Surface tension powered self-assembly of 3-D micro-optomechanicalstructures

A new surface micromachining process for surface tension powered self-assembly of silicon-based microstructures is described. Mechanical parts are formed from bonded silicon-on-insulator material and rotated out-of-plane by melting photoresist pads at tow temperature. Simple mechanisms that allow accurate control of the final angle are introduced and used to construct fixed 45° mirrors and scanning mirror assemblies     

Surface tension driven formation of microstructures

The controlled formation of curved, three-dimensional (3-D) microstructures can be accomplished through solidification from a liquid phase. As a demonstration, we have placed objects in contact with the interface of a photopolymerizable liquid and air to create various liquid menisci that were subsequently solidified with ultraviolet radiation. Geometric control is achieved through variation of physical and environmental parameters; for example, solidified menisci formed at 25/spl deg/C were 300 /spl mu/m taller than those formed at 7/spl deg/C. Comparisons between the polymerized structures and theoretical predictions for liquid menisci indicate that the polymerization process results in repeatable changes in contact angle and meniscus size.     

Surface tension driven flow for open microchannels with different turning angles

Present study examines the flow characteristics of open microchannels with sharp turns by experimental and numerical methods. For the open channel system in microscale, the flow is mainly driven by surface tension at atmospheric pressure. The open channels are of various aspect ratios of depth-to-width, ranging from 0.75 to 3, and of turning angles from 45° to 135°. It is found that the turning angle and the aspect ratio of depth-to-width play major roles in the velocity of liquid front advancing, the meniscus of liquid–gas interface shape, and head loss of flow due to turning. Besides, the radius of curvature of the liquid front is reduced as the liquid front travels downstream and over the turning elbow. The loss coefficient remains the same for turning angles less than 75°, whereas it is increased further and is even more pronounced for turning angles larger than 105°. Numerical predications based on conservation laws agree with the experimental observations, and the flow characteristics are well described for open channel in microscale, as the aspect ratio is greater than or near to 1.5.     

三维图形简化新算法

本文的图形简化新算法,具有保细节.保真和快速等优点D快速是采用传播法快速形成近平面块的结 果D保真和保细节都是可以控制的.算法规整,效果良好,适应面宽,很有实用价值.     

无对应点三维表面重建的全局优化算法

一、三维平面重建问题陈述图1是成象系统,包括一对焦距f=1的照相机。两坐标系间的关系是 (X_R,Y_R,Z_R)=(X_L-b,Y_L,Z_L)。三维点(X_L,Y_L,Z_L)在左、右图象平面的投影分别是 (x_L,y_L)=(X_L/Z_L,Y_L/Z_L) (x_R,y_R)=(X_R/Z_R,Y_R/Z_R) =((Z_L-b)/Z_L,Y_L/Z_L) (1)则水平和垂直方向的差异场分别是δ_x=x_L-x_R=b/Z_L; δ_y=y_L-y_R=0 (2) 图1 平行轴立体成象系统假设三维点位于平面Z=Z_0+PX+QY上,则对应点匹配约束条件是     

Approximation-Based Similarity Search for 3-D Surface Segments

The issue of finding similar 3-D surface segments arises in many recent applications of spatial database systems, such as molecular biology, medical imaging, CAD, and geographic information systems. Surface segments being similar in shape to a given query segment are to be retrieved from the database. The two main questions are how to define shape similarity and how to efficiently execute similarity search queries. We propose a new similarity model based on shape approximation by multi-parametric surface functions that are adaptable to specific application domains. We then define shape similarity of two 3-D surface segments in terms of their mutual approximation errors. Applying the multi-step query processing paradigm, we propose algorithms to efficiently support complex similarity search queries in large spatial databases. A new query type, called the ellipsoid query, is utilized in the filter step. Ellipsoid queries, being specified by quadratic forms, represent a general concept for similarity search. Our major contribution is the introduction of efficient algorithms to perform ellipsoid queries on multidimensional index structures. Experimental results on a large 3-D protein database containing 94,000 surface segments demonstrate the successful application and the high performance of our method.     

一种基于B样条曲面的深度图像重抽样方法

银行深度图像处理中由于等角测距造成的几何失真,根据非等网格深度数据的数值特点,文中提出了一种基于B样条曲面的深度图像重抽样方法,并且与其它一些三维插值方法进行了精度比较。该文利用真实深度图像进行了重抽样实验,结果表明,基于B样条曲面的重抽样方法有效地克服了原始图像数据中存在的几何失真以及测量噪声,为后续的三维表面处理提供了更为精确的三维网格深度数据。     

CCD传感器在三维表面测量中的应用

本文采用电荷耦合成像的CCD摄像机获取立体图像,利用面积相关与灰暗度相关性,为精确地计算三维表面坐标、图像处理提供了一种新的测量三维表面的方法。     

三维表面平滑约束断层图象形状插值

断层图象序列的层间插值是三维重建的关键技术之一。已有的断层插值方法主要使用灰度，灰度梯度，距离，方向等约束，重建的三维表面往往不平滑，本文引入有向距离概念，增加表面平滑约束，提出一种重建三维平滑表面的断层图象间形状插值方法。     

A framework for rapid evaluation of heterogeneous 3-D NoC architectures

The scalability of communication infrastructure in modern Integrated Circuits (ICs) becomes a challenging issue, which might be a significant bottleneck if not carefully addressed. Towards this direction, the usage of Networks-on-Chip (NoC) is a preferred solution. In this work, we propose a software-supported framework for quantifying the efficiency of heterogeneous 3-D NoC architectures. In contrast to existing approaches for NoC design, the introduced heterogeneous architecture consists of a mixture of 2-D and 3-D routers, which reduces the delay and power consumption with a slight impact on packet hops. More specifically, the experimental results with a number of DSP applications show the effectiveness of the introduced methodology, as we achieve on average 25% higher maximum operation frequency and 39% lower power consumption compared to the uniform 3-D NoCs.     

由任意形状轮廓线重建三维表面的方法研究

由一组二维轮廓线重建出物体的三维表面是医学数据可视化的一种主要绘制方式。当轮廓线比较复杂,例如当遇到非凸轮廓或相邻层轮廓线相差过大时,常用的三角化拼接方法就会失败。文章提出一种新的轮廓拼接方法能够处理任意形状的轮廓线。该方法的基本思想是对轮廓线进行凹凸性层次分析,然后将相邻轮廓线从外到内逐层拼接,从而构成一个三角化的物体表面。实验结果表明,该算法对于手动勾画和自动提取的轮廓线都可以给出较好的重建效果。     

基于表面粗糙度的三维模型质量评价研究

数字水印的嵌入会引起三维模型数据的失真,正确评价含水印三维模型的质量可以为三维水印算法的测评提供统一标准。提出了一种新的三维模型质量的评价方法,它首先利用网格模型中二面角为基本度量单位计算出整个原始三维模型的粗糙度,然后在嵌入水印以后用同样的方法计算出含水印三维模型的粗糙度,最后得到嵌入水印前后粗糙度的增量,并将其作为水印嵌入对三维模型造成的失真度的度量。大量实验结果表明,相比传统的质量评价方法,该方法更加适用于三维网格模型。该质量评价方法还可用于评价各种水印攻击对含水印三维模型造成损害的程度。     

等高线的光滑内插重构三维物体

三维曲面重构技术在现实中有着广泛的应用,目前已经有多种三维曲面重构技术出现．本文通过对当前各种三维重构算法的研究,在DSI算法的基础上提出了一个三维曲面模型重构的新方法。该方法简捷直观,集成了其它方法的优点,而又避免了它们的不足。     

一种医学图像的3-D表面重建方法

等值面绘制算法是医学图像表面重建的一种重要方法,但是它需要用户根据经验设定阈值。本文运用OTSU算法来获取体数据各类组织的灰度阈值,由此求得各类组织的灰度均值,并以此作为等值面阈值。在VTK中的重建实例表明,该方法能够体现出不同组织影像的灰度分布特点,使重建后的图像信息更丰富、表面更平滑。     

综合利用VB与Surfer实现地学三维曲面的动态显示

Surfer软件具有较完美的数据处理和显示功能。文中通过Surfer下编程调用绘图函数,和VB与Surfer混合编程以增强操作交互性这两条途径,在充分利用Surfer强大的绘图功能的基础上,实现了三维曲面的动态显示。     

一个基于结构化特征匹配的月面三维重建方法

基于图像建立三维月面地图对于月球车任务规划、导航控制具有重要意义。本文提出一种基于参数化轮廓结构特征匹配的月面三维重建方法，该方法从月面立体图像中提取特 征物的轮廓特征，通过参数化轮廓特征匹配恢复特征物的三维信息，从而建立三维月面地图。本文以Apollo 15登月计划的着陆区域为例，建立了一个三维月面地图。     

Building Skeleton Models via 3-D Medial Surface Axis Thinning Algorithms

In this paper, we present an efficient three-dimensional (3-D) parallel thinning algorithm for extracting both the medial surfaces and the medial axes of a 3-D object (given as a 3-D binary image). A new Euler table is derived to ensure the invariance of the Euler characteristic of the object, during thinning. An octree data structure of 3 × 3 × 3 lattice points is built to examine the local connectivity. The sets of "simple" points found by different researchers are compared with the constructed set. Different definitions of "surface" points including ours are given. By preserving the topological and the geometrical conditions, our algorithm produces desirable skeletons and performs better than others in terms of noise sensitivity and speed. Pre- and postprocessors can be used to remove additional noise spurs. Its use in defect analysis of objects produced by casting and forging is discussed.     

Free-Form Simulation of Sequential Etching and Surface Characterization for 3-D MEMS Fabrication

A new diffusion-based simulation model of isotropic wet etching and free-form surface characterization method for 3-D free-form microelectromechanical systems (MEMS) fabrication is presented in this paper. To simulate the etching process, a diffusion-based model solved by the finite-element method (FEM) has been developed, allowing extraction of more accurate etch-front data at discrete time steps. In the developed method, free-form MEMS objects are modeled as B-spline functions with material concentration. Finite elements are generated by discretization in the parametric domain of the free-form object and mapping back to the Euclidean space. Points on the etch front are extracted using a Z-map method. The extracted point data are characterized to obtain a B-spline representation of the etch-front surface. Examples from the isotropic etching simulation of 2-D and 3-D objects with both regular and free-form geometry are presented. The developed method allows the simulation of 3-D objects with free-form input and free-form mask opening and facilitates the simulation of sequential etching of free-form objects with irregular mask openings. This paper also discusses applications of the developed method in MEMS process planning that can be realized by taking advantage of the better control of geometry that it provides in MEMS fabrication.     

基于凸包算法的三维表面重建中边缘轮廓提取

在三维表面重建过程中,边缘轮廓的提取起着关键的作用.为了对头部CT图片中的颅骨边缘进行有效地提取,提出利用平面凸包进行边缘轮廓提取的方法.利用该方法提取出头部CT图像中的颅骨边缘,并将其作为三维表面重建中的轮廓输入,取得了良好的效果.同时,将通过该方法得到的颅骨边缘应用于基于颅骨的三维面貌复原技术研究中,为面貌复原技术的发展提供了新的思路.