An Improved Virtual Spherical Lights Approach for Glossy Illumination

Based on a virtual spherical light source method, this paper presents an improved virtual spherical lights approach for glossy illumination by modifying a reflection render equation. First, in order to keep primitive spherical lights, it uses non-zero solid angle integration instead of a geometric item of traditional Instant Radiosity arithmetic. Second, the formula mode for the light energy allocation of VSLs is improved by the energy distribution, in which the radius of sphere is replaced by the radius of inscribed circle generated by the tangent to the non-zero solid angle of cone. Third, the similar function of judging two point visibility takes place of a cosine term in the approximate equations of the VSLs. Experiments show that blurring or disappearing phenomenon that appear in part of right-angle surface scene is avoided.

Labeling Line Drawings with Hidden-Part-Drawn of Planar Object with Trihedral Vertices

Although line drawings consist of only line segments on a plane, they convey much information about the three-dimensional object structures. For a computer interpreting line drawings, some intelligent mechanism is required to extract three-dimensional information from the two-dimensional line drawings. In this paper, a new labeling theory and method are proposed for the two-dimensional line drawing with hidden-part-draw of a three-dimensional planar object with trihedral vertices. Some rules for labeling line drawing are established. There are 24 kinds of possible junctions for line drawing with hidden-part-draw, in which there are 8 possible Y and 16 W junctions. The three problems are solved that Sugihara＇s line drawing labeling technique exists. By analyzing the projections of the holes in manifold planar object, we have put forward a labeling method for the line drawing. Our labeling theory and method can discriminate between correct and incorrect hidden-part-draw natural line drawings. The hidden-part-draw natural line drawings can be labeled correctly by our labeling theory and method, whereas the labeling theory of Sugihara can only label the hidden-part-draw unnatural line drawings in which some visible lines must be drawn as hidden lines, and some invisible lines must be drawn as continuous lines.

Research on engineering-oriented constraints conflict detection in collaborative design of wire harness technology

Engineering-oriented constraint of harness technology has much information and project information presents progressive changes along with the design. Therefore, how to handle conflict resolution quickly is a problem to be solved. Process model of con- flict detection is put forward according to characteristics of harness technology design engineering-oriented constraint, and then two problems of how to conduct conflict positioning and judgment of constraint rules are introduced in this paper. Afterwards in this pa- per, constraint information directed acyclic graph is established by classified project constraint information to solve the conflict posi- tioning problem; solution of constraint satisfaction problem is applied to realize judgment problem of constraint rules. Finally, exam- ple is used to analyze the method in this paper to further verify the correctness and effectiveness of this method.

Spatial Data Sharing on Grid

The Internet technology has already changed the Information Society in profound ways, and will continue to do so. Nowadays many people foresee that there is a similar trajectory for the next generation of Internet - Grid Technology. As an emerging computational and networking infrastructure, Grid Computing is designed to provide pervasive, uniform and reliable access to data, computational and human resources distributed in a dynamic, heterogeneous environment. On the other hand, the development of Geographic Information System （GIS） has been highly influenced by the evolution of information technology such as the Internet, telecommunications, software and various types of computing technology. In particular, in the distributed GIS domain, the development However, due to the closed and centralized has made significant impact in the past decade. legacy of the architecture and the lack of interoperability, modularity, and flexibility, current distributed GIS still cannot fully accommodate the distributed, dynamic, heterogeneous and speedy development in network and computing environments. Hence, the development of a high performance distributed GIS system is still a challenging task. So, the development of Grid computing technology undoubtedly provides a unique opportunity for distributed GIS, and a Grid Computing based GIS paradigm becomes inevitable. This paper proposes a new computing platform based distributed GIS framework - the Grid Geographic Information System （G^2IS）.

View-point Control for Walk-through in Internet Environment

Techniques of Viewpoint-binding, interactive Viewpoint-animation interaction and their realization with VRML2 are illustrated

Many-Knot Spline Interpolating Curves and Their Applications in Font Design

Many-knot spline interpolating is a class of curves and surfaces fitting method presentedin 1974. Many-knot spline interpolating curves are suitable to computer aided geometric design anddata points interpolation. In this paped, the properties of many-knot spline interpolating curves arediscussed and their applications in font design are considered. The differences between many-knotspline interpolating curves and the curves genoaed by exceeding-lacking adjuStment algorithm aregiven.

A MULTIPLE STRUCTURE RECONSTRUCTION ALGORITHM BASED ON WIRE FRAME MODEL

A “LAG & RLC” visualization algorithm has been presented to display a clear three dimensional structure from stereo slice data which has the characteristics of multiple layer structure. This algorithm is based on wire frame model which can do multiple logical operations and has multiple display effects. It has wide use in biomedical science and computer graphics. The practical system is based on PC with a TVGA adapter at least 512k byte display memory and 2M byte extended memory.

Sheet material lifting mechanism of the manipulator

At present, machine fixed up and down repeatedly work is done by human. Although it is low cost and easy to change plate, there are many shortcomings of the work injury and the low work efficiency. Foreign automatic loading and unloading device has been developed, but the principle is more complex, the cost is higher, the energy consumption is larger, so the automatic loading and unloading robot came into being. Aiming at the transportation of mechanical raw material, an automatic device is designed to transport the scheduled raw materials to the specified position according to the processing requirements. The device has the characteristics of the simple operation, the rapid response and the large range of activities, and has obvious economic and environmental benefits. There is certain popularization value.

Digital Design of Multi-Functional Rehabilitation Robot

The mechanical structure as well as the schematic organization has been designed to achieve lower limb rehabilitation training function; Solidworks has been used to model the robot. And the robot has been optimized by the means of human-interference engineering. The primary components of the robot have been analyzed by Ansys workbench.

An optimization method for rational Bézier curve design

Adjusting weights as a shape control tool in rational B6zier curve design is not easy because the weights have a global in- fluence. The curve could not approximate control polygon satisfactorily by an interactive manner. In order to produce a curve close enough to control polygon at every control vertex, an optimization model is established to minimize the distance between rational B6zier curve and its control points. This optimization problem is converted to a quadratic programming problem by separating and recombining the objective function. The new combined multi-objective optimization problem is reasonable and easy to solve. With an optimal parameter, the computing process is discussed. Comparative examples show that the designed curve is closer to control polygon and preserves the shape of the control polygon well.

Design and Implementation of an Ultrasonic Heat Meter Based on MSP430F437

Flowing with the reform of the hot water heating method in China, heat meter will enter into households in the near future. A portable ultrasonic heat meter is designed in this paper. The meter uses chip microprocessor MSP430F437 as the data process core, and uses ultrasonic flow sensor to measure flow rate of the hot water, and capture input and output temperatures of the hot water using the thermal resistance sensor Ptl000, and then household energy consumption is calculated via temperature difference between input temperature and output temperature of the hot water multiplied by volume of hot water that is calculated though flow rate integration of hot water. In order to test the performance of the proposed heat meter, experiments is carried out. Both the temperature and flow measurement results satisfy the requirements of accuracy and the heat meter is effective in the heat measurement.

Derivative Geometric Modeling of Basic Rotational Solids on CATIA

Hybrid models derived from rotational solids like cylinders, cones and spheres were implemented on CATIA software. Firstly, make the isosceles triangular prism, cuboid, cylinder, cone, sphere, and the prism with tangent conic and curved triangle ends, the cuboid with tangent cylindrical and curved rectangle ends, the cylinder with tangent spherical and curved circular ends as the basic Boolean deference units to the primary cylinders, cones and spheres on symmetrical and some critical geometric conditions, forming a series of variant solid models. Secondly, make the deference units above as the basic union units to the main cylinders, cones, and spheres accordingly, forming another set of solid models. Thirdly, make the tangent ends of union units into oblique conic, cylindrical, or with revolved triangular pyramid, quarterly cylinder and annulus ends on sketch based features to the main cylinders, cones, and spheres repeatedly, thus forming still another set of solid models. It is expected that these derivative models be beneficial both in the structure design, hybrid modeling, and finite element analysis of engineering components and in comprehensive training of spatial configuration of engineering graphics.

3D FEM Simulation of Precision Forging Automobile Clutch Damping Spindle Sleeve

The precision forging process is simulated by commercial software Deform 3D using a rigid visco-plastic model to predict the status of metal flow and the distribution of equivalent plastic strain, providing guidance for making decision on the optimal choice of process parameters and mould structure. Trial forging was used to verify the effectiveness of FEM simulation results.

Research on Application of Visual Simulation System of Expressway

Applying the visual simulation technology to highway engineering, an expressway visual simulation system for the analysis of landscape design proposals is built during the construction of Xiaoxiang expressway. Its functional requirements and overall architecture are presented. The 3D model of expressway is created with AutoCAD DWG files as source data and the dynamic design method of expressway landscape elements is introduced. A data analysis interface dedicated to the landscape evaluation is developed. The system offers an effective tool to facilitate the analysis and evaluation of the road landscape proposals.

A Mechanism for Dynamic and Consistent Product Information Association

The dynamic and consistent information association among vtrious application activities in the full life cycle of a product is a key to the assurance of the cooperation among different application domains. In order to establish and maintain the association, a design-process-based product association model was proposed. This model takes advantage of the generic naming mechanism, the private protocol for history-based form feature modeling, on which the Data Association Protocol is built. Hence the model can provide the way of constructing and maintaining the information linkage among different product developing stages naturally and dynamically while keeping the privacy of the feature coding. A case study illustrates the utilities of the model in the data linking between design model and process planning model.

B-SPLINE SURFACE SMOOTH JOINING

Optimization techniques are being applied to solve the problems of surface interpolation, approximation, smooth joining and fairing, aiming at corresponding objective functions. This paper focuses on the construction of fair surface interpolating the given mesh of curved boundaries with G 2 adjustment at comers and G 1, G 2 smoothness between adjacent patches. Many papers on surface blending have been presented, but almost all of them are restricted to the discussion of Bezier patches, there are no good results for B-spline surface. This paper gives a solution to the B-spline surface, allowing the surface to degenerate at comer in and have different parameterization along the common boundary of two patches.

An approach for converting orthographic projection drawings into 3D-CAD models

Abstract： Hand drawings and two dimensional （2D） CAD drawings have been replaced by three dimensional （3D） CAD models in mechanical design, but some 2D drawings produced before are needed in the new design. However, the techniques and software packages for automatically converting 2D drawings into 3D-CAD models with high precision have not yet been developed due to the difficulties to verify the validity of the drawings, to decide the hidden lines and eoncavo-convex faces, and to represent free-form surfaces. In addition, it is very time consuming to manually convert a large number of 2D drawings into 3D CAD models. To address these problems, we propose an approach for converting 2D drawings into 3D-CAD models automatically.

An Algorithm for Finding Internal Faces Based on the 3D Coordinates

This paper presents a direct method to find the internal faces. It uses four sets of information： get the coordinates of each point on the 3D composite objects; （~）based on the 3D coordinates to calculate all the plane equation of two objects; （~）calculate all the intersecting lines of the two objects and exclude the intersecting lines which are not within the scope of the plane;finding the internal face, the remaining intersecting lines formed the plane is the internal face of the two objects. We proposed a new algorithm for finding internal faces. This algorithm could be adapted to any regular composite objects .The algorithm works well for finding internal faces.

Slicing Strategy for Selective Laser Melting

Selective laser melting （SLM） is one of the most popular additive manufacturing （AM） technologies for metal parts. Slicing result, especially for the different dimensional slicing geometry and its topology, plays an important role because of the thermodynamic behavior of metal powders. To get correct geometry and reliable topology, a slicing strategy for SLM is proposed. The unavoidable numerical error caused by sampling and geometric transformation is suppressed firstly, according to shifting the z-coordinate of a vertex with a small value such the shifted vertex is on a slicing plane. The result of vertex-shifting makes it possible to identify different geometric features such as skin surfaces, overhang surfaces, extreme edges and volumetric solid. Second, from geometric primitives a hierarchy of axis-aligned bounding boxes （AABBs） is constructed and used to speed up intersection of slicing planes against sets of triangles. All intersecting segments are given different signs to depict their geometric or topological information. Based the different signs, the different dimensional geometry that is eventually represented by simple and anticlockwise oriented polygons, are identified. Finally, the polygons are classified and nested in a multi-tree data structure set to produce correct topological relations. The result of digital and physical experiments shows the proposed slicing strategy is feasible and robust.