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Multiscale mechanics of noncovalent interface in graphene oxide layered nanocomposites

Theoretical & Applied Mechanics Letters 2022年第1期12卷 3-9页

作者： ZeZhou He YinBo Zhu HengAn Wu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei 230027China

Noncovalent interfaces play a vital role in inelastic deformation and toughening mechanisms in layered nanocomposites due to their dynamical recoverability. When interfacial engineering is applied to design layered nanocomposites, shear-lag analysis is usually implemented to evaluate the capability of interfacial loading transfer. Here, we introduce a multiscale shear-lag model that correlates macroscale mechanical properties with the molecular mechanisms to quantify the effects of interfacial configuration in graphene oxide(GO) layered nanocomposites. By investigating the mechanical responses of commensurate and incommensurate interfaces, we identify that the commensurate interface exhibits a pronounced size effect due to the nucleation and propagation of interfacial defects, whereas the incommensurate interface displays uniform deformation. Our predictions are further validated through large-scale molecular dynamics simulations for GO layered nanocomposites. This work demonstrates how size effects and interfacial configurations can be exploited to fabricate layered nanocomposites with superior mechanical properties despite relying on weak noncovalent interfaces.

关键词： Multiscale mechanics Noncovalent interface Commensurate and incommensurate Shear-lag model Layered nanocomposites

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On the Accuracy and Efficiency of the reactor Operation Digital Twin for Parameter Identification and State Estimation

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SSRN 2023年

作者： Hong, Lizhan Gong, Helin Ji, Hongjun Lu, Jialiang Li, Han Li, Qing Paris Elite Institute of Technology Shanghai Jiao Tong University Shanghai200240 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

Accurate and efficient online parameter identification and state estimation are crucial to leveraging Digital Twin simulations for optimizing the operation of near-carbon-free nuclear energy systems. In previous works, we have developed the idea of reactor Operation Digital Twin (RODT). However, non-differentiabilities and discontinuities arise when employing some machine learning based surrogate forward models, challenging traditional gradient-based inverse methods and their variants. This study investigates deterministic and metaheuristic algorithms and further develops hybrid algorithms to address such issues. An efficient modular RODT software framework is presented incorporating these methods into its post-evaluation module for comprehensive comparison. Methods are rigorously assessed based on convergence profiles, stability with respect to noise, and computational performance. Numerical results demonstrate that the hybrid KNNLHS algorithm delivers the optimal balance of accuracy and efficiency for real-time online applications. Meanwhile, algorithms like FSA, DE and ADE exhibit slower yet highly accurate performance. This work advances RODT methodologies to harness machine learning and systems modelling for improved reactor monitoring, systematic diagnosis of off-normal events, lifetime management strategies, etc. The developed modular software and novel optimization methods presented offer pathways to realize the full potential of RODT for transforming energy engineering practices. © 2023, The Authors. All rights reserved.

关键词： State estimation

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Hot Compression Mechanical Behavior of Solution Heat‑Treated and Pre‑aged Mg–Zn–Gd–Er Alloys

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Acta Metallurgica Sinica(English Letters) 2023年第3期36卷 469-485页

作者： Bo Che Liwei Lu Longfei Liu Yan Yang Wei Kang Jun Luo Zhiqiang Wu Yongfeng Qiu School of Materials Science and Engineering Hunan University of Science and TechnologyXiangtan 411201China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Hunan Provincial Key Laboratory of Vehicle Power and Transmission System Hunan Institute of EngineeringXiangtan 411104China Guiyang Aluminum Magnesium Design&Research Institute Co. LtdGuiyang 550081China School of Automation Central South UniversityChangsha 410083China

The mechanical behavior of solution heat-treated and pre-aged Mg–6Zn–1Gd–1Er alloys during hot compression(from 180 to 330℃)has been *** results showed that the flow stress curves of the pre-aged sample(PAS)intersected with that of the solution heat-treated sample(SHTS)during hot *** 180℃,when the true strain is 0.27 and 0.47,the PAS showed larger and smaller stress(210.80 MPa vs.207.58 MPa and 205.67 MPa vs.207.93 MPa)than the SHTS,*** phenomena were due to the stronger interaction of W phase and dislocations/twins under the strain of 0.27,while dynamic recrystallization softening occurred under the strain of *** the temperature increased to 330℃,the flow stress of PAS and SHTS showed an opposite trend to that of 180℃.Continuous dynamic recrystallization and particle stimulated nucleation based on slip operations are the main deformation mechanisms under 330℃.At the true strain is 0.33 and 0.53,the PAS has smaller and larger stress(61.32 MPa vs.63.69 MPa and 58.75 MPa vs.57.09 MPa)than the SHTS,*** increasing deformation resistance of dynamic precipitation improved the flow stress under smaller strain and dynamic recrystallization decreased the flow stress under high strain,which resulted the opposite phenomena of SHTS.

关键词： Mg-6Zn-1Gd-1Er alloy Mechanical behavior Precipitates Twin Dynamic recrystallization

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

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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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Neural Network-Based Terminal Sliding Mode Controller design for Manipulator systems 1

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UNIfied Conference of International Workshop on Defence Applications of Multi-Agent systems, DAMAS 2023, International Conference on Maintenance Engineering, IncoME-V 2023, International conference on the Efficiency and Performance Engineering Network, TEPEN 2023

作者： Qu, Lufeng Fan, Qiming Kang, Yang Yang, Jun 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 Tianjin300384 China School of Intelligent Manufacturing Tianjin Sino-German University of Applied Technology Tianjin300350 China School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (数字)9783031494130

ISBN: (纸本)9783031494123

In the context of nonlinear and uncertain manipulator systems, achieving fast and accurate desired trajectories for each joint of the manipulator is crucial. Our study aims to improve current control methods by combining sliding mode control and neural network techniques. Specifically, we leverage the neural networks’ approximation capabilities to estimate both the modeling error and external disturbance in our research. These estimates are then integrated into the synovial control as additional gains. This approach allows for the sliding mode controller’s switch gain to adapt to changing modeling error and external disturbance, thereby avoiding the vibration production typically associated with traditional sliding mode controllers. It can be observed from the simulation results that the combination of the proposed nonsingular terminal sliding mode controller and neural network achieves fast and precise tracking of desired trajectories. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024.

关键词： Sliding mode control

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A Simple Method to Measure the Contact Angle of Metal Droplets on Graphite

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Nanomanufacturing and Metrology 2023年第4期6卷 35-45页

作者： Bozhao Wu Yongping Kang Cai Lu Langquan Shui Wengen Ouyang Qi Peng Qiankun He Ze Liu Department of Engineering Mechanics School of Civil EngineeringWuhan UniversityWuhan 430072HubeiChina School of Civil Engineering Architecture and Environment Hubei University of TechnologyWuhan 430068HubeiChina System Design Institute of Hubei Areospace Technology Academy Wuhan 430040China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China

The determination of solid–liquid interfacial tension plays an important role in science and ***,we propose a simple method to directly measure the contact angle between metal droplets and a graphite substrate for the determination of metal–graphite interfacial *** proposed method involves the synthesis of micro-and nanosized metal droplets on graphite by arc *** to its small volume,the rapid cooling of the prepared metal droplets on the graphite substrate leads to the freezing of equilibrium contact confguration after *** observe that the measured contact angle between micro-and nanosized Au(or Ag)particles and the graphite substrate is almost size independent,even though the size of the particles synthesized herein is 1–3 orders of magnitude smaller than that studied in previous *** addition,the interfacial tensions of Au and Ag on the step edges(edge plane)of graphite are found to be larger than that on the(0001)plane(basal plane).The proposed method provides a simple approach to determine the solid–liquid interfacial tension and may be efective in the study of interface related science and technology.

关键词： Metal droplets Graphite/graphenes Contact angle Interfacial tension

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Evaluation of a Numerical Model for Predicting Flow and Heat Transfer in a Hexagonal Helical Cruciform Seven-Rods Bundle and Analysis of Rod Bundle Size Independence

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SSRN 2024年

作者： Jiang, Dianqiang Deng, Jian Zhang, Dalin Zhou, Xingguang Xiao, Changzhi Tian, Wenxi Qiu, Suizheng Su, Guanghui H. State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China China Institute of Atomic Energy Beijing611731 China

In this study, the accuracy and applicability of the numerical model are comprehensively evaluated based on the experimental data of a hexagonal helical cruciform (HC) seven-rods bundle. The STAR CCM+ is utilized as a tool to obtain predicted results of flow and heat transfer in different flow regions. The numerical results indicate that it is an improved method to set a negative heat flux on the hexagonal wall in the laminar flow region. The Reynolds stress transport model can accurately predict the experimental results of heat transfer in the transitional flow region, with an average wall temperature deviation of 2.8℃. The SST k-ω model with cubic constitutive option can accurately predict the experimental results of the flow resistance, and a relative error of f is 1.8%. In the turbulent flow region, the SST k-ω model with cubic constitutive option provides an accurate prediction, with an average wall temperature deviation of 3.7℃. The realizable k-Ε two-layer model can accurately predict the flow resistance, and the relative error of f is 0.1%. The preferred numerical model is used to analyze the size independence of the HC rod bundle. This work provides certain guidelines for the accurate simulation in the HC seven-rods bundle. © 2024, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Nonreciprocity of energy transfer in a nonlinear asymmetric oscillator system with various vibration states

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Applied Mathematics and Mechanics(English Edition) 2023年第5期44卷 727-744页

作者： Jian’en CHEN Jianling LI Minghui YAO Jun LIU Jianhua ZHANG Min SUN Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin 300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of TechnologyTianjin 300384China School of Aeronautics and Astronautics Tiangong UniversityTianjin 300387China Agricultural Information Institute of Chinese Academy of Agricultural Sciences Key Laboratory of Agricultural Big DataMinistry of Agriculture and Rural AffairsBeijing 100081China School of Science Tianjin Chengjian UniversityTianjin 300384China

The nonreciprocity of energy transfer is constructed in a nonlinear asymmetric oscillator system that comprises two nonlinear oscillators with different parameters placed between two identical linear *** slow-flow equation of the system is derived by the complexification-averaging *** semi-analytical solutions to this equation are obtained by the least squares method,which are compared with the numerical solutions obtained by the Runge-Kutta *** distribution of the average energy in the system is studied under periodic and chaotic vibration states,and the energy transfer along two opposite directions is *** effect of the excitation amplitude on the nonreciprocity of the system producing the periodic responses is analyzed,where a three-stage energy transfer phenomenon is *** the first stage,the energy transfer along the two opposite directions is approximately equal,whereas in the second stage,the asymmetric energy transfer is *** energy transfer is also asymmetric in the third stage,but the direction is reversed compared with the second ***,the excitation amplitude for exciting the bifurcation also shows an asymmetric *** vibrations are generated around the resonant frequency,irrespective of which linear oscillator is *** excitation threshold of these chaotic vibrations is dependent on the linear oscillator that is being *** addition,the difference between the energy transfer in the two opposite directions is used to further analyze the nonreciprocity in the *** results show that the nonreciprocity significantly depends on the excitation frequency and the excitation amplitude.

关键词： nonreciprocity strong nonlinearity energy transfer chaotic vibration higher branch of response

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The Shortest Path Algorithm Based on Geometric Symmetry for Low Earth Orbit Satellite Network

The Shortest Path Algorithm Based on Geometric Symmetry for ...

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Information Communication Technologies Conference (ICTC)

作者： Benchu Zhang Zaiyue Yang School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China Shenzhen Key Laboratory of Control Theory and Intelligent Systems and the School of System Design and Intelligent Manufacturing Southern University of Science and Technology Shenzhen China

ISBN: (数字)9798350373523

ISBN: (纸本)9798350373530

Since the Low Earth Orbit (LEO) satellite communication system has the advantages of low latency, global coverage, and rapid reconstruction, it has become the main networking method of satellite networks [1]. Routing is the basis for realizing satellite communications. Because the complexity of the shortest path algorithm basically determines the computational complexity of the routing algorithm, the shortest path algorithm is the core of the routing problem. This paper attempts to use the laws of LEO satellite network topology to calculate the shortest path between the source satellite and the destination satellite. First, we derive the function of inter-satellite link (ISL) length with time and establish the geometric model of the satellite network. Then, on the basis of this model, we establish the shortest path algorithm between source-destination pairs (SD pairs) - the symmetric geometry algorithm (SGA). In addition, in order to ensure the optimality of the path, we extend the applicable scene of the model from the two-dimensional plane to the three-dimensional sphere. The simulation test results show that compared with the traditional Dijkstra’s algorithm, SGA can greatly improve the calculation speed of the shortest path while ensuring the optimality of the path.

关键词： Geometry Solid modeling Satellites Network topology Geometric modeling Low earth orbit satellites Routing

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