Tsinghua-Johns Hopkins Joint Center for Biomedical Engineering Research Opens

An inauguration ceremony to mark the opening of the Tsinghua-Johns Hopkins Joint Center for Biomedical Engineering Research was held in the School of Medicine on January 8th, 2008. The Tsinghua-Johns Hopkins Joint Center for Biomedical Engineering Research will carry out research in such biomedical engineering frontier areas as neural engineering, medical imaging, and tissue engineering. It will also promote graduate student and faculty exchange and joint cultivation, and organize bilateral academic symposia.     

Processes and mechanism of effects of sludge dredging on internal source release in lakes

Simulated research of internal loading and collecting and analyzing the samples from the lakes were carried out before and after dredging in polluted suburb lakes, Wuli Lake (Wuxi City) and Xuanwu Lake (Nanjing City). The research results showed that dredging can inhibit internal loadings in a certain degree in a short term. The discrepancy of dredging effect and technical level, namely dredging quality, by different dredging methods will result in a difference of control of lake internal loadings. The internal loadings‘ reversion will gradually appear along with the biogeochemical processes, including suspended particle precipitation, hydrodynamic disturbance and microbio-transformation. The reversion rate mainly depends on the dredging method and the change of interfacial processes on the newborn surface layer. The higher nutrient contents and organic matter in the sediment will enhance water-sediment interfacial processes and nutrients regeneration. It is very important to study the physicochemical and biological character of lacustrine sediments before dredging for determining the dredging methods and predicting their environmental effect.     

Observation of interactions between impurities and hydrodynamics solitons

We have experimentally investigated interactions between impurities and hydrodynamic solitons in a shallow water trough subject to vertical vibration. The impurities are minor convex and concave defects located on the bottom of the trough, slightly varying the water depth. The experiments show that a shallow impurity will attract breathers and kinks while a deep one will repel them. These observations are consistent with the theoretical prediction proposed in the continuous Frankel-Kontorova model with impurities and can also be explained in the view of energy absorption.     

The analysis of the legislation on health and safety in Britain

Health and safety is an integral feature of work and employment relations. The consequences of ill-health and danger have an untold impact on workers,on their personal life,on those who enter employment settings,and on the provision of services and goods. In a variety of ways,people attempt to establish minimum standards of danger and hazard to deal with these consequences in their workplace. This essay will firstly review and assess the important issues in the development of the legislation on health and safety at work in Britain,and then analyze the recent situation on health and safety at work in Britain according to some statistics and examples. Finally,it will conclude that Business will benefit from good management of health and safety at work.     

Influence of MnS particles on the behaviors of grain boundary migration in Fe-3%Si alloys

The precipitation behaviors of MnS particles at 900℃ in a hot deformed Fe-3%Si alloy were observed statistically. The ratio of MnS particles on dislocations and in grain boundaries was calculated based on a model concerning the second phase precipitation in supersaturated solid solution. It was indicated that the precipitation of MnS particles on dislocations prevailed. The coarsening process of MnS particles in grain boundaries determined the boundary mobility during the secondary recrystallization. However, the density difference of precipitated MnS particles inside the grains on both sides of a boundary will determine the migration direction of the boundary as well, besides the grain size effect. It was observed that the densities of MnS particles in two neighboring grains were commonly different, and the boundary tended to move towards the area with lower particle density. The factors, e.g. dislocation densities in differently oriented grains will affect the density of precipitated particles, in which the Goss grains with higher particle density could grow more easily.     

Numerical Simulation of Two-dimensional Nonlinear Sloshing Problems

IntroductionSloshing is a phenomenon of great i mportance inengineering such as oil oscillationin a fuel tank,sloshing ofliquid propellant rocket and so on.The liquid in acontainer can be violent if the excitation frequency is closeto the natural frequency of liquid motion in the container,and a strong amplification of liquid motion will occur,which will cause high pressure to act on the container.Since sloshing is so i mportant for engineering,it hasbeen widely studied for many years,and vari…     

贫穷与犯罪的动力学

Poverty and crime are two maladies that plague metropolitan areas. The economic theory of crime[1]demonstrates a direct correlation between poverty and crime. The model considered in this study seeks to examine the dynamics of the poverty-crime system through stability analysis of a system of ordinary differential equations in order to identify cost-effective strategies to combat crime in metropolises.     

少儿图灵测试和常识处理

This talk presents our research work on children Turing test. It is implemented in a conversation system supported by a commonsense knowledge base. This system can talk to school children in a more or less natural way. The main difference between it and many other conversation programs is its knowledgebased character. In this talk, motivation of children Turing test and the analysis of its results will be described. We will analyze the achievements and failures of children Turing test, its main bottlenecks, its modified versions and its relation to commonsense knowledge processing. In addition, we will propose some conjectures on Turing test under certain hypotheses and give some concluding remarks.     

全球招聘新闻（英文）

正博士后[美国]Northwestern University Northwestern University opens a post-doctoral researcher position.The focus of their research is Alzheimer’s disease pathogenesis withparticular emphasis on the beta-secretase enzyme,BACE1.Thepostdoctoral research project will include investigations of the role ofBACE1 in Alzheimer’s disease and its potential as a therapeutictarget,and the normal physiological functions of the enzyme in vivo.Applicants must have a PhD in a field of the life sciences and/or MDdegree.Preference will be given to individuals with expertise in     

Retrospect and prospect: advances and future strategies in climate research

A brief review of the progress in climate research and a prospect on its further development in the 21st century is presented. Some key findings including the concept of climate system, the discovery of climatic multi-equilibrium and abrupt climate changes, and the recognition of human activities as an important force of climate change made breakthroughs in climatology possible during last few decades. The adaptation to climatic and global change emerged as a new aspect of climatic research during the 1990s. Climate research will break through in the observation of the global system, in the analysis of mass data, in the deepening of research on the mechanism of climatic change, and in the improvement of models. In the applied fields of climate research, there will be substantial progress in the research on adaptation to global change and sustainable development, on orderly human activities, and climate modification.     

Impacts of climate change on ecosystem in Priority Areas of Biodiversity Conservation in China

Priority Areas of Biodiversity Conservation （PABCs） are the key areas for future biodiversity conservation in China. In this study, we used 5 dynamic global vegetation models （DGVMs） to simulate the ecosystem function changes under future climate change scenario in the 32 terrestrial PABCs. We selected vegetation coverage, vegetation productivity, and ecosystem carbon balance as the indicators to describe the ecosystem function changes. The results indicate that woody vegetation coverage will greatly increase in the Loess Plateau Region, the North China Plain, and the Lower Hilly Region of South China. The future climate change will have great impact on the original vegetation in alpine meadow and arid and semiarid regions. The vegetation productivity of most PABCs will enhance in the coming 100 years. The largest increment will take place in the southwestern regions with high elevation. The PABCs in the Desert Region of Inner Mongolia-Xinjiang Plateau are with fastest productivity climbing, and these areas are also with more carbon sink accumulation in the future. DGVM will be a new efficient tool for evaluating ecosystem function changes in future in large scale. This study is expected to provide technical support for the future ecosystem management and biodiversity conservation under climate change.     

Charge transport in organic semiconductors: From incoherent to coherent

Quantum decoherence in organic charge transport is a complicated but crucial topic. In this paper, several theoretical approaches corresponding to it, from incoherent to coherent, are comprehensively reviewed. We mainly focus on the physical insight provided by each theory and extent of its validity. The aim of this review is to clarify some contentious issues and elaborate on the promising perspectives provided by different approaches. The device model approaches based on both continuous and discretized treatments of the transporting layer will be first discussed. The prominent focus of this review will be devoted to the dynamic disorder model and its variants considering that it is the most promising approach to tackle charge transport problems in organic materials. We will also address other theories such as the variational method.     

National Academic Standings Announced, Tsinghua Ranks First in Nine Areas

The Assessment Center for Degree and Research Education of Higher Education and Scientific Research Institu-tions has announced its latest evaluation results on academic standings in China. The assessment took place in 2003 and examined a total of 42 fields. Tsinghua received ratings for 15 subjects, 9 of which ranked highest in the country. They are: mechanical engineering, optical engineering, instrument science and technology, power engineering and thermal engineering, electrical engin…     

基于多层次模糊系统的贫困等级认定模型(英文)

Poverty,a permanent problem in the human society,is listed top-class global problem of social development by the UN. Grading the needy situation of impoverished families enables better aid policy. This paper applies the theories and methods of fuzzy mathematics and comprehensive evaluation. Based on fuzzy inference,its perform evaluations that are both qualitative and quantitative and contain exact and inexact factors. The paper determines the indexes of poverty grade according to maximum membership degree,...     

Break the Ties for NEH Heuristic in Solving the Permutation Flow Shop Problems

This study deals with the Permutation Flow Shop Scheduling Problem （PFSP） based on the maximum completion time （makespan）. NEH （ the algorithm of Nawaz, Eascore and Ham） is the concluded most efficient constructive method in solving this NP-hard problem. The principal features of its strengths are the initial arrangement of jobs and the job insertion phase. In some instances, ties will occur in both the initial permutation and the partial sequences. The problem of ties breaking may have a significant impact on the NEH performance, but evaluate all the ties will be non-polynomial in the worst case. Several kinds of methods are presented in the paper to break the ties in a quick time. Together with the basic one, all 22 methods are tested on the famous Taillard＇s benchmarks and the most suitable ties breaking policy is recommended.     

Multi-body dynamic simulation research on the influence of piston engine crankshaft thrust bearings abrasion①

Fault diagnosis studying on piston engine , crankshaft and gearbox is focused in this paper .The thrust bearing abrasion caused by axial movement of the crankshaft will affect the force of timing gears and oil pump gears , which will result in the fracture of gears , abnormal ignition, connecting rod cracking and collision of cylinder .Simulation based on CREO software is done to build three-di-mensional models of crankshaft and gears of a WP 10 diesel engine .The models are imported into ADAMS to complete multi-body dynamics simulations .The force analysis of gears in different kinds of axial movements is finished and variations rules of gear dynamic load is obtained .The presented results show that the crankshaft axial movement can cause overload and vibration on gears .Com-bined with the realistic case data , the fault feature through simulation research is validated and early warming parameters of gear fault are proposed .     

Amplitudes, rates, periodicities and causes of temperature variations in the past 2485 years and future trends over the central-eastern Tibetan Plateau

Amplitudes, rates, periodicities, causes and future trends of temperature variations based on tree rings for the past 2485 years on the central-eastern Tibetan Plateau were analyzed. The results showed that extreme climatic events on the Plateau, such as the Medieval Warm Period, Little Ice Age and 20th Century Warming appeared synchronously with those in other places worldwide. The largest amplitude and rate of temperature change occurred during the Eastern Jin Event (343-425 AD), and not in the late 20th century. There were significant cycles of 1324 a, 800 a, 199 a, 110 a and 2-3 a in the 2485-year temperature series. The 1324 a, 800 a, 199 a and 110 a cycles are associated with solar activity, which greatly affects the Earth surface temperature. The long-term trends (>1000 a) of temperature were controlled by the millennium-scale cycle, and amplitudes were dominated by multi-century cycles. Moreover, cold intervals corresponded to sunspot minimums. The prediction indicated that the temperature will decrease in the future until to 2068 AD and then increase again.     

全球招聘新

正博士后[美国]Northwestern University Northwestern University opens a post-doctoral researcher position.The focus of their research is Alzheimer’s disease pathogenesiswith particular emphasis on the beta-secretase enzyme,BACE1.The postdoctoral research project will include investigations of therole of BACE1 in Alzheimer’s disease and its potential as atherapeutic target,and the normal physiological functions of theenzyme in vivo.Applicants must have a PhD in a field of the life     

Coupling and propagating of mesoscale sea level variability between the western Pacific and the South China Sea

The coupling and propagating features of mesoscale sea level variability between the western Pacific (WP) and the South China Sea (SCS) were studied based on time series analyses of satellite altimeter measured, along-track sea surface height anomalies (SSHA) along 21°N and the slope of the northern SCS. The analyses show that mesoscale sea level fluctuations in the WP have rather limited coherent effects on the SCS, and no statistically significant propagation of mesoscale variability through the Luzon Strait was observed except in the 45-day band. Evidence suggests that the 45-day fluctuation is very much likely a character of the Kuroshio originating from its low-latitude beginning. It is also sug- gested that the westward propagating Rossby waves will deform when they encounter the dynamical barrier of the Kuroshio. The Kuroshio will then acts on the SCS in its own way. The SCS is a relatively isolated system in the sense of coupling and propagating of oceanic mesoscale waves.