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Broadband electromagnetic Wave Tunneling with Transmuted Material Singularity

Physical Review Letters 2020年第20期125卷 207401-207401页

作者： Yichao Liu Fei Sun Yibiao Yang Zhihui Chen Jianzhong Zhang Sailing He Yungui Ma Key Lab of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan 030024 China State Key Lab of Modern Optical Instrumentation Centre for Optical and Electromagnetic Research College of Optical Science and Engineering International Research Center for Advanced Photonics Zhejiang University Hangzhou 310058 China Department of Electromagnetic Engineering School of Electrical Engineering Royal Institute of Technology (KTH) S-100 44 Stockholm Sweden

Subwavelength channels filled with near-zero-index (NZI) media can realize extraordinary optical functionalities, for example, tunneling electromagnetic wave without reflections, but usually confined in a narrow wavelength band due to the material singularity (refractive index n≈0), which seriously limits the practical potentials. In this Letter, we show this limit can be fundamentally overcome by an alternative, named near-zero-index-featured (NZIF) structure, with the singularity transmuted via a controlled optical conformal mapping, enabling the device implementation with nonmagnetic normal dielectrics (i.e., relative permittivity >1). Their equivalence is strictly examined through a subwavelength tunneling waveguide. Classic wave tunneling features in a broad frequency range are revealed in various confined geometries. These properties are robust against the disturbance of several kinds of structural defects benefited from the infinite effective local wavelength. The broadband and lossless NZIF medium proposed here provides a promising way to pursue the fascinating light controlling functionalities as initially enabled by singular NZI materials.

关键词： Transformation optics Waveguides

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Dynamic polarimetric calibration using a single dual-polarized antenna polarimetric active radar calibrator

Dynamic polarimetric calibration using a single dual-polariz...

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IET International Radar Conference 2013

作者： Li, Y.Z. He, M. Huang, J. Luo, Y.J. Xiao, S.P. State Key Lab. of Complex Electromagnetic Environ. Effects on Electron./Info. Syst. Changsha 410073 China College of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China Beijing Space Information Relay and Transmission Center Beijing 100094 China

ISBN: (纸本)9781849196031

This paper designs a single rotatable dual-polarized antenna polarimetric active radar calibrator (PARC) and proposes a corresponding dynamic calibration polarimetric (DPC) method. The novel PARC simplifies the system equipment and optimises the antenna's pattern. By modulating the timedelay of the retransmitted signal of the PARC, the polarimetric radar is calibrated with the DPC method. The simulations verify that the single dual-polarized antenna DPC scheme possesses better calibration accuracy than the doubleantenna DPC scheme.

关键词： Calibration

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A New GaN Hybrid Resonant-Clamping Gate driver For High Frequency SiC MOSFETs

A New GaN Hybrid Resonant-Clamping Gate driver For High Freq...

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European Conference on Power Electronics and Applications

作者： Ziyue Dang Han Peng Hao Peng Yong Kang Yu Chen Xudan Liu Maojun He State Key Lab of Advanced Electromagnetic Engineering Technology Huazhong University of Science and Technology Wuhan Hubei State China Bosch (China) Investment Ltd. Changning Shanghai China

ISBN: (数字)9789075815368

ISBN: (纸本)9781728198071

Conventional resonant gate driver suffers from significant reverse recovery loss due to the usage of Si devices, especially at high frequencies. A novel hybrid resonant gate driver is proposed in this design composed by two hybrid GaN HEMT and Schottky diode half bridges. The hybrid topology merges the merits of efficient resonant turn on and ultra-fast turn off by GaN. The GaN based hybrid resonant-clamping gate driver achieves 29% reduction in gate driver active area. It also has 49.3% reduction in power loss is achieved compared with Si full bridge resonant gate driver.

关键词： Gallium nitride Gate drivers Silicon Silicon carbide Clamps Transient analysis

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Concentric silicon micro-ring resonators with enhanced transmission notch depth

Concentric silicon micro-ring resonators with enhanced trans...

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Optoelectronic Materials and Devices III

作者： Li, Xiaohui Zhang, Ziyang Li, Qiang Qiu, Min Su, Yikai State Key Lab. of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University 800 Dongchuan Rd Shanghai 200240 China Department of Microelectronics and Applied Physics Royal Institute of Technology 164 40 Kista Sweden

In this work, we have analyzed, fabricated and demonstrated concentric micro-ring resonators in silicon-on-insulator (SOI) structure for enhanced transmission notches. The operation principles of the concentric ring resonators are studied by time-domain coupled-mode theory. Directional coupling between concentric rings offers another freedom in designing deep notch optical filters and ultra-sensitive biosensors. The finite-difference-time-domain (FDTD) simulations have shown the improvement of the notch depth, evenly distributed mode field and the effect of the resonance shift. The device is demonstrated in silicon-on-insulator structure. Transmission notch depth improvement of ~ 15dB is demonstrated for the 21-20.02-μm-radius double-ring structure comparing with the single 21-μm-radius ring. © 2008 SPIE.

关键词： Silicon on insulator technology

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Model Predictive Control for Automatic Operation of Space Nuclear Reactors: Design, Simulation, and Performance Evaluation

SSRN

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SSRN 2023年

作者： Fu, Jianghan Jin, Zhao Dai, Zhiwen Su, Guanghui Wang, Chenglong Tian, Wenxi Qiu, Suizheng Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi’an710049 China

Space nuclear reactors possess the inherent benefits of independence from solar energy and the capability to withstand intricate external circumstances. Consequently, the establishment of a dependable automatic control system assumes utmost significance. In this paper, a high-fidelity nonlinear space thermionic nuclear reactor system model is established. An automatic control system with a model predictive control (MPC) controller is designed based on the system. In the case of a nuclear power step response, the MPC controller achieves an overshoot of 0.07% and a settling time of 0.65s. For an electric power step response, the MPC controller yields an overshoot of 0.28% and a settling time of 36.6s. These control performances are better than those achieved by the PID controller. In power tracking control, the MPC controller demonstrates virtually error-free tracking performance. When external reactivity disturbances are introduced, the MPC controller swiftly compensates for the disturbances at the desired level. © 2023, The Authors. All rights reserved.

关键词： Model predictive control

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Validation of Lead-Bismuth Thermal Hydraulic Facilities Based on Modified Relap5

SSRN

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SSRN 2022年

作者： Zhang, Yixin Zhang, Jiaxin Wang, Chenglong Tian, Wenxi Qiu, Suizheng Su, G.H. Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi'An710049 China

On the basis of not affecting the original computing power of RELAP5, the physical properties of lead and bismuth are added and verified. The important content of this paper is to use the modified RELAP5 to simulate the transient operating conditions carried out on the three lead-bismuth eutectic experimental devices of NACIE, TALL and NCCL, and compare it with the experimental data. The results show that the temperature error of the heating section of the NACIE facility under transient power conditions is within 7%. The error between the calculated value and the experimental value of the final core temperature under each working condition of the TALL facility is within 5%. The temperature simulation error of the experimental section of the NCCL circular tube heat transfer test is within 4%. The research in this paper can provide data and verification support for the development of the lead-bismuth fast reactor project. © 2022, The Authors. All rights reserved.

关键词： Fast reactors

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Optical properties of pulsed laser deposited K3Li2Nb5O15 thin films

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Rengong Jingti Xuebao/Journal of Synthetic Crystals 2008年第2期37卷 297-300页

作者： Zhan, Zu-Sheng Gong, Yan-Sheng Wang, Chuan-Bin Shen, Qiang Zhang, Lian-Meng State Key Lab. of Advanced Technology for Material Synthesis and Processing Wuhan University of Technology Wuhan 430070 China School of Materials Science and Chemical Engineering China University of Geosciences Wuhan 430074 China

Potassium lithium niobate (KLN:K3Li2Nb5O15) thin films have been deposited on quartz glass by pulsed laser deposition (PLD) technique using a stoichiometric KLN target, which was prepared by solid reaction with K2CO3, Li2CO3, and Nb2O5 powders as starting materials. X-ray diffraction (XRD) and Raman studies have revealed that tetragonal tungsten-bronze-type structure of KLN films with (310) preferred orientation could be achieved at the substrate temperature of 700°C and the oxygen partial pressure of 10 Pa. The average transmittance of as-deposited thin films in the visible range was nearly 90%.

关键词： Ferroelectric thin films

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Influence Study of the Anisotropic Scattering and Solar Radiation on the Radiation Working Performance of Liquid Droplet Radiator

SSRN

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SSRN 2024年

作者： Fei, Yiheng Fu, Jianghan Wang, Chenglong Tian, Wenxi Guanghui, S.U. Qiu, Suizheng Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi’an710049 China

The Liquid Droplet Radiator (LDR), a lightweight frameless radiant heat rejection system, is widely regarded as the optimal heat rejection solution for megawatt-scale space nuclear power systems. The LDR dissipates heat to space through its droplet layer, which plays a crucial role in determining its radiative rejection capacity. Radiation beams undergo a series of emission, scattering, and absorption processes within the layer before being emitted into space. Prior studies typically assume isotropic scattering in this process. However, this study introduces a 3D model of the LDR layer based on Mie theory and Monte-Carlo methods to investigate the impact of anisotropic scattering and solar radiation. Our calculations reveal that the working fluid exhibits strong forward anisotropic scattering characteristics. Under the anisotropic assumption, the heat rejection capability of the LDR is 27-33% higher compared to the isotropic assumption. Regarding the temperature distribution within the LDR, under the anisotropic assumption, the layer's temperature is 6 K lower at the XY boundary surface and 3 K higher at the layer median, as opposed to the isotropic assumption. We introduce the concept of the probability of a light beam escape to elucidate the distinct beam transmission mechanisms and temperature distribution. When the distance between the LDR and the sun is in the vicinity of 1 AU, the impact of solar radiation on the LDR's ability to operate is on the order of 1E-5, which is almost negligible. This study provides a theoretical foundation for calculating the heat rejection capacity during the LDR design phase. © 2024, The Authors. All rights reserved.

关键词： Solar radiation

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Generalized model-based decomposition for polarimetric SAR data

Generalized model-based decomposition for polarimetric SAR d...

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IET International Radar Conference 2013

作者： Chen, Si-Wei Wang, Xue-Song Xiao, Shun-Ping Sato, Motoyuki State Key Lab. of Complex Electromagnetic Environ. Effects on Electron./Info. Syst. Changsha 410073 China College of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China Center for Northeast Asian Studies Tohoku University Sendai 980-8576 Japan

ISBN: (纸本)9781849196031

Orientation angle compensation has been incorporated into model-based decomposition to cure the overestimation of volume scattering contribution, by rotating the coherency matrix to minimize the cross-polarization term. However, this processing cannot always guarantee to rotate the double- and odd-bounce scattering components back to zero orientation angle cases and with zero cross-polarization power. Therefore, built-up patches with large orientation angles may still suffer from the scattering mechanism ambiguity. In this paper, general double- and odd-bounce scattering models are proposed to fit for the cross-polarization and off-diagonal terms, by separating their independent orientation angles. The general decomposition framework is proposed and utilizes the complete information. The residual minimization criterion is used for model inversion. The optimal solutions are obtained using the nonlinear least square optimization technique. The manual interference and negative power issues are well avoided during the model inversion. Its efficiency and advantages are demonstrated and evaluated with airborne Xband Pi-SAR polarimetric SAR datasets. Comparison studies are also carried out. Further improved decomposition performance is achieved by the proposed method, especially in oriented built-up areas.

关键词： Polarimeters

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A novel Nth-order microstrip dual-mode bandpass filter with N+2 transmission zeros

A novel Nth-order microstrip dual-mode bandpass filter with ...

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2010 International Conference on Microwave and Millimeter Wave technology, ICMMT 2010

作者： Shen, Wei Yin, Wen-Yan Sun, Xiao-Wei Wu, Lin-Sheng Center for Microwave and RF Technologies School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University Shanghai 200240 China Center for Optical and Electromagnetic Research State Key Lab. of MOI Zhejiang University 310058 China Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China

ISBN: (纸本)9781424457052

A novel Nth-order microstrip filter with N+2 transmission zeros using two dual-mode resonators is presented in this paper. Two different coupling schemes are obtained by changing couplings between dual-mode resonators and ports. Then, two fourth- and second-order filter characteristics with three and four transmission zeros are obtained correspondingly. The generation mechanism of transmission zeros is interpreted in detail by coupling matrix theory. A microstrip dual-mode filter is designed and fabricated, with good agreement achieved between the measured and the simulated S-parameters. © 2010 IEEE.

关键词： Bandpass filters

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