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A new method to solve the Reynolds equation including mass-conserving cavitation by physics informed neural networks(PINNs)with both soft and hard constraints

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Friction 2024年第6期12卷 1165-1175页

作者： yinhu XI Jinhui DENG Yiling LI School of Mechanical Engineering Anhui University of Science and TechnologyHuainan 232001China Ericsson AB Datalinjen 3Linköping 58330Sweden

In this work,a new method to solve the Reynolds equation including mass-conserving cavitation by using the physics informed neural networks(PINNs)is *** complementarity relationship between the pressure and the void fraction is *** are several difficulties in problem solving,and the solutions are ***,the difficulty for considering the pressure inequality constraint by PINNs is solved by transferring it into one equality constraint without introducing *** the void fraction inequality constraint is considered by using the hard constraint with the max-min ***,to avoid the fluctuation of the boundary value problems,the hard constraint method is also utilized to apply the boundary pressure values and the corresponding functions are ***,for avoiding the trivial solution the limitation for the mean value of the void fraction is *** results are validated against existing data,and both the incompressible and compressible lubricant are *** agreement can be found for both the domain and domain boundaries.

关键词： Reynolds equation mass-conserving cavitation physics informed neural networks hard constraints trivial solution

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改进YOLOv5模型的草莓检测方法研究

中国农机化学报 2025年第1期46卷 213-219页

作者：彭勇乔印虎张春燕姚杰包殿令安徽工程大学机械工程学院安徽芜湖241000 安徽科技学院机械工程学院安徽凤阳233100

草莓检测对草莓的自动化采摘具有重要的意义和价值,针对目前草莓模型检测精度较低、模型占用较大等问题,基于深度学习技术,提出一种改进YOLOv5的目标检测方法。首先,使用Ghost模块对YOLOv5主干网络进行优化,降低模型参数量和复杂度;其次... 详细信息

草莓检测对草莓的自动化采摘具有重要的意义和价值,针对目前草莓模型检测精度较低、模型占用较大等问题,基于深度学习技术,提出一种改进YOLOv5的目标检测方法。首先,使用Ghost模块对YOLOv5主干网络进行优化,降低模型参数量和复杂度;其次,使用坐标注意力模块CA,提升模型对草莓关键特征的关注;然后将YOLOv5中的定位损失替换为SIoU,考虑边界框回归之间的向量角度。结果表明,该模型的平均精度均值为94.8%,相较于目前经典的目标检测模型,检测能力提升显著,一张图片的预测时间为25.2 ms,模型大小仅为10.4 MB,具有较快的推理速度且模型尺寸较小。为草莓检测提供更加准确快捷的检测方法,更为容易地应用到移动式和嵌入式设备中。

关键词：草莓深度学习 YOLOv5 损失函数目标检测

Numerical Study on the Morphology of a Re-Ignited Laminar Partially Premixed Flame with a Co-Axial Pilot Flame

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Journal of Thermal Science 2020年第1期29卷 90-97页

作者： WU Zejun KANG yinhu HE Xiaomin College of Aerospace Engineering Chongqing UniversityChongqing 400044China School of Energy and Power Engineering Chongqing UniversityChongqing 400045China Jiangsu Province Key Laboratory of Aerospace Power System Nanjing 210016China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Re-ignited partially premixed flame(PPF)is a quite extensive flame type in real applications,which is directly relevant to the local and global extinction and re-ignition *** authors designed a model burner to establish laminar re-ignited *** simulations were carried out to reveal the morphology of laminar re-ignited *** on the distributions of temperature,heat release and radicals,the morphologies of re-ignited flames were explored.W-shaped flames were formed under pilot-lean ***-shaped and y-shaped flames were formed under pilot-rich *** w-shaped and y-shaped flames had a triple-flame *** re-ignited flames can stand beyond the rich flammability ***,OH distributions indicated both pilot flame and re-ignited flame well as it rapidly increased near the flame *** concentration did not increase visibly while CH2O concentration mildly increased during the mild re-ignition process in the pre-zone of the re-ignited *** to the results of 0-D simulations using closed homogeneous reactor,both OH and CH2O reduced ignition time *** results of this work are helpful for understanding re-ignited PPF more closely.

关键词： re-ignited flame partially premixed flame flame morphology numerical simulation

Rigorous and integrated self-calibration model for a large-field-of-view camera using a star image

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Chinese Journal of Aeronautics 2023年第12期36卷 375-389页

作者： yinhu ZHAN Shaojie CHEN Chao ZHANG Ruopu WANG Institute of Geospatial Information Information Engineering UniversityZhengzhou 450001China

This paper proposes a novel self-calibration method for a large-FoV(Field-of-View)camera using a real star ***,based on the classic equisolid-angle projection model and polynomial distortion model,the inclination of the optical axis is thoroughly considered with respect to the image plane,and a rigorous imaging model including 8 unknown intrinsic parameters is ***,the basic calibration equation based on star vector observations is ***,the partial derivative expressions of all 11 camera parameters for linearizing the calibration equation are deduced in detail,and an iterative solution using the least squares method is ***,simulation experiment is designed,results of which shows the new model has a better performance than the old *** last,three experiments were conducted at night in central China and 671 valid star images were *** results indicate that the new method obtains a mean magnitude of reprojection error of 0.251 pixels at a 120°FoV,which improves the calibration accuracy by 38.6%compared with the old calibration model(not considering the inclination of the optical axis).When the FoV drops below 20°,the mean magnitude of the reprojection error decreases to 0.15 pixels for both the new model and the old *** stars instead of manual control points are used,the new method can realize self-calibration,which might be significant for the long-duration navigation of vehicles in some unfamiliar or extreme environments,such as those of Mars or Earth’s moon.

关键词： Camera calibration Calibration model Imaging models Lens distortion Star image

The “Fingerprint” of a freshwater microalga Scenedesmus sp. LX1:Visualizing the composition of its soluble algal products

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Chinese Chemical Letters 2019年第5期30卷 1126-1128页

作者： yinhu Wu Yin Yu Hongying Hu Environmental Simulation and Pollution Control State Key Joint Laboratory State Environmental Protection Key Laboratory of Microorganism Application and Risk Control(SMARC)School of EnvironmentTsinghua UniversityBeijing 100084China State Key Laboratory of Environmental Criteria and Risk Assessment Research Center of Water Pollution Control TechnologyChinese Research Academy of Environmental SciencesBeijing 100012China Shenzhen Environmental Science and New Energy Technology Engineering Laboratory Tsinghua-Berkeley Shenzhen InstituteShenzhen 518055China

In this study,a fingerprint analysis method along with the EEM fluorescence spectra was used to characterize the SAPs released by Scenedesmus ***1 during the growth *** fractionation was used firstly to divide the SAPs into six resin fractions,and then size exclusion chromatography(SEC)was performed to separate each resin fraction into several subfractions with different molecular weights(MW).The fingerprint graph integrated the information revealed by resin fractionation as well as that by SEC,showing that main components of SAPs changed from the hydrophilic subfractions with MW of 10~2-10~3 Da to the hydrophobic subfractions with MW of 10~3-10~4 *** these results with the EEM fluorescence spectra of different resin fractions,the change of the main matters within SAPs could be inferred.

关键词： Microalgae Soluble algal products Fingerprint analysis Resin fractionation Molecular weight distribution

Stripe theory based numerical method for solving asymmetrical hysteresis of friction force in linear rolling guideways

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Science China(Technological Sciences) 2016年第9期59卷 1320-1327页

作者： ZHAO Yang XI yinhu MAO JunHong WONG Patrick Pat Lam Theory of Lubrication and Bearing Institute Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System Xi'an Jiaotong University Department of Mechanical and Biomedical Engineering City University of Hong Kong

Linear rolling guideways(LRGs) play an important role in precision engineering. In the pre-rolling region, the hysteretic friction force exerts great impacts on the positioning accuracy. Numerical and experimental studies of the hysteresis of friction force are presented in this paper. A model, which is based on the stripe theory and the simplified theory of rolling contact, is built to describe the transient hysteresis of the friction force. Then, the model is modified by taking the anelasticity effect into consideration. Experimentally, a linear motor direct-drive setup is utilized to measure the transient asymmetrical hysteresis of the friction force in the pre-rolling region of an LRG. The influences of the pre-rolling displacement and the dwelling time on the asymmetrical hysteresis of the friction force are studied. The numerical and experimental results are well correlated, which shows good accuracy of the model. The transient asymmetrical hysteresis of friction force in the pre-rolling region of LRGs can thus be determined using the model.

关键词： pre-rolling friction anelasticity hysteresis linear rolling guideway

Dynamic Modeling and Analysis ofWind Turbine Blade of Piezoelectric Plate Shell

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Sound & Vibration 2019年第1期53卷 14-24页

作者： yinhu Qiao Chunyan Zhang Jiang Han School of Mechanical Engineering College Anhui Science and Technology UniversityFengyang233100China School of Mechanical Engineering Hefei University of TechnologyHefei230000China

This paper presents a theoretical analysis of vibration control technology of wind turbine blades made of piezoelectric intelligent *** design of the blade structure,which is made from piezoelectric material,is approximately equivalent to a flat shell *** differential equations of piezoelectric shallow shells for vibration control are derived based on piezoelectric laminated shell *** this basis,wind turbine blades are simplified as elastic piezoelectric laminated *** establish the electromechanical coupling system dynamic model of intelligent structures and the dynamic equation of composite piezoelectric flat shell structures by analyzing simulations of active vibration *** results show that,under wind load,blade vibration is reduced upon applying the control voltage.

关键词： Wind-turbine blade smart structure laminated shallow shell dynamics modeling

Optimized Design of H-Type Vertical Axis Wind Airfoil at Multiple Angles of Attack

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Fluid Dynamics & Materials Processing 2023年第10期19卷 2661-2679页

作者： Chunyan Zhang Shuaishuai Wang yinhu Qiao Zhiqiang Zhang School of Mechanical Engineering Anhui Science and Technology UniversityFengyang233100China School of Mechanical Engineering Anhui Polytechnic UniversityWuhu241000China

Numerical simulations are conducted to improve the energy acquisition efﬁciency of H-type vertical axis wind turbines through the optimization of the related blade airfoil aerodynamic *** Bézier curve is initi-ally used toﬁt the curve proﬁle of a NACA2412 airfoil,and the moving asymptote algorithm is then exploited to optimize the design of the considered H-type vertical-axis wind-turbine blade airfoil for a certain attack *** results show that the maximum lift coefﬁcient of the optimized airfoil is 8.33%higher than that of the original *** maximum lift-to-drag ratio of the optimized airfoil exceeds the maximum lift-to-drag ratio of the ori-ginal airfoil by 11.22%.Moreover,the power coefﬁcient is increased by 12.19%and the torque coefﬁcient of the wind turbine is signiﬁcantly improved.

关键词： H-type vertical axis wind turbine Bézier curves moving asymptote algorithm airfoil optimization

An experimental method for measuring friction behaviors of linear rolling guides

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Chinese Science Bulletin 2014年第29期59卷 3912-3918页

作者： yinhu Xi Yuan Zhou Wei Zhang Junhong Mao Theory of Lubrication and Bearing Institute Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing SystemSchool of Mechanical EngineeringXi’an Jiaotong University

Friction behaviors of linear rolling guides(LRGs)are determined by many factors and are crucial for precision *** is difficult to create an expression to describe the friction behaviors exactly and completely.A new experimental method for measuring the friction behaviors of one LRG individually was developed,and linear motor direct drive technology is utilized in the experiment *** position signal is acquired by a grating,and the friction of the LRG is deduced by the product of the mass of the moving part and its *** the experiment,the LRG can move with the friction only,and the friction transition from normal rolling to prerolling stage was *** asperities’deformations were utilized to explain *** loops and internal loops were *** results indicate the non-local memory of the LRG,and the historical trajectory have an important impact on the friction behaviors of LRGs in the pre-rolling stage.

关键词：直线滚动导轨摩擦行为测量验方精确定位驱动技术直线电机位置信号