19801796
Multimedia Over IP For Thin Clients : Building A Collaborative Resource-Sharing Prototype
This paper describes the issues and the techniques of enabling multimedia applications with thin-client/server computing. A prototype of a video communication system based on H.323 family of ITU-T recommendations has been developed to demonstrate the efficient support to multimedia applications with a terminal server and thin clients in an IP-based thin-client computing environment. With the proposed architecture, a collaborative multi-user audio/video conference system is presented as an illustrative application. The collaborative multiuser audio/video conference system leverages the benefit of sharing common components among multiple conference terminals as well as increases their extensibility and ease of use. As a result, we can attain a balanced architecture that supports both centralized management of application softwares and distributed multimedia processing for I/O devices.
37840776
Design and implementation of a network application architecture for thin clients
This paper explores the issues and the techniques of enabling multimedia applications for the thin client computing. Our study on the network applications over thin clients is devoted to the universal plug-in architecture which supports multimedia applications over thin clients. With the proposed architecture, the universal plug-in technique is devised to shift jobs from thin clients to a supporting server, thus reducing the computing overhead required by the thin clients. In addition, this plug-in architecture is implemented and empirically evaluated It is shown by our experiments that the proposed architecture not only significantly enhances the multimedia capability of thin clients but also reduces the memory consumed by the clients for various applications, showing the very advantage of the universal plug-in architecture for thin clients of limited resources.
18278456
On General Results for All-to-All Broadcast
All-to-all broadcast refers to the process by which every node broadcasts its certain piece of information to all other nodes in the system. In this paper, we develop all-to-all broadcast schemes by dealing with two classes of schemes. A prior scheme based on generation of minimal complete sets is first described, and then a new scheme based on propagation of experts is developed. The former always completes the broadcasting in the minimal number of steps and the latter is designed to minimize the number of messages. Performance of these two classes of schemes is comparatively analyzed. The all-to-all broadcast scheme desired can be derived by combining the advantages of these two classes of schemes.
14887651
Adaptive recovery techniques for real-time audio streams
There are a number of packet-loss recovery techniques proposed for streaming audio applications. However, there are few works that are able to exploit the tradeoff between the recovery quality and the computational complexity. We develop a recovery method, called DSPWR (Double Sided Pitch Waveform Replication) which is able to tolerate a much higher packet loss rate. In essence, DSPWR is composed of several procedures devised to improve the quality of the reconstructed speech. It is noted that a more sophisticated recovery scheme that can tolerate a higher degree of packet loss in general requires a larger computational cost. In view of this, we evaluate the quality of the reconstructed speech under different packet loss rates for various receiver-based recovery methods, and compare the computational complexity among these methods. Under the acceptable speech quality whose MOS (Mean Opinion Score) is above 3.5, we develop an adaptive mechanism that can select the recovery method with the minimal complexity in accordance with different packet loss rates encountered. To conduct real experiments in the networks, we implement these recovery methods and evaluate the performance of DSPWR devised and the adaptive recovery techniques empirically. As validated by our experimental results, the adaptive mechanism is able to strike a compromise between the computational overhead and the quality of the speech desired.
29466407
An adaptive transmission scheme for audio and video synchronization based on real-time transport protocol
Multimedia streams impose tight temporal constraints since different kinds of continuous multimedia streams have to be played synchronously. We devise in this paper an adaptive transmission scheme to ensure the continuous and synchronous playback of audio and video streams based on Real-time Transport Protocol. Realization of our adaptive scheme is composed of a series of operations in three stages, namely, (1) dynamic reordering mechanism, (2) decoding-recovery mechanism, and (3) adaptive synchronization mechanism. An empirical study is conducted to provide insights into our adaptive transmission scheme. As validated by our simulation results, the adaptive transmission mechanism is able to strike a good balance of both stable playback and the end-to-end delay reduction. Furthermore, we analyze the jitter resistance, the end-to-end delay, and the buffer size required in order to enhance the applicability of this scheme to more applications that require the transmission of multimedia data.
6688024
Error-resilient real-time video communications over IP-based LANs
Video communication over IP networks involves more issues than that over ATM networks in terms of error control. First, IP networks provide neither prioritized transmission nor guaranteed QOS for data packets. Second, video streams need to be packetized well before transmission over IP networks in order to have good error resilience characteristics. Finally, the mitigation of spatial and temporal error propagation in IP networks is very different from that in ATM networks upon the loss of IP packets. In this paper, we develop an error-resilient video communication system based on the H.323 family of ITU-T recommendations. With a low-delay backward channel for packet receipt reports, bidirectional error resilience mechanisms are employed to avoid error spreading in the temporal domain. Two operation modes, i.e., ACK and NACK, are devised for two communicating parties to eliminate error propagation after either one frame lag or one round trip delay without consuming much additional bandwidth as compared to simple INTRA updates. Our system can also adaptively choose an operation mode to maintain a satisfactory video quality at the decoder under variable channel error conditions. It is shown by experimental results that our error control scheme is suitable for video transmission over IP-based LANs at packet loss rates up to 20%.
26236484
A new object-oriented method integrating Jackson structured programming method
Abstract This article presents a new object-oriented method which integrates the Jackson Structured Programming method with an object-oriented approach. The new method analyzes the user's services, identifies attributes from data structure diagrams, and identifies operations from program structure diagrams. Also, this method defers the identification of class relationships until the attributes and operations have been identified, so as to prevent premature decisions. In addition, the concept of “leading object” is used to decrease the number of actors and agents and to increase the number of servers in a system. This may enhance reusability of the objects.
12280706
A distributed multi-agent system for collaborative information management and sharing
In this paper, we present DIAMS, a system of distributed, collaborative agents to help users access, manage, share and exchange information. A DIAMS personal agent helps its owner find information most relevant to current needs. It provides tools and utilities for users to manage their information repositories with dynamic organization and virtual views. Flexible hierarchical display is integrated with indexed query search to support effective information access. Automatic indexing methods are employed to support user queries and communication between agents.
9144862
Rules and fuzzy rules in text: concept, extraction and usage
Several concepts and techniques have been imported from other disciplines such as Machine Learning and Artificial Intelligence to the field of textual data. In this paper, we focus on the concept of rule and the management of uncertainty in text applications. The different structures considered for the construction of the rules, the extraction of the knowledge base and the applications and usage of these rules are detailed. We include a review of the most relevant works of the different types of rules based on their representation and their application to most of the common tasks of Information Retrieval such as categorization, indexing and classification.
38658502
Learning by Discovering Problem Solving Heuristics Through Experience
The authors present a system, called SAFE (strategy acquisition from experience), which incorporates novel methods for discovering domain-dependent problem-solving heuristics. SAFE is implemented as a sorting system whose sorting strategies are represented as production rules. SAFE initially uses the insertion sort strategy to solve problems. After solving each given problem. SAFE learns symbolic rules from the solution path which is obtained by applying the existing heuristic information. By one or several processes of learning. SAFE is able to obtain the heuristics to sort new problems with minimum exchanges of elements. The notion of shortcut, an effective inductive learning bias for reducing the hypothesis space to be searched during learning, is introduced. >
30612222
Constrained minimum vertex cover in bipartite graphs: complexity and parameterized algorithms
Motivated by the research in reconfigurable memory array structures, this paper studies the complexity and algorithms for the constrained minimum vertex cover problem on bipartite graphs (NIN-CVCB) defined as follows: given a bipartite graph G = (V, E) with vertex bipartition V = U ∪ L and two integers ku and kl, decide whether there is a minimum vertex cover in G with at most ku vertices in U and at most kl vertices in L. It is proved in this paper that the MIN-CVCB problem is NP-complete. This answers a question posed by Hasan and Liu. A parameterized algorithm is developed for the problem, in which classical results in matching theory and recently developed techniques in parameterized computation theory are nicely combined and extended. The algorithm runs in time O(1.26ku + kl + (ku + kl) |G|) and significantly improves previous algorithms for the problem.