DIVE on the internet

This dissertation reports research and development of a platform for Collaborative Virtual Environments (CVEs). It has particularly focused on two major challenges: supporting the rapid development of scalable applications and easing their deployment on the Internet. This work employs a research method based on prototyping and refinement and promotes the use of this method for application development. A number of the solutions herein are in line with other CVE systems. One of the strengths of this work consists in a global approach to the issues raised by CVEs and the recognition that such complex problems are best tackled using a multi-disciplinary approach that understands both user and system requirements. CVE application deployment is aided by an overlay network that is able to complement any IP multicast infrastructure in place. Apart from complementing a weakly deployed worldwide multicast, this infrastructure provides for a certain degree of introspection, remote controlling and visualisation. As such, it forms an important aid in assessing the scalability of running applications. This scalability is further facilitated by specialised object distribution algorithms and an open framework for the implementation of novel partitioning techniques. CVE application development is eased by a scripting language, which enables rapid development and favours experimentation. This scripting language interfaces many aspects of the system and enables the prototyping of distribution-related components as well as user interfaces. It is the key construct of a distributed environment to which components, written in different languages, connect and onto which they operate in a network abstracted manner. The solutions proposed are exemplified and strengthened by three collaborative applications. The Dive room system is a virtual environment modelled after the room metaphor and supporting asynchronous and synchronous cooperative work. WebPath is a companion application to a Web browser that seeks to make the current history of page visits more visible and usable. Finally, the London travel demonstrator supports travellers by providing an environment where they can explore the city, utilise group collaboration facilities, rehearse particular journeys and access tourist information data

Faculty Publications and Creative Works 1997

One of the ways we recognize our faculty at the University of New Mexico is through this annual publication which highlights our faculty\u27s scholarly and creative activities and achievements and serves as a compendium of UNM faculty efforts during the 1997 calendar year. Faculty Publications and Creative Works strives to illustrate the depth and breadth of research activities performed throughout our University\u27s laboratories, studios and classrooms. We believe that the communication of individual research is a significant method of sharing concepts and thoughts and ultimately inspiring the birth of new of ideas. In support of this, UNM faculty during 1997 produced over 2,770 works, including 2,398 scholarly papers and articles, 72 books, 63 book chapters, 82 reviews, 151 creative works and 4 patents. We are proud of the accomplishments of our faculty which are in part reflected in this book, which illustrates the diversity of intellectual pursuits in support of research and education at the University of New Mexico. Nasir Ahmed Interim Associate Provost for Research and Dean of Graduate Studie

The design and performance evaluation of a proactive multipath routing protocol for mobile ad hoc networks

Due to unpredictable network topology changes, routing in Mobile Ad Hoc Networks (MANET) is an important and challenging research area. The routing protocol should detect and maintain a good route(s) between source and destination nodes in these dynamic networks. Many routing protocols have been proposed for mobile ad hoc networks, and none can be considered as the best under all conditions. This thesis presents the design and implementation of a new proactive multipath MANET routing protocol. The protocol, named Multipath Destination Sequenced Distance Vector (MDSDV), is based on the well known single path Destination Sequenced Distance Vector (DSDV). We show that the protocol finds node-disjoint paths, i.e., paths which do not have any nodes in common, except for the source and the destination. The thesis presents a systematic evaluation of MDSDV in comparison with three well known protocols: one proactive (DSDV), and two reactive (AODV) and (DSR). MDSDV behaves very well in terms of its packet delivery fraction and data dropped in both static and dynamic networks. It delivers nearly 100% of data in dense networks (networks with more than 20 nodes). The speed of the nodes and the number of sources have a low impact on its performance

An Annotated Bibliography of Mobile Agents in Networks

The purpose of this thesis is to present a comprehensive colligation of applications of mobile agents in networks, and provide a baseline association of these systems. This work has been motivated by the fact that mobile agent systems have been deemed proficuous alternatives in system applications. Several mobile agent systems have been developed to provide scalable and cogent solutions in network-centric applications. This thesis examines some existing mobile agent systems in core networking areas, in particular, those of network and resource management, routing, and the provision of fault tolerance and security. The inherent features of these systems are discussed with respect to their specific functionalities. The applicability and efficacy of mobile agents are further considered in the specific areas mentioned above. Although an initial foray into a collation of this nature, the goal of this annotated bibliography is to provide a generic referential view of mobile agent systems in network applications

Μηχανική Μάθηση στην Επεξεργασία Φυσικής Γλώσσας

Η διατριβή εξετάζει την χρήση τεχνικών μηχανικής μάθησης σε διάφορα στάδια της επεξεργασίας φυσικής γλώσσας, κυρίως για σκοπούς εξαγωγής πληροφορίας από κείμενα. Στόχος είναι τόσο η βελτίωση της προσαρμοστικότητας των συστημάτων εξαγωγής πληροφορίας σε νέες θεματικές περιοχές (ή ακόμα και γλώσσες), όσο και η επίτευξη καλύτερης απόδοσης χρησιμοποιώντας όσο το δυνατό λιγότερους πόρους (τόσο γλωσσικούς όσο και ανθρώπινους). Η διατριβή κινείται σε δύο κύριους άξονες: α) την έρευνα και αποτίμηση υπαρχόντων αλγορίθμων μηχανικής μάθησης κυρίως στα στάδια της προ-επεξεργασίας (όπως η αναγνώριση μερών του λόγου) και της αναγνώρισης ονομάτων οντοτήτων, και β) τη δημιουργία ενός νέου αλγορίθμου μηχανικής μάθησης και αποτίμησής του, τόσο σε συνθετικά δεδομένα, όσο και σε πραγματικά δεδομένα από το στάδιο της εξαγωγής σχέσεων μεταξύ ονομάτων οντοτήτων. Ο νέος αλγόριθμος μηχανικής μάθησης ανήκει στην κατηγορία της επαγωγικής εξαγωγής γραμματικών, και εξάγει γραμματικές ανεξάρτητες από τα συμφραζόμενα χρησιμοποιώντας μόνο θετικά παραδείγματα.This thesis examines the use of machine learning techniques in various tasks of natural language processing, mainly for the task of information extraction from texts. The objectives are the improvement of adaptability of information extraction systems to new thematic domains (or even languages), and the improvement of their performance using as fewer resources (either linguistic or human) as possible. This thesis has examined two main axes: a) the research and assessment of existing algorithms of machine learning mainly in the stages of linguistic pre-processing (such as part of speech tagging) and named-entity recognition, and b) the creation of a new machine learning algorithm and its assessment on synthetic data, as well as in real world data from the task of relation extraction between named entities. This new algorithm belongs to the category of inductive grammar learning, and can infer context free grammars from positive examples only