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Protein secondary structure prediction problem is one of the widely studied problems in bioinformatics. Predicting the secondary structure of a protein is an important step for determining its tertiary structure and thus its function. This paper explores the protein secondary structure problem using a novel feature selection algorithm combined with a machine learning approach based on random forests. For feature reduction, we propose an algorithm that uses a graph theoretical approach which finds cliques in the non-position specific evolutionary profiles of proteins obtained from BLOSUM62. Then, the features selected by this algorithm are used for condensing the position specific evolutionary information obtained from PSI-BLAST. Our results show that we are able to save significant amount of space and time and still achieve high accuracy results even when the features of the data are 25% reduced. [ABSTRACT FROM AUTHOR]

The concept of structural clusters defining the vocabulary of protein structure is one of the central concepts in the modern theory of protein folding. Typically clusters are found by a variation of the K-means or K-NN algorithm. In this paper we study approaches to estimating the number of clusters in data. The optimal number of clusters is believed to result in a reliable clustering. Stability with respect to bootstrap sampling was adapted as the cluster validation measure for estimating the reliable clustering. In order to test this algorithm, six random subsets were drawn from the unique chains in the PDB. The algorithm converged in each case to unique set of reliable clusters. Since these clusters were drawn randomly from the total current set of chains, counting the number of coincidences and using basic sampling theory provides a rigorous statistical estimate of the number of unique clusters in the dataset. [ABSTRACT FROM AUTHOR]

Neuroscience research increasingly involves the exploration of computational models of neurons and neural networks. To ensure systematic model exploration, it is often desirable to conduct a parameter-space analysis in which the behavior of the model is catalogued over a very large range of parameter permutations. Here we report the development and testing of a tool-kit called NEURONgrid for conducting this type of analysis in a grid environment using NEURON (Hines & Carnevale, 1997, 2001), a popular and powerful simulation platform for the neurosciences. NEURONgrid provides helper classes within NEURON for manipulating parameters, a package of NEURON for running in a grid environment, and a management client that enables neuroscientists to submit a parameter-space analysis, monitor progress, and download results. NEURONgrid provides a user-friendly means for conducting intensive model exploration within the neurosciences. It is available for download at http://neurongrid.homeip.net. [ABSTRACT FROM AUTHOR]

An important problem in wireless ad hoc networks is to select a few nodes to form a virtual backbone that supports routing and other tasks such as area monitoring. Connected dominating set (CDS) has been proposed to approximate the virtual backbone. Although computing minimum CDS is known to be NP-hard, many distributed protocols have been presented to construct small CDS. However, these protocols are either too complicated, need non-local information or have slow convergence speed, are not adaptive to topology changes. In this paper, we propose a new pure localized algorithm for computing the approximate solution to the minimum CDS problem. The algorithm starts with a feasible and near-optimal CDS solution via marking process based on classification of neighbors, and removes vertices from this solution by redundancy elimination, until an approximate CDS is found. Both analytical and experimental results demonstrate that our algorithm has better performance than other distributed algorithms. Keywords: connected dominating set, distributed algorithm, pure localized algorithm, routing, wireless ad hoc networks. [ABSTRACT FROM AUTHOR]

The speed and convenience of the Internet facilitated the development of electronic commerce (e-commerce). E-commerce research and technologies have always drawn the attention of researchers. Among them, the application of mobile agent on e-commerce has drawn much attention in recent years. Mobile agents can roam freely over different execution environments to execute tasks assigned to them. However, a mobile agent may be attacked when it requests services from other servers or when comes in contact with and exchange information with another agents while roaming on the internet. Hence, a mobile agent user may be concerned that his mobile agent could be corrupted or private information tapped and pirated by other agents. To ensure the security of mobile agents in public network environment, this paper proposes a security scheme that is suitable for mobile agents. The scheme includes access control and key management; it is also an improvement on the key management and access control for mobile agent scheme of Volker and Mehrdad. The proposed scheme corrects the drawback in Volker and Mehrdad's scheme which is the need of a large amount of storage for storing the secret keys. Security and performance analysis of our scheme proves the proposed scheme to be more efficient and secure. [ABSTRACT FROM AUTHOR]

Mining association rules from multi-stream data has received a lot of attention to the data mining community. It is quite effective and useful to discover such rules. However, it is a very time consuming and expensive task to mine the rules from these kinds of time ordered real valued continuous data sets with high dimensionality when they are enormous in size. This strongly motivates the need of efficient parallel processing techniques and algorithms. In this paper, we use parallel processing to discover dependency from the large amount of time series multi-stream data. We apply two parallel programming techniques (OpenMP and MPI) to implement this. The experimental results conducted in multiprocessor systems show the effectiveness of MPI over OpenMp. [ABSTRACT FROM AUTHOR]

Scientific collaboration has emerged as an important tool for getting forefront research results by interoperating geographically distributed scientific equipment to solve complicated scientific problems. Grid technologies offer effective strategies to achieve this ambitious goal. However, more capabilities are required in the context of Equipment Grid due to the complexity of collaboration between equipment resources. In this paper an interesting equipment interoperation chain model is proposed. Equipment resources are organized into equipment pools, based on which the interoperation chain of equipment is built. The performance is discussed by means of several theoretical tools like Petri Net and π-Calculus from the different viewpoint of users. The structure of interoperation chain is proven highly efficient and feasible. Finally we analyze the prospective direction and challenges in this field. [ABSTRACT FROM AUTHOR]

This work studies the allocation of bandwidth resources in wireless ad hoc networks. The highest-density clustering algorithm is presented to promote reuse of the spatial channel and a new slot allocation algorithm is proposed to achieve conflict-free scheduling for transmissions. Since the location-dependent contention is an important characteristic of ad hoc networks, in this paper we consider this feature of ad hoc networks to present a new cluster formation algorithm, by increasing the number of simultaneous links to enhance spatial channel reuse. Furthermore, because each cluster has its own scheduler and schedulers operate independently of each other, the transmissions may conflict among the clusters. In this paper, we classify the flows by the locations of their endpoints to prevent this problem. Finally, the proposed mechanism is implemented by simulation and the results reveal that the conflicts can be efficiently avoided without global information and the network throughput is improved without violating fairness. [ABSTRACT FROM AUTHOR]

Route caching strategy is an important on-demand routing protocol for mobile ad hoc networks. On-demand routing protocol for mobile ad hoc networks utilizes route caching in different forms to reduce overheads, peer-to-peer delay. This paper presents a variation in view compared to DSR and HER, to minimize cache staleness, partitions and enhance reliability of service. The variation is with respect to identification of route and cache validation of errors using different techniques namely Update Route Caching (URC), Temporal Cache Validation (TCV), Negative Cache Validation (NCV) and Combined Cache Validation (CCV). The proposed method refreshes cache more often than the DSR and HER thereby initiating route requests earlier, when a route still being used is broken, thus reducing peer to peer delay to transmit packets. The results of GloMoSim simulator validates higher cache hit percentage and reliable delivery of packets in the technique Combined Cache Validation (CCV) when in comparison to DSR and HER [ABSTRACT FROM AUTHOR]

The use of periodic invalidation reports (IRs), has been shown to be a useful technique for conserving wireless bandwidth and battery power. However, IR-based schemes have some drawbacks, such as long query delay and low client caching availability, even if the clients have sufficient local cache capacity. In this paper, we propose an efficient cache access protocol to address these problems. Instead of passively waiting, the clients use the local cache actively. Using our protocol, we can remove the "false alarm" that causes unnecessary delay. Based on our threshold-based scheme, the proposed protocol can optimize response time with little loss of data currency. Our simulation results are carried out to evaluate the proposed methodology. Compared to previous IR-based schemes, our scheme can reduce the response time significantly with a very little loss of data currency. [ABSTRACT FROM AUTHOR]

The Internet is replacing the traditional telephone network as the ubiquitous network infrastructure. Internet customers are increasing at an exponential rate and will continue to increase in the near future. With the proliferation of mobile communication technologies and wireless personal devices, the demand for mobile communications has grown exponentially over the last decade and is expected to grow even more in the near future. This paper proposes a new bandwidth allocation scheme that guarantees the time independent fairness and fault tolerance in the heterogeneous mobile communication services. It will hold some calls in the second buffer rather than directly discarding it when the residual bandwidth is insufficient. A multimedia call that satisfies all connection requirements has precedence over other calls. [ABSTRACT FROM AUTHOR]

In recent times, there are increasing numbers of computer vision and pattern recognition (CVPR) technologies being applied to real time video processing using single processor PCs. However, these multiple computational expensive tasks are generating bottlenecks in real-time processing. We propose a scheme to achieve both high throughput and accommodation to user-specified scheduling rules. The scheduler is then distributing ‘slices' of the latency insensitive tasks such as video object recognition and facial localization among the latency sensitive ones. We show our proposed work in detail, and illustrating its application in a real-time e-learning streaming system. We also provide discussions into the scheduling implementations, where a novel concept using interleaved SIMD execution is discussed. The experiments have indicated successful scheduling results on a high end consumer grade PC. [ABSTRACT FROM AUTHOR]

The importance of multiuser detection for CDMA-based ad hoc network is addressed in this paper. Conventionally, the terminal in CDMA-based ad hoc network uses matched filter to receive packets, so the performance (e.g., throughput) of the network suffers from multi-access interference (MAI). Different from above scheme, in this paper, each terminal of the ad hoc network is equipped with an adaptive blind linear multiuser detector, so the ability of MAI-resistance is gained. Based on fully-connected network model and Log-distance path loss radio propagation model, the throughput of ad hoc network with multiuser detection is studied. Simulation results show that multiuser detection can remarkably enlarge the throughput of ad hoc network. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a new QoS framework with Distributed Adaptive Resource Management(DARM). DARM provides end-to-end QoS guarantees to individual flows with minimal overhead, while keeping the scalability characteristic of DiffServ. In DARM, per-flow admission control and resource reservation, in conjunction with a novel IPv6 flow label mechanism, can be processed instantaneously in a fully distributed and independent manner at edge of network without hop-by-hop signaling. In addition, DARM is capable of reconfiguring network resource adaptively according to dynamically changing of traffic load. Through extensive simulations, the results clearly exhibit that DARM has a better overall performance comparing to the IntServ and DiffServ. [ABSTRACT FROM AUTHOR]

The viability of overlay multicasting has been established by previous research. However, in order to apply overlay multicast to Internet-scale distributed systems, such as the Grid and Peer-to-Peer systems, the issue of effectively enforcing fairness among peers so as to optimize overall performance remains as a challenge. This paper argues that simply applying a multiple-tree scheme does not provide sufficient fairness, in terms of performance. Instead, we believe that a better way to define fairness, for performance's sake, is to factor in peers' proportional contributions as it provides the opportunity to support many simultaneous multicasting sessions. This paper then presents a protocol, called FairOM (Fair Overlay Multicast), to enforce proportional contributions among peers in Internet-scale distributed systems. By exploiting the notion of staged spare capacity group and deploying a two-phase multicast forest construction process, FairOM enforces proportional contributions among peers, which enables more simultaneous multicasting sessions and alleviates potential hot-spots. The simulation results of a large multicast group with 1000 members show that FairOM achieves the goal of enforcing proportional contributions among peers and does not overwhelm the peers, including the multicast source. FairOM also achieves low delay penalty for peers and high path diversity. [ABSTRACT FROM AUTHOR]

Next-generation network (NGN) is a new concept and becoming more and more important for future telecommunication networks. This paper illustrates five function layers of NGN architecture and discusses some end-to-end QoS (quality of service) issues for NGN (called NGNQoS). The five function layers are: (1) Application Layer that supports SIP protocol; (2) Network Control Layer that aims at overcoming the bottleneck problems at edge nodes or servers for end-to-end admission control; (3) Adaptation Layer that supports different network configurations and network mobility; (4) Network Transmission Layer that provides end-to-end QoS control for real-time communications through integrating Differentiated Service (DiffServ) and Multi-Protocol Label Switching (MPLS) and (5) Management Layer that provides Web-based GUI browser for data presentation, monitoring, modification and decision making in NGN. [ABSTRACT FROM AUTHOR]

Managing distributed ontologies is a challenging issue in the Semantic Web area. Different to most current distributed ontologies management researches, which focus on ontologies maintenance, evolutions, and versioning, this paper proposes a new distributed ontologies management framework based on the function-oriented perspective, and its goal is to bring multiple distributed ontologies together to provide more powerful capabilities. Ontology mapping is the key factor for manage distributed ontologies. This management framework also proposes a novel approach to eliminate the redundancies and errors of mappings in distributed ontologies. [ABSTRACT FROM AUTHOR]

With the frequent changes in recent business and scientific environment, more efficient and effective workflow infrastructure is required. Besides, with increasing emphasis on Service-oriented architecture, service composition becomes a hot topic in workflow research. This paper proposes a novel approach of using ECA rules to realize the workflow modeling and implementation for service composition. First of all, the concept and formalization of ECA rule-based Workflow is presented. Second, an automatic event composition algorithm is developed to ensure the correctness and validness of service composition at design time. Finally, the proposed ECA rule-based approach for service composition is illustrated through a prototype system. [ABSTRACT FROM AUTHOR]

Multicast mobility management poses a great challenge in mobile Internet. This paper proposes a novel multicast mobility management algorithm using our proposed RingNet hierarchy, which takes advantage of our designed four states for mobility management: Not-in-the-group, PassiveReservation, QuasiReservation, and ActiveReservation, and two kinds of ranges which are closely related to a Mobile Host (MH) 's attached device called the Access Proxy (AP): TransmissionRange and ReservationRange. By judging the state of the AP and the distance between the AP and its attaching MH, operations of mobility management can be implemented. The introduction of prediction algorithm greatly decreases the blindness of resource reservation, and avoids the unnecessary waste of bandwidth. Furthermore, the introduction of resource reservation makes the smooth handoff highly probable. [ABSTRACT FROM AUTHOR]

In this paper, we first present a simple and effective path capacity predicting method to model the complex interaction between medium access mechanism and routing scheme. Based on the predicting model, an end-to-end cross-layer flow control architecture is proposed. The key issues about flowing control are discussed deeply. As we designed, whenever the path length changes, the applications adaptively modify their sending rate with the pre-computed optimal value. Simulation evaluation has demonstrated that this technique can greatly improve the performance of end-to-end transmission in ad hoc network: the throughput of the long path is improved by up to 40%. [ABSTRACT FROM AUTHOR]

The long-tailed distribution characterizes many properties of Internet traffic. The property is often modeled by Lognormal distribution, Weibull or Pareto distribution theoretically. However, it hinders us in traffic analysis and evaluation studies directly from these models due to their complex representations and theoretical properties. This paper proposes a Hyper-Erlang Model (Mixed Erlang distribution) for such long-tailed network traffic approximation. It fits network traffic with long-tailed characteristic into a mixed Erlang distribution directly to facilitate our further analysis. Compared with the well-known hyperexponential based method, the mixed Erlang model is more accurate in fitting the tail behavior and also computationally efficient. [ABSTRACT FROM AUTHOR]

Nowadays, the Internet architecture is complicated and IP addresses are limited in IPV4 context. Many users located behind different kinds of NATs or Firewalls can hardly get a public unique IP. So the hosts behind the NAT can not be accessed by the hosts behind the other NATs. Some P2P systems can partially solve such kind of problems, but unfortunately, these systems just focus the specific self-contained applications such as Skype and BitTorrent whose P2P architectures and NAT traversal mechanisms can not be re-used by other applications directly. In this paper we present a solution by setting up a Virtual Intranet Platform (VIP) which use the public DHT service -OpenDHT as the distributed address/port information rendezvous. Without changing the configuration of the NAT, all the network and distributed application service behind the NAT can make use of the VIP to communicate with the corresponding peer services outside the NAT. The performance of the bandwidth, data lost and delay problems are much better than the existing traditional C-S framework platforms, more general than specific P2P applications. The P2P Communication Platform for NAT Traversal-VIP, is robust and scalable because there are no single failure points in the platform, the structure is in distributed, and majority of the traffic data between two hosts behind the NAT can be transfer directly without relaying. [ABSTRACT FROM AUTHOR]

High availability in peer-to-peer DHTs requires data redundancy. This paper takes user download behavior into account to evaluate redundancy schemes in data storage and share systems. Furthermore, we propose a hybrid redundancy scheme of replication and erasure coding. Experiment results show that replication scheme saves more bandwidth than erasure coding scheme, although it requires more storage space, when average node availability is higher than 48%. Our hybrid scheme saves more maintenance bandwidth with acceptable redundancy factor. Keywords: Peer-to-Peer, Distributed Hash Table, Replication, Erasure Coding. [ABSTRACT FROM AUTHOR]

Over the past decade, many fully adaptive routing algorithms have been proposed in the literature, of which Duato's routing algorithm has gained considerable attention for analytical modeling. In this study we propose an analytical model to predict message latency in wormhole routed 2-dimensional torus networks in which fully adaptive routing, based on Linder-Harden's methodology [10], is employed. This methodology presents a framework in which adaptive routing algorithms can be developed for the k-ary n-cube network. Simulation experiments reveal that the latency results predicted by the proposed analytical model are in good agreement with those provided by simulation experiments. [ABSTRACT FROM AUTHOR]

The Java Virtual Machine computing model implements a multi-threading paradigm but its computing model does not define and does not verify the distribution paradigm of the threads over set of JVM instances. Without a distribution paradigm the Java Virtual Machine computing model cannot get any advantage from the theory of parallel Turing Machines. This work formally specifies and verifies the JVM computing model distribution paradigm. An intrinsic transparent thread distribution mechanism over many JVMs relying on different communication technology such as Peer to Peer is an important outcome of the presented solution. Other consequences, such as distributed JVM run-time location, aggregation and reachability, are achieved. Moreover the creation of Virtual Farms of JVMs for Multi-threading applications computing is made possible. [ABSTRACT FROM AUTHOR]

The current P2P application protocols are usually constructed over the application-level overlay network. However, because the users in the P2P systems always follow a very dynamic mode, the overlay network with poor performance will leads to the problem of connectivity—the departures of peers often break the network into plenty of small parts, and results in the resource islands. Although increasing the links between peers can enhance the performance of connectivity by information redundancy. But it will lead to the severe cost of maintenance. Then there is an urgent need to integrate the online peers as a "giant component" as large as possible, so that the resources online can be shared completely; at the same time to guarantee the cost of maintenance as little as possible. And due to the prevalence and significance of small world in reality and theory, in this paper we analyzed the correlation between the shortcuts density and the connectivity, as well as the impact of shortcuts density to robustness over the popular WS Small World model. At last, numerical simulation was done to confirm our analytic results. [ABSTRACT FROM AUTHOR]

Power conservation is a critical issue in mobile ad hoc networks, as the nodes are powered by batteries only. In this paper, according to the mobility of nodes, the power-aware dynamic adaptive replica allocation algorithm is proposed. In the power-aware dynamic adaptive replica allocation algorithm, based on the locality of data access, the replica allocation scheme is adjusted regularly in order to reduce the power consumption, and thus extend the survival time of network. The relation between mobility models and efficiency of power-aware dynamic adaptive replica allocation algorithm is studied. The results of performance evaluation show that the power-aware dynamic adaptive replica allocation algorithm can reduce the total power consumption of network greatly. [ABSTRACT FROM AUTHOR]

Call Admission Control (CAC) is crucial for assuring the quality of service (QoS) of communication in wireless cellular networks. In this paper, we propose a model, called Guard Channel Prediction Model (GCPM), for efficient call admission control satisfying the QoS requirements. A predictive value of the appropriate number of guard channels can be calculated based on this model by using statistical properties of new and handoff call arrival rates and mean call residency time, as well as the total capacity of a specific cell. Simulation studies are carried out to evaluate the performance in comparison with an existing adaptive algorithm under variable traffic loads and mobility patterns. Simulation results show that our proposed GCPM, using the static and fractional Guard Channel policy to process both types of incoming calls based on the predictive values, has gained better QoS with less blocking probabilities of both types of calls and meanwhile, larger network utilizations. Keywords: Call Admission Control, Guard Channel, Guard Channel Prediction Model (GCPM), Quality of Service (QoS), Wireless/Mobile Cellular Networks. [ABSTRACT FROM AUTHOR]

Ad hoc networks became a hot topic recently, but the routing algorithm of anycast in the ad hoc networks has not yet been much explored. In this paper, we propose a mesh-based anycast routing algorithm (MARP) for ad hoc networks. The proposed routing model is robust and reliable, which can solve the unsteady topology problem in ad hoc networks. The future work is discussed at the end of this paper. [ABSTRACT FROM AUTHOR]

The way conventional Ethernet is used today differs in two aspects from how dedicated system area networks are used. Firstly, dedicated system area networks are lossless and only drop frames when bit errors occur, while conventional Ethernet drop frames whenever congestion occur. Secondly, these networks are either deadlock free or use mechanisms which avoids deadlock situations, while still using all available links. Ethernet avoids deadlocks by using a spanning tree protocol which turns any topology into a tree. A drawback of this approach is that we are left with a lot of unused links and thus wasting resources. In this paper we describe how to obtain a lossless deadlock free network with the best possible performance, while adhering to the current Ethernet standard and using off-the-shelf Ethernet equipment. We achieve this by introducing flow control in all network nodes and by taking control over the routing algorithm. Also, we use TCP to illustrate the effect of flow control on higher layer protocols. Through simulations we verify the following tree improvements. Firstly, the activation of flow control turns Ethernet into a lossless network. Secondly, taking control over the routing algorithm allows us to build any topology without the limitations of the spanning tree protocol. And thirdly, an overall improvement in throughput is achieved by combining these enhancements. [ABSTRACT FROM AUTHOR]

The goal of geocasting protocols is to deliver data packets to a group of nodes that are within a specified geographical area, i.e., the geocast region. In an ad hoc environment, there are numerous scenarios which benefit from geocast communication. In this paper, the network is divided into grids, we propose a new routing protocol for geocasting, which combines anycast and flood. The proposed protocol utilizes the location information to route messages in grid-by-grid manner. The routing path by using proposed protocol is the shortest route between hosts in grids. The grid structure is successfully used to eliminate redundant transmission of geocasting messages. The time complexity of route discovery and the routing overhead are reduced. [ABSTRACT FROM AUTHOR]

On the basis of analyzing the evolution and drawbacks of current network fault diagnosis methods, a novel network data link troubleshooting system (NDTS) based on fuzzy neural network is proposed. NDTS tightly combines neural network and rough sets, so that it can be used to fit the smooth curves perfectly. Let the membership function as the base, an rule scavenging method is put forward in NDTS, which is the variable-precision modal, and the notion of variable-precision be founded on the measurement of dependent degree. Furthermore, NDTS is adopted to deal with the mapping relation, categorizing the network faults. The experiment system implemented by this method shows the proposed system is an open and efficient troubleshooting engine. [ABSTRACT FROM AUTHOR]

As an enhancement mechanism for the end-to-end congestion control, Active Queue Management (AQM) can keep smaller queuing delay and higher throughput by proposing fully dropping the packets at the intermediate nodes. comparing with RED algorithm, although PI controller for AQM designed by Hollot improves the stability, it seems other methods to design of robust controllers may lead to better results. Morover, the transient performance of PI controller is not perfect, such as the regulating time is so long. In order to overcome to this drawback, in this paper, a novel adaptive fuzzy logic based controller is designed for Active Queue Management (AQM) in TCP/AQM networks. From control point of view, it is rational to regard AQM as a typical regulation system. Recently many AQM algorithms have been proposed to address performance degradations of end-to-end congestion control. However, these AQM algorithms show weaknesses to detect and control congestion under dynamically changing network situations. A simulation study over a wide range of IP traffic conditions shows the effectiveness of the proposed controller in terms of the queue length dynamics, the packet loss rates, and the link utilization. [ABSTRACT FROM AUTHOR]

Both TCP and ICMP are applied in network measurement, while investigating differences between the measured results of them is important but has been less addressed. To compare the differences between TCP and ICMP when they are used in measuring host connectivity, RTT, and packet loss rate, we designed two groups of comparison programs, after careful evaluating of the program parameters, we executed a lot of experiments on the Internet. The experimental results shows, there are significant differences between the host connectivity measured using TCP or ICMP; in general, the accuracy of TCP is 20%-30% higher than that of ICMP. The case of RTT and packet loss rate is complicated, which are related to path loads and destination host loads. While commonly, the RTT and packet loss rate measured using TCP or ICMP are very close. We also give some advices on protocol selection for conducting accurate network measurements. [ABSTRACT FROM AUTHOR]

Because of the limited bandwidth, wireless communication in mobile environments is much more expensive than the communication cost in wired network. Thus, to save the cost of wireless communication, during the process of wireless Web page access, mobile unit usually prefetches some Web pages into its local cache and then disconnect itself from the network, so that updates are performed in its local cache and propagated back to Web server upon reconnection again. In this paper, after discussing the design rationale of a new Web page access mechanism, the performance of this mechanism is analyzed theoretically and experimentally. The results show that the efficiency of update propagation is improved and the burden of Web server is decreased. [ABSTRACT FROM AUTHOR]

Many studies have shown that Zipf's law governs many features of the WWW and can be used to describe the popularity of the Web objects. Based upon Zipf's law, we analyze quantitatively the relationship between the hit ratio and the size of Web cache, present approximate formulae to calculate the size of Web cache when the hit ratio is given under the condition of basic Zipf's law and Zipf-like law, determine the critical value n in the top-n prefetching algorithm by studying the effect of parameter α on the hot Web documents. Zipf's law plays an important role in solving the Internet latency, and holds the promise of more effective design and use of Web cache resources. Keywords: Zipf's law, Web Cache, Web Prefetching, Top-N. [ABSTRACT FROM AUTHOR]

Heterogeneity of Web objects is the important causes of the decrease the performance of web caching algorithms. To increase the throughput of web caching process and to improve service availability, we may consider heterogeneity of web object adaptively. In this study, we proposed the new web-caching algorithm. A heterogeneity variation of an object can be reduced as the proposed method dividedly managing. Web objects and a cache scope with heterogeneity, and it is adaptively reflecting a variation of object reference characteristics with the flowing of time. In the experiments, we verified that the performance of the proposed method was more improved than existing algorithms through the two experiment models, which considered heterogeneity of an object. [ABSTRACT FROM AUTHOR]

This paper proposes a workflow management mechanism to address a neglected aspect of existing P2P computing platforms - the lack of support for various computational models. In the workflow management mechanism, a workflow description file is used to define the workflow diagram of the target application. We develop a prototype system, and evaluate it using a test program to demonstrate how the workflow management mechanism effectively works. [ABSTRACT FROM AUTHOR]

Today many current and emerging applications require support for on-line analysis of rapidly changing data streams. Limitations of traditional DBMSs in supporting streaming applications have been recognized, prompting research to augment existing technologies and build new systems to manage streaming data. Stream-oriented systems are inherently geographically distributed and because distribution offers scalable load management and higher availability, future stream processing systems will operate in a distributed fashion. Moreover, service-based approaches have gained considerable attention recently for supporting distributed application development in e-business and e-science. In this paper, we present our innovative work to build a large scale distributed query processing over streaming data, this system has been designed as a WSRF-compliant application built on top of standard Web services technologies. Our distributed data stream Queries are written and evaluated over distributed resources discovered and accessed using emerging the WS-Resource Framework specifications. The data stream query processor has been designed and implemented as a collection of cooperating services, using the facilities of the WSRF to dynamically discover, access and use computational resources to support query compilation and evaluation. [ABSTRACT FROM AUTHOR]

With the help of distributed hash tables, the structured peer-to-peer system has a short routing path and good extensibility. However, the mismatch between the overlay and physical network is the barrier to build an effective peer-to-peer system in the large-scale environment. In this paper, we propose a generic approach to solve this problem, which is quite different from other protocol-dependent methods. We reserve the structure of system and break the coupling between the node and its identifier by swap operations. We also propose several policies to reduce the traffic overhead. The policies include adaptive probing and shadow scheme. The experiment shows that our approach can greatly reduce the average latency of overlay networks and the overhead is controllable. Keywords: peer-to-peer, overlay network, topology-aware, stretch. [ABSTRACT FROM AUTHOR]

Authentication protocols are essential for security in many systems. However, authentication protocols are error-prone and difficult to design. In pervasive computing, the inherent characteristics such as mobility and restricted resources make it even harder to design suitable authentication protocols. In this paper we propose an authentication protocol to solve an open problem in pervasive computing, that is secure use of public information utilities without accessing a trusted third party (TTP). Our solution not only provides authentication, but also establishes a secure communication channel between the user and the service provider without the participation of TTP. The authentication protocol can be built with any secure symmetric and asymmetric cryptographic algorithm. We show the protocol can resist passive and active attacks. We also discuss how the protocol can be extended to an applicable scheme with payment support. Keywords: Authentication, Pervasive Computing Security, Public Key Infrastructure, E-Commerce. [ABSTRACT FROM AUTHOR]

To extend a Peer-to-Peer (P2P) network system with the mechanisms of distributed/Grid computing, we developed a flexible JXTA- based P2P network interface and architecture, JXTPIA. The JXTPIA system provides the basic functionalities for Grid computing, such as resources allocation and sharing, task scheduling and assignment, network structure constructing and maintenance, etc. One of the main challenges in developing the JXTPIA system is efficient allocation of resources. We developed and evaluated algorithms for resource allocation to improve the efficiency of the JXTPIA system. The experimental results show that the efficiency of the JXTPIA system differs depending on the adopted algorithms. It indicates that scheduling based on limited information about peers has effects on the performance of the entire system. Though the adopted algorithms are specialized for the JXTPIA system only, the principle of the algorithms can be widely used on similar systems. Keywords: JXTPIA system, resource allocation, Grid computing, network structures. [ABSTRACT FROM AUTHOR]