Time filter

Source Type

Salvador, Brazil

Barbosa D.,Salvador University | Netto U.C.,University of Sao Paulo | Coury D.V.,University of Sao Paulo | Oleskovicz M.,University of Sao Paulo
IEEE Transactions on Power Delivery | Year: 2011

The power transformer is a piece of electrical equipment that needs continuous monitoring and fast protection since it is very expensive and an essential element for a power system to perform effectively. The most common protection technique used is the percentage differential logic, which provides discrimination between an internal fault and different operating conditions. Unfortunately, there are some operating conditions of power transformers that can affect the protection behavior and the power system stability. This paper proposes the development of a new algorithm to improve the differential protection performance by using fuzzy logic and Clarke's transform. An electrical power system was modeled using Alternative Transients Program (ATP) software to obtain the operational conditions and fault situations needed to test the algorithm developed. The results were compared to a commercial relay for validation, showing the advantages of the new method. © 2011 IEEE. Source

Molitor M.,Salvador University
Journal of Geometric Mechanics | Year: 2015

Let (M, g) be a compact, connected and oriented Riemannian manifold with volume form dvolg. We denote by D the space of smooth probability density functions on M, i.e. D := {ρ ∈ C∞ (M, ℝ) | ρ > 0 and ∫Mρ·dvolg = 1}. We regard D as an infinite dimensional manifold. In this paper, we consider the almost Hermitian structure on TD associated, via Dombrowski's construction, to the Wasserstein metric gD and a natural connection ∇D on D. Using geometric mechanical methods, we show that the corresponding fundamental 2-form on T D leads to the Schrödinger equation for a quantum particle living in M. Geometrically, we exhibit a map which pulls back the Fubini-Study symplectic form to the 2-form on TD. The integrability of the almost complex structure on TD is also discussed. These results echo other papers of the author where it is stressed that the Fisher metric and exponential connection are related (via Dombrowski's construction) to Kähler geometry and the quantum formalism in finite dimension. © American Institute of Mathematical Sciences. Source

Do Rosario J.L.P.,Salvador University
Journal of Bodywork and Movement Therapies | Year: 2014

Introduction: The study of posture is not an easy task, mainly because postural assessment is still scientifically inaccurate. Photographs of bipedalism in the frontal and sagittal planes are one of the most widely used methods for this assessment. The aim of this literature review was to determine which anatomical markers authors of scientific papers have taken to minimize the chances of error in measurements. Materials and methods: The Medline and Lilacs databases were searched for the period from 2002 to 2012, with the following keywords: "postura"; "posture" and "postural.". Discussion: A number of studies have shown a reasonable correlation between radiographic measurements and the placement of markers. It appears possible to use photography as a form of scientific assessment since the anatomical landmarks are well chosen. Conclusion: The markers that were suggested in this review: malleolus; posterior calcaneal tuberosity; fibular head; tibial tuberosity; greater trochanter of the femur; anterior angle and/or posterior lateral edge of the acromion; spinous processes (particularly C7); inferior angle of the scapula; sternum manubrium; mental protuberance; and the intertragic notch. Iliac spines, both anterior superior and posterior superior, should only be used with lean subjects. © 2013 Elsevier Ltd. Source

Camara G.,Federal University of Bahia | Andrade C.,Federal University of Bahia | Silva Jr. A.,Federal University of Bahia | Rocha P.,Salvador University
Journal of Cleaner Production | Year: 2013

Increased anthropogenic emissions and accumulation of greenhouse gases (GHGs) in the atmosphere have led to climate change, which has become a major global environmental concern. The effects of anthropogenic GHG emissions and their relationship with climate change have been extensively studied and discussed in recent decades. Carbon dioxide (CO2) is one of the main GHGs, and several technologies have been developed to capture and dispose of it before it is released into the atmosphere. CO2 storage in geological reservoirs to mitigate CO2 emissions is one of the technological solutions that has attracted interest. This article primarily focuses on answering the following question: To what extent can the storage of carbon dioxide in geological reservoirs (CGS) be considered a cleaner technology? A literature review on this subject was carried out along with document analysis and expert consultation. Initially, the literature on environmental technologies, specifically that on CGS technology, was reviewed. Subsequently, the use of CGS technology as an environmental technology was investigated. We conclude that it can be considered a transitional technology. © 2012 Elsevier Ltd. All rights reserved. Source

Zolina O.,University of Bonn | Zolina O.,CNRS Laboratory for Glaciology and Environmental Geophysics | Simmer C.,University of Bonn | Belyaev K.,Salvador University | And 2 more authors.
Journal of Climate | Year: 2013

Daily rain gauge data over Europe for the period from 1950 to 2009 were used to analyze changes in the duration of wet and dry spells. The duration of wet spells exhibits a statistically significant growth over northern Europe and central European Russia, which is especially pronounced in winter when the mean duration of wet periods increased by 15%-20%. In summer wet spells become shorter over Scandinavia and northern Russia. The duration of dry spells decreases over Scandinavia and southern Europe in both winter and summer. For the discrimination between the roles of a changing number of wet days and of a regrouping of wet and dry days for the duration of the period, the authors suggest a fractional truncated geometric distribution. The changing numbers of wet days cannot explain the long-term variability in the duration of wet and dry periods. The observed changes are mainly due to the regrouping of wet and dry days. The tendencies in duration of wet and dry spells have been analyzed for a number of European areas. Over the Netherlands both wet and dry periods are extended in length during the cold and the warm season. A simultaneous shortening of wet and dry periods is found in southern Scandinavia in summer. Over France and central southern Europe during both winter and summer and over the Scandinavian Atlantic coast in summer, opposite tendencies in the duration of wet and dry spells were identified. Potential mechanisms that might be responsible for the changing durations of wet and dry periods and further perspectives are discussed. © 2013 American Meteorological Society. Source

Discover hidden collaborations