Parameter selection for periodicity measurement by the method of power spectral analysis
Parameters for power spectral analysis of periodicities in computer generated and real data of hibernating squirrel brain temperatures
PHYSIOLOGY↗
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Multi-dimensional real Fourier transform
Four subroutines compute one-dimensional and multi-dimensional Fourier transforms for real data, multi-dimensional complex Fourier transforms, and multi-dimensional sine, cosine and sine-cosine transforms. Subroutines use Cooley-Tukey fast Fourier transform. In all but one-dimensional case, transforms are calculated in up to six dimensions.
Krogh, F. T.↗
An investigation into some problems in analytical processing of lunar orbiter photography
Problems in analytical processing of lunar orbiter photography are discussed. The effects of image motion and image motion compensation on the location of the principal point are analyzed. The effect of the focal plane shutter on the distortion and interior geometry is examined. Real data is used to confirm the workability of a mathematical model and the use of a computer to calibrate spaceborne photographic imagery.
Ghosh, S. K.↗
Transformation between orbital parameters in different coordinate systems of the general relativistic Schwarzschild problem.
The relationships between the osculating orbital elements for a family of solutions of the general relativistic Schwarzschild problems are developed. These relationships provide a method for evaluating orbital elements in different Schwarzschild coordinate systems without the necessity of fitting to real data every time the system of coordinates is changed. The objectivity of different coordinate systems is discussed. Considerations of orbital motions favor the standard Schwarzschild metric, but the propagation of light signals is more objective in the metric of Painleve. Because the orbital motions usually dominate the representation of data, the standard Schwarzschild coordinates are the best objective choice for most applications.
Georgevic, R. M.↗
Filtering theory applied to orbit determination
Modifications to the extended Kalman filter and the Jazwinski filter are made and compared with the classical extended Kalman filter in applications to orbit determination using real data. The results show that with the kind of data available today, the application of filtering theories in this field presents many problems.
Torroglosa, V.↗
Adjustment technique without explicit formation of normal equations /conjugate gradient method/
For a simultaneous adjustment of a large geodetic triangulation system, a semiiterative technique is modified and used successfully. In this semiiterative technique, known as the conjugate gradient (CG) method, original observation equations are used, and thus the explicit formation of normal equations is avoided, 'huge' computer storage space being saved in the case of triangulation systems. This method is suitable even for very poorly conditioned systems where solution is obtained only after more iterations. A detailed study of the CG method for its application to large geodetic triangulation systems was done that also considered constraint equations with observation equations. It was programmed and tested on systems as small as two unknowns and three equations up to those as large as 804 unknowns and 1397 equations. When real data (573 unknowns, 965 equations) from a 1858-km-long triangulation system were used, a solution vector accurate to four decimal places was obtained in 2.96 min after 1171 iterations (i.e., 2.0 times the number of unknowns).
Saxena, N. K.↗
Computer simulation of the Pioneer 10 microwave occultation experiment
As Pioneer 10 approaches the planet Jupiter, its trajectory will carry it behind the planet, as seen from the earth. The microwave telemetry signal from the spacecraft will then pass through the Jovian atmosphere on its way to the earth, and analysis of the effects of the atmosphere on the signal should yield information on the atmospheric structure. To help define the capabilities of this experiment and to aid the analysis of the real data, we have simulated the occultation experiment on a computer by using model Jovian atmospheres and a predicted trajectory. The results indicate that the useful depth of penetration of the microwave signal will be governed by ammonia absorption rather than superrefractivity. The experiment is apparently far more sensitive to variations in cloud-top temperature than to variations in the hydrogen-helium ratio. Characteristic 'flashes' in the attenuation record of the signal may yield information on the location of the top of the Jovian convective zone.
Ungar, S. G.↗
Projection of school district enrollments
The objectives were to provide a better statistical basis for enrollment projections, to attempt to model the school district's enrollment, and to produce a single estimate of enrollment for each grade, grade group, and ethnic group, and for the total by year. Efforts were also made to provide error estimates for the projections, to design a simple, user-oriented computer program for use by school district administrators, and to work with real data from local school districts and aid them in making projections on an experimental basis. The study at Jet Propulsion Laboratory was concerned with projection methodology and production of a generally usable computer program.
Van Dillen, S. L.↗
A Skylab program for the International Hydrological Decade (IHD)
The author has identified the following significant results. The development of the algorithm (using real data) relating red and IR reflectance to surface soil moisture over regions of variable vegetation cover will enable remote sensing to make direct inputs into determination of this important hydrologic parameter.
Polcyn, F. C.↗
Atmospheric analysis and prediction model development, volume 1
A set of hemispheric atmospheric analysis and prediction models was designed and tested. All programs were executed on either a 63 x 63 or 187 x 187 polar stereographic grid of the Northern Hemisphere. Parameters for objective analysis included sea surface temperature, sea level pressure, and twelve levels (from 1,000 to 100 millibars) of temperatures, heights, and winds. Stratospheric extensions (up to 10 millibars) were also provided. Four versions of a complex atmospheric prediction model, based on primitive equations, were programmed and tested. These models were executed on either the 63 x 63 or 187 x 187 grid, using either five or ten computational layers. The coarse-mesh (63 x 63) models were tested using real data for the period 21-23 April 1976. The fine-mesh (187 x 187) models were debugged, but insufficient computer resources precluded production tests. Preliminary test results for the 63 x 63 models are provided. Problem areas and proposed solutions are discussed.
Kesel, P. G.↗
Computer-aided analysis of CCD linear image sensors
Special test equipment and techniques to collect and process image information from charge coupled devices (CCDs) by digital computer were reviewed. The video channel was traced from the CCD to the direct memory access bus of the Interdata Computer. Software was developed to evaluate and characterize a CCD for (1) dark signal versus temperature relationship, (2) calculation of temporal noise magnitude and noise shape for each pixel, (3) spatial noise into the video chain due to dark signal, (4) response versus illumination relationship (gamma), (5) response versus wavelength of illumination (spectral), (6) optimization of forcing functions, and (7) evaluation of an image viewed by a CCD. The basic software differences and specific examples of each program operating on real data are presented.
Prince, S. S.↗
Reference orbits from range and Doppler observations
The paper is concerned with the height accuracy of reference orbits obtained by a system composed of one laser and three Doppler stations. It is thought that reference orbits obtained by this system could be used for altimeter evaluation, although height errors increased up to 50% over those from the orbits with four lasers. Simulation studies and real data results are analyzed, and the implications for the GEOS-3 project are considered.
Berbert, J.↗
Sensitivity of Forecast Skill to Different Objective Analysis Schemes
Numerical weather forecasts are characterized by rapidly declining skill in the first 48 to 72 h. Recent estimates of the sources of forecast error indicate that the inaccurate specification of the initial conditions contributes substantially to this error. The sensitivity of the forecast skill to the initial conditions is examined by comparing a set of real-data experiments whose initial data were obtained with two different analysis schemes. Results are presented to emphasize the importance of the objective analysis techniques used in the assimilation of observational data.
Baker, W. E.↗
Mathematic modeling of the Earth's surface and the process of remote sensing
It is shown that real data from remote sensing of the Earth from outer space are not best suited to the search for optimal procedures with which to process such data. To work out the procedures, it was proposed that data synthesized with the help of mathematical modeling be used. A criterion for simularity to reality was formulated. The basic principles for constructing methods for modeling the data from remote sensing are recommended. A concrete method is formulated for modeling a complete cycle of radiation transformations in remote sensing. A computer program is described which realizes the proposed method. Some results from calculations are presented which show that the method satisfies the requirements imposed on it.
Balter, B. M.↗
The augmentation algorithm and molecular phylogenetic trees
Moore's (1977) augmentation procedure is discussed, and it is concluded that the procedure is valid for obtaining estimates of the total number of fixed nucleotide substitutions both theoretically and in practice, for both simulated and real data, and in agreement, for experimentally dense data sets, with stochastic estimates of the divergence, provided the restrictions on codon mutability resulting from natural selection are explicitly allowed for. Tateno and Nei's (1978) critique that the augmentation procedure has a systematic bias toward overestimation of the total number of nucleotide replacements is disputed, and a data analysis suggests that ancestral sequences inferred by the method of parsimony contain a large number of incorrectly assigned nucleotides.
Holmquist, R.↗
On the simulation of the oceanic general circulation
Two global ocean simulations based on the physics of a highly viscous ocean are discussed, one having realistic atmospheric functions for calculating the thermal forcing of the ocean. The velocity field of this model compares reasonably well with the relatively small amount of real data available. Temperature and heat budget components of the model reproduce best the equatorial band of heating. A simulation based upon the physics of a weakly viscous ocean is described, which produces the correct pattern of isotherms. This model has not yet been run to thermal equilibrium. The Gulf Stream and eddies and their influence on the oceanic and atmospheric heat budgets are discussed in the terms of their importance in coupled ocean-atmosphere models.
Mintz, Y.↗
Treatment of cloudiness in regional scale - Numerical weather prediction models
A numerical weather prediction model is considered in which cloud water and precipitation are explicitly predicted as functions of three space dimensions and time. Approximations in the thermodynamic and continuity equations are discussed in detail, as well as the cumulus parameterization and the cloud microphysics parameterization. An example of a real-data forecast indicates that very accurate quantitative precipitation and cloud cover forecasts are possible using initial observations from only the relatively sparse rawinsonde network in the U.S.
Kreitzberg, C. W.↗
Semi-empirical estimates of gravitational wave generation by stellar collapse
The problems of the generation and detection of gravitational waves and the difficulty of detecting the burst of gravitational radiation produced by a stellar collapse in our Galaxy, or in neighbouring clusters of galaxies where such collapses are expected to occur frequently, have been reviewed elsewhere. As stellar collapses, explosions, or supernovae are poorly understood, the values of the strength of these sources depend on uncertain assumptions. However, it is possible to make some independent estimates on semi-empirical grounds, using observed facts concerning the remnants of stellar evolution. These estimates, reported here, have serious weaknesses. They must involve oversimplified models and very crude standard calculations of the collapse and radiation processes. Also, because they are based on observed properties of stellar remnants, they say nothing about collapses which do not produce observable remnants. Although this selection may introduce a strong bias, these estimates deserve consideration because they are tied to real data.
Katz, J. I.↗