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In order to confirm that earth-origin electromagnetic (EM) pulses could be excited by dynamical stress impacts onto earth crusts, we have been developing a method of pointing source locations of EM pulses on real-time basis, using a highly sensitive direction finding sensor system installed in deep boreholes at geographically different observation sites. Source locations of EM pulses can be determined by intersected points of arrival direction lines obtained at the observation sites. Through test measurements, we found that many detected EM pulses were unnecessary ones radiated from electric power lines on the ground and their related earth currents. It tells us a most important remark to beware in measurements of natural electromagnetic phenomena. By taking the preventive measures against noise, we obtained a preliminary result of source locations of EM pulses which are concentrated in an area of off-shore of Tou-Nan-Kai where is an area of potential earthquake occurrences in the future. Through the present developing process, we have proceeded to another stage toward the establishment of an observation network for accurately pointing source locations of earth-origin EM pulses on real-time basis.

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We propose a high-resolution precipitation and lightning monitoring for meteorological application. This monitoring is mainly utilized the Ku-band broadband radar (BBR) and the VHF broadband digital interferometer (DITF). The BBR can accurately measure the radar reflectivity factor and the mean Doppler velocity with 5 m resolution over a range from 40 m to several kilometers for 10 W power using a pulse compression technique. The two or more DITFs make us visualize lightning channel propagations in three dimensions. Moreover, we add new functions that integrate these observation data and disclose integration analyses results with the quasi real-time information disclosure system. Initial observations for severe storms with lightning during summer and winter thunderstorm season by these monitoring instruments indicate that we obtain detailed precipitation distribution and detect active convective cells with lightning discharges.

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The microwave emission at 22 GHz, 2GHz and 300 MHz was experimentally found in association with rock crash in laboratory. This phenomenon could be applied to detect earthquakes or volcanic eruption phenomena which are accompanied with the rock crash. In order to confirm the microwave emission in natural phenomena, we planned a field test at the volcano of Miyake-jima. This paper describes the estimation of the signal to noise ratio of the test, the test site and the measuring system. The obtained data and their analysis showed successful detection of signals at 300 MHz.

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In this paper, we analyze the equivalent potential temperature (EPT) at lightning locations in typhoons in order to determine whether a storm in typhoon produces lightning. We examined the vertical profiles of EPT and found that the lightning producing thunderstorm in typhoon typically had two instability layers at upper level (250hPa-300hPa) and lower levels (600hPa-700hPa), while the normal thunderstorm usually has single instability layer. The difference between the 250hPa EPT and 300hPa EPT in the upper-level convective instability is used to create an instability index for the forecast of lightning flashes particularly in typhoon. We calculated the False Alarm Rate (FAR), the Probability of Detection (POD) and the Critical Success Index (CSI) for the lightning prediction in typhoons with the value of 250hPa EPT and 300hPa EPT. As a result of the statistical analysis, when the 250hPa EPT of 367K or more and 300hPa EPT of 390K or less, the POD and FAR showed the highest score of 0.66±0.38 and 0.35±0.14, respectively. In this condition, CSI showed the highest score of 0.45±0.26. The proposed that N-index, namely the 250hPa EPT of 367K or more and 300hPa EPT of 390K or less, can be used as a specialized index for the prediction of lightning in typhoon.

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Chubu University has established ULF/ELF electromagnetic observation network in order to study seismo-electromagnetics. We estimate the direction angle of the ULF emissions observed at three observation stations (Nakatsugawa, Shinojima and Minami Izu) before the 2007 Noto Hantou and 2008 Iwate-Miyagi Nairiku earthquakes. As a result of analysis, we found that observed ULF emissions have been propagated possibly from the direction of the epicenter of the 2007 Noto Hantou earthquake and the 2008 Iwate-Miyagi Nairiku earthquake. However, the observed ULF emissions possibly propagated from the epicentral region were not so convincing enough, and so we need more event studies.

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We built an observational system in the Hosokura underground mine in northeast Japan. An underground laboratory for setting up equipment is located ∼1.5 km from the main gallery entrance and ∼70 m below the surface. To detect electric signals related to earthquakes, volcanic eruptions, and/or land slides, the room contains sensors for seismic waves, electric potentials, electric fields, air ion concentrations, air temperature, and air humidity. Long-term observations with a GPS-synchronized clock have identified daily and seasonal changes in the background levels of the quasi-static electric field and the air ion concentration, probably related to air movement in and out of the mine through the shaft near our laboratory. The background electric field may be caused by a bias distribution of negative and positive air ions.

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It is well known that electromagnetic waves radiated from the earth's crust are useful for predicting earthquakes. We analyze the electromagnetic waves received at the extremely low frequency band of 223Hz. These observed signals contain the seismic radiation from the earth's crust, but also include several undesired signals. Our research focuses on the signal detection technique to identify an anomalous signal corresponding to the seismic radiation in the observed signal. Conventional anomalous signal detections lack a wide applicability due to their assumptions, e.g. the digital data have to be observed at the same time or the same sensor. In order to overcome the limitation related to the observed signal, we proposed the anomalous signals detection based on a multi-layer neural network which is trained by digital data observed during a span of a day. In the neural network approach, training data do not need to be recorded at the same place or the same time. However, some noises, which have a large amplitude, are detected as the anomalous signal. This paper develops a multi-layer neural network to decrease the false detection of the anomalous signal from the electromagnetic wave. The training data for the proposed network is the decomposed signal of the observed signal during several days, since the seismic radiations are often recorded from several days to a couple of weeks. Results show that the proposed neural network is useful to achieve the accurate detection of the anomalous signal that indicates seismic activity.

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In this paper, a linear array typed imaging system of electrical and ultrasonic properties is proposed as one of measurement techniques for comfortable life. The proposed imaging system measures not only the ultrasonic property of the living body using the linear arrayed piezoelectric ceramic transducers, but also the electrical property using the surface electrodes of each piezoelectric ceramic transducer. From these data, the ultrasonic and electrical properties in the same object space are simultaneously reconstructed. In the experiment, propagation time and electrical voltage in the model, which the acrylic is inserted in the 0.1 % saline solution, are measured by the proposed imaging system based on linear array typed eight piezoelectric ceramic transducers. The ultrasonic and electrical properties are reconstructed from the measurement values. It was found that the ultrasonic and electrical properties in the same space were reconstructed by the proposed imaging system. Therefore, it is suggested that the proposed imaging system has potential for comfortable application although there are some problems that must be solved.

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It has been pointed out that free volumes in polymer materials are related to their microscopic structure, and thus it is considered that degradation mechanism of polymer materials will be well understood if correlations among free volumes and various characteristics of polymer materials are clarified. Recently, positron annihilation spectroscopy has been applied to evaluate free volumes in polymer materials. In this study, six types of polyethylene with different densities and cross-linked polyethylene were selected as typical polymer materials, and their free volumes were evaluated by the positron annihilation technique. Then, their relationships among free volumes and material characteristics such as thermal expansion and tensile strength were investigated. As a result, it was found that the estimated free volume radius and number density decreased with the increase in the material density, and their estimated average free volume radii were about 0.3nm. We proposed a parameter which is related to both of the volume and the number density and referred to it as relative free volume. The relative free volume decreased with the material density. Moreover, it increased with the increase in the coefficient of thermal expansion and with the decrease in the tensile strength. The correlations among the relative free volume and these material characteristics were confirmed to be strong.

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The restricted dielectric barrier discharge in nonwoven pores has been investigated by observation of the current pulse, the Lissajous figure and light emissions. The current pulse measurement revealed that homogeneity of the discharge was relatively high and the amount of individual pulse was quite small on the order of 0.01nC. Such a small current pulse demonstrates that nonwoven fiber is effective as a dielectric barrier. Analysis of the Lissajous figure, indicates the calculated value of the gap voltage for the discharge starting point of nonwoven fiber layers is close to what was predicted using the Paschen curve. On the other hand, the measured value of the gap voltage in the Lissajous figure is larger than its calculated value, so the surface charge on the dielectrics dissipated relatively fast. The observations of light emissions also showed a high homogeneity.

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In Recent years, atmospheric plasma source is widely used for industrial applications, because it does not demand vacuum chamber and pumping system. Also the density and chemical reactivity of atmospheric pressure plasma are much higher than low-pressure plasma. In addition, because of the density is very high, the concentration of contamination species in the plasma will be a negligible quantity, which means high purity plasma. Therefore, atmospheric plasma is expected that one of the best solution to realize the low cost, high speed and purity processing. However, it is not easy to generate large sized plasma under the atmospheric pressure. In this study, pulse or RF operation atmospheric large sized remote plasma source was developed and attached for surface treatment. Hydrophilization of acryl and glass were tested. By plasma irradiation for 30 seconds, the surface tension of acryl and glass were increased from 40 dyn/cm to 70 dyn/cm and 60 dyn/cm to 70 dyn/cm, respectively. The hydrophilic effect remained more than 4 weeks.

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Townsend's secondary ionization coefficients γ of MgO in Ar are determined from the breakdown voltages and the Townsend's criterion. Breakdown voltages on MgO film are measured by the both wave forms, discharge current and applied voltage between the electrodes on the oscilloscope. According to the experimental procedure, γ of gold film and stainless steel electrodes are determined and compared with other experimental values. After the confirmation of the validity of those results, we have carried out the determination for γ of MgO. Furthermore, the influence of heating effect of MgO film to the value of γ is also discussed.

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Detection of electro-magnetic waves is one of a good diagnosis tool that can be used for the condition assessment of insulating systems. Detection and frequency analysis of electro-magnetic wave caused by partial discharge in epoxy resin have been investigated. Electro-magnetic waves radiated by partial discharge could be detected by using simple system with a conventional discone antenna and a spectrum analyzer. Detected electro-magnetic wave spectra have two specific frequency regions: one is at lower than around 200MHz and another is higher than around 200MHz. From observation of electrical tree development and measurements of discharge current and partial discharge level, the former is associated with a void discharge in epoxy resin and the latter is identified as tree development. By using these specific frequency regions, it is applicable to detection of partial discharge and insulating assessment for power apparatus and their accessories including epoxy resin.

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Partial discharge (PD) activity of inter-turn insulation of electric motor winding is investigated under different parameters of square wave voltage, and the memory effect of deposited space charge in a cavity on PD activity is also studied. Under different frequency and rise time of square wave, discharge number, maximum discharge magnitude and phase resolved PD pattern is investigated. Increase in frequency and decrease in rise time both results in increase in maximum discharge magnitude and discharge number at square wave. Comparing the results of phase resolved PD patterns at different frequency of square wave, most of PD moves to zero point of square wave voltage with the increase in frequency. Meanwhile, with the reduction in rise time of square wave, a similar phenomenon can be observed. Through the analysis of a PD process at square wave voltage, the memory effect of deposited space charge after a discharge in cavity leads to superposition of electric field when the polarity of square wave voltage rapidly reverses. With the increase in frequency and reduction in rise time at square wave, superposition of electric field enhances. As a result, available discharge time prolongs during the rise time of square wave and overvoltage across the cavity increases. They result in the increase in discharge number and maximum discharge magnitude. Furthermore, for this reason, the position of PD shifts to zero point of square wave voltage.

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