Theory and performance of auxiliary discharge thermionic energy converters
Auxiliary discharge thermionic energy converter - gas discharge processes, and plasma parameters
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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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An Engineering Approach to Nonlinear Estimation
Linear analog operation followed by nonlinear digital signal processing for nonlinear parameter approximation
APPROXIMATION METHOD↗
Locations of solar radio bursts
Measurements of the positions of the sources of solar radio bursts at decameter wavelengths, 20- to 60-MHz range, provide information about physical conditions in a region of the corona extending from about one-half to several solar radii from the surface of the sun. Position measurements in the 20- to 60-MHz range were made with the Clark Lake sweep-frequency grating interferometer. Although the resolution of the instrument is sufficient to measure source position accurately, the highly variable effect of refraction in the earth's ionosphere severely limits the observations, distorting position determinations to such an extent as to make much of the position data useless unless ionospheric refraction can be taken into account. A method was developed for the removal of the refractive effect from the data to permit determination of true source position. With this technique it is considered possible to measure spatial extent of radio sources that will provide information about emission processes and physical parameters in the corona.
Fitzenreiter, R.↗
Progress and plans of a remote sensing program for the International Field Year for the Great Lakes (IFYGL)
The author has identified the following significant results. ERTS-1 coverage of the 32,000 square mile Lake Ontario Basin is being used to study short term and seasonal changes which affect many aspects of water problems in the Great Lakes. As part of the International Field Year for the Great Lakes (IFYGL), a coordinated, synoptic study of the Lake Ontario Basin, processed ERTS-1 imagery will contribute to the data base of synchronized observations being made by investigators from many U.S. and Canadian government agencies and universities. The first set of ERTS data has been received and will be processed shortly for parameters of hydrological and limnological significance such as land use, terrain features, and water quality. When complete, nine ERTS-1 frames recorded during a substantially clear period will provide coverage of the entire Basin. Seven frames show all but a small portion of the southern and eastern end of the Basin. Many drainage basin characteristics are clearly identifiable on the imagery.
Polcyn, F. C.↗
Development of a battery status monitor
A prototype battery status monitor system has been developed. The functions of the system are: (1) to provide the energy status of the battery, (2) to measure and transmit basic battery parameters, (3) to process these measurements required to determine abnormal functioning of the battery, and (4) to transmit warning signals of the abnormal condition along with a go/no go signal. The system was developed for use with the space shuttle.
Zimmerman, R. I.↗
Multispectral scanner data applications evaluation. Volume 1: User applications study
A six-month systems study of earth resource surveys from satellites was conducted and is reported. SKYLAB S-192 multispectral scanner (MSS) data were used as a baseline to aid in evaluating the characteristics of future systems using satellite MSS sensors. The study took the viewpoint that overall system (sensor and processing) characteristics and parameter values should be determined largely by user requirements for automatic information extraction performance in quasi-operational earth resources surveys, the other major factor being hardware limitations imposed by state-of-the-art technology and cost. The objective was to use actual aircraft and spacecraft MSS data to outline parametrically the trade-offs between user performance requirements and hardware performance and limitations so as to allow subsequent evaluation of compromises which must be made in deciding what system(s) to build.
Thomson, F. J.↗
Apollo Soyuz Test Project photographic processing control plan
The laboratory controls to be used within the photographic technology division (PTD) for processing original space flight films exposed on the Apollo Soyuz Test Project mission are specified. The sensitometric exposures to be used by PTD for certifying processes, for exposing Houston Controls, and for preflight and postflight exposures on original films as well as procedures for film certification are described. Processing conditions used to achieve each control and processing machine operating parameters are included.
Lockwood, H. E.↗
Sequential filtering applied to the determination of tracking station locations
The extended sequential filter has been applied to the problem of dynamically determining the geocentric coordinates of two laser satellite tracking stations. This filter provides significant advantages over the classical batch methods through (1) fewer iterations required for convergence, (2) wider radius of convergence, and (3) availability of the parameter estimate evolution. Processing the data sequentially readily identifies the data arcs required to minimize the effects of geopotential model errors. By means of the Smithsonian standard earth 2 and the Goddard earth model 1 geopotentials to reduce laser range observations of the Beacon Explorer-C satellite, it is demonstrated that a two-pass arc is optimal for estimating the height of one station and all coordinates of the second station while minimizing the effect of geopotential model error. These two-pass estimates are in good agreement with other determinations that utilize considerably more data as well as different satellites.
Schutz, B. E.↗
Stochastic simulation of vertically nonhomogeneous gusts
The small-scale horizontal gust structure of detailed wind profiles along the vertical in the first 20 km of the atmosphere is a vertically nonhomogeneous process. A linear stochastic model is developed for the process based on the process covariance function. This model is formulated through the use of a scaling hypothesis that transforms the nonhomogeneous gust process into a nondimensional gust process which is homogeneous in a nondimensional height coordinate. The velocity scaling parameter for the gust process is the gust standard deviation, and the length scale used to nondimensionalize the altitude is the vertical space lag associated with the first zero of the gust covariance function. State space theory is used to derive a digital filter from the model, which can be readily used to simulate gusts for space vehicle design applications.
Fichtl, G. H.↗
A thematic mapper performance optimization study
A six-month systems study of earth resource surveys from satellites was conducted in early 1974. Skylab S-192 Multispectral Scanner (MSS) data were used as a baseline to aid in evaluating the characteristics of future systems using satellite MSS sensors. The study took the viewpoint that overall system (sensor and processing) characteristics and parameter values should be determined largely by user requirements for automatic information extraction performance in quasi-operational earth resources surveys, the other major factor being hardware limitations imposed by state-of-the-art technology and cost.
Thomson, F. J.↗
Definition and fabrication of an airborne scatterometer radar signal processor
A hardware/software system which incorporates a microprocessor design and software for the calculation of normalized radar cross section in real time was developed. Interface is provided to decommutate the NASA ADAS data stream for aircraft parameters used in processing and to provide output in the form of strip chart and pcm compatible data recording.
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A model of the 0.4-GHz scatterometer
The 0.4 GHz aircraft scatterometer system used for the agricultural soil moisture estimation program is analyzed for the antenna pattern, the signal flow in the receiver data channels, and the errors in the signal outputs. The operational principal, system sensitivity, data handling, and resolution cell length requirements are also described. The backscattering characteristics of the agriculture scenes are contained in the form of the functional dependence of the backscattering coefficient on the incidence angle. The substantial gains of the cross-polarization term of the horizontal and vertical antennas have profound effects on the cross-polarized backscattered signals. If these signals are not corrected properly, large errors could result in the estimate of the cross-polarized backscattering coefficient. It is also necessary to correct the variations of the aircraft parameters during data processing to minimize the error in the 0 degree estimation. Recommendations are made to improve the overall performance of the scatterometer system.
Wu, S. T.↗
A scene-analysis approach to remote sensing
The author has identified the following significant results. Geometric correspondance between a sensed image and a symbolic map is established in an initial stage of processing by adjusting parameters of a sensed model so that the image features predicted from the map optimally match corresponding features extracted from the sensed image. Information in the map is then used to constrain where to look in an image, what to look for, and how to interpret what is seen. For simple monitoring tasks involving multispectral classification, these constraints significantly reduce computation, simplify interpretation, and improve the utility of the resulting information. Previously intractable tasks requiring spatial and textural analysis may become straightforward in the context established by the map knowledge. The use of map-guided image analysis in monitoring the volume of water in a reservoir, the number of boxcars in a railyard, and the number of ships in a harbor is demonstrated.
Tenenbaum, J. M.↗
Parametric study of two planar high power flexible solar array concepts
The design parameters examined were: frequency, aspect ratio, packaging constraints, and array blanket flatness. Specific power-to-mass ratios for both solar arrays as a function of array frequency and array width were developed and plotted. Summaries of the baseline design data, developed equations, the computer program operation, plots of the parameters, and the process for using the information as a design manual are presented.
Garba, J. A.↗
Map-guided interpretation of remotely-sensed imagery
A map-guided approach to interpretation of remotely sensed imagery is described, with emphasis on applications involving continuous monitoring of predetermined ground sites. Geometric correspondence between a sensed image and a symbolic reference map is established in an initial stage of processing by adjusting parameters of a sensor model so that image features predicted from the map optimally match corresponding features extracted from the sensed image. Information in the map is then used to constrain where to look in an image and what to look for. With such constraints, previously intractable remote sensing tasks can become feasible, even easy, to automate. Four illustrative examples are given, involving the monitoring of reservoirs, roads, railroad yards, and harbors.
Tenenbaum, J. M.↗
Rime ice accretion and its effect on airfoil performance
A methodology was developed to predict the growth of rime ice, and the resulting aerodynamic penalty on unprotected, subcritical, airfoil surfaces. The system of equations governing the trajectory of a water droplet in the airfoil flowfield is developed and a numerical solution is obtained to predict the mass flux of super cooled water droplets freezing on impact. A rime ice shape is predicted. The effect of time on the ice growth is modeled by a time-stepping procedure where the flowfield and droplet mass flux are updated periodically through the ice accretion process. Two similarity parameters, the trajectory similarity parameter and accumulation parameter, are found to govern the accretion of rime ice. In addition, an analytical solution is presented for Langmuir's classical modified inertia parameter. The aerodynamic evaluation of the effect of the ice accretion on airfoil performance is determined using an existing airfoil analysis code with empirical corrections. The change in maximum lift coefficient is found from an analysis of the new iced airfoil shape. The drag correction needed due to the severe surface roughness is formulated from existing iced airfoil and rough airfoil data. A small scale wind tunnel test was conducted to determine the change in airfoil performance due to a simulated rime ice shape.
Bragg, M. B.↗
Accuracy of vertical velocity determination
Typical wind spectra taken at Poker Flat, Alaska, using the vertically oriented antenna show velocities of 10's of cm to meters per second and spectral widths winds of 0.5 to 1 m/s. The potential errors in such measurements can be broken down into three categories: (1) those due to instrumental parameters and data processing, (2) those due to specular returns from non-horizontal surfaces, and (3) those due to other physical effects. Error analysis in vertical velocity measurement is further discussed.
Riddle, A. C.↗
Executive Summary: Background
Background information on, and the objectives of, the NASA Global Biology Research Program are given. The following issues were addressed: (1) geographic distribution of wetland parameters, (2) the processes of wetland material fluxes, and (3) the relation of local fluxes with global processes. Wetland inventorying and categorizing, gas-phase exchanges with the atmosphere, material exchange with the aquatic environment, and material storage in wetland sediments were identified as topics requiring further research.
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