15 resultados para Analog-to-digital converter (ADC)
em Universidade Federal do Rio Grande do Norte(UFRN)
Resumo:
This work deals with the development of an experimental study on a power supply of high frequency that provides the toch plasmica to be implemented in PLASPETRO project, which consists of two static converters developed by using Insulated Gate Bipolar Transistor (IGBT). The drivers used to control these keys are triggered by Digital Signal Processor (DSP) through optical fibers to reduce problems with electromagnetic interference (EMI). The first stage consists of a pre-regulator in the form of an AC to DC converter with three-phase boost power factor correction which is the main theme of this work, while the second is the source of high frequency itself. A series-resonant inverter consists of four (4) cell inverters operating in a frequency around 115 kHz each one in soft switching mode, alternating itself to supply the load (plasma torch) an alternating current with a frequency of 450 kHz. The first stage has the function of providing the series-resonant inverter a DC voltage, with the value controlled from the power supply provided by the electrical system of the utility, and correct the power factor of the system as a whole. This level of DC bus voltage at the output of the first stage will be used to control the power transferred by the inverter to the load, and it may vary from 550 VDC to a maximum of 800 VDC. To control the voltage level of DC bus driver used a proportional integral (PI) controller and to achieve the unity power factor it was used two other proportional integral currents controllers. Computational simulations were performed to assist in sizing and forecasting performance. All the control and communications needed to stage supervisory were implemented on a DSP
Resumo:
In this study, the methodological procedures involved in digital imaging of collapsed paleocaves in tufa using GPR are presented. These carbonate deposits occur in the Quixeré region, Ceará State (NE Brazil), on the western border of the Potiguar Basin. Collapsed paleocaves are exposed along a state road, which were selected to this study. We chose a portion of the called Quixeré outcrop for making a photomosaic and caring out a GPR test section to compare and parameterize the karst geometries on the geophysical line. The results were satisfactory and led to the adoption of criteria for the interpretation of others GPR sections acquired in the region of the Quixeré outcrop. Two grids of GPR lines were acquired; the first one was wider and more spaced and guided the location of the second grid, denser and located in the southern part of the outcrop. The radargrams of the second grid reveal satisfactorily the collapsed paleocaves geometries. For each grid has been developed a digital solid model of the Quixeré outcrop. The first model allows the recognition of the general distribution and location of collapsed paleocaves in tufa deposits, while the second more detailed digital model provides not only the 3D individualization of the major paleocaves, but also the estimation of their respective volumes. The digital solid models are presented here as a new frontier in the study of analog outcrops to reservoirs (for groundwater and hydrocarbon), in which the volumetric parameterization and characterization of geological bodies become essential for composing the databases, which together with petrophysical properties information, are used in more realistic computer simulations for sedimentary reservoirs.
Resumo:
Over the last decades, the digital inclusion public policies have significantly invested in the purchase of hardwares and softwares in order to offer technology to the Brazilian public teaching institutions, specifically computers and broadband Internet. However, the teachers education to handle these artefacts is put away, even though there is some demand from the information society. With that, this dissertation chooses as an object of study the digital literacy practices performed by 38 (thirty-eight) teachers in initial and continuous education by means of the extension course Literacies and technologies: portuguese language teaching and cyberculture demands. In this direction, we aim at investigating the digital literacy practices of developing teachers in three specific moments: before, while and after this extension action with the intent to (i) delineate the digital literacy practices performed by the collaborators before the formative action; (ii) to narrate the literacy events made possible by the extension course; (iii) to investigate the contributions of the education course to the collaborators teaching practice. We sought theoretical contributions in the literacy studies (BAYNHAM, 1995; KLEIMAN, 1995; HAMILTON; BARTON; IVANIC, 2000), specifically when it comes to digital literacy (COPE, KALANTZIS, 2000; BUZATO, 2001, 2007, 2009; SNYDER, 2002, 2008; LANKSHEAR & KNOBEL, 2002, 2008) and teacher education (PERRENOUD, 2000; SILVA, 2001). Methodologically, this virtual ethnography study (KOZINETS, 1997; HINE, 2000) is inserted into the field of Applied Linguistics and adopts a quali-quantitative research approach (NUNAN, 1992; DÖRNYEI, 2006). The data analysis permitted to evidentiate that (i) before the course, the digital literacy practices focused on the personal and academic dimensions of their realities at the expense of the professional dimension; (ii) during the extension action, the teachers collaboratively took part in the hybrid study sessions, which had a pedagogical focus on the use of ICTs, accomplishing the use of digital literacy practices - unknown before that; (iii) after the course, the attitude of the collaborator teachers concerning the use of ICTs on their regular professional basis had changed, once those teachers started to effectively make use of them, promoting social visibility to what was produced in the school. We also observed that teachers in initial education acted as more experienced peers in collaborative learning process, offering support scaffolding (VYGOTSKY, 1978; BRUNER, 1985) to teachers in continuous education. This occurred because of the undergraduates actualize digital literacy practices were more sophisticated, besides the fact being integrate generation Y (PRENSKY, 2001)
Resumo:
This dissertation aims to develop a software applied to a communication system for a wireless sensor network (WSN) for tracking analog and digital variables and control valve of the gas flow in artificial oil s elevation units, Plunger Lift type. The reason for this implementation is due to the fact that, in the studied plant configuration, the sensors communicate with the PLC (Programmable and Logic Controller) by the cables and pipelines, making any changes in that system, such as changing the layout of it, as well as inconveniences that arise from the nature of the site, such as the vicinity s animals presence that tend to destroy the cables for interconnection of sensors to the PLC. For software development, was used communication polling method via SMAC protocol (Simple Medium Access ControlIEEE 802.15.4 standard) in the CodeWarrior environment to which generated a firmware, loaded into the WSN s transceivers, present in the kit MC13193-EVK, (all items described above are owners of Freescale Semiconductors Inc.). The network monitoring and parameterization used in its application, was developed in LabVIEW software from National Instruments. The results were obtained through the observation of the network s behavior of sensors proposal, focusing on aspects such as: indoor and outdoor quantity of packages received and lost, general aspects of reliability in data transmission, coexistence with other types of wireless networks and power consumption under different operating conditions. The results were considered satisfactory, which showed the software efficiency in this communication system
Resumo:
Over the last decades, the digital inclusion public policies have significantly invested in the purchase of hardwares and softwares in order to offer technology to the Brazilian public teaching institutions, specifically computers and broadband Internet. However, the teachers education to handle these artefacts is put away, even though there is some demand from the information society. With that, this dissertation chooses as an object of study the digital literacy practices performed by 38 (thirty-eight) teachers in initial and continuous education by means of the extension course Literacies and technologies: portuguese language teaching and cyberculture demands. In this direction, we aim at investigating the digital literacy practices of developing teachers in three specific moments: before, while and after this extension action with the intent to (i) delineate the digital literacy practices performed by the collaborators before the formative action; (ii) to narrate the literacy events made possible by the extension course; (iii) to investigate the contributions of the education course to the collaborators teaching practice. We sought theoretical contributions in the literacy studies (BAYNHAM, 1995; KLEIMAN, 1995; HAMILTON; BARTON; IVANIC, 2000), specifically when it comes to digital literacy (COPE, KALANTZIS, 2000; BUZATO, 2001, 2007, 2009; SNYDER, 2002, 2008; LANKSHEAR & KNOBEL, 2002, 2008) and teacher education (PERRENOUD, 2000; SILVA, 2001). Methodologically, this virtual ethnography study (KOZINETS, 1997; HINE, 2000) is inserted into the field of Applied Linguistics and adopts a quali-quantitative research approach (NUNAN, 1992; DÖRNYEI, 2006). The data analysis permitted to evidentiate that (i) before the course, the digital literacy practices focused on the personal and academic dimensions of their realities at the expense of the professional dimension; (ii) during the extension action, the teachers collaboratively took part in the hybrid study sessions, which had a pedagogical focus on the use of ICTs, accomplishing the use of digital literacy practices - unknown before that; (iii) after the course, the attitude of the collaborator teachers concerning the use of ICTs on their regular professional basis had changed, once those teachers started to effectively make use of them, promoting social visibility to what was produced in the school. We also observed that teachers in initial education acted as more experienced peers in collaborative learning process, offering support scaffolding (VYGOTSKY, 1978; BRUNER, 1985) to teachers in continuous education. This occurred because of the undergraduates actualize digital literacy practices were more sophisticated, besides the fact being integrate generation Y (PRENSKY, 2001)
Resumo:
Brazil is going through the process from analogical transmission to digital transmission. This new technology, in addition to providing a high quality audio and video, also allows applications to execute on television. Equipment called Set-Top Box are needed to allow the reception of this new signal and create the appropriate environment necessary to execute applications. At first, the only way to interact with these applications is given by remote control. However, the remote control has serious usability problems when used to interact with some types of applications. This research suggests a software resources implementation capable to create a environment that allows a smartphone to interact with applications. Besides this implementation, is performed a comparative study between use remote controle and smartphones to interact with applications of digital television, taking into account parameters related to usability. After analysis of data collected by the comparative study is possible to identify which device provides an interactive experience more interesting for users
Resumo:
The North Paraíba River Estuary, located in the eastern portion of the Paraíba State, Northeast Brazil, on coordinates 34º50 00 -34º57 30 S and 6º55 00 -7º7 30 W, constitutes a fluvio-marine plain formed by the North Paraíba River and its tributaries Sanhauá, Paroeira, Mandacaru, Tiriri, Tambiá, Ribeira and Guia. This estuary comprises an area of about 260 km2. Increasing human demands on the estuary area and inadequate environment managing have generated conflicts. The present work main purpose is to evaluate the geodynamic evolution of the North Paraíba River Estuary in the period from 1969 to 2001, using digital image processing techniques, thematic digital cartography and multitemporal data integration, combined to geological-geophysical field surveys. The SUDENE cartographic database, converted to digital format were, used to obtain occupation and topographic maps from 1969 and to generate a Digital Elevation Model (DEM). Digital Landsat 7 ETM+ and Spot HRVIR-PAN satellite images interpretation allowed the environmental characterization of the estuary. The most important digital processing results were achieved color composites RGB 5-4-3, 5-3-1, 5-2-NDWI and band ratio 7/4-5/3-4/2, 5/7-3/1-5/4). In addition the fusion image technique RGBI was used by the inclusion of the Spot HRVRI and Landsat 7 ETM+ panchromatic band on I layer with RGB triplets 5-4-3, 5-3-1 and 5/7-3/1-5/4. The DEM and digital images integration allowed the identification of seven geomorphological units: coastal tableland, flowing tray, tide plain, fluvial terrace, submerged dune, beach plain and beach). Both Side Scan Sonar and Echosound were used to analyse underwater surface and bedforms of the estuarine channel, sand predominance (fine to very fine) and 2D dune features 5 m wide and 0.5 m height. This investigation characterized the estuary as an environment dominated by regimen of average flow. The channel depth varies between 1 m and 11 m, being this last quota reached in the area of Porto de Cabedelo. The chanel estuary is relatively shallow, with erosion evidences mainly on its superior portion, attested by sand banks exposed during the low tide. Multitemporal digital maps from 1969 and 2001 integration were obtained through geoprocessing techniques, resulting the geodynamic evolution of the estuary based on landuse, DEM geomorphology and bathymetric maps
Resumo:
The use of the maps obtained from remote sensing orbital images submitted to digital processing became fundamental to optimize conservation and monitoring actions of the coral reefs. However, the accuracy reached in the mapping of submerged areas is limited by variation of the water column that degrades the signal received by the orbital sensor and introduces errors in the final result of the classification. The limited capacity of the traditional methods based on conventional statistical techniques to solve the problems related to the inter-classes took the search of alternative strategies in the area of the Computational Intelligence. In this work an ensemble classifiers was built based on the combination of Support Vector Machines and Minimum Distance Classifier with the objective of classifying remotely sensed images of coral reefs ecosystem. The system is composed by three stages, through which the progressive refinement of the classification process happens. The patterns that received an ambiguous classification in a certain stage of the process were revalued in the subsequent stage. The prediction non ambiguous for all the data happened through the reduction or elimination of the false positive. The images were classified into five bottom-types: deep water; under-water corals; inter-tidal corals; algal and sandy bottom. The highest overall accuracy (89%) was obtained from SVM with polynomial kernel. The accuracy of the classified image was compared through the use of error matrix to the results obtained by the application of other classification methods based on a single classifier (neural network and the k-means algorithm). In the final, the comparison of results achieved demonstrated the potential of the ensemble classifiers as a tool of classification of images from submerged areas subject to the noise caused by atmospheric effects and the water column
Resumo:
The telecommunications industry has experienced recent changes, due to increasing quest for access to digital services for data, video and multimedia, especially using the mobile phone networks. Recently in Brazil, mobile operators are upgrading their networks to third generations systems (3G) providing to users broadband services such as video conferencing, Internet, digital TV and more. These new networks that provides mobility and high data rates has allowed the development of new market concepts. Currently the market is focused on the expansion of WiMAX technology, which is gaining increasingly the market for mobile voice and data. In Brazil, the commercial interest for this technology appears to the first award of licenses in the 3.5 GHz band. In February 2003 ANATEL held the 003/2002/SPV-ANATEL bidding, where it offered blocks of frequencies in the range of 3.5 GHz. The enterprises who purchased blocks of frequency were: Embratel, Brazil Telecom (Vant), Grupo Sinos, Neovia and WKVE, each one with operations spread in some regions of Brazil. For this and other wireless communications systems are implemented effectively, many efforts have been invested in attempts to developing simulation methods for coverage prediction that is close to reality as much as possible so that they may become believers and indispensable tools to design wireless communications systems. In this work wasm developed a genetic algorithm (GA's) that is able to optimize the models for predicting propagation loss at applicable frequency range of 3.5 GHz, thus enabling an estimate of the signal closer to reality to avoid significant errors in planning and implementation a system of wireless communication
Resumo:
Currently, there are several power converter topologies applied to wind power generation. The converters allow the use of wind turbines operating at variable speed, enabling better use of wind forces. The high performance of the converters is being increasingly demanded, mainly because of the increase in the power generation capacity by wind turbines, which gave rise to various converter topologies, such as parallel or multilevel converters. The use of converters allow effective control of the power injected into the grid, either partially, for the case using partial converter, or total control for the case of using full converter. The back-to-back converter is one of the most used topologies in the market today, due to its simple structure, with few components, contributing to robust and reliable performance. In this work, is presented the implementation of a wind cogeneration system using a permanent magnet synchronous generator (PMSG) associated with a back-to-back power converter is proposed, in order to inject active power in an electric power system. The control strategy of the active power delivered to the grid by cogeneration is based on the philosophy of indirect control
Resumo:
This work shows a integrated study of modern analog to fluvial reservoirs of Açu Formation (Unit 3). The modern analog studied has been Assu River located in the same named city, Rio Grande do Norte State, Northeast of Brazil. It has been developed a new methodology to parameterizating the fluvial geological bodies by GPR profile (by central frequency antennas of 50, 100 and 200 MHz). The main parameters obtained were width and thickness. Still in the parameterization, orthophotomaps have been used to calculate the canal sinuosity and braided parameters of Assu River. These information are integrated in a database to supply input data in 3D geological models of fluvial reservoirs. It was made an architectural characterization of the deposit by trench description, GPR profile interpretation and natural expositions study to recognize and describe the facies and its associations, external and internal geometries, boundary surfaces and archtetural elements. Finally, a three-dimensional modeling has been built using all the acquired data already in association with real well data of a reservoir which Rio Assu is considered as analogous. Facies simulations have been used simple kriging (deterministic algorithm), SIS and Boolean (object-based, both stochastics). And, for modeling porosities have used the stochastic algorithm SGS
Resumo:
The humanity reached a time of unprecedented technological development. Science has achieved and continues to achieve technologies that allowed increasingly to understand the universe and the laws which govern it, and also try to coexist without destroying the planet we live on. One of the main challenges of the XXI century is to seek and increase new sources of clean energy, renewable and able to sustain our growth and lifestyle. It is the duty of every researcher engage and contribute in this race of energy. In this context, wind power presents itself as one of the great promises for the future of electricity generation . Despite being a bit older than other sources of renewable energy, wind power still presents a wide field for improvement. The development of new techniques for control of the generator along with the development of research laboratories specializing in wind generation are one of the key points to improve the performance, efficiency and reliability of the system. Appropriate control of back-to-back converter scheme allows wind turbines based on the doubly-fed induction generator to operate in the variable-speed mode, whose benefits include maximum power extraction, reactive power injection and mechanical stress reduction. The generator-side converter provides control of active and reactive power injected into the grid, whereas the grid-side converter provides control of the DC link voltage and bi-directional power flow. The conventional control structure uses PI controllers with feed-forward compensation of cross-coupling dq terms. This control technique is sensitive to model uncertainties and the compensation of dynamic dq terms results on a competing control strategy. Therefore, to overcome these problems, it is proposed in this thesis a robust internal model based state-feedback control structure in order to eliminate the cross-coupling terms and thereby improve the generator drive as well as its dynamic behavior during sudden changes in wind speed. It is compared the conventional control approach with the proposed control technique for DFIG wind turbine control under both steady and gust wind conditions. Moreover, it is also proposed in this thesis an wind turbine emulator, which was developed to recreate in laboratory a realistic condition and to submit the generator to several wind speed conditions.
Resumo:
In the shallow continental shelf in Northeastern Rio Grande do Norte - Brazil, important underwater geomorphological features can be found 6km from the coastline. They are coral reefs, locally known as “parrachos”. The present study aims to characterize and analyze the geomorphological feature as well as the ones of the benthic surface, and the distribution of biogenic sediments found in parrachos at Rio do Fogo and associated shallow platforms, by using remote sensing products and in situ data collections. This was made possible due to sedimentological, bathymetric and geomorphological maps elaborated from composite bands of images from the satellite sensors ETM+/Landsat-7, OLI/Landsat-8, MS/GeoEye and PAN/WordView-1, and analysis of bottom sediments samples. These maps were analyzed, integrally interpreted and validated in fieldwork, thus permitting the generation of a new geomorphological zoning of the shallow shelf in study and a geoenvironmental map of the Parrachos in Rio do Fogo. The images used were subject to Digital Image Processing techniques. All obtained data and information were stored in a Geographic Information System (GIS) and can become available to the scientific community. This shallow platform has a carbonate bottom composed mostly by algae. Collected and analyzed sediment samples can be classified as biogenic carbonatic sands, as they are composed 75% by calcareous algae, according to the found samples. The most abundant classes are green algae, red algae, nonbiogenic sediments (mineral grains), ancient algae and molluscs. At the parrachos the following was mapped: Barreta Channel, intertidal reefs, submerged reefs, the spur and grooves, the pools, the sandy bank, the bank of algae, sea grass, submerged roads and Rio do Fogo Channel. This work presents new information about geomorphology and evolution in the study area, and will be guiding future decision making in the handling and environmental management of the region
Resumo:
In the current work are presented the results about the study of digital mapping of analogs referents the fluvial oil reservoirs in the Açu Formation. With the regional recognizing in the south corner of Potiguar Basin was selected a area of 150 Km square in the west of Assu city. In this area was chosen the outcrops for the digital mapping and from the data fields and remote sensors were done the depositional architectural for the fluvial deposits, which it was named coarse meandering fluvial systems. In the deposits were individualized 3 (three) fluvial cycles, which they was separated by bounding surface of fifth order. Such cycles are preferentially sandy, with fining-upward sequence finished in flood plain deposits. Inner of the sandy levels of the filling channels were characterized least cycles, normaly incomplete, constituted by braided sandy bodies and bounding surfaces of fourth order. In the mapped area was chosen a outcrop with great exposition, where it was possible to see tipical deposits of filling channel and was in this outcrop that was done the digital mapping. In this outcrop was used diverse technics and tools, which they integrated sedimentological, altimetric (GPS, Total Station), LIDAR (Light Detection and Ranging), digital photomosaic of high resolution and of the inner geometries (Ground Penetration Radar) data sets. For the integrating, interpretation and visualization of data was used software GoCAD®. The final product of the outcrop digital mapping was the photorealistic model of part of the cliff (or slope) because the observed reflectors in the radargrams were absents. A part of bar oblique accretion was modeled according to GPR gride of 200x200 meters in the alluvial Assu river probable recent analog. With the data of inner geometries was developed the three-dimentional sedimentary architectural, where it was possible characterize sand sheet deposits and many hierarchy of braided channels. At last, simulations of sedimentary geometries and architectures of the Potiguar Basin Fluvial Reservoirs were done with PetBool software, in order to understand the capacity of this program in simulations with a lot of numbers of conditioning wells. In total, 45 simulations was acquired, where the time and the channel numbers increase in relation of the conditioning wells quantity. The deformation of the meanders was detected from the change of simulated dominion dimensions. The presence of this problem was because the relationship between the simulated dominion and the width of the meander
Resumo:
This thesis was elaborated in the scenario of Digital Metropolis Institute (IMD) – a supplementary unit at the Federal University of Rio Grande do Norte in the training of personnel with technical and higher level courses whose technical level training is associated with a process of digital inclusion, with the purpose of attracting young people to this area, with emphasis on Software and Hardware Development. It aims to investigate the cognitive change of young apprentice on technological education and his/her entrance into the labor market, through the formation and the social inclusion proposed by the Instituto Metrópole Digital; understanding the juvenile subjectivity production through the Instituto Metrópole Digital’s education by performance in the labor market; recognizing the Brazilian professional qualification public policies for youth and identifying the role of Tutoring in the learning process during the course of formation of the young apprentice of the technological education proposed by the Instituto Metrópole Digital.The clipping of the object of investigation was the process of cognitive change and constitution of subjectivity of the young apprentice in information technology (IT) in the IMD. It was searched support in theory Freireana as proposal that problematizes the policies and the process of formation and professional qualification, in the perspective of a citizen and liberating consciousness. By qualitative and ethnographic nature, descriptive-explanatory, it counts with the participation of young people, high school students from public and private schools, aged between 15 and 18 years. There are strong aspects: a cognitive change on the young apprentice of technological education onto overdrive high school as the student of the Instituto Metrópole Digital; it happened the social integration for those who remain in the course, both in the neighborhood where they reside and at school where he attended high school, the young man is recognized and becomes reference to other young, favoring him a life projection which when the activities of mentoring is learning motivator, it exerts a positive influence to the young on the continuity of studies, it provides intellectual and institutional affiliation and continuity in the investments to the academic life for a better insertion in the labor market, which refers to the modification of the life project-invest in academic training, in exchange for a technical job in the labor market. There are weak aspects: the absence of professor in the course, in his most important role, which involves awareness of his/her condition in action, in explicit position that the professional practice constitutes as this constitution requires reciprocity of its students and the context in which it operates; fragile formation of mentoring, absence of dialogues in the classroom that favors the formation of subject learning, mainly in guiding action, mediator of the young; There is a lack of methodological proposal to develop real projects on the labor market with problem solving and collaborative learning. It considers that without converting information into knowledge cannot discern clearly enough that there is no direct causal relationship between Professional and technological Education and the level of employability of the young worker certificate. It suggests to the evasion: a greater knowledge of the reality of the student of the Institute Metropolis Digital; better knowledge of youth and their expectations of life project; the Tutoring will be Teacher-tutor; investing in employability conditions effective the young into the labor market.