384 resultados para Comités


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The main goal of this work is to investigate the suitability of applying cluster ensemble techniques (ensembles or committees) to gene expression data. More specifically, we will develop experiments with three diferent cluster ensembles methods, which have been used in many works in literature: coassociation matrix, relabeling and voting, and ensembles based on graph partitioning. The inputs for these methods will be the partitions generated by three clustering algorithms, representing diferent paradigms: kmeans, ExpectationMaximization (EM), and hierarchical method with average linkage. These algorithms have been widely applied to gene expression data. In general, the results obtained with our experiments indicate that the cluster ensemble methods present a better performance when compared to the individual techniques. This happens mainly for the heterogeneous ensembles, that is, ensembles built with base partitions generated with diferent clustering algorithms

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In the world we are constantly performing everyday actions. Two of these actions are frequent and of great importance: classify (sort by classes) and take decision. When we encounter problems with a relatively high degree of complexity, we tend to seek other opinions, usually from people who have some knowledge or even to the extent possible, are experts in the problem domain in question in order to help us in the decision-making process. Both the classification process as the process of decision making, we are guided by consideration of the characteristics involved in the specific problem. The characterization of a set of objects is part of the decision making process in general. In Machine Learning this classification happens through a learning algorithm and the characterization is applied to databases. The classification algorithms can be employed individually or by machine committees. The choice of the best methods to be used in the construction of a committee is a very arduous task. In this work, it will be investigated meta-learning techniques in selecting the best configuration parameters of homogeneous committees for applications in various classification problems. These parameters are: the base classifier, the architecture and the size of this architecture. We investigated nine types of inductors candidates for based classifier, two methods of generation of architecture and nine medium-sized groups for architecture. Dimensionality reduction techniques have been applied to metabases looking for improvement. Five classifiers methods are investigated as meta-learners in the process of choosing the best parameters of a homogeneous committee.

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Committees of classifiers may be used to improve the accuracy of classification systems, in other words, different classifiers used to solve the same problem can be combined for creating a system of greater accuracy, called committees of classifiers. To that this to succeed is necessary that the classifiers make mistakes on different objects of the problem so that the errors of a classifier are ignored by the others correct classifiers when applying the method of combination of the committee. The characteristic of classifiers of err on different objects is called diversity. However, most measures of diversity could not describe this importance. Recently, were proposed two measures of the diversity (good and bad diversity) with the aim of helping to generate more accurate committees. This paper performs an experimental analysis of these measures applied directly on the building of the committees of classifiers. The method of construction adopted is modeled as a search problem by the set of characteristics of the databases of the problem and the best set of committee members in order to find the committee of classifiers to produce the most accurate classification. This problem is solved by metaheuristic optimization techniques, in their mono and multi-objective versions. Analyzes are performed to verify if use or add the measures of good diversity and bad diversity in the optimization objectives creates more accurate committees. Thus, the contribution of this study is to determine whether the measures of good diversity and bad diversity can be used in mono-objective and multi-objective optimization techniques as optimization objectives for building committees of classifiers more accurate than those built by the same process, but using only the accuracy classification as objective of optimization

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This work discusses the application of techniques of ensembles in multimodal recognition systems development in revocable biometrics. Biometric systems are the future identification techniques and user access control and a proof of this is the constant increases of such systems in current society. However, there is still much advancement to be developed, mainly with regard to the accuracy, security and processing time of such systems. In the search for developing more efficient techniques, the multimodal systems and the use of revocable biometrics are promising, and can model many of the problems involved in traditional biometric recognition. A multimodal system is characterized by combining different techniques of biometric security and overcome many limitations, how: failures in the extraction or processing the dataset. Among the various possibilities to develop a multimodal system, the use of ensembles is a subject quite promising, motivated by performance and flexibility that they are demonstrating over the years, in its many applications. Givin emphasis in relation to safety, one of the biggest problems found is that the biometrics is permanently related with the user and the fact of cannot be changed if compromised. However, this problem has been solved by techniques known as revocable biometrics, which consists of applying a transformation on the biometric data in order to protect the unique characteristics, making its cancellation and replacement. In order to contribute to this important subject, this work compares the performance of individual classifiers methods, as well as the set of classifiers, in the context of the original data and the biometric space transformed by different functions. Another factor to be highlighted is the use of Genetic Algorithms (GA) in different parts of the systems, seeking to further maximize their eficiency. One of the motivations of this development is to evaluate the gain that maximized ensembles systems by different GA can bring to the data in the transformed space. Another relevant factor is to generate revocable systems even more eficient by combining two or more functions of transformations, demonstrating that is possible to extract information of a similar standard through applying different transformation functions. With all this, it is clear the importance of revocable biometrics, ensembles and GA in the development of more eficient biometric systems, something that is increasingly important in the present day

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Incluye Bibliografía

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Incluye Bibliografía

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Our study considers the natural resources of the Miombo forests in Cabo Delgado from a broad ecosystems perspective. Thus, our view goes beyond the disciplinary approaches of forestry, agronomy, biology or zoology, and also of the social sciences, namely anthropology, history, sociology, political science or economics. The present study aims to establish a dialogue and create synergies between Miti Ltd. – the logging company and owner of the forest concessions – as well as government and state structures at the various levels and the communities – through the Committees on Natural Resources – in order to promote the sustainable use of resources and ecosystems. The research methodology we used can broadly be described as moderated transdisciplinary interaction for action-research based on the approach known as Learning for Sustainability (LforS, http://www.cde.unibe.ch/Pages/Project/2/14/Learning-for-Sustainability-Extension-Approach.aspx). The research methods used include: LforS seminars; field work; forests observations focusing, among others, on ecosystems, trees, wildlife, and burned areas; visits to farms; and interviews. We conducted both collective interviews and individual interviews, including with key informants. The main results indicate that members of the Committee on Natural Resources have a dual attitude: their statements defend the paradigm of sustainable use of natural resources as well as their own immediate monetary gain. They are willing to apply the values, concepts and theories of sustainable development that underpin the establishment of Committees on Natural Resources if they are paid for their work or if they can derive direct benefits from it, i.e. if they can earn a salary or allowance. If this does not happen, however, they are willing to allow actors to engage in illegal hunting or logging activities. This dual attitude also exists in relation to forestry operators. If the concession workers pay the committee members in cash or provide goods, they can run their business even if they violate the law. Natural forest regeneration in Nkonga and Namiune already shows the impact of such use. Although there are many saplings that could basically ensure continuous regeneration under sustainable management, repeated burning is damaging the young trees, deforming them and killing a great number of them. Campaigns against uncontrolled fires are ineffective because the administrative and political authorities have a dual attitude as well and are also part of the group that uses resources to their own profit and benefit. There are institutional structures within the administration, populations, and communities to perform regulating functions, create and implement rules, punish offenders, and oversee resource use. However, they feel that since they are not paid for performing these functions, they do not have to do so. This attitude shows a lack of awareness, but also indicates a situation where everyone seeks to derive maximum benefits from existing resource use patterns. Anything goes.

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Welsch (Projektbearbeiter): Darlegung der Geschehnisse in Großherzogtum Posen aus polnischer Sicht