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Transcranial magnetic stimulation (TMS) is a non-invasive neuro-stimulation based on the principle of electromagnetic induction that uses brief, strong magnetic pulses of electric current delivered to a coil placed on the subject’s head to induce an electric field in the brain. This electric field could stimulate and modulate neural activity. Induced E-field inside brain generated by repetitive TMS (rTMS) can produce changes in neural activity that extends beyond the period of stimulation. Therefore, rTMS can be used as a probe for exploring higher brain functions and as potential treatment technique for psychiatric and neurological disorders. However, based on the chosen shape of the excitation coil, there exists a tradeoff between the excitation focality in the brain and the depth to which the field penetrates. In this paper, a new design of TMS coil is proposed to enhance the performance of the traditional figure-of-eight (FOE) coil. 3-D finite-element method has been used to simulate and compare the electric field induced inside the model of a human brain under the influence of both coil designs. An experimental verification was then followed to validate the advantages of the proposed coil design over the classic FOE coil. [ABSTRACT FROM AUTHOR]

The double-stator configuration of the switched reluctance machine (SRM) aims to maximise the energy conversion efficiency by optimising the ratio of motional force to the total magnetic force. Maintaining the attractive features of SRM, the double-stator switched reluctance machine (DSSRM) proves to have higher torque/power density than the conventional SRM, which is a crucial feature for traction applications. The original winding configuration used in DSSRM is the full-pitch winding, which yields high-power density but causes significant heat within the machine's end windings. As end windings do not take part in torque generation, concentrated windings were proposed to reduce the heat as well as to reduce the size, cost, and weight of the machine. This study provides a detailed comparative analysis of the effects that the winding configuration has on the performance of a 100 kW DSSRM, with emphasis on flux density distribution, efficiency, and heat generation. It is concluded that the concentrated windings are a better alternative to the full-pitch windings in DSSRM. [ABSTRACT FROM AUTHOR]

Pulsed cold plasma reforming is a novel method to harvest hydrogen from hydrocarbons. The harvested hydrogen can feed a fuel cell for distributed generation of electricity in a stationary or mobile platform. The cold plasma arc is generated by a pulsating high voltage waveform. The arc rotates in the magnetic field caused by a ring permanent magnet, thus increasing the collision area between the arc and the fuel. Due to the difficulties of measurement of plasma properties such as ion and electron temperature without disturbing the plasma, multiphysics simulation is a key step in the design of electrodes, thereby increasing the hydrogen harvest rate in the syngas. In this paper, a 3D multiphysics simulation including fluid dynamics, thermal response, and electromagnetic fields has been carried out to assist in selection of the permanent magnet. Experiments were carried out to verify the simulation results. The 3D multiphysics simulation is demonstrated to be an effective tool to assist in the design of the reformer. The hydrogen harvest rate has been improved from 58.7% to 67.8% with the introduction of the magnet. [ABSTRACT FROM AUTHOR]

This paper proposes a stability optimization method based on virtual resistor and nonunity voltage feedback loop for cascaded dc–dc converters. Oscillating phenomenon or instability would occur occasionally with two or more closed-loop dc–dc converters in series. The virtual resistor and nonunity voltage feedback are used to modify the feedback loop instead of only a direct voltage feedback to improve stability and get rid of oscillating behavior. Based on the stability analysis of dc–dc converters with distributed parameters, several cases have been derived. After that, relative to different cases, two modified methods based on virtual resistor and nonunity voltage feedback loop are proposed to stabilize the overall system. With these methods, no extra power loss would be generated, and it is easy to embed them into any conventional control system. Experimental results verified the theoretical analysis and feasibility of the proposed control methods. [ABSTRACT FROM PUBLISHER]

This paper presents an optimal design for the rotor of a double stator switched reluctance machine. The effect of the rotor shape on the torque profile is analyzed first. Due to the nonlinearity of magnetic core and complex geometry, an iterative approach is developed to automatically shape the rotor geometry using static finite element method. The rotor of a 12/8/12 prototype is optimized. Simulation results validate the effectiveness of the optimal design. [ABSTRACT FROM PUBLISHER]