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Theoretical prediction and experimental testing of mechanical properties for 3d printed silk fibroin-type II collagen scaffolds for cartilage regeneration

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MCB Molecular and Cellular Biomechanics 2018年第2期15卷 85-98页

作者： Gao, Lilan Yuan, Qingxian Li, Ruixin Chen, Lei Zhang, Chunqiu Zhang, Xizheng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin30000 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300000 China Hospital of Stomatolgy NanKai University Tianjin300000 China

Silk fibroin-type II collagen scaffold was made by 3D printing technique and freeze-drying method, and its mechanical properties were studied by experiments and theoretical prediction. The results show that the three-dimensional silk fibroin-typeII collagen scaffold has good porosity and water absorption, which is (89.3%+3.26%) and (824.09%+93.05%), respectively. With the given strain value, the stress of scaffold decreases rapidly firstly and then tends to be stable during the stress relaxation. Both initial and instantaneous stresses increase with increase of applied strain value. The creep strains of scaffold with different stress levels show the two stages: the rapidly increasing stage and the second stable stage. It is noted that the scaffold with compressive stress of less than 35 kPa can recover when the compressive stress is removed. However when the compressive stress is higher than 50 kPa, the scaffold is damaged and its structure is destroyed. Not only the compressive property but tensile property of scaffold are dependent on the applied displacement rate or strain rate. Its compressive elastic modulus and tensile modulus increase with increase of strain rate or displacement rate. The nonlinear relaxation model and creep model were constructed respectively and applied to predict the stress relaxation behavior and creep behavior of scaffold. It is found that there are good agreements between the experimental data and predictions, which mean that the built theoretical model can predict the mechanical behavior of scaffold. Copyright © 2018 Tech Science Press.

关键词： Strain rate

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In vitro uniaxial stretch model for evaluating the effect of strain along axon on damage to neurons

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Journal of Biomechanical Science and engineering 2014年第3期9卷 1-10页

作者： Nakadate, Hiromichi Fukumura, Yohei Kaneko, Yuma Kakuta, Akira Furukawa, Hidenori Aomura, Shigeru Graduate School of System Design Tokyo Metropolitan University 6-6 Asahigaoka Hino Tokyo191-0065 Japan Advanced Course of Mechanical and Computer Systems Engineering Tokyo National College of Technology 1220-2 Kunugida-machi Hachioji-shi Tokyo193-0997 Japan

Diffuse axonal injury (DAI), a major component of traumatic brain injury, is associated with rapid deformation of brain tissue resulting in the stretching of neuronal axons. Focal axonal beading, which is the morphological hallmark of DAI pathology, leads to the disconnection of neurons from tissues and results in cell death. Our goal is to achieve a better understanding of neuronal tolerance and help predict the pathogenesis of DAI from mechanical loading to the head. In the present study, we developed an experimental model that subjected cultured neurons to uniaxial stretch by controlling the direction of axonal elongation with a microfluidic culture technique and examined the effect of strains along the axon on cell damage. Neurites from PC 12 cells that differentiate into neurons with structurally axon-like cylindrical protrusions by nerve growth factor were extended at 0°, 45°, and 90° relative to the tensile direction by using a fabricated polydimethylsiloxane (PDMS) piece with microgrooves in combination with a PDMS substrate. The morphology of the same neurites was observed before and after stretching with a strain of 0.22 at a strain rate of 27 s-1. As a result, swellings along neurites oriented at 0° increased immediately following stretching and were sustained for 24 h. In contrast, swellings along neurites oriented at 45° and 90° transiently increased within 1 h following stretching. Although more ruptures were observed in neurites oriented at 0° and 90° than in those oriented at 45°, the number of neurites and cells did not differ among orientation conditions. These results suggest that the difference in strain along the axon induces axonal injuries differing in type and degree. They also suggest that the strain on the axon, rather than that on the cell-cultured substrate, is important for evaluating neuronal damage. © 2014 The Japan Society of mechanical Engineers.

关键词： Strain rate

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LCFNet: Loss Compensation Fusion Network for Real-Time Semantic Segmentation of Urban Road Scenes

LCFNet: Loss Compensation Fusion Network for Real-Time Seman...

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International Conference on Intelligent Transportation

作者： Lu Yang Yiwen Bai Fenglei Ren Shiyu Zhang Chongke Bi Tianjin Key Laboratory for Advanced Mechanical System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin China College of Intelligence and Computing Tianjin University Tianjin China

Semantic segmentation is used by intelligent transportation systems to understand and sense the traffic environment. However, achieving semantic segmentation in real-time is a challenge due to the necessity of both high accuracy and fast processing. This is especially valuable for applications such as autonomous driving and industrial robotics. In this paper, we propose a real-time semantic segmentation network, called LCFNet, which makes use of three-branch structure. The LCFNet consists of Lightweight Detail Guidance Fusion (L-DGF) and Lightweight Semantic Guidance Fusion (L-SGF) modules. Both modules aggregate information from various network layers. In the termination of network, a Total Guidance Fusion (TGF) module is proposed for processing information from all three branches. Depth-wise Convolution Pyramid Pooling (DCPP) module is also included to optimize accuracy and simplify computation. The effectiveness of LCFNet is demonstrated on two typical semantic segmentation datasets, Cityscapes and CamVid. On a single NVIDIA GeForce GTX 2080 Ti GPU, LCFNet reaches 77.02% mIoU at 95.97 FPS and 81.17% mIoU at 204.82 FPS, respectively.

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Newly Developed Universal Analytical Approach to Incomplete Spherical Conformal Contact Problems: Application to Spherical Plain Bearings with Self-Lubricating Fabric Liner

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SSRN 2024年

作者： Xue, Yahong Kang, Dongzhuang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China College of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

To address the conformal contact problem in self-lubricating spherical plain bearings bonded with a self-lubricating layer, a universal analytical model for normal contact between friction-less spheres is established. The accuracy and generality of this new model are verified through numerous finite element analyses. Our model overcomes the limitations of elastic half-space and small deformation assumptions. It can accurately calculate the contact stress distribution of self-lubricating spherical bearings bonded with a self-lubricating layer. Based on the new model, the complex non-linear relationship between the variables is being investigated. The model can be extended and applied to the conformal contact problem of spherical contact surfaces in biomechanics and other fields. © 2024, The Authors. All rights reserved.

关键词： Analytical models

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Exploration and Practice of Blended Teaching in the course of engineering Drawing Empowered by Knowledge Graph

Exploration and Practice of Blended Teaching in the Course o...

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International Conference on Educational and Information Technology (ICEIT)

作者： Yahong Xue Haozhi Mu Lijun Xue Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin University of Technology Tianjin China

ISBN: (数字)9798350372663

ISBN: (纸本)9798350372670

Under the current blended learning mode, students' ability to process, organize, and integrate knowledge is insufficient, and the ability to construct a complete knowledge system for autonomous learning is slightly weak. Taking the national first-class undergraduate course “engineering Drawing” at Tianjin University of Technology as an example, this study explores and practices the teaching of online and offline hybrid courses based on knowledge graphs, and conducts a comprehensive effectiveness analysis. Practice has proven that the hybrid teaching empowered by knowledge graphs enables visualization of knowledge points and analysis of learning situations, allows for planned learning paths, intelligent resource recommendations, and can achieve targeted integration of data and teaching of key and difficult issues. It has reference significance for the construction of an open, personalized, and precise intelligent education system.

关键词： Federated learning engineering drawings Education Knowledge based systems Data visualization Knowledge graphs Hybrid learning

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Stability Analysis of Nonlinear Self-excited Vibration in Cold Rolling Main Drive system

Stability Analysis of Nonlinear Self-excited Vibration in Co...

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第26届中国控制与决策会议

作者： Yang Xu Li Qing Peng Kaixiang Tong Chaonan Ding Dawei Key Laboratory of Advanced Control of Iron and Steel Process School of Automation and Electrical EngineeringUniversity of Science and Technology Beijing State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University

A nonlinear self-excited vibration model of main drive system in cold rolling is established. The mechanism of torsional vibration in main drive system stability is discussed within multiple scale method as well as Hopf bifurcation theorem. Then, the periodic solutions and condition of Hopf bifurcation are derived and the influence by subcritical/supercritical bifurcation is analyzed. Based on the simulation experiments with actual industrial data, the previous theoretical analysis and nonlinear model have been testified.

关键词： Nonlinear Modeling,Self-excited Vibration,Stability Analysis,Main Drive system,Cold Rolling Process

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Design of deep-water omnidirectional spirit level

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Journal of Measurement Science and Instrumentation 2021年第4期12卷 472-478页

作者： ZHAO Lianyu LI Shuo ZHAO Xiaolei LI Maolin CHEN Jinyu WANG Chenglin Tianjin Key Laboratory of Advanced Mechatronic System Design and Intelligent Control National Demonstration Center of Experimental Mechanical and Electrical Engineering EducationSchool of Mechanical EngineeringTianjin University of TechnologyTianjin 300384China Offshore Oil Engineering Co. Ltd.Tianjin 300461China

Attitude adjustment is a key link in the installation process of underwater facilities in deep *** solve this problem,an omnidirectional spirit level for deep water was *** sealing principle of the spirit level and the principle of deep-water pressure resistance are analyzed,and the threaded connection strength is *** mechanical simulation verifies that the spirit level can withstand the pressure of 2000 m water depth,and the water pressure test is carried out for 30 min in a 20 MPa hyperbaric *** the experiment is completed,the appearance of the spirit level is intact and there is no *** experiment results show that the deep-water omnidirectional spirit level can be used in the deep sea within 2000 m.

关键词： deep water omnidirectional spirit level attitude adjustment pressure test underwater pressure

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Intelligent fuzzy controller design on WARP for mechanical systems with complex dynamic behaviors

Intelligent fuzzy controller design on WARP for mechanical s...

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IEEE International Conference on Fuzzy systems (FUZZ-IEEE)

作者： S.V. Ulyanov T. Yamafuji V.G. Gradetsky A. Pagni Department of Mechanical and Control Engineering University of Electro-Communications Chofu Tokyo Japan Institute for Problems in Mechanics Russian Academy of Science Russia SGS-THOMSON Microelectronics Corporate Advanced System Architectures Italy

The methodology of intelligent fuzzy controller design is introduced. The basis of the methodology is simulation of computer dynamics for mechanical systems with the help of qualitative physics and the search of possible solutions with genetic algorithm (GA). On artificial neural networks optimal solutions are defined and knowledge base of fuzzy controller on the Weight Associative Rule Processor (WARP) is formed. Applications of this methodology on examples including a mobile robot for service use, a wall climbing robot (WCR) for decontamination of nuclear-power plant, a DC/DC converter and an apparatus for artificial ventilation of lungs, are examined.< >

关键词： Fuzzy control Fuzzy systems control systems mechanical systems Artificial intelligence Computational modeling Computer simulation Physics computing Genetic algorithms Artificial neural networks

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Virtually coupled train set control subject to space-time separation:A distributed economic MPC approach with emergency braking configuration

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High-Speed Railway 2024年第3期2卷 143-152页

作者： Xiaolin Luo Tao Tang Le Wang Hongjie Liu State Key Laboratory of Advanced Rail Autonomous Operation Beijing Jiaotong UniversityBeijing 100044China Department of Electrical and Computer Engineering University of CaliforniaRiversideCA 92521USA Beijing Zongheng Electro-Mechanical Technology Development Co. Ltd.Beijing 100081China School of Automation and Intelligence Beijing Jiaotong UniversityBeijing 100044China National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong UniversityBeijing 100044China

The emerging virtual coupling technology aims to operate multiple train units in a Virtually Coupled Train Set(VCTS)at a minimal but safe *** guarantee collision avoidance,the safety distance should be calculated using the state-of-the-art space-time separation principle that separates the Emergency Braking(EB)trajectories of two successive units during the whole EB *** this case,the minimal safety distance is usually numerically calculated without an analytic ***,the constrained VCTS control problem is hard to address with space-time separation,which is still a gap in the existing *** solve this problem,we propose a Distributed Economic Model Predictive control(DEMPC)approach with computation efficiency and theoretical ***,to alleviate the computation burden,we transform implicit safety constraints into explicitly linear ones,such that the optimal control problem in DEMPC is a quadratic programming problem that can be solved *** theoretical analysis,sufficient conditions are derived to guarantee the recursive feasibility and stability of DEMPC,employing compatibility constraints,tube techniques and terminal ingredient ***,we extend our approach with globally optimal and distributed online EB configuration methods to shorten the minimal distance among ***,experimental results demonstrate the performance and advantages of the proposed approaches.

关键词： Virtually coupled train set Space-time separation Economic model predictive control Distributed model predictive control Emergency braking configuration

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A Novel Frequency Estimation Strategy and Filter Based on the Gearbox Response Mechanism Model

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SSRN 2024年

作者： Li, Decai Chen, Jiwei Xie, Ruitong Luo, Zhiweng Sheng, Yanliang Hu, Mantang Wang, Guofeng Zhang, Mian Key Laboratory of Mechanism Theory and Equipment Design Ministry of Education School of Mechanical Engineering Tianjin University Tianjin300072 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

In the gearbox response signal, numerous sideband components generated by different fault characteristic frequencies are interleaved. Coupled with the noise interference, this makes health monitoring based on spectral analysis highly challenging. Traditional filtering methods, such as low-pass, high-pass and band-pass filters, and mode decomposition methods, exhibit limitations in filtering out interference signals over the entire frequency spectrum. Moreover, the absence of speed information complicates the determination of appropriate passbands. Most critically, noise within the passband is entirely retained. To address these issues, this paper proposes a methodology for estimating characteristic frequencies and filtering interference signals based on a novel response mechanism model (RMM) of gearbox. The proposed RMM model takes into account the structural attributes and vibration response mechanism of the gearbox, describing the modulation phenomena of fault characteristic frequencies on the meshing frequency and its harmonics. The proposed model-based frequency estimation (MFE) strategy accurately computes characteristic frequencies even in the absence of speed information. Additionally, the proposed model-based filter (MF) can perform accurate filtering over the entire frequency spectrum or within specified gear train vibration responses. Numerical simulations and experimental data validate the viability and effectiveness of the proposed methods. © 2024, The Authors. All rights reserved.

关键词： Frequency estimation

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