Teixeira V.C.,Federal University of Sergipe |
Montes P.J.R.,Federal Institute of Sergipe |
Valerio M.E.G.,Federal University of Sergipe
Optical Materials | Year: 2014
Pure, Ce3+ doped and Ce3+ and Mn2+ co-doped Ca2Al2SiO7 ceramic powders were prepared by two different methodologies which are the proteic sol-gel process and a new hybrid route combining the proteic sol-gel with solid state reaction processes. The second one is an eco-friendly method because it uses natural raw materials in replacement of the metal alkoxides used in the traditional sol-gel routes. X-ray diffraction showed that Ca2Al2SiO 7 crystalline phase was obtained for both preparations. Differential thermal analysis indicated that the exothermic event around 850°C, for sample produced by proteic sol-gel method, and around 927°C, for ceramics prepared by hybrid synthesis, can be associated to crystallization of Ca 2Al2SiO7. Transmission electron microscope indicates that regular and spherical nanoparticles were obtained with average sizes of about 12 nm. The Scherrer's method was used to determine the average crystallite sizes and it was shown that nanometric crystallites were obtained of about 74 nm for samples produced via hybrid route. For all the single phase samples, the crystallite sizes are about the same and that agrees with TEM results. Diffuse optical reflectance measurements were used to estimate the Ca2Al2SiO7 optical band gap and the obtained value is about 6 eV, photoluminescence (PL) spectra presented typical emissions of Ce3+ and Mn2+ ions. Upon excitation at 352 nm the emission spectra showed a broad band centered at 415 nm due to the Ce 3+ 4f1 → 5d1 typical transition. This emission is resonant with Mn2+ excitation and it transfers energy to Mn ions generating a second broad emission band centered at 620 nm due to the Mn2+. The PL results were used to obtain, as a fist approach, the Ce3+ energy levels diagram and, using the Tanabe-Sugano diagrams, the transitions due to the Mn2+ were calculated. X-ray excited optical luminescence measurements showed the same emission spectra as the PL emission spectra. Luminescence lifetime decay constants were measured for Ce and Mn co-doped and for Ce doped samples and the results indicate Ca2Al 2SiO7:Ce3+, Mn2+ showed quite fast responses with main time constants below 30 ns. © 2014 Elsevier B.V. All rights reserved.
de Oliveira R.P.,Federal University of Bahia |
de Oliveira R.P.,Federal Institute of Sergipe |
de Almeida E.S.,Federal University of Bahia |
da Silva Gomes G.S.,Federal University of Bahia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014
The evolution of a single system is a task where we deal with the modification of a single product. Lehman’s laws of software evolution were broadly evaluated within this type of systems and the results shown that these single systems evolve according to his stated laws over time. However, when dealing with Software Product Lines (SPL), we need to deal with the modification of several products which include common, variable and product specific assets. Because of the several assets within SPL, each stated law may have a different behavior for each asset kind. Nonetheless, we do not know if the stated laws are still valid for SPL since they were not yet evaluated in this context. Thus, this paper details an empirical investigation where four of the Lehman’s Laws (LL) of Software Evolution were used in an SPL industrial project to understand how the SPL assets evolve over time. This project relates to an application in the medical domain developed in a medium-size company in Brazil. It contains 45 modules and a total of 70.652 bug requests in the tracking system, gathered along the past 10 years. We employed two techniques - the KPSS Test and linear regression analysis, to assess the relationship between LL and SPL assets. Finally, results showed that three laws were supported based on the data employed (continuous change, increasing complexity, and declining quality). The other law (continuing growth) was partly supported, depending on the SPL evaluated asset (common, variable or product-specific). © Springer International Publishing Switzerland 2014.
de Castro F.J.S.,Federal Institute of Sergipe |
de Oliveira A.C.C.,Federal University of Sergipe
Revista Brasileira de Cineantropometria e Desempenho Humano | Year: 2016
This study aimed to verify the association between health-related physical fitness and academic performance in adolescents. Overall, 326 students aged 15-18 years of the Federal Institute of Sergipe (IFS) participated in this cross-sectional study. Data relating to physical fitness were collected by applying the following tests: body mass index, sit and reach, abdominal in one minute and one mile running, which comprise the American Alliance for Health, Physical Education, Recreation and Dance testing battery. Academic performance was measured by the grades of two-month period in the disciplines that comprise the following areas of knowledge: languages and codes, natural sciences and humanities, obtained from the IFS school record. Students with average grades ≥ 6.0 were considered on satisfactory academic performance. The prevalence of physical unfitness in the sample was 15.8% (girls 15.4%; boys 16.4%) in body composition, 32.3% (girls 23.1%; boys 41.5%) in flexibility, 93.0% (95.8% girls; 90.2% boys) in muscular strength and 86.9% (85.3% girls; 88.5% boys) in cardiorespiratory endurance. On academic performance, the prevalence of adolescents below the average grade was 8.8% (girls 5.6%; boys 12.0%) in languages and codes, 24.5% (girls 19.5%; boys 29.5%) in natural sciences and 12.8% (girls 11.9%; boys 13.7%) in humanities. Adolescents with low cardiorespiratory endurance levels were more likely to have worse academic performance (OR=2.39; CI95%=1.05 to 5.44). It was concluded that low cardiorespiratory endurance levels were associated with worse academic performance. © 2016, Universidade Federal de Santa Catarina. All rights reserved.
Santos C.A.S.,Federal University of Espirito Santo |
Neto A.N.R.,Federal Institute of Sergipe |
Saleme E.B.,Federal University of Espirito Santo
Proceedings - 2015 IEEE International Conference on Systems, Man, and Cybernetics, SMC 2015 | Year: 2015
The paper presents an event driven approach for building interactive environments with sensory effects (such as RGB color light, wind and vibration) described through MPEGV standard. The most important differences of this work from previous ones are: (1) it divides the design process into well defined stages, showing the behavior of the system under a new perspective and their interactions, (2) it follows an event driven paradigm instead of a timeline one to send commands to sensory devices and (3) it decouples rendering of MPEG-V effects from the presentation software component. The method to validate the proposed approach was a case study, which has integrated multiples sensory effects to an interactive environment based on gesture recognizing. © 2015 IEEE.
Ribeiro A.N.,Federal Institute of Sergipe |
Macedo C.A.,Federal University of Sergipe
Journal of the Korean Physical Society | Year: 2013
The goal of this work is to examine the possibility of ferromagnetism in a three-dimensional lattice using the Hubbard model with only nearest-neighbor hopping and finite on-site Coulomb interaction (U) and temperature (T) when solved using the dynamical mean-field approximation (DMFA). We calculated the density of states for an fcc lattice with n = 0.6, 0.7 and 0.8, at T = 0.04 t/k B, and with U = 3W where W denotes the non-interacting energy bandwidth. The results reveal magnetization that is nearly saturated and indicate that these systems are metallic. In the particular case where n = 0.6, the magnetization, internal energy and specific-heat versus temperature curves were calculated. © 2013 The Korean Physical Society.
Santana D.M.M.,Federal Institute of Sergipe |
Ferreira N.R.,Federal University of Bahia |
Costa F.F.,Federal University of Bahia
Przeglad Elektrotechniczny | Year: 2015
In this paper we propose to use a novel Prony’s approach, relying on suitable time-segmentation of current oscillograms and proper model order choice, to estimate transient and sub-transient parameters of synchronous generators associated to sudden three-phase short-circuit tests. Comparison between the proposed approach and a traditional graphical method, described in the IEEE-115 standard, has been performed. The current data used here have been generated from characteristic equations of short-circuit armature current. Based on these results, we conclude that the Prony’s algorithm is a suitable alternative to the graphical method for parameter estimation in synchronous machines, providing more accurate estimates than the later approach. © 2014, Wydawnictwo SIGMA - N O T Sp. z o.o. All rights reserved.
Farias M.A.D.F.,Federal University of Bahia |
Farias M.A.D.F.,Federal Institute of Sergipe |
Ortins P.,Federal University of Bahia |
Novais R.,Federal Institute of Bahia |
And 3 more authors.
Proceedings of the International Conference on Software Engineering and Knowledge Engineering, SEKE | Year: 2014
Context. Distributed software development is currently a modern practice in software industry. This is especially true in Open Source Software (OSS) development community. Understanding how developers' practices are on those projects may guide communities to successfully manage their projects. Goal. We mined two repositories of the Apache Httpd project in order to gather information about its developers' behavior. Methods. We developed an approach to cross data gathered from mail list and source code repository through mining techniques. The approach uses software visualization to analyze the mined data. We conducted an experimental evaluation of the approach to assess the behavioral patterns from OSS development community. Results. The collected data built a rich set of information. The results highlight Apache developers' behavior patterns. We perceived that there is a correlation over time between emails and commits of the Apache Project developers. Conclusion. The use of data mining and software visualization to analyze crossing data sources can spot important properties of the development process. Copyright © 2014 by Knowledge Systems Institute Graduate School.
De Oliveira R.A.,Federal Institute of Sergipe |
De Medeiros Junior M.F.,Federal University of Rio Grande do Norte |
Menezes R.F.A.,Federal University of Sergipe
Electric Power Systems Research | Year: 2014
This paper presents a proposal for minimizing costs of public illumination projects (PI), using the optimization technique of genetic algorithm (GA). The solution is found from the characteristics of public roads (input parameters) and existing norms and standards, which sets the parameters for evaluating each project, ensuring the minimum requirements for safety and comfort efficiently. In order to evaluate the results of the proposed algorithm, tests were performed, based on the characteristics of several existing roads in the state of Sergipe, Brazil, with the distribution of masts in accordance with the following standards: Unilateral, Bilateral Opposite and Central. The implemented GA provides as solution the height of the mast to be used, in addition to the distance between the masts, the number of petals and their orientation, arm size, luminaries model and power of the bulbs used. The photometric features of the set formed by the luminaries and lamp are presented in a file of type IES, like those created from tests conducted by the manufacturers of the models. The results show a good performance of the proposed methodology. © 2014 Elsevier B.V.
Ribeiro L.F.,Salvador University |
Ribeiro L.F.,Federal Institute of Bahia IFBA |
De Farias M.A.F.,Federal Institute of Sergipe |
De Farias M.A.F.,Federal University of Bahia |
And 3 more authors.
ICEIS 2016 - Proceedings of the 18th International Conference on Enterprise Information Systems | Year: 2016
The term Technical Debt (TD) is used to describe the debt that a development team incurs when it takes shortcuts in the software development process, but that may increase the complexity and maintenance cost in the long-term. If a development team does not manage TD, this debt can cause significant long-term problems such as high maintenance costs. An important goal of the management of the debt is to evaluate the appropriate time to pay a TD item and to effectively apply decision-making criteria to balance the shortterm benefits against long-term costs. However, although there are different studies that have proposed strategies for the management of TD, decision criteria are often discussed in the background and, sometimes, they are not even mentioned. Thus, the purpose of this work is to identify, by performing a systematic mapping study of the literature, decision-making criteria that have been proposed to support the management of TD. We identified 14 decision-making criteria that can be used by development teams to prioritize the payment of TD items and a list of types of debt related to the criteria. In addition, the results show possible gaps where further research may be performed. Copyright © 2016 by SCITEPRESS - Science and Technology Publications, Lda. All rights reserved.
De Figueiredo E.E.,Federal University of Campina Grande |
Souto C.C.R.A.,Federal University of Campina Grande |
Vieira Z.C.,Federal Institute of Sergipe
IAHS-AISH Proceedings and Reports | Year: 2014
In the semi arid Cariri region of the state of Paraiba, Brazil, runoff is of the Hortonian type generated by excess of rainfall over infiltration capacity, and soil erosion is governed by rainfall intensity and sediment size. However, the governing sediment transport mechanism is not well understood. Sediment transport generally depends on the load of sediment provided by soil erosion and on the transport capacity of the flow. The latter is mainly governed by mechanisms such as water shear stress, or stream power. Accordingly, the load of sediment transported by the flow may vary depending on the mechanism involved in the equation of estimation. Investigation of the sediment transport capacity of the flow via a distributed physically-based model is an important and necessary task, but quite rare in semi-arid climates, and particularly in the Cariri region of the state of Paraíba/Brazil. In this study, the equations of Yalin, Engelund & Hansen, Laursen, DuBoys and Bagnold have been coupled with the MOSEE distributed physically based model aiming at identifying the mechanisms leading to the best model simulations when compared with data observed at various basin scales and land uses in the study region. The results obtained with the investigated methods were quite similar and satisfactory suggesting the feasibility of the mechanisms involved, but the observed values were better represented with Bagnold's equation, which is physically grounded on the stream power, and we recommend it for simulations of similar climate, runoff generation mechanisms and sediment characteristics as in the study region. Copyright © 2014 IAHS Press.