This article describes the motivation and basis of magnetic energy harvesting project. Magnetic field is a reusable energy source to be used for both energy harvesting and wireless power transmission applications. From a human effects perspective, ICNIRP2010 provides a guideline for acceptable electromagnetic field level. In this project, "environmental magnetic field" means this acceptable magnetic field level. The main purpose of this project is to provide both of "self-generating parts" and "killer applications" using environmental magnetic fields.
In this report, an application of vibration energy harvester for MEMS wireless sensor systems was described. The MEMS vibration harvester is one the great candidate for maintenance free power source for the wireless sensor network (WSN) and system e.g. the IoT and the Trillion Sensors Universe. By introducing some researches for the human monitoring WSN and two types of vibration harvester based on an electromagnetic and an electrostatic (electret) technologies, the present situation of vibration harvesters and their goal were summarized in the article.
Parametric pendulum inherently exhibits a conversion from a vertical vibration into its rotational motion. The converting motion, which can directly drive a rotational generator, is associated with energy extraction from vibrations and movements of nature. The nonlinear characteristics of the parametric pendulum present various issues as well as the simple converting mechanism for the conversion of vibrational energy. This review article describes the dependences of the converting motion on the initial states and the excitation parameters and then the proposed methods to resolve the issues. In addition, we explore the application potentiality of the parametric pendulum for wave energy conversion.
Magnetostrictive alloys are promising materials for realizing vibration energy harvesting technology, as they enable us to convert kinetic energy to electric energy. These materials are used as smart materials for actuators and sensors. Among these materials, iron based magnetostrictive alloys are attracted since they reveal the superior magnetic properties such as large magnetostriction and high permeability, as well as the good mechanical properties. The present paper describes the present status and prospect of these magnetostrictive alloys. In particular, the physical properties such as elasticity and magnetostriction of iron-gallium binary alloys are overviewed.
In this research, the Singular Spectrum Analysis (SSA) was applied for the prediction of time series data. A simulation method was developed to predict the location of the human lung tumors during breathing. The prediction results showed good agreement with the measured data and they showed hopeful possibility to be applied for the chasing radiotherapy technology.
A characteristics calculation of induction motors is rather complicated in closed-slot induction motors. The inductance of a closed-slot bridge, that is, its leakage reactance has been problematic due to saturation of a magnetic steel sheet at a bridge. In this paper, the inductance characteristics of a closed-slot induction motor are studied with an experiment and finite element method (FEM) analysis. In the experiment, the flux linkage of a model rotor was measured by a search coil and was compared with FEM results. The inductance of a closed-slot bridge and the other rotor leakage inductances of a closed-slot induction motor were also calculated with magnetic energy and magnetic co-energy obtained from FEM from slip 0.25% to 100%. This paper makes it newly clear that a bridge inductance drastically increases around the rated speed of a closed-slot induction motor and it composes most of the rotor leakage inductance. In less than 60% speed, the bridge inductance is about half of the rotor leakage inductance. The bridge inductance of a closed-slot rotor also has a peak in small bar current region as the magnetic permeability of a magnetic steel sheet has a peak value.