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The Coverage Holes of The Largest Component of Random Geometric Graph

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Acta Mathematicae Applicatae Sinica 2015年第4期31卷 855-862页

作者： chang-long YAO Tian-de GUO School of Mathematical Sciences Peking University School of Mathematical Sciences University of Chinese Academy of Sciences

In this paper, a domain in a cube is called a coverage hole if it is not covered by the largest component of the random geometric graph in this cube. We obtain asymptotic properties of the size of the largest coverage hole in the cube. In addition, we give an exponentially decaying tail bound for the probability that a line with length s do not intersect with the coverage of the infinite component of continuum percolation. These results have applications in communication networks and especially in wireless ad-hoc sensor networks.

关键词： random geometric graph continuum percolation wireless sensor networks, coverage

On the energy conversion in electrokinetic transports

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Applied Mathematics and Mechanics(English Edition) 2022年第2期43卷 263-274页

作者： Zhaodong DING long chang Kai TIAN Yongjun JIAN School of Mathematical Science Inner Mongolia UniversityHohhotInner Mongolia010021China School of Statistics and Mathematics Inner Mongolia University of Finance and EconomicsHohhotInner Mongolia010021China

Energy conversion in micro/nano-systems is a subject of current research,among which the electrokinetic energy conversion has attracted extensive ***,there exist two different definitions on the electrokinetic energy conversion efficiency in literature.A few researchers defined the efficiency using the pure pressure-driven flow rate,while other groups defined the efficiency based on the flow rate with the inclusion of the effect of the streaming potential *** this work,both definitions are investigated for different fluid types under the periodic electrokinetic flow *** Newtonian fluids,the two definitions give similar ***,for viscoelastic fluids,these two definitions lead to significant *** efficiency defined by the pure pressure-driven flow rate even exceeds 100%in a certain range of the *** result shows that in the case of viscoelastic flow,it is incorrect to define the energy conversion efficiency by pure pressure-driven flow *** the same time,the reason for this problem is clarified through comprehensive analysis.

关键词： electrokinetic transport energy conversion efficiency Newtonian fluid viscoelastic fluid streaming potential field

Some Properties for the Largest Component of Random Geometric Graphs with Applications in Sensor Networks

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Acta Mathematicae Applicatae Sinica 2009年第4期25卷 579-592页

作者： Ge Chen Tian-de Guo chang-long Yao School of Mathematical Science Graduate University of Chinese Academy of Sciences Beijing 100049 China

In this paper we consider the standard Poisson Boolean model of random geometric graphs G（Hλ,s; 1） in Rd and study the properties of the order of the largest component L1 （G（Hλ,s; 1）） . We prove that ElL1 （G（Hλ,s; 1））] is smooth with respect to A, and is derivable with respect to s. Also, we give the expression of these derivatives. These studies provide some new methods for the theory of the largest component of finite random geometric graphs （not asymptotic graphs as s - co） in the high dimensional space （d 〉 2）. Moreover, we investigate the convergence rate of E[L1（G（Hλ,s; 1））]. These results have significance for theory development of random geometric graphs and its practical application. Using our theories, we construct and solve a new optimal energy-efficient topology control model of wireless sensor networks, which has the significance of theoretical foundation and guidance for the design of network layout.

关键词： Random geometric graph the largest component wireless sensor networks topology control

Web service composition algorithm based on TOPSIS

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The Journal of China Universities of Posts and Telecommunications 2011年第4期18卷 89-97页

作者： ZHANG long-chang ZOU Hua YANG Fang-Chun School of Marketing Management Liaoning Technical University Huludao 125105 China State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

Independent quality of service （QoS） registration center is difficult to monitor QoS with lots of requests in Intemet environment with a large number of services and lots of service requests. It is able to reduce the load and decrease the failure rate by using multiple QoS registration centers to monitor QoS of some services with lots of requests. In addition, the heterogeneous QoS data close to user＇s habitual expression and adapts to the environment with complexity and uncertainty. This paper introduces a novel Web service composition algorithm based on technique for order preference by similarity to an ideal solution （TOPSIS）（WSCA TOPSIS） to solve the above difficulties for the fu＇st time. WSCA TOPSIS can support multiple decision-makers and heterogeneous QoS data. It includes three main steps： normalizing decision matrix, evaluating alternatives synthetically and evaluating group alternatives synthetically. Other contributions of the paper include a novel algorithm of aggregating QoS and a set of experiments that demonstrate the benefits and effectiveness of our approach. Experimental results show that the proposed algorithm can better support Web service composition with heterogeneous QoS data and multiple decision-makers.

关键词： Web service service composition TOPSIS QoS multiple decision-makers

Transient electro-osmotic and pressure driven flows of two-layer fluids through a slit microchannel

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Acta Mechanica Sinica 2013年第4期29卷 534-542页

作者： Jie Su Yong-Jun Jian long chang Quan-Sheng Liu School of Mathematical Science Inner Mongolia University School of Mathematics and Statistics Inner Mongolia University of Finance and Economics

By method of the Laplace transform, this arti- cle presents semi-analytical solutions for transient electro- osmotic and pressure-driven flows （EOF/PDF） of two-layer fluids between microparallel plates. The linearized Poisson- Boltzmann equation and the Cauchy momentum equation have been solved in this article. At the interface, the Maxwell stress is included as the boundary condition. By numerical computations of the inverse Laplace transform, the effects of dielectric constant ratio e, density ratio p, pressure ratio p, viscosity ratioμ of layer II to layer I, interface zeta potential difference △ψ, interface charge density jump Q, the ratios of maximum electro-osmotic velocity to pressure velocity , and the normalized pressure gradient B on transient veloc- ity amplitude are *** find the velocity amplitude becomes large with the interface zeta potential difference and becomes small with the increase of the viscosity. The ve- locity will be large with the increases of dielectric constant ratio; the density ratio almost does not influence the EOF ve- locity. Larger interface charge density jump leads to a strong jump of velocity at the interface. Additionally, the effects of the thickness of fluid layers （hi and h2） and pressure gradient on the velocity are also investigated.

关键词： Hydromechanics ~ Micro-parallel plates ~ Elec-tric double layer (EDL) ~ Unsteady EOF/PDF ~ Two-layerNewtonian fluids

Determination method of permafrost table in seasonal frozen soil areas under“Water-Heat-Salt”coupling

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Journal of Mountain Science 2023年第11期20卷 3266-3282页

作者： WANG Fang YANG Zhong LIU Kai LU chang-long School of Civil Engineering Anhui Jianzhu UniversityHefei 230601China School of Automobile and Traffic Engineering Hefei University of TechnologyHefei 230009China

The permafrost table is an important index for the design and construction of roads in cold regions,so it is necessary to find a convenient,accurate and fast judgment method to determine the permafrost *** this study,a three-field coupled model was established based on the hydrothermal salt coupling within the permafrost and the similarity theory,and the changes of the permafrost table under different temperature,moisture and salt conditions were numerically simulated by considering the transient temperature change and the influence of the permafrost layer on the seasonally thawed *** addition,an accelerated permafrost table test method was designed based on the time-domain variation and hydrothermal salt coupling by the similarity theory,which rapidly simulated the permafrost table change under different temperatures,moisture,and salts in the natural *** the simulation and test results with the measured values in the field,the errors are less than 3%,which verified the feasibility of the method for determining the permafrost table,and the simulated results are better than the test *** show that the results of determining the permafrost table with a single index have different degrees of deviation,and the permafrost table obtained by the temperature index is the most accurate in general,and it is more accurate to use the average value of the three indexes as the permafrost table compared with a single index.

关键词： Permafrost table Hydrothermal salt coupling Seasonally thawed layer Numerical simulation Accelerated test

Process strengthening for electrochemical reduction of solid TiO_(2) to Ti in situ

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Rare Metals 2023年第6期42卷 2104-2112页

作者： chang-long Guan Ting-An Zhang Jian-She Chen Zhi-He Dou Key Laboratory for Ecological Utilization of Multimetallic Mineral Ministry of EducationNortheastern UniversityShenyang110819China School of Environmental and Chemical Engineering Shenyang ligong UniversityShenyang110159China

In this paper,a new electrolysis device was presented with corundum crucible as an electrolytic cell in place of a graphite crucible,and in the corundum crucible a sleeve with a cathode pellet with a fluted base placed flat in it was adopted to separate the cathode and *** process of electrochemical reduction of solid TiO_(2) to Ti in situ was studied and characterized by the time-current curves and X-ray diffraction(XRD) patterns of the electrochemical reduction *** influence of CaCl_(2)doping in the cathode and the electrolysis device structures on electrochemical reduction mechanisms and the process strengthening was systematically *** results show that the oxygen content in the obtained Ti is reduced to0.51% with a cathode pellet sintering temperature of1000 ℃,sample preparation pressure of 20 MPa and CaCl_(2) doping amount of 30%.Tiny holes are formed in the cathode pellet by CaCl_(2) doping in the electrochemical reduction process,which could increase the contact area between the electrolyte and cathode and improve the electrode reaction *** new electrolysis device could reduce the carbon content in the molten salt,cathode polarization and the electrode reaction overvoltage,inhibit the chances of secondary reactions,increase the contact area between the produced Ca and cathode and strengthen the thermal reduction of TiO_(2) by Ca.

关键词： Titanium Calcium chloride Electrochemical reduction Electrolytic cell Cyclic voltammetry

One-pot tandem Barbier-Prins synthesis of tetrahydropyrans in aqueous media

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Science China Chemistry 2005年第1期48卷 38-41页

作者： WEN Meijiao TANG long chang Weixing LI Jing State Key Laboratory of Elemento-Organic Chemistry Nankai University Tianjin 300071 China State Key Laboratory of Elemento-Organic Chemistry Nankai University Tianjin 300071 China State Key Laboratory of Elemento-Organic Chemistry Nankai University Tianjin 300071 China State Key Laboratory of Elemento-Organic Chemistry Nankai University Tianjin 300071 China

By investigating the effect of the amount of water, the ratio of aldehyde and allyl- bromide, and the reaction temperature on the transformation, 2,4,6-trisubstituted tetrahydro- pyrans are synthesized by a novel tandem Barbier-Prins-cyclization reaction in the presence of micro-amount of water under mild conditions. The experiment is easy to perform without the need to exclude moisture or air. The reaction is atomic economical and environmentally benign.

关键词： Barbier-type, Prins-cyclization, tetrahydropyran, water, environment benign.

Simulation and control strategy for the variational influent of WWTP

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Journal of Environmental Sciences 2006年第1期18卷 62-68页

作者： LIU Yan-chen FAN long SHI Han-chang WANG Zhi-qiang State Key Joint Laboratory of Environment Simulation and Pollution Control Department of Environmental Science and Engineering TsinghuaUniversity Beijing 100084 China

With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant （WWTP） was produced and has been widely used. The dynamic change of the quality and flow of influent are major factors causing the unstable operation of wastewater treatment process. As a basic model, ASMI model was used for the simulation of activated sludge process, and double exponential model was selected for the simulation of secondary sedimentation tank. The influences of influent change to the aeration tank and secondary sedimentation tank were investigated, and the relationship among influent change, the quality of effluent and the level of sludge blanket in secondary sedimentation tank was established. On the basis of the simulation results, the operation of the WWTP could be adjusted under the dynamic change of the influent. Furthermore, the controlling strategy combined the feed-forward on the influent flow and the feedback on the level of sludge blanket in the secondary sedimentation tank was studied.

关键词： modeling dynamic simulation static simulation controlling strategy influent