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Multi-blade rubbing characteristics of the shaft-disk-blade-casing system with large rotation

Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 111-136页

作者： Zhiyuan WU Linchuan ZHAO Han YAN ge YAN Ao CHEN Wenming ZHANG State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Institute of Aerospace Systems Engineering Shanghai 201108China

Blade rubbing faults cause detrimental impact on the operation of aeroengines. Most of the existing studies on blade rubbing in the shaft-disk-blade-casing(SDBC) system have overlooked the elastic deformation of the blade, while some only consider the whirl of the rotor, neglecting its spin. To address these limitations, this paper proposes a dynamic model with large rotation for the SDBC system. The model incorporates the spin and whirl of the rotor, enabling the realistic reproduction of multiblade rubbing faults. To verify the accuracy of the SDBC model with large rotation and demonstrate its capability to effectively consider the rotational effects such as the centrifugal stiffening and gyroscopic effects, the natural characteristics and dynamic responses of the proposed model are compared with those obtained from reported research and experimental results. Furthermore, the effects of the rotating speed, contact stiffness,and blade number on the dynamic characteristics of the SDBC system with multi-blade rubbing are investigated. The results indicate that the phase angle between the rotor deflection and the unbalance excitation force increases with the increasing rotating speed,which significantly influences the rubbing penetration of each blade. The natural frequency of the SDBC system with rubbing constrain can be observed in the acceleration response of the casing and the torsional response of the shaft, and the frequency is related to the contact stiffness. Moreover, the vibration amplitude increases significantly with the product of the blade number under rubbing, and the rotating frequency approaches the natural frequency of the SDBC system. The proposed model can provide valuable insight for the fault diagnosis of rubbing in bladed rotating machinery.

关键词： shaft-disk-blade-casing(SDBC) large rotation spin and whirl multi-blade rubbing rotational effect

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Stability and accuracy of central difference method for real-time dynamic substructure testing considering mass participation coefficient

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 625-636页

作者： Zheng Lichang Xu Guoshan Yang ge Wang Zhen Yang Kaibo Zheng Zhenyun School of Civil Engineering Harbin Institute of TechnologyHarbin 150090China Key Lab of Structures Dynamic Behavior and Control Ministry of EducationHarbin Institute of TechnologyHarbin 150090China Key Lab of Intelligent Disaster Mitigation Ministry of Industry and Information TechnologyHarbin 150090China School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan 430070China

For real-time dynamic substructure testing(RTDST),the influence of the inertia force of fluid specimens on the stability and accuracy of the integration algorithms has never been ***,this study proposes to investigate the stability and accuracy of the central difference method(CDM)for RTDST considering the specimen mass participation ***,the theory of the CDM for RTDST is ***,the stability and accuracy of the CDM for RTDST considering the specimen mass participation coefficient are ***,numerical simulations and experimental tests are conducted for verifying the effectiveness of the *** study indicates that the stability of the algorithm is affected by the mass participation coefficient of the specimen,and the stability limit first increases and then decreases as the mass participation coefficient *** most cases,the mass participation coefficient will increase the stability limit of the algorithm,but in specific circumstances,the algorithm may lose its *** stability and accuracy of the CDM considering the mass participation coefficient are verified by numerical simulations and experimental tests on a three-story frame structure with a tuned liquid damper.

关键词： real-time dynamic substructure testing central difference method stability mass participation coefficient tuned liquid damper

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Stochastic Gradient Compression for Federated Learning over Wireless Network

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China Communications 2024年第4期21卷 230-247页

作者： Lin Xiaohan Liu Yuan Chen Fangjiong Huang Yang ge Xiaohu School of Electronic and Information Engineering South China University of TechnologyGuangzhou 510641China Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China School of Electronic Information and Communications Huazhong University of Science and TechnologyWuhan 430074China

As a mature distributed machine learning paradigm,federated learning enables wireless edge devices to collaboratively train a shared AI-model by stochastic gradient descent(SGD).However,devices need to upload high-dimensional stochastic gradients to edge server in training,which cause severe communication *** address this problem,we compress the communication by sparsifying and quantizing the stochastic gradients of edge *** first derive a closed form of the communication compression in terms of sparsification and quantization ***,the convergence rate of this communicationcompressed system is analyzed and several insights are ***,we formulate and deal with the quantization resource allocation problem for the goal of minimizing the convergence upper bound,under the constraint of multiple-access channel *** show that the proposed scheme outperforms the benchmarks.

关键词： federated learning gradient compression quantization resource allocation stochastic gradient descent(SGD)

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Influence of ambient temperature on the CO_(2)emitted of light-duty vehicle

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Journal of Environmental Sciences 2024年第6期140卷 59-68页

作者： Dan Tan Yachao Wang Jianwei Tan Jiachen Li Changyu Wang Yunshan ge School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

Because of global warming,people have paid more attention to greenhouse gas emitted by *** quantify the impact of temperature on vehicle CO_(2)emissions,this study was conducted using the world light vehicle test cycle on two light-duty E10 gasoline vehicles a ambient temperatures of-10,0,23,and 40℃,and found that CO_(2)emission factors of Vehicle1 in the low-speed phase were 22.07%and 20.22%higher than those of Vehicle 2 at cold star and hot start under-10℃.The reason was vehicle 1 had a larger displacement and more friction pairs than vehicle *** was the highest CO_(2)emission at the low-speed phase due to low average speed,frequent acceleration,and *** CO_(2)temperature factor and the ambient temperature had a strong linear correlation(R2=0.99).According to CO_(2)temperature factors and their relationships,CO_(2)emission factors of other ambien temperatures could be calculated when the CO_(2)emission factor of 23℃was obtained,and the method also could be used to obtain the CO_(2)temperature factors of different *** separate the effect of load setting and temperature variation on CO_(2)emission quantitatively a method was *** results showed that the load setting was dominant for the CO_(2)emission *** with 23℃,the CO_(2)emission for vehicle 1 caused by load setting variation were 62.83 and 47.42 g/km,respectively at-10 and 0℃,while those fo vehicle 2 were 45.01 and 35.63 g/km,respectively.

关键词： CO_(2)emission Ambient temperature E10 gasoline Light-duty vehicle WLTC

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Quick Hosting Capacity Evaluation Based on Distributed Dispatching for Smart Distribution Network Planning with Distributed generation

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 128-140页

作者： Bing Sun Ruipeng Jing Leijiao ge Yuan Zeng Shimeng Dong Luyang Hou the School of Electrical and Information Engineering Tianjin UniversityTianjin 300072China State Grid Corporation of China BeijingChina the School of Computer Science(National Pilot Software Engineering School) Beijing University of Posts and TelecommunicationsBeijingChina

The smart distribution network(SDN)is integrat ing increasing distributed generation(DG)and energy storage(ES).Hosting capacity evaluation is important for SDN plan ning with *** and ES are usually invested by users or a third party,and they may form friendly microgrids(MGs)and operate *** centralized dispatching meth od no longer suits for hosting capacity evaluation of SDN.A quick hosting capacity evaluation method based on distributed optimal dispatching is ***,a multi-objective DG hosting capacity evaluation model is established,and the host ing capacity for DG is determined by the optimal DG planning *** steady-state security region method is applied to speed up the solving process of the DG hosting capacity evalua tion ***,the optimal dispatching models are estab lished for MG and SDN respectively to realize the operating *** the distributed dispatching strategy,the dual-side optimal operation of SDN-MGs can be realized by several iterations of power exchange ***,an SDN with four MGs is conducted considering multiple flexible *** shows that the DG hosting capacity of SDN oversteps the sum of the maximum active power demand and the rated branch ***,the annual DG electricity oversteps the maximum active power demand value.

关键词： Smart distribution network(SDN) microgrid hosting capacity multi-objective optimization distributed opti mal dispatching flexible resource

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Multiplicity of solutions for the semilinear subelliptic Dirichlet problem

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Science China Mathematics 2024年第3期67卷 475-504页

作者： Hua Chen Hong-ge Chen Jin-Ning Li Xin Liao School of Mathematics and Statistics Wuhan UniversityWuhan 430072China Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China

In this paper,we study the semilinear subelliptic equation{−△Xu=f(x,u)+g(x,u)inΩ,u=0 on∂Ω,where△X=−∑m i=1 Xi∗Xi is the self-adjoint Hormander operator associated with the vector fields X=(X_(1),X_(2),...,X_(m))satisfying the Hormander's condition,f(x,u)∈C(Ω×R),g(x,u)is a Carathéodory function onΩ×R,andΩis an open bounded domain in R~n with smooth *** the perturbation from the symmetry method with the approaches involving the eigenvalue estimate and the Morse index in estimating the minimax values,we obtain two kinds of existence results for multiple weak solutions to the problem ***,we discuss the difference between the eigenvalue estimate approach and the Morse index approach in degenerate *** with the classical elliptic cases,both approaches here have their own strengths in the degenerate *** new phenomenon implies that the results in general degenerate cases would be quite different from the situations in classical elliptic cases.

关键词： degenerate elliptic equations Hormander operators perturbation method Morse index

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A hybrid data-mining framework for train rescheduling strategy pattern discovery

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Transportation Safety and Environment 2024年第1期6卷 56-67页

作者： Ruirui Chen Xuekai ge Ping Huang Chao Wen School of Transportation&Logistics Southwest Jiaotong UniversityChengdu 611756China Department of IT Operational Technology CN RailWaterloo N2V2R1Canada

This study presents a hybrid data-mining framework based on feature selection algorithms and clustering methods to perform the pattern discovery of high-speed railway train rescheduling strategies(RSs).The proposed model is composed of two *** the first state,decision tree,random forest,gradient boosting decision tree(GBDT)and extreme gradient boosting(XGBoost)models are used to investigate the importance of *** features that have a high influence on RSs are first *** the second state,a K-means clustering method is used to uncover the interdependences between RSs and the influencing features,based on the results in the first *** proposed method can determine the quantitative relationships between RSs and influencing *** results clearly show the influences of the factors on RSs,the possibilities of different train operation RSs under different situations,as well as some key time periods and key trains that the controllers should pay more attention *** research in this paper can help train traffic controllers better understand the train operation patterns and provides direction for optimizing rail traffic RSs.

关键词： high-speed railway rescheduling strategy pattern discovery feature identification clustering algorithm

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The dynamics of traveling wavefronts for a model describing host tissue degradation by bacteria

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International Journal of Biomathematics 2024年第3期17卷 265-287页

作者： Xing-Xing Yang Guo-Bao Zhang ge Tian College of Mathematics and Statistics Northwest Normal University Lanzhou Gansu 730070P.R.China

In this paper,we mainly investigate the dynamics of traveling wavefronts for a model describing host tissue degradation by *** first establish the existence of spreading speed,and show that the spreading speed coincides with the minimal wave speed of traveling ***,a lower bound estimate of the spreading speed is ***,we prove that the traveling wavefronts with large speeds are globally exponentially stable,when the initial perturbation around the traveling wavefronts decays exponentially asχ→-∞,but the initial perturbation can be arbitrarily large in other *** adopted methods are the weighted energy and the squeezing technique.

关键词： Host tissue degradation bacterial infection traveling wavefronts minimal wave speed stability

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Cross-diffusion induced Turing instability of Hopf bifurcating periodic solutions in the reaction-diffusion enzyme reaction model

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International Journal of Biomathematics 2024年第4期17卷 133-150页

作者： Haicheng Liu Wenshuo Yuan Bin ge Jihong Shen College of Mathematical Sciences Harbin Engineering University Harbin 150001 HeilongjiangP.R.China

Aiming at the spatial pattern phenomenon in biochemical reactions,an enzyme-reaction Sporns-Seelig model with cross-diffusion is chosen as study *** the central manifold theory,normal form method,local Hopf bifurcation theorem and perturbation theory,we study Turing instability of the spatially homogeneous Hopf bifurcation periodic *** last,the theoretical results are verified by numerical simulations.

关键词： Sporns-Seelig model diffusion Hopf bifurcation periodic solutions Turing instability

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Cross-species transmission and host range genes in poxviruses

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Virologica Sinica 2024年第2期39卷 177-193页

作者： Chen-Hui Yang A-Ling Song Ye Qiu Xing-Yi ge College of Biology Hunan Provincial Key Laboratory of Medical VirologyHunan UniversityChangsha410012China

The persistent epidemic of human mpox, caused by mpox virus (MPXV), raises concerns about the future spread ofMPXV and other poxviruses. MPXV is a typical zoonotic virus which can infect human and cause smallpox-likesymptoms. MPXV belongs to the Poxviridae family, which has a relatively broad host range from arthropods tovertebrates. Cross-species transmission of poxviruses among different hosts has been frequently reported andresulted in numerous epidemics. Poxviruses have a complex linear double-strand DNA genome that encodeshundreds of proteins. genes related to the host range of poxvirus are called host range genes (HRGs). This reviewbriefly introduces the taxonomy, phylogeny and hosts of poxviruses, and then comprehensively summarizes thecurrent knowledge about the cross-species transmission of poxviruses. In particular, the HRGs of poxvirus aredescribed and their impacts on viral host range are discussed in depth. We hope that this review will provide acomprehensive perspective about the current progress of researches on cross-species transmission and HRGvariation of poxviruses, serving as a valuable reference for academic studies and disease control in the future.

关键词： Poxvirus Host range gene(HRG) Host spectrum Cross-species transmission

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