2010
Thesis concluded in 2010
49th Doctorate Thesis
Author:
Wagner Rodrigo Weinert
Title:
Evolutionary Computation to Rules Induction of Multidimensional Cellular Automata
Supervisor:
Prof. Heitor Silvério Lopes, Dr.
Area:
Applied Computer Science
Abstract:
A cellular automata is a discrete dynamic system that evolves thought interactions of rules and can be applied to solve several complex problems. The task to find the transition rule to solve a problem can be generalized as a problem of rule induction for cellular automata. Several approaches, based on evolutionary computation techniques, have been proposed to solve this problem. However, there is no generic methodology capable of being applied to a large range of problems. The main contribution of this work is a generic methodology for rule induction for cellular automata. This research was done in four steps to achieve this objective. In the first step we evaluated the performance of some dynamic behavior forecasting parameters calculated as function of a transition rule. The obtained results indicated that those parameters can be used in a careful way. This is due to the possibility of obtaining valid, but insatisfactory solutions. We stress the importance of considering reference parameters, which for the majority of real problems, are not available. In the second research step we proposed a new method to forecast the dynamic behavior. This method considers the transition rule and the initial configuration of the cellular automata. We used the qualitative dynamic behavior patterns described by Wolfram as reference to the forecast. This method was efficient for null behavior rules. Since the process of dynamic simulation can have a high computational cost, we developed a third methodology: an architecture based on the concept of hardware/software co-design to accelerate the processing time. This architecture implements the evolution of cellular automata using reconfigurable logic and was able to decrease hundreds of times the processing time. In the fourth step we developed a new parallel architecture based on the master-slave paradigm. In this paradigm, the master process implements the evolutionary algorithm and a set of slaves processes divide the task of validating the obtained rules. The system runs in a cluster with 120 processing cores connected by a local area network. The co-evolutionary strategy based on an insular model allowed the search for high quality solutions. The generic system implemented over a parallel environment was able to solve the problems proposed. A task distribution analyses among several processors emphasized the benefits of parallel processing. The experiments also indicated a set of reference parameters that can be used to configure the system. The contributions of this work were theoretical and methodological. The former refers to the evaluations done and the different methods for dynamic behavior forecasting parameters. The latter is about the development of two architectures for processing.
Keywords:
cellular automata, evolutionary computation, dynamic behavior, reconfigurable logic, parallel computing.
Exam date:
February 8th, 2010
Download
[pdf] Portuguese version only
| 50th Doctorate Thesis | |
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| Author: |
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| Title: | |
| Supervisor: |
Prof. , Dr. |
| Area: |
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| Abstract: |
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| Keywords: |
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| Exam date: |
2010 |
| Download |
[pdf] Portuguese version only |
| 51st Doctorate Thesis | |
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| Author: |
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| Title: | |
| Supervisor: |
Prof. , Dr. |
| Area: |
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| Abstract: |
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| Keywords: |
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| Vica voce exam: |
2010 |
| Download |
[pdf] Portuguese version only |
| 52nd Doctorate Thesis | |
|---|---|
| Author: |
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| Title: | |
| Supervisor: |
Prof. , Dr. |
| Area: |
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| Abstract: |
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| Keywords: |
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| Vica voce exam: |
2010 |
| Download |
[pdf] Portuguese version only |
| 53rd Doctorate Thesis | |
|---|---|
| Author: |
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| Title: | |
| Supervisor: |
Prof. , Dr. |
| Area: |
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| Abstract: |
. |
| Keywords: |
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| Vica voce exam: |
2010 |
| Download |
[pdf] Portuguese version only |
| 54th Doctorate Thesis | |
|---|---|
| Author: |
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| Title: | |
| Supervisor: |
Prof. , Dr. |
| Area: |
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| Abstract: |
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| Keywords: |
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| Vica voce exam: |
2010 |
| Download |
[pdf] Portuguese version only |
| 55th Doctorate Thesis | |
|---|---|
| Author: |
Ricardo Carvalho Pereira |
| Title: | Proposals of Cognitive Radio Models to Improve Wireless System Capacity |
| Supervisor: |
Prof. , Dr. Richard Demo Souza |
| Area: |
Telematics |
| Abstract: |
This work presents the application of the overlay and underlay cognitive radio models in two distinct wireless networks, constrained by self interference with the goal of improving network capacity. The overlay model was applied in a WMN (Wireless Mesh Network) in order to allow concurrent transmissions within the same interference region with a slightly node throughput degradation, but with a significant overall network capacity improvement. The underlay model was applied in order to introduce a new independent wireless network within the region of a primary wireless network and using a fraction of the primary frequency band as common frequency for both networks. In this case, the network capacity improvement is regarding the introduction of a new network without interfering with the primary system performance. Other modern wireless communications techniques were employed along with cognitive radio concept to achieve the final results presented here such as superposition and dirty paper coding, orthogonal antenna beamforming and dinamic radio resources scheduling. |
| Keywords: |
Cognitive Radio, Wireless Network, Wireless Mesh Network, Superposition Coding, Dirty Paper Coding, Beamforming Antennas. |
| Vica voce exam: |
June 1st, 2010 |
| Download |
[pdf] Portuguese version only |
