检索结果-内蒙古大学图书馆

Thin-Walled Structures 2025年 215卷

作者： Bian, Zheng Gong, Yu Liu, Hao Zhang, Jianyu Zhao, Libin Hu, Ning College of Aerospace Engineering Chongqing Key Laboratory of Heterogeneous Material Mechanics Chongqing University Chongqing 400044 China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Chongqing 400044 China State Key Laboratory of Reliability and Intelligence Electrical Equipment School of Mechanical Engineering Hebei University of Technology Tianjin 300401 China Key Laboratory of Advanced Intelligent Protective Equipment Technology Ministry of Education Hebei University of Technology Tianjin 300401 China

The multi-phase design of additively manufactured triply periodic minimal surfaces (TPMS) lattices and a series of studies have demonstrated that this design strategy has excellent mechanical performance improvement effects compared to homogeneous materials. However, the influence of phase proportions on mechanical properties under quasi-static compression and high strain-rate impact remains underexplored. Inspired from precipitation strengthening, this study investigates the energy absorption and deformation behaviors of multiphase TPMS lattices with varying hybrid ratios. By combining finite element simulations and experiments, the impact of hybrid ratio, relative density, and strain rate on specific stiffness, strength, and energy absorption was investigated. Results indicate that unlike the previous equipartitioned multiphase structure, the inserted multiphase structure has better energy absorption performance and impact resistance with a smaller hybrid ratio. These findings provide valuable insights for multiphase design and application of multiphase metamaterials in engineering structures. © 2025 Elsevier Ltd

关键词： Strain rate

Significant Wave Height Prediction Based on VMD-SA-MLP-BP

学校读者我要写书评

暂无评论

Significant Wave Height Prediction Based on VMD-SA-MLP-BP

Chinese Automation Congress (CAC)

作者： Yining Wu Runfeng Zhang Fang Liu Zhenzhong Liu Jianguo Wu Haonan Dong Tianjin Key Laboratory for Advanced Mechatronic 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 Yichang Research Institute of Testing Technology Yichang China Tianjin Hanhailanfan Marine Technology Co. Ltd. Tianjin China School of Computer Science and Engineering Tianjin University of Technology Tianjin China

Waves seriously impact port construction, worldwide route planning, military activities, and wave power generation. To improve the accuracy of significant wave height prediction, we proposed a novel prediction method, a multi-layer perceptron combined with a backpropagation adjustment (MLP-BP) prediction model that combines mutation mode decomposition (VMD) and a simulated annealing optimization algorithm (SA). Firstly, we use the variable modulus method to decompose the significant wave height sequence data and transform the wave height sequence into multiple different sub-modes (IMF) to reduce the complexity and non-stationarity of the data. Secondly, the simulated annealing algorithm (SA) is used to optimize the weight and bias of the MLP-BP neural network to find the optimal parameter configuration and improve the performance and generalization ability of the prediction model. Finally, the decomposed sub-modal components of each significant wave height sequence are inserted into the MLP-BP neural network and the predicted values of each element are summed to obtain the final significant wave height prediction. The prediction results of the SSA-MLP-BP, PSO-MLP-BP, SA-MLP-BP, and VMD-SA-MLP-BP were compared and demonstrated that the VMD-SA-MLP-BP model performed best. The MAE, MAPE, MSE, RMSE, and R2 of the prediction evaluation indexes were 0.036 m, 11.7%, 0.004 m 2 , 0.067 m, and 0.983, respectively, which performed well in predicting significant wave height.

关键词：

Liquid Metal Manifold Microchannel Heat Sink for Ultra-High Heat Flux Cooling

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Zhang, Mingkuan Gao, Qi Zhao, Zhiyuan Guo, Luna Li, Xuan Zhang, Chao Zhang, Xudong Rao, Wei 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 China School of mechanical engineering Tianjin University of Commerce Tianjin300134 China Institute of Refrigeration and Cryogenics Shanghai Jiao Tong University Shanghai200240 China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering Mechanics Tsinghua University Beijing Beijing100084 China CAS Key Laboratory of Cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences China Beijing Key Lab of CryoBiomedical Engineering and Key Lab of Cryogenics Beijing100190 China

The reduction in transistor dimensions and advancements in chip integration have led to a dramatic increase in the heat flux of chip. advanced heat dissipation technology has become the pivotal in ensuring the normal operation of chips and fully utilizing chip performance. Room temperature liquid metal convection cooling technology has demonstrated its efficacy as a viable approach for addressing high heat flux heat dissipation. However, the smaller specific heat capacity of liquid metal leads to a large temperature rise, imposing a constraint on the progression of liquid metal cooling technology. To overcome this drawback, this paper proposed a liquid metal manifold channel structure designed to convert the continuous long-range flow into a segmented short-range flow. The good matching between liquid metal and manifold structures is adequately demonstrated through a comparison with alternative coolant and channel structure. The simulation results demonstrate the effectiveness of liquid metal manifold channel cooling in dealing with a heat flux of 1000 W/cm², ensuring that the maximum temperature of the chip remains below 351.7 K. Moreover, the convective heat transfer coefficient even reaches 106 W/(m2·K), which is ten times larger than that of water conventional microchannel heat sink. The orthogonal experiments were conducted to analyze how the structural parameters affect the dissipation performance, including the height of the microchannel, ratio of manifold length to fin length, length of fin in manifold, width of channel, and ratio of fin with to channel width. It concluded that the height of the microchannel has been identified as the most critical factor. This manifold structure mitigates the inherent limitation of the lower specific heat capacity of liquid metal, paving the way for effective thermal management of electronic devices subjected to ultra-high heat flux. © 2024, The Authors. All rights reserved.

关键词： Heat flux

Effects of Wall Emissivity on Aerodynamic Heating in Scramjets

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2020年第6期16卷 206-216页

作者： Yue Zhou Pengfei Ju School of Aeronautical Science and Technology Beihang UniversityBeijing100191China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education(Tianjin University of Technology) Tianjin300384China

The effects of the wall emissivity on aerodynamic heating in a scramjet are *** supersonic turbulent combustion flow including radiation is solved in the framework of a decoupled strategy where the flow field is determined first and the radiation field *** particular,a finite difference method is used for solving the flow while a DOM(iscrete ordinates method)approach combined with a WSGGM(weighted sum of gray gases)model is implemented for radiative *** nonreactive turbulent channel flows are examined for a DLR hydrogen fueled scramjet changing parametrically the wall *** results indicate that the wall radiative heating rises greatly with increasing the wall *** the wall emissivity rises,the radiative source and total absorption increase,while the incident radiation decreases ***,although the radiative heating can reach a significant level,its contribution to the total aerodynamic heating is relatively limited.

关键词： Scramjet aerodynamic heating wall emissivity radiation

Nonstoichiometric Protic Ionic Liquids for Efficient Carbon Dioxide Capture

学校读者我要写书评

暂无评论

SSRN 2023年

作者： Wang, Litian Chen, Jie Li, Dan Li, Cuiping Qian, Lirong Xiong, Yang Xie, Zhiyong Wang, Shuai Zhou, Tongyao Gai, Baojia Wang, Yinuo Tianjin Key Laboratory of Film Electronic and Communication Devices School of Integrated Circuit Science and Engineering Tianjin University of Technology Tianjin300384 China School of Integrated Circuit Science and Engineering Tianjin University of Technology Tianjin300384 China 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 China Tianjin Bohua Yongli Chemical Industry CO. Ltd Tianjin30045 China

Protic ionic liquids (PILs) have emerged as promising solvents for CO2 capture, offering great potential for the development of efficient CO2 absorbents. Understanding the relationship between the PILs’ structures and CO2absorption mechanisms is instructive for advancing their applicability. Herein, an innovative strategy for CO2 capture using nonstoichiometric PILs was demonstrated for the first time. These nonstoichiometric PILs composed of imidazole (Im) as a Brønsted acid and 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) as a Brønsted base with various ratios. They exhibited both low viscosities and remarkable CO2 loading capacities, reaching up to 0.194 g CO2 /g IL and 1.42 mol CO2 /mol IL at 0.1 atm and 40 °C. The distribution of neutral and ionic species in these nonstoichiometric PILs was determined using density functional theory (DFT) calculations and nuclear magnetic (NMR) spectroscopy analysis. Correlations between the mole ratio of Brønsted acid and base and the viscosities, conductivities, and CO2 absorption properties were observed. The mechanism of CO2 absorption was proposed from the spectral results and DFT calculations. The superior CO2 loading ability of these PILs can be attributed to the formation of the zwitterionic carbamic complexes through interactions between CO2 and the N atom in DBU. Additionally, the presentence of Im significantly avoided the dramatic increase in the viscosity of the absorbents during CO2 absorption. It is believed that the new insights into the CO2 mechanism will facilitate the rational design of PILs for CO2 capture in the future. © 2023, The Authors. All rights reserved.

关键词： Carbon dioxide

design of wearable squat booster for automobile assembler based on ergonomics 6

学校读者我要写书评

暂无评论

Design of wearable squat booster for automobile assembler ba...

2020 6th International Forum on Engineering Materials and Manufacturing Technology, IFEMMT 2020

作者： Chen, Zhewen Qiao, Zhifeng Bao, Tianxu Dou, Fuchao Chen, Xinpu Tianjin University of Technology Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin China

Aiming at the problem that automobile assembler need to squat for a long time, a wearable squatting assistance system with low cost, simple control and easy to squat and walk is designed. Based on ergonomics and finite element theory, UG was used to draw a three-dimensional solid model of the wearable squatting power system for automobile assemblers. With the help of ANSYS software, the statics analysis of key components is carried out to check their strength and stiffness. It is concluded that the wearable squatting power assist device for automotive fitters based on ergonomics has reached the design requirements in terms of function use and strength and stiffness. © Published under licence by IOP Publishing Ltd.

关键词： Ergonomics

Vibration Absorption Efficiency and Higher Branches Elimination of Variable-Stiffness Nonlinear Energy Sink

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2020年第1期27卷 76-84页

作者： Rui Zhong Jian’en Chen Weimin Ge Jun Liu Xiaofeng Wang Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System Tianjin University of TechnologyTianjin 300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of TechnologyTianjin 300384China

Vibration absorption efficiency of a variable⁃stiffness nonlinear energy sink(NES)was investigated when the main oscillator was subjected to harmonic and impulse *** slow flow equations of the coupled system were derived by using the complexification⁃averaging method,and the nonlinear equations which describe the steady⁃state response were *** the harmonic excitation force increased,the system which comprises constant⁃stiffness NES generated higher branch responses,greatly reducing the vibration absorption *** influence of nonlinear stiffness on the responses of the system was *** show that,with the increase of harmonic exciting force,a reduction of NES stiffness can eliminate the higher branch responses and even the frequency band of strongly modulated *** vibration absorption efficiency of variable⁃stiffness NES attached to the linear oscillator for different amplitudes of impulse excitation was *** show that the proper reduction of nonlinear stiffness under increasing impulse excitation can greatly increase the vibration absorption efficiency of NES,and the variable⁃stiffness design can effectively mitigate the negative influences of the increase of the excitation amplitude on the efficiency of constant⁃stiffness NES.

关键词： nonlinear energy sink efficiency variable⁃stiffness vibration suppression higher branch

Investigation on Material Removal of the Sub-Aperture Tool Used for Polishing Riblet Surfaces

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Wang, Guilian Lv, Bingrui Liu, Bin Fang, Fengzhou Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China School of Mechanical and Materials Engineering University College Dublin Belfield D04 V1W8 Ireland Key Laboratory of Advanced Ceramics and Machining Technology Ministry of Education Tianjin University Tianjin300072 China Tianjin Laboratory of Control Theory and Applications in Complicated System School of Electrical and Electronic Engineering Tianjin University of Technology Tianjin 300384 China Tianjin University Tianjin 300072 China

Riblet surfaces find wide applications owing to their excellent performance such as drag reduction. In this study, sub-aperture tool is investigated to polish the riblet surfaces, two main different curvatures at any point of this kind of tool surface are proposed. A series of simulation studies are conducted to investigate the effect of key parameters on the material removal, such as tool radius, inclination angle, polishing pressure, and tool speed. The results show that a higher difference between the tool radius values in two directions increases the difference between the major and minor axes of the contact area. Based on experimental tests and simulation analysis, it is conluded that the profile and depth of material removal distribution both increase with an increase in polishing pressure, the material removal profile remains constant but the removal detpth increases with an increase in polishing speed, and the parameter K is a time-dependent. © 2022, The Authors. All rights reserved.

关键词：

Hamiltonian Dynamics and Targeted Energy Transfer of a Grounded Bistable Nonlinear Energy Sink

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Li, Shuangbao Zhou, Xinxing Chen, Jianen Research Institute of Science and Technology Civil Aviation University of China Tianjin300300 China College of Science Civil Aviation University of China Tianjin300300 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China

A two-degree-of-freedom nonlinear mechanical system describing a damped linear oscillator weakly coupled to a lightweight grounded bistable nonlinear energy sink is proposed to investigate the targeted energy transfer (TET) under asymmetric local nonlinear potentials. The Bogdanov-Takens bifurcations of equilibria are discussed to reflect the bistable and asymmetric characteristics of the system. Through projections of isoenergetic manifolds, the topological features of the Hamiltonian dynamics under $1:1$ internal resonance have been investigated, which induces conditions for energy localization and exchange. In the general case, the topological features of the Hamiltonian dynamics related to the nonlinear normal modes (NNMs) are classified by the Poincare map, the relations between the NNMs and the Hamiltonian dynamics have been interpreted through the frequency energy plots. The results show that introducing the asymmetric characteristics may enhance the TET and realize the complete TET. © 2022, The Authors. All rights reserved.

关键词： Degrees of freedom (mechanics)

In-Situ Biaxial Cyclic Loading Behavior of Articular Cartilage and its Microstructure Analysis

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Gao, Lilan Feng, Luming Tan, Yansong Liu, Gang Li, Ruixin Gao, Hong Zhang, Chunqiu 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 Tianjin Stomatological Hospital Tianjin300041 China School of Chemical Engineering and Technology Tianjin University Tianjin300350 China

Altered cyclic loading may change the mechanical properties, further inducing damage to articular cartilage. In this study, we studied the biaxial cyclic loading behavior of knee articular cartilage and analyzed the changes of microstructure at fibril level. Firstly, the in-plane biaxial cyclic behaviors of cartilage were investigated with an emphasis on the effects of loading paths to account for complicated loading states in daily activities. The results show that the strain evolution in X-direction is obviously affected by the constraints in Y-direction (orthogonal direction). The loading path has a great influence on the biaxial mean strain, while due to no constraint and the largest stress constraint in Y direction, proportional loading path and uniaxial loading path show the highest and lowest mean strain in X-direction, respectively. Subsequently, the effects of stress amplitude and stress peak holding time on mean strain were probed under square path. It was found that the mean strain of cartilage increases with the increase of stress amplitude or peak stress holding time. In addition, to reveal the inherent deformation mechanism, the collagen fibrils networks before and after biaxial cyclic loading were analyzed. The rearrangement of collagen fibrils networks is related to the stress state of cartilage. Larger stress leads to severer fiber damage in cartilage. © 2022, The Authors. All rights reserved.

关键词： Cartilage