一种基于复数编码的遗传算法

第一次把复数编码的思想应用到遗传算法中去,用复数编码来表达双倍体,并具体规定了遗传操作.每一个复数对应于双倍体的一对等位基因.目标函数自变量的大小由其对应的复数的模决定,符号则由相应复数的幅角决定.与传统的实数编码的遗传算法相比,本算法大大地扩展了表达空间的维数,实验结果证明了本算法的有效性.     

基于信任值的云存储数据确定性删除方案

数据确定性删除是云存储安全的研究热点。目前云存储中分散式的数据确定性删除方案在密钥分量存储时没有考虑DHT((Distributed Hash Table)节点可信性,使得用户在授权时间内也存在无法访问自己敏感数据的问题。为此提出了一种基于信任值的云存储数据确定性删除方案,该方案的核心是对DHT节点进行可信度评价,密钥分量的存储选择可信度较高的节点。与已有的确定性删除方案相比,该方案仍然是利用DHT网络的动态特性实现密钥的定期删除,使得用户敏感数据能够在特定的一段时间之后自动销毁。不同的是,该方案在将密钥分量分发到DHT网络中时倾向于选择可信度高的节点进行交互,使得在密钥的过期时间戳之前从DHT网络中得到足够多的密钥分量来恢复出密钥的可能性大大提高,降低了用户在授权时间内无法访问自己敏感数据的概率。实验结果表明,该方案不仅可以有效地抑制恶意节点,还可以提高密钥分量提取成功率,从而增加用户在授权时间内访问自己敏感数据的成功率。     

统计机器翻译删词问题研究

该文对基于短语的统计机器翻译模型的删词问题进行研究与分析,使用人工评价的方式将删词错误分为3类。该文通过两种方法,即基于频次的方法和基于词性标注的方法,对源语言句子中关键词汇进行识别。通过对传统的短语对抽取算法中引入源语言对空关键词汇的约束来缓解删词错误问题。自动评价方法以及人工评价方法证明,该方法在汉英翻译任务以及英汉翻译任务中显著的缓解了删词错误问题,同时得到一个精简的短语翻译表。     

Insert and delete algorithms for maintaining dynamic Delaunay triangulations

We recall that optimal condensing of nearest neighbor data requires the construction of the Delaunay triangulation of the training set. We argue that, from the viewpoint of computational complexity, an iterative approach using a dynamic triangulation is most desirable. We describe two algorithms, Insert and Delete, which permit to maintain a dynamic Delaunay triangulation.     

深水多次波与噪音同时压制技术

海洋地震资料预处理,两大难题就是噪音和多次波。常规的近道多次波压制有预测反褶积和SRME,中远道多次波压制有速度滤波等方法。然而在深水崎岖海底资料中,对于侧面反射、绕射多次波等等,常规的多次波压制方法往往失效,原因在于常规的多次波压制方法的理论多假设地震波是以二维双曲线方式传播,实际上地下地震波传播路径复杂,常规去多次方法有局限。另外对于噪音的压制,技术人员往往是头痛医头脚痛医脚,对不同的噪音采用不同的模块进行压制,即增加了处理步骤,也增加了损伤有效波的风险。本文研究了一种利用剔除拟合法并结合LIFT思想进行深水多次波和噪音压制技术,一次处理流程可以同时压制多种噪音和多种多次波,取得了良好的效果。     

Maximum gap labelings of graphs

Given a graph, we define a base set to be a set of integers of size equal to the number of vertices in the graph. Given a graph and a base set, a labeling of the graph from the base set is an assignment of distinct integers from the base set to the vertices of the graph. The gap of an edge in a labeled graph is the absolute value of the difference between the labels of its endpoints. The gap of a labeled graph is the sum of the gaps of its edges.The maximum gap graph labeling problem takes as input a graph and a base set and maximizes the gap of the graph over all possible labelings from the base set. We show that this problem is NP-complete even when the base set is restricted to consecutive integers. We also show that this restricted case has polynomial time approximations that achieve a factor of 2/3 for trees, of 1/2 for bipartite graphs, and of 1/4 for general graphs, with a deterministic algorithm, while an expected factor of 1/3 for general graphs is achieved with a randomized algorithm. The case of general base sets is approximated within an expected factor of 1/16 for general graphs with a randomized polynomial time algorithm. We finally give a polynomial time algorithm that solves the maximum gap graph labeling problem for a graph that has bounded degree and bounded treewidth. The maximum graph labeling problem shows connections with the graceful tree conjecture.     

An imputation method for categorical variables with application to nonlinear principal component analysis

The problem of missing data in building multidimensional composite indicators is a delicate problem which is often underrated. An imputation method particularly suitable for categorical data is proposed. This method is discussed in detail in the framework of nonlinear principal component analysis and compared to other missing data treatments which are commonly used in this analysis. Its performance vs. these other methods is evaluated throughout a simulation procedure performed on both an artificial case, varying the experimental conditions, and a real case. The proposed procedure is implemented using R¹.     

基于欧拉函数秘密分享的RSA私钥的理性分布计算(英文)

随着分布式计算的发展,分布式计算环境中的安全性问题变得越来越突出。基于RSA算法的分布式认证和分布式数据加密等安全性机制也取得了长足的发展。不过,这些机制中大部分是基于传统密码协议中参与者类型的假设:半诚实或恶意的。本文从假设参与者是理性的这一视角出发,设计了基于RSA欧拉函数秘密分享的RSA私钥的分布式计算协议。协议中所有的参与者均是理性的,他们以自我利益为驱动。所有的参与者均采取遵守协议的执行这一策略形成了纳什均衡,并且该策略是不能严格劣势剔除的。     

Encoding and retrieval processes in velo-cardio-facial syndrome (VCFS).

Velo-cardio-facial syndrome (VCFS) is a neurogenetic disorder associated with very high risk for developing schizophrenia. More than half of affected individuals experience transient psychotic symptoms during childhood and a third may develop schizophrenia. Memory regulation deficits disturbing both the encoding and retrieval stages of memory represent core deficits in the cognitive profile associated with schizophrenia. In this study, the authors investigate memory regulation processes in 33 individuals with VCFS along with 33 age- and sex-matched control participants. By using a directed forgetting paradigm and a continuous recognition paradigm, the authors examined selective encoding and suppression of irrelevant contents during retrieval in VCFS. Group comparison analyses revealed comparable performances on selective encoding and recognition accuracy between the VCFS group and control group. However, individuals with VCFS were more likely to make false recognitions and showed deficits in the suppression of irrelevant contents. Results suggest that trait-like deficits of memory regulation in VCFS can be observed during the retrieval stage, while selective encoding remains efficient. Memory regulation processes during retrieval may constitute a trait deficit in the memory profile of individuals with VCFS and may contribute to the cognitive deficits underlying an increased risk for developing schizophrenia in this population. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Efficiency of Critical Slicing in Fault Localization

In software testing, developing effective debugging strategies is important to guarantee the reliability of software under testing. A heuristic technique is to cause failure and therefore expose faults. Based on this approach mutation testing has been found very useful technique in detecting faults. However, it suffers from two problems with successfully testing programs: (1) requires extensive computing resources and (2) puts heavy demand on human resources. Later, empirical observations suggest that critical slicing based on Statement Deletion (Sdl) mutation operator has been found the most effective technique in reducing effort and the required computing resources in locating the program faults. The second problem of mutation testing may be solved by automating the program testing with the help of software tools. Our study focuses on determining the effectiveness of the critical slicing technique with the help of the Mothra Mutation Testing System in detecting program faults. This paper presents the results showing the performance of Mothra Mutation Testing System through conducting critical slicing testing on a selected suite of programs. Zuhoor Abdullah Al-Khanjari is an assistant professor in the Computer Science Department at Sultan Qaboos University, Sultanate of Oman. She received her BSc in mathematics and computing from Sultan Qaboos University, MSc and PhD in Computer Science (Software Engineering) from the University of Liverpool, UK. Her research interests include software testing, database management, e-learning, human-computer interaction, programming languages, intelligent search engines, and web data mining and development. ~Currently, she is the coordinator of the software engineering research group in the Department of Computer Science, College of Science, Sultan Qaboos University. She is also coordinating a program to develop e-learning based undergraduate teaching in the Department of Computer Science. Currently she is holding the position of assistant dean for postgraduate studies and research in the College of Science, Sultan Qaboos University, Sultanate of Oman. Martin Woodward is a Senior Fellow in the Computer Science Department at the University of Liverpool in the UK. After obtaining BSc and Ph.D. degrees in mathematics from the University of Nottingham, he was employed by the University of Oxford as a Research Assistant on secondment to the UK Atomic Energy Authority at the Culham Laboratory. He has been at the University of Liverpool for many years and initially worked on the so-called ‘Testbed’ project, helping to develop automated tools for software testing which are now marketed successfully by a commercial organisation. His research interests include software testing techniques, the relationship between formal methods and testing, and software visualisation. He has served as Editor of the journal ‘Software Testing, Verification and Reliability’ for the past thirteen years. Haider Ramadhan is an associate professor in the Computer Science Department at Sultan Qaboos University. He received his BS and MS in Computer Science from University of North Carolina, and the PhD in Computer Science and AI from Sussex University. His research interests include visualization of software, systems, and process, system engineering, human-computer interaction, intelligent search engines, and Web data mining and development. Currently, he is the chairman of the Computer Science Department, College of Science, Sultan Qaboos University, Sultanate of Oman. Swamy Kutti (N. S. Kutti) is an associate professor in the Computer Science Department at Sultan Qaboos University. He received his B.E. in Electronics Engineering from the University of Madras, M.E. in Communication Engineering from Indian Institute of Science (Bangalore), and the MSc in Computer Science from Monash University (Australia) and PhD in Computer Science from Deakin University (Australia). His research interests include Real-Time Programming, Programming Languages, Program Testing and Verification, eLearning, and Distributed Operating Systems.