New approach to the automatic segmentation of coronary artery in X-ray angiograms

For the segmentation of X-ray angiograms （XRA）, the essential feature and the prior knowledge of angiographic image were analyzed, and a multi-feature based fuzzy recognition （MFFR） algorithm was proposed to infer the local vessel structure in this paper. Guided by the prior knowledge of artery vessel, a probability tracking operator （PTO） can rapidly track along the artery tree, and walk across the weak region or gaps because of disturbance or preprocessing to angiographic image. Another, the accurate measurement of the vascular axis-lines and diameters can be synchronously implemented in the tracking process. To correctly evaluate the proposed method, a simulated image of CAT and some clinical XRA images were used in the experimentations. The algorithms performed better than the conventional one： given one start-point, on average 92.7% of the visible segments or branches was automatically delineated; the correctness ratio of vessel structure inference reached to 90.0% on the average.     

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。     

新型高速大容量雷达数据记录器设计

提出了一种新型高速大容量雷达数据记录器的设计。为了将有效速度为59MB/s的雷达回波数据流及时、可靠的存储到记录器中,系统逻辑使用了乒乓缓存技术将其分解为两路速度为29.5MB/s的数据流并分别交叉写入两片Flash,这样大大减轻了单片Flash操作时序的压力。同时单片Flash运用了交错式双平面编程和高效的无效块管理,最大化的提高了芯片的写入速度。此数据记录器已经通过了振动、高低温、电磁兼容和冲击等实验,运行可靠稳定,同时已经交付部队使用。     

基于EMD和模极大值的造影图像血管提取

针对冠脉造影图像噪音大且血管边缘模糊问题,提出一种基于经验模态分解的冠脉造影图像血管提取方法以较完整有效地提取出造影图像中的血管信息。该方法首先对图像预处理后的造影图像进行经验模态分解,将其分解成若干图像层,保留包含血管信息的图像层并丢弃含非血管信息图像层;其次对保留的图像层进行血管特征提取,依据连通区域的一系列属性来提取图像层中血管信息以获取清晰明显的血管段;最后通过层间信息相互参照,重构血管脉络明显的心血管图像。实验证明了方法有很高的精确度和实际的医用价值。     

基于概率跟踪的冠状动脉造影图像的血管树提取

采用传统的基于跟踪的方法分割冠状动脉X射线造影图像的血管时,易受血管节点和曲率的影响.对此,本文提出了基于多特征测度的概率跟踪模型和中心线优化算子,该方法能够准确地分割出血管树的骨架并进行中心线优化.实验中,该方法不仅避免了传统方法的弊端,而且具有较低的计算耗时、较高的鲁棒性、全自动性:一次选定跟踪的起点,可以自动提取出80%以上冠状动脉树.     

四轴线切割变锥度异面加工控制的探讨

对现有四轴线切割锥度异面加工控制的模型进行了分析,指出了它们的缺点,指出全新的加工控制方案——双平面插补控制法,并给出了此方案的实现方法,从而大幅提高加工的精度和效率．指出此加工方案能控制常规锥度切割,同时也能加工复杂的变锥度异面工件．     

Application of compatible dual‐echo arteriovenography in stroke: Preliminary observations

Compatible dual‐echo arteriovenography (CODEA) is a recent MRI technique for simultaneous acquisition of an MR angiogram (MRA) and MR venogram (MRV) with image quality comparable to conventional single‐echo acquisitions. The purpose of this study was to evaluate the utility of CODEA in imaging patients with chronic stroke and to test the utility of a new image representation technique (“enhanced maximum intensity projection [MIP]") based on tissue segmentation, intensity inversion, and vessel enhancement filtering) for MRV. Arterial and venous abnormalities associated with stroke were delineated on MRA and MRV acquired simultaneously with the CODEA technique. CODEA MRV displayed with the enhanced MIP technique facilitated the visualization of the overall venous structures in 3D. Reduced venous vascularity was detected in the regions of arterial occlusion compared to the contralateral normal brain regions. The CODEA technique along with the enhanced MIP technique may be valuable, particularly in clinical applications that require efficient MRA/MRV imaging because of limited scan time such as in acute stroke. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 152–156, 2013     

冠脉树三维重建中血管段的匹配

针对冠状动脉树三维重建中血管段难以配准的问题，提出了一种新型的血管段匹配方法。该方法采用“有向二叉树”描述冠状动脉树的拓扑结构，然后根据外极线约束和拓扑约束，从冠状动脉树的根结点开始，沿血管行走方向逐级匹配分支点和端点，从而实现血管段的自动匹配。实验结果表明，该方法降低了冠状动脉树三维重建的复杂度，提高了重建的速度和精度。     

Aero‐structural investigation of biplane wind turbine blades

As wind turbines grow larger, loads increase dramatically, particularly in the inboard region of the blade. A key problem is to design a strong inboard region that supports these loads without sacrificing too much aerodynamic performance. A new design is proposed: a biplane inboard region that transitions into a joint, which connects to a monoplane outboard region. The objective is to develop biplane inboard configurations that improve the aero‐structural performance of blades. To approximately compare a conventional inboard region with a biplane inboard region, cross‐sectional properties of a thick monoplane and a biplane were measured. Numerical simulations were used to explicitly compare the aerodynamic performance of a thick monoplane with a biplane. Then, several model beams were designed to be simple approximations of a conventional blade (‘monoplane beam’) and the biplane blade (‘biplane beam’). Canonical bending loads were applied to each model beam, and their deflections were compared. Numerical simulations show that the lift‐to‐drag ratio is significantly greater for the biplane than the thick monoplane for 0° < α < 15.5°. A parametric analysis of biplane beam configurations shows that their tip deflections are smaller than monoplane beams of the same length. These benefits for the inboard region of (i) improved aerodynamics and (ii) improved strength could lead to weight reductions in wind turbine blades. Innovations that create lighter blades can make large blades a reality. These results suggest that the biplane blade is an attractive design for large blades. Copyright © 2012 John Wiley & Sons, Ltd.