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Effects of temperature distribution and level on heat transfer on a rotating free disk

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航空动力学报 2011年第6期26卷 1310-1320页

作者： ZHAO Xi XU guo-qiang LUO Xiang National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100191 China

In gas turbine engines,with the existence of the intense forced convection and significant buoyancy effects,temperature distribution and level on turbine or compressor disks affect the heat transfer characteristics *** this paper,numerical simulations were performed to analyze these influences for a free disk,with the laminar and turbulent flow *** influences of temperature distribution on the heat transfer were observed by using incompressible cooling air,and temperature profiles of nth order monomial and polynomial were assumed on the *** analysis revealed that the heat transfer for two flow states on the free disk is determined by the exponent n of the monomial profile when specifying the rotating Reynolds number;for an arbitrary polynomial profile,the local Nusselt number can be deduced from results of monomial *** study the effects of temperature level on heat transfer singly,monomial profiles were used and the local Nusselt number of compressible and incompressible cooling air were *** both for two flow states,the following conclusions could be drawn: the relative difference of local Nusselt number is mainly controlled by nondimensional local temperature difference,and almost independent of the monomial's coefficient C,exponent n and the rotating Reynolds ***,a correction method for heat transfer of the free disk is presented and verified computationally,with which the local Nusselt number,obtained with a uniform and low temperature profile,can be revised by arbitrary distribution and high temperature magnitude.

关键词： thermal boundary condition temperature boundary condition rotating disk free disk heat transfer

Interfacial intermetallic compound growth and shear strength of low-silver SnAgCuBiNi/Cu lead-free solder joints

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International Journal of Minerals,Metallurgy and Materials 2013年第9期20卷 883-889页

作者： guo-qiang Wei Lei Wang Xin-qiang Peng Ming-yang Xue School of Mechanical and Automotive Engineering South China University of Technology

The growth rule of the interfacial intermetallic compound （IMC） and the degradation of shear strength of ***-0.5Cu-2.0Bi-0.05Ni （SACBN）/Cu solder joints were investigated in comparison with Sn-3.0Ag-0.5Cu （SAC305）/ Cu solder joints aging at 373, 403, and 438 K. The results show that （Cul-x,Nix）6Sn5 phase forms between the SACBN solder and Cu substrate during soldering. The interracial IMC thickens constantly with the aging time increasing, and the higher the aging temperature, the faster the IMC layer grows. Compared with the SAC305/Cu couple, the SACBN/Cu couple exhibits a lower layer growth coefficient. The activation energies of IMC growth for SACBN/Cu and SAC305/Cu couples are 111.70 and 82.35 kJ/mol, respectively. In general, the shear strength of aged solder joints declines continuously. However, SACBN/Cu solder joints exhibit a better shear strength than SAC305/Cu solder joints.

关键词： soldering alloys soldered joints aging intermetallics activation energy shear strength

Populating ^(229m)Th via two-photon electronic bridge mechanism

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Nuclear Science and Techniques 2021年第6期32卷 45-53页

作者： Neng-qiang Cai guo-qiang Zhang Chang-Bo Fu Yu-Gang Ma Shanghai Tech University Shanghai 201210China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201210China Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China

The isomer ^(229m)Th is the most promising candidate for clocks based on the nuclear transition because it has the lowest excitation energy of only 8.10±0.17 *** experiments and theories have focused on methods of triggering the transition between the ground state and isomeric state,among which the electronic bridge(EB)is one of the most *** this paper,we propose a new electronic bridge mechanism via two-photon excitation based on quantum optics for a two-level nuclear quantum *** long-lived 7 s1/2 electronic shell state of^(229m)Th^(3+),with a lifetime of approximately 0.6 s,is chosen as the initial state and the atomic shells(7 s-10 s)could be achieved as virtual states in a two-photon *** the virtual states return to the initial state 7 s1/2,there is a chance of triggering the nucleus 229Th^(3+),to its isomeric state ^(229m)Th ^(3+),via *** lasers at moderate intensity((10^(10)-10^(14))W/m^(2)),with photon energies near the optical range,are expected to populate the isomer at a saturated rate of approximately 10^(9) s^(-1),which is much higher than that due to other *** believe that this twophoton EB scheme can help in the development of nuclear clocks and deserves verification via a series of experiments with ordinary lasers in laboratories.

关键词： Electronic bridge ^(229)mTh Nuclear clocks Two-photon excitation

Dissipation-induced nonreciprocal magnon blockade in a magnon-based hybrid system

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Science China(Physics,Mechanics & Astronomy) 2022年第6期65卷 44-52页

作者： Yimin Wang Wei Xiong Zhiyong Xu guo-qiang Zhang Jian-qiang You Communications Engineering College Army Engineering University of PLANanjing 210007China Department of Physics Wenzhou UniversityWenzhou 325035China Interdisciplinary Center of Quantum Information State Key Laboratory of Modern Optical Instrumentationand Zhejiang Province Key Laboratory of Quantum Technology and DeviceSchool of PhysicsZhejiang UniversityHangzhou 310027China

We propose an experimentally realizable nonreciprocal magnonic device at the single-magnon level by exploiting magnon block-ade in a magnon-based hybrid *** coherent qubit-magnon coupling,mediated by virtual photons in a microwave cavity,leads to the energy-level anharmonicity of the composite *** contrast,the corresponding dissipative counterpart,induced by traveling microwaves in a waveguide,yields inhomogeneous broadenings of the energy *** a result,the cooperative effects of these two kinds of interactions give rise to the emergence of the direction-dependent magnon *** show that this can be demonstrated by studying the equal-time second-order correlation function of the magnon *** study opens an avenue to engineer nonreciprocal magnonic devices in the quantum regime involving only a small number of magnons.

关键词： nonreciprocal magnon blockade non-classical statistics dissipative coupling hybrid system

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The flow characteristics around bridge piers under the impact of a ship

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Journal of Hydrodynamics 2020年第6期32卷 1165-1177页

作者： Yan-fen Geng Hua-qiang guo Xing Ke School of Transportation Southeast UniversityNanjing211189China

The complicated flow structure around the pier threatens the safe navigation of *** paper studies the mechanism of the flow with a ship around the pier,passing or not passing and with consideration of the interval between the ship and the *** flow field model and the moving ship model are constructed by the six degrees of freedom(6DOF)solver combined with the virtual unit immersed boundary method and the level set method,both of which are based on the three-dimensional Navier-Stokes *** simulation results show that the ship significantly influences the flow around the pier,increasing the flow velocity by 50%to 140%.Away from the bridge pier,the cross-flow velocity *** cross-flow velocity near the side of the pier also increases but in the opposite *** ship is affected by the negative yaw moment because of the reverse cross-flow between the pier and the *** size of the ship has an important impact on the extent of the affected flow areas but the velocity distribution is roughly in the same *** results show double impacts of ship and pier should be considered when determining the safe area of navigation.

关键词： Bridge pier flow around cylinder moving ship model

Parameter Identification for Static Var Compensator Model Using Sensitivity Analysis and Improved Whale Optimization Algorithm

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CSEE Journal of Power and Energy Systems 2022年第2期8卷 535-547页

作者： qiang guo Lei Gao Xiaojie Chu Huadong Sun China Electric Power Research Institute Beijing 100192China

A parameter estimation method based on an improved Whale Optimization Algorithm is proposed in this paper to identify the parameters of a static var compensator(SVC)***,a mathematical model of SVC is ***,the reverse learning strategy and Levy flight disturbance strategy are introduced to improve the whale optimization algorithm,and the improved whale optimization algorithm is applied to the parameter identification of the static var compensator ***,a stepwise identification method,by analyzing the local sensitivities of parameters,is proposed which solves the problem of low accuracy caused by multi-parameter *** method provides a new estimation strategy for accurately identifying the parameters of the static var compensator *** results show that the parameter estimation method can be an effective tool to solve the problem of parameter identification for the SVC model.

关键词： Local sensitivity analysis parameter estimation static var compensator model stepwise identification method whale Optimization Algorithm

Enhanced production of poly-3-hydroxybutyrate by recombinant Escherichia coli containing NAD kinase and phb CAB operon

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Science China Chemistry 2016年第11期59卷 1390-1396页

作者： Shaoqin Zhang Lei Fang Zhengjun Li Yingying guo guo-qiang Chen Center for Synthetic and Systems Biology School of Life Science Tsinghua-Peking Center for Life SciencesTsinghua University Beijing Key Laboratory of Bioprocess College of Life Science and Technology Beijing University of Chemical Technology Center for Nano and Micro Mechanics Tsinghua University

With the help of Tn5 transposon technique, gene yfj B encoding NAD kinase in Escherichia coli(E. coli) was inserted into chromosome of recombinant E. coli polyhydroxybutyrate(PHB) containing PHB synthesis operon integrated in the host genome. After successful transposition of an extra yfj B gene copy into genome, the selected recombinant named E. coli PHBTY4 showed stronger NAD kinase activity than that of E. coli PHB. Shake flask studies suggested that both cell dry weight and PHB accumulation were significantly increased in E. coli PHBTY4 compared with that of the control. E. coli PHBTY4 produced approximately 23 g/L PHB compared with its control which synthesized only 10 g/L PHB when grown under the same conditions in a 6 L fermentor after 32 h of cultivation. In addition, E. coli PHBTY4 maintained high genetic stability during the cultivation processes. These results revealed a practical method to construct genetically stable strains harboring extra NAD kinase gene to enhance NADP(H)-dependent bio-reactions.

关键词： PHB polyhydroxyalkanoates Tn5 transposon NAD kinase Escherichia coli

Primal-dual Interior-point Algorithms for Second-order Cone Optimization Based on a New Parametric Kernel Function

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Acta Mathematica Sinica,English Series 2007年第11期23卷 2027-2042页

作者： Yan Qin BAI guo qiang WANG Department of Mathematics College of Sciences Shanghai University Shanghai 200444 P. R. China College of Vocational Technology Shanghai University of Engineering Science Shanghai 200437 P. R. China

A class of polynomial primal-dual interior-point algorithms for second-order cone optimization based on a new parametric kernel function, with parameters p and q, is presented. Its growth term is between linear and quadratic. Some new tools for the analysis of the algorithms are proposed. The complexity bounds of O（√Nlog N log N/ε） for large-update methods and O（√Nlog N/ε） for smallupdate methods match the best known complexity bounds obtained for these methods. Numerical tests demonstrate the behavior of the algorithms for different results of the parameters p and q.

关键词： second-order cone optimization linear optimization interior-point methods large- and small-update methods polynomial-time complexity

EXPERIMENTAL INVESTIGATION OF TIP CLEARANCE FLOW FOR AN AXIAL FLOW FAN ROTOR

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Chinese Journal of Mechanical Engineering 2006年第3期19卷 376-382页

作者： guo qiang ZHU Xiaocheng DU Zhaohui School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China

The flow field in the tip region of an axial ventilation fan is investigated with a particle image velocimeter （PIV） system at the design condition. Flow fields with three different tip clearances are surveyed on three different circumferential planes, respectively. The phase-locked average method is used to investigate the generation and the development of a tip leakage vortex. The result from PIV system is compared with that from a particle dynamics anemometer（PDA） system. Both data are in good agreement and the structure of the tip leakage vortex for the rotor is illustrated. The characteristic of a leakage vortex is described in both velocity vectors and vortical contours. The unsteadiness of the leakage vortex and the position of the vortex are surveyed in detail, which interprets the discrepancy between the numerical simulation and PDA experimental results to a certain extent. The center loci of tip leakage vortex at different times and the mean center loci of the leakage vortex are displayed particularly. Finally, the trajectories of the tip leakage vortex by the experimental measurement are compared with predictions from the existing models for high speed and high-pressure compressors and turbines when appropriately interpreted. A good agreement is obtained.

关键词： Axial ventilation fan Tip leakage vortex Particle image velocimetry (PIV) Vortex center trajectory