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Plasmas induced by the irradiation of femtosecond laser pulses are promising as future intense terahertz pulse sources. Liquid water is attractive as a target for the terahertz pulse emission from the laser-induced plasmas because of its high density and ease of continuous supply. The studies of the terahertz emission from water-based laser plasma have just started in the last few years by several groups, including the author's group. In this article, recent findings in regard with the terahertz pulse emission from water films excited by the optical pulses are reviewed, mainly based on our studies.

This study reports a new experiment, “Experiments on Antenna Design and Electromagnetic Wave Propagation." Electromagnetism is an academic field that clarifies various phenomena associated with electrical charges, electric fields, and electromagnetic waves. These phenomena are invisible, which makes it difficult for students to learn this field of study only in a didactic manner. Based on such background, the new experiment has been set up. This study reports details of the proposed experiment, followed by the results of a survey conducted to figure out students' understanding of the experiment.

In this study, in order to improve the accuracy of estimate method of chloride content in concrete structures using electromagnetic wave, simulation of attenuation electromagnetic waves (SAE) was constructed considering influence of temperature, relative humidity and the chloride ion content were experimented in laboratory. As a result, the precision can presume average chloride content in the every depth of concrete from the conductivity calculated by SAE. Furthermore the chloride ion permeation degree by the long-term deterioration is presumed and the way to predict the time when corrosion of re-bar starts is proposed.

application/pdf, 要旨 : 私たちが生活をしている現代環境はさまざまな電磁波がありとあらゆるところを飛び回っている世界である。それは, 医療現場においても例外ではなく, 病院内もさまざまな電波に取り囲まれた環境にある。極端にいえば, 電気照明ひとつをとっても電磁波を発生しているのである。今回, 医療機器を中心として医療現場における電磁環境について検討した。 Abstract : Various electromagnetic waves exist in our daily life, no exception with healthcare facilities. Even through the electric illuminations have electromagnetic waves. this study investigated the electromagnetic environment in healthcare facilities containing medical equipment.

In this study, as one of basic experiment for estimation of chloride content using electromagnetic waves, the measurement using sodium chloride solution in different concentration were carried out. In field survey, five marine structures which were different environmental conditions had been measured during three years. In order to evaluate chloride content for several structures, the estimation of chloride content considering the differences of structural member and environmental conditions were suggested. In addition, the estimation of chloride content in the neighborhood of reinforcing bars and the interannual prediction of chloride content in the neighborhood of reinforcing bars were reported.

In this study, as a part of the study for the application to existing structures using Electromagnetic waves for estimation of content of chloride ion, and carried out of experiments to estimate whether mix proportion and the depth of reinforcing bars affect Electromagnetic wave measurement. In addition, Electromagnetic wave measurement in existing structures have been carried out to estimate content of chloride ion.

漏洩同軸ケーブル(LCX)は同軸ケーブルの外部導体表面にスロットが設けられたVHFアンテナの一種であり, 移動体通信用のアンテナとして主に利用されている。豪雨時に受信信号が変動することが経験的に知られているため, この変動を解析することでLCXに沿ってリアルタイムに豪雨を検出できないか検討した。まず, 理想的な状態で人工降雨実験を行った結果, 受信信号のノイズレベルは極めて大きく降雨強度との相関は見られなかった。そこで, 水滴がLCX表面に付着した時に発生する不連続点を検出するため多重解像度解析を使ってノイズ除去を行った結果, ノイズに埋もれた降雨による変動を抽出することができた。実降雨実験データにこのMRAを適用した結果, 約40mm/h以上の豪雨については, 検出することに成功した。これにより, 既に日本中に設置されたLCXネットワークを用いて豪雨を検出できる可能性を示せたと考 えられる。, Use of Leaky Coaxial cable (LCX) of a VHF/UHF antenna is proposed to monitor intensity of heavy rains along the cable in real time. Using a pair of LCXs with a transmitting antenna and a receiving antenna installed in parallel each other, receiving signals at arbitrary locations along LCX can be determined. For quantitative evaluation between rainfall intensity and the LCX signals, an artificial rainfall experiment was conducted. The LCX signal was nonstationary, and a component of fluctuation due to rainfall was below a noise floor. For denoising, a multiresolution analysis using a Daubechies wavelet was applied to the signals. As a result, the component of the fluctuation due to rainfall was extracted, and one-minute rainfall intensity of the artificial heavy rains was detected successfully. Conducting a field rainfall experiment using the dual LCX system as well, real heavy rains were also detected from a noisy signal using MRA.

Phishing scams often occur every day, and it is still not showing signs of decline. The recognized number of criminal damage was about 20,500 and the amount of damage was about 27.6 billion Japanese yen in 2008. This is a very serious problem and a great pressure to the society. To reduce such social anxiety, the device that restrains phishing scams was developed in this study. The most important aim of this study is to detect the existence of the 2 GHz band high frequency electromagnetic wave emitted from a mobile phone.As the result of the production of the device, the expected detection of the electromagnetic wave from a mobile phone could be achieved within the distance of 30 cm at least. Further several improvements, e.g. the improvement in sensitivity of the antenna and so on, will be added to the device in the future.

An improvement of hybrid Trefftz finite element method (HTFEM) for electromagneticwave propagation problems in periodic waveguiding structures is reported. Removingthe good initial guess required for the solving eigenvalue problem, we replace the downhillsimplex method with the Sakurai-Sugiura projection method (SSM) which is one ofnonlinear eigenvalue problem solvers. Therefore, we may compute all eigenvalues in thescope without time-consuming preparations for the initial guess. Numerical results ofperiodic metallic electrodes on the dielectric waveguide as a frequency selective surfaceshow usefulness of HTFEM with SSM.

A fast technique is desired for estimating reflection coefficients of electromagnetic planewaves from a plane boundary of discretized perfect matched layer(PML), because in thefinite element analysis(FEA) division of PML region into finite-elements and absorptionparameter distribution in the PML should be determined for achieving non-reflection fromPML boundary. For tackling this problem, we present the reflection coefficients calculatedfrom discretized wavenumber. In this paper, we consider the plane wave scattering froma PML plane boundary, and demonstrate that the results give satisfactory approximationof FEA results.

The investigated electrode configuration was composed of a needle electrode and a plane electrode. The discharge inception voltage rose as the gap length increased. This change on the discharge inception voltage should be affected by changing the electric field. When the electromagnetic wave was measured using a spectrum analyzer, the electromagnetic waves with around 150 MHz were detected in oil. While, the waves with around 50 MHz were detected in air. In addition, the appearance of the discharge images was observed with the image-intensified still camera.

In this report, in order to improve the accuracy of the non-destructive method to estimate the chloride content using electromagnetic waves, the construction of theory and experiments for verification were carried out. At first, the phenomenon of attenuation of electromagnetic wave due to content of chloride ions in concrete was clarified by applying the electromagnetism and physicochemical theory. Then, each optimal solution was obtained from the results of measurement using radar with specimens of concrete in which changed the depth of concrete, temperature of concrete, water content and chloride coment. As the results, it is possible to estimate the attenuation characteristics of electromagnetic waves for change of the material propenies of concrete and to obtain the estimation equation which contribute to improve in accuracy of estimation of chloride ions in concrete using electromagnetic wave.

For the study of the EM (Electro Magnetic) wave propagation on the surface of the human body, the agar-gel phantom is used in the experiment. As the numerical analysis with the moment method which corresponding to the experiments, the relative permittivity of the homogeneous phantom plate becomes as the higher as the value of some thousands. The, numerical analysis shows that the other electrical properties can not contribute to the propagation characteristics in VHF resigon. These results assume that there is the unknown surface effect on the water in the region of VHF frequencies. Another experiment is conducted with varying the intervals of electrodes or forms and sizes, can give the optimal parameters. According to these experiments there is a frequency band which can be propagate on the human body in 40 MHz and near 100 MHz regions.

This paper describes frequency analysis of electromagnetic waves caused by partial discharge. The investigated electrode configuration is composed of a needle electrode and a plane electrode. The discharge inception voltage rose as the gap length increased. And the discharge inception voltage rose when the gap length was small. This difference on the discharge inception voltage should be affected by changing the width of the gap length. When the electromagnetic wave was measured using a spectrum analyzer, the electromagnetic waves were with around 150MHz were detected in oil. While, the waves with around 60MHz were detected in air. In addition, the appearance of the discharge images was observed with the image-intensified still camera.

application/pdf, 論文(Article), As part of earthquake prediction research, observations have been performed using simulated cir­cuits modeling the electrical potential in live plants, nonresonating circuits, and LC resonance circuits. From this research, the ripple change characteristic of LC resonance circuits is displayed. By examin­ing the change in this ripple, it is found to match an electromagnetic wave that is one of the known earthquake precursor phenomena. Unusual change in this ripple was detected on March 4, and it is noted that the earthquake off the western coast of Fukuoka (M7.0) occurred 16 days later, on March 20, 2005. Furthermore, similar anomalies of lesser magnitude were detected in the ripple on April 12, and the aftershock (M5.8) occurred eight days later, on April 20. After the observed pulse displays an un­usual change, an earthquake occurs. This phenomenon is related to the electromagnetic wave emitted before an earthquake occurs. Since the major earthquake and aftershock have occurred after an un­usual pulse change appears, it is inferred that it is possible to use phenomenon in earthquake predic­tion.

金沢大学理工研究域電子情報学系, Two nobel radiation process arc reviewed. One is a DARC (D)c to Ac Radiation Convenor) and I he ogher is a superradiance process. DARC can emit the radiation from a static electric field via the interaction between the field and a laser created ionization front. The frequency of the radiation mainly depends on the geometry of the DARC structure. The snperradiance is the stimulated emission from spatially localized ensembles of electrons and is promising method of generaling powerful ultrashort electromagnetic pulses. Here, radiation from a thin electron layer is reviewed as a simple model of superradiance.

Electromagnetic (EM) waves associated with natural phenomena in VHF band have been observed by use of a novel dual frequency observation method. The observation method can observe not only natural EM waves but also reflected FM broadcasting waves. This paper shows some observation results of natural EM phenomena associated with galactic noise, solar flare, sporadic-E layer, the Leonid echo and the Geiyo earthquake., 資料番号: AA0045438069

In this paper, we monitored the electromagnetic waves generated by human activity. We investigated a monitoring system that used the bioelectric potential of a plant. Four subjects walked on the spot at a distance of 60 cm from a rubber tree and we measured the variation in the bioelectric potential of the tree produced by the stepping motion. The results confirmed that the electromagnetic waves generated by a person walking on the spot produced a measurable response in the bioelectric potential of a plant. It was also found that this variation in the bioelectric potential varied in synchrony with the subject's walking pace.

Chapter 1 Introduction||Chapter 2 Experimental Setup and Measurement System||Chapter 3 Partial Discharge Characteristics under Three-phaseElectric Field in Three-phase Construction||Chapter 4 Effect of Rotating Electric Field on PD Pattern in aThree-phase Construction||Chapter 5 Propagation Properties of Electromagnetic Wave Induced byPartial Discharge in Three-phase GIS using UHF Method||Chapter 6 Concluding Remarks||List of Publication||Acknowledgment||Appendix, 九州工業大学博士学位論文 学位記番号:工博甲第259号 学位授与年月日:平成20年3月25日, 平成19年度