<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Vassiliki A. Koutsonikola</style></author><author><style face="normal" font="default" size="100%">Petridou, Sophia G.</style></author><author><style face="normal" font="default" size="100%">Athena Vakali</style></author><author><style face="normal" font="default" size="100%">Papadimitriou, Georgios I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">A new approach to web users clustering and validation: a divergence-based scheme</style></title><secondary-title><style face="normal" font="default" size="100%">IJWIS</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cluster analysis</style></keyword><keyword><style  face="normal" font="default" size="100%">Internet Data mining</style></keyword><keyword><style  face="normal" font="default" size="100%">User studies</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year></dates><number><style face="normal" font="default" size="100%">3</style></number><volume><style face="normal" font="default" size="100%">5</style></volume><pages><style face="normal" font="default" size="100%">348-371</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Purpose â€“ Web usersâ€™ clustering is an important mining task since it contributes in identifying usagepatterns, a beneficial task for a wide range of applications that rely on the web. The purpose of thispaper is to examine the usage of Kullback-Leibler (KL) divergence, an information theoretic distance,as an alternative option for measuring distances in web users clustering.Design/methodology/approach â€“ KL-divergence is compared with other well-known distancemeasures and clustering results are evaluated using a criterion function, validity indices, andgraphical representations. Furthermore, the impact of noise (i.e. occasional or mistaken page visits) isevaluated, since it is imperative to assess whether a clustering process exhibits tolerance in noisyenvironments such as the web.Findings â€“ The proposed KL clustering approach is of similar performance when compared withother distance measures under both synthetic and real data workloads. Moreover, imposing extranoise on real data, the approach shows minimum deterioration among most of the other conventionaldistance measures.Practical implications â€“ The experimental results show that a probabilistic measure such asKL-divergence has proven to be quite efficient in noisy environments and thus constitute a goodalternative, the web users clustering problem.Originality/value â€“ This work is inspired by the usage of divergence in clustering of biological dataand it is introduced by the authors in the area of web clustering. According to the experimental resultspresented in this paper, KL-divergence can be considered as a good alternative for measuringdistances in noisy environments such as the web.&lt;/p&gt;
</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Petridou, Sophia G.</style></author><author><style face="normal" font="default" size="100%">Vassiliki A. Koutsonikola</style></author><author><style face="normal" font="default" size="100%">Athena Vakali</style></author><author><style face="normal" font="default" size="100%">Papadimitriou, Georgios I.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Time-Aware Web Users’ Clustering</style></title><secondary-title><style face="normal" font="default" size="100%">IEEE Trans. Knowl. Data Eng.</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2008</style></year></dates><number><style face="normal" font="default" size="100%">5</style></number><volume><style face="normal" font="default" size="100%">20</style></volume><pages><style face="normal" font="default" size="100%">653-667</style></pages><language><style face="normal" font="default" size="100%">eng</style></language></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>47</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Petridou, Sophia G.</style></author><author><style face="normal" font="default" size="100%">Vassiliki A. Koutsonikola</style></author><author><style face="normal" font="default" size="100%">Athena Vakali</style></author><author><style face="normal" font="default" size="100%">Papadimitriou, Georgios I.</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">Gavrilova, Marina L.</style></author><author><style face="normal" font="default" size="100%">Gervasi, Osvaldo</style></author><author><style face="normal" font="default" size="100%">Kumar, Vipin</style></author><author><style face="normal" font="default" size="100%">Tan, Chih Jeng Kenneth</style></author><author><style face="normal" font="default" size="100%">Taniar, David</style></author><author><style face="normal" font="default" size="100%">LaganĂ , Antonio</style></author><author><style face="normal" font="default" size="100%">Mun, Youngsong</style></author><author><style face="normal" font="default" size="100%">Choo, Hyunseung</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">A Divergence-Oriented Approach for Web Users Clustering</style></title><secondary-title><style face="normal" font="default" size="100%">ICCSA (2)</style></secondary-title><tertiary-title><style face="normal" font="default" size="100%">Lecture Notes in Computer Science</style></tertiary-title></titles><dates><year><style  face="normal" font="default" size="100%">2006</style></year></dates><publisher><style face="normal" font="default" size="100%">Springer</style></publisher><volume><style face="normal" font="default" size="100%">3981</style></volume><pages><style face="normal" font="default" size="100%">1229-1238</style></pages><isbn><style face="normal" font="default" size="100%">3-540-34072-6</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Clustering web users based on their access patterns is a quite significanttask in Web Usage Mining. Further to clustering it is important to evaluatethe resulted clusters in order to choose the best clustering for a particular framework.This paper examines the usage of Kullback-Leibler divergence, aninformation theoretic distance, in conjuction with the k-means clusteringalgorithm. It compares KL-divergence with other well known distance measures(Euclidean, Standardized Euclidean and Manhattan) and evaluates clusteringresults using both objective functionâ€™s value and Davies-Bouldin index.Since it is imperative to assess whether the results of a clustering process aresusceptible to noise, especially in noisy environments such as Web environment,our approach takes the impact of noise into account. The clusters obtainedwith KL approach seem to be superior to those obtained with the otherdistance measures in case our data have been corrupted by noise.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Papadimitriou, Georgios I.</style></author><author><style face="normal" font="default" size="100%">Athena Vakali</style></author><author><style face="normal" font="default" size="100%">Pomportsis, Andreas S.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">A learning-automata-based controller for client/server systems</style></title><secondary-title><style face="normal" font="default" size="100%">Neurocomputing</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">client/server systems</style></keyword><keyword><style  face="normal" font="default" size="100%">learning automata</style></keyword><keyword><style  face="normal" font="default" size="100%">polling policies</style></keyword><keyword><style  face="normal" font="default" size="100%">throughput improvement</style></keyword><keyword><style  face="normal" font="default" size="100%">time-delay</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2004</style></year></dates><volume><style face="normal" font="default" size="100%">61</style></volume><pages><style face="normal" font="default" size="100%">381-394</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Polling policies have been introduced to simplifythe accessing process in client/server systems by acentralized control access scheme. This paper considers aclient/server model which employs a polling policy as itsaccess strategy. We propose a learning-automata-based approachfor polling in order to improve the throughput-delayperformance of the system. Each client has an associatedqueue and the server performs selective polling such thatthe next client to be served is identified by a learning automaton.The learning automaton updates each clientâ€™schoice probability according to the feedback information.Under the considered approach, a clientâ€™s choice probabilityasymptotically tends to be proportional to the probabilitythat this client is ready. Simulation results have shown thatthe proposed polling policy is beneficial in comparison tothe conventional round-robin polling when operating underbursty traffic conditions. The benefits are significant for thedelay reduction in the considered client/server system.&lt;/p&gt;
</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Athena Vakali</style></author><author><style face="normal" font="default" size="100%">Papadimitriou, Georgios I.</style></author><author><style face="normal" font="default" size="100%">Pomportsis, Andreas S.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">A feedback-based model for I/O servicing</style></title><secondary-title><style face="normal" font="default" size="100%">Computers &amp; Electrical Engineering</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><number><style face="normal" font="default" size="100%">4</style></number><volume><style face="normal" font="default" size="100%">27</style></volume><pages><style face="normal" font="default" size="100%">309-322</style></pages><language><style face="normal" font="default" size="100%">eng</style></language></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>47</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Athena Vakali</style></author><author><style face="normal" font="default" size="100%">Papadimitriou, Georgios I.</style></author><author><style face="normal" font="default" size="100%">Pomportsis, Andreas S.</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">Bubak, Marian</style></author><author><style face="normal" font="default" size="100%">Afsarmanesh, Hamideh</style></author><author><style face="normal" font="default" size="100%">Williams, Roy</style></author><author><style face="normal" font="default" size="100%">Hertzberger, Louis O.</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">A New Approach to the Design of High Performance Multiple Disk Subsystems: Dynamic Load Balancing Schemes</style></title><secondary-title><style face="normal" font="default" size="100%">HPCN Europe</style></secondary-title><tertiary-title><style face="normal" font="default" size="100%">Lecture Notes in Computer Science</style></tertiary-title></titles><dates><year><style  face="normal" font="default" size="100%">2000</style></year></dates><publisher><style face="normal" font="default" size="100%">Springer</style></publisher><volume><style face="normal" font="default" size="100%">1823</style></volume><pages><style face="normal" font="default" size="100%">610-613</style></pages><isbn><style face="normal" font="default" size="100%">3-540-67553-1</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The performance of storage subsystems has not followed therapid improvements in processors technology, despite the increased capacityand density in storage medium. Here, we introduce a new modelbased on the idea of enhancing the I/O subsystem controller capabilitiesby dynamic load balancing on a storage subsystem of multiple disk drives.The request servicing is modified such that each request is directed to themost appropriate disk drive towards servicing performance improvement.The redirection is performed by a proposed algorithm which considersthe disk drive queues and the disk drives â€śpopularityâ€ť. The proposed requestservicing has been simulated and the load balancing approach hasbeen shown quite effective as compared to conventional request servicing.</style></abstract></record></records></xml>