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Wigner function for squeezed negative binomial state and evolution of density operator for amplitude decay

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Chinese Physics B 2019年第9期28卷 93-99页

作者： Heng-Yun Lv Ji-suo Wang xiao-Yan Zhang Meng-Yan Wu Bao-Long liang Xiang-Guo Meng Shandong Provincial Key Laboratory of Optical Communication Science and Technology School of Physical Science and Information EngineeringLiaocheng UniversityLiaocheng 252059China Shandong Provincial Key Laboratory of Laser Polarization and Information Technology College of Physics and EngineeringQufu Normal UniversityQufu 273165China

Using the thermal-entangled state representation and the operator-ordering method, we investigate Wigner function(WF) for the squeezed negative binomial state(SNBS) and the analytical evolution law of density operator in the amplitude decay *** results show that the analytical WF is related to the square of the module of single-variable Hermite polynomials, which leads to a new two-variable special function and its generating function, and the parameters s and γplay opposite roles in the WF ***, after undergoing this channel, the initial pure SNBS evolves into a new mixed state related to two operator Hermite polynomials within normal ordering, and fully loses its nonclassicality and decays to vacuum at long decay time.

关键词： squeezed negative binomial state operator ordering Wigner function density-operator evolution amplitude decay

Double resonance in star networks of bistable units with disordered signals

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Communications in Theoretical Physics 2020年第5期72卷 98-104页

作者： Yang Ge xiao-Ming liang School of Physics and Electronic Engineering Jiangsu Normal UniversityXuzhou 221116China

It has been found that a hub node is better able to amplify weak external signals than leaf nodes in star *** hub-enhanced amplification is only attained by a single hub node and is limited to weak coupling *** show here that random initial phases in external weak signals do not affect the hub-enhanced amplification at weak coupling ***,they can improve the responses of all the leaf nodes to external signals at large coupling strength,resulting in a double resonance-like signal *** use a reduced model to analyze the influence of the star structure and random initial phases on the emergence of double resonance.

关键词： signal amplification random initial phases star networks bistable units

Partitioning behavior and lattice misfit of γ/γ’phases in Ni-based superalloys with different Mo additions

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Rare Metals 2021年第4期40卷 920-927页

作者： Zhe Ma Yan-Ling Pei liang Luo Lu Qin Shu-suo Li Sheng-Kai Gong School of Materials Science and Engineering Beihang UniversityBeijing 100191China

A low-density single crystal(LDS) alloy with the composition of high Mo content was *** extra 1.5 wt% Mo was added in the Alloy A with the composition of Ni-6.5 Al-8.0 Mo-2.4 Cr-6.2 Ta-4.9 Co-1.5 Re-(0.01-0.05) Y(wt%) to study the influence of Mo on the lattice parameter and partitioning *** electron microscope(SEM) with energy-dispersive spectrometer(EDS),transmission electron microscopy(TEM)and high-temperature X-ray diffraction(HT-XRD) were used to observe the microstructure,analyze the elemental content and measure the lattice parameter of the *** natural lattice misfit was calculated by lattice constants which were measured by HT-XRD at the temperature from 25 to 1150℃,and the results showed that the lattice misfit would be more and more negative with temperature *** was found that 1.5 wt% addition of Mo will increase the absolute value of the lattice misfit of γ/γ’phases and the volume fraction of γ’,and at the same time,influence the elemental distribution in γ and γ’ phases,especially Re and *** has a higher partitioning ratio(k) after the addition of Mo.

关键词： Ni-based superalloys Mo Lattice misfit High-temperature X-ray diffraction(HT-XRD) Partitioning behavior

Evolution of a two-mode squeezed vacuum for amplitude decay via continuous-variable entangled state approach

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Frontiers of physics 2018年第5期13卷 231-239页

作者： Xiang-Guo Meng Ji-suo Wang Bao-Long liang Cheng-Xuan Han School of Physical Science and Information Engineerig Liaocheng University Liaocheng 252059 China Shandong Provincial Key Laboratory of Optical Communication Science and Technology Liaocheng University Liaocheng 252059 China Shandong Provincial Key Laboratory of Laser Polarization and Information Technology College of Physics and Engineering Qufu Normal University Qufu 273165 China

Extending the recent work completed by Fan et al. [Front. Phys. 9（1）, 74 （2014）] to a two-mode case, we investigate how a two-mode squeezed vacuum evolves when it undergoes a two-mode amplitude dissipative channel, with the same decay rate ~, using the continuous-variable entangled state approach. Our analytical results show that the initial pure-squeezed vacuum state evolves into a definite mixed state with entanglement and squeezing, decaying over time as a result of amplitude decay. We also investigate the time evolutions of the photon number distribution, the Wigner function, and the optical tomogram in this channel. Our results indicate that the evolved photon number distribution is related to Jacobi polynomials, the Wigner function has a standard Gaussian distribution （corresponding to the vacuum） at long periods, losing its nonclassicality due to amplitude decay, and a larger squeezing leads to a longer decay time.

关键词： two-mode squeezed vacuum amplitude decay continuous-variable entangled staterepresentation photon number distribution Wigner function optical tomogram

LINEAR FINITE ELEMENT APPROXIMATIONS FOR THE TIMOSHENKO BEAM AND THE SHALLOW ARCH PROBLEMS

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Journal of Computational Mathematics 2002年第1期20卷 15-22页

作者： xiao-liang Cheng Wei-min Xue Department of Mathematics Zhejiang UniversityXixi CampusHangzhou 310028China Department of Mathematics Hong Kong Baptist UniversityKowloon TongHong Kong

Focuses on a study that discusses the linear finite element approximations for the Timoshenko beam and the shallow arch problems with shear dampening and reduced integration. Information on the Timoshenko beam; Detail... 详细信息

关键词： Timoshenko beam shallow arch shear dampening reduced integration

A general law of human mobility

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Science China(Information Sciences) 2015年第10期58卷 24-37页

作者： liang xiao ZHAO JiChang XU Ke Key Laboratory of Technology in Geo-spatial Information Processing and Application System Institute of Electronics Chinese Academy of Sciences School of Economics and Management Beihang University State Key Laboratory of Software Development Environment Beihang University

The intrinsic factors that drive human mobility have remained unclear for decades. Our observations from both intra-urban and inter-urban trips demonstrate a general law of human mobility. Specifically, the probability that a trip will occur is inversely proportional to the size of population located inside a circle with radius equal to the travel distance centered at the trip origin. A simple parameterless rank-based model is presented; this model can predict human flows with a convincing fidelity. Moreover, existing models can be implemented as special cases of our model, suggesting that our model is stable at more spatial scales. Our model also creates a fundamental bridge between individual mobility and social relationships.

关键词： human mobility social mobility general law rank-based model flux prediction

A statistical approach to determine 2D optimal equivalent linear parameters with application to earthquake engineering

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Earthquake Engineering and Engineering Vibration 2012年第3期11卷 415-425页

作者： Su liang xiao Nan Wang Yi College of Civil Engineering and Architecture Zhejiang University Hangzhou 310058 China China Aviation Planning and Construction Development Co. Ltd Beijing 100120 China

The equivalent linearization method approximates the maximum displacement response of nonlinear structures through the corresponding equivalent linear system. By using the particle swarm optimization technique, a new statistical approach is developed to determine the key parameters of such an equivalent linear system over a 2D space of period and damping ratio. The new optimization criterion realizes the consideration of the structural safety margin in the equivalent linearization method when applied to the performance-based seismic design/evaluation of engineering structures. As an application, equations for equivalent system parameters of both bilinear hysteretic and stiffness degrading single-degree-of- freedom systems are deduced with the assumption of a constant ductility ratio. Error analyses are also performed to validate the proposed approach.

关键词： equivalent linearization particle swarm optimization structural safety nonlinear displacement response performance-based engineering

Numerical Study of Propulsion Mechanism for Oscillating Rigid and Flexible Tuna-Tails

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Journal of Bionic Engineering 2011年第4期8卷 406-417页

作者： liang Yang Yumin Su Qing xiao State Key Laboratory of Autonomous Underwater Vehicle Harbin Engineering University Harbin 150001 P. R. China Department of Naval Architecture and Marine Engineering University of Strathelyde Glasgow G40LZ United Kingdom

Numerical study on the unsteady hydrodynamic characteristics of oscillating rigid and flexible tuna-tails in viscous flow-field is performed. Investigations are conducted using Reynolds-Averaged Navier-Stokes （RANS） equations with a moving adaptive mesh. The effect of swimming speed, flapping amplitude, frequency and flexure amplitude on the propulsion performance of the rigid and flexible tuna-tails are investigated. Computational results reveal that a pair of leading edge vortices develop along the tail surface as it undergoes an oscillating motion. The propulsive efficiency has a strong correlation with various locomotive parameters. Peak propulsive efficiency can be obtained by adjusting these parameters. Particularly, when input power coeffcient is less than 2.8, the rigid tail generates larger thrust force and higher propulsive efficiency than flexible tail. However, when input power coefficient is larger than 2.8, flexible tail is superior to rigid tail.

关键词： tuna-tail RANS propulsion mechanism hydrodynamic characteristics viscous flow-fields

Enhancement of the photoassociation of ultracold atoms via a non-resonant magnetic field

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Chinese Physics B 2020年第8期29卷 239-242页

作者： Ji-Zhou Wu Yu-Qing Li Wen-liang Liu Peng Li xiao-Feng Wang Peng Chen Jie Ma Lian-Tuan xiao suo-Tang Jia State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Laser SpectroscopyShanxi UniversityTaiyuan 030006China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China College of Physics and Electronics Engineering Shanxi UniversityTaiyuan 030006China

We report an effective method for enhancing the photoassociation of ultracold atoms using a non-resonant magnetic field,which enables the manipulation of the coupling between the wavefunctions of the colliding atomic pairs and the excited molecules.A series of photoassociation spectra are measured for different magnetic *** show that the photoassociation rate is significantly dependent on the non-resonant magnetic field.A qualitatively theoretical explanation is provided,and shows a good agreement with the experimental result.

关键词： photoassociation ultracold atoms magnetic field