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基于Ga_(2)O_(3)-SiC-Ag多层结构的介电常数近零超低开关阈值光学双稳态器件

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物理学报 2024年第5期73卷 109-116页

作者：胡生润季学强王进进阎结昀张天悦李培刚北京邮电大学信息光子学与光通信国家重点实验室北京100876 北京邮电大学理学院信息功能材料与器件实验室北京100876 功率器件与功率集成实验室北京邮电大学集成电路学院北京100876

光学双稳态这一非线性光学现象因其在全光系统中的巨大应用潜力而备受关注.然而微弱的非线性响应往往需要巨大的输入功率才能实现光学双稳态,导致其实用性不强.本文基于Ga_(2)O_(3)-SiC-Ag的金属-介电材料多层结构,在实现介电常数近零... 详细信息

光学双稳态这一非线性光学现象因其在全光系统中的巨大应用潜力而备受关注.然而微弱的非线性响应往往需要巨大的输入功率才能实现光学双稳态,导致其实用性不强.本文基于Ga_(2)O_(3)-SiC-Ag的金属-介电材料多层结构,在实现介电常数近零的大场增强的同时,还引入了具有大非线性系数的材料,并基于有限元法研究了介电常数近零层的厚度和长度对光学双稳态的影响.研究结果表明,光学双稳态随介电常数近零层的厚度和长度的增大而变得愈发显著,在通信波段的开关阈值低至约10^(-6)W/cm^(2),与之前报道的基于介电常数近零材料的光学双稳态相比,降低了9个数量级,展现了在光子集成电路产业化中的巨大应用潜力.

关键词：光学双稳态 Ga_(2)O_(3)-SiC-Ag 介电常数近零材料非线性光学

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TransCrowd: weakly-supervised crowd counting with transformers

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Science china(information Sciences) 2022年第6期65卷 48-61页

作者： Dingkang lIANG Xiwu CHEN Wei XU Yu ZHOU xiang BAI school of Artificial Intelligence and Automation Huazhong University of Science and Technology school of Electronic information and communication Huazhong University of Science and Technology school of Artificial Intelligence Beijing University of Posts and Telecommunications

The mainstream crowd counting methods usually utilize the convolution neural network(CNN)to regress a density map, requiring point-level annotations. However, annotating each person with a point is an expensive and laborious process. During the testing phase, the point-level annotations are not considered to evaluate the counting accuracy, which means the point-level annotations are redundant. Hence,it is desirable to develop weakly-supervised counting methods that just rely on count-level annotations, a more economical way of labeling. Current weakly-supervised counting methods adopt the CNN to regress a total count of the crowd by an image-to-count paradigm. However, having limited receptive fields for context modeling is an intrinsic limitation of these weakly-supervised CNN-based methods. These methods thus cannot achieve satisfactory performance, with limited applications in the real world. The transformer is a popular sequence-to-sequence prediction model in natural language processing(NlP), which contains a global receptive field. In this paper, we propose TransCrowd, which reformulates the weakly-supervised crowd counting problem from the perspective of sequence-to-count based on transformers. We observe that the proposed TransCrowd can effectively extract the semantic crowd information by using the self-attention mechanism of transformer. To the best of our knowledge, this is the first work to adopt a pure transformer for crowd counting research. Experiments on five benchmark datasets demonstrate that the proposed TransCrowd achieves superior performance compared with all the weakly-supervised CNN-based counting methods and gains highly competitive counting performance compared with some popular fully-supervised counting methods.

关键词： crowd counting visual transformer weakly supervised crowd analysis transformer

Analysis of User's Weight in Microblog Network Based on User Influence and Active Degree

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Journal of Electronic Science and Technology 2012年第4期10卷 368-377页

作者： Jie lian yun liu Zhen-Jiang Zhang jun-jun Cheng Fei Xiong school of Electronic and information engineering Beijing Jiaotong University Key Laboratory of Communication and Information Systems (Beijing Jiaotong University) Beijing Municipal Commission of Education

Based on user＇s in-degree distribution, traditional ranking algorithms of user＇s weight usually neglect the considerations of the differences among user＇s followers and the features of user＇s tweets. In order to analyze the factors which impact on user＇s weight, under the analysis of the data collected from SINA Microblog network, this paper discovers that user influence and active degrees are the dominant factors for this issue. The proposed algorithm evaluates user influence by user＇s follower number, the influence of user＇s followers and the reciprocity between users. User＇s active degree is modeled by user＇s participation and the quality of user＇s tweets. The models are tested by different data groups to confirm the parameters for the final calculation. Eventually, this paper compares the computational results with the user＇s ranking order given by the SINA official application. The performance of this algorithm presents a stronger stability on the fluctuant range of the value of user＇s weight.

关键词： HITS algorithm SINA Microblog,user influence user rank.

IRS辅助去蜂窝大规模MIMO系统反窃听安全波束赋形研究

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重庆理工大学学报（自然科学） 2024年第7期38卷 133-141页

作者：鲜永菊于东方邢智童梁吉申李云重庆邮电大学通信与信息工程学院重庆400065 中国人民解放军陆军工程大学通信士官学校重庆400035

为提高物理层安全通信性能,针对目前物理层通信容易受到建筑物遮挡和非法用户窃听的问题,提出了一种智能反射面(intelligent reflecting surface,IRS)辅助去蜂窝大规模多输入多输出(multiple-input multiple-output,MIMO)系统反窃听安... 详细信息

为提高物理层安全通信性能,针对目前物理层通信容易受到建筑物遮挡和非法用户窃听的问题,提出了一种智能反射面(intelligent reflecting surface,IRS)辅助去蜂窝大规模多输入多输出(multiple-input multiple-output,MIMO)系统反窃听安全传输波束赋形方案。考虑信道理想的情况下,以还原合法用户接收信号和阻止非法用户接收信号为目标,最小化发射波束赋形向量,构建了一个基站主动波束赋形向量和IRS相移的联合波束赋形问题。通过交替优化将原问题分解为基站波束赋形向量优化子问题和IRS相移优化子问题,并通过解非齐次线性方程组思想的方法,对优化子问题进行求解。仿真结果表明,相较于传统物理层安全通信方案,提出的方案能够有效使非法用户窃听信号为0,降低传输功率,并且具有较好的误码率。

关键词：智能反射面去蜂窝大规模MIMO 波束赋形物理层安全

Digital rights management independent of terminals in mobile applications

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The Journal of china Universities of posts and telecommunications 2007年第1期14卷 32-38页

作者： ZHANG li-he KONG xiang-wei YANG Cheng Department of Electronic engineering Dalian University of Technology Dalian 116023 China school of information engineering Communication University of China Beijing 100024 China

At present, most mobile terminals do not have any functions of fights management, and the cryptology-based method cannot resolve all the copyright problems in the mobile digital distribution service. With the urgent demand of digital rights management in digital distribution service, a scheme independent of terminals is proposed in this article. It integrates the watermark and signature techniques. In this article the scheme theory, architecture, service process, and performance are mainly discussed. In the end, the functional relationship between the proposed digital rights management （DRM） and the cryptology-based open mobile alliance digital rights management （OMA-DRM） is given. The analysis shows that the scheme is feasible and secure.

关键词： DRM copyright protection digital watermarking,mobile distribution service

Quality-Aware Massive Content Delivery in Digital Twin-Enabled Edge Networks

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china communications 2023年第2期20卷 1-13页

作者： yun Gao junqi liao Xin Wei liang Zhou school of communications and information engineering Nanjing University of Posts and TelecommunicationsNanjing 210003China Key laboratory of Broadband Wireless communication and Sensor Network Technology Ministry of EducationNanjing University of Posts and TelecommunicationsNanjing 210003China

Massive content delivery will become one of the most prominent tasks of future B5G/6G ***,various multimedia applications possess huge differences in terms of object oriented(i.e.,machine or user)and corresponding quality evaluation metric,which will significantly impact the design of encoding or decoding within content delivery *** get over this dilemma,we firstly integrate the digital twin into the edge networks to accurately and timely capture Quality-of-Decision(QoD)or Quality-of-Experience(QoE)for the guidance of content ***,in terms of machinecentric communication,a QoD-driven compression mechanism is designed for video analytics via temporally lightweight frame classification and spatially uneven quality assignment,which can achieve a balance among decision-making,delivered content,and encoding ***,in terms of user-centric communication,by fully leveraging haptic physical properties and semantic correlations of heterogeneous streams,we develop a QoE-driven video enhancement scheme to supply high data *** results demonstrate the remarkable performance improvement of massive content delivery.

关键词： content delivery digital twin edge networks QoD QoE

Energy-Efficient Power Allocation for IoT Devices in CR-NOMA Networks

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china communications 2021年第4期18卷 166-181页

作者： Guangfu Wu Wenyi Zheng yun li Mengyuan Zhou school of communication and information engineering Chongqing University of Posts and Telecommunications Chongqing400065China Chongqing Key laboratory of Mobile communications Technology Chongqing University of Posts and Telecommunications400065China

Non-orthogonal multiple access is a promising technique to meet the harsh requirements for the internet of things devices in cognitive radio *** improve the energy efficiency(EE)of the unlicensed secondary users(SU),a power allocation(PA)algorithm with polynomial complexity is *** first establish the feasible range of power consumption ratio using Karush-Kuhn-Tucker optimality conditions to support each SU’s minimum quality of service and the effectiveness of successive interference ***,we formulate the EE optimization problem considering the total transmit power requirements which leads to a non-convex fractional programming *** efficiently solve the problem,we divide it into an inner-layer and outer-layer optimization *** inner-layer optimization which is formulated to maximize the sub-carrier PA coefficients can be transformed into the difference of convex programming by using the first-order Taylor *** on the solution of the inner-layer optimization sub-problem,the concave-convex fractional programming problem of the outer-layer optimization sub-problem may be converted into the lagrangian relaxation model employing the Dinkelbach *** results demonstrate that the proposed algorithm has a faster convergence speed than the simulated annealing algorithm,while the average system EE loss is only less than 2%.

关键词： cognitive radio-non-orthogonal multiple access(CR-NOMA) power allocation energy efficiency internet of things(IoT)

Quantum Private Query Protocol Based on EPR Pairs

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Chinese Journal of Electronics 2018年第2期27卷 256-262页

作者： CHANG Yan XIONG Jinxin GAO xiang ZHANG Shibin YAN lili College of information Security engineering Chengdu University of Information Technology school of Computer Beijing University of Posts and Telecommunications

We propose a Quantum private query(QPQ) protocol based on device-independent Quantum key distribution(QKD) by using Einstein-Podolsky-Rosen(EPR) pairs. We analyze coherent attacks by a third party in a weaker constraints(non-signaling condition) compared with the formalism of quantum physics. We deduce the relationship between the raw key bits of Alice and the third party’s attack factor. Compared with existing QPQ protocols, our protocol is secure even when the source and measuring equipment used to distribute oblivious secret key can not be trusted. Quantum register is not needed in our protocol.

关键词： Quantum private query(QPQ) Coherent attack Einstein-Podolsky-Rosen(EPR) pairs Bell inequality

Variance-Constrained Filtering Fusion for Nonlinear Cyber-Physical Systems With the Denial-of-Service Attacks and Stochastic communication Protocol

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IEEE/CAA Journal of Automatica Sinica 2022年第6期9卷 978-989页

作者： Hang Geng Zidong Wang yun Chen Xiaojian Yi Yuhua Cheng IEEE school of Automation engineering University of Electronic Science and Technology of ChinaChengdu 611731China College of Electrical engineering and Automation Shandong University of Science and TechnologyQingdao 266590China Department of Computer Science Brunel University LondonUxbridgeMiddlesexUB83PHUnited Kingdom Key laboratory for IoT and information Fusion Technology of Zhejiang School of AutomationHangzhou Dianzi UniversityHangzhou 310018China school of Mechatronical engineering Beijing Institute of TechnologyBeijing 100081China

In this paper,a new filtering fusion problem is studied for nonlinear cyber-physical systems under errorvariance constraints and denial-of-service *** prevent data collision and reduce communication cost,the stochastic communication protocol is adopted in the sensor-to-filter channels to regulate the transmission order of *** sensor is allowed to enter the network according to the transmission priority decided by a set of independent and identicallydistributed random *** the defenders’view,the occurrence of the denial-of-service attack is governed by the randomly Bernoulli-distributed *** the local filtering stage,a set of variance-constrained local filters are designed where the upper bounds(on the filtering error covariances)are first acquired and later minimized by appropriately designing filter *** the fusion stage,all local estimates and error covariances are combined to develop a variance-constrained fusion estimator under the federated fusion ***,the performance of the fusion estimator is examined by studying the boundedness of the fused error covariance.A simulation example is finally presented to demonstrate the effectiveness of the proposed fusion estimator.

关键词： Cyber-physical system(CPS) denial-of-service attack stochastic communication protocol(SCP) variance-constrained filtering fusion