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Optimum weighting-coefficient-pair in inter-carrier interference self-cancellation scheme of OFDM system

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第12期9卷 1676-1684页

作者： Min-jian ZHAO di zhang Bin CAI Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

As one of the most important components of the wideband wireless access technique, orthogonal frequency division multiplexing （OFDM） has a high usage rate of spectrum and combats inter-symbol interference （ISI） in multi-path fading channel. However, when there are frequency offsets during the signal transmission, the inter-carrier interference （ICI） is introduced, which significantly degrades the performance. The existing ICI self-cancellation schemes such as PCC-OFDM are not optimum to minimize the interference considering both noise and ICI. In this paper, a new metric named S1NR （signal-to-interference- and-noise ratio） is proposed. We discuss the optimization issue when a constant frequency offset exists and in time-varying channels. The optimum weighting-coefficient-pair （OWCP） is obtained, which maximizes SINR theoretically through the alternant iteration algorithm. Simulations show that the performance of OWCP-OFDM is better than that of PCC-OFDM, especially when the frequency offset is large. Although the ICI self-cancellation scheme suffers bandwidth inefficiency, from the simulation results we can also see that the performance of OWCP-OFDM is much better than that of the standard OFDM systems with the same bandwidth efficiency when a frequency offset exists. Moreover, since the redundant modulation provides the capability to suppress ICI as well as a receiving SNR gain, it can be considered as exchanging the bandwidth for SNR.

关键词： Orthogonal frequency division multiplexing (OFDM) Frequency offset Inter-carrier interference (ICI) Polynomial cancellation coding (PCC) Optimum weighting-coefficient-pair (OWCP)

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Risk-constrained Energy Management Strategy for a Commercial Campus Considering Comprehensive Reserves Against Islanding Conditions

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CSEE Journal of Power and Energy Systems 2023年第5期9卷 1797-1807页

作者： Zheming Liang Desong Bian Xiaohu zhang di Shi GEIRI North America San JoseCAUSA.Z.M.Liang is also with Huaneng Renewables Co.Ltd.Beijing 100036China

This paper proposes an optimal risk-constrained energy management strategy for commercial buildings in a commercial campus with islanding *** goal is to minimize the total operation and maintenance costs,while maximizing comprehensive comfort levels for the occupants.A two-stage riskconstrained,scenario-based stochastic optimization approach is adopted to handle various uncertainties associated with the energy management process,such as power generation of rooftop solar panels,arrival state-of-charges,and arrival/departure time of plug-in electric vehicles,intermittent load demand,and uncertain grid-connection conditions.A conditional-valueat-risk method is introduced to provide a risk-averse energy management *** face the challenge of both reducing the computational burden and maintaining the accuracy of the stochastic programming,an advanced scenario reduction method is *** simulation results validate the effectiveness of the proposed energy management strategy for minimizing total operating and maintenance costs of commercial buildings with islanding capabilities,while maximizing comprehensive comfort levels of the occupants.

关键词： Comprehensive comfort levels CVaR energy management islanding capability reserve stochastic programming uncertainty

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High capacity reversible data hiding in encrypted images based on adaptive quadtree partitioning and MSB prediction

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Frontiers of Information Technology & Electronic Engineering 2023年第8期24卷 1156-1168页

作者： Kaili QI Minqing zhang Fuqiang di Yongjun KONG Key Laboratory of Network&Information Security under Chinese People Armed Police Force Engineering University of PAPXi’an710086China

To improve the embedding capacity of reversible data hiding in encrypted images(RDH-EI),a new RDH-EI scheme is proposed based on adaptive quadtree partitioning and most significant bit(MSB)***,according to the smoothness of the image,the image is partitioned into blocks based on adaptive quadtree partitioning,and then blocks of different sizes are encrypted and scrambled at the block level to resist the analysis of the encrypted *** the data embedding stage,the adaptive MSB prediction method proposed by Wang and He(2022)is improved by taking the upper-left pixel in the block as the target pixel,to predict other pixels to free up more embedding *** the best of our knowledge,quadtree partitioning is first applied to *** results show that the proposed method is reversible and separable,and that its average embedding capacity is *** gray images with a size of 512×512,the average embedding capacity is increased by 25565 *** all smooth images with improved embedding capacity,the average embedding capacity is increased by about 35530 bits.

关键词： Adaptive quadtree partitioning Adaptive most significant bit(MSB)prediction Reversible data hiding in encrypted images(RDH-EI) High embedding capacity

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Investigation of Portevin–Le Chatelier Band Strain and Elastic Shrinkage in Al-Based Alloys Associated with Mg Contents

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Journal of Materials Science & Technology 2017年第6期33卷 580-586页

作者： Yulong Cai Suli Yang Shihua Fu di zhang Qingchuan zhang CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of China State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

The Portevin–Le Chatelier（PLC） effect in Al–2.30wt%Mg, Al–4.57wt%Mg and Al–6.91wt%Mg alloys has been investigated at various applied strain rates at room temperature in this study. Three-dimensional digital image correlation（3D-diC） technique was applied to obtaining the further insight into the spatiotemporal characteristics, in particular the influence of Mg content on deformation behaviors. Mg content has a pronounced effect on serration characteristics, including the serration type and amplitude; Mg content tends to weaken the spatial correlation of the propagative bands. Additionally, the serration amplitude linearly increases with the maximum PLC band strain; high Mg content generates a higher PLC band strain at a given serration amplitude compared with low Mg content. Mg content is found to be effective to enhance the serration amplitude, the maximum PLC band strain and also the amount of elastic shrinkage outside PLC bands.

关键词： Mg content Al–Mg alloy Portevin–Le Chatelier effect digital image correlation Elastic shrinkage

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Asynchronous control for 2-D Markov jump cyber-physical systems against aperiodic denial-of-service attacks

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Science China(Information Sciences) 2023年第7期66卷 195-209页

作者： Peng CHENG di WU Shuping HE Weidong zhang Department of Automation Shanghai Jiao Tong University School of Electrical Engineering and Automation Anhui University

This work focuses on the asynchronous controller design for two-dimensional Markov jump cyberphysical systems against denial-of-service attacks. Firstly, due to the openness of the network, it is vulnerable to cyber-attacks, resulting in the control input signal may not being sent to the designated location. Meanwhile, considering the influence of transmission delays and unavoidable packet dropout, a hidden Markov model can help to deal with the unavoidable asynchronous phenomenon between the plant mode and the controller mode. Then, by introducing the concepts of time instants and global states into two-dimensional systems, an asynchronous control scheme for two-dimensional Markov jump cyber-physical systems is successfully formulated. Subsequently, recurring to the multi-Lyapunov function method and iterative technology,sufficient conditions are achieved to make sure that the dynamic hidden two-dimensional Markov jump cyberphysical systems are asymptotically mean-square stable. To conclude, an application example related to the metal rolling process is provided to illustrate the feasibility and effectiveness of the presented asynchronous control scheme under aperiodic denial-of-service attacks.

关键词： asynchronous two-dimensional Markov jump cyber-physical systems denial-of-service attacks hidden Markov model

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Current-driving intergranular corrosion performance regeneration below the precipitates solvus temperature in Al–Mg alloy

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Journal of Materials Science & Technology 2020年第18期52卷 132-139页

作者： di zhang Zhen zhang Yanlin Pan Yanbin Jiang Linzhong Zhuang Jishan zhang Xinfang zhang State Key Laboratory of Advanced Metals and Materials University of Science and Technology Beijing.Beijing 100083China School of Materials Science and Engineering.Central South University Changsha 410083China School of Metallurgical and Ecological Engineering.University of Science and Technology Beijing Beijing 100083China

Heat treatment is an effective method to improve the intergranular corrosion resistance of the sensitized Al–Mg alloy due to dissolution of the grain boundary precipitates above the solvus temperature ofβ-*** grain boundary precipitates will grow and coarsening below the solvus *** this study,the in-situ intergranular corrosion performance regeneration of the sensitized Al–Mg alloy can be realized by low-density electro-pulsing treatment below the solvus temperature ofβ-*** findings show that the dissolution of grain boundary precipitates by electro-pulsing treatment is accelerated at relatively low temperature in comparison to traditional heat *** athermal effect produced by the interaction between atoms and electrons on the dissolution of grain boundary precipitates is the main reason for the improved corrosion resistance below the solvus temperature ofβ-phase.

关键词： Aluminium alloys Phase transformation kinetics Electro-pulsing treatment Intergranular corrosion

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Recovery and reuse of floc sludge for high-performance capacitors

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Frontiers of Environmental Science & Engineering 2022年第6期16卷 133-144页

作者： di zhang Rong Hou Wenbo Wang He Zhao Beijing Engineering Research Center of Process Pollution Control CAS Key Laboratory of Green Process and EngineeringInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

In this paper,floc sludge was transformed into porous carbon matrix composites by acidification and KOH activation at high temperature and used as an electrode material for application in *** effects of different treatment processes on the electrochemical properties of sludge materials were *** results of electrochemical tests showed that the sludge electrode exhibited excellent energy storage performance after HNO3 acidification and KOH activation with a mass ratio of 3:1(KOH/C).The specific capacitance of the sludge electrode reached 287 F/g at a current density of 1 A/*** addition,the sludge electrode material showed excellent cycle stability(specific capacity retained at 93.4%after 5000 cycles at 5 A/g).Based on XRD,FTIR,SEM,TEM,and BET surface analysis,the morphology of sludge electrode materials can be effectively regulated by chemical *** best-performing material showed a 3D porous morphology with a large specific surface area(2588 m^(2)/g)and optimal pore size distribution,improving ion channels and charge *** to the life cycle assessment of floc sludge utilization,it reduced the resource consumption and toxicity risk by more than 90%compared with ordinary sludge disposal *** work provided a cost-effective and eco-friendly sludge reuse method and demonstrated the application potential of sludge-based materials in high-performance supercapacitors.

关键词： Floc sludge Porous carbon electrode Energy storage performance Supercapacitors

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Near-Far Field Beamforming for Holographic Multiple-Input Multiple-Output

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Journal of Communications and Information Networks 2023年第2期8卷 99-110页

作者： Yutong zhang Boya di Hongliang zhang Lingyang Song State Key Laboratory of Advanced Optical Communication Systems and Networks School of ElectronicsPeking UniversityBeijing 100871China School of Electronic and Computer Engineering Peking University Shenzhen Graduate SchoolShenzhen 518055China

Recently,holographic multiple-input multiple-output(HMIMO)has motivated its potential use to support high-capacity data transmission with spatially quasi-continuous *** a practical instance of HMIMO,reconfigurable refractive surfaces(RRSs)equipped with numerous metamaterial elements are utilized as antennas by refracting incident signals from signal *** this paper,we investigate a multi-user communication system with an RRS deployed as the base station(BS)’s transmit *** mitigate the high overhead of accurate channel state information(CSI)acquisition,the codebook design and beam training are employed to perform *** the large scale of RRS,users are likely to be randomly distributed in both the near and far fields around the BS,which is unknown in *** considering radiation characteristics in both fields,a near-far field codebook is designed to be applicable to all users,regardless of their *** reduce overhead,a multi-user beam training is proposed to serve all users simultaneously by enhancing each codeword capable of covering multiple *** a general case that includes users in both fields,simulation results indicate that,without prior knowledge of user distribution,the proposed scheme outperforms state-of-the-art ones in terms of sum rate and overhead.

关键词： near-far field codebook design RRSs multi-user beam training

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Practical Quantum Private Query with Classical Participants

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Chinese Physics Letters 2019年第3期36卷 9-13页

作者： Min Xiao di-Fang zhang Institute of Computer Forensics Chongqing University of Posts and Telecommunications College of Computer Science and Technology Chongqing University of Posts and Telecommunications

Quantum key distribution(QKD)-based quantum private query(QPQ) is a practical application of QKD, which relaxes the security condition of perfectly concealing a private query to a cheating-sensitive strategy. We propose a QPQ protocol based on the delegated QKD scheme(DQKD-based QPQ), in which two almost ‘classical' clients(data user and database owner) can establish a 1-out-of-N oblivious key with the help of a cloud server with full quantum ability. Concretely, the two classical participants in the DQKD-based QPQ only need to access the quantum channel and reorder qubits, and the costly quantum operations, quantum state preparation and measurement are outsourced to a full quantum server in the cloud without leaking participants' privacy. The proposed protocol not only provides a cloud-based framework of QKD-based QPQ, but also obtains better security by a real-time security check, which can protect the security of the database and user against all potential attacks even if the quantum server is assumed to be a powerfully untrusted adversary.

关键词： QKD Private Query Participants

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High‑Efciency g‑C_(3)N_(4) Based Photocatalysts for CO_(2) Reduction:Modifcation Methods

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Advanced Fiber Materials 2022年第3期4卷 342-360页

作者： Qingtong Wang Zixi Fang Wang zhang di zhang State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong University800#Dongchuan Rd.Shanghai 200240People’s Republic of China

Photocatalysis is an efective means to solve the greenhouse efect caused by the large amount of carbon dioxide(CO_(2))emissions from fossil fuel *** carbon nitride(g-C_(3)N_(4))has the advantages of suitable band gap,easy preparation,low price,and good stability,making it a promising semiconductor ***,bulk g-C3N4 also has disadvantages such as low gas adsorption,low photocatalytic efciency,narrow spectral response,and easy recombination of electron–hole *** modifcation method based on g-C_(3)N_(4) photocatalyst helps to improve the above-mentioned *** review summarizes the research progress in recent years from four aspects:morphology adjustment,co-catalysts,heterostructures and *** aspect includes the pros and cons of diferent improvement methods,the comparison of theoretical calculations and experimental results,the application of diferent characterization methods,and the detailed listing of product yield and *** to this,there was an explanation of the basic theory of semiconductor photocatalytic CO_(2) ***,the future challenges and development prospects are also briefy prospected.

关键词： g-C_(3)N_(4) Photocatalytic CO_(2)reduction Morphology adjustment Co-catalysts Heterostructures Doping

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