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Nonlinearity in the Dark: Broadband Terahertz Generation with Extremely High Efficiency

Physical Review Letters 2019年第2期122卷 027401-027401页

作者： Ming Fang Nian-Hai Shen Wei E. I. Sha Zhixiang Huang Thomas Koschny Costas M. Soukoulis Ames Laboratory—U.S. DOE and Department of Physics and Astronomy Iowa State University Ames Iowa 50011 USA Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University Hefei 230039 China Key Laboratory of Micro-nano Electronic Devices and Smart Systems of Zhejiang Province College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China Institute of Electronic Structure and Lasers (IESL) FORTH 71110 Heraklion Crete Greece

Plasmonic metamaterials and metasurfaces offer new opportunities in developing high performance terahertz emitters and detectors beyond the limitations of conventional nonlinear materials. However, simple meta-atoms for second-order nonlinear applications encounter fundamental trade-offs in the necessary symmetry breaking and local-field enhancement due to radiation damping that is inherent to the operating resonant mode and cannot be controlled separately. Here we present a novel concept that eliminates this restriction obstructing the improvement of terahertz generation efficiency in nonlinear metasurfaces based on metallic nanoresonators. This is achieved by combining a resonant dark-state metasurface, which locally drives nonlinear nanoresonators in the near field, with a specific spatial symmetry that enables destructive interference of the radiating linear moments of the nanoresonators, and perfect absorption via simultaneous electric and magnetic critical coupling of the pump radiation to the dark mode. Our proposal allows eliminating linear radiation damping, while maintaining constructive interference and effective radiation of the nonlinear components. We numerically demonstrate a giant second-order nonlinear susceptibility ∼10−11 m/V, a one order improvement compared with the previously reported split-ring-resonator metasurface, and correspondingly, a 2 orders of magnitude enhanced terahertz energy extraction should be expected with our configuration under the same conditions. Our study offers a paradigm of high efficiency tunable nonlinear metadevices and paves the way to revolutionary terahertz technologies and optoelectronic nanocircuitry.

关键词： Metamaterials

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A High Efficiency Wireless Charging Antenna with Embedded Magnetic Core of Segmented Two-turns Loop 7

A High Efficiency Wireless Charging Antenna with Embedded Ma...

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2017 7th IEEE International Symposium on Microwave, Antenna, Propagation, and EMC Technologies

作者： Yong Song Kaihong Song Xianliang Wu Zhixiang Huang Xiaojing Kuang Yanyan Zhu Key Laboratory of Intelligent Computing & Signal Processing Ministry of Education Anhui University Electronic Information Engineering Hefei Normal University

ISBN: (纸本)9781509059300;9781509059294

In this paper, a high-efficiency transceiver antenna with embedded high magnetic permeability core of segmented two-turns loop is presented. It can be applied in the implanted device of monitoring human body neural with a wireless charging and bi-directional data transmission. The whole structure of transmitting and receiving antenna is basically similar;the difference is that receiving antenna is composed of double-sided ring and an embedded magnetic core at central position, transmitting antenna can be realized by dividing ring and welding fixed-value capacitor at corresponding position. The efficiency of wireless energy transfer has been improved and the specific absorption rate value has been reducing by simulation optimization. Compared with conventional loop antenna, our transmission efficiency has been exceed doubled and average SAR reduced by approximately 52%, when the distance of wireless transmission is 5 mm. Finally, we fabricate a conventional loop antenna, a segmented loop antenna with embedded magnetic core and a kind of mixed liquid that have the same dielectric parameters with skin at 402 MHz. Experiences show that actual results of transmission efficiency are in good agreement with the simulation results.

关键词： Implantable Wireless charging Segment Magnetic core Bi-directional data transmission

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Reversible data hiding in encrypted images with Two-MSB prediction 10

Reversible data hiding in encrypted images with Two-MSB pred...

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10th IEEE International Workshop on Information Forensics and Security, WIFS 2018

作者： Puyang, Yi Yin, Zhaoxia Qian, Zhenxing Key Laboratory of Intelligent Computing Signal Processing Ministry of Education Anhui University Hefei230601 China Department of Computer Science Purdue University West lafayette47906 United States Shanghai Institute for Advanced Communication and Data Science School of Communication and Information Engineering Shanghai University Shanghai200072 China

ISBN: (纸本)9781538665367

In recent years, reversible data hiding in encrypted images (RDHEI) that embeds additional data into the encrypted image content has received more and more attention. In previous RDHEI methods, there is no one considering the correlation between neighboring pixels. In this paper, to better explore the correlation between neighbor pixels, a novel reversible data hiding method in encrypted images with two-MSB (MSB and second MSB) prediction is proposed. After analyzing the original image content and detecting all the possible prediction errors, we encrypt the original image content using the bitwise exclusive-or (XOR) operation and highlight prediction error based on the error location binary map. Finally, all available pixels are embedded with additional data by two-MSB substitution. In our method, reversibility, separability and error-free data extraction are realized. The experimental results show that the proposed method providing a higher embedding rate and better quality of directly decrypted image compared with other start-of-the-art methods. © 2018 IEEE.

关键词： Pixels

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A Novel Multiple-traces Electric Field/Combined Field Integral Equation for Electromagnetic Modeling of Microstrip Objects

A Novel Multiple-traces Electric Field/Combined Field Integr...

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International Applied Computational Electromagnetics Society Symposium (ACES)

作者： Yv Long Wang Ran Zhao Zhi Xiang Huang Jun Hu Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University School of Electronic Engineering University of Electronic Science and Technology of China (UESTC)

In this paper, a new multiple-traces electric field/combined field integral equation (MT-EF/CFIE) is proposed for the electromagnetic modeling of microstrip objects. Different from traditional EFIE-PMCHWT method, this new multiple-traces method decomposes the original microstrip object into two independent domains i.e., the exterior region (free space) and interior region (microstrip), and enforces the Robin transmission conditions (TCs) on the interface between exterior and interior regions to ensure the continuity of fields. In comparison to the traditional EFIE-PMCHWT, this new MT-EF/CFIE has a better convergence property. Because the continuity of fields is ensured by TCs, the exterior and interior regions can be discretized by non-conformal meshes, which improves the flexibility and efficiency of the proposed methods substantially.

关键词： Microstrip Microstrip antenna arrays Dielectrics Integral equations Electromagnetic scattering Convergence

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3D fresnel field computing method based on its propagation reversibility

3D fresnel field computing method based on its propagation r...

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Chinese Society for Optical Engineering Conferences, CSOE 2016

作者： Zhang, Kai Wang, Xiangxiang Tan, Shengxia Shen, Chuan Wei, Sui Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University Hefei Anhui230039 China

ISBN: (纸本)9781510610118

There are many 3D data structures for computing diffraction field, the description based on 3D point-cloud is the elemental method of other descriptions, the diffraction field of 3D scene can be thought as the superposition of the diffraction field of each sampled light point and other descriptions can be thought as grouping with point-cloud by different way. The paper focuses on devising a computation method of 3D Fresnel field which is based on Fresnel diffraction field propagation reversibility. The proposed method combines the reversibility of Fresnel propagation and the requirement of sampling spacing by Nyquist criterion, i.e. to find the best space positions to optimize the number of sampling points and the reconstruction for the 3D Fresnel field. The method can be applied to reduce the computational complexity and improve computational efficiency. © 2017 SPIE.

关键词： Computational efficiency

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Uplink Supportive Number of Users in Massive MIMO Systems 9

Uplink Supportive Number of Users in Massive MIMO Systems

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2017 9th IEEE International Conference on Communication Software and Networks (ICCSN 2017)

作者： Jun Zhu Chao Wang Peng Ma Chaochao Jia Kai Li Key laboratory of Intelligent Computing & Signal Processing (Anhui University) Ministry of Education Technology and Innovation Department Shanghai Research Center for Wireless Communication

ISBN: (纸本)9781509038237;9781509038220

The supportive number of users achieving the maximum sum rate is studied in uplink massive MIMO systems for zero-forcing(ZF) and maximum-ratio combining(MRC). We obtain the lower bound of the achievable rate of each user for ZF and MRC receivers with any finite number of base station(BS) antennas, respectively. By this theoretical result, this paper will focus on the supportive number of users which was constrained with the minimum achievable rate. Through analyzing the optimal problem of maximizing the overall sum rate, we obtain the expression of optimal number of users and present the user scheduling algorithm for achieving the maximized sum rate. The numerical results show that the massive MIMO systems can improve the supportive number of users, and ZF receivers can support more number of users than MRC under the same condition.

关键词： large number of antennas achievable uplink rate supportive number of users massive MIMO

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An Adaptive Spectrum Allocation Algorithm in Ultra-Dense Network

An Adaptive Spectrum Allocation Algorithm in Ultra-Dense Net...

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International Conference on Communication Software and Networks, ICCSN

作者： Jun Zhu Chaochao Jia Chao Wang Kai Li Key laboratory of Intelligent Computing & Signal Processing (Anhui University) Ministry of Education Hefei China Technology and Innovation Department Shanghai Research Center for Wireless Communication Shanghai China

In this paper, we propose a novel method to adaptively adjust the parameter threshold used in overlapping frequency. We verify the performance of the proposed algorithm from the system simulation. Compared with the traditional network planning scheme which needs setting parameters manually, the optimal threshold is adaptively adjusted according to the distribution of the users. The simulation results show that the algorithm can improve the signal-to-interference-plus-noise-ratio (SINR) performance of users and the cell throughput when the users are distributed in the edge of cell coverage which owns the same optimization result as traditional optimization method. So the algorithm can effectively solve the decrease problem of spectral efficiency when the threshold in frequency overlap is set unreasonable and also save a lot of labour cost on setting parameters.

关键词： Interference signal to noise ratio Throughput Clustering algorithms Bandwidth Radio spectrum management Resource management

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Nonlinearity in the dark: Broadband terahertz generation with extremely high efficiency

arXiv

引用

arXiv 2019年

作者： Fang, Ming Shen, Nian-Hai Sha, Wei E.I. Huang, Zhixiang Koschny, Thomas Soukoulis, Costas M. Ames Laboratory U.S. DOE and Department of Physics and Astronomy Iowa State University AmesIA50011 United States Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University Hefei230039 China Key Laboratory of Micro-nano Electronic Devices and Smart Systems of Zhejiang Province College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China FORTH Heraklion Crete71110 Greece

Plasmonic metamaterials and metasurfaces offer new opportunities in developing high performance terahertz emitters/detectors beyond the limitations of conventional nonlinear materials. However, simple meta-atoms for second-order nonlinear applications encounter fundamental trade-offs in the necessary symmetry-breaking and local-field enhancement due to radiation damping that is inherent to the operating resonant mode and cannot be controlled separately. Here we present a novel concept that eliminates this restriction obstructing the improvement of terahertz generation efficiency in nonlinear metasurfaces based on metallic nano-resonators. This is achieved by combing a resonant dark-state metasurface, which locally drives nonlinear SRRs in the near field, with a specific spatial symmetry that enables destructive interference of the radiating linear moments of the SRRs, and perfect absorption via simultaneous electric and magnetic critical coupling of the pump radiation to the dark mode. Our proposal allows eliminating linear radiation damping, while maintaining constructive interference and effective radiation of the nonlinear components. We numerically demonstrate a giant second-order nonlinear susceptibility ∼ 10−11 m/V, one order improvement compared to previously reported split-ring-resonator metasurface, and correspondingly, two orders of magnitude enhanced terahertz energy extraction should be expected with our configuration under the same conditions. Our study offers a paradigm of high efficiency tunable nonlinear meta-devices and paves the way to revolutionary terahertz technologies and optoelectronic nanocircuitry. Copyright © 2019, The Authors. All rights reserved.

关键词： Terahertz waves

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Discovering Temporal User Interest on Twitter by Using Semantic Based Dynamic Interest Finding Model(TUT) 2nd

Discovering Temporal User Interest on Twitter by Using Seman...

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2017 IEEE 2nd Information Technology, Networking, Electronic and Automation Control Conference (ITNEC 2017)

作者： Rashid Abbasi Gohar Rehman Jia lee Farhad Muhammad Riaz Bin Luo School of Computer Science and Technology Anhui University College of Computer Science Chongqing University Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University

ISBN: (纸本)9781509064151;9781509064144

Social media systems are very popular in today's dynamic web. One of the famous social media systems is Twitter, in which peoples used to share their personal ideas about current issues with their friends. This work focuses on the problem of discovering a user's interest over time on twitter. Previous approaches have used to model the user topic of interest on twitter by building the profile of the users, that contain the words which can be used the user in his or her conversions with other users, but on twitter users used the noisy words which does not represent the correct topics or topic related to interest. This model has extended by a novel framework by using twitter user model. This model uses the latent topic variable to indicate the relatedness of the topic with any user. In this work, we propose a Temporal User Topic(TUT) approach which can consider the text of tweet by any user and time of the tweet. The proposed approach is used to discover topically related Users for different time periods. We also show how the interests and relationships of these users are changeovers a time period.

关键词： Topic Model User Interest Twitter Twitter-User Model Social Network Time Topic Modeling

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Construction of One-Lee Weight and Two-Lee Weight Codes over IF_p+vIF_p

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Journal of Systems Science & Complexity 2017年第2期30卷 484-493页

作者： SHI Minjia LUO Yong SOLE Patrick Key Laboratory of Intelligent Computing&Signal Processing Ministry of EducationAnhui UniversityHefei 230039China School of Mathematical Sciences Anhui UniversityHefei 230601China National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China Telecom Paris Tech ParisFrance

This paper is devoted to the construction of one-Lee weight codes and two-Lee weight codes over IF_p+vIF_p(v^2=v) with type p^(2 k_1)p^(k2)p^(k3) based on two different distance-preserving Gray maps from((IF_p+vIF_p)~n, Lee weight) to(IF_p^(2 n), Hamming weight), where p is a prime. Moreover, the authors prove that the obtained two-Lee weight codes are projective only when p=2.

关键词： Generator matrix Gray map linear code one-Lee weight code two-Lee weight code

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