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.
De Oliveira Rolim H.,Federal University of Ceará |
Chaves J.R.,Federal University of Ceará |
De Araujo Nunes A.B.,Federal University of Ceará |
Filho H.A.S.,Docente Doutor do Instituto Federal do Ceara IFCE |
Dos Santos E.V.M.,Instituto Federal do Ceara IFCE
Revista em Agronegocio e Meio Ambiente | Year: 2016
The reuse of affluents from two biological sewage treatment systems is assessed. The study comprised a Upflow Anaerobic Sludge Blanket (UASB) reactor and an activated sludge system according to standards recommended by the World health Organization and water quality criteria for irrigation. Evaluated variables included pH; CE; Ca2+; Mg2+;; Na+; Cl-; NTK; total phosphorus; OCD; Turbidity; TSS; ammonia; thermotolerant coliforms and helminth eggs; RAS; and salinity. Results showed that system partially comply with requirements for agricultural reuse. The UASG system showed TSS and turbidity as limiting in irrigation; coliform concentration for restricted sub-surface irrigation; NTK above 30 mg.L-1+; and counts > 1.0 egg.L-1+;of helminths that make reuse unviable. UCT system had less limitations according to the parameters evaluated, with non-viability of direct reuse mainly due to turbidity, coliforms and helminths eggs.
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.
Sales A.J.M.,Federal University of Ceará |
Sousa D.G.,Federal University of Ceará |
Rodrigues H.O.,Instituto Federal do Ceara IFCE |
Costa M.M.,Institute of Physics |
And 5 more authors.
Ceramics International | Year: 2016
In the present article, optical properties and energy upconversion in Er3+/Yb3+ co-doped BiNbO4 matrix were investigated. The BiNbO4 matrix was prepared using the solid-state reaction method. X-ray diffraction of the matrix shows that the crystal structure is consistent with ICSD code 74338. The grain distribution and the behavior of doping with Er3+ and Yb3+ on the sample surface were obtained by scanning electron microscope. Raman spectral characterization was carried out to examine the behavior of the vibrational modes of the samples. Upconversion emissions in the visible region at 484.5, 522, 541.5 and 670.5nm in the matrices BiNbO4:Er,Yb and BiNbO4:Er were observed and analyzed as a function of 980nm laser excitation power and rare-earth doping concentration. The results show that BiNbO4 is a promising host material for efficient upconversion phosphors. © 2016.
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.