Maracanaú, Brazil
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Araujo R.T.S.,Federal University of Ceará | Medeiros F.N.S.,Federal University of Ceará | Araujo M.E.S.,Instituto Federal do Ceara IFCE | Lima K.P.,Federal University of Lavras | And 2 more authors.
IEEE Latin America Transactions | Year: 2017

Engineering education as a field of study is young, and the number of experienced researchers investigating the complex learning questions associated with becoming an engineer still sparse [44]. In this perspective, the following research question can be outlined: Do educational resources that are available in online engineering courses, such as Virtual Learning Environment, Content Instructional Design and Simulations, impact the effectiveness of learning? The main objective of this article is to statistically assess the effectiveness of e-learning courses in engineering. To fulfill the research objective, the use of the investigated learning resources was observed in a distance learning course, and an evaluation instrument was adapted, validated and applied to the students. To test the learning effectiveness, multivariate statistical methods were used to analyze the instrument, namely: Principal Component Analysis (PCA) and canonical correlation analysis. The multivariate analysis with the canonical correlation discloses how the positive contribution of the two groups arises from the PCA application: Functionality of Virtual Environment and Design Content and Simulations in learning effectiveness. © 2003-2012 IEEE.


Arruda T.B.M.G.,Federal University of Ceará | Dantas M.B.,Instituto Federal da Paraiba IFPB | de Araujo K.C.,Instituto Federal da Paraiba IFPB | Rodrigues F.E.A.,Instituto Federal do Ceara IFCE | And 2 more authors.
International Journal of Energy and Environmental Engineering | Year: 2017

This research reports the use of cooking oil waste and moringa biodiesel and their blends into mineral diesel and the influence of the storage conditions. The behavior of the blend between moringa and cooking oil waste and biodiesel were evaluated through thermogravimetric analysis and the data were used in the determination of the kinetic parameters of the blends as activation energy and pre-exponential factor and the values found were similar to reported in literature for others samples of biodiesel. The quality of the blend between biodiesel and diesel and the influence of storage conditions were evaluated through the determination of the acid value of the samples. The acid value for the samples that contained mineral diesel was virtually constant. The acid values of the samples of biodiesel were not in accordance with Brazilian legislation, but did not affect the quality of the blend with mineral diesel. The average values of activation energy for waste cooking oil and moringa biodiesel were 70.04 ± 2.99 and 53.80 ± 6.83 kJ mol−1, respectively. © 2017 The Author(s)


Kleine I.,German Research Center for Geosciences | Rogass C.,German Research Center for Geosciences | Medeiros P.H.A.,Instituto Federal Do Ceara IFCE | Meyer Zu Erpen N.,Astrium GEO Information Services | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The semi-arid Northeast of Brazil is characterized by distinct rainy and dry seasons. The water supply for the local population is based on surface reservoirs in which precipitation is collected. There are more than 150 reservoirs in the 933 km2 Benguê catchment, however, little is known about the temporal dynamics of the water storage in the reservoirs. In this study, we use TerraSAR-X imagery for a year-long monitoring of reservoir surface areas and their seasonal changes. The precise extraction of the reservoir surface areas forms the basis of the monitoring. Therefore, we evaluated the results of a pixel-based threshold classification and a feature-based segmentation (mean shift). The evaluation was based on in-situ GPS measurements and manual digitization. The results of the manual digitization and threshold classification were similar as both tended to underestimate the water surface area in comparison to GPS in-situ data. The mean shift segmentation, however, tended to spread over the shorelines into the surrounding areas. We used the threshold classification for the analysis of 47 TerraSAR-X images. The viewing direction of the TerraSAR-X sensor was also important for the distinction of the entire area of the reservoirs, since geometric effects at the shorelines shaded parts of the water surface area. For the monitoring of the reservoir area with only one viewing direction we derived an empirical geometry correction factor. © 2013 SPIE.


Sousa R.,University of Porto | Da Rocha Neto A.R.,Instituto Federal Do Ceara IFCE | Cardoso J.S.,INESC Porto | Barreto G.A.,Federal University of Ceará
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2014

Reject option is a technique used to improve classifier's reliability in decision support systems. It consists on withholding the automatic classification of an item, if the decision is considered not sufficiently reliable. The rejected item is then handled by a different classifier or by a human expert. The vast majority of the works on this issue have been concerned with implementing a reject option by endowing a supervised learning scheme (e.g., Multilayer Perceptron, Learning Vector Quantization or Support Vector Machines) with a reject mechanism. In this paper we introduce variants of the Self-Organizing Map (SOM), originally an unsupervised learning scheme, to act as supervised classifiers with reject option, and compare their performances with that of the MLP classifier. © 2014 Springer International Publishing Switzerland.


Furtado Junior C.G.,Instituto Federal Do Ceara IFCE | Soares J.M.,Federal University of Ceará | Barroso G.C.,Federal University of Ceará
IEEE Latin America Transactions | Year: 2015

Efficient policies should be applied in order to decrease the document retrieval time on distributed systems, the network traffic, admission and content replacement for cache systems. Usually, proposed simulators that aim to select better policies have limitation. As an example, it's difficult to create scenarios with multiple cache systems. Besides, frequently those simulators present a lack of extensibility resources for both custom policies as to include new mechanisms for measuring performance. To address these issues, we developed CacheSIM. It is an extensible platform for simulating distributed cache systems. Using CacheSIM, we can conceive different scenarios based on a hierarchical Coloured Petri Net (CPN) model. We are able to define one replacement policy of fifteen available and one admission policy of two possible ones. Moreover, we can program custom policies and choose them. This paper presents the architecture and native resources of CacheSIM. We have evaluated its extensibility by including two replacement policies based on semantics found in works of the state of the art. We reproduced scenarios and results of those works, as well as we compared to those obtained using native policies. Thus, we can demonstrate the potential of CacheSIM as a simulation tool. © 2003-2012 IEEE.


De Oliveira T.Q.,Instituto Federal do Ceara IFCE | Fernandez M.P.,State University of Ceará
Proceedings - International Conference on Advanced Information Networking and Applications, AINA | Year: 2013

Content Delivery Network (CDN) is a large distributed system of servers deployed in multiple data centers on the Internet. Its main goal is to serve requests from users providing high availability and performance. It also reduces the system failure risk providing redirection to many replica servers. It can provide load balancing between servers, avoiding network bottlenecks and, therefore, ensuring greater performance and QoE (Quality of Experience) to the end user. One of the critical issues involving CDN networks is the algorithm used to choose the replica server, because it directly influences the performance and scalability of the network. In this paper, the FuzzyCDN algorithm is proposed. The algorithm chooses the best replica server in a CDN network using a Fuzzy logic decision-making algorithm. The proposal is compared in simulation against other algorithms in the literature. © 2013 IEEE.


Bezerra Mota Gomes Arruda T.,Federal University of Ceará | Arruda Rodrigues F.E.,Instituto Federal do Ceara IFCe | Duarte Arruda D.T.,Federal University of Ceará | Pontes Silva Ricardo N.M.,Federal University of Ceará | And 2 more authors.
Industrial Crops and Products | Year: 2016

The brute oil obtained by sesame seed mechanical extraction and biodiesel obtained through transesterification with methyl and ethyl alcohol was analyzed by the use of the following techniques: gas chromatography coupled to mass spectrometer (CG/MS) and nuclear magnetic resonance of hydrogen and carbon (NMR 1H and 13C). The seeds were cultivated in Sousa city, located in the northeast of Brazil. The linoleic acid was found as major component of the oil followed by the oleic acid. The NMR spectra confirm the obtaining of the methyl and ethyl biodiesel. The thermal behavior of the oil and the biodiesel were determined by the use of thermogravimetric analysis (TG). The TG curves were obtained in three different heat rates (10, 20 e 30 °C.min−1) in oxidative atmosphere. The decomposition of the biodiesels occurred in only one-step. However, three steps were observed for the thermal degradation of the brute oil. These steps can be attributed to evaporation and/or decomposition of the triglycerides. The analysis of the thermogravimetric data allowed the determination of the thermodynamics parameters as pre exponential factor and activation energy. The average value of the energy activation for the methyl biodiesel was 67.54 ± 0.84 KJ mol−1 and for the ethyl biodiesel was 66.74 ± 0.75 KJ mol−1. © 2016


Araujo R.T.S.,Federal University of Ceará | Araujo M.E.S.,Instituto Federal Do Ceara IFCE | Medeiros F.N.S.,Federal University of Ceará | Oliveira B.F.C.,Federal University of Ceará | Araujo N.M.S.,State University of Ceará
IEEE Latin America Transactions | Year: 2016

This paper presents a simulator to help electrical engineering students and professionals in the learning process. The proposed tool embodies Virtual Reality technologies on the improvement of understanding equipment maneuvers in distribution power systems. The tool has a virtual didactic distribution network in which the students handle several real tasks related to operation and maintenance of distribution network through applied technology. We hope that this tool can contribute to develop and improve professional skills in engineering at a low cost and furthermore it supports laboratory and associated technical activities. © 2016 IEEE.


Imaculada Soares Pereira R.,Federal University of Ceará | Cesar Silveira Juca S.,Instituto Federal Do Ceara IFCE | Cesar Marques De Carvalho P.,Federal University of Ceará
IEEE Latin America Transactions | Year: 2016

The present project consists of a system based on free hardware and software for online monitoring, using a WiFi embedded modem, applied to an electrical microgeneration plant based on thermoelectric microgenerators (GTEs). These have small size, zero-carbon emission, no moving parts or noise and produce electricity through the reuse of waste heat. The main objective is to analyze plant variables through online monitoring software developed in order to allow data storage in an online database and chart generation with the possibility of remote access. © 2016 IEEE.


Menezes J.W.M.,Federal University of Ceará | Fraga W.B.,Federal University of Ceará | Fraga W.B.,Instituto Federal Do Ceara IFCE | Ferreira A.C.,Federal University of Ceará | And 4 more authors.
Fiber and Integrated Optics | Year: 2010

In this article, a numerical simulation study using the symmetric planar three-core non-linear directional coupler, operating with a short light pulse (2 ps), for the implementation of an all-optical half-adder is presented. The half-adder is the key building block for many digital processing functions such as shift register, binary counter, and serial parallel data converters. Optical couplers are an important component for application in optical fiber telecommunication systems and all integrated optical circuits because of very high switching speeds (as high as the femto-second range). In this numerical simulation, the symmetric planar three-core non-linear directional coupler presents a planar symmetrical structure with three cores in a parallel equidistant arrangement, three logical inputs (CP, A, and B), and two output logic functions (C and S). The CP(Δφ) input is a control pulse with a phase difference Δφ= Δθπ(0≤2Δθ≤2) between inputs A and B (logical inputs of the half-adder) and one amplitude discriminator circuit. The half-adder uses two output logic functions of Sum(S) and Carry(C), which can be demonstrated by using XOR and AND gates, respectively. For the half-adder, the phase [ΔφMIN, ΔφMAX] intervals are studied, allowing the operation of the device as a half-adder. For the selected range of CP(ΔφBETTER), the extinction ratio was studied, the compression factors for both Sum(S) and Carry(C) outputs of the symmetric planar three-core non-linear directional coupler. Copyright © Taylor & Francis Group, LLC.

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