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Scalable peer-to-peer resource discovering scheme for wireless self-organized networks

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The Journal of China Universities of Posts and Telecommunications 2009年第2期16卷 47-52,57页

作者： li xi JI Hong Key Laboratory of Universal Wireless Communications Minisa-y of Education Beijing University of Posts and Telecommunications Beijing 100876 China

Peer-to-peer technologies have attracted increasing research attention with fruitful protocols and applications proposed for wired networks. As to mobile environments, there are currently no mature deployments. A novel resource managing and discovering protocol, Cheer, is proposed to realize scalable and effective peer-to-peer lookup in wireless self-organized networks. Cheer resolves the topologies mismatch problem between peer-to-peer overlay networks and actual nodes distribution, allowing for frequent nodes membership changes. With specially designed resource storage table, Cheer also supports multikey and fuzzy lookup. Its hybrid architecture and improved routing scheme based on small-world theory may realize effective lookup routing. Theoretical analysis and simulation results both prove that Cheer makes using peer-to-peer applications in large-scale self-organized mobile networks feasible and promising.

关键词： peer-to-peer small-world resource discovering

NUMERICAL SIMULATIONS OF NONliNEAR WAVE TRANSFORMATION AROUND WAVE-PERMEABLE STRUCTURE

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Journal of Hydrodynamics 2005年第6期17卷 699-703页

作者： li xi YAN Yi-xin Department of Ocean Engineering Hohai University Nanjing 210098 China

The problem of wave partial/full reflection and transmission by wave-permeable structure is approached by solving the shape-related function with focus on the understanding of wave attenuation. 2D depth averaged Boussinesq type wave equations are given with new damping item in simulating the nonlinear wave transmission through wave-permeable structure. 1D wave equation is examined to give the analytical expression of the absorbing coefficient, and is compared with laboratory data in flume to calibrate the coefficients, and the expression is applied directly in modified Boussinesq type equations. Compared with wave basin data for various incident wave conditions, the accurate predictions of combined diffraction refraction effects in simulating nonlinear wave going through wave-permeable breakwater in the engineering application can be obtained. It shows that wave-permeable breakwaters with proper absorbing effects can be used as an effective alternative to massive gravity breakwaters in reduction of wave transmission in shallow water.

关键词： Boussinesq equations wav-absorbing coeffieient wave permeable breakwaters

Experimental and numerical study on surface roughness of magnetorheological elastomer for controllable friction

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Friction 2020年第5期8卷 917-929页

作者： Rui li xi li Yuanyuan li Ping-an YANG Jiushan liU Key Laboratory of Industrial Internet of Things&Networked Control Ministry of EducationChongqing University of Posts and TelecommunicationsChongqing 400065China School of Automation Chongqing University of Posts and TelecommunicationsChongqing 400065China

Magnetorheological elastomer (MRE) is a type of smart material of which mechanical and electrical properties can be reversibly controlled by the magnetic field. In this study, the influence of the magnetic field on the surface roughness of MRE was studied by the microscopic modeling method, and the influence of controllable characteristics of the MRE surface on its friction properties was analyzed by the macroscopic experimental method. First, on the basis of existing studies, an improved mesoscopic model based on magneto-mechanical coupling analysis was proposed. The initial surface morphology of MRE was characterized by the W–M fractal function, and the change process of the surface microstructures of MRE, induced by the magnetic interaction between particles, was studied. Then, after analyzing the simulation results, it is found that with the increase in the magnetic field and decrease in the modulus of rubber matrix, the surface of MRE changes more significantly, and the best particle volume fraction is within 7.5%–9%. Furthermore, through experimental observation, it is found that the height of the convex peak on the surface of MRE decreases significantly with the action of the magnetic field, resulting in a reduction in the surface roughness. Consistent with the simulation results, a particle volume fraction of 10% corresponds to a maximum change of 14%. Finally, the macroscopic friction experiment results show that the friction coefficients of MREs with different particle volume fractions all decrease with the decrease in surface roughness under the magnetic field. When the particle volume fraction is 10%, the friction coefficient can decrease by 24.7% under a magnetic field of 400 mT, which is consistent with the trend of surface roughness changes. This shows that the change in surface morphology with the effect of the magnetic field is an important factor in the control of MRE friction properties by magnetic field.

关键词： controllable friction surface roughness magnetorheological elastomer(MRE) mesoscopic model coupled magneto-mechanical analysis numerical simulation

Remote sensing of human beings-a perspective from nighttime light

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Geo-Spatial Information Science 2016年第1期19卷 69-79页

作者： Deren li xia Zhao xi li State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina Collaborative Innovation Centre of Geospatial Technology Wuhan UniversityWuhanChina

City lights,fishing boats,and oil fields are the major sources of nighttime lights,therefore the nighttime light images provide a unique source to map human beings and their activities from outer *** most of the scholars focused on application of nighttime light remote sensing in urbanization and regional development,the actual fields are much *** paper summarized the applications of nighttime light remote sensing into fields such as the estimation of socioeconomic parameters,monitoring urbanization,evaluation of important events,analyzing light pollution,fishery,*** estimation of socioeconomic parameters,the most promising progress is that Gross Domestic Product and its growth rate have been estimated with statistical data and nighttime light data using econometric *** monitoring urbanization,urban area and its dynamics can be extracted using different classification methods,and spatial analysis has been employed to map urban *** sharp changes of nighttime light are associated with important socioeconomic events,the images have been used to evaluate humanitarian disasters,especially in the current Syrian and Iraqi *** pollution is another hotspot of nighttime light application,as the night light is related to some diseases and abnormal behavior of animals,and the nighttime light images can provide light pollution information on large scales so that it is much easier to analyze the effects of light *** each field,we listed typical cases of the *** last,future studies of nighttime light remote sensing have been predicted.

关键词： Nighttime lights socioeconomics human activities remote sensing data mining

RAYLEIGH-TAYLOR INSTABIliTIES BY OVERTURNING EXPERIMENTS IN TANK

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Journal of Hydrodynamics 2007年第3期19卷 303-308页

作者： li xi CHU Vincent H. Department of Ocean and Traffic Engineering Hohai University Nanjing 210098 China Deptartment of Civil Engineering and Applied Mechanics McGill University Montreal H3A 2K6 Canada

A laboratory study of the turbulence front initiated by the Rayleigh-Taylor instabilities was conducted by overturning a two-layer stratified flow in a tank. Dye was introduced to the upper layer and the concentration of the dye was determined using a video imaging method. The mass center of the heavier upper layer moved continuously to a lower elevation because of the intrusion of the heavier fluid into the lower layer and the lighter fluid into the upper layer. The downward movement of the mass center was accurately determined from the dye concentration profile. It is concluded that the initial advancement of the mass center follows a quadratic relation with time and the final advancement obeys a linear relation with time.

关键词： Rayleigh-Taylor instability stratified flow turbulent mixing video imaging technique overturning experiment

Genesis of ultra-deep dolostone and controlling factors of largescale reservoir:A case study of the Sinian Dengying Formation and the Cambrian Longwangmiao Formation in the Sichuan Basin

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Science China Earth Sciences 2024年第7期67卷 2352-2382页

作者： xi li Guangyou ZHU Zhiyao ZHANG PetroChina Research Institute of Petroleum Exploration and Development Beijing 100083China School of Geosciences Yangtze UniversityWuhan 430100China School of Earth Resoures China University of GeosciencesWuhan 430074China

This paper investigates the origin of ultra-deep dolostone and the factors influencing large-scale dolostone reservoirs,focusing on the Sinian Dengying Formation and the Cambrian Longwangmiao Formation in the Sichuan *** study involves petrology,microscale X-ray diffraction,trace element analysis,and C-O-Sr-Mg isotope experiments to provide a detailed *** research findings indicate that the Dengying and Longwangmiao formations comprise six types of matrix dolostone and four types of *** Dengying Formation,which developed under a sedimentary background of a restricted platform,contains special microbial and microcrystalline *** dolomite grains are small(line,and calcite dolostones with coarser and more ordered crystals exhibit similar δ^(13)C and^(87)Sr/^(86)Sr values to microbial and microcrystalline *** the sedimentary period of the Dengying Formation,ancient marine conditions were favorable for microbial *** induced the direct precipitation of primary dolomite in seawater,forming microbial and microcrystalline dolostones during the seawater diagenesis *** the subsequent diagenesis period,dolostones underwent the effects of dissolution-recrystallization,structures,and hydrothermal *** resulted in the formation of dolostone with coarser crystals,a higher degree of order,and various types of *** Longwangmiao Formation was developed in an interplatform beach characterized by special particle *** particle dolostone has a large grain size(>30μm),high order degree(Min=0.7),small unit cell parameters,high Na content

关键词： Ultra-deep layers Dolostone Supercontinent evolution Microscale geochemistry Dengying Formation Longwangmiao Formation Sichuan Basin

Martensitic Transformation and Its Thermal Cycling Stability in Ni_(56)Mn_(21)Cu_4Ga_(19)High-Temperature Shape Memory Ribbon

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Acta Metallurgica Sinica(English Letters) 2015年第2期28卷 243-248页

作者： xi-li Lu De-xi Su Feng Chen Wei-li liu Yang-Guang Shi Yun-xiang Tong li li Center for Biomedical Materials and Engineering Key Laboratory of Superlight Material and Surface TechnologyMinistry of Education Harbin Engineering University Department of Applied Physics Nanjing University of Aeronautics and Astronautics

The microstructure, martensitic transformation, and thermal cycling stability of Ni56Mn21Cu4Ga19 high-tem- perature shape memory ribbons subjected to different annealing conditions were investigated and compared with that of the bulk master alloy. It was shown that 7 phases precipitated in the bulk and the ribbons annealed for 5 h at 800 and 900 ℃, which lead to the same poor thermal cycling stability. However, the formation of 7 phase was inhibited in the ribbons annealed at 700 ℃ for 30 rnin and 5 h, which remarkably improved the thermal cycling stability and also shifted the martensitic transformation to a lower temperature with a drop of about 60 ℃ than other three samples.

关键词： Ni-Mn-Cu-Ga Annealing Melt spinning Martensitic transformation Shape memory alloy

Design formulas of transmission coefficients for permeable breakwaters

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Water Science and Engineering 2014年第4期7卷 457-467页

作者： Su-xiang ZHANG xi li Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science and Technology Department of Civil Engineering and Applied Mechanics McGill University College of Harbor Coastal and Offshore EngineeringHohai University

New empirical formulas of the transmission coefficient for permeable breakwaters were suggested based on available experimental data regarding the low-crest structure （LCS）, including the permeable rubble mound breakwater and pile-type breakwater. The rationality of the present formulas was verified by their comparison with existing empirical and analytical formulas. Numerical flume results were obtained by solving the modified Boussinessq-type wave equations （MBEs）, and a new expression relating the friction coefficient of to the relative submerged depth Rt/H8 was also derived. Comparative analysis shows that the results of the present formulas agree with the numerical flume results as well as available experimental data, and the present formulas are superior to the existing empirical and analytical expressions in estimating the transmission coefficient. The present formulas can provide references for estimation of the transmission coefficient in engineering practice.

关键词： permeable breakwater transmission coefficient wave reflection nonlinear wave Boussinesq wave model low-crest structure

‘‘Complexation–precipitation'' metal separation method system and its application in secondary resources

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Rare Metals 2014年第4期33卷 369-378页

作者： Zuo-Ren Nie li-Wen Ma xiao-li xi College of Materials Science and Engineering Beijing University of Technology

Recovery processes of secondary resources usually encounter problems because of the diverse com- positions of wastes. To enhance the applicability of tradi- tional hydrometallurgical process toward secondary resources, the adjustment of components is necessary. In traditional hydrometallurgical separation, precipitation and complexation are extensively used. However, their com- bination as a specific metal separation method has not yet been studied in detail. This approach is very promising for solving problems caused by changeable components during recycling processes of secondary resources. This paper reviews the effects of precipitation and complexation in metal separation processes, and a metal separation method system of ＂complexation-precipitation＂ developed to adjust the components of secondary resources is introduced.

关键词： Secondary resources Complexation-precipitation Method system Metal separation