Solution of systems of nonlinear equations Final report
Algorithm and computer program of diagonal discrimination method for computing nonlinear and transcendental functions
Law, V. J.↗
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Results for “Computer algorithms”
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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Computing polynomial resultants - Bezout's determinant vs. Collins' reduced P.R.S. algorithm.
Algorithms for polynominal resultants computation, considering extraneous factors, truncation errors, memory and computing speed
Adler, R. J.↗
Pseudoinversion for operator's defined on finite dimensional Hilbert spaces
Algorithm for computing pseudoinverse for any linear operator on Hilbert spaces
Engvall, J. L.↗
A pathfinding algorithm for an autonomous roving vehicle
Routing algorithm for computer controlled unmanned autonomous roving vehicle on Martian surface
Kirk, D. E.↗
Direct methods for the solution of systems of linear equations with sparse coefficient matrix and related topics Final report, 1 Dec. 1967 - 31 Aug. 1970
Deriving algorithms for computations involving sparse matrices
Tewarson, R. P.↗
A note on the automatic generation and recognition of textures
Discriminator algorithm for computer pattern generation and texture recognition
Flower, D. W.↗
A heuristic algorithm for the testing of asynchronous circuits
Heuristic algorithm for computation of failures detection tests in asynchronous sequential logic circuits
Putzolu, G. R.↗
Structural synthesis 1959-1969 - A decade of progress
Structural synthesis and analysis concepts, discussing design philosophy, failure modes, load conditions, algorithms and computer aided design
Schmit, L. A., Jr.↗
An empirical comparison of two sequential decoding algorithms
Fano and stack algorithms comparison by computer simulation of two sequential decoding algorithms
Geist, J. M.↗
Optimum impulsive midcourse guidance with control dependent errors.
The problem of determining the optimum guidance policy for an interplanetary spacecraft is treated as a stochastic optimal control problem. An algorithm for computing the optimum velocity correction and the optimum execution time (with allowance for correction-dependent errors) is derived in the case of a single midcourse correction. The performance index was chosen to be an upper bound for the probability that the mission fails, and it is defined as a function of the maximum allowable velocity correction and the maximum allowable deviation of the terminal state. Numerical results obtained for a Jupiter fly-by mission indicate that the execution errors have a significant influence on the performance index, but an acceptably small upper bound on the probability of mission failure can be obtained for sufficiently small execution errors.
Tapley, B. D.↗
Computer simulation for time optimal or energy optimal attitude control of spin-stabilized spacecraft.
An original technique for determining the optimal magnetic torque strategy for control of the attitude of spin stabilized spacecraft is presented. By employing Lagrange multipliers and the Calculus of Variations, optimal control equations are derived which define minimum time and minimum energy attitude maneuvers. Computer program algorithms to numerically solve these optimal control equations are also described. The performance of this technique is compared with a commonly employed planning method.
Woolley, R. D.↗
Application and sensitivity investigation of Fourier transforms for microwave radiometric inversions
Existing microwave radiometer technology now provides a suitable method for remote determination of the ocean surface's absolute brightness temperature. To extract the brightness temperature of the water from the antenna temperature equation, an unstable Fredholm integral equation of the first kind was solved. Fast Fourier Transform techniques were used to invert the integral after it is placed into a cross-correlation form. Application and verification of the methods to a two-dimensional modeling of a laboratory wave tank system were included. The instability of the Fredholm equation was then demonstrated and a restoration procedure was included which smooths the resulting oscillations. With the recent availability and advances of Fast Fourier Transform techniques, the method presented becomes very attractive in the evaluation of large quantities of data. Actual radiometric measurements of sea water are inverted using the restoration method, incorporating the advantages of the Fast Fourier Transform algorithm for computations.
Holmes, J. J.↗
Spline function approximation techniques for image geometric distortion representation
Least squares approximation techniques were developed for use in computer aided correction of spatial image distortions for registration of multitemporal remote sensor imagery. Polynomials were first used to define image distortion over the entire two dimensional image space. Spline functions were then investigated to determine if the combination of lower order polynomials could approximate a higher order distortion with less computational difficulty. Algorithms for generating approximating functions were developed and applied to the description of image distortion in aircraft multispectral scanner imagery. Other applications of the techniques were suggested for earth resources data processing areas other than geometric distortion representation.
Anuta, P. E.↗
An optimal control of a flexible spinning satellite
A modification of optimal spinning satellite control theory is proposed, based on introducing an additional vector into the equation for control torque components. This modification essentially means that the amplitudes of the time-dependent satellite perturbation functions can be made small when the amplitudes of the control torque components are allowed to be different. An algorithm for computer simulation of the satellite control theory is provided. A singular perturbation scheme is used which greatly reduces the number of degrees of freedom in the flexible satellite motion equations.
Das, A.↗
Precision Attitude Determination System (PADS) design and analysis. Two-axis gimbal star tracker
Development of the Precision Attitude Determination System (PADS) focused chiefly on the two-axis gimballed star tracker and electronics design improved from that of Precision Pointing Control System (PPCS), and application of the improved tracker for PADS at geosynchronous altitude. System design, system analysis, software design, and hardware design activities are reported. The system design encompasses the PADS configuration, system performance characteristics, component design summaries, and interface considerations. The PADS design and performance analysis includes error analysis, performance analysis via attitude determination simulation, and star tracker servo design analysis. The design of the star tracker and electronics are discussed. Sensor electronics schematics are included. A detailed characterization of the application software algorithms and computer requirements is provided.
Source record↗
A numerical comparison of discrete Kalman filtering algorithms: An orbit determination case study
The numerical stability and accuracy of various Kalman filter algorithms are thoroughly studied. Numerical results and conclusions are based on a realistic planetary approach orbit determination study. The case study results of this report highlight the numerical instability of the conventional and stabilized Kalman algorithms. Numerical errors associated with these algorithms can be so large as to obscure important mismodeling effects and thus give misleading estimates of filter accuracy. The positive result of this study is that the Bierman-Thornton U-D covariance factorization algorithm is computationally efficient, with CPU costs that differ negligibly from the conventional Kalman costs. In addition, accuracy of the U-D filter using single-precision arithmetic consistently matches the double-precision reference results. Numerical stability of the U-D filter is further demonstrated by its insensitivity of variations in the a priori statistics.
Thornton, C. L.↗
A very-long-baseline interferometer system for geodetic applications
A very-long-baseline interferometer system was designed and built for geodetic applications. Each interferometer terminal records a 360-kHz spectral band of noise from a compact extragalactic radio source. The center frequency of the spectral band can be selected to sample sequentially bands covering a much wider frequency range to obtain subnanosecond accuracy in group-delay measurements. A tunnel-diode pulse generator is used to calibrate the delays in the receiver. The necessary sets of algorithms and computer programs have been developed to analyze the data and have allowed the system to be employed to make accurate determinations of vector baselines, radio-source positions, polar motion, and universal time.
Whitney, A. R.↗
Table-aided design of the energy-storage reactor in dc-to-dc converters
A new procedure for the selection of magnetic cores for use in energy-storage dc-to-dc power converters which eliminates the need for an automated computer search algorithm and stored data file is presented. The converter configurations included in the procedure are the three commonly encountered single-winding converters for voltage step-up, for current step-up and for voltage step-up/current step-up, and for the two-winding converter for voltage step-up/current step-up. For each converter configuration, three types of controllers are considered - constant-frequency, constant on-time and constant off-time. Using concepts developed from analyses of these converters by considering the transfer of energy by means of an energy-storage inductor or transformer, a special table of parameters calculated from magnetic core data is constructed and leads to a considerably simplified design procedure.
Owen, H. A., Jr.↗