Reciprocating Flux-Concentrated Induction Generator for Free-Piston Generator

This paper presents and examines a self-excited tubular induction generator for a free-piston generator system. The induction generator utilizes flux concentration by eddy currents. The paper shows that leakage flux is thereby reduced in the proposed generator and its performance is greatly improved. A three-dimensional finite-element method is employed to investigate its performance. A comparison of the calculated and measured results for standstill thrust force confirms the validity of the model

Coupled Finite-Element/Boundary-Element Analysis of a Reciprocating Self-Excited Induction Generator in a Harmonic Domain

This paper suggests a general method for analysis of a reciprocating self-excited induction generator based on the coupled finite-element/boundary- element method in a harmonic domain. The finite-element method is used for iron and copper parts in order to deal with nonlinearity and eddy currents, while the boundary-element method is utilized for the air-gap region between the moving parts using a free-space Green function that facilitates the application of a linear time periodic movement. The proposed method leads to a static global matrix that is symmetrical for particular boundary conditions. The results agree well with those obtained by the time-stepping methods

Finite Element Analysis of Galfenol Unimorph Vibration Energy Harvester

This paper develops a numerical model to examine the performance of the vibration energy harvester with one-rod (unimorph) of Iron-Gallium (Galfenol). The device\u27s principle of operation is based on inverse magnetostrictive effect of the Galfenol rod. In order to take into consideration the anisotropy of the Galfenol, the Armstrong model is employed that is implemented into a static 3-D finite element model (FEM) of the energy harvester. The predicted results from the numerical model are compared to the measured ones

Heat Generation Ability of Ferromagnetic Implants in Hyperthermia

In this paper, proposed implants in literature are compared in terms of the ability to heat generation in electromagnetic thermotherapy. To destroy the tumor cells, their temperature must rise above 42.5oC. The magnitude of the temperature rise depends strongly on the thermal conductivity of the tissue that has not been considered in most studies. For this reason, liver tissue is modeled using bioheat transfer equation that is coupled to the electromagnetic equations and electrical circuits by employing Multiphysics finite element package COMSOL, in order to create the numerical model of the system

Spatial detection of ferromagnetic wires using GMR sensor and based on shape induced anisotropy

The purpose of this paper is to introduce a new technique for row spacing measurement in a wire array using giant magnetoresistive (GMR) sensor. The self-rectifying property of the GMR-based probes leads to accurately detection of the magnetic field fluctuations caused by surface-breaking cracks in conductive materials, shape-induced magnetic anisotropy, etc. The ability to manufacture probes having small dimensions and high sensitivity (11 mV/mT) to low magnetic fields over a broad frequency range (from dc up to 1 MHz) enhances the spatial resolution of such a probe that is applicable to eddy current testing (ECT) techniques. Here, an AC uniform magnetic field is formed using a Helmholtz coil in which by scanning the probe over an array of acupuncture needles, the distances between them are detected. The results verified the possibility and the performance of the proposed row spacing measurement using GMR sensor