Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Alternative Relativity”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Abstract for CRADA between National Energy Technology Laboratory and ClearSign Technologies Corporation

The National Energy Technology Laboratory (NETL) and ClearSign Technologies Corporation (Participant) will collaborate in the development of a preliminary LCA for the scaling of a hydrogen burner product currently in proof of concept and primarily developed for chemicals processing at refineries. The current combustion product has been tested at 80% hydrogen content (20% natural gas) and maintains the NOx 97% improvement vs incumbent technologies, yet the GHG emissions of the product and use case in refining to chemicals processing would be the focus of this preliminary LCA. The Participant has noted areas where they expect environmental improvements relative to alternatives, but these improvements have not been quantified to date. The collaboration will facilitate characterizing the emissions improvement comparative to some selected incumbent technologies during the deployment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1976

Technology assessment of future intercity passenger transportation systems. Volume 4: Scenarios

Four background scenarios that relate to alternative states of society in the next 25 to 50 years are described. The scenarios were developed for use in analyzing and evaluating alternative future intercity transportation technologies. The scenarios are based, in part, on discussions contained in the issue papers and, in part, on separate analysis of social and economic trends considered relevant for the evolution of intercity transportation.

Source record↗
NASA NTRS1977

Preliminary design study of a baseline MIUS

Results of a conceptual design study to establish a baseline design for a modular integrated utility system (MIUS) are presented. The system concept developed a basis for evaluating possible projects to demonstrate an MIUS. For the baseline study, climate conditions for the Washington, D.C., area were used. The baseline design is for a high density apartment complex of 496 dwelling units with a planned full occupancy of approximately 1200 residents. Environmental considerations and regulations for the MIUS installation are discussed. Detailed cost data for the baseline MIUS are given together with those for design and operating variations under climate conditions typified by Las Vegas, Nevada, Houston, Texas, and Minneapolis, Minnesota. In addition, results of an investigation of size variation effects, for 300 and 1000 unit apartment complexes, are presented. Only conceptual aspects of the design are discussed. Results regarding energy savings and costs are intended only as trend information and for use in relative comparisons. Alternate heating, ventilation, and air conditioning concepts are considered in the appendix.

Wolfer, B. M.↗
NASA NTRS1979

An investigation of several factors involved in a finite difference procedure for analyzing the transonic flow about harmonically oscillating airfoils and wings

Analytical and empirical studies of a finite difference method for the solution of the transonic flow about harmonically oscillating wings and airfoils are presented. The procedure is based on separating the velocity potential into steady and unsteady parts and linearizing the resulting unsteady equations for small disturbances. Since sinusoidal motion is assumed, the unsteady equation is independent of time. Three finite difference investigations are discussed including a new operator for mesh points with supersonic flow, the effects on relaxation solution convergence of adding a viscosity term to the original differential equation, and an alternate and relatively simple downstream boundary condition. A method is developed which uses a finite difference procedure over a limited inner region and an approximate analytical procedure for the remaining outer region. Two investigations concerned with three-dimensional flow are presented. The first is the development of an oblique coordinate system for swept and tapered wings. The second derives the additional terms required to make row relaxation solutions converge when mixed flow is present. A finite span flutter analysis procedure is described using the two-dimensional unsteady transonic program with a full three-dimensional steady velocity potential.

Ehlers, F. E.↗
NASA NTRS1979

Multiple scattering and charged-particle - hydrogen-atom collisions

Glauber-approximation scattering amplitudes for charged-particle - hydrogen-atom elastic and inelastic collisions are derived directly in terms of the known particle-electron and particle-proton Coulomb scattering amplitudes and the known hydrogen-atom form factors. It is shown that the particle-hydrogen amplitude contains no single-scattering term. The double-scattering term is obtained as a two-dimensional integral in momentum space. It is demonstrated how the result can be used as the starting point for an alternative and relatively simple derivation, in closed form, of the Glauber particle-hydrogen scattering amplitude for transitions from the ground state to an arbitrary (nlm) state.

Franco, V.↗
NASA NTRS1984

Valles Marineris layered deposits: Implications of origin

Layered deposits within Valles Marineris and its associated system of canyons have been considered to consist of two different rock types: (1) thick, competent, cliff-forming, light and dark bedded material in canyon walls, and (2) relatively thin, alternating series of light and dark layered material, both horizontal and inclined, that form rounded hills and large flat-topped mesas rising above the canyon floors. The dissimilarity in appearance between canyon wall and floor materials, as well as their contrasting patterns of erosion, have been considered strong evidence that their modes of origin were different.

Scott, D. H.↗
NASA NTRS1983

A study of space station needs, attributes and architectural options, volume 2, technical. Book 3: Economic benefits, costs and programmatics

The economic benefits, cost analysis, and industrial uses of the manned space station are investigated. Mission payload costs are examined in relation to alternative architectures and projected technological evolution. Various approaches to industrial involvement for financing, development, and marketing of space station resources are described.

Source record↗
NASA NTRS1985

On the geodetic applications of simultaneous range differences to Lageos

While the majority of the currently deployed satellite laser systems are of centimeter level precision, the accuracy of the geodetic products corresponds to the accuracy in which geodesists are interested. On several occasions, the best models are either not good enough or result in tedious computations which are required to achieve accuracies comparable to those of the observations. A possible alternative is related to the development of a new method of data analysis. This method involves the minimization of the effect of the systematic errors and, in particular, the minimization of errors arising from an incorrectly modeled orbit. The present paper provides a summary of the results of a study of this option, taking into account laser ranging data from Lageos.

Pavlis, E. C.↗
NASA NTRS1988

Growth of electron plasma waves above and below f(p) in the electron foreshock

This paper investigates the conditions required for electron beams to drive wave growth significantly above and below the electron plasma frequency, f(p), by numerically solving the linear dispersion equation. It is shown that kinetic growth well below f(p) may occur over a broad range of frequencies due to the beam instability, when the electron beam is slow, dilute, and relatively cold. Alternatively, a cold or sharp feature at low parallel velocities in the distribution function may drive kinetic growth significantly below f(p). Kinetic broadband growth significantly above f(p) is explained in terms of faster warmer beams. A unified qualitative theory for the narrow-band and broad-band waves is proposed.

Cairns, Iver H.↗
NASA NTRS1989

High resolution flow field prediction for tail rotor aeroacoustics

The prediction of tail rotor noise due to the impingement of the main rotor wake poses a significant challenge to current analysis methods in rotorcraft aeroacoustics. This paper describes the development of a new treatment of the tail rotor aerodynamic environment that permits highly accurate resolution of the incident flow field with modest computational effort relative to alternative models. The new approach incorporates an advanced full-span free wake model of the main rotor in a scheme which reconstructs high-resolution flow solutions from preliminary, computationally inexpensive simulations with coarse resolution. The heart of the approach is a novel method for using local velocity correction terms to capture the steep velocity gradients characteristic of the vortex-dominated incident flow. Sample calculations have been undertaken to examine the principal types of interactions between the tail rotor and the main rotor wake and to examine the performance of the new method. The results of these sample problems confirm the success of this approach in capturing the high-resolution flows necessary for analysis of rotor-wake/rotor interactions with dramatically reduced computational cost. Computations of radiated sound are also carried out that explore the role of various portions of the main rotor wake in generating tail rotor noise.

Quackenbush, Todd R.↗
NASA NTRS1991

Hot Oil Removes Wax

Mineral oil heated to temperature of 250 degrees F (121 degrees C) found effective in removing wax from workpieces after fabrication. Depending upon size and shape of part to be cleaned of wax, part immersed in tank of hot oil, and/or interior of part flushed with hot oil. Pump, fittings, and ancillary tooling built easily for this purpose. After cleaning, innocuous oil residue washed off part by alkaline aqueous degreasing process. Serves as relatively safe alternative to carcinogenic and environmentally hazardous solvent perchloroethylene.

Herzstock, James J.↗
NASA NTRS1991

Assessing damping uncertainty in space structures with fuzzy sets

NASA has been interested in the development of methods for evaluating the predictive accuracy of structural dynamic models. This interest stems from the use of mathematical models in evaluating the structural integrity of all spacecraft prior to flight. Space structures are often too large and too weak to be tested fully assembled in a ground test lab. The predictive accuracy of a model depends on the nature and extent of its experimental verification. The further the test conditions depart from in-service conditions, the less accurate the model will be. Structural damping is known to be one source of uncertainty in models. The uncertainty in damping is explored in order to evaluate the accuracy of dynamic models. A simple mass-spring-dashpot system is used to illustrate a comparison among three methods for propagating uncertainty in structural dynamics models: the First Order Method, the Numerical Simulation Method, and the Fuzzy Set Method. The Fuzzy Set Method is shown to bound the range of possible responses and thus to provide a valuable limiting check on the First Order Method near resonant conditions. Fuzzy Methods are a relative inexpensive alternative to numerical simulation.

Ross, Timothy J.↗
NASA NTRS1991

Atomic oxygen stimulated outgassing

The passive Long Duration Exposure Facility (LDEF) Experiment A0034, Atomic Oxygen Simulated Outgassing, consisted of two identical one-sixth tray modules, exposing selected thermal control coatings to atomic oxygen and the combined space environment on the leading edge and, for reference, to the relative wake environment on the trailing edge. Optical mirrors were included adjacent to the thermal coatings for deposition of outgassing products. Ultraviolet grade windows and metal covers were provided for additional assessment of the effects of the various environmental factors. Preliminary results indicate that orbital atomic oxygen is both a degrading and a optically restorative factor in the thermo-optical properties of selected thermal coatings. There is evidence of more severe optical degradation on collector mirrors adjacent to coatings that were exposed to the RAM-impinging atomic oxygen. This evidence of atomic oxygen stimulated outgassing is discussed in relation to alternative factors that could affect degradation. The general effects of the space environment on the experiment hardware as well as the specimens are discussed.

Linton, Roger C.↗
NASA NTRS1991

The role of impacts in the history of the early earth

The significant conclusions of a conference called 'Meteorite Impact and the Early Earth' are reported including data which support the notion that extraterrestrial impacts greatly influenced the development of the earth. The cratering of other planetary surfaces is discussed, and the energy added by meteorite impacts is characterized. The primary effects of large impacts are set forth in terms of atmospheric, oceanic, and biological considerations which suggest that the ramifications would have been significant. Contentious issues include the variation of impact rate with time in the early universe, the interpretation of the record of intense bombardment in the lunar highlands, and the effects related to alternative scenarios. Directions of future study are mentioned including the identification of terrestrial impact structures, conducting searches in the Archean, and assessing ancient impact rates.

French, Bevan M.↗
NASA NTRS1992

LDEF experiment A0034: Atomic oxygen stimulated outgassing

The passive Long Duration Exposure Facility (LDEF) Experiment A0034, 'Atomic Oxygen Stimulated Outgassing', consisted of two identical one-sixth tray modules, exposing selected thermal control coatings to atomic oxygen and the combined space environment on the leading edge, and for reference, to the relative 'wake' environment of the trailing edge. Optical mirrors were included adjacent to the thermal coatings for deposition of the outgassing products. Ultraviolet grade windows and metal covers were provided for additional assessment of the effects of various environmental factors. Preliminary results indicate that orbital atomic oxygen is both a degrading and optically restorative factor in the thermo-optical properties of selected thermal coatings. There is evidence of more severe optical degradation on collector mirrors adjacent to coatings that were exposed to RAM-impinging atomic oxygen. This evidence of atomic oxygen stimulated outgassing is discussed in relation to alternative factors that could affect degradation. The general effects of the space environment on the experiment hardware as well as the specimens are discussed.

Linton, Roger C.↗
NASA NTRS1991

Prediction of high-resolution flowfields for rotorcraft aeroacoustics

A new approach to the vortex wake of a helicopter is described. This approach makes it possible to obtain highly accurate resolution of the flowfield experienced by the tail rotor with modest computational effort relative to alternative models. A full-span free wake model of the main rotor in a scheme is presented which reconstructs high resolution flow solutions from preliminary simulations with coarse resolution. A new reconstruction method uses local velocity correction terms to capture the steep velocity gradients characteristic of the the vortex-dominated incident flow. The approach is considered to be successful in capturing the high resolution flows necessary for analysis of rotor-wake/rotor interactions with substantially reduced computational cost.

Quackenbush, Todd R.↗
NASA NTRS1993

Relation between bond-length alternation and second electronic hyperpolarizability of conjugated organic molecules

The solvent dependence of the second hyperpolarizability, gamma, of a variety of unsaturated organic compounds has been measured by third harmonic generation at 1907 nanometers. It is seen that the measured gamma is a function of solvent polarity. These solvent-dependent hyperpolarizabilities are associated with changes in molecular geometry from a highly bond-length alternated, polyenelike structure for a formyl-substituted compound in nonpolar solvents, to a cyaninelike structure, with little bond-length alternation, for a dicyanovinyl-substituted compound in polar solvents. By tuning bond-length alternation, gamma can be optimized in either a positive or negative sense for polymethine dyes of a given conjugation length.

Marder, Seth R.↗
NASA NTRS1995

Viscous-flow analysis of a subsonic transport aircraft high-lift system and correlation with flight data

High-lift system aerodynamics has been gaining attention in recent years. In an effort to improve aircraft performance, comprehensive studies of multi-element airfoil systems are being undertaken in wind-tunnel and flight experiments. Recent developments in Computational Fluid Dynamics (CFD) offer a relatively inexpensive alternative for studying complex viscous flows by numerically solving the Navier-Stokes (N-S) equations. Current limitations in computer resources restrict practical high-lift N-S computations to two dimensions, but CFD predictions can yield tremendous insight into flow structure, interactions between airfoil elements, and effects of changes in airfoil geometry or free-stream conditions. These codes are very accurate when compared to strictly 2D data provided by wind-tunnel testing, as will be shown here. Yet, additional challenges must be faced in the analysis of a production aircraft wing section, such as that of the NASA Langley Transport Systems Research Vehicle (TSRV). A primary issue is the sweep theory used to correlate 2D predictions with 3D flight results, accounting for sweep, taper, and finite wing effects. Other computational issues addressed here include the effects of surface roughness of the geometry, cove shape modeling, grid topology, and transition specification. The sensitivity of the flow to changing free-stream conditions is investigated. In addition, the effects of Gurney flaps on the aerodynamic characteristics of the airfoil system are predicted.

Potter, R. C.↗