Bostick, F. X, JrOverview
Publication Timeline
Most widely held works by
F. X, Jr Bostick
The continuation of the study of the detection of magnetic anomalies by means of the perturbations in the natural geomagnetic field
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1 edition published in 1970 in English and held by 1 library worldwide The report presents a feasible method of detecting the passage of various metallic objects by means of perturbations in the natural geomagnetic field in the micropulsation frequency range (0.0001 to 10 Hz). (Author).
An investigation of the magnetotelluric tensor impedance method
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1 edition published in 1970 in English and held by 1 library worldwide A study was made of the magnetotelluric sounding method involving a tensor impedance relationship between the surface electric and magnetic micropulsation fields of the earth. A theoretical treatment of the tensor impedance (including the vertical magnetic field relationship) is offered with emphasis on its response to three-dimensional geometry. Some approximate mathematical models are proposed for use in interpreting three-dimensionality in the surface impedance. An experimental investigation conducted in central Texas is fully discussed. (Author).
Magnetic Anomaly Detection Utilizing Component Differencing Techniques
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1 edition published in 1973 in English and held by 1 library worldwide A scheme for the detection of the passage of ships and other permeable objects which uses stationary component magnetometers is described. The system requires as complete a cancellation of the natural geomagnetic micropulsation noise as is possible in the frequency range from 0.001 to 1 Hz. A simple method for detecting the magnetic anomaly produced by a passing ship is to form the difference between parallel components of the magnetic field variations at each end of a baseline several miles in length. The geomagnetic micropulsation noise tends to cancel, but the target anomaly is more localized and causes each magnetic sensor to operate almost independently for the target detection. However, in many locations the variation in local geology along the baseline introduces a 'geology filter' which must be removed by more elaborate measurement and computation. (Modified author abstract).
An Experimental System for Audio - Magnetotelluric Measurements
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1 edition published in 1973 in English and held by 1 library worldwide An experimental, frequency domain system for audio-magnetotelluric (AMT) measurements is described along with appropriate electromagnetic field theory and data processing techniques. The system employs an induction coil magnetic field sensor, lead metal electrodes for electric field detection, and a pair of synchronized wave analyzers for frequency selection. Data is displayed on a storage oscilloscope and stored on Polaroid photographs. This instrumentation is emphasized in the report with detailed descriptions of sensors and electronic equipment. Sources of the earth's natural field are discussed with particular reference to possible seasonal variations in the strength of the audio-magnetotelluric signal. Also, source distance requirements are included, and the surface impedance of a stratified earth model is derived. Finally, results of AMT measurements in Central Texas are presented. Raw photographic data and computer-estimated apparent resistivity information is displayed, and recommendations for system improvements are made. (Author).
Propagation characteristics of plane small amplitude hydromagnetic disturbances in the earth's upper atmosphere
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1 edition published in 1964 in English and held by 1 library worldwide From the equations of motion, continuity and state, written for a gas consisting of electrons and a single species of positive ions and neutral particles together with Maxwell's equations, the general dispersion relation for plane small amplitude hydromagnetic waves is derived. This relation, a polynomial of the fifth degree in the square of the propagation constant, is solved numerically for medium parameters representative of those encountered in the earth's upper atmosphere. Each of the five roots of the dispersion relation represents a different wave type. Two of the five wave types may be described as essentially transverse waves with the component field fluctuations occurring in planes perpendicular to the direction of propagation. Three of the wave types are longitudinal type waves in which the field component fluctuations occur in planes parallel to the direction of propagation. Of the five wave types, only the two transverse waves appear to be responsible for the transmission of significant amounts of energy through the upper atmosphere. One of the wave forms, qualitatively described as a sound wave in the electron gas, is evanescent throughout the geomagnetic micropulsation frequency range and therefore should not exist with an appreciable amplitude anywhere in the upper atmosphere at those frequencies. (Author).
Propagation characteristics of micropulsations
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1 edition published in 1967 in English and held by 1 library worldwide Simultaneous earth current measurements were made during August and September, 1965 at Ashland, Maine; Huancayo, Peru; Dillingham Air Force Base, Hawaii; and Manila, Philippines. The purpose of the measurements was to provide accurate, reliable data for a study of the worldwide propagation of micropulsations. A method was developed to estimate, by computerized analysis of the data, the difference in arrival time of coherent energy (group delay) at the respective stations. The accuracy limits imposed upon these measurements by the equipment and local geologic conditions have been investigated. Confidence levels of coherence were examined. A method of measuring differences between stations of polarization sense and direction has been derived.
Magnetospheric ducting of electromagnetic waves excited by a line source distribution
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Book
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1 edition published in 1967 in English and held by 1 library worldwide An atmospheric model was used to study the propagation of energy from an electromagnetic source located in the earth's upper atmosphere. An infinite line current source was used with a two-dimensional earth and atmosphere for this study. The model consisted of n isotropic layers with a real value of conductivity, permittivity and permeability in each layer. The earth's magnetic field was omitted from the model. A system of iterative computational matrices was used for numerical evaluation of an 11-layer model where attenuation and phase velocity profiles were stratified for the layer parameters. Curves of the magnitude of the tangential component of magnetic field intensity at the earth's surface are presented as a function of source frequency at a constant distance along the earth's surface from the source, and as a function of distance along the surface from the source at a constant source frequency. The results indicate that ducting or guiding of the energy occurs over a frequency range, and show a large peak of magnetic field intensity on the earth's surface at about 0.3 cycles per second. (Author).
An investigation of the variable frequency dipole-dipole method for determining subsurface resistivities
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1 edition published in 1966 in English and held by 1 library worldwide In this report, the theoretical and some of the experimental features of the variable frequency dipole-dipole method of determining the electrical resistivities of the earth's subsurface structures are investigated. This is essentially equivalent to determining the fields due to a dipole operated at frequencies ranging from DC to several hundred cycles in the presence of resistive inhomogeneities. Mathematical models consisting of homogeneous, isotropic layers are developed for the case when the source is an horizontal electric dipole and a vertical magnetic dipole. Normalized apparent resistivity curves are developed and compared with the equivalent curves one would obtain using the DC dipole method and the magnetotelluric method. It is shown that under certain conditions the variable frequency dipole-dipole method may be superior to them. Experimental data taken in the Delaware Basin, near Pecos, Texas is analyzed by comparison to layered models. The resulting models are compared to models obtained from well-logs and magnetotelluric data. (Author).
Magnetotelluric and DC Dipole-Dipole Soundings in Northern Wisconsin
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1 edition published in 1977 in English and held by 1 library worldwide During the summer of 1974 this Laboratory participated in a joint study of the crust in northern Wisconsin with the Colorado School of Mines, the University of Wisconsin at Madison and others. The Wisconsin Arch region was selected for the large areal extent of outcrop of highly resistive crystalline basement rocks considered most favorable for possible lithospheric propagation of low frequency electromagnetic waves. The principal objective of the joint study was the determination of the maximum resistivity and thickness of a highly resistant zone underlying a thin surface layer of glacial till over most of the area. It was recognized at the outset that a combination of deep DC resistivity sounding, which can determine the resistivity-thickness product of the resistant zone, and the magnetotelluric method, which can determine its thickness, would be required.
AN ANALYSIS OF DYNAMIC POWER SPECTRA
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1 edition published in 1965 in English and held by 1 library worldwide A digital computer program has been developed for computing and displaying dynamic or running power density spectra, with the results being presented as contour plots having lines of constant spectral density on time-frequency planes. The program is discussed in detail, and samples of the output are included. (Author).
Hydromagnetic wave propagation and theoretical power spectra
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1 edition published in 1964 in English and held by 1 library worldwide By assuming that only two modes of propagation (ordinary and extraordinary) exist in a partially ionized medium, one may investigate the complicated behavior of hydromagnetic waves propagat ing in the ionosphere. The Booker Quartic is derived from the general dispersion relation subjected to coordinate transformations. The boundary equations are established and transformed into matrix equations which are used to relate an input wave in the upper ionosphere to the output at the earth. A stratified ionosphere and a dipolar magnetic field are used in the physical model in this report. A constant Hz field is assumed as the incident wave at an altitude of 2000 km. The output power density at the earth's surface is calculated and presented as theoretical power spectrum. The computer program is written so that the theoretical power spectrums produced by input waves incident at any angle with respect to either the input strata or the earth's magnetic field may be computed. (Author).
A study of the transmission of plane hydromagnetic waves through the upper atmosphere
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1 edition published in 1964 in English and held by 1 library worldwide A new conductivity dyadic was used to study the propagation of ordinary and extraordinary modes of wave propagation in a partially-ionized gas. The conductivity tensor included effects of all collisions and the motion of neutral particles. Medium parameters were those of the earth's upper atmosphere. The range of frequencies considered was that of geomagnetic micro-pulsations, 0.00110.0 cps. Geomagnetic equatorial regions received special attention. Incoming incident waves were assumed on a plane-stratified ionosphere. Resultant steady-state frequency responses, impulse responses, current density, electric field, and power dissipation profiles, and power spectra for daytime and nighttime atmospheres were computed. A study of coupling between the two characteristic modes showed appreciable collisional coupling in the lowest ionosphere. (Author).
Ionospheric transmission of transversely propagated plane waves at micropulsation frequencies and theoretical power spectrums
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1 edition published in 1964 in English and held by 1 library worldwide From attenuation and phase constants for plane waves in a partially-ionized magnetopionic medium, the resultant surface magnetic field for discrete, constant-amplitude input signals at an outer boundary is calculated and presented as power spectra. The ionosphere is assumed stratified, and the only mode considered is the extraordinary mode, propagating at 90 degrees with respect to the earth's magnetic field. The results are discussed with reference to experimental power spectra. (Author).
Investigation of large scale inhomogeneities in the earth by magnetotelluric method
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1 edition published in 1962 in English and held by 1 library worldwide IN THE MAGNETOTELLURIC ANALYSIS PROPOSED BY Cagniard, a resistivity profile of a homogeneous stratified earth model is determined from the ratio of the tangential components of the natural electric and magnetic fields at the surface of th earth. This type of analysis is often confused by the fact that apparent resistivity estimates obtained from data recorded at one site on different occasions may vary considerably. Also the apparent resistivities computed from one component of the E field and its orthogonal H field component may be significantly different from those computed from another pair of orthogonal field components. Cantwell points out that these variations may, at least in part, be due to two dimensional in omoge iti s a /or iso ropies toget er with randomly polarized magnetotelluric fields. Accordingly, he has suggested tes ing the wave impedance of the earth as a rank two ten or. This report de crib s a measurement and analysis procedure developed using a model based on a two dimensional wave impedance tensor. A rotation of the measuring axis to minimize the mai diagonal terms in the impedance tensor yields a reasonably con istent stimate of the direction and magnitude of a major inhomogeneity in th apparent resistivity profile. (Author).
An analysis of the magnetotelluric method for determining subsurface resistivities
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1 edition published in 1961 in English and held by 1 library worldwide Theoretical and experimental features of the magnetotelluric method of determining the electrical resistivities of the earth's subsurface structures were investigated. Mathematical models consisting of multiple homogeneous and isotropic resistive layers in a semi-infinite half space were analyzed, and a set of normalized apparent resistivity curves were derived for a twolayer model. A theoretical treatment of the data analysis procedures is presented with particular emphasis on the power spectrum and cross spectrum analysis performed by the direct filtering method. It is pointed out that it is unnecessary and often undesirable to treat the data recordings as stationary time series. Many of the fluctuations in the resistivity estimates are the result of the presence of two-dimensional inhomogeneities and anisotropies and may not be averaged out in the usual statistical sense. Recordings made of the fluctuations of the magnetotelluric fields were analyzed and the results of these analyses are presented. A brif description of the data recording and analysis equipment is also included. (Author).
Further studies of the directional properties of magnetotelluric signals
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1 edition published in 1961 in English and held by 1 library worldwide Preliminary measurements of the directional properties and phase relations of the magnetotelluric fields at Austin, Texas, were described in EERL Report No. 116, (AD-245 507). In this report, these measurements have been extended to include a large number of cases over the period from 13 April to 26 October 1960. In addition, the measurement of the direction of the vertical components and the total variable magnetic field have been included. (Author).
Directional properties and phase relations of the magnetotelluric fields at austin, texas
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1 edition published in 1960 in English and held by 1 library worldwide
A geomagnetic micropulsation measuring system utilizing air-core coils as detectors
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1 edition published in 1960 in English and held by 1 library worldwide
Frequency spectra analyses of one millisecond time response temperature sensors at various levels near the ground
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1 edition published in 1960 in English and held by 1 library worldwide
A POWER SPECTRUM COMPUTER
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1 edition published in 1956 in English and held by 1 library worldwide more
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