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arXiv 2018年

作者： Li, Lingxiang Quek, Tony Q.S. Ren, Ju Yang, Howard H. Chen, Zhi Zhang, Yaoxue School of Information Science and Engineering Central South University Changsha410083 China Information Systems Technology and Design Pillar Singapore University of Technology and Design Singapore487372 Singapore National Key Laboratory of Science and Technology on Communications UESTC Chengdu611731 China

This paper considers a scenario in which an access point (AP) is equipped with a mobile edge server of finite computing power, and serves multiple resource-hungry mobile users by charging users a price. Pricing provides users with incentives in offloading. However, existing works on pricing are based on abstract concave utility functions (e.g, the logarithm function), giving no dependence on physical layer parameters. To that end, we first introduce a novel utility function, which measures the cost reduction by offloading as compared with executing jobs locally. Based on this utility function we then formulate two offloading games, with one maximizing individual’s interest and the other maximizing the overall system’s interest. We analyze the structural property of the games and admit in closed form the Nash Equilibrium and the Social Equilibrium, respectively. The proposed expressions are functions of the user parameters such as the weights of computational time and energy, the distance from the AP, thus constituting an advancement over prior economic works that have considered only abstract functions. Finally, we propose an optimal pricing-based scheme, with which we prove that the interactive decision-making process with self-interested users converges to a Nash Equilibrium point equal to the Social Equilibrium point. Copyright © 2018, The Authors. All rights reserved.

关键词： Game theory

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The application of Lagrangian particle Tracking method in the study of steam generator sludge collector

The application of Lagrangian particle Tracking method in th...

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2017 International Congress on Advances in Nuclear Power Plants: A New Paradigm in Nuclear Power Safety, ICAPP 2017

作者： Wu, Ge Cheng, Xiang Huang, Wei Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory NO.328 First Sec. of Changshun Ave. Shuangliu District Chengdu China

ISBN: (纸本)9784890471676

During the operation of the Pressurized Water reactor recirculation steam generator, sludge particles from the feed water system and secondary system, mainly corrosion products, converge in the secondary side of steam generator. Since the saturated steam exiting the steam generator carries almost no sludge, the corrosion products' concentration increases with time. Although a part of the sludge can be removed by the blowdown system, the rest will either suspend in the water or deposit as a result of gravity, boiling or turbulence. Some sludge particles deposited on the surfaces of heat transfer tubes, tube sheet, and tube supporting plates or in the gaps around will cause a variety of problems, such as accelerating component device corrosion. The sludge collector is a passive device located in the upper internals of a PWR U-tube natural recirculation steam generator. It is able to trap and collect the sludge particles suspending in the secondary side fluid, which helps in reducing the amount of sludge available to settle on the tube bundle area. In this paper, the flow conditions and the sludge particle tracks around the sludge collector in a typical U-tube recirculation steam generator are studied by using a Computational Fluid Dynamics method. For the simulation method, a k-e model is selected as the turbulent model, and the two-way coupling Lagrangian Particle Tracking scheme is employed to account for the momentum transfer effects between the continuous phase of fluid and the discrete phase of particles. The forces acting on the sludge particles in this paper include the drag force, buoyancy force, and other additional forces such as added mass force and pressure gradient force. And the number of the representative particles captured by the sludge collector is also studied, while the mass flow rate entering the sludge collector is always paid more attention. The simulation results have successfully captured the flow patterns and the tracks of the representative

关键词： Steam generators

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A unified gas kinetic scheme for transport and collision effects in plasma

arXiv

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arXiv 2018年

作者： Pan, Dongxin Zhong, Chengwen Zhuo, Congshan Tan, Wei State Key Laboratory of Astronautic Dynamics Xi’anShaanxi710043 China National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical University Xi’an Shaanxi710072 China

In this study, the Vlasov-Poisson equation with or without collision term for plasma is solved by the unified gas kinetic scheme (UGKS). The Vlasov equation is a differential equation describing time evolution of the distribution function of plasma consisting of charged particles with long-range interaction. The distribution function is discretized in discrete particle velocity space. After the Vlasov equation is integrated in finite volumes of physical space, the numerical flux across a cell interface and source term for particle acceleration are computed to update the distribution function at next time step. The flux is decided by Riemann problem and variation of distribution function in discrete particle velocity space is evaluated with central difference method. A electron-ion collision model is introduced in the Vlasov equation. This finite volume method for the UGKS couples the free transport and long-range interaction between particles. The electric field induced by charged particles is controlled by the Poisson’s equation. In this paper, the Poisson’s equation is solved using the Green’s function for two dimensional plasma system subjected to the symmetry or periodic boundary conditions. Two numerical tests of the linear Landau damping and the Gaussian beam are carried out to validate the proposed method. The linear electron plasma wave damping is simulated based on electron-ion collision operator. Compared with previous methods, it is shown that the current method is able to obtain accurate results of the Vlasov-Poisson equation with a time step much larger than the particle collision time. Highly non-equilibrium and rarefied plasma flows, such as electron flows driven by electromagnetic field, can be simulated *** Codes 35Q83, 82D10, 82C40, 74S10, 34B27 Copyright © 2018, The Authors. All rights reserved.

关键词： Velocity control

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CFD simulation and validation of turbulent mixing in a rod bundle with vaned spacer grids based on LDV test

CFD simulation and validation of turbulent mixing in a rod b...

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2017 International Congress on Advances in Nuclear Power Plants: A New Paradigm in Nuclear Power Safety, ICAPP 2017

作者： Chen, Xi Li, Songwei Li, Zhongchun Du, Sijia Zhang, Yu Peng, Huanhuan Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China No. 328 Section 1 Changshun Avenue Shuangliu sub-district Chengdu Sichuan610213 China

ISBN: (纸本)9784890471676

Spacer grids with mixing vanes are generally used in fuel assemblies of Pressurized Water reactor (PWR), because that mixing vanes could enhance the lateral turbulent mixing in subchannels. Thus, heat exchangements are more efficient, and the value of departure from nucleate boiling (DNB) is greatly increased. Actually turbulent mixing is composed of two kinds of flows: swirling flow inside the subchannel and cross flow between subchannels. Swirling flow could induce mixing between hot water near the rod and cold water in the center of the subchannel, and may accelerate deviation of the bubbles from the rod surface. Besides, crossing flow help to mixing water between hot subchannels and cold subchannels, which impact relatively large flow area. As a result, how to accurately capture and how to predict the complicated mixing phenomenon are of great concernments. Recently many experimental studies has been conducted to provide detailed turbulent mixing in rod bundle, among which Laser Doppler Velocimetry method is widely used. With great development of Computational Fluid Dynamics, CFD has been validated as an analysis method for nuclear engineering, especially for single phase calculation. This paper presents the CFD simulation and validation of the turbulent mixing induced by spacer grid with mixing vanes in rod bundles. Experiment data used for validation came from 5 X5 rod bundle test with LDV technology, which is organized by science and technology on reactor system design technology laboratory. A 5 X5 rod bundle with two spacer grids were used. Each rod has dimension of 9.5 mm in outer diameter and distance between rods is 12.6 mm. Two axial bulk velocities were conducted at 3.0 m/s for high Reynolds number and 1.0 m/s for low Reynolds number. Working pressure was 1.0 bar, and temperature was about 25 V. Two different distances from the downstream of the mixing spacer grid and one from upstream were acquired. Mean axial velocities and turbulent intensities (Wrms

关键词： Mixing

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Sound transmission of periodic composite structure lined with porous core: Rib-stiffened double panel case

arXiv

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arXiv 2018年

作者： Qiao, Hou He, Zeng Jiang, Wen Peng, Weicai Department of Mechanics Huazhong University of Science &Technology Wuhan China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Huazhong University of Science & Technology Wuhan China National Key Laboratory on Ship Vibration and Noise China Ship Development and Design Center Wuhan China

Porous materials are effective for the isolation of sound with medium to high frequencies, while periodic structures are promising for low to medium frequencies. In the present work, we study the sound insulation of a periodically rib-stiffened double-panel with porous lining to reveal the effect of combining the two characters above. The theoretical development of the periodic composite structure, which is based on the space harmonic series and Biot theory, is included. The system equations are subsequently solved numerically by employing a precondition method with a truncation procedure. This theoretical and numerical framework is validated with results from both theoretical and finite element methods. The parameter study indicates that the presence of ribs can lower the overall sound insulation, although a direct transfer path is absent. Despite the unexpected model results, the method proposed here, which combines poroelastic modeling and periodic structures semi-analytically, can be promising in broadband sound modulation. Copyright © 2018, The Authors. All rights reserved.

关键词： Architectural acoustics

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Noble Metal Dichalcogenides: A Noble Metal Dichalcogenide for High‐Performance Field‐Effect Transistors and Broadband Photodetectors (Adv. Funct. Mater. 5/2020)

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Advanced Functional Materials 2020年第5期30卷

作者： Zhen Wang Peng Wang Fang Wang Jiafu Ye Ting He Feng Wu Meng Peng Peisong Wu Yunfeng Chen Fang Zhong Runzhang Xie Zhuangzhuang Cui Liang Shen Qinghua Zhang Lin Gu Man Luo Yang Wang Huawei Chen Peng Zhou Anlian Pan Xiaohao Zhou Lili Zhang Weida Hu State Key Laboratory of Infrared Physics Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai 200083 China University of Chinese Academy of Sciences Beijing 100049 China Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Hangzhou 310024 China State Key Laboratory of Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun 130012 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China Jiangsu Key Laboratory of ASIC Design Nantong University Nantong Jiangsu 226019 China State Key Laboratory of ASIC and System Department of Microelectronics Fudan University Shanghai 200433 China Key Laboratory for Micro‐Nano Physics and Technology of Hunan Province College of Materials Science and Engineering Hunan University Changsha 410082 China

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design of Wide Interval Frequency Hopping Pattern for Frequency Hopping Mobile Ad-hoc Networks

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Journal of Physics: Conference Series 2020年第1期1584卷

作者： Yadong Zhao Yu Zhang Jian Song Beijing National Research Center for Information Science and Technology (BNRist) Department of Electronic Engineering Tsinghua University Beijing 100084 China Key Laboratory of Digital TV System of Guangdong Province and Shenzhen City Research Institute of Tsinghua University in Shenzhen Shenzhen 518057. P.R. China

The frequency hopping mobile ad-hoc network (FH MANET) is a communication network that combines frequency hopping (FH) technology and mobile ad-hoc network (MANET) technology. FH technology can improve the anti-interference performance of the network, and MANET technology improves the mobility and anti-destructiveness of the network. It can be networked autonomously without manual intervention and other network facilities. It has strong application value in complex battlefield environment and occasions with harsh environment and high confidentiality requirements. The frequency hopping pattern (FHP) design is a key technology in the FH MANET, which is directly related to the network's anti-interference and multipath fading capabilities. In this paper, a wide interval expansion method (WIEBM) based on m-sequence and non-continuous tap L-G model is proposed. The experimental results demonstrate that proposed scheme can effectively improve the anti-interference ability of the system. It has the ability to resist more than 30% of broadband interference.

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Thermo-hydraulic research for supercritical water reactor during power-raising phase of startup 25

Thermo-hydraulic research for supercritical water reactor du...

引用

2017 25th International Conference on Nuclear Engineering, ICONE 2017

作者： Li, Zichao Zhou, Tao Lanyu, Zhou Liu, Liang Chen, Juan Hongxing, Yu Nuclear Safety and Thermal Power Standardization Institute North China Electric Power University Changping District Beijing China School of Nuclear Science and Technology University of South China Hengyang 421001 China Science and Technology on Reactor System Design Technology Laboratory Chengdu China

ISBN: (纸本)9780791857830

Thermal characteristics during startup of CSR1000 are directly related to the security of supercritical water reactors. The heat transfer model during power-raising phase is built according to the sliding pressure mode of CSR1000 and thermal characteristics of coolant and moderator are analyzed. The results show that, during the temperature-raising phase of startup, Coolant and moderator temperatures in inner assemblies increase with core power increase only. With increases of core power and feed-water flow rate, Coolant and moderator temperatures remain unchanged during powerraising phase. Thermal properties of the coolant change in the pseudo-critical temperature and the heat transfer deterioration occurs. © Copyright 2017 ASME.

关键词： Coolants

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Improvement and validation of free convection heat transfer model for tube bundle in RELAP5

Improvement and validation of free convection heat transfer ...

引用

2017 Transactions of the American Nuclear Society, ANS 2017

作者： Lin, Xian Guangming, Jiang Fan, Yang Feng, Li Xu, Ran Science and Technology on Reactor System Design Technology Laboratory 328# Changshun Avenue Chengdu Sichuan610213 China Nuclear Power Institute of China 328# Changshun Avenue Chengdu Sichuan610213 China

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Study of bottom reflooding in a narrow rectangular Channel 17

Study of bottom reflooding in a narrow rectangular Channel

引用

17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Xu, Wei Yao, Jun Liu, Xiaojing Cheng, Xu Zeng, Wei School of Nuclear Science and Engineering Shanghai Jiao Tong University 800 Dongchuan Road Minhang District Shanghai China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Cheng Du610041 China

For the purpose of figuring out the thermal-hydraulic behaviors during bottom reflooding in the narrow rectangular channel of plate-type fuel reactor, experimental apparatus was established to simulate the bottom reflooding process, with different inlet velocities, initial surface temperatures. The narrow channel was formed between a heating plate made of stainless steel and a heat-proof glass. Thermo-couples (TCs) were fixed to measure the solid temperature in the vertical and horizontal directions, and a high-speed camera was used to record flow regime near the quench front. Based on experimental results, conclusion is drawn that rewetting velocity increases with the increasing inlet velocity and decreasing initial solid temperature. The rewetting temperature, which is strongly affected by the initial wall temperature, is almost independent of the inlet velocity. A new conception of ‘temperature variation velocity’ is put forward, and rewetting front and rewetting temperature can be obtained by this means. Moreover, an analytical model of rewetting velocity in narrow rectangular channel is discussed and proposed, and this proposed correlation can predict rewetting velocity in narrow rectangular channel more precisely. © 2016 Association for Computing Machinery Inc. All Rights Reserved.

关键词： Velocity

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