带参数的一阶脉冲微分方程边值问题

利用上下解和单调迭代法。讨论了带参数的一阶脉冲微分方程。获得了单边Lipschitz条件下这类方程边值问题的解的存在性。     

A new distributed approximation algorithm for constructing minimum connected dominating set in wireless ad hoc networks

In recent years, constructing a virtual backbone by nodes in a connected dominating set (CDS) has been proposed to improve the performance of ad hoc wireless networks. In general, a dominating set satisfies that every vertex in the graph is either in the set or adjacent to a vertex in the set. A CDS is a dominating set that also induces a connected sub‐graph. However, finding the minimum connected dominating set (MCDS) is a well‐known NP‐hard problem in graph theory. Approximation algorithms for MCDS have been proposed in the literature. Most of these algorithms suffer from a poor approximation ratio, and from high time complexity and message complexity. In this paper, we present a new distributed approximation algorithm that constructs a MCDS for wireless ad hoc networks based on a maximal independent set (MIS). Our algorithm, which is fully localized, has a constant approximation ratio, and O(n) time and O(n) message complexity. In this algorithm, each node only requires the knowledge of its one‐hop neighbours and there is only one shortest path connecting two dominators that are at most three hops away. We not only give theoretical performance analysis for our algorithm, but also conduct extensive simulation to compare our algorithm with other algorithms in the literature. Simulation results and theoretical analysis show that our algorithm has better efficiency and performance than others. Copyright © 2005 John Wiley & Sons, Ltd.     

F150交换机告警关联规则的研究

为了提高电信网络运营效率，降低维护成本，电信运营企业在网络告警管理系统中需要引入数据挖掘技术。本文主要研究利用数据挖掘技术来进行故障的管理，即对告警进行关联性分析，详细分析了告警序列数据的关联规则挖掘算法，并在南昌本地网F150交换机的告警数据库中予以实现，同时对实际挖掘结果进行分析和整理，推导出一些实用的关联规则。     

横置螺旋弹簧隔振器在冲击激励下的最大应力研究

本文研究横置螺旋弹簧隔振器简化模型在主工作方向上的有预载荷的不同初值，或幅值的上架或基础冲击激励下的最大应力及发生位置，并对隔振器弹簧进行了强度分析。     

A new algorithm for fast mining frequent itemsets using N-lists

Mining frequent itemsets has emerged as a fundamental problem in data mining and plays an essential role in many important data mining tasks.In this paper,we propose a novel vertical data representation called N-list,which originates from an FP-tree-like coding prefix tree called PPC-tree that stores crucial information about frequent itemsets.Based on the N-list data structure,we develop an efficient mining algorithm,PrePost,for mining all frequent itemsets.Efficiency of PrePost is achieved by the following three reasons.First,N-list is compact since transactions with common prefixes share the same nodes of the PPC-tree.Second,the counting of itemsets’ supports is transformed into the intersection of N-lists and the complexity of intersecting two N-lists can be reduced to O(m + n) by an efficient strategy,where m and n are the cardinalities of the two N-lists respectively.Third,PrePost can directly find frequent itemsets without generating candidate itemsets in some cases by making use of the single path property of N-list.We have experimentally evaluated PrePost against four state-of-the-art algorithms for mining frequent itemsets on a variety of real and synthetic datasets.The experimental results show that the PrePost algorithm is the fastest in most cases.Even though the algorithm consumes more memory when the datasets are sparse,it is still the fastest one.     

Maximal contractions in Boolean algebras

In the present paper,the concepts of deductive element and maximal contraction are introduced in Boolean algebras,and corresponding theories of consistency and maximal contractions are studied.An algorithm principle is proposed to compute all maximal contractions for a consistent set with respect to its refutation in Boolean algebras.It is pointed out that the quotient algebra of the first-order language with respect to its provable equivalence relation constitutes a Boolean algebra,and hence the computation of R-contractions for closed formulas in first-order languages can be converted into the one in Boolean algebras proposed in this paper.Furthermore,the concept of basic element is introduced in Boolean algebras,which contributes to the definitions of clause and Horn clause transplanted from logic to a special type of Boolean algebras generated by basic elements.It is also pointed out that the computation of R-contractions for clauses in the classical propositional logic can be converted into the one in Boolean algebras generated by basic elements proposed in this paper.     

基于图论的最大频繁项集挖掘*

利用有向项集图来存储事务数据库中有关频繁项集的信息,提出了有向项集图的三叉链表式存储结构和基于有向项集图的最大频繁项集挖掘算法.它不仅实现了事务数据库的一次扫描,减少了I/O代价,而且可以同时解决好稀疏数据库和稠密数据库的最大频繁项集挖掘问题.     

基于二进制的关联规则挖掘算法*

将二进制引入关联规则求解中,充分利用二进制操作方便、运算速度快、节省空间的优势.在求解事务项集真子集和支持度时,对事务数据库中相同事务只求解一次,并给出了真子集的具体求解算法.本算法一次扫描数据库可以挖掘出所有频繁集,而且可以根据需求对最小支持度和最小置信度进行修改,修改后不需要再次扫描数据库即可求出频繁项集,大大提高了挖掘效率.     

欧盟撤销硫丹登记对我国茶叶出口影响的分析

欧盟在对硫丹进行风险评估的基础上,于2005年5月3日和6月2日,先后发布SPS和TBT通报,撤销硫丹作为植物保护产品登记。按照欧盟相关指令的要求,硫丹在茶叶中的MRLs由30mg/kg调整为0.01mg/kg。硫丹是目前我国茶叶生产中的农药推广品种,而且欧盟是我国重要的茶叶出口市场,欧盟的此项规定对我国茶叶出口有一定的影响,应当采取措施积极应对。