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Renormalization Group Analysis of Weakly Rotating Turbulent Flows

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Chinese Physics Letters 2011年第12期28卷 167-170页

作者： WANG Xiao-hong ZHOU quan Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei 230026

Dynamic renormalization group(RNG)analysis is applied to the investigation of the behavior of the infrared limits of weakly rotating *** turbulent flow subject to weak rotation,the anisotropic part in the renormalized propagation is considered to be a perturbation of the isotropic ***,with a low-order approximation,the coarsening procedure of RNG transformation is *** implementing the coarsening and rescaling procedures,the RNG analysis suggests that the spherically averaged energy spectrum has the scaling behavior E(k)∝k−11/5 for weakly rotating *** is also shown that the Coriolis force will disturb the stability of the Kolmogorov−5/3 energy spectrum and will change the scaling behavior even in the case of weak rotation.

关键词： scaling weakly rotating

Bending behavior of double-row stabilizing piles with constructional time delay

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第8期13卷 596-609页

作者： Yang YU Yue-quan SHANG hong-yue SUN College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China Department of Ocean Science and Engineering Zhejiang UniversityHangzhou 310058China

The bending behavior of double-row stabilizing plies is associated with the constructional time delay(CTD),which can be defined as the time interval between the installations of the front stabilizing pile and the rear stabilizing *** paper investigates the effect of CTD on the bending moments of double-row stabilizing piles and a method for determining the optimal CTD is *** stabilizing pile is modeled as a cantilever pile embedded in the Winkler elastic foundation.A triangular distributed earth pressure is assumed on the pile segment in the sliding *** front stabilizing pile and the rear stabilizing pile are connected by a beam with pinned *** analytical solutions of bending moments on the front and the rear stabilizing piles are derived and the accuracy of bending moment solutions is validated by comparing the tensile strain measured from the hongyan landslide project,Taizhou,Zhejiang,*** is concluded that CTD has a significant influence on the bending moments of double-row stabilizing *** optimal CTD can be obtained when the maximum tensile stress in the front stabilizing pile is equal to that in the rear stabilizing pile,which is 1.4 months for the hongyan landslide project.

关键词： Subgrade reaction Landslide Stabilizing pile Constructional time delay (CTD) Bending moment

Tensile properties and fractographs of Ti–2.5Al–1.5Mn foils at different temperatures

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Rare Metals 2017年第4期36卷 247-255页

作者： Zhen-Wu ma Guo-quan Tong Feng Chen College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016China

The tensile properties and fractographs of Ti- 2.5Al-1.5Mn foils at different temperatures were investi- gated. It is observed that material properties closely cor- relate with the thickness （T） to grain size （d） ratio and deformation temperature. Tensile analysis shows that local deformation is the main deformation feature in foils forming at room temperature, which may lead to premature fracture. The causes of inhomogeneous deformation behavior are the limited number of deformable grains contained in deformation zone and the weak transferability of hardening among different grains. Fracture analysis reveals that the size of dimples can represent the ductility of foils at room temperature. With the further increase of deformation temperature, the main plastic deformation mode of foils is transformed from intragranular disloca- tions and twin crystal to grain-boundary gliding and roll- ing. In conclusion, foil forming at elevated temperature can increase the hardening transferability and the number of deformable grains in deformation zone, which is an effective method to improve the formability and reduce the scatter of material properties.

关键词： Size effects Titanium foils Tensile properties Homogeneous deformation Elevated temperature

Dynamics and adaptive control of a dual-arm space robot with closed-loop constraints and uncertain inertial parameters

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Acta Mechanica Sinica 2014年第1期30卷 112-124页

作者： Ying-hong Jia quan Hu Shi-Jie Xu School of Astronautics Beihang University

A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of controlling the po- sition and attitude of both the satellite base and the payload grasped by the manipulator end effectors. The equations of motion in reduced-order form for the constrained system are derived by incorporating the constraint equations in terms of accelerations into Kane＇s equations of the unconstrained system. Model analysis shows that the resulting equations perfectly meet the requirement of adaptive controller design. Consequently, by using an indirect approach, an adaptive control scheme is proposed to accomplish position/attitude trajectory tracking control with the uncertain parameters be- ing estimated on-line. The actuator redundancy due to the closed-loop constraints is utilized to minimize a weighted norm of the joint torques. Global asymptotic stability is proven by using Lyapunov＇s method, and simulation results are also presented to demonstrate the effectiveness of the proposed approach.

关键词： Space robot Dynamics. Adaptive control Closed-loop constraint Parameter uncertainty - Kane's equation

Dynamics of a spacecraft with large flexible appendage constrained by multi-strut passive damper

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Acta Mechanica Sinica 2013年第2期29卷 294-308页

作者： Ying-hong Jia Shi-Jie Xu quan Hu School of Astronautics Beihang University

This paper is concerned with the dynamics of a spacecraft with multi-strut passive damper for large flexible *** damper platform is connected to the spacecraft by a spheric hinge,multiple damping struts and a rigid *** damping struts provide damping forces while the rigid strut produces a motion constraint of the multibody *** exact nonlinear dynamical equations in reducedorder form are firstly derived by using Kane＇s equation in matrix *** on the assumptions of small velocity and small displacement,the nonlinear equations are reduced to a set of linear second-order differential equations in terms of independent generalized displacements with constant stiffness matrix and damping matrix related to the damping strut *** simulation results demonstrate the damping effectiveness of the damper for both the motion of the spacecraft and the vibration of the flexible appendage,and verify the accuracy of the linear equations against the exact nonlinear ones.

关键词： Dynamics·Motion constraints·Multi-strut passive damper·Kane's equation

Two-Dimensional Animal-Like Fractals in Thin Films

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Chinese Physics Letters 1996年第2期13卷 121-124页

作者： GAO hong-jun XUE Zeng-quan WU quan-de PANG Shi-jin Beijing Laboratory of Vacuum Physics Chinese Academy of SciencesBeijing 100080 Department of Radio-Electronics Peking UniversityBeijing 100871

we present a few unique animal-like fractal patterns in ionized-clnster-beam deposited fullerene-tetracyanoquinodimethane thin *** fractal patterns consisting of animal-like aggregates such as"fishes"and"quasi-seahorses"have been characterized by transnission electron *** results indicate that the sall aggregates ofthe aninmal-like body are composed of many single crystals whose crystalline directions are generally *** formation of tle fractal patterns can be attributed to the cluster-diffusion-lirnited aggregation.

关键词： aggregation fractal crystalline

Mechanical properties and thermal stability of 7055 Al alloy by minor Sc addition

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Rare Metals 2020年第6期39卷 725-732页

作者： Chong-Yu Liu Guang-Biao Teng Zong-Yi ma Li-Li Wei Wen-Biao Zhou hong-Feng Huang Hai-quan Qi Key Laboratory of New Processing Technology for Nonferrous Metal and materials Ministry of EducationGuilin University of TechnologyGuilin 541004China Shenyang National Laboratory for materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Alnan Aluminium Co. LtdNanning 530000China

This study investigated the effect of 0.25 wt%Sc addition on the microstructure and mechanical properties of AA 7055 *** addition of Sc obviously refined the grains of AA 7055 alloy during casting,homogenizing,rolling,solution,and aging treatments due to the formation of primary and precipitate Al3(Sc,Zr)*** recrystallization and precipitation of AA 7055 alloy were inhibited during heat treatments by Sc *** Sccontaining AA 7055 alloy exhibited higher thermal stability than AA 7055 alloy during homogenizing treatment,because of the grain boundary pinning effect of nano-sized Al3(Sc,Zr)*** its structure characteristics such as fine grains,fineη′phase,and lessηphase,AA 7055 alloy with added Sc showed good mechanical properties after aging at 120℃for 24 h,with an ultimate tensile strength(UTS)of 679 MPa and elongation(EL)of 14%.This work provides an effective strategy to fabricate AlZn-Mg(-Cu)series(7 xxx)alloys with excellent mechanical properties.

关键词： Al alloy Sc addition Microstructure Mechanical properties

A defect recognition model for cross-section profile of hot-rolled strip based on deep learning

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Journal of Iron and Steel Research International 2023年第12期30卷 2436-2447页

作者： Tian-lun Li Wen-quan Sun An-rui He Jian Shao Chao Liu Ai-bin Zhang Yi Qiang Xiang-hong ma National Engineering Research Center for Advanced Rolling and Intelligent manufacturing University of Science and Technology BeijingBeijing100083China Academy of machinery Science and Technology Beijing100044China School of Engineering and Applied Science Aston UniversityBirminghamB47ETUK

The cross-section profile is a key signal for evaluating hot-rolled strip quality,and ignoring its defects can easily lead to a final *** characteristics of complex curve,significant irregular fluctuation and imperfect sample data make it a challenge of recognizing cross-section defects,and current industrial judgment methods rely excessively on human decision making.A novel stacked denoising autoencoders(SDAE)model optimized with support vector machine(SVM)theory was proposed for the recognition of cross-section ***,interpolation filtering and principal component analysis were employed to linearly reduce the data dimensionality of the profile ***,the deep learning algorithm SDAE was used layer by layer for greedy unsupervised feature learning,and its final layer of back-propagation neural network was replaced by SVM for supervised learning of the final features,and the final model SDAE_SVM was obtained by further optimizing the entire network parameters via error ***,the curve mirroring and combination stitching methods were used as data augmentation for the training set,which dealt with the problem of sample imbalance in the original data set,and the accuracy of cross-section defect prediction was further *** approach was applied in a 1780-mm hot rolling line of a steel mill to achieve the automatic diagnosis and classification of defects in cross-section profile of hot-rolled strip,which helps to reduce flatness quality concerns in downstream processes.

关键词： Hot-rolled strip cross section:Curve recognition Deep learning-Stacked denoising autoencoder Support vector machine Imperfect data

New Three-Mode Squeezing Operators Gained via Tripartite Entangled State Representation

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Communications in Theoretical Physics 2008年第1期49卷 225-228页

作者： JIANG Nian-quan FAN hong-Yi College of Physics and Electric Information Wenzhou University Wenzhou 325035 China Department of material Science and Engineering University of Science and Technology of China Hefei 230026 China

We show that the Agarwal-Simon representation of single-mode squeezed states can be generalized to find new form of three-mode squeezed states. We use the tripartite entangled state representations ｜p, y, z） and ｜x... 详细信息

关键词： tripartite entangled state three-mode squeezing operator IWOP technique