasis in space vehicle simulations such as the rendezvous and docking simulator for the Gemini program and the lunar landing simulator used before Apollo. In more recent times, Langley operated the first synergistic six degree of freedom motion platform (the Visual Motion Simulator, or VMS) and developed the first dual-dome air combat simulator, the Differential Maneuvering Simulator (DMS). Each Langley simulator was developed more or less independently from one another with different programming support. At present time, the various simulation cockpits, while supported by the same host computer system, run dissimilar software. The majority of recent investments in Langley's simulation facilities have been hardware procurements: host processors, visual systems, and most recently, an improved motion system. Investments in software improvements, however, have not been of the same order.

Jackson, Bruce↗

NASA NTRS1995

Advanced compilation techniques in the PARADIGM compiler for distributed-memory multicomputers

The PARADIGM compiler project provides an automated means to parallelize programs, written in a serial programming model, for efficient execution on distributed-memory multicomputers. .A previous implementation of the compiler based on the PTD representation allowed symbolic array sizes, affine loop bounds and array subscripts, and variable number of processors, provided that arrays were single or multi-dimensionally block distributed. The techniques presented here extend the compiler to also accept multidimensional cyclic and block-cyclic distributions within a uniform symbolic framework. These extensions demand more sophisticated symbolic manipulation capabilities. A novel aspect of our approach is to meet this demand by interfacing PARADIGM with a powerful off-the-shelf symbolic package, Mathematica. This paper describes some of the Mathematica routines that performs various transformations, shows how they are invoked and used by the compiler to overcome the new challenges, and presents experimental results for code involving cyclic and block-cyclic arrays as evidence of the feasibility of the approach.

Su, Ernesto↗