A multi-objective optimal approach to automated construction of sacrificial multi-piece molds

Sacrificial multi-piece molds can be used for producing complex parts. To obtain the optimal design of molds automatically, a multi-objective optimal approach is proposed. Mold pieces number, material utilization and partitioning area are taken as the objective functions, and the machinability of each mold piece is taken as constraint condition. Genetic algorithm (GA) is adopted to realize global optimization of partitioning process. Each mold piece in optimal scheme can be manufactured by milling and drilling operations, which reduce the tooling cost and shorten product cycle obviously. Using the proposed approach, mold design can be significantly automated for making complex parts.     

Evaluation and optimization of intersection process between voxelized mesh models and homocentric spheres

In the field of 3D model matching and retrieval, an effective method for feature extraction is spherical harmonic or its mutations, and is acted on the spherical images. But the obtainment of spherical images from 3D models is very time-consuming, which greatly restrains the responding speed of such systems. In this paper, we propose a quantitative evaluation of the whole process and give a detailed two-sided analysis based on the comparative size between pixels and voxels. The experiments show that the resultant optimized parameters are fit for the practical application and exhibit a satisfactory performance.     

Voxelizating 3D mesh models with gray levels

A novel algorithm to voxelize 3D mesh models with gray levels is presented in this paper. The key innovation of our method is to decide the gray level of a voxel according to the total area of all surfaces contained by it. During the preprocessing stage, a set of voxels in the extended bounding box of each triangle is established. Then we travel each triangle and compute the areas between it and its set of voxels one by one. Finally, each voxel is arranged a discrete gray level from 0 to 255. Experiments show that our algorithm gets a comparatively perfect result compared with the prevenient ones and approaches the original models in a more accurate way.     

STUDY ON CONFLICT MANAGEMENT FOR COLLABORATIVE DESIGN SYSTEM

IntroductionAdvances in computer networks and informationtechnology have enabled product designers tomore effectively communicate,collaborate,ob-tain and exchange a wide range of design re-sources during product development.ComputerSupported Cooperative Work( CSCW) describesa research area concerned with people working ingroups and computer systems supporting them,and collaborative design is an important applica-tion of CSCW.Collaborative design has typicallydistributed multiple functional…     

A new algorithm for non-newtonian flow and its application in mould filling process

The simulation of injection molding process requires a stable algorithm to model the molten polymer with non-isothermal non-Newtonian property. In this paper, a staggered and iterative scheme is particularly designed to solve the velocity-pressure-temperature variables. In consideration of the polymer characteristic of high viscosity and low thermal conductivity, the non-Newtonian momentum-mass conservation equations are solved by the Crank-Nicolson method based split (CNBS) scheme, and the energy conservation equation with convective character is discretized by the characteristic Galerkin (CG) method. In addition, an arbitrary Lagrangian Eulerian (ALE) free surface tracking and mesh generation method is introduced to catch the front of the fluid flow. The efficiency of the proposed scheme is demonstrated by numerical experiments including a lid-driven cavity flow problem and an injection molding problem.     

列车空调机组性能试验台远程监控和诊断系统的开发

本文介绍了列车空调机组性能试验台远程监控和诊断系统的工作原理、功能,以及该系统的软、硬件组成,阐述了软件开发过程的要点和关键技术,并总结了该软件的特点及开发步骤。其研究成果对于节约维修成本、提高生产效率,保证列车空调机组安全、可靠运行具有十分重要的意义。     

Graph and hint based algorithm for machining feature automation recognition and mapping

Feature recognition is a process of extracting machining features which has engineering meaning from solid model, and it is a key technology of CAD/CAPP/CAM integration. This paper presents an effective and efficient methodology of recognizing machining feature. In this approach, features are classified into two categories: pocket feature and predefined feature. Different feature type adopts its special hint and heuristic rule, and is helpful to recognize intersection feature. Feature classification optimizes search algorithm and shortens search scope dramatically. Meanwhile, extension and split algorithm is used to handle intersecting feature. Moreover, feature mapping based on machining knowledge is introduced to support downstream application better. Finally, case studies with complex intersecting features prove that the developed approach has stronger recognizing ability.     

Multi-objective optimal approach for injection molding based on surrogate model and particle swarm optimization algorithm

An integrated optimization strategy based on Kriging model and multi-objective particle swarm optimization(PSO) algorithm was constructed.As a new surrogate model technology,Kriging model has better fitting precision for nonlinear problem.The Kriging model was adopted to replace computer aided engineering(CAE) simulation as fitness function of multi-objective PSO algorithm,and the computation cost can be reduced greatly.By introducing multi-objective handling mechanism of crowding distance and mutation oper...     

Curvature estimation of point set data based on the moving-least square surface

Curvature estimation is a basic step in many point relative applications such as feature recognition, segmentation, shape analysis and simplification. This paper proposes a moving-least square (MLS) surface based method to evaluate curvatures for unorganized point cloud data. First a variation of the projection based MLS surface is adopted as the underlying representation of the input points. A set of equations for geometric analysis are derived from the implicit definition of the MLS surface. These equations are then used to compute curvatures of the surface. Moreover, an empirical formula for determining the appropriate Gaussian factor is presented to improve the accuracy of curvature estimation. The proposed method is tested on several sets of synthetic and real data. The results demonstrate that the MLS surface based method can faithfully and efficiently estimate curvatures and reflect subtle curvature variations. The comparisons with other curvature computation algorithms also show that the presented method performs well when handling noisy data and dense points with complex shapes.