論文 - 大坊 真洋
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住宅用火災警報器とスマートスピーカーを接続したICT火災通知システムの開発
千葉寿，小西誠一，大坊真洋
日本火災学会 火災 73 ( 2 ) 32 - 37 2023年04月 [査読有り]
学術誌 共著・分担
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Vector Potential Coupling From Outside the Loop Through the Superconducting Shield
M. Daibo
IEEE Transactions on Applied Superconductivity ( IEEE ) 33 ( 5 ) 1 - 5 2023年03月 [査読有り]
学術誌 単著
We tested whether the Maxwell-Lodge effect, a classi- cal version of the Aharonov-Bohm effect, occurs even when electro- magnetic shielding is provided by a superconducting tube. A long, thin superconducting solenoid coil was confined inside a lead tube so that there was no flux leakage from the coil ends. The double semi-circular vector potential coils ensure that 1) there is no local magnetic field at the location of the copper wire in the secondary coil and 2) there is no magnetic flux inside the loop of the secondary coil. Three different materials with different permeability were used for the core. A coaxial wire secondary coil shielded by a lead tube was placed orthogonally to the center of the semicircle of the primary coil. The voltage generated in the secondary coil at 4.2 K was only reduced to about 1/10 of 300 K. This coupling between the primary and secondary coils is due to the vector potential, since it cannot be completely shielded even with a superconducting shield.
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Y. Shoji and M. Daibo
AIP Advances 13 ( 025127 ) 2023年02月 [査読有り]
学術誌 共著・分担
Although vector potentials are more intrinsic physical quantities than magnetic and electric fields, measuring them macroscopically is difficult. A double-nested Helmholtz-type vector potential coil, consisting of an elongated solenoid coil wound around a cylinder, and producing a uniform magnetic vector potential, was developed in this study. The coil is carefully designed to reduce the influence of the leakage magnetic field and the scalar potential generated by the coil’s electrical resistance on the measurement. It has the ability to toggle between vector potential and magnetic field generation. We adapted the coil for use in an optically pumped atomic magnetometer. We also developed an optically pumping Rb atomic magnetometer that can calibrate in a zero magnetic field and applied a time-varying magnetic vector potential. We found that the output signal changed with the vector potential even when there was virtually no magnetic field. With increasing frequency, the output voltage decreases for the magnetic signal and increases for the magnetic vector potential signal. The results revealed that the atomic magnetometer is influenced not only by the magnetic field but also by the magnetic vector potential and that the frequency responses are opposite.
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Self-interference along boundaries between positive and negative refractive index media for 3D displays
Masahiro Daibo, Tomoya Tabuchi, Prathan Buranasiri,
Proc. SPIE 11331 2020年03月 [査読有り]
国際的学術誌 共著・分担
Negative index media have a phase velocity opposite to that of the pointing vector. Therefore, if media having the same absolute value of positive and negative refractive indices are alternately arranged, standing waves are generated along the boundaries of the media because these wavelengths are the same and the directions are opposite. We propose a method of generating a stationary interference fringe that is caused by self-interference with irradiating light from a direction parallel to the positive and negative media boundaries.
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Reflective wavefront control using random zero refractive index medium
T. Tabuchi, M. Daibo,
Proc. SPIE 11331 2020年03月 [査読有り]
国際的学術誌 共著・分担
The FDTD simulation is performed with a system in which the front-surface is a concave lens, the inside of bulk is a zero refractive index medium in which positive and negative refractive index cells are randomly arranged, and a reflector is placed over the back-surface plane. In a zero-index medium, an outgoing wavefront is always parallel to the outgoing- surface, is independent of either the incident wavefront or the shape of the incoming-surface. After waiting for a while after entering pulsed light into this structure, the light reflected from the back-surface is focused at the focal point of the concave lens over the front-surface.
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DC-Bias-Magnetic-Field Dependence of Step Response in an Elliptically Polarized Single-Beam Atomic Magnetometer
Y. Shoji, S. Khanuengchat, S. Takahashi and M. Daibo
IEEE 2020 8th International Electrical Engineering Congress (iEECON) 2020年03月 [査読有り]
国際的学術誌 共著・分担
A single-beam atomic magnetometer with elliptical polarization is simple in construction because it requires only one laser for both pumping and probing. When a small-signal magnetic field is input into the magnetometer after the DC magnetic field is set to zero, a full-wave cleared waveform is output. This characteristic is appropriate for calibration and measurement of DC magnetic fields, because the bias of such fields affects their sensitivity. In this paper, we examined the step-response waveform when a pulsed magnetic field with various DC magnetic-field biases was applied. The response waveform was measured in the time domain with an oscilloscope. The oscillation frequency did not depend on the step-magnetic-field difference but on the amplitude when changing from an absolute-zero magnetic field to a finite magnetic field. Because the DC magnetic field can be determined by measuring the frequency, the bias magnetic field of the atomic magnetometer can be adjusted to maintain the
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Modeling and Numerical Simulation for a Spherical Vector-Potential Coil
S. Lekchaum and M. Daibo
IEEE Transactions on Applied Superconductivity 30 ( 4 ) 1 - 5 2020年01月 [査読有り]
国際的学術誌 共著・分担
We proposed a model for a spherical vector-potential coil and investigated the properties of the coil, including the uniform distribution of the vector potential. We modeled a structure in which thin toroidal coils are superposed along a spherical surface. Rather than arranging the toroidal coils in close contact with each other along the surface of the sphere, the layer spacing of the toroidal coils should be constant so that the projection onto the axis of the sphere is equally spaced. When a current was applied to a toroidal coil, no magnetic field was created outside the toroidal coils; instead, a vector potential was present. When the same current was passed through each toroidal coil, the vector potential in the sphere achieved a uniform distribution by superposition. We presented the results of our numerical simulation of the distribution of the vector potential and the induced voltage when a secondary conductor was passed through the coil.
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Zero Magnetic Field Calibration for Single-Beam Atomic Magnetometers Using Second Harmonics
K. Saenyot, Y. Shoji, S. Takahashi and M. Daibo
IEEE Magnetics Letters 10 1 - 4 2019年09月 [査読有り]
学術誌 共著・分担
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Holographic Control of Electric Field Distribution for Mobile Communication
Masahiro Daibo, Hiroshi Okazaki, and Yasunori Suzuki
Published online: https://www.ieice.org/~mw/TJMW2019/ 2019年06月 [査読有り]
学会誌 共著・分担
2019 Thailand-Japan MicroWave Proceedings of TJMW2019
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トロイダル型ベクトルポテンシャルトランス
大坊真洋
Proceedings of the 2017 Eleventh International Conference on Sensing Technology (ICST) 2018年03月 [査読有り]
国際的学術誌 単著
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正と負の屈折率粒子をランダムに配置したゼロ屈折率媒体
大坊 真洋
電子情報通信学会論文誌 C J100–C ( 7 ) 227 - 285 2017年06月 [査読有り]
学術誌 単著
正と負の屈折率媒体セルを面積比率 1:1 でランダムに配置したゼロ屈折率媒体の性質を FDTD に より調べた.この媒体中では電界強度の分布がランダムになり，波面は完全に乱れるが，媒体の厚さが十分に厚 ければ，媒体から出射される波面は，入射波の波面，入射面形状，媒体中の空隙のいずれの影響も受けず，常に 出射面に平行であった.セルの大きさが波長の 20 分の 1 以下になると空間的に均一な媒体とみなすことができ， 屈折率がゼロの性質である位相速度無限大，媒体の入射面と出射面での位相の接続が現れた.これらの性質は， 光軸や焦点の調整が不要な集光器に利用することができる.混合比を変えることによって，屈折率を負から正ま で調整することができるので，負の屈折率媒体の絶対値を正確に調整する必要がなくなる.また，正と負の屈折 率媒体セルを規則的に層状に交互に配置したところ，層に直交する方向にゼロ屈折率の性質が現れ，異方性のあ るゼロ屈折率媒体となった.この異方性媒体では，球面波を入射すると入射波面と同じ波面で出射面から放出さ れる.また層を斜めに配置した場合は，横方向に伝搬方向がシフトする効果も現れた.
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Vector-Potential Transformer with a Superconducting Secondary Coil and Superconducting Magnetic Shield
Masahiro Daibo, Shuzo Oshima, Yoichi Sasaki, and Kento Sugiyama
IEEE Transactions on Applied Superconductivity 26 ( 3 ) 500904 2016年03月 [査読有り]
国際的学術誌 共著・分担
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Vector Potential Coil and Transformer
Masahiro Daibo, Shuzo Oshima, Yoichi Sasaki, and Kento Sugiyama
IEEE Transactions on Magnetics 51 ( 11 ) 1000604 2015年05月 [査読有り]
国際的学術誌 共著・分担
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Optical characterization by variable angle spectroscopic ellipsometry of nitrogen-doped MgxZn1-xO thin filmes prepared by the plasma-assisted reactive evaporation method
Takami Abe, Akira Nakagawa, michiko Nakagawa, Tetsuya Chiba, Shuzo Takahashi, Yasuhiro Kashiwaba, Shigeki Chiba, Tsutomu Ojima, Katsumi Aota, Masahiro Daibo, Hiroshi Osada, Tamiya Fujiwara, Ikuo Niikura, Yasube Kashiwaba, Kouichi Tsutsumi, Michio Suzuki
Thin Solid Films 571 615 - 619 2014年11月 [査読有り]
国際的学術誌 共著・分担
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Applicability of nitrogen-doped ZnO single crystals for photoconductive type UV sensors
Shuzo Takahashi, Takami Abe, Akira Nakagawa, Syuhei Kamata, Tetsuya Chiba, Michiko Nakagawa, Yasuhiro Kashiwaba, Shigeki Chiba, Haruyuki Endo, Kazuyuki Meguro, Masahiro Daibo, Ikuo Niikura, Yasube Kashiwaba, Shuzo Oshima, and Hiroshi Osada
Phys. Status Solidi C 9 11 ( 44020 ) 1304 - 1307 2014年03月 [査読有り]
国際的学術誌 共著・分担
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Fabrication of Schottky barrier diodes using H2O2-treated non-polar ZnO(1010) substrates
Yasuhiro Kashiwaba, Mio Sakuma, Takami Abe, Akira Nakagawa, Ikuo Niikura, Yasube Kashiwaba, Masahiro Daibo, Hiroshi Osada
Applied Surface Science 186 126 - 130 2013年09月 [査読有り]
国際的学術誌 共著・分担
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Hetero-epitaxial growth of non-polar ZnO films on single crystal NdGaO3 (001) substrates by MOCVD
Yasuhiro Kashiwaba, Tai Yokoyama, Mio Sakuma, Takami Abe, Akira Nakagawa, Ikuo Niikura, Yasube Kashiwaba, Masahiro Daibo, and Hiroshi Osada
physica status solidi（ｃ） DOI 10.100 2013年03月 [査読有り]
国際的学術誌 共著・分担
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Formation of a ZnO_2 layer on the surface of single crystal ZnO substrates with oxygen atoms by hydrogen peroxide treatment
Y. Kashiwaba, T. Abe, A. Nakagawa, I. Niikura, Y. Kashiwaba, M. Daibo, T. Fujiwara, and H. Osada
Journal of Applied Physics 113 ( 113501 ) 2013年03月 [査読有り]
国際的学術誌 共著・分担
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Epitaxial growth of high-quality MgxZn1-xO films by a plasma-assisted reactive evaporation method using ZnMg alloys as a source material
T. Abe, A. Nakagawa, M. Tanaka, M. Nakagawa, H. Endo, K. Megro, Y. Kashiwaba, S. Chiba, T. Ojima, K. Aota, S. Takahashi, M. Daibo, H. Osada, T. Fujiwara, K. Yamaguchi, I. Niikura, and Y. Kashiwaba
Phys. Status Solidi C 9 9 ( 8 ) 1813 - 1816 2012年08月 [査読有り]
国際的学術誌 共著・分担
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Structure and optical properties of non-doped and N-doped ZnO films with no-polar serface grown homoepitaxially on single crystal ZnO(1120) substrates
Takami Abe, A. Nakagawa, S. Chiba, Y. Kashiwaba, H. Endo, K. Meguro, T. Ojima, K. Aota, M. Daibo, H. Osada, I. Niikura, Y. Kashiwaba, and T. Fujiwara
Phys. Status Solidi (c) 6 ( S1 ) s94 - s97 2009年05月 [査読有り]
学術誌 共著・分担