Analysis of low-frequency circular cylindrical induction devices having helical windings

In Human Body Communication, it is important to investigate the input impedance characteristics of the electrodes for improving the qualities of communication. For rapid analysis and development of phantom, an approximation model is needed. In this paper, we proposed newly developed homogenous human arm model which consists of single material. Input impedance characteristics of the homogenous model were compared with that of conventional model which has a multilayered cylindrical structure. As a result, it was found that the input impedance characteristics obtained from two models were well consistent at 10 MHz. On the other hand, it was found that transmission characteristics and electric fields around the model were different in each model.

A concentric cylindrical cloak is showed here to achieve the acoustic cloaking phenomenon. The introduced structure consists of MNE layers and water in MNE substrate in the MHz frequency range. Due to avoiding the incoming acoustic waves by the shell, the object can be hidden inside the cylindrical area of any shape. In order to improve the quality of cloaking, we have optimized the desired shell by considering the manufacturing technology. We show that an optimized, acoustic cloak based on composite lattice structure can reduce the scattering of an object more than a 20-layer realization of acoustic cloak based on multilayer cylindrical structure. This design approach can substantially simplify the fabrication of cloaking shells. In this research, to study the acoustic distribution of the desired structure, finite element method (FEM) has been used to analyze the structure in two dimensions and a cloak of natural materials with isotropic properties has been designed using effective medium theory.

This paper describes the fault classification and detection of SVC (Static VAR Compensator) integrated differential relay based double circuit transmission line applying Discrete Wavelet Transform (DWT) approach. The SVC is placed at mid-point of circuit-I of double transmission line. The other circuit (circuit-II) remains uncompensated. The differential relay based protection scheme is used for the analysis of fault detection and classification. The process starts by extracting current signals (A, B or C-phase) from both sending and receiving end of the transmission line synchronously and processes through DWT to obtain the spectral energy (SE) at both the end of the line. The Differential Spectral Energy (DSE) of each phase current signals are obtained by SE of current measured at sending end minus SE of current measured at receiving end. This DSE value is used to register the fault pattern.

By the excitation of the electromagnetic signal, double transmission line will inducing a voltage and current, thereby creating the space radiation field. Based on infinitesimal current source radiation field and by the convenience of the terminal response aspects of solving transmission line of BLT equation, the double transmission line is derived and gets the analytical solution.

This project is partly supported by NSFC Grant 51207146, RAEng Research Exchange scheme of UK and EPSRC EP/K01496X/1.Superconducting cable is an emerging technology for electricity power transmission. Since the high power capacity HTS transmission cables are manufactured using a multi-layer conductor structure, the current distribution among the multilayer structure would be nonuniform without proper optimization and hence lead to large transmission losses. Therefore a novel optimization method has been developed to achieve evenly distributed current among different layers considering the HTS cable structure parameters: radius, pitch angle and winding direction which determine the self and mutual inductance. A prototype HTS cable has been built using BSCCO tape and tested to validate the design the optimal design method. A superconductor characterization system has been developed using the Labview and NI data acquisition system. It can be used to measure the AC loss and current distribution of short HTS cables.

This paper presents the development of the cross differential relay. The new relay is suitable to double circuit HV transmission lines. Based on basic principle of cross differential relay, the paper introduces a percentage cross differential current elements used to improve sensitivity of cross differential relay. To improve stability of cross differential relay, voltage elements are used to distinguish between fault and open circuit condition, and phase selector elements are used to block healthy phase elements. EMTP simulations and real time digital simulator system (RTDS) tests prove that the cross differential protection is able to offer correct responses under various system and fault conditions.

The integral equation (IE) method is one of the efficient approaches for solving electromagnetic problems, where dyadic Green’s function (DGF) plays an important role as the Kernel of the integrals. In general, a layered medium with planar, cylindrical, or spherical geometry can be used to model different biomedical media such as human skin, body, or head. Therefore, in this chapter, different approaches for the derivation of Green’s function for these structures will be introduced. Due to the recent great interest in two-dimensional (2D) materials, the chapter will also discuss the generalization of the technique to the same structures with interfaces made of isotropic and anisotropic surface impedances. To this end, general formulas for the dyadic Green’s function of the aforementioned structures are extracted based on the scattering superposition method by considering field and source points in the arbitrary locations. Apparently, by setting the surface conductivity of the interfaces equal to zero, the formulations will turn into the associated problem with dielectric boundaries. This section will also aid in the design of various biomedical devices such as sensors, cloaks, and spectrometers, with improved functionality. Finally, the Purcell factor of a dipole emitter in the presence of the layered structures will be discussed as another biomedical application of the formulation.

A high precision triangular laminated anisotropic cylindrical shell finite element

Hundreds of thousands of kilometres of pipelines run on the ocean floor all over the globe. They represent the main oil & gas means of transportation from offshore structures. They are expensive and critical assets for production companies. Therefore their integrity as a structure is a key element for sustainable ocean exploitation. Blockages caused by wax or hydrates are serious production problems. Localisation and characterisation of blockages remains a big issue for production companies. Currently there are no efficient technologies to detect and characterise blockages from outside the pipeline. In this paper we develop the acoustic scattering theory for multi-layer co-centrical cylindrical structure and propose an analytic solution to the problem. We demonstrate that using WideBand Sonar (WBS) technology, it is possible to detect effectively blockages within a pipeline. Blockage scenarios are investigated using both simulated and real data.

This article presents a synthetic aperture radar (SAR) imaging algorithm based on a compressed sensing (CS) reconstruction approach, which is suitable for the detection of foreign object debris (FOD) located in a multilayered circular dielectric structure for nondestructive testing (NDT) application. The method proposed considers the refraction model at the boundaries between each two adjacent layers. This method is different from free space as imaging background assumption in previous CS-based SAR imaging applications. In addition, the prior information that the FOD is displayed with a sparse distribution is applied. Therefore, the method proposed could obtain better focus on effectiveness than time-reversal imaging algorithm with the same measurement points. Further, the CST simulations and the experiment were conducted by taking two small metallic targets as FOD embedded in the three-layered circular dielectric structure. The results of simulations and experiment demonstrated that the proposed method has better effect than previous methods.

The double circuit EHV transmission lines have been widely used because of its many advantages. But when faults occur, the style of fault and the operation condition are more complicated than that on the single circuit transmission line. The faults occurred on the transmission lines is mainly transient fault. The auto-reclosure is normally applied after the fault line tripped to improve the power supplies reliability and the power system safety. But if the fault is permanent and the auto-reclosure reclosed accordingly, the power system and its apparatus will suffer short circuit current again, resulting further damage of the equipment and making power system instability. Thus, it is very important to distinguish the transient and permanent fault before the tripped fault line auto-reclose. If the EHV line has shunt reactor, identification of fault nature becomes even more difficult. There are several methods proposed for distinguishing the transient and permanent fault but mainly for single circuit transmission line. In this paper, a novel method is proposed for the EHV double circuit transmission lines with shunt reactor. After tripped, the phase voltage across shunt reactor was calculated using our established transient fault line model regardless of the fault is transient or permanent. The difference between the calculated voltage and the measured voltage of the fault phase across shunt reactor was employed to identify transient or permanent fault. The amplitude ratio, i.e. the difference of the voltage between calculated and measured to the voltage across neutral reactor was used to judge fault nature. If the amplitude ratio is greater less than 1, the fault is regarded as transient. If it is more than 1, it is regarded as permanent. This result can be further verified by EMTP simulation.

Transmission lines are generally subjected to faults, so it is advantageous to determine these faults as quickly as possible. This study uses an Artificial Neural Network technique to locate a fault as soon as it happens on the Doukan-Erbil of 132kv double Transmission lines network. CYME 7.1-Programming/Simulink utilized simulation to model the suggested network. A multilayer perceptron feed-forward artificial neural network with a back propagation learning algorithm is used for the intelligence locator's training, testing, assessment, and validation. Voltages and currents were applied as inputs during the neural network's training. The pre-fault and post-fault values determined the scaled values. The neural network's performance was evaluated, and tests were run. Line-to-ground faults were examined. The study demonstrates how effective, rapid, and precise this method is at locating faults. The neural network's performance was examined, and tests were run on it. The overall performance of the mean square error in the trained network execution was 0.11792 at 35 epochs. The correlation coefficient at the entire target was 0.99987 percent of an error on the Doukan-Erbil double transmission lines.

Obstacle recognition and location is one of the key techniques for the autonomous transmission line inspection robot. Considering the structure of 220kV double split transmission line, a method of obstacle recognition and location based on the monocular vision is proposed. First of all, capture the image located ahead of the inspection robot with camera, and recognize such obstacles as spacer, counterweight, etc in the image. Then build the geometric model of ranging using the position relation of obstacle's location center and camera, and calibrate the camera's intrinsic parameters. At last, put the parameters obtained by calibration into ranging formula to perform the ranging tests. The tests indicate that the method can recognize and locate the obstacles effectively.

Purpose – The purpose of this paper is to give a simple, fast and universal inductance calculation approach of slotless-winding machines and comparison of inductances of toroidal, concentrated and helical-winding machines, since these winding types are widely used among low-power PM machines. Design/methodology/approach – Harmonic modeling approach is applied to model the magnetic field of the windings in order to calculate the synchronous inductances. The method is based on distinction between electromagnetic properties of different regions in the machine where each region is represented by its own governing equation describing the magnetic field. The governing equations are obtained from Maxwell’s equations by introducing vector potential in order to simplify the calculations. Findings – Results of the inductances of toroidal, concentrated and helical-winding slotless PM machines, which have the same torque and dimensions, obtained by the proposed analytical method are in good agreement with 3D FEM, where the relative difference is smaller than 15 percent. However, the calculation time of the analytical method is significantly less than in 3D FEM: seconds vs hours. Additionally, from the results it is concluded that the toroidal-winding machine has the highest inductance and DC resistance values among considered machines. Helical-winding machine has lowest inductance and DC resistance values. Inductance of concentrated-winding machine is between inductance of helical and toroidal windings; however, DC resistance of the concentrated windings is comparable with resistance toroidal windings. Originality/value – In this paper the inductance calculation based on harmonic modeling approach is extended for toroidal and helical-winding machines which makes the method applicable for most of the slotless machine types.

An eigensolution expansion of dyadic Green's function for cylindrical sector structures is presented. The cylindrical structure is limited in azimuthal direction by electric or magnetic walls. Due to orthogonality of the eigensolution functions between the walls, the derivation of the dyadic Green's function can be done in spectral domain. The Green's dyad is used to set up an electric field integral equation for the microstrip structure. The solution is carried out with the method of moments. Numerical results for input impedance and radiation pattern are shown.