The electric field in numerical human models has been used as an evaluation metric in the last 30 years. Recently, multiphysics, multi-scale modeling, and fast computation methods have advanced the state of the art in electrostimulation. These methods combined with image processing and machine learning are expected to bring personalized medicine in the near future. In this review, we presented two examples of electrostimulation; nerve root stimulation and brain stimulation. For the latter example, machine learning is demonstrated to successfully estimate the induced electric field in the brain.

The very fast transient electromagnetic field is generated by discharge events. Especially, the micro-gap electrostatic discharge (ESD) of less than 1 kV voltages produces an impulsive electromagnetic noise having more than 10 GHz frequency bandwidth. The ESD noise is menace to cause malfunction of high-tech electrical equipment and systems. So far, many studies have been made on electromagnetic noise of ESDs from the viewpoint of electromagnetic compatibility (EMC). Then, the electromagnetic noise characteristics of the ESDs are gradually becoming clearer. In this paper, here is the recent research trend on EMC issues of discharge event and the specificity of electromagnetic noise caused by the micro-gap ESD.

Renewable energy generation systems such as photovoltaic and wind are introduced positively in the world, and smart grid is focused on in order to optimize relation between these generation systems and power users. Since the smart grid is composed of facilities such as generation, transmission, distribution and secondary battery systems, there are emission problem emitting disturbance from the facilities and immunity problem in which the facilities malfunction by external disturbance, that is, EMC problem. In this report, as EMC problem related to the smart grid, (1) smart grid approach on IEC/SMB (Standard Management Board), (2) EMC problem related to a smart meter, (3) emission standard for a photovoltaic generation system, (4) emission standard for WPT (Wireless Power Transfer) equipment, are introduced.

We review a system that performs accurate computation of body temperature elevation and sweating by combining electromagnetic and thermal analysis with weather forecast data toward the risk assessment and management. We validate our computational code by comparing with different exposure scenarios, and then extend to estimate allowable time of firefighters as a computational example. We also review our newly-designed system for public enlightenment toward reducing heat stroke patients. Finally, we apply the system to estimate the number of patients of heat stroke in summer.

A fast-transient electromagnetic field is emitted by an electrostatic discharge (ESD) event. The field caused by an ESD often gives a serious impact on electric/electronic equipment/facilities. Especially, a micro-gap discharge below 1 kV produces broadband electromagnetic noises of which frequency is more than several gigahertz. Therefore, we investigate an emission mechanism of transient electromagnetic fields due to the ESD event by using spherical electrodes. In this paper, the electric-field waveforms were measured using an optical electric-field sensor to elucidate the mechanism of the ESD event. As a result, we concluded that the measured electric-field represent a feature of as including a quasi-static field, an inductive field, and a radiation field. It was confirmed that the mechanism of electromagnetic emission caused by the ESD in spherical electrodes could be explained as a dipole-radiation model.

In this paper, a two-variable multi-pole Debye relaxation model with additional static conductive term is proposed to model complex permittivity of expanded polystyrene mixed with graphite powder obtained from the measured data. This data was available in the frequency range 0.4-5GHz and the carbon content range 2-30 kg/m³. The parameters of the proposed model are empirically modeled as a linear and quadratic function of carbon content. It is shown that using the proposed model a time domain calculation of broadband characteristics of wave absorbers containing this composite material is enabled. To evaluate the proposed model for a time domain broadband calculation, numerical simulations of the wave absorbers with different structures (planar and pyramid) are performed by the finite-different time-domain (FDTD) method. The results of the simulations are compared with those obtained by other techniques and good agreement is obtained.

Sufficient evaluation for effects caused by electromagnetic interference is required, since faults in information processing inside ICs may cause not only data destruction but also security deterioration. Effect evaluation methods focusing on processing inside ICs have not been sufficiently studied. In this paper, we propose an effect evaluation method using an evaluation circuit that can detect setup time violation (STV), which is one of mechanisms of fault occurrence inside ICs caused by external noises. The evaluation circuit has a long path delay. Since the output of the evaluation circuit changes depending on the clock cycle, it is possible to detect occurrence of the STV. To confirm the possibility to detect STV occurrence using the evaluation circuit, we conducted the experiment to generate STV by inserting a glitch simulating electrostatic discharge into the clock signal in the target circuit. As a result, the evaluation circuit succeeded to detect the STV occurrence and it is confirmed that the proposed effect evaluation method by external noise using the evaluation circuit works effectively.

Micro-gap electrostatic discharges (ESDs) cause serious malfunction in electronic devices. To elucidate the mechanism, it is indispensable to understand the spark behavior of micro-gap ESDs. For this reason, two types of spark-resistance formulae proposed by Rompe-Weizel and Toepler have often been used so far to explain the spark process, while the verification and applicability of these formulae still remain unknown even at present. We previously measured spark currents from a human volunteer with charge voltages of 200 V or 2000 V in order to show which spark-resistance formula can better explain the spark process. The result showed that the behavior of sparks from 200 V and 2000 V charged human can be better represented by the Toepler's and Rompe-Weizel's formulae, respectively. In this study, a new measurement setup for spark currents, which are difficult to be directly measured due to the charge neutralization through the spark channel, is developed by using parallel disc electrodes. The setup allows to simply estimating the spark current and the corresponding spark voltage from the measured discharge currents. From this setup and the Matlab analyses, we confirm that spark currents through the spark channel are almost identical to discharge currents from the disc electrodes with charge voltages of 500 V or 4000 V, which reveals that the Toepler's and Rompe-Weizel's formulae can be better applied to the prediction of the dynamic spark behavior with charge voltages of 500 V and 4000 V, respectively, despite the fact that the spark lengths derived from the most commonly used spark constants of the Rompe-Weizel formula agree fairly with the measured spark lengths, while the spark lengths by the Toepler's formula are considerably smaller compared to the measured results. The finding obtained above supports our previous study.

In the ICNIRP guidelines on the protection of human exposure to low frequency electric and magnetic fields, the reference levels are given based on the maximum value of induced electric fields (EF’s) inside a numerical human model that stands erect on ground plane with both hands down by its sides. In this contribution, numerical results on the induced EF’s inside a numerical human model standing with elevated arms in a 50 Hz uniform EF, are illustrated. The effect of the arm elevation angle on the maximum EF is discussed. It is found that, when both arms are raised overhead, the maximum values of the induced EF in the nervous system tissues increase by 20 - 35% compared with those obtained when both hands are down by its sides, which falls within the reduction factor of 2.4.

Recently, technology of wireless power transfer (WPT) system for EV/PHV has been developed for the purpose of facilitating the battery charging. However, it is required that we grasp the influence on human health by exposure to leaked magnetic field from WPT system. ICNIRP guideline makes a recommendation that the induced electric field in human body is used for assessment of human safety. In this paper, the value of this quantity is evaluated for different parking patterns of two vehicles. Here, transfer power and frequency are 3.7kW and 85kHz, respectively. As a result of analysis, we found that the value could be reduced by controlling the phase difference between primary currents of two vehicles for each parking pattern.

In our daily lives, information devices are interconnected each other. So, there is a possibility that the immunity may degrade compared to the single unit under the actual use environment, and it may be susceptible to interference from external noise. To evaluate the noise in such a real environment, we propose a dynamically configurable noise measuring circuit. The proposed measurement circuit has high dynamic range and measures noise with high resolution in time domains. Through experiments, we implement the proposal circuit in a FPGA and show that the proposed circuit can accurately measure the conducted noise propagating from the outside of the circuit.

This paper discussed the influence of Absorber-Lined Shielded Enclosure (ALSE) on magnetic field measurement at the frequencies of 150 kHz or lower. To evaluate the influence of the ALSE for the measurement of “Low-frequency” magnetic field, we focused on the variation value of magnetic field strength against the distance from the magnetic field source to measurement point. By applying a mirror image method to the ALSE's floor, ceiling and walls with considering their materials, we could get the calculation results that agree with three dimensional simulation results and measurement results within 3dB in the range of 0.5 m to 2.5 m, and we confirmed the influence is caused by the material characteristics of ALSE's floor, ceiling and walls. In this study, we found that the method allows to calculate the influence of ALSE easily against the low-frequency magnetic field measurement in advance.

In this paper, we determine the coupling factor of kHz-band wireless power transfer (WPT) systems for electric vehicles by using measured magnetic near-field. A near-field measurement system with in-house developed magnetic- field probes is constructed and used to measure the magnetic field distributions at the position close to the fabricated WPT systems. Then, the magnitude and phase of the magnetic near-field obtained by the developed system are used as an incident field in the numerical analyses by the impedance method in order to numerically derive induced electric fields inside various human body models. Finally, the coupling factor for both kHz-band WPT systems with and without ferrite tiles and mimic vehicle body is proved to be lower than 0.15, which is the coupling factor value for WPT systems of EVs, determined in the report by the Information and Communication Council, Japan.