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arXiv 2017年

作者： Mahdi Davari Esfahani, M. Zhu, Qiang Dong, Huafeng Oganov, Artem R. Wang, Shengnan Rakitin, Maksim S. Zhou, Xiang-Feng Department of Geosciences Center for Materials by Design Institute for Advanced Computational Science State University of New York Stony BrookNY11794-2100 United States Skolkovo Institute of Science and Technology Skolkovo Innovation Center 3 Nobel St. Moscow143026 Russia Moscow Institute of Physics and Technology 9 Institutskiy Lane Dolgoprudny City Moscow Region141700 Russia International Center for Materials Design Northwestern Polytechnical University Xi’an710072 China NSLS-II Brookhaven National Laboratory UptonNY11973-5000 United States School of Physics and Key Laboratory of Weak-Light Nonlinear Photonics Nankai University Tianjin300071 China

With the motivation of searching for new superconductors in the Mg-B system, we performed ab initio evolutionary searches for all the stable compounds in this binary system in the pressure range of 0-200 GPa. We found previously unknown, yet thermodynamically stable, compositions MgB3 and Mg3B10. Experimentally known MgB2 is stable in the entire pressure range 0-200 GPa, while MgB7 and MgB12 are stable at pressures below 90 GPa and 35 GPa, respectively. We predict a reentrant behavior for MgB4, which becomes unstable against decomposition into MgB2 and MgB7 at 4 GPa and then becomes stable above 61 GPa. We find ubiquity of phases with boron sandwich structures analogous to the AlB2-type structure. However, with the exception of MgB2, all other magnesium borides have low electron-phonon coupling constants λ of 0.32 to 0.39 and are predicted to have Tc below 3 K. Copyright © 2017, The Authors. All rights reserved.

关键词： Aluminum compounds

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CFD simulation of direct contact condensation phenomenon of vapor in subcooled water tank 23

CFD simulation of direct contact condensation phenomenon of ...

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23rd International Conference on Nuclear Engineering: Nuclear Power - Reliable Global Energy, ICONE 2015

作者： Ji, Yu Quan, Yan Zhang, Yining Zhang, Haochun Wang, Yahui Harbin Institute of Technology Harbin Heilongjiang China Science and Technology on Reactor System Design Technology Laboratory Chengdu Sichuan China

ISBN: (纸本)9784888982566

The direct contact condensation (DCC) is a significant phenomenon in nuclear reactor and its balance facilities, together with other chemical engineering systems. DCC occurs when the vapor is injected into the subcooled water, contacts and condenses on the interface directly. The DCC phenomenon accompanied with the heat transfer and mass transfer will result in the temperature and pressure fluctuations in the tank. This paper discusses the DCC in the subcooled water tank from the view of computation fluid dynamics. The numerical simulation was performed with the CFD software, Fluent, in which the direct contact condensation phenomenon was modeled with the Euler-Euler framework for two phases flow, and the evaporation & condensation model was adopted to simulate the mass transfer process. During the simulation process, the flow field and temperature field are derived. In addition, the shape and size of plume jet are also investigated. Copyright © 2015 by JSME.

关键词： Heat transfer

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Experiment of Azimuth-invariant Bistatic UHF UWB SAR

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Journal of Physics: Conference Series 2018年第1期960卷

作者： Hongtu Xie Shaoying Shi Junfa Mao Fuhai Li Daoxiang An Zhimin Zhou Guoqian Wang Key Laboratory of Ministry of Education of Design and Electromagnetic Compatibility of High Speed Electronic Systems Shanghai Jiao Tong University Shanghai China College of Electrical and Information Engineering Hunan University Changsha Air Force Early Warning Academy Wuhan China College of Electronic Science National University of Defense Technology Changsha Hunan Institute of Traditional Chinese Medicine Changsha China

Bistatic ultrahigh frequency ultrawideband synthetic aperture radar (UHF UWB SAR) has the well ability of the penetrating the foliage, high-resolution imaging and providing the increased information. In the paper, an imaging experiment of the azimuth-invariant bistatic UHF UWB SAR is described and the result is proposed. In August 2015, an along-track bistatic UHF UWB SAR experiment was conducted in China, and the raw data was collected. In this bistatic SAR system, the transmitter and receiver are both carried by a vehicle and separated by an invariable distance. The aim was to investigate the imaging property of the bistatic UHF UWB SAR system. Bistatic image was obtained using the subaperture spectrum-equilibrium method integrated with the fast factorized back projection algorithm (FFBPA). Experiment results prove the validity of the bistatic UHF UWB SAR experiment.

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An Algorithm for Global Path Planning and Multi-objective Optimization Using Cell Mapping

An Algorithm for Global Path Planning and Multi-objective Op...

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第十届全国动力学与控制学术会议

作者： XUE Yang XIONG Fu-rui SUN Jian-qiao Department of Mechanics Tianjin UniversityTianjin300350China Science and Technology on Reactor System Design Technology LaboratoryNuclear Power Institute of ChinaChengdu 610041China School of EngineeringUniversity of CaliforniaMercedCA 95343USA

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Multi-objective Optimization of Elastic Beams For Minimum Weight and Sound Radiation

Multi-objective Optimization of Elastic Beams For Minimum We...

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第十届全国动力学与控制学术会议

作者： Meng-xin He Fu-Rui Xiong Yousef Naranjani Qian Ding Jian-Qiao Sun Department of Mechanics Tianjin University Tianjin300072China Science and Technology on Reactor System Design Technology LaboratoryNuclear Power Institute of ChinaChengdu 610041China School of EngineeringUniversity of California MercedCA 95343USA

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Simulation of body force effect on steady and unsteady flow induced by DBD plasma actuator 47

Simulation of body force effect on steady and unsteady flow ...

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47th AIAA Plasmadynamics and Lasers Conference, 2016

作者： Wu, Bin Gao, Chao Liu, Feng Xiong, Juntao Department of Fluid Mechanics Northwestern Polytechnical University Xi’an710072 China National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical University Xi’an710072 China Department of Mechanical and Aerospace Engineering University of California IrvineCA92697-3975 United States

ISBN: (数字)9781624104343

ISBN: (纸本)9781624104343

The density field induced by Dielectric-Barrier-Discharge (DBD) plasma actuation is visualized through the schlieren photography. Meanwhile, based on PIV system, velocity fields are accurately measured. In steady plasma flow, continuous discharge is applied. On the other side, duty-cycle discharge is used in unsteady plasma flow study. By solving the Maxwell’s electromagnetic equations, a model of body force is established. Based on this electro-static model, numerical simulation of flow over the plate with DBD plasma actuators are presented. Comparisons of computation and experiment of steady and unsteady plasma flows are consistent in both continuous discharge and duty-cycle discharge. Experiment of PIV and schlieren results verify the correctness of the model which can be applied to both steady and unsteady flow. The result also shows that there are vortexes forming upon the encapsulated electrode near the gap side, and move with the direction of other side of encapsulated electrode in the duty-cycle discharge. When duty-cycle increasing fromt =0.3 tot =0.5, vortexes near the plasma actuator are more concentrated. In continuous discharge, that ist =1, the vortex flow become the jet flow. The vortexes play a very important role in the mechanism research of flow induced by DBD plasma actuators. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Vortex flow

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An energy-efficient design for multihop relay network adopting CC-HARQ scheme

An energy-efficient design for multihop relay network adopti...

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International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Junmei Han Songhu Ge Yong Xi Jibo Wei School of Electronic Science and Computer Engineering National University of Defense Technology Changsha Hunan National Key Laboratory for Vessel Integrated Power System Technology Naval University of China Engineering Wuhan China

ISBN: (纸本)9781509028610

This paper investigates the energy-efficient design of a multihop relay network adopting the Chase Combining based Hybrid Automatic Repeat reQuest (CC-HARQ) scheme with sum power constraint from a cross-layer perspective. We aim at maximizing the energy efficiency (EE) in the multihop relay network by jointly optimizing the payload length and average transmission energy per bit over all hops, with no limitation on the total number of (re)transmissions times. The theoretical findings are verified by simulations and the impacts of various parameters, e.g., the modulation and coding scheme (MCS) levels, channel gains and transmission distance, on EE are studied in detail. The results demonstrate that significant energy saving can be achieved by the proposed joint optimum algorithm.

关键词： Spread spectrum communication Relay networks (telecommunications) Payloads Frequency modulation Signal to noise ratio

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Natural convective heat transfer from a heated slender vertical tube in a cylindrical tank 16

Natural convective heat transfer from a heated slender verti...

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16th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2015

作者： Xian, Lin Jiang, Guangming Yu, Hongxing Science and Technology on Reactor System Design Technology Laboratory Chengdu610041 China Nuclear Power Institute of China Chengdu610041 China

ISBN: (纸本)9781510811843

Natural convective heat transfer in enclosures is widely researched in extensive range of engineering application such as passive residual heat removal system (PRHRS) in nuclear plant, solar collectors and cooling of electronic equipment. After Fukushima incident, the application and researching of PRHRS have been gaining more and more attention. It still has no proper calculating tools to analyze natural convective heat transfer with large L/D ratio and high Rayleigh number in PRHRS. In this paper, based on some former natural convective heat transfer experiments, numerical simulations and scale analysis, the single phase natural convective heat transfer correlation from the vertical tube have been developed. Transient single phase natural convection heat transfer along vertical tube in a cylindrical enclosure has been investigated for water with widely used computational fluid dynamic (CFD) engineering program ANSYS CFX-12. The influence brought by different geometry of tube and mesh scales has been evaluated by the results of former experiments. The ratio of tube length to diameter is a dimensionless factor affects heat transfer rate. The evaluation of thermal stratification to natural convective heat transfer in enclosure has been studied. Numerical simulation covers large L/D and high Rayleigh number natural convection: 108RaL14. Based on the scale analysis of natural convection cylindrical boundary equations the new dimensionless group has been put forward contains L/D factor. The new natural convective heat transfer along the vertical single tube model has been build according to the former experiments1 results. After combining numerical simulation results, the new model covers the higher Rayleigh number range of natural convection.

关键词： Natural convection

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Research on large equipment maintenance system in life cycle

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IOP Conference Series: Earth and Environmental science 2017年第1期69卷

作者： Xiaowei Xu Hongxia Wang Zhenxing Liu Nan Zhang School of Automobile and Traffic Engineering Wuhan University of Science and Technology Wuhan 430081 China Hubei Key Laboratory of Power System Design and Test for Electrical Vehicle Xiangyang 441053 China

In order to change the current disadvantages of traditional large equipment maintenance concept, this article plans to apply the technical method of prognostics and health management to optimize equipment maintenance strategy and develop large equipment maintenance system. Combined with the maintenance procedures of various phases in life cycle, it concluded the formulation methods of maintenance program and implement plans of maintenance work. In the meantime, it takes account into the example of the dredger power system of the Waterway Bureau to establish the auxiliary platform of ship maintenance system in life cycle.

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Multiple unpinned Dirac points in group-Va single-layers with phosphorene structure

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npj Computational Materials 2016年第1期2卷 142-148页

作者： Yunhao Lu Di Zhou Guoqing Chang Shan Guan Weiguang Chen Yinzhu Jiang Jianzhong Jiang Xue-sen Wang Shengyuan A Yang Yuan Ping Feng Yoshiyuki Kawazoe Hsin Lin School of Materials Science and Engineering Zhejiang UniversityHangzhouChina State Key Laboratory of Silicon Materials Zhejiang UniversityHangzhouChina Centre for Advanced 2D Materials and Graphene Research Centre National University of SingaporeSingaporeSingapore Department of Physics National University of SingaporeSingaporeSingapore Research Laboratory for Quantum Materials Singapore University of Technology and DesignSingaporeSingapore College of Physics and Electronic Engineering Zhengzhou Normal UniversityZhengzhouChina New Industry Creation Hatchery Center Tohuku UniversitySendaiJapan Institute of Thermophysics Siberian Branch of Russian Academy of SciencesNovosibirskRussia

Emergent Dirac fermion states underlie many intriguing properties of graphene,and the search for them constitutes one strong motivation to explore two-dimensional(2D)allotropes of other ***,the ultrathin layers of black phosphorous,has been a subject of intense investigations recently,and it was found that other group-Va elements could also form 2D layers with similar puckered lattice ***,by a close examination of their electronic band structure evolution,we discover two types of Dirac fermion states emerging in the low-energy *** pair of(type-I)Dirac points is sitting on high-symmetry lines,while two pairs of(type-II)Dirac points are located at generic k-points,with different anisotropic dispersions determined by the reduced symmetries at their *** fully-unpinned(type-II)2D Dirac points are discovered for the first *** the absence of spin-orbit coupling(SOC),we find that each Dirac node is protected by the sublattice symmetry from gap opening,which is in turn ensured by any one of three point group *** SOC generally gaps the Dirac nodes,and for the type-I case,this drives the system into a quantum spin Hall insulator *** suggest possible ways to realise the unpinned Dirac points in strained phosphorene.

关键词： structure spectrum Dirac

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