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Outage-driven link selection for secure buffer-aided networks

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science china(information sciences) 2022年第8期65卷 197-212页

作者： Dawei WANG Tianmi HE Fuhui ZHOU Julian CHENG Ruonan ZHANG Qihui wu school of Electronics and information Northwestern Polytechnical University College of Electronic and information engineering Nanjing University of Aeronautics and Astronautics National Mobile Communications Research Laboratory Southeast University school of engineering The University of British Columbia Research & Development Institute of Northwestern Polytechnical university in Shenzhen Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space Nanjing University of Aeronautics and Astronautics

In this paper, we investigate secure communication in a two-hop wireless network, where multiple buffer-aided relays assist to securely forward data from the sender to the destination threatened by a passive eavesdropper. To satisfy the security and delay requirements, we propose a novel link selection policy without the instantaneous wiretap channel state information. Different from the most current link selection policies,the proposed link selection policy is designed by joint considering the link secrecy outage probability and the buffer states. To evaluate the secrecy performance, we first characterize the system state transition matrix and the stationary state probability, and then derive the closed-form expressions for the secrecy outage probability and the secrecy rate. Moreover, we formulate a framework based on the queuing theory to analyze the end-to-end information delay at the source, the relays, and the queues, and derive the closed-form expression for the information delay. Finally, we conduct simulations to validate our theoretical performance analysis, and verify the performance improvement of the proposed outage-driven secure transmission scheme in terms of secrecy outage probability and information delay.

关键词： buffer-aided relay information delay link selection secrecy outage probability

Removal of multicomponent VOCs in off-gases from an oil refining wastewater treatment plant by a compost-based biofilter system

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Frontiers of Environmental science & engineering 2009年第4期3卷 483-491页

作者： Dan wu Chunyan ZHANG Changjun GENG Li HAO Xie QUAN school of Environmental science Liaoning UniversityShenyang 110036China school of Environmental and Biological science and technology Dalian University of TechnologyDalian 116024China Research Institute of Daqing Petrochemical Company Daqing 163714China

Waste gases from oil refining wastewater treatment plants are often characterized by the presence of multicomponent and various concentrations of *** evaluation of the performance and feasibility of removing multicomponent volatile organic compounds(VOCs)in off-gases from oil refining wastewater treatment plants was conducted in a pilot-scale compost-based biofilter *** system consists of two identical biofilters packed with compost and polyethylene(PE).This paper investigates the effects of various concentrations of nonmethane hydrocarbon(NMHC)and empty bed residence time(EBRT)on the removal efficiency of *** on the experimental results and practical applications,an EBRT of 66 s was applied to the biofilter *** removal efficiencies of NMHC were within the range of 47%–100%.At an EBRT of 66 s,the average removal efficiency of benzene,toluene,and xylene were more than 99%,99%,and 100%,*** results demonstrated that multicomponent VOCs in off-gases from the oil refining wastewater treatment plant could be successfully removed in the biofilter system,which may provide useful information concerning the design criteria and operation of full-scale biofilters.

关键词： biodegradation volatile organic compounds(VOCs) biofiltration biofilter

An Open Source Toolkit for Identifying Comparative Space-time Research Questions

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Chinese Geographical science 2014年第3期24卷 348-361页

作者： YE Xinyue SHE Bing wu Ling ZHU Xinyan CHENG Yeqing Computational Social science Lab & Department of Geography Kent State University State Key Lab of information engineering in Surveying Mapping and Remote Sensing Wuhan University College of Criminal Justice Zhongnan University of Economics and Law Northeast Institute of Geography and Agroecology Chinese Academy of Sciences

Comparative space-time thinking lies at the heart of spatiotemporally integrated social sciences. The multiple dimensions and scales of socioeconomic dynamics pose numerous challenges for the application and evaluation of public policies in the comparative context. At the same time, social scientists have been slow to adopt and implement new spatiotemporally explicit methods of data analysis due to the lack of extensible software packages, which becomes a major impediment to the promotion of spatiotemporal thinking. The proposed framework will address this need by developing a set of research questions based on space-time-distributional features of socioeconomic datasets. The authors aim to develop, evaluate, and implement this framework in an open source toolkit to comprehensively quantify the changes and level of hidden variation of space-time datasets across scales and dimensions. Free access to the source code allows a broader community to incorporate additional advances in perspectives and methods, thus facilitating interdisciplinary collaboration. Being written in Python, it is entirely cross-platform, lowering transmission costs in research and education.

关键词： open source comparative spatiotemporally integrated social sciences

Detection of false data injection attacks on power systems using graph edge-conditioned convolutional networks

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Protection and Control of Modern Power Systems 2023年第2期8卷 1-12页

作者： Bairen Chen Q.H.wu Mengshi Li Kaishun Xiahou school of Electric Power engineering South China University of TechnologyGuangzhou 510641China

State estimation plays a vital role in the stable operation of modern power systems,but it is vulnerable to cyber *** data injection attacks(FDIA),one of the most common cyber attacks,can tamper with measure-ment data and bypass the bad data detection(BDD)mechanism,leading to incorrect results of power system state estimation(PSSE).This paper presents a detection framework of FDIA for PSSE based on graph edge-conditioned convolutional networks(GECCN),which use topology information,node features and edge *** deep graph architecture,the correlation of sample data is effectively mined to establish the mapping relationship between the estimated values of measurements and the actual states of power *** addition,the edge-conditioned convolution operation allows processing data sets with different graph *** studies are undertaken on the IEEE 14-bus system under different attack intensities and degrees to evaluate the performance of *** results show that GECCN has better detection performance than convolutional neural networks,deep neural net-works and support vector ***,the satisfactory detection performance obtained with the data sets of the IEEE 14-bus,30-bus and 118-bus systems verifies the effective scalability of GECCN.

关键词： Power system state estimation(PSSE) Bad data detection(BDD) False data injection attacks(FDIA) Graph edge-conditioned convolutional networks(GECCN)

Approximate Solution of Oil Film Load-carrying Capacity of Turbulent Journal Bearing with Couple Stress Flow

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Chinese Journal of Mechanical engineering 2015年第1期28卷 106-114页

作者： ZHANG Yongfang wu Peng GUO Bo L Yanjun LIU Fuxi YU Yingtian school of Printing and Packaging engineering Xi'an University of Technology State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University College of engineering Michigan State University Xi'an Institute of Mechatronics information technology school of Mechanical and Precision Instrument engineering Xi'an University of Technology Department of Civil engineering University of California Los Angeles

The instability of the rotor dynamic system supported by oil journal bearing is encountered frequently, such as the half speed whirl of the rotor, which is caused by oil film lubricant with nonlinearity. Currently, more attention is paid to the physical characteristics of oil film due to an oil-lubricated journal bearing being the important supporting component of the bearing-rotor systems and its nonlinear nature. In order to analyze the lubrication characteristics of journal bearings efficiently and save computational c[~brts, an approximate solution of nonlinear oil film forces of a finite length turbulent journal bearing with couple stress flow is proposed based on Sommerfeld and Ocvirk numbers. Reynolds equation in lubrication of a finite length turbulent .journal bearing is solved based on multi-parametric principle. Load-carrying capacity of nonlinear oil film is obtained, and the results obtained by different methods are compared. The validation of the proposed method is verified, meanwhile, the relationships of load-carrying capacity versus eccentricity ratio and width-to-diameter ratio under turbulent and couple stress working conditions are analyzed. The numerical results show that both couple stress flow and eccentricity ratio have obvious influence on oil film pressure distribution, and the proposed method approximates the load-carrying capacity of turbulent journal bearings efficiently with various width-to-diameter ratios. This research proposes an approximate solution of oil film load-carrying capacity of turbulent journal bearings with different width-to-diameter ratios, whicb are suitable for high eccentricity ratios and heavy loads.

关键词： finite length turbulent journal bearing couple stress fluid multi-parametric principle

A new method of pseudo absence data generation in landslide susceptibility mapping with a case study of Shenzhen

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science china(Technological sciences) 2010年第S1期53卷 75-84页

作者： XIAO ChenChao TIAN Yuan SHI WenZhong GUO QingHua wu Lun Institute of Remote Sensing and Geographic information System Peking UniversityBeijing 100871China university of Salzburg Z_GISCenter for GeoinformaticsSchillerstraβe 305020 SalzburgAustria Department of Land Surveying and Geo-Informatics Hong Kong Polytechnic UniversityHong KongChina school of engineering University of California MercedMerced 95343USA

Landslide susceptibility mapping is a typical two-class classification problem where generating pseudo absence (non-slide) data plays an important *** this paper,a new method,target space exteriorization sampling method (TSES),is presented to generate pseudo absence data based on presence data directly in feature *** exteriorizes a presence sample to become a pseudo absence one by replacing the value of one of its features with a new one outside the value range of this feature of all presence *** method is compared with two existing methods,buffer controlled sampling (BCS) and iteratively refined sampling (IRS),in a study area of Shenzhen *** pseudo absence data generated by each of these three methods are organized into 20 subsets with increasing data sizes to study the effects of the proportion of pseudo absence data to presence *** landslide susceptibility maps of the study area are calculated with all these datasets by general additive model (GAM).It can be concluded that,through a 10-fold validation,TSES and IRS-based models have similar AUC values that are both greater than that of BCS,but TSES outperforms BCS and IRS in prediction *** results also have more reasonable spatial and histogram distributions than BCS and IRS,which can support categorization of an area into more susceptibility ranks,while IRS shows a tendency to separate the whole study area into two susceptibility *** can be also concluded that when using BCS,the pseudo absence data proportion to the presence data would be about 50% to get a considerable result,while for IRS or TSES the minimum proportion is 40%.

关键词： pseudo absence data landslide susceptibility mapping GIS GAM

Design of a 10 bit high resolution,high speed time-to-digital converter using a two-step pulse-train time amplifier

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The Journal of china Universities of Posts and Telecommunications 2018年第1期25卷 78-84页

作者： wu Zebo Chen Bingxu Fan Chuanqi Wang Yuan Jia Song school of Electronic engineering and Computer science Peking University College of Communication and information technology Beijing University of Posts and Telecommunications

A high resolution and fast conversion rate time-to-digital converter （TDC） design based on time amplifier （TA） is proposed. The pulse-train TA employs a two-step scheme. The input time interval is first amplified by a N-times TA and the effective time is extracted in pulse-train using a time-register. Then the resulted interval is further amplified by the other pulse-train amplifier to obtain the final result. The two-step TA can thus achieve large gain that is critical for high resolution TDC. Simulation results in 1.2 V, 65 nm technology showed that for a 10 bit TDC, a resolution of 0. 8 ps and a conversion rate of 150 MS/s are achieved while consuming 2. 1 mW power consumption.

关键词： time-to-digital converter time amplifier two-step architecture time register

Illuminating Recommendation by Understanding the Explicit Item Relations

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Journal of Computer science & technology 2018年第4期33卷 739-755页

作者： Qi Liu Hong-Ke Zhao Le wu Zhi Li En-Hong Chen Anhui Province Key Laboratory of Big Data Analysis and Application University of Science and Technology of China Hefei 230027 China school of Computer and information Hefei University of Technology Hefei 230009 China school of Software engineering University of Science and Technology of China Hefei 230051 China

Recent years have witnessed the prevalence of recommender systems in various fields, which provide a personalized recommendation list for each user based on various kinds of information. For quite a long time, most researchers have been pursing recommendation performances with predefined metrics, e.g., accuracy. However, in real-world applications, users select items from a huge item list by considering their internal personalized demand and external constraints. Thus, we argue that explicitly modeling the complex relations among items under domain-specific applications is an indispensable part for enhancing the recommendations. Actually, in this area, researchers have done some work to understand the item relations gradually from ＂implicit＂ to ＂explicit＂ views when recommending. To this end, in this paper, we conduct a survey of these recent advances on recommender systems from the perspective of the explicit item relation understanding. We organize these relevant studies from three types of item relations, i.e., combination-effect relations, sequence-dependence relations, and external-constraint relations. Specifically, the combination-effect relation and the sequence-dependence relation based work models the intra-group intrinsic relations of items from the user demand perspective, and the external-constraint relation emphasizes the external requirements for items. After that, we also propose our opinions on the open issues along the line of understanding item relations and suggest some future research directions in recommendation area.

关键词： recommender system item relation recommendation interpretability

Origin软件在物理实验数据处理中的应用

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实验科学与技术 2009年第4期7卷 60-62页

作者：牟中飞吴福根胡义华王银海广东工业大学实验教学部广州510006 广东工业大学物理与光电工程学院广州510006

为提高物理课程学习和物理学研究中实验数据的处理水平,文章将Origin软件应用于多个物理实验的数据处理过程。应用中发现,Origin软件的数据分析和图形处理功能十分强大,可以大大简化实验数据处理过程,并可获得手工绘图及用电子计算器计... 详细信息

为提高物理课程学习和物理学研究中实验数据的处理水平,文章将Origin软件应用于多个物理实验的数据处理过程。应用中发现,Origin软件的数据分析和图形处理功能十分强大,可以大大简化实验数据处理过程,并可获得手工绘图及用电子计算器计算难以获得的更大的信息量,在物理实验数据处理过程中有显著的应用价值。

关键词： Origin软件物理实验曲线拟合