Electromagnetic methods method

Although isotopes have similar chemical properties, their slight difference in mass causes slight differences in physical properties. Use of this is made in isotopic separation pro cesses using techniques such as fractional distillation, exchange reactions, diffusion, electrolysis and electromagnetic methods. 

Zaitzev, V.M., Pokhil, P.F., and Shvedov, K.K. (1960), An Electromagnetic Method for Measurement of the Velocity of Explosion Products, Dokl. Akad. Nauk. SSSR 132, 1339-1340. 

In 1929 Lawrence invented the cyclotron, which instrument played (and still plays) an important role in nuclear physics. That work led directly to the award of the Nobel Prize in Physics for 1939, just one of his many honors. During World War II E. O. Lawrence made vital contributions to the development of the atomic bomb holding several high-level appointments in the Manhattan Project. He played an influential role in the decision to develop and later employ electromagnetic methods for uranium isotope separation (Calutrons) during the early 1940s. (Photo credit http //wikipedia.org, public domain)... 

Zirconium silicate occurs in nature as mineral zircon. Ore is mined from natural deposits and concentrated by various techniques (See Zirconium, Recovery). It is separated from sand by electrostatic and electromagnetic methods. 

Dremin Shvedov (Ref 3) measured by an electromagnet method the CJ pressure time of reaction in detonation waves of RDX, TNT, PETN, Tetryl, DINA, and of some of their mixts. The results obtd were significantly different from previous data. An attempt was made to explain this difference Refs 1) W.E. Deal, "Measurement of Chapman-Jouguet Pressure for Explosives", JChemPhys 27, 796-800(1957) 2) N.L. 

V.M. Zaitsev et al, "Electromagnetic Method for Measuring the Speed of Explosive... 

Aleksandrov et al (Ref 19) used the electromagnetic method to obtain what they term reaction times fas a function of input press P. For RDX of 1.8mm particle size at l.Og/cc they obtained the following ... 

For molecules situated in/at and interacting with a structured environment, it is important to determine molecular properties of the molecules when they are exposed to an external time-dependent electromagnetic field. Methods for doing... 

H. Karl, J. Fetzer, S. Kurz, G. Lehner and WM. Rucken Rroblem 28 An Electrodynamic Levitation Device, Testing Electromagnetic Analysis Methods (TEAM) Workshop, International Computing Society, Tucson, AR, 1998. 

Electromagnetic geophysical methods arc based on the study of the propagation of electric currents and electromagnetic fields in the earth. There arc two major modifications of electromagnetic methods one is based on direct current (DC), and another employs a transient electromagnetic field. 

In both cases the electric potential distribution recorded by the receiver electrodes is used to map the spatial resistivity distribution of the rock formation. The main limitation of the resistivity method is that direct current cannot penetrate through resistive formations. Electromagnetic induction methods, based on transient electromagnetic fields, overcome this difficulty because a transient field can easily propagate through resistors like a radiowave propagates in the air. At the same time,... 

Gusarov s theorem is a further generalization of this result for a 2-D geoelectrical model with a piecewise analytic distribution of electrical conductivity. The last two theorems make it feasible to apply the electromagnetic method for examining inhomogeneous geological structures of the earth. 

In most geophysical applications of electromagnetic methods, it is necessary to model geoelectrical structures of quite arbitrary shape and size, with anomalous conductivity varying in an arbitrary manner and not necessarily restricted to a local region. The most widely used approach to forward modeling of such problems is through the use of finite difference and finite element methods to find numerical solutions to Maxwell s equations written in differential form (Weaver, 1994 Zhdanov et ah, 1997). 

Electromagnetic potential equations and boundary conditions Another approach to the formulation of electromagnetic boundary-value problem is to use the electromagnetic potentials introduced in Chapter 8. This approach has been used in a number of publications on numerical electromagnetic methods (Biro and Preis, 1990 Everett and Schultz, 1996 Everett, 1999 Haber et aJ., 1999). 

Figure 12-5 The staggered grid for electromagnetic field discretization in the electromagnetic potential method. The normal components of electric field E are defined at the centers of the cell faces, while the tangential components of magnetic field H are defined on the cell edges.

Rogge also calcd that for propelling by electromagnetic method of a projectile weighing 750kg with muzzle velocity of lOOOm/sec from a barrel cal 38cm and 20 meters long, would require 100000 kilowatts, which is extremely hi ... 

Spectrometric methods Methods based on the absorption, emission, or fluorescence of electromagnetic radiation that is related to the amount of analyte in the sample. Spectrophotometer A spectrometer designed for the measurement of the absorption of ultraviolet, visible, or infrared radiation. The instrument includes a source of radiation, a monochromator, and an electrical means of measuring the ratio of the intensities of the sample and reference beams. 

Inducing an electromagnetic field eliminates the need for an electrode array and, therefore, the electromagnetic field method is a more rapid tool for surveying. The elimination of electrodes to measure electrical properties of subsurface materials also enables electromagnetic surveys to be conducted in many areas where resistivity surveys cannot be considered (i.e. pavement areas, very dry sandy soils, frozen ground, railroad tracks, etc.). Electromagnetic conductivity surveys may also be used to produce rapid continuous profiles up to depths of 15 meters. 

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