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A user-space file system for on-demand legacy desktop software

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Science China(Information Sciences) 2011年第6期54卷 1142-1150页

作者： ZHANG YouHui 1.2., SU GeLin 1.2.& ZHENG WeiMin 1.2.1.department of Computer Science and Technology,{1.,{2., China 2.tsinghua National Laboratory for Information Science and Technology,{1.,{2., China 1. department of Computer Science and Technology Tsinghua University Beijing 100084 China2. Tsinghua National Laboratory for Information Science and Technology Tsinghua University Beijing 100084 China

Some user-level virtualization technologies have been used to convert legacy software (like the existing Windows desktop applications) into the on-demand software without any modification. To give the client a friendly and compatible method to access on-demand legacy software across the Internet, this paper presents a clientend file system for this usage case. It is a Windows user-space file system based on the cloud storage (where the on-demand software is stored), which converts the local file system accesses into remote visits. Quite a few optimizations are adopted and adjusted to suit the file-access-pattern of on-demand software, including the local cache, metadata/data/software prefetch and content-addressable storage (CAS), to decrease the number of remote visits and/or to overlap IO (input/output) operations with software execution. Detailed access-pattern analyses are also presented. This file system has been implemented and tests show that it is practical for much daily-used software-a local cache of limited size can provide up to 80% hit ratio and the corresponding overhead of running-time is about 37%. Owing to this method, on any compatible and networked computer, a user can use his/her personalized software conveniently although it does not exist on the local host.

关键词： on-demand software software as a service user-space file system cloud storage

The geometrical structure, electronic structure and magnetism of bimetallic Au_nM_2.(n=1. 2. M=Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd) clusters

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Science China(Physics,Mechanics & Astronomy) 2009年第7期52卷 1011-1020页

作者： GU Juan1.2. WANG ShanYing2.& GOU BingCong1.1.department of Physics, {1. Institute of Technology, {1. 1.0081. China 2.department of Physics, tsinghua university, beijing 1.0084, China department of Physics Beijing Institute of Technology Beijing 100081 China department of Physics Tsinghua University Beijing 100084 China

The geometrical structure, stability, magnetism, and electronic structure of bimetallic clusters AuM2.and Au2.2. where M are 4d transition metal elements, are investigated systematically by using the first-principles method based on density functional theory. The calculation results show that there is a large amount of low-energy isomers with the very similar structure. AuM2.and Au2.2.clusters display dramatic magnetism. The magnetic moment of the 4d element is either enhanced or weakened with respect to the bulk value, which is largely dependent on the orbital exchange-splitting.

关键词： density functional theory first-principles cluster electronic structure magnetism

Extremal eigenvalues of measure differential equations with fixed variation

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Science China Mathematics 2010年第10期53卷 2573-2588页

作者： ZHANG MeiRong 1.2.1.{1. of Mathematical Sciences,{1. {2.,beijing 1.0084,China 2.Zhou Pei-Yuan Center for Applied Mathematics,{1. {2.,beijing 1.0084,China 1. department of Mathematical Sciences Tsinghua University Beijing 100084 China2. Zhou Pei-Yuan Center for Applied Mathematics Tsinghua University Beijing 100084 China

In this paper we will study eigenvalues of measure differential equations which are motivated by physical problems when physical quantities are not absolutely *** taking Neumann eigenvalues of measure differential equations as an example,we will show how the extremal problems can be completely solved by exploiting the continuity results of eigenvalues in weak* topology of measures and the Lagrange multiplier rule for nonsmooth *** results can give another explanation for extremal eigenvalues of SturmLiouville operators with integrable potentials.

关键词： measure differential equation eigenvalue extremal value weak* topology Frechét derivative sub-differential

Degradation of 4-chlorophenol in aqueous solution by γ-radiation and ozone oxidation

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Science China chemistry 2006年第2期49卷 186-192页

作者： HU Jun1. WANG Jianlong1.2.& CHEN Rong1.1. Laboratory of Environmental Technology, Institute of Nuclear Energy Technology,{1.,{1., China 2. State Key Joint Laboratory of Environmental Simulation and Pollution Control,{1.,{1., China Correspondence should be addressed to Wang Jianlong 1. Laboratory of Environmental Technology Institute of Nuclear Energy Technology Tsinghua University Beijing 100084 China 2. State Key Joint Laboratory of Environmental Simulation and Pollution Control Tsinghua University Beijing 100084 China

The degradation of 4-chlorophenol (4-CP) by using gamma rays generated by a 60Co source in the presence of O3 was investigated. The radiolysis of 4-CP and the kinetics of 4-CP min-eralization were analyzed based on the determination of total organic carbon (TOC). The influence of initial 4-CP concentration and the free radicals scavengers (such as NaHCO3 and t-butanol) on the 4-CP degradation was also studied. The results showed that when the radiation rate was 336 Gy·min?1. 4-chlorophenol at concentration of 1. mg·L?1.could be completely degraded at the radiation dose of 2.kGy. The degradation of 4-chlorophenol could be described by a first-order reaction model, the rate constant of 4-CP degradation by combined ozonation and radiation was 0.1.1. min?1. which was 2.4 times higher than the sum of radiation (0.02.4 min?1. and ozonation (0.01.7 min?1.. It re-vealed that the combination of radiation and ozonation resulted in synergistic effect, which can re-markably increase the degradation efficiency of 4-CP.

关键词： radiolysis, 4-chlorophenol, priority pollutant, degradation, O3, synergistic effect, kinetics.

Generalized gradient projection neural networks for nonsmooth optimization problems

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Science China(Information Sciences) 2010年第5期53卷 990-1005页

作者： LI GuoCheng 1 , SONG ShiJi 2.? & WU Cheng 2.1 department of Mathematics, {1. Information Science and Technology {2., {1. 100192. China 2.department of Automation, tsinghua university, beijing 1.0084, China 1. department of Mathematics Beijing Information Science and Technology University Beijing 100192 China2. Department of Automation Tsinghua University Beijing 100084 China

Generalized gradient projection neural network models are proposed to solve nonsmooth convex and nonconvex nonlinear programming problems over a closed convex subset of R n . By using Clarke’s generalized gradient, the neural network modeled by a differential inclusion is developed, and its dynamical behavior and optimization capabilities both for convex and nonconvex problems are rigorously analyzed in the framework of nonsmooth analysis and the differential inclusion theory. First for nonconvex optimization problems, the quasi convergence results similar to those achieved by previous work are proved. For convex optimization problems, the global convergence results are proved, i.e. any trajectory of the neural network converges to an asymptotically stable equilibrium point, which is an optimal solution of the primal problem whenever it exists. This result remains valid even if the initial condition is chosen outside the feasible set. In addition, an asymptotic control result involving a Tykhonov like regularization shows that any trajectory of the revised neural network can be forced to converge toward a particular optimal solution of the primal problem. Finally, two simulation optimization algorithms for solving the optimization and control problems are designed respectively, and three typical simulation experiments are illustrated to present the accuracy and efficiency of theoretical convergence results of this paper.

关键词： nonsmooth optimization problem generalized gradient projection networks differential inclu sions convergence

Population-size-dependent branching processes in Markovian random environments

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Chinese Science Bulletin 1998年第8期43卷 635-638页

作者： WANG Hanxing 1.and DAI Yonglong 2.1. {1. of Mathematics, Shanghai {1., Shanghai 2.1.00, China 2. {1. of Mathematics, Zhongshan {1., Guangzhou 51.2.5, China department of Mathematics Shanghai University Shanghai China department of Mathematics Zhongshan University Gunngzhou China

A branching model {Z n} n≥0is considered where the offspring distribution of the population’s evolution is not only dependent on the population size, but also controlled by a Markovian environmental process {ξ n} n≥0. For this model, asymptotic behaviour is studied such as limn→∞Z n and limn→∞Z n/m n in the case that the mean m k, θof the offspring distribution converges to m>1.as the population size k grows to ∞. In the case that {ξ n} n≥0is an irreducible positive recurrent Markov chain, certain extinction (i.e. P(Z n=0 for some n)=1. and noncertain extinction (i.e. P(Z n=0 for some n)1. are studied.

关键词： Markov chains in random environments stochastic population models branching processes.

Synthesis and crystal structure of complex of Ce(NO_3)_3 with N-(3-methyl-pyridin-2.yl)-formimidoyl-(3-methyl-pyridin-2.yl) hydrazone

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Science China chemistry 2004年第3期47卷 251-256页

作者： JIANG Yinzhi1.2.& HU Weixiao1.1. {1. of Pharmaceutical Science, Zhejiang {1. of Technology, Hangzhou 31.032. China 2. {1. of Applied chemistry, Zhejiang Institute of Science and Technology, Hangzhou 31.033, China 1. department of Pharmaceutical Science Zhejiang University of Technology 310032 Hangzhou China 2. {1. of Applied {1. Zhejiang Institute of Science and Technology 310033 Hangzhou China

The reaction of 3,6-di-(3-methyl-pyridin-2.yI)-s-tetrazine (DMPTZ, II) with CeIII salt [Ce(NO3)3 · 6H2.] generates a new ligand, N-(3-methyl-pyridin-2.yl)-formimidoyl-(3-methyl-pyridin-2.yl) hydrazone (L), and forms a new complex: a mononuclear complex [Ce(L)(NO3)2.(H2.)3] · NO3 (III). Crystal data for III: space group P-1. with a = 0.71.3(4) nm, b = 1.1.39(2. nm, c = 1.4572.3) nm, α= 1.2.1.(2.°, β= 99.81.3)°, γ= 91.1.(3)°, Z = 2. V = 1.1..6(7) nm3, μ = 2.1.0} mm?1.and F(000) = 630. L acts as a tri-dentate chelating ligand in III. There are 1. coordination sites around Ce3+ of III, which are respectively occupied by seven oxygen atoms (four from two nitrate anions and three from three H2. molecules) and three nitrogen atoms (all from L). The cerium atom and three chelating nitrogen atoms are coplanar. The mechanism of the metal assisted decomposition is discussed briefly.

关键词： rare earth, complex, crystal structure, synthesize, 3,6-bis (3-methyl-pyridin-2.yl)-s-tetrazine, N-(3-methyl-pyridin- 2.yl)-formimidoyl-(3-methyl-pyridin-2.yl) hydrazone.

Perturbations of the radical of nest algebras

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Chinese Science Bulletin 1998年第7期43卷 556-560页

作者： LU Fangyan 1.and LU Shijie 2.1. {1. of Mathematics, Suzhou {1., Suzhou 2.5006, China 2. {1. of Mathematics, Zhejiang {1., Hangzhou 31.02., China department of Mathematics Suzhou University Suzhou China department of Mathematics Zhejiang University Hangzhou China

Let R N and K-N be the radical ideal and the compact operator ideal of nest algebra T(N) respectively. It is proved thatR-N+K-N=span{T∈T(N)∶TT(N)NCT}=span{T∈T(N): #σ′(ST)≤1. S∈T(N)}.

关键词： nest algebras radical perturbation.

Pole assignment in descriptor periodic systems

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Science China Mathematics 2005年第10期48卷 1309-1332页

作者： FAN Hung-Yuan~1.LIN Wen-Wei~1.& XU Shufang~2.1. {1. of Mathematics,Tsing Hua {1.,Hsinchu 30043,China 2. LMAM,School of Mathematical Sciences,Peking {1.,beijing 1.0871.China 1. department of Mathematics Tsing Hua University 30043 Hsinchu China 2. LMAM School of Mathematical Sciences Peking University 100871 Beijing China

In this paper a pole assignment problem is considered for the descriptor linear discrete-time periodic systems, which is using the periodic proportional-derivative feedback to modify a given system such that the closed loop system has a specified selfconjugate set of eigenvalues. It is shown that the complete reachability of an open loop periodic system is equivalent to the possibility of assigning an arbitrary set of the eigenvalues to the system by choosing the suitable periodic proportional-derivative feedback.A computational approach is also proposed to solve the problem, which uses the reliable numerical techniques based on the orthogonal transformations. Numerical examples are presented to illustrate the effectiveness of the proposed approach.

关键词： descriptor linear periodic system, pole assignment, proportional and derivative feedback, numerical method, periodic Schur decomposition.