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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 919 records · Page 51
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Estimating costs and performance of systems for machine processing of remotely sensed data

This paper outlines a method for estimating computer processing times and costs incurred in producing information products from digital remotely sensed data. The method accounts for both computation and overhead, and may be applied to any serial computer. The method is applied to estimate the cost and computer time involved in producing Level II Land Use and Vegetative Cover Maps for a five-state midwestern region. The results show that the amount of data to be processed overloads some example computer systems, but that the processing is feasible on others.

Ballard, R. J.↗
NASA NTRS1978

GPS-aided Space Shuttle navigation

In the present paper, specific GPS (Global Positioning System) aided Shuttle navigation are presented as examples of the navigation performance prediction process. The process described is a statistical covariance error analysis. To facilitate detailing, the process is broken down into four portions with sharply limited interfaces. Considerations of mission scenarios form one distinct package of computer routines. Simulation of the onboard navigation filter is another facet of the process, as are the larger system covariance program and the GPS segment covariance simulation. The combination of these computer tools permits proper evaluation of the multitude of correlated error sources affecting GPS-aided Shuttle navigation.

Matchett, G.↗
NASA NTRS1980

Incorporation of star measurements for the determination of orbit and attitude parameters of a geosynchronous satellite: An iterative application of linear regression

Currently on NOAA/NESS's VIRGS system at the World Weather Building star images are being ingested on a daily basis. The image coordinates of the star locations are measured and stored. Subsequently, the information is used to determine the attitude, the misalignment angles between the spin axis and the principal axis of the satellite, and the precession rate and direction. This is done for both the 'East' and 'West' operational geosynchronous satellites. This orientation information is then combined with image measurements of earth based landmarks to determine the orbit of each satellite. The method for determining the orbit is simple. For each landmark measurement one determines a nominal position vector for the satellite by extending a ray from the landmark's position towards the satellite and intersecting the ray with a sphere with center coinciding with the Earth's center and with radius equal to the nominal height for a geosynchronous satellite. The apparent motion of the satellite around the Earth's center is then approximated with a Keplerian model. In turn the variations of the satellite's height, as a function of time found by using this model, are used to redetermine the successive satellite positions by again using the Earth based landmark measurements and intersecting rays from these landmarks with the newly determined spheres. This process is performed iteratively until convergence is achieved. Only three iterations are required.

Phillips, D.↗
NASA NTRS1981

Evaluation and verification of epitaxial process sequence for silicon solar cell production

The applicability of solar cell and module processing sequences, to be used on lower cost epitaxial silicon wafers was evaluated. The extent to which the process sequences perform effectively when applied to film solar cells formed by epitaxial deposition of Si on potentially inexpensive substrates of upgraded metallurgical grade Si is examined. It is concluded that these substrates are satisfactory in their cell performance.

Redfield, D.↗
NASA NTRS1982

Recent advances in remote sensing; Proceedings of the First International Geoscience and Remote Sensing Symposium, Washington, DC, June 8-10, 1981

The state of the art in remote sensing of the earth and the planets was discussed in terms of sensor performance, signal processing, and data interpretation. Particular attention was given to lidar for characterizing atmospheric particulates, the modulation of short waves by long ocean gravity waves, and runoff modeling for snow-covered areas. The use of NOAA-6 spacecraft AVHRR data to explore hydrologic land surface features, the effects of soil moisture and vegetation canopies on microwave and thermal microwave emissions, and regional scale evapotranspiration rate determination through satellite IR data are examined. A Shuttle experiment to demonstrate high accuracy global time and frequency transfer is described, along with features of the proposed Gravsat, radar image processing for rock-type discrimination, and passive microwave sensing of temperature and salinity in coastal zones.

Mcintosh, R.↗
NASA NTRS1982

Automated segment matching algorithm-theory, test, and evaluation

Results to automate the U.S. Department of Agriculture's process of segment shifting and obtain results within one-half pixel accuracy are presented. Given an initial registration, the digitized segment is shifted until a more precise fit to the LANDSAT data is found. The algorithm automates the shifting process and performs certain tests for matching and accepting the computed shift numbers. Results indicate the algorithm can obtain results within one-half pixel accuracy.

Kalcic, M. T.↗
NASA NTRS1984

A new measuring machine in Paris

A new photographic measuring machine is under construction at the Paris Observatory. The amount of transmitted light is measured by a linear array of 1024 photodiodes. Carriage control, data acquisition and on line processing are performed by microprocessors, a S.E.L. 32/27 computer, and an AP 120-B Array Processor. It is expected that a Schmidt telescope plate of size 360 mm square will be scanned in one hour with pixel size of ten microns.

Guibert, J.↗
NASA NTRS1985

A modeling analysis program for the JPL table mountain Io sodium cloud

Progress and achievements in the first year are discussed in three main areas: (1) review and assessment of the massive JPL Table Mountain Io sodium cloud data set, (2) formulation and execution of a plan to perform further processing of this data set, and (3) initiation of modeling activities. The complete 1976-79 and 1981 data sets are reviewed. Particular emphasis is placed on the superior 1981 Region B/C images which provide a rich base of information for studying the structure and escape of gases from Io as well as possible east-west and magnetic longitudinal asymmetries in the plasma torus. A data processing plan is developed and is undertaken by the Multimission Image Processing Laboratory of JPL for the purpose of providing a more refined and complete data set for our modeling studies in the second year. Modeling priorities are formulated and initial progress in achieving these goals is reported.

Smyth, W. H.↗
NASA NTRS1984

Evaluation of error recovery blocks used for cooperating processes

It is pointed out that the increasing computation power and rapidly falling cost of microprocessors and memories have given an impetus to the development of distributed computing systems. There are a number of potential benefits. A number of issues have to be resolved, however, before the full potential of a distributed processing system can be realized. The present investigation is concerned with one such issue, taking into account the effectiveness of implementing recovery blocks (RB's) in backward error recovery for a set of cooperating processes. A quantitative evaluation of three different recovery blocks employed in backward error recovery for concurrent processing is performed.

Shin, K. G.↗
NASA NTRS1984

MOSAIC

The Mosaicked Optical Self-scanned Array Imaging Camera (MOSAIC), is a 50 sq cm active area detector system encompassing 5.76 million picture elements. This camera is being developed for use in astronomical instrumentation requiring the use of large area imaging detectors with high resolution photon counting capability in the space ultraviolet. This paper gives a descriptive outline of the MOSAIC camera system including: the 100 mm diameter microchannel plate intensifier, the 3 x 3 array of 800 x 800 pixel charge coupled devices, the signal processing and buffer storage subsystem, the electronic support and control subsystem, and the data processing subsystem. Performance characteristics of the camera and its subsystems are presented, based on system analysis.

Williams, J. T.↗
NASA NTRS1985

Space Station crew workload - Station operations and customer accommodations

The features of the Space Station which permit crew members to utilize work time for payload operations are discussed. The user orientation, modular design, nonstressful flight regime, in space construction, on board control, automation and robotics, and maintenance and servicing of the Space Station are examined. The proposed crew size, skills, and functions as station operator and mission specialists are described. Mission objectives and crew functions, which include performing material processing, life science and astronomy experiments, satellite and payload equipment servicing, systems monitoring and control, maintenance and repair, Orbital Maneuvering Vehicle and Mobile Remote Manipulator System operations, on board planning, housekeeping, and health maintenance and recreation, are studied.

Shinkle, G. L.↗
NASA NTRS1986

A low-cost optical data acquisition system for vibration measurement

A low cost optical data acquisition system was designed to measure deflection of vibrating rotor blade tips. The basic principle of the new design is to record raw data, which is a set of blade arrival times, in memory and to perform all processing by software following a run. This approach yields a simple and inexpensive system with the least possible hardware. Functional elements of the system were breadboarded and operated satisfactorily during rotor simulations on the bench, and during a data collection run with a two-bladed rotor in the Lewis Research Center Spin Rig. Software was written to demonstrate the sorting and processing of data stored in the system control computer, after retrieval from the data acquisition system. The demonstration produced an accurate graphical display of deflection versus time.

Posta, S. J.↗
NASA NTRS1986

Symbolic generation of elastic rotor blade equations using a FORTRAN processor and numerical study on dynamic inflow effects on the stability of helicopter rotors

The process of performing an automated stability analysis for an elastic-bladed helicopter rotor is discussed. A symbolic manipulation program, written in FORTRAN, is used to aid in the derivation of the governing equations of motion for the rotor. The blades undergo coupled bending and torsional deformations. Two-dimensional quasi-steady aerodynamics below stall are used. Although reversed flow effects are neglected, unsteady effects, modeled as dynamic inflow are included. Using a Lagrangian approach, the governing equations are derived in generalized coordinates using the symbolic program. The program generates the steady and perturbed equations and writes into subroutines to be called by numerical routines. The symbolic program can operate on both expressions and matrices. For the case of hovering flight, the blade and dynamic inflow equations are converted to equations in a multiblade coordinate system by rearranging the coefficients of the equations. For the case of forward flight, the multiblade equations are obtained through the symbolic program. The final multiblade equations are capable of accommodating any number of elastic blade modes. The computer implementation of this procedure consists of three stages: (1) the symbolic derivation of equations; (2) the coding of the equations into subroutines; and (3) the numerical study after identifying mass, damping, and stiffness coefficients. Damping results are presented in hover and in forward flight with and without dynamic inflow effects for various rotor blade models, including rigid blade lag-flap, elastic flap-lag, flap-lag-torsion, and quasi-static torsion. Results from dynamic inflow effects which are obtained from a lift deficiency function for a quasi-static inflow model in hover are also presented.

Reddy, T. S. R.↗
NASA NTRS1987

A study of reduced chromium content in a nickel-base superalloy via element substitution and rapid solidification processing

A study of reduced chromium content in a nickel base superalloy via element substitution and rapid solidification processing was performed. The two elements used as partial substitutes for chromium were Si and Zr. The microstructure of conventionally solidified materials was characterized using microscopy techniques. These alloys were rapidly solidified using the chill block melt spinning technique and the rapidly solidified microstructures were characterized using electron microscopy. The spinning technique and the rapidly solidified microstructures was assessed following heat treatments at 1033 and 1272 K. Rapidly solidified material of three alloys was reduced to particulate form and consolidated using hot isostatic pressing (HIP). The consolidated materials were also characterized using microscopy techniques. In order to evaluate the relative strengths of the consolidated alloys, compression tests were performed at room temperature and 1033 K on samples of as-HIPed and HIPed plus solution treated material. Yield strength, porosity, and oxidation resistance characteristics are given and compared.

Powers, William O.↗
NASA NTRS1987

A more perfect vacuum

Design and operational features, problems and benefits of a Space Ultravacuum Research Facility (SURF), a wake shield, are discussed. SURF is primarily targeted at providing vacuums exceeding 10 to the -14th torr for performing materials processing experiments and, eventually, commercial-scale production. The materials to be processed would be at the apex of a convex shield, with the quality of vacuum limited mainly by the backscattering toward the wake surface of atmospheric molecules which have collided with molecules leaving the SURF surface. A stainless steel skin on the SURF, cured in orbit, is proposed as a means to minimize the molecules outgassed from the surface. Applications of SURF could include coating mirrors or other optical equipment, containerless melting and solidification of materials, and ultrapurification processing.

Naumann, Robert J.↗
NASA NTRS1986

EDC development and testing for the Space Station program

NASA's development of electrochemical CO2 concentration technology has led to the creation of subsystem hardware and control and monitoring instrumentation that are ideally suited to Space Station program applications; only seven orbital replacement units, for instance, are required for the performance of process functions. This process simplification leads to superior reliability and enhanced maintainability. Hardware and software features that enhance subsystem reliability through fault detection and isolation have been emphasized in the course of development. Further power, weight, and volume savings, together with enhanced maintainability, are also foreseen in prospective developments of these subsystems.

Boyda, R. B.↗