平面域任意散乱点自动三角化的研究

基于平面区域内散乱点的Ｄｅｌａｕｎａｙ三角剖分准则,本文提出一种适用于平面区域内任意散乱点的通用三角化算法。文中详述了三角化的具体实现过程和在三角化过程中可能出现的各种“接触”情况,给出了程序流程图。最后给出实例并把此种方法成功地运用到三维光学数字成像系统。     

工程图中查找极值点及视图划分中心点的算法

提出了自动识别工程图中视图极值点和视图划分中心点的方法;叙述了图元包围盒的思想:给出了三视图划分的两种预处理算法,即二分扫描线算法和极大相邻坐标扫描线算法.针对后一个算法,给出了基本图元包围盒的性质,定义了图元包围盒一维投影轴的概念和相应的视图划分原则.通过获取的视图极值点及视图划分中心点,可将同属一个全局坐标系中的三个视图分开,为后续建立三视图的局部坐标系作准备.     

裁剪曲面的三角化及图形显示

结合自主版权的超人ＣＡＤ／ＣＡＭ系统的开发，本文提出了一种适合于裁剪曲面图形显示的曲面三角化算法，该算法将曲面的三角化转化为曲面参数域的三角化，并将二维图形的集合运算与Ｄｅｌａｕｎａｙ三角剖分应有和于曲面参数域边界的处理，从而使裁剪曲面在边界上的三角形分布均匀。     

一种基于单调多边形的三角剖分算法

提出了一种基于单调多边形三角化算法,被三角化的多边形可以含有任意个内孔。先根据边界y（x）方向的局部极值顶点作水平（垂直）分割线,将多边形划分成单连通y（x）单调多边形,然后再将各单调多边形三角化。算法考虑了各种几何奇异情况,因此比较稳定。     

由三视图重建三维物体

本文描述的三维重建的方法旨在从提高重建效率和扩大形体覆盖域两个方面改进现有算法。本算法模拟人工识图的经验,采用启发式的搜索方式,加速了由解空间求解的进程,程序改造了一些基本模块的现有算法,提出了通过构造“生成树”搜索物体表面投影的“环路搜索法”,还提出了寻找基本块的“一点入手,两边定面”的搜索方法,本算法已能处理由平面及圆柱面构成的物体,其中通过完整表面轮廓线和切边在各个视图中的投影,已使轴矢量处于空间任意位置的圆柱表面得到了重建,文章阐述了形体覆盖域进一步扩展的可能。病态问题和多解情况在程序中得到了处理。     

工程图中建立各分视图坐标中心及局部坐标系的算法

已知三视图极值点和三视图划分点,提出了建立各分视图坐标中心及局部坐标系的方法.给出了两种算法:坐标中心通用求解算法和原点取整平移算法.采用ObjectARX的选择集函数及视图变换建立了各分视图的局部坐标系,为后续的图形正误判断或三维重建作了准备.     

一种裁剪曲面自适应三角剖分算法

本文介绍了一种裁剪曲面按精度三角剖分算法。三角剖分过程在参数域和曲面空间同时进行，参数域上控制三角片的拓扑关系，曲面空间进行精度检测。算法的核心思想是将裁剪曲面三角剖分视为约束剖分问题，从而使得三角形的细分操作拓展为有效域内插入散乱节点的三角剖分问题。算法简便、实用，三角化结果品质良好，已成功地应用于数控加工刀具轨迹干涉处理等具有精度要求的应用领域。     

CAD/CAM中三角超限插值曲面的应用

本文提出了一类带控制顶点的三角超限插值样条曲面,它具有现有超限插值曲面及形状控制曲面的优点。文章推导并讨论了“边-点”和“边-边”两种格式,并给出了“边-点”格式的实现算法。     

距离查找表的产生及其在三维传感中的应用

本文提出了一种快速、简便的三角剖面术查找表算法。根据这种算法,可以从样板上测量三个以上不同高度的点在CCD上成象位置,综合出距离查找表。采用这种方法可以加快以三角剖面术为基础的三维测量过程,减小误差,更重要的是当系统结构发生变化时(如重新安装系统或运输后),可以对样板重新测量,产生新的距离查找表,从而对系统进行自动校正。该算法已在四川大学研制的“鞋楦三维面形自动测量系统”中应用,获得了预期的结果。     

用改变表面位置的方法设计平面立体的视图

用改变表面位置的方法设计平行面立体和垂直面立体的视图，它是基于压缩坐标形成视图的原理，先设定一个视图，在该视图上拟出可见面和 不可见面，在另外两个视图上确定各表面的位置，连接各表面的端点重影点，可以设计出立体的另外两个视图，交叉改变各表面的位置，就可以设计出多种形状各不相同的立体的视图，应用此法不仅可设计平面立体的视图，并可设计曲面立体的视图。     

Ultra-high-precision alignment of the elastomerically mounted elements of the science camera lenses for the Mars Science Laboratory (MSL) rover

Cameras built for space exploration are required to meet stringent environmental conditions, such as thermal and dynamic loads for both the optics (camera lens) and imaging electronics. On a multitude of spaceborne imaging instruments, optical elements are supported in their mounts via an elastomeric bonding approach using a room temperature vulcanizing silicone as the bonding agent. Employing this integration method, we achieved element-to-element alignment, measured as the total indicated runout, using a high-precision contact probe to be on the order of half a wavelength of He-Ne laser light, or 0.3?μm, on the Malin Space Science Systems lenses for the Mars Science Laboratory (MSL) cameras. This is a higher precision than the current industry state-of-the-art, and it was achieved for the very challenging small diameter lens elements. This paper describes the design philosophy, implementation, and integration method that resulted in achieving this level of precision for interelement alignment. The results are based on actual measurements that were made during the process of building the MSL rover's science camera lenses, namely Mastcams, the Mars Hand Lens Imager, and the Mars Descent Imager. The optical designs of these cameras lenses are described in detail in [Opt. Eng.48, 103002 (2009)], while further information on the four science cameras can be found at http://www.msss.com.     

Generation of photorealistic 3D image using optical digitizer

A technique to generate a photorealistic three-dimensional (3D) image and color-textured model using a dedicated optical digitizer is presented. The proposed technique is started with the range and texture image acquisition from different viewpoints, followed by the registration and integration of multiple range images to get a complete and nonredundant point cloud that represents a real-life object. The accuracy of the range image and the precision of correspondence between the range image and texture image are guaranteed by sensor system calibration. Based on the point cloud, a geometric model is established by considering the connectivity of adjacent range image points. In order to enhance the photorealistic effect, we suggest a texture blending technique that utilizes a composite-weight strategy to blend the texture images within the overlapped region. This technique allows more efficient removal of the artifacts existing in the registered texture image, leading to a 3D image with photorealistic quality and color-texture modeling. Experimental results are also presented to testify to the validity of the proposed method.     

A Large Range Flexure-Based Servo System Supporting Precision Additive Manufacturing

This paper presents the design, development, and control of a large range beam flexure-based nano servo system for the micro-stereolithography (MSL) process. As a key enabler of high accuracy in this process, a compact desktop-size beam flexure-based nanopositioner was designed with millimeter range and nanometric motion quality. This beam flexure-based motion system is highly suitable for harsh operation conditions, as no assembly or maintenance is required during the operation. From a mechanism design viewpoint, a mirror-symmetric arrangement and appropriate redundant constraints are crucial to reduce undesired parasitic motion. Detailed finite element analysis (FEA) was conducted and showed satisfactory mechanical features. With the identified dynamic models of the nanopositioner, real-time control strategies were designed and implemented into the monolithically fabricated prototype system, demonstrating the enhanced tracking capability of the MSL process. The servo system has both a millimeter operating range and a root mean square (RMS) tracking error of about 80 nm for a circular trajectory.     

Phase behavior characterization of propylene glycol, white petrolatum, surfactant ointments

Ointment vehicles consisting of moderate amounts of propylene glycol (5-10%) and large amounts of white petrolatum (greater than 80%) were investigated by determining the ternary phase behavior between these two components and each of five surfactants exhibiting a range of physical properties. The commercial anionic surfactant Pationic SSL performed better as an emulsifier for propylene glycol and white petrolatum than did Lexamul 515, Lexamul AR, Arlacel 20, or Grilloten ZT 40. From this study a formulation consisting of 7% propylene glycol, 90% petrolatum, and 3% Pationic SSL was considered to be an optimized propylene glycol/white petrolatum ointment base.     

Phase behavior characterization of propylene glycol,white petrolatum,surfactant ointments

Abstract

Ointment vehicles consisting of moderate amounts of propylene glycol (5–10%) and large amounts of white petrolatum (greater than 80%) were investigated by determining the ternary phase behavior between these two components and each of five surfactants exhibiting a range of physical properties. The commercial anionic surfactant Pationic SSL performed better as an emulsifier for propylene glycol and white petrolatum than did Lexamul 515, Lexamul AR, Arlacel 20, or Grilloten ZT 40. From this study a formulation consisting of 7% propylene glycol, 90% petrolatum, and 3% Pationic SSL was considered to be an optimized propylene glycol/white petrolatum ointment base.     

Multiview foreground extraction and composition to multiview background using trimap sharing for natural 3D scene generation

Digital matting for extracting foreground objects from an image is an important process to generate special effects in the movie industry and the broadcasting center. Recently, a digital matting algorithm has been developed to create an alpha matte using a well‐focused image generated from multiview images. However, this method could generate only a single‐view alpha matte, even though it used multiple cameras. In this article, we propose a new estimation scheme for multiview alpha mattes by sharing the trimap of the reference view. Furthermore, we use the motion vector to update the trimap for video matting. After we extract foreground objects from all view images, we composite the foreground objects with the corresponding background images captured in the same multiview camera arrangement. Experimental results demonstrate that multiview composite images can generate reasonably natural 3D views through the stereoscopic monitor. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 285‐293, 2010     

Characterization of a focal plane camera fitted to a Mattauch-Herzog geometry mass spectrograph. 1. Use with a glow-discharge source

A Mattauch-Herzog geometry mass spectrograph (MHMS) has been equipped with a novel array detector, the focal plane camera (FPC). The FPC consists of an array of gold Faraday cups, each coupled to its own integrator, with interrogation of the integrators performed by a multiplexer. The initial coupling of this instrument with a pin-type glow discharge source has provided limits of detection in the single to hundreds of nanograms per gram regime; isotope ratio accuracy and precision better than 5% error and 0.2% RSD, respectively; and a linear dynamic range of at least 6 orders of magnitude. A current weakness of the FPC is its pixel size, which limits both sensitivity and baseline resolution (to R = 130). The minimum data acquisition time for multiple images at present is 1 ms/image, with a dead time of 3.2 ms between images, which will limit the ability of the FPC to monitor extremely short transient signals.     

低分辨率多描述编码图像的超分辨率重构

图像的高质量、低帧率传输有较广泛的应用.由于传输信道的不可靠、易丢包或误码等固有特性使传输图像降质甚至无法正常译码.本文对原图像亚采样后进行低分辨率多描述编码以增强传输鲁棒性,接收端再采用多幅解码图像超分辨率重构,可在相同信道条件下得到2～3 dB的PSNR增益.并且可以结合目前几乎所有的图像多描述编码技术和超分辨率重构算法,有很强的应用和推广价值.     

Electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy study of the response mechanism of the chalcogenide glass membrane iron(III) ion-selective electrode in saline media

The response mechanism of the iron(III) chalcogenide glass membrane ion-selective electrode (ISE) in saline media has been studied using electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). EIS equivalent circuits and XPS surface compositions for the FeIII ISE are consistent with the presence of two surface films probably comprising a outer surface layer (OSL) and an Fe-deficient modified surface layer (MSL), along with a low-frequency charge-transfer impedance that is attributable to the reduction of Fe3+. In accordance with literature data for the conductivity of low-bearing iron(III) chalcogenide glasses, a high-impedance MSL is internally consistent with XPS data for an Fe-deficient MSL. It is evident that the impedance of the MSL diminishes on exposure to solutions containing Fe3+, and this finding is consistent with the ion exchange of Fe3+ within the MSL. Likewise, the charge-transfer impedance also decreases at elevated levels of Fe3+, demonstrating that Fe3+ is a participant in the reversible charge-transfer reaction occurring at the electrolyte/electrode interface. The kinetics of charge transfer are facilitated by Fe chelating agents (e.g., citrate, salicylate, EDTA, etc.) due presumably to the complexation of the products of the charge transfer process (possibly Fe2+). It is shown unequivocally that the response of the FeIII ISE in saline buffers is independent of pH, demonstrating that the ISE is responding directly to Fe3+, not H+. A mechanism involving a combination of charge transfer and ion exchange of FeIII, at the electrode diffusion layer, has been proposed to explain the 30 mV/decade slope of the FeIII ISE.     

MLEM deconvolution of protein X-ray diffraction images based on a multiple-PSF model

In this paper we analyze the degradation of protein X-ray diffraction images by diffuse light distortion (DLD). In order to correct the degradation, a new multiple point spread function (PSF) model is introduced and used to restore X-ray diffraction image data (XRD). Raw PSFs are collected from isolated spots in high-resolution areas on the diffraction patterns which represent the orientation of DLDs. An adaptive ridge regression (ARR) technique is used to remove noise from the raw PSF data. A target Gaussian function is used to model the raw PSFs. A maximum likelihood expectation maximization (MLEM) algorithm combined with a multi-PSF model is employed to restore high intensity, asymmetrical protein X-ray diffraction data. Experimental results using a single and multiple PSFs are presented and discussed. We show that using a multiple PSF model in the deconvolution algorithm improved the quality of the XRD and as a result the spot integration error (/spl chi//sup 2/) and corresponding electron density map are improved.