42395704
On the use of hierarchical information in sequential mining-based XML document similarity computation
Measuring the structural similarity among XML documents is the task of finding their semantic correspondence and is fundamental to many web-based applications. While there exist several methods to address the problem, the data mining approach seems to be a novel, interesting and promising one. It explores the idea of extracting paths from XML documents, encoding them as sequences and finding the maximal frequent sequences using the sequential pattern mining algorithms. In view of the deficiencies encountered by ignoring the hierarchical information in encoding the paths for mining, a new sequential pattern mining scheme for XML document similarity computation is proposed in this paper. It makes use of a preorder tree representation (PTR) to encode the XML tree’s paths so that both the semantics of the elements and the hierarchical structure of the document can be taken into account when computing the structural similarity among documents. In addition, it proposes a postprocessing step to reuse the mined patterns to estimate the similarity of unmatched elements so that another metric to qualify the similarity between XML documents can be introduced. Encouraging experimental results were obtained and reported.
10729822
Segment-based application level multicast (SALM) for supporting group communication in CSCW applications
This paper illustrates an application level multicast architecture -segment-based application level multicast (SALM). The SALM partitions the shared multicast tree into segments and creates control mesh group (CMG) composed of segment leaders. SALM, in accordance with estimations of intra-segment and inter-segment interactions, dynamically adjusts the sizes of the segments and the configuration of CMG to improve the perceived performance in a collaborative working environment and a relatively stable shared multicast tree structure. The main purpose of CMG is to improve users' performance when they interact with CSCW applications.
11534317
A solid modeling library for the World Wide Web
A library of functions for the creation, manipulation, and viewing of solid models was created for deployment on the World Wide Web. The core data structure was based on the halfedge boundary-representation data structure proposed by M. Mantyla but much functionality had been added. It provided an alternate, constructive-solid-geometry interface to the core data structure. It was initially implemented in C and subsequently re-implemented in Java. An interface to the STEP standard and various applications such as a simple solid modeling applet, a conic illustrator applet, and a virtual furniture showroom applet had been built. It is being extended to support multiple simultaneous users as part of a prototype WWW-based tele-processing manufacturing system.
41363533
Accessing Hidden Web Documents by Metasearching a Directory of Specialty Search Engines
Many valuable Web documents have not been indexed by general search engines and are only accessible through specific search interfaces. Metasearching groups of specialty search engines is one possible way to gain access to large amount of such hidden Web resources. One of the key issues for returning quality metasearch results is how to select the most relevant specialty search engines for a given query. We introduce a method for categorizing specialty search engines automatically into a hierarchical directory for metasearching. By utilizing the directory, specialty search engines that have a high possibility of having relevant information and resources can be easily selected by a metasearch engine. We evaluate our algorithm by comparing the directory built by the proposed algorithm with another one that was built by human-judgments. In addition, we present a metasearch engine prototype, which demonstrates that such a specialty search engine directory can be beneficial in locating essential but hidden Web resources.
14225029
A collaborative filtering framework based on fuzzy association rules and multiple-level similarity
The rapid development of Internet technologies in recent decades has imposed a heavy information burden on users. This has led to the popularity of recommender systems, which provide advice to users about items they may like to examine. Collaborative Filtering (CF) is the most promising technique in recommender systems, providing personalized recommendations to users based on their previously expressed preferences and those of other similar users. This paper introduces a CF framework based on Fuzzy Association Rules and Multiple-level Similarity (FARAMS). FARAMS extended existing techniques by using fuzzy association rule mining, and takes advantage of product similarities in taxonomies to address data sparseness and nontransitive associations. Experimental results show that FARAMS improves prediction quality, as compared to similar approaches.
30816460
Token-tray/weighted queuing-time (TT/WQT): an adaptive batching policy for near video-on-demand system
In near video-on-demand (near-VoD), requests for a video title are grouped together (i.e. batched) and are served with a single multicast stream, thereby increasing the number of concurrent users which can be supported by the system. Since users may not be able to tolerate the delay incurred by batching and hence cancel their requests, a batching policy should be designed so as to achieve low user loss and high revenue (given by the total pay-per-view collected over a long period of time across all movies). We propose an adaptive batching policy which offers users low delay at low arrival rate, and gates the allocation of the channels at high rate. Such adaptivity is achieved by the use of a simple "token-tray" (TT) scheme which governs when a stream may be allocated to a movie. In assigning a movie to a stream, we propose a weight function which depends on the user queuing-time and its pay-per-view (hence the term "weighted queuing-time") (WQT). By comparing our batching policy (TT/WQT) with a number of traditional ones (FCFS, forced-wait, batch-size-based scheme, etc.), our scheme is shown to achieve the highest revenue and lowest loss rate even when the arrival rate changes, with the user loss rate across the movies being fairly uniform, and the user delay being fairly low even at high arrival rate.
45355055
TCP and UDP performance for Internet over optical packet-switched networks
A strong candidate for the future Internet core is optical packet-switched (OPS) network. In this paper, we study the impact of mechanisms as employed in OPS networks on the performance of upper layer Internet protocols represented by TCP and UDP. The mechanisms we investigate are packet aggregation, deflection routing, and ingress buffering. We show that packet aggregation in general improves TCP throughput, and the improvement increases with the aggregation interval (or optical packet size). With the packets destined to the same egress optical switch, aggregation may be done at different granularities: aggregating all the packets (full aggregation), aggregating packets from the same traffic class (per-class aggregation), and aggregating packets from the same flow (per-flow aggregation). We show that with per-class aggregation and per-flow aggregation some flows may be severely penalized in throughput at large aggregation intervals, resulting in significant degradation in TCP fairness, because of the synchronization problem with shared queueing. By using weighted fair queueing (WFQ) at the ingress buffer, in contrast, we show that differentiated QoS (in terms of throughput) can be provisioned for both TCP and UDP traffic even with deflection routing. Deflection routing avoids packet losses, but results in out-of-order packet delivery and increased packet delay jitter. We show that TCP throughput can be significantly improved by deflection routing in spite of the packet reordering, and the UDP packet delay jitter introduced by deflection routing can be alleviated by packet aggregation and ingress buffering. We also show that ingress buffering significantly improves TCP throughput and the ingress buffer only needs a small size (in terms of the number of optical packets).
3100826
Low-Complexity Rate Control for Efficient H.263 to H.264/AVC Video Transcoding
Rate control is a complicated problem in the H.264/AVC coding standard, extra computation is usually needed for the existing rate control schemes to estimate the complexity of frames or macroblocks (MBs). However, during transcoding, information from preceded video could be used to simplify the rate control. In this paper, we propose a low-complexity rate control scheme for transcoding from H.263 to H.264/AVC. The relationship between the rate of the pre-coded video and both the rate and distortion of the transcoded video are studied. By using only the rate information from the preceded video, we introduce a row-layer bit allocation and perform average rate shaping across a row of MBs. Estimation error diffusion is also introduced. The proposed scheme has sufficiently lower computational complexity than other methods as there is no explicit complexity measurement of MBs and complicated parameters updating. Experimental results show the effectiveness of the proposed scheme.
39840719
Mapping XML Schema to Relations Using Genetic Algorithm
As web-applications grow in number and complexity, there is a need for efficient mappings from XML schemas to the flat relational tables so that existing functions in relational database systems can be utilized. However, many of the existing mapping methods, such as the model-based or the structure-based methods, do not exploit query history for better query performance. In this paper, we propose the use of genetic algorithm (GA) in a cost-based approach for converting a XML schema to relational tables. By formulating the mapping problem as a cost optimization task with respect to a set of weighted frequent queries, we can obtain an efficient mapping that minimizes the queries execution time. In our experiments, we show that the mapping obtained by GA is superior to other non-cost-based approaches. In particular, the GA approach has out-performed the greedy heuristic in the browsing queries where the accessed attributes are many and scattered.
14067684
A Cost-Based Evaluation of End-to-End Network Measurements in Overlay Multicast
Application-layer multicast (ALM, or overlay multicast) has been proposed to overcome limitations in IP multicast. While much measurement work (such as delay or connectivity measurement) has been conducted to build efficient ALM trees, several interesting questions therein are left unclear: (1) What are the measurement costs of the different measurement methods? (2) What is the major improvement to an ALM tree by using a certain measurement method? (3) To achieve the target tree performance, what is the most cost-efficient measurement method? In this paper, we study three representative measurement methods, i.e., delay measurement, connectivity measurement and available bandwidth measurement. We select six typical ALM protocols each adopting at least one of the measurement methods and evaluate their performance on Internet-like topologies. Our study shows that delay and connectivity measurements can effectively reduce end-to-end delay in overlay trees with low measurement costs. Only using delay measurement may lead to a tree consuming much network resource. The use of connectivity and bandwidth measurements can build a tree with low resource consumption.