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arXiv 2024年

作者： Zhao, Wei Feng, Dan Tong, Wei Wei, Xueliang Wu, Bing The Wuhan National Laboratory for Optoelectronics Key Laboratory of Information Storage System Engineering Research Center of Data Storage Systems and Technology Ministry of Education of China School of Computer Science and Technology Huazhong University of Science and Technology China

Massive off-chip accesses in GPUs are the main performance bottleneck, and we divided these accesses into three types: (1) Write, (2) Data-Read, and (3) Read-Only. Besides, We find that many writes are duplicate, and the duplication can be inter-dup and intra-dup. While inter-dup means different memory blocks are identical, and intra-dup means all the 4B elements in a line are the same. In this work, we propose a cache-assisted GPU memory deduplication architecture named CMD to reduce the off-chip accesses via utilizing the data duplication in GPU applications. CMD includes three key design contributions which aim to reduce the three kinds of accesses: (1) A novel GPU memory deduplication architecture that removes the inter-dup and inter-dup lines. As for the inter-dup detection, we reduce the extra read requests caused by the traditional read-verify hash process. Besides, we design several techniques to manage duplicate blocks. (2) We propose a cache-assisted read scheme to reduce the reads to duplicate data. When an L2 cache miss wants to read the duplicate block, if the reference block has been fetched to L2 and it is clean, we can copy it to the L2 missed block without accessing off-chip DRAM. As for the reads to intra-dup data, CMD uses the on-chip metadata cache to get the data. (3) When a cache line is evicted, the clean sectors in the line are invalidated while the dirty sectors are written back. However, most read-only victims are re-referenced from DRAM more than twice. Therefore, we add a full-associate FIFO to accommodate the read-only (it is also clean) victims to reduce the re-reference counts. Experiments show that CMD can decrease the off-chip accesses by 31.01%, reduce the energy by 32.78% and improve performance by 37.79%. Besides, CMD can improve the performance of memory-intensive workloads by 50.18%. © 2024, CC BY-NC-ND.

关键词： Cache memory

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Experimental Investigation and Mathematical Modeling on the Roles of Suspension and Deposition for Pool Boiling of Nanofluids

SSRN

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SSRN 2023年

作者： Peng, Cheng Song, Youya Wu, Jiang Deng, Jian College of Energy and Mechanical Engineering Shanghai University of Electric Power Shanghai China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

The influence of deposited and suspended nanoparticles on pool boiling of Al2O3 nanofluids was examined through visualization approach in this paper. The deposited nanoparticles cause the wettability to progressively increase as the concentration of nanofluid increases. The findings in this study demonstrate that deposited and suspended nanoparticles increase the frequency of bubble detachment and the quantity of active nucleate sites in water at a mass concentration ranging from 0.001% to 0.005%. The bubble behavior prediction equation was then rectified based on the surface contact angle, and the error margin was found to be within ±12% by comparing the experimental data. Based on which, the predicted values of the bubble behavior parameters were substituted into a corrected equation for boiling heat transfer. By validating the experimental data, the error margin was found to be within ±25%. Additionally, it was discovered that the effect of deposited nanoparticles on boiling heat transfer is always dominant at the heat fluxes between 50 and 250 kW/m2. © 2023, The Authors. All rights reserved.

关键词： Nanoparticles

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Recent advancement of flow-induced piezoelectric vibration energy harvesting techniques:principles,structures,and nonlinear designs

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Applied Mathematics and Mechanics(English Edition) 2022年第7期43卷 959-978页

作者： Dongxing CAO Junru WANG Xiangying GUO S.K.LAI Yongjun SHEN Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing 100124China Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Structures Beijing 100124China School of Automation Beijing Information Science and Technology UniversityBeiing 100192China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina Hong Kong Branch of National Rail Transit Electrification and Automation Engineering Technology Research Center The Hong Kong Polytechnic UniversityKowloonHong KongChina State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Energy harvesting induced from flowing fluids(e.g.,air and water flows)is a well-known process,which can be regarded as a sustainable and renewable energy *** addition to traditional high-efficiency devices(e.g.,turbines and watermills),the micro-power extracting technologies based on the flow-induced vibration(FIV)effect have sparked great concerns by virtue of their prospective applications as a self-power source for the microelectronic devices in recent *** article aims to conduct a comprehensive review for the FIV working principle and their potential applications for energy ***,various classifications of the FIV effect for energy harvesting are briefly introduced,such as vortex-induced vibration(VIV),galloping,flutter,and wake-induced vibration(WIV).Next,the development of FIV energy harvesting techniques is reviewed to discuss the research works in the past three *** application of hybrid FIV energy harvesting techniques that can enhance the harvesting performance is also ***,the nonlinear designs of FIV-based energy harvesters are reported in this study,e.g.,multi-stability and limit-cycle oscillation(LCO)***,advanced FIV-based energy harvesting studies for fluid engineering applications are briefly ***,conclusions and future outlook are summarized.

关键词： vibration-driven energy harvesting flow-induced vibration(FIV) piezoelectric approach nonlinear design

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An Adaptive Sliding Mode Terminal Guidance Method

An Adaptive Sliding Mode Terminal Guidance Method

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2023 china Automation Congress, CAC 2023

作者： Zhu, Yichuan Yao, Na Fan, Hu Beijing Aerospace Automatic Control Institute National Key Laboratory of Science and Technology on Aerospace Intelligence Control Beijing China Beijing Aerospace Automatic Control Institute System Simulation Laboratory Beijing China The Third Representative Office of Air Force Equipment in Beijing Area Beijing China

ISBN: (纸本)9798350303759

This article designs a sliding mode terminal guidance law for high-speed targets by modifying the approach law. Firstly, the relative motion equation of the chaser and escaper is established;Then adjust the aircraft based on the changes in the distance of the chaser and escaper and approach speed, design a self adaptive approach law, and derive the guidance law. At the same time, prove the stability of the guidance system by constructing a Lyapunov function;Finally, simulation verification was conducted. The simulation results showed that the designed guidance law can achieve the encounter between the chaser and the escaper. By comparing it with proportional guidance under different operating conditions, it was verified that the method has higher adaptability to different operating conditions, thus verifying the effectiveness of the guidance law designed in this paper and providing certain reference value for further research. © 2023 IEEE.

关键词： Equations of motion

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Assessment of Coupled Effect of Steam Pipes on Seismic Analysis of reactor Coolant system

Assessment of Coupled Effect of Steam Pipes on Seismic Analy...

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作者： Lijuan Li Zhenyu Liu Hui Li Xianhui Ye Honglei Ai National Key Laboratory of Science and Technology on Reactor System Design Technology

reactor coolant system is connected with auxiliary pipes, surge pipes and steam pipes. In order to facilitate the dynamic analysis of reactor coolant system, it is necessary to decouple the pipes connected with the reactor coolant system. Although some international standards stipulating requirements for the decoupling of subsystems from the main system, in order to further explore the influence of decoupling steam pipes, the seismic response of reactor coolant system with or without steam pipes is simulated by using ANSYS program. Firstly, the modal analysis of reactor coolant system is carried out to analysis the influence of steam pipes on the resonant frequency of reactor system. Then, the standardized seismic dynamic analysis of reactor system with or without steam pipes is carried out. The nozzle load(inlet and outlet nozzle load of main device, such as reactor pressure vessel, steam generator, pump) and support load(of main device such as reactor pressure vessel, steam generator, pump) are output and compared. According to nozzle load and support load, it can be seen that the steam pipes have little influence on the seismic analysis of reactor coolant system, i.e. steam pipes can be decoupled in the seismic analysis of reactor coolant system.

关键词： reactor coolant system dynamic analysis seismic response decouple steam pipes

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MDSTC: A Dynamic Approach to Multi-Robot Coverage Path Planning

MDSTC: A Dynamic Approach to Multi-Robot Coverage Path Plann...

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International Conference on Control, Automation, Robotics and Vision (ICARCV)

作者： Weimin Mo Zhiyun Lin School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China Shenzhen Key Laboratory of Control Theory and Intelligent Systems Southern University of Science and Technology Shenzhen China Peng Cheng Laboratory Shenzhen China

ISBN: (数字)9798331518493

ISBN: (纸本)9798331518509

Maximizing the efficiency of multi-robot systems is one of the primary objectives in solving the multi-robot coverage path planning (mCPP) problem. During coverage tasks, unexpected imbalances in the multi-robot systems, such as changes in speed, can lead to suboptimal utilization of the system's capabilities, subsequently reducing the efficiency of task execution. In this paper, we developed a multi-robot dynamic spanning tree coverage (MDSTC) algorithm, an online area-division-based approach that adjusts region allocation among robots based on their coverage status through an exchange-based mechanism to enhance multi-robot system efficiency. To validate the effectiveness of the proposed algorithm, we conducted extensive numerical simulations. The results demonstrate that our algorithm achieves a superior solution in scenarios where robot efficiency remains balanced, closely matching the performance of state-of-the-art mCPP methods. Furthermore, when differences in efficiency arise among the robots during task execution, the proposed algorithm provides a dynamic solution that enhances overall coverage efficiency.

关键词： Automation Heuristic algorithms Numerical simulation Dynamic scheduling Path planning Multi-robot systems Resource management Robots

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Knowledge-driven material design platform based on the whole-process simulation and modeling

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International Journal of Modeling, Simulation, and Scientific Computing 2022年第2期13卷 1-15页

作者： Gongzhuang Peng Tie Li Xiang Zhai Wenzheng Liu Heming Zhang National Engineering Research Center for Advanced Rolling Technology University of Science and Technology Beijing Beijing 100083 P.R.China Shanghai Electro-Mechanical Engineering Institute Shanghai 201109 P.R.China State Key Laboratory of Intelligent Manufacturing System Technology Beijing Institute of Electronic System Engineering Beijing 100854 P.R.China Beijing Complex Product Advanced Manufacturing Engineering Research Center Beijing Simulation Center Beijing 100854P.R.China Science and Technology on Space System Simulation Laboratory Beijing Simulation Center Beijing 100854P.R.China National CIMS Engineering Research Center Tsinghua University Beijing 100084P.R.China

In order to realize the agility,collaboration and visualization of alloy material devel-opment process,a product development platform based on simulation and modeling technologies is established in this *** this platform,the whole-process simulation module builds multi-level simulation models based on metallurgical mechanisms from the production line level,the thermo-mechanical coupling field level and the microstructure evolution *** design knowledge management module represents the multi-source heterogeneous material design knowledge through ontology model,including customers’requirement knowledge,material component knowledge,process design knowledge and quality inspection knowledge,and utilizes the case-based reasoning approach to reuse the *** data-driven modeling module applies machine learning algorithms to mine the relationships between product mechanical properties,material components,and process parameters from historical samples,and utilizes multi-objective optimiza-tion algorithms to find the optimal combination of process *** of the developed platform in actual steel mills shows that the proposed method helps to improve the efficiency of product design process.

关键词： Product development knowledge-based engineering multi-scale simulation performance prediction model

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Load balancing strategy for wireless multi-hotspot networks based on improved NSGA-II algorithm

Load balancing strategy for wireless multi-hotspot networks ...

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2022 International Conference on Networking and Network Applications, NaNA 2022

作者： Yu, Han Zhan, Jie Libin, Jiao Han, Jun-Mei School of Physics and Electronic Science Hunan University of Science and Technology Xiangtan412001 China Science and Technology on Communication Networks Laboratory Shijiazhuang050081 China National Key Laboratory for Complex Systems Simulation Department of Systems General Design Institute of Systems Engineering Beijing100101 China

ISBN: (数字)9781665461313

ISBN: (纸本)9781665461313

IEEE 802.11 Wireless Local Area Network (WLAN) is a popular way for mobile devices to access the Internet. Operators and service providers often increase the density of wireless access points in order to provide users with better connections and user experience. As a result, WLAN users find themselves covered by multiple access points. In traditional wireless multi-hotspot networks most user terminals choose the access point with the strongest signal without considering the existing load on that access point, leading to severe congestion and load imbalance problems. This paper proposes an improved NSGA-II-based load balancing strategy for wireless multi-hotspot networks, which determines which hotspot should be associated with each user terminal by taking into account the current access point load, the received signal strength and the throughput size of the user terminal. The simulation results show that compared with the traditional strongest signal First (SSF) strategy, the proposed load balancing strategy can improve the network throughput by more than 30%. © 2022 IEEE.

关键词： IEEE Standards

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design of Pelton Turbine Test Stand in Plateau Environment 4

Design of Pelton Turbine Test Stand in Plateau Environment

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4th IAHR Asian Working Group Symposium on Hydraulic Machinery and systems

作者： Cai, Jinhan Zhou, Xuejun Luo, Hongying Wang, Zhengwei Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology China College of Mechanical Engineering Tianjin Sino-German University of Applied Science No. 2 Yashen Road Tianjin China College of Hydraulic and Civil Engineering Tibet Agricultural and Animal Husbandry University China Department of Energy and Power Engineering Tsinghua University China

In recent years, with the continuous development of china's hydropower projects, Pelton turbines are gradually being valued, and the focus of development has shifted from plain areas to plateau areas. Environmental impacts such as high altitude, water temperature, and high sediment content in the plateau area have caused serious interference to equipment that originally worked in a stable environment, for example, the failure of the cooperation between the parts of the turbine and the mutual seizure, the increased wear of the nozzle needle, the decrease of the flow rate and the water outlet speed of the nozzle, and the decrease of the air pressure in the plateau environment lead to the change of the flow state of the nozzle. In view of the above problems, this paper puts forward the design scheme of impulse turbine test-bed, using the method of changing specific speed to determine the basic parameters of impulse turbine unit, so as to eliminate the influence of plateau environment on the normal operation of turbine, obtain the efficiency condition of model experiment under low ambient pressure, and improve the operation efficiency and reliability of turbine unit. © 2024 Institute of Physics Publishing. All rights reserved.

关键词： Nozzles

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The application of Deep Reinforcement Learning in Coordinated Control of Nuclear reactors 4

The application of Deep Reinforcement Learning in Coordinate...

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2021 4th International Conference on Mechatronics and Computer technology Engineering, MCTE 2021

作者： Li, Jing Liu, Yanyang Qing, Xianguo Xiao, Kai Zhang, Ying Yang, Pengcheng Yang, Yue Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Engineering The University of Sydney Sydney2006 Australia

The nuclear reactor control system plays a crucial role in the operation of nuclear power plants. The coordinated control of power control and steam generator level control has become one of the most important control problems in these systems. In this paper, we propose a mathematical model of the coordinated control system, and then transform it into a reinforcement learning model and develop a deep reinforcement learning control algorithm so-called DDPG algorithm to solve the problem. Through simulation experiments, our proposed algorithm has shown an extremely remarkable control performance. © 2021 Institute of Physics Publishing. All rights reserved.

关键词： Steam generators

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