Sketching input for computer aided engineering

The design process often begins with a graphical description of the proposed device or system and sketching is the physical expression of the design engineer’s thinking process. Computer Aided Design is a technique in which man and machine are blended into a problem solving team, intimately coupling the best characteristics of each. Solid modelling is developed to act as the common medium between man and the computer. At present it is achieved mainly by designing with volumes and hence does not leave much room for sketching input, the traditional physical expression of the thinking process of the design engineer. This thesis describes a method of accepting isometric free hand sketching as the input to a solid model. The design engineer is allowed to make a sketch on top of a digitizer indicating (i) visible lines (ii) hidden lines (iii) construction lines (iv) centre lines (v) erased lines and (vi) redundant lines as the input. The computer then process this sketch by identifying the line segments, fitting the best possible lines, removing the erased lines, ignoring the redundant lines and finally merging the hidden lines and visible lines to form the lines in the solid in an interactive manner. The program then uses these lines and the information about the three dimensional origin of the object and produces three dimensional information such as the faces, loops, holes, rings, edges and vertices which are sufficient to build a solid model. This is achieved in the following manner. The points in the sketch is first written into a file. The computer then reads this file, breaks the group of points into sub-groups belonging to individual line segments, fits the best lines and identify the vertices in two dimensions. These improved lines in two dimensions are then merged to form the lines and vertices in the solid. These lines are then used together with the three dimensional origin (or any other point) to produce the wireframe model in three dimensions. The loops in the wireframe models are then identified and surface equations are fitted to these loops. Finally all the necessary inputs to build a B-rep solid model are produced

Optimal choice of machine tool for a machining job in a CAE environment

Developments in cutting tools, coolants, drives, controls, tool changers, pallet changers and the philosophy of machine tool design have made ground breaking changes in machine tools and machining processes. Modern Machining Centres have been developed to perform several operations on several faces of a workpiece in a single setup. On the other hand industry requires high value added components, which have many quality critical features to be manufactured in an outsourcing environment as opposed to the traditional in-house manufacture. The success of this manufacture critically depends on matching the advanced features of the machine tools to the complexity of the component. This project has developed a methodology to represent the features of a machine tool in the form of an alphanumeric string and the features of the component in another string. The strings are then matched to choose the most suitable and economical Machine Tool for the component’s manufacture. Literature identified that block structure is the way to answer the question ‘how to systematically describe the layout of such a machining centre’. Incomplete attempts to describe a block structure as alphanumeric strings were also presented in the literature. Survey on sales literature from several machine tool suppliers was investigated to systematically identify the features need by the user for the choice of a machine tool. Combining these, a new alphanumeric string was developed to represent machine tools. Using these strings as one of the ‘key’s for sorting a database of machine tools was developed. A supporting database of machine tools was also developed. Survey on machining on the other hand identified, that machining features can be used as a basis for planning the machining of a component. It analysed various features and feature sets proposed and provided and their recognition in CAD models. Though a vast number of features were described only two sets were complete sets. The project was started with one of them, (the other was carrying too many unwanted details for the task of this project) machining features supported by ‘Expert Machinist’ software. But when it became unavailable a ‘Feature set’ along those lines were defined and used in the generation of an alphanumeric string to represent the work. Comparing the two strings led the choice of suitable machines from the database. The methodology is implemented as a bolt on software incorporated within Pro/Engineer software where one can model any given component using cut features (mimicking machining operation) and produce a list of machine tools having features for the machining of that component. This will enable outsourcing companies to identify those Precision Engineers who have the machine tools with the matching apabilities. Supporting software and databases were developed using Access Database, Visual Basic and C with Pro/TOOLKIT functions. The resulting software suite was tested on several case studies and found to be effective.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Quantitative model for efficient temporal targeting of tumor cells and neovasculature

The combination of cytotoxic therapies and anti-angiogenic agents is emerging as a most promising strategy in the treatment of malignant tumors. However, the timing and sequencing of these treatments seem to play essential roles in achieving a synergic outcome. Using a mathematical modeling approach that is grounded on available experimental data, we investigate the spatial and temporal targeting of tumor cells and neovasculature with a nanoscale delivery system. Our model suggests that the experimental success of the nanoscale delivery system depends crucially on the trapping of chemotherapeutic agents within the tumor tissue. The numerical results also indicate that substantial further improvements in the efficiency of the nanoscale delivery system can be achieved through an adjustment of the temporal targeting mechanism.Comment: 17 pages, 5 figure

Characterization of brain cancer stem cells: a mathematical approach

Abstract Objectiv

Diffeomorphic approximation of Sobolev homeomorphisms

Every homeomorphism h : X -> Y between planar open sets that belongs to the Sobolev class W^{1,p}(X,Y), 1<p<\infty, can be approximated in the Sobolev norm by diffeomorphisms.Comment: 21 pages, 5 figure

Whirl mappings on generalised annuli and the incompressible symmetric equilibria of the dirichlet energy

In this paper we show a striking contrast in the symmetries of equilibria and extremisers of the total elastic energy of a hyperelastic incompressible annulus subject to pure displacement boundary conditions.Indeed upon considering the equilibrium equations, here, the nonlinear second order elliptic system formulated for the deformation u=(u1,…,uN) : EL[u,X]=⎧⎩⎨⎪⎪Δu=div(P(x)cof∇u)det∇u=1u≡φinX,inX,on∂X, where X is a finite, open, symmetric N -annulus (with N≥2 ), P=P(x) is an unknown hydrostatic pressure field and φ is the identity mapping, we prove that, despite the inherent rotational symmetry in the system, when N=3 , the problem possesses no non-trivial symmetric equilibria whereas in sharp contrast, when N=2 , the problem possesses an infinite family of symmetric and topologically distinct equilibria. We extend and prove the counterparts of these results in higher dimensions by way of showing that a similar dichotomy persists between all odd vs. even dimensions N≥4 and discuss a number of closely related issues