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Visual Modeling of Rice Root Growth based on b-spline curve

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Wuhan University Journal of Natural Sciences 2022年第1期27卷 85-92页

作者： YANG Le TANG Zizong WU Panpan PENG Jun SHI Junlin LONG Lan School of Computer and Information Engineering Jiangxi Agricultural UniversityNanchang 330045JiangxiChina Key Laboratory of Agricultural Information Technology in Jiangxi Higher Education Institutions Nanchang 330045JiangxiChina

As a major food production crop in China,the growth and development of rice is an extremely complex systemic process,and the root system is the main organ for rice to obtain ***,3D modeling and visualization of the rice root system can help to further understand its morphology,structure and function,and provide an aid for scientific cultivation of rice and improving rice yield for decision *** this paper,a mathematical model of the rice root system is established based on the b spline curve combined with the L-system approach,using mathematical knowledge based on the 3D morphological characteristics of the real rice root *** b-spline curve is chosen to simulate this,and the recursive definition of b-spline curve and its formula are used to realize the modeling of the rice root system *** on the mathematical method of rice root system integration,the bending effect of rice root system at different periods and different growth positions is ***,the L-system combined with b-spline curve is used to construct a rice root system model and realize the rice root system visualization *** simulated image is closer to the real rice root system image in terms of morphological structure and has a strong sense of realism.

关键词： rice root system visual modeling L-system b-spline curve

Planning of a Single Flow Channel in Valve blocks based on Additive Manufacturing and the Ant Colony Algorithm

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CHINESE JOURNAL OF MECHANICAL ENGINEERING 2024年第1期37卷 1-12页

作者： Zhang, Jin Li, Ziyang Zhang, Yuying Liu, Yandong Li, Ying Kong, Xiangdong Yanshan Univ Sch Mech Engn Qinhuangdao 066004 Peoples R China Hebei Prov Key Lab Heavy Machinery Fluid Power Tra Qinhuangdao 066004 Peoples R China Natl & Local Joint Engn Res Ctr Adv Mfg Technol & Qinhuangdao 066004 Peoples R China State Key Lab Fluid Power & Mechatron Syst Hangzhou 310027 Peoples R China

As electro-hydrostatic actuator (EHA) technology advances towards lightweight and integration, the demand for enhanced internal flow pathways in hydraulic valve blocks intensifies. However, owing to the constraints imposed by traditional manufacturing processes, conventional hydraulic integrated valve blocks fail to satisfy the demands of a more compact channel layout and lower energy dissipation. Notably, the subjectivity in the arrangement of internal passages results in a time-consuming and labor-intensive process. This study employed additive manufacturing technology and the ant colony algorithm and b-spline curves for the meticulous design of internal passages within an aviation EHA valve block. The layout environment for the valve block passages was established, and path optimization was achieved using the ant colony algorithm, complemented by smoothing using b-spline curves. Three-dimensional modeling was performed using SolidWorks software, revealing a 10.03% reduction in volume for the optimized passages compared with the original passages. Computational fluid dynamics (CFD) simulations were performed using Fluent software, demonstrating that the algorithmically optimized passages effectively prevented the occurrence of vortices at right-angled locations, exhibited superior flow characteristics, and concurrently reduced pressure losses by 34.09%-36.36%. The small discrepancy between the experimental and simulation results validated the efficacy of the ant colony algorithm and b-spline curves in optimizing the passage design, offering a viable solution for channel design in additive manufacturing.

关键词： Hydraulic valve block Flow channel b-spline curve Additive manufacturing Ant colony algorithm

An optimization method on runner blades in bulb turbine based on CFD analysis

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Science China(Technological Sciences) 2011年第2期54卷 338-344页

作者： YANG Wei WU YuLin LIU ShuHong Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China State Key Laboratory of Hydroscience and Engineering Department of Thermal Engineering Tsinghua University Beijing 100084 China

In this paper an optimization method of the runner blades in a bulb turbine based on CFD analysis is *** the method the main scales of the turbine including guide vane,runner and draft are *** the runner blades are modified based on the present *** the optimization method the runner blade is expressed by spline surface with a gather of coordinate *** b-spline curve is used to keep the modified blades *** order to make the blade optimization simple and ef- ficient,one of the coordinates is fixed and only the angles of the points are changed according to different modification *** main optimization principles based on flow diagnosis are presented *** three principles are all based on the CFD analysis of the internal flow in bulb *** the purpose of method verification,the optimization method is used in a model bulb turbine.A three dimensional steady turbulent computation is carried out through the whole passage including the bulb body,guide vanes,runner and draft tube of the bulb turbine under seven different work *** SST k-ωturbulence model is used during the CFD analysis and the performance of the turbine can be *** runner blade is optimized according to the three optimization principles based on flow *** CFD analysis is conducted again on the optimized turbine and another modification is needed if the new turbine can’t satisfy the required *** of the computational results between the original turbine and an optimized one indicates that the optimization method is practical and does improve the performance of the bulb turbine.

关键词： bulb turbine CFD flow diagnose performance prediction SST k-ω turbulence model b-spline curve

A Class of spline curves with Four Local Shape Parameters

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Acta Mathematicae Applicatae Sinica 2017年第4期33卷 979-988页

作者： Yuan-peng ZHU Xu-li HAN School of Mathematics South China University of Technology School of Mathematics and Statistics Central South University

A class of spline curves with four local shape parameters, which includes the quartic spline curves with three local shape parameters given in Han [Xuli Han. A class of general quartic spline curves with shape parameters. Comput. Aided Geom. Design, 28：151-163 （2011）], is proposed. Without solving a linear system, the spline curves can be used to interpolate sets of points with C2 continuity partly or entirely. The shape parameters have a predictable adjusting role on the sp[ine curves.

关键词： b-spline curve quartic spline curve interpolation curve shape control shape parameter

A Novel Contour Tracing Algorithm for Object Shape Reconstruction Using Parametric curves

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Computers, Materials & Continua 2023年第4期75卷 331-350页

作者： Nihat Arslan Kali Gurkahraman Defence Technology Programme Sivas University of Science and TechnologySivas58070Turkey Department of Computer Engineering Sivas Cumhuriyet UniversitySivas58140Turkey

Parametric curves such as bézier and b-splines, originally developedfor the design of automobile bodies, are now also used in image processing andcomputer vision. For example, reconstructing an object shape in an image,including different translations, scales, and orientations, can be performedusing these parametric curves. For this, bézier and b-spline curves can be generatedusing a point set that belongs to the outer boundary of the object. Theresulting object shape can be used in computer vision fields, such as searchingand segmentation methods and training machine learning algorithms. Theprerequisite for reconstructing the shape with parametric curves is to obtainsequentially the points in the point set. In this study, a novel algorithm hasbeen developed that sequentially obtains the pixel locations constituting theouter boundary of the object. The proposed algorithm, unlike the methods inthe literature, is implemented using a filter containing weights and an outercircle surrounding the object. In a binary format image, the starting point ofthe tracing is determined using the outer circle, and the next tracing movementand the pixel to be labeled as the boundary point is found by the filter ***, control points that define the curve shape are selected by reducing thenumber of sequential points. Thus, the bézier and b-spline curve equationsdescribing the shape are obtained using these points. In addition, differenttranslations, scales, and rotations of the object shape are easily provided bychanging the positions of the control points. It has also been shown that themissing part of the object can be completed thanks to the parametric curves.

关键词： Contour tracing algorithm bézier curve b-spline curve object shape reconstruction

A New Processing Method for the Nonlinear Signals Produced by Electromagnetic Flowmeters in Conditions of Pipe Partial Filling

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Fluid Dynamics & Materials Processing 2021年第4期17卷 759-772页

作者： Yulin Jiang College of Information Engineering Zhongshan Polytechnic CollegeZhongshan528404China

When a pipe is partially filled with a given working liquid,the relationship between the electromotive force(EMF)measured by the sensor(flowmeter)and the average velocity is nonlinear and *** relationship varies with the inclination of the pipe,the fluid density,the pipe wall friction coefficient,and other ***fore,existing measurement methods cannot meet the accuracy requirements of many industrial *** this study,a new processing method is proposed by which the flow rate can be measured with an ordinary electromagnetic flowmeter even if the pipe is only partially ***,a b-spline curve fitting method is applied to a limited set of ***,matrix inversion required in the b-spline curve method is optimized in order to reduce the number of needed *** experimental tests prove that the proposed method can effectively measure the average flow velocity of the *** the fluid level of the pipeline is between 50%and 100%,the relative error is less than 3.5%.

关键词： Partially filled nonlinear signal online signal processing b-spline curve induced electromotive force(EMF)

Ship hull plate processing surface fairing with constraints based on b-spline

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Journal of Marine Science and Application 2005年第3期4卷 13-17页

作者： LIU Yu-jun ZHU Xiu-li JI Zhuo-shang Department of Naval Architecture Dalian University of Technology Dalian 116023 China

The problem of ship hull plate processing surface fairing with constraints based on b-spline is solved in this paper. The algorithm for b-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method.

关键词： b-spline curve fairing algorithm with constraints ship hull plate processing surface

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混合型参数的支持向量回归机建模及优化研究

混合型参数的支持向量回归机建模及优化研究

作者：王方成郑州大学

学位级别：硕士

制造业是国家的支柱产业,随着技术进步和产品多样化,使得制造过程中涌现了大量的复杂作用关系,具体表现为参数众多、参数与质量特性非线性相关以及输入的参数中不仅含有标量型参数还含有函数型参数等。函数型参数是一种区别于传统标量... 详细信息

制造业是国家的支柱产业,随着技术进步和产品多样化,使得制造过程中涌现了大量的复杂作用关系,具体表现为参数众多、参数与质量特性非线性相关以及输入的参数中不仅含有标量型参数还含有函数型参数等。函数型参数是一种区别于传统标量型参数的变量,该参数不是以“点”的形式存在而是以“函数(曲线)”的形式存在,其优化目标为确定一条合适的曲线方程而非某个特定水平值。实验设计是生产过程中参数优化的主要方法之一,其主要目的是分析出哪些输入参数显著地影响输出质量特性,以及如何确定输入参数的值,使其质量特性达到最佳。然而,传统基于实验设计的参数优化理论及方法,针对的仅是参数及质量特性均为标量型的情形,未对混合型参数的复杂作用关系过程进行研究。混合型参数也即是输入的参数不仅有函数型还有标量型。基于此,本文从函数型参数的角度对复杂作用关系过程的混合型参数优化问题进行研究,提出了基于SVR的含有函数型参数与标量型参数的混合回归建模与优化研究。具体研究内容如下:(1)针对函数型参数的自身建模问题,提出建立基于b样条曲线(b-spline curve)的函数型参数模型。b-spline curve是分段多项式曲线,它可以降低拟合曲线的阶数,对于复杂曲线的拟合效果较好,因此可以采用b-spline curve对函数型参数进行建模。首先采用超拉丁方设计随机获得一组数据点,进而获得b-spline curve的控制点,然后选择合适的次数和节点数,获得基函数,根据b-spline curve的表达式,实现函数型参数的自身建模。(2)针对含有函数型参数和标量型参数的复杂作用关系过程建模问题,提出建立基于支持向量回归机的函数型参数与标量型参数的混合回归模型。支持向量回归机是公认的关于小样本的最佳通用机器学习理论,在样本量较小的情况下可以建立较好的预测模型和寻优模型。首先根据已建立的函数型参数和标量型参数选择恰当的实验设计方法如带中心点的全因子设计或均匀设计等进行设计获得输出质量特性值,从而获得建模所需的训练集。根据训练集建立基于SVR的含有函数型参数的混合回归模型,然后选择恰当的评价指标对建立的SVR模型进行评价,最后采用遗传算法对模型进行寻优,获得较优的输入参数,从而获得期望的质量特性值。(3)最后,将本文的方法运用到复杂的仿真函数和高分子注塑过程优化案例中,仿真与案例研究表明,在取样困难、样本量较小的情况下,本文所提方法可以较好地建立函数型参数和标量型参数的混合回归模型。

关键词：复杂作用关系 b-spline curve SVR 遗传算法