Swept Surface Research Articles

Caractérisation géométrique de la frontière de l'espace de travail d'un système polyarticulé dans le plan

We model a planar polyarticulated system by points defining the joints and a last point A p linked to the last solid. The surface swept by the point A p has its boundary defined by 3 kinds of particular configurations. These curves can be geometrically determined. To cite this article: J. Bastien et al., C. R. Mecanique 335 (2007).

Sweep‐based Freeform Deformations

Abstract We propose a sweep‐based approach to the freeform deformation of three‐dimensional objects. Instead of using a volume enclosing the whole object, we approximate only its deformable parts using sweep surfaces. The vertices on the object boundary are bound to the sweep surfaces and follow their deformation. Several sweep surfaces can be organized into a hierarchy so that they interact with each other in a controlled manner. Thus we can support intuitively plausible shape deformation of objects of arbitrary topology with multiple control handles. A sweep‐based approach also provides important advantages such as volume preservation. We demonstrate the effectiveness of our technique in several examples. Categories and Subject Descriptors (according to ACM CCS): I.3.5 [Computational Geometry and Object Modeling]: Curve, surface, solid, and object representations

Hydrogenated Ge nanocrystals: band gap evolution with increasing size

The electronic band structure of various Ge quantum wires of different sizes, with hydrogenated surfaces, is studied using a nearest-neighbor empirical tight-binding Hamiltonian by means of a sp³s* atomic orbitals basis set. We suppose that the nanostructures have the same lattice structure and the same interatomic distance as in bulk Ge and that all the dangling bonds are saturated with hydrogen atoms. These atoms are used to simulate the bonds at the surface of the wire and sweep surface states out of the fundamental gaps. One of the most important features is a clear broadening of the band gap due the quantum confinement. Comparing to experimental data, we conclude that, similar to the case of Si, the size dependent PL in the near infrared may involve a trap in the gap of the nanocrystals.

Planarization Efficiency of Electrochemical Mechanical Deposition and Its Dependence on Process Parameters

Electrochemical mechanical deposition (ECMD) is a technique that has the ability to deposit planar metal films on nonplanar substrate surfaces with cavities. The method involves electrochemical deposition and simultaneous sweeping of the substrate surface with a planarization pad. Mechanical action of the pad increases suppression at the swept surface and therefore, mechanically induced superfilling of the cavities takes place. In this study we show that the planarization efficiency of the ECMD process for copper deposition is a strong function of the plating chemistry. Electrolytes containing no organic additives or only accelerators do not yield any planarization. Plating baths with only suppressors show low planarization capability, whereas those containing both suppressors and accelerators yield the highest planarization efficiency. Soaking the wafer surface in an accelerator-containing solution before the ECMD process step increases the planarization efficiency significantly. The presence of levelers in the plating electrolyte is detrimental to planarization efficiency of ECMD. High-acid copper plating solutions display higher planarization capability than low-acid electrolytes.

DESIGN OF AUTO-BODY PANEL ADDENDUM BASED ON SWEEP SURFACE

Making the addendum and blank-holder surface is key technique in auto-body panel stamping and die-face design and machining. A great number of experiments and numerical simulation based on CAE have fully validated that the shape and configuration of the addendum and blank-holder surface have obvious influence on the formability of the stamped panel. In the past design of the panel die, users design them by hand- craft scheme and based on their old design experience, which evidently decreases design efficiency. A design scheme of the addendum and blank-holder surface, which is based on sweep surface design method and can efficiently solve some troubles on making the addendum is proposed. Besides, the creating ideal and constructing scheme of the sweep surface design are introduced, and their relative algorithms are proposed in terms of the forming features of auto-body panels. The feasibility of the constructing scheme is explained from actual industrial forming examples. Compared with the creating scheme based on FE meshes used in some CAE software, the most advantage of the present method is that the addendum and blank-holder surface created by sweep surface scheme can be directly used in DNC machining; and in the same time, many automatic and self-adaptive design processes based on the present algorithm can obviously increase design efficiency on auto-body panel die-face.

PDGI-based regular swept surface extraction from point cloud

一幅主要方向 Gaussian 图象(PDGI ) 基于算法被建议从点云提取常规打扫表面。第一，常规打扫表面的 PDGI 从点云被构造，然后， Gaussian 范围的跳的盒子一致地被划分成很多个小立方体(3D 格子) ， PDGI 指在 Gaussian 范围上有相应 3D 格子的 reassociated。第二，簇分析技术被用来整理在 3D 格子之中包含更多的 PDGI 点的一组 3D 格子。由连接区域的成长算法，会众点或大圆从 3D 格子被检测。因此，翻译方向被会众点决定，旋转的轴的方向被大圆决定。另外，旋转的轴的位置的点被旋转表面的所有投射的正常的线的交叉在对旋转的轴的估计的方向垂直的飞机上获得。最后，一个模式搜索方法被使用优化翻译方向和旋转的轴。Someexperiments 被用来说明上述算法的可行性。

Sweep-based human deformation

We present a sweep-based approach to human body modeling and deformation. A rigid 3D human model, given as a polygonal mesh, is approximated with control sweep surfaces. The vertices on the mesh are bound to nearby sweep surfaces and then follow the deformation of the sweep surfaces as the model bends and twists its arms, legs, spine and neck. Anatomical features including bone-protrusion, muscle-bulge, and skin-folding are supported by a GPU-based collision detection procedure. The volumes of arms, legs, and torso are kept constant by a simple control using a volume integral formula for sweep surfaces. We demonstrate the effectiveness of this sweep-based human deformation in several test animation clips.

Volume Manipulations for Simulating Bone and Joint Surgery

Bone and joint surgery is widely used in orthopedic, oral, and maxillofacial, and dental and plasty departments to correct bone and joint pathology such as bone and joint tumors and fractures, and skeletal morphological deformities. This article presents a voxel structure to represent topologically and geometrically correct surfaces and algorithms to accurately compute intersections of tool swept surfaces with bones based on this voxel structure. This article then presents various volume manipulation algorithms to operate on virtual bones, bone grafts, and prostheses for bone and joint surgery simulations. A complicated knee arthroplasty illustrates the practicality and versatility of the proposed method.

Application of Sweeping Techniques to Reverse Engineering

Reverse engineering refers to the process of developing a CAD model from a set of data collected from a physical part. Most reverse engineering applications assume that the parts are complete and the collected data provide complete information on them. In this paper, however, the authors consider the case where the parts are not complete due to breakage, and develop algorithms to infer the shapes of the original parts. Sweeping techniques are extensively used for the inference of shapes. Sweeping refers to the moving of a generator such as a curve, surface, or solid along a path . In this paper, the generator of sweep will be limited to a curve. There are three cases to consider: translational, rotational, and general. In each case, a part will be represented as a surface swept by a profile curve along a spine curve or a trajectory, both of which are modelled as NURBS curves. Once the original shape is inferred, the dimensions may be extracted from the original or mating part. The ultimate goal of this project is to develop a software system that infers the shape of the original part from the incomplete data so that the broken or worn-out piece may be designed and manufactured.

Systematic investigation on the use of plate type tools for the production of linear and circular swept surfaces on CNC EDM

EDM has taken an important place in modern workshops for machining material in various conditions where the material is too hard or the workpiece is too complicated for conventional machining. One disadvantage is the need to use 3D shaped tools as these require intricate manufacturing processes and increases the cost of the EDM process. The application of CNC to EDM has offered great flexibility for the generation of 3D complex shapes by using simple type of EDM tools. This paper describes the use of simple 'profiled plate electrodes' for the generation of any linear and circular swept surfaces on CNC EDM machines and introduces the machining characteristic of these type of tools using statistical techniques.

Edge detection in reverse engineering using a scanning approach. Part 1: scanning algorithm

This paper describes an algorithm for edge detection in reverse engineering applications. This algorithm is able to detect edges in unstructured point clouds, and also reconstruct the “original” sharp edge in point clouds scanned on objects with broken, worn or filleted edges. Edges can be detected from point clouds without a priori compensation for the probe radius. When combined with a swept surface approximation algorithm, these surfaces can be used to segment some point clouds. These capabilities make this algorithm a valuable tool in the reverse engineering of machine components such as the inlet manifold used as a case study.

Methods for the physical and chemical characterisation of surfaces of titanium implants

At present, one is still searching for physical and chemical methods which are suitable for the characterisation of biocompatibility of implant surfaces. In this paper, we analysed differently structured titanium surfaces (the roughness average of the various structures differs by four orders of magnitude) with a number of electrochemical and physical methods such as electrochemical impedance spectroscopy, chronoamperometry, linear sweep voltammetry, surface profiling and scanning electron microscopy. The aim of the work is to compare the specific methods regarding their significance, and to correlate the results. Beside the extraction of physical and electrochemical parameters which are typical for the above-mentioned methods, the possibility of the determination of the fractal dimension of the surface structures is also examined. Cell biological examinations concerning the mechanism of cell adhesion were used to verify the ability of the parameters measured by the referred methods to describe the biocompatibility of the analysed surfaces.

NC machining for revolved and swept surfaces with free-form profiles

An accurate, flexible and simple method is proposed for machining the surfaces obtained, either by revolving around an axis (surface of revolution), or by moving along a straight line (swept surface), a free-form profile which is implemented in terms of Bezier formulation. In the first case, the profile curve is coplanar with the symmetry axis, while in the second case it lies in a plane perpendicular to the direction of translation. The demand for manufacturing of such geometric shapes is frequently met in sculptured surfaces of molds, stamping dies, forging tools, rolling shapes, etc.

A Z-map update method for linearly moving tools

In numerically controlled (NC) machining simulation, a Z-map has been frequently used for representing the workpiece. Since the Z-map is usually represented by a set of z-axis aligned vectors, the machining process can be simulated through calculating the intersection points between the vectors and the surface swept by a machining tool. In this paper, we present an efficient method to calculate those intersection points when automatically programmed tool-type tools move along a linear tool path. Each of the intersection points can be expressed as the solution of a system of non-linear equations. We transform this system of equations into a single-variable equation, and calculate the candidate interval in which the unique solution exists. We prove the existence of a solution and its uniqueness in this candidate interval. Based on these properties, we can effectively apply numerical methods to finally calculate the solution of the non-linear equations within a given precision. The whole process of NC simulation is achieved by updating the Z-map properly. Our method can improve accuracy greatly while increasing processing time negligibly in comparison with previous Z-map update methods, making it possible to verify the tool path more accurately and reliably.

Identification and Characterization of Regular Surfaces from Unorganized Points by Normal Sensitivity Analysis

In this paper, the concept of free motion subspace is introduced and utilized to characterize the special kinematic properties of regular surfaces, including planes, natural quadrics, and regular swept surfaces. Based on the concept, a general approach is developed to automatically identify the surface type and calculate the associated geometric parameters of an unknown surface from unorganized measurement points. In the approach, a normal sensitivity matrix, that characterizes the normal perturbation of surface points under differential motions, is derived. With the normal sensitivity matrix, it is shown that the free motion subspace of a surface can be determined through a regular eigen analysis. From the identified free motion subspace, the surface type of a regular surface can be determined and its geometric parameters can be simultaneously computed. An algorithm that identifies the free motion subspace of an unknown surface from its unorganized sample points has been implemented. Experiments are carried out to investigate the robustness and efficiency of the developed algorithm. The developed algorithm can be used to solve various problems including geometric primitive classification and parameter estimation, regular swept surface reconstruction, geometric constraint recognition and multi-view data registration. Integrated with state-of-art segmentation techniques, the proposed method can be used for object recognition, robot vision, and reverse engineering.

Algorithms for reverse engineering boundary representation models

A procedure for reconstructing solid models of conventional engineering objects from a multiple-view, 3D point cloud is described. (Conventional means bounded by simple analytical surfaces, swept surfaces and blends.) Emphasis is put on producing accurate and topologically consistent boundary representation models, ready to be used in computer aided design and manufacture. The basic phases of our approach to reverse engineering are summarised, and related computational difficulties are analysed. Four key algorithmic components are presented in more detail: efficiently segmenting point data into regions; creating linear extrusions and surfaces of revolution with smooth, constrained profiles; creating the topology of B-rep models; and finally adding blends. The application of these algorithms in an integrated system is illustrated by means of various examples, including a well-known reverse engineering benchmark.

Gear Geometric Design by B-Spline Curve Fitting and Sweep Surface Modelling

Gear Geometric Design by B-Spline Curve Fitting and Sweep Surface Modelling

Dynamic Inhibition of Constrained Crystallization by Mesoscopic Morphology Modifiers

We investigate the mechanisms by which two chemically diverse polymer additives affect crystal separation from hexacosane/decane solutions under various conditions. The additives are dissimilarly effective for delaying the onset of crystallization in supercooled solutions, although none, of course, ultimately prevents their reaching equilibrium. Remarkably, one polymer significantly raises the dissolution temperature of the crystal aggregates grown in its presence, even at sub-parts-per-million additive levels. More interesting is the finding that sufficiently large concentrations of either additive are able to cap at a common minimum thickness the porous layers formed on a cold surface swept by undersaturated solutions. The thin layers formed in the presence of crystallization inhibitors are mesoscopically more compact (i.e., have pore sizes about 10-fold smaller) than those produced in their absence, although all meltwhen rid of solventas neat hexacosane at 329.5 ± 0.5 K. We infer that inhibitors permanently limit the extent of crystal separation from undersaturated solutions subjected to fixed temperature constraints by blocking solute transfer across the boundary layer. This lasting action is mediated by the subtle modification of mesoscopic crystal morphology and is remotely related to the kinetics of isothermal crystal nucleation or the thermodynamics of phase separation.

Estimating Aerodynamic Characteristics of Automatic Landing Flight Experiment Vehicle Using Flight Data

The Automatic Landing Flight Experiment (ALFLEX) project was conducted as part of the research on the H-II orbiting plane-experimental (HOPE-X) unmanned reentry vehicle. One of the aims of the ALFLEX was to estimate the low-speed aerodynamic characteristics of a delta-winged vehicle with wingtip fins and experiments for this purpose, such as α/β sweep and control surface excitation, were conducted during hanging (suspended from a mother ship) and automatic landing test flights. When flight test data are analyzed, the aerodynamic characteristics of the ALFLEX vehicle are estimated and the results are compared with those predicted by wind-tunnel tests. Flight results show that estimated characteristics are similar to the predictions except for a few characteristics. Although the results from the hanging flight tests exhibit scattering that is due to measurement errors caused by the effects of an umbilical cable, the hanging test method will be useful if this problem is solved by means such as using an internal battery to supply power to the vehicle instead of the umbilical cable

Swept Surface Synthesis With Visibility

The visibility of a surface has wide applications in manufacturing, where accessibility of the workpiece to the processing agent is of critical importance. A surface is visible to a direction d if for every point on the surface a line-of-sight can be established along d. Important applications, such as die-face design, arise in manufacturing where surfaces must be constructed visible to a given direction. In this paper we present a family of swept surfaces with built-in visibility. In particular, methods are laid out to build translational, rotational and spined sweeps visible to a given direction by sweeping monotone section curves. In these methods, minimal limitations are imposed besides those needed to avoid surface singularities. To increase modeling flexibility, the methods are extended to sweeps with distinct end sections and nonuniform scaling functions. [S1087-1357(00)00103-9]