Aplicação de técnicas inteligentes com análise no domínio do tempo para reconhecimento de defeitos em motores de indução trifásicos

Os motores de indução trifásicos são os principais elementos de conversão de energia elétrica em mecânica motriz aplicados em vários setores produtivos. Identificar um defeito no motor em operação pode fornecer, antes que ele falhe, maior segurança no processo de tomada de decisão sobre a manutenção da máquina, redução de custos e aumento de disponibilidade. Nesta tese são apresentas inicialmente uma revisão bibliográfica e a metodologia geral para a reprodução dos defeitos nos motores e a aplicação da técnica de discretização dos sinais de correntes e tensões no domínio do tempo. É também desenvolvido um estudo comparativo entre métodos de classificação de padrões para a identificação de defeitos nestas máquinas, tais como: Naive Bayes, k-Nearest Neighbor, Support Vector Machine (Sequential Minimal Optimization), Rede Neural Artificial (Perceptron Multicamadas), Repeated Incremental Pruning to Produce Error Reduction e C4.5 Decision Tree. Também aplicou-se o conceito de Sistemas Multiagentes (SMA) para suportar a utilização de múltiplos métodos concorrentes de forma distribuída para reconhecimento de padrões de defeitos em rolamentos defeituosos, quebras nas barras da gaiola de esquilo do rotor e curto-circuito entre as bobinas do enrolamento do estator de motores de indução trifásicos. Complementarmente, algumas estratégias para a definição da severidade dos defeitos supracitados em motores foram exploradas, fazendo inclusive uma averiguação da influência do desequilíbrio de tensão na alimentação da máquina para a determinação destas anomalias. Os dados experimentais foram adquiridos por meio de uma bancada experimental em laboratório com motores de potência de 1 e 2 cv acionados diretamente na rede elétrica, operando em várias condições de desequilíbrio das tensões e variações da carga mecânica aplicada ao eixo do motor.

El sur también existe: las relaciones migratorias entre las islas Baleares y la Argelia francesa (1830-1962)

La Argelia francesa (1830-1962) constituyó un poderoso polo de atracción para los habitantes de las islas Baleares y del sudeste peninsular. En este artículo se analizan las relaciones migratorias y comerciales entre el archipiélago balear y su por entonces próspero vecino del sur. Además, también se estudian los diferentes exilios que vincularon las dos riberas del Mediterráneo. Para realizar este artículo se han combinado tanto fuentes primarias como la bibliografía existente.

Métodos de máxima verosimilitud en ecología y su aplicación en modelos de vecindad

Los métodos de máxima verosimilitud (MMV) ofrecen un marco alternativo a la estadística frecuentista convencional, alejándose del uso del p-valor para el rechazo de una única hipótesis nula y optando por el uso de las verosimilitudes para evaluar el grado de apoyo en los datos a un conjunto de hipótesis alternativas (o modelos) de interés para el investigador. Estos métodos han sido ampliamente aplicados en ecología en el marco de los modelos de vecindad. Dichos modelos usan una aproximación espacialmente explícita para describir procesos demográficos de plantas o procesos ecosistémicos en función de los atributos de los individuos vecinos. Se trata por tanto de modelos fenomenológicos cuya principal utilidad radica en funcionar como herramientas de síntesis de los múltiples mecanismos por los que las especies pueden interactuar e influenciar su entorno, proporcionando una medida del efecto per cápita de individuos de distintas características (ej. tamaño, especie, rasgos fisiológicos) sobre los procesos de interés. La gran ventaja de aplicar los MMV en el marco de los modelos de vecindad es que permite ajustar y comparar múltiples modelos que usen distintos atributos de los vecinos y/o formas funcionales para seleccionar aquel con mayor soporte empírico. De esta manera, cada modelo funcionará como un “experimento virtual” para responder preguntas relacionadas con la magnitud y extensión espacial de los efectos de distintas especies coexistentes, y extraer conclusiones sobre posibles implicaciones para el funcionamiento de comunidades y ecosistemas. Este trabajo sintetiza las técnicas de implementación de los MMV y los modelos de vecindad en ecología terrestre, resumiendo su uso hasta la fecha y destacando nuevas líneas de aplicación.

Variación espacial de la exposición a contaminación atmosférica en la ciudad de Valencia y su relación con un índice de privación

Objetivo: Evaluar la variación espacial de la exposición a dióxido de nitrógeno (NO2) en la ciudad de Valencia y su relación con la privación socioeconómica y la edad. Métodos: La población por sección censal (SC) procede del Instituto Nacional de Estadística. Los niveles de NO2 se midieron en 100 puntos del área de estudio, mediante captadores pasivos, en tres campañas entre 2002 y 2004. Se utilizó regresión por usos del suelo (LUR) para obtener el mapa de los niveles de NO2. Las predicciones del LUR se compararon con las proporcionadas por: a) el captador más cercano de la red de vigilancia, b) el captador pasivo más cercano, c) el conjunto de captadores en un entorno y d) kriging. Se asignaron niveles de contaminación para cada SC. Se analizó la relación entre los niveles de NO2, un índice de privación con cinco categorías y la edad (≥65 años). Resultados: El modelo LUR resultó el método más preciso. Más del 99% de la población superó los niveles de seguridad propuestos por la Organización Mundial de la Salud. Se encontró una relación inversa entre los niveles de NO2 y el índice de privación (β = –2,01 μg/m3 en el quintil de mayor privación respecto al de menor, IC95%: –3,07 a –0,95), y una relación directa con la edad (β = 0,12 μg/m3 por incremento en unidad porcentual de población ≥65 años, IC95%: 0,08 a 0,16). Conclusiones: El método permitió obtener mapas de contaminación y describir la relación entre niveles de NO2 y características sociodemográficas.

Improving classification using a Confidence Matrix based on weak classifiers applied to OCR

This paper proposes a new feature representation method based on the construction of a Confidence Matrix (CM). This representation consists of posterior probability values provided by several weak classifiers, each one trained and used in different sets of features from the original sample. The CM allows the final classifier to abstract itself from discovering underlying groups of features. In this work the CM is applied to isolated character image recognition, for which several set of features can be extracted from each sample. Experimentation has shown that the use of CM permits a significant improvement in accuracy in most cases, while the others remain the same. The results were obtained after experimenting with four well-known corpora, using evolved meta-classifiers with the k-Nearest Neighbor rule as a weak classifier and by applying statistical significance tests.

Improving kNN multi-label classification in Prototype Selection scenarios using class proposals

Prototype Selection (PS) algorithms allow a faster Nearest Neighbor classification by keeping only the most profitable prototypes of the training set. In turn, these schemes typically lower the performance accuracy. In this work a new strategy for multi-label classifications tasks is proposed to solve this accuracy drop without the need of using all the training set. For that, given a new instance, the PS algorithm is used as a fast recommender system which retrieves the most likely classes. Then, the actual classification is performed only considering the prototypes from the initial training set belonging to the suggested classes. Results show that this strategy provides a large set of trade-off solutions which fills the gap between PS-based classification efficiency and conventional kNN accuracy. Furthermore, this scheme is not only able to, at best, reach the performance of conventional kNN with barely a third of distances computed, but it does also outperform the latter in noisy scenarios, proving to be a much more robust approach.

Il valore del voto: Italia e Spagna nel dibattito sulla rappresentanza politica liberale (1860-1870)

During the 1860's and 1870's, Spain and Italy experienced a convergence of debates on the significance of political representation in the framework of Liberal State. Spain suffered a political and social crisis, ending with the Revolution of 1868 and the adoption of male universal suffrage in 1878. Its coeval Italy began to build its new Kingdom, anxious about state building, as well as the relevance of electoral processes in the Constitutional scheme. Although members of parliament and essayists of both countries well knew their neighbour's political reality, a dialogue on representation didn't occur. Nonetheless, we believe it is useful to analyse the survey drawn by the Italian publicist in the light of current knowledge of the opinions that prevailed in Spain. What sense did they give to the general election? How did they understand the value of the vote? Who were considered eligible voters? These questions comprise the main subjects of the essay.

Discontinuity spacing analysis in rock masses using 3D point clouds

The complete characterization of rock masses implies the acquisition of information of both, the materials which compose the rock mass and the discontinuities which divide the outcrop. Recent advances in the use of remote sensing techniques – such as Light Detection and Ranging (LiDAR) – allow the accurate and dense acquisition of 3D information that can be used for the characterization of discontinuities. This work presents a novel methodology which allows the calculation of the normal spacing of persistent and non-persistent discontinuity sets using 3D point cloud datasets considering the three dimensional relationships between clusters. This approach requires that the 3D dataset has been previously classified. This implies that discontinuity sets are previously extracted, every single point is labeled with its corresponding discontinuity set and every exposed planar surface is analytically calculated. Then, for each discontinuity set the method calculates the normal spacing between an exposed plane and its nearest one considering 3D space relationship. This link between planes is obtained calculating for every point its nearest point member of the same discontinuity set, which provides its nearest plane. This allows calculating the normal spacing for every plane. Finally, the normal spacing is calculated as the mean value of all the normal spacings for each discontinuity set. The methodology is validated through three cases of study using synthetic data and 3D laser scanning datasets. The first case illustrates the fundamentals and the performance of the proposed methodology. The second and the third cases of study correspond to two rock slopes for which datasets were acquired using a 3D laser scanner. The second case study has shown that results obtained from the traditional and the proposed approaches are reasonably similar. Nevertheless, a discrepancy between both approaches has been found when the exposed planes members of a discontinuity set were hard to identify and when the planes pairing was difficult to establish during the fieldwork campaign. The third case study also has evidenced that when the number of identified exposed planes is high, the calculated normal spacing using the proposed approach is minor than those using the traditional approach.

An ethnopharmacological and historical analysis of “Dictamnus”, a European traditional herbal medicine

Ethnopharmacological relevance and background: “Dictamnus” was a popular name for a group of medicinal herbaceous plant species of the Rutaceae and Lamiaceae, which since the 4th century have been used for gynaecological problems and other illnesses BCE and still appear in numerous ethnobotanical records. Aims: This research has as four overarching aims: Determining the historical evolution of medical preparations labelled “Dictamnus” and the different factors affecting this long-standing herbal tradition. Deciphering and differentiating those medicinal uses of “Dictamnus” which strictly correspond to Dictamnus (Rutaceae), from those of Origanum dictamnus and other Lamiaceae species. Quantitatively assessing the dependence from herbal books, and pharmaceutical tradition, of modern Dictamnus ethnobotanical records. Determining whether differences between Western and Eastern Europe exist with regards to the Dictamnus albus uses in ethnopharmacology and ethnomedicine. Methods: An exhaustive review of herbals, classical pharmacopoeias, ethnobotanical and ethnopharmacological literature was conducted. Systematic analysis of uses reported which were standardized according to International Classification of Diseases – 10 and multivariate analysis using factorial, hierarchical and neighbour joining methods was undertaken. Results and discussion: The popular concept “Dictamnus” includes Origanum dictamnus L., Ballota pseudodictamnus (L.) Benth. and B. acetabulosa (L.) Benth. (Lamiaceae), as well as Dictamnus albus L. and D. hispanicus Webb ex Willk. (Rutaceae), with 86 different types of uses. Between 1000 and 1700 CE numerous complex preparations with “Dictamnus” were used in the treatment of 35 different pathologies. On biogeographical grounds the widespread D. albus is a far more likely prototypical “Dictamnus” than the Cretan endemic Origanum dictamnus. However both form integral parts of the “Dictamnus” complex. Evidence exists for a sufficiently long and coherent tradition for D. albus and D. hispanicus, use to treat 47 different categories of diseases. Conclusions: This approach is a model for understanding the cultural history of plants and their role as resources for health care. “Dictamnus” shows how transmission of traditional knowledge about materia medica, over 26 centuries, represents remarkable levels of development and innovation. All this lead us to call attention to D. albus and D. hispanicus which are highly promising as potential herbal drug leads. The next steps of research should be to systematically analyse phytochemical, pharmacological and clinical evidence and to develop safety, pharmacology and toxicology profiles of the traditional preparations.

Quem é o meu próximo? Senciência, empatia e ilimitação

This paper aims to rethink the traditional understanding of the two commandments formulated by Christ – to love God and our neighbour as ourselves –, by rethinking the category of neighbour, not just as those who belongs to the human species, but as all those to whom we can feel close, depending on the degree of empathy concerning not just sentient beings, but even all forms of life and existence. Rethinking also God not as the supreme being, but (according to the etymology) as the light of the full awareness of life itself, we propose that to live wholeheartedly the two commandments implies to die and resurrect as being everything in all and all things.

Putin’s grand design to destroy the EU’s Eastern Partnership and replace it with a disastrous neighbourhood policy of his own. CEPS Commentary, 17 September 2013

This new Commentary by Michael Emerson and Hrant Kostanyan shows how the pressure exerted by President Putin on Armenia to withdraw from the Deep and Comprehensive Free Trade Agreement it had negotiated with the EU and to join the Belarus, Kazakhstan and Russia customs union is but the most recent in a long series of ongoing moves by Russia to destroy the Eastern Partnership. In their view, the message to be hammered home to those unsure of the economic arguments is that you do not have to have an exclusive customs union to enjoy deep integration for goods, services, people and capital, and of course even less for hard security relationships. High-quality free trade agreements are the logical instrument for those who want excellent relations with more than one big neighbour.

The Judicial Dimension of the European Neighbourhood Policy. EU Diplomacy Paper 08/2013, November 2013

In this paper, the expression “neighbourhood policy” of the European Union (EU) is understood in a broad way which includes the members of the European Free Trade Association (EFTA) contracting parties to the European Economic Area (EEA), the EFTA State Switzerland, candidate states, the countries of the European Neighbour-hood Policy (ENP), and Russia. The European Court of Justice (ECJ) is the centre of gravity in the judicial dimension of this policy. The innermost circle of integration after the EU itself comprises the EFTA States who are party to the European Economic Area. With the EFTA Court, they have their own common court. The existence of two courts – the ECJ and the EFTA Court – raises the question of homogeneity of the case law. The EEA homogeneity rules resemble the ones of the Lugano Convention. The EFTA Court is basically obliged to follow or take into account relevant ECJ case law. But even if the ECJ has gone first, there may be constellations where the EFTA Court comes to the conclusion that it must go its own way. Such constellations may be given if there is new scientific evidence, if the ECJ has left certain questions open, where there is relevant case law of the European Court of Human Rights or where, in light of the specific circumstances of the case, there is room for “creative homogeneity”. However, in the majority of its cases the EFTA Court is faced with novel legal questions. In such cases, the ECJ, its Advocates General and the Court of First Instance make reference to the EFTA Court’s case law. The question may be posed whether the EEA could serve as a model for other regional associations. For the ENP states, candidate States and Russia this is hard to imagine. Their courts will to varying degrees look to the ECJ when giving interpretation to the relevant agreements. The Swiss Government is – at least for the time being – unwilling to make a second attempt to join the EEA. The European Commission has therefore proposed to the Swiss to dock their sectoral agreements with the EU to the institutions of the EFTA pillar, the EFTA Surveillance Authority (ESA) and the EFTA Court. Switzerland would then negotiate the right to nominate a member of the ESA College and of the EFTA Court. The Swiss Government has, however, opted for another model. Swiss courts would continue to look to the ECJ, as they did in the past, and conflicts should also in the future be resolved by diplomatic means. But the ECJ would play a decisive role in dispute settlement. It would, upon unilateral request of one side, give an “authoritative” interpretation of EU law as incorporated into the relevant bilateral agreement. In a “Non-Paper” which was drafted by the chief negotiators, the interpretations of the ECJ are even characterised as binding. The decision-making power would, however, remain with the Joint Committees where Switzerland could say no. The Swiss Government assumes that after a negative decision by the ECJ it would be able to negotiate a compromise solution with the Commission without the ECJ being able to express itself on the outcome. The Government has therefore not tried to emphasise that the ECJ would not be a foreign court. Whether the ECJ would accept its intended role, is an open question. And if it would, the Swiss Government would have to explain to its voters that Switzerland retains the freedom to disregard such a binding decision and that for this reason the ECJ is not only no foreign court, but no adjudicating court at all.

Kyiv-in memoriam; Brussels-think big; Moscow-big rethink. CEPS Commentaries, 24 February 2014

In surveying the traumatic events of the last week in Kyiv, Michael Emerson reports on the profoundly moving scenes at the Maidan this last weekend, but goes on to offer constructive advice to the EU on its next move there; and the clear message to Russia that its coercive policies towards its most important neighbour do not work and need a big rethink.

How should the EU respond to Russia's war in Ukraine? CEPS Commentary, 3 September 2014

President Putin has chosen to escalate the conflict in south-eastern Ukraine, thereby ignoring both the sanctions and the diplomatic advances of the EU and its partners in response to Russia’s belligerence towards its neighbour over the last six months. Ahead of the NATO Summit in Wales on September 4-5, calls are growing for EU member states to provide arms and more intelligence to Ukraine’s beleaguered army. But it is far from certain that the EU will summon up the collective courage to do so. Beyond sanctions, what other options does the EU have to alter the Kremlin’s calculus?

The prospects for Croatia's co-operation with the Visegrad Group. OSW Commentary No. 116, 02.10.2013

The Visegrad Group gained a new neighbour in the European Union on 1 July 2013. Given the geographic proximity, similar level of development and a number of shared interests, Croatia could become a valuable partner in Central European regional co-operation. Co-operation in the “V4+” format is possible in most of the Visegrad Group’s priorities, primarily in: energy security, transport, neighbourhood policy and EU enlargement. V4 could be attractive for Croatia as a grouping which forms broader coalitions within the EU and is helpful in solving regional problems. However, making use of this potential in practice will depend on the determination to enhance co-operation, and its success may be thwarted by temporary bilateral issues.