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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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NASA NTRS1982

Spatially Characterizing Effective Timber Supply

The structure of a computer-oriented cartographic model for assessing roundwood supply for generation of base load electricity is discussed. The model provides an analytical procedure for coupling spatial information of harvesting economics and owner willingness to sell stumpages. Supply is characterized in terms of standing timber; of accessibility considering various harvesting and hauling factors; and of availability as affected by ownership and residential patterns. Factors governing accessibility to timber include effective harvesting distance to haulic roads as modified by barriers and slopes. Haul distance is expressed in units that take into account the relative ease of travel along various road types to a central processing facility. Areas of accessible timber are grouped into spatial units, termed 'timbersheds', of common access to particular haul road segments that belong to unique 'transport zones'. Timber availability considerations include size of ownership parcels, housing density and excluded areas. The analysis techniques are demonstrated for a cartographic data base in western Massachusetts.

Berry, J. K.↗

NASA NTRS1988

Propagation effects by roadside trees measured at UHF and L-band for mobile satellite systems

Propagation field tests were performed in Central Maryland and involved a helicopter and mobile van as the source and receiving platforms, respectively. Tests were implemented at both UHF (870 MHz) and L-band (1.5 GHz) during a period in which the trees were in full blossom and contained maximum moisture. Cumulative fade distributions were determined from the data for various fixed elevation angles, side of the road driving, and road types for both worst and best case path geometries and for overall average road conditions.

Goldhirsh, Julius↗

NASA NTRS1990

Mobile satellite system propagation measurements at L-band using Marecs-B2

A mobile satellite system (MSS) propagation experiment at 1.5 GHz was performed near the east coast of the United States in central Maryland during December 1987 using the Marecs-B2 satellite as a transmitter platform. A receiving system in a vehicle measured signal fades caused by shadowing and multipath from roadside trees and utility poles. The propagation degradations were characterized for a system of three roads previously examined using a helicopter as the transmitter platform. The objectives of the Marecs-B2 MSS tests were to: (1) establish cumulative fade distributions for the particular satellite geometry for both rural and suburban roads; (2) validate the consistency of previous roadside tree measurements which employed a helicopter as the transmitter platform for the same system of roads; (3) obtain an additional set of fade levels at a lower angle hitherto not measured in central Maryland; and (4) combine the satellite-acquired data set with previous helicopter results and establish an analytic, empirically derived function describing the cumulative fade distributions for a family of path angles. An analysis of the satellite data has demonstrated the successful achievement of these objectives.

Vogel, Wolfhard J.↗

NASA NTRS1991

Toward autonomous driving: The CMU Navlab. I - Perception

The Navlab project, which seeks to build an autonomous robot that can operate in a realistic environment with bad weather, bad lighting, and bad or changing roads, is discussed. The perception techniques developed for the Navlab include road-following techniques using color classification and neural nets. These are discussed with reference to three road-following systems, SCARF, YARF, and ALVINN. Three-dimensional perception using three types of terrain representation (obstacle maps, terrain feature maps, and high-resolution maps) is examined. It is noted that perception continues to be an obstacle in developing autonomous vehicles.

Thorpe, Charles↗

NASA NTRS1961

An Investigation of the Effects of the Time Lag Due to Long Transmission Distances upon Remote Control: Tracking Experiments - Phase 1

A series of pursuit tracking tasks were performed incorporating a transport lag in the control loop. The target was a mixture of four sine waves, the fastest having a frequency of 16 cycles per minute at full speed. An attempt was made to design the experiments so that they would provide data applicable to remote control of a ground vehicle over long transmission distances. Three programs were run. In each the time lag was placed between the control and the display. In the first program a velocity control was used and the operator was told that his knob controlled a vehicle, the problem represented a road 9 and he was to drive his vehicle along the road 9 using the delayed vehicle position as feedback for whatever means he desired. The objective was not to match the display traces. In the second program a velocity control was used, and the operator was told that the problem trace represented a road and the delayed trace represented a vehicle and he was to keep them together. The objective was to match display traces. The third program was identical with the first, except that an acceleration control was used rather than a velocity control. Target speeds used were full speed, 1/2 speed, 1/4 speed, 1/8 speed, and 1/16 speed. Time lags were 1/4 second, l/2 second, 1 second, 1-1/2 second, 2 second, 3 second, and 6 seconds. The experimental results are presented in the last section of this report.

Adams, James L.↗

NASA NTRS2000

New Strategy for Exploration Technology Development: The Human Exploration and Development of Space (HEDS) Exploration/Commercialization Technology Initiative

In FY 2001, NASA will undertake a new research and technology program supporting the goals of human exploration: the Human Exploration and Development of Space (HEDS) Exploration/Commercialization Technology Initiative (HTCI). The HTCI represents a new strategic approach to exploration technology, in which an emphasis will be placed on identifying and developing technologies for systems and infrastructures that may be common among exploration and commercial development of space objectives. A family of preliminary strategic research and technology (R&T) road maps have been formulated that address "technology for human exploration and development of space (THREADS). These road maps frame and bound the likely content of the HTCL Notional technology themes for the initiative include: (1) space resources development, (2) space utilities and power, (3) habitation and bioastronautics, (4) space assembly, inspection and maintenance, (5) exploration and expeditions, and (6) space transportation. This paper will summarize the results of the THREADS road mapping process and describe the current status and content of the HTCI within that framework. The paper will highlight the space resources development theme within the Initiative and will summarize plans for the coming year.

Mankins, John C.↗

NASA NTRS2005

Urban forms, physical activity and body mass index: a cross-city examination using ISS Earth Observation photographs

Johnson Space Center has archived thousands of astronauts acquired Earth images. Some spectacular images have been widely used in news media and in k-12 class room, but their potential utilizations in health promotion and disease prevention have relatively untapped. The project uses daytime ISS photographs to define city forms and links them to city or metropolitan level health data in a multicity context. Road connectivity, landuse mix and Shannon's information indices were used in the classification of photographs. In contrast to previous remote-sensing studies, which tend to focus on a single city or a portion of a city, this project utilized photographs of 39 U.S. cities. And in contrast to previous health-promotion studies on the built environment, which tend to rely on survey respondents' responses to evaluate road connectivity or mixed land use for a single study site, the project examined the built environments of multiple cities based on ISS photos. It was found that road connectivity and landuse mix were not statistically significant by themselves, but the composite measure of the Shannon index was significantly associated with physical activity, but not BMI. Consequently, leisure-time physical activity seems to be positively associated with the urban complexity scale. It was also concluded that unless they are planned or designed in advance, photographs taken by astronauts generally are not appropriate for a study of a single-site built environment nor are they appropriate for a study of infectious diseases at a local scale. To link urban built environment with city-wide health indicators, both the traditional nadir view and oblique views should be emphasized in future astronauts' earth observation photographs.

Lin, Ge↗

NASA NTRS1977

Skid Resistance Research

Skidding causes many traffic accidents. Streets and highways with skid-resisting surfaces reduce the incidence of such accidents. In fact, resurfacing roads to improve skid resistance is now required by federal law. Skid resistance is measured by road testing with specially equipped skid trailers. A project underway at NASA-Langley may considerably reduce the cost of skid trailers, thus making them more widely available to highway departments. For testing the skid resistance of aircraft runways, Langley engineers developed a relatively inexpensive test vehicle and a "pulsed braking" technique that is now being applied experimentally to road testing. The vehicle is a standard automobile modified to incorporate instrumentation, special test tires and valves, and a trailing fifth wheel for monitoring distance and velocity. The instrumentation includes a low-cost meter, a set of accelerometers that sense motion changes, and a chart recorder.

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NASA NTRS2012

Roles of Urban Tree Canopy and Buildings in Urban Heat Island Effects: Parameterization and Preliminary Results

Urban heat island (UHI) effects can strengthen heat waves and air pollution episodes. In this study, the dampening impact of urban trees on the UHI during an extreme heat wave in the Washington, D.C., and Baltimore, Maryland, metropolitan area is examined by incorporating trees, soil, and grass into the coupled Weather Research and Forecasting model and an urban canopy model (WRF-UCM). By parameterizing the effects of these natural surfaces alongside roadways and buildings, the modified WRF-UCM is used to investigate how urban trees, soil, and grass dampen the UHI. The modified model was run with 50% tree cover over urban roads and a 10% decrease in the width of urban streets to make space for soil and grass alongside the roads and buildings. Results show that, averaged over all urban areas, the added vegetation decreases surface air temperature in urban street canyons by 4.1 K and road-surface and building-wall temperatures by 15.4 and 8.9 K, respectively, as a result of tree shading and evapotranspiration. These temperature changes propagate downwind and alter the temperature gradient associated with the Chesapeake Bay breeze and, therefore, alter the strength of the bay breeze. The impact of building height on the UHI shows that decreasing commercial building heights by 8 m and residential building heights by 2.5 m results in up to 0.4-K higher daytime surface and near-surface air temperatures because of less building shading and up to 1.2-K lower nighttime temperatures because of less longwave radiative trapping in urban street canyons.

urban vegetation↗

NASA NTRS2005

A Global Rapid Integrated Monitoring System for Water Cycle and Water Resource Assessment (Global-RIMS)

The main focus of our work was to solidify underlying data sets, the data processing tools and the modeling environment needed to perform a series of long-term global and regional hydrological simulations leading eventually to routine hydrometeorological predictions. A water and energy budget synthesis was developed for the Mississippi River Basin (Roads et al. 2003), in order to understand better what kinds of errors exist in current hydrometeorological data sets. This study is now being extended globally with a larger number of observations and model based data sets under the new NASA NEWS program. A global comparison of a number of precipitation data sets was subsequently carried out (Fekete et al. 2004) in which it was further shown that reanalysis precipitation has substantial problems, which subsequently led us to the development of a precipitation assimilation effort (Nunes and Roads 2005). We believe that with current levels of model skill in predicting precipitation that precipitation assimilation is necessary to get the appropriate land surface forcing.

Roads, John↗

NASA NTRS1972

Exploratory evaluation of ceramics for automobile thermal reactors

An exploratory evaluation of ceramics for automobile thermal reactors was conducted. Potential ceramic materials were evaluated in several reactor designs using both engine dynamometer and vehicle road tests. Silicon carbide contained in a corrugated metal support structure exhibited the best performance lasting over 800 hours in engine dynamometer tests and over 15,000 miles (24,200 km) of vehicle road tests. Reactors containing glass-ceramic components did not perform as well as silicon carbide. But the glass-ceramics still offer good potential for reactor use. The results of this study are considered to be a reasonable demonstration of the potential use of ceramics in thermal reactors.

Stone, P. L.↗

NASA NTRS1972

Automatic identification of land uses from ERTS-1 data obtained over Milwaukee, Wisconsin

The author has identified the following significant results. Spectrally, thirteen classes of ground cover were identified within Milwaukee County: five classes of water, grassy open areas, beach, two classes of road, woods, suburban, inner city, and industry. A distinct concentric pattern of land use was identified in the county radiating outward from the central business district. The first ring has a principal feature, termed the inner city, which is indicative of the older part of the county. In the second ring, the land use becomes more complex, consisting of suburban areas, parks, and varied institutional features. The third general ring consists primarily of open, grassy land, with scattered residential subdivisions, wood lots, and small water bodies. The five classes of water identified suggest differences in depth, turbidity, and/or color. A number of major roads were identified. Other spectrally identifiable features included the larger county parks and larger cemeteries.

Baumgardner, M. F.↗

NASA NTRS1972

Smoke Plume Analysis Using Fan-beam and Single-beam Radiometers

Smoke plume data were taken using the stacks of the Mills Road Steam Plant on Redstone Arsenal, Huntsville, Alabama. The fan-beam unit was placed approximately 235 meters east of the Mills Road Steam Plant, and the single-beam unit was placed approximately 80 meters north of the fan-beam unit. Results of the smoke plume measurements indicate that the smoke plume is a periodic process near the mouth of the smokestack. The usefulness of the system is limited because of inaccurate and cumbersome positioning methods and base line constraints due to cable length. It is recommended that the radiometers be mounted on pedestals which have both azimuth and elevation positions determined by digitally controlled stepper drive motors. It is also recommended that a time multiplex system be used to transmit data from the radiometers to the electronics van.

Dodd, J. L.↗

NASA NTRS1973

Preliminary measurements on heat balance in pneumatic tires

A variety of tests was undertaken to determine the nature of heat generation associated with a pneumatic tire operating under various conditions. Tests were conducted to determine the magnitude and distribution of internally generated heat caused by hysteresis in the rubber and ply fabric in an automobile tire operating under conditions of load, pressure, and velocity representative of normal operating conditions. These included tests at various yaw angles and tests with braking applied. In other tests, temperature sensors were mounted on a road to measure the effect of a tire rolling over and an attempt was made to deduce the magnitude and nature of interfacial friction from the resulting information. In addition, tests were performed using the scratch plate technique to determine the nature of the motion between the tire and road. Finally, a model tire was tested on a roadwheel, the surface covering which could be changed, and an optical pyrometer was used to measure rubber surface temperatures.

Nybakken, G. H.↗

NASA NTRS1973

Proceedings of Symposium on Utilization of Waste Glass in Secondary Products

Papers are reported which were presented at the conference on waste glass recovery and re-use in secondary products. The uses considered include: road surfacing, asphaltic concretes, road construction, terrazzo, cement concrete, pozzolan, glass wool, glass-polymer composites, and tiles. Problems of recycling glass in remote areas, and the economics and markets for secondary glass products are discussed.

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NASA NTRS1974

The utilization of ERTS-1-generated photographs in the evaluation of the Iranian playas as potential locations for economic and engineering development

The author has identified the following significant results. Seasonal monitoring of hydrologic conditions at three playa lakes provides a basis for constructing an annual water inventory for these lakes. Although the extreme variation in the extent of playa lakes must be considered, the principal periods of their fluctuations are generally constant. Playa lakes provide an important water source for arid region needs, and their water can be diverted and stored for use during the long, hot, and dry summer. At their 1973 maxima, approximately 400 million cu m and 794 million cu m of water were available at the lakes at Qom and Neriz playas, respectively. These lakes adjoin areas of moderately dense population that have severe annual water deficits. A preliminary road alignment across the Great Kavir in north-central Iran has been prepared from an analysis of ERTS-1 images of that area from September 2, 1972, through May 12, 1973, a total of 6 scenes. An all-weather road constructed along this alignment could reduce the distance between points north and south of the Great Kavir by as much as 700 km.

Krinsley, D. B.↗

NASA NTRS1974

To assess the value of satellite photographs in resource evaluation on a national scale

The author has identified the following significant results. The limit of resolution on ERTS imagery is normally acknowledged to be about 60 miles although very long features such as roads and railways which are often less than 10 miles long are easily detectable. An example is the north-south road and railway from Lobatse to Francistown. Vegetation growth from winter to summer is readily monitored on false color imagery. The limits of government ranches and special farming areas can be quite accurately ascertained from ERTS imagery. Another aspect to which ERTS imagery lends itself is the location and demarcation of bush fires, many of which were seen on the first imagery which was acquired at the end of the cold, dry season. As a whole, MSS 7 offers maximum reflectance contrast among black and white imagery and is the wavelength used most for interpretation.

Hepworth, J. V.↗

NASA NTRS1974

Design and evaluation of experimental ceramic automobile thermal reactors

The results obtained in an exploratory evaluation of ceramics for automobile thermal reactors are summarized. Candidate ceramic materials were evaluated in several reactor designs by using both engine-dynamometer and vehicle road tests. Silicon carbide contained in a corrugated-metal support structure exhibited the best performance, lasting 1100 hr in engine-dynamometer tests and more than 38,600 km (24000 miles) in vehicle road tests. Although reactors containing glass-ceramic components did not perform as well as those containing silicon carbide, the glass-ceramics still offer good potential for reactor use with improved reactor designs.

Stone, P. L.↗