变形模型技术在冠状动脉造影图像序列后处理中的应用

以冠状动脉血管轴线的三维运动跟踪和心脏的形状建模为例,论述了变形模型在X射线心血管造影图像序列后处理中的应用.首先采用3D snake模型,表示血管轴线的曲线在三维空间中的变形,完成对血管骨架的序列重建.然后以各时刻的血管骨架点作为采样点,采用基于扩展超二次曲面的变形模型,建立心脏形状模型,通过分析不同时刻模型参数的变化,获得心脏变形参数的估计.     

弹性配准在冠状动脉三维运动分析中的应用

针对冠状动脉的运动分析问题,本文提出基于弹性配准的血管骨架三维运动估计方法.在对X射线冠脉造影图像序列进行三维血管骨架序列重建的基础上,寻找两个时刻同一血管分支上点之间的对应关系,得到各点的运动向量.通过使适当的目标函数最小化,运用动态规划算法,得到最优匹配.通过采用运动场已知的模拟数据对算法精度进行定量估计,并采用临床图像序列进行实验,结果表明,算法具有较高的精度和较快的运算速度.     

造影图像序列中动脉血管的三维测量

针对X射线心血管造影图像的后处理问题,本文提出一种采用两个近似正交的单面X射线造影图像序列对冠状动脉的三维形状和运动参数进行定量测量的方法.该方法首先采用snake技术从两个角度的图像中重建出各时刻的三维血管轴线.根据三维重建和二维提取的结果,完成对血管形状参数(如长度和腔径)的测量.然后将血管运动场的估计转化为对相邻时刻间血管分支轴线的逐点匹配,并获得位移幅值和运动轨迹等重要参数.最后分别采用模型的X射线图像、计算机模拟数据和临床图像对该方法进行了验证.实验结果表明,该方法是可行的.     

基于造影图像的冠状动脉血管三维表面重建方法

在冠状动脉树骨架三维重建的基础上,研究了基于造影图像的血管表面重建方法。首先采用B样条曲线拟合血管的三维骨架,建立了骨架点的局部坐标系。同时研究了血管横截面的椭圆模型,并推导了椭圆方程。针对血管树表面重建中的自相交问题,提出一种新型顶点融合技术,给出了融合点的计算方法。最后利用两幅不同角度的临床冠脉造影图像,成功实现了血管的三维表面重建。     

基于光流法的冠状动脉造影图像序列中血管运动的估计

利用冠状动脉造影图像序列进行二维血管运动的分析，对于准确估计与解释心脏的运动，从而正确诊断心血管和心脏疾病十分关键。同时也是由血管造影图进行冠状动脉树三维重建的重要步骤。笔者采用光流法对单面冠状动脉造影图像序列进行血管运动估计，以动脉分叉点作为运动跟踪的标志，并提出在很短的时间间隔内冠状动脉上很小部分的运动可以认为是简单平移的假设，从而计算出血管以及相关心外膜的运动参数。     

动态规划在运动图像分析中的应用

对运动图像序列中的目标进行运动跟踪和估计,可以分别采用变形模型和弹性配准的方法,两问题的求解均可归纳为成本函数的最优化问题。提出了应用动态规划算法求解离散成本函数最优化的方法,把问题分解成多个子问题分别求解,并存储子问题的解以避免重复计算。该方法不仅可保证解的全局最优性,而且计算量小,有利于实现实时处理。在对临床X射线冠状动脉造影图像序列的实验中得到了满意的结果,匹配大约2000个点的血管骨架只需要一秒钟左右的时间。对运动场已知的模拟图像的实验证明运动估计误差小于1个像素（1像素=0．3mm）。     

冠状动脉造影图像序列中估计二维运动及变形的弹性配准算法

提出一种由单面血管造影图像序列分析心脏冠状动脉运动和变形的方法，即利用弹性配准算法，将动脉运动的估计简化为对连续两帧图像的骨架像素的匹配．采用动态规划的方法进行配准，同时引入自回归建模，二者结合起来互相作用：动态规划为自回归模型参数的估计提供样本值；自回归模型为动态规划提供适当的成本函数。采用临床得到的单面冠状动脉造影图像序列对该算法进行了验证。实验结果表明应用该方法计算血管骨架图像中各点的光滑移动向量场，能够得到精确的结果。     

基于B样条的冠状动脉树骨架三维重建方法

以B样条曲线为基元，根据两幅不同角度的冠脉造影图像重建冠状动脉树的三维骨架。首先采用B样条曲线的“迭代最近点拟合算法”拟合二维血管中心线，由二维控制点计算三维控制点，然后根据曲线拟合误差和对应点匹配误差优化三维B样条控制点，最后得到冠状动脉树三维骨架的B样条描述。利用临床冠脉造影图像进行冠脉树骨架的三维重建实验，结果表明本重建方法比传统方法在重建精度和算法复杂性上都有较大的改善。     

基于场景平面结构的增强现实方法

提出了一种基于场景平面结构的增强现实方法.首先,选定图像序列中的两帧对目标场景进行局部的三维重建;然后,选择场景中某一平面作为处理和跟踪的对象,通过交互指定该平面内矩形的四个顶点作为虚拟对象的嵌入区域并建立局部参考坐标系,从而实现虚拟对象与三维场景的迅速对齐;最后通过鲁棒的场景平面跟踪算法实现虚拟对象在整个图像序列中的真实感嵌入,完全允许嵌入区域被部分遮挡的情况.真实序列图像的实验结果及对算法的分析验证了方法的有效性和可行性.     

基于自适应前景分割及粒子滤波的人体运动跟踪

提出了在图像序列中用自适应前景分割及粒子滤波对人体的3-D运动轨迹进行跟踪的方法．首先建立了像素点的高斯模型,并结合图像帧间的差分信息以及灰度分布的先验概率等因素完成了图像中人体的自适应分割．根据所得到的分割结果建立了透视投影下的运动平面跟踪模型．根据投影过程的非线性以及图像中噪声分布的未知性,提出了粒子滤波的跟踪方法,并最终得到了人体运动平面的3-D轨迹．实际人体运动图像序列的实验证明,本文方法能有效地跟踪人体运动的3-D轨迹,并反映出在此跟踪问题上粒子滤波比传统的扩展卡尔曼滤波更具优势．     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to