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Research Square 2021年

作者： Li, Shuangbao Wang, Tingting Chen, Jianen Research Institute of Science and Technology Innovation Civil Aviation University of China Tianjin300300 China College of Science Civil Aviation University of China Tianjin300300 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

A new highly efficient elastic-impact bistable nonlinear energy sink (EI-BNES) based on magnetic-elastic impacts with negative stiffness and bistability is proposed and optimized through global dynamical analysis. The EI-BNES has better robustness and higher energy dissipation rates with nearly more than 96.5% for broadband impulsive excitations than the traditional cubic NESs and single bistable NESs. The structure of negative stiffness impacts is realized by reasonable layout of permanent ring magnets and springs. A two-degree-of-freedom (two-DOF) elastic-impact system is established to describe the coupled nonlinear interaction between the main structure and the attached EI-BNES. A global Melnikov reduction analysis (GMRA) is proposed to study global dynamics and homoclinic bifurcations of the reduced two-dimensional subsystem, which is used to explain the mechanism of nonlinear targeted energy transfer (TET) and detect the threshold of impulsive amplitudes of EI-BNES for in-well and compound motions between in-well and cross-well resonance responses. A special type of saddle-center equilibrium points is also found in the non-smooth system of the EI-BNES and can be used to effectively increase the energy dissipation rates. The optimal design criterion of the tuned EI-BNES for better dissipation performance is also first discussed based on the GMRA and numerical techniques for calculating the Melnikov function of the non-smooth systems. The effectiveness of the analytical GMRA is also verified by numerical simulations. © 2021, CC BY.

关键词： Stiffness

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Limit load estimation for finite plates with semi-elliptical defects under tensile loading

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Journal of Physics: Conference Series 2021年第1期1777卷

作者： K K Shi X L Fu H Xie X J Shao J Tian Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan China

The ASME code allows the designer to circumvent many of the problems arising in design by elastic analysis by performing plastic or limit analysis of the component. Unlike elastic analysis, these analyses take account of the redistribution of stress upon yield. In limit analysis, the calculation of the limit load for finite plate with different semi-elliptical defects is an important stage for mechanical safety evaluation. The elastic compensation technique proposed by Mackenzie can be used to provide the limit load of a structure with a finite element method and aims at producing a suitable stress filed for the lower bound theory. In the present study, it is assumed that the finite plate exists three kinds of semi-elliptical cracks with low aspect ratio a/c (a/c=0.1, 0.5 and 1.0), respectively. The improved elastic compensation technique realized by finite element method is applied in the limit load estimation. At last, the results show that the improved elastic compensation technique can be used to obtain the limit value for the finite plate with different semi-elliptical defects under tensile loading. Moreover, the improved elastic compensation technique can be easily implemented in any finite element method and enables the limit load for any complex structure to be obtained swiftly.

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Comparisons of Subgrid-Scale Models for OpenFoam Large- Eddy Simulation

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Journal of Physics: Conference Series 2021年第4期1802卷

作者： Zhipeng Feng Huanhuan Qi Xuan Huang Shuai Liu Jian Liu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan China

OpenFOAM is a free, open-source software package that can be used for the solutions of computational fluid dynamics and simulation of various fluid flow processes. Nevertheless, OpenFOAM still lacks default settings and a large number of different numerical schemes and turbulent models should be validated. In this paper, the unsteady flow around a cylinder (Re=3900) is calculated by the large eddy simulation of OpenFOAM. The predictions include the drag and lift coefficient, the pressure distribution around the cylinder, the velocity distribution and Reynolds stress distribution in the wake region, as well as the prediction of the recirculation length and separation angle. Thanks to several simulations, these five subgrid-scale (SGS) models are compared and studied: The Smagorinsky SGS model, wall adaptive local eddy visibility SGS model, dynamic SGS model with Lagrangian averaging, dynamic one equation eddy visibility model, one equation eddy visibility model. The numerical results are verified with the published experimental data.

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Increasingly important role of numerical modeling in oceanic observation design strategy: A review

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science China Earth sciences 2020年第11期63卷 1678-1690页

作者： Kun ZHANG Mu MU Qiang WANG CAS Key Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of Sciences and Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China Department of Atmospheric and Oceanic Sciences and Institute of Atmospheric Sciences Fudan UniversityShanghai 200438China CMA-FDU Joint Laboratory of Marine Meteorology Shanghai 200438China Innovation Center of Ocean and Atmosphere System Zhuhai Fudan Innovation Research InstituteZhuhai 518057China Key Laboratory of Marine Hazards Forecasting Ministry of Natural ResourcesHohai UniversityNanjing 210098China College of Oceanography Hohai UniversityNanjing 210098China

Oceanic observation design is of considerable significance and has made remarkable progress during the past several *** study addresses the critical role of numerical modeling in oceanic observation *** a brief introduction of the characteristics of existing oceanic observation design studies,we present the advantages of the model-based observation design strategy and further review its decisive *** demonstrate the effectiveness of this strategy,the targeted observation applications using the conditional nonlinear optimal perturbation(CNOP)approach for improving the Kuroshio predictions are ***,the authors present their consideration for correcting model errors by targeted observations of sensitive model parameters and mitigating the model-dependency problem by utilizing multiple modeling *** on using observing system simulation experiments to validate the designed observations and extending the model-based observation design strategy into observing oceanic climatological mean states are also discussed.

关键词： Observation design Numerical modeling Targeted observation CNOP

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Non-Equilibrium Solidification Complexions in Additive Manufacturing Enable Exceptional Creep Resistance: An Example in Nickel-Based Superalloys

SSRN

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SSRN 2024年

作者： Li, Yansong Cui, Luqing Xu, Jinghao Xin, Tongzheng Jiang, Shuang Li, Yao Zhang, Honghong Dang, Xiaofeng Liang, Xiaoqing Gao, Shuang Mu, Yahang Lu, Kaiju Moverare, Johan J. He, Weifeng Shaanxi Xi’an710049 China School of Mechanical Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Division of Engineering Materials Department of Management and Engineering Linköping University LinköpingSE-58183 Sweden School of Materials Science and Engineering Dalian University of Technology Dalian116024 China Key Laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang110819 China School of Materials Science and Engineering Chang’an University Shaanxi Xi’an710064 China School of Mechanical Engineering Xi’an Shiyou University Shaanxi Xi’an710065 China National Key Lab of Aerospace Power System and Plasma Technology Air Force Engineering University Shaanxi Xi’an710038 China School of Material Engineering Shanghai University of Engineering Science Shanghai201620 China Shenyang110016 China Defense Innovation Institute Academy of Military Science Beijing100071 China

Insufficient time-dependent properties at elevated temperatures, particularly creep resistance and ductility, are currently crucial factors impeding the use of additively manufactured Hastelloy X (HX). To address this limitation, a micro-nano olive-shaped carbide network was purposely introduced into HX via laser powder bed fusion (L-PBF) and following optimized heat treatment. The inherent chemical heterogeneity combined with the sufficient stored energy of boundaries, induced by the ultrafast cooling rate of the L-PBF process, creates favorable conditions for the formation of micro-nano precipitation networks. Compared to its untreated counterpart, the optimized HX exhibited considerably improved creep resistance, with an 83% increase in creep life and a 122% improvement in fracture ductility. Furthermore, through multiscale characterization techniques and theoretical calculations, the preferential precipitation behavior of the micro-nano carbide networks was systematically investigated from both kinetic and thermodynamic perspectives. The superior creep resistance of the L-PBF HX, decorated with carbide networks, stems from the synergistic effects of the higher cavity surface energy, greater pinning force for grain boundary sliding, and lower plasticity-assisted diffusion rate, which markedly inhibit the nucleation and growth of microvoids during high-temperature deformations. This work provides a comprehensive understanding of the strengthening mechanisms associated with non-equilibrium solidification-facilitated carbide networks, providing new insights into the targeted design and optimization of L-PBF alloys. © 2024, The Authors. All rights reserved.

关键词： Creep resistance

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Multi-level forwarding and scheduling recovery algorithm in rapidly-changing network for erasure-coded clusters

arXiv

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arXiv 2020年

作者： Zhou, Hai Feng, Dan Hu, Yuchong Wuhan National Laboratory for Optoelectronics Key Laboratory of Information Storage System Huazhong University of Science and Technology Ministry of Education of China Wuhan430074 China Wuhan National Laboratory for Optoelectronics Key Laboratory of Information Storage System School of Computer Science and Technology Huazhong University of Science and Technology Ministry of Education of China Wuhan430074 China

A key design goal of erasure-coded clusters is to reduce the repair time. The existing Erasure-coded data repair schemes are roughly classified into two categories: 1. designing rapid data repair (e.g., PPR) in a homogeneous environment. 2. Constructing data repair (e.g., PPT) based on bandwidth in a heterogeneous environment. However, these solutions are difficult to cope with the heterogeneous and Rapidly-changing network in erasure-coded clusters. To address this problem, a bandwidth-aware multi-level forwarding repair algorithm, called BMFRepair, is proposed. BMFRepair monitors the network bandwidth in real time when data is forwarded, and selects idle nodes with high-bandwidth links to assist in forwarding. Thus, it can reduce the time bottleneck caused by low link transmission. At the same time, multi-node repair becomes very complicated when the bandwidth changes drastically. A multi-node scheduling repairing algorithm, called MSRepair, is proposed for multi-node repairing problems, which can repair multiple failed blocks in parallel by scheduling node resources. The two algorithms can flexibly adapt to the rapidly changing network environment and make full use of the bandwidth resources of idle nodes. Most importantly, algorithms can continuously adjust the repair plan according to the bandwidth change in fast and dynamic network. The algorithms have been evaluated by both simulations on Mininet and real experiments on Aliyun cloud platform ECS. Results show that compared with the state-of-the-art repair schemes PPR and PPT, the algorithms can significantly reduce the repair time in rapidly-changing network. Copyright © 2020, The Authors. All rights reserved.

关键词： Heterogeneous networks

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Finite Element Analysis of Series Elastic Actuator for Exoskeleton Robot Joint 17

Finite Element Analysis of Series Elastic Actuator for Exosk...

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17th IEEE International Conference on Mechatronics and Automation, ICMA 2020

作者： Xi, Pengyu Ge, Weimin Zhang, Sen Zhang, Zhili Zielinska, Teresa Tianjin University of Technology Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin300384 China Tianjin Sino-German University of Applied Science Intelligent Manufacturing College Tianjin300384 China Institute of Aeronautics and Applied Mechanics Warsaw University of Technology Warsaw00665 Poland

ISBN: (纸本)9781728164151

The finite element simulation for the joints of an exoskeleton robot is conducted in this paper. Using software OpenSim to simulate the normal walking gait of the human body, the motion angle and moment of the human hip, knee and ankle joints are obtained. Using the obtained data as the input parameters in the finite element simulation of the simulation software Ls-dyna, the strain diagrams and contact force curves of the circular roller and cam disk were obtained. In this study, three commonly used materials are selected: alloy steel, ductile iron and hard aluminum alloy. Finally, the effects of different materials on the key components of the series elastic actuator are studied. © 2020 IEEE.

关键词： Finite element method

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Experimental study on corrugated plate dryer in steam generator under hot working conditions

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iscience 2025年第6期28卷

作者： Ru Li Bo Wang Gongqing Wang Xuan Ye Hanliang Bo Ruifeng Tian Xiong Wei Institute of Nuclear and New Energy Technology of Tsinghua University Collaborative Innovation Center of Advanced Nuclear Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Beijing 100084 China College of Nuclear Science and Technology Harbin Engineering University Harbin Heilongjiang 150001 China Wuhan Second Ship Design and Research Institute Wuhan Hubei 430205 China

In advanced pressurized water reactors, the corrugated plate dryer (CPD) is essential for ensuring the safety and efficiency of nuclear power plants by influencing steam quality in the separation system of steam generators. While previous research has focused on cold-condition experiments, this study addresses the complexities of hot operational conditions, which are more representative of real-world scenarios. By investigating the effects of CPD structural parameters on separation performance, the research establishes an experimental platform that reveals a critical plate spacing where the CPD’s critical velocity (CV) peaks. Additionally, the study explores the internal gas flow dynamics, demonstrating that increased recirculation along the plate walls significantly impacts flow velocity. These findings contribute to a deeper understanding of CPD performance under realistic conditions, enhancing the reliability and efficiency of nuclear power generation.

关键词： Heat transfer Mechanical engineering Computational mechanics

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FedPHE: A Secure and Efficient Federated Learning via Packed Homomorphic Encryption

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IEEE Transactions on Dependable and Secure Computing 2025年

作者： Li, Yuqing Yan, Nan Chen, Jing Wang, Xiong Hong, Jianan He, Kun Wang, Wei Li, Bo Wuhan University Key Laboratory of Aerospace Information Security and Trusted Computing Ministry of Education School of Cyber Science and Engineering Wuhan430072 China Wuhan University RiZhao Information Technology Institute Rizhao276800 China Huazhong University of Science and Technology National Engineering Research Center for Big Data Technology and System Services Computing Technology and System Lab/Cluster and Grid Computing Lab School of Computer Science and Technology Wuhan430074 China Shanghai Jiao Tong University School of Cyber Science and Engineering Shanghai200240 China Hong Kong University of Science and Technology Department of Computer Science and Engineering Hong Kong

Cross-silo federated learning (FL) enables multiple institutions (clients) to collaboratively build a global model without sharing private data. To prevent privacy leakage during aggregation, homomorphic encryption (HE) is widely used to encrypt model updates, yet incurs high computation and communication overheads. To reduce these overheads, packed HE (PHE) has been proposed to encrypt multiple plaintexts into a single ciphertext. However, the original design of PHE assumes all clients share a single private key, making the system vulnerable to security threats of ciphertexts being intercepted and decrypted by honest-but-curious clients. Also, it does not consider the heterogeneity among different clients, resulting in undermined training efficiency with slow convergence and stragglers. To address these challenges, we propose FedPHE, a secure and efficient FL framework with PHE by jointly exploiting contribution-aware secure aggregation and straggler-resistant client selection. Using CKKS with sparsification and blinding, FedPHE achieves efficient secure aggregation that allows clients to only provide obscured encrypted updates while the server can perform aggregation by accounting for contributions of local updates. To mitigate the straggler effect, we devise a perturbed sketch-based selection to cherry-pick representative clients with heterogeneous models and computing capabilities in a communication-efficient and privacy-preserving manner. We show, through rigorous security analysis and extensive experiments, that FedPHE can efficiently safeguard clients' privacy, achieve 2.45-6.56× training speedup, cut the communication overhead by 1.32-24.85×, and reduce straggler effects by 1.89-2.78×. © 2004-2012 IEEE.

关键词： Privacy by design

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Comprehensive duck DNA fingerprinting based on machine learning for breed identification

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Poultry science 2025年第8期104卷 105359页

作者： DengKe Yan Feng Zhu HaoLin Wang ZhongTao Yin ZhuoCheng Hou National Engineering Laboratory for Animal Breeding Key Laboratory of Animal Genetics Breeding and Reproduction of the Ministry of Agriculture College of Animal Science and Technology China Agricultural University Beijing 100193 PR China. Frontiers Science Center for Molecular Design Breeding (MOE) China Agricultural University Beijing 100193 PR China National Engineering Laboratory for Animal Breeding Key Laboratory of Animal Genetics Breeding and Reproduction of the Ministry of Agriculture College of Animal Science and Technology China Agricultural University Beijing 100193 PR China. Electronic address: yinzhongtao@***. National Engineering Laboratory for Animal Breeding Key Laboratory of Animal Genetics Breeding and Reproduction of the Ministry of Agriculture College of Animal Science and Technology China Agricultural University Beijing 100193 PR China. Electronic address: zchou@***.

Duck is one of the most widely distributed waterfowl in the world, with more than 6 billion of them farmed annually in the world, and has great economic and ecological value. Amidst mounting global prioritization of duck genetic resource exploration and prevalent inter-varietal hybridization events, the traditional breed identification methods are difficult to address actual requirements, restricting the utilization, development and protection of duck germplasm resources. This study aims to develop an accurate, efficient, and scalable duck DNA fingerprinting system based on genomic technologies and machine learning methods to address the urgent need for breed identification tools in high-quality agricultural production and ecological protection. Our study aims to construct a global duck DNA fingerprint map based on genomic data and machine learning algorithm, develop an accurate, efficient and scalable duck DNA fingerprinting identification tool, and solve the urgent need for breed identification tools for high-quality agricultural production and ecological protection. In this study, we obtained the whole genome resequencing data of 196 duck individuals from 16 breeds and constructed a high-density duck population variation dataset containing 2,360,039 SNPs. Four characteristic molecular marker selection methods (Delta, Average Euclidean Distance (AED), Polymorphism Information Content (PIC), and Fixation Index (F)) and four machine learning classification algorithms (Random Forest (RF), Support Vector Machine (SVM), Linear Discriminant Analysis (LDA), and Naive Bayes (NB)) were tested. The results showed that AED indicator had the best performance in selecting SNP markers in ducks, and the classification accuracy was the highest (98.38 %) when 2000 SNP sites were selected. SVM algorithm showed the best classification performance in ducks, with the classification accuracy of 98.71 % and the running time was within 70 seconds. We constructed the duck DNA fingerprinti

关键词： Breed assignment DNA fingerprinting Machine learning SNP selection

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