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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 1,279 records · Page 71
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Fully automated urban traffic system

The replacement of the driver with an automatic system which could perform the functions of guiding and routing a vehicle with a human's capability of responding to changing traffic demands was discussed. The problem was divided into four technological areas; guidance, routing, computing, and communications. It was determined that the latter three areas being developed independent of any need for fully automated urban traffic. A guidance system that would meet system requirements was not being developed but was technically feasible.

Dobrotin, B. M.↗
NASA NTRS1978

Prospects for a civil/military transport aircraft

The similarities and disparities between commercial and military payloads, design features, missions, and transport aircraft are enumerated. Two matrices of civil/military transport aircraft designs were evaluated to determine the most cost effective payloads for a projected commercial route structure and air freight market. The probability of this market developing and the prospects for alternate route structures and freight markets are evaluated along with the possible impact on the aircraft designs. Proposals to stimulate the market and increase the viability of the common aircraft concept are reviewed and the possible impact of higher cargo demand on prospects for common civil/military freighters is postulated. The implications of planned advanced technology developments on the aircraft performance and cost are also considered.

Jobe, C. E.↗
NASA NTRS1979

Mission summary: Halley flyby/Tempel-2 rendezvous

A unique dual-comet flight opportunity exists in mid-1985 which includes flyby of the large and active comet Halley en route to rendezvous with second comet, Tempel-2. This mission will utilize ion propulsion at a modest performance level, based on proven technology. The Project is planned for FY81 start. Launch occurs in July 1985 via the Shuttle/IUS twin stage. Following IUS injection, the ion propulsion stage provides continuous thrust virtually throughout the 3-year flight until the Tempel-2 rendezvous in 1988. En route, a probe is deployed for encounter with Halley about 4 months after launch at a point 73 days before its perihelion. Rendezvous with Tempel-2 occurs about 60 days before the comet's perihelion during the summer of 1988 and continues for about 1 year. Earth will be in favorable relative positions for observing both the flyby and the rendezvous.

Atkins, K.↗
NASA NTRS1979

Space Shuttle communications RF switch matrix

The Shuttle Orbiter communications equipment includes phase modulation (PM) and frequency modulation (FM) channels. The PM section has the capability of routing high levels of energy (175 W) from any one of four transmitters to any one of four antennas, mutually exclusive. The FM channel uses a maximum of 15-W power routed from either of two transmitters to one of two antennas, mutually exclusive. The paper describes the design and the theory of a logic-controlled RF switch matrix devised for the purposes cited. Both PM and FM channels are computer-controlled with manual overrides. The logic interface is realized with CMOS logic for low power consumption and high noise immunity. The interior of the switch matrix is maintained at a pressure of 15 psi (90% nitrogen, 10% helium) by an electron beam-welded encapsulation. The computational results confirm the viability of the RF switch matrix concept.

Winch, R.↗
NASA NTRS1981

CADAT network translator

Program converts cell-net data into logic-gate models for use in test and simulation programs. Input consists of either Place, Route, and Fold (PRF) or Place-and-Route-in-Two-Dimensions (PR2D) layout data deck. Output consists of either Test Pattern Generator (TPG) or Logic-Simulation (LOGSIM) logic circuitry data deck. Designer needs to build only logic-gate-model circuit description since program acts as translator. Language is FORTRAN IV.

Pitts, E. R.↗
NASA NTRS1980

Multigigabit satellite on-board signal processing

The satellite communication system described provides communications for very small and very large (trunking) users. Independent combinations of FDMA and TDMA are used in the uplink and downlink designs to minimize terminal costs. Signal routing for small users is accomplished by a digital store-and-forward technique which greatly simplifies the terminal receiver, compared to satellite-switched TDMA. Different processing techniques are used for very high data rate users, but complete interconnectivity between all users is maintained. This avoids double-hop routing with excessive transmission delays.

Holmes, W. M., Jr.↗
NASA NTRS1980

The future of short-haul transport aircraft

Owing to recent economic and regulatory changes and escalating fuel costs, major airlines have begun to shift their short-haul service to longer, more profitable routes, leaving short-haul operations to rapidly growing commuter airlines. The short-haul routes are currently serviced by small turboprop-powered aircraft. The results of some recent design studies aimed at replacing the turboprops with specialized propeller- and rotor-driven aircraft are discussed. Some potential future designs are illustrated and discussed.

Williams, L. J.↗
NASA NTRS1980

Vehicle testing of Cummins turbocompound diesel engine

Two turbocompound diesel engines were installed in Class VIII heavy-duty vehicles to determine the fuel consumption potential and performance characteristics. One turbocompound powered vehicle was evaluated at the Cummins Pilot Center where driveability, fuel consumption, torsional vibration, and noise were evaluated. Fuel consumption testing showed a 14.8% benefit for the turbocompound engine in comparison to a production NTC-400 used as a baseline. The turbocompound engine also achieved lower noise levels, improved driveability, improved gradeability, and marginally superior engine retardation. The second turbocompound engine was placed in commercial service and accumulated 50,000 miles on a cross-country route without malfunction. Tank mileage revealed a 15.92% improvement over a production NTCC-400 which was operating on the same route.

Brands, M. C.↗
NASA NTRS1980

Concorde with the airlines

The only supersonic aircraft in airline service, Concorde, offers the first actual test of supersonic cruise feasibility and the only real experience relative to passenger, airline, and community acceptance. The dominant characteristic of Concorde operations is low aircraft utilization, due partly to the restricted route network. Operating costs, the maintenance/reliability record and associated dispatch delays are discussed. Problems with overwater operations, and the secondary boom phenomena are examined. Monthly average load factors for various routes, major causes of technical delays, aircraft technical performance, and aircraft tracks are graphically depicted.

Leyman, C. S.↗
NASA NTRS1980

Long-range airplane study: The consumer looks at SST travel

The attitudes of long-range air travelers toward several basic air travel decisions, were surveyed. Of interest were tradeoffs involving time versus comfort and time versus cost as they pertain to supersonic versus conventional wide-body aircraft on overseas routes. The market focused upon was the segment of air travelers most likely to make that type of tradeoff decision: those having flown overseas routes for business or personal reasons in the recent past. The information generated is intended to provide quantifiable insight into consumer demand for supersonic as compared to wide-body aircraft alternatives for long-range overseas air travel.

Landes, K. H.↗
NASA NTRS1981

Real time software tools and methodologies

Real time systems are characterized by high speed processing and throughput as well as asynchronous event processing requirements. These requirements give rise to particular implementations of parallel or pipeline multitasking structures, of intertask or interprocess communications mechanisms, and finally of message (buffer) routing or switching mechanisms. These mechanisms or structures, along with the data structue, describe the essential character of the system. These common structural elements and mechanisms are identified, their implementation in the form of routines, tasks or macros - in other words, tools are formalized. The tools developed support or make available the following: reentrant task creation, generalized message routing techniques, generalized task structures/task families, standardized intertask communications mechanisms, and pipeline and parallel processing architectures in a multitasking environment. Tools development raise some interesting prospects in the areas of software instrumentation and software portability. These issues are discussed following the description of the tools themselves.

Christofferson, M. J.↗
NASA NTRS1982

Real-time simulation of helicopter IFR approaches into major terminal areas using RNAV, MLS, and CDTI

Helicopter IFR routes at hub airports have been investigated in an air-traffic-control system simulation involving a piloted helicopter simulator, computer-generated air traffic, and air traffic controllers. Problems studied included: (1) pilot acceptance of the approach procedure and tracking accuracy; (2) ATC procedures for handling a mix of helicopter and fixed-wing traffic; and (3) utility of the Cockpit Display of Traffic Information (CDTI) for the helicopter. Results indicate that the helicopter routes were pilot acceptable and were noninterfering with fixed-wing traffic. Merging and spacing maneuvers using CDTI were successfully carried out by the pilots, but controllers had some reservations concerning CDTI.

Tobias, L.↗
NASA NTRS1982

Gates to Gregg High Voltage Transmission Line Study

The usefulness of LANDSAT data in the planning of transmission line routes was assessed. LANDSAT digital data and image processing techniques, specifically a multi-date supervised classification aproach, were used to develop a land cover map for an agricultural area near Fresno, California. Twenty-six land cover classes were identified, of which twenty classes were agricultural crops. High classification accuracies (greater than 80%) were attained for several classes, including cotton, grain, and vineyards. The primary products generated were 1:24,000, 1:100,000 and 1:250,000 scale maps of the classification and acreage summaries for all land cover classes within four alternate transmission line routes.

Bergis, V.↗
NASA NTRS1983

Cloud encounter statistics in the 28.5-43.5 KFT altitude region from four years of GASP observations

The results of an analysis of cloud encounter measurements taken at aircraft flight altitudes as part of the Global Atmospheric Sampling Program are summarized. The results can be used in estimating the probability of cloud encounter and in assessing the economic feasibility of laminar flow control aircraft along particular routes. The data presented clearly show the tropical circulation and its seasonal migration; characteristics of the mid-latitude regime, such as the large-scale traveling cyclones in the winter and increased convective activity in the summer, can be isolated in the data. The cloud encounter statistics are shown to be consistent with the mid-latitude cyclone model. A model for TIC (time-in-clouds), a cloud encounter statistic, is presented for several common airline routes.

Jasperson, W. H.↗
NASA NTRS1982

Implication of a color multibeam communications satellite in the 30/20 GHz bands

In order to meet the need for increased communications capacity, NASA is conducting a program to develop technology and systems for a 30/20 GHz multibeam domestic U.S. satellite. One way to provide the required national interconnectivity is to permute and time share connections among the involved areas by means of a satellite-borne multiport microwave switch with a Time-Division Multiple Access (TDMA) system. In this connection, the question was analyzed whether a practical satellite message routing system can be developed using FDMA techniques. The total traffic (model A) was derived and used as an input specification for the satellite-routed FDMA study. Attention is given to beam isolations, color and regional systems, the level of service, and the color FDMA satellite. It is concluded that the FDMA system considered can handle substantially all the Customer Premises Service (CPS) and Trunking (TR) traffic in Model A. The (color) scheme completely satisfies the CPS and TR requirements of 23 cities.

Hoffman, M.↗
NASA NTRS1983

Communications network design and costing model technical manual

This computer model provides the capability for analyzing long-haul trunking networks comprising a set of user-defined cities, traffic conditions, and tariff rates. Networks may consist of all terrestrial connectivity, all satellite connectivity, or a combination of terrestrial and satellite connectivity. Network solutions provide the least-cost routes between all cities, the least-cost network routing configuration, and terrestrial and satellite service cost totals. The CNDC model allows analyses involving three specific FCC-approved tariffs, which are uniquely structured and representative of most existing service connectivity and pricing philosophies. User-defined tariffs that can be variations of these three tariffs are accepted as input to the model and allow considerable flexibility in network problem specification. The resulting model extends the domain of network analysis from traditional fixed link cost (distance-sensitive) problems to more complex problems involving combinations of distance and traffic-sensitive tariffs.

Logan, K. P.↗
NASA NTRS1984

Development of the L-1011 four-dimensional flight management system

The development of 4-D guidance and control algorithms for the L-1011 Flight Management System is described. Four-D Flight Management is a concept by which an aircraft's flight is optimized along the 3-D path within the constraints of today's ATC environment, while its arrival time is controlled to fit into the air traffic flow without incurring or causing delays. The methods developed herein were designed to be compatible with the time-based en route metering techniques that were recently developed by the Dallas/Fort Worth and Denver Air Route Traffic Control Centers. The ensuing development of the 4-D guidance algorithms, the necessary control laws and the operational procedures are discussed. Results of computer simulation evaluation of the guidance algorithms and control laws are presented, along with a description of the software development procedures utilized.

Lee, H. P.↗
NASA NTRS1983

Shock tube study of the fuel structure effects on the chemical kinetic mechanisms responsible for soot formation

Soot formation in toluene-, benzene-, and acetylene-oxygen-argon mixtures was investigated to study soot formation in a combustion environment. High concentrations of oxygen completely suppress soot formation. The addition of oxygen at relatively low concentrations uniformly suppresses soot formation at high pressures, while at relatively lower pressures it suppresses soot formation at higher temperatures while promoting soot production at lower temperatures. The observed behavior indicates that oxidation reactions compete with ring fragmentation. The main conclusion to be drawn from the results is that the soot formation mechanism is probably the same for the pyrolysis and oxidation of hydrocarbons. That is, the addition of oxygen does not alter the soot route but rather promotes or inhibits this route by means of competitive reactions. An approach to empirical modeling of soot formation during pyrolysis of aromatic hydrocarbons is also presented.

Frenklach, M.↗