有序二叉决策图在防火墙规则库设计中的应用

在防火墙规则库的设计中利用有序二叉决策图（ordered binary decision diagram，OBDD）来表示防火墙的访问控制规则集，改变了传统的顺序存储规则的规则库设计方法，以增加预处理时间为代价，有效地提高了规则的匹配速度，从而提高了防火墙的性能及其安全性．     

BBO，LBO，KDP晶体光参量啁啾脉冲放大特性的比较研究

 对BBO，LBO，KDP晶体I类非共线匹配下的光参量啁啾脉冲放大的相位匹配、参量范围、增益特性等进行了理论分析，重点对BBO和LBO的光参量啁啾脉冲放大特性进行了比较。结果表明对于以光参量啁啾脉冲放大系统代替800nm中心波长的Ti:sappire再生放大系统，用BBO晶体可获得更宽的增益带宽，而对1 053nm中心波长的种子光用LBO晶体更好。     

31P CP/MAS NMR of polycrystalline and immobilized phosphines and catalysts with fast sample spinning

Cross‐polarization (CP) at fast magic angle spinning (MAS) frequencies leads to a splitting of the Hartmann–Hahn (HH) matching profile into a centerband and additional bands of higher orders. The matching profiles differ with the substance categories. Therefore, signal intensity is usually lost, when e.g. the routine standard NH₄H₂PO₄ is used for optimizing the ¹H–³¹P HH match prior to measuring phosphines and their metal complexes in polycrystalline or immobilized form. Here, a variety of model compounds, such as Ph₂PCH₂CH₂PPh₂ and (CO)₂Ni(PPh₃)₂, which can be used as ³¹P CP standards for analogous substances or materials are presented. Investigating the influences of MAS frequency, contact time, ¹H pulse power and sample volume on the matching profiles of the model compounds leads to general trends. Thereby, a new strategy for measuring difficult samples with CP at high MAS rates has been developed: their optimum CP parameters are derived from the most intense maxima in the HH matching profiles of the corresponding model compounds. This new strategy is compared with variations of a conventional ramp sequence. Although the latter generally provide smaller signal half‐widths, the new strategy leads to higher signal intensities. The new method was successfully applied to polycrystalline and immobilized phosphines and catalysts. Copyright © 2003 John Wiley & Sons, Ltd.     

Calculating distances for dissimilar strings: The shortest path formulation revisited

Fast detection of string differences is a prerequisite for string clustering problems. An example of such a problem is the identification of duplicate information in the data cleansing stage of the data mining process. The relevant algorithms allow the application of large-scale clustering techniques in order to create clusters of similar strings. The vast majority of comparisons, in such cases, is between very dissimilar strings, therefore methods that perform better at detecting large differences are preferable. This paper presents approaches which comply with this requirement, based on reformulation of the underlying shortest path problem. It is believed that such methods can lead to a family of new algorithms. An upper bound algorithm is presented, as an example, which produces promising results.     

匹配最大根小于等于2的图的匹配等价

给出了十六个匹配等价桥,证明了两个匹配最大根小于等于2的图匹配等价当且仅当它们之间可以由这十六个匹配等价桥进行等价转换,完整地刻画了这些图的补图的匹配等价图类,找到了这些图和它们的补图中的所有匹配唯一图．     

转移开、闭集值映象和H－KKM定理的推广及应用

本文中，我们引入转移开、闭集值映象的概念，推广了Ｈ－空间中的ＫＫＭ定理￣［４］．然后用所得的结果证明了几个重合定理、匹配定理和向量值极大极小不等式。这些结论推广了近期文献［１，２，４，５，６，７］中的相应结果。     

Construction for bicritical graphs and k-extendable bipartite graphs

A graph G is said to be bicritical if G-u-v has a perfect matching for every choice of a pair of points u and v. Bicritical graphs play a central role in decomposition theory of elementary graphs with respect to perfect matchings. As Plummer pointed out many times, the structure of bicritical graphs is far from completely understood. This paper presents a concise structure characterization on bicritical graphs in terms of factor-critical graphs and transversals of hypergraphs. A connected graph G with at least 2k+2 points is said to be k-extendable if it contains a matching of k lines and every such matching is contained in a perfect matching. A structure characterization for k-extendable bipartite graphs is given in a recursive way. Furthermore, this paper presents an O(mn) algorithm for determining the extendability of a bipartite graph G, the maximum integer k such that G is k-extendable, where n is the number of points and m is the number of lines in G.     

The study of phase matching of nonlinear waves in microdroplets

In this paper, the internal field distribution of higher order MDRs of water droplets is calculated and the result shows that the higher order MDRs should dominate the nonlinear couple process. Furthermore, the phase matching required for four-wave mixing (FWM) process in the droplet is interpreted as the concept of angular momentum conservation. The slight mismatch in angular momentum leads to significant improvement of phase matching than that in optical cell.     

Fast detection of common sequence structure patterns in RNAs

We developed a dynamic programming approach for computing common exact sequential and structural patterns between two RNAs, given their sequences and their secondary structures. An RNA consists of a sequence of nucleotides and a secondary structure defined via bonds linking together complementary nucleotides. It is known that secondary structures are more preserved than sequences in the evolution of RNAs.We are able to compute all patterns between two RNAs in time O(nm) and space O(nm), where n and m are the lengths of the RNAs. Our method is useful for describing and detecting local motifs. It is especially suitable for finding similar regions of large RNAs that do not share global similarities. An implementation is available in C++ and can be obtained by contacting one of the authors.     

3-D imaging and modeling – Part I: acquisition and registration

The key modules in a typical reverse engineering system consist of the acquisition, registration, and the integration of range images of three-dimensional objects with complex geometry. We first present a self-made optical digitizer that is employed for quickly acquiring range data from multiple views, then introduce a visualized registration procedure that can provide a reliable estimate for the fine registration of multiple range images in a unified coordinate system. Experiment results are given to show the effectiveness of this approach in 3-D imaging and multiple range image registration for the applications of reverse engineering.