检索结果-南通市图书馆

Trust-region based instantaneous optimal semi-active control of long-span spatially extended structures with MRF-04K damper

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2008年第4期7卷 447-464页

作者： lin wei Li Zhongxian Ding Yang School of Civil Engineering Tianjin University Tianjin 300072 China Tianjin Key Laboratory of Civil Engineering Structures and New Materials Tianjin 300072 China

In the field of civil engineering, magnetorheological fluid （MRF） damper-based semi-active control systems have received considerable attention for use in protecting structures from natural hazards such as strong earthquakes and high winds. In this paper, the MRF damper-based semi-active control system is applied to a long-span spatially extended structure and its feasibility is discussed. Meanwhile, a _trust-region method based instantaneous optimal semi-active control algorithm （TIOC） is proposed to improve the performance of the semi-active control system in a multiple damper situation. The proposed TIOC describes the control process as a bounded constraint optimization problem, in which an optimal semi- active control force vector is solved by the trust-region method in every control step to minimize the structural responses. A numerical example of a railway station roof structure installed with MRF-04K dampers is presented. First, a modified Bouc- Wen model is utilized to describe the behavior of the selected MRF-04K damper. Then, two semi-active control systems, including the well-known clipped-optimal controller and the proposed TIOC controller, are considered. Based on the characteristics of the long-span spatially extended structure, the performance of the control system is evaluated under uniform earthquake excitation and travelling-wave excitation with different apparent velocities. The simulation results indicate that the MR fluid damper-based semi-active control systems have the potential to mitigate the responses of full-scale long-span spatially extended structures under earthquake hazards. The superiority of the proposed TIOC controller is demonstrated by comparing its control effectiveness with the clipped-optimal controller for several different cases.

关键词： long-span spatially extended structure instantaneous optimal control semi-active control trust-regionmethod magnetorheological (MR) damper bounded constraint optimization modified Bouc-Wen model clipped-optimal control

Dynamic Flow Control Strategies of Vehicle SCR Urea Dosing System

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2015年第2期28卷 276-284页

作者： lin wei ZHANG Youtong ASIF Malik Laboratory of Clean Vehicles Beijing Institute of Technology

Selective Catalyst Reduction（SCR）Urea Dosing System（UDS）directly affects the system accuracy and the dynamic response performance of a ***,the UDS dynamic response is hard to keep up with the changes of the engine＇s operating *** will lead to low NO_χconversion efficiency or NH_3 *** order to optimize the injection accuracy and the response speed of the UDS in dynamic conditions,an advanced control strategy based on an air-assisted volumetric UDS is *** covers the methods of flow compensation and switching working *** strategy is authenticated on an UDS and tested in different dynamic *** result shows that the control strategy discussed results in higher dynamic accuracy and faster dynamic response speed of *** inject deviation range is improved from being between-8%and 10%to-4%and 2%and became more stable than before,and the dynamic response time was shortened from 200 ms to 150 *** ETC cycle result shows that after using the new strategy the NH_3 emission is reduced by 60%,and the NO_χemission remains almost *** trade-off between NO_χconversion efficiency and NH_3 slip is *** studied flow compensation and switching working conditions can improve the dynamic performance of the UDS significantly and make the UDS dynamic response keep up with the changes of the engine＇s operating conditions quickly.

关键词： select catalyst reduction(SCR) urea dosing system(UDS) dynamic flow control strategies

Classification of power quality combined disturbances based on phase space reconstruction and support vector machines

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第2期9卷 173-181页

作者： Zhi-yong LI wei-lin WU School of Electrical Engineering Zhejiang University Hangzhou 310027 China

Power Quality (PQ) combined disturbances become common along with ubiquity of voltage flickers and harmonics. This paper presents a novel approach to classify the different patterns of PQ combined disturbances. The classification system consists of two parts, namely the feature extraction and the automatic recognition. In the feature extraction stage, Phase Space Reconstruction (PSR), a time series analysis tool, is utilized to construct disturbance signal trajectories. For these trajectories, several indices are proposed to form the feature vectors. Support Vector Machines (SVMs) are then implemented to recognize the different patterns and to evaluate the efficiencies. The types of disturbances discussed include a combination of short-term dis-turbances (voltage sags, swells) and long-term disturbances (flickers, harmonics), as well as their homologous single ones. The feasibilities of the proposed approach are verified by simulation with thousands of PQ events. Comparison studies based on Wavelet Transform (WT) and Artificial Neural Network (ANN) are also reported to show its advantages.

关键词： Power Quality (PQ) Combined disturbance Classification Phase Space Reconstruction (PSR) Support Vector Machines (SVMs)

On the stochastic dynamics of molecular conformation

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第9期8卷 1401-1407页

作者： DENG Mao-lin ZHU wei-qiu Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

An important functioning mechanism of biological macromolecules is the transition between different conformed states due to thermal fluctuation. In the present paper, a biological macromolecule is modeled as two strands with side chains facing each other, and its stochastic dynamics including the statistics of stationary motion and the statistics of conformational transition is studied by using the stochastic averaging method for quasi Hamikonian systems. The theoretical results are confirmed with the results from Monte Carlo simulation.

关键词： Biological macromolecule Thermal fluctuation Stationary statistics Transition time Stochastic averaging method

Collapse of cavitation bubbles near air bubbles

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2020年第5期32卷 929-941页

作者： Jing Luo wei-lin Xu Rui Li State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China

The cavitation erosion is one of the common damage modes in water *** study of the interaction among cavitation bubbles,air bubbles and the wall is of great significance for understanding the mechanism of the air entrainment to alleviate the cavitation and to enhance the cavitation erosion mitigation effect of *** using the high-speed camera,the regular patterns of the collapse of cavitation bubbles in the vicinity of the wall and the air bubbles are studied in this *** is shown that in the vicinity of air bubbles,the cavitation bubbles may only collapse towards or from air bubbles,while under the dual impacts of air bubbles and the wall,the direction of collapse of the cavitation bubbles depends on the combined vector of the impact forces of the air bubbles and the *** the air bubbles are very close to the cavitation bubbles,the air bubbles will be penetrated and stretched by the cavitation bubbles,when the distance between them is short enough,the cavitation bubbles and the air bubbles will connect to form gas-type cavitation bubbles,and the collapse strength will be significantly decreased,when there are two air bubbles near the cavitation bubbles,they may even be penetrated successively by the cavitation *** it can be concluded that during the air entrainment to alleviate the cavitation,the number of air bubbles is more important than the total air concentration.

关键词： Cavitation bubble air bubble high-speed photography air entrainment to alleviate cavitation

Nanozyme-Triggered Cascade Reactions from Cup-Shaped Nanomotors Promote Active Cellular Targeting

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research 2022年第3期2022卷 117-131页

作者： Xin Wang Zhongju Ye Shen lin lin wei Lehui Xiao State Key Laboratory of Medicinal Chemical Biology Tianjin Key Laboratory of Biosensing and Molecular RecognitionCollege of ChemistryNankai UniversityTianjin 300071China College of Chemistry Zhengzhou UniversityZhengzhou 450001China Key Laboratory of Chemical Biology&Traditional Chinese Medicine Research Key Laboratory of Phytochemical R&D of Hunan ProvinceCollege of Chemistry and Chemical EngineeringHunan Normal UniversityChangsha 410082China

Self-propelled nanomotors have shown enormous potential in biomedical ***,we report on a nanozymepowered cup-shaped nanomotor for active cellular targeting and synergistic photodynamic/thermal therapy under nearinfrared(NIR)laser *** nanomotor is constructed by the asymmetric decoration of platinum nanoparticles(PtNPs)at the bottom of gold nanocups(GNCs).PtNPs with robust peroxidase-(POD-)like activity are employed not only as propelling elements for nanomotors but also as continuous O_(2)generators to promote photodynamic therapy via catalyzing endogenous H_(2)O_(2)*** to the Janus structure,asymmetric propulsion force is generated to trigger the shortranged directional diffusion,facilitating broader diffusion areas and more efficient cellular searching and *** cascade strategy combines key capabilities,i.e.,endogenous substrate-based self-propulsion,active cellular targeting,and enhanced dual-modal therapy,in one multifunctional nanomotor,which is crucial in advancing self-propelled nanomotors towards eventual therapeutic agents.

关键词： endogenous shaped Active

Risk factors of metabolic syndrome after liver transplantation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2015年第6期14卷 582-587页

作者： Jun Zheng wei-lin Wang Division of Hepatobiliary and Pancreatic Surgery Department of SurgeryFirst Affiliated HospitalZhejiang University School of Medicine Department of Surgery The University of Hong Kong Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases

BACKGROUND： Liver transplantation is a treatment of choice for both acute and chronic liver failure. Accompanied with the increase of long-term survival rates of recipients, metabolic syndrome and its individual components, including obesity, hyperglycemia, hypertension and hyperlipidemia, have become more frequent post liver transplantation. Here we reviewed the literature concerning the risk factors for the development of metabolic complications in liver recipients.

关键词： liver transplantation risk factors hypertension hyperlipidemia diabetes mellitus

Technical review of electric vehicle charging distribution models with considering driver behaviors impacts

在线全文

学校读者我要写书评

暂无评论

Journal of Traffic and Transportation Engineering(English Edition) 2024年第4期11卷 643-666页

作者： wei lin Heng wei Lan Yang Xiangmo Zhao ART-EngineS Transportation Research Laboratory Department of Civil and Architectural Engineering and Construction ManagementUniversity of CincinnatiCincinnatiOH 45221USA School of Information Engineering Chang'an UniversityXi'an 710064China

Amassive market penetration of electric vehicles(EVs)associated with nonnegligible energy consumption and environmental issues has imposed a big challenge on evaluating electrical power distribution and related transportation facilities improvement in response to the largescale EV charging service *** deployment of EV charging stations including location and determination ofnumber of slowcharging stations and fast charging stationshas become an emerging concern and one of the most pressing needs in *** paper conducts a comprehensive survey of EV charging demand and distribution models with consideration of realistic driver behaviors *** is currently a shortage in academic literature,but indeed has drawn practical attention in the strategic planning *** address the need,this paper presents an in-depth literature review of relevant studies that have identified different types of EV charging facilities,needs or concerns that are considered into EV charging demand and distribution modeling,alongside critical impacting factor identification,mathematical relationshipsof the contributing factorsandEVchargingdemand and distribution *** findings from the current literature are summarized with strategies for optimized plan of charging station deployments(i.e.,location and related number of charging station),in an attempt to provide a valuable reference for interested readers.

关键词： Charging demand estimation Strategic charging station deployment Electric vehicle Driver behavior

Measurement of Temperature and Residual Strain during Fatigue of a CFRP Composite Using Fiber Bragg Grating Sensors

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2009年第3期22卷 364-368页

作者： SHEN Xiaoyan lin Yuchi WANG wei State Key Laboratory of Precision Measuring Technology and Instruments Tianjin University Tianjin 300072 China

Fatigue behaviour has important implications for engineering composite structures in sectors ranging from automotive to aerospace. Optical sensing technology displays excellent performance in these fields for monitoring. In this paper, temperature and residual strain during fatigue of a carbon fiber reinforced polymer（CFRP） are investigated. Four autoclaved CFRP beam specimens, with fiber Bragg grating（FBG） sensors and thermocouples embedded at selected locations, are subjected to three-point bending cyclic loading on the BOSE testing machine for fatigue testing. Thennocouples are used to measure the temperature while FBGs can sense the temperature and strain as well. Seven tests in total are conducted at different frequencies, and each test lasts for several days. From the experimental results, transient steep peaks of temperature increases （up to 2.3℃） are discovered at the beginning of the load. The following constant temperature increments are around 1.0℃, which is not relevant to frequencies from 0.1 Hz to 20 Hz and suspected due to fatigue. Residual strains of 1×10^-5-2×10^-5 during fatigue, fading away rapidly when unloading, are also reported. Embedded FBGs here are validated to sense temperature and strains in composite structures, which demonstrates promising potentials in structure monitoring fields. CFRP are verified to have an excellent performance during fatigue with low temperature increase and residual strain.

关键词： fatigue temperature residual strain frequency CFRP composite embedded fiber Bragg grating