External Electromagnetic Sources Research Articles

Double Bits Error Correction for Computational Grid with CRC

In grid system error during sending information due to devastating factors like external electromagnetic sources and noise is inevitable. The Cyclic Redundancy Check (CRC) method is used for error detection. CRC is used to control such factors in received information. In this paper, the new method based on CRC has been introduced that is able to detect the exact place of double bits error and correct them. In this method the receiver divide the received data on polynomial generator, g(x), and then get the remainder. Receiver can correct double bits error by comparing the remainder and the content of the look-up table. The result show that presented method can reduce the traffic for application that have low bit error rate (BER).

Equivalent Circuit Model of a Bundle of Cables for Bulk Current Injection (BCI) Test

A "simulation program with integrated circuit emphasis" (SPICE) model for the evaluation, in frequency and time domain, of the coupling of a bundle of shielded coaxial cables with an external electromagnetic source such as a bulk current injection clamp, is developed. The proposed equivalent circuit takes into account the presence of the transfer impedance and the presence of the transfer admittance, and it does not need the subdivision in elementary cells. Intermediate results are validated by comparing the exact numerical solutions with the output of the SPICE circuit, and the final results are validated by means of comparison with measurements carried out on an experimental setup. The feature selective validation (FSV) technique is used as a measure of the comparisons

Interference and Implantable Cardiac Stimulators.

As pacemakers and defibrillators are electronic devices that elaborate electrical signals, they are by nature sensitive to electromagnetic signals. The crucial problem is not so much to establish which devices are susceptible to such physical phenomena, but rather to determine threshold levels and the precautions required to ensure that the devices function properly. The preferential pathways of interference between an external electromagnetic source and an implanted device are constituted by catheters, antennas used in telemetry, magnetic switches, and rate-responsive sensors; that is to say, those components which in some way communicate with the external environment. The human body, which is a fairly good conductor of electricity, acts as an effective shield against electrical fields surrounding the patient, thereby intrinsically protecting the implanted device. The internal microprocessor and electronic interfaces are based on the c-mos technology, which is sensitive to ionising radiation that can alter the conduction thresholds of the transistors. Moreover the electronic components and the ceramic base supporting them can be mechanically damaged by high power vibrations like high power ultrasounds. The aim of this review is to summarise the recommendations for all professionals managing patients with an implanted cardiac stimulator in case of interference most frequently encountered in hospital, at home and in everyday life. keywords: Pacemacker, DeWbrillator, Interference.

Full SPICE model for transfer impedance and transfer admittance inclusion in shielded coaxial cables analysis

A SPICE circuit model for the evaluation, in both the frequency and time domains of the coupling of a shielded coaxial cable with an external electromagnetic source is developed. The proposed equivalent circuit takes into account the presence of both the transfer impedance, and the transfer admittance and does not need this subdivision into elementary cells. All needed computations are executed, in the form of equivalent active and passive networks, inside the SPICE environment without needing to resort to external CAD tools. The intermediate and final results are validated by means of a comparison with results evaluated by independent methods.

Surface Waves and Forced Oscillations in QHE Planar Samples

Dispersion relations and polarizations for surface waves in infinite planar samples in the QHE regime are explicitly determined in the small wavevector limit in which the dielectric tensor can be considered local. The wavelength and frequency regions of applicability of the results extends to the infrared region for typical experimental conditions. Then, standard samples with millimetric sizes seem to be able to support such excitations. Forced oscillations are also determined which should be generated in the 2DEG by external electromagnetic sources. They show an almost frequency independent wavelength which decreases with the magnetic field. A qualitative model based in these solutions is also presented to describe a recently found new class of resonances appearing near the edge of a 2DEG in the QHE regime.

Many-body approaches to atoms and molecules in external magnetic fields

The proper treatment of many-body effects for fermions has long been a goal of theorists working in atomic and molecular physics. The computational demands of such a treatment, however, when coupled to the added difficulties imposed by the presence of external electromagnetic sources, have resulted in few studies of many-body effects in strong magnetic fields, i.e., in the field regime where perturbation theory is no longer applicable. In this article, we review the fundamental aspects of the problem and describe a variety of theoretical approaches for small atoms and molecules in strong fields, beginning with mean-field theory (Hartree–Fock) and progressing through variational and exact stochastic methods. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 64: 523–552, 1997

Response of underground multiconductor cable systems to external fields illumination

The paper presents a novel model and its equivalent transmission line equations (ETLEs) for analysing the coupling of external electromagnetic sources to underground multiconductor transmission systems. The earth conduction effect, earth surface boundary, mutual coupling among multiconductors and impressed fields are all taken into account and described simultaneously in the same ETLEs utilising equivalent transmission parameters. Although the model is developed by employing a series of mathematical transforms, its general and closed representations in the form of ETLEs are simple and intuitive, and can easily be applied to calculate coupling and interference problems in many engineering applications. An application of this model to conductive coupling to a two underground conductor system is shown to be in good agreement with experimental results.

Transient response of a microstrip line circuit excited by an external electromagnetic source

The transient voltages and currents induced by an external electromagnetic field along a microstrip line interconnecting active and/or passive components are studied by using a distributed-source transmission-line model. The influence of the angle of incidence as well as that of the microstrip geometrical and electrical parameters on the line response is analyzed. The instantaneous voltage and power induced on the loads by various types of pulse excitations are computed. Numerical results are obtained both for dispersive and nondispersive lines. A line feeding a transistor microwave amplifier is also considered. The results show the effects of the multiple reflections of the field inside the dielectric substrate and of the signal at the ends of the line. Indications of how to reduce the coupling between the external field and the considered structure are given.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A design technique for minimizing the electromagnetic interference induced along a microstrip line by external sources

AbstractThis work shows that embedded‐strip microstrip lines may be usefully adopted in microwave integrated circuit applications when minimization of the interference caused by external electromagnetic sources is required. A design procedure for minimizing the interference induced by external sources in the proposed structure is suggested.

Spectral Theory of Transmission Lines in Presence of External Electromagnetic Sources

ABSTRACT The analysis of the coupling of electromagnetic pulses with transmission lines is rigorously formulated in the spectral domain by means of a Fourier transform, on the line axis, of the currents and of the total electromagnetic field. By means of this formulation, the validity of the telegrapher model and its limitations are clearly assessed; and the spectral domain counterpart of the telegrapher model is presented along with the modifications required to deal with transmission lines over an unperfectly conducting ground. To demonstrate the usefulness of the spectral theory on a practical case that cannot be studied by the telegrapher model, the formal solutions of the problem of a single buried wire of arbitrary length are obtained, by means of the Wiener-Hopf technique. A discussion of the numerical methods that can be used to solve the general equations obtained by the spectral theory is also included.