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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 721 records · Page 40

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NASA NTRS1974

Fire-resistant aircraft materials development and evaluation program

The overall objectives of this program are to provide a more fire-resistant commercial aircraft interior and to improve the fuselage insulation barrier between the cabin interior and an exterior fuel fire. Significant secondary objectives are to reduce the smoke and toxic gas production of the materials and to meet the end item use requirements pertaining to wearability, color fastness, and aesthetic appeal. It is shown that the fuselage insulation materials must meet stringent requirements pertaining to acoustic attenuation, low density, and water repellency.

Bricker, R. W.↗

NASA NTRS1975

Conservation: Toward firmer ground

The following aspects of energy conservation were discussed: conservation history and goals, conservation modes, conservation accounting-criteria, and a method to overcome obstacles. The conservation modes tested fall into one of the following categories: reduced energy consumption, increased efficiency of energy utilization, or substitution of one or more forms of energy for another which is in shorter supply or in some sense thought to be of more value. The conservation accounting criteria include net energy reduction, economic, and technical criteria. A method to overcome obstacles includes (approaches such as: direct personal impact (life style, income, security, aspiration), an element of crisis, large scale involvement of environmental, safety, and health issues, connections to big government, big business, big politics, involvement of known and speculative science and technology, appeal to moral and ethical standards, the transient nature of opportunities to correct the system.

Source record↗

NASA NTRS1976

Design, fabrication, testing and delivery of a solar collector

A two phase program encompassing the redesign and fabrication of a solar collector which is low in cost and aesthetically appealing is described. Phase one work reviewed the current collector design and developed a low-cost design based on specific design/performance/cost requirements. Throughout this phase selected collector component materials were evaluated by testing and by considering cost, installation, maintainability and durability. The resultant collector design was composed of an absorber plate, insulation, frame, cover, desiccant and sealant. In Phase two, three collector prototypes were fabricated and evaluated for both nonthermal and thermal characteristics. Tests included static load tests of covers, burst pressure tests of absorber plates, and tests for optical characteristics of selective absorber plate coatings. The three prototype collectors were shipped to Marshall Space Flight Center for use in their solar heating and cooling test facility.

Sims, W. H.↗

NASA NTRS1977

Modeling and Analysis of Power Processing Systems (MAPPS), initial phase 2

The overall objective of the program is to provide the engineering tools to reduce the analysis, design, and development effort, and thus the cost, in achieving the required performances for switching regulators and dc-dc converter systems. The program was both tutorial and application oriented. Various analytical methods were described in detail and supplemented with examples, and those with standardization appeals were reduced into computer-based subprograms. Major program efforts included those concerning small and large signal control-dependent performance analysis and simulation, control circuit design, power circuit design and optimization, system configuration study, and system performance simulation. Techniques including discrete time domain, conventional frequency domain, Lagrange multiplier, nonlinear programming, and control design synthesis were employed in these efforts. To enhance interactive conversation between the modeling and analysis subprograms and the user, a working prototype of the Data Management Program was also developed to facilitate expansion as future subprogram capabilities increase.

Yu, Y.↗

NASA NTRS1977

New batteries and their impact on electric vehicles

The paper is concerned with the development of electric vehicles and electric vehicle batteries. The present and predicted performance levels of some battery systems such as lead-acid, nickel-iron, nickel-zinc, and zinc-chlorine are considered, as are the characteristics that an electric vehicle must possess in order to appeal to customers. The implications of battery improvements for manufacturers of electric vehicles are discussed. Lack of knowledge of passenger range requirements for electric vehicles is noted.

Schwartz, H. J.↗

NASA NTRS1977

KREEP petrogenesis revisited

An experimentally determined crystallization sequence for a composition similar to the LKFM breccias and experimentally determined crystal/liquid distribution coefficients are used to calculate the evolution of the abundances of several key elements during the crystallization of LKFM liquids. Results indicate that the LKFM breccias are not themselves precursors to Apollo 15 igneous KREEP, but that compositions slightly poorer in Ti and Fe might be. Consideration of the evolution of Ti and Sm abundances during the differentiation of proposed whole-moon compositions suggests that it may be necessary to appeal to 'unorthodox' mechanisms such as magma hybridization or interaction of magma with genetically unrelated minerals within the lunar crust to produce KREEP-rich liquids having the observed Ti/Sm. It is concluded that the compositions of samples with Sm contents greater than those in LKFM are dominated by igneous processes, while samples with lower Sm contents may be mixtures of an anorthositic component, a Mg-rich Sm-poor component, and a component similar in composition to LKFM.

Mckay, G. A.↗

NASA NTRS1979

Scientific and technical applications of a tethered satellite system

A Shuttle-borne tether system capable of deploying a tether to radial distances as great as 100 km was described by Rupp and Laue (1978). The system as discussed by Rupp and Laue would have a total mass of 700 kg and would be mounted on one Shuttle pallet. It would consist of a tether reel mechanism complete with a servo drive motor and control sensors, a boom with docking probe used for initial deployment and subsequent retrieval, some type of satellite weighing 175 kg, up to 100 km of synthetic or metallic tether approximately 1 mm in diameter, a digital control computer, and a control and display panel on the Orbiter aft flight deck for crew operation. The primary use of a tether system for geological applications would be in the measurement of those magnetic and gravitational fields associated with geological structures. The major appeal in connection with atmospheric applications is the system's ability to extend instrumentation down into the lower thermosphere and possibly the mesosphere.

Snoddy, W. C.↗

NASA NTRS1980

Air cargo market outlook and impact via the NASA CLASS project

An overview is given of the Cargo/Logistics Airlift Systems Study (CLASS) project which was a 10 man-year effort carried out by two contractor teams, aimed at defining factors impacting future system growth and obtaining market requirements and design guidelines for future air freighters. Growth projection was estimated by two approaches: one, an optimal systems approach with a more efficient and cost effective system considered as being available in 1990; and the other, an evolutionary approach with an econometric behavior model used to predict long term evolution from the present system. Both approaches predict significant growth in demand for international air freighter services and less growth for U.S. domestic services. Economic analysis of air freighter fleet options indicate very strong market appeal of derivative widebody transports in 1990 with little incentive to develop all new dedicated air freighters utilizing the 1990's technology until sometime beyond the year 2000. Advanced air freighters would be economically attractive for a wide range of payload sizes (to 500 metric tons), however, if a government would share in the RD and T costs by virtue of its needs for a slightly modified version of a civil air freighter design (a.g. military airlifter).

Winston, M. M.↗

NASA NTRS1981

Slosh dynamics of a spin-stabilized spacecraft comprising off-axis tanks filled partially with liquid propellant

The fundamental nonlinear equations of motion were derived and the specialized to a steady-state rotation of the vehicle about a given axis of rotation. A thrust about the spin axis was introduced. A perturbation solution was derived which linearizes the problem. The effect of the centrifugal and coriolis accelerations together with vorticity are implicitly taken into consideration in the formulation. A variational formulation of the associated boundary conditions is presented. For practical cases it is shown that the simple classical pendulum representation for slosh is not very appealing for a spinning spacecraft unless severe restrictions are allowed.

Fontenot, L. L.↗

NASA NTRS1981

Satellite services - An added benefit of the space transportation system

It is argued that the greatest economic benefit can be achieved by the Space Shuttle Orbiter's use as a satellite servicing platform if the following conditions are fulfilled: (1) the international user community must build serviceability features into its satellite and orbital platform designs, based on a common set of guidelines; (2) the various tools required for satellite servicing must be developed in a timely manner; and (3) servicing costs must be kept as low as possible, in order to appeal to the greatest number and variety of satellite operators. A three-part program development schedule is proposed, beginning with near-Orbiter servicing in low earth orbit, continuing with servicing at orbital heights between the low and geosynchronous at greater distances from the Orbiter, and culminating in the early 1990's with the use of the Space Operations Center (SOC) platform for servicing at all orbital heights.

Herardian, M. M.↗

NASA NTRS1980

Conceptual design study of a visual system for a rotorcraft simulator and some advances in platform motion utilization

A conceptual design of a visual system for a rotorcraft flight simulator is presented. Also, drive logic elements for a coupled motion base for such a simulator are given. The design is the result of an assessment of many potential arrangements of electro-optical elements and is a concept considered feasible for the application. The motion drive elements represent an example logic for a coupled motion base and is essentially an appeal to the designers of such logic to combine their washout and braking functions.

Sinacori, J. B.↗

NASA NTRS1981

Identification and evaluation of software measures

A large scale, systematic procedure for identifying and evaluating measures that meaningfully characterize one or more elements of software development is described. The background of this research, the nature of the data involved, and the steps of the analytic procedure are discussed. An example of the application of this procedure to data from real software development projects is presented. As the term is used here, a measure is a count or numerical rating of the occurrence of some property. Examples of measures include lines of code, number of computer runs, person hours expended, and degree of use of top down design methodology. Measures appeal to the researcher and the manager as a potential means of defining, explaining, and predicting software development qualities, especially productivity and reliability.

Card, D. N.↗

NASA NTRS1981

Cleanroom software development

The 'cleanroom' software development process is a technical and organizational approach to developing software with certifiable reliability. Key ideas behind the process are well structured software specifications, randomized testing methods and the introduction of statistical controls; but the main point is to deny entry for defects during the development of software. This latter point suggests the use of the term 'cleanroom' in analogy to the defect prevention controls used in the manufacturing of high technology hardware. In the 'cleanroom', the entire software development process is embedded within a formal statistical design, in contrast to executing selected tests and appealing to the randomness of operational settings for drawing statistical inferences. Instead, random testing is introduced as a part of the statistical design itself so that when development and testing are completed, statistical inferences are made about the operation of the system.

Dyer, M.↗

NASA NTRS1981

A preliminary assessment of the problems in the use of interference filter photometers to determine total ozone

In the spring of 1979 an investigation was started involving the intercomparison of five ground based instruments designed to measure total ozone. The instruments considered include the Dobson spectrometer, the Russian M-83 ozonometer, the Brewer Ozone Spectrophotometer, the New Zealand (Canterbury) filter photometer, and the SenTran Company filter photometer. Three of these instruments use optical filters to make spectrophotometric determinations of total atmospheric ozone. The M-83 uses glass absorption filters to isolate the ultraviolet bands used. The Canterbury and the SenTran instruments use narrow-bandpass dielectric interference filters for the same purpose. Instruments employing optical filters are very appealing since they can be made small, rugged, and relatively inexpensive. However, the results of the reported investigation show that serious problems must be resolved before any filter instrument can be considered reliable enough for the conduction of long term, meaningful ozone measurements.

Gerlach, J. C.↗

NASA NTRS1983

A viscous shock-layer flowfield analysis by an explicit-implicit method

An implicit analogue of a widely used explicit method to external axisymmetric laminar flows with strong entropy gradients is extended. The details of the "numerics" of the implicit part are provided in a body oriented coordinate system with a moving outer (shock) boundary during the transient part of the solutions. The limiting values of the Courant number are obtained when the shock boundary is treated explicitly. The solution algorithm outlined includes the treatment of the source term associated with the equations in weak conservation form. From the results obtained for two sample problems, it becomes clear that accuracy of predictions is, indeed, very good at higher values of the Courant number. There is a significant saving in overall computing time, depending on the Courant number used and the flow Reynolds number. These properties combined with the simplicity of programming the implicit analog may appeal to researchers for using it in the analysis of 3-D flow problems.

Gupta, R. M.↗

NASA NTRS1982

Spline approximations for nonlinear hereditary control systems

A sline-based approximation scheme is discussed for optimal control problems governed by nonlinear nonautonomous delay differential equations. The approximating framework reduces the original control problem to a sequence of optimization problems governed by ordinary differential equations. Convergence proofs, which appeal directly to dissipative-type estimates for the underlying nonlinear operator, are given and numerical findings are summarized.

Daniel, P. L.↗

NASA NTRS1983

Viscous shock-layer flowfield analysis by an explicit-implicit method

The present work extends the recently reported implicit analogue of MacCormack's earlier widely-used explicit method to external axisymmetric laminar flows with strong entropy gradients. The details of the 'numerics' of the implicit part are provided in a body-oriented coordinate system with a moving outer (shock) boundary during the transient part of the solutions. The limiting values of the Courant number are obtained when the shock boundary is treated explicitly. The solution algorithm outlined includes the treatment of the source term associated with the equations in weak conservation form. From the results obtained for two sample problems, it becomes clear that accuracy of predictions is, indeed, very good at higher values of the Courant number. There is a significant saving in overall computing time, depending on the Courant number used and the flow Reynolds number. These properties combined with the simplicity of programming the implicit analogue may appeal to researchers for using it in the analysis of three-dimensional flow problems.

Gupta, R. N.↗

NASA NTRS1983

Coronal heating by waves

Alfven waves or Alfvenic surface waves carry enough energy into the corona to provide the coronal energy requirements. Coronal loop resonances are an appealing means by which large energy fluxes enter active region loops. The wave dissipation mechanism still needs to be elucidated, but a Kolmogoroff turbulent cascade is fully consistent with the heating requirements in coronal holes and active region loops.

Hollweg, J. V.↗