检索结果-南通市图书馆

Generalized gradient projection neural networks for nonsmooth optimization problems

在线全文

学校读者我要写书评

暂无评论

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, beijing Information Science and technology {3., beijing 100192, china 2 department of Automation, tsinghua university, beijing 100084, china department of Mathematics Beijing Information Science and Technology University Beijing China department of Automation Tsinghua University Beijing 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

Fuzzy dynamic characteristic modeling and adaptive control of nonlinear systems and its application to hypersonic vehicles

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Information Sciences) 2011年第3期54卷 460-468页

作者： LI HongBo , SUN ZengQi, MIN HaiBo & DENG JianQiu department of computer Science and technology, {3., beijing 100084, china department of computer Science and technology Tsinghua University Beijing China

In this paper, a fuzzy dynamic characteristic modeling and adaptive control method is proposed for a class of nonlinear systems. By employing fuzzy dynamic characteristic model, the controlled plant is described as a slowly time-varying fuzzy system, wherein the parameters are estimated online by using recursive Least-Squares algorithm. Under this framework, a fuzzy adaptive controller is constructed, and the stability condition of the closed-loop system is also derived. The main advantage of the proposed method lies in no requirement for the prior knowledge of system model and less parameters to tune, which allows engineers to operate it in a simple, straightforward manner. The proposed method is applied to the control of hypersonic vehicle, and simulation results are given to demonstrate the effectiveness of the obtained results.

关键词： fuzzy control dynamic characteristic model adaptive control hypersonic vehicle

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

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

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, beijing Institute of technology, beijing 100081, china 2 department of Physics, tsinghua university, beijing 100084, china department of Physics Beijing Institute of Technology Beijing China department of Physics Tsinghua University Beijing China

The geometrical structure, stability, magnetism, and electronic structure of bimetallic clusters AuM2 and Au2M2, 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 Au2M2 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

Reduced analysis and confirmatory research on co-adaptability theoretical solution to conflicting events in construction engineering projects

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第2期53卷 480-485页

作者： HOU XueLiang1 , LU Mei2 & WANG Kai3.1 School of Business Administration, North china Electric Power university, beijing 102206, china 2 department of Construction Management, tsinghua university, beijing 100084, china 3.College of Management, beijing Jiaotong university, beijing 100084, china School of Business Administration North China Electric Power University Beijing China department of Construction Management Tsinghua University Beijing China College of Management Beijing Jiaotong University Beijing China

The co-adaptability theoretical solution to conflicting events in construction engineering projects has three problems. First, the transformation of constraint conditions of theoretical solution is very difficult in practical engineering applications; second, some coefficients are difficult to be determined; third, there are overfull circular arithmetic operations involved in it. To resolve these problems, a new method to reduce the theoretical solution complications is proposed. By analyzing the operating mechanism of theoretical solution model, redundancies in the theoretical solution can be eliminated, and the ISM mapping with the co-adaptability solution can be set up. Based on this approach, a procedure to solve practical conflicting events in construction projects is established by replacing characteristic variables with mathematic variables. The research results show that the procedure can replace the co-adaptability theoretical solution effectively and solve practical conflicting events in construction projects.

关键词： construction project conflict theoretical solution reduced analysis ISM confirmatory research

Extremal eigenvalues of measure differential equations with fixed variation

在线全文

学校读者我要写书评

暂无评论

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

作者： ZHANG MeiRong 1,2 1 department of Mathematical Sciences,tsinghua university,beijing 100084,{3. 2 Zhou Pei-Yuan Center for Applied Mathematics,tsinghua university,beijing 100084,{3. department of Mathematical Sciences Tsinghua University Beijing China Zhou Pei-Yuan Center for Applied Mathematics Tsinghua University Beijing 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

A　Nonprecedence－based　Query　Schedule　Algorithm　on　Heterogeneous　Multiprocessor　System

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 1995年第3期6卷 63-69页

作者： He Jun bang Dingxing & Zheng Weimin(department of computer Science & technology,{3., beijing, 100084, china) department of computer Science & technology Tsinghua University Beijing 100084 China

There has been a number of algorithms designed to handle intra-query or inter-query scheduling in multiprocessor-based parallel database system. They all have the assumption that the processorsare identical. But in some cases, such as shared nothing environment, this assumption would not be fullyvalid. In this paper we devise and evaluate a scheduling algorithm ELLIST to handle nonprecedence-basedheterogeneous malleable scheduling problem. It uses LLIST-NM as subroutine that handles nonmalleablescheduling without precedence and assuming the processors are identical. Even though the problem we considered is NP-hard in the strong sense, the schedule generated by our algorithm is seen experimentally toachieve results that are close to optimum when there are enough tasks to be scheduled.

关键词： Heterogeneous malleable scheduling Makespan Affinity

Arbitrarily long distance quantum communication using inspection and power insertion

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2009年第1期54卷 158-162页

作者： WANG WanYing1,2,WANG Chuan1,2,ZHANG GuangYu1,3.& LONG GuiLu1,2 1 department of Physics,tsinghua university,beijing 100084,{3. 2 tsinghua National Laboratory for Information Science and technology,tsinghua university,beijing 100084,{3. 3.College of Applied Science,Harbin university of Science and technology,Harbin 150080,{3. department of Physics Tsinghua University Beijing China tsinghua National Laboratory for Information Science and technology Tsinghua University Beijing China College of Applied Science Harbin University of Science and Technology Beijing China

The biggest obstacle for long distance quantum communication is the channel loss and the channel noise on photons. In this paper,a method to solve this problem was analyzed using inspection and power insertion (IPI). It is proved that quantum communication may be established over arbitrarily long distance using this technology. The amount of resources required is a polynomial function of the dis-tance. IPI is proposed as a general technique to prolong quantum secure direct communication where secret messages are transmitted directly over a quantum channel.

关键词：长距离量子通信量子安全通信量子密匙分布噪声

Absence of State Collapse and Revival in a Superconducting Charge Qubit

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2007年第12期48卷 1029-1032页

作者： HUO Wen-Yi~1 and LONG Gui-Lu~(1,2,3.~1 department of Physics amd Key Laboratory for Quantum Information and Measurements,tsinghua university,beijing{3.,china~2 Key Laboratory for Atomic and Molecular Nanosciences,tsinghua university,beijing 100084,china~3.National Laboratory for Information Science and technology,Hsinghua university,beijing 100084,china department of Physics amd Key Laboratory for Quantum Information and Measurements Tsinghua University Beijing 100084 China Key Laboratory for Atomic and Molecular Nanosciences Tsinghua University Beijing 100084 China National Laboratory for Information Science and technology Hsinghua University Beijing 100084 China

The Hamiltonian of a superconducting charge qubit with a configuration of dc SQUID contains an interac-tion between the LC oscillator part and charge *** interaction may leads to quantum state collapse and revivalwhich degrades the charge qubits and leads to serious *** analysis shows that the existing charge qubitparameters do not lead to this phenomenon,which is very good for the superconducting charge

关键词： quantum computer superconducting charge qubit absence and revival

Maximal regularity of second order delay equations in Banach spaces

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2010年第1期53卷 51-62页

作者： BU ShangQuan ? & FANG Yi department of Mathematical Sciences, tsinghua university, beijing 100084, {3. department of Mathematical Sciences, tsinghua university, beijing 100084, {3. department of Mathematical Sciences Tsinghua University Beijing China

We give necessary and sufficient conditions of Lp-maximal regularity(resp.B sp ,q-maximal regularity or F sp ,q-maximal regularity) for the second order delay equations:u″(t)=Au(t) + Gu't + F u t + f(t), t ∈ [0, 2π] with periodic boundary conditions u(0)=u(2π), u′(0)=u′(2π), where A is a closed operator in a Banach space X,F and G are delay operators on Lp([-2π, 0];X)(*** ,q([2π, 0];X) or Fsp,q([-2π, 0;X])).

关键词： maximal regularity second order delay equations Lebesgue-Bochner spaces Besov spaces Triebel-Lizorkin spaces