A new cable fault location method based on wavelet reconstruction is proposed. In this method the difference between the currents of faulty phase and sound phase under the high voltage pulse excitation is used as the measured signal and is decomposed in multi-scale by wavelet transform, then reconstructed in single scale. Comparing with traditional fault location method by travelling wave, the presented method will not be interfered by the reflected wave from the branch joint of cables or from other positions where the impedances are not matched and not be influenced by fault types, otherwise, the reflected waves can be recognized even the faulty position is near to the measuring terminal, at the same time, the influence of the wave speed uncertainty can be reduced. The correctness of the proposed method is proved by simulation results.
标签： method reconstruction location proposed
上传时间： 2016-02-04
上传用户：maizezhen
外国人开发的电磁时域有限差分方法工具包 Electromagnetic Finite-Difference Time-Domain (EmFDTD) is a basic two-dimensional FDTD code developed at the School of Electrical Engineering, Sharif University of Technology. This code has been written based on the standard Yee s FDTD algorithm. Applications include propagation, scattering, and diffraction of electromagnetic waves in homogeneous and non-homogeneous isotropic media for in-plane propagating waves. Negative permittivites or permeabilities as well as dispersion is not included. Zero, Periodic, and Perfectly Matched Layer boundary conditions may be selectively applied to the solution domain. The program is best suited for study of propagation and diffraction of electromagnetic waves in Photonic Crystal structures. EmFDTD is written in MATLAB language and has been tested under MATLAB 5.0 and higher versions.
标签： Finite-Difference Electromagnetic two-dimensio Time-Domain
上传时间： 2014-11-24
上传用户：watch100
It was proposed that perfect invisibility cloaks can be constructed for hiding objects from electromagnetic illumination (Pendry et al., Science 312, p. 1780). The cylindrical cloaks experimentally demonstrated (Schurig et al., Science 314, p. 997) and theoretically proposed (Cai et al., Nat. Photon. 1, p. 224) have however simplified material parameters in order to facilitate easier realization as well as to avoid infinities in optical constants. Here we show that the cylindrical cloaks with simplified material parameters inherently allow the zeroth-order cylindrical wave to pass through the cloak as if the cloak is made of a homogeneous isotropic medium, and thus visible. To all high-order cylindrical waves, our numerical simulation suggests that the simplified cloak inherits some properties of the ideal cloak, but finite scatterings exist.
标签： invisibility constructed proposed electrom
上传时间： 2013-12-18
上传用户：13215175592
We analyze, both analytically and numerically, the effectiveness of cloaking an infinite cylinder from observations by electromagnetic waves in three dimensions. We show that, as truncated approximations of the ideal permittivity and permeability tensors tend towards the singular ideal cloaking fields, so that the anisotropy ratio tends to infinity, the D and B fields blow up near the cloaking surface. Since the metamaterials used to implement cloaking are based on effective medium theory, the resulting large variation in D and B will pose a challenge to the suitability of the field averaged characterization of " and 碌. We also consider cloaking with and without the SHS (softand- hard surface) lining, shown in [6] to be theoretically necessary for cloaking in the cylindrical geometry. We demonstrate numerically that cloaking is significantly improved by the SHS lining, with both the far field of the scattered wave significantly reduced and the blow up of D and B prevented.
标签： effectiveness analytically numerically cloaking
上传时间： 2017-03-30
上传用户：zxc23456789
This book provides the reader with the basics in radio engineering, the techniques needed to generate, control, detect, and use radio waves. The text approaches the relevant problems both from the electromagnetic theory based on Maxwell抯 equations and from the circuit theory based on Kirchoff and Ohm抯 laws. Brief introductions to the electromagnetic theory as well as to the circuit theory are provided. Besides passive transmission lines and components, active RF circuits are also addressed.
标签： the engineering techniques provides
上传时间： 2014-01-17
上传用户：rocketrevenge
These codes require an ASCII input file called input.dat of the following form: Lower Limit on x Upper Limit on x Final Time Pressure for x<0 when t=0 Density for x<0 when t=0 Speed for x<0 when t=0 Pressure for x>0 when t=0 Density for x>0 when t=0 Speed for x>0 when t=0 These codes produce 8 ASCII output files: density.out. Density vs. x entropy.out. Entropy vs. x mach.out. Mach number vs. x massflux.out. Mass flux vs. x pressure.out. Pressure vs. x sound.out. Speed-of-sound vs. x velocity.out. Velocity vs. x waves.out. A description of the solution in terms of the three waves defined in the book (+,-,0).
标签： input following require called
上传时间： 2017-09-21
上传用户：希酱大魔王
DDSCAT 7.3 is a freely available open-source Fortran-90 software package applying the “discrete dipole approximation” (DDA) to calculate scattering and absorption of electromagnetic waves by targets with arbitrary geometries and complex refractive index. The targets may be isolated entities (e.g., dust particles), but may also be 1-d or 2-d periodic arrays of “target unit cells”, which can be used to study absorption, scattering, and electric fields around arrays of nanostructures.
标签： userguide
上传时间： 2015-04-29
上传用户：499689361
This book describes the applications of the fundamental interactions of electromagnetic waves and materials as described in the preceding volume, “Basic Electromagnetism and Materials”. It is addressed to students studying masters or doctorate courses in electronics, electromagnetism, applied physics, materials physics, or chemical physics. In particular, this volume analyzes the behavior of materials in the presence of an electromagnetic field and related applications in the fields of electronics, optics, and materials physics.
标签： Electromagnetism Materials Applied and
上传时间： 2020-05-26
上传用户：shancjb
The capability of radio waves to provide almost instantaneous distant communications without interconnecting wires was a major factor in the explosive growth of communica- tions during the 20th century. With the dawn of the 21st century, the future for communi- cations systems seems limitless. The invention of the vacuum tube made radio a practical and affordable communications medium.
上传时间： 2020-05-26
上传用户：shancjb
This book presents millimeter wave communication system design and analysis at the level to produce an understanding of the interaction between a wireless system and its front end so that the overall performance can be predicted. Gigabit wireless commu- nications require a considerable amount of bandwidth, which can be supported by millimeter waves. Millimeter wave technology has come of age, and at the time of writing the standards of IEEE 802.15.3c, WiGig, Wireless HD TM , and the European Computer Manufacturers Association have recently been finalized.
标签： Communication Millimeter Systems Wave
上传时间： 2020-05-28
上传用户：shancjb
