scholarly journals Decision Maintenance Management Problems in Agriculture Engineering by Constructive Geometric Modeling Methods

Author(s):  
Tojiddin Juraev
Author(s):  
Yanbin Liu ◽  
Bing Hua ◽  
Dibo Xiao

AbstractThis paper presents the geometric modeling methods based on the class and shape function transformation (CST) technique for the hypersonic vehicle. First, the typical waverider configuration is considered to be the basic shape for the hypersonic vehicle, and then the CST method is applied to describe and build the improved geometric shape. On this basis, the aerodynamic forces and thrust are estimated according to the shock wave and Rayleigh flow theory. Furthermore, the model dynamic features using the CST method are analyzed in comparison to the basic shape. Finally, the simulation results show the effectiveness of this method for the hypersonic vehicle.


2017 ◽  
Vol 54 (9) ◽  
pp. 091402
Author(s):  
邹媛媛 Zou Yuanyuan ◽  
左克铸 Zuo Kezhu ◽  
李鹏飞 Li Pengfei ◽  
蔡尚 Cai Shang

Author(s):  
Jianhua Li ◽  
Hao Ling ◽  
Zhengchun Du

In the design of surface micromachined microelectromechanical systems (MEMS), there is a lack of effective modeling methods to refine the geometry of a MEMS device. This paper presents a method of incremental geometric modeling and mask synthesis for surface micromachined MEMS. In this method, propagation-mapping graphs are introduced to label all the affected entities in one variation operation, according to the characteristic of surface micromachining. Based on the propagation-mapping graphs constructed from a 3D geometric model and its process model, variation propagation and mapping are used to update these models. In order to keep manufacturability of these models, four manufacturability problems caused by variation propagation are analyzed and a manufacturability maintenance method is discussed. Variation propagation and mapping achieve incremental modeling for the geometric model and process model of a MEMS device. This method enables designers to modify a MEMS device in a quick and intuitive way. Finally the method is implemented and some test results are given.


Author(s):  
Alla Nesterenko ◽  
Oleksandr Duchenko

The paper is devoted to the methods of geometric modeling of plane curves given in the natural parameterization. The paper considers numerical modeling methods that make it possible to find the equation of curvature of the desired curve for different cases of the input data. The unknown curvature distribution coefficients of the required curve are determined by solving a system of nonlinear integral equations. Various numerical methods are considered to solve this nonlinear system. The results of computer implementation of the proposed methods for modeling two curvilinear contours with different initial data are presented. For the first curve, the input data are the coordinates of three points, the angles of inclination of the tangents at the extreme points and the linear law of curvature distribution. The second example considers an S-shaped curve with a quadratic law of curvature distributi.


2021 ◽  
Vol 264 ◽  
pp. 01029
Author(s):  
Тojiddin Juraev ◽  
Denis Voloshinov ◽  
Rustam Xujakulov ◽  
Abdurahim Qahharov ◽  
Dilorom Ubaydullayeva

There are considered the tasks of computer simulation of moldboard's surface in the article. The proposed solution is required in educational, research, and production processes. The researches were carried out using the constructive geometric modeling methods and systems. Objects of computer simulation were chosen the computer models of a directory curve, generative lines, and a frontal contour which are elements of the working surface. The geometric models of working surface elements developed based on research results were implemented in AutoCAD and SIMPLEX systems. The proposed simulation models can reduce the design period, simplify the geometric parameters' setting and facilitate the work of designers.


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