Computer-aided Design Problems Research Articles

Mesh segmentation via geodesic curvature flow

Perceptually meaningful segmentation of a mesh is one of the fundamental, yet unconquered problems in computer-aided design and geometry modeling. A critical component that affects the result of se...

Infological modeling method in knowledge engineering for solution of computer-aided design problems

Infological modeling method in knowledge engineering for solution of computer-aided design problems

Optmization of «fuel electric generator – electric motor» system in CAD

The main problems of computer-aided design of «fuel electric generator – asynchronous electric motor» systems stem from the fact that these systems can є t be considered separately during optimization. Theoretically, the increase in production efficiency due to CAD, which ensures the optimization of equipment parameters for global connectivity, is proved. A computational model of «fuel electric generator – asynchronous electric motor» system with comparable energy parameters of the source and the consumer, which takes into account the processes that occur not only in the electric motor, but also in the generator is proposed. The concept of a «global connectivity» between the arguments of a projected object as a characteristic of the relationship between the parameters of subsystems is suggested, when such connection dominates over others. In the sense that it is present in the largest number of computational models, in connection with which, its calculation has a decisive influence on the design object as a whole. The method of calculation of «fuel electric generator – asynchronous electric motor» systems in CAD is proposed, in which the intermediate objective function is not one of the consumer qualities of the object, but the nominal global connectivity between the elements of the system. In Odessa, LLC «Specialized Energetic Enterprise «Energo-KOM» (Ukraine), a CAD test of electrical equipment «OPTIGLOC» is conducted, which is based on the proposed models and methods. As the object of computer-aided design, «diesel generator – asynchronous induction motor» system is used. As a result of the tests it is found that the use of the CAD «OPTIGLOC» allows to reduce the specific fuel consumption in the generator by 5.3 %. At the same time, the service life of the system and the stability of its technical tasks do not change, and the design time is reduced by an average of 13.7 %.

PROJECTING A HYDROGRAPHIC MAP OF THE REPUBLIC OF MACEDONIA

Bezier and B-spline curves are among the most powerful tools used for complex graphical approximation. In this paper, we will use them to recreate the hydrographic map of the Republic of Macedonia. The results obtained in this paper show that cubic spline curves have smaller average deviation in respect to B-spline curves, in contrast to Bezier curves. The results and the images are obtained by using the software package Wolfram Mathematica. Key words: Bezier curves; B-spline; cubic spline REFERENCES [1] Vera B. Anand: Computer Graphics and Geometric Modeling for Engineers, John Wiley & Sons Inc. 1996. [2] V. Andova, S. Atanasova, K. Bacev, Gj. Peev, G.Kostov: Approximation of map borders using Mathematica, ETAI (2015). [3] R. H. Bartels, J. C. Beatty, B. A. Barsky: An Introduction to Splines for Use in Computer Graphics and Geometric Modeling, Morgan Kaufmann Publishers Inc. 1987. [4] R. C. Beach: An Introduction to the Curves and Surfaces of Computer-Aided Design, Van Nostrand Reinhold, 1991. [5] E. Cohen: Discrete B-splines and Subdivision Techniques in Computer Aided Geometric Design and Computer Graphics, International Association for Bridge and Structural Engineering, 1979. [6] C. De Boor: A Practical Guide to Splines, Revised Edition, Springer, 1978. [7] G. Farin: Curves and Surfaces for CAGD. A Practical Guide, fifth edition, Academic Press, 2002. [8] G. Farin, J. Hoschek, M.-S. Kim: Handbook of Computer Aided Geometric Design, Elsevier, 2002. [9] G. Farin: NURBS: From Projective Geometry to Practical Use, 2nd edition, AK Peters, 1999. [10] J. Fiorot, P. Jeannin: Rational Curves and Surfaces, Wiley, 1992. [11] J. Gallier: Curves and Surfaces. In: Geometric Modeling:Theory and Algorithms, Morgan Kofman Publishers,2000. [12] G. G. Lorentz: Bernstein Polynomials, University of Toronto Press, 1953. [13] R. F. Riesenfeld: Applications of B-spline Approximation to Geometric Problems of Computer-Aided Design, Syracuse University, 1973. [14] D. Rogers: An Introduction to NURBS with Historical Perspective, Elsevier, 2001. [15] W. Rudin: Real and Complex Analysis, McGraw-Hill Higher Education, 1986. [16] D. Salomon: Curves and Surfaces for Computer Graphic, Springer, 2006. [17] S. Wagon: Mathematica in Action Problem Solving Through Visualization and Computation, Springer, 2010. [18] S. Wolfram: The Mathematica Book, Fifth Edition, Wolfram Media, 2003.

Software for calculation of belt conveyors at their computer-aided design

The article is devoted to developing algorithms and software for automated calculation of the main traction characteristics of the conveyor for the second option, involves designing the conveyor for installation in a particular formulation, when given the receiving capacity, operating performance, circuit tracks, production type, method of installation of the load it is determined velocity, width, type and strength of the belt, power and traction drive factor, tensioner stroke, drive starting time, force of the braking device and size of the assembly units. The basis is known calculation method. There are considered various options of the conveyor – single and double-drum, with the presence of the clamping roller or belt, with rigid kinematic coupling or connection between independent drums. It is formalized the second stage of the problem of computer-aided design of mine conveyors, using known methods approved by the State Standard. It is developed visual form to the user interface based on the example of the basic parameters of mine conveyor which is established in the programming language Delphi 7. To automate the calculation of these parameters is used programming language. The visual forms of the calculating algorithm realization of traction capacity of the conveyor drive are given.

Генетический алгоритм проектирования основных переходов в САПР технологических процессов ковки валов

The application of the statements from the theory of developing genetic algorithms to solve the problems of computer-aided design of forging preparatory transitions demonstrates that the suggested approach seems reasonable for solving problems in CAPP of shaft press-forging, which are difficult to formalize. The paper describes developed genetic algorithm for computer-aided design of shaft press-forging main transitions. The standard procedure of the main forging transitions is exemplified by rotor-type shaft forging. The authors discuss the algorithm of forming the geometry of the steps on blanks in each transition; introduce a concept of relatively displaced volume as a value that correlates with the duration of forging. On the basis of this concept, the condition for the forging process termination in each transition is formalized. The genetic algorithm for computer-aided design of main transitions of shaft press-forging is developed on the principles of the theory of probability and mathematical statistics. The algorithm has the properties of self-improvement and auto-adjustment to manufacturing conditions. Thus, it simplifyes CAPP system user work and creates preconditions for a successful replication of the shaft press-forging system at various enterprises.

Knot calculation for spline fitting via sparse optimization

Curve fitting with splines is a fundamental problem in computer-aided design and engineering. However, how to choose the number of knots and how to place the knots in spline fitting remain a difficult issue. This paper presents a framework for computing knots (including the number and positions) in curve fitting based on a sparse optimization model. The framework consists of two steps: first, from a dense initial knot vector, a set of active knots is selected at which certain order derivative of the spline is discontinuous by solving a sparse optimization problem; second, we further remove redundant knots and adjust the positions of active knots to obtain the final knot vector. Our experiments show that the approximation spline curve obtained by our approach has less number of knots compared to existing methods. Particularly, when the data points are sampled dense enough from a spline, our algorithm can recover the ground truth knot vector and reproduce the spline.

A discrete dynamic convexized method for VLSI circuit partitioning

In this paper, we consider the circuit partitioning problem, which is a fundamental problem in computer-aided design of very large-scale-integrated circuits. We formulate the problem as an equivalent constrained integer programming problem by constructing an auxiliary function. A global search method, entitled the dynamic convexized method, is developed for the integer programming problem. We modify the Fiduccia–Mattheyses (FM) algorithm, which is a fundamental partitioning algorithm for the circuit partitioning problem, to minimize the auxiliary function. We show both computationally and theoretically that our method can escape successfully from previous discrete local minimizers by taking increasing values of a parameter. Experimental results on ACM/SIGDA and ISPD98 benchmarks show up to 58% improvements over the well-known FM algorithm in terms of the best cutsize. Furthermore, we integrate the algorithm with the state-of-the-art practical multilevel partitioner MLPart. Experiments on the same set of benchmarks show that the solutions obtained in this way has 3–7% improvements over that of the MLPart.

Application of Multi-Objective Optimization Model in Design of Photovoltaic Architecture

With the increasingly serious crisis of the energy problem, all around the world, the application of solar energy has become an approach of solving the problem undoubtedly. In recent years, due to the rapid development of Chinese photovoltaic (PV) industry, the emergence of PV buildings is more and more widely in the domestic. The current trend is to apply Computer-Aided Design (CAD) software to realize the design of Building Integrated Photovoltaic (BIPV). The core problem of CAD is to obtain the best solution to a laying scheme of PV cell. In this paper, the design problem of PV building is concerned about. Through the research on the multi-objective optimization theory, it is to establish the model of multi-objective optimization that can meet these two objectives of the largest total annual solar photovoltaic power generation, yet the smallest possible the unit cost of power generation. The model can be solved by MATLAB using ideal point method. In order to detail explain the application of model and verify it, the design of PV cabin, in Datong area of Shanxi Province, is as an example. The study has laid the foundation for the development of CAD in the future.

The concept of creating of computer-aided design of process equipment

The solution of creating a computer-aided design problem of technological equipment by applying a systematic approach to the methodology of the machine system and its information and the mathematical provisions constructing is offered, methods of new technical solutions searching are used

Transistor sizing of custom high-performance digital circuits with parametric yield considerations

Transistor sizing is a classic computer-aided design problem that has received much attention in the literature. Given the increasing importance of process variation in deep sub-micron circuits and the wide-spread use of statistical methods, the sizing problem for such circuits warrants revisiting. This paper addresses transistor sizing as one that can be solved via interior point nonlinear optimization with an objective function that is directly dependent on statistical process variation. Our technique automatically adjusts transistor sizes to maximize parametric yield at a given timing performance, or to maximize performance at a required parametric yield. Our results show that for process variation sensitive circuits, consisting of thousands of independently tunable transistors, a statistically aware tuner can give more robust, higher yield solutions when compared to deterministic circuit tuning and is thus an attractive alternative to the Monte Carlo methods that are typically used to size transistors in such circuits. To the best of our knowledge, this is the first working system to optimize transistor sizes in custom circuits using a process variation aware tuner.

Improved Hybrid Taboo Search with its Application in Computer-Aided Optimization Problem

A new improved algorithm of Taboo Search (TS), namely, Hybrid Taboo Search (HTS) is first introduced and tried for several test functions having multiple local optima. Here, Taboo Search was improved by combining Immune Arithmetic (IA) and Simulated Annealing (SA). Several strategies to improve the TS have been presented before, but the focus here is on the novelty, availability and precision of algorithm. There are several optimization problems in computer-aided design, so the article used the improved HTS in computer-aided optimization problems, the performance of which is compared with the performance of conventional TS (TS). Results show that HTS plays an important role in solving computer-aided optimization problems with the effectiveness and higher accuracy.

Solving polynomial systems using no-root elimination blending schemes

Searching for the roots of (piecewise) polynomial systems of equations is a crucial problem in computer-aided design (CAD), and an efficient solution is in strong demand. Subdivision solvers are frequently used to achieve this goal; however, the subdivision process is expensive, and a vast number of subdivisions is to be expected, especially for higher-dimensional systems. Two blending schemes that efficiently reveal domains that cannot contribute by any root, and therefore significantly reduce the number of subdivisions, are proposed. Using a simple linear blend of functions of the given polynomial system, a function is sought after to be no-root contributing, with all control points of its Bernstein–Bézier representation of the same sign. If such a function exists, the domain is purged away from the subdivision process. The applicability is demonstrated on several CAD benchmark problems, namely surface–surface–surface intersection (SSSI) and surface–curve intersection (SCI) problems, computation of the Hausdorff distance of two planar curves, or some kinematic-inspired tasks.

Computer design of electrostatic systems of charge particle optics: Systems with spherical electrodes and a fine-structure grid

Problems in computer-aided design of 3D optical systems for charged particle optics are analyzed. The results of simulation of electron-optical systems of optoelectronic transducers with two cathode packs (spherical cathode-plane fine-structure grid as the accelerating electrode and plane cathode-spherical fine-structure grid) are considered. We note a low technological efficiency of such structures and unsatisfactory quality (as it regards some parameters) of the image being recorded due to spherical electrodes and a fine-structure grid in the cathode pack. Numerical analysis of the effect of adjustment of the design on the quality of the image being recorded is carried out.

Placement and Routing for Cross-Referencing Digital Microfluidic Biochips

Computer-aided design problems of digital microfluidic biochips are receiving much attention, and most of the previous works focus on direct-addressing biochips. In this paper, we solve the placement and droplet routing problem in cross-referencing biochips. In these biochips, the electrodes are addressed in a row-column manner, which may cause electrode interference that prevents simultaneous movements of multiple droplets. We propose a routing algorithm that solves the droplet routing problem directly. A two-coloring graph-theoretic method is used in our router to detect and prevent the electrode interference. In addition, we propose an integer linear programming based method to solve the placement problem. Our method considers the characteristics of cross-referencing biochips and is aware of droplet routing. Real-life benchmarks are used to evaluate the proposed methods. Compared with previous works, our router improves on average 4% in routing time and 58% in runtime. It can route all the benchmarks within the time limits, while the latest work fails in some cases. Moreover, experimental results show that by running our router on the placement result generated by our method and those generated by the latest work, an average improvement of 11%, 29%, 54%, and 46% in the maximum routing time, average routing time, stalling steps, and cell usage can be achieved.

Exponential space complexity for OBDD-based reachability analysis

Ordered binary decision diagrams (OBDDs) are one of the most common dynamic data structures for Boolean functions. Nevertheless, many basic graph problems are known to be PSPACE-hard if their input graphs are represented by OBDDs. Computing the set of nodes that are reachable from some source s ∈ V in a digraph G = ( V , E ) is an important problem in computer-aided design, hardware verification, and model checking. Until now only exponential lower bounds on the space complexity of a restricted class of OBDD-based algorithms for the reachability problem have been known. Here, the result is extended by presenting an exponential lower bound for the general reachability problem. As a by-product a general exponential lower bound is obtained for the computation of OBDDs representing all connected node pairs in a graph, the transitive closure.

Multiprocessor System-on-Chip (MPSoC) Technology

The multiprocessor system-on-chip (MPSoC) uses multiple CPUs along with other hardware subsystems to implement a system. A wide range of MPSoC architectures have been developed over the past decade. This paper surveys the history of MPSoCs to argue that they represent an important and distinct category of computer architecture. We consider some of the technological trends that have driven the design of MPSoCs. We also survey computer-aided design problems relevant to the design of MPSoCs.

Special Issue on Collaborative Engineering

Special Issue on Collaborative Engineering

Computer-aided design of porous artifacts

Heterogeneous structures represent an important new frontier for 21st century engineering. Human tissues, composites, ‘smart’ and multi-material objects are all physically manifest in the world as three-dimensional (3D) objects with varying surface, internal and volumetric properties and geometries. For instance, a tissue engineered structure, such as bone scaffold for guided tissue regeneration, can be described as a heterogeneous structure consisting of 3D extra-cellular matrices (made from biodegradable material) and seeded donor cells and/or growth factors. The design and fabrication of such heterogeneous structures requires new techniques for solid models to represent 3D heterogeneous objects with complex material properties. This paper presents a representation of model density and porosity based on stochastic geometry. While density has been previously studied in the solid modeling literature, porosity is a relatively new problem. Modeling porosity of bio-materials is critical for developing replacement bone tissues. The paper uses this representation to develop an approach to modeling of porous, heterogeneous materials and provides experimental data to validate the approach. The authors believe that their approach introduces ideas from the stochastic geometry literature to a new set of engineering problems. It is hoped that this paper stimulates researchers to find new opportunities that extend these ideas to be more broadly applicable for other computational geometry, graphics and computer-aided design problems.

On the Exploration of the Solution Space in Analog Placement With Symmetry Constraints

The traditional way of approaching placement problems in computer-aided design (CAD) tools for analog layout is to explore an extremely large search space of feasible or unfeasible placement configurations, where the cells are moved in the chip plane (being even allowed to overlap in possibly illegal ways) by a stochastic optimizer. This paper presents a novel exploration technique for analog placement operating on a subset of tree representations of the layout-called symmetric-feasible, where the typical presence of an arbitrary number of symmetry groups of devices is directly taken into account during the search of the solution space. The computation times exhibited by this novel approach are significantly better than those of the algorithms using the traditional exploration strategy. This superior efficiency is partly due to the use of segment trees, a data structure introduced by Bentley, mainly used in computational geometry.