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Analytic derivation of Monin-Obukhov similarity function for open atmospheric surface layer

Science China(Physics,Mechanics & Astronomy) 2021年第3期64卷 73-83页

作者： Yong Ji Zhen-Su She State Key Laboratory for Turbulence and Complex Systems and Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing100871China

The Monin-Obukhov(MO)similarity functionφm of the atmospheric surface layer(ASL)describing the deviation from the log law of the canonical turbulent boundary layer because of thermal stratification has been traditionally determined *** study presents a unified analytic expression derived from a symmetry-based theory of wall turbulence,called structural ensemble dynamics(SED),which postulates a generalized dilation symmetry principle expressing the effect of the wall on turbulence,leading to an analytic multi-regimes expression for the mixing *** ASL in unstable and stable conditions(i.e.,UC and SC),a unified two-regime formula of the mixing length is proposed,leading to aφm,similar to the Businger-Dyer(BD)formula;with a simplified model energy balance equation,φm is completely specified with no free ***,the theory allows the study of the open ASL’s underlying additional physical processes such as bottom-up or top-down flux due to pressure variations *** that Tp is decomposed into shear-like and buoyancy-like components,we propose new explanations for two important features of typical ASL:a significantly smaller Karman constant of 0.36 and a varyingφm for SC mean speed *** theory is validated by the data obtained at Kansas and also at Qingtu Lake Observation Array in Northern China for a variety of heat flux *** conclusion,due to pressure variations,we assert that ASL is intrinsically open and that the current theory offers a new basis for its quantification.

关键词： Monin-Obukhov similarity theory open atmospheric surface layer boundary layer turbulence symmetry-based analysis

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Multiple AMR Rigid Formation Control With Collision Avoidance Based On MADDPG 41

Multiple AMR Rigid Formation Control With Collision Avoidanc...

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第41届中国控制会议

作者： Kaiqi Wu Qing Wang YongBao Wu Jian Liu Lei Xue The College of Software Engineering Southeast University SEU-Monash Joint Graduate school Southeast University School of Automation Southeast UniversityKey Laboratory of Measurement and Control of Complex Systems of EngineeringMinistry of Education

ISBN: (数字)9789887581536

ISBN: (纸本)9781665482561

Recently,the formation control of multiple autonomous mobile robots(AMRs) have gained significant attention,and autonomous mobile robots(AMRs) have applied to all aspects of our ***-agent reinforcement learning is used to solve the autonomously sequential decision-making problem of agents in a common environment with competition or ***,we present a utility function and a reward function to achieve formation control with collision avoidance for a rigid AMRs system,and build a simulation environment to meet environmental requirements based on MPE.

关键词： Formation control Reinforcement learning Rigid system Collision avoidance

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DMGA: A Directional-Mutation Genetic Algorithm for CDMS Problem of Kafka 21

DMGA: A Directional-Mutation Genetic Algorithm for CDMS Prob...

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21st International Conference on Networking, Sensing and Control, ICNSC 2024

作者： Ma, Hanbo Ma, Yaofei Yuan, Haitao Wang, Meijia Hu, Jingwei Wang, Yihuan Yang, Hanbo School of Automation Science and Electrical Engineering Beihang University Beijing100191 China Beijing Simulation Center National Key Laboratory of Modeling and Simulation for Complex Systems Beijing China

ISBN: (纸本)9798350365221

With the increasing role of distributed message systems (DMS) represented by Kafka in handling large-scale data streams, it is critical to improve system performance by optimizing configuration parameters in different production environments. Due to the target system possessing numerous configuration parameters and the complex interactions between them, parameter optimization becomes a complex and time-consuming process that relies heavily on human effort and an iterative trial-and-error approach. At present, this type of configuration parameter problem has been classified as the Configuration of Distributed Message systems (CDMS) problem, for which the goal is to obtain the optimal set of parameters for achieving the best performance. In order to deal with this complex problem, an automatic optimization method is proposed in this paper, which combines an automatic script-based deployment and running framework with an improved Genetic Algorithm (GA) in cooperation with the Random Forest (RF) and statistical methods, named the Directional-Mutation Genetic Algorithm (DMGA). The framework and algorithm are designed to find the best configuration efficiently, obtaining optimal parameters accurately without human supervision. Actual results of comparison experiments based on the Kafka system show that the DMGA algorithm significantly improves the data throughput performance of Kafka, and its optimization speed is more efficient than the basic GA, highlighting its potential to quickly optimize Kafka's operational efficiency in different scenarios. © 2024 IEEE.

关键词： Genetic algorithms

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Instability-Induced Origami Design by Topology Optimization

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Acta Mechanica Solida Sinica 2023年第4期36卷 506-513页

作者： Weiwei Wang Ke Liu Meiqi Wu Hongyuan Li Pengyu Lv Huiling Duan State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering ScienceBIC-ESATCollege of EngineeringPeking UniversityBeijing 100871China Department of Advanced Manufacturing and Robotics College of EngineeringPeking UniversityBeijing 100871China CAPT HEDPS and IFSACollaborative Innovation Center of MoEPeking UniversityBeijing 100871China

Instability-induced wrinkle patterns of thin sheets are ubiquitous in nature,which often result in origami-like patterns that provide inspiration for the engineering of origami *** by instability-induced origami patterns,we propose a computational origami design method based on the nonlinear analysis of loaded thin sheets and topology *** bar-and-hinge model is employed for the nonlinear structural analysis,added with a displacement perturbation strategy to initiate out-of-plane *** ideas from topology optimization,a continuous crease indicator is introduced as the design variable to indicate the state of a crease,which is penalized by power functions to establish the mapping relationships between the crease indicator and hinge *** the structural strain energy with a crease length constraint,we are able to evolve a thin sheet into an origami structure with an optimized crease *** examples with different initial setups are illustrated,demonstrating the effectiveness and feasibility of the method.

关键词： Origami structure Instability Topology optimization Bar-and-hinge model

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Apollonius Partitions Based Pursuit-evasion Game Strategies by Q-Learning Approach 41

Apollonius Partitions Based Pursuit-evasion Game Strategies ...

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第41届中国控制会议

作者： Qing Wang KaiQi Wu JianFeng Ye YongBao Wu Lei Xue SEU-Monash Joint Graduate school Southeast University The College of Software Engineering Southeast University School of Automation Southeast UniversityKey Laboratory of Measurement and Control of Complex Systems of EngineeringMinistry of Education

ISBN: (数字)9789887581536

ISBN: (纸本)9781665482561

This paper studies a classical single pursuer and single evader pursuit-evasion *** pursuer attempts to capture the slower evader who aims to extend its lifetime during the *** simplify this question,requiring the evader to take fixation strategy which is choosing the farthest point in its current dominant region as aimpoint and moving at a constant *** the pursuer is faster than the ***,the speed ratio is a *** instaneous state space will be partitioned into pursuer's dominant zone and evader's dominant zone by the generalized Apollonius *** pursuit strategy is based on minimizing the area of the evader's dominant ***,we propose a supermodular game for this ***,the existence of the Nash equilibrium is *** results based on Q-learning are presented to solve the problem,which shows the effectiveness of this method.

关键词： Pursuit-evasion game Nash equilibrium Q-learning

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Optimized Hybrid Control for Attitude Adjustment of Downhole Directional Drilling Tools 50

Optimized Hybrid Control for Attitude Adjustment of Downhole...

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50th Annual Conference of the IEEE Industrial Electronics Society, IECON 2024

作者： Xiao, Jing Wang, She Cai, Zhen School of Information Engineering Wuhan City Polytechnic University Wuhan430064 China Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems Wuhan430074 China

ISBN: (纸本)9781665464543

This study delves into the critical role of attitude control in downhole directional drilling tools, focusing on the complex coupling between inclination and azimuth in the motion model, particularly the time-varying nature of azimuth adjustments. By implementing separate control strategies for inclination and azimuth, the research integrates a comprehensive hybrid control system. It rigorously examines the stability of the closed-loop systems and validates the effectiveness and applicability of the hybrid control method through extensive simulations. The system demonstrates significant robustness and adaptability, enhancing drilling precision and efficiency. © 2024 IEEE.

关键词： State feedback

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Position Tracking Control for PMSM System Based on Continuous Sliding Mode Control and Sliding Mode Observer 41

Position Tracking Control for PMSM System Based on Continuou...

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第41届中国控制会议

作者： Qian Wan Huiming Wang Xia Sun Chongqing Key Laboratory of Complex Systems and Bionic Control Chongqing University of Posts and Telecommunications Chongqing Institute of Engineering

ISBN: (数字)9789887581536

ISBN: (纸本)9781665482561

In this article,a robust finite-time control strategy using continuous terminal sliding mode control(CTSMC) and sliding mode observer(SMO) is proposed to solve the problem of position tracking of permanent magnet synchronous motor(PMSM) servo *** control performance of such a system is always affected by internal and external *** this reason,a continuous sliding mode control(CSMC) method with fast convergence and strong anti-disturbance is firstly ***,considering that the disturbance of the actual system is generally in various forms and time-varying,to further improve the disturbance rejection ability of the system,an SMO based CTSMC method is proposed,where the SMO is devised to estimate time-varying disturbances and the estimations are employed to the position controller through feedforward compensation for disturbance *** present control method can not only improve the tracking rate,but also enhance the disturbance suppression ability of the *** with the PD control,CSMC,and CTSMC,simulation results demonstrate that the proposed control method can achieve the promised control performance for the studied system.

关键词： Continuous terminal sliding mode(CTSM) sliding mode observer(SMO) position control permanent magnet synchronous motor(PMSM)

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Optimization of Wide-Baseline Stereo Matching Based on Multi-view Geometry

Optimization of Wide-Baseline Stereo Matching Based on Multi...

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2024 China Automation Congress, CAC 2024

作者： Xu, Yinhui Shan, Shuo Han, Gongben Fang, Shixiong Zhang, Kanjian Wei, Haikun Key Laboratory of Measurement and Control of Complex Systems of Engineering Ministry of Education School of Automation Southeast University Nanjing China Shenzhen Research Institute Southeast University Shenzhen China

ISBN: (纸本)9798350368604

Stereo vision plays a crucial role in scientific expeditions and facility maintenance. However, fixed-baseline stereo vision lacks accuracy for long-distance measurements, while wide-baseline stereo vision encounters occlusion issues at short distances. In this study, a wide-baseline stereo matching based on multi-view geometric constraints is proposed. Initially, the camera poses of multiple wide-baseline images are estimated, followed by image rectification and depth estimation. Subsequently, the disparity searching is constrained using geometric relationships among the views, resulting in more precise depth maps. Experiments were conducted to verify the superiority of the proposed method. The results indicate that the proposed method achieves an RMSE as low as 0.15 meters, even with invalid depth points. Compared to traditional stereo vision methods, accuracy is improved by approximately 35%, and robustness is significantly enhanced. In the aircraft runway scenario, overall depth map accuracy is higher, and occluded areas are significantly reduced. © 2024 IEEE.

关键词： Stereo vision

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Universality class of machine learning for critical phenomena

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Science China(Physics,Mechanics & Astronomy) 2023年第12期66卷 63-70页

作者： Gaoke Hu Yu Sun Teng Liu Yongwen Zhang Maoxin Liu Jingfang Fan Wei Chen Xiaosong Chen School of Systems Science and Institute of Nonequilibrium Systems Beijing Normal UniversityBeijing 100875China Data Science Research Center Faculty of ScienceKunming University of Science and TechnologyKunming 650500China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Herein,percolation phase transitions on a two-dimensional lattice were studied using machine learning *** reveal that different phase transitions belonging to the same universality class can be identified using the same neural networks(NNs),whereas phase transitions of different universality classes require different *** on this finding,we proposed the universality class of machine learning for critical ***,we investigated and discussed the NNs of different universality *** research contributes to machine learning by relating the NNs with the universality class.

关键词： universality class machine learning percolation

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Tetris-Style Stacking Process to Tailor the Orientation of Carbon Fiber Scaffolds for Efficient Heat Dissipation

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Nano-Micro Letters 2023年第9期15卷 310-324页

作者： Shida Han Yuan Ji Qi Zhang Hong Wu Shaoyun Guo Jianhui Qiu Fengshun Zhang The State Key Laboratory of Polymer Materials Engineering Sichuan Provincial Engineering Laboratory of Plastic/Rubber Complex Processing TechnologyPolymer Research Institute of Sichuan UniversityChengdu 610065People’s Republic of China Department of Mechanical Engineering Faculty of Systems Science and TechnologyAkita Prefectural University015-0055AkitaJapan Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621900People’s Republic of China

As the miniaturization of electronic devices and complication of electronic packaging,there are growing demands for thermal interfacial materials with enhanced thermal conductivity and the capability to direct the heat toward heat sink for highly efficient heat ***-based carbon fiber(CF)with ultrahigh axial thermal conductivity and aspect ratios exhibits great potential for developing thermally conductive composites as ***,it is still hard to fabricate composites with aligned carbon fiber in a general approach to fully utilize its excellent axial thermal conductivity in specific ***,three types of CF scaffolds with different oriented structure were developed via magnetic field-assisted Tetris-style stacking and carbonization *** regulating the magnetic field direction and initial stacking density,the self-supporting CF scaffolds with horizontally aligned(HCS),diagonally aligned and vertically aligned(VCS)fibers were *** embedding the polydimethylsiloxane(PDMS),the three composites exhibited unique heat transfer properties,and the HCS/PDMS and VCS/PDMS composites presented a high thermal conductivity of 42.18 and 45.01 W m^(−1)K^(−1)in fiber alignment direction,respectively,which were about 209 and 224 times higher than that of *** excellent thermal conductivity is mainly ascribed that the oriented CF scaffolds construct effective phonon transport pathway in the *** addition,fishbone-shaped CF scaffold was also produced by multiple stacking and carbonization process,and the prepared composites exhibited a controlled heat transfer path,which can allow more versatility in the design of thermal management system.

关键词： Carbon fiber Magnetic field Thermal management Thermally conductive composites

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