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Irregular wavelet frames on L^2 (R^n)

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science china Mathematics 2005年第2期48卷 277-287页

作者： YANG Deyun & ZHOU Xingwei department of information & technology, Nankai university, Tianjin 300071, china department of Mathematics, Nankai university, Tianjin 300071, china department of computer science, Taishan college, Taian 271000, china 1. department of information & technology Nankai University 300071 Tianjin China 2. department of Mathematics Nankai University 300071 Tianjin China 3. department of computer science Taishan College 271000 Taian China

In this paper, we present the conditions on dilation parameter {sj}j that ensure a discrete irregular wavelet system to be a frame on L2(Rn), and for the wavelet frame we consider the perturbations of translation para... 详细信息

关键词： wavelet transform, frame, wavelet frame, irregular dilation.

Dense coding scheme using superpositions of Bell-states and its NMR implementation

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science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 57-67页

作者： ZHANG Jingfu, XIE Jingyi, DENG Zhiwei & LU Zhiheng Key Laboratory for Quantum information and Measurements, department of Physics, tsinghua university, beijing 100084, china Center for Quantum information, tsinghua university, beijing 100084, china department of Materials science and Engineering, beijing Normal university, beijing 100875, china Testing and Analytical Center, beijing Normal university, beijing 100875, china department of Physics, beijing Normal university, beijing 100875, china 1. Key Laboratory for Quantum information and Measurements Department of Physics Tsinghua University 100084 Beijing China 2. Center for Quantum information Tsinghua University 100084 Beijing China 3. department of Materials science and Engineering Beijing Normal University 100875 Beijing China 4. Testing and Analytical Center Beijing Normal University 100875 Beijing China 5. department of Physics Beijing Normal University 100875 Beijing China

Dense coding using superpositions of Bell-states is proposed. The generalized Grover's algorithm is used to prepare the initial entangled states, and the reverse process of the quantum algorithm is used to determine the entangled state in the decoding measurement. Compared with the previous schemes, the superpositions of two Bell-states are exploited. Our scheme is demonstrated using a nuclear magnetic resonance (NMR)quantum computer. The corresponding manipulations are obtained. Experimental results show a good agreement between theory and experiment. We also generalize the scheme to transmit eight messages by introducing an additional two-state system.

关键词： dense coding, superpositions of Bell-states, generalized Grover's algorithm, nuclear magnetic res-onance, quantum computer.

Two mode photon bunching effect as witness of quantum criticality in circuit QED

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science china(Physics,Mechanics & Astronomy) 2009年第12期52卷 1898-1905页

作者： AI Qing1,WANG YingDan2,LONG GuiLu1,3 & SUN ChangPu4 1 department of Physics,tsinghua university,beijing 100084,china 2 department of Physics,university of Basel,Klingelbergstrasse 82,4056 Basel,Switzerland 3 tsinghua National Laboratory for information science and technology,beijing 100084,china 4 Institute of Theoretical Physics,Chinese Academy of sciences,beijing 100080,china 1. department of Physics Tsinghua University Beijing 100084 China 2. department of Physics University of Basel Klingelbergstrasse 82 4056 Basel Switzerland 3. tsinghua National Laboratory for information science and technology Beijing 100084 China 4. Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100080 China

We suggest a scheme to probe critical phenomena at a quantum phase transition (QPT) using the quantum correlation of two photonic modes simultaneously coupled to a critical system. As an experimentally accessible physical implementation,a circuit QED system is formed by a capacitively coupled Josephson junction qubit array interacting with one superconducting transmission line resonator (TLR). It realizes an Ising chain in the transverse field (ICTF) which interacts with the two magnetic modes propagating in the TLR. We demonstrate that in the vicinity of criticality the originally independent fields tend to display photon bunching effects due to their interaction with the ICTF. Thus,the occurrence of the QPT is reflected by the quantum characteristics of the photonic fields.

关键词： quantum phase transition photon bunching circuit QED

Competent predicate abstraction in model checking

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science china(information sciences) 2011年第2期54卷 258-267页

作者： LI Li1,2,3, SONG XiaoYu4, GU Ming2,3 & LUO XiangYu2,3 1department of computer science & technology, tsinghua university, beijing 100084, china 2Key Laboratory for information System Security, Ministry of Education of china, beijing 100084, china 3School of Software, tsinghua university, beijing 100084, china 4department of ECE, Portland State university, Portland, Oregon 97207, USA 1. department of computer science & technology Tsinghua University Beijing 100084 China2. Key Laboratory for Information System Security Ministry of Education of China Beijing 100084 China3. School of Software Tsinghua University Beijing 100084 China4. Department of ECE Portland State University Portland Oregon 97207 USA

The paper presents a new approach to computing the abstract state and a maximum weight heuristic method for finding the shortest counter-example in verification of imperative programs. The strategy is incorporated in a verification system based on the counterexample-guided abstraction refinement method. The proposed method slashes both the size of the abstract state space and the number of invokes of a decision procedure. A number of benchmarks are employed to evaluate the effectiveness of the approach.

关键词： program model checking predicate abstraction weight heuristic

MEAM Potential with Angular Dependence for TiAl

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Rare Metals 2001年第1期20卷 13-17页

作者： Xiaodong Ni, Xitao Wang, Guoliang Chen (Physics department, university of science and technology beijing, beijing 100083, china State Key Laboratory for Advanced Metals and Materials, university of science and technology beijing, beijing 100083, china) Univ Sci & Technol beijing Dept Phys Beijing 100083 Peoples R China Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China

The modified embedded atom method (MEAM) is an empirical extension of the embedded atom method (EAM) that includes angular forces. By fitted to the lattice constants, the cohesive energy, the APE (anti-phase boundary) energy, and the vacancy formation energy of TiAl, an accurate MEAM potential is obtained for the TiAl system with L10 structure. The calculation results of the properties of TiAl are in good agreement with experiments and the results of first principle (F.P.) calculations.

关键词： embedded atom method TiAl alloy angular dependence potential intermetallics

The influence of thermal radiation on MHD station-point flow past a stretching sheet with heat generation

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Acta Mechanica Sinica 2011年第4期27卷 502-509页

作者： Jing Zhu.Lian-Cun Zheng.Xin-Xin Zhang department of Mathematics and Mechanics,university of science and technology beijing,100083 beijing,china Thermal Engineering department,university of science and technology beijing,100083 beijing,china Zheng department of Mathematics and Mechanics University of Science and Technology Beijing Beijing China Thermal Engineering department University of Science and Technology Beijing Beijing China

This letter is concerned with the plane and axisymmetric stagnation-point flows and heat transfer of an electrically-conducting fluid past a stretching sheet in the presence of the thermal radiation and heat generation or absorption. The analytical solutions for the velocity distribution and dimensionless temperature profiles are obtained for the various values of the ratio of free stream velocity and stretching velocity, heat source parameter, Prandtl number, thermal radiation parameter, the suction and injection velocity parameter and magnetic parameter and dimensionality index in the series form with the help of homotopy analysis method （HAM）. Convergence of the series is explicitly dis- cussed. In addition, shear stress and heat flux at the surface are calculated.

关键词： Thermal radiation MHD Laminar boundarylayers - Homotopy analysis method

Thermodynamic Assessment of Reactions between Yttrium and Tramp Elements in Petroleum Pipe Steel

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International Journal of Minerals,Metallurgy and Materials 1998年第4期12卷 219-222页

作者： Aixue Sha Luren Dong Shangyi Li( Metallurgy School, university of science and technology beijing, beijing 1 00083, china)(science and technology department, Metallurgical Industry Bureau of china, beijing 100711, china) Metallurgy School University of Science and Technology Beijing Beijing 100083 China science and technology department Metallurgical Industry Bureau of China Beijing 100711 China

In the thermodynamic evaluation Y was selected as a typical heavy rare earth metal for reducing the detrmental effects of tramp elements in the petroleum pipe steel. The possibilities of reactions between Y and trampelements such as Sn, Sb, As, etc. after deoxidation and desulphurization were estimated by calculating the Gibbsfree energies of formation. The equilibrium content of Y for eliminating the detrimental effects of tramp elements inthe steel was recommended from the results of thermodynamic calculation.

关键词： rare earth metals tramp elements thermodynamic calculation

Structure and kinematic analysis of a novel 2-DOF translational parallel robot

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Progress in Natural science:Materials International 2007年第10期17卷 1213-1219页

作者： Chen Tao1, Wu Chao2 and Liu Xinjun2(1. School of Application science and technology, Harbin university of science and technology, Harbin 150080, china 2. department of Precision Instruments, tsinghua university, beijing 100084, china) School of Application science and technology Harbin University of Science and Technology Harbin 150080 China department of Precision Instruments Tsinghua University Beijing 100084 China

This paper addresses the analysis of a novel parallel robot with 2 translational degrees of freedom (DOFs). The robot can position a rigid body in a plane with constant orientation. The kinematic structure of the robot is first described in detail. Some kinematic problems, such as the inverse and forward kinematics, velocity, and singularity are then analyzed. The working and assembly modes are discussed. Since it is the most important index to design a robot, the workspace of the robot is studied systematically in this paper. Based on the analysis of reachable workspace and singularity, a kind of workspace concept characterizing the region that the end-effector of the robot can reach in practice is defined. The results of this paper will be very useful for the design and application of the robot.

关键词： parallel robot degree of freedom kinematics workspace.

EFFECT OF NITROGEN ON GRAPHITE MORPHOLOGY IN GRAY CAST IRON

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Acta Metallurgica Sinica(English Letters) 1993年第8期6卷 151-155页

作者： ZHAI Qijie HU Hanqi university of science and technology beijing,beijing,china Faculty of Foundry,university of science and technology beijing,beijing 100083,china beijing Univ of science and Technology Beijing China

The distribution of N and morphology of graphite in gray cast iron containing N were studicd by adopting the man-made specimens of Fe-C-Si-Mn alloys with some N added. The N adsorbed along the interfaces between graphite and matrix together with solid- solutioned in graphite is believed to be the principal cause of morpholongical variation of graphite.

关键词： gray cast iron graphite morphology N