Calculation Of Field Strength Research Articles

A discussion of potential exposure metrics for use in epidemiological studies on human exposure to radiowaves from mobile phone base stations.

There is currently a high level of concern in many countries that exposure to radiowaves from mobile phone base stations may be hazardous to health. When investigating such suggested risks, epidemiologists need to define an exposure metric that can reliably discriminate between exposed and unexposed groups of people. We conducted a feasibility study to investigate if either short-term measurements of electric field strength, calculations of electric field strength, or distance from nearby mobile phone base stations could be used to develop a metric reflecting an individual's exposure to radiowaves. With electric field strengths in the range of 0.012-0.343 V/m, radiowaves from mobile phone base stations were found to give a material contribution to total exposure; however, stronger signals were frequently measured from other sources such as broadcast radio and television transmitters. Theoretical considerations and the measurements made during this work demonstrated that studies at the population level on suggested adverse effects of radiowaves from mobile phone base stations are not feasible since no valid metric for estimating historical exposures is currently available. The pace of radio infrastructure development is also such that today's measurements are unlikely to be good proxies for either past or future exposures. The complex propagation characteristics affecting the beams from base station antennas include shielding effects and multiple reflections from house walls and other buildings. These factors, combined with the presence of other environmental sources of radiowaves, cause distance from a base station to be a poor proxy for exposure to radiowaves indoors. It may be possible to adapt computer models developed by network providers to predict network coverage for epidemiological purposes; however, this has yet to be investigated. Furthermore, there is little evidence that presently justifies epidemiological studies being restricted to adverse effects of radiowaves from mobile phone base stations while neglecting radiowaves at other frequencies produced by different transmitters.

Micro-discharge at strip edge of silicon microstrip sensors

We have investigated the micro-discharge (micro-breakdown) phenomenon which is potentially a serious problem in operating in a high radiation environment. Numerical calculation of field strength for the model structure of the microstrip sensor gives us a quantitative understanding of each different cause of micro-discharge. The structure of the microstrip sensor can be optimized through this field calculation for suppressing the micro-discharge. We propose a new strip structure to suppress the micro-discharge.

“Spontaneous” desorption: A controlled phenomenon for surface analysis application? Part I: New evidence for a sputtering process induced by a well localized field enhanced desorption

The mechanism of Spontaneous Desorption Mass Spectrometry (SOMS) has been investigated through the use of extraction electrodes with circular aperture, in place of the more conventional grid system. High emission rates of contaminant and sample specific anions have been recorded from reference materials like CsI and phenylalanine. It is shown that the emission rate is controlled by the existence and the characteristics of the aperture edge such as sharpness or (and) rugosity. Geometrical shape and material composition of this well localized region also influence the emission rate and ion yields. Experimentally, the sample emitting zone has been determined in two ways: (1) from the variation of the emission yield of sample specific ions as a function of the deposit diameter and (2) from the lateral distribution of impacts of these ions after their flight path. Both experiments clearly show that this emitting zone (impact zone of the primaries) has a ring shape related to the circular aperture parameters. SIMION ion trajectory simulations and field strength calculations demonstrate that the primary ions are mostly emitted from the well defined edges (inner and outer) of the electrode. The emission rate is shown to decrease rapidly with time after the application of the extraction potential indicating both a degradation of the edge sharpness or microtips density and a decrease of adsorbates release.

Calculation of magnetic field strength for coil system designed to free from magnetic force and to confine the high .BETA. plasma.

The coil system designed to free from the magnetic force and to confine the high β plasma is proposed. We carry out the calculation of the magnetic field for the proposed coil by using the Biot-Savart law. It is noted that no or very weak magnetic fields are appeared in the central region of the proposed coil, while the strong magnetic field localizes at the outside of this region, being satisfied the requirement of confining the high β plasma.The simplified model is considered in order to reduce the cpu time for the computation. From the results of the computation, it is shown that the proposed coil is able to be replaced by the simplified model.

Horizontal parabolic equation solution of radiowave propagation problems on large domains

The modeling of radiowave propagation in the troposphere often involves field-strength calculations in very large domains, for which the usual parabolic equation techniques become prohibitively expensive. The horizontal parabolic equation method (HPE) provides a rigorous and efficient full-wave solution for this type of problem, taking advantage of the fact that refractive index perturbations in the troposphere are usually confined to a limited portion of the integration domain. Above the height where the medium becomes standard, Fourier and Laplace transform techniques are used to compute the field on a given horizontal, with convolution kernels based on exponential or Airy functions. The field on the initial horizontal may be obtained by any available method. The environment below the initial height may be range-dependent and include terrain variations. Substantial computing gains in both memory requirements and execution time are obtained. The method has been validated by comparison to the standard vertical PE. >

A three-dimensional field solution for axially-polarized multipole disks

A three-dimensional field solution is presented for axially polarized magnetic disks. The field components are expressed in terms of finite sums of elementary functions and are easily programmed. They can be used to determine the operating point of rare-earth multipole disk magnets. They are also useful for performing rapid parametric calculations of field strength as a function of material properties and dimensions.

Electron kinetics in a collision-dominated SiH4 rf plasma including self-consistent rf field strength calculation

The electron kinetics of a collision-dominated rf plasma in silane has been studied by solving the nonstationary electron Boltzmann equation. Ionization and attachment processes and the spatially averaged electron loss to the plasma wall by ambipolar diffusion have been included in the kinetic approach. This makes it possible to calculate, in addition to the time-resolved energy distribution, the self-consistent rf field amplitude which is necessary for the maintenance of the steady-state rf discharge. The impact of the rf field frequency, of the density ratio of negative ions to electrons, and of superelastic (second kind) collisions with excited silane molecules was studied. In particular, large, rf field amplitudes of about 100 V cm−1 Torr−1 result, connected with large modulations of the energy distribution for field frequencies in the megahertz region.

Current displacement of a solid cylindrical conductor placed in a semiclosed slot, taking into account the leakage field in the gap

The field problem is solved assuming a constant magnetic field strength in the middle of the slot opening. Adapting the vector potential in gap and conductor, which has been expanded into Fourier series and described in different coordinate systems, one obtains a system of linear complex equations for the Fourier coefficients. The calculation of surface current density and surface field strength is checked by measuring the bar current and comparing it with a value deduced from the measurement of the voltage drop at the surface of the bar. This comparison becomes significant due to the fact that these quantities converge badly and determine the bar impedance by means of Poyntings's vector. Finally a comparison is made with the normal approach, which has high practical importance, and which takes the magnetic field strength on the surface of the conductor as a given boundary condition. This comparison shows the advantages of the analysis presented over the conventional approximation. At last a finite element (FE) solution for this problem is given.

Calculation of electromagnetic field strength, reflectivity, transmission, and absorption of n-layer thin metallic films

We present a calculation of the fields within a metallic heterostructure system for the purpose of optimizing the scattering efficiency of one component. The example chosen is a Ge-Bi heterostructure. The calculation, carried out by a new technique which results in considerable simplification for the case of absorbing media, yields as well the field value within each layer of the heterostructure.

Empirical formula for groundwave field-strength calculation

A well known empirical formula for groundwave field-strength calculation has been found to be inaccurate under some conditions. An alternative formula which has a wider range of validity has been derived.

Propagation factors controlling mean field strength on urban streets

Calculation of mean field strength for urban mobile radio has been made on a ray-theoretical basis assuming an ideal city structure with uniform building heights. The result shows that building height, street width, and street orientation as well as mobile station antenna height are controlling propagation parameters in addition to the ordinary factors. The major theoretical characteristics agree approximately with experimental data including conventional empirical predictions. This suggests a way of theoretically predicting mean field strength in an urban area.

Calculation of maximum field strength for ferroprobe excitation

Calculation of maximum field strength for ferroprobe excitation

A device for increasing the insulating strength of an electrostatic accelerator column

A series of calculations of electrostatic field strength showed, that only by means of using a special “slipper-shaped” form for the column electrode profile can the field strength on the column surface be reduced by 30%, and the maximum field strength in a given accelerator - by 15% as compared to the case of a circular profile for the electrodes. An experimental check has confirmed that as a result of modernization the accelerator breakdown voltage increased by 14%.

Corona-onset field-strength calculations and the equivalent radius concept

The concept of the equivalent radius is examined in relation to its application to the evaluation of coronaonset field-strengths in atmospheric air. It is shown that the use of this concept provides erroneous values. The underlying reasons for this situation are discussed in detail, such that the basis for a physically meaningful approach to corona onset calculations is established.

Estimation of diamagnetic limitations to the fusion rate in a Migmacell

We describe a two-dimensional analytic calculation of the equilibrium diamagnetic field strength and shape, applicable in the regime of high magnetization to the high-energy low-angular-momentum ion orbits which characterize the distribution in a Migma fusion device.

A Modified Charge Superposition Method for the Calculation of Electric Field

A modified charge superposition method is proposed for the numerical calculation of electrical potential and field strength in the region where true charges exist on the boundary between two dielectrics. The validity of this method is demonstrated by the calculation of an example.

球状導体粒子近傍の電界ならびに粒子に働く力の計算と放電への応用

球状導体粒子近傍の電界ならびに粒子に働く力の計算と放電への応用

Semiautomatic optimization of external beam radiation treatment planning.

In this method, the operator/therapist is enabled to assign dosage constraints directly to points in the patient's cross section rather than field strengths as in the programmed console. Linear programming then solves for field strengths, optimizing for uniformity within the constraints imposed by the operator, and aiding also in the selection of wedges and beam directions. The iterative nature of the interaction between operator and machine is stressed. Two examples of treatment plans are simulated through the system. Computer calculation of field strengths combined with rapid interaction allows the therapist to examine more variations of beam directions than otherwise currently feasible.

Nomographs for Calculation of Field Strength

A method of calculating skywave field strength in tropical region was developed in the Research Department, All India Radio. This is based on results of ionospheric absorption and field strength measurement conducted by the department. In order to enable easy estimating of skywave field strength by this method at any distance, for any mode of propagation, for any height of reflecting layer and for any operating frequency at any time of the day of any month during any phase of sunspot activity, a set of graphs has been prepared. These are based on the method of progressive substitution for solving an equation. The above field strength method and the details for reading field strength from the graphs are given in this paper.

Calculation of electric field strengths at a sharp edge

The sharp edge of a typical carbon-steel razor blade may be approximated by a hyperbola. The electric field at the vertex of the edge can then be calculated by the method of the conformal transformation. Equations are deduced for a blade above a plate and for a blade above a rod. The results are considered in relation to the use of blades in field ionisation mass spectrometry.