Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Advanced Computing”

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.

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

At least 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

NASA's CSTI Earth-to-Orbit Propulsion Program - On-target technology transfer to advanced space flight programs

NASA's Civil Space Technology Initiative encompasses among its major elements the Earth-to-Orbit Propulsion Program (ETOPP) for future launch vehicles, which is budgeted to the extent of $20-30 million/year for the development of essential technologies. ETOPP technologies include, in addition to advanced materials and processes and design/analysis computational tools, the advanced systems-synthesis technologies required for definition of highly reliable LH2 and hydrocarbon fueled rocket engines to be operated at significantly reduced levels of risk and cost relative to the SSME. Attention is given to the technology-transfer services of ETOPP.

Escher, William J. D.↗
NASA NTRS1991

Hypersonic Shock/Boundary-Layer Interaction Database

Turbulence modeling is generally recognized as the major problem obstructing further advances in computational fluid dynamics (CFD). A closed solution of the governing Navier-Stokes equations for turbulent flows of practical consequence is still far beyond grasp. At the same time, the simplified models of turbulence which are used to achieve closure of the Navier-Stokes equations are known to be rigorously incorrect. While these models serve a definite purpose, they are inadequate for the general prediction of hypersonic viscous/inviscid interactions, mixing problems, chemical nonequilibria, and a range of other phenomena which must be predicted in order to design a hypersonic vehicle computationally. Due to the complexity of turbulence, useful new turbulence models are synthesized only when great expertise is brought to bear and considerable intellectual energy is expended. Although this process is fundamentally theoretical, crucial guidance may be gained from carefully-executed basic experiments. Following the birth of a new model, its testing and validation once again demand comparisons with data of unimpeachable quality. This report concerns these issues which arise from the experimental aspects of hypersonic modeling and represents the results of the first phase of an effort to develop compressible turbulence models.

Settles, G. S.↗
NASA NTRS1991

The magnetopause

A review of theoretical and observational research on the magnetopause during 1987-1990. Starting with recent work on magnetic reconnection, the review proceeds to magnetopause surface wave phenomena, including the controversy over the role of solar wind pressure pulses in the coupling process and in the mimicking of flux transfer events signatures, and finishes with the magnetopause structure and associated wave phenomena. Recent advances in computer modeling of the magnetopause and the pertinent processes are also discussed.

Smith, M. F.↗
NASA NTRS1991

Intelligent perturbation algorithms to space scheduling optimization

The limited availability and high cost of crew time and scarce resources make optimization of space operations critical. Advances in computer technology coupled with new iterative search techniques permit the near optimization of complex scheduling problems that were previously considered computationally intractable. Described here is a class of search techniques called Intelligent Perturbation Algorithms. Several scheduling systems which use these algorithms to optimize the scheduling of space crew, payload, and resource operations are also discussed.

Kurtzman, Clifford R.↗
NASA NTRS1991

Acquisition and production of skilled behavior in dynamic decision-making tasks: Modeling strategic behavior in human-automation interaction: Why and aid can (and should) go unused

Advances in computer and control technology offer the opportunity for task-offload aiding in human-machine systems. A task-offload aid (e.g., an autopilot, an intelligent assistant) can be selectively engaged by the human operator to dynamically delegate tasks to an automated system. Successful design and performance prediction in such systems requires knowledge of the factors influencing the strategy the operator develops and uses for managing interaction with the task-offload aid. A model is presented that shows how such strategies can be predicted as a function of three task context properties (frequency and duration of secondary tasks and costs of delaying secondary tasks) and three aid design properties (aid engagement and disengagement times, aid performance relative to human performance). Sensitivity analysis indicates how each of these contextual and design factors affect the optimal aid aid usage strategy and attainable system performance. The model is applied to understanding human-automation interaction in laboratory experiments on human supervisory control behavior. The laboratory task allowed subjects freedom to determine strategies for using an autopilot in a dynamic, multi-task environment. Modeling results suggested that many subjects may indeed have been acting appropriately by not using the autopilot in the way its designers intended. Although autopilot function was technically sound, this aid was not designed with due regard to the overall task context in which it was placed. These results demonstrate the need for additional research on how people may strategically manage their own resources, as well as those provided by automation, in an effort to keep workload and performance at acceptable levels.

Kirlik, Alex↗
NASA NTRS1991

Adjoint operator approach to shape design for internal incompressible flows

The problem of determining the profile of a channel or duct that provides the maximum static pressure rise is solved. Incompressible, laminar flow governed by the steady state Navier-Stokes equations is assumed. Recent advances in computational resources and algorithms have made it possible to solve the direct problem of determining such a flow through a body of known geometry. It is possible to obtain a set of adjoint equations, the solution to which permits the calculation of the direction and relative magnitude of change in the diffuser profile that leads to a higher pressure rise. The solution to the adjoint problem can be shown to represent an artificially constructed flow. This interpretation provides a means to construct numerical solutions to the adjoint equations that do not compromise the fully viscous nature of the problem. The algorithmic and computational aspects of solving the adjoint equations are addressed. The form of these set of equations is similar but not identical to the Navier-Stokes equations. In particular some issues related to boundary conditions and stability are discussed.

Cabuk, H.↗
NASA NTRS1992

Structural ceramics

This presentation gives a brief history of the field of materials sciences and goes on to expound the advantages of the fastest growing area in that field, namely ceramics. Since ceramics are moving to fill the demand for lighter, stronger, more corrosion resistant materials, advancements will rely more on processing and modeling from the atomic scale up which is made possible by advanced analytical, computer, and processing techniques. All information is presented in viewgraph format.

Craig, Douglas F.↗
NASA NTRS1992

Using adaptive grid in modeling rocket nozzle flow

The mechanical behavior of a rocket motor internal flow field results in a system of nonlinear partial differential equations which cannot be solved analytically. However, this system of equations called the Navier-Stokes equations can be solved numerically. The accuracy and the convergence of the solution of the system of equations will depend largely on how precisely the sharp gradients in the domain of interest can be resolved. With the advances in computer technology, more sophisticated algorithms are available to improve the accuracy and convergence of the solutions. An adaptive grid generation is one of the schemes which can be incorporated into the algorithm to enhance the capability of numerical modeling. It is equivalent to putting intelligence into the algorithm to optimize the use of computer memory. With this scheme, the finite difference domain of the flow field called the grid does neither have to be very fine nor strategically placed at the location of sharp gradients. The grid is self adapting as the solution evolves. This scheme significantly improves the methodology of solving flow problems in rocket nozzles by taking the refinement part of grid generation out of the hands of computational fluid dynamics (CFD) specialists and place it into the computer algorithm itself.

Chow, Alan S.↗
NASA NTRS1987

Three dimensional flows in multistage compressors

Current multi-stage turbomachinery design/analysis methods are based on a time-averaged, axisymmetric representation of the flow field. The actual flow field is asymmetric and unsteady due to blade row interactions. The Reynolds averaged Navier-Stokes solvers are limited to single-stage machines for existing computers. Therefore, advanced multi-stage compressors will operate far off-design for portions of the flight regime. The objectives are to provide an experimentally validated average-passage calculation of multistage compressor blade row interactions and an experimentally validated time-accurate calculation of multi-stage compressor blade row interactions. Various aspects of this investigation are presented in viewgraph form.

Hathaway, Michael D.↗
NASA NTRS1992

MODIS algorithm development and data visualization using ACTS

The study of the Earth as a system will require the merger of scientific and data resources on a much larger scale than has been done in the past. New methods of scientific research, particularly in the development of geographically dispersed, interdisciplinary teams, are necessary if we are to understand the complexity of the Earth system. Even the planned satellite missions themselves, such as the Earth Observing System, will require much more interaction between researchers and engineers if they are to produce scientifically useful data products. A key component in these activities is the development of flexible, high bandwidth data networks that can be used to move large amounts of data as well as allow researchers to communicate in new ways, such as through video. The capabilities of the Advanced Communications Technology Satellite (ACTS) will allow the development of such networks. The Pathfinder global AVHRR data set and the upcoming SeaWiFS Earthprobe mission would serve as a testbed in which to develop the tools to share data and information among geographically distributed researchers. Our goal is to develop a 'Distributed Research Environment' that can be used as a model for scientific collaboration in the EOS era. The challenge is to unite the advances in telecommunications with the parallel advances in computing and networking.

Abbott, Mark R.↗
NASA NTRS1992

Modeling the performance of the human (pilot) interaction in a synthetic flight domain: Information theoretic approach

Current advances in computing technology are devoid of formal methods that describe the theories of how information is shared between humans and machines. Specifically, in the domain of human-machine interaction, a common mathematical foundation is lacking. The aim of this paper is to propose a formal method of human-machine (H-M) interaction paradigm from the information view point. The methods presented are interpretation- and context-free and can be used both in experimental analysis as well as in modeling problems.

Ntuen, Celestine A.↗
NASA NTRS1993

Modernization of the NASA scientific and technical information program

The NASA Scientific and Technical Information Program utilizes a technology infrastructure assembled in the mid 1960s to late 1970s to process and disseminate its information products. When this infrastructure was developed it placed NASA as a leader in processing STI. The retrieval engine for the STI database was the first of its kind and was used as the basis for developing commercial, other U.S., and foreign government agency retrieval systems. Due to the combination of changes in user requirements and the tremendous increase in technological capabilities readily available in the marketplace, this infrastructure is no longer the most cost-effective or efficient methodology available. Consequently, the NASA STI Program is pursuing a modernization effort that applies new technology to current processes to provide near-term benefits to the user. In conjunction with this activity, we are developing a long-term modernization strategy designed to transition the Program to a multimedia, global 'library without walls.' Critical pieces of the long-term strategy include streamlining access to sources of STI by using advances in computer networking and graphical user interfaces; creating and disseminating technical information in various electronic media including optical disks, video, and full text; and establishing a Technology Focus Group to maintain a current awareness of emerging technology and to plan for the future.

Cotter, Gladys A.↗
NASA NTRS1991

NASA Space Engineering Research Center for VLSI systems design

This annual review reports the center's activities and findings on very large scale integration (VLSI) systems design for 1990, including project status, financial support, publications, the NASA Space Engineering Research Center (SERC) Symposium on VLSI Design, research results, and outreach programs. Processor chips completed or under development are listed. Research results summarized include a design technique to harden complementary metal oxide semiconductors (CMOS) memory circuits against single event upset (SEU); improved circuit design procedures; and advances in computer aided design (CAD), communications, computer architectures, and reliability design. Also described is a high school teacher program that exposes teachers to the fundamentals of digital logic design.

Source record↗
NASA NTRS1993

SPOT4 Operational Control Center (CMP)

CNES(F) is responsible for the development of a new generation of Operational Control Center (CMP) which will operate the new heliosynchronous remote sensing satellite (SPOT4). This Operational Control Center takes large benefit from the experience of the first generation of control center and from the recent advances in computer technology and standards. The CMP is designed for operating two satellites all the same time with a reduced pool of controllers. The architecture of this CMP is simple, robust, and flexible, since it is based on powerful distributed workstations interconnected through an Ethernet LAN. The application software uses modern and formal software engineering methods, in order to improve quality and reliability, and facilitate maintenance. This software is table driven so it can be easily adapted to other operational needs. Operation tasks are automated to the maximum extent, so that it could be possible to operate the CMP automatically with very limited human interference for supervision and decision making. This paper provides an overview of the SPOTS mission and associated ground segment. It also details the CMP, its functions, and its software and hardware architecture.

Zaouche, G.↗
NASA NTRS1993

Design project: LONGBOW supersonic interceptor

A recent white paper entitled 'From the Sea' has spotlighted the need for Naval Aviation to provide overland support to joint operations. The base for this support, the Aircraft Carrier (CVN), will frequently be unable to operate within close range of the battleground because of littoral land-based air and subsurface threats. A high speed, long range, carrier capable aircraft would allow the CVN to provide timely support to distant battleground operations. Such an aircraft, operating as a Deck-Launched Interceptor (DLI), would also be an excellent counter to Next Generation Russian Naval Aviation (NGRNA) threats consisting of supersonic bombers, such as the Backfire, equipped with the next generation of high-speed, long-range missiles. Additionally, it would serve as an excellent high speed Reconnaissance airplane, capable of providing Battle Force commanders with timely, accurate pre-mission targeting information and post-mission Bomb Damage Assessment (BDA). Recent advances in computational hypersonic airflow modeling has produced a method of defining aircraft shapes that fit a conical shock flow model to maximize the efficiency of the vehicle. This 'Waverider' concept provides one means of achieving long ranges at high speeds. A Request for Proposal (RFP) was issued by Professor Conrad Newberry that contained design requirements for an aircraft to accomplish the above stated missions, utilizing Waverider technology.

Stoney, Robert↗
NASA NTRS1994

The Prediction of Nozzle Performance and Heat Transfer in Hydrogen/Oxygen Rocket Engines with Transpiration Cooling, Film Cooling, and High Area Ratios

An advanced engineering computational model has been developed to aid in the analysis of chemical rocket engines. The complete multispecies, chemically reacting and diffusing Navier-Stokes equations are modelled, including the Soret thermal diffusion and Dufour energy transfer terms. Demonstration cases are presented for a 1030:1 area ratio nozzle, a 25 lbf film-cooled nozzle, and a transpiration-cooled plug-and-spool rocket engine. The results indicate that the thrust coefficient predictions of the 1030:1 nozzle and the film-cooled nozzle are within 0.2 to 0.5 percent, respectively, of experimental measurements. Further, the model's predictions agree very well with the heat transfer measurements made in all of the nozzle test cases. It is demonstrated that thermal diffusion has a significant effect on the predicted mass fraction of hydrogen along the wall of the nozzle and was shown to represent a significant fraction of the diffusion fluxes occurring in the transpiration-cooled rocket engine.

Kacynski, Kenneth J.↗
NASA NTRS1994

An applications-oriented approach to the development of virtual environments

The field of Virtual Reality (VR) is diverse, ranging in scope from research into fundamental enabling technologies to the building of full-scale entertainment facilities. However, the concept of virtual reality means many things to many people. Ideally, a definition of VR should derive from how it can provide solutions to existing challenges in building advanced human computer interfaces. The measure of success for VR lies in its ability to enhance the assimilation of complex information, whether to aid in difficult decision making processes, or to recreate real experiences in a compelling way. This philosophy is described using an example from a VR-based advertising project. The common and unique elements of this example are explained, though the fundamental development process is the same for all virtual environments that support information transfer. In short, this development approach is an applications oriented approach that begins by establishing and prioritizing user requirements and seeks to add value to the information transfer process through the appropriate use of VR technology.

Crowe, Michael X.↗