Development of a general formula expanding the higher-order derivatives of the function tanh z in powers of tanh z and A-numbers
Formula for expanding higher order derivatives of function tanh z in powers of tanh z and A-numbers
Hosenthien, H. H.↗
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Results for “generalized functions”
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Probe and radar electron temperatures in an isotropic nonequilibrium plasma.
Electron temperatures measured by electrostatic probes and radar backscatter are distinct physical quantities, the temperature from each technique determined from a different moment of the electron-distribution function. Numerical inequality of temperatures results from a non-Maxwellian electron-distribution function or, equivalently, from a nonequilibrium electron plasma. Probe and backscatter electron temperatures are studied for low- and high-energy (isotropic) distortions of the distribution function. The nonequilibrium plasma generally produces higher probe than backscatter temperatures; however, the temperature difference is small for distortions due to realistic photoelectron populations. If the ionosphere is in a highly nonequilibrium state, probe and backscatter temperatures would differ from the temperature characterizing the average electron kinetic energy, and a single temperature applicable to a variety of physical processes would no longer exist.
Hoegy, W. R.↗
Numerical methods for reduction of topside ionograms
Several alternative methods for solving the group height equation are presented. Three of these are now in operation at Ames Research Center and use data contained in a single ionogram trace. From the data an electron density profile N(h) is computed. If the ionogram also exhibits other traces, reverse ionogram traces are computed, using the N(h) profile, for comparison with the redundant data. When agreement is poor, the initial data trace is reinterpreted, another N(h) profile computed, and the reverse traces generated once again. This process is repeated until a desired degree of consistency is achieved. To reduce the necessity for human intervention and eliminate decision making required in conjunction with the preceding methods, a method is proposed that accepts as input, all data from a single ionogram. In general, no electron density function will satisfy these data exactly, but a best N(h) profile can be computed. Finally, a method is described that eliminates the need to assume that the ionosphere is spherically stratified. Horizontal gradients in electron density are detected and accounted for by processing several ionograms from the same satellite pass simultaneously. This idea is derived as an extension of one of the basic methods.
Mcculley, L.↗
Continuous dependence of fixed points of condensing maps
Many problems in analysis are concerned with the dependence upon parameters of fixed points of maps. For contraction mappings, criteria are relatively easy to obtain and have been known for some time. In the study of solutions of functional differential equations, more general results were needed. It is the purpose of this paper to give a rather general fixed-point theorem for condensing maps depending on a parameter, to prove continuous dependence and to indicate how many of the previous results are special cases.
Hale, J. K.↗
Theoretical autophotogrammetry. I - The method of the photometric potential
The present work presents preliminary efforts at a mathematical formulation of a photogrammetric method suitable for computerized processing. A theory is derived for the extraction of surface topography from stereometric pairs of photographs. The theory can be applied to either convergent or near-orthographic-projection stereo. Scene brightness is treated as a scalar function defined on a general surface embedded in ordinary three-dimensional space (the actual topography). Correspondence of points is based on adjustments leading to photometric equivalence, while the adjustments are based on the local value of the photometric gradient.
Wildey, R. L.↗
Wind tunnel investigation of a 14 foot vertical axis windmill
A full scale wind tunnel investigation was made to determine the performance characteristics of a 14 ft diameter vertical axis windmill. The parameters measured were wind velocity, shaft torque, shaft rotation rate, along with the drag and yawing moment. A velocity survey of the flow field downstream of the windmill was also made. The results of these tests along with some analytically predicted data are presented in the form of generalized data as a function of tip speed ratio.
Muraca, R. J.↗
A self-documenting source-independent data format for computer processing of tensor time series
The UCLA Space Science Group has developed a fixed format intermediate data set called a block data set, which is designed to hold multiple segments of multicomponent sampled data series. The format is sufficiently general so that tensor functions of one or more independent variables can be stored in the form of virtual data. This makes it possible for the unit data records of the block data set to be arrays of a single dependent variable rather than discrete samples. The format is self-documenting with parameter, label and header records completely characterizing the contents of the file. The block data set has been applied to the filing of satellite data (of ATS-6 among others).
Mcpherron, R. L.↗
A well posed boundary value problem in transonic gas dynamics
A boundary value problem for the Tricomi equation was studied in connection with transonic gas dynamics. The transformed equation delta u plus 1/3Y u sub Y equals 0 in canonical coordinates was considered in the complex domain of two independent complex variables. A boundary value problem was then set by prescribing the real part of the solution on the boundary of the real unit circle. The Dirichlet problem in the upper unit semicircle with vanishing values of the solution at Y = 0 was solved explicitly in terms of the hypergeometric function for the more general Euler-Poisson-Darboux equation. An explicit representation of the solution was also given for a mixed Dirichlet and Neumann problem for the same equation and domain.
Sanz, J. M.↗
Incremental exposure facilitates adaptation to sensory rearrangement
Visual-target pointing experiments were performed on 24 adult volunteers in order to compare the relative effectiveness of incremental (stepwise) and single-step exposure conditions on adaptation to visual rearrangement. The differences between the preexposure and postexposure scores served as an index of the adaptation elicited during the exposure period. It is found that both single-step and stepwise exposure to visual rearrangement elicit compensatory changes in sensorimotor coordination. However, stepwise exposure, when compared to single-step exposur in terms of the average magnitude of visual displacement over the exposure period, clearly enhances the rate of adaptation. It seems possible that the enhancement of adaptation to unusual patterns of sensory stimulation produced by incremental exposure reflects a general principle of sensorimotor function.
Lackner, J. R.↗
Effects of soil maturation on grain size-dependence of trapped solar gases
A description is presented of a simple two-part model which relates the retention of solar-wind-implanted noble gases and N in different grain sizes of lunar soils to the maturation level of that soil. It is assumed that concentrations of solar-wind gases are implanted into surfaces of soil grains in inverse proportion to grain diameter and that differences in irradiation probability and surface saturation as a function of grain diameter generally are not a major factor. The model demonstrates that incorporation of a major fraction of this surface-correlated gas into constructional particles such as agglutinates causes much of the gas to become volume-correlated in mature soils. This volume-correlated gas produces a relative enrichment in gas concentrations in coarser grains and a selective enrichment of more retentive gases (e.g., N) over less retentive gases (e.g., He). It is shown that the maturity model plays a major role in determining the complexities of the distribution of solar-wind gases in soils.
Bogard, D. D.↗
Time-domain Green's Function Method for three-dimensional nonlinear subsonic flows
The Green's Function Method for linearized 3D unsteady potential flow (embedded in the computer code SOUSSA P) is extended to include the time-domain analysis as well as the nonlinear term retained in the transonic small disturbance equation. The differential-delay equations in time, as obtained by applying the Green's Function Method (in a generalized sense) and the finite-element technique to the transonic equation, are solved directly in the time domain. Comparisons are made with both linearized frequency-domain calculations and existing nonlinear results.
Tseng, K.↗
Apodization and image contrast
Apodization is often defined in a restricted sense as the suppression of the outer parts (i.e., the concentric rings) of wave optical point images, which results in a higher relative concentration of energy in the central image area. In a wider sense, apodization is defined as any modification of the transmission distribution across the aperture. Generally the modulation transfer function (MTF) is not used in the treatment of apodization. To see how the imaging performance is modified, the MTF is introduced into the discussion. Besides the constant transmission, two transmission distributions which are functions of the aperture radius are considered.
Tschunko, H. F. A.↗
Data Base Management Systems Panel. Third workshop summary
The discussions and results of a review by a panel of data base management system (DRMS) experts of various aspects of the use of DBMSs within NASA/Office of Space and Terrestrial Applications (OSTA) and related organizations are summarized. The topics discussed included the present status of the use of DBMS technology and of the various ongoing DBMS-related efforts within NASA. The report drafts of a study that seeks to determine the functional requirements for a generalized DBMS for the NASA/OSTA and related data bases are examined. Future problems and possibilities with the use of DBMS technology are also considered. A list of recommendations for NASA/OSTA data systems is included.
Urena, J. L.↗
Aircrew-aircraft integration: A summary of US Army research programs and plans
A review of selected programs which illustrate the research efforts of the U.S. Army Aeromechanics Laboratory in the area of aircrew-aircraft integration is presented. Plans for research programs to support the development of future military rotorcraft are also described. The crew of a combat helicopter must, in general, perform two major functions during the conduct of a particular mission: flightpath control and mission management. Accordingly, the research programs described are being conducted in the same two major categories: (1) flightpath control, which encompasses the areas of handling qualities, stability and control, and displays for the pilot's control of the rotorcraft's flightpath, and (2) mission management, which includes human factors and cockpit integration research topics related to performance of navigation, communication, and aircraft systems management tasks.
Key, D. L.↗
Aircrew-aircraft integration - A summary of U.S. Army research programs and plans
A review of selected programs which illustrate the research efforts of the U.S. Army Aeromechanics Laboratory in the area of aircrew-aircraft integration is presented. Plans for research programs to support the development of future military rotorcraft are also described. The crew of a combat helicopter must, in general, perform two major functions during the conduct of a particular mission: flightpath control and mission management. Accordingly, the research programs described are being conducted in the same two major categories: (1) flightpath control, which encompasses the areas of handling qualities, stability and control, and displays for the pilot's control of the rotorcraft's flightpath, and (2) mission management, which includes human factors and cockpit integration research topics related to performance of navigation, communication, and aircraft systems management tasks.
Key, D. L.↗
Nonlinear rotordynamics analysis
Three analytic consequences of the nonlinear Jeffcott equations are examined. The primary application of these analyses is directed toward understanding the excessive vibrations recorded in the Liquid Oxygen (LOX) pump of the Space Shuttle Main Engine (SSME) during hot firing ground testing. The first task is to provide bounds on the coefficients of the equations which delimit the two cases of numerical solution as a circle or an annulus. The second task examines the mathematical generalization to multiple forcing functions, which includes the special problems of mass imbalance, side force, rubbing, and combination of these forces. Finally, stability and boundedness of the steady-state solutions is discussed and related to the corresponding linear problem.
Day, W. B.↗
Algorithms and programming tools for image processing on the MPP, part 2
A number of algorithms were developed for image warping and pyramid image filtering. Techniques were investigated for the parallel processing of a large number of independent irregular shaped regions on the MPP. In addition some utilities for dealing with very long vectors and for sorting were developed. Documentation pages for the algorithms which are available for distribution are given. The performance of the MPP for a number of basic data manipulations was determined. From these results it is possible to predict the efficiency of the MPP for a number of algorithms and applications. The Parallel Pascal development system, which is a portable programming environment for the MPP, was improved and better documentation including a tutorial was written. This environment allows programs for the MPP to be developed on any conventional computer system; it consists of a set of system programs and a library of general purpose Parallel Pascal functions. The algorithms were tested on the MPP and a presentation on the development system was made to the MPP users group. The UNIX version of the Parallel Pascal System was distributed to a number of new sites.
Reeves, Anthony P.↗
NASA Regional Planetary Image Facility image retrieval and processing system
The general design and analysis functions of the NASA Regional Planetary Image Facility (RPIF) image workstation prototype are described. The main functions of the MicroVAX II based workstation will be database searching, digital image retrieval, and image processing and display. The uses of the Transportable Applications Executive (TAE) in the system are described. File access and image processing programs use TAE tutor screens to receive parameters from the user and TAE subroutines are used to pass parameters to applications programs. Interface menus are also provided by TAE.
Slavney, Susan↗