Human body communication (HBC) is a promising technology for realizing smart personal identification systems where users do not have to touch with IC cards. A severe problem of HBC is that an outsider in the vicinity of the system is often misidentified. A feasible solution to this problem is to classify signals sent from the user/outsider based on the HBC channel-gain feature G(f). To apply the classification scheme to real identification systems, G(f) must be acquired in a short time. A reasonable way to quickly acquire G(f) is to measure the impulse response of the HBC channel. We first demonstrated that G(f) can be correctly acquired by using the impulse signals. This result is an important step toward establishment of the smart identification systems.

Auditory stimuli, such as distress calls, are highly effective for controlling crows, but it has also been suggested that exposure to a single stimulus leads to habituation. In this study, we conducted an experiment on captive large-billed crows (Corvus macrorhynchos) to investigate the effects when a visual stimulus (a mirror) is added to the crow's distress call. Eight large-billed crows were divided into two groups; their foraging behaviours in the test cage were compared between a group only subjected to the auditory stimulus and a group subjected to both auditory and visual stimuli (combined stimuli). Both groups delayed the time to start feeding (i.e., latency time) compared with no stimulation (control condition). The group receiving only the auditory stimulus did not differ from the control condition in the number of landings on the food patch or total time spent at the food patch during the experiment. In contrast, when the combined stimuli were provided, the total time spent at the food patch during the experiment was less than in the control condition. This finding suggests that the combined stimuli were more effective at preventing the approach of crows and contributed to the long-term deterrence of crows compared with a single stimulus.

In solid insulation systems, the space charge generated by the insulator under a high DC electric field is one of the factors determining the properties of the insulation material, and its measurement has become an indispensable method of evaluating insulation materials. As one of the common measurement methods of space charge, the pulsed electroacoustic (PEA) method detects the time-domain acoustic signals generated by the interaction of the space charge with the pulsed electric field through a piezoelectric transducer, and thus the position and value of the space charge are deduced. Recently, measurements utilizing the PEA method have become a reality for ultra-high voltage DC insulation systems such as full-size DC cables. However, the spike noise generated by the high-voltage pulses applied during the measurement process can lead to fluctuations in the offset and tilt of the baseline of the response signal, which can lead to errors in the measurement and analysis results. For the measurement of thick specimens, it is difficult to eliminate this effect due to the small response signal. In this paper, the method for minimizing this error is discussed using the measurement results of a parallel plate electrode insulation system as an example.

This paper presents an experimental study on the sterilizing effect of dielectric barrier discharges on bacteria hidden inside tomato seeds. DBD treatment is performed on the tomato seeds containing transformed bacteria (Clavibacter Michiganensis Subsp. Michiganensis). The results of the colony counting tests after the DBD treatment show that the bacteria hidden inside the seeds cannot be completely sterilized, although those located on the seed surface can be easily sterilized. The distribution of bacteria on the cross-section of the seed is observed using a fluorescence microscope. It is confirmed that the area of bacterial distribution on the cross section is reduced by the DBD treatment. However, it is also confirmed that some bacteria hidden deeply inside the seeds are still viable after 180 min of DBD treatment.

In order to investigate effect of heating rate of short-time heat treatment using low-frequency induction heating on the magnetic properties of semi-processed electromagnetic steel sheets, magnetic properties of ring core samples were measured and the grain sizes were also measured by using a scanning electron microscopy. The results of the magnetic property measurements showed that the iron loss decreased at lower heating rate and higher attained temperature. The grain size measurements revealed that the secondary recrystallization was suppressed at higher heating rate. Furthermore, the eddy current loss and the hysteresis loss tended to increase and decrease, respectively, as the average grain size increased.

The load sensor we are researching uses the inverse magnetostriction effect of magnetostrictive materials. It was confirmed that Fe₃₀Co₇₀ exhibits a leakage flux change rate of approximately 130% when compressive stress changes from 1 to 100 MPa, suggesting the possibility of a load sensor using leakage flux using Fe₃₀Co₇₀. In this paper, we focused on the fact that Fe₃₀Co₇₀ Ni alloy has magnetostrictive properties that are opposite to those of Fe₃₀Co₇₀ Ni alloy, and measured the leakage magnetic flux with respect to compressive stress of Ni alloy. It was confirmed that in the Fe₃₀Co₇₀ alloy, the rate of change in leakage magnetic flux increases by 134% when compressive stress is applied, whereas in the Ni alloy, the rate of change in leakage magnetic flux decreases by -78% when compressive stress is applied. The leakage flux of positive magnetostrictive materials increased due to stress, while that of negative magnetostrictive materials decreased. Load sensors for magnetostrictive materials are feasible.

In this paper, the effect of twisting FeCoV magnetic wire on the magnetic property (the maximum strain rate and maximum effective permeability) was investigated. As a result, it was confirmed that twisting reduces the maximum strain rate of the FeCoV magnetic wire and increases its maximum effective permeability.

Dielectric elastomer (DE) can be used as a small-scale energy harvester due to its remarkable flexibility, lightweight and output power density. However, the key characteristic of DE, the permittivity, decreases when the DE is stretched. Meanwhile, the influence of the stretch-dependent permittivity on the power generation output performance of DE is unclear. In this study, the stretch-dependent permittivity and its effect on DE's power generation output were clarified. Then a DE's power generation output prediction method considering the stretch-dependent permittivity was proposed. The comparison between the measured and predicted values of power generation output, charge and voltage for the DE revealed that the stretch-dependent permittivity causes a reduction in charge during the charge-discharge cycle, leading to decreased power generation output. Therefore, it is necessary to consider the stretch-dependent permittivity for predicting the power generation output of DE.

To observe space charge distribution directly on an oscillogram without deconvolution, space charge measurements for 1 mm thick LDPE sheet are performed not with the very short pulse voltage but with the step-like voltage. In this system, a transducer consisting of a PVDF and an amplifier acts as a CR high-pass filter. The impulse response can be monopolar pulse because it corresponds to the differentiation of the pressure wave generated by the step-like voltage e(t) with a very long tail. In this paper, the influence of the rise time of the step-like voltage and the thickness of the PVDF sheet on the impulse response is experimentally studied. The half-width of the impulse response becomes short with reducing the rise time because de(t)/dt increases as the rise time decreases. On the other hand, the half-width cannot be short by reducing the PVDF thickness. This is because the cut-off frequency of the CR high-pass filter becomes low with decreasing the PVDF thickness, so the half-width for the 9 µm thick PVDF becomes longer than that for the 30 µm thick PVDF. We conclude that this method, with appropriate controls for the rise time of the step-like voltage and for the cut-off frequency, is very convenient for direct observation of the space charge distribution on a thick sample such as power cables.