The field of harvesting electrical energy from ambient vibration has grown with rapid interest. Perpetual source of electrical energy can be extracted from structural vibrations. The paper deals with a technology for scavenging electricity from vibration using iron-gallium alloy. This alloy offers high ductile property and the effect of inverse magnetostriction is also quite high. In this paper, a bending type magnetostrictive prototype energy harvester has been considered. Volume of the used material is 7 × 2 × 42 mm3. Forced & free vibration characteristics have been examined on this prototype. Maximum conversion efficiency of 49% has been achieved at input frequency of 30 Hz.

Abstract-This paper represents the force calculation in a radial passive magnetic bearing using Monte Carlo technique with general division approach (s-MC). The expression of magnetic force is obtained using magnetic surface charge density method which incurs a multidimensional integration with complicated integrand. This integration is solved using Monte Carlo technique with 1-division (1-MC) and 2-division (2-MC) approaches with a MATLAB programming. Analysis using established methods such as finite element method (FEM), semi-analytical method, and adaptive Monte Carlo (AMC) method has been carried out to support the proposed technique. Laboratory experiment has been conducted to validate the proposed method. 2-MC gives better result than 1-MC. The computation time of the proposed method is compared with the quadrature method, FEM and AMC. It is observed that the proposed method invites less computational burden than those methods as the algorithm adaptively traverses the domain for promising parts of the domain only, and all the elementary regions are not considered with equal importance.

This paper presents a consideration of the nonlinear modelling and vibration control of a hybrid magnetic bearing (HMB). The dynamics of the system are highly nonlinear in nature and exhibit parameter uncertainty. A sliding mode controller (SMC), well known for its robustness against parameter variation and external disturbance attenuation, was used, in the form of an adaptive sliding mode controller (ASMC), chosen because the ASMC operates in the absence of knowledge of the upper bounds of the system uncertainty, and its tracking performances are guaranteed. The HMB–ASMC system was simulated with varying system parameters and the performance of the controller is discussed. A laboratory prototype of the HMB system was built and experiments were carried out with the ASMC controller, which was found to offer acceptable vibration characteristics and disturbance attenuation.

Abstract-This paper represents a new simple technique to calculate force between two ring magnets using adaptive Monte Carlo integration technique. Elementary magnetic force is calculated by discretizing the pole faces of the passive magnets into tiny surfaces. To obtain the resultant force, this elementary force equation is integrated over the dimensions of the ring magnets which incur a multidimensional integration with complicated integral function. This multidimensional integration is solved using adaptive Monte Carlo technique considering singularity treatment and importance sampling. This method is advantageous over existing analytical or quasi analytical methods regarding singularity treatment and computational burden. It is more flexible, especially for using in digital computer. The result of the proposed technique is verified with finite element method and also validated by laboratory experiment. It is observed that the proposed result matches very well with the practical test result, particularly if self demagnetization is considered. So taking into account of simplicity, less computational burden and usefulness, the proposed method may be an alternative choice for magnetic force calculation.

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