今井先生はファラデー流の電場と磁場の概念から出発して, 電磁気の諸法則を運動量・角運動量およびエネルギーの保存則から導くという電磁気学を構成した.そこで, ローレンツ力のパラドックスの考察から, 電磁運動量と・の意義と重要性を考える.そして電磁場の近接相互作用を基礎にすると, 電磁場は複素振幅で表され, 電場と磁場よりもベクトル・ポテンシャルが基本になると考える.

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This article focuses on Poynting’s vector which is defined by a vector product of electric and magnetic fields and plays an important role in considering a flow of electromagnetic energy between power supplies and various types of electromagnetic devices in electrical, electronical and information networks. Poynting’s vector is introduced from a law of energy conservation and its surface integral on an arbitrary domain is equal to the electromagnetic power inside it. This relation can be applied to any system in which there is an interest in the energy flow. Validity of the speculation that Poynting’s vector directly gives the energy flow is examined in various cases. It is pointed out that Poynting’s vector is not equal to the energy flow in some cases. Also discussed is the condition under which the equality holds.

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本報告では、プリント基板上におけるデカップリングコンデンサ位置最適化手法について述べる。最終的に、任意の周波数におけるPCB近傍の磁界強度分布を比較することにより、本手法の有効性を検証する。

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It is essential to understand radio wave propagation for the efficient operation of mobile communication systems. Numerical simulations can support characterizations of the indoor propagation and lead to many new discoveries related to them. This paper employs large-scale numerical simulations to estimate propagation channels of a dual-band wireless LAN system.

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無線LANシステムなどの移動通信において,効率的な運用を実現するためには電波伝搬に関する十分な理解が必要である.従来,電波伝搬特性推定においては実験的な手法が多く用いられてきた.一方,計算機システムの性能向上および大規模化により,数値シミュレーションによるオフィスビルなどの屋内伝搬に関する推定が現実的になっている.本稿においては,オフィスビルにおける5GHz帯無線LANシステムの屋内伝搬特性として,大規模電磁界解析に基づく伝搬経路の推定を行う.はじめに,数値シミュレーションのための高精度数値モデルを作成する.特に,電波伝搬は金属導体により大きな影響を受けることから,金属製什器やコンクリート壁内部の鉄筋構造等を正確に考慮する.定常状態における電磁界成分からを計算および可視化することで,屋内伝搬経路の推定を行う.

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近年、時間反転対称性や空間反転対称性が破れたフォトニック結晶において、異種媒質との境界面に沿って表面波が一方向伝搬する現象が報告されている。　本研究では、マイクロ波領域において、カイラリティを有するメタ分子がサブ波長間隔で並べられた2次元カイラルメタマテリアルを構築し、伝搬する電磁波の電磁界分布を実験的に調べた。その結果、電磁界分布は非対称性を示し、カイラリティに依存して変化することを確認した。

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In this paper, a new absorbing boundary condition based on the advection equation has been proposed, which considers the attenuation of electromagnetic waves propagating towards the absorbing boundaries. The validity of the proposed condition has been tested by comparing the results, calculated using the FDTD method with the proposed absorbing boundary condition, with those calculated with other representative absorbing boundary conditions such as Liao's first- and second-order conditions. It has become clear that the proposed absorbing boundary condition is more effective than the other representative advection-equation-based absorbing boundary conditions.

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光がエネルギーを運ぶことは知識としてだけでなく，日常的な体験からもよく知られている．本解説では，空間に蓄えられている光のエネルギーとその流れの基本的な概念を整理し，実用上重要な光の強度という物理量を正確に理解していただくことを目指す．また，物質中ではそれを構成する電子との相互作用を通して，光は損失を受け，熱エネルギー，電気エネルギーなどに変換される．応用上はエネルギー変換効率が性能として重要となるが，その最適化のためには物質中を伝搬する光の強度変化に対する理解が必須である．

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Structure of non-equilibrium cesium seeded argon plasma excited with microwave power is simulated numerically. The plasmas produced at suitable microwave powers are found to consist of three regimes, that is, the region limited by charged particle loss toward the wall, the full seed ionization and the diffusion limited regions. The fully ionized seed plasma is produced within the skin-depth determined by the electrical conductivity of the plasma, and the thickness of the fully ionized seed plasma depends on the seed fraction, gas pressure and microwave power.

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We developed an integrated optical device for MiniDisc MO recording systems. The simple configuration and manufacturing process of the device were realized through developing ray-tracing and diffraction integral methods for crystals and employing a simple micro-prism of a birefringent crystal KTP (KTiOPO₄). We confirmed that an optical head using the device had adequate quality and reliability for practical use.

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Spectral control of near-field radiation transfer from Metal-Insulator-Metal (MIM) structured emitter made of Ni and SiO2 to Metal-Semiconductor-Metal (MSM) structured Thermo-photovoltaic (TPV) cell made of GaSb semiconductor and Au is studied using Finite Difference Time Domain (FDTD) method. As the simulation result, enhancement of near-field thermal radiation flux is observed among near infrared radiation range for GaSb TPV cell, 1.0~1.6μm, mainly by the structure of MIM emitter. In addition, inside of GaSb is partially stimulated by MIM emitter and MSM structures.

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本研究では、カイラル物質で実現されるワイル型スピン軌道相互作用系を想定し、電磁場の有効ハミルトニアンを導出する。スピン軌道相互作用によって空間反転対称性のみが破れている場合では、光学カイラリティに比例した項が現れると考えられる。磁化の存在によって時間反転対称性も破れている場合では、

に比例した、磁気カイラル現象を記述する項が現れると予想される。得られた結果をもとに、誘起される電磁応答現象を議論する。

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Spectral control of near-field radiation transfer by interference of Surface Plasmon Polaritons (SPPs) in pillar array structured surface made of nickel was investigated using a numerical simulation based on Maxwell’s electromagnetic wave theory. The electromagnetic field between two pillar array structured surfaces fixed in face to face with a vacuum gap of several hundred nanometers was obtained using a three dimensional Finite Difference Time Domain (FDTD) method and fluctuational electrodynamics (FED). The near-field radiation flux from a high temperature to a low temperature pillar array structured surfaces was evaluated through the summation of normal components of Poynting vector in any direction at the intermediate of the vacuum gap. Through the numerical simulation, it was clarified that the local maximum and the local minimum of near-field radiation flux were shown periodically with increasing height of pillar under the condition of a fixed vacuum gap, which was regarded as interference between the pillar height and an electromagnetic wave propagating in the channel between pillars. Moreover, the dispersion relation of the electromagnetic wave with interference in the channel between pillars is quite similar to the SPPs established in two semi-infinite smooth plates with a nanometer vacuum gap. As a result, it was concluded that the spectral control of near-field radiation transfer was achieved by interference of SPPs in the channel between pillars by tuning the height of pillar.

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It is well known that damage and fracture of the structure are originated from slipping and breaking binds between atomics, which could emit manifold physical signals. Thus, the detection of those signals will bring us a lot of information as linking between micro and macro structure. Many studies in this area have been focused on detection of physical signals generated by fracture phenomenon. On the other hand, the signal by dislocation, which could be related to plastic deformation, has never been interested. The dislocation could disturb an electric density field in crystal structure. It is thus expected that the disturbed field forms an electric dipole. Consequently, when the dislocation is moved rapidly, electromagnetic wave will be radiated from this dipole. In this study, electric density field around an edge dislocation is analyzed using first-principles calculation. As a result, it was confirmed that the existence of the dipole was identified around the dislocation core, and an electromagnetic radiation from the dislocation movement was estimated.

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There are many studies for detecting several physical signals generated by fracture phenomenon. However, the signal by dislocation motion, which is related to plastic deformation, has never been interested. The dislocation could disturb an electric density field in crystal structure. It is expected that the disturbed field forms an electric dipole. When the dislocation is moved rapidly, electromagnetic wave will be radiated from this dipole. In this study, electric density field around an edge dislocation is analyzed based on a first-principles calculation. Influence of different strain, atomic number Z and dislocation movement on the dipole was also discussed. As a result, the magnitude of dipole was varied with strain and was linearly increased as the atomic number Z. Moreover, electromagnetic radiation from the dislocation movement was estimated.

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