一种基于最小割的稠密视差图恢复算法

针对经典最小割算法计算量大和适应性不足的问题,提出一种改进的基于网络最小割计算稠密深度图的全局优化方法.首先,根据视差变化与不连续区域之间的关系,定义了具有一定适应性的平滑约束和遮挡约束,然后使用网络最小割算法,求解遮挡情况下的稠密视差.其次,在分析最小割算法复杂性的基础上,给出了一种受限α-扩展(α-expansion)操作,该操作根据灰度连通性和特征点匹配的结果对每次网络构造的顶点进行控制,减少网络中顶点和边的数目,可有效提高计算效率.实验结果显示,该算法在保证视差恢复准确性的前提下,能以较快的速度计算出较理想的稠密视差图.

群体决策的α-较多扩展规则及其充要条件

集体选择规则的理性检验,是群体决策研究的基本理论课题.对于群体决策的简单多数规则,May K O曾建立了它的充要条件,Sen A K则给出了Pareto扩展规则的充要条件.笔者引进群体决策的一个包括简单多数规则为其特例的带参数α的α-较多扩展规则,在证明它满足的一组理性必要条件的基础上,也建立了它的充要条件.

Effect ofαphase morphology on fatigue crack growth behavior of Ti−5Al−5Mo−5V−1Cr−1Fe alloy

Taking a Ti−5Al−5Mo−5V−1Cr−1Fe alloy as exemplary case,the fatigue crack growth sensitivity and fracture features with various tailoredαphase morphologies were thoroughly investigated using fatigue crack growth rate(FCGR)test,optical microscopy(OM)and scanning electron microscopy(SEM).The tailored microstructures by heat treatments include the fine and coarse secondaryαphase,as well as the widmanstatten and basket weave features.The sample with coarse secondaryαphase exhibits better comprehensive properties of good crack propagation resistance(with long Paris regime ranging from 15 to 60 MPa·m1/2),high yield strength(1113 MPa)and ultimate strength(1150 MPa),and good elongation(11.6%).The good crack propagation resistance can be attributed to crack deflection,long secondary crack,and tortuous crack path induced by coarse secondaryαphase.

Transforming growth factor-α promotes mouse blastocyst outgrowth and secretion of matrix metalloproteinases

Objective To study the effect of transforming growth factor-α (TGF-α) on early stage of embryo implantation.Methods Mouse blastocysts were cultured in vitro in medium containing various concentrations of TGF-α. Blastocyst implantation capacity was evaluated by calculating the percentage of embryos with attachment or outgrowth. Matrix metalloproteinases (MMPs) secretion of blastocysts was observed using gelatin zymography. Results There was no significant difference in the percentage of attachment between control and TGF-α treated groups, but the percentage of outgrowth of TGF-α treated groups was significantly higher than that of the control group after 24h culturing. Gelatin zymography showed that blastocysts cultured in TGF-α treated groups started secreting MMPs earlier than those in the control group.Conclusion TGF-α is involved in regulating the mouse embryo implantation process by promoting blastocyst outgrowth and secreting matrix matalloproteinases.

高分辨率遥感影像中建筑物轮廓信息矢量化

针对高分辨率遥感影像的特点,提出了基于多类分割与模板匹配的建筑物轮廓矢量化方法:首先对影像进行多尺度SVM分割获取建筑物候选点;然后在Radon变换结合主轴分析获取建筑物主方向的基础上,引入多类分割思想,构建用于分割的能量函数,基于α-扩展算法解算能量函数,将轮廓线分割为3类边缘线段;接着构建形状先验的边缘模板,进行精确定位以获取边缘线的实际位置,去除锯齿状变形,降低提取结果的影响;最后相邻边缘线相正交得到拐角点,依次连接每一个拐角点,得到规则化的建筑物轮廓。相比于同类其他方法,此方法考虑了边缘点的方向信息和相邻边缘点趋于同一类的先验知识,可得到近似全局最优的边缘线段分割结果,避免了规则化过程中选择初始点和处理顺序的麻烦和不利影响,同时充分利用了影像特征,对边缘线段进行精确定位,减弱建筑物提取结果误差的影响。对不同影像的实验结果证明此方法可得到规则化的建筑物外轮廓线,不考虑提取过程中遗漏的建筑物,矢量化结果平均准确度为89%、完整度98%、几何形状相似性87%、整体质量85%。