Avaliação dos modelos de predição de propagação para telefonia móvel celular na cidade do Natal

The development of wireless telecommunication in the last years has been great. It has been taking academics to conceive new ideas and techniques. Their aims are to increase the capacity and the quality of the system s services. Cells that are smaller every time, frequencies that are every time higher and environments that get more and more complex, all those facts deserve more accurate models the propagation prediction techniques are inserted in this context and results with a merger of error that is compatible with the next generations of communication systems. The objective of this Work is to present results of a propagation measurement campaign, aiming at pointing the characteristics of the mobile systems covering in the city of Natal (state of Rio Grande do Norte, Brazil). A mobile laboratory was set up, using the infra-structure available and frequently used by ANATEL. The measures were taken in three different areas: one characterized by high buildings, high relief, presence of trees and towers of different highs. These areas covered the city s central zone, a suburban / rural zone and a section of coast surrounded by sand dunes. It is important to highlight that the analysis was made taking into consideration the actual reality of cellular systems with covering ranges by reduced cells, with the intent of causing greater re-use of frequencies and greater capacity of telephone traffic. The predominance of telephone traffic by cell in the city of Natal occurs within a range inferior to 3 (three) km from the Radio-Base Station. The frequency band used was 800 MHz, corresponding to the control channels of the respective sites, which adopt the FSK modulation technique. This Dissertation starts by presenting a general vision of the models used for predicting propagation. Then, there is a description of the methodology used in the measuring, which were done using the same channels of control of the cellular system. The results obtained were compared with many existing prediction models, and some adaptations were developed by using regression techniques trying to obtain the most optimized solutions. Furthermore, according to regulations from the old Brazilian Holding Telebrás, a minimum covering of 90% of a determined previously area, in 90% of the time, must be obeyed when implanting cellular systems. For such value to be reached, considerations and studies involving the specific environment that is being covered are important. The objective of this work is contribute to this aspect

Ambiente de simulação híbrido integrando hysys e rede industrial Foundation Fieldbus aplicado ao controle de uma coluna de destilação

The main purpose of this work is to develop an environment that allows HYSYS R chemical process simulator communication with sensors and actuators from a Foundation Fieldbus industrial network. The environment is considered a hybrid resource since it has a real portion (industrial network) and a simulated one (process) with all measurement and control signals also real. It is possible to reproduce different industrial process dynamics without being required any physical network modification, enabling simulation of some situations that exist in a real industrial environment. This feature testifies the environment flexibility. In this work, a distillation column is simulated through HYSYS R with all its variables measured and controlled by Foundation Fieldbus devices

Estudo de antenas patches de microfita miniaturizadas em banda larga para aplicação em dispositivos móveis e portáteis

This work presents techniques used to design and manufacture microstrip patch antennas for applications in portable and mobile devices. To do so, are evaluated several factors that can influence the performance of microstrip patch antennas. Miniaturization techniques are studied and employed in order to apply this type of antenna in mobile and / or mobile. The theories of microstrip patch antennas are addressed by analyzing characteristics such as constitution, kinds of patches, substrates, feeding methods, analysis methods, the main advantages and disadvantages and others. Techniques for obtaining broadband microstrip patch antennas were surveyed in literature and exemplified mainly by means of simulations and measurements. For simulations of the antennas was used the commercial software . In addition, antenna miniaturization techniques have been studied as a main concern the fundamental limits of antennas with special attention to electrically small antennas because they are directly linked to the microstrip patch antennas. Five design antennas are proposed to demonstrate the effectiveness of techniques used to obtain the microstrip patch antennas broadband and miniaturized for use in mobile devices and/or portable. For this, the proposed antennas were simulated, built and measured. The antennas are proposed to be used in modern systems of wireless communications such as DTV, GPS, IEEE 802.16, IEEE 802.11, etc. The simulations of the antennas were made in business and computer programs. The measured results were obtained with a parser Vector of networks of the Rhode and Schwarz model ZVB 14

Redes neurais artificiais no ambiente de redes industriais foundation fieldbus usando blocos funcionais padrões

Industrial automation networks is in focus and is gradually replacing older architectures of systems used in automation world. Among existing automation networks, most prominent standard is the Foundation Fieldbus (FF). This particular standard was chosen for the development of this work thanks to its complete application layer specification and its user interface, organized as function blocks and that allows interoperability among different vendors' devices. Nowadays, one of most seeked solutions on industrial automation are the indirect measurements, that consist in infering a value from measures of other sensors. This can be made through implementation of the so-called software sensors. One of the most used tools in this project and in sensor implementation are artificial neural networks. The absence of a standard solution to implement neural networks in FF environment makes impossible the development of a field-indirect-measurement project, besides other projects involving neural networks, unless a closed proprietary solution is used, which dos not guarantee interoperability among network devices, specially if those are from different vendors. In order to keep the interoperability, this work's goal is develop a solution that implements artificial neural networks in Foundation Fieldbus industrial network environment, based on standard function blocks. Along the work, some results of the solution's implementation are also presented

Análise de desempenho experimental de redes IEEE 802.3.

The Ethernet technology dominates the market of computer local networks. However, it was not been established as technology for industrial automation set, where the requirements demand determinism and real-time performance. Many solutions have been proposed to solve the problem of non-determinism, which are based mainly on TDMA (Time Division Multiple Access), Token Passing and Master-Slave. This work of research carries through measured of performance that allows to compare the behavior of the Ethernet nets when submitted with the transmissions of data on protocols UDP and RAW Ethernet, as well as, on three different types of Ethernet technologies. The objective is to identify to the alternative amongst the protocols and analyzed Ethernet technologies that offer to a more satisfactory support the nets of the industrial automation and distributed real-time application

Um modelo de unidade de medida inercial utilizando três acelerômetros triaxiais

No espaço tridimensional, um corpo rígido qualquer pode efetuar translações e ou rotações em relação a cada um de seus eixos. Identificar com precisão o deslocamento realizado por um corpo é fundamental para alguns tipos de sistemas em engenharia. Em sistemas de navegação inercial tradicionais, utilizam-se acelerômetros para reconhecer a aceleração linear e giroscópios para reconhecer a velocidade angular registrada durante o deslocamento. O giroscópio, entretanto, é um dispositivo de custo mais elevado e com alto consumo de energia quando comparado a um acelerômetro. Essa desvantagem deu origem a pesquisas a respeito de sistemas e unidades de medidas inerciais que não utilizam giroscópios. A ideia de utilizar apenas acelerômetros para calcular o movimento linear e angular surgiu no início da década de 60 e vem se desenvolvendo através de modelos que variam no número de sensores, na maneira como estes são organizados e no modelo matemático que é utilizado para derivar o movimento do corpo. Esse trabalho propõe um esquema de configuração para construção de uma unidade de medida inercial que utiliza três acelerômetros triaxiais. Para identificar o deslocamento de um corpo rígido a partir deste esquema, foi utilizado um modelo matemático que utiliza apenas os nove sinais de aceleração extraídos dos três sensores. A proposta sugere que os sensores sejam montados e distribuídos em formato de L . Essa disposição permite a utilização de um único plano do sistema de coordenadas, facilitando assim a instalação e configuração destes dispositivos e possibilitando a implantação dos sensores em uma única placa de circuito integrado. Os resultados encontrados a partir das simulações iniciais demonstram a viabilidade da utilização do esquema de configuração proposto

Controlador adaptativo backstepping a estrutura variavel com Observadores de estado

This research aims at developing a variable structure adaptive backstepping controller (VS-ABC) by using state observers for SISO (Single Input Single Output), linear and time invariant systems with relative degree one. Therefore, the lters were replaced by a Luenberger Adaptive Observer and the control algorithm uses switching laws. The presented simulations compare the controller performance, considering when the state variables are estimated by an observer, with the case that the variables are available for measurement. Even with numerous performance advantages, adaptive backstepping controllers still have very complex algorithms, especially when the system state variables are not measured, since the use of lters on the plant input and output is not something trivial. As an attempt to make the controller design more intuitive, an adaptive observer as an alternative to commonly used K lters can be used. Furthermore, since the states variables are considered known, the controller has a reduction on the dependence of the unknown plant parameters on the design. Also, switching laws could be used in the controller instead of the traditional integral adaptive laws because they improve the system transient performance and increase the robustness against external disturbances in the plant input

Métodos estatísticos recursivos aplicados ao problema de estimação de vazão de gás em plantas de Plunger-lift

This work has as main objective to find mathematical models based on linear parametric estimation techniques applied to the problem of calculating the grow of gas in oil wells. In particular we focus on achieving grow models applied to the case of wells that produce by plunger-lift technique on oil rigs, in which case, there are high peaks in the grow values that hinder their direct measurement by instruments. For this, we have developed estimators based on recursive least squares and make an analysis of statistical measures such as autocorrelation, cross-correlation, variogram and the cumulative periodogram, which are calculated recursively as data are obtained in real time from the plant in operation; the values obtained for these measures tell us how accurate the used model is and how it can be changed to better fit the measured values. The models have been tested in a pilot plant which emulates the process gas production in oil wells

Desenvolvimento de estruturas integradas de filtros e antenas para aplicações em sistemas de comunicações sem fio

This paper presents a study of the integration of filters and microstrip antennas, yielding devices named as filtennas for applications in wireless communications systems. The design of these structures is given from the observation of filtennas based integration between horn antennas and frequency selective surfaces (FSS), used in the band X. The choice of microstrip line structures for the development of a new configuration filtennas justifies the wide application of these transmission lines, in recent decades, always resulting in the production of circuit structures with planar light-weight, compact size, low cost, easy to construct and particularly easy to integrate with other microwave circuits. In addition, the antenna structure considered for the composition of filtennas consists of a planar monopole microstrip to microstrip filters integrated in the feed line of the antenna. In particular, are considered elliptical monopole microstrip (operating in UWB UWB) microstrip filters and (in structures with associated sections in series and / or coupled). In addition, the monopole microstrip has a proper bandwidth and omnidirectional radiation pattern, such that its integration with microstrip filters results in decreased bandwidth, but with slight changes in the radiation pattern. The methods used in the analysis of monopoles, and filters were filtennas finite elements and moments by using commercial software Ansoft Designer and HFSS Ansoft, respectively. Specifically, we analyze the main characteristics of filtennas, such as radiation pattern, gain and bandwidth. Were designed, constructed and measures, several structures filtennas, for validation of the simulated results. Were also used computational tools (CAD) in the process of building prototypes of planar monopoles, filters and filtennas. The prototypes were constructed on substrates of glass-fiber (FR4). Measurements were performed at the Laboratory for Telecommunications UFRN. Comparisons were made between simulated and measured, and found good agreement in the cases considered

Implementação de conversor de polarização linear-circular para antenas de microfita usando metasuperfícies

This work aims to propose a new model of metasurface with simplified basic cell, able to convert linearly polarized signals generated by planar antenna array in circularly polarized signals, for the ISM frequency band (2.45 GHz), with good bandwidth of return loss and axial ratio. To study the behavior of the proposed structure, the metasurface is coupled to three different structures. First, initial tests are made with the metasurface coupled to a microstrip antenna in its simple configuration. Then the metasurface is coupled to an array with two elements of patch type. And later it is coupled to an optimized array, that uses a stub in its main feed, to get a better impedance matching. The structures are analyzed numerically through Ansoft HFSS™, and to validate these results, the structures are characterized experimentally. The characteristics of transmissions simulated and measures are presented. A good agreement between simulated and measured results was obtained. The structure proposed here has the advantage of meeting the desired characteristics, with a simple geometry to be built using a low-cost substrate (FR-4).

Implementação de conversor de polarização linear-circular para antenas de microfita usando metasuperfícies

This work aims to propose a new model of metasurface with simplified basic cell, able to convert linearly polarized signals generated by planar antenna array in circularly polarized signals, for the ISM frequency band (2.45 GHz), with good bandwidth of return loss and axial ratio. To study the behavior of the proposed structure, the metasurface is coupled to three different structures. First, initial tests are made with the metasurface coupled to a microstrip antenna in its simple configuration. Then the metasurface is coupled to an array with two elements of patch type. And later it is coupled to an optimized array, that uses a stub in its main feed, to get a better impedance matching. The structures are analyzed numerically through Ansoft HFSS™, and to validate these results, the structures are characterized experimentally. The characteristics of transmissions simulated and measures are presented. A good agreement between simulated and measured results was obtained. The structure proposed here has the advantage of meeting the desired characteristics, with a simple geometry to be built using a low-cost substrate (FR-4).

Arquitetura para o desenvolvimento de unidades de medição fasorial sincronizada no monitoramento a nível de distribuição

This work presents a low cost architecture for development of synchronized phasor measurement units (PMU). The device is intended to be connected in the low voltage grid, which allows the monitoring of transmission and distribution networks. Developments of this project include a complete PMU, with instrumentation module for use in low voltage network, GPS module to provide the sync signal and time stamp for the measures, processing unit with the acquisition system, phasor estimation and formatting data according to the standard and finally, communication module for data transmission. For the development and evaluation of the performance of this PMU, it was developed a set of applications in LabVIEW environment with specific features that let analyze the behavior of the measures and identify the sources of error of the PMU, as well as to apply all the tests proposed by the standard. The first application, useful for the development of instrumentation, consists of a function generator integrated with an oscilloscope, which allows the generation and acquisition of signals synchronously, in addition to the handling of samples. The second and main, is the test platform, with capabality of generating all tests provided by the synchronized phasor measurement standard IEEE C37.118.1, allowing store data or make the analysis of the measurements in real time. Finally, a third application was developed to evaluate the results of the tests and generate calibration curves to adjust the PMU. The results include all the tests proposed by synchrophasors standard and an additional test that evaluates the impact of noise. Moreover, through two prototypes connected to the electrical installation of consumers in same distribution circuit, it was obtained monitoring records that allowed the identification of loads in consumer and power quality analysis, beyond the event detection at the distribution and transmission levels.

Medidas de concentração de radônio proveniente de argamassas de cimento portland, gesso e fosfogesso

Portland cement being very common construction material has in its composition the natural gypsum. To decrease the costs of manufacturing, the cement industry is substituting the gypsum in its composition by small quantities of phosphogypsum, which is the residue generated by the production of fertilizers and consists essentially of calcium dihydrate and some impurities, such as fluoride, metals in general, and radionuclides. Currently, tons of phosphogypsum are stored in the open air near the fertilizer industries, causing contamination of the environment. The 226 Ra present in these materials, when undergoes radioactive decay, produces the 222Rn gas. This radioactive gas, when inhaled together with its decay products deposited in the lungs, produces the exposure to radiation and can be a potential cause of lung cancer. Thus, the objective of this study was to measure the concentration levels of 222Rn from cylindrical samples of Portland cement, gypsum and phosphogypsum mortar from the state of Paraná, as well as characterizer the material and estimate the radon concentration in an environment of hypothetical dwelling with walls covered by such materials. Experimental setup of 222Rn activity measurements was based on AlphaGUARD detector (Saphymo GmbH). The qualitative and quantitative analysis was performed by gamma spectrometry and EDXRF with Au and Ag targets tubes (AMPTEK), and Mo target (ARTAX) and mechanical testing with x- ray equipment (Gilardoni) and the mechanical press (EMIC). Obtained average values of radon activity from studied materials in the air of containers were of 854 ± 23 Bq/m3, 60,0 ± 7,2 Bq/m3 e 52,9 ± 5,4 Bq/m3 for Portland cement, gypsum and phosphogypsum mortar, respectively. These results extrapolated into the volume of hypothetical dwelling of 36 m3 with the walls covered by such materials were of 3366 ± 91 Bq/m3, 237 ± 28 Bq/m3 e 208 ± 21 Bq/m3for Portland cement, gypsum and phosphogypsum mortar, respectively. Considering the limit of 300 Bq/m3 established by the ICRP, it could be concluded that the use of Portland cement plaster in dwellings is not secure and requires some specific mitigation procedure. Using the results of gamma spectrometry there were calculated the values of radium equivalent activity concentrations (Raeq) for Portland cement, gypsum and phosphogypsum mortar, which were obtained equal to 78,2 ± 0,9 Bq/kg; 58,2 ± 0,9 Bq/kg e 68,2 ± 0,9 Bq/kg, respectively. All values of radium equivalent activity concentrations for studied samples are below the maximum level of 370 Bq/kg. The qualitative and quantitative analysis of EDXRF spectra obtained with studied mortar samples allowed to evaluate quantitate and the elements that constitute the material such as Ca, S, Fe, and others.

Síntese e caracterização de ferrita ni-zn pelo método dos precursores poliméricos calcinada por energia de microondas

Magnetic ceramics have been widely investigated, especially with respect to intrinsic and extrinsic characteristics of these materials. Among the magnetic ceramic materials of technological interest, there are the ferrites. On the other hand, the thermal treatment of ceramic materials by microwave energy has offered various advantages such as: optimization of production processes, high heat control, low consumption of time and energy among others. In this work were synthesized powders of Ni-Zn ferrite with compositions Ni1- xZnxFe2O4 (0.25 ≤ x ≤ 0.75 mols) by the polymeric precursor route in two heat treatment conditions, conventional oven and microwave energy at 500, 650, 800 and 950°C and its structural, and morphological imaging. The materials were characterized by thermal analysis (TG/ DSC), X-ray diffraction (XRD), absorption spectroscopy in the infrared (FTIR), scanning electron microscopy (SEM), X-ray spectroscopy and energy dispersive (EDS) and vibrating sample magnetometry (VSM). The results of X-ray diffraction confirmed the formation of ferrite with spinel-type cubic structure. The extrinsic characteristics of the powders obtained by microwave calcination and influence significantly the magnetic behavior of ferrites, showing particles ferrimagnéticas characterized as soft magnetic materials (soft), is of great technological interest. The results obtained led the potential application of microwave energy for calcining powders of Ni-Zn ferrite

Fatores de decisão da adoção do gás natural na geração de energia elétrica em pequena escala em postos de combustíveis: um estudo de anális de decusão usando o processo de hierarquia analítica AHP

A modeling of criterias and alternatives is through and applied a questionnaire based on method AHP to proprietors of gas stations. The considered alternatives had been the maintenance of the current state with electric energy of the deliverer and the generation in small scale based on the natural gas. The used criteria had been Cost of the Investment, Final Cost of the Energy, Operational cost, Ambient Benefits, Risk and Variation of Costs. The study it was carried through in the city of Natal, RN in ranks that make use of the natural as for resale, where the generation alternative on the basis of the available gas is present. The main results evidence in a dimension the viability of use of method AHP with questionnaire by means of validation of the judgments with analysis of variance beyond proper the normal mechanisms of analysis of consistency to the method. The main results of the analysis help to show that in this in case that the profile of models of criteria and judgments of the actors is similar, with the final evidence of that it has a dominance of the maintenance of the energy of the deliverer. The main criterion to influence this decision was the risk