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Subsurface electromagnetic measurement through steel casing

Description: Numerical calculations show that useful information can be obtained in an electromagnetic crosswell survey where one of the wells is cased in steel. Our simple model is based on the assumption of an infinitely long uniform casing embedded in a homogeneous full space. Nevertheless the results indicate that if the pipe characteristics are independently known then the formation signal can be accurately recovered. This is best done at a single frequency where the pipe attenuation is modest. In fact we show that the optimal frequency for formation signal recovery is defined mainly by the pipe parameters and is largely independent of the formation conductivity.
Date: November 1998
Creator: Becker, A. B.; Wang, B. & Lee, K. H.
Partner: UNT Libraries Government Documents Department

A New Determination of the Ratio of the Electromagnetic to the Electrostatic Unit of Electricity [Part 1]

Description: Report issued by the Bureau of Standards over new determinations made in regard to units of electricity. Methods and equipment used are discussed. This report includes tables, illustrations, and photographs. Part 1 includes sections I through VI.
Date: 1907
Creator: Rosa, Edward B. & Dorsey, N. E.
Partner: UNT Libraries Government Documents Department

A New Determination of the Ratio of the Electromagnetic to the Electrostatic Unit of Electricity [Part 2]

Description: Report issued by the Bureau of Standards over studies of the determination of the ratio of electricity. The ratio of electromagnetic to electrostatic units of electricity is discussed in detail. This report includes tables, illustrations, and photographs. Part 2 includes section VII and concluding remarks.
Date: 1907
Creator: Rosa, Edward B. & Dorsey, N. E.
Partner: UNT Libraries Government Documents Department

Isentropic Compression in a Strip Line, Numerical Simulations and Comparison with GEPI Shot 268

Description: Isentropic compressions in a strip line geometry are performed on the GEPI facility at Centre d'etudes de Gramat in order to study isentrope, associated Hugoniot and phase changes [1] [2]. 3D GEPI configuration has been calculated here to test the new beta version of the electromagnetism package coupled with the dynamics in LS-DYNA{reg_sign} and compared with the GEPI experiment number 268.
Date: February 13, 2006
Creator: Lefran├žois, A; L'Eplattenier, P. & Burger, M.
Partner: UNT Libraries Government Documents Department

Precision Measurement and Calibration: Electricity: Selected Papers on the Realization and Maintenance of the Fundamental Electrical Units and Related Topics

Description: Abstract: Selected publications of the National Bureau of Standards technical staff in the field of electricity were first compiled in 1962 as a volume of the NBS Precision Measurement and Calibration Series (Electricity and Electronics, Handbook 77, Volume I); this compilation was extended in 1968 by the compilation of an additional volume in the Precision Measurement and Calibration Series (Electricity-Low Frequency, NBS Special Publication 300, Volume 3). The present volume, a further extension of these earlier compilations of selected publications in the field of electricity, includes 66 more recent papers by NBS authors and 16 abstracts of closely related papers by authors from other organizations. In view of the expansion of measurement technologies used in electricity and electromagnetism it has been necessary to reduce the range of topics for the selection of papers in the new compilation. In this connection an emphasis has been placed upon the realization and maintenance of fundamental electrical units and the related scientific advances, particularly in quantum physics. However, in the interest of completeness, three appendices also provide up-to-date bibliographies of publications by NBS authors in different areas of electromagnetism. (This book is a sequel to NBS Handbook 77-Vol. 1(1961) and NBS SP 300-Vol. 3 (1968).
Date: October 1985
Creator: McCoubrey, Arthur O.
Partner: UNT Libraries Government Documents Department

Dispersive wave processing: a model-based solution

Description: Wave propagation through various media represents a significant problem in many applications in acoustics and electromagnetics especially when the medium is dispersive. We post a general dispersive wave propagation model that could easily represent many classes of dispersive waves and proceed to develop a model-based processor employing this underlying structure. The general solution to the model-based dispersive wave estimation problem is developed using the Bayesian maximum a posteriori approach which leads to the nonlinear extended Kalman filter processor.
Date: October 1, 1996
Creator: Candy, J.V. & Chambers, D.C.
Partner: UNT Libraries Government Documents Department

Surface and borehole electromagnetic imaging of conducting contaminant plumes

Description: Electromagnetic induction tomography is a promising new tool for imaging electrical conductivity variations in the earth. The EM source field is produced by induction coil (magnetic dipole) transmitters deployed at the surface or in boreholes. Vertical and horizontal component magnetic field detectors are deployed in other boreholes or on the surface. Sources and receivers are typically deployed in a configuration surrounding the region of interest. The goal of this procedure is to image electrical conductivity variations in the earth, much as x-ray tomography is used to image density variations through cross-sections of the body. Although such EM field techniques have been developed and applied, the algorithms for inverting the magnetic field data to produce the desired images of electrical conductivity have not kept pace. One of the main reasons for the lag in the algorithm development has been the fact that the magnetic induction problem is inherently three dimensional; other imaging methods such as x-ray and seismic can make use of two-dimensional approximations that are not too far from reality, but we do not have this luxury in EM induction tomography. In addition, previous field experiments were conducted at controlled test sites that typically do not have much external noise or extensive surface clutter problems often associated with environmental sites. To use the same field techniques in environments more typical of cleanup sites requires a new set of data processing tools to remove the effects of both noise and clutter. The goal of this project is to join theory and experiment to produce enhanced images of electrically conducting fluids underground, allowing better localization of contaminants and improved planning strategies for the subsequent remediation efforts. After explaining the physical context in more detail, this report will summarize the progress made in the first 18 months of this project: (1) on code ...
Date: July 1, 1998
Creator: Berryman, J. G., LLNL
Partner: UNT Libraries Government Documents Department

Electromagnetic aftereffects of near-death experiences.

Description: The purpose of this quantitative study was first to investigate the comparative incidence of electromagnetic aftereffects (EMEs) during the past year among near-death experiencers (NDErs), people who experienced a close brush with death without an NDE (CBrs), and people who reported never having experienced a close brush with death (LCErs). The second purpose was to investigate a possible change in EME incidence among the three groups before and after a critical life event. The third purpose was to investigate the relationship between the reported overall depth and specific components of the subjective experiences of people who have had a close brush with death -- NDErs and CBrs -- and their reported incidence of EMEs. I used the Near-Death Experience Scale (Greyson, 1983), and developed the Close Brush with Death Question form, Life Changing Event Question form, and Electromagnetic Effects Questionnaire for this study. The final sample included 36 NDErs, 20 CBrs, and 46 LCErs. The results of this study firmly supported more reported problems with EM devices experienced by NDErs compared to CBrs or LCErs. Especially with respect to EM devices such as lights and cell phones, as well as the emotional state of individuals affecting EM devices, this study showed more reports of problems with these devices between before and after NDEs for NDErs compared to before and after a life changing event for LCErs. Moreover, findings of this study showed a correlation between the depth of NDEs and EMEs. This study has important implications for counselors working with NDErs. Findings from this study show that NDErs have a strong possibility of experiencing electromagnetic interferences when close to electromagnetic devices such as cell phones, computers, lights, and watches after their NDEs. This phenomenon can be a stressor in the lives of NDErs and their families and friends. As some ...
Date: August 2008
Creator: Nouri, Farnoosh Massoudian
Partner: UNT Libraries

A Fundamental Theorem on Particle Acceleration

Description: A fundamental theorem on particle acceleration is derived from the reciprocity principle of electromagnetism and a rigorous proof of the theorem is presented. The theorem establishes a relation between acceleration and radiation, which is particularly useful for insightful understanding of and practical calculation about the first order acceleration in which energy gain of the accelerated particle is linearly proportional to the accelerating field.
Date: May 1, 2003
Creator: Xie, Ming
Partner: UNT Libraries Government Documents Department


Description: Expressions for the wave-energy density and wave-momentum density of each species of a collisionless plasma are derived. The sum of the wave-energy (momentum) densities of all the species and the electromagnetic energy (momentum) density gives the previously known result for the total wave-energy (momentum) density of a dispersive medium.
Date: November 1, 1979
Creator: Cary, John R. & Kaufman, A.N.
Partner: UNT Libraries Government Documents Department


Description: In a previous series of reports (1, 2, 3), we have outlined and incorporated a mathematical analysis of a circular and elliptical boundary into the program POISSON thus making it possible to calculate with good accuracy the vector potential (and hence the field) of problems which have little or no symmetry. The analysis was based on the assumption that no sources are present outside the boundary introduced . As will be shown, this condition can be waived by incorporating superposition into the relaxation process in a way that solutions to electromagnetic problems which are affected by an outside field (such as the earth magnetic field) can be obtained. Such solutions are also possible in the area of hydrodynamics. Similarities in the physical laws that govern electromagnetism and incompressible invicid hydrodynamics indicate that POISSON can be used as a tool to solve such problems. It is, however, the introduction of boundary condition and superposition into the relaxation process of POISSON that make such solutions practical. We have introduced a combination of superposition and boundary condition into the relaxation process of POISSON in a manner that solutions can be obtained to electromagnetic problems placed in a background field as well as two-dimensional hydrodynamic problems involving potential flow and circulation. We have named the new program FOIL. In simple terms. the total potential, reduced by such background contributions, is subjected to the type of boundary treatment that was employed previously when no external 'sources' were present.
Date: January 1, 1985
Creator: Caspi, S.; Helm, M. & Laslett, L.J.
Partner: UNT Libraries Government Documents Department

Parallel auxiliary space AMG for definite Maxwell problems

Description: Motivated by the needs of large multi-physics simulation codes, we are interested in algebraic solvers for the linear systems arising in time-domain electromagnetic simulations. Our focus is on finite element discretization, and we are developing scalable parallel preconditioners which employ only fine-grid information, similar to algebraic multigrid (AMG) for diffusion problems. In the last few years, the search for efficient algebraic preconditioners for H(curl) bilinear forms has intensified. The attempts to directly construct AMG methods had some success, see [12, 1, 7]. Exploiting available multilevel methods on auxiliary mesh for the same bilinear form led to efficient auxiliary mesh preconditioners to unstructured problems as shown in [4, 8]. A computationally more attractive approach was recently proposed by Hiptmair and Xu [5]. In contrast to the auxiliary mesh idea, the method in [5] uses a nodal H{sup 1}-conforming auxiliary space on the same mesh. This significantly simplifies the computation of the corresponding interpolation operator. In the present talk, we consider several options for constructing unstructured mesh AMG preconditioners for H(curl) problems and report a summary of computational results from [10, 9]. Our approach is slightly different than the one from [5], since we apply AMG directly to variationally constructed coarse-grid operators, and therefore no additional Poisson matrices are needed on input. We also consider variable coefficient problems, including some that lead to a singular matrix. Both type of problems are of great practical importance and are not covered by the theory of [5].
Date: February 16, 2007
Creator: Kolev, T V & Vassilevski, P S
Partner: UNT Libraries Government Documents Department


Description: Brillouin polyhedra for the intermetallic compounds of lithium and lead were determined using the zone theory. From these determinations, predictions and explanations of some electromagmetic and structural properties of the intermetallic compounds were made. (For Part IV see UCRL-4973.) (C.J.G.)
Date: November 13, 1959
Creator: Ramsey, W J & Jepson, J O
Partner: UNT Libraries Government Documents Department