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Degradation process assessment of prestressed concrete continuous bridges in life-cycle

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Journal of Central South University 2012年第5期19卷 1411-1418页

作者：田浩李国平陈艾荣 College of Civil Engineering Tongji University Zhejiang Scientific research institute of Communication

To accurately evaluate the degradation process of prestressed concrete continuous bridges exposed to aggressive environments in life-cycle,a finite element-based approach with respect to the lifetime performance assessment of concrete bridges was *** existing assessment methods were firstly introduced and *** essential mechanics problems involved in the degradation process,such as the deterioration of materials properties,the reduction of sectional areas and the variation of overall structural performance caused by the first two problems,were investigated and solved.A computer program named CBDAS(Concrete Bridge Durability Analysis System) was written to perform the above-metioned ***,the degradation process of a prestressed concrete continuous bridge under chloride penetration was *** results show that the concrete normal stress for serviceability limit state exceeds the threshold value after 60 a,but the various performance indicators at ultimate limit state are consistently in the allowable level during service ***,in the case of prestressed concrete bridges,the serviceability limit state is more possible to have durability problems in life-cycle;however,the performance indicators at ultimate limit state can satisfy the requirements.

关键词： prestressed concrete continuous bridges life-cycle degradation process finite element chloride penetration serviceability limit state ultimate limit state

Modeling and Verifying Concurrent Programs with Finite Chu Spaces

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Journal of Computer Science & Technology 2010年第6期25卷 1168-1183页

作者：杜旭涛刑春晓周立柱 Department of Computer Science and Technology Tsinghua University research institute of Information Technology Tsinghua University

Finite Chu spaces are proposed for the modeling and verification of concurrent *** order to model not only typical concurrent behaviors but also modern exception handling and synchronization mechanisms,we design an enriched process algebra of Chu spaces from a practical point of *** illustrate the power of finite Chu spaces and the process algebra while abstracting away from language-specific details,an imaginary concurrent programming language（ICL） is designed.A denotational semantics of ICL is presented using finite Chu spaces and the enriched process *** valuation functions are fairly straightforward since the carefully designed operators have done much of the *** enriched process algebra is also used as the specification language for Chu spaces,with which process-algebraic properties can be *** algorithms are presented with their time complexities discussed.

关键词： Chu spaces process algebra verification denotational semantics concurrency

Effect of time delay on the upper bound of the time derivative of information entropy in a stochastic dynamical system

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Chinese Physics B 2011年第11期20卷 122-126页

作者：张敏敏王参军梅冬成 Department of Physics Yunnan University Nonlinear research institute Baoji University of Arts and Sciences

The effects of the time delay on the upper bound of the time derivative of information entropy are investigated in a time-delayed dynamical system driven by correlated noise. Using the Markov approximation of the stochastic delay differential equations and the Schwartz inequality principle, we obtain an analytical expression for the upper bound UB（t） of the time derivative of the information entropy. The results show that there is a critical value of T （delay time）, and UB（t） presents opposite behaviours on difference sides of the critical value. For the case of the weak additive noise, T can induce a reentrance transition. Delay time T also causes a reversal behaviour in UB（t）-λplot, where λ denotes the degree of the correlation between the two noises.

关键词： information entropy upper bound time delay noise

The Effect of Transient Eddy on Interannual Meridional Displacement of Summer East Asian Subtropical Jet

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Advances in Atmospheric Sciences 2012年第3期29卷 484-492页

作者：向洋杨修群 institute for Climate and Global Change research School of Atmospheric Sciences Nanjing University

Using ERA-40 reanalysis daily data for the period 1958-2002, this study investigated the effect of tran- sient eddy （TE） on the interannual meridional displacement of summer East Asian subtropical jet （EASJ） by conducting a detailed dynamical diagnosis. The summer EASJ axis features a significant interannual coherent meridional displacement. Associated with such a meridional displacement, the TE vorticity forcing anomalies are characterized by a meridional dipole pattern asymmetric about the climatological EASJ axis. The TE vorticity forcing anomalies yield barotropic zonal wind tendencies with a phase meridionally lead- ing the zonal wind anomalies, suggesting that they act to reinforce further meridional displacement of the EASJ and favor a positive feedback in the TE and time-mean flow interaction. However, The TE thermal forcing anomalies induce baroclinic zonal wind tendencies that reduce the vertical shear of zonal wind and atmospheric baroclinicity and eventually suppress the TE activity, favoring a negative feedback in the TE and time-mean flow interaction. Although the two types of TE forcing tend to have opposite feedback roles, the TE vorticity forcing appears to be dominant in the TE effect on the time-mean flow.

关键词： East Asian subtropical jet transient eddy vorticity forcing transient eddy thermal forcing

Energy internet or comprehensive energy network?

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Journal of Modern Power Systems and Clean Energy 2015年第3期3卷 297-301页

作者： Yusheng XUE State Grid Electric Power research institute Nanjing 211000China

What needs to be developed from the concept of"Smart Grid"is that:when renewable energy sources are absolutely prevailing in power generation,distributed power generation and distributed energy storage systems are widespread across the grid,and electric vehicle charging loads are prevailing in power load demands,how can the power grid support electric power as a core secondary energy source,undertake the role of a bridge between primary energy and end-use energy,and achieve the coordination and the optimization in macro energy perspective;how to guarantee the security of both macro energy and environment as well as the reliability of *** a new term is needed,it should be Comprehensive Energy Network,not Energy Internet.

关键词： Energy security Environmental security Primary energy Electric power End-use energy Smart grid Energy internet Comprehensive energy network

Error Analysis of Robotic Assembly System Based on Screw Theory

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Journal of Donghua University(English Edition) 2003年第3期20卷 72-77页

作者：韩卫军费燕琼赵锡芳 research institute of Robotics Shanghai Jiaotong UniversityShanghai200030

Assembly errors have great influence on assembly quality in robotic assembly systems. Error analysis is directed to the propagations and accumula-tions of various errors and their effect on assembly *** the screw coordinates, assembly errors are represented as 'error twist', the extremely compact expression. According to the law of screw composition, relative position and orientation errors of mating parts are computed and the necessary condition of assembly success is concluded. A new simple method for measuring assembly errors is also proposed based on the transformation law of a *** of the compact representation of error, the model presented for error analysis can be applied to various part- mating types and especially useful for error analysis of complexity assembly.

关键词： robotic assembly system screw theory error twist error analysis

Nano-composite Particles Synthesized by a Hydrogen Arc Plasma

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Journal of Materials Science & Technology 1997年第4期13卷 315-317页

作者： Zuolin CUI Zhikun ZHANG Chuncheng HAO Lifeng DONG Zhaoguo MENG and Liyan YU(research Center of Nanostructured Materials, Qingdao institute of Chemical Technology Qingdao 266042, China) research Center of Nanostructured Materials Qingdao Institute of Chemical Technology Qingdao 266042 China

Nano-composite particles can be synthesized by a hydrogen arc plasma method, which possesses the advantages of high productivity, controllable size distribution and low electric energy consumption comparing with conventional gas condensation method. With this method, not only the nanoparticles of metals and alloys, but also the nano-composite particles with shell structure can be synthesized. The microstructures, compositions and the formation mechanism of the nano composite particles were studied

关键词： Nano-composite Particles Synthesized by a Hydrogen Arc Plasma Arc

Solvent extraction of neodymium(Ⅲ) from acidic nitrate medium using Cyanex 921 in kerosene

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Journal of Rare Earths 2012年第8期30卷 794-797页

作者： Nandita Panda Niharbala Devi Sujata Mishra Department of Chemistry Institute of Technical Education and Research Siksha 'O' Anusandhan deemed to be University

The extraction of neodymium（III） from acidic nitrate medium was investigated using Cyanex 921 as extractant in kerosene. The metal concentration in the aqueous phase before and after extraction was determined spectrophotometrically by Arsenazo III method. The complete equilibration was achieved in 15 rain. The effects of shaking time, nitric acid concentration, nitrate concentration, extractant concen- tration, and temperature on the extraction were studied. The extraction of Nd（III） was found to increase very slowly with increase in concen- tration of HNO3 in the range of 0.001-3.008 mol/L and then decreased when 0.01 mol/L HNO3 was used. The percentage of extraction was increased with increase in nitrate concentration from 0.01M）.45 mol/L and then decreased when nitrate concentration increased to 0.5 mol/L. Quantitative extraction of Nd（III）（98%） was obtained from the aqueous phase containing 0.001 mol/L HNO3 and 0.1 mol/L KNO3 using 0.5 mol/L Cyanex 921. On the basis of slope analysis, the extracted complex in the organic phase was proposed to be Nd（NO3）3.2Cyanex 921. The extraction of Nd（III） was found to increase with increase in concentration of metal ion in the range of 0.0014）.05 mol/L from 0.001 mol/L HNO3 and 0.1 mol/L KNO3 with 0.1 mol/L Cyanex 921. The percentage of extraction of neodymium was found to decrease with in- crease in temperature. From temperature variation studies, the negative value of AH indicated the extraction reaction to be exothermic and the negative value of AS indicated the formation of a stable complex, Almost 100% Nd（III） was recovered from the fully loaded organic phase using 0.002 mol/L H2SO4 and 0.01 mol/L HCl.

关键词： extraction neodymium(III) acidic nitrate Cyanex 921 kerosene stripping rare earths

New ductile laminate structure of Ti-alloy/Ti-based metallic glass composite with high specific strength

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Journal of Materials Science & Technology 2018年第4期34卷 708-712页

作者： D.Li Z.W.Zhu A.M.Wang H.M.Fu H.Li H.W.Zhang H.F.Zhang Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

Bulk laminate structure of Ti-alloy/Ti-based metallic glass composite （MGC） was prepared by melting a preform of alternate stack-up foils in the high vacuum atmosphere. The composite demonstrates a good combination of yield strength （-1618MPa）, plasticity （-4.3%） and specific fracture strength （384 × 10^3 N m kg^-1 ） in compression. The maintained yield strength results from the unique microstruc- ture composed of the Ti layer, the solution layer with gradient structure and the MGC layer. Such a multilayer structure effectively inhibits the propagation of shear band, leading to the enhanced plastic- ity. Those extraordinary properities suggest that combining ductile lamella with brittle metallic glass （MG） by such a lay-up method can be an effective way to improve mechanical properties of MG.

关键词： Laminate composite Metallic glass Specific strength Plasticity