In this paper, we introduce a new approach to surface mesh improvement problem. In contrast to previous methods we do not tend to preserve new mesh vertices on the original discrete surface. Instead our technique keeps mesh nodes very close to a smooth or piecewise-smooth surface approximated by an initial mesh. As a result, the algorithm is able to improve mesh quality while preserving essential surface characteristics and features. Proposed approach can be applied iteratively not only to polygonal meshes but also to 2D and 3D curves that allows to treat sharp edges and surface boundaries. We demonstrate effectiveness of our method using various triangular and quadrilateral meshes. Also we compare our algorithm with some commonly used techniques and analyze their advantages and disadvantages.

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In this paper, we present a novel method, based on an implementation of quasi-statistical modeling, for improving hexahedral solid mesh. A method for improving meshes by producing elements with a Gaussian (normal) distribution of the mesh quality parameter values is discussed. The main intention is to attain a fairly smooth change from one mesh element to another without creating a significant difference between the shapes of neighboring elements. As regards the initial distribution of the mesh quality parameter values, we assume that after improvement the distribution varies from a rather random distribution to a smoother one, such as a normal distribution. The preliminary choice of the desirable distribution affects the new parameter values modeled by the formula presented here. Our proposed method can be used in a pre-processing stage for subsequent studies (finite element analysis, computer graphics, etc.) by providing better input parameters for these processes. Experimental results are included to demonstrate the functionality of our method.

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Our method is based on an implementation of quasi-statistical modeling for improving meshes by producing mesh elements with modeled values of different mesh quality parameters. In this paper we implement this approach to triangular surface mesh. Considering the initial distribution of the mesh quality parameter values, we assume that after improvement the distribution of elements of the mesh varies from a rather random distribution to a smoother one, such as a normal distribution. The preliminary choice of the desirable distribution affects the new parameter values modeled by the formula presented here. Uncertainty of the smoothed vertex positions of the mesh element affords to use a statistical approach in sense of random variable modeling to connect quasi-statistical modeling and mesh improvement techniques. The so-called “kernel” method allows creating different applicable to a mesh processing algorithms, which can be interpreted as a kind of smoothing technique to determine vertex direction movement with the distribution control of the shape of mesh elements. An aspect ratio is mainly used in present research as a mesh quality parameter. The geometry of the initial mesh surface is preserved by local mesh improving such that the new positions of the interior nodes of the mesh remain on the original discrete surface. Our method can be interpreted as a kind of smoothing technique with using the distribution control of the mesh quality parameter values. This method is comparable with optimization-based approach for avoiding the invalid elements of the mesh by producing a mesh with a rather homogeneous distribution of the mesh elements. Experimental results are included to demonstrate the functionality of our method. This method can be used at a pre-process stage for subsequent studies (finite element analysis, computer graphics, etc.) by providing the better-input parameters for these processes.

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Radial basis functions are popular basis for interpolating scattered data during the image reconstruction process in graphic analysis. In this context, the solution of a linear system of equations is required for each color (blue, red, green) and represents the most time-consuming operation. In this paper a two-level iterative algorithm is proposed to solve efficiently these linear systems of equations. This two-level algorithm consists of a preconditioned iterative method which enforces at each iteration a projection of the residual onto a suitable coarse space. This constraint is ensured by solving an auxiliary second-level problem at each iteration. Numerical results illustrate the convergence properties of the proposed method on a wide range of interpolation problems for image reconstruction.

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In this paper, a method of constructing C¹ triangular patch using C-curves is presented. C-curves are developed by using the basis {sin t, cos t, t, 1} by Zhang, Pottmann and Wagner, and it overcomes some shortcomings of the non-uniform rational B-splines (NURBS) model. For example, it can represent exactly transcendental curves such as the helix and the cycloid. So, how to develop C-curve into surface becomes a very important problem. In Ref.(3), tensor product quadrilateral patches have been constructed using C-curves. By using the side-vertex method proposed by Nielson, a method for constructing C¹ triangular patch using C-curves is proposed in this paper. The constructed triangular patch interpolates the positions and the first derivatives of the boundary composite C-Bézier curves.

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In this paper we propose the use of wavelets to accelerate the solution of the System of Linear Algebraic Equations that arise from the formulation of the problem of image interpolation from scattered data by means of Compactly-Supported Radial Basis Functions. Examples demonstrate the superiority of the solution in the wavelet domain using preconditioned iterative Krylov methods.

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Local sharp feature generation and shape control of surface model are the fundamental issues of surface modeling in the field of CAD/CG. The basic principle of surface modeling based on static recursive approximating subdivision schemes is briefly introduced to deal with the arbitrary topological surface modeling. Method for generating local sharp feature on the subdivision surface by modifying the topological attribute of the vertices is presented. By means of pre-subdivision of the initial mesh, the shape of subdivision surface can be controlled by assigning different weights to the vertices of the initial mesh. The examples of complex surface modeling show that subdivision schemes have prosperous prospect in the field of CAD/CG.

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We describe a novel algorithm for local approximation of scattered surface points, implementing a 2D finite element interpolation algorithm in combination with approximation of coordinates using quadrics for conversion of noisy data to sufficiently smooth data sets. The applied methods and time performance of the developed algorithm are discussed. Experimental results are included to demonstrate the functionality of our approximation technique.

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The past and current trends in CAD/CG are discussed. An overview of the approach used in our ongoing project is given. Our final goal is primarily focused on developing a shape modeling system for solving problems of surface generation and enhancement, which includes polygon generation from unorganized points, shape smoothing, simplification, and improvement of mesh quality parameters of 3D polygonal sets.

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Recently, as consumers gradually prefer buying products that reflect their own personality, there exist some consumers who wish to involve in the product design process. Parallel with the popularization of e-business, many manufacturers have utilized the Internet to promote their products, and some have even built websites that enable consumers to select their desirable product specifications. Nevertheless, this method has not been applied on complicated mechanical product due to the facts that complicated mechanical product has a large number of specifications that inter-relate among one another. In such a case, ordinary consumers who are lacking of design knowledge, are not capable of determining these specifications. In this paper, a prototype framework called Internet-based consumer-oriented product ordering system has been developed in which it enables ordinary consumers to have large freedom in determining complicated mechanical product specifications, and meanwhile ensures that the manufacturing of the determined product is feasible.

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3D-CAD system is needed for the Designing of plastic processing products that are required art-design. But the current use Boolean 3D-CAD system takes too match man-power of the operation, and design engineers can not use it directly. And this situation have made the degeneration of the design technology. We have developed the new topology-CAD system as next generation-CAD. Also the current CAE system has the same problems as CAD. And so, the design engineers depend on the out-source-technology. We have also developed the new genera- use-CAE system integrated in the Topology-CAD using particle analysis.

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Volume CAD, which is being developed at RIKEN, will be a common platform for storing and handling volume data in manufacturing processes. In VCAD, both geometry and volume data are represented as attributes of a set of cells in a simple voxel or octree data structure. In this paper, a method by which to conduct highly accurate structural analysis by directly using VCAD data is proposed. A degenerated hexahedral mesh representing the precise geometry of an object is generated from VCAD data, and finite element analysis is then conducted using the mesh. The proposed method is compared with the X-FEM, and the performances of these two methods are shown to be approximately the same. The robustness of the proposed method is demonstrated by presenting numerical examples of stamping tools.

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Existing CAE is based on CAD data and is mainly applied to design and development. Product-based CAE to acquire data from actual products and implement CAE based on the derived data is being actively studied now. The present paper describes the important points in using reverse engineering that acquires data using noncontact 3D measuring instruments and generates CAD and CAE models based on the derived data. The present paper furthermore introduces the uniquely developed automatic surfacing tool, Clay Galaxy, for use in reverse engineering. The effectiveness of reverse engineering and Product-based CAE is also explained.

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In this paper, the dynamic behavior of a multibody system including very flexible beam elements is presented. The very deformable motion of a beam is demonstrated using absolute nodal coordinate formulation, which is based on finite element procedures, and the general continuum mechanics theory to represent the elastic forces. In order to consider the dynamic interaction between flexible beams and a rigid multibody system, a combined system equation of motion is derived using an absolute nodal coordinate and a rigid body coordinate. In particular, a very flexible catenary cable on which a multibody system moves along its length is presented as a numerical example in this study. To do this, formulations for the sliding joint between a very flexible beam and a rigid body were derived using a non-generalized coordinate, which has no inertia or forces associated with it. This sliding joint is very important to many mechanical applications such as cable cars, pulley systems, and pantograph-catenary system for high-speed trains. In addition, a computation method for the dynamic stress in flexible multibody simulation using an absolute nodal coordinate is presented based on Euler-Bernoulli beam theory, and its reliability was verified by commercial program NASTRAN. Numerical examples are shown using the developed analysis program for flexible multibody systems that include a large deformable beam.

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The unmatched characteristics between dissymmetry hydraulic cylinder and symmetry servo valve while building the model were analyzed. And the simulation analysis adopting dynamic pressure feedback controlling method were proceeded. The unmatched problem has been solved well. The integration simulation study of test bed upon step-input function and sine movement associating with the tri-system of mechanics, hydraulics and control, as well as the static and dynamic control system performance were described in this article.

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An aircraft structure is considered freely in air, unsupported. It is discretized with a set of triangular shell finite elements. It is subjected to alternate pressure forces on its wings. The governing equation is the nonlinear dynamics equation, the nonlinearity arising from the inclusion of the geometrical stiffness allowing for large displacements. The time dependent nonlinear problem is solved by a finite difference scheme. Time-displacement curves are given for a point on the tip of the wing and on the body shell. Under alternate pressure forces -as in case of turbulence- the wings displace upwards in a nonlinear way and then rigid body motion of the aircraft takes place. The motion has chaotic characteristics.

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In this study, the impact of information technologies in architectural design process is discussed. In this discussion, first the differences/nuances between the concept of software engineering and system architecture are clarified. Then, the design process in engineering, and design process in architecture has been compared by considering 3-D models as the center of design process over which the other disciplines involve the design. It is pointed out that in many high-end engineering applications, 3-D solid models and consequently digital mock-up concept has become a common practice. But, architecture as one of the important customers of CAD systems employing these tools has not started to use these 3-D models. It is shown that the reason of this time lag between architecture and engineering lies behind the tradition of design attitude. Therefore, it is proposed a new design scheme a meta-model to develop an integrated design model being centered on 3-D model. It is also proposed a system architecture to achieve the transformation of architectural design process by replacing 2-D thinking with 3-D thinking. It is stated that in the proposed system architecture, the CAD systems are included and adapted for 3-D architectural design in order to provide interfaces for integration of all possible disciplines to design process. It is also shown that such a change will allow to elaborate the intelligent or smart building concept in future.

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A comprehensive mathematical model of a typical hydraulic power steering system equipped with variable ratio rack and pinion gear is developed. The steering system’s dynamic characteristics are investigated and its forced vibrations are compared with those obtained from a counterpart system with a constant ratio rack and pinion gear. The modeling details of the mechanism subsystem, hydraulic supply lines subsystem and the rotary spool valve subsystem are provided and included in the integrated steering system model. The numerical simulations are conducted to investigate the dynamics of the nonlinear parametric steering system. From the comparison between simulated results and the experimental ones, it is shown that the model accurately integrates the boost characteristics of the rotary spool valve which is the key component of hydraulic power steering system. The variable ratio rack-pinion gear behaviors significantly differently from its constant ratio counterpart does. It significantly affects not only the system natural frequencies but also reduces vibrations under constant rate and ramp torque steering inputs. The developed steering model produces valid predictions of the system’s behavior and therfore could assist engineers in the design and analysis of integrated steering systems.

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Dynamic characteristics of an oil-lubricated spiral-grooved journal bearing are theoretically investigated in this paper with considering the effect of cavitation occurrence in the bearing clearance. The Reynolds equation by cooperating with a cavitation theory called ‘equivalent flow model’ as a formulation for cavitation occurrence is expanded by perturbation scheme with respect to the journal eccentricity, so that the dynamic bearing characteristics, such as bearing stiffnesses and damping coefficients, are calculated from the obtained results of perturbed pressure distributions. It is shown that, when the cavitation occurrence is considered, the value of the direct bearing stiffness becomes larger, while those of the cross-coupling bearing stiffness and damping coefficients become smaller, compared with those with neglecting the contribution of the cavitation occurrence. Stable operating limits against ‘half-frequency whirl’ are discussed as well, showing that the critical mass values become larger when considering the cavitation occurrence than those with neglecting it.

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In this paper, a manufacturing feature recognition method for the generation of multiple process plans is proposed. The feature recognition method is constructed in 2 phases. First, features are extracted using Extended Super Relation Graph (Extended SRG) Method. By using Extended SRG Method, interacting and overlapping features can be extracted in several different ways, corresponding with different kind of machining operations. In the second phase, the authors organize the extracted features into manufacturing feature sets using Feature Spatial Relation (FSR) Method. By organizing features into multiple manufacturing feature sets, the generation of multiple process plans is made possible, since each manufacturing feature set corresponds with different kind of process plans. In this paper, the authors describe the Extended SRG Method and FSR Method. The authors use a case study to clarify the effectiveness of these methods for the manufacturing feature sets creation.

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A mathematical model was formulated on the basis of results from psychophysical experiments in which human subjects discriminated fine steps on aluminum plates. The mathematical model emulated the real neuron discharge caused when a membrane potential exceeds a threshold. This membrane potential was determined by spatial and temporal summations of postsynaptic potential. To evaluate the mathematical model for surface texture recognition by robots, we performed a series of surface-detection experiments using a robotic manipulator equipped with an optical three-axis tactile sensor. The single sensor cell of this sensor consisted of a columnar feeler and a 2-by-2 array of conical feelers. The three-axis force was calculated from the area-sum and area-difference of the conical feelers’ contact areas. The robotic manipulator rubbed the tactile sensor on four brass plates with step heights of 0, 0.05, 0.1 and 0.2mm. Results showed that the mathematical model could distinguish these step heights in real time.

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This paper describes a new method for micro-EDM drilling which utilizes the wear of rod electrodes. With this method, a pair of micro rod and micro hole can be machined in a single process, while with conventional methods, the micro rod electrode needs to be formed before machining the micro hole. Processing conditions were optimized for the new method to obtain higher aspect ratio for the micro rods. Results of experiments also showed the following: 1) This method can be applied to AISI1045, AISI304 and Kovar and any electrode diameter size. 2) From the second process, if machining many holes using the same electrode, the electrode shape can be regenerated with excellent repeatability and holes processed efficiently. 3) The influence of carbon adhering to the tip region of the rod electrode is large, which is why the rod electrode becomes needle sharp.

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Mechanical property of bone is inhomogeneous and its variation depends on individual. It influences on the total stiffness and stress condition of the bone. Therefore, mechanical analysis considering inhomogeneous property is necessary for patients oriented evaluation of bone in clinic. If the finite element method is used, the inhomogeneous analysis is possible by giving a material property to an element one by one. So that, extreme fine meshing is required. In this study, we improved the “ADVENTURE system”, which had developed by JSPS (Japan Society for the Promotion of Science) as a large-scale finite element analysis system, to be applicable to stress analysis of inhomogeneous bone problems. We applied the improved program to a composite beam model with graded material property and ensured its validity by comparing between the theoretical and calculated results. Furthermore, it was applied to stress analysis of proximal femur based on CT images and its efficiency was discussed.

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The paper describes an augmented Lagrangian decomposition and coordination approach for solving single machine scheduling problems to minimize the total weighted tardiness. The problem belongs to the class of NP-hard combinatorial optimization problem. We propose an augmented Lagrangian decomposition and coordination approach, which is commonly used for continuous optimization problems, for solving scheduling problems despite the fact that the problem is nonconvex and non-differentiable. The proposed method shows a good convergence to a feasible solution without heuristically constructing a feasible solution. The performance of the proposed method is compared with that of an ordinary Lagrangian relaxation.

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Most passive vibration isolation systems are composed of springs and dampers. Although it is possible to improve the isolation performance by active vibration control, the complexity, power requirements and cost of such a system have restricted its use. A vibration isolation system with variable damping is practical and has good performance in the high frequency region, but it was found not to improve the responses in the low frequency region. On the base of a damping on-off control method, a stiffness on-off control method and a combination of damping and stiffness on-off control method were proposed. Comparison of the responses among the proposed methods and the conventional methods showed that the damping and stiffness on-off control method had the best isolation properties in the whole frequency region. A new system with controllable dampers of two Voigt elements in series was used to achieve the proposed idea.

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