检索结果-南通市图书馆

MLDA:a multi-level k-degree anonymity scheme on directed social network graphs

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2024年第2期18卷 199-215页

作者： Yuanjing HAO Long LI Liang chang Tianlong gu guangxi Key Laboratory of Trusted Software Guilin University of Electronic TechnologyGuilin 541004China Engineering Research Center of Trustworthy AI(Ministry of Education) Jinan UniversityGuangzhou 510632China

With the emergence of network-centric data,social network graph publishing is conducive to data analysts to mine the value of social networks,analyze the social behavior of individuals or groups,implement personalized recommendations,and so ***,published social network graphs are often subject to re-identification attacks from adversaries,which results in the leakage of users’***-anonymity technology is widely used in the field of graph publishing,which is quite effective to resist re-identification ***,the current researches still exist some issues to be solved:the protection of directed graphs is less concerned than that of undirected graphs;the protection of graph structure is often ignored while achieving the protection of nodes’identities;the same protection is performed for different users,which doesn’t meet the different privacy requirements of ***,to address the above issues,a multi-level-degree anonymity(MLDA)scheme on directed social network graphs is proposed in this ***,node sets with different importance are divided by the firefly algorithm and constrained connectedness upper approximation,and they are performed different-degree anonymity protection to meet the different privacy requirements of ***,a new graph anonymity method is proposed,which achieves the addition and removal of edges with the help of fake *** addition,to improve the utility of the anonymized graph,a new edge cost criterion is proposed,which is used to select the most appropriate edge to be ***,to protect the community structure of the original graph as much as possible,fake nodes contained in a same community are merged prior to fake nodes contained in different *** results on real datasets show that the newly proposed MLDA scheme is effective to balance the privacy and utility of the anonymized graph.

关键词： directed social network graph graph publishing k-degree anonymity community structure graph utility

Dynamical characteristics of geomorphologic evolution of the basins covered by Pisha-sandstone in the eastern wing of the Ordos Plateau, China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2018年第5期15卷 1046-1056页

作者： gu Zhen-kui SHI chang-xing Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China

There are several basins with high sediment yield in the Pisha-sandstone covering area of the east wing of the Ordos Plateau. Due to the lack of targeted research on the dynamical characteristics of geomorphic evolution that plays an important role in the sand production, this paper analyzed the tectonic activity intensity and erosion characteristics of the area. The results show that the intensity of tectonic activities in the area is generally moderateweak and shows an unconspicuous increase from north to south. Tectonic activity is manifested mainly in the form of uplift. The uplift rate in the lower reaches of each basin is greater than the erosion rate,which is prominent in the Kuyehe and the Tuweihe rivers. During the uplift of the regional topography,the most serious parts under erosion are generally concentrated in the upstream and midstream of basins. All longitudinal profiles of the basins have a shape close to an exponential function, which indicates that they are in the early stage of erosion evolution. The mechanisms of geomorphologic evolution of these basins have a great similarity. The conservative estimate of historical average erosion rate was less than 182–520 t/(km^2·yr), much less than that of the modern times. The average stream power values are typically distributed between 4 and102 W/m, with the larger being in the Kuyehe and the Tuweihe rivers and the smallest being in the Qinshuihe River. The maximum stream power value appears in the downstream reach, which should be the main reason for the particles being directly injected into the Yellow River. From the perspective of geomorphological evolution, the current soil and water conservation measures can hardly cure the erosion of these basins in the long run.

关键词： Dynamic characteristics Geomorphologic evolution Ordos Plateau Tectonicactivity Stream power Geomorphological parameter

Time synchronization and ranging under unknown positions and velocities

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2017年第2期60卷 271-281页

作者： gu XiaoBo chang Qing XU Yong WANG Dun School of Electronic & Information Engineering Beihang University Space Star Technology Co. Ltd

The process to achieve time synchronization and ranging for a network of mobile nodes is raising a concern among researchers, and hence a variety of joint time synchronization and ranging algorithms have been proposed in recent years. However, few of them handle the case of all-node motion under unknown positions and velocities. This study addresses the problem of determining ranging and time synchronization for a group of nodes moving within a local area. First, we examined several models of clock discrepancy and synchronous two-way ranging. Based upon these models, we present a solution for time synchronization with known positions and velocities. Next, we propose a functional model that jointly estimates the clock skew, clock offset, and time of flight in the absence of a priori knowledge for a pair of mobile nodes. Then, we extend this model to a network-wide time synchronization scheme by way of a global least square estimator. We also discuss the advantages and disadvantages of our model compared to the existing algorithms, and we provide some applicable scenarios as well. Finally, we show that the simulation results verify the validity of our analysis.

关键词： time synchronization two-way ranging relative motion clock model joint estimation

Is the mission to identify all the human proteins achievable? —Commenting on the human proteome draft maps

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2014年第10期57卷 1039-1040页

作者： chang ZengYi gu LiangCai Center for Protein Science State Key Laboratory of Protein and Plant Gene Studies School of Life Sciences Center for History and Philosophy of Science Peking University Department of Genetics Harvard Medical School

Unveiling the structure and function of all the proteins a human body produces is undoubtedly a key task for us to better understand ourselves. Although a mission difficult to achieve, this apparently becomes more feasible upon the determination of the DNA sequence of the whole human genome, which was predicted to encode a total of 20,000-25,000 proteins [1]. Recent efforts of direct （de novo） protein isolation and peptide sequencing, mainly using liquid chromatography-tandem mass spectrometry （LC-MS/ MS） and in-depth bioinformatics analyses, led to the apparent identification of over 17,000 proteins from large sets of human tissues, cell lines and body fluids [2,3].

关键词：人类蛋白质组 DNA序列 LC-MS 地图人类基因组串联质谱法蛋白分离液相色谱

Integrating BDS and GPS for precise relative orbit determination of LEO formation flying

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2018年第10期31卷 2013-2022页

作者： Bin YI Defeng gu Xiao chang Kai SHAO College of Liberal Arts and Sciences National University of Defense Technology

Low-Earth-Orbit（LEO） formation-flying satellites have been widely applied in many kinds of space geodesy. Precise Relative Orbit Determination（PROD） is an essential prerequisite for the LEO formation-flying satellites to complete their mission in space. The contribution of the BeiDou Navigation Satellite System（BDS） to the accuracy and reliability of PROD of LEO formation-flying satellites based on a Global Positioning System（GPS） is studied using a simulation method. Firstly, when BDS is added to GPS, the mean number of visible satellites increases from9.71 to 21.58. Secondly, the results show that the 3-Dimensional（3 D） accuracy of PROD, based on BDS-only, GPS-only and BDS ＋ GPS, is 0.74 mm, 0.66 mm and 0.52 mm, respectively. When BDS co-works with GPS, the accuracy increases by 29.73%. Geostationary-Earth-Orbit（GEO） satellites and Inclined Geosynchronous-Orbit（IGSO） satellites are only distributed over the Asia-Pacific region; however, they could provide a global improvement to PROD. The difference in PROD results between the Asia-Pacific region and the non-Asia-Pacific region is not apparent. Furthermore, the value of the Ambiguity Dilution Of Precision（ADOP）, based on BDS ＋ GPS, decreases by 7.50% and 8.26%, respectively, compared with BDS-only and GPS-only. Finally, if the relative position between satellites is only a few kilometres, the effect of ephemeris errors on PROD could be ignored. However, for a several-hundred-kilometre separation of the LEO satellites, the SingleDifference（SD） ephemeris errors of GEO satellites would be on the order of centimetres. The experimental results show that when IGSO satellites and Medium-Earth-Orbit（MEO） satellites co-work with GEO satellites, the accuracy decreases by 17.02%.

关键词： Ambiguity Dilution Of Precision BeiDou Navigation Satellite System Geostationary-Earth-Orbit Global Positioning System LEO formation flying Precise Relative Orbit Determination

Velocity Profiles between Two Baffles in a Shell and Tube Heat Exchanger

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2015年第4期24卷 356-363页

作者： Tae-hyun chang chang-Hoan Lee Hae-Soo Lee Kwon-Soo Lee Senior Research Fellow of RESEAT Korea Institute of Science and Technology Information Korea Institute of Science and Technology Information Postdoctoral Research Fellow School of Mechanical Engineering of Kyungnam University International University of Korea

Heat exchangers are extensively utilized for waste heat recovery,oil refining,chemical processing,and steam *** this study,velocity profiles are measured using a 3D particle image velocimetry(PIV)system between two baffles in a shell and tube heat exchanger for parallel and counter *** PIV and computational fluid dynamics results show the occurrence of some strong vectors near the *** vectors are assumed due to the clearance between the inner tubes and the front ***,the major parts of the vectors are moved out through the bottom opening of the rear baffle,and other vectors produce a large circle between the two *** simulations are conducted to investigate the effects of the baffle on the heat exchanger using the Fluent *** k-εturbulence model is employed to calculate the flows along the heat exchanger.

关键词： Baffle P1V Shell and tube heat exchanger Cut off ratio CFD

Flexible double-wall carbon foam/Cu-Co oxides based symmetric supercapacitor with ultrahigh energy density

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第29期160卷 109-117页

作者： Ruimei Yuan Xuemin Yin Shengyue gu Jingjing chang Hejun Li Advanced Interdisciplinary Research Center for Flexible Electronics Xidian UniversityXi’an 710071China Carbon/Carbon Composites Research Center Northwestern Polytechnical UniversityXi’an 710072China School of Science XI’AN University of Posts&TelecommunicationsXi’an 710121China

Electrochemical supercapacitors are regarded as a promising electrochemical energy storage device,because of its fast chargeability,long cycle life,and high power *** connection of porous carbon and extensive electroactive substances have significantly improved their ***,the unsuitable constructing strategy and unclear electrochemical mechanism lead to a mismatch between the fast double-layer effect and the sluggish Faradaic behavior at the electrode,degrading the energy density and capacitance ***,the construction strategy based on the double-wall carbon foam,carbon nanotubes and copper nanocubes provides enhanced electronic structure and ion transport path,resulting in accelerated proton transport and redox insertion/deinsertion processes,as well as surprising electrochemical behaviors of Cu-Co oxide on both positive and negative electrodes(927.9 and 427.0 F g^(−1)at 1 A g^(−1)).A flexible symmetric supercapacitor assembled with the SCF/CNT@Cu/Cu-Co-O delivers a extremely excellent *** 1 A g^(−1),the specific capacitance is 337.8 F g^(−1),the energy density hits 60 Wh kg^(−1)at the power density of 17.8 kW kg^(−1).At 10 A g^(−1),the energy density is up to 120.1 Wh kg^(−1),representing the top energy density of *** systematical structural optimization and mechanism study,this work broadens the fabricating strategy of hierarchical nanostructures and high-performance electrode materials for energy storage.

关键词： Carbon foam Cu-Co oxides Symmetric supercapacitors Energy density

Analysis of air quality characteristics of Beijing–Tianjin–Hebei and its surrounding air pollution transport channel cities in China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2020年第1期32卷 213-227页

作者： Cuicui Xiao Miao chang Peikun guo Meifeng gu Yang Li School of Environment Tsinghua University

Beijing–Tianjin–Hebei(BTH)and its surrounding areas are very important to air pollution control in *** analyze the characteristics of BTH and its surrounding areas of China,we collected 5,641,440 air quality data from 161 air monitoring stations and 37,123,000 continuous monitoring data from air polluting enterprises in BTH and surrounding cities to establish an indicator system for urban air quality *** results showed that particulate matter with aerodynamic diameters ofchanges in air quality revealed that peaks of PM2.5,PM10 and NO2 appeared from 8:00 to 10:00,while those for O3 appeared at 15:00–16:*** exposure characteristics of the 31 cities showed that six districts in Beijing had the highest air quality population exposure,and that exposure levels in Zhengzhou,Puyang,Anyang,Jincheng were higher than the average of the 31 investigated ***,multiple linear regression revealed a negative correlation between meteorological factors(especially wind and precipitation)and air quality,while a positive correlation existed between industrial pollution emissions and air quality in most of BTH and its surrounding cities.

关键词： Beijing–Tianjin–Hebei Air quality population exposure Seasonal index Hourly change Industrial pollution source emission Meteorology factors

Research Progress and Future Perspectives on Rechargeable Na-O_(2) and Na-CO_(2) Batteries

在线全文

学校读者我要写书评

暂无评论

Energy & Environmental Materials 2021年第2期4卷 158-177页

作者： Zhi Zheng chang Wu Qinfen gu Konstantin Konstantinov Jiazhao Wang Institute for Superconducting and Electronic Materials University of WollongongWollongong NSW 2522Australia The Australian Synchrotron(ANSTO) 800 Blackburn RoadClayton VIC 3168Australia

Rechargeable sodium–oxygen(Na-O_(2))and sodium–carbon dioxide(Na-CO_(2))batteries have attracted intensive research attention in recent years owing to their advantages of high theoretical energy density,modest cost,abundance of sodium resources,and promising potential for achieving real sodium–air batteries in large-scale energy storage ***,current research on Na-O_(2)and Na-CO_(2)batteries is facing enormous challenges,such as low energy efficiency and limited cycle life,which are restricting their progress at the initial ***,understanding their working principles,and the chemical and electrochemical reactions of the electrodes is indispensable to achieve their practical application and even the goal of true sodium–air *** review aims to provide an overview of the research developments and future perspectives on Na-O_(2)and Na-CO_(2)batteries,which include the major aspects,such as working mechanisms,air cathode materials design strategies,sodium anode protection,and electrolyte ***,the remaining issues and future research directions are also thoroughly discussed and presented.

关键词： anode protection cathode materials electrolytes Na-CO_(2)batteries Na-O_(2)batteries