Improvement of Pairwise Alignment by an Information Measure

The alignment of amino acid sequences is an important element in the study of life on the level of genome. There exist several methods to align the sequences by computer. In these methods there are several difficulties to judge whether the alignment result is proper. One of such problems is that many results give the same distance, so that often one cannot determine which result should be used. In this paper it is shown that the number of alignment results can be reduced by applying an information measure based on Shannon's mutual entropy.     

Pairwise Matching of 3D Fragments Using Cluster Trees

We propose a novel and efficient surface matching approach for reassembling broken solids as well as for matching assembly components using cluster trees of oriented points. The method rapidly scans through the space of all possible contact poses of the fragments to be (re)assembled using a tree search strategy, which neither relies on any surface features nor requires an initial solution. The new method first decomposes each point set into a binary tree structure using a hierarchical clustering algorithm. Subsequently the fragments are matched pairwise by descending the cluster trees simultaneously in a depth-first fashion. In contrast to the reassemblage of pottery and thin walled artifacts, this paper addresses the problem of matching broken 3D solids on the basis of their 2.5D fracture surfaces, which are assumed to be reasonable large. Our proposed contact area maximization is a powerful common basis for most surface matching tasks, which can be adapted to numerous special applications. The suggested approach is very robust and offers an outstanding efficiency.     

基于轮廓与断面匹配的秦俑碎片拼接方法

针对兵马俑第3次发掘大量破碎俑片的虚拟复原需求,分析秦俑碎片拼接的特殊性,归纳陶制碎片的分类原则,提出一种结合碎片边缘轮廓和断裂面匹配的混合拼接方法。依据俑体碎片断裂面厚度,将其映射到空间曲线模板或空间曲面模板。基于积分不变量计算俑体碎片特征向量,采用一致性约束方法获取碎片初始匹配点对。利用筛选算法去除伪初始匹配点对,应用几何哈希算法寻找碎片最优匹配点对。其中,空间轮廓曲线匹配基于多边形弧串匹配法,空间曲面匹配基于多尺度积分不变量法。对破碎兵俑和陶马的拼接结果表明,该方法能正确得到碎片间的匹配关系,具有较好的鲁棒性。     

成像测井中的裂缝图象识别与处理

碳酸盐岩、火成岩、硬砂岩中的裂缝性油气藏是近年来石油勘探的难点和重点,成像测井为裂缝识别和缝洞性储层参数计算提供了关键数据.此文分析了成像测井图象上的裂缝特征、裂缝类型及裂缝形态,应用HOUGH变换计算了裂缝的角度,在此基础上研究了假裂缝的识别方法,同时还计算出裂缝的长度、宽度、面积等参数.经过对胜利油田**井的图象资料处理表明,处理出的裂缝参数更准确地反映了地下地质构造特征.     

A Nondestructive Dynamic Characterization of a Microheater Through Digital Holographic Microscopy

This paper describes the possibility of employing a digital holographic microscope (DHM) to carry out a noncontact and nondestructive characterization of a microheater integrated on a silicon nitride membrane and subjected to a high thermal load. Microheaters can be affected by the presence of the residual stress due to the technological processes appearing in the form of undesired bowing of the membrane. Moreover, when the temperature of the microheater increases, a further warpage of the structure can be induced. A DHM allows for evaluation, with high accuracy, the deformations due to the residual stress and how these deformations are affected by the thermal loads due to the microheater operating mode. In particular, this dynamic analysis is made possible by measuring the unwanted longitudinal displacement induced by the thermal expansion of both the device and its mechanical support. Taking into account this displacement, it is possible to have a continuous monitoring of profile deformation induced by the working condition of the microheater.