| 1. |
- Abu-Hamam, Anas, 1977-, et al.
(författare)
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Understanding Web Users Behaviour From A Web Video Camera
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- To develop a Real-Time system, which can capture and track the web user’s head motion. Based on the head motion information, the system should be able to identify whether the user is interested in the current homepage or not. A future system property would be to find out in which area of the homepage the user’s interest is moving.
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| 2. |
- Georgakis, Apostolos A., 1975-
(författare)
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Textual information retrieval : An approach based on language modeling and neural networks
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis covers topics relevant to information organization and retrieval. The main objective of the work is to provide algorithms that can elevate the recall-precision performance of retrieval tasks in a wide range of applications ranging from document organization and retrieval to web-document pre-fetching and finally clustering of documents based on novel encoding techniques.The first part of the thesis deals with the concept of document organization and retrieval using unsupervised neural networks, namely the self-organizing map, and statistical encoding methods for representing the available documents into numerical vectors. The objective of this section is to introduce a set of novel variants of the self-organizing map algorithm that addresses certain shortcomings of the original algorithm.In the second part of the thesis the latencies perceived by users surfing the Internet are shortened with the usage of a novel transparent and speculative pre-fetching algorithm. The proposed algorithm relies on a model of behaviour for the user browsing the Internet and predicts his future actions when surfing the Internet. In modeling the users behaviour the algorithm relies on the contextual statistics of the web pages visited by the user.Finally, the last chapter of the thesis provides preliminary theoretical results along with a general framework on the current and future scientific work. The chapter describes the usage of the Zipf distribution for document organization and the usage of the adaboosting algorithm for the elevation of the performance of pre-fetching algorithms.
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| 3. |
- Georgakis, Apostolos, 1975-, et al.
(författare)
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Document distances using the Zipf distribution and a novel metric
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A novel metric is proposed in the present report for the evaluation of the goodness-of-fit criterion between the distribution functions of two samples. We extend the usage of the proposed criterion for the case of the generalized Zipf distribution. Detailed mathematical analysis of the proposed metric, which is embodied in a hypothesis testing, is also provided.
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| 4. |
- Georgakis, Apostolos, 1975-, et al.
(författare)
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Spread spectrum wavelet watermarking system
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Lately attention has been focused on wavelet-based watermarking because of its compatibility with the newly developed JPEG 2000 image compression scheme. The major setback associated with wavelet-based watermarking is its vulnerability to geometric distortion caused by the lack of invariance property of wavelet transform. The domain of digital watermarking focused on spread spectrum based technique because of its excellent antijamming feature in wireless communication. However existing digital watermarking systems based on spread spectrum technique are yet to replay the anti-jamming feature in wireless communication, hence have not yielded the desired fully robust characteristics. Existing geometric invariant spread spectrum watermarking systems are complex, difficult to implement and unreliable. In our view this is due to inability of researchers to faithfully implement spread spectrum principle. Our investigation showed that most spread spectrum based watermarking faithfully implement the embedding process but fail to despread the signal before detection as required in a typical wireless spread spectrum communication. In this project we propose a simple spread spectrum wavelet watermarking system that is secure, tuneable and fully robust to all known forms and severities of attacks. The novel feature of our watermarking system design is its model as a communication system with the original (host) image representing the communication channel, the watermark represent the message (base band) signal and the legal and malicious attacks represent the noise, interference or jamming of the message signal. Experimental results from our system showed a replay of the excellent anti-jamming feature of spread spectrum communication technique and confirm the superior performance of our system over existing correlation-based spread spectrum wavelet watermarking system.
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| 5. |
- Georgakis, Apostolos, 1975-, et al.
(författare)
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Web prefetching through automatic categorization
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The present report provides a novel transparent and speculative algorithm for content based web page prefetching. The proposed algorithm relies on a user profile that is dynamically generated when the user is browsing the Internet and is updated over time. The objective is to reduce the user perceived latency by anticipating future actions. In doing so the adaboost algorithm is used in order to automatically annotate the outbound links of a page to a predefined set of “labels”. Afterwards, the links that correspond to labels relevant to the user’s preferences are pre-fetched in an effort to reduce the perceived latency when the user is surfing the Internet. A comparison between the proposed algorithm against two other pre-fetching algorithms yield improved cache-hit rates given a moderate bandwidth overhead.
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| 6. |
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