Variation of hydrodynamic impact loads with flight-path angle for a prismatic float at 12 degree trim and with a 22-1/2 degree angle of dead rise
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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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Comparative Cooling of Cylinders of Nonuniform Fin Width with Tight-fitting Baffles and with Baffles that Provide Constant Flow-path Areas
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ENGINE CYLINDERS-TEMPERATURES↗
Paths of target-seeking missiles in two dimensions
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Watkins, Charles E↗
Path programmable logic: A structured design method for digital and/or mixed analog integrated circuits
The design of Integrated Circuits has evolved past the black art practiced by a few semiconductor companies to a world wide community of users. This was basically accomplished by the development of computer aided design tools which were made available to this community. As the tools matured into different components of the design task they were accepted into the community at large. However, the next step in this evolution is being ignored by the large tool vendors hindering the continuation of this process. With system level definition and simulation through the logic specification well understood, why is the physical generation so blatantly ignored. This portion of the development is still treated as an isolated task with information being passed from the designer to the layout function. Some form of result given back but it severely lacks full definition of what has transpired. The level of integration in I.C.'s for tomorrow, whether through new processes or applications will require higher speeds, increased transistor density, and non-digital performance which can only be achieved through attention to the physical implementation.
Taylor, B.↗
Long duration measurements of fading on a low elevation angle, 11-GHz satellite path
Some rainfall rate and beacon fade results from the first 5 years of continuous observations of an 11.2 GHz satellite beacon with a 5.8 degree elevation angle in Austin, Texas are presented and compared to Consultative Committee for International Radio (CCIR) predictions.
Vogel, Wolfhard J.↗
Effects of a shading band in the data path of an optical drive
A shading band can alter the system transfer function. In our theory and experiment, both contrast improvement and enhanced carrier-to-noise ratio are investigated.
Milster, T. D.↗
Low cost paths to binary optics
Application of binary optics has been limited to a few major laboratories because of the limited availability of fabrication facilities such as e-beam machines and the lack of standardized design software. Foster-Miller has attempted to identify low cost approaches to medium-resolution binary optics using readily available computer and fabrication tools, primarily for the use of students and experimenters in optical computing. An early version of our system, MacBEEP, made use of an optimized laser film recorder from the commercial typesetting industry with 10 micron resolution. This report is an update on our current efforts to design and build a second generation MacBEEP, which aims at 1 micron resolution and multiple phase levels. Trails included a low cost scanning electron microscope in microlithography mode, and alternative laser inscribers or photomask generators. Our current software approach is based on Mathematica and PostScript compatibility.
Nelson, Arthur↗
Finding the path to a better Mars rover
A Microrover Flight Experiment (MFEX) based on a basic Rocky 4 design and conducted in the framework of the NASA Mars Environmental Survey (MESUR) Pathfinder program is described. The MFEX rover design features six powered wheels attached by a set of 'bogie levers' to a single body. The rover is designed to perform technology, science, and mission experiments. Instruments on the rover mechanisms will determine wheel-soil interactions, detect hazards, and determine navigational errors. Science data will be gathered using an alpha-proton-X-ray spectrometer against one or more rocks, and possible soil. The pathfinder will also serve as an engineering test of a transport and landing system for the MESUR network mission and the rover will image the lander to assess its condition.
Pivirotto, Donna S.↗
A nonlinear strategy for sensor based vehicle path control
A method of transverse control which makes use of nonlinear formulations is presented. The strategy is utilized to stabilize a vehicle. The vehicle is autonomously guided and takes its control inputs from an optical sensing system. Additionally, the velocity of the vehicle is dictated by a longitudinal controller, which is also discussed.
Mayr, R.↗
A practical method of reverse engineering and automatic path programming for robotic surface finishing
A method of robotic surface finishing is discussed. The method is question incorporates COTS (commercial of the shelf) technology.
Adams, William T.↗
The path to an experiment in space (from concept to flight)
The following are discussed in this viewgraph presentation on developing flight experiments for NASA's Microgravity Science and Applications Program: time from flight PI selection to launch; key flight experiment phases and schedule drivers; microgravity experiment definition/development process; definition and engineering development phase; ground-based reduced gravity research facilities; project organization; responsibilities and duties of principle investigator/co-investigators, project scientist, and project manager; the science requirements document; flight development phase; experiment cost and schedule; and keys to experiment success.
Salzman, Jack A.↗
Linear and nonlinear dynamic analysis of redundant load path bearingless rotor systems
The goal of this research is to develop the transfer matrix method to treat nonlinear autonomous boundary value problems with multiple branches. The application is the complete nonlinear aeroelastic analysis of multiple-branched rotor blades. Once the development is complete, it can be incorporated into the existing transfer matrix analyses. There are several difficulties to be overcome in reaching this objective. The conventional transfer matrix method is limited in that it is applicable only to linear branch chain-like structures, but consideration of multiple branch modeling is important for bearingless rotors. Also, hingeless and bearingless rotor blade dynamic characteristics (particularly their aeroelasticity problems) are inherently nonlinear. The nonlinear equations of motion and the multiple-branched boundary value problem are treated together using a direct transfer matrix method. First, the formulation is applied to a nonlinear single-branch blade to validate the nonlinear portion of the formulation. The nonlinear system of equations is iteratively solved using a form of Newton-Raphson iteration scheme developed for differential equations of continuous systems. The formulation is then applied to determine the nonlinear steady state trim and aeroelastic stability of a rotor blade in hover with two branches at the root. A comprehensive computer program is developed and is used to obtain numerical results for the (1) free vibration, (2) nonlinearly deformed steady state, (3) free vibration about the nonlinearly deformed steady state, and (4) aeroelastic stability tasks. The numerical results obtained by the present method agree with results from other methods.
Murthy, V. R.↗
SSME propellant path leak detection real-time
Included are four documents that outline the technical aspects of the research performed on NASA Grant NAG8-140: 'A System for Sequential Step Detection with Application to Video Image Processing'; 'Leak Detection from the SSME Using Sequential Image Processing'; 'Digital Image Processor Specifications for Real-Time SSME Leak Detection'; and 'A Color Change Detection System for Video Signals with Applications to Spectral Analysis of Rocket Engine Plumes'.
Crawford, R. A.↗
Chondrule precursors and cooling paths: The sulfur evidence
The behavior of moderately volatile elements (Na and S) is controversial but critical in understanding chondrule precursors and heating processes. Sulfide appeared to be present in most chondrules, but S should have been vaporized during chondrule formation. In fact, S is extensively redistributed in the course of metamorphism, and its abundance at the end of chondrule formation can only be inferred from the least equilibrated chondrites. Our study of 530 chondrules from Renazzo (CR2) and Semarkona (LL3.0) shows partial volatilization of S during chondrule formation and our melting experiments define conditions for total loss or partial retention of S.
Zanda, B.↗
Scintillation fading on a low elevation angle satellite path: Assessing the Austin experiment at 11.2 GHz
The University of Texas at Austin is now in its fifth year of observing an 11.2 GHz INTELSAT satellite beacon with an elevation angle of only 5.8 degrees. Measurements of the rainfall rate, beacon level, the radiometric sky temperature, and of meteorological parameters are ongoing. The experiment is motivated by the fact that significant increases in coverage can be obtained from a given geostationary orbit location if acceptable performance can be achieved at elevation angles below the current standard at Ku-Band of 10 degrees. The topics covered include the following: data collection, data processing, scintillation fading vs. rain fading, diurnal and seasonal variations, power spectrum, and variability of the beacon standard deviation.
Vogel, W. J.↗
A new path for the electron bulk energization in solar flares: Fermi acceleration by magnetohydrodynamic turbulence in reconnection outflows
We recently proposed that a magnetohydrodynamic (MHD) turbulent cascade produces the bulk energization of electrons to approximately 25 keV in the impulsive phase of solar flares (LaRosa & Moore 1993). In that scenario, (1) the cascading MHD turbulence is fed by shear-unstable Alfvenic outflows from sites of strongly driven reconnection in the low corona, and (2) the electrons are energized by absorbing the energy that flows down through the cascade. We did not specify the physical mechanism by which the cascading energy is ultimately transferred to the electrons. Here we propose that Fermi acceleration is this mechanism, the process by which the electrons are energized and by which the cascading MHD turbulence is dissipated. We point out that in the expected cascade MHD fluctuations of scale 1 km can Fermi-accelerate electrons from 0.1 keV to approximately 25 keV on the subsecond timescales observed in impulsive flares, provided there is sufficient trapping and scattering of electrons in the MHD turbulence. We show that these same fluctuations provide the required trapping; they confine the electrons within the turbulent region until the turbulence eis dissipated. This results in the energization of all of the lectrons in each large-scale (5 x 10(exp 7)cm) turbulent eddy to 25 keV. The Fermi process also requires efficient scattering so that the pitch-angle distribution of the accelerating electrons remains isotropic. We propose that the electrons undergo resonant scattering by high-frequency plasma R-waves that, as suggested by others (Hamilton & Petrosian 1992), are generated by the reconnection. Ions are not scattered by R-waves. Provided that there is negligible generation of ion-scattering plasma turbulence (e.g., L-waves) by the reconnection or the MHD turbulence, the ions will not Fermi-accelerate and the cascading energy is transferred only to the electrons. We conclude that, given this situation, electron Fermi acceleration can plausibly account for the electron bulk energization in impulsive solar flares.
Larosa, T. N.↗
SMES: Redefining the path to commerical demonstration
SMES (Superconducting Magnetic Energy Storage) is an emerging technology offering tremendous potential benefits to the utility industry. San Diego Gas & Electric (SDG&E) and Bechtel are leading a team of companies and national laboratories working towards design and construction of the world's first demonstration facility for large, commercial SMES for enhancing transmission stability in the Southwestern United States.
Bingham, W. G.↗
SSME propellant path leak detection
Initial research established that the occurrence of a leak in the powerhead of the Space Shuttle Main Engine (SSME) is accompanied by a sudden, but sustained, change in intensity in a given region of an image. Based upon this, temporal processing of video images on a frame-by-frame basis has been used to detect leaks within a given field of view. The leak detection algorithm developed in this study consists of a digital highpass filter cascaded with a moving average filter applied at each point in the image field. The absolute value of the output is then averaged over the full frame to produce a single time-varying mean value estimate that is indicative of the intensity and extent of a leak. Recent work has included the processing of an extensive amount of data obtained from NASA MSFC to verify the performance of the leak detection system. Further research is being conducted on applying the leak detection algorithm to anomaly detection in the SSME exhaust by means of three channel color processing as opposed to single channel monochrome processing in the case of the leak detection system.
Smith, L. M.↗