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Program eliminates or reduces time-consuming aspects of computation of power spectrum for high-frequency communication system. This program was written in FORTRAN IV for UNIVAC 1230 or 1108 computer.
A method for prediction and analysis of the spectrum of the signal from the Laser Doppler Velocimeter is presented. The results relate the heterodyne spectrum of the signal to the space-time correlation function for the turbulent transport of tracer particles in the fluid and to the characteristics of the optical system.
Four meteor spectra are analyzed for chemical composition and radiative processes. The chemical compositions of the Taurid, Geminid, and Perseid meteors were found to be similar to that of a typical stony meteorite. The chemical composition of the sporadic meteor was found to be similar to that of a nickel iron meteorite. The radiation from optical meteors was found to be similar to that of a low temperature gas, except that strong, anomalous ionic radiation is superposed on the neutral radiation in bright, fast meteors.
An experimental model of a mechanical spectrometer is reported that permits vibration measurements at 297 points on a mechanical device and processes this information by digital computer for automatic printout.
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A spectrogram of a fast optical meteor was reduced and analyzed, and 60 features were identified in the spectrum. Air and ionized elements in this meteor radiate throughout the spectrum from 3000 A to 6800 A. A mass of 9 mg and an effective radiation temperature of approximately 5700 K were computed for the meteor. Weight ratios of Ca:Fe, and Mg:Fe, and Na:Fe were computed. A plasma particle velocity distribution for meteors was derived, and the average collision speed obtained from this distribution was compared with the relative collision speed of a Fe-N2 gas mixture at 5700 K.
Results are presented for a project directed to assess the type and extent of long-term natural and man-made changes in floodplain features of a definite area in the Mississipi River Valley. 1:6000 scale maps were prepared from remotely sensed film/filter photographic coverage of the area at different times to compare changes in such features as channels, backwaters, vegetation as well as changes in the amount, location, and conditions of dredge spoil. Changes observed by this sequential photo comparison include abandonment of agricultural land followed by orderly secondary plant succession, the filling-in of shallows by sediment and the orderly succession of plants from a hydric to a more mesic environment and changes in deltas of small tributary streams in response to agricultural practices occurring at their headwaters. Plant colonization is observed on some spoil, and secondary movement of spoil is revealed in other areas.
Analysis of the bandlike Jovian decametric emission is presented. A model for the active region that accounts for the observed radiation characteristics is described using the measured parameters of the bandlike emission and a model of the Jovian magnetic field. The active region is characterized not only by the fact that an upward-flowing electron stream is caused to radiate in this region, but the stream itself is broken into radiating electron bunches within the active region. Observed undulations of the emission band on the time-frequency plane are interpreted as motions of the active region along a flux tube. The instantaneous location of the active region along the flux tube shows a dependence on the density of the stream entering the active region. The mechanism responsible for density modulation of the stream appears to be common to both the bandlike and simple-S-burst emission types.
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In connection with a need for more definitive information concerning the composition of Phobos in a study of its origin, an ultraviolet-visible-infrared reflectance spectrum of the Martian satellite was compiled from the Mariner 9 ultraviolet spectrometer, Viking lander imaging, and ground-based photometric data. The probable surface composition of Phobos was deduced by comparing the obtained spectrum with the spectra of asteroids of known composition. The considered data show that the reflectivity of Phobos is flat from 1100 to 400 nm but decreases sharply in the ultraviolet to about 1 percent at 212 nm. The reflectance spectrum is similar to the spectra of asteroids Ceres and Pallas which were found to have surface compositions similar to that of carbonaceous chondrites. It is concluded that the surface composition of Phobos is also similar to that of carbonaceous chondrites. The results of the investigation point to different modes of origin for Mars and Phobos.
A description is presented of a study which examines not only wind shear, but considers the velocity spectrum of the wind, as it may affect the flight of an aircraft. A model reported by McCarthy and Blick (1976) and by Blick et al. (1978) is considered. The model simulated the approach performance of a Boeing 727-type aircraft, as affected by the time series winds measured along the aircraft's longitudinal axis. Attention is given to the model and its implications, wind shear simulations, and the use of the model in the study of a crash on June 24, 1975.
The application of the remote sensing techniques of aerial photography and multispectral scanning in the qualitative and quantitative analysis of plumes from ocean dumping of waste materials is investigated in the New York Bight Apex. Plumes resulting from the dumping of acid waste and sewage sludge were observed by Ocean Color Scanner at an altitude of 19.7 km and by Modular Multispectral Scanner and mapping camera at an altitude of 3.0 km. Results of the qualitative analysis of multispectral and photographic data for the mapping, location, and identification of pollution features without concurrent sea truth measurements are presented which demonstrate the usefulness of in-scene calibration. Quantitative distributions of the suspended solids in sewage sludge released in spot and line dumps are also determined by a multiple regression analysis of multispectral and sea truth data.
An analysis of the spatial phase and amplitude structures of the ground Pc 5 pulsations in the morning sector was carried out using data from the North American IMS magnetometer network. Signals in the X, Y, and Z components were found to propagate from noon to the nightside with an apparent phase velocity of 13 km/sec. The phase was determined to vary with latitude, with total latitudinal phase differences of 200 and 90 deg, respectively, for the X and Y components. Corresponding latitudinal phase differences in the vertical components were 550 deg for the Alaska chain, and 360 deg for the Fort Churchill chain. Phase variation in the Fort Churchill chain was attributed to the ionospheric Hall current related to the field line resonance and the earth induction current. The earth induction current in the shallower regions near Fort Yukon is a necessary factor to explain the large variation in the Alaska chain.
Evidence for two types of relatively large amplitude MHD waves upstream and downstream of quasi-parallel forward and reverse interplanetary shocks is presented. The first mode is an Alfven wave with frequencies (in the spacecraft frame) in the range of 0.025 to 0.07 Hz. This is a left-hand polarized mode and propagates within a few degrees of the ambient magnetic field. The second is a fast MHD mode with frequencies in the range of 0.025 to 0.17 Hz, right-hand polarization and propagating along the magnetic field. These waves are detected principally in association with quasi-parallel shock. The Alfven waves are found to have plasma rest frame frequencies in the range of 1.1 to 6.3 mHz with wavelengths in the order of 4.8 x 10 to the 8th power to 2.7 x 10 to the 9th power cm. Similarly, the fast MHD modes have rest frame frequencies in the range 1.6 to 26 mHz with typical wavelengths about 2.19 x 10 to the 8th power cm. The magnetic field power spectrum in the vicinity of these interplanetary shocks is much steeper than f to the -s/3 at high frequencies. The observed spectra have a high frequency dependence of f to the -2/5 to f to the -4.
The CF2Cl2 absorption bands at 1/923 cm and 1/1161 cm are examined as to their detectability in long-path solar spectroscopy. Measurements are reported for a long-path White Cell. A cryo-condensation unit was also constructed to test its ability to improve detection of trace gases in the ambient atmosphere.
The technique used to analyze groove spacing on Ganymede is presented. Data from Voyager images are used determine the surface topography and position of the grooves. Power spectal estimates are statistically analyzed and sample data is included.
A quantitative analysis of groove spacing on Ganymede is described. Fourier transforms of a large number of photometric profiles across groove sets are calculated and the resulting power spectra are examined for the position and strength of peaks representing topographic periodicities. The geographic and global statistical distribution of groove wavelengths are examined, and these data are related to models of groove tectonism. It is found that groove spacing on Ganymede shows an approximately long-normal distribution with a minimum of about 3.5 km, a maximum of about 17 km, and a mean of 8.4 km. Groove spacing tends to be quite regular within a single groove set but can vary substantially from one groove set to another within a single geographic region.