A mobile knowledge carrier with personalized knowledge provision

In the e-commerce era, the organization knowledge within a centralized knowledge management server can be easily accessed over the Internet by the client PCs at distinct locations. Currently, the personal digital assistant (PDA) has been widely used as the carrier for personal memos and daily records for its high mobility. Taking advantage of the personal information, the user requirements for knowledge can be determined. This research presents an intelligent KM scheme by integrating the PDA information (including notes, schedules and address book) mining model and mobile knowledge management mechanism. Based on the user profile mining technique, the PDA-ready knowledge that fits user requirements can be imported from the knowledge server to the client PDA. Demonstration cases are also provided to illustrate the applications of the proposed model in the content services and healthcare industry. By application of the mobile KM technique, the organization knowledge can be seamlessly provided to the PDA user via the data synchronization process. The attempt of this paper is to present an applicable and intelligent mobile knowledge carrier for realization of the mobile office.     

OSAF-tree--可迭代的移动序列模式挖掘及增量更新方法

移动通信技术和无限定位技术的发展积累了海量的、动态增长的时空数据．利用数据挖掘技术从移动用户的时空行为轨迹当中挖掘用户移动序列模式,在移动通信、交通管理、基于位置服务等领域有着广泛的应用前景．由于移动环境网络资源珍贵、数据量大的特点,传统的序列模式挖掘方法在效率上很难满足需求．OSAF-tree算法基于投影的概念,只需要对数据库进行一遍扫描,就可以很好地处理移动序列模式的挖掘及其增量更新和迭代挖掘问题,这是一个非常高效的算法．与已有的方法相比,OSAF-tree算法在性能和I/O代价等方面都具有明显的优势．     

Mining multilevel and location-aware service patterns in mobile web environments

In this correspondence, we address the issue of efficiently mining multilevel and location-aware associated service patterns in a mobile web environment. In terms of multilevel concept, we consider the complex problem that locations and services are of hierarchical structures. We propose a new data mining method named two-dimensional multilevel (2-DML) association rules mining, which can efficiently discover the associated service request patterns by taking into account the multilevel properties of locations and services. The discovered patterns can be effectively utilized in real applications like location-based and personalized services. To the best of our knowledge, this is the first work addressing this research issue. Some variations of the 2-DML method with different properties in terms of execution efficiency and memory efficiency were also developed. Through empirical evaluation, the proposed methods are shown to deliver good performance in terms of efficiency and scalability under various system conditions.     

基于RBAC的移动代理安全策略

移动代理是一种新兴的分布式计算模式,具有广泛的应用前景,安全问题是移动代理系统能否成功应用的关键。在分析移动代理系统存在的主要安全需求及基于角色访问控制特性的基础上,利用扩展的X．509公钥证书,提出了基于RBAc的移动代理安全访问策略,通过基于角色的授权实现了对代理服务器资源的访问控制,利用公钥认证协议实现了移动代理与代理服务器之间的安全认证,同时采用数据加密实现了信息的安全传输。     

Developing data allocation schemes by incremental mining of user moving patterns in a mobile computing system

In this paper, we present a new data mining algorithm which involves incremental mining for user moving patterns in a mobile computing environment and exploit the mining results to develop data allocation schemes so as to improve the overall performance of a mobile system. First, we propose an algorithm to capture the frequent user moving patterns from a set of log data in a mobile environment. The algorithm proposed is enhanced with the incremental mining capability and is able to discover new moving patterns efficiently without compromising the quality of results obtained. Then, in light of mining results of user moving patterns and the properties of data objects, we develop data allocation schemes that can utilize the knowledge of user moving patterns for proper allocation of both personal and shared data. By employing the data allocation schemes, the occurrences of costly remote accesses can be minimized and the performance of a mobile computing system is thus improved. For personal data allocation, two schemes are devised: one utilizes the set level of moving patterns and the other utilizes their path level. Schemes for shared data are also developed. Performance of these schemes is comparatively analyzed.     

一种预测群体用户访问行为的算法

在电子商务发展中,商家需要理解用户访问网站的行为,为用户提供个性化服务,从而吸引用户购买商品。挖掘用户访问网站的行为是商家一个急需解决的问题,通过对Web日志进行挖掘是解决该问题的重要研究方法。提出了网页兴趣信息素的新概念,它是由页面相对浏览时间和点击率构建而成,利用兴趣信息素设计了基于蚁群算法的群体用户访问路径挖掘算法,根据挖掘结果预测用户访问行为。实验结果表明,兴趣信息索可以有效地预测用户的兴趣变化,能准确地反映用户访问模式,提高了预测群体用户访问行为的准确率。     

分布式环境下保持隐私的聚类挖掘算法

隐私保护是数据挖掘中一个重要的研究方向。针对如何在不共享精确数据的条件下,应用k-平均聚类算法从数据中发现有意义知识的问题,提出了一种基于安全多方计算的算法。算法利用半可信第三方参与下的安全求平均值协议,实现了在分布式数据中进行k-平均聚类挖掘时隐私保护的要求。实验表明算法能很好的隐藏数据,保护隐私信息,且对聚类的结果没有影响。     

一种基于智能家居的用户行为预测方法

随着移动通信技术、物联网技术和传感器技术等的快速发展,智能家居行业发展迅速。由于人们生活水平的提高,对智能家居可以提供的智能服务需求正在增加。然而,现有的智能家居系统只能根据预设的控制方法和规则简单地重复运行,并且根据用户的日常生活习惯,不能随时提供满足其个性化需求的服务。试图为智能家居提供个性化服务,使智能家居的服务能够更加灵活、智能和人性化,报告了智能家居和关联规则挖掘的研究现状,对提高Apriori算法的效率进行了研究,设计了原型系统中的数据采集和预处理,网关以及行为识别和预测3个功能模块的总体实现方案。实验结果表明,采用关联规则数据挖掘的方法可以预测智能家居环境下用户未来的行为,同时基于散列技术的Apriori算法提高了智能家居下用户行为预测过程中的效率。     

Energy consumption of data mining algorithms on mobile phones: Evaluation and prediction

The pervasive availability of increasingly powerful mobile computing devices like PDAs, smartphones and wearable sensors, is widening their use in complex applications such as collaborative analysis, information sharing, and data mining in a mobile context. Energy characterization plays a critical role in determining the requirements of data-intensive applications that can be efficiently executed over mobile devices. This paper presents an experimental study of the energy consumption behavior of representative data mining algorithms running on mobile devices. Our study reveals that, although data mining algorithms are compute- and memory-intensive, by appropriate tuning of a few parameters associated to data (e.g., data set size, number of attributes, size of produced results) those algorithms can be efficiently executed on mobile devices by saving energy and, thus, prolonging devices lifetime. Based on the outcome of this study we also proposed a machine learning approach to predict energy consumption of mobile data-intensive algorithms. Results show that a considerable accuracy is achieved when the predictor is trained with specific-algorithm features.     

A scalable low-latency cache invalidation strategy for mobile environments

Caching frequently accessed data items on the client side is an effective technique for improving performance in a mobile environment. Classical cache invalidation strategies are not suitable for mobile environments due to frequent disconnections and mobility of the clients. One attractive cache invalidation technique is based on invalidation reports (IRs). However, the IR-based cache invalidation solution has two major drawbacks, which have not been addressed in previous research. First, there is a long query latency associated with this solution since a client cannot answer the query until the next IR interval. Second, when the server updates a hot data item, all clients have to query the server and get the data from the server separately, which wastes a large amount of bandwidth. In this paper, we propose an IR-based cache invalidation algorithm, which can significantly reduce the query latency and efficiently utilize the broadcast bandwidth. Detailed analytical analysis and simulation experiments are carried out to evaluate the proposed methodology. Compared to previous IR-based schemes, our scheme can significantly improve the throughput and reduce the query latency, the number of uplink request, and the broadcast bandwidth requirements.     

Efficient mining and prediction of user behavior patterns in mobile web systems

The development of wireless and web technologies has allowed the mobile users to request various kinds of services by mobile devices at anytime and anywhere. Helping the users obtain needed information effectively is an important issue in the mobile web systems. Discovery of user behavior can highly benefit the enhancements on system performance and quality of services. Obviously, the mobile user's behavior patterns, in which the location and the service are inherently coexistent, become more complex than those of the traditional web systems. In this paper, we propose a novel data mining method, namely SMAP-Mine that can efficiently discover mobile users' sequential movement patterns associated with requested services. Moreover, the corresponding prediction strategies are also proposed. Through empirical evaluation under various simulation conditions, SMAP-Mine is shown to deliver excellent performance in terms of accuracy, execution efficiency and scalability. Meanwhile, the proposed prediction strategies are also verified to be effective in measurements of precision, hit ratio and applicability.     

Secure Electronic Payments Based on Mobile Agents

The SET protocol for secure electronic payments, in particular its purchasing phase, is intended for users connected to the Internet during the entire transaction. This requirement cannot be easily met in high communication costs and/or low bandwidth settings, typically found in mobile computing environments.In this paper we describe SET/A, a system that works according to the SET rules for purchasing operations without forcing the user to be connected during the entire transaction. This is achieved by sending an agent to the merchant's server carrying all the data necessary to order and pay the goods (products, services or information). The paper shows that this can be achieved safely and efficiently, providing an alternative way for Internet payments using the SET protocol. We give our first impressions on SET/A usage by describing a prototype implementation based on a mobile agent system called AgentSpace, as well as a detailed example of what we consider a realistic application of the system.     

A Data Cube Model for Prediction-Based Web Prefetching

Reducing the web latency is one of the primary concerns of Internet research. Web caching and web prefetching are two effective techniques to latency reduction. A primary method for intelligent prefetching is to rank potential web documents based on prediction models that are trained on the past web server and proxy server log data, and to prefetch the highly ranked objects. For this method to work well, the prediction model must be updated constantly, and different queries must be answered efficiently. In this paper we present a data-cube model to represent Web access sessions for data mining for supporting the prediction model construction. The cube model organizes session data into three dimensions. With the data cube in place, we apply efficient data mining algorithms for clustering and correlation analysis. As a result of the analysis, the web page clusters can then be used to guide the prefetching system. In this paper, we propose an integrated web-caching and web-prefetching model, where the issues of prefetching aggressiveness, replacement policy and increased network traffic are addressed together in an integrated framework. The core of our integrated solution is a prediction model based on statistical correlation between web objects. This model can be frequently updated by querying the data cube of web server logs. This integrated data cube and prediction based prefetching framework represents a first such effort in our knowledge.     

基于模糊聚类的Web日志挖掘的应用研究

在Web数据挖掘研究领域中，Web日志挖掘是Web数据研究领域中一个最重要的应用方面。本文对Web日志挖掘作了系统的研究。包括对服务器上日志结构的分析和对数据预处理过程的描述。文中着重讨论了用户模糊聚类的算法，并用实例证明了模糊聚类在web用户聚类应用中的可行性。在此基础上还提出了一个Web站点的个性化服务模型，通过对Web服务器中日志的挖掘，发现具有相似访问兴趣的用户群，进而为用户作个性化的推荐。     

基于模糊聚类的Web日志挖掘的应用研究

在Web数据挖掘研究领域中,Web日志挖掘是Web数据研究领域中一个最重要的应用方面。本文对Web日志挖掘作了系统的研究,包括对服务器上日志结构的分析和对数据预处理过程的描述。文中着重讨论了用户模糊聚类的算法,并用实例证明了模糊聚类在Web用户聚类应用中的可行性。在此基础上还提出了一个Web站点的个性化服务模型,通过对Web服务器中日志的挖掘,发现具有相似访问兴趣的用户群,进而为用户作个性化的推荐。     

A decentralized approach for mining event correlations in distributed system monitoring

Nowadays, there is an increasing demand to monitor, analyze, and control large scale distributed systems. Events detected during monitoring are temporally correlated, which is helpful to resource allocation, job scheduling, and failure prediction. To discover the correlations among detected events, many existing approaches concentrate detected events into an event database and perform data mining on it. We argue that these approaches are not scalable to large scale distributed systems as monitored events grow so fast that event correlation discovering can hardly be done with the power of a single computer. In this paper, we present a decentralized approach to efficiently detect events, filter irrelative events, and discover their temporal correlations. We propose a MapReduce-based algorithm, MapReduce-Apriori, to data mining event association rules, which utilizes the computational resource of multiple dedicated nodes of the system. Experimental results show that our decentralized event correlation mining algorithm achieves nearly ideal speedup compared to centralized mining approaches.     

基于SOAP消息扩展的服务访问权限控制

简单对象访问协议(SOAP)是面向服务架构(SOA)中实现远程服务调用的协议,但是它没有定义标准的服务访问控制规范。本文提出了一种符合SOAP消息中XML语法的服务访问控制结构,并以此结构为基础,构建了一个动态细粒度基于角色的服务访问控制模型DFG-RBAC(Dynamic Fine Grain Role-based Access Control)。同时,利用目录服务器设计了服务访问权限数据存储与查询机制,实现了精确、高效的服务访问控制。     

A cache invalidation scheme for continuous partial match queries in mobile computing environments

The continuous partial match query is a partial match query whose result remains consistently in the client’s memory. Conventional cache invalidation methods for mobile clients are record ID-based. However, since the partial match query uses content-based retrieval, the conventional ID-based approaches cannot efficiently manage the cache consistency of mobile clients. In this paper, we propose a predicate-based cache invalidation scheme for continuous partial match queries in mobile computing environments. We represent the cache state of a mobile client as a predicate, and also construct a cache invalidation report (CIR), which the server broadcasts to clients for cache management, with predicates. In order to reduce the amount of information that is needed for cache management, we propose a set of methods for CIR construction (in the server) and identification of invalidated data (in the client). Through experiments, we show that the predicate-based approach is very effective for the cache management of mobile clients.     

Efficient data mining for calling path patterns in GSM networks

In this paper, we explore a new data mining capability that involves mining calling path patterns in global system for mobile communication (GSM) networks. Our proposed method consists of two phases. First, we devise a data structure to convert the original calling paths in the log file into a frequent calling path graph. Second, we design an algorithm to mine the calling path patterns from the frequent calling path graph obtained. By using the frequent calling path graph to mine the calling path patterns, our proposed algorithm does not generate unnecessary candidate patterns and requires less database scans. If the corresponding calling path graph of the GSM network can be fitted in the main memory, our proposed algorithm scans the database only once. Otherwise, the cellular structure of the GSM network is divided into several partitions so that the corresponding calling path sub-graph of each partition can be fitted in the main memory. The number of database scans for this case is equal to the number of partitioned sub-graphs. Therefore, our proposed algorithm is more efficient than the PrefixSpan and a priori-like approaches. The experimental results show that our proposed algorithm outperforms the a priori-like and PrefixSpan approaches by several orders of magnitude.     

基于操作日志的完井数据同步模型

同步技术是提高移动数据库系统性能的一项关键技术。依托完井移动平台,结合完井业务数据,提出一种基于操作日志的移动数据同步处理模型,重点分析了该模型中的日志序列的生成以及冲突的消解,并给出了具体的实现算法。该模型允许移动终端在断接状态下对本地副本数据进行操作,并通过移动事务日志记录用户行为,当重新连接时,根据服务器返回的日志序列进行同步处理,使系统最终收敛于一致性状态。同时还引入了日志合并、时间戳等方法,有效减少了移动终端的资源消耗,提高了同步效率。实验表明该算法能快速高效地完成客户端与服务器之间的数据更新与交互。