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The effects of relative density of metal foams on the stresses and deformation of beam under bending

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Acta Mechanica Sinica 2007年第4期23卷 409-414页

作者： Aiyu Zhu tianyou fan department of Mathematics,School of Science,beijing institute of technology,P.O.Box 327,beijing 100081,china department of physics,School of Science,beijing institute of technology,P.O.Box 327,beijing 100081,china department of Mathematics School of Science Beijing Institute of Technology Beijing China department of physics School of Science Beijing Institute of Technology Beijing China

The exact analytic solution of the pure bending beam of metallic foams is given. The effects of relative density of the material on stresses and deformation are revealed with the Triantafillou and Gibson constitutive law （TG model） taken as the analysis basis. Several examples for individual foams are discussed, showing the importance of compressibility of the cellular materials. One of the objects of this study is to generalize Hill＇s solution for incompressible plasticity to the case of compressible plasticity, and a kinematics parameter is brought into the analysis so that the velocity field can be determined.

关键词： Metal foams - Relative density Compressible plasticity Constitutive law - TG model

Nontrivial homoclinic orbits for second-order singular and periodic Hamiltonian systems

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Chinese Science Bulletin 1999年第2期44卷 123-129页

作者： li Chengyue , fan tianyou TONG MingshengResearch Center of Materials Science, beijing institute of technology, beijing 100081, china department of Mathematics, Central University for Nationalities, beijing 100081, china Computer Center, beijing institute of technology, beijing 100081, china Research Center of Materials Science Beijing Institute of Technology Beijing China department of Mathematics Central University for Nationalities Beijing China Computer Center Beijing Institute of Technology Beijing China

The existence of nontrivial homoclinic orbits of periodic Hamiltonian systems: is proved, where q=（q1,q2,’',qn）, n>2; V（t, q）:R1×Rn\{e}→R1 is a potential With a singularity, i.e. -V（t, q）→+∞, as q→e. The m... 详细信息

关键词： Hamiltonian systems strong force condition homoclinic orbit.

An optimal flow rate allocation model of the oilfield treated oil pipeline network

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Petroleum 2024年第1期10卷 93-100页

作者： Hai li tianyou fan Kun Wang Xueyuan Long Yu He Meng Wang Wen Cheng Qian Huang Huirong Huang Weichao Yu Petrochina Southwest Oil&Gasfield Company Chengdu 610056China china Petroleum Planning&Engineering institute Beijing 100083China School of Petroleum Engineering Chongqing University of Science and TechnologyChongqing 401331China Pipechina Oil&Gas Control Center Dongtucheng RoadChaoyang DistrictBeijing 100028China

Oilfield treated oil pipeline network is the link connecting the upstream oilfields and the downstream *** to the differences in operating costs and transportation fee between different pipelines and the fluctuation in the demand and sales prices of the treated oil,there is an optimal flow allocation plan for the pipeline network to make the oilfield company obtain the highest social and economic *** this study,a mixed integer nonlinear programming(MINLP)model is developed to determine the optimal flow rate allocation plan of the large-scale and complex treated oil pipeline network,and both the social and economic benefits are considered *** optimization objective is the multi-objective which includes the largest user satisfaction and the highest economic *** model constraints include the oilfield production capacity,refinery demand,pipeline transmission capacity,flow,pressure,and temperature of the node and station,and the pipeline hydraulic and thermal *** 3.7 is utilized for the programming of the off-line calculation procedure and the MINLP model,and GUROBI 9.0.2 is served as the MINLP ***,the model is applied to a real treated oil pipeline network located in china,and three optimization scenarios are *** social benefit,the values of the user satisfaction of each refinery and the total network are 1 before and after optimization for scenarios 1,2,and *** economic benefit,the annual revenue can be increased by 0.227,0.293,and 0.548 billion yuan after the optimization in scenario 1,2,and 3,respectively.

关键词： Treated oil pipeline network Flow rate allocation Optimal User satisfaction Economic benefit

Calculation of light emission in sonoluminescence

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Science china(physics,Mechanics & Astronomy) 2009年第4期52卷 593-601页

作者： li ChaoHui1 & AN Yu1,2 1 department of physics,Tsinghua University,beijing 100084,china 2 institute of Acoustics,Chinese Academy of Sciences,beijing 100190,china department of physics Tsinghua University Beijing China institute of Acoustics Chinese Academy of Sciences Beijing China

We modify a uniform model of single bubble sonoluminescence,in which heat diffusion,water vapor diffusion and chemical reactions are included to describe the bubble dynamics,and the processes of electron-atom bremsstrahlung,electron-ion bremsstrahlung and recombination radiation,radiative attachment of electrons to atoms and molecules,line emissions of OH radicals and Na atoms are taken into account to calculate the light emission. With this model,we compute the light pulse width,the photon number per flash,the continuum and line spectra and the gas species as the products of chemical reactions,and try to compare with all the experimental data available. We obtain good agreement with the observations of Ar and Xe bubbles in many cases,but fail to match the experimental data of the photon number per flash. We also find that for He bubble the computed photon number is always too small to interpret the observations.

关键词： sonoluminescence bremsstrahlung radiative attachment line spectrum collision broadening

ON THE EXISTENCE OF SOLUTIONS TO A TYPE OF NONliNEAR DIFFERENTIAL-ITERATIVE EQUATIONS

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Chinese Annals of Mathematics,Series B 2000年第2期21卷 217-224页

作者： GE WEIGAO(department of Applied Mathematics, beijing institute of technology, beijing 100081, china.) li CUIZHE(department of Applied Mathematics, beijing institute of technology, beijing 100081, china.) YU YUANHONG(Inditute of Applied Mathematics, Acad department of Applied Mathematics Beijing Institute of Technology Beijing 100081 China institute of Applied Mathematics Academia Sinica Beijing 100080 China

Under the assumption that h(z) is strictly monotone the existence of solutions to a type of nonlinear differential-iterative equations in the form of x’(t) = g(x(t)) -h(x(x(t))) is discussed according to the behavior... 详细信息

关键词： Differential-iterative equation Quasi-isoclinic curve Fixed point

Impact of non-ideal UE hardware on cell-free massive MIMO network with centralized operation

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Science china(Information Sciences) 2024年第4期67卷 255-271页

作者： Ning li Pingzhi fan institute of Mobile Communications Southwest Jiaotong University

This paper investigates the impact of non-ideal user equipment(UE) hardware on a cell-free(CF) massive MIMO(mMIMO) network with centralized operation under spatially correlated channels. The minimum mean-squared error(MMSE) estimator can be derived with the help of the generic non-ideal UE hardware model. It is demonstrated that even if the effective signal-to-noise ratio approaches infinity, pilot contamination and imperfect hardware can cause a non-zero estimation error floor. After that, a lower bound is determined for the ergodic uplink capacity of the centralized CF mMIMO network under non-ideal UE hardware. Moreover, the optimal receive combining vector is obtained to maximize the uplink spectral efficiency(SE). The maximum ratio(MR) and regularized zero-forcing(RZF) combining schemes are offered as alternatives in light of the computational complexity of the MMSE receiver. Comparing the RZF to the MMSE scheme under different levels of hardware impairments, our findings indicate that the RZF receiver suffers a negligible loss in total SE. For MR combining, a novel closed-form uplink achievable SE expression is obtained based on the MMSE estimator and the use-and-then-forget bounding technique. This expression gives vital insights into the achievable uplink performance with UE hardware impairments. Besides, for various hardware impairment factors, the impact of pilot sequence length on average sum SE is disclosed for different receive combining schemes. To increase the overall SE of the max-min fairness scheme, a heuristic fractional power control scheme with UE hardware impairments is developed, which can essentially avoid sacrificing the SE of other UEs while maximizing the SE of the unluckiest UE in the whole network. Finally,our theoretical performance analysis and power control algorithm are validated by simulation results, and fundamental design guidelines are provided for selecting hardware satisfying the practical UE requirements.

关键词： cell-free massive MIMO centralized operation spatially correlated channels hardware impairments channel estimation uplink spectral efficiency optimal receive combining pilot length design fractional power control

Influence of Dissipation on Multiparticle Entanglement Transfer

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Communications in Theoretical physics 2007年第12期48卷 1033-1037页

作者： li Jun-Gang ZOU Jian JI Tao SHAO Bin CAI Jin-fang department of physics,beijing institute of technology,beijing 100081,china department of physics Beijing Institute of Technology Beijing 100081 China

We investigate the influence of the initial mixture of qubits and the dissipation on the entanglement transferfrom three-qubit Greenberger-Horne-Zeilinger (GHZ) and W state fields to three matter qubits,which are trapped inthree spatially separated *** find that at gt≈11.07,the entanglement transfer can be almost complete nomatter what state the qubits are initially prepared *** the dissipation is taken into account,we tind that thespontaneous emission plays the similar role to the cavity damping in the entanglement transfer,and the decay rate ofthe GHZ state is larger than that of the W state.

关键词： W state GHZ state entanglement transfer dissipation

Holographic superfluid ring with a weak link

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Science china(physics,Mechanics & Astronomy) 2024年第11期67卷 29-38页

作者： Zhi-Hong li Huai-fan li department of physics Shanxi Datong UniversityDatong 037009China institute of Theoretical physics Shanxi Datong UniversityDatong 037009China

We explore the generation of topological defects in the course of a dynamical phase transition in a ring with a weak link, i.e., a SSS Josephson junction, from the AdS/CFT correspondence. By setting different parameters of the junction(width, steepness,depth) and the final temperature of the quench, the configurations of the charge density and condensate of the order parameters of the dual field theory are presented. Meanwhile, we observe that in the final equilibrium state, variations in parameters of the junctions only affect the configurations of the charge density and condensate of the order parameters, without altering their values outside the junction. However, variations in the final temperature will directly affect the values of the charge density and condensate of the order parameters outside of the junction. Moreover, in the final equilibrium state, we propose an analytic relation between the gauge-invariant velocity in the two superconducting states in the SSS Josephson junction, which agrees well with the numerical results.

关键词： AdS/CFT correspondence holographic superfluid holographic Josephson junction

Fiducial inference in the pivotal family of distributions

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Science china Mathematics 2006年第3期49卷 410-432页

作者： XU Xingzhong & li Guoying department of Mathematics, beijing institute of technology, beijing 100081, china Academy of Mathematics and Systems Science, Chinese Academy of Sciences, beijing 100080, china department of Mathematics Beijing Institute of Technology Beijing China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing China

In this paper a family, called the pivotal family, of distributions is considered.A pivotal family is determined by a generalized pivotal model. Analytical results show that a great many parametric families of distributions are pivotal. In a pivotal family of distributions a general method of deriving fiducial distributions of parameters is proposed. In the method a fiducial model plays an important role. A fiducial model is a function of a random variable with a known distribution, called the pivotal random element, when the observation of a statistic is *** method of this paper includes some other methods of deriving fiducial distributions. Specially the first fiducial distribution given by Fisher can be derived by the method. For the monotone likelihood ratio family of distributions, which is a pivotal family, the fiducial distributions have a frequentist property in the Neyman-Pearson view. Fiducial distributions of regular parametric functions also have the above frequentist property. Some advantages of the fiducial inference are exhibited in four applications of the fiducial distribution. Many examples are given, in which the fiducial distributions cannot be derived by the existing methods.

关键词： confidence bounds, fiducial distributions, fiducial model, frequentist prop-erty, generalized pivotal model, pivotal family of distributions, testing hypotheses.