检索结果-南通市图书馆

Review on the study of entanglement in quantum computation speedup

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2007年第16期52卷 2161-2166页

作者： DING ShengChao1,3.& JIN Zhi1,2.1 institute of computing {2.,Chinese academy of sciences,Beijing 100080,china 2.academy of Mathematics and Systems Science,Chinese academy of sciences,Beijing 100080,china 3.Graduate University of Chinese academy of sciences,Beijing 100080,china institute of computing {2. Chinese Academy of Sciences Beijing China Graduate University of Chinese academy of sciences Beijing China academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China

The role the quantum entanglement plays in quantum computation speedup has been widely disputed. Some believe that quantum computation's speedup over classical computation is impossible if entan-glement is absent,while others claim that the presence of entanglement is not a necessary condition for some quantum algorithms. This paper discusses this problem systematically. Simulating quantum computation with classical resources is analyzed and entanglement in known algorithms is reviewed. It is concluded that the presence of entanglement is a necessary but not sufficient condition in the pure state or pseudo-pure state quantum computation speedup. The case with the mixed state remains open. Further work on quantum computation will benefit from the presented results.

关键词：量子论量子纠缠量子计算加速模拟

Formal Verification under Unknown Constraints

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural sciences 2005年第1期10卷 43-46页

作者： LI Guang-hui 1,2.3., LI Xiao-wei 2.3.. School of Information Engineering, Zhejiang Forestry College, Hangzhou 3.13.0, Zhejiang, china {3., Chinese {2. of sciences, Beijing 100080, china 3. Graduate School of the Chinese {2. of sciences, Beijing 10003., china School of Information Engineering Zhejiang Forestry College Hangzhou Zhejiang China institute of computing {2. Chinese Academy of Sciences Beijing China Graduate School of the Chinese academy of sciences Beijing China

We present a formal method of verifying designs with unknown constraints (e.g., black boxes) using Boolean satisfiability (SAT). This method is based on a new encoding scheme of unknown constraints, and solves the corresponding conjunctive normal form (CNF) ***,this method can avoid the potential memory explosion, which the binary decision diagram (BDD) based techniques maybe suffer from, thus it has the capacity of verifying large designs. Experimental results demonstrate the efficiency and feasibility of the proposed method.

关键词： formal verification unknown constraints black box Boolean satisfiability Boolean comparison

A new DNA algorithm to solve graph coloring problem

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第6期17卷 733-738页

作者： Jiang Xingpeng1, Li Yin2. Meng Ya3.and Meng Dazhi2.1. National Laboratory of Pattern Recognition,institute of Automation, Chinese {3. of {2., Beijing 100080, china 2. College of Applied {2., Beijing University of technology, Beijing 10002., china 3. School of Science, Beijing institute of technology, Beijing 100081, china) National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences Beijing 100080 China College of Applied sciences Beijing University of Technology Beijing 100022 China School of Science Beijing Institute of Technology Beijing 100081 China

Using a small quantity of DNA molecules and little experimental time to solve complex problems successfully is a goal of DNA computing. Some NP-hard problems have been solved by DNA computing with lower time complexity than conventional computing. However, this advantage often brings higher space complexity and needs a large number of DNA encoding molecules. One example is graph coloring problem. Current DNA algorithms need exponentially increasing DNA encoding strands with the growing of problem size. Here we propose a new DNA algorithm of graph coloring problem based on the proof of four-color theorem. This algorithm has good properties of needing a relatively small number of operations in polynomial time and needing a small number of DNA encoding molecules (we need only 6R DNA encoding molecules if the number of regions in a graph is R).

关键词： DNA computing NP-hard problem graph coloring problem.

Simulation study of phase retrieval for hard X-ray in-line phase contrast imaging

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) 2005年第4期48卷 450-458页

作者： YU Bin1,2. PENG Xiang1,2. TIAN Jindong1, NIU Hanben1, DIAO Luhong3.& LI Hua3.1. Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, {4. of Optoelec- tronics, Shenzhen University, Shenzhen 518060,{3. 2. State Key Laboratory of Precision Measuring {2. and Instruments, Tianjin University, Tianjin 3.0072.china 3. Key Laboratory of Intelligent Information Processing, {4. of computing {2., Chinese academy of sciences, Beijing {13.,china Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education Institute of Optoelectronics Shenzhen University Shenzhen China State Key Laboratory of Precision Measuring technology and Instruments Tianjin University Tianjin China Key Laboratory of Intelligent Information Processing Institute of Computing Technology Chinese Academy of Sciences Beijing China

Two algorithms for the phase retrieval of hard X-ray in-line phase contrast imaging are presented. One is referred to as Iterative Angular Spectrum Algorithm (IASA) and the other is a hybrid algorithm that combines IASA with TIE (transport of intensity equation). The calculations of the algorithms are based on free space propagation of the angular spectrum. The new approaches are demonstrated with numerical simulations. Comparisons with other phase retrieval algorithms are also performed. It is shown that the phase retrieval method combining the IASA and TIE is a promising technique for the application of hard X-ray phase contrast imaging.

关键词： X-ray optics, phase contrast imaging, phase retrieval, angular spectrum, hard X-ray.

Design of secure operating systems with high security levels

在线全文

学校读者我要写书评

暂无评论

Science in china(Series F) 2007年第3期50卷 399-418页

作者： QING SiHan1,2.& SHEN ChangXiang3.1 institute of Software, Chinese academy of {2., Beijing 100080, china 2.School of Software and Microelectronics, Peking University, Beijing 102.00, china 3.institute of computing technology, Navy, Beijing 10084., china institute of Software Chinese Academy of Sciences Beijing China School of Software and Microelectronics Peking University Beijing China institute of computing {2. Navy Beijing China

Numerous Internet security incidents have shown that support from secure operating systems is paramount to fighting threats posed by modern computing environments. Based on the requirements of the relevant national and international standards and criteria, in combination with our experience in the design and development of the ANSHENG v4.0 secure operating system with high security level （hereafter simply referred to as ANSHENG OS）, this paper addresses the following key issues in the design of secure operating systems with high security levels： security architecture, security policy models, and covert channel analysis. The design principles of security architecture and three basic security models： confidentiality, integrity, and privilege control models are discussed, respectively. Three novel security models and new security architecture are proposed. The prominent features of these proposals, as well as their applications to the ANSHENG OS, are elaborated. Cover channel analysis （CCA） is a well-known hard problem in the design of secure operating systems with high security levels since to date it lacks a sound theoretical basis and systematic analysis approach. In order to resolve the fundamental difficulties of CCA, we have set up a sound theoretical basis for completeness of covert channel identification and have proposed a unified framework for covert channel identification and an efficient backward tracking search method. The successful application of our new proposals to the ANSHENG OS has shown that it can help ease and speedup the entire CCA process.

关键词： secure operating systems with high security levels architecture security model covert channel analysis

A mixed finite element method for the unilateral contact problem in elasticity

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2006年第4期49卷 513-524页

作者： HUA Dongying & WANG Lieheng The First Fundamental Department, Beijing Information technology institute, Beijing 100101,{2. institute of Computational Mathematics and Scientific/Engineering {4., academy of Mathematics and System sciences, Chinese academy of sciences, Beijing 100080,{2. The First Fundamental Department Beijing Information Technology Institute Beijing China institute of Computational Mathematics and Scientific/Engineering computing Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China

In this paper, we provide a new mixed finite element approximation of the variational inequality resulting from the unilateral contact problem in elasticity. We use the continuous piecewise P2.P1 finite element to approximate the displacement field and the normal stress component on the contact region. Optimal convergence rates are obtained under the reasonable regularity hypotheses. Numerical example verifies our results.

关键词： unilateral contact problem, mixed finite element method.

Target-Fault-Oriented Test Generation of Sequential CircuitsUsing Genetic Algorithm

在线全文

学校读者我要写书评

暂无评论

湖南大学学报（自然科学版） 2000年第S2期27卷 95-103页

作者： Li Shen institute of computing {2., Chinese {3. of {4., Beijing, china, 100080

This paper deals with the target-fault-oriented test generation of sequential circuits using genetic algorithms. We adopted the concept of multiple phases and proposed four sub-procedures which consist of activation, propagation and justification phases. The paper focuses on the design of genetic operators and construction of fitness functions which are based on the structure information of circuits. Using ISCAS89 benchmarks, the experiment results of GA were given.

关键词： target-fault-oriented test generation genetic algorithm test generati(

EMMA:An Efficient Massive Mapping Algorithm Using Improved Approximate Mapping Filtering

在线全文

学校读者我要写书评

暂无评论

Acta Biochimica et Biophysica Sinica 2006年第12期38卷 857-864页

作者： Xin ZHANG~1 Zhi-Wei CAO~2.Zhi-Xin LIN~3.Qing-Kang WANG~1* Yi-Xue LI~4. 1 institute of Micro/Nano Science and technology,Shanghai Jiaotong University,Shanghai 2.003.,{2. 2.Shanghai Center for Bioinformation technology,Shanghai 2.02.5,{2. 3.College of Life Science and technology,Shanghai Jiaotong University,Shanghai 2.003.,{2. 4.Bioinformation Center of Shanghai institutes for Biological sciences,Chinese academy of sciences,Shanghai 2.003.,{2. institute of Micro/Nano Science and technology Shanghai Jiaotong UniversityShanghai 200030 China Shanghai Center for Bioinformation technology Shanghai 200235 China College of Life Science and technology Shanghai Jiaotong UniversityShanghai 200030 China Bioinformation Center of Shanghai institutes for Biological sciences Chinese Academy of SciencesShanghai 200031 China

Efficient massive mapping algorithm (EMMA),an algorithm on efficiently mapping massivecDNAs onto genomic sequences,has recently been *** process of mapping massive cDNAsonto genomic sequences has been improved using more approximate mapping filtering based on an enhancedsuffix array coupled with a pruned fast hash table,algorithms of block alignment extensions,and *** compared with the classical BLAT software in this field,the computing of EMMA ranges fromtwo to forty-one times faster under similar prediction precisions.

关键词： cDNA mapping maximal exact match enhanced suffix array pruned fast hash table extension algorithm

The Real-gas Effect in Single-bubble Sonoluminescence

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Communications in Nonlinear Science and Numerical Simulation 1999年第1期4卷 29-34页

作者： Li YUAN (LSEC, institute of Computational Mathematics and Scientific-Engineering computing, Chinese {2. of {3., Beijing {4., china) Wei WEI (Center for Nonlinear {3., University of Science and technology of china, Hefei 2.002.,china) LSEC Inst. Compl. Math./Sci.-Eng. Comp. Chinese Academy of Sciences Beijing 100080 China Center for Nonlinear sciences Univ. of Sci. and Technol. of China Hefei 230026 China Department of Physics Chinese University of Hong Kong Shatin Hong Kong

The full set of hydrodynamic equations governing the oscillation of a bubble is solved numerically by using a modified equation of state with ionization. We show that the hydro-thermal process in the form of compression waves and low-level ionization are dominant inside a sonoluminescing bubble for a wide range of driving pressure. The resulting thermal bremsstrahlung radiation has pulse heights and widths that agree with experimental data for cases considered in this paper.

关键词： single-bubble sonoluminescence ionization bremsstrahlung