一种变形表面的三维测量方法

提出一种新的利用标定图像进行三维测量的方法。利用SIFT算法找到初始的对应点,然后根据这些点生成三维空间中的种子点,再以这些种子点为中心,向外区域增长,直到完成整个物体表面测量。在每次增长的过程中,需要计算增长的三维空间平面在两个相机上的投影之间的图像相关系数。图像相关系数较大时认为是正确的增长,否则是错误的增长。实验证明,使用该方法能够得到很好的三维测量结果。     

基于英汉平行语料库术语词典的自动抽取

该文提出了一种从英汉平行语料库中自动抽取术语词典的算法。采用的是已对齐好的双语语料,中文经过了分词处理。利用英文和中文词性标注工具对英文语料和中文语料分辨进行词性标注。统计双语语料库中的名词和名词短语生成候选术集。然后对每个英文候选术语计算与其相关的中文翻译间的翻译概率。再通过设定阈值过滤掉一些与该英文候选词无关的中文翻译,最后通过贪心算法选取概率最大的词作为该英文候选词的中文翻译。     

一种基于使用差异的词语领域性分析方法

领域知识的表达形式最终体现在词汇的领域性上,因此对领域词及其部件的领域度分析是一个关键。该文在分词的基础上,对各个领域语料进行分析,利用词语之间的关系,引入链接分析方法分析词语在各个领域中的使用重要性,并通过词语在各个领域中的使用差异性计算其领域度,从而达到领域分析的目的,获取某个领域的领域部件词。该文采用以上方法在军事、娱乐等领域进行了实验,实验结果表明该方法相对于当前常用的tf×idf方法和Bootstrapping方法,可以更有效地进行领域分析获取领域部件词。     

Detecting Overlapping Community Structures in Networks

Community structure has been recognized as an important statistical feature of networked systems over the past decade. A lot of work has been done to discover isolated communities from a network, and the focus was on developing of algorithms with high quality and good performance. However, there is less work done on the discovery of overlapping community structure, even though it could better capture the nature of network in some real-world applications. For example, people are always provided with varying characteristics and interests, and are able to join very different communities in their social network. In this context, we present a novel overlapping community structures detecting algorithm which first finds the seed sets by the spectral partition and then extends them with a special random walks technique. At every expansion step, the modularity function Q is chosen to measure the expansion structures. The function has become one of the popular standards in community detecting and is defined in Newman and Girvan (Phys. Rev. 69:026113, 2004). We also give a theoretic analysis to the whole expansion process and prove that our algorithm gets the best community structures greedily. Extensive experiments are conducted in real-world networks with various sizes. The results show that overlapping is important to find the complete community structures and our method outperforms the C-means in quality.     

Up in smoke: I. Smoke-derived germination cues for postfire annual,Nicotiana attenuata torr. Ex. Watson

Some postfire annuals with dormant seeds use heat or chemical cues from charred wood to synchronize their germination with the postfire environment. We report that wood smoke and polar extracts of wood smoke, but not the ash of burned wood, contain potent cue(s) that stimulate germination in the postfire annual plant,Nicotiana attenuata. We examined the responses of seeds from six populations of plants from southwest Utah to extracts of smoke and found the proportion of viable seeds that germinated in the presence of smoke cues to vary between populations but to be consistent between generations. With the most dormant genotypes, we examine three mechanisms by which smoke-derived chemical cues may stimulate germination (chemical scarification of the seed coat and nutritive- and signal-mediated stimulation of germination) and report that the response is consistent with the signal-mediated mechanism. The germination cue(s) found in smoke are produced by the burning of hay, hardwood branches, leaves, and, to a lesser degree, cellulose. Moreover, the cues are found in the common food condiment, liquid smoke, and we find no significant differences between brands. With a bioassay-driven fractionation of liquid smoke, we identified 71 compounds in active fractions by GC-MS and AA spectrometry. However, when these compounds were tested in pure form or in combinations that mimicked the composition of active fractions over a range of concentrations, they failed to stimulate germination to the same degree that smoke fractions did. Moreover, enzymatic oxidation of some of these compounds also failed to stimulate germination. In addition, we tested 43 additional compounds also reported from smoke, 85 compounds that were structurally similar to those reported from smoke and 34 compounds reported to influence germination in other species. Of the 233 compounds tested, 16 proved to inhibit germination at the concentrations tested, and none reproduced the activity of wood smoke. By thermally desorbing smoke produced by cellulose combustions that was trapped on Chromosorb 101, we demonstrate that the cue is desorbed between 125 and 150°C. We estimate that the germination cues are active at concentrations of less than 1 pg/seed and, due to their chromatographic behavior, infer that a number of different chemical structures are active. In separate experiments, we demonstrate that cues remain active for at least 53 days in soil under greenhouse conditions and that the application of aqucous extracts of smoke to soil containing seeds results in dramatic increases in germination of artificial seed banks. Hence, although the chemical nature of the germination cue remains elusive, the stability of the germination cues, their water-solubility, and their activity in low concentrations suggest that these cues could serve as powerful tools for the examination of dormant seed banks and the selective factors thought to be important in the evolution of postfire plant communities.     

A new method using feature extraction for identifying paddy rice species for quality seed selection

The purpose of this work was to explore a new feature extraction method for classifying paddy seeds using a feature extraction algorithm to achieve the area ratio, horizontal–slant and front–rear angles and find whether the proposed features have high discriminating power. Another objective was to find the smallest feature set that can ensure highly accurate recognition of seeds. A total of a 100 image features were extracted, and features having significant discriminating power were identified based on the analysis of variance (ANOVA). From the 100 features, 14 features were found to have high discriminating power and from these features, six were selected as the proposed features. Experimental results show that the proposed features and removal of redundant features enhanced the discriminating power of the feature set, and that the proposed features have an excellent discriminating property for seeds. The presented features resulted in the highest classification accuracy (98.8%) when compared to other methods.     

Inconel 740H合金750℃长期时效后的组织稳定性

对Inconel 740H合金管材在750℃进行500~3000h的无应力时效实验,采用热力学模拟,OM,FEG-SEM,显微硬度测定等方法研究了合金微观组织及显微硬度的变化趋势。结果表明:供货态(固溶处理)管材的合金成分及拉伸性能等均满足ASME要求,管材合格;长期时效后合金的主要析出相为γ′及M23C6,无η,σ等有害相析出。随着时效时间的延长,γ′粒子的粗化速率较快,其规律符合LSW熟化理论,M23C6相尺寸变化不明显;合金的显微硬度呈现先上升后下降的变化趋势,但整体波动较小。长期时效后合金组织及显微硬度的变化表明Inconel 740H在750℃/3000h条件下的组织稳定性较好,可用于进一步进行持久等长时力学性能的检验。     

Numerical inversions of a source term in the FADE with a Dirichlet boundary condition using final observations

This paper deals with an inverse problem of determining a source term in the one-dimensional fractional advection-dispersion equation (FADE) with a Dirichlet boundary condition on a finite domain, using final observations. On the basis of the shifted Grünwald formula, a finite difference scheme for the forward problem of the FADE is given, by means of which the source magnitude depending upon the space variable is reconstructed numerically by applying an optimal perturbation regularization algorithm. Numerical inversions with noisy data are carried out for the unknowns taking three functional forms: polynomials, trigonometric functions and index functions. The reconstruction results show that the inversion algorithm is efficient for the inverse problem of determining source terms in a FADE, and the algorithm is also stable for additional data having random noises.     

犹豫模糊语言的可能度排序方法

研究犹豫模糊语言集可能度排序方法. 在给出犹豫模糊语言集排序可能度公理的基础上, 给出3 类犹豫模糊语言集可能度排序公式: 第1 类基于RL 的5 个等价犹豫模糊语言可能度排序公式; 第2 类基于WNS的5 个等价犹豫模糊语言可能度排序公式; 第3 类基于概率可信度的犹豫模糊语言可能度比较公式. 通过实例对3 类公式进行对比分析, 给出方法选择的建议, 第3 类方法可以区别差别较小的犹豫模糊语言数, 第1 类方法适于大规模计算中的应用.