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Chinese Journal of Mechanical Engineering 2018年第4期31卷 168-181页

作者： Rui-Ting Tong Geng Liu Shaanxi Engineering Laboratory for Transmissions and Controls Northwestern Polytechnical University

Textured surfaces are widely used in engineering components as they can improve tribological properties of sliding contacts, while the detailed behaviors of nanoscale reciprocating sliding contacts of textured surfaces are still lack of study. By using multiscale method, two dimensional nanoscale reciprocating sliding contacts of textured surfaces are investigated. The influence of indentation depth, texture shape, texture spacing, and tip radius on the average friction forces and the running-in stages is studied. The results show that the lowest indentation depth can make all the four textured surfaces reach steady state. Surfaces with right-angled trapezoid textures on the right side are better for reducing the running-in stage, and surfaces with right-angled trapezoid textures on the left side are better to reduce wear. Compared with other textured surfaces, the total average friction forces can be reduced by 82.94%–91.49% for the case of the contact between the tip with radius R = 60rand the isosceles trapezoid textured surface. Besides,the total average friction forces increase with the tip radii due to that bigger tip will induce higher contact areas. This research proposes a detailed study on nanoscale reciprocating sliding contacts of textured surfaces, to contribute to design textured surfaces, reduce friction and wear.

关键词： Nanoscale Reciprocating sliding contacts Textured surface structure parameters Indentation depth

Integrated Optimization of structure and Control parameters for the Height Control System of a Vertical Spindle Cotton Picker

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Chinese Journal of Mechanical Engineering 2021年第6期34卷 405-416页

作者： Xingzheng Chen Congbo Li Rui Hu Ning Liu Chi Zhang College of Engineering and Technology Southwest UniversityChongqing400715China State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing400044China Department of Mechanical Engineering National University of SingaporeSingapore119077Singapore

Vertical picking method is a predominate method used to harvest cotton crop.However,a vertical picking method may cause spindle bending of the cotton picker if spindles collide with stones on the cotton field.Thus,how to realize a precise height control of the cotton picker is a crucial issue to be solved.The objective of this study is to design a height control system to avoid the collision.To design it,the mathematical models are established first.Then a multi-objective optimization model represented by structure parameters and control parameters is proposed to take the pressure of chamber without piston,response time and displacement error of the height control system as the opti-mization objectives.An integrated optimization approach that combines optimization via simulation,particle swarm optimization and simulated annealing is proposed to solve the model.Simulation and experimental test results show that the proposed integrated optimization approach can not only reduce the pressure of chamber without piston,but also decrease the response time and displacement error of the height control system.

关键词： Cotton picker Height control system structure parameters Control parameters Integrated optimization

Influence of structure parameters on aeroelastic stability for labyrinth seal based on energy method

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Propulsion and Power Research 2018年第4期7卷 288-295页

作者： Nengmao Wang Yanrong Wang Aimei Tian School of Energy and Power Engineering.Beihang University Beijing 100191China Collaborative Innovation Center for Advanced Aero-Engine Beijing 100191China School of Astronautics Beihang UniversityBeijing 100191China

Numerical analysis of turbomachinery based on energy method is used to predict the aeroelastic stability of the straight-through labyrinth seal by solving aerodynamic work and vibration modes has been compared.It's found that the increase of pressure ratio leads to the in the circumferential direction of the labyrinth seal corresponds to the number of vibrating nodal diameters.In order to investigate the influence of structure parameters,the effect of relative thickness of the tooth tip,the width of the seal cavity and the eccentricity of the rotor on the aeroelastic stability of the labyrinth seal has been studied.The result of numerical calculation shows that the change of the structural parameters can affect the aeroelastic stability of the labyrinth seal to a certain extent,and can be applied in the structural optimization.

关键词： Labyrinth seal Aeroelastic stability Energy method Nodal diameters structure parameters

Determination of structure parameters in strong-field ionization models of atoms

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Communications in Theoretical Physics 2020年第9期72卷 118-126页

作者：高轩鸿张磊焦志宏王国利赵松峰 College of Physics and Electronic Engineering Northwest Normal UniversityKey Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu ProvinceLanzhou 730070China School of Mathematics and Physics Lanzhou Jiaotong UniversityLanzhou 730070China

The Ammosov–Delone–Krainov(ADK) and Perelomov–Popov–Terent'ev(PPT) ionization models were widely used in strong-field physics and attosecond science due to their many attractive advantages such as simpler analytical formula, less computational demands, and satisfied accuracy of ionization rate. Based on the density-functional theory, we systematically determine accurate structure parameters of 25 atoms, 24 positive ions and 13 negative ions and tabulate for future applications. The wave function with correct asymptotic behavior is obtained by solving the time-independent Schr?dinger equation with B-spline basis sets and the accurate structure parameters are extracted from this wave function in the asymptotic region. The accuracies of structure parameters are carefully examined by comparing the ionization probabilities(or yields) calculated by PPT and ADK models with those of solving the threedimensional time-dependent Schr?dinger equation and the experimental data.

关键词： strong-field ionization models structure parameters density-functional theory

Research on Wireless Sensor Node for Measurement of Vegetation structure parameters

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Research on Wireless Sensor Node for Measurement of Vegetati...

Mode analysis and structure parameter optimization of a novel SiGe-OI rib optical waveguide

亚洲精细农业与计算机农业应用联合大会

作者： QU Yonghua 1 SUN Gang 2 1. State Key Laboratory of Remote Sensing Science Jointly Sponsored by Beijing Normal University and the Institute of Remote Sensing Applications of Chinese Academy of Sciences Beijing China. 100875 2. College of Information and electric engine China Agriculture University Beijing China. 100083

Based on WSN（Wireless Sensor Network）technology, this article designed a wireless sensor network node for vegetation parameter’s measurement, which can be used at large space scale and in long temporal series measurement activity. Preliminary validation of the wireless sensor network node’s algorithm and performance are presented in this article. The results indicated that the algorithm can estimate the vegetation parameters accurately from the measurement of transmittance of radiance through the canopy. The relative error of estimated LAI（Leaf Area Index） is 5%, and the LIDF（Leaf Inclination Distribution Function）agree with that of real vegetation structure basically. The sensitivity of designed wireless sensor network node is tested by measuring transmitted light intensity of projected direct LED light to leaves which have been punched with different density hole. The results indicted that the measured transmittance of leaves has high correlation with the holes density though it was also found that value of the former was slightly lower than that of the latter.

关键词： Wireless sensor node vegetation structure parameters

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Journal of Semiconductors 2009年第8期30卷 90-94页

作者：冯松高勇杨媛冯玉春 Department of Electronic Engineering Xi'an University of Technology Key Laboratories of Optoelectronic Devices and Systems Shenzhen University

The mode of a novel SiGe-OI optical waveguide is analyzed, and its single-mode conditions are derived. The Ge content and structure parameters of SiGe-OI optical waveguides are respectively optimized. Under an operation wavelength of 1300 nm, the structures of SiGe-OI rib optical waveguides are built and analyzed with Optiwave software, and the optical field and transmission losses of the SiGe-OI rib optical waveguides are analyzed. The optimization results show that when the structure parameters H, h, W are respectively 500 nm, 250 nm, 500 nm and the Ge content is 5%, the total power loss of SiGe-OI rib waveguides is 0.3683 dB/cm considering the loss of radiation outside the waveguides and materials, which is less than the traditional value of 0.5 dB/cm. The analytical technique for SiGe-OI optical waveguides and structure parameters computed by this paper are proved to be accurate and computationally efficient compared with the beam propagation method （BPM） and the experimental results.

关键词： SiGe-OI rib optical waveguides mode analysis Ge content structure parameters

Positioning error compensation for parallel mechanism with two kinematic calibration methods

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Chinese Journal of Aeronautics 2020年第9期33卷 2472-2489页

作者： Guohua ZHAO Dan WANG Liangbao LIU Jiangzhen GUO Wuyi CHEN He LI School of Mechanical Engineering and Automation Beihang UniversityBeijing 100083China School of Electric and Automatic Engineering Changshu Institute of TechnologyChcmgshu 215500China AVIC Aviation High-Technology Co. LtdNantong 226011China

Compared with serial mechanisms, the parallel mechanism(PM) theoretically exhibited higher positioning accuracy, dynamic performance, strength-to-weight ratio, and lower manufacturing cost, but they had not been widely used in the practical application. One key issue, positioning accuracy, which directly affected their performance and was greatly influenced by the errors of kinematic structure parameters was analyzed. To effectively enhance the positioning precision of PMs, a novel modeless kinematic calibration method, namely the split calibration, was presented and its compensation effect of the positioning error was comprehensively compared with that of an integrated method on two different types of PMs. A strange phenomenon-correct and incorrect identified results were derived from two different PMs by the same integrated method, respectivelywhich had not been reported yet was discovered, and the origin of it was revealed utilizing numerical simulations. Finally, respective merits and drawbacks of these two methods obtained in this paper provided underlying insights to guide the practical application of the kinematic calibration for PMs.

关键词： Compensation effect Kinematic calibration Parallel mechanism Positioning accuracy structure parameters

Influence of Structural parameters of Turbocharger Floating Bearing on Its Dynamic Characteristic Coefficients

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Journal of Beijing Institute of Technology 2017年第2期26卷 183-190页

作者： Junsheng Zhao Yuantong Gu Shengxian Yi Xuelong Lu School of Mechanical and Power Engineering North University of China School of Chemistry Physics and Mechanical EngineeringQueensland University of Technology

The structure parameters in an actual industrial production have a great influence on the coefficient of supercharger floating bearing dynamic characteristics,but there has been little systematic study so far.In this paper,the influence of structural parameters of the turbocharger floating bearing on its dynamic characteristic coefficientsis systematically investigated based on the theories of hydrodynamic lubrication and tribology.The influence of clearance ratio on eccentricity and the influence of internal to external radius ratios,and Sommerfeld number were analyzed.A new formula of responding characteristics of the oil film force caused by the displacement or velocity disturbance was deduced near an equilibrium in the steady state.Applying the newly developed formula,the dynamic characteristic was studied for floating bearings.Regularity for change of oil film stiffness and damping was analyzed with the structural parameters of floating bearing such as radius ratios and eccentricity.It has been found that the clearance ratio increases with eccentricity when the radius ratio is unchanged.The eccentricity decreases with the internal to external radius ratio of floating rings when the clearance ratio is constant.The absolute value of total principal stiffness and total main damping decrease with the clearance ratio and radius ratio of floating rings when the total cross damping is stable.The results and findings in this paper can contribute to nonlinear dynamics designs of turbocharger rotor-bearing systems.

关键词： turbocharger floating bearing structure parameters dynamic characteristic coefficient