Digital compensation of the thrust vector control system Technical report, 28 May 1966 - 28 Sep. 1966
Sampled data control, quantization effects, and transfer function for Saturn 5 thrust vector control
Phillips, C. L.↗
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Nth order redundancy reduction.
Curve fitting for optimum redundance reduction on sampled data, describing polygonal and approximate polygonal techniques
Wilkins, L. C.↗
Flexible format generator design techniques.
Flexible format generator for manned spacecraft data management system designed with memory for data sampling formats, emphasizing software counters and power strobing
Rathbone, W. M.↗
Dual-rate finite-settling-time discrete systems
Finite settling time for feedback control systems using dual rate, sampled data control algorithm
Gatlin, J. A.↗
Synthesis of multistage triggers
Design of multistage triggers for digital computers and sampled-data control systems
Zibin, D. K.↗
Design of finite settling time discrete systems
Finite settling response for single input/output feedback control system obtained by dual rate sampled data control algorithm
Gatlin, J. A.↗
On an extension of Mullin and Jury's method
Actuating signal at sampling instants determined in phase plane by Mullin-Jury method for sampled data feedback containing quantizer and zero order hold circuit
Klepl, M. J.↗
Simulation studies related to GARP
Simulation studies for first GARP global experiment, discussing data redundancy, measured and derived data, sampling, etc
Halem, M.↗
The versatile information processor - A unique concept for an adaptable satellite telemetry system
Nimbus 4 satellite telemetry information processor with data sampling and formatting flexibility
Feinberg, P.↗
Identification of human operator models by stochastic approximation
Human operator models parameter estimation by stochastic approximation, considering continuous and sampled data models
Bekey, G. A.↗
Users manual for the Variable dimension Automatic Synthesis Program (VASP)
A dictionary and some problems for the Variable Automatic Synthesis Program VASP are submitted. The dictionary contains a description of each subroutine and instructions on its use. The example problems give the user a better perspective on the use of VASP for solving problems in modern control theory. These example problems include dynamic response, optimal control gain, solution of the sampled data matrix Ricatti equation, matrix decomposition, and pseudo inverse of a matrix. Listings of all subroutines are also included. The VASP program has been adapted to run in the conversational mode on the Ames 360/67 computer.
White, J. S.↗
Results of scatterometer systems analysis for NASA/MSC Earth observation sensor evaluation program
A systems evaluation of the 13.3 GHz scatterometer system is presented. The effects of phase error between the scatterometer channels, antenna pattern deviations, aircraft attitude deviations, environmental changes, and other related factors such as processing errors, system repeatability, and propeller modulation, are established. Furthermore, the reduction in system errors and calibration improvement is investigated by taking into account these parameter deviations. Typical scatterometer data samples are presented.
Krishen, K.↗
Some analyses of the variability of atmospheric parameters at low altitudes significant for aircraft propagation
The results are discussed in terms of the meteorological data acquisition procedures necessary to monitor changes in atmospheric parameters to support aircraft flyover noise measurements and aircraft noise certification programs. The data consisted primarily of sequential radiosonde ascents to approximately 5000 ft spaced some half-hour to an hour apart. The weather covered by the data sample was predominantly that of clear skies and calm-to-light surface winds associated with well established high-pressure systems. Under these restrictive weather conditions, the study shows that the largest variabilities in temperature and humidity occur during the early morning hours resulting from the effects of direct solar heating of the surface. These rapid changes apparently do not penetrate above approximately 1000 ft. In the late morning hours, the atmosphere appears to become stabilized so that net changes in temperatures and relative humidities at all levels are insignificant even in time periods exceeding three hours. By noon, however, turbulent fluctuations in surface wind and the wind speed itself increase to levels which would make the microphone recording of acoustic signals in the field difficult.
Chang, D. T.↗
Boundedness regions of discrete-time dynamic systems
Techniques for obtaining quantitative information about boundedness properties are developed and applied to the sampled-data control of satellite attitude with quantization. Relevant stability concepts are introduced as a series of definitions, and interrelationships between various definitions are discussed. The boundedness regions are estimated by means of quadratic Liapunov functions, and a sufficient condition for the existence of a boundedness region is given for a certain class of systems. A quadratic Liapunov function is applied to the Lur'e-Postinkov class of systems, where the linear part of the system is not asymptotically stable and the quantizer represents the nonlinear characteristic. A numerical calculation of the region of boundedness estimates is performed for satellite attitude control and is compared with simulation results. It is tentatively concluded that the Liapunov results may be good and that simulation results may be difficult to interpret and time-consuming to generate. The Lur'e-based technique yields estimates of regions of absolute boundedness, but at the cost of greater analytical complexity.
Siljak, D.↗
Optimum runway orientation relative to crosswinds
Specific magnitudes of crosswinds may exist that could be constraints to the success of an aircraft mission such as the landing of the proposed space shuttle. A method is required to determine the orientation or azimuth of the proposed runway which will minimize the probability of certain critical crosswinds. Two procedures for obtaining the optimum runway orientation relative to minimizing a specified crosswind speed are described and illustrated with examples. The empirical procedure requires only hand calculations on an ordinary wind rose. The theoretical method utilizes wind statistics computed after the bivariate normal elliptical distribution is applied to a data sample of component winds. This method requires only the assumption that the wind components are bivariate normally distributed. This assumption seems to be reasonable. Studies are currently in progress for testing wind components for bivariate normality for various stations. The close agreement between the theoretical and empirical results for the example chosen substantiates the bivariate normal assumption.
Falls, L. W.↗
Transition region response of the symmetric double probe and its application in the lower ionosphere
The technique is discussed of the symmetric double-probe which readily lends itself to the in situ measurement of plasma temperature in the ionospheric D-region because it can lead to meaningful results under relatively high collision frequencies where the Langmuir probe has been observed to fail. It is shown that the modification to the original collision-free double-probe theory of Johnson and Malter for the determination of electron temperature is never greater than + or - 12%, with a value of (8 + or - 2)% nominally applicable in the case of D-region diagnostics. This technique was successfully operated on a Nike-Cajun payload flown at mid-day from White Sands, New Mexico to an apogee of 78.5 km. The associated electronics and deployed double-probe configuration are presented, and a current-voltage characteristic collected in the ascent stage at 73.7 km is briefly discussed. The values of electron temperature indicated by the sampled data are approximately 30% higher than those predicted by theory for the anticipated state of thermal equilibrium with the ambient neutrals.
Szuszczewicz, E. P.↗
Results of scatterometer systems analysis for NASA/MSC Earth Observation Sensor Evaluation Program.
Radar scatterometers have applications in the NASA/MSC Earth Observation Aircraft Program. Over a period of several years, several missions have been flown over both land and ocean. In this paper a system evaluation of the NASA/MSC 13.3-GHz Scatterometer System is presented. The effects of phase error between the Scatterometer channels, antenna pattern deviations, aircraft attitude deviations, environmental changes, and other related factors such as processing errors, system repeatability, and propeller modulation, were established. Furthermore, the reduction in system errors and calibration improvement was investigated by taking into account these parameter deviations. Typical scatterometer data samples are presented.
Krishen, K.↗
A method of computing periods of cyclic phenomena.
Use of an analysis of Expected Mean Square Deviations to search for periodicities in an observational data sample is described. The statistic for testing the null hypothesis of nonperiodicity is derived from a partitioning of the total sum of squared deviations from the mean. Unlike most existing methods, the present one does not require equally spaced observations. No assumptions are made concerning the statistical nature of spacing intervals. The method is illustrated by numerical examples.
Jurkevich, I.↗