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1 
Electromagnetic response of thin wires over an homogeneous earth.Young, Jeffrey Lee. January 1989 (has links)
The electromagnetic response of infinitely long, thin wires over a flat earth is presented for two different applications: the shielding properties of an ensemble of parallel wires excited by a plane wave and the electromagnetic coupling of two perpendicular wires excited by a dipole. The shielding study begins with the formulation of the boundary value problem for N wires over a lossy half space. A suitable axial impedance operator is applied to obtain a system of equations whose unknowns are the currents flowing on each wire. Once the currents are determined, the aggregate field produced by the ensemble can be computed by summing N Fourier type integrals. For the specialized case of the infinite planar grid, Floquet's Theorem and Poisson's Summation Formula are invoked, transforming the linear system of equations into a closed form expression for the current flowing on each wire. We show that the electromagnetic response of the planar grid of finite extent and the grid of infinite extent are similar. For nonplanar configurations, such as the semicircular shell, shielding values of 60 dB are possible when the structure is of nonresonant dimensions; otherwise, the performance can degrade to 20 dB. In the case of the crossed wire configuration, the starting point is the development of the integral equations that govern the coupling between wires and the source; the unknowns are the spectral currents flowing in each wire. The equations are given in terms of generalized impedance functions for the situation where the wires are over a stratified earth. However, for the numerical work, only the case where the wires are in an unbounded, homogeneous medium is considered. Two numerical methods, with overlapping regions of validity, are applied: the method of moments and the method of multiple scatterers. By using the method of moments, we can obtain a matrix equation that will determine the spectral currents for any wire spacing. The multiple scatterer method leads to a more convenient matrix series solution and shows that the coupling strength is proportional to 1/d², where d is the wire separation, plus higher order inverse terms.

2 
Basic concepts of structure shielding from falloutCarlson, Donald R January 2010 (has links)
Digitized by Kansas Correctional Industries

3 
PET/CT shielding design comparisonsCoker, Audra Lee 17 September 2007 (has links)
The objective of this project was to compare two different methods of calculating
dose through leadshielded walls in the PET/CT suite at Scott & White Hospital in
Temple, Texas. The ultimate goal was to see which of the two methods agreed with the
actual physical measurements. Minimizing shielding needed in future suite designs
would result in a possible reduction of structural as well as financial burden. Formulas
and attenuation coefficients following the basic January 2006 AAPM guidelines were
used to calculate unattenuated radiation through existing lead walls. The computer code
MCNPX was used to simulate the leaded walls of the PET/CT suite and provide another
set of results. These two sets of results were compared to doses gathered from OSL
badges placed around the suite for a period of two months. For this type of problem,
MCNPX proved to provide results that were inconsistent and unreliable. It was
concluded that the traditional computational methods are the most reliable for designing
shielding in a PET/CT suite.

4 
Shielding effectiveness of superalloy, aluminum, and mumetal shielding tapes a project report /Cheung, Cindy S. Mehiel, Eric A. January 1900 (has links)
Thesis (M.S.)California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on July 10, 2009. Major professor: Dr. Eric Mehiel. "Presented to the faculty of California Polytechnic State University at San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Aerospace Engineering with specialization in Space Systems Engineering." "April 2009." Includes bibliographical references (p. 48).

5 
Frequency response of E polarized sources over a lossy earth in the presence of twodimensional shielding structures.Baertlein, Brian Allen. January 1988 (has links)
Electromagnetic shielding by thin, perfectly conducting, two dimensional cylindrical shells over a lossy earth is investigated. The temporal frequency response of the exterior field due to a line source within the shell is computed for a shell described by a three sided, rectilinear structure whose opening faces the earth. The formulation allows shells of arbitrary crosssectional shape to be analyzed. The earth is modeled as a homogeneous halfspace with a planar boundary and frequency dependent electromagnetic properties. Two solution techniques are presented. In the first, the induced current is obtained through a numerical solution of the electric field integral equation (EFIE) at many discrete frequencies. It is found that the applicability of this formulation is limited since in the case of effective shielding, fields calculated from the EFIE are very sensitive to numerical errors. In the second technique the EFIE is again solved for the currents induced on the shell. The induced currents are used to calculate the electric field in the aperture which is used to solve a combinedsource integral equation (CSIE) for the external fields. It is found that the CSIE does not suffer from the numerical illconditioning that plagues the EFIE, and is well behaved at all frequencies. Numerical results are presented which indicate that the shellearth combination is very effective in shielding the internal source. Interior modes are weakly transmitted to the interior for the case of a purely dielectric earth. For a lossy halfspace the resonances of the closed shell are enhanced. The related topic of scattering by perfectly conducting objects over a lossy earth is addressed. Numerical formulations for the solution of the integral equations are presented which deal with several troublesome aspects of the problem, including the incorporation of the correct edge singularities.

6 
THERMAL NEUTRONS IN DUCTED SHIELDSChannon, Frederick Robert, 1938 January 1966 (has links)
No description available.

7 
Design of a ²⁵²CFbased neutron shielding test standBanks, Julia Michelle 05 1900 (has links)
No description available.

8 
Development of Active Magnetic Shielding for the Neutron Electric Dipole Moment Experiment at TRIUMFLang, Michael 14 January 2014 (has links)
Active magnetic shielding has been proposed to provide lowfrequency magnetic field stability in the neutron electric dipole moment (nEDM) experiment planned for TRIUMF. A prototype active magnetic shielding system was constructed and tested at the University of Winnipeg. The system is capable of providing RMS shielding factors > 1000 for magnetic field perturbation frequencies ≤ 20 mHz, and > 100 for frequencies ≤ 0.5 Hz, and can reduce magnetic
field variations on the order of tens of μT to the level of tens of nT. The achievable shielding factor was limited by the fi eld sampling rate limit of 400 Hz, and by the background fi eld noise floor of the laboratory. This represents good progress towards the eventual system for nEDM experiments, where lowfrequency field drifts on the order of 100 nT require active shielding to the order of 1 nT.

9 
Analysis of a test technique for hardness surveillanceMarcum, Frank. January 1988 (has links)
Thesis (M.S.)Ohio University, June, 1988. / Title from PDF t.p.

10 
A comparison of measured and simulated exposure rates near tungstenbased medical transport pigs /Newman, Errol D. I. January 1900 (has links)
Thesis (M.S.)Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 8485). Also available on the World Wide Web.

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