Medial Axis Transform of Planar Shapes With Free-Form Curve Boundary

Author(s):  
Qiang Fu ◽  
Zezhong C. Chen

Medial axis transform (MAT) is a very useful shape interrogation tool in NC tool path generation for pocket milling. This paper presents a new, efficient approach to calculating MATs of planar profiles with boundaries of free-form curves. The proposed approach is mainly based on profile boundary tracing and decomposition. By studying the basic elements of MAT and their geometric properties, several algorithms of finding contact circles are developed. The boundary tracing algorithm can handle profiles with/without internal holes. For a profile without internal holes, it is continuously divided into simpler sub-profiles while travelling along the boundary, and a tree data structure is adopted to keep track of the boundary decomposition process. For a profile with internal holes, it is divided into several simple profiles without internal holes. After generating the MAT of each simple profile, the completed MAT can be found by combining these MATs. This proposed approach is implemented and some illustrative samples are presented to demonstrate its advantages.

Author(s):  
A. K. M. B. Khoda ◽  
Ibrahim T. Ozbolat ◽  
Bahattin Koc

A novel modeling technique for porous tissue scaffolds with targeting the functionally gradient variational porosity with continuous material deposition planning has been proposed. To vary the porosity of the designed scaffold functionally, medial axis transformation is used. The medial axis of each layers of the scaffold is calculated and used as an internal feature. The medial axis is then used connected to the outer contour using an optimum matching. The desired pore size and hence the porosity have been achieved by discretizing the sub-regions along its peripheral direction based on the pore size while meeting the tissue scaffold design constraints. This would ensure the truly porous nature of the structure in every direction as well as controllable porosity with interconnected pores. Thus the desired controlled variational porosity along the scaffold architecture has been achieved with the combination of two geometrically oriented consecutive layers. A continuous, interconnected and optimized tool-path has been generated for successive layers for additive-manufacturing or solid free form fabrication process. The proposed methodology has been computationally implemented with illustrative examples. Furthermore, the designed example scaffolds with the desired pore size and porosity has been fabricated with an extrusion based bio-fabrication process.


2020 ◽  
Vol 14 ◽  
Author(s):  
Shefali Singhal ◽  
Poonam Tanwar

Abstract:: Now-a-days when everything is going digitalized, internet and web plays a vital role in everyone’s life. When one has to ask something or has any online task to perform, one has to use internet to access relevant web-pages throughout. These web-pages are mainly designed for large screen terminals. But due to mobility, handy and economic reasons most of the persons are using small screen terminals (SST) like mobile phone, palmtop, pagers, tablet computers and many more. Reading a web page which is actually designed for large screen terminal on a small screen is time consuming and cumbersome task because there are many irrelevant content parts which are to be scrolled or there are advertisements, etc. Here main concern is e-business users. To overcome such issues the source code of a web page is organized in tree data-structure. In this paper we are arranging each and every main heading as a root node and all the content of this heading as a child node of the logical structure. Using this structure, we regenerate a web-page automatically according to SST size. Background:: DOM and VIPS algorithms are the main background techniques which are supporting the current research. Objective:: To restructure a web page in a more user friendly and content presenting format. Method Backtracking:: Method Backtracking: Results:: web page heading queue generation. Conclusion:: Concept of logical structure supports every SST.


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