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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Field size distributions for selected agricultural crops in the United States and Canada

Digitized agricultural field boundary taken in the United States and Canada during the LACIE and AgRISTARS programs, in 1977 through 1980, were used to construct histograms showing the distributions of field area, width, and length for crops for which there were data for 700 or more fields per state. The observed distributions of area and width for fields of 10 crops grown in 13 states of the United States and Canada were compared with best-fit inverse Gaussian distributions and with log-normal distributions. For 28 distributions of area and 16 distributions of width there was found to be a probability of greater than .01 of their being inverse Gaussian. There were 10 distributions of area for which there was probability of greater than .005 of their being log-normal. Distributions of area and width stratified by state and crop type appear to be unique. The inverse Gaussian, which represents a wide range of statistical distributions from skewed to almost symmetrical, can provide a useful model for distributions of field area.

Ferguson, M. C.↗
NASA NTRS1986

Orbital flight simulation utility software unit specifications

The HP PASCAL source code contained in pages 6 through 104 was developed for the Mission Planning and Analysis Division (MPAD) and takes the place of detailed flow charts defining the specifications for a Utility Software Unit designed to support orbital flight simulators such as MANHANDLE and GREAS (General Research and Engineering Analysis Simulator). Besides providing basic input/output, mathematical, vector, matrix, quaternion, and statistical routines for such simulators, one of the primary functions of the Utility Software Unit is to isolate all system-dependent code in one well-defined compartment, thereby facilitating transportation of the simulations from one computer to another. Directives to the PASCAL compilers of the HP-9000 Series 200 PASCAL 3.0 operating system and the HP-9000 Series 500 HP-UX 5.0 operations systems are also provided.

Wilson, S. W.↗
NASA NTRS1987

Development of a standard connector for orbital replacement units for serviceable spacecraft

The current trend for spacecraft to be serviceable and repairable in orbit has led to a modular approach to satellite subsystem design. Spacecraft equipment, such as sensors, tape recorders, computers, transponders, batteries, etc., housed in discrete modular units, (Orbital Replacement Units(ORUs)) can be attached and detached to the spacecraft as needed. The interface between the ORU and the spacecraft is crucial. The projected use of robotics and the need for a common mechanism capable of performing several functions puts many constraints on the design of the interface. Such an interface mechanisms was designed and developed called the Standard Interface Connector (SIC) that mates the ORU to the spacecraft. The SIC also provides for the flow of fluids, data, and power between the module and spacecraft. The baseline design presented can be configured to provide various attachment schemes. Tests on SIC models have demonstrated the functionality of the design and its compatibility with current robotics.

Heath, Ellen F.↗
NASA NTRS1986

A study of the use of abstract types for the representation of engineering units in integration and test applications

Physical quantities using various units of measurement can be well represented in Ada by the use of abstract types. Computation involving these quantities (electric potential, mass, volume) can also automatically invoke the computation and checking of some of the implicitly associable attributes of measurements. Quantities can be held internally in SI units, transparently to the user, with automatic conversion. Through dimensional analysis, the type of the derived quantity resulting from a computation is known, thereby allowing dynamic checks of the equations used. The impact of the possible implementation of these techniques in integration and test applications is discussed. The overhead of computing and transporting measurement attributes is weighed against the advantages gained by their use. The construction of a run time interpreter using physical quantities in equations can be aided by the dynamic equation checks provided by dimensional analysis. The effects of high levels of abstraction on the generation and maintenance of software used in integration and test applications are also discussed.

Johnson, Charles S.↗
NASA NTRS1989

Block diagrams of the radar interface and control unit

The Interface and Control Unit is the heart of the radar module, which occupies one complex channel of the High-Speed Data Acquisition System of the Goldstone Solar System Radar. Block diagrams of the interface unit are presented as an aid to understanding its operation and interconnections to the rest of the radar module.

Collier, J. W.↗
NASA NTRS1989

The impact of summer rainfall on the temperature gradient along the United States-Mexico border

The international border running through the Sonoran Desert in southern Arizona and northern Sonora is marked by a sharp discontinuity in albedo and grass cover. The observed differences in surface properties are a result of long-term, severe overgrazing of the Mexican lands. Recently, investigators have shown the Mexican side of the border to have higher surface and air temperatures when compared to adjacent areas in the United State. The differences in temperatures appear to be more associated with differential evapotranspiration rates than with albedo changes along the border. In this study, the impact of summer rainfall on the observed seasonal and daily gradient in maximum temperature is examined. On a seasonal time scale, the temperature gradient increases with higher moisture levels, probably due to a vegetative response on the United States' side of the border; at the daily level, the gradient in maximum temperature decreases after a rain event as evaporation rates equalize between the countries. The results suggest that temperature differences between vegetated and overgrazed landscapes in arid areas are highly dependent upon the amount of moisture available for evapotranspiration.

Balling, Robert C., Jr.↗
NASA NTRS1990

WINCOF-I code for prediction of fan compressor unit with water ingestion

The PURDUE-WINCOF code, which provides a numerical method of obtaining the performance of a fan-compressor unit of a jet engine with water ingestion into the inlet, was modified to take into account: (1) the scoop factor, (2) the time required for the setting-in of a quasi-steady distribution of water, and (3) the heat and mass transfer processes over the time calculated under 2. The modified code, named WINCOF-I was utilized to obtain the performance of a fan-compressor unit of a generic jet engine. The results illustrate the manner in which quasi-equilibrium conditions become established in the machine and the redistribution of ingested water in various stages in the form of a film out of the casing wall, droplets across the span, and vapor due to mass transfer.

Murthy, S. N. B.↗
NASA NTRS1990

Evaluation of EDR-3 vibration, shock, temperature, and humidity recording unit

The purpose of this evaluation was to determine if the self-contained, off-the-shelf, Environmental Data Recorder 3 (EDR-3) could be qualified to monitor shock, vibration, and temperature during rail transportation of space shuttle solid rocket components. The evaluation testing started in November 1989 and continued until June 1990. Two EDR-3 units were used to monitor both on- and off-plant shipments of shuttle components. In addition, extensive testing was performed at Thiokol's Vibration Test facility, T-53. Testing demonstrated that the EDR-3 is capable of successfully monitoring actual shipments of solid rocket hardware. Thiokol metrology has verified the accuracy of temperature monitoring. In addition, calibrated shock/vibration testing demonstrated that the EDR-3 does accurately record acceleration. It is recommended that the vendor modify the EDR-3 data recovery system to allow remote communication via a 30-foot cable. This would permit communication with the unit mounted on a case segment after a rail car cover is installed. The vendor will make this change and produce a new model, designated EDR-3-10. It is further recommended that Thiokol qualify the EDR-3-10 for transportation monitoring of redesigned solid rocket motor (RSRM) components.

Rees, Kevin G.↗
NASA NTRS1989

A fuel cell energy storage system concept for the Space Station Freedom Extravehicular Mobility Unit

An update is given on work to design and build a Fuel Cell Energy Storage System (FCESS) bench-tested unit for the Space Station Freedom Extravehicular Mobility Unit (EMU). Fueled by oxygen and hydride-stored hydrogen, the FCESS is being considered as an alternative to the EMU zinc-silver oxide battery. Superior cycle life and quick recharge are the main attributes of FCESS. The design and performance of a nonventing, 28 V, 34 Ahr system with 7 amp rating are discussed.

Adlhart, Otto J.↗
NASA NTRS1989

A helmet mounted display demonstration unit for a Space Station application

Under NASA guidance an advanced development helmet mounted display (HMD) has been designed and fabricated. Delivery has been made of an extravehicular mobility unit (EMU) HMD demonstration unit as an alternative to the current low-resolution, chest-mounted display, and cuff-mounted checklists. Important design goals achieved with this HMD include the use of transmissive liquid display image sources with fairly high resolution (text, graphics, and video compatible), binocular viewing with total image overlap, virtual image projection, low profile packaging, low power design, and demonstration of voice control of the HMD data. Test results showed that the HMD program successfully demonstrated the feasibility of the concept and operated as designed, meeting the necessary program requirements.

Gernux, Carolyn G.↗
NASA NTRS1990

Flight test results of failure detection and isolation algorithms for a redundant strapdown inertial measurement unit

Flight test results for two sensor fault-tolerant algorithms developed for a redundant strapdown inertial measurement unit are presented. The inertial measurement unit (IMU) consists of four two-degrees-of-freedom gyros and accelerometers mounted on the faces of a semi-octahedron. Fault tolerance is provided by edge vector test and generalized likelihood test algorithms, each of which can provide dual fail-operational capability for the IMU. To detect the wide range of failure magnitudes in inertial sensors, which provide flight crucial information for flight control and navigation, failure detection and isolation are developed in terms of a multi level structure. Threshold compensation techniques, developed to enhance the sensitivity of the failure detection process to navigation level failures, are presented. Four flight tests were conducted in a commercial transport-type environment to compare and determine the performance of the failure detection and isolation methods. Dual flight processors enabled concurrent tests for the algorithms. Failure signals such as hard-over, null, or bias shift, were added to the sensor outputs as simple or multiple failures during the flights. Both algorithms provided timely detection and isolation of flight control level failures. The generalized likelihood test algorithm provided more timely detection of low-level sensor failures, but it produced one false isolation. Both algorithms demonstrated the capability to provide dual fail-operational performance for the skewed array of inertial sensors.

Morrell, F. R.↗
NASA NTRS1990

Liquid hydrogen production and commercial demand in the United States

Kennedy Space Center, the single largest purchaser of liquid hydrogen (LH2) in the United States, evaluated current and anticipated hydrogen production and consumption in the government and commercial sectors. Specific objectives of the study are as follows: (1) identify LH2 producers in the United States and Canada during 1980-1989 period; (2) compile information in expected changes in LH2 production capabilities over the 1990-2000 period; (3) describe how hydrogen is used in each consuming industry and estimate U.S. LH2 consumption for the chemicals, metals, electronics, fats and oil, and glass industries, and report data on a regional basis; (4) estimate historical and future consumption; and (5) assess the influence of international demands on U.S. plants.

Heydorn, Barbara↗
NASA NTRS1990

Assemblages of geologic/morphologic units in the northern hemisphere of Venus

Several basic assemblages of geologic/morphologic units are defined, and their characteristics, spatial distribution, and correlation with topography and other surface properties are documented. The relationships of these assemblages are analyzed, and their possible origins discussed. It is concluded that the geologic/morphologic map units derived from Venera 15/16 data at the northern mid-to-high latitudes do not occur randomly and can be grouped into several basic assemblages. The distribution and characteristics of assemblages demonstrate that vertical and horizontal tectonic forces are operating on the crust and lithosphere of Venus in different ways in specific localized areas. Alternative models are outlined for the origin of each assemblage and the relationship between assemblages, and important unresolved questions are identified.

Head, James W.↗
NASA NTRS1991

The minimal flow unit in near-wall turbulence

Direct numerical simulations of unsteady channel flow were performed at low to moderate Reynolds numbers on computational boxes chosen small enough so that the flow consists of a doubly periodic (in x and z) array of identical structures. The goal is to isolate the basic flow unit, to study its morphology and dynamics, and to evaluate its contribution to turbulence in fully developed channels. For boxes wider than approximately 100 wall units in the spanwise direction, the flow is turbulent, and the low-order turbulence statistics are in good agreement with experiments in the near-wall region. For a narrow range of widths below that threshold, the flow near only one wall remains turbulent, but its statistics are still in fairly good agreement with experimental data when scaled with the local wall stress. For narrower boxes only laminar solutions are found. In all cases, the elementary box contains a single low-velocity streak, consisting of a longitudinal strip on which a thin layer of spanwise vorticity is lifted away from the wall.

Jimeez, Javier↗
NASA NTRS1992

Portable Power And Digital-Communication Units

Conceptual network of electronic-equipment modules provides electrical power and digital radio communications at multiple sites not served by cables. System includes central communication unit and portable units powered by solar photovoltaic arrays. Useful to serve equipment that must be set up quickly at remote sites or buildings that cannot be modified to provide cable connections.

Levin, Richard R.↗
NASA NTRS1992

Hand-Switch Unit For Use With Protective Suit

Unit containing two hand-operated switches water-tight and designed for use with protective suit. One switch is toggle switch used to select communication by wire or radio. Other switch is press-to-talk button. User grasps and operates switches without looking at them. Fences on top of new unit protects toggle switch from inadvertent operation and spaced to accommodate gloved thumb. Push-to-talk button protected by longitudinal bar, springy and compressed inward to actuate button.

Chalson, Howard E.↗
NASA NTRS1991

Quantitative analysis of terrain units mapped in the northern quarter of Venus from Venera 15/16 data

The contacts between 34 geological/geomorphic terrain units in the northern quarter of Venus mapped from Venera 15/16 data were digitized and converted to a Sinusoidal Equal-Area projection. The result was then registered with a merged Pioneer Venus/Venera 15/16 altimetric database, root mean square (rms) slope values, and radar reflectivity values derived from Pioneer Venus. The resulting information includes comparisons among individual terrain units and terrain groups to which they are assigned in regard to percentage of map area covered, elevation, rms slopes, distribution of suspected craters greater than 10 km in diameter.

Schaber, G. G.↗