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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2007.11.020 Byline: Yung-Cheng Tu (a), Meng Chang Chen (b), Yeali S. Sun (c), Wei-Kuan Shih (a) Keywords: Bandwidth allocation; End-to-end delay; Bulk scheduling; Quality of service Abstract: Providing end-to-end delay guarantees for delay sensitive applications is an important packet scheduling issue with routers. In this paper, to support end-to-end delay requirements, we propose a novel network scheduling scheme, called the bulk scheduling scheme (BSS), which is built on top of existing schedulers of intermediate nodes without modifying transmission protocols on either the sender or receiver sides. By inserting special control packets, which called TED (Traffic Specification with End-to-end Deadline) packets, into packet flows at the ingress router periodically, the BSS schedulers of the intermediate nodes can dynamically allocate the necessary bandwidth to each flow to enforce the end-to-end delay, according to the information in the TED packets. The introduction of TED packets incurs less overhead than the per-packet marking approaches. Three flow bandwidth estimation methods are presented, and their performance properties are analyzed. BSS also provides a dropping policy for discarding late packets and a feedback mechanism for discovering and resolving bottlenecks. The simulation results show that BSS performs efficiently as expected. Author Affiliation: (a) Department of Computer Science, National Tsing Hua University, Hsinchu, Taiwan, ROC (b) Institute of Information Science, Academia Sinica, Taipei, Taiwan, ROC (c) Department of Information Management, National Taiwan University, Taipei, Taiwan, ROC Article History: Received 21 February 2007; Revised 4 November 2007; Accepted 27 November 2007 Article Note: (miscellaneous) Responsible Editor: P. Frossard

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2006.07.013 Byline: Jeng Farn Lee (a)(c), Meng Chang Chen (a), Yeali Sun (b) Keywords: Scheduling; Rate control; Weighted fair; QoS Abstract: While existing weighted fair scheduling schemes guarantee minimum bandwidths/resources for the classes/processes of a shared channel, the maximum rate control, which is critical to service providers, carriers, and network managers for resource management and business strategies in many applications, is generally enforced by employing traffic policing mechanisms. These approaches use either a concatenation of the rate controller and scheduler, or a policer in front of the scheduler. The concatenation method uses two sets of queues and a management apparatus that incurs overhead. The latter method may allow bursty traffic to pass through the controller, which violates the maximum rate constraint, or results in packet loss. In this paper, we present a new weighted fair scheduling scheme, WF.sup.2Q-M, which can simultaneously support maximum rate control and minimum service rate guarantees. WF.sup.2Q-M uses the virtual clock adjustment method to enforce maximum rate control and distribute the excess bandwidths of saturated sessions to other sessions without recalculating the virtual starting and finishing times of sessions. In terms of performance, we prove that WF.sup.2Q-M is theoretically bounded by a corresponding fluid reference model. A procedural scheduling implementation of WF.sup.2Q-M is proposed, and a proof of correctness is given. Finally, we present the results of extensive experiments to show that the performance of WF.sup.2Q-M is just as claimed. Author Affiliation: (a) Institute of Information Science, Academia Sinica Taiwan, Taipei 115, Taiwan, ROC (b) Department of Information Management, National Taiwan University, Taiwan, ROC (c) Department of Electrical Engineering, National Taiwan University, Taipei 106, Taiwan, ROC Article History: Received 3 November 2004; Revised 4 May 2006; Accepted 27 July 2006 Article Note: (miscellaneous) Responsible Editor: R. Sivakumar

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2006.06.005 Byline: Meng Chang Chen (a), Li-Ping Tung (b), Yeali S. Sun (c), Wei-Kuan Shih (b) Keywords: Differentiated services; Quality of Service; VoIP; Wireless LAN; IEEE 802.11 Abstract: In this paper, we propose a new per-CLAss Flow fixed proportional differentiated service model (CLAF) and a companioning medium access control scheme for multi-service wireless LANs (WLANs), based on the IEEE 802.11 framework. Different from conventional relative differentiated service, in CLAF, a fixed bandwidth quality ratio is guaranteed on per-class per-flow basis regardless of the traffic load of each service class. Specifically, each service class is assigned a number of separate coordination periods, proportional to the policy-based bandwidth quality ratio for class isolation. Each class is associated with its own contention window size which is dynamically adjusted in accordance with the number of flows in the class in such a way to minimize collision probability between flows of the same class. Simulations results of the CLAF performance as well as a comparison with IEEE 802.11e EDCA including the support of QoS-sensitive VoIP applications are presented. The results show that the proposed scheme outperforms EDCA and achieves better resource utilization efficiency. CLAF can provide users a more predictive, affirmative service guarantees than conventional relative differentiated service like IEEE 802.11e EDCA. Author Affiliation: (a) Institute of Information Science, Academia Sinica, NanKang, Taipei 115, Taiwan, ROC (b) Department of Computer Science, National Tsing Hua University, Hsinchu, Taiwan, ROC (c) Department of Information Management, National Taiwan University, Taipei, Taiwan, ROC Article History: Received 3 May 2006; Revised 13 June 2006; Accepted 18 June 2006 Article Note: (miscellaneous) Responsible Editor: X.S. Shen

Self-regulated learning (SRL) is helpful to students. On the other hand, prior knowledge has great effects on students' self-regulation and learning performance. To this end, this study aimed to examine how high prior knowledge students (HPKs) and low prior knowledge students (LPKs) behaved differently when interacting with a SRL environment. To achieve this aim, we proposed a self-regulated learning support system (SRLSS) for a mathematical course. The results showed that the gap of learning performance between the HPKs and LPKs was removed after a long-term learning process. Moreover, the LPKs and HPKs behaved similarly in the forethought and self-reflection phases but some behavior differences were found in the performance phase, where the LPKs relied on the notes and sought support the dashboard and quiz records while the HPKs did not demonstrate such a tendency. Our results' theoretical and methodological implications and possible applications for further research are also discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] We propose an anonymous multi-server authenticated key agreement scheme. [•] Our scheme is a three-factor authentication scheme. [•] Our scheme is a lightweight authentication scheme which uses the hash function. [•] The proposed scheme can resist many kinds of attacks. [Copyright &y& Elsevier]

Abstract: Prior knowledge is an important issue in the study of concept acquisition among students. Traditional studies on prior knowledge generation during reading activities have focused on extracting sentences from reading materials that are manually generated by website administrators and educators. This is time-consuming and strenuous, and hence personalized prior knowledge recommendation is difficult to perform. To cope with this problem, we combine the concept of prior knowledge with social tagging methods to assist the reading comprehension of students studying English. We incorporate tags into a tag based learning approach, which then identifies suitable supplementary materials for quickly constructing a student's prior knowledge reservoir. The experimental results demonstrate that the proposed approach benefits the students by embedding the additional information in social knowledge, and hence significantly improve their on-line reading efficiency. [Copyright &y& Elsevier]

Abstract: In this paper, we propose using chi-square statistics to measure similarities and chi-square tests to determine the homogeneity of two random samples of term vectors for text categorization. The properties of chi-square tests for text categorization are studied first. One of the advantages of chi-square test is that its significance level is similar to the miss rate that provides a foundation for theoretical performance (i.e. miss rate) guarantee. Generally a classifier using cosine similarities with TF∗IDF performs reasonably well in text categorization. However, its performance may fluctuate even near the optimal threshold value. To improve the limitation, we propose the combined usage of chi-square statistics and cosine similarities. Extensive experiment results verify properties of chi-square tests and performance of the combined usage. [ABSTRACT FROM AUTHOR]

Abstract: While voice over IP (VoIP) services have brought many desirable communication features to the general public, they have also become a medium through which criminals communicate and conduct illegal activities e.g., fraud and blackmail without being intercepted by law enforcement agencies (LEAs). Previous research on IP traceback focused on tracking IP addresses on the network layer. The mechanisms developed thus far, however, require an inefficient and sometimes infeasibly large amount of router and network support. In this paper, we propose a collaborative forensics mechanism that cooperates with related network operators (NWO) and service providers (SvP) in tracing back VoIP calls without depending on routers throughout the full trace path. We discuss the various kinds of attacks of VoIP services and the characteristics of VoIP service requests as they pertain to those attacks. Additionally, we propose a procedure for identifying forged header field values (HFVs) on SIP requests, and introduce the concept of active forensics. This can lead to a reduction in the probability of important information being deleted by the time collaborative forensics is initiated, and thus assist law enforcement agencies in intercepting criminals. We also describe extended applications for traceback for attacks resulting in Distributed Denial of Service and those involving mobile phones. [Copyright &y& Elsevier]

Abstract: For students of English as a Foreign Language (EFL), reading exercises are critical not only for developing strong reading comprehension, but also for developing listening, speaking, and writing skills. Prior research suggests that social, collaborative learning environments are best suited for improving language ability. However, opportunities for English learners to collaboratively practice reading comprehension are minimal, and due to resource constraints and a lack of accurate evaluation methods, English instructors rarely assess student literacy effectively. In response to these problems, we propose a Tag-based Collaborative reading learning System (TACO) that makes use of Web 2.0 Internet social tagging techniques to provide a collaborative environment for reading English. We test our system’s ability to both improve reading comprehension and aid teachers in accurately assessing literacy by conducting a three-month trial with 56 participating Taiwanese high school students from February to May 2009. During this period, post-testing results show a significant improvement in reading scores among participants in our tag-based system, and survey feedback from teachers suggests an improved capacity for literacy assessment. [Copyright &y& Elsevier]

An online learning community enables learners to access up-to-date information via the Internet anytime–anywhere because of the ubiquity of the World Wide Web (WWW). Students can also interact with one another during the learning process. Hence, researchers want to determine whether such interaction produces learning synergy in an online learning community. In this paper, we take the Technology Acceptance Model as a foundation and extend the external variables as well as the Perceived Variables as our model and propose a number of hypotheses. A total of 436 Taiwanese senior high school students participated in this research, and the online learning community focused on learning English. The research results show that all the hypotheses are supported, which indicates that the extended variables can effectively predict whether users will adopt an online learning community. Finally, we discuss the implications of our findings for the future development of online English learning communities. [Copyright &y& Elsevier]