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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Proceedings: Fourth Parabolic Dish Solar Thermal Power Program Review

The results of activities within the parabolic dish technology and applications development program are presented. Stirling, organic Rankine and Brayton module technologies, associated hardware and test results to date; concentrator development and progress; economic analyses; and international dish development activities are covered. Two panel discussions, concerning industry issues affecting solar thermal dish development and dish technology from a utility/user perspective, are also included.

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NASA NTRS1982

A means for utilizing ancillary information in multispectral classification

Attention is given to a method which makes it possible to incorporate information from ancillary data sources into the results of an existing classification of remotely sensed data. The method is based upon probabilistic label relaxation procedures which are used for imbedding spatial context data in image-labeling problems. The source of ancillary information is utilized in the form of a set of probabilities. These are introduced into a modified relaxation method called supervised relaxation labeling which, on application, develops a labeling for remotely sensed data that strikes a balance in consistency between spectral, spatial, and ancillary data sources of information. A description is given of results of a forestry classification in which accuracy is improved from 68% to 81% by incorporating topographic elevation in the outlined manner.

Richards, J. A.↗
NASA NTRS1983

Constraints on the invariant functions of axisymmetric turbulence

Constraints are derived for the two invariant functions Q1 and Q2 that occur in Chandrasekhar's (1950) development of the axisymmetric turbulence theory. These constraints must be satisfied for the correlation tensor derived from Q1 and Q2 to be that of a stationary random process, i.e., for the turbulence to be realizable. The equivalent results in spectrum space are also developed. Applications of the constraints in aerodynamic noise modeling are discussed. It is shown that significant errors in prediction can be introduced by the use of turbulence models which violate the constraints.

Kerschen, E. J.↗
NASA NTRS1984

Tools for active control system design

Efficient control law analysis and design tools which properly account for the interaction of flexible structures, unsteady aerodynamics and active controls are developed. Development, application, validation and documentation of efficient multidisciplinary computer programs for analysis and design of active control laws are also discussed.

Adams, W. M., Jr.↗
NASA NTRS1984

The 3SPACE digitizer: A new input device for solid geometry modeling

The 3SPACE Digitizer is a derivation of SPASYN, which is a patented magnetic transducing system offering an accurate method of calculating the location of one object relative to another. SPASYN uses low-frequency magnetic fields to measure both the position and orientation of its sensor relative to its transmitter. The 3SPACE Digitizer unit consists of a system's electronics unit, a model table, a stylus, and a keypad. In operation, the 3SPACE Digitizer determines the X, Y, Z coordinates of any point located on a low-conductive, three-dimensional model. This data, along with the orientation of the Digitizer's stylus, is immediately available for transmission to a host computer or graphics terminal. Digitization is effected by touching the point to be measured with the tip of a handheld stylus. The 3SPACE Digitizer presents new opportunities for interacting with computers in a large number of engineering and scientific applications. Developed from proven military technology, the 3SPACE Digitizer significantly simplifies three-dimensional digitization and overcomes many of the problems that once plagued such procedures. Its ability to digitize solid objects makes it a valuable new tool for computer-aided design and manufacturing.

Scully, J.↗
NASA NTRS1985

Damage and Repair of Composite Structures

NASA technical memorandum reports on research in damage and repair of composite-material structures of types used in airplane. Research includes: Identifying defect areas, determining whether particular kind of damage weakens structure in manner that degrades performance in intended application, developing repair procedures, and testing to demonstrate given repair procedure enables component to serve during remainder of its design life.

Deaton, J. W.↗
NASA NTRS1984

SAGA: A project to automate the management of software production systems

The project to automate the management of software production systems is described. The SAGA system is a software environment that is designed to support most of the software development activities that occur in a software lifecycle. The system can be configured to support specific software development applications using given programming languages, tools, and methodologies. Meta-tools are provided to ease configuration. Several major components of the SAGA system are completed to prototype form. The construction methods are described.

Campbell, R. H.↗
NASA NTRS1983

A function space approach to state and model error estimation for elliptic systems

An approach is advanced for the concurrent estimation of the state and of the model errors of a system described by elliptic equations. The estimates are obtained by a deterministic least-squares approach that seeks to minimize a quadratic functional of the model errors, or equivalently, to find the vector of smallest norm subject to linear constraints in a suitably defined function space. The minimum norm solution can be obtained by solving either a Fredholm integral equation of the second kind for the case with continuously distributed data or a related matrix equation for the problem with discretely located measurements. Solution of either one of these equations is obtained in a batch-processing mode in which all of the data is processed simultaneously or, in certain restricted geometries, in a spatially scanning mode in which the data is processed recursively. After the methods for computation of the optimal esimates are developed, an analysis of the second-order statistics of the estimates and of the corresponding estimation error is conducted. Based on this analysis, explicit expressions for the mean-square estimation error associated with both the state and model error estimates are then developed. While this paper focuses on theoretical developments, applications arising in the area of large structure static shape determination are contained in a closely related paper (Rodriguez and Scheid, 1982).

Rodriguez, G.↗
NASA NTRS1984

Assessment of US industry's technology trends and new technology requirements

The utility and effectiveness of a novel approach (the Applications Development, or AD approach), intended to augment the efficiency of NASA's technology utilization (TU) through dissemination of NASA technologies and joint technology development efforts with U.S. industry is tested. The innovative AD approach consists of the following key elements: selection of NASA technologies appearing to have leading edge attributes; interaction with NASA researchers to assess the characteristics and quality of each selected technology; identification of industry's needs in the selected technology areas; structuring the selected technologies in terms of specifications and standards familiar to industry (industrial Spec. Sheets); identification and assessment of industry's interest in the specific selected NASA technologies, utilizing the greatly facilitated communication made possible by the availability of the industrial Spec. Sheets; and matching selected NASA technologies with the needs of selected industries.

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NASA NTRS1988

Validation of expert systems

The validation of expert systems (ESs) has only recently become an active AI research topic. Current approaches have concentrated mainly on the validation of rule properties of such systems. The efforts presented improves on current methods by also exploiting the structural and semantic information of such systems. To increase programmer productivity, more and more companies have begun exploiting the advent of AI technology by developing applications using ES shells or other AI-based high level program generators. The architecture, functionality, and future goals of Expert Systems Validation are described along with the features that have been implemented for and in Automated Reasoning Tool, the ES shell presented.

Stachowitz, Rolf A.↗
NASA NTRS1987

Foil bearing lubrication theory including compressibility effects

An analysis is presented to determine the film thickness in a foil bearing. Using the Reynolds equation and including the compressibility effects of the gas, an equation was developed applicable to the film thickness in a foil bearing. The bearing was divided into three regions, namely, the entrance region, middle region and exit region. Solutions are obtained for the film thickness in each region.

Gorla, Rama Subba Reddy↗
NASA NTRS1988

Adaptive servo control for umbilical mating

Robotic applications at Kennedy Space Center are unique and in many cases require the fime positioning of heavy loads in dynamic environments. Performing such operations is beyond the capabilities of an off-the-shelf industrial robot. Therefore Robotics Applications Development Laboratory at Kennedy Space Center has put together an integrated system that coordinates state of the art robotic system providing an excellent easy to use testbed for NASA sensor integration experiments. This paper reviews the ways of improving the dynamic response of the robot operating under force feedback with varying dynamic internal perturbations in order to provide continuous stable operations under variable load conditions. The goal is to improve the stability of the system with force feedback using the adaptive control feature of existing system over a wide range of random motions. The effect of load variations on the dynamics and the transfer function (order or values of the parameters) of the system has been investigated, more accurate models of the system have been determined and analyzed.

Zia, Omar↗
NASA NTRS1984

A performance evaluation of the IBM 370/XT personal computer

An evaluation of the IBM 370/XT personal computer is given. This evaluation focuses primarily on the use of the 370/XT for scientific and technical applications and applications development. A measurement of the capabilities of the 370/XT was performed by means of test programs which are presented. Also included is a review of facilities provided by the operating system (VM/PC), along with comments on the IBM 370/XT hardware configuration.

Dominick, Wayne D.↗
NASA NTRS1989

The evolution of space mechanisms in the ESA R and D program

The status of recently completed and already ongoing technology developments, as well as some of the most important future developments of the European Space Agency are discussed. Among the subjects considered are Scientific Satellites, Columbus space station development, applications spacecraft for communications, Earth observation and meteorology, and the Ariane V and Hermes space transportation systems.

Wyn-Roberts, D.↗
NASA NTRS1989

Real-time simulation of an F110/STOVL turbofan engine

A traditional F110-type turbofan engine model was extended to include a ventral nozzle and two thrust-augmenting ejectors for Short Take-Off Vertical Landing (STOVL) aircraft applications. Development of the real-time F110/STOVL simulation required special attention to the modeling approach to component performance maps, the low pressure turbine exit mixing region, and the tailpipe dynamic approximation. Simulation validation derives by comparing output from the ADSIM simulation with the output for a validated F110/STOVL General Electric Aircraft Engines FORTRAN deck. General Electric substantiated basic engine component characteristics through factory testing and full scale ejector data.

Drummond, Colin K.↗
NASA NTRS1989

Reliable broadcast protocols

A number of broadcast protocols that are reliable subject to a variety of ordering and delivery guarantees are considered. Developing applications that are distributed over a number of sites and/or must tolerate the failures of some of them becomes a considerably simpler task when such protocols are available for communication. Without such protocols the kinds of distributed applications that can reasonably be built will have a very limited scope. As the trend towards distribution and decentralization continues, it will not be surprising if reliable broadcast protocols have the same role in distributed operating systems of the future that message passing mechanisms have in the operating systems of today. On the other hand, the problems of engineering such a system remain large. For example, deciding which protocol is the most appropriate to use in a certain situation or how to balance the latency-communication-storage costs is not an easy question.

Joseph, T. A.↗
NASA NTRS1990

Observation simulation experiments with regional prediction models

Research efforts in FY 1990 included studies employing regional scale numerical models as aids in evaluating potential contributions of specific satellite observing systems (current and future) to numerical prediction. One study involves Observing System Simulation Experiments (OSSEs) which mimic operational initialization/forecast cycles but incorporate simulated Advanced Microwave Sounding Unit (AMSU) radiances as input data. The objective of this and related studies is to anticipate the potential value of data from these satellite systems, and develop applications of remotely sensed data for the benefit of short range forecasts. Techniques are also being used that rely on numerical model-based synthetic satellite radiances to interpret the information content of various types of remotely sensed image and sounding products. With this approach, evolution of simulated channel radiance image features can be directly interpreted in terms of the atmospheric dynamical processes depicted by a model. Progress is being made in a study using the internal consistency of a regional prediction model to simplify the assessment of forced diabatic heating and moisture initialization in reducing model spinup times. Techniques for model initialization are being examined, with focus on implications for potential applications of remote microwave observations, including AMSU and Special Sensor Microwave Imager (SSM/I), in shortening model spinup time for regional prediction.

Diak, George↗