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  Access Rights: Use restricted to UNT Community
  Partner: UNT Libraries
 Department: Department of Computer Science
 Collection: UNT Theses and Dissertations
Multi-Agent Architecture for Internet Information Extraction and Visualization

Multi-Agent Architecture for Internet Information Extraction and Visualization

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Date: August 2000
Creator: Gollapally, Devender R.
Description: The World Wide Web is one of the largest sources of information; more and more applications are being developed daily to make use of this information. This thesis presents a multi-agent architecture that deals with some of the issues related to Internet data extraction. The primary issue addresses the reliable, efficient and quick extraction of data through the use of HTTP performance monitoring agents. A second issue focuses on how to make use of available data to take decisions and alert the user when there is change in data; this is done with the help of user agents that are equipped with a Defeasible reasoning interpreter. An additional issue is the visualization of extracted data; this is done with the aid of VRML visualization agents. The cited issues are discussed using stock portfolio management as an example application.
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Temporally Correct Algorithms for Transaction Concurrency Control in Distributed Databases

Temporally Correct Algorithms for Transaction Concurrency Control in Distributed Databases

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Date: May 2001
Creator: Tuck, Terry W.
Description: Many activities are comprised of temporally dependent events that must be executed in a specific chronological order. Supportive software applications must preserve these temporal dependencies. Whenever the processing of this type of an application includes transactions submitted to a database that is shared with other such applications, the transaction concurrency control mechanisms within the database must also preserve the temporal dependencies. A basis for preserving temporal dependencies is established by using (within the applications and databases) real-time timestamps to identify and order events and transactions. The use of optimistic approaches to transaction concurrency control can be undesirable in such situations, as they allow incorrect results for database read operations. Although the incorrectness is detected prior to transaction committal and the corresponding transaction(s) restarted, the impact on the application or entity that submitted the transaction can be too costly. Three transaction concurrency control algorithms are proposed in this dissertation. These algorithms are based on timestamp ordering, and are designed to preserve temporal dependencies existing among data-dependent transactions. The algorithms produce execution schedules that are equivalent to temporally ordered serial schedules, where the temporal order is established by the transactions' start times. The algorithms provide this equivalence while supporting currency to the ...
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A Study of Perceptually Tuned, Wavelet Based, Rate Scalable, Image and Video Compression

A Study of Perceptually Tuned, Wavelet Based, Rate Scalable, Image and Video Compression

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Date: May 2002
Creator: Wei, Ming
Description: In this dissertation, first, we have proposed and implemented a new perceptually tuned wavelet based, rate scalable, and color image encoding/decoding system based on the human perceptual model. It is based on state-of-the-art research on embedded wavelet image compression technique, Contrast Sensitivity Function (CSF) for Human Visual System (HVS) and extends this scheme to handle optimal bit allocation among multiple bands, such as Y, Cb, and Cr. Our experimental image codec shows very exciting results in compression performance and visual quality comparing to the new wavelet based international still image compression standard - JPEG 2000. On the other hand, our codec also shows significant better speed performance and comparable visual quality in comparison to the best codec available in rate scalable color image compression - CSPIHT that is based on Set Partition In Hierarchical Tree (SPIHT) and Karhunen-Loeve Transform (KLT). Secondly, a novel wavelet based interframe compression scheme has been developed and put into practice. It is based on the Flexible Block Wavelet Transform (FBWT) that we have developed. FBWT based interframe compression is very efficient in both compression and speed performance. The compression performance of our video codec is compared with H263+. At the same bit rate, our encoder, ...
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Developing a Test Bed for Interactive Narrative in Virtual Environments

Developing a Test Bed for Interactive Narrative in Virtual Environments

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Date: August 2002
Creator: Mellacheruvu, Krishna
Description: As Virtual Environments (VE) become a more commonly used method of interaction and presentation, supporting users as they navigate and interact with scenarios presented in VE will be a significant issue. A key step in understanding the needs of users in these situations will be observing them perform representative tasks in a fully developed environment. In this paper, we describe the development of a test bed for interactive narrative in a virtual environment. The test bed was specifically developed to present multiple, simultaneous sequences of events (scenarios or narratives) and to support user navigation through these scenarios. These capabilities will support the development of multiple users testing scenarios, allowing us to study and better understand the needs of users of narrative VEs.
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Implementation of Scalable Secure Multicasting

Implementation of Scalable Secure Multicasting

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Date: August 2002
Creator: Vellanki, Ramakrishnaprasad
Description: A large number of applications like multi-player games, video conferencing, chat groups and network management are presently based on multicast communication. As the group communication model is being deployed for mainstream use, it is critical to provide security mechanisms that facilitate confidentiality, authenticity and integrity in group communications. Providing security in multicast communication requires addressing the problem of scalability in group key distribution. Scalability is a concern in group communication due to group membership dynamics. Joining and leaving of members requires the distribution of a new session key to all the existing members of the group. The two approaches to key management namely centralized and distributed approaches are reviewed. A hybrid solution is then provided, which represents a improved scalable and robust approach for a secure multicast framework. This framework then is implemented in an example application of a multicast news service.
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Performance Evaluation of MPLS on Quality of Service in Voice Over IP (VoIP) Networks

Performance Evaluation of MPLS on Quality of Service in Voice Over IP (VoIP) Networks

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Date: December 2002
Creator: Chetty, Sharath
Description: The transmission of voice data over Internet Protocol (IP) networks is rapidly gaining acceptance in the field of networking. The major voice transmissions in the IP networks are involved in Internet telephony, which is also known as IP telephony or Voice Over IP (VoIP). VoIP is undergoing many enhancements to provide the end users with same quality as in the public switched telephone networks (PSTN). These enhancements are mostly required in quality of service (QoS) for the transmission of voice data over the IP networks. As with recent developments in the networking field, various protocols came into market to provide the QoS in IP networks - of them, multi protocol label switching (MPLS) is the most reliable and upcoming protocol for working on QoS. The problem of the thesis is to develop an IP-based virtual network, with end hosts and routers, implement MPLS on the network, and analyze its QoS for voice data transmission.
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A Quality of Service Aware Protocol for Power Conservation in Wireless Ad Hoc and Mobile Networks

A Quality of Service Aware Protocol for Power Conservation in Wireless Ad Hoc and Mobile Networks

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Date: December 2002
Creator: Gangidi, Murali
Description: Power consumption is an important issue for mobile computers since they rely on the short life of batteries. Conservation techniques are commonly used in hardware design of such systems but network interface is a significant consumer of power, which needs considerable research to be devoted towards designing a low-power design network protocol stack. Due to the dynamic nature of wireless networks, adaptations are necessary to achieve energy efficiency and a reasonable quality of service. This paper presents the application of energy-efficient techniques to each layer in the network protocol stack and a feedback is provided depending on the performance of this new design. And also a comparison of two existing MAC protocols is done showing a better suitability of E2MAC for higher power conservation. Multimedia applications can achieve an optimal performance if they are aware of the characteristics of the wireless link. Relying on the underlying operating system software and communication protocols to hide the anomalies of wireless channel needs efficient energy consumption methodology and fair quality of service like E2MAC. This report also focuses on some of the various concerns of energy efficiency in wireless communication and also looks into the definition of seven layers as defined by International ...
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Implementation of Back Up Host in TCP/IP

Implementation of Back Up Host in TCP/IP

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Date: December 2002
Creator: Golla,Mohan
Description: This problem in lieu thesis is considering a TCP client H1 making a connection to distant server S and is downloading a file. In the midst of the downloading, if H1 crashes, the TCP connection from H1 to S is lost. In the future, if H1 restarts, the TCP connection from H1 to S will be reestablished and the file will be downloaded again. This cannot happen until host H1 restarts. Now consider a situation where there is a standby host H2 for the host H1. H1 and H2 monitor the health of each other by heartbeat messages (like SCTP). If H2 detects the failure of H1, then H2 takes over. This implies that all resources assigned to H1 are now reassigned or taken over by H2. The host H1 and H2 transmit data between each other when any one of it crashed. Throughout the data transmission process, heart beat chunk is exchanged between the hosts when one of the host crashes. In particular, the IP addresses that were originally assigned to H1 are assigned to H2. In this scenario, movement of the TCP connection between H1 and S to a connection between H2 and S without disrupting the TCP ...
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Server load balancing.

Server load balancing.

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Date: December 2002
Creator: Kanuri, Jaichandra
Description: Server load balancing technology has obtained much attention as much business proceeded towards e-commerce. The idea behind is to have set of clustered servers that share the load as against a single server to achieve better performance and throughput. In this problem in lieu of thesis, I propose and evaluate an implementation of a prototype scalable server. The prototype consists of a load-balanced cluster of hosts that collectively accept and service TCP connections. The host IP addresses are advertised using the Round Robin DNS technique, allowing any host to receive requests from any client. Once a client attempts to establish a TCP connection with one of the hosts, a decision is made as to whether or not the connection should be redirected to a different host namely, the host with the lowest number of established connections. This problem in lieu of thesis outlines the history of load balancing, various options available today and finally approach for implementing the prototype and the corresponding findings.
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Ensuring Authenticity and Integrity of Critical Information Using XML Digital Signatures

Ensuring Authenticity and Integrity of Critical Information Using XML Digital Signatures

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Date: December 2002
Creator: Korivi, Arjun
Description: It has been noticed in the past five years that the Internet use has been troubled by the lack of sufficient security and a legal framework to enable electronic commerce to flourish. Despite these shortcomings, governments, businesses and individuals are using the Internet more often as an inexpensive and ubiquitous means to disseminate and obtain information, goods and services. The Internet is insecure -- potentially millions of people have access, and "hackers" can intercept anything traveling over the wire. There is no way to make it a secure environment; it is, after all, a public network, hence the availability and affordability. In order for it to serve our purposes as a vehicle for legally binding transactions, efforts must be directed at securing the message itself, as opposed to the transport mechanism. Digital signatures have been evolved in the recent years as the best tool for ensuring the authenticity and integrity of critical information in the so called "paperless office". A model using XML digital signatures is developed and the level of security provided by this model in the real world scenario is outlined.
Contributing Partner: UNT Libraries
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