检索结果-内蒙古大学图书馆

arXiv 2020年

作者： Zhou, Xing-Yu Ding, Hua-Jian Zhang, Chun-Hui Li, Jian Zhang, Chun-Mei Wang, Qin Institute of quantum information and technology Nanjing University of Posts and Telecommunications Nanjing210003 China " Broadband Wireless Communication and Sensor Network Technology" Key Lab of Ministry of Education NUPT Nanjing210003 China "Telecommunication and Networks" National Engineering Research Center NUPT Nanjing210003 China

The measurement-device-independent quantum key distribution (MDI-QKD) protocol plays an important role in quantum communications due to its high level of security and practicability. It can be immune to all side-channel attacks directed on the detecting devices. However, the protocol still contains strict requirements during state preparation in most existing MDI-QKD schemes, e.g., perfect state preparation or perfectly characterized sources, which are very hard to realize in practice. In this letter, we investigate uncharacterized MDI-QKD by utilizing a three-state method, greatly reducing the finite-size effect. The only requirement for state preparation is that the state are prepared in a bidimensional Hilbert space. Furthermore, a proof-of-principle demonstration over a 170 km transmission distance is achieved, representing the longest transmission distance under the same security level on record. Copyright © 2020, The Authors. All rights reserved.

关键词： Quantum cryptography

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Atomic switches of metallic point contacts by plasmonic heating

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Light(Science & Applications) 2019年第1期8卷 893-900页

作者： Weiqiang Zhang Hongshuang Liu Jinsheng Lu Lifa Ni Haitao Liu Qiang Li Min Qiu Bingqian Xu Takhee Lee Zhikai Zhao Xianghui Wang Maoning Wang Tao Wang Andreas Offenhausser Dirk Mayer Wang-Taek Hwang Dong Xiang Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Key Laboratory of Optical Information Science and TechnologyInstitute of Modern OpticsCollege of Electronic Information and Optical EngineeringNankai University300350 TianjinChina State Key Laboratory of Modern Optical Instrumentation College of Optical Science and EngineeringZhejiang University310027 HangzhouChina College of Engineering University of GeorgiaAthensGA 30602USA Department of Physics and Astronomy and Institute of Applied PhysicsSeoul National UniversitySeoul 08826Korea Institute of Materials Research and Engineering A*STAR2 Fusionopolis WayInnovisSingapore 138634Singapore Institute of Complex Systems ICS-8BioelectronicsResearch Center Juelich and JARA Fundamentals of Future Information TechnologyJülich 52425Germany

Electronic switches with nanoscale dimensions satisfy an urgent demand for further device miniaturization.A recent heavily investigated approach for nanoswitches is the use of molecular junctions that employ photochromic molecules that toggle between two distinct *** contrast to the reports on this approach,we demonstrate that the conductance switch behavior can be realized with only a bare metallic contact without any molecules under light *** demonstrate that the conductance of bare metallic quantum contacts can be reversibly switched over eight orders of magnitude,which substantially exceeds the performance of molecular *** the switch process,the gap size between two electrodes can be precisely adjusted with subangstrom accuracy by controlling the light intensity or *** by simulations,we reveal a more general and straightforward mechanism for nanoswitching behavior,i.e.,atomic switches can be realized by the expansion of nanoelectrodes due to plasmonic heating.

关键词： metallic behavior illumination

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Pyramid MIMO Dielectric Resonator Antenna with Circular Polarization Diversity

Pyramid MIMO Dielectric Resonator Antenna with Circular Pola...

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International Symposium on Antennas and Propagation (ISAP)

作者： B. J. Liu J. H. Qiu N. N. Wang X. Pan J. Ni S. Yan School of Electronics and Information Engineering Harbin Institute of Technology Harbin China Department of Network Heilongjiang Meteorological Data Center Harbin China

In this paper, a pyramid MIMO dielectric resonator antenna (DRA) with circular polarization diversity is proposed. It consists of two DRA elements with same dielectric resonator (DR) and rectangular slot fed by microstrip line. The proposed pyramid DR with given width to length ratio is easy to obtain circular polarization performance by rotating the DR to the slot. The difference between the two elements is the relative position of DR to the feeding slot. Two ports correspond to different DR to x- axial angles of 45° and 135° resulting in left-handed circular polarization and right-handed circular polarization. For the symmetry of MIMO antenna structure, two ports have the same impedance bandwidth of 4.65 GHz with the isolations between two ports higher than 21.8 dB under no extra method for reducing mutual coupling. In addition, axial ratio bandwidths are 820 MHz and the peak gains attains at 7 dBiC.

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Dynamic relaxation process of a 3D super crystal structure in a Cu:KTN crystal

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Chinese Optics Letters 2020年第2期18卷 61-65页

作者： Quanxin Yang Xin Zhang Hongliang Liu Xuping Wang Yingying Ren Shan He Xiaojin Li Pengfei Wu Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Institute of Modern OpticsNankai UniversityTianjin 300071China Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices Hubei University of Arts and ScienceXiangyang 441053China Advanced Materials Institute Qilu University of Technology(Shandong Academy of Sciences)Jinan 250014China Shandong Provincial Engineering and Technical Center of Light Manipulations&Shandong Provincial Key Laboratory of Optics and Photonic Device School of Physics and ElectronicsShandong Normal UniversityJinan 250358China

In this Letter,we report the existence and relaxation properties of a critical phenomenon on called a 3D super crystal that emerges at T=TC?3.5℃,that is,in the proximity of the Curie temperature of a Cu:KTN *** dynamics processes of a 3D super crystal manifest in its formation containing polarized nanometric regions and/or polarized ***,with strong coupling and interaction of microcomponents,the characteristic relaxation time measured by dynamic light scattering demonstrates a fully new relaxation mechanism with a much longer relaxation *** the relaxation mechanism of a relaxator is so-far undetermined,this research provides a novel *** results can help structure a fundamental theory of ferroelectric relaxation.

关键词： KTN relaxation time dynamic light scattering micronano structure

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Universal multi-source domain adaptation

arXiv

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arXiv 2020年

作者： Yin, Yueming Yang, Zhen Hu, Haifeng Wu, Xiaofu Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing210003 China National Engineering Research Center of Communications and Networking Nanjing University of Posts and Telecommunications Nanjing210003 China

Unsupervised domain adaptation enables intelligent models to transfer knowledge from a labeled source domain to a similar but unlabeled target domain. Recent study reveals that knowledge can be transferred from one source domain to another unknown target domain, called Universal Domain Adaptation (UDA). However, in the real-world application, there are often more than one source domain to be exploited for domain adaptation. In this paper, we formally propose a more general domain adaptation setting, universal multi-source domain adaptation (UMDA), where the label sets of multiple source domains can be different and the label set of target domain is completely unknown. The main challenges in UMDA are to identify the common label set between each source domain and target domain, and to keep the model scalable as the number of source domains increases. To address these challenges, we propose a universal multi-source adaptation network (UMAN) to solve the domain adaptation problem without increasing the complexity of the model in various UMDA settings. In UMAN, we estimate the reliability of each known class in the common label set via the prediction margin, which helps adversarial training to better align the distributions of multiple source domains and target domain in the common label set. Moreover, the theoretical guarantee for UMAN is also provided. Massive experimental results show that existing UDA and multi-source DA (MDA) methods cannot be directly applied to UMDA and the proposed UMAN achieves the state-of-the-art performance in various UMDA settings. Copyright © 2020, The Authors. All rights reserved.

关键词： Machine learning

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Exploiting Meta-Path with Attention Mechanism for Fine-Grained User Location Prediction in LBSNs 3

Exploiting Meta-Path with Attention Mechanism for Fine-Grain...

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2019 3rd International Conference on Data Mining, Communications and Information technology, DMCIT 2019

作者： Wang, Zhixiao Yan, Wenyao Wang, Wendong Gao, Ang Yu, Lei Yang, Shaobo Nie, GaoYang School of Computer Science and Engineering Xi'an University of Technology Xi'an710048 China Telematics Group University of Goettingen Goettingen37077 Germany Shaanxi Key Laboratory of Network Computing and Security Xi'an710048 China School of Electronic and Information Engineering Xi'an Jiaotong University Xi'an710048 China College of Xi'an Innovation Yan'an University Xi'an710100 China Yan'an University Yan'an716000 China National Satellite Meteorological Center China Meteorological Administration Beijing100081 China

Based on the huge volumes of user check-in data in LBSNs, users' intrinsic mobility patterns can be well explored, which is fundamental for predicting where a user will visit next given his/her historical check-in records. As there are various types of nodes and interactions in LBSNs, they can be treated as Heterogeneous Information network (HIN) where multiple semantic meta-paths can be extracted. Inspired by the recent success of meta-path context based embedding techniques in HIN, in this paper, we design a deep neural network framework leveraging various meta-path contexts for fine-grained user location prediction. Experimental results based on two real-world LBSN datasets demonstrate the best effectiveness of the proposed approach using various evaluation metrics than others. © 2019 Published under licence by IOP Publishing Ltd.

关键词： Deep neural networks

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Is AI Robust Enough for Scientific Research?

arXiv

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arXiv 2024年

作者： Zhang, Jun-Jie Song, Jiahao Wang, Xiu-Cheng Li, Fu-Peng Liu, Zehan Chen, Jian-Nan Dang, Haoning Wang, Shiyao Zhang, Yiyan Xu, Jianhui Shi, Chunxiang Wang, Fei Pang, Long-Gang Cheng, Nan Zhang, Weiwei Zhang, Duo Meng, Deyu Northwest Institute of Nuclear Technology No. 28 Pingyu Road Shaanxi Xi’an710024 China School of Telecommunications Engineering Xidian University No. 2 South Taibai Road Shaanxi Xi’an710071 China State Key Laboratory of ISN No. 2 South Taibai Road Shaanxi Xi’an710071 China Institute of Particle Physics Central China Normal University No. 152 Luoyu Road Hubei Wuhan30079 China School of Computer Science and Technology Xi’an Jiaotong University No. 28 Xianning West Road Shaanxi Xi’an710049 China Ministry of Education Key Lab of Intelligent Networks and Network Security Xi’an Jiaotong University No. 28 Xianning West Road Shaanxi Xi’an710049 China Guangzhou Institute of Geography Academy of Sciences No. 100 Xianlie Road Guangdong Guangzhou510070 China National Meteorological Information Center Beijing100044 China MDX Research Center for Element Strategy Institute of Integrated Research Institute of Science Tokyo Midori-ku Yokohama226-8503 Japan School of Physics and Information Technology Shaanxi Normal University No. 620 West Chang’an Avenue Shaanxi Xi’an710119 China School of Aeronautics Northwestern Polytechnical University No. 127 West Youyi Road Shaanxi Xi’an710072 China AI for Science Institute Beijing100080 China DP Technology Beijing100080 China Academy for Advanced Interdisciplinary Studies Peking University Beijing100871 China School of Mathematics and Statistics Xi’an Jiaotong University No. 28 Xianning West Road Shaanxi Xi’an710049 China

We uncover a phenomenon largely overlooked by the scientific community utilizing AI: neural networks exhibit high susceptibility to minute perturbations, resulting in significant deviations in their outputs. Through an analysis of five diverse application areas—weather forecasting, chemical energy and force calculations, fluid dynamics, quantum chromodynamics, and wireless communication—we demonstrate that this vulnerability is a broad and general characteristic of AI systems. This revelation exposes a hidden risk in relying on neural networks for essential scientific computations, calling further studies on their reliability and security. © 2024, CC0.

关键词： Weather forecasting

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Twin-field quantum digital signatures

arXiv

引用

arXiv 2020年

作者： Zhang, Chun-Hui Fan, Yu-Teng Zhang, Chun-Mei Guo, Guang-Can Wang, Qin Institute of quantum information and technology Nanjing University of Posts and Telecommunications Nanjing210003 China Broadband Wireless Communication and Sensor Network Technology Key Lab of Ministry of Education NUPT Nanjing210003 China Telecommunication and Networks National Engineering Research Center NUPT Nanjing210003 China Key Laboratory of Quantum Information CAS University of Science and Technology of China Hefei Anhui230026 China

Digital signature is a key technique in information security, especially for identity authentications. Compared with classical correspondence, quantum digital signatures (QDSs) provide a considerably higher level of security, i.e., information-theoretic security. At present, its performance is limited by key generation protocols (e.g., BB84 or measurement-device-independent protocols), which are fundamentally limited in terms of channel capacity. Fortunately, the recently proposed twin-field quantum key distribution can overcome this limit. This paper presents a twin-field QDS protocol and details a corresponding security analysis. In its distribution stage, a specific key generation protocol, the sending-or-not-sending twin-field protocol, has been adopted and full parameter optimization method has been implemented. Numerical simulation results show that the new protocol exhibits outstanding security and practicality compared with all other existing protocols. Therefore, the new protocol paves the way toward real-world applications of QDSs. Copyright © 2020, The Authors. All rights reserved.

关键词： Quantum cryptography

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Average Channel Capacity Analysis for Visible Light Communications with Random Receivers

Average Channel Capacity Analysis for Visible Light Communic...

引用

International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Xian-Tao Fu Rong-Rong Lu Sheng-Hong Lin Jin-Yuan Wang Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing China Shanghai Key Laboratory of Trustworthy Computing East China Normal University Shanghai China Key Laboratory of Opto-technology and Intelligent Control Ministry of Education Lanzhou Jiaotong University Lanzhou China National Local Joint Engineering Research Center for Communication and Network Technologies Nanjing University of Posts and Telecommunications Nanjing China

ISBN: (数字)9781728172361

ISBN: (纸本)9781728172378

For indoor visible light communications (VLC), the receivers are usually set to be fixed ones in previous studies. However, the locations and orientations of receivers are affected by random factors in practical VLC systems. In this paper, the performance of VLC with random receivers is investigated. We consider an VLC system, which consists of a transmitter and a receiver. The main noise is additive white Gaussian noise. Two random factors (i.e., random location and random orientation) of the receiver are considered. Based on the established system model, closed-form expressions of the average channel capacity for systems with random location and random orientation are derived, respectively. Numerical results verify the accuracy of the derived theoretical expressions. Moreover, the impacts of the nominal optical intensity, the dimming target, the transmitter height and the Lambertian emission order on system performance are also discussed.

关键词： Visible light communication Optical transmitters Optical receivers Light emitting diodes Channel capacity High-speed optical techniques Wireless communication

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Stochastic Dynamic Modeling of Rain Attenuation: A Survey

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China Communications 2018年第3期15卷 220-235页

作者： Zhicheng Qu Gengxin Zhang Haotong Cao Jidong Xie College of Telecommunications and Information Engineering Nanjing University of Posts and Telecommunications Satellite & Mobile communication Section Nanjing University of Posts and Telecommunications National Local Joint Engineering Research Center for communication and network technology Nanjing University of Posts and Telecommunications Key Laboratory of Broadband Wireless Communication and Sensor Network Technique of Ministry of Education Nanjing University of Posts and Telecommunications

Satellite communication systems(SCS) operating on frequency bands above 10 GHz are sensitive to atmosphere physical phenomena, especially rain attenuation. To evaluate impairments in satellite performance, stochastic dynamic modeling(SDM) is considered as an effective way to predict real-time satellite channel fading caused by rain. This article carries out a survey of SDM using stochastic differential equations(SDEs) currently in the literature. Special attention is given to the different input characteristics of each model to satisfy specific local conditions. Future research directions in SDM are also suggested in this paper.

关键词： stochastic dynamic modeling rainattenuation time-series synthesizer satellitecommunication satellite link stochastic dif-ferential equations

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