Theses and Dissertations

2006

ABSTRACTS

Departmento de Informática 
Pontifícia Universidade Católica do Rio de Janeiro - PUC-Rio
Rio de Janeiro - Brazil
 

This file contains the list of the MSc. Dissertations and PhD. Thesis presented to the Departmento de Informática, Pontifcia Universidade Católica do Janeiro - PUC-Rio, Brazil, in 2006.  They are all available in  print format and, according to the authors' preference, some of them are freely available for download, while others are freely available for download to the PUC-Rio community exclusively(*). 

For any requests, questions, or suggestions, please contact:
Rosane Castilho bib-di@inf.puc-rio.br

Last update: 29/DECEMBER/2006
 

INDEX

[06_PhD_medeiros]
Adriana Pereira de MEDEIROS. Kuaba: uma abordagem para representação de Design Rationale para o reúso de designs baseados em modelo. [Title in English: Kuaba: an approach for the representation of design rationale for reuse in model-based designs]  Ph.D. Thesis. Port. Presentation: 31/03/06 149 p. Advisor: Daniel Schwabe.

Abstract: This work presents a knowledge representation model and the conceptual architecture of an integrated design environment to support recording design rationale, as well as use of design rationale, during design of software artifacts. In our representation approach, we propose the use of the formal semantics of artifacts provided by design methods to represent design rationale using the vocabulary defined in the Kuaba ontology. This vocabulary described in a formal ontologies specification language allows defining a set of rules and computable operations that support the reuse of designs in the production of new software artifacts.  This representation approach enables a type of software design reuse at the highest abstraction level, where rationales can be integrated and re-employed in designing a new artifact.
 

[06_PhD_santos]*
Andréa Cynthia dos SANTOS. Modelos e algoritmos para o problema da árvore geradora de custo mínimo com restrição de diâmetro. [Title in English: Models and algorithms for the diameter constrained minimum spanning tree problem]  Ph.D. Thesis. Port. Presentation: 12/06/2006  133 p. Advisor: Celso da Cruz Carneiro Ribeiro.

Abstract: In this work, models and approximation algorithms to solve the Diameter Constrained Minimum Spanning Tree Problem (AGMD) are proposed. This problem typically models network design applications where all vertices must communicate with each other at a minimum cost, while meeting a given quality requirement. The formulations proposed by Achuthan and Caccetta are strengthened with valid inequalities. A lagrangean relaxation is proposed
for the multicommodity flow model developed by Gouveia and Magnanti. Adaptations are made in the constructive heuristics proposed by Deo and Abdalla and by Raidl and Julstrom. Four local search procedures, a GRASP algorithm and a hybrid heuristic are proposed. Upper bounds within 2% of the optimal solution values are obtained for the two classes of instances used by Gouveia and Magnanti and by Santos, Lucena and Ribeiro. Moreover, stronger upper bounds are reported for 11 instances in complete graphs used by Raidl, Julstrom and Gruber.

[06_PhD_albuquerque]
Antonia Lucinelma Pessoa ALBUQUERQUE. Um modelo para visualização estereoscópica utilizando webcams. [Title in English: A model for stereoscopic visualization through webcams]  Ph.D. Thesis. Port. Presentation: 01/09/2006   130 p. Advisor: Rubens Nascimento Melo.

Abstract: The improviment of communication among remotely located people constitutes a very comprehensive prominent subject nowadays. Among applications to attain this goal, some aim to support social and personal
interactions to meet partners, friends and family in distance. Presence research results, some obtained as part of this thesis, allowed to infer the four pillars of the proposal: 1. visualization is very important in social/personal interactions, mainly when people have close social/personal relationship; 2. simple technology can afford social presence; 3. camera images are more satisfactory than avatars during some social/personal interactions; 4. stereoscopy influences presence positively. Under the constraint of using simple technology without adding any special hardware to a PC system, the thesis proposes the use of stereoscopy through webcams, in real-time, as one solution to add 3D features to camera images. Since webcams are simple equipments with low resolution, to obtain stereo images in good quality is a challenge. Considering the fact that human eyes treat short and long distance in a different way, this research analysed the natural stereo processing of human eye, and based on psychophysical features of binocular vision, the thesis proposes a model to process stereoscopic images to be visualized in short distance, and implemented it as a proof of concept. The obtained results are satisfactory for stereoscopic images
visualization through webcams, in real-time, and mainly, eliminated the need of adjusting images parallax and cameras position for each viewer's movement, allowing more freedom to the viewer.

[06_PhD_vieira]
Carlos Eduardo Costa VIEIRA. Heurísticas para o problema das p-medianas conectadas. [Title in English: Heuristics for the connected p-median problem]  Ph.D. Thesis. Port. Presentation: 11/09/2006  191 p. Advisor: Sérgio Lifschitz.

Abstract: In this work, the connected p-median and the connected facility location problems are defined. Applications arise in regional planning,design of telecommunications and transportation networks. For the first
problem, two integer linear programming formulations are proposed. Adaptations are made in one of these formulations and are used to model the second problem. Approximation algorithms to solve the connected p-median problem are developed. A hybrid local search strategy is proposed. In order to speed up the local search iterations, ideas as circularity, first-improving strategy and discard neighbors are incorporated. A GRASP algorithm and a
VNS heuristic are also proposed. A filter is used to reduce the computational time required and a path-relinking is applied to improve the results found. Computational experiments to compare the algorithms are reported. To improve these results, it is applied a post-optimization step to the GRASP and VNS heuristics.

[06_MSc_barretojunior]
Celso Gomes BARRETO JUNIOR. Agregando frameworks de infra-estrutura em uma arquitetura baseada em componentes: um estudo de caso no ambiente AulaNet. [Title in English: Adding system intrastructure frameworks in a component based architecture: a case study within the AulaNet environment]  M.Sc. Diss. Port. Presentation: 14/03/06 210 p. Advisor: Hugo Fuks.

Abstract: Groupware is difficult to develop and maintain becase it involves multidisciplinary aspects in its construction. Besides the difficulties related to the development of collaborative applications, usually the developer must handle with other infrastructure aspects. In this dissertation, it is proposed a multilayer component based architecture with system infrastructure frameworks to deal with them. In the business layer, the Hibernate framework is responsible for the persistence of application data, and the Spring framework is responsible for, amongst others, transactions control and remote exposition of services. In the presentation layer the JaveServer Faces framework provides ways to create and to reuse user-interface components. This dissertation also presents a way to compare system infrastructure frameworks, considering both technical aspects, related to the application requirements fulfillment, and non-technical, related to aspects such as documentation availability and market acceptance. The architecture defined in this dissertation is applied to the AulaNet, wich is a groupware for learning developed in the Software Engineering Laboratory of PUC-Rio.

[06_PhD_barbosa]
Clarissa Maria de Almeida BARBOSA. Manas - uma ferramenta epistêmica de apoio ao projeto de comunicação de sistemas colaborativos. [Title in English: Manas – an epistemic tool to support the design of communication in collaborative systems]  Ph.D. Thesis. Port. Presentation: 05/05/2006  222 p. Advisors: Clarisse Sieckenius de Souza and Raquel Oliveira Prates.

Abstract: Collaborative systems (SiCos) support or enable human interaction online; this involves users communicating not only with the system, but also, and mainly, with each other. Theoretical contributions reveal and empirical studies illustrate and provide evidence of the influence of SiCos on the communication among users (USU communication), the users' experience, and ultimately on the social activity supported by the system, as well as group dynamics. The effects of SiCos, especially the social effects, call for the development of design tools that help designers make more informed decisions. In this work, we introduce Manas, a Semiotic Engineering epistemic tool that enables designers to represent their USU communication project, and offers them qualitative feedback on the potential social effects of their project on interaction between users and the system as well as among themselves. In doing so, Manas leads designers to reflect upon both the problem being handled and the proposed solution, allowing them to make more conscious decisions. Furthermore, Manas registers the underying rationale in the USU communication project, which is a valuable source of information and study of the design process and its product, and creates favorable conditions for the transmission of this knowledge to users through the system interface. Users will then be able to use the system more efficiently. Thus Manas potentially enhances the quality of SiCos.
 

[06_PhD_mello]
Claudio Gomes MELLO. Codificação livre de prefixo para cripto-compressão. [Title in English: Crypto-compression prefix coding]  Ph.D. Thesis. Port. Presentation: 18/09/2006  110 p. Advisor: Ruy Luiz Milidiú.

Abstract: Data compression and encryption are essential features when digital data stored or transmitted over insecure channels. Usually, we apply two sequential operations: first, we apply data compression to save disk space
and to reduce transmission costs, and second, data encryption to provide confidentiality. This solution works fine for most applications, but we have to execute two expensive operations, and if we want to access data, we must first decipher and then decompress the ciphertext to restore information. In this work we propose algorithms that achieve both compressed and encrypted data. The first contribution of this thesis is the algorithm ADDNULLS - Selective Addition of Nulls. This algorithm uses steganographic technique to hide the real symbols of the encoded text within fake ones. It is based on selective insertion of a variable number of null symbols after the real ones. It is shown that coding and decoding rates loss are small. The disadvantage is ciphertext expansion. The second contribution of this thesis is the algorithm HHC - Homophonic-Canonic Huffman. This algorithm creates a new homophonic tree based upon the original canonical Huffman tree for the input text. It is shown the results of the experiments. Adding security has not significantly decreased performance. The third contribution of this thesis is the algorithm RHUFF - Randomized Huffman. This algorithm is a variant of Huffman codes that defines a crypto-compression algorithm that randomizes output. The goal is to generate random ciphertexts as output to obscure the redundancies in the plaintext (confusion). The algorithm uses homophonic substitution, canonical Huffman codes and a secret key for ciphering. The secret key is based on an initial permutation function, which dissipates the redundancy of the plaintext over the ciphertext (diffusion). The fourth contribution of this thesis is the algorithm HSPC2 - Homophonic Substitution Prefix Codes with 2 homophones. It is proposed a provably secure algorithm by using a homophonic substitution algorithm and a key. In the encoding process, the HSPC2 function appends a one bit suffix to some codes. A secret key and a homophonic rate parameters control this appending. It is shown that breaking HSPC2 is an NP-Complete problem.
 

[06_MSc_marreco]
Daniel Catunda MARRECO. Um processo controlável de desenvolvimento de software focado na gestão da qualidade em pequenos projetos. [Title in English: A controllable software development process for quality management in small enterprises enviroment]  M.Sc. Diss. Port. Presentation: 14/03/06 110 p. Advisor: Arndt von Staa.

Abstract: The following work presents a proposal of software project management methodology applicable to small projects and strongly inspired by already well established methodologies such as the Unified Process and eXtreme Programming. The objective of this proposal is to provide an agile process that is adaptable yet prescriptive. Through this one plans to arrive at a process of easy implementation and control, and less dependent on the technical quality of the development team. Subsequently, a case study will be presented that was conducted in a real environment, on a small enterprise development team. It consists of a report on the maturing and implementation of the proposed process and an analysis of the work of implementing development procedures in emerging enterprises in the IT area.

[06_MSc_steinbruch]
David STEINBRUCH. Um estudo de algoritmos para classificação automática multi-rótulo de textos utilizando Naive-bayes. [Title in English: A study for multilabel text classification algorithms using Naive-bayes]  M.Sc. Diss. Port. Presentation: 05/09/2006 78 p. Advisor: Daniel Schwabe e Ruy Luiz Milidiú.

Abstract: The amount of electronic information has been growing fast, mainly due to the easiness of publication and spreading that Internet provides. Therefore, is necessary the organization of information to facilitate its retrieval. Many works have solved this problem through the automatic text classification, associating to them several labels (multilabel classification). However, those works have transformed this problem into binary classification
subproblems, considering there is not dependence among categories. Moreover, they have used thresholds, which are very specific of the classifier document base, and so, does not have great generalization capacity in the learning
process. This thesis proposed two text classifiers based on the multinomial algorithm naive Bayes and its usage in an on-line text classification environment with user relevance feedback. In order to test the proposed algorithms efficiency, experiments have been performed on the Reuters 21578 news base, and on the Ohsumed medical document base.

[06_PhD_silva]
Diva de Souza e SILVA. Modelagem de composição de objetos de aprendizagem. [Title in English: Modeling of learning objects composition]  Ph.D. Thesis. Port. Presentation: 11/01/06 117 p. Advisors: Rubens Nascimento Melo, Maria Helena Lima Baptista Braz and Sean Wolfgan Matsui Siqueira.

Abstract: The development of instructional content using new Information Technologies is an expensive, time-consuming and complex process that leads to the development of new methodologies. It was in this context that the concept of Learning Objects (LOs) was proposed as an approach that promotes content reuse. However, if content is expressed as small LOs, it is also necessary to sequence them in order to build more elaborated and complex content. In this thesis we adopt a strategy to represent smaller LOs, modeling not only content but also practice, called Component Objects (COs) herein. In order to structure content we adapted an existing proposal and defined a conceptual schema to structure learning practices (or activities).  We also defined a conceptual schema for composing these COs. Then, based on these conceptual schemas it was possible to propose an algorithm for sequencing COs,  which supports a teacher/professor to better control the implementation of a complex content such as a class or a course, thus reducing errors and eventual omissions in its implementation. The sequencing process must follow a methodology and must be specified in a non-ambiguous way. It is in this context that we also present a specification language for sequences of LOs, with a syntax that is adequate to the description of the possible ways of sequencing LOs. Finally, we describe a case study that shows the conceptual schemas that were proposed and the use of the sequencing algorithm and the specification language.


[06_MSc_figueiredo]
Eduardo Magno Lages FIGUEIREDO. Uma abordagem quantitativa para desenvolvimento de software orientado a aspectos. [Title in English: A quantitative approach to aspect oriented software development]  M.Sc. Diss. Port. Presentation: 29/03/06 140 p. Advisors: Carlos José Pereira de Lucena and Alessandro Fabrício Garcia.

Abstract: Aspect-oriented software development is an emerging paradigm that provides new abstractions and mechanisms to support the modularization of crosscutting concerns through the software development lifecycle. However, the achievement of high-quality aspect-oriented software is not trivial. The inappropriate use of aspect-oriented abstractions and mechanisms potentially leads to the violation of important design principles, such as low coupling, high cohesion, incomplete modularization of crosscutting concerns into aspects, and so forth. These problems are not easily detectable and an ad hoc analysis of large designs and implementations is often expensive
and time-consuming. Hence there is a need for an assessment method that assists software engineers in the analysis of their aspect-oriented implementations. This work proposes the development of a systematic approach to support the quantitative assessment of aspect-oriented software. The approach is organized in a stepwise fashion and is founded on a metrics suite and a comprehensive set of complementary rules. Our proposal is supported by a measurement and assessment tool. A set of five case studies from different application domains have been carried out in order to evaluate the usability and usefulness of our proposed approach.


[06_MSc_morelli]
Eduardo Maria Terra MORELLI. Recriação automática de índices em um SGBD relacional. M.Sc. Diss. Port. Presentation: 19/09/06 120 p. Advisor: Sergio Lifschitz

Abstract: One of the most important tasks of Database Administrators is certainly to guarantee optimal response times to statements submitted by users of big RDBMS. Our dissertation deals with Index Self-tuning, which means creating, dropping or recreating indexes automatically, in order to decrease SQL queries durations. We start from Marcos Salles' dissertation (2004), which proposed an automatic way of creating indexes. We extend it in many ways: first using a different workload, TPC-H like. Second, following created indexes inspecting its usage. Finally, we have gotten to drop and, mostly, recreate indexes using different fillfactor in leaf pages. Also, we have elaborated many tests using commercial tools, Microsoft SQL Server 2005 and Oracle 10g in order to ratify Marcos Salles' ideas. Unfortunatelly, we could not test automatic dropping and recreating in these tools, as long as they do not offer this kind of functionalities. Unlike related work and commercial tools, we have created a code prototype that not only suggests new indexes creations, but also drops and recreates indexes using an own heuristics. To validate our ideas we have used a TPC-C like workload, but we had to make some changes to increase updates and force reindexing.


[06_PhD_russo]
Ênio Emanuel Ramos RUSSO. Um metamodelo para configuração de espaços de trabalho virtuais colaborativos: aplicação no gerenciamento de desastres de estruturas offshore de Óleo e Gás. [Title in English: A metamodel for collaborative workspaces configuration: application in disaster management of Oil & Gas offshore structures]  Ph.D. Thesis. Port. Presentation: 27/03/06 222 p. Advisors: Marcelo Gattass, Terrence Fernando and Alberto Barbosa Raposo.

Abstract: Many companies have been creating virtual teams that bring together geographically dispersed workers with complementary skills, increasing the demand for CSCW (Computer Supported Cooperative Work) applications. In order to facilitate the development of a wide range of these collaborative applications, we should offer a general architecture that is adaptable to different situations, tasks, and settings in a flexible way. This work investigates how a distributed workspace environment can support disaster management, involving distributed collaborative technical teams. We first identify the requirements for the distributed workspace, from the stakeholders involved in a disaster, and analyse the commercial emergency systems available. We then elaborate a multi-perspective metamodel to support configuring this collaborative virtual workspace. Finally a prototype for oil and gas offshore structures disaster management based on our multi- perspective metamodel is derived and an HLA (High Level Architecture) compliant implementation for this prototype is developed as a proof- of-concept of the metamodel.


[06_MSc_marques]
Fábio Seixas MARQUES. Um processo baseado em MDA para a especialização de mecanismos de persistência. [Title in English: A process based on MDA for specialization of persistence mechanisms]  M.Sc. Diss. Port. Presentation: 10/04/06  88 p. Advisor: Carlos José Pereira de Lucena and Ivan Mathias Filho.

Abstract: According to the changes on functional and non-functional requirements on application field, there is a great need for softwares to adapt themselves to these changes. Due to it, the process involved on this work has the purpose of automate some parts of applications' developments, reducing the manual work needed to adapt the software systems to the need of constant changes determined by business world's reality. The approach Model Driven Architecture (MDA), defined by OMG, was used as base for this process, having as main goal the transformation of models; i mean, generate from an platform independent model, one or more platform specific models. The process suggested is divided according to the MDA steps, having as a goal the support of generate models steps and on the adaptation of Persistence Frameworks. It was used on the suggested process, the concept
of base of knowledge, having as main goal map the informations held within the model transformation rules to be done on these models. These rules are responsible by the definition of changes to be done on platform-independent
models aiming to include a specific Persistence Framework in an application. The language RDL was used to formalize the transformation rules used in the process, making the development and maintenance of themselves easy the process has as a result a platform-specific model, also a Persistence Framework adapted to the architecture used. Some configuration files also are generated, intending to reduce the manual work.


[06_MSc_moura]
Francisco Eduardo Torres Cursino de MOURA. Uma proposta para rendering baseado em imagens em celulares. [Title in English: A proposal for image based rendering in cellphones]  M.Sc. Diss. Port. Presentation: 22/09/2006  p. Advisor: Bruno Feijó.

Abstract: Image Based Rendering (IBR) is a strong tendence in visualization due to the high quality of the images. One of the most complex problems is the 2D/3D object composition in a panorama. The use of IBR in limited platforms, like cell phones, faces a number of problems and the literature is scarse. This work analizes the possibility of implementing IBR with active objects in cell phones. A prototype is presented and results are analyzed. .


[06_MSc_guimaraes]
Frederico Silva GUIMARÃES. Um sistema multi-agentes para monitoramento e aquisição em tempo real. [Title in English: A multi-agent system for real time monitoring and data acquisition]  M.Sc. Diss. Port. Presentation: 05/04/06 93 p. Advisor: Carlos José Pereira de Lucena

Abstract: Supervisory systems allied to embedded software, a common subject in the literature, are responsible by the supervision of equipments like industrial machines, household-electric devices, cellular phones and PDAs. Many of them have severe requisites of fault tolerance and reliability as well as real time systems features. This research investigates the use of state-of-the-art technologies such as Design By Contract, Mock Objects, software agents and components in the development of real-time monitoring and data-acquisiton systems. Recovery oriented systems concepts are also explored. The case study carried out to the research is a pipeline inspection software system, which uses such technologies. In a nutshell, it can be said that this case study showed strong evidence that the use of these technologies allowed the development in a very short time, without any loss of robustness, fault tolerance and reliability. The developed system is currently being used in real pipeline inspections.


[06_MSc_gomes]
Geórgia Regina Rodrigues GOMES. Integrando repositórios de sistemas de bibliotecas digitais e sistemas de gerência de aprendizagem. [Title in English: Integrating repositories of digital library systems and learning management systems]  Ph.D. Thesis. Port. Presentation: 29/09/2006  143 p. Advisor: Rubens Nascimento Melo, Maria Helena Lima Baptista Braz and Sean Wolfgan Matsui Siqueira.

Abstract: With the widespread use of Information Technology for teaching support, it is usual to made digital content available through Digital Library Systems (DLMS) or Learning Management Systems (LMS). These systems, however, work independently, have different characteristics and manipulate different types of materials, and their data and metadata repositories are heterogeneous and distributed. The content of repositories would be better used if it was integrated in the same environment or accessed in an integrated way from DLMS and LMS. This thesis presents a homogeneous view of DLMS and LMS content. In order to provide such homogenization, it is proposed an extension of the mediator and wrapper architecture for dealing with metadata integration and ontologies for treating semantics. Local ontologies are used for describing each metadata repository, and a global ontology for the integration. As documents of DLMS repositories tend to be monolithic and not to follow a reuse approach, rules for extracting the most important content from these documents were developed in order to make them reusable. This extraction includes text mining techniques as well as rules for discovering definitions embedded in the documents. A prototype was developed which implements the extraction and proves the feasibility of this approach. In order to make the work easier to understand, it is presented a case study that uses the proposed technique and the prototype. The work described in this thesis facilitates and enriches the development of learning material by making the content of digital library documents reusable and integrated to exixting learning objects.



[06_MSc_muhammad]
Hisham Hashem MUHAMMAD. Estudo sobre APIs de linguagens de script. [Title in English: A study on APIs for scripting languages]  M.Sc. Diss. Port. Presentation: 28/08/2006 123 p. Advisor: Roberto Ierusalimschy.

Abstract: Applications written in two programming languages, in order to optimize parts where performance is critical or to obtain extensibility through userwritten scripts, are commonplace nowadays. There are several ways to obtain this kind of interoperability; ideally, however, a language should provide a foreign language interface (FLI), allowing the programmer to send and receive both data and function calls to the external language. This work discusses the main issues involving the design of APIs for the integration of language environments within C applications. We present the main problems faced in the interaction between code executed in an environment with inherently dynamic characteristics such as a scripting language and C code. We compare the approaches employed by five languages when handling communication between the data spaces of C and the embedded runtime environment and the consequences of these approaches in memory management, as well as sharing of code between the C application and that from the scripting language. We illustrate the differences of the APIs of those languages and their impact in the resulting code of a C application through a case study. Different scripting languages were embedded as plugins for a library, which on its turn exposes to client applications a generic scripting API. This way, the code of each plugin allows us to observe in a clear and isolated way the procedures adopted by each language for function calls, registration of C functions and conversion of data between the environments.


[06_MSc_rosa]
Janaína Oleinik Moura ROSA. Um estudo de compactação de dados para biossequências. [Title in English: A study of biosequence data compression]  M.Sc. Diss. Port. Presentation: 06/09/2006 135 p. Advisor: Sérgio Lifschitz.

Abstract: The BLAST is the sequence comparison strategy mostly used in computational biology. Therefore, research on data structures, secondary memory access methods and on the algorithm itself, could bring important optimizations and consequently contributions to the area. In this work, we study a NCBI BLAST version by analyzing its data structures and algorithms for data manipulating. In addition, we collect performance data for identifying processing bottleneck in all the BLAST execution phases. Based on this analysis, data compress techniques were applied as a strategy for reducing number of secondary memory access operations. Finally, a modified version of BLAST was implemented in the Microsoft Windows environment, where the program was directly altered. Finally, an analysis was made over using the results of execution of original BLAST against modified BLAST.

[06_MSc_damasceno]
Karla Nazaré Ferreira DAMASCENO.  Tratamento de exceções sensível ao  contexto. [Title in English: Context-sensitive exception handling] M.Sc. Diss. Port. Presentation: 31/03/06 107 p. Advisors: Carlos José Pereira de Lucena and Alessandro Fabricio Garcia.

Abstract: Context-sensitive exception handling on mobile systems is not a trivial task due to their intrinsic characteristics: mobility, asynchrony and increased unpredictability. Conventional mechanisms of exception handling can not be used for many reasons. First, error propagation needs considering the contextual changes that often occur in these systems. Second, error recovery and exception handling strategies also frequently need to be selected according to contextual information. Third, the characterization of an exception may depend on the contextual situation of involved devices. Even though there are now several context-oriented middleware systems that provide support for the development of mobile applications, they rarely provide explicit and adequate features for contextual -sensitive exception handling. This work presents an analysis of existing exception handling mechanisms. which to some extent consider the context-awareness requirements. Besides, it proposes a general model for contex-sensitive exception handling and a supporting mechanism implemented using the MoCA (Mobile Collaboration Architecture) infrastruture. MoCA is a publish-subscribe middleware supporting the development of collaborative mobile applications by incorporating explicit services to empower agents with context-sensitiveness. Finally, this paper reports our experience in implementing context-aware exception handling strategies in some prototype collaborative applications built with the MoCA system.

[06_MSc_cunha]
Leonardo Godinho da CUNHA. Modelos de concorrência e sandboxes aplicados a servidores HTTP em Lua. [Title in English: Concurrency and sandboxes models applied to Lua HTTP servers]  M.Sc. Diss. Port. Presentation: 13/09/2006 137 p. Advisor: Noemi de La Rocque Rodriguez.

Abstract: Client-server developers constantly have to deal with questions concerning performance and scalability, since the number of simultaneous clients can grow significantly. Moreover, if these systems can execute third-party code,there is also the concern of secure execution of these pieces of code. This work goal is to benchmark several combinations of concurrency and sandboxes models. As an example of a system exposed to several concurrent requests that must be able to execute third-party code, we have the web servers. Xavante is a web server developed in the Lua programming language that originally uses an concurrency programming model based on coroutines. This server offers the flexibility to map request types to different handlers. Some of these request handlers dynamically allow the use of third-party code, therefore they make use of sandboxes in order to offer a protected running environment. In this work we test the use of Xavante's native sandboxes and other types of sandboxes. We also improve the extensibility of server, using a different architecture in order to allow different concurrency strategies. Using the new architecture we tested the performance of several combinations of sandboxes and concurrency programming models, allowing the model comparison not only in a qualitative point of view but also measuring the related performance impacts.
 

[06_PhD_cunha]
Leonardo Magela CUNHA.  Um framework de aplicações para a Web Semântica. [Title in English: A Semantic Web application framework] M.Sc. Diss. Port. Presentation: 18/12/06  p. Advisor: Carlos José Pereira de Lucena.

Abstract: Documents have been the main vehicle of the Web until some years ago. With the advent of Web applications, data stored in organizations databases or legacy systems has been made available to users. However, very often, the exchange of data between those applications themselves or between them and end-users applications were not possible since they used different formats for the information representation. The development of standards and the use of the eXtensible Markup Language (XML) solved parts of the problem. That was a syntactic solution and it works for several cases, e.g., schema interoperability in Business-to-Business e-commerce scenarios. Nevertheless, the lack of semantics on these data prevented applications to take more advantage of them. The idea behind the Semantic Web is to define explicitly the semantics of data available on the Web. Therefore, we expect another step forward where applications, being them corporative or for end-users, will understand the meaning of the data available on the Web. Once those applications can understand it, they will be able to help users to take advantage of this data driven Web and to perform their daily tasks easily. This thesis proposes a framework for the development of Semantic Web applications. Considering the scenario described in the previous paragraph, the number of possible applications that can be developed is almost infinite. For this reason, we restricted ourselves to examine the solutions that aim to solve the problem presented at the Semantic Web Challenge; and to propose a framework that represent those solutions. The challenge is concerned in demonstrating how Semantic Web techniques can provide valuable or attractive applications to end users. Our main concern was then to demonstrate and help a developer to achieve that value addition or attractiveness, through Semantic Web techniques, in a Software Engineering approach using frameworks.

[06_MSc_couto]
Leonardo Matriciano COUTO. Sistemas de informação geográfica adaptativos baseados em modelos. [Title in English: Model-driven adaptive geographic information systems]  M.Sc. Diss. Port. Presentation: 30/08/2006 102 p. Advisor: Marco Antonio Casanova and Daniel Schwabe.

Abstract: This dissertation introduces a strategy to develop geographic information systems based on a variant of the Model-View-Controller (MVC) design pattern. The strategy adopts models to reproduce user classes and to
capture additional characteristics of the information classes. The MVC components are modified to implement adaptation mechanisms, which interpret the models. The dissertation also describes an example application designed according to the proposed strategy.

[06_MSc_belmonte]
Leonardo Mendes BELMONTE. Um modelo e um framework de implementação para processamento de conjuntos. [Title in English: A semantic information processing model based on sets]  M.Sc. Diss. Port. Presentation: 04/09/2006  137 p. Advisor: Daniel Schwabe.

Abstract: This dissertation proposes an information processing model based on sets that can be seen as a generalization of the classic model of graphs for hypertexts. This model estimates a semantic model of an application domain, and the sets of objects are defined from this. Information processing tasks that the users should execute, with support of the application, are described as functional compositions of operations applied over the information items and over the defined sets. This model type allows the application construction with interfaces of direct manipulation on items and sets, and includes, among others, the faceted navigation interfaces that are currently found in the Web. In this type of interface, the user builds the functional composition that represents the desired computation in the incremantal form, through the direct manipulation of elements in the interface. This dissertation specifies this model, and presents an implementation in the .Net environment. Beyond the definition of items and sets, it generates a Domain Specific Language (DSL) that allows the direct expression of operations on items and sets. The proposed model, and its implementation, is integrated with a framework for generating direct  manipulation interfaces on sets, that is the focus of another dissertation. A study case is presented, using the model, its implementation and the integration with the interface, illustrating how the approach facilitated different types of tasks that are frequently executed by Web application users.

[06_MSc_lemos]
Luiz André Portes Paes LEME. Uma arquitetura de software para aplicações de catalogação automática de dados geográficos. [Title in English: A Software architecture for the automated cataloguing of geographic data] M.Sc. Diss. Port. Presentation: 08/08/06 120 p. Advisor: Marco Antonio Casanova

Abstract: The amount and variety of geographic data increase as technology evolves. To make them useful it is necessary to implement search engines capable of identifying appropriate data. Such engines are usually based on  metadata catalogs which describe the geographic data. However, the metadata generation process is time consuming and is not fail if it is carried out manually. This dissertation presents a software architecture, and related technologies for the construction of automated cataloguing applications of geographic data.

[06_MSc_ricci]
Luiz Antonio RICCI. SHDM.Net - um framework e ambiente de desenvolvimento dirigido por ontologias para aplicações hipermídia. [Title in English: SHDM.Net - a framework and development environment driven by ontologies for hypermedia applications]  M.Sc. Diss. Port. Presentation: 06/09/2006  117 p. Advisor: Daniel Schwabe.

Abstract: This dissertation presents how a model driven development architecture and environment framework to support Web application development are being developd using SHDM/OOHDM as development methods. The models are described through graphical diagrams that are processed by the environment. The application interface is also produced using models, and the interface produced is defined by concrete interface ontologies, specified in RDFS, that maps the concrete widgets to some target technology such as ASP.Net and XAML. The main purpose is to ease the development of a web application using Visual Studio .Net 2005 as an IDE and SHDM as the development method, allowing the application architect to focus on the application modeling. SHDM.Net generates a complete runnable application; also producing domain-specific languages for each application modeled, resulting in a programming model much more concise and natural. The main feature of SHDM.Net is the integration between the analysis and development phases of a project.

[06_MSc_rodrigues]
Luiz Fernando Chagas RODRIGUES. Teste automatizado para sistemas multi-agentes abertos implementados com o middleware M-Law. [Title in English: Automated test for open multi-agent systems implemented with M-Law middleware]  M.Sc. Diss. Port. Presentation: 15/08/2006  92 p. Advisor: Carlos José Pereira de Lucena.

Abstract: Complexity and distribution of multi-agent systems make the development of such systems failure prone. In this context, few solutions try to solve the problem through automated tests as we see in object oriented development. This work presents a framework for test automated applications development through the use of Stub agents for the middleware M-Law. This middleware implements the law-enforcement mechanism for regulating OMAS specified by the description language XMLaw which implements a law definition language, called XMLaw, for agent interaction in open multi-agent systems.


[06_MSc_nogara]
Luiz Gustavo Couri NOGARA. Um estudo sobre middlewares adaptáveis. [Title in English: A study on adaptive middlewares]  M.Sc. Diss. Port. Presentation: 01/09/2006 110 p. Advisor: Renato Fontoura de Gusmão Cerqueira.

Abstract: Middlewares have been used in order to develop distributed applications in a variety of domains. Each of these domains has different requirements related to the communication among parts of the distributed system. Many times the requirements of different domains are contradictory, turning the implementation of a middleware that fulfills them in more than one application domain into a very complex problem. One of the options to solve this issue is to create the middleware in a way that it can be adapted accordingly to the needs of each application. In this study we survey some of the available techniques for the construction of adaptative middleware, ranging from simple changes in the transmission of data between nodes in a distributed system to more through adaptations in a system in order to allow for different application execution contexts. As a case study we propose a component model for an exixting middleware, implemented in Lua, with the goal of enabling the middleware to accommodate adaptations in its implementation in a simple and structured manner. We also created experiments in order to
evaluate the applicability and effectiveness of the middleware.

[06_PhD_silva]
Lyrene Fernandes da SILVA. Uma estratégia orientada a aspectos para modelagem de requisitos. [Title in English: An aspect-oriented requirements modeling strategy]  Ph.D. Thesis. Port. Presentation: 30/03/06 222 p. Advisor: Julio Cesar Sampaio do Prado Leite.

Abstract: Due to the increasing software complexity, it has been difficult to manipulate the models that represent them. It is difficult to identify the impact of changes, to modify, or reuse model parts in other projects because the system concerns are, in general, strongly interconnected.  Traditional modeling and programming methods use separation method to minimize this coupling, however they consider only one dimension (classes, functions, events). Therefore, the concerns in other dimensions continue scattered and tangled, i.e., they are crosscutting concerns. In this thesis, we applied aspect-oriented concepts in modeling requirements. We define a metamodel to integrate crosscutting concerns that provides a set of activies and mechanisms to facilitate the requirements modularization, traceability, evolution and reuse. These mechanisms are centered in a language that defines new constructs to be used in traditional requirements languages, allowing the separation and composition of crosscutting concerns. We present two detailed case studies to show the proposed metamodel instantiated to a goal oriented requirements model, V-graph.


[06_MSc_gatti]
Maíra Athanázio de Cerqueira GATTI. Fidedignidade de sistemas multiagentes abertos governados por leis. [Title in English: Dependability of open multi-agent systems based on a law-governed approach]  M.Sc. Diss. Port. Presentation: 18/08/2006  138 p. Advisor: Carlos José Pereira de Lucena and Jean-Pierre Briot.

Abstract: With law-governed multi-agent systems complexity growth, it is harder to design and implement requirements related to dependability mainly because there is no control point over such systems. Despite the great importance of those problems, there is no solution that fully addresses those issues in the context of law-governed  multi-agent systems. However, there is a fault tolerant technique called Agent Replication that proposes the reuse of some recovery concepts of distributed systems through a fault tolerance based approach on some data that helps the identification of critical agent. And, besides the existents strategies of agents' criticality estimation, none of them presents the granularity degree necessary for the monitoring of law-governed open MAS's. Due to it, the goal of this work is to present a mechanism of the configuration variation of the agents' criticality that interacts in open  MAS's. To achieve this goal, an architecture to support the development of fault tolerant law-governed open MAS and an approach to design such mechanisms with simplicity, modularity and reuse were proposed. This work has three main contributions: an extension on the conceptual model of the law-specification declarative language XMLaw within new elements to monitor the agents' criticality; the integration of two frameworks: one is for law-enforcement (M-Law), and the other one is for a dynamic and adaptative agents' replication (DimaX); and a proposal of a means to document and derive the laws. Finally, we present some sheets of the results of the proposed mechanism application in two case studies.


[06_MSc_noronha]
Maíra Ferreira de NORONHA. Controle da execução e disponibilização de dados para aplicativos sobre seqüências biológicas: o caso BLAST. [Title in English: Execution and data availability control for applications on biological sequences: the case of BLAST]  M.Sc. Diss. Port. Presentation: 20/09/2006  83 p. Advisor: Sérgio Lifschitz.

Abstract: This work consists on the creation of a tool named BioProvider to provide data to BLAST. The tool provides the data using buffer management techniques that are efficient for BLAst and controls process scheduling. The communication between BioProvider and the BLAST processes, as well as the concurrency and blocking control, is done through a device driver that substitutes the read and write function calls to the database files. By this means, the application code can remain unchanged and BioProvider can be used with different versions of BLAST. The development of BioProvider was the first stage to the creation of a solution that can be applied as well to other Bioinformatics tools. Due to its transparency in the view of other applications, BioProvider can be easily extended in the future to provide data to other applications, to use other buffer management techniques or to provide data stored in different formats of those read by the client processes, converting the data in runtime. BioProvider has been tested with the most recent version of NCBI BLAST and considerable improvement has been verified. The tool has been shown to work as well with the open source version of WU-BLAST. Some variations on the buffer management algorithm were studied, as well as the different factors that influence the performance of BLAST processes.
 

[06_MSc_mas]
Marcelo Albuquerque Fernandes MÁS. Um estudo sobre leilões de demanda unitária. [Title in English: A study on unit-demand auctions] M.Sc. Diss. Port. Presentation: 06/09/06 82 p. Advisor: Eduardo Sany Laber

Abstract: This work focuses on the development of randomized truthful mechanisms that seek to maximize both the revenue and the economic efficiency, or social welfare, of unit-demand auctions. In a unit-demand auction a set of k items is auctioned to a set on n consumers and no consumer can purchase more than one item. A framework is presented for devising polynomial-time randomized truthful mechanisms that are based on a new variant of the Vickrey-Clarke-Grovees (VCG) mechanism. Instead of using reserve prices, this variant of VCG uses the number of objects that we wish to sell as a parameter. The mechanisms obtained differ from each other in the way they select the number of items to be sold and allow an interesting trade-off between revenue and economic efficiency, while
improving upon the state-of-the-art results for the Unit-Demand Auction problem.
 

[06_MSc_santos]
Marcelo Nery dos SANTOS. GridFS - um servidor de arquivos para grades e ambientes distribuídos heterogêneos. [Title in English: GridFS: A file server for grids and heterogeneous distributed environments] M.Sc. Diss. Port. Presentation: 22/03/06 101 p. Advisor: Renato Fontoura de Gusmão Cerqueira.

Abstract: Grid computing allows the use of distributed networks resources for tasks requiring a high processing power. A Grid infra-structure may help in the execution of these tasks and is able to coordinate their related activities, possibly regarding the provision of data files for the tasks executing in the grid nodes. GridFS is a system that enables data sharing in grid and heterogeneous distributed environments. By deploying servers over several nodes, it is possible to build a federated system integrating all local file systems and leveraging possibilities for tera-scale sized data storage. The proposed system was modeled and developed considering several aspects such as scalability, interoperability and performance.  GridFS combines some characteristics from diverse file management systems, that is, GridFS provides an API for remote data access, copy operations allowing file transfers between servers, and some special features for grid environments. Apart from defining system characteristics and implementation aspects, this dissertation shows some experimental results about the service scalability and performance, and, as an evaluation, discusses the integration of GridFS with CSBase, a framework used to develop systems for grid computing.

[06_MSc_moreno]
Marcio Ferreira MORENO. Um middleware declarativo para sistemas de TV digital interativa. [Title in English: A declarative middleware to interactive TV systems]  M.Sc. Diss. Port. Presentation: 12/04/2006  105 p. Advisor: Luiz Fernando Gomes Soares and Rogério Ferreira Rodrigues.

Abstract:  The evolution of digital modulation techniques and the efficient schemes for digital transmissions have allowed the advent of the digital TV. Conceiving low cost receivers is one of the main challenges to broaden digital TV use, mainly in non-developed countries. As a consequence, low cost requirements should not burden receiver resources that should try to reduce their costs in items such as software copyright and royalties. In this scenario, the middleware (which use mechanisms defined by the communication protocols, the operational system and its libraries) conception plays an important role. A great number of declarative middleware focuses on user interaction instead of synchronization, in its broad sense. However, the majority of digital TV applications deals with different types of media-objects synchronization, beyond the audio and video that compose the main stream. Thus, the declarative middleware language focus should be placed on synchronism, having user interaction as a special sychronization case. This is the goal of this work. The middleware implementation presented in this work is based on the modular architecture of the HyperProp Formatter, whose architecture was reorganized in a simple profile for digital TV systems. The implementation was carried out using C++ language, and all media players were developed to run in low cost receivers.


[06_PhD_gerosa]
Marco Aurélio GEROSA. Desenvolvimento de groupware componentizado com base no modelo 3C de colaboração. [Title in English: Component-based groupware development based on the 3C collaboration model]  Ph.D. Thesis. Port. Presentation: 16/03/06  275 p. Advisor: Hugo Fuks.

Abstract: Groupware is evolutionary and difficult to develop and maintain.  Thus, its codes becomes unstructured and difficult to evolve. In this thesis, a groupware development approach based on components organized according to the 3C collaboration model is proposed. In this model, collaboration is analyzed based on communication, coordination and cooperation. Collaboration necessities of the group, analyzed based on the 3C model, are mapped to software components, also organized according to the model, in order to compose the system. The proposed approach is applied as a case study to the development of the new version of the AulaNet environment. The environment's code currently suffers the mentioned problems. In order to instantiate the communication services of the environment, for the case study, 3C based component kits were developed. The components allow the composition, re-composition and customization of the services in order to reflect collaboration dynamics changes.


[06_PhD_pimentel]
Mariano Gomes PIMENTEL. RUP-3C-Groupware: um processo de desenvolvimento de groupware baseado no modelo 3C de colaboração. [Title in English: RUP-3C-Groupware: a groupware development process based on the 3C Collaboration Model]  Ph.D. Thesis. Port. Presentation: 22/03/06 162 p. Advisor: Hugo Fuks

Abstract: A groupware (group work support software) development process is proposed in this thesis. This process is the result of eight years of experience with the development of services for the AulaNet environment, and more specifically of five years researching and developing Mediated Chat tool versions. The good practices learned through these activities were incorporated into the process proposed: the use of the 3C Collaboration Model to guide groupware development, evolutionary development focusing on a single problem per version in an investigative process, and reuse-oriented component-based development. These practices were used to guide the specification of the RUP, Rational Unified Process, resulting in the new process, namely the RUP-3C-Groupware. The new or extended RUP-3C-Groupware workflows and artifacs are presented. This process was investigated through a case-study in which Software Engineering students performed certain activities producing a few key-artifacts. From this case-study some indications regarding process repetitiveness and its suitability to groupware development were obtained.


[06_MSc_zimmermann]
Mario Mendes de Oliveira ZIMMERMANN. LuaPS - Lua Publish-Subscribe.  [Title in English: LuaPS - Lua Publish-Subscribe]  M.Sc. Diss. Port. Presentation: 31/03/06. 75 p. Advisor: Noemi de La Rocque Rodriguez.

Abstract: Publish-subscribe systems are defined by its communication model.  However, most of the existent publish-subscribe systems incorporate other mechanisms in their implementation. This work seeks a better understanding of publish-subscribe systems, defining an architecture where different layers group related decisions and  constructions. Based on this architecture, we describe a system developed in Lua that uses a distributed hash table as its base. The system differs in its architecture from monolithic publish-subscribe systems and focus on generality, flexibility and extensibility.


[06_MSc_braga]
Otavio de Pinho Forin BRAGA. Uma arquitetura para síntese de imagens fotorrealistas baseada em técnicas de Monte Carlo. [Title in English: An architecture for photorealistic image synthesis based on Monte Carlo techniques]  M.Sc. Diss. Port. Presentation: 17/04/06. 75 p. Advisors: Marcelo Gattass and Paulo Cezar Pinto Carvalho.

Abstract: One of the main goals in computer graphics is to create photorealistic images, that is, images indistinguishable from the ones captured by a real camera, or, more ambitiously, images that cause the same sensation on the visual system of an observer looking directly at a scene. Applications include illumination design, architecture, virtual reality and the movie industry. This work presents the architecture of a renderer that solves by Monte Carlo techniques the light transport equation, essentially a geometric optics approximation of Maxwell's equations. The system is not only a functional renderer but also a framework where we can easily experiment new ideas in photorealistic image synthesis, such as new materials, geometries, aceleration structures and integration techniques.

[06_MSc_oguri]
Pedro OGURI. Aprendizado de máquina para o problema de sentiment analysis. [Title in English: Machine learning for sentiment classification] M.Sc. Diss. Port. Presentation: 25/10/06. 75 p. Advisors: Ruy Luiz Milidiú and Raul Pierre Rentería.

Abstract: Sentiment Analysis is a text categorization problem in which we want to identify favorable and unfavorable opinions towards a given topic. Examples of such topics are organizations and its products. In this problem, documents are classifed according to their sentiment, connotation, attitudes and opinions instead of being limited to the facts described in it. The main challenge in Sentiment Classification is identifying how sentiments are expressed in texts and whether they indicate a positive (favorable) or negative (unfavorable) opinion towards a topic. Due to the growing volume of information available online in an environment where we all tend to be content generators and express opinions on a variety of subjects, Machine Learning techniques have become more and more attractive. In this dissertation, we investigate Machine Learning methods applied to Sentiment Analysis. We present document representation models such as bag-of-words and N-grams. We compare the performance of the Naive Bayes and the Support Vector Machine classifiers for each proposed model.

[06_MSc_ghelman]
Raphael GHELMAN. Extensão de um sistema de integração de repositórios de objetos de aprendizagem visando a personalização das consultas com enfoque em acessibilidade.  [Title in English: Extension of an integration system of learning objects repositories aiming at personalizing queries with focus on accessibility]  M.Sc. Diss. Port. Presentation: 29/08/06. 128 p. Advisors: Rubens Nascimento Melo and Sean Wolfgand Matsui Siqueira.

Abstract:  Nowadays e-learning is becoming more important as it makes possible the dissemination of knowledge and information through the Internet in a faster and costless way. Consequently, in order to filter what is more relevant and/or of users' interest, architectures and personalization techniques have been raised. Among the many existing possibilities of personalization, the one that deals with accessibility is becoming essential because it guarantees that a wide variety of users may have access to the information according to their preferences and needs. Accessibility is not just about ensuring that disabled people can access information, although this is important and may be a legal requirement. It is also about ensuring that the wide variety of users and devices can all gain access to information, thereby maximizing the potential audience. This dissertation presents an extension of LORIS, an integration system of learning object repositories, describing the changes on its architecture to make it able to deal with accessibility and to recognize different versions of the same learning object, thus allowing a user to execute a query considering his/her preferences and needs. A prototype of the services that are described in the architecture was developed using web services and faceted navigation, as well as e-learning and accessibility standards. The use of web services and standards aims at providing flexibility and interoperability, while the faceted navigation, as implemented, allows the user to apply multiple filters to the query results without the need to resubmit it.

[06_MSc_kawase]
Ricardo Robalinho KAWASE. Um framework para a construção de interfaces para manipulação direta de conjuntos. [Title in English: A framework for the development of interfaces for direct manipulation on sets] M.Sc. Diss. Port. Presentation: 04/09/06 78 p. Advisor: Daniel Schwabe.

Abstract: This dissertation proposes the development of a framework capable to generate an interface for navigation and direct manipulation on groups and objects of a specific repository. Based on Shneiderman's Visual Information Seeking Mantra, "Overview first, zoom and filter, then details on demand" the zoomable user interface generated by the framework, using Piccolo library, has the characteristics of exhibit all groups in a single canvas, filters and infinite zoom. The objective of this framework it to allow developers to join the generated interface with any library based on groups and objects, and to joint the direct manipulation interactions with it's domain-specific language that describes the operations on objects. Through a quick implementation of the custom object class and of the mapping class, repository"s objects are mapped to a correspondent format in the framework according to the desired mode of renderization, as well the operations on objects defined in the DSL are mapped to operations on the interface. With the map of the operations, it is up to the user, through a simple configuration file, to select which direct manipulation interactions on the interface call which operation. The final interface uses the data and the actions given by the developer and behaves according to the choices of the end-user.

[06_MSc_martins]
Rodrigo Pereira MARTINS. Renderização em tempo real utilizando mapas de iluminação em alta precisão. [Title in English: Real time rendering using high dynamic range illumination maps]  M.Sc. Diss. Port. Presentation: 07/04/2006. 99 p. Advisor: Bruno Feijó.

Abstract:  In 1997, the seminal work by Paul Debevec and Jitendra Malik on the generation of HDR (High Dynamic Range) images, from ordinary LDR (Low Dynamic Range) cameras, facilitated the generation of light probes enormously. In consequence, this caused a boom of works on the rendering of objects with images of light from the real world, which is known as Image-Based Lighting. The present dissertation aims to study this new area, trying to situate itself in the question of real-time compositing of synthetic objects in real images. This dissertation proposes a real-time rendering pipeline for 3D games, in the simple case of static scenes, adapting the non-real-time technique presented by Paul Debevec in 1998. There is no written work about this adaptation in the literature, although exists some reference to developments done by graphics card manufacturers in this direction. Also this dissertation presents an experiment with diffuse objects. Moreover, the author gives ideas towards the solution of shadow problems for diffuse objects.


[06_MSc_dias]
Sandra Aparecida DIAS. Integração semântica de dados através de federação de ontologias. [Title in English: Semantic data integration through ontology federation]  M.Sc. Diss. Port. Presentation: 17/03/2006. 83 p. Advisor: Rubens Nascimento Melo.

Abstract:  The WEB has spread out the use of heterogeneous distributed databases. Sometimes, the answer to a query demands the use of more than one database. Some level of integration among these databases is desired. However, frequently, the bases were not designed according to a unique semantic pattern. Thus, it seems essential to relate the different data, in the respective base, in order to provide an adequate answer to the query. The process of building this relationship is often called data integration. The Data Base community has acquired enough knowledge to deal with this in the context of Data Base Heterogeneous Federation. Nowadays, there are more expressive model descriptions, namely ontologies. The Data Base community has also considered ontologies as a tool to contribute as part of a solution to the data integration problem. The Semantic WEB community defined alignment or merge of ontologies as one of the possible solutions to the some of this integration problem. This work has the aim of using "merge" of ontologies methods as a mean to define the construction of a Federation of ontologies as a mean to integrate source of data. The dissertation includes a case study written in the Protegé tool. From this case study, a discussion follows on the scalability and applicability of the proposal as a feasible technological solution for data integration.


[06_MSc_rosseto]
Silvana ROSSETO. Integrando comunicação assíncrona e gerência cooperativa de tarefas em ambientes de computação distribuída. [Title in English: Integrating asynchronous communication with cooperative task management in distributed computing environments]  Ph.D. Thesis. Port. Presentation: 24/03/06  95 p. Advisor: Noemi de La Rocque Rodriguez and Gian Pietro Picco.

Abstract: New contexts of distributed computing emphasize the need of programming abstractions able to deal with asynchronous communication and concurrent tasks. Event-driven or threaded programming models are able to deal with these issues, but each model presents particular advantages and problems. Normally, when choosing the model more appropriate for a context or problem, the programmer must deal directly with the difficulties related to this model, making the development task more complex. In this work we discuss a way to combine the advantages of the traditional programming models in order to support a programming interface more suitable for the programmer. We explore asynchronous communication and cooperative task management based on the co-routine construction. By using these concepts, we implement: (1) a set of operations for building client/server applications upon an asynchronous communication basis; and (2) a more appropriate programming interface for TinyOS, the state of the art of operating system for sensor networks.


[06_MSc_maranhao]
Suzana Mesquita de Borba MARANHÃO. Ajuste elástico em tempo de exibição para fluxos de áudio comprimido. [Title in English: On-the-fly timescale for compressed audio streams]  M.Sc. Diss. Port. Presentation: 03/04/2006. 136 p. Advisor: Luiz Fernando Gomes Soares.

Abstract:  Timescale is a technique used to modify media-object playing duration. This worl proposes timescale algorithms, to be performed on-the-fly, for compressed audio streams. The focus is situations where there is no user interface as, for example, the temporal consistency maintenance of a hypermedia document. The algorithms are proposed, developed and integrated to video timescale algorithms. Furthermore, a resynchronization algorithm is also proposed, and implemented, in order to maintain inter-media synchronization in MPEG-2 system streams. The timescale tool is composed by the aforementioned algorithms and their integration to content rendering tools. The proposed solution can be easily used in applications that need timescale compressed media streams. As an example, the adjustment tool was integrated to a hypermedia formatter. The proposed algorithms can adjust audio durations up to 10%, maintaining the audio perceptual quality within acceptable limits, as observed through quality measurements also described in this work.
 

[06_PhD_rodrigues]
Vagner José do Sacramento RODRIGUES. Gerência de privacidade para aplicações sensíveis ao contexto em redes móveis. [Title in English: Privacity to context-aware applications in mobile networks] Ph.D. Thesis. Port. Presentation: 15/09/06 135 p. Advisors: Markus Endler and Clarisse Sieckenius de Souza.

Abstract: The widespread dissemination of IEEE 802.11 networks and the enhancement of positioning techniques based on RF signal strength (e.g., sensors, positioning triangulation algorithms, etc) have fostered the development of location-based and context-aware services and applications. These applications offer several benefits to the end-users, e.g. adaptation to the device and wireless network limitations, access to location-specific information, or the ability to send location-specific notifications to other users (e.g., Geocaching). However, there are two main challenges concerning the development and use of context-aware applications: the complexity in developing context provisioning services and the need to guarantee the privacy of the users' context information (e.g.; their location). In order to support the development of context-aware applications, we have designed and implemented some services that constitute the core of a context provisioning architecture called MoCA (Mobile Collaboration Architecture). These services implement the gathering, processing and diffusion of context information through synchronous and event-based communication interfaces. MoCA architecture has been used as a basis to the development of our research about privacy in which we have designed a service that aids the end-user in defining the privacy level for his/her contextual information, and in particular for his/her location information. As part of our work, we define the conceptual model underlying our privacy control service (targeted at a community of users) and discuss the most important requirements that should be considered in the design of such a service. Most of these requirements have guided the design and implementation of the Context Privacy Service (CoPS). This service has   been integrated to the context provisioning services of the MoCA middleware.

[06_MSc_silva]
Vinicius Fontes Vieira da SILVA. QEEF-G: execução paralela adaptativa de consultas iterativas. [Title in English: QEEF-G: Adpative parallel execution of iterative queries]  M.Sc. Diss. Port. Presentation: 21/09/06 92 p. Advisor: Rubens Nascimento Melo.

Abstract: Traditional parallel query processing uses multiple computing nodes to reduce query response time. Withing a grid computing context, the availability of thousands of nodes challenge current parallel query processing techniques to support massive parallelism in a constrantly varying environment conditions. In addition, scientific applications running on grids offer new data processing characteristics that shall be integrated in such a framework. In this work we present the CoDIMS-G parallel query processing system with a full-fledged new query execution operator named Orbit. Orbit is designed for evaluating massive iterative based data processing. Tuples in Orbit iterate over a parallelized fragment of query execution plan. This work includes the development of the query processing system and a new scheduling algorithm that considers variation on network and the throughput of each node. Such algorithm permits the system to adapt constantly to the changes in the environment.