检索结果-南通市图书馆

science china(Technological sciences) 2009年第7期52卷 1919-1922页

作者： li qiang1,2 1 school of physics science and technology, xinjiang university, urumqi 830046, china 2 Department of physics, The Chinese university of HongKong, Shatin N.T., HongKong, china school of physics science and technology Xinjiang University Urumqi China Department of physics The Chinese University of HongKong Shatin N.T. HongKong China

Nanostructured Fe40Ni40P14B6 alloy ingots of 3―5 mm in diameter could be synthesized by a metastable liquid state spinodal decomposition method. For undercooling T> 260 K, the microstructure of the undercooled specimen had exhibited liquid state spinodal decomposition in the undercooled liquid state. The microstructure could be described as two intertwining networks with small grains dispersed in them. For undercooling T>290 K, the overall microstructure of the specimen changed into a granular morphology. The average grain sizes of the small and large grains are 30 nm and 80 nm, respectively. These prepared samples are soft magnets with saturation magnetization Bs 0.744 T.

关键词： nanomaterials magnetic materials solidification bulk nanostructured alloy Fe40Ni40P14B6 metastable liquid spinodal decomposition

C^MC^N D-computable state

在线全文

学校读者我要写书评

暂无评论

science china(physics,Mechanics & Astronomy) 2008年第9期51卷 1300-1307页

作者： liU DongDong1,2 & DI YaoMin1 1 school of physics & Electronic Engineering,Xuzhou Normal university,Xuzhou 221116,china 2 school of Mathematics & physics science,Xuzhou Institute of technology,Xuzhou 221008,china school of physics & Electronic Engineering Xuzhou Normal University Xuzhou China school of Mathematics & physics science Xuzhou Institute of Technology Xuzhou China

The notions of D-computable state and D-concurrence are generalized to the CMCN system. A class of D-computable state on CMCN is given and the calculating method of the lower bound of D-concurrence is provided. Th... 详细信息

关键词： quantum entanglement entanglement of formation concurrence D-computable state

A new approximating method for Holstein model

在线全文

学校读者我要写书评

暂无评论

science china(physics,Mechanics & Astronomy) 2010年第1期53卷 44-48页

作者： REN XueZao 1 , liAO Xu 1 , li Lei 1 & WANG Kelin 2 1 school of science, Southwest university of science and technology, Mian Yang 621010, china 2 Department of Modern physics, university of science and technology of china, Hefei 230026, china school of science Southwest University of Science and Technology Mian Yang China Department of Modern physics University of Science and Technology of China Hefei China

A new approach-the method of coherent state orthogonal expansion is developed for one-dimensional Holstein model. In zeroth order approximation, the formula of ground state energy is deduced analytically and the solutions in strong- and weak-coupling limits are obtained correctly. When the trial wave-function of ground state is expanded to the second order, the obtained ground state energy agrees quite well with that calculated by numerical method in all coupling regimes. The present approach can be easily generalized to the situations of higher dimensions and more electrons.

关键词： coherent-state orthogonal expansion polaron simulated annealing method

Search for B_c (ns) via the B_c (ns) → B_c (ms) π^+ π^- transition at LHCb and Z^0 factory

在线全文

学校读者我要写书评

暂无评论

science china(physics,Mechanics & Astronomy) 2010年第11期53卷 2019-2024页

作者： KE HongWei 1 & li XueQian 2 1 school of science,Tianjin university,Tianjin 300072,china 2 school of physics,Nankai university,Tianjin 300071,china school of science Tianjin University Tianjin China school of physics Nankai University Tianjin China

It is interesting to study the characteristics of the whole family of B c which contains two different heavy *** and the proposed Z 0 factory provide an opportunity because a large database of the B c family will be achieved.B c and its excited states can be identified via their decay *** suggested by experimentalists,B-c (ns) → B c +γ is not easy to be clearly measured,instead,the trajectories of π + and π- occurring in the decay of B c (ns) → B c (ms) + π + π( n > m ) can be unambiguously identified,thus the measurement seems easier and more reliable;therefore this mode is more favorable at the early running stage of LHCb and the proposed Z 0 *** this work,we calculate the rate of B c (ns) → B c (ms) + π + π-in terms of the QCD multipole-expansion and the numerical results indicate that the experimental measurements with the luminosity of LHC and Z 0 factory are feasible.

关键词： meson hadronic decay QCD multipole-expansion

Finite-Time Stabilization for Constrained Discrete-time Systems by Using Model Predictive Control

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1656-1666页

作者： Bing Zhu Xiaozhuoer Yuan li Dai Zhiwen qiang IEEE the Seventh Research Division Beihang UniversityBeijing 100191China the school of Automation Beijing Institute of TechnologyBeijing 100081China

In this paper, a model predictive control(MPC)framework is proposed for finite-time stabilization of linear and nonlinear discrete-time systems subject to state and control constraints. The proposed MPC framework guarantees the finite-time convergence property by assigning the control horizon equal to the dimension of the overall system, and only penalizing the terminal cost in the optimization, where the stage costs are not penalized explicitly. A terminal inequality constraint is added to guarantee the feasibility and stability of the closed-loop *** feasibility can be improved via augmentation. The finite-time convergence of the proposed MPC is proved theoretically,and is supported by simulation examples.

关键词： Constraints deadbeat control finite-time stabilization model predictive control(MPC)

Improving Fatigue Properties of 316L Stainless Steel Welded Joints by Surface Spinning Strengthening

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 840-854页

作者： Dongqiqiong Wang qiang Wang Xiaowu li Zhefeng Zhang Department of Materials physics and Chemistry School of Materials Science and Engineeringand Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education)Northeastern UniversityShenyang 110819China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China College of light Industry Liaoning UniversityShenyang 110036China

The surface spinning strengthening(3S)mechanism and fatigue life extension mechanism of 316L stainless steel welded joint were systematically elucidated by microstructural analyses and mechanical *** indicate that surface gradient hardening layer of approximately 1 mm is formed in the base material through grain fragmentation and deformation twin strengthening,as well as in the welding zone composed of deformedδ-phases and *** fatigue strength of welded joint after 3S significantly rises by 32%(from 190 to 250 MPa),which is attributed to the effective elimination of surface geometric defects,discrete refinement ofδ-Fe phases and the appropriate improvement in the surface strength,collectively mitigating strain localization and surface fatigue damage within the gradient strengthening *** redistributed fineδ-Fe phases benefited by strong stress transfer of 3S reduce the risk of surface weak phase cracking,causing the fatigue fracture to transition from microstructure defects to crystal defects dominated by slip,further suppressing the initiation and early propagation of fatigue cracks.

关键词： 316L stainless steel Welded joint Surface spinning strengthening Nanotwin Fatigue life

Bell violation for the thermal states of an XXZ spin chain with Dzialoshiski-Moriya interaction

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

science china(physics,Mechanics & Astronomy) 2010年第11期53卷 2074-2079页

作者： MA XiaoSan 1 & WANG AnMin 2 1 school of Electric Engineering and Information,Anhui university of technology,Maanshan 243002,china 2 Department of Modern physics,university of science and technology of china,Hefei 230026,china school of Electric Engineering and Information Anhui University of Technology Maanshan China Department of Modern physics University of Science and Technology of China Hefei China

The effect of Dzialoshiski-Moriya (DM) interaction on the violation of Bell inequality for thermal states of interacting qubits via a two-qubit XXZ spin chain is *** results imply that the DM interaction and anisotropy taking a large positive value can enhance the Bell violation and improve the threshold temperatures of *** the comparison between the Bell violation and thermal entanglement,we find that the threshold temperatures of thermal entanglement are higher than those of the Bell *** implies that some states are entangled but the Bell inequality is not violated.

关键词： Bell violation threshold temperatures DM interaction

Numerical simulations and experimental investigations on transverse effects of two-wave mixing in a photovoltaic photorefractive crystal

在线全文

学校读者我要写书评

暂无评论

science china(physics,Mechanics & Astronomy) 2010年第5期53卷 856-863页

作者： CAI Xin1,2,liU JinSong1 & WANG Shenglie1 1 Wuhan National Laboratory for Optoelectronics,school of Optoelectronic science and Engineering,Huazhong university of science and technology,Wuhan 430074,china 2 school of science,Wuhan university of technology,Wuhan 430070,china Wuhan National Laboratory for Optoelectronics School of Optoelectronic Science and Engineering Huazhong University of Science and Technology Wuhan China school of science Wuhan University of Technology Wuhan China

The transverse effects of two Gauss waves mixing in a photovoltaic photorefractive crystal,i.e.,the dynamical evolutions of signal beam with different parameters,are traced numerically and *** the one-dimensional numerical simulations and two-dimensional experimental investigations show that the self-focusing effect of signal beam becomes more obvious as the intensity of pump beam and the angle between the signal and pump beams *** accordance with these results,the state of two Gaussian waves mixing is controllable.

关键词： numerical simulation experimental investigation two-wave mixing transverse effects Gaussian distribution

A computational investigation of boron-doped chromium and chromium clusters by density functional theory

在线全文

学校读者我要写书评

暂无评论

science china(physics,Mechanics & Astronomy) 2010年第5期53卷 812-817页

作者： GE GuiXian1,JING Qun1 & LUO YouHua2,3 1 Key Laboratory of Ecophysics and Department of physics,Normal College,Shihezi university,xinjiang 832003,china 2 school of science,East china university of science and technology,Shanghai 200237,china 3 Institute of Theoretical physics,school of physics and Information Optoelectronics,Henan university,Kaifeng 475004,china Key Laboratory of Ecophysics and Department of physics Normal College Shihezi University Xinjiang China school of science East China University of Science and Technology Shanghai China Institute of Theoretical physics School of Physics and Information Optoelectronics Henan University Kaifeng China

The geometries,stabilities and electronic properties of Crn and CrnB(n=2-9) clusters have been systematically investigated by density functional *** results suggest that the lowest energy structures for CrnB clusters can be obtained by substituting one Cr atom in Crn+1 clusters with B *** geometries of CrnB clusters are similar to that of Crn+1 clusters except for local structural *** second-order difference and fragmentation energy show Cr4,Cr6,Cr8,Cr3B,Cr5B and Cr8B cluster are the most stable among these studied *** impurity B increases the stabilities of chromium *** B is doped on the Crn clusters,cluster geometry does dominate positive role in enhancing their *** doped B atom does not change the coupling way of the Cr site in Crn clusters,but breaks the symmetry and the Cr atoms are no longer *** doped B atom increases the total magnetic moments of Crn in most cases.

关键词： Crn and CrnB clusters geometries electronic properties

Ferroelectric properties of Bi_(3.4)Ho_(0.6)Ti_3O_(12) thin films prepared by sol-gel method

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2008年第9期51卷 1439-1444页

作者： FU ChengJu1, HUANG ZhiXiong1, li Jie2 & GUO DongYun3 1 school of Materials science and technology, Wuhan university of technology, Wuhan 430070, china 2 school of Mechanical Engineering, Chongqing university of science and technology, Chongqing 400050, china 3 Department of physics, Wuhan university, Wuhan 430072, china school of Materials science and technology Wuhan University of Technology Wuhan China school of Mechanical Engineering Chongqing University of Science and Technology Chongqing China Department of physics Wuhan University Wuhan China

We have prepared the Ho-substituted bismuth titanate (Bi3.4Ho0.6Ti3O12, BHT) thin films on Pt/Ti/SiO2/Si substrates using sol-gel method. The crystal structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The BHT film shows a single phase of Bi-layered Aurivillius structure and dense microstructure. The 2Pr and 2Ec of the 600-nm-thick BHT film were 38.4 μC/cm2 and 376.1 kV/cm, respectively at applied electric field 500 kV/cm. The dielectric constant and dielectric loss are about 310 and 0.015 at a frequency of 1 MHz, respectively. The Pr value decreased to 93% of its pre-fatigue values after 4.46×109 switching cycles at 1 MHz frenquency, and the BHT film shows good in-sulating behavior according to the test of leakage current.

关键词： Bi3.4Ho0.6Ti3O12 thin film sol-gel method ferroelectric property fatigue dielectric constant