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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 955 records · Page 53

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NASA NTRS1989

FFT-local gravimetric geoid computation

Model computations show that changes of sampling interval introduce only 0.3 cm changes, whereas zero padding provides an improvement of more than 5 cm in the fast Fourier transformation (FFT) generated geoid. For the Global Positioning System (GPS) survey of Franklin County, Ohio, the parameters selected as a result of model computations, allow large reduction in local data requirements while still retaining the cm accuracy when tapering and padding is applied. The results are shown in tables.

Nagy, Dezso↗

NASA NTRS1990

High resolution spectroscopy in the microwave and far infrared

High resolution rotational spectroscopy has long been central to remote sensing techniques in atmospheric sciences and astronomy. As such, laboratory measurements must supply the required data to make direct interpretation of data for instruments which sense atmospheres using rotational spectra. Spectral measurements in the microwave and far infrared regions are also very powerful tools when combined with infrared measurements for characterizing the rotational structure of vibrational spectra. In the past decade new techniques were developed which have pushed high resolution spectroscopy into the wavelength region between 25 micrometers and 2 mm. Techniques to be described include: (1) harmonic generation of microwave sources, (2) infrared laser difference frequency generation, (3) laser sideband generation, and (4) ultrahigh resolution interferometers.

Pickett, Herbert M.↗

NASA NTRS1990

High resolution infrared spectroscopy of planetary molecules using diode lasers and Fourier transform spectrometers

Modern observations of infrared molecular lines in planets are performed at spectral resolutions which are as high as those available in the laboratory. Analysis of such data requires laboratory measurements at the highest possible resolution, which also yield accurate line positions and intensities. For planetary purposes the spectrometer must be coupled to sample cells which can be reduced in temperature and varied in pressure. An approach which produces the full range of required molecular line parameters uses a combination of tunable diode lasers and Fourier transform spectrometers (FTS). The FTS provides board spectral coverage and good calibration accuracy, while the diode laser can be used to study those regions which are not resolved by the FTS.

Jennings, Donald E.↗

NASA NTRS1990

ERBE and CERES broadband scanning radiometers

Broadband scanning radiometers have been used extensively on earth-orbiting satellites to measure the Earth's outgoing radiation. The resulting estimates of longwave and shortwave fluxes have played an important role in helping to understand the Earth's radiant energy balance or budget. The Clouds and the Earth Radiant Energy System (CERES) experiment is expected to include instruments with three broadband scanning radiometers. The design of the CERES instrument will draw heavily from the flight-proven Earth Radiation Budget Experiment (ERBE) scanner instrument technology and will benefit from the several years of ERBE experience in mission operations and data processing. The discussion starts with a description of the scientific objectives of ERBE and CERES. The design and operational characteristics of the ERBE and CERES instrument are compared and the two ground-based data processing systems are compared. Finally, aspects of the CERES data processing which might be performed in near real-time aboard a spacecraft platform are discussed, and the types of algorithms and input data requirements for the onboard processing system are identified.

Weaver, William L.↗

NASA NTRS1990

On estimating scale invariance in stratocumulus cloud fields

Examination of cloud radiance fields derived from satellite observations sometimes indicates the existence of a range of scales over which the statistics of the field are scale invariant. Many methods were developed to quantify this scaling behavior in geophysics. The usefulness of such techniques depends both on the physics of the process being robust over a wide range of scales and on the availability of high resolution, low noise observations over these scales. These techniques (area perimeter relation, distribution of areas, estimation of the capacity, d0, through box counting, correlation exponent) are applied to the high resolution satellite data taken during the FIRE experiment and provides initial estimates of the quality of data required by analyzing simple sets. The results of the observed fields are contrasted with those of images of objects with known characteristics (e.g., dimension) where the details of the constructed image simulate current observational limits. Throughout when cloud elements and cloud boundaries are mentioned; it should be clearly understood that by this structures in the radiance field are meant: all the boundaries considered are defined by simple threshold arguments.

Seze, Genevieve↗

NASA NTRS1990

On the global exchange of mass between the stratosphere and troposphere

Seasonal mean downward mass fluxes across the 100 mb level in the extratropics of both hemispheres are computed using the meridionally integrated residual vertical circulation as determined from the transformed Eulerian mean equations. The eddy momentum and heat flux data required for the calculation are taken from Oort's 15-year climatology. Upward mass flux from the troposphere to the stratosphere in the tropics is computed from mass continuity. The flux is a maximum during Northern Hemisphere winter and a minimum during Northern Hemisphere summer. The computed fluxes imply a 2.5 year turnover time for the global atmospheric layer above 100 mb.

Holton, J. R.↗

NASA NTRS1989

Conceptual design of a Liquid Droplet Radiator space flight experiment

This paper discusses the conceptual design of a shuttle-attached Liquid Droplet Radiator (LDR) experiment. The Liquid Droplet Radiator is an advanced lightweight heat rejection concept that can be used to reject heat from future high-powered space platforms. In the LDR concept, submillimeter-sized droplets are generated, radiate heat as they pass through space and are then collected and recirculated back to the heat source. The LDR experiment is designed to be attached to the shuttle longeron and integrated into the shuttle bay using standard shuttle/experiment interfaces. Overall power, weight, and data requirements of the experiment are detailed. Conceptual design and shuttle integration issues are discussed.

Pfeiffer, S.↗

NASA NTRS1990

Space station structural performance experiment

A flight experiment that could be used to measure Space Station dynamics during and after its assembly is discussed. By integrating sensors into the structure to measure its ambient dynamic responses, it will provide some information as to how it behaves during its evolution. The objectives of the experiment are to define a series of experiments to measure the dynamic responses due to disturbances to establish the experiment scenarios, and to identify the locations of the instrumentation that can be integrated into the structure. Researchers have also defined the Space Station resources that are required so that they can be included in the Mission Requirements Data Base (MRDB). They used the 16-flight-assembly scenario that was recommended by Rockwell as the baseline.

Gates, Dick↗

NASA NTRS1991

A proposal to extend our understanding of the global economy

Satellites acquire information on a global and repetitive basis. They are thus ideal tools for use when global scale and analysis over time is required. Data from satellites comes in digital form which means that it is ideally suited for incorporation in digital data bases and that it can be evaluated using automated techniques. The development of a global multi-source data set which integrates digital information is proposed regarding some 15,000 major industrial sites worldwide with remotely sensed images of the sites. The resulting data set would provide the basis for a wide variety of studies of the global economy. The preliminary results give promise of a new class of global policy model which is far more detailed and helpful to local policy makers than its predecessors. The central thesis of this proposal is that major industrial sites can be identified and their utilization can be tracked with the aid of satellite images.

Hough, Robbin R.↗

NASA NTRS1990

User's guide to PANCOR: A panel method program for interference assessment in slotted-wall wind tunnels

Guidelines are presented for use of the computer program PANCOR to assess the interference due to tunnel walls and model support in a slotted wind tunnel test section at subsonic speeds. Input data requirements are described in detail and program output and general program usage are described. The program is written for effective automatic vectorization on a CDC CYBER 200 class vector processing system.

Kemp, William B., Jr.↗

NASA NTRS1991

Report of the panel on volcanology, section 4

Two primary goals are identified as focal to NASA's research efforts in volcanology during the 1990s: to understand the eruption of lavas, gases, and aerosols from volcanoes, the dispersal of these materials on the Earth's surface and through the atmosphere, and the effects of these eruptions on the climate and environment; and to understand the physical processes that lead to the initiation of volcanic activity, that influence the styles of volcanic eruptions, and that dictate the morphology and evolution of volcanic landforms. Strategy and data requirements as well as research efforts are discussed.

Francis, Peter W.↗

NASA NTRS1991

Effects of rotation on coolant passage heat transfer. Volume 1: Coolant passages with smooth walls

An experimental program was conducted to investigate heat transfer and pressure loss characteristics of rotating multipass passages, for configurations and dimensions typical of modern turbine blades. The immediate objective was the generation of a data base of heat transfer and pressure loss data required to develop heat transfer correlations and to assess computational fluid dynamic techniques for rotating coolant passages. Experiments were conducted in a smooth wall large scale heat transfer model.

Hajek, T. J.↗

NASA NTRS1990

CCSDS - An approach to the definition of common standards for understanding space-related data

International cooperation for space data projects requires common data processing goals and unique data exchange mechanisms. The absence of standards has led to project unique interface definitions and special software on diverse systems. To address this problem, CCSDS Panel 2 is creating a set of standards to support self description of data using standard structures. The proposed standard data interchange mechanism - the Standard Formatted Data Unit (SFDU) - reduces information loss in data transfers, increases automated information exchange, and extends the lifetime of data. Data interchange structures, languages, and services are being developed with necessary control functions to provide these benefits. A set of recommendations for agency review has been issued this year to be the basis for future data exchange and to enhance access to older mission data sets. Space agencies and other space data handling facilities are being encouraged to implement the SFDU concept for ongoing and planned projects.

Drexler, Manfred↗

NASA NTRS1991

Calorimetric output power measurements on a CW 20 kW 7.16 GHz microwave transmitter

A calorimetric measurement technique developed for NASA's Deep Space Network (DSN) transmitters that does not require data on the coolant's thermal parameters is described. Calibration of the measurement system is achieved by measuring the DC input power to the klystron and relating coolant temperature increases to this known power dissipation. Agreement between calorimetric and electrical measurements of total system power was good, the difference being less than 2 percent. The operation of the system was not greatly affected by the composition of the coolant, which was varied from pure water to 40 percent ethylene glycol by mass. Good accuracy was also shown at output power levels, which varied over a 3.6:1 range.

Perez, Raul M.↗

NASA NTRS1991

Flight dynamics facility operational orbit determination support for the ocean topography experiment

The Ocean Topography Experiment (TOPEX/POSEIDON) mission is designed to determine the topography of the Earth's sea surface across a 3 yr period, beginning with launch in June 1992. The Goddard Space Flight Center Dynamics Facility has the capability to operationally receive and process Tracking and Data Relay Satellite System (TDRSS) tracking data. Because these data will be used to support orbit determination (OD) aspects of the TOPEX mission, the Dynamics Facility was designated to perform TOPEX operational OD. The scientific data require stringent OD accuracy in navigating the TOPEX spacecraft. The OD accuracy requirements fall into two categories: (1) on orbit free flight; and (2) maneuver. The maneuver OD accuracy requirements are of two types; premaneuver planning and postmaneuver evaluation. Analysis using the Orbit Determination Error Analysis System (ODEAS) covariance software has shown that, during the first postlaunch mission phase of the TOPEX mission, some postmaneuver evaluation OD accuracy requirements cannot be met. ODEAS results also show that the most difficult requirements to meet are those that determine the change in the components of velocity for postmaneuver evaluation.

Bolvin, D. T.↗

NASA NTRS1992

Designing a Methodology for Future Air Travel Scenarios

The growing demand on air travel throughout the world has prompted several proposals for the development of commercial aircraft capable of transporting a large number of passengers at supersonic speeds. Emissions from a projected fleet of such aircraft, referred to as high-speed civil transports (HSCT's), are being studied because of their possible effects on the chemistry and physics of the global atmosphere, in particular, on stratospheric ozone. At the same time, there is growing concern about the effects on ozone from the emissions of current (primarily subsonic) aircraft emissions. Evaluating the potential atmospheric impact of aircraft emissions from HSCT's requires a scientifically sound understanding of where the aircraft fly and under what conditions the aircraft effluents are injected into the atmosphere. A preliminary set of emissions scenarios are presented. These scenarios will be used to understand the sensitivity of environment effects to a range of fleet operations, flight conditions, and aircraft specifications. The baseline specifications for the scenarios are provided: the criteria to be used for developing the scenarios are defined, the required data base for initiating the development of the scenarios is established, and the state of the art for those scenarios that have already been developed is discussed. An important aspect of the assessment will be the evaluation of realistic projections of emissions as a function of both geographical distribution and altitude from an economically viable commercial HSCT fleet. With an assumed introduction date of around the year 2005, it is anticipated that there will be no HSCT aircraft in the global fleet at that time. However, projections show that, by 2015, the HSCT fleet could reach significant size. We assume these projections of HSCT and subsonic fleets for about 2015 can the be used as input to global atmospheric chemistry models to evaluate the impact of the HSCT fleets, relative to an all-subsonic future fleet. The methodology, procedures, and recommendations for the development of future HSCT and the subsonic fleet scenarios used for this evaluation are discussed.

Wuebbles, Donald J.↗

NASA NTRS1992

Mentat/A: Medium grain parallel processing

The objective of this project is to support the Algorithm to Architecture Mapping Model (ATAMM) firing rules using the Mentat run-time system and the Mentat Programming Language (MPL). Specifically, this required changes to (1) modify the run-time system to control queue length and inhibit actor firing until required data tokens are available and space is available in the input queues of all of the direct descendent actors, (2) disallow the specification of persistent object classes in the MPL, and (3) permit only decision free graphs in the MPL. We have been successful in implementing the spirit of the plan, although some goals changed as we came to better understand the problem. Here, we report on what we accomplished and the lessons we learned. The Mentat/A runtime system, the compiler, results for three applications, and a summary and some observations are given. Appendix A contains a list of technical reports and published papers partially supported by the grant. Appendix B contains listings for the three applications.

Grimshaw, Andrew S.↗

NASA NTRS1992

Mentat/A: Medium grain parallel processing

The objective of this project is to test the Algorithm to Architecture Mapping Model (ATAMM) firing rules using the Mentat run-time system and the Mentat Programming Language (MPL). A special version of Mentat, Mentat/A (Mentat/ATAMM) was constructed. This required changes to: (1) modify the run-time system to control queue length and inhibit actor firing until required data tokens are available and space is available in the input queues of all of the direct descendent actors; (2) disallow the specification of persistent object classes in the MPL; and (3) permit only decision free graphs in the MPL. We were successful in implementing the spirit of the plan, although some goals changed as we came to better understand the problem. We report on what we accomplished and the lessons we learned. The Mentat/A run-time system is discussed, and we briefly present the compiler. We present results for three applications and conclude with a summary and some observations. Appendix A contains a list of technical reports and published papers partially supported by the grant. Appendix B contains listings for the three applications.

Grimshaw, Andrew S.↗