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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Ice classification algorithm development and verification for the Alaska SAR Facility using aircraft imagery

The Alaska SAR Facility (ASF) at the University of Alaska, Fairbanks is a NASA program designed to receive, process, and archive SAR data from ERS-1 and to support investigations that will use this regional data. As part of ASF, specialized subsystems and algorithms to produce certain geophysical products from the SAR data are under development. Of particular interest are ice motion, ice classification, and ice concentration. This work focuses on the algorithm under development for ice classification, and the verification of the algorithm using C-band aircraft SAR imagery recently acquired over the Alaskan arctic.

Holt, Benjamin↗
NASA NTRS1990

Prediction of inlet drag for aircraft conceptual design

Recent efforts to upgrade conceptual design program ACSYNT have resulted in a study of methods for inlet drag prediction. These methods enable the drag of four different inlet types (the subsonic pitot, supersonic pitot, supersonic two-dimensional and supersonic conical inlets) to be predicted over the complete operating range of the inlet. The methods, which have been incorporated into ACSYNT, are presented here, together with sample applications to different inlet geometries.

Malan, P.↗
NASA NTRS1991

Fade-durations derived from land-mobile-satellite measurements in Australia

Transmissions from the Japanese ETS-V geostationary satellite were measured at L band (1.5 GHz) in a vehicle driving on roads of southeastern Australia. The measurements were part of a program designed to characterize propagation effects due to roadside trees and terrain for mobile satellite service. It is shown that the cumulative distributions of fade and nonfade durations follow a lognormal and power law, respectively. At 1 percent probability, fades last 2-8 m, and nonfades 10-100 m, depending on the degree of shadowing. Phase fluctuations are generally small, allowing the channel characteristics to be estimated from levels only.

Hase, Yoshihiro↗
NASA NTRS1992

Software For Generating Graphs And Charts

Common Graphics Library (CGL) computer program designed to enable users to generate graphs and charts of quality sufficient for publication or optical projection. Quickly and easily generates linear, logarithmic, bar, pie, and composite charts. Features of linear charts include automatic scaling, increasing or decreasing numerical axes, and character axes. Features of pie charts include segment labels, exploded segments, and chart keys. One of general features, horizontal or vertical orientation of figures. Written in ANSI FORTRAN 77.

Hammond, Dana P.↗
NASA NTRS1992

Estimating Effects Of Rain On Ground/Satellite Communication

LeRC-SLAM provides static and dynamic statistical assessment of impact of attenuation by rain on communication link established between Earth terminal and geosynchronous satellite. Program designed for use in specification, design, and assessment of satellite link for any terminal location in continental United States. IBM PC version written in Microsoft QuickBASIC, and Macintosh version written in Microsoft Basic.

Manning, R. M.↗
NASA NTRS1992

Software For Monitoring A Computer Network

SNMAT is rule-based expert-system computer program designed to assist personnel in monitoring status of computer network and identifying defective computers, workstations, and other components of network. Also assists in training network operators. Network for SNMAT located at Space Flight Operations Center (SFOC) at NASA's Jet Propulsion Laboratory. Intended to serve as data-reduction system providing windows, menus, and graphs, enabling users to focus on relevant information. SNMAT expected to be adaptable to other computer networks; for example in management of repair, maintenance, and security, or in administration of planning systems, billing systems, or archives.

Lee, Young H.↗
NASA NTRS1990

In situ ozone measurements for the airborne arctic stratospheric experiment

The research provided in-situ ozone measurements onboard the NASA Ames DC-8 research aircraft during the 1989 Airborne Arctic Stratospheric Experiment. The Ames DC-8 and ER-2 aircraft performed extensive sampling of the Arctic stratosphere and troposphere in a program designed to study those factors important in ozone depletion in the Arctic during times when the polar vortex and meteorology are conducive to the formation of polar stratospheric clouds and/or an Arctic ozone hole. The DC-8 ozone instrument complement included in-situ measurements for H2O, NO, NO2, NO(y) gas, NO(y) particulate, as well as remote sensors for measuring the vertical distribution and column density of ozone above the aircraft altitude. The in-situ data (ozone, water vapor, and nitrogen species) at the aircraft altitude provide a definition of tropospheric conditions in the vicinity of the polar vortex and polar stratospheric clouds. Defining tropospheric conditions will assist in the understanding of the chemistry of both stratosphere and troposphere and the extent to which polar stratospheric clouds affect the chemistry of transported air.

Gregory, Gerald L.↗
NASA NTRS1992

Reliability analysis of laminated CMC components through shell subelement techniques

An updated version of the integrated design program Composite Ceramics Analysis and Reliability Evaluation of Structures (C/CARES) was developed for the reliability evaluation of ceramic matrix composites (CMC) laminated shell components. The algorithm is now split into two modules: a finite-element data interface program and a reliability evaluation algorithm. More flexibility is achieved, allowing for easy implementation with various finite-element programs. The interface program creates a neutral data base which is then read by the reliability module. This neutral data base concept allows easy data transfer between different computer systems. The new interface program from the finite-element code Matrix Automated Reduction and Coupling (MARC) also includes the option of using hybrid laminates (a combination of plies of different materials or different layups) and allows for variations in temperature fields throughout the component. In the current version of C/CARES, a subelement technique was implemented, enabling stress gradients within an element to be taken into account. The noninteractive reliability function is now evaluated at each Gaussian integration point instead of using averaging techniques. As a result of the increased number of stress evaluation points, considerable improvements in the accuracy of reliability analyses were realized.

Starlinger, Alois↗
NASA NTRS1990

Oscillating flow loss test results in Stirling engine heat exchangers

The results are presented for a test program designed to generate a database of oscillating flow loss information that is applicable to Stirling engine heat exchangers. The tests were performed on heater/cooler tubes of various lengths and entrance/exit configurations, on stacked and sintered screen regenerators of various wire diameters and on Brunswick and Metex random fiber regenerators. The test results were performed over a range of oscillating flow parameters consistent with Stirling engine heat exchanger experience. The tests were performed on the Sunpower oscillating flow loss rig which is based on a variable stroke and variable frequency linear drive motor. In general, the results are presented by comparing the measured oscillating flow losses to the calculated flow losses. The calculated losses are based on the cycle integration of steady flow friction factors and entrance/exit loss coefficients.

Koester, G.↗
NASA NTRS1991

The polarization lidar technique for cloud research - A review and current assessment

The development of the polarization lidar technique is reviewed, and the current capabilities and limitations of the technique for the cloud research are discussed. At present, polarization lidar is a key component of climate-research programs designed to characterize the properties of cirrus clouds and is an integral part of multiple remote-sensor studies of mixed-phase cloud systems such as winter mountain storms, making it possible to discriminate between cloud phases and to identify some particle types and orientations. Recent theoretical approaches involving ice crystal ray-tracing and cloud microphysical-model simulations are expected to increase the utility of the polarization lidar technique.

Sassen, Kenneth↗
NASA NTRS1991

Space commerce - Preparing for the next century

The role of NASA in space commerce is discussed in terms of providing direct assistance to the private sector and in terms of the most suitable industrial areas for such support. The primary mechanism for such support is the program of Centers for the Commercial Development of Space (CCDS) which selects industrial high-technology projects to help make them viable. The research spans such fields as remote sensing, crop forecasting, and microgravity materials processing. The collaboration of NASA and private industry is discussed in terms of sounding-rocket projects, the Commercial Experiment Transporter, and academic/industrial programs designed to generate enthusiasm for commercial space research. The future of such research is expected to focus on CCDSs for microgravity-developed products, commercial infrastructure, SEI, and commercial use of the Space Station Freedom.

Stone, Barbara A.↗
NASA NTRS1991

Instrumentation and calibration issues for Space Station Freedom and future space projects

Space-based instrumentation calibration for long duration and remote space missions is discussed. The traditional approach, in which instrumentation was an afterthought in the space program design process and calibration was not even addressed until after design was completed, are discussed. Current issues and approaches to calibration are discussed, and guidelines are developed to instrumentation calibration for the Space Station Freedom and beyond.

Bushman, David M.↗
NASA NTRS1992

Reliability analysis of laminated CMC components through shell subelement techniques

An updated version of the integrated design program C/CARES (composite ceramic analysis and reliability evaluation of structures) was developed for the reliability evaluation of CMC laminated shell components. The algorithm is now split in two modules: a finite-element data interface program and a reliability evaluation algorithm. More flexibility is achieved, allowing for easy implementation with various finite-element programs. The new interface program from the finite-element code MARC also includes the option of using hybrid laminates and allows for variations in temperature fields throughout the component.

Starlinger, A.↗
NASA NTRS1992

Experimental verification of scaling parameters for thermal stratification

A study to determine important dimensionless parameters associated with thermal stratification of a heated container of liquid, and the pressure history of its vapor, was performed. Analysis of the governing equations identified the modified Grashoff number, the modified Fourier number, and the interface number as the dominant dimensionless parameters associated with this process. A test program designed to verify the validity of these scaling parameters was executed. The quality of scaling was checked by comparing the dimensionless pressures and temperatures for scaled pairs of tests. Results indicate that the bulk liquid temperature, the surface temperature of the liquid, and the tank pressure can be scaled with the three dimensionless parameters. Some deviations were found in the detailed temperature profiles between the scaled pairs of tests.

Ji, H.-C.↗
NASA NTRS1991

Avionic architecture requirements for Space Exploration Initiative systems

The authors discuss NASA's Strategic Avionics Technology Working Group (SATWG) and the results of the first study commissioned by the SATWG, the Space Avionics Requirements Study (SARS). The goal of the SARS task was to show that an open avionics architecture, using modular, standardized components, could be applied across the wide range of systems that comprise the Space Exploration Initiative. The study addressed systems ranging from expendable launch vehicles and the space station to surface systems such as Mars or lunar rovers and habitats. Top-level avionics requirements were derived from characterizations of each of the systems considered. Then a set of avionics subsystems were identified, along with estimates of the numbers and types of modules needed to meet the requirements. Applicability of these results across the infrastructure was then illustrated. In addition to these tasks, critical technologies were identified, characterized, and assessed in terms of their criticality and impact on the program. Design, development, test, and evaluation methods were addressed to identify potential areas of improvement.

Herbella, C. G.↗
NASA NTRS1993

Thermal Radiation Analyzer System (TRASYS)

Working alone or with SINDA '85/FLUINT, TRASYS solves radiation components of thermal analysis problems. Calculates both internode radiation exchange and incident and absorbed heat rate due to sunlight. Used in satellite design, program handles situations where one surface wholly or partially shades another from direct sunlight.

Vogt, R. A.↗
NASA NTRS1992

Description of the SSF PMAD DC testbed control system data acquisition function

The NASA LeRC in Cleveland, Ohio has completed the development and integration of a Power Management and Distribution (PMAD) DC Testbed. This testbed is a reduced scale representation of the end to end, sources to loads, Space Station Freedom Electrical Power System (SSF EPS). This unique facility is being used to demonstrate DC power generation and distribution, power management and control, and system operation techniques considered to be prime candidates for the Space Station Freedom. A key capability of the testbed is its ability to be configured to address system level issues in support of critical SSF program design milestones. Electrical power system control and operation issues like source control, source regulation, system fault protection, end-to-end system stability, health monitoring, resource allocation, and resource management are being evaluated in the testbed. The SSF EPS control functional allocation between on-board computers and ground based systems is evolving. Initially, ground based systems will perform the bulk of power system control and operation. The EPS control system is required to continuously monitor and determine the current state of the power system. The DC Testbed Control System consists of standard controllers arranged in a hierarchical and distributed architecture. These controllers provide all the monitoring and control functions for the DC Testbed Electrical Power System. Higher level controllers include the Power Management Controller, Load Management Controller, Operator Interface System, and a network of computer systems that perform some of the SSF Ground based Control Center Operation. The lower level controllers include Main Bus Switch Controllers and Photovoltaic Controllers. Power system status information is periodically provided to the higher level controllers to perform system control and operation. The data acquisition function of the control system is distributed among the various levels of the hierarchy. Data requirements are dictated by the control system algorithms being implemented at each level. A functional description of the various levels of the testbed control system architecture, the data acquisition function, and the status of its implementationis presented.

Baez, Anastacio N.↗
NASA NTRS1992

Direct Broadcast Satellite: Radio Program

NASA is committed to providing technology development that leads to the introduction of new commercial applications for communications satellites. The Direct Broadcast Satellite-Radio (DBS-R) Program is a joint effort between The National Aeronautics and Space Administration (NASA) and The United States Information Agency/Voice of America (USIA/VOA) directed at this objective. The purpose of this program is to define the service and develop the technology for a direct-to-listener satellite sound broadcasting system. The DBS-R Program, as structured by NASA and VOA, is now a three-phase program designed to help the U.S. commercial communications satellite and receiver industry bring about this new communications service. Major efforts are being directed towards frequency planning hardware and service development, service demonstration, and experimentation with new satellite and receiver technology.

Hollansworth, James E.↗