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Snap-through behaviors and nonlinear vibrations of a bistable composite laminated cantilever shell:an experimental and numerical study

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 779-794页

作者： Lele ren Wei ZHANG Ting DONG Yufei ZHANG State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Department of Mechanics Guangxi UniversityNanning 530004China Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Structures College of Mechanical EngineeringBeijing University of TechnologyBeijing 100124China School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

The snap-through behaviors and nonlinear vibrations are investigated for a bistable composite laminated cantilever shell subjected to transversal foundation excitation based on experimental and theoretical *** improved experimental specimen is designed in order to satisfy the cantilever support boundary condition,which is composed of an asymmetric region and a symmetric *** symmetric region of the experimental specimen is entirely clamped,which is rigidly connected to an electromagnetic shaker,while the asymmetric region remains free of *** motion paths are realized for the bistable cantilever shell by changing the input signal levels of the electromagnetic shaker,and the displacement responses of the shell are collected by the laser displacement *** numerical simulation is conducted based on the established theoretical model of the bistable composite laminated cantilever shell,and an off-axis three-dimensional dynamic snap-through domain is *** numerical solutions are in good agreement with the experimental *** nonlinear stiffness characteristics,dynamic snap-through domain,and chaos and bifurcation behaviors of the shell are quantitatively *** to the asymmetry of the boundary condition and the shell,the upper stable-state of the shell exhibits an obvious soft spring stiffness characteristic,and the lower stable-state shows a linear stiffness characteristic of the shell.

关键词： bistable composite laminated cantilever shell snap-through behavior nonlinear vibration nonlinear stiffness characteristic chaos and bifurcation

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Preparation of K-doped g-C_(3)N_(4) composite loaded on magnetic attapulgite and its degradation performance for malachite green

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Chinese Journal of Chemical Engineering 2024年第7期71卷 110-121页

作者： Aishun Ma Hanlin Qian Hongxia Liu Sili ren Jiangxi Key Laboratory of Mining&Metallurgy Environmental Pollution Control Jiangxi University of Science and TechnologyGanzhou 341000China Jiangxi Provincial Key Laboratory of Low-Carbon Processing and Utilization of Strategic Metal Mineral Resources Jiangxi University of Science and TechnologyGanzhou 341000China

Visible-light-driven photocatalysis is a promising technology for the treatment of dye *** this work,a novel photocatalyst of K-doped g-C_(3)N_(4) loaded on magnetic attapulgite(ATP)(Kω-g-C_(3)N_(4)@ATP-Fe_(3)O_(4))with excellent visible light photocatalytic properties and stability were successfully prepared and *** removal efficiency of Kω-g-C_(3)N_(4)@ATP-Fe_(3)O_(4) for malachite green(MG)was studied,and the degradation mechanism was analyzed and *** was found that the K_(5)-g-C_(3)N_(4)@ATP-Fe_(3)O_(4) photocatalyst possessed excellent degradation efficiency of over 98.0%for the MG dye wastewater under optimal ***,the K_(5)-g-C_(3)N_(4)@ATP-Fe_(3)O_(4) materials possessed good recyclability with a removal rate over 82%after 4 *** visible light condition,the K_(5)-g-C_(3)N_(4)@ATP-Fe_(3)O_(4) photocatalyst produce radicals of·OH and O_(2)^(-)to degrade the MG dyes,which was supported by electron paramagnetic resonance(EPR)and radical trapping *** addition,the LC-MS analysis interpreted the degradation pathways and intermediates of MG in the *** findings in this work indicate that the prepared photocatalytic material has excellent degradation efficiency for MG and can be applied in dye wastewater treatment.

关键词： Photocatalyst Malachite green K-doped g-C_(3)N_(4) Degradation

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Fault diagnosis of HVAC system with imbalanced data using multi-scale convolution composite neural network

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Building Simulation 2024年第3期17卷 371-386页

作者： Rouhui Wu Yizhu ren Mengying Tan Lei Nie School of Mechanical Engineering Hubei University of TechnologyWuhan430068China Industrial Research Institute of Xiangyang Hubei University of Technology Xiangyang441100China

Accurate fault diagnosis of heating,ventilation,and air conditioning(HVAC)systems is of significant importance for maintaining normal operation,reducing energy consumption,and minimizing maintenance ***,in practical applications,it is challenging to obtain sufficient fault data for HVAC systems,leading to imbalanced data,where the number of fault samples is much smaller than that of normal ***,most existing HVAC system fault diagnosis methods heavily rely on balanced training sets to achieve high fault diagnosis ***,to address this issue,a composite neural network fault diagnosis model is proposed,which combines SMOTETomek,multi-scale one-dimensional convolutional neural networks(M1DCNN),and support vector machine(SVM).This method first utilizes SMOTETomek to augment the minority class samples in the imbalanced dataset,achieving a balanced number of faulty and normal ***,it employs the M1DCNN model to extract feature information from the augmented ***,it replaces the original Softmax classifier with an SVM classifier for classification,thus enhancing the fault diagnosis *** the SMOTETomek-M1DCNN-SVM method,we conducted fault diagnosis validation on both the ASHRAE RP-1043 dataset and experimental dataset with an imbalance ratio of 1:*** results demonstrate the superiority of this approach,providing a novel and promising solution for intelligent building management,with accuracy and F1 scores of 98.45%and 100%for the RP-1043 dataset and experimental dataset,respectively.

关键词： fault diagnosis chiller imbalanced data SMOTETomek multi-scale neural networks

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Conceptual design and control method for a noncontact annular electromagnetic stabilized satellite platform

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Chinese Journal of Aeronautics 2024年第1期37卷 256-270页

作者： He LIAO Daixin WANG Yuan ren Weijie WANG Institute of Astronautics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Department of Basic Course Space Engineering UniversityHuairou DistrictBeijing 101416China

Disturbance-Free Payload(DFP)spacecraft can meet the requirements of ultra-high attitude pointing accuracy and stability for future space ***,as the main control actuators of DFP spacecraft,Linear Non-Contact Lorentz Actuators(LNCLAs)have control output problems with six-degree-of-freedom coupling and nonlinear effects,which will affect the attitude control performance of DFP *** solve this problem,a novel concept for Non-Contact Annular Electromagnetic Stabilized Satellite Platform(NCAESSP)is proposed in this *** concept is centered on replacing the LNCLAs with a non-contact annular electromagnetic actuator to solve the two problems mentioned ***,for the different control requirements of the payload module and the support module of the NCAESSP,a high-precision attitude controller based on the robust model matching method and a dual quaternion-based adaptive sliding mode controller are ***,the simulation results verify the feasibility and effectiveness of the proposed approach.

关键词： Disturbance-free payload Robust model matching Dual quaternion Sliding mode control Collision avoidance

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Maximizing conditional independence for unsupervised domain adaptation

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Science China(Information Sciences) 2024年第5期67卷 136-149页

作者： Yiming ZHAI Chuanxian ren Youwei LUO Daoqing DAI School of Mathematics Sun Yat-Sen University

Unsupervised domain adaptation(UDA) studies how to transfer a learner from a labeled source domain to an unlabeled target domain with different distributions. Existing methods mainly focus on matching marginal distributions of the source and target domains, which probably leads to a misalignment of samples from the same class but different domains. In this paper, we tackle this misalignment issue by achieving the class-conditioned transferring from a new perspective. Specifically, we propose a method named maximizing conditional independence(MCI) for UDA, which maximizes the conditional independence of feature and domain given class in the reproducing kernel Hilbert spaces. The optimization of conditional independence can be viewed as a surrogate for minimizing class-wise mutual information between feature and domain. An interpretable empirical estimation of the conditional dependence measure is deduced and connected with the unconditional case. Besides, we provide an upper bound on the target error by taking the class-conditional distribution into account, which provides a new theoretical insight for class-conditioned transferring. Extensive experiments on six benchmark datasets and various ablation studies validate the effectiveness of the proposed model in dealing with UDA.

关键词： conditional independence kernel method domain adaptation class-conditioned transferring

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Exogeneous metal ions as therapeutic agents in cardiovascular disease and their delivery strategies

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Regenerative Biomaterials 2024年第2期3卷 1-16页

作者： Xiaoqian Hong Geer Tian Yang Zhu Tanchen ren Department of Cardiology of the Second Affliated Hospital and State Key Laboratory of Transvascular Implantation Devices Cardiovascular Key Laboratory of Zhejiang ProvinceZhejiang University School of MedicineHangzhou 310o09China Binjiang Institute of Zhejiang University Hangzhou 310053China MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China

Metal ions participate in many metabolic processes in the human body,and their homeostasis is crucial for *** cardiovascular diseases(CVDs),the equilibriums of metal ions are frequently interrupted,which are related to a variety of disturbances of physiological processes leading to abnormal cardiac *** supplement of metal ions has the potential to work as therapeutic strategies for the treatment of *** with other therapeutic drugs,metal ions possess broad availability,good stability and safety and diverse drug delivery *** delivery strategies of metal ions are important to exert their ther-apeutic effects and reduce the potential toxic side effects for cardiovascular applications,which are also receiving increasing *** local delivery strategies for metal ions based on various biomaterials are constantly being *** this review,we comprehensively summarized the positive roles of metal ions in the treatment of cVDs from three aspects:protecting cells from oxidative stress,inducing angiogenesis,and adjusting the functions of ion *** addition,we introduced the transferability of metal ions in vascular reconstruction and cardiac tissue repair,as well as the currently available engineered strategies for the precise delivery of metal ions,such as integrated with nanoparticles,hydrogels and scaffolds.

关键词： metal ions cardiovascular disease tissue engineering oxidative stress angiogenesis ion channel

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MEMS Huygens Clock Based on Synchronized Micromechanical Resonators

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Engineering 2024年第5期36卷 124-131页

作者： Xueyong Wei Mingke Xu Qiqi Yang Liu Xu a Yonghong Qi Ziming ren Juan ren Ronghua Huan Zhuangde Jiang State Key Laboratory for Manufacturing System Engineering Xi’an Jiaotong UniversityXi’an 710049China School of Construction Machinery Chang’an UniversityXi’an 710064China Department of Mechanics Zhejiang UniversityHangzhou 310027China

With the continuous miniaturization of electronic devices,microelectromechanical system(MEMS)oscillators that can be combined with integrated circuits have attracted increasing *** study reports a MEMS Huygens clock based on the synchronization principle,comprising two synchronized MEMS oscillators and a frequency compensation *** MEMS Huygens clock improved shorttime stability,improving the Allan deviation by a factor of 3.73 from 19.3 to 5.17 ppb at 1 s.A frequency compensation system based on the MEMS oscillator’s temperature-frequency characteristics was developed to compensate for the frequency shift of the MEMS Huygens clock by controlling the resonator *** effectively improved the long-term stability of the oscillator,with the Allan deviation improving by 1.6343105 times to 30.9 ppt at 6000 *** power consumption for compensating both oscillators simultaneously is only 2.85 mW·℃^(-1).Our comprehensive solution scheme provides a novel and precise engineering solution for achieving high-precision MEMS oscillators and extends synchronization applications in MEMS.

关键词： Frequency stability Huygens clock MEMS Oscillator Synchronization

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Effects of projectile parameters on the momentum transfer and projectile melting during hypervelocity impact

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Defence Technology（防务技术） 2024年第2期32卷 89-103页

作者： Wenjin Liu Qingming Zhang renrong Long Zizheng Gong ren Jiankang Xin Hu Siyuan ren Qiang Wu Guangming Song State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China Beijing Institute of Spacecraft Environment Engineering China Academy of Space TechnologyBeijing100094China

The effects of projectile/target impedance matching and projectile shape on energy,momentum transfer and projectile melting during collisions are investigated by numerical *** comparing the computation results with the experimental results,the correctness of the calculation and the statistical method of momentum transfer coefficient is *** shapes of aluminum,copper and heavy tungsten alloy projectiles striking aluminum,basalt,and pumice target for impacts up to 10 km/s are *** influence mechanism of the shape of the projectile and projectile/target density on the momentum transfer was *** an increase in projectile density and length-diameter ratio,the energy transfer time between the projectile and targets is *** projectile decelerates slowly,resulting in a larger cratering *** energy consumed by the projectile in the excavation stage increased,resulting in lower mass-velocity of ejecta and momentum transfer *** numerical simulation results demonstrated that for different projectile/target combinations,the higher the wave impedance of the projectile,the higher the initial phase transition velocity and the smaller the mass of phase *** results can provide theoretical guidance for kinetic impactor design and material selection.

关键词： Hypervelocity impact Energy partitioning Impact melting Momentum transfer

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Design,Testing and Control of a Magnetorheological Damper for Knee Prostheses

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Journal of Bionic Engineering 2024年第4期21卷 1788-1800页

作者： Hounan Song Yu Cao Wei Chen Lei ren Yongxin Ma Kunyang Wang Xu Wang Yao Zhang Luquan ren Key Laboratory of Bionic Engineering Ministry of EducationJilin UniversityChangchun130022People’s Republic of China Department of Mechanical Aerospace and Civil EngineeringThe University of ManchesterManchesterM139PLUK

This study aims to develop a magnetorheological(MR)damper for semi-active knee prostheses to restore the walking ability of transfemoral *** core dimensions of the MR damper were determined via theoretical magnetic field calculations,and the theoretical relationship between current and joint torque was derived through electromagnetic ***,a physical prototype of the semi-active prosthetic knee equipped with the MR damper was *** on the data obtained from angle sensor,pressure sensor(loadcell),and inertial measurement unit(IMU)on the prosthesis,a matching control algorithm is *** joint torque of the MR damper can be adaptively adjusted according to the walking speed of the amputee,allowing the amputee to realize a natural *** effectiveness of the control program was verified by the ADAMS and MATLAB *** results of the test and simulation show that the MR damper can provide sufficient torque needed for normal human activities.

关键词： Semi-active knee prosthesis Magnetorheological damper Theoretical analysis ADAMS and MATLAB co-simulation

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Performance Prediction Based Workload Scheduling in Co-Located Cluster

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 2043-2067页

作者： Dongyang Ou Yongjian ren Congfeng Jiang School of Computer Science and Technology Hangzhou Dianzi UniversityHangzhou310018China

Cloud service providers generally co-locate online services and batch jobs onto the same computer cluster,where the resources can be pooled in order to maximize data center resource *** to resource competition between batch jobs and online services,co-location frequently impairs the performance of online *** study presents a quality of service(QoS)prediction-based schedulingmodel(QPSM)for *** performance prediction of QPSM consists of two parts:the prediction of an online service’s QoS anomaly based on XGBoost and the prediction of the completion time of an offline batch job based on ***-line service QoS anomaly prediction is used to evaluate the influence of batch jobmix on on-line service performance,and batch job completion time prediction is utilized to reduce the total waiting time of batch *** the same number of batch jobs are scheduled in experiments using typical test sets such as CloudSuite,the scheduling time required by QPSM is reduced by about 6 h on average compared with the first-come,first-served strategy and by about 11 h compared with the random scheduling *** with the non-co-located situation,QPSM can improve CPU resource utilization by 12.15% and memory resource utilization by 5.7% on *** show that the QPSM scheduling strategy proposed in this study can effectively guarantee the quality of online services and further improve cluster resource utilization.

关键词： Co-located cluster workload scheduling online service batch jobs data center

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