49 resultados para Multiple Classifier Systems
em Reposit
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The research on multiple classifiers systems includes the creation of an ensemble of classifiers and the proper combination of the decisions. In order to combine the decisions given by classifiers, methods related to fixed rules and decision templates are often used. Therefore, the influence and relationship between classifier decisions are often not considered in the combination schemes. In this paper we propose a framework to combine classifiers using a decision graph under a random field model and a game strategy approach to obtain the final decision. The results of combining Optimum-Path Forest (OPF) classifiers using the proposed model are reported, obtaining good performance in experiments using simulated and real data sets. The results encourage the combination of OPF ensembles and the framework to design multiple classifier systems. © 2011 Springer-Verlag.
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Deposition of wear-resistant hard chromium plating leads to a decrease in the fatigue strength of the base material. Despite the effective protection against wear and corrosion, fatigue life and environmental requirements result in pressure to identify alternatives or to improve conventional chromium electroplating mechanical characteristics. An interesting, environmentally safer and cleaner alternative for the replacement of hard chronic plating is tungsten carbide thermal spray coating, applied by high velocity oxyfuel (HVOF) process.To improve the fatigue strength of aeronautical steel chromium electroplated, shot peening is a successfully used method. Multiple lacer systems of coatings are considered to have larger resistance to crack propagation in comparison with simple layer.The aim of this study was to analyze the effect of nickel underplate on the fatigue strength of hard chromium plated AISI 4340 steel in two mechanical conditions: HRc 39 and HRc 52.Rotating bending fatigue tests results indicate that the clectroless nickel plating underlayer is responsible for the increase in fatigue strength of AISI 4340 steel chromium electroplated. This behavior may be attributed to the largest toughness/ductility and compressive residual stresses which, probably, arrested or delayed the inicrocrack propagation from the hard chromium external layer. The compressive residual stress field (CRSF) induced by the electroplating process was determined by X-ray diffraction method. The evolution of fatigue strength compressive residual stress field CRSF and crack sources are discussed and analyzed by SEM. (c) 2006 Elsevier Ltd. All rights reserved.
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RACIONAL: As doenças difusas do tecido conjuntivo afetam vários sistemas orgânicos, inclusive o digestório. Neste, as lesões variam em intensidade e freqüência na dependência da doença envolvida. A descrição das diferentes manifestações digestivas tem sido pouco freqüente, pouco detalhada e, não raro, baseada em experiências individuais e levantamentos retrospectivos. Tais formas de registro de dados produzem resultados muitas vezes conflitantes entre as diferentes casuísticas. OBJETIVO: Estabelecer de forma mais consistente, por intermédio de entrevista e questionário predefinido de sintomas, o conjunto e freqüência dos sintomas digestivos observados na esclerose sistêmica progressiva, artrite reumatóide, polimiosite/dermatomiosite, doença mista do tecido conjuntivo e lúpus eritematoso sistêmico. PACIENTES E MÉTODO: Estudaram-se 99 pacientes, 90% mulheres, com idade média de 45 anos. do total, 35 tinham artrite reumatóide, 26 esclerose sistêmica progressiva, 21 lúpus eritematoso sistêmico, 12 dermatomiosite/polimiosite e 5 doença mista do tecido conjuntivo. Todos foram submetidos, por investigador treinado, a entrevista e preenchimento de um questionário de sintomas digestivos, composto de 17 itens, previamente definidos. RESULTADOS: O estudo revelou elevada prevalência de sintomas gastrointestinais nas cinco doenças investigadas, muitas vezes afetando mais de 50% dos casos. Chamou a atenção a presença significativa de sintomas negligenciados pela literatura como a incontinência fecal. Discordante de trabalhos anteriores, os pacientes desta série com artrite reumatóide apresentaram variadas queixas digestivas, surpreendendo o achado de disfagia em 1/3 deles. CONCLUSÕES: As doenças difusas do tecido conjuntivo são causas de freqüentes e numerosos sintomas digestivos. O uso de questionários predefinidos mostrou-se instrumento válido na identificação de substancial número de sintomas, alguns deles ainda não referidos pela literatura. Por fim, foi constatada escassez de trabalhos passados e atuais relativos às manifestações gastrointestinais das doenças difusas do tecido conjuntivo, o que prejudicou análises comparativas mais amplas.
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A wide range of sex chromosome mechanisms, including simple and multiple chromosome systems is characteristic of fishes. The Leporinus genus represent a good model to study sex chromosome mechanisms, because an unambiguous ZZ/ZW sex chromosome system was previously described for seven species, while the remaining studied species of the genus do not show differentiated sex chromosomes. The occurrence of sex chromosomes in Leporinus trifasciatus and Leporinus sp2 from the Araguaia river, Amazon basin, Brazil, was here investigated. ZZ/ ZW sex chromosomes were detected for both species. The Z and W chromosome morphology of L. trifasciatus is the same as described for other species of the genus Leporinus. However, the Z and W chromosomes of L. sp2 were quite different in their morphology and banding pattern suggesting that the ZW system of this species have originated independently from the ZW system previously described for other Leporinus.
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The extent of racemization of aspartic acid (Asp) has been used to estimate the ages of 9 shells of the epifaunal calcitic brachiopod Bouchardia rosea and 9 shells of the infaunal aragonitic bivalve Semele casali. Both taxa were collected concurrently from the same sites at depths of 10 m and 30 m off the coast of Brazil. Asp D/L values show an excellent correlation with radiocarbon age at both sites and for both taxa (r(Site)(2) (9) (B. rosea) = 0.97 r(Site)(2) (1) (B.) (rosea) = 0.997, r(Site)(2) (9) (S.) (casali) = 0.9998, r(2) (Site) (1) (S.casali) = 0.93). The Asp ratios plotted against reservoir-corrected AMS radiocarbon ages over the time span of multiple millennia can thus be used to develop reliable and precise geochronologies not only for aragonitic mollusks (widely used for dating previously), but also for calcitic brachiopods. At each collection site, Bouchardia specimens display consistently higher D/L values than specimens of Semele. Thermal differences between sites are also notable and in agreement with theoretical expectations, as extents of racemization for both taxa are greater at the warmer, shallower site than at the cooler, deeper one. In late Holocene marine settings, concurrent time series of aragonitic and calcitic shells can be assembled using Asp racemization dating, and parallel multi-centennial to multi-millennial records can be developed simultaneously for multiple biomineral systems. (c) 2006 University of Washington. All rights reserved.
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Wireless Sensor Networks (WSNs) can be used to monitor hazardous and inaccessible areas. In these situations, the power supply (e.g. battery) of each node cannot be easily replaced. One solution to deal with the limited capacity of current power supplies is to deploy a large number of sensor nodes, since the lifetime and dependability of the network will increase through cooperation among nodes. Applications on WSN may also have other concerns, such as meeting temporal deadlines on message transmissions and maximizing the quality of information. Data fusion is a well-known technique that can be useful for the enhancement of data quality and for the maximization of WSN lifetime. In this paper, we propose an approach that allows the implementation of parallel data fusion techniques in IEEE 802.15.4 networks. One of the main advantages of the proposed approach is that it enables a trade-off between different user-defined metrics through the use of a genetic machine learning algorithm. Simulations and field experiments performed in different communication scenarios highlight significant improvements when compared with, for instance, the Gur Game approach or the implementation of conventional periodic communication techniques over IEEE 802.15.4 networks. © 2013 Elsevier B.V. All rights reserved.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Besides possessing good mechanical properties, dental materials should present a good biological behavior and should not injure the involved tissues. Bond strength and biocompatibility are both highly significant properties of dentin adhesives. For that matter, these properties of four generations of adhesive systems (Multi-Purpose/Single Bond/SE Plus/Easy Bond) were evaluated.Eighty bovine teeth had their dentin exposed (500- and 200-mu m thickness). Adhesive was applied on the dentin layer of each specimen. Following that, the microshearing test was performed for all samples. A dentin barrier test was used for the cytotoxicity evaluation. Cell cultures (SV3NeoB) were collected from testing materials by means of 200- or 500-mu m-thick dentin slices and placed in a cell culture perfusion chamber. Cell viability was measured 24 h post-exposition by means of a photometrical test (MTT test).The best bonding performance was shown by the single-step adhesive Easy Bond (21 MPa, 200 mu m; 27 MPa, 500 mu m) followed by Single Bond (15.6 MPa, 200 mu m; 23.4 MPa, 500 mu m), SE Plus (18.2 MPa, 200 mu m; 20 MPa, 500 mu m), and Multi-Purpose (15.2 MPa, 200 mu m; 17.9 MPa, 500 mu m). Regarding the cytotoxicity, Multi-Purpose slightly reduced the cell viability to 92 % (200 mu m)/93 % (500 mu m). Single Bond was reasonably cytotoxic, reducing cell viability to 71 % (200 mu m)/64 % (500 mu m). The self-etching adhesive Scotchbond SE decreased cell viability to 85 % (200 mu m)/71 % (500 mu m). Conversely, Easy Bond did not reduce cell viability in this test, regardless of the dentin thickness.Results showed that the one-step system had the best bond strength performance and was the least toxic to pulp cells. In multiple-step systems, a correct bonding technique must be done, and a pulp capping strategy is necessary for achieving good performance in both properties.The study showed a promising system (one-step self-etching), referring to it as a good alternative for specific cases, mainly due to its technical simplicity and good biological responses.
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In this work we study some topics of Celestial Mechanics, namely the problem of rigid body rotation and “spin-orbit” resonances. Emphasis is placed on the problem formulation and applications to some exoplanets with physical parameters (e.g. mass and radius) compatible with a terrestrial type constitution (e.g. rock) belonging to multiple planetary systems. The approach is both analytical and numerical. The analytical part consists of: i) the deduction of the equation of motion for the rotation problem of a spherical body with no symmetry, disturbed by a central body; ii) modeling the same problem by including a third-body in the planet-star system; iii) formulation of the concept of “spin-orbit” resonance in which the orbital period of the planet is an integer multiple of the rotation’s period. Topics of dynamical systems (e.g. equilibrium points, chaos, surface sections, etc.) will be included at this stage. In the numerical part simulations are performed with numerical models developed in the previous analytical section. As a first step we consider the orbit of the planet not perturbed by a third-body in the star-planet system. In this case the eccentricity and orbital semi-major axis of the planet are constants. Here the technique of surface sections, widely used in dynamical systems are applied. Next, we consider the action of a third body, developing a more realistic model for planetary rotation. The results in both cases are compared. Since the technique of disturbed surface sections is no longer applicable, we quantitatively evaluate the evolution of the characteristic angles of rotation (e.g. physical libration) by studying the evolution of individual orbits in the dynamically important regions of phase space, the latter obtained in the undisturbed case
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Connectivity is the basic factor for the proper operation of any wireless network. In a mobile wireless sensor network it is a challenge for applications and protocols to deal with connectivity problems, as links might get up and down frequently. In these scenarios, having knowledge of the node remaining connectivity time could both improve the performance of the protocols (e.g. handoff mechanisms) and save possible scarce nodes resources (CPU, bandwidth, and energy) by preventing unfruitful transmissions. The current paper provides a solution called Genetic Machine Learning Algorithm (GMLA) to forecast the remainder connectivity time in mobile environments. It consists in combining Classifier Systems with a Markov chain model of the RF link quality. The main advantage of using an evolutionary approach is that the Markov model parameters can be discovered on-the-fly, making it possible to cope with unknown environments and mobility patterns. Simulation results show that the proposal is a very suitable solution, as it overcomes the performance obtained by similar approaches.
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To evaluate variations of some anatomic structures of sellar and parasellar regions and their possible differences between genders and age groups. Magnetic resonance images (MRI) of 380 patients were performed to analyze the dimensions of the sphenoid sinus, pituitary gland, optic chiasm, intra-cavernous carotid distances, distance between columella nasal - sphenoid sinus; and columella nasal-pituitary gland. The patients age ranged between 20 and 80 years (mean age 48 years). The study included 235 females (mean age 53 years) and 145 males (mean age 40 years). The transverse length of the pituitary, the inter-carotid distance and the height of the pituitary were similar between genders and age groups. The width and height of the optic chiasm showed differences only between females of different ages. Males presented greater distances between nasal columella and sphenoid sinus. The most common type of pneumatization of the sphenoid sinus was the sellar, and depending on the age group, sphenoid sinus was larger in males than females. The anatomy of the Sellar and parasellar regions is complex and varies widely within the normal range. They are a small area, rich in anatomical details affecting multiple physiological systems in the body and, therefore, have great importance in several medical fields. A better understanding of these complex structures is essential in clinical diagnosis and treatment of disease.