检索结果-内蒙古大学图书馆

Matrix regularization-based method for large-scale inverse problem of force identification

MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2020年 140卷 106698-000页

作者： Pan, Chudong Ye, Xijun Zhou, Junyong Sun, Zhuo Guangzhou Univ Sch Civil Engn Guangzhou Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China

Identification of force via structural responses has been widely studied due to the force is always difficult or even impossible to be measured directly. Force identification is a typical ill-posed problem. To overcome this drawback, regularization methods have been widely studied. However, existing regularization methods used for force identification belong to the vector-based method, in which unknown force and structural responses are organized in two vectors, respectively. This characteristic decides that the identified process of a long-duration problem will be time-consuming because the size of system matrix is large. In view of this, a novel matrix regularization-based method is proposed for force identification in this paper. Combing with moving time windows, the structural responses are extracted and organized in a form of matrix. A system matrix is formulated by considering both unknown force and unknown initial conditions. Then a governing equation is established, in which structural excitation sources such as force and initial condition are orderly stored in a form of matrix. To obtain a stable solution, matrix regularization is introduced for improving the matrix-based governing equation. Herein, the sparse penalty term is considered as the sum of absolute values of elements in the matrix of excitation sources. Fast iterative shrinkage-thresholding algorithm (FISTA) is applied for solving the matrix regularization model. The regularization parameter is selected according to Bayesian information criterion (BIC). Finally, numerical simulations and experimental studies are carried out for assessing the feasibility and effectiveness of the proposed method. Illustrated results show that the proposed method is effective and time-saving. It can use a system matrix with a relatively small size to dealing with a large-scale problem of force identification. Some related issues are discussed as well. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Force identification Matrix regularization Sparse regularization Inverse problem Moving time window

来源：评论

学校读者我要写书评

暂无评论

Synergetic roadmap of carbon neutrality and clean air for China

引用

Environmental Science and Ecotechnology 2023年第4期16卷 1-25页

作者： Qiang Zhang Zhicong Yin Xi Lu Jicheng Gong Yu Lei Bofeng Cai Cilan Cai Qimin Chai Huopo Chen Hancheng Dai Zhanfeng Dong Guannan Geng Dabo Guan Jianlin Hu Cunrui Huang Jianing Kang Tiantian Li Wei Li Yongsheng Lin Jun Liu Xin Liu Zhu Liu Jinghui Ma Guofeng Shen Dan Tong Xuhui Wang Xuying Wang Zhili Wang Yang Xie Honglei Xu Tao Xue Bing Zhang Da Zhang Shaohui Zhang Shaojun Zhang Xian Zhang Bo Zheng Yixuan Zheng Tong Zhu Jinnan Wang Kebin He Ministry of Education Key Laboratory for Earth System Modelling Department of Earth System ScienceTsinghua UniversityBeijing100084China Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing210044China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing100084China Institute for Carbon Neutrality Tsinghua UniversityBeijing100084China State Key Joint Laboratory for Environment Simulation and Pollution Control College of Environmental Sciences and Engineering and Center for Environment and HealthPeking UniversityBeijing100871China Center of Air Quality Simulation and System Analysis Chinese Academy of Environmental PlanningBeijing100012China Center for Carbon Neutrality Chinese Academy of Environmental PlanningBeijing100012China National Center for Climate Change Strategy and International CooperationBeijing100035China Nansen-Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China College of Environmental Sciences and Engineering Peking UniversityBeijing100871China Institute of Environmental Policy Management Chinese Academy of Environmental PlanningBeijing100012China Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control School of Environmental Science and EngineeringCollaborative Innovation Center of Atmospheric Environment and Equipment TechnologyNanjing University of Information Science and TechnologyNanjing210044China Vanke School of Public Health Tsinghua UniversityBeijing100084China Center for Energy and Environmental Policy Research Beijing Institute of TechnologyBeijing100081China China CDC Key Laboratory of Environment and Population Health National Institute of En

It is well recognized that carbon dioxide and air pollutants share similar emission sources so that synergetic policies on climate change mitigation and air pollution control can lead to remarkable co-benefits on greenhouse gas reduction,air quality improvement,and improved *** the context of carbon peak,carbon neutrality,and clean air policies,this perspective tracks and analyzes the process of the synergetic governance of air pollution and climate change in China by developing and monitoring 18 *** 18 indicators cover the following five aspects:air pollution and associated weather-climate conditions,progress in structural transition,sources,inks,and mitigation pathway of atmospheric composition,health impacts and benefits of coordinated control,and synergetic governance system and *** tracking the progress in each indicator,this perspective presents the major accomplishment of coordinated control,identifies the emerging challenges toward the synergetic governance,and provides policy recommendations for designing a synergetic roadmap of Carbon Neutrality and Clean Air for China.

关键词： Carbon neutrality Clean air Synergetic roadmap

来源：评论

学校读者我要写书评

暂无评论

Study on Cooling Efficiency and Mechanism of Li-Ion Battery Thermal Runaway Inhibition by Additive Enhanced Water Mist Based on Boiling Heat Transfer Theory

SSRN

引用

SSRN 2024年

作者： Hu, Xiangming Yang, Zhiyuan Deng, Yurui Li, Ming Wang, Qingsong Wei, Hongbin Wei, Xiaoxuan Han, Guoyu College of Safety and environmental engineering Shandong University of Science and Technology Shandong Qingdao266590 China State Key Laboratory of Mining Lab Disaster Prevention and Control Co-found by Shandong Province the Ministry of Science and Technology Shandong University of Science and Technology Shandong Qingdao266590 China Yantai Chuangwei New Energy Technology Co Yantai264006 China State Key Laboratory of Fire Science University of Science and Technology of China Hefei230026 China

In recent years, fire and explosion accidents caused by thermal runaway (TR) of lithium-ion battery (LIB) have occurred frequently, which has become one of the main obstacles restricting its development. Therefore, it is urgent to develop fire extinguishing agents with high cooling efficiency to inhibit the growth of TR. The water mist is an effective choice, but it shows poor performance with the rise of cell temperature under TR. In this study, two additives, KCl and nonionic fluorocarbon surfactant FC-4430, were added into the water mist to improve the cooling efficiency. In addition, the inhibition effect exerted by the modified water mist during the whole process of lithium-ion battery TR was experimentally investigated. Furthermore, the influence of water mist with additives on the Leidenfrost effect in the high temperature range was deduced, and the reinforcement cooling mechanism was analyzed by heat transfer theory. The results show that KCl and FC-4430 can increase the initial cooling rate in the high temperature range by 48.6%-120%. The reinforcement mechanism is attributed to change the medium physical parameters by additives. On the one hand, the Leidenfrost point of the droplets on the cell surface is increased, which in turn extends the temperature range of the nucleate boiling stage, and on the other hand, the heat flux density and heat transfer of the water mist in the film boiling state are increased. © 2024, The Authors. All rights reserved.

关键词： Efficiency

来源：评论

学校读者我要写书评

暂无评论

Exploring the Effect of Different Waste Polypropylene Matrix Composites on Service Performance of Modified Asphalt Using Analytic Hierarchy Process

SSRN

引用

SSRN 2023年

作者： Li, Fan Zhang, Xiao Zhang, Kaifeng Li, Feng Wang, Linbing Cao, Junsheng Shanxi Key Laboratory of Civil Engineering Disaster Prevention and Control College of Civil Engineering Taiyuan University of Technology Shanxi Taiyuan030024 China School of Transportation Science and Engineering Beihang University Beijing100191 China The Sensing and Perception Lab School of Environmental Civil Agricultural and Mechanical Engineering University of Georgia AthensGA30602 United States Shanxi Traffic Maintenance Group Co. Ltd Shanxi Taiyuan030006 China

Using end-of-life polypropylene (PP) as additive to modify base asphalt has received rapid-growing attention because of the significant benefits not only to alleviating environmental pressure of waste plastic but also to improving service performance of asphalt pavement. However, the low flexibility of waste PP results in undesired low-temperature property of corresponding modified asphalt so as to limit its application. Accordingly, several PP matrix composites have developed in recent years via adding elastomer or fiber, aiming to enhance the toughness and impact resistance at low temperature. Nevertheless, utilizing these waste PP matrix composites as modifiers of base asphalt unfortunately has not been well investigated yet. In this study, three different waste PP matrix copolymers were used to modify base asphalt, including laboratory-made PP, ethylene-propylene-rubber (EPR) and polyethylene (PE) copolymer, as well as commercial high-impact PP (HIPP) and fiber reinforced PP (FRPP). Moreover, their modifying effects were measured and compared with respect to creep recovery, force-ductility curve, fatigue resistance and storage stability. The fluorescence micrograph was also analyzed to reveal the modification mechanism. Analytic hierarchy process (AHP) was employed to determine the optimum waste PP matrix composite and concentration considering the overall service performance. Test results showed that the PP/EPR/PE modified asphalt exhibited superior overall properties in terms of lowest fatigue factor, excellent rutting resistance and satisfied toughness. By contrast, although the HIPP modified asphalt had highest creep recovery rate at high temperature, the ductility and toughness at low temperature were worst. For FRPP modified asphalt, the fibers could form crosslink structure within base asphalt that had positive effect on improving the low-temperature property, while the incompatibility between fiber and base asphalt led to poor storage stability and the o

关键词： Polypropylenes

来源：评论

学校读者我要写书评

暂无评论

Three-body problem - From Newton to supercomputer plus machine learning

引用

NEW ASTRONOMY 2022年第0期96卷

作者： Liao, Shijun Li, Xiaoming Yang, Yu State Key Lab Ocean Engn Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ Ctr Marine Numer Expt Sch Naval Architecture Ocean & Civil Engn Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ Sch Phys & Astron Shanghai 200240 Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

The famous three-body problem can be traced back to Newton in 1687, but quite few families of periodic orbits were found in 300 years thereafter. In this paper, we propose an effective approach and roadmap to numerically gain planar periodic orbits of three-body systems with arbitrary masses by means of machine learning based on an artificial neural network (ANN) model. Given any a known periodic orbit as a starting point, this approach can provide more and more periodic orbits (of the same family name) with variable masses, while the mass domain having periodic orbits becomes larger and larger, and the ANN model becomes wiser and wiser. Finally we have an ANN model trained by means of all obtained periodic orbits of the same family, which provides a convenient way to give accurate enough predictions of periodic orbits with arbitrary masses for physicists and astronomers. It suggests that the high-performance computer and artificial intelligence (including machine learning) should be the key to gain periodic orbits of the famous three-body problem.

关键词： Three-body problem Periodic orbit Machine learning Arbitrary mass of body

来源：评论

学校读者我要写书评

暂无评论

Post-buckling induced delamination propagation of composite laminates with bi-nonlinear properties and anti-penetrating interaction effects

引用

COMPOSITES PART B-engineering 2019年第Jun.1期166卷 148-161页

作者： Xue, Jianghong Jin, Fusong Zhang, Jianwen Li, Ping Xia, Fei Xu, Jiachu Liu, Renhuai Yuan, Hong Jinan Univ Sch Mech & Construct Engn Inst Appl Mech Guangzhou 510632 Guangdong Peoples R China Minist Educ Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

This paper presents a unique theoretical analysis for the multiple failures of in-plane loaded composite laminates containing a through-width delamination. Under the action of the in-plane load, the delaminated laminates undergo first post buckling failure, then delamination propagation. The anti-penetrating contact effect occurred at the interfaces of the delamination is identified by analyzing the local transverse deformation and is incorporated into the multiple failure stages. Based on von Karman nonlinear geometric relationships, the post-buckling equilibrium path of the delaminated laminates characterized by the in-plane load vs deflection amplitude curves is solved. Expression of energy release rate is derived from variational principles as the summation of the products of shear forces and deflection slopes at the delamination fronts. With the available solutions from post-buckling analysis, threshold to initiate the delamination to propagate is computed according to Griffith fracture criterion and is calculated for different delamination conditions by developing Matlab program. It is found that the delaminated laminate undergoes a consistently macroscopic deflection with microscopic local buckles on the interfaces of the delamination. For all cases, Mode I delamination propagation can never occur due to the contact behavior. Instead, Mode II delamination propagation prevails regardless of the delamination size and position. The analysis presented in this paper accounts for nonlinear geometric deformation, nonlinear constitutive behavior and anti-penetrating interaction effects and identifies multiscale deformation modes involved in different failure mechanisms, thereby demonstrates the latest research idea for the current frontier problems.

关键词： Delamination propagation Multiple failure modes Bi-nonlinear properties Anti-penetration contact effect

来源：评论

学校读者我要写书评

暂无评论

Static and dynamic tensile behaviors of BFRP bars embedded in seawater sea sand concrete under marine environment

引用

COMPOSITES PART B-engineering 2022年 242卷

作者： Li, Sheng Zhu, Deju Guo, Shuaicheng Xi, Huifeng Rahman, Md Zillur Yi, Yong Fu, Bing Shi, Caijun Hunan Univ Coll Civil Engn Key Lab Green & Adv Civil Engn Mat & Applicat Tech Changsha 410082 Peoples R China Hunan Univ Int Sci Innovat Collaborat Base Green & Adv Civil Changsha 410082 Peoples R China Hunan Univ Key Lab Bldg Safety & Energy Efficiency Minist Educ Changsha 410082 Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Ahsanullah Univ Sci & Technol Dept Mech Engn Dhaka 1208 Bangladesh Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China

Basalt fiber reinforced polymer (BFRP) bars can be used as an appropriate substitute for steel rebars in marine concrete structures due to their corrosion-free nature and high tensile performance. However, the long-term dynamic properties of BFRP bars in the marine environment are not well known, which is critical for structural safety when subjected to external dynamic loads (e.g., tsunamis and earthquakes). Therefore, this study investigates the static and dynamic tensile behaviors of BFRP bars after exposure to the seawater sea sand concrete (SWSSC) under marine environment. Accelerated corrosion tests were conducted under various exposure periods (60, 90, and 120 days) and temperatures (25, 40, and 55 C). Both optical stereo microscope (OSM) and scanning electron microscope (SEM) were used to examine the failure patterns of BFRP bars, whereas the degradation mechanisms were investigated by X-ray micro-computed tomography (micro-CT), SEM, and Fourier transform infrared spectroscopy (FTIR). Results show that the tensile properties of BFRP bars are sensitive to strain rate. Both the tensile strength and the elastic modulus of BFRP bars increase with increasing strain rate, but the failure strain drops. The tensile strength and failure strain reduce with increasing exposure temperature and duration, whereas the elastic modulus does not change significantly. Microstructure analysis clearly reveals that failures of BFRP bars occur due to fiber breakage, matrix cracking, and interface debonding. The basalt fibers always exhibit brittle fracture, but the fracture surfaces change from relatively flat to rough when the strain rate increases. Moreover, the deterioration of BFRP bars is caused by resin hydrolysis, fiber-resin interfaces debonding and fiber damage after corrosion. These results can provide some insights to promote the application of BFRP composites in coastal and marine structures.

关键词： BFRP bars Seawater sea sand concrete Marine environment Tensile properties Strain rate Failure patterns

来源：评论

学校读者我要写书评

暂无评论

Identification of external forces via truncated response sparse decomposition under unknown initial conditions

引用

ADVANCES IN STRUCTURAL engineering 2019年第15期22卷 3161-3175页

作者： Pan, Chudong Yu, Ling Guangzhou Univ Sch Civil Engn Guangzhou Guangdong Peoples R China Jinan Univ Sch Mech & Construct Engn MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

When structural dynamic design for smart control and health monitoring is executed, imposed excitations on structures are one of most important issues in structural engineering. Identification of structural excitations, such as force reconstruction, moving force identification, and so on, has drawn increasing attentions in the last decades. Assumption of known initial conditions is a precondition for existing deterministic force reconstruction methods. However, initial conditions are often unknown and hard to be estimated. To address this problem, a novel truncated response sparse decomposition method is proposed for calculating the external forces under unknown initial conditions. The truncated response sparse decomposition involves two basic steps, that is, response sparse decomposition and force estimation. First, a collection of basis vectors is defined for expressing unknown forces. Unknown initial conditions are represented in modal space. Structural responses induced by both external forces and initial conditions are then normalized as potential response features to form an image dictionary, which is adapted to decompose the measured responses via sparse regularization. Second, the response features with lower decomposed amplitudes and small scaling factors are eliminated from the decomposed results. The remaining features are used for estimating the external forces. In order to assess the accuracy and the feasibility of the proposed force reconstruction method, some numerical simulations on a planar truss structure and a series of experimental studies are carried out. The illustrated results show the robustness and the applicability of the proposed method for addressing the force reconstruction problem under unknown initial conditions. Some related issues are discussed as well.

关键词： force reconstruction ill-condition problem sparse regularization truncated response sparse decomposition unknown initial conditions

来源：评论

学校读者我要写书评

暂无评论

Orthotropic Analysis of Steel Deck-Girder-Rib Systems Subjected to Transverse Load

引用

INTERNATIONAL JOURNAL OF STEEL STRUCTURES 2019年第3期19卷 1010-1022页

作者： Chen, Mu Xue, Jianghong Li, Ping Jin, Fusong Jinan Univ Sch Mech & Construct Engn Inst Appl Mech Guangzhou 510632 Guangdong Peoples R China Minist Educ Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China

As one of the advanced modern techniques, orthotropic steel decks are widely used in bridge engineering. Because of its structural complexity, theoretical analysis of mechanical performances of the orthotropic steel bridge deck is very difficult. Therefore, in the past 50years, a series of experiments and finite element analysis have been used to obtain the information. A steel deck-girder-rib bridge system subjected to the transverse load is investigated in this paper. The bridge deck is laid on four simply-supported girders at the four edges and is reinforced by ribs in longitudinal direction. The longitudinally stiffened deck is idealized as an orthotropic plate. The equivalent material properties in the longitudinal and breadth directions of the orthotropic plate are evaluated using micro-mechanics of composite material by treating the ribs as reinforcing fiber-beams. Governing equations for the deck-girder-rib bridge systems are established and are solved using Ritz method. The analytical solutions are substantiated by comparing with the classic solutions of an isotropic deck with fixed ends and with the finite element predictions. The analytical approach presented in this paper eliminates the very intricate and arduous kinematics study among deck-girder-rib and allows the bridge engineer to fast and convenient estimate the deformation in an orthotropic bridge deck.

关键词： Steel deck-girder-rib system Orthotropic analysis Overall integrity ABAQUS finite element analysis Ritz method

来源：评论

学校读者我要写书评

暂无评论

Bridge condition monitoring using fixed moving principal component analysis

引用

STRUCTURAL control & HEALTH MONITORING 2020年第6期27卷 e2535-e2535页

作者： Nie, Zhenhua Guo, Enguo Li, Jun Hao, Hong Ma, Hongwei Jiang, Hui Jinan Univ Sch Mech & Construct Engn Guangzhou Peoples R China Minist Educ China Key Lab Disaster Forecast & Control Engn Guangzhou Peoples R China Curtin Univ Sch Civil & Mech Engn Ctr Infrastruct Monitoring & Protect Bentley WA Australia Dongguan Univ Technol Sch Environm & Civil Engn Dongguan Peoples R China Guangdong Seismol Bur Guangzhou Peoples R China

This paper proposes a data-driven damage detection method based on fixed moving principal component analysis (FMPCA) to analyze structural dynamic responses and monitor the bridge operational condition and the damage occurrence. The damage indices based on principal components (PCs) and eigenvalues can be calculated continuously by applying a fixed moving window. The length of the moving window is determined by using a new criterion based on the convergent spectrum of cumulative contribution ratio. Numerical simulations and experimental tests in the laboratory on beam bridge models subjected to stochastic loads are conducted to investigate the accuracy and effectiveness of the proposed approach. Both simulation and experimental results indicate that using the FMPCA can well analyze the dynamic vibration data to detect damage or abnormal vibration behavior during the operational condition. It can be used to accurately monitor the time instant of damage occurrence, which is very important in long-term monitoring of civil engineering structures. The proposed method is successfully applied to analyze the data recorded during an incident that a real large-scale suspension bridge was slightly scraped by the mast of a sand ship, which further verifies the effectiveness and feasibility of this method in engineering applications. The results also indicate that the bridge was not damaged after the incident but presented a short time abnormal vibration behavior owing to the impact of the ship mast.

关键词： damage detection fixed window moving principal component analysis online monitoring structural health monitoring

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：