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Fractional viscoelastic solution of stratum displacement of a shallow tunnel under the surface slope condition

Underground Space 2023年第3期10卷 233-247页

作者： Fanchao Kong Dechun Lu Chao Ma Chenpeng Shen Xiaodong Yang Xiuli Du Institute of Geotechnical and Underground engineering Beijing University of TechnologyBeijing 100124China School of Civil and Transportation engineering Beijing University of Civil Engineering and ArchitectureBeijing 102626China Beijing Urban Construction design&Development Group Co. LimitedThe Third Design Institute of Railway InstituteBeijing 100034China college of Mechanical engineering Beijing University of TechnologyBeijing 100124China

The unified displacement function(UDF)is presented to describe the deformation behaviours of the tunnel profile along with time under the surface slope condition.Based on the discrete Fourier method,the third-order UDF in the physical plane is expanded to the Laurent series in the complex variable plane.The complex variable method is employed to derive the elastic analytical solution of stra-tum displacement,when the third-order UDF is taken as the displacement boundary condition of tunnel cross-section(DBCTC).The proposed elastic solution agrees well with the results of the finite element method for the consistent model,which verifies the correctness of the proposed analytical solution.Combining the corresponding principle and fractional Generalized Kelvin viscoelastic constitutive model,the fractional viscoelastic solution under the surface slope condition is determined.The time effect of stratum displacement is presented in two aspects:time-dependent DBCTC and time-dependent material parameters.The parameter analysis is performed to investigate influences of deformation modes of the third-order UDF,slope angle,tunnel radius and fractional order on the time effect of stratum vertical and horizontal displacement.

关键词： Third-order unified displacement function Surface slope condition Fractional viscoelastic solution Complex variable method Discrete Fourier method

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Chemomechanical Properties of Electrospun Polyvinyl Acetate(PVAc)Fiber Mat and its Application in Water-Triggered Self-folding

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Acta Mechanica Solida Sinica 2022年第5期35卷 851-866页

作者： Diankun Zhou Kun Jiang Yiqi Mao Shujuan Hou State Key Laboratory of Advanced design and Manufacruing for Vehicle Body Hunan UniversityChangsha410082China college of Mechanical and Vehicle engineering Hunan UniversityChangsha410082China

Environmental-stimulus-triggered self-folding mechanisms have found promising applications in many engineering fields.Recently,a water-activated self-folding procedure has been designed by using the electrospun polyvinyl acetate(PVAc)fiber mat which contains high tensile residual stresses in the vitrified fibers during the spinning processes.The water permeation initiates plasticization of PVAc fiber mat and leads to a material shrinkage.When water diffusion starts at the top surface of a PVAc sheet,a shrinkage variation along the diffusion pathway forms a bending hinge on the sheet,which has been demonstrated in 3D origami design.To capture the water-triggered plasticization mechanism and chemomechanical coupling deformation compatibility,a consistent finite deformation viscoplastic model is developed for the PVAc fiber mat under coupled chemomechanical loading conditions.The residual stress and‘fixed’strain are modeled through the unrecoverable plastic strain in the PVAc fiber mat.As water permeates into the PVAc fiber mat,the induced increase in mixing entropy lowers the glass transition temperature of the material,and results in a gradual relaxation of the fixed viscoplastic strain.A non-Fickian diffusion model suitable for glassy material is adopted to capture the water permeation in the PVAc fiber mat.After calibrated and validated by a series of experiments,the proposed model is implemented in ABAQUS software to simulate the water-activated self-folding of PVAc sheet.The numerical example for a typical origami design suggests a promising engineering application prospect.

关键词： Polyvinyl acetate(PVAc)fiber mat Water diffusion Viscoplastic model Self-folding

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考虑腐蚀和液舱晃荡影响的养殖水舱结构响应计算

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哈尔滨工程大学学报（英文版） 2024年第2期23卷 249-260页

作者：孙智勇李辉周思奇李志雨冯国庆 college of Shipbuilding engineering Harbin Engineering UniversityHarbin 150001China Guangdong Institute of Intelligent Unmanned System Guangzhou 511458China Marine design&Research Institute of China Shanghai 200011China

The environment and structure of the tanks used in aquaculture vessels are remarkably different from those of ordinary ships,and the resulting problem of structural strength is related to breeding safety.In this study,a model of aquaculture tank corrosion was constructed by using the multiphysical field coupling analysis software COMSOL Multiphysics,and wave and sloshing loads were calculated on the basis of potential flow theory and computational fluid dynamics.The influence of different calculation methods for corrosion allowance and sloshing load on the structural responses of aquaculture tanks was analyzed.Through our calculations,we found that the corrosion of aquaculture tanks is different from that of ordinary ships.The corrosion allowance in Rules for the Classification of Sea-going Steel Ships is small,and the influence of the aquaculture environment on corrosion can be ignored.Compared with the method set in the relevant rules,our proposed coupling direct calculation method for the structural response calculation of aquaculture tanks can better combine the specific environment of aquaculture tanks and provide more accurate calculations.

关键词： Aquaculture tank Corrosion simulation Sloshing load design load Structural response

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A simple image-based method for online moisture content estimation of iron ore green pellets

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Journal of Iron and Steel Research(International) 2023年第5期30卷 851-863页

作者： Shu-yi Zhou Xiao-yan Liu college of Electrical and Information engineering Hunan UniversityChangsha 410082HunanChina Innovation Institute of Industrial design and Machine Intelligence Quanzhou-Hunan University Quanzhou 362006FujianChina

Moisture content(MC)is an important quality metric of iron ore green pellets in pelletizing process in ironmaking industry.Current image-based methods for MC estimation may result in big errors for gray-scale pellet images captured under various lighting conditions.We proposed a simple image-based method to improve the MC estimation accuracy by illumination correction and linear regression modeling.Firstly,the illumination of the pellet image was transformed into the reference illumination by use of a color checker chart and piecewise linear interpolation,so that the influence of different illuminations could be greatly reduced.By experimental analysis,it was found that MC is approximately adversely proportional to the average intensity of the transformed images.A simple model for MC prediction was then established by linear fitting.Experiments demonstrated that the proposed method has good robustness to different lighting conditions and achieves the best performance in metrics of mean square error,mean absolute error and maximum absolute error in comparison with five state-of-art MC estimating methods.Application on a working disk pelletizer shows that the proposed method can predict well the change of moisture content with time,and its computing efficiency can satisfy the requirement for online MC monitoring during the pelletizing process.

关键词： Green pellet Moisture content Image processing Pelletizing process

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Novel Cylinder Movement Modeling Method Based on Aerodynamics

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Chinese Journal of Mechanical engineering 2017年第5期30卷 1193-1202页

作者： Jian-Qing Zhang Xiao-Mei Hu Jin-Sheng Kang Feng Xiong Ning Zeng School of Mechatronic engineering and Automation Key Laboratory of Intelligent Manufacturing and RoboticsShanghai University college of engineering Design and Physical SciencesBrunel University London

The cylinder movement is affected by multiple factors and it is difficult to establish the accurate movement model of the cylinder. In order to improve the reliability of the production line design and to speed up the production line debugging, a novel cylinder movement modeling method based on aerodynamics is proposed. The kinetic theory, thermodynamic theory and kinematics knowledge are applied and integrated various factors which affect the movement characteristics of the cylinder are considered. According to the proposed mathematical model of cylinder movement, thecombined simulation software of cylinder movement based on Visual Studio and Visual Component （3D Create） is developed to calculate thevelocity, accel- eration and movement time of the cylinders during the running of the assembly line. Comparison results of cylinder＇s movement time under different intake air and displacement show that the mathematical model of cylinder movement based on aerodynamic is more accurate and the degree of fittingis 0.9846, which proves the effectiveness of the combined simulation software of cylinder movement. By the cylinder movement modeling method based on aerodynamic, accurate value of takt and the debug parameters can be calculated as a reference for the designers and debuggers of the cylinder-driven assembly lines.

关键词： Aerodynamics Thermodynamics Cylindercharacteristic Combined simulation

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Control-oriented modeling of a high-aspect-ratio flying wing with coupled flight dynamics

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Chinese Journal of Aeronautics 2023年第4期36卷 409-422页

作者： Cong NIU Xiutian YAN Boyi CHEN Department of design Manufacturing&Engineering ManagementUniversity of StrathclydeGlasgow G11XQUK college of Astronautics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The flight-structural dynamics of a high-aspect-ratio wing challenge the flight control design.This paper develops a reduced model of coupled dynamics with stability consideration.The structural dynamics are formulated with dihedrals,and the central loads drive the deformation.The control-oriented model with essential coupled dynamics is formulated.Modal sensitivity anal-ysis and input–output pairing are performed to identify the control structure.Besides,an example of flight control design is provided to discuss the necessity of considering structural dynamics in controller design.Analytical coupled flight dynamics provide a system-theoretic approach for sta-bility and facilitate model-based control techniques.Simulation results reveal the characteristics of flight-structural coupled dynamics and demonstrate that the influence of flexible modes should be considered in control design,especially in lateral dynamics.

关键词： Flexible couplings Flexible wings Flight control systems Flight dynamics Sensitivity analysis

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Assessing the accessibility to fire hazards in preserving historical towns: Case studies in suburban Shanghai, China

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Frontiers of Architectural Research 2022年第4期11卷 731-746页

作者： Harrison Huang Lu Li Yan Gu college of Civil engineering and Architecture Zhejiang UniversityHangzhouChina Department of Environmental design Fuzhou UniversityFuzhouChina Center for Balance Architecture of Zhejiang University China Architectural design&Research Institute of Zhejiang University China

Protecting large-scale heritage settlements from being damaged by fires has become increasingly crucial in developing areas that lack adequate legislation, emergency planning, and particularly efficient techniques. This study provides a systematic emergency assessment methodology for evaluating the accessibility of specific fire-fighting techniques to mitigate fire hazards in historical towns and examines how the integration of municipal and local fire services works. Specifically, this paper examines the accessibility of fire trucks, local fire services and the overall protection capacity. There are quantitative calculations of the obstruction degrees on main streets, the feasible moving distances of fire-fighting vehicles and firefighters at a given time, and the fire protection coverage and intensity in each town. Using these methods, this paper systematically assesses the fire resistance of three historical towns, Chuansha, Gaoqiao and Fengjing, as case studies. In contrast to previous studies focusing on the vulnerability of buildings in large historical settlements, this assessment method combines an examination of street networks and various emergency response techniques and is particularly applicable to developing areas.

关键词： Accessibility to fire hazards Emergency assessments Fire-fighting techniques Heritage protection Historical towns Developing areas

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Entanglement Dynamics of Two Qubits Coupled Independently to Cavities in the Ultrastrong Coupling Regime:Analytical Results

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Chinese Physics Letters 2016年第5期33卷 5-8页

作者：朱维婷任清褒段立伟陈庆虎 College of Engineering and Design Lishui University Department of Physics Zhejiang University Collaborative Innovation Center of Advanced Microstructures

Dynamics of quantum entanglement of two qubits in two identical quantum Rabi models is studied analytically in the framework of corrections to the rotating-wave approximations. A closed-form expression for the entanglement dynamics initiated from the well-known Bell states is derived, which is very close to the numerical exact results up to the ultrastrong coupling regime. It is found that the vanishing entanglement can be purely induced by the counter-rotating terms, and can be enhanced with the atom-cavity coupling.

关键词： RWA on it in Entanglement Dynamics of Two Qubits Coupled Independently to Cavities in the Ultrastrong Coupling Regime:Analytical Results of for been is that Bell

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Lighting Estimation of a Convex Lambertian Object Using Redundant Spherical Harmonic Frames

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Journal of Computer Science & Technology 2013年第3期28卷 454-467页

作者：赵文勇陈绍林郑媛彭思龙 National ASIC design and engineering Center Institute of Automation Chinese Academy of Sciences college of Control engineering Northeastern University at Qinhuangdao

An explicit lighting estimation from a single image of Lambertian objects is influenced by two factors： data incompletion and noise contamination. Measurement of lighting consistency purely using the orthogonal spherical harmonic basis cannot achieve an accurate estimation. We present a novel signal-processing framework to represent the lighting field. We construct a redundant spherical harmonic frame with geometric symmetry on the sphere S2. Spherical harmonic frames are defined over the generating rotation matrices about symmetry axes of finite symmetry subgroups of SO（3）, and the generating functions are spherical harmonic basis functions. Compared with the orthogonal spherical harmonic basis, the redundant spherical harmonic frames not only describe the multidirectional lighting distribution intuitively, but also resist the noise theoretically. Subsequently, we analyze the relationship of the irradiance to the incoming radiance in terms of spherical harmonic frames, and reconstruct the lighting function filtered by the Lambertian BRDF （bidirectional reflectance distribution function）. The experiments show that the frame coefficients of spherical harmonic frames can better characterize the complex lighting environments finely and robustly.

关键词： lighting estimation spherical harmonic frame Lambertian object

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Study on the Bonding Performance of the Moso Bamboo Dowel Welded to a Poplar Substrate Joint by High-Speed Rotation

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Journal of Renewable Materials 2021年第7期9卷 1225-1237页

作者： Suxia Li Haiyang Zhang Biqing Shu Liangsong Cheng Zehui Ju Xiaoning Lu college of Materials Science and engineering Nanjing Forestry UniversityNanjing210037China college of Furniture and Art design Central South University of Forestry and TechnologyChangsha410004China college of Civil engineering Yangzhou Polytechnic InstituteYangzhou225127China

The wood friction welding technique with its high bonding strength,low cost,high efficiency,and without any adhesive has been increasing concern in China.Moso bamboo(Phyllostachys pubescens)and poplar(Populus sp.)are widely planted and used in the furniture industry,interior decoration,and wood structure construction in China.The aim of this work was to investigate the bonding performance of moso bamboo dowel rotation welded joints with different dowel/receiving hole diameter ratios.The results indicated that the ratio of dowel/receiving hole diameter was an important parameter that influenced the welding performance.The bonding strength of the bamboo-to-poplar welded joints at the optimal ratio of 10/7 was as high as 7.50 MPa,which was higher than that of the beech(Fagus sylvatica,L.),schima(Schima superba)dowels and PVAc glued joints.The temperature measurement results showed a peak temperature of bamboo dowel welding as high as 350–360°C.Some differences in the temperature curves between each dowel/hole diameter ratio group were observed at the three different hole depths,such as the friction time,peak temperatures,and stabilization time at the maximum temperature,which could explain the differences in welding strengths between different ratios.The SEM results showed the temperature-induced softening,melting and flowing of cell-interconnected polymer material in the wood and bamboo structure.In addition,the bamboo fibers(mainly vascular bundles)were wrapped to form a dense continuous bonding layer,similar to the reinforced concrete,thus producing a good bonding effect.The Fourier transform-infrared spectroscopy(FT-IR)analyses showed that the high temperature resulted in the increase of the lignin relative content due to the degradation reaction of cellulose in the welding zone,which improved the bonding properties.

关键词： Moso bamboo rotation welding tensile strength optimal ratio poplar

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