298
298

Jun 20, 2010
06/10

by
Benedict, A. G

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Small-sample evaluation of squib time-current firing characteristics

Topics: DATA SAMPLING, SQUIBS, TEMPLATES, TESTS, TIME DEPENDENCE, FIRING, SAMPLED DATA, SQUIB

Generator measures period between zero crossings of reference signal and accepts as correct timing points only those zero crossings which occur acceptably close to nominal time predicted from last accepted command. Unidirectional crossover points are used exclusively so errors from analog nonsymmetry of crossover detector are avoided.

Topics: NASA Technical Reports Server (NTRS), DATA RECORDING, DATA SAMPLING, ELECTROMAGNETIC NOISE,...

600
600

Jun 21, 2010
06/10

by
Britting, K. R

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Error analysis of strapdown and local level inertial navigation systems which compute in geographic coordinates

Topics: DATA SAMPLING, EYE MOVEMENTS, STOCHASTIC PROCESSES, TRACKING (POSITION), AUTOMATIC CONTROL,...

Asteroid families are clusters of asteroids in proper element space which are thought to be fragments from former collisions. Studies of families promise to improve understanding of large collision events and a large event can open up the interior of a former parent body to view. While a variety of searches for families have found the same heavily populated families, and some searches have found the same families of lower population, there is much apparent disagreement between proposed families...

Topics: NASA Technical Reports Server (NTRS), ASTEROIDS, DATA SAMPLING, RELIABILITY, IMPACT, POPULATIONS,...

391
391

Jul 5, 2010
07/10

by
Allen, E. C

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Experimental aerodynamic investigations were made in the NASA/MSFC 14 x 14 inch trisonic wind tunnel on a NR-GD/C 0.0031 scale model delta wing booster (B-15B-1) and reusable nuclear stage (RNS). Three basic configurations were tested: (1) the B-15B-1 booster alone, (2) the RNS alone, and (3) the booster with the RNS mounted piggyback. Six component force and moment data were recorded for each of these configurations over an angle of attack range from -16 deg to 4 deg at zero degrees sideslip,...

Topics: COMPUTER PROGRAMS, CONTROL THEORY, INSTRUCTION SETS (COMPUTERS), MANUALS, SUBROUTINE LIBRARIES...

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290

May 21, 2011
05/11

by
Philippe, Pacholczy

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SPOT sun-synchronous remote sensing satellites are operated by CNES since February 1986. Today, the SPOT mission and control center (CCM) operates SPOT1, SPOT2, and is ready to operate SPOT3. During these seven years, the way to operate changed and the CCM, initially designed for the control of one satellite, has been modified and upgraded to support these new operating modes. All these events have shown the performances and the limits of the system. A new generation of satellite (SPOT4) will...

Topics: DATA SAMPLING, STATISTICAL ANALYSIS, DATA STRUCTURES, HIERARCHIES, IMAGE PROCESSING, QUADRANTS,...

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379

Jul 26, 2010
07/10

by
Preiss, Kirk A.; Dunnam, Joan B

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No Abstract Available

Topics: FRANCE, MOISTURE CONTENT, REMOTE SENSING, SOIL MAPPING, SOIL MOISTURE, SURFACE TEMPERATURE, DATA...

Systems and methods for self-synchronized data sampling are provided. In one embodiment, a system for capturing synchronous data samples is provided. The system includes an analog to digital converter adapted to capture signals from one or more sensors and convert the signals into a stream of digital data samples at a sampling frequency determined by a sampling control signal; and a synchronizer coupled to the analog to digital converter and adapted to receive a rotational frequency signal from...

Topics: NASA Technical Reports Server (NTRS), DATA SAMPLING, SYNCHRONISM, PULSE COMMUNICATION, PATENTS,...

278
278

Jul 11, 2010
07/10

by
Wilner, D. O

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A remote multiplexer/digitizer unit (RMDU), a part of the airborne integrated flight test data system, was subjected to an accuracy study. The study was designed to show the effects of temperature, altitude, and vibration on the RMDU. The RMDU was subjected to tests at temperatures from -54 C (-65 F) to 71 C (160 F), and the resulting data are presented here, along with a complete analysis of the effects. The methods and means used for obtaining correctable data and correcting the data are also...

Topics: OPTIMIZATION, RADIO ASTRONOMY, SIGNAL TO NOISE RATIOS, SINE WAVES, DATA SAMPLING, FOURIER SERIES,...

Suitability of ERTS-1 data as tool for managing wildlife habitat of Yukon-Kuskokwim Delta

Topics: NASA Technical Reports Server (NTRS), ALASKA, HABITATS, RESOURCES MANAGEMENT, WILDLIFE, DATA...

Determining the distribution of statistics by sampling was investigated. Characteristic functions, the quadratic regression problem, and the differential equations for the characteristic functions are analyzed.

Topics: NASA Technical Reports Server (NTRS), DATA SAMPLING, STATISTICAL DISTRIBUTIONS, DIFFERENTIAL...

The state of the art and anticipated requirements for resampling in applications of remote sensing are examined. It is noted that the wide range of potential applications and expanded needs for resampling versatility in new imaging sensors leads to a concern for creating standardized test data sets and ground training sites. Several research areas are defined including the development of (1) a theory for defining an input psf of an instrument such that upon resampling of the processed data into...

Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, DATA SAMPLING, DIGITAL FILTERS, IMAGE PROCESSING,...

A comprehensive sampled data analysis of a computer-controlled manipulator is presented in terms of root loci for gain selection and transient responses to step input functions. All parameter values and their derivations where applicable were tabulated. The analysis, while quite specific, uses normalized gain parameters, which allows the results to be applied to any similar system regardless of individual hardware parameter values.

Topics: NASA Technical Reports Server (NTRS), AIRCRAFT STABILITY, DATA SAMPLING, MANIPULATORS, DATA...

System synchronizes data transfer between two computers by generating data strobe pulses when computers are ready for data transfer. In addition, interface filters noise by sampling.

Topics: NASA Technical Reports Server (NTRS), COMPUTER DESIGN, DATA PROCESSING EQUIPMENT, DATA SAMPLING,...

The International Satellite Cloud Climatology Project (ISCCP) is the first active project of the World Climate Research Program. It is a multinational data collection project focused on collecting a data set that will improve the ability to predict and/or simulate the radiative effects of clouds on climate. For specified cloud parameters, the goals are to archieve values for 3-hour periods over the whole globe for 5 years at 30 km resolution. The task of collecting and processing radiance data...

Topics: NASA Technical Reports Server (NTRS), CLIMATE, CLOUDS (METEOROLOGY), DATA BASES, DATA SYSTEMS,...

The frequency response method of analyzing control system performance is discussed, and the difficulty of obtaining the sampled frequency response of the continuous system is considered. An upper bound magnitude error equation is obtained which yields reasonable estimates of the actual error. Finalization of the compensator improvement program is also reported, and the program was used to design compensators for Saturn 5/S1-C dry workshop and Saturn 5/S1-C Skylab.

Topics: NASA Technical Reports Server (NTRS), COMPUTER PROGRAMMING, CONTROL, DATA SAMPLING, FREQUENCY...

178
178

May 31, 2011
05/11

by
Goetz, Alexander F

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The High Plains is an economically important and climatologically sensitive region of the United States and Canada. The High Plains contain 100,000 sq km of Holocene sand dunes and sand sheets that are currently stabilized by natural vegetation. Droughts and the larger threat of global warming are climate phenomena that could cause depletion of natural vegetation and make this region susceptible to sand dune reactivation. The original proposal was directed toward the use of Landsat TM data to...

Topics: TIME SERIES ANALYSIS, DATA SAMPLING, OCEANOGRAPHY, WATER COLOR, DATA ACQUISITION, OCEAN DATA...

Procedures to evaluate the accuracy of LANDSAT derived wildland cover classifications are described. The evaluation procedures include: (1) implementing a stratified random sample for obtaining unbiased verification data; (2) performing area by area comparisons between verification and LANDSAT data for both heterogeneous and homogeneous fields; (3) providing overall and individual classification accuracies with confidence limits; (4) displaying results within contingency tables for analysis of...

Topics: NASA Technical Reports Server (NTRS), CLASSIFICATIONS, LAND USE, MAPS, PATTERN REGISTRATION,...

A FORTRAN digital computer program which performs the general analysis of linearized control systems is described. State variable techniques are used to analyze continuous, discrete, and sampled data systems. Analysis options include the calculation of system eigenvalues, transfer functions, root loci, root contours, frequency responses, power spectra, and transient responses for open- and closed-loop systems. A flexible data input format allows the user to define systems in a variety of...

Topics: NASA Technical Reports Server (NTRS), DATA PROCESSING, FORTRAN, LINEAR PROGRAMMING, COMPUTER...

Theory deficiencies, data, and potential computational procedures that make the physical determination of the ocean geoid with true scale, shape, and absolute orientation of an elusive target are outlined. Satellite altimetry potential, in combination with adequate ground support and sea truth to resolve accurate global marine geoid and other peripheral benefits associated with ocean physics, are stated. Results are given in tabular form.

Topics: NASA Technical Reports Server (NTRS), ALTIMETERS, GEODETIC SURVEYS, GEOIDS, OCEANOGRAPHY, SATELLITE...

Current adaptive sampling schemes that can be used in sampled-data systems with variable rate sampling does not guarantee the stability of the resulting closed-loop system. A study was undertaken with the objective of finding a stable control law for multirate sampled-data systems. The problem is formulated such that the sampling interval is selected from a set of fixed number of sample intervals. A necessary and sufficient condition under which these types of systems can be stabilized is...

Topics: NASA Technical Reports Server (NTRS), CONTROL THEORY, DATA SAMPLING, FEEDBACK CONTROL, ALGORITHMS,...

Development of quadtree as hierarchical data structuring technique for representing spatial data (like points, regions, surfaces, lines, curves, volumes, etc.) has been motivated to a large extent by storage requirements of images, maps, and other multidimensional (spatially structured) data. For many spatial algorithms, time-efficiency of quadtrees in terms of execution may be as important as their space-efficiency concerning storage conditions. Briefly, the quadtree is a class of hierarchical...

Topics: NASA Technical Reports Server (NTRS), DATA SAMPLING, DATA STRUCTURES, HIERARCHIES, IMAGE...

The Generalized Fluid System Simulation Program (GFSSP) is a finite-volume based general-purpose computer program for analyzing steady state and time-dependent flow rates, pressures, temperatures, and concentrations in a complex flow network. The program is capable of modeling real fluids with phase changes, compressibility, mixture thermodynamics, conjugate heat transfer between solid and fluid, fluid transients, pumps, compressors and external body forces such as gravity and centrifugal. The...

Topics: NASA Technical Reports Server (NTRS), FINITE VOLUME METHOD, HEAT TRANSFER, DATA, DATA SAMPLING,...

Studies are summarized on the application of advanced analytical and computational methods to the development of mathematical models of human controllers in multiaxis manual control systems. Specific accomplishments include the following: (1) The development of analytical and computer methods for the measurement of random parameters in linear models of human operators. (2) Discrete models of human operator behavior in a multiple display situation were developed. (3) Sensitivity techniques were...

Topics: NASA Technical Reports Server (NTRS), MANUAL CONTROL, MATHEMATICAL MODELS, OPERATOR PERFORMANCE,...

The utilization of minimum distance classification methods in remote sensing problems, such as crop species identification, is considered. Literature concerning both minimum distance classification problems and distance measures is reviewed. Experimental results are presented for several examples. The objective of these examples is to: (a) compare the sample classification accuracy of a minimum distance classifier, with the vector classification accuracy of a maximum likelihood classifier, and...

Topics: NASA Technical Reports Server (NTRS), CLASSIFIERS, CROP IDENTIFICATION, DATA SAMPLING, PERFORMANCE,...

A new algorithm for calculating H (sup infinity) optimal controllers is investigated. The algorithm is significantly simpler than existing approaches and yields much simpler controllers. The design equations are first presented. Special system transformations required to apply the algorithm are then presented. The use of the algorithm with sampled-data systems is outlined in detail. Several constraints on the characteristics of the problem formulation are required for the application of the...

Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, CONTROLLERS, OPTIMAL CONTROL, STRATEGY, TRACKING...

The author has identified the following significant results. Practical use of recognition results of LANDSAT data as the base map of the field survey or the retouching work of vegetation and land use has the effective benefit to cut down the cost, labor, and time lower than 10% of a conventional method. Correct and detailed vegetation maps were prepared using combined interpretation of repetition of data of different seasons at warm and temperate forested areas.

Topics: NASA Technical Reports Server (NTRS), DATA SAMPLING, ECOLOGY, FORESTS, JAPAN, VEGETATION, EARTH...

A vectorized rebinning (down-sampling) algorithm, applicable to N-dimensional data sets, has been developed that offers a significant reduction in computer run time when compared to conventional rebinning algorithms. For clarity, a two-dimensional version of the algorithm is discussed to illustrate some specific details of the algorithm content, and using the language of image processing, 2D data will be referred to as "images," and each value in an image as a "pixel." The...

Topics: NASA Technical Reports Server (NTRS), ALGORITHMS, DATA SAMPLING, SAMPLING, SIGNAL PROCESSING, DATA...

The specific objectives of the FY 1980-81 tasks are: (1) further refinements to the weighted aggregation procedure; (2) improved approaches for estimating within-stratum variance; (3) more intensive investigation of alternative sampling strategies such as full-frame sampling strategy, and (4) further developments in regard to a simulated approach for assessing the performance of the overall designed sampling and aggregation system.

Topics: NASA Technical Reports Server (NTRS), CLASSIFICATIONS, CROP INVENTORIES, DATA SAMPLING,...

Research studies of residents' responses to noise consist of interviews with samples of individuals who are drawn from a number of different compact study areas. The statistical techniques developed provide a basis for those sample design decisions. These techniques are suitable for a wide range of sample survey applications. A sample may consist of a random sample of residents selected from a sample of compact study areas, or in a more complex design, of a sample of residents selected from a...

Topics: NASA Technical Reports Server (NTRS), NOISE POLLUTION, RANDOM PROCESSES, REGRESSION ANALYSIS,...

Engine-order sampling was used to eliminate the integral harmonics from the flutter spectra corresponding to a case-mounted static pressure transducer. Using the optical displacement data, it was demonstrated that the blade-order sampling of pressure data may yield erroneous results due to the interference caused by blade vibration. Two methods are presented which effectively eliminate this interference yielding the blade-pressure-difference spectra. The phase difference between the...

Topics: NASA Technical Reports Server (NTRS), FLUTTER, PRESSURE SENSORS, ROTOR BLADES (TURBOMACHINERY),...

A sequential adaptive experimental design procedure for a related problem is studied. It is assumed that a finite set of potential linear models relating certain controlled variables to an observed variable is postulated, and that exactly one of these models is correct. The problem is to sequentially design most informative experiments so that the correct model equation can be determined with as little experimentation as possible. Discussion includes: structure of the linear models;...

Topics: NASA Technical Reports Server (NTRS), EXPERIMENT DESIGN, INFORMATION THEORY, PROBABILITY THEORY,...

46
46

Jan 4, 2020
01/20

by
Franklin, Gene F

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xxi, 837 pages : 24 cm

Topics: Dynamique, Commande, théorie de la, Dynamics, Digital control systems, Dynamisches System,...

The current state of minor planet ephemerides was assessed, and the means for providing and updating these emphemerides for use by both the mission planner and the astronomer were developed. A system of obtaining data for all the numbered minor planets was planned, and computer programs for its initial mechanization were developed. The computer based system furnishes the osculating elements for all of the numbered minor planets at an adopted date of October 10, 1972, and at every 400 day...

Topics: NASA Technical Reports Server (NTRS), COMPUTER SYSTEMS DESIGN, DATA SYSTEMS, PLANET EPHEMERIDES,...

Method is described for reduction of error components in numerical integration, sampling with zero hold order, and execution time delay.

Topics: NASA Technical Reports Server (NTRS), DATA SAMPLING, ERROR ANALYSIS, ERROR FUNCTIONS, HYBRID...

No abstract available

Topics: NASA Technical Reports Server (NTRS), SAMPLES, BIOMEDICAL DATA, AEROSPACE MEDICINE, STATISTICAL...

Problems associated with using an altimetry sampling function approach to the geoid are examined. They include: (1) conventent mathematical representation of short-wavelength (eventually approximately 1 deg) features of the geoid or geopotential, (2) utilization of detailed data from only part of the globe (i.e., the oceans) (3) application of appropriate formalism to relate the sea-level equipotential below the atmospheric mass to the external potential above the atmosphere, (4) mathematical...

Topics: NASA Technical Reports Server (NTRS), ALTIMETERS, ALTITUDE, DATA SAMPLING, FUNCTIONAL INTEGRATION,...

The determination of an error criterion which will give a sampling rate for adequate performance of linear, time-invariant closed-loop, discrete-data control systems was studied. The proper modelling of the closed-loop control system for characterization of the error behavior, and the determination of an absolute error definition for performance of the two commonly used holding devices are discussed. The definition of an adequate relative error criterion as a function of the sampling rate and...

Topics: NASA Technical Reports Server (NTRS), COMPUTER SYSTEMS DESIGN, DATA SAMPLING, ERROR ANALYSIS,...

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226

May 23, 2011
05/11

by
Landers, Stephen F.; Saltzman, John A.; Bjarke, Lisa J

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Chordwise pressure distributions were obtained in-flight on the upper and lower surfaces of the F-16XL ship 2 aircraft wing between Mach 1.4 and Mach 2.0. This experiment was conducted to determine the location of shock waves which could compromise or invalidate a follow-on test of a large chord laminar flow control suction panel. On the upper surface, the canopy closure shock crossed an area which would be covered by a proposed laminar flow suction panel. At the laminar flow experiment design...

Topics: ACCELEROMETERS, FOURIER TRANSFORMATION, INTERNETS, SPECTROGRAMS, HISTOGRAMS, TIME SERIES ANALYSIS,...

Weighting is employed in synthetic aperture radar (SAR) processing to reduce the sidelobe response at the expense of peak center response height and mainlobe resolution. The weighting effectiveness in digital processing depends not only on the choice of weighting function, but on the fineness of sampling and quantization, on the time bandwidth product, on the quadratic phase error, and on the azimuth antenna pattern. The results of simulations conducted to uncover the effect of these parameters...

Topics: NASA Technical Reports Server (NTRS), DATA PROCESSING, DIGITAL TECHNIQUES, SYNTHETIC APERTURE...

Technical progress made in the foreign commodity production forecasting for the advancement of spring small grains (SSG) area estimation is reported with emphasis on results achieved since the last AgRISTARS level semiannual review. Major objectives and accomplishments are reviewed and the experiment is described. The technical approach data assessment, and data systems used are considered. Results of the group approach comparison study are presented along with preliminary aggregation results...

Topics: NASA Technical Reports Server (NTRS), CLASSIFICATIONS, CROP INVENTORIES, DATA PROCESSING, GRAINS...

End-to-end root-mean-square (rms) tests performed on a constant bandwidth FM/FM system with various settings of system parameters are reported. The testing technique employed is that of sampling, digitizing, delaying, and comparing the analog input against the sampled and digitized corresponding output. Total system error is determined by fully loading all channels with band-limited noise and conducting end-to-end rms error tests on one channel. Tests are also conducted with and without a...

Topics: NASA Technical Reports Server (NTRS), ERROR ANALYSIS, PERFORMANCE TESTS, ROOT-MEAN-SQUARE ERRORS,...

An electronic filter comprised of three active filter sections to smooth the stepped signal from a digital to analog converter is described. The first section has a noninverting low pass filter transfer function, and the second has an inverting transfer function designed to pass a narrow frequency band centered at the step frequency of the stepped output signal with sharp cutoff of either side of that narrow band. The third section adds the noninverted output of the first section to the...

Topics: NASA Technical Reports Server (NTRS), BANDPASS FILTERS, DATA SMOOTHING, DIGITAL TO ANALOG...

Recent tests using the Common Research Model (CRM) at the Langley National Transonic Facility (NTF) and the Ames 11-foot Transonic Wind Tunnel (11' TWT) produced large sets of data that have been used to examine the effects of active damping on transonic tunnel aerodynamic data quality. In particular, large statistically significant sets of repeat data demonstrate that the active damping system had no apparent effect on drag, lift and pitching moment repeatability during warm testing...

Topics: NASA Technical Reports Server (NTRS), ACTIVE CONTROL, DAMPING, HIGH REYNOLDS NUMBER, PITCHING...

Previous work in the development of quantitative models for the prediction of passenger reaction to motion and vehicle environment parameters in flight was extended to include a class of aircraft appropriate for low-density, short-haul service. The results indicate that it is possible to obtain quantitative response inputs from an usually small special test-subject group which will be representative of the general traveling public. Additional data which indicate the importance of comfort as a...

Topics: NASA Technical Reports Server (NTRS), AIR TRANSPORTATION, PASSENGERS, SHORT TAKEOFF AIRCRAFT,...

In the decades since the 1950s, when NASA first developed mechanical impact testing of materials, researchers have continued efforts to gain a better understanding of the chemical, mechanical, and thermodynamic nature of the phenomenon. The impact mechanism is a real combustion ignition mechanism that needs understanding in the design of an oxygen system. The use of test data from this test method has been questioned due to lack of a clear method of application of the data and variability found...

Topics: NASA Technical Reports Server (NTRS), IMPACT TESTS, STATISTICAL TESTS, VARIABILITY, COMBUSTION,...

The stability characteristics of a launch vehicle, as a function of gain and phase variations at the thrust vector controller, cannot be obtained using classical sampled-data control theory if the launch vehicle attitude control system contains both sampled-data and continuous feedback control loops. A method was developed which can be used to generate a sampled-data pseudo-Nyquist plot for gain and phase variations at the controller. This method was developed and used to determine the...

Topics: NASA Technical Reports Server (NTRS), DATA SAMPLING, DATA SYSTEMS, SATURN 1B LAUNCH VEHICLES,...

Parameter optimization techniques for the design of linear automatic control systems that are applicable to both continuous and digital systems are described. The model performance index is used as the optimization criterion because of the physical insight that can be attached to it. The design emphasis is to start with the simplest system configuration that experience indicates would be practical. Design parameters are specified, and a digital computer program is used to select that set of...

Topics: NASA Technical Reports Server (NTRS), AUTOMATIC CONTROL, COMPUTER AIDED DESIGN, OPTIMIZATION,...

Resource inventories require samples with geographical scatter, sometimes not as widely spaced as would be hoped. A simple model of correlation over distances is used to create a minimum variance unbiased estimate population means. The fitting procedure is illustrated from data used to estimate Missouri corn acreage.

Topics: NASA Technical Reports Server (NTRS), AGRISTARS PROJECT, CORN, CROP INVENTORIES, DATA SAMPLING,...

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130

May 31, 2011
05/11

by
Dickman, J. David; Si, Xiao-Hon

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The current final report covers the period from June 1, 1999 to May 31, 2002. The primary objective of the investigation was to determine how information regarding head movements and head position relative to gravity is received and processed by central vestibular nuclei neurons in the brainstem. Specialized receptors in the vestibular labyrinths of the inner ear function to detect angular and linear accelerations of the head, with receptors located in the semicircular canals transducing...

Topics: TIME SERIES ANALYSIS, DATA SAMPLING, SEA SURFACE TEMPERATURE, SALINITY, ALGORITHMS, OCEAN DATA...