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ItemDissertação de mestrado Estudo do comportamento de transistores MISHEMT com diferentes dielétricos de porta(Universidade Estadual Paulista (Unesp), 22-05-27) Carmo, Genilson Julião do; Agopian, Paula Ghedini Der [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais Este trabalho tem como objetivo o estudo do comportamento elétrico do transistor MISHEMT (Isolante/AlGaN/AlN/GaN) a partir dos parâmetros elétricos do mesmo. O comportamento do transistor foi estudado variando-se o tipo do material isolante de porta, as dimensões do dispositivo (comprimento da porta, distancias porta/fonte e porta/dreno, profundidade dos contatos de fonte e dreno) e temperaturas de funcionamento do dispositivo. Como isolantes de porta, foram utilizados os materiais Si3N4 de 2nm de espessura e Al2O3 com 10nm de espessura. Em uma primeira análise, variou-se o comprimento do canal do transistor de 200nm até 600nm. Os dispositivos foram analisados operando em temperaturas variando de 25ºC à 200ºC. Nas análises seguintes, o comportamento do transistor foi estudado variando-se as distâncias de porta/fonte (LGS) e porta/dreno (LGD) e a profundidade dos contatos de fonte e dreno. As curvas de transferência para o dispositivo com isolante de Al2O3 apresentaram histerese, enquanto a histerese pode ser negligenciada para o dispositivo com isolante de porta Si3N4. Quando analisada a tensão de limiar (VT), o transistor com isolante de porta Si3N4 apresenta valores menos negativos de VT, melhor comportamento aos efeitos de canal curto e melhores respostas ao DIBL (Drain Induced Barrier Lowering). No entanto, quando a análise de VT inclui os efeitos da variação da temperatura, enquanto o transistor de Al2O3 apresentou um comportamento convencional (redução de VT com o aumento da temperatura), um comportamento não esperado ocorreu para os transistores com Si3N4. Este comportamento anômalo deve-se a uma dupla condução que foi observada mais facilmente na curva da transcondutância. Essa dupla condução parece estar relacionada às diferentes componentes de corrente do dispositivo estudado. Essa dupla condução da curva de gm sugere que a corrente total do dispositivo parece ser influenciada pela condução MOS e pela condução 2DEG (Two-dimensional electron gas). Esses canais de condução de corrente acontecem nas interfaces das junções dos materiais. Apesar do transistor de Si3N4 apresentar maiores valores de corrente de fuga pela porta, o que parece estar relacionado com a espessura do isolante, o transistor Al2O3 apresenta um importante auto aquecimento do dispositivo, sendo inapropriado para aplicações analógicas. O potencial do transistor com isolante de Si3N4 para aplicações analógicas foi avaliado e o mesmo apresentou bom desempenho do ganho intrínseco de tensão e mesmo com a variação da temperatura o dispositivo apresentou uma boa estabilidade térmica. Dispositivos com profundidade de contatos alcançando o topo do material AlGaN apresentaram maior degradação de gm e IDS em comparação com os dispositivos com contatos alcançando o material AlN. Quanto menores as distâncias LGS e LGD, menor a degradação de IDS e gm. O comportamento de IDS e gm pode ser explicado pelas resistências séries associadas as configurações estudadas. As curvas das bandas de condução e concentração de elétrons sugerem três prováveis canais de condução associados ao dispositivo estudado.Exibir mais ItemTrabalho apresentado em evento Characterization of grazing bifurcation in airfoils with control surface freeplay nonlinearity(European Assoc Structural Dynamics, 2014-01-01) Vasconcellos, Rui M. G. [UNESP]; Abdelkefi, Abdessattar; Marques, Flavio D.; Hajj, Muhammad R.; Universidade Estadual Paulista (Unesp); Virginia Tech; Universidade de São Paulo (USP)Exibir mais A variety of nonlinear features is obtained from aeroelastic systems with discontinuous nonlinearity motivates investigations that may support future applications in controls design, flutter prediction problems, and energy harvesting exploration. The freeplay nonlinearity leads to bifurcations and abrupt response changes which can result in undesirable or catastrophic responses. Grazing bifurcations of limit cycles are one of the most commonly found discontinuity-induced bifurcations (DIBs) and are caused by a limit cycle that becomes tangent to the discontinuity boundary of the available piecewise-smooth function. The abrupt transition from periodic to aperiodic is directly related with the discontinuous nature of freeplay nonlinearity. In fact, recent studies in different areas discussed the presence of grazing bifurcations and the associated behavior changes. These abrupt transitions caused by grazing bifurcations are different from the well-known routes to chaos. In this work, a nonlinear analysis based on modern methods of nonlinear dynamics, such as power spectra and phase portraits is performed to characterize the sudden transitions in a three-degree of freedom aeroelastic system with freeplay nonlinearity in the flap degree of freedom. The results show that the main transition is due to a grazing bifurcation.Exibir mais ItemTrabalho apresentado em evento Influence of structural nonlinearities in stall-induced aeroelastic response of pitching airfoils(European Assoc Structural Dynamics, 2014-01-01) Pereira, Daniel A.; Vasconcellos, Rui M. G. [UNESP]; Marques, Flávio D.; Universidade de São Paulo (USP); Universidade Estadual Paulista (Unesp)Exibir mais Stall-induced vibrations are a relevant aeroelastic problem for very flexible aero-structures. Helicopter blades, wind turbines, or other rotating components are severely inflicted to vibrate in stall condition during each revolution of its rotor. Despite a significant effort to model the aerodynamics associated to the stall phenomena, non-linear aeroelastic behavior prediction and analysis in such flow regime remain formidable challenges. Another source of nonlinearity with influence to aeroelastic response may be associated to structural dynamics. The combination of both separated flow aerodynamic and structural nonlinearities lead to complex dynamics, for instance, bifurcations and chaos. The purpose of this work is to present the analysis of stall-induced vibrations of an airfoil in pitching when concentrated nonlinearities are associated to its structural dynamics. Limit cycles oscillations at higher angles of attach and complex non-linear features are analyzed for different nonlinear models for concentrated restoring pitching moment. The pitching-only typical section dynamics is coupled with an unsteady aerodynamic model based on Beddoes-Leishmann semi-empirical approach to produce the proper framework for gathering time series of aeroelastic responses. The analyses are performed by checking the content of the aeroelastic responses prior and after limit cycle oscillations occur. Evolutions on limit cycles amplitudes are used to reveal bifurcation points, thereby providing important information to assess, characterize, and qualify the nonlinear behavior associated with combinations of different forms to represent concentrated pitching spring of the typical section.Exibir mais ItemArtigo Compressible modes in a square lid-driven cavity(Elsevier B.V., 2015-07-01) Bergamo, Leandro Fernandes; Gennaro, Elmer Mateus [UNESP]; Theofilis, Vassilis; Medeiros, Marcello Augusto Faraco; Universidade de São Paulo (USP); Universidade Estadual Paulista (Unesp); Universidad Politécnica de MadridExibir mais This paper studies the effect of compressibility on the linear stability of a two-dimensional lid-driven cavity flow in the subsonic regime. The base flow is generated by high fidelity direct numerical simulation and a biglobal mode instability analysis is carried out by a matrix forming approach. The eigenvalue problem is discretized by high-order finite differences and Arnoldi algorithm is used to reduce the size of the problem. The solution procedure uses sparse matrix techniques. Influence of Mach number on the modes known from incompressible calculations is presented, showing that compressibility has a stabilizing effect. New modes that appear only for compressible flows are presented and their relationship with duct acoustics is investigated.Exibir mais ItemArtigo A study of the errors of the averaged models in the restricted three-body problem in a short time scale(Springer, 2015-07-01) Domingos, Rita de Cássia [UNESP]; Prado, Antonio Fernando Bertachini de Almeida; Moraes, Rodolpho Vilhena de; Universidade Estadual Paulista (Unesp); Instituto Nacional de Pesquisas Espaciais (INPE); Universidade Federal de São Paulo (UNIFESP)Exibir mais The objective of the present research is to study the accuracy of the double- and single-averaged models that are usually considered to predict the motion of spacecrafts or celestial bodies that have their motion perturbed by a third-body. Those two models are compared with each other and then validated against the complete elliptic restricted three-body problem. Those models are developed to give a faster but general behaviour of the motion of the perturbed body in a medium or longer time scale. The researches performed here verify the accuracy of those methods for shorter time scales by showing the differences in terms of the values of the inclination and eccentricity of the perturbed body predicted by those models. Those differences are calculated both at every instant of time and as an integral over the time. The use of the integral along the time for the errors is a new form to study those differences and show a more complete comparison of the accuracy of those approximations, completing the instantaneous picture given by the usual approach of looking at the instantaneous measurement. If the value of the integral is divided by the time integration, the mean error is obtained. The results show that the single-averaged model is better in the short time scale and the difference among those models is smaller when predicting the eccentricity than the inclination. The effects of the time scale is verified by varying the study to values from 2 days up to 50 revolutions of the Moon (1,366 days). Another important point found in the present paper is the range of the eccentricities of the perturbing body that accelerates the dynamics.Exibir mais ItemTrabalho de conclusão de curso Esquemas de seleção de relay para redes cooperativas full-duplex com compartilhamento espectral do tipo underlay(Universidade Estadual Paulista (Unesp), 2018) Mucin, Daniel de Paiva [UNESP]; Olivo, Edgar Eduardo Benitez [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais In this work, the performance of different relay selection schemes is analyzed in terms of the outage probability for a cognitive relay network with underlay spectral sharing, which consists of multiple relays operating in full-duplex mode, under the decode-and-forward protocol. To this end, four relay selection criteria are considered, namely: (i) optimal selection criterion, which requires global knowledge of the channel state information of the network; and three suboptimal selection criteria, which require partial knowledge of the channel state information of the network, more specifically, based on (ii) the self- interference links inherent to full-duplex relays, (iii) the links between the source and relays, and (iv) the links between the relays and destination. An arbitrary power allo- cation between the source and the selected relay is also considered. As contributions of this work, for the proposed relay selection criteria, analytical expressions are obtained for the asymptotic outage probability at the high signal-to-noise ratio regime. From these analytical expressions, the impact of different system parameters are assessed, such as the number of relays, the average channel gain of the self-interference link, and the interfe- rence temperature imposed by the primary receiver. The obtained analytical results are validated through exhaustive Monte Carlo simulations. In addition, computer simulations are carried out to evaluate the effect of the maximum power available at the secondary nodes, as well as the variation of the power allocation factor and distance between the source and relaysExibir mais ItemTrabalho de conclusão de curso Codificação de canal para redes 5G utilizando códigos polares(Universidade Estadual Paulista (Unesp), 2018) Martão, Vanessa Beatriz [UNESP]; Oliveira, Cintya Wink de [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais Polar codes are linear block codes with low computational cost that have great potential to be used in 5G technology, due to evidence that it achieves the Shannon's channel capacity. These codes are essentially binary, being implemented in symmetric and memoryless channels. The objective of this work was study the coding and decoding strategy of the polar codes for the application in the 5G networks. To this end, we have introduced the elements of information theory and coding. After that we did a study about the channel polarization technique that separates the good channels from the bad ones. We studied coding and decoding strategies for codes, and a computational implementation to verify its efficiency. The results showed that the larger the N size of the codeword, the closer the signal is to the limit of the Shannon's channel capacity theoremExibir mais ItemTrabalho de conclusão de curso Modelo físico de linhas de transmissão: desenvolvimento em placas de circuito impresso(Universidade Estadual Paulista (Unesp), 2018) Pereira, Thainá Guimarães [UNESP]; Prado, Afonso José do [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais The objective of this work is to analyze the behavior of modules of a physical transmis-sion line model. The model uses single-phase representation based on modified π circuits. The classical π-circuit structure does not consider frequency fluency and this causes significant er-rors in the calculations of currents and voltages propagated by the line mainly in transients or for high-frequency phenomena. Thus, in the classical circuit structure π parallel RL blocks can be inserted to simulate the influence of the frequency on the transmission line parameters. In the current stage of development of the work, twenty four π circuit units were assembled in printed circuit board (PBC) and two hundred and fifty π circuit units were assembled in software HFSS for comparison. The resistance and inductance characteristics of the longitudinal param-eters were obtained as a function of frequency. The Bode (module and angle) diagrams were also obtained for the relation between the output voltage and the input voltage of the π circuit units. In the software just the Bode diagrams were obtained. One way to model the transmission lines is applying π circuit cascades. In practice, it is impossible to carry out tests in actual lines that transmit large blocks of electrical power. This model may consist of resistors, inductors and capacitors. Increasing the number of π circuits increases the accuracy of the obtained results. For a unit of the circuit π does not represent a transmission lineExibir mais ItemTrabalho de conclusão de curso Redução do nível de lóbulos laterais em arranjo de antenas 1D(Universidade Estadual Paulista (Unesp), 2018) Souza, Bruna Dias Pires de [UNESP]; Garde, Ivan Aritz Aldaya [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais Array antennas have been widely proposed to improve radiation features and to enable dynamic control of the radiation pattern through beam steering and beam forming, which are required in state-of-the-art wireless communication. However, in ultra wideband applications, as well as in photonic systems, the minimum separation distance between radiation elements is limited to several wavelengths, leading to the presence of strong side-lobes known as grating lobes. These grating lobes represent a critical impairment that prevents the adoption of these sparse array antennas in applications where crosstalk and security faults must be avoided. In this work, we numerically analyze, for the first time to our knowledge, the side-lobe level (SLL) reduction of 1D sparse antenna arrays under beam steering operation when the radiating elements are arranged non-uniformly (the separation between radiation elements is increased geometrically). The proposed method has a single parameter and, therefore, can be easily optimized and extended to higher dimensions. Numerical results reveal a SLL reduction, in the worst-case scenario (steering angles close to =2), of approximately 5 dB for a 5-element array with a total length of 6 wavelengthsExibir mais ItemTrabalho de conclusão de curso Estudo teórico e experimental de transistores de múltiplas portas fabricados em estruturas de nanofios(Universidade Estadual Paulista (Unesp), 2018) Perina, Welder Fernandes [UNESP]; Agopian, Paula Ghedini Der [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais The technological advancement of semiconductor devices is based on increasing their scalability over the years, ensuring greater performance of electronic circuits and better utilization of the occupied area by integrated circuits. However, with the continuous reduction of the devices, effects such as loss of gate control over the charges in the channel and the influence of drain bias on the threshold voltage, known as short channel effects (SCE), started appearing. The SOI (Silicon-Over-Insulator) technology allowed for a greater reduction of the dimensions of the transistors due to their greater immunity to the SCE. Continuing the technological evolution, 3D transistors have emerged, further enhancing the performance of integrated circuits (the most modern comercially) and enabling the fabrication of even smaller devices. However, it is necessary to study new technologies for the continuation of technological progress, and in this scenario, silicon nanowires appear as one of the alternatives to this evolution. In this work, it was analyzed the digital and analog parameters of Ω-gate nanowires and evaluated digital parameters such as subthershold slope, threshold voltage, maximum transconductance and Drain-Induced Barrier Lowering (DIBL). When evaluating its switching efficiency, represented by subthreshold slope, it was noted that the Ω gate nanowire reaches SS values close to the theoretical limit (60 mV/dec), at room temperature, of the MOSFET technology. By observing the maximum transconductance values, threshold voltage and DIBL, it was possible to analyze indications that the shortest devices were losing the electrostatic control, possibly because of the SCE. The largest and shortest devices presented the worst performance in the case of digital applications, but the narrowest devices showed good results such as high maximum transconductance, low threshold voltage variation with respect to the...Exibir mais ItemTrabalho de conclusão de curso Sistema de comunicação para rede de sensores sem fio aplicada ao controle ambiental(Universidade Estadual Paulista (Unesp), 2018) Fidanza, Letícia Barbosa [UNESP]; Ferreira, André Alves [UNESP]; Oliveira, José Augusto de [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais The Internet of Things (IoT)concept proposes connectivity as an agent of daily routines, making it easier to manage tasks. In the agricultural production environment, for example, the use of IoT promotes numerous benefits in control and maintenance. With the increase of the world population it becomes necessary the use of mechanisms, in order to optimize the productivity and predictability in the productive process. In this context,Wireless Sensor Networks (WSNs) are tools used for environmental control in the field. The automation of agricultural production and monitoring are necessary for rapid decision-making, increasing agricultural production beyond saving natural resources, avoiding waste with irrigation and loss of production due to climatic conditions. The greatest difficulties encountered are the lack of knowledge about the application of technologies in the agricultural sector, the infrastructure and the interoperability with other control systems for rural automation. In this way, this project intends to implement a scalable and applicable solution for both the small and the large producer. Through the survey of the main relevant aspects in the implementation of the technology in the field and the construction of an WSN capable of acquiring data such as temperature and humidity, to process and transmit to the user in an interface that facilitates the decision making and control on its planting, down cost and in a sustainable way, taking into account the conditions of the studied environment, the technical and environmental impact of the implementation of this solutionExibir mais ItemTrabalho de conclusão de curso Influência da resistência de amortecimento em transitórios eletromagnéticos utilizando cascatas de circuitos π: comparação entre diferentes estruturas(Universidade Estadual Paulista (Unesp), 2018) Santos, Melissa de Oliveira [UNESP]; Prado, Afonso José do [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais The study of transmission lines is fundamental, but it is impracticable to perform measurements on real transmission lines, so it is necessary to apply numerical models. Currently, the simplest way to model a transmission line is to use a large number of cascaded circuits. However, the results of the simulation include numerical errors and are influenced by numerical oscillations, result of the Gibbs phenomenon. Thus, a damping resistance (RD) is inserted to dampen the oscillations and reduce errors in simulations of transient electromagnetic propagation in transmission lines. Initially, the damping resistance was included in all circuits of the cascade, allowing very precise results and a very low error percentage. However, in an attempt to reduce computational simulation time without losing the precision obtained previously, tests are being performed with different circuit structures for the simulation of electromagnetic transients in transmission lines. In this work, two different cascade structures of circuits are presented and discussed, which are compared with the original structure that includes RD in all circuits of the cascade. The first one is an alternating structure, where a circuit contains RD in its structure while the other does not contain RD. In this case, the two circuit structures, with and without damping resistance, are applied alternately in the cascade representing the analyzed transmission line. The second structure does not contain the damping resistance in half of the total circuits of the model, this half being found in the central block of the cascade. Based on the results obtained, the new structures tested can not maintain the same precision and low error percentage of the original model that includes RD in all circuits of the cascade, even with the change and combination of the different parameters of the simulationExibir mais ItemTrabalho de conclusão de curso Impacto da utilização de pré-ênfase no desempenho sistêmico de um amplificador óptico paramétrico projetado para um guia de onda integrado de telurito(Universidade Estadual Paulista (Unesp), 2018) Pinto Neto, Pedro Ferreira [UNESP]; Abbade, Marcelo Luís Francisco [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais This work describes, by the use of simulations, the evaluation of performance of a two pump optical parametric amplifier (2P-OPA) designed on a tellurite waveguide using pre-emphasis power technique. The objective is to evaluate the application of the pre-emphasis power technique to minimize the power ripple at the output of the amplifier. The figures of merit used to compare the 2P-OPA performance without and with pre-emphasis are: the maximum bit error ratio (BER) achieved after each pass through the amplifier and the maximum optical span length that can be achieved when using this amplifier. The simulation software utilized is the VPItransmissionMaker™. The first setup analyzed is built to reproduce the results reported for 243 wavelength division multiplexing (WDM) signals quadrature phase shift keying (QPSK) modulated in single polarization with a 56 Gb/s bit rate for a -29 dBm input power per channel. The second setup includes the pre-emphasis onto the first setup with the addition of a block to unbalance the power signal. The pre-emphasis is made so the maximum power output per channel on the 2P-OPA is close to the average power output per channel (-10,47 dBm) when using the first setup. The BER of 13 channels, from the 243 transmitted channels, is estimated and compared to the case of the first setup. It's verified a decrease in the power variation of approximately 2,8 dB. Even with this decrease, the BER curves still have a similar behavior on both cases. Small BER variation is achieved because of the unbalancing of 3,5 dB used to make the power output per channel reasonably plane. The variation causes an increase of the maximum BER after the 12th amplifier. Consequently, this increase results in the reduction of the maximum optical span length from 1040 km to about 960 km. Unfortunately, this result do not support the use of pre-emphasis profile proposedExibir mais ItemTrabalho de conclusão de curso Técnicas de múltiplo acesso para redes LORAWAN(Universidade Estadual Paulista (Unesp), 2018) Dellalibera, Leonardo Arten [UNESP]; Oliveira, Cintya Wink de [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais In this work a study of LPWAN networks and their main proprietary technologies, Sigfox and LoRa, will be realized with the objective of presenting channel access techniques for LoRaWAN networks. Initially a study of LPWAN networks and their applications in Internet of Things (IoT), presenting the main characteristics of these networks, will be realized. After this, a study of principals types of modulations, namely ultra narrow band modulation and chirp spread spectrum modulation, will be presented. Following the proprietary technologies Sigfox and LoRa, giving more focus to LoRa / LoRaWAN, will be studied. And the work will be finalized with channel access techniques that allows a better use of different channels and users to avoid collisions in the transmissionExibir mais ItemTrabalho de conclusão de curso Relações diferenciais entre tensões e correntes de circuitos π com resistência de amortecimento(Universidade Estadual Paulista (Unesp), 2018) Jús, Luis Henrique [UNESP]; Prado, Afonso José do [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais This paper describes the mathematical modeling of a single phase transmission line based on electrical circuits described by concentrated and frequency independent parameters. This single-phase representation of a transmission line is approximated by means of a π circuit cascade with damping resistors in all circuit units in order to smooth the numerical oscillations present in the simulation results when energizing this model. Along, it is discussed the use of an alternative method to construct the modeling matrices, also with the intention of smoothing Gibbs oscillations and increase the range of results that are numerically stable. During the paper, the mathematical representation of this cascade is discussed through state equations. The development of the state equations is the main objective in this paper and will result in differential relations between the currents and voltages for each π circuit of the cascade. During this development, differences will be observed between specific circuits, which will result in three different equations depending on the position of these circuits in the cascade. Finally, there are some final considerations and it is suggested the stages for future works, which involve the development of the numerical method and the numerical routine, which aims to improve the results of simulations using this type of structure, reducing the influence of undesirable numerical oscillations that are generated by the numerical solution method of the mathematical modelExibir mais ItemTrabalho de conclusão de curso Antenas de microlinha multibanda(Universidade Estadual Paulista (Unesp), 2018) Geraldo, Felipe de Castro [UNESP]; Penchel, Rafael Abrantes [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais Modern wireless communications systems are going through a period of great growth and innovation that is because the development of new technologies. Nowadays, microstrip antennas are being demanded by the market due to the manufacturing low cost and the ability to operate across the whole microwave spectrum, besides the ability of multiband operation. In this work we present a study of the microstrip antennas in particular about those with a rectangular patch. The first antenna model was designed and analyzed for a 2.4GHz operating frequency using the Finite Element Method (FEM) in the ANSYS HFSS simulation software. The second stage of the study was focused around multiband antennas, where a rectangular micropostrip antenna should be designed to operate in multiband (1.8, 2.4 and 5.2 GHz). That is why a U-shaped slot was used in its conductive patch. The proposed antenna model was designed, analyzed and finally optimized through the HFSS software, by means of several parametric analysis. With these analysis it was possible to observe the behavior of the resonance frequencies, reflection coefficient, radiation pattern, input impedance, which were dependent on the dimensions of the patch and the size of the inserted slot. At last, simulated theoretical results (ANSYS HFSS) are presented, demonstrating good agreement with the objectives sought in the design phase and showing similar ones that are presented in the literatureExibir mais ItemTrabalho de conclusão de curso Desempenho de redes cooperativas full-duplex baseadas em NOMA e seleção parcial de relays(Universidade Estadual Paulista (Unesp), 2018) Tregancini Junior, Anderson [UNESP]; Olivo, Edgar Eduardo Benitez [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais With the rapidly increasing demand for wireless-based applications and services, the need to efficiently exploit the radio spectrum is imperative. In addition, fifth-generation (5G) networks must satisfy some requirements regarding the quality of service provided to their users, such as increased spectral efficiency, higher data rates and support for a massive number of connected devices. In light of this, non-orthogonal multiple acess (NOMA) and full-duplex relaying are technologies being considered, in order to achieve these objectives, as candidates to be part of the specifications of 5G networks. NOMA is a strategy whereby multiple users can share the same time, frequency or code resources, by adjusting their power allocation ratio, whereas full-duplex relaying allows to recover the spectral efficiency loss inherent to half-duplex relaying. Thus, the joint use of NOMA and full-duplex relaying has been drawing attention, due to the gains in spectral efficiency and data rate, as well as to the decrease in latency, in addition to taking advantage from the spatial diversity obtained through cooperative communications. This work analyzes the performance in terms of the outage probability for a NOMA-based cooperative scheme, which employs full-duplex relaying and the amplify-and-forward protocol, with partial relay selection. The considered system model consists of one source, two users, acessing the channel through NOMA, and a cluster of full-duplex relays. As contributions of this work, an exact expression in integral form, a lower-bound expression, an asymptotic expression at the high signal-to-noise ratio regime and an approximated losed-form expression are obtained. From the analytical expressions, the impact of the numbers of relays, the power allocation factor between users, and the residual self-interference inherent to full-duplex relaying is assessed on the performance of the proposed system. In addition, a performance comparison is...Exibir mais ItemTrabalho de conclusão de curso Projeto de uma antena yagi-uda(Universidade Estadual Paulista (Unesp), 2019) Pancracio, Thiago Coquieri [UNESP]; Penchel, Rafael Abrantes [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais The Yagi-Uda antenna is one of the most used antennas in a telecommunications system because of its high directivity and low cost. It can be designed to operate in different spectral ranges, with greater application in HF, VHF and UHF. The radiation characteristics that are usually of interest in a Yagi-Uda antenna are the forward and backward gains, bandwidth, input impedance, front-to-back ratio and the magnitude of minor lobes. In this work, Yagi was scaled to operate in the UHF band at 2,45 GHz. After being scaled, the antenna was analyzed and optimized in ANSYS Eletronic Desktop (HFSS) obtaining a gain of 15,89 dBi with two 20 MHz channels within the bandwidthExibir mais ItemTrabalho de conclusão de curso Otimização de subportadoras pilotos em OFDM PONs coerentes de longo alcance(Universidade Estadual Paulista (Unesp), 2019) Ferreira Júnior, Antonio Elcio [UNESP]; Garde, Ivan Aritz Aldaya [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais In this work, the impact of the number of pilots and their relative amplitude in the performance of long-reach passive optical networks (LR-PON) using of the Orthogonal Frequency Division Multiplexing (OFDM) is analyzed by means of numerical simulati- ons. OFDM is a multi-carrier modulation format that presents high spectral e ciency and capability to overcome for frequency selectivity, making possible to use this technique by several actual telecommunication standards. PON are formed by passive elements in- terconnected on the optical ber, responsible for enabling the ow of information in the network. Among several types of PON networks, LR-PONs are used, due to their low implementation cost and their large coverage area, which can reach up to 100 km. The system phase noise, in combination with non-linear e ects, however, degrades the signal and, consequently, the performance of such networks. As a solution, the use of pilots (un- modulated subcarriers) have been widely adopted to compensate for phase noise in coherent high-range systems. Thus, the e ect of the pilot number and their relative amplitudes in four QPSK modulation scenarios with di erent number of subcarriers is analyzed. The results show that the best OFDM con guration in terms of bit error rate for the 100-km LR-PON network has 32 subcarriers, being 10 of them pilots with a relative amplitude of 1:3. In terms of energy e cienc, however, simulations reveal that 64 subcarriers where 10 of them being pilots, represents the best con guration, since it presents a satisfactory bit error rate with the lowest ratio of the number of pilots to the total number of subcar- riers. All the coding implemented for the realization of the simulations can be seen in the AppendixExibir mais ItemTrabalho de conclusão de curso Projeto de arranjos de antenas microstrip patch(Universidade Estadual Paulista (Unesp), 2019) Andrade, Larissa Roberta [UNESP]; Penchel, Rafael Abrantes [UNESP]; Universidade Estadual Paulista (Unesp)Exibir mais This work presents a methodology for the design, analysis, and construction of microstrip patch antennas, that with the development of wireless communications become fundamental in the systems performance devices. The requirement for devices with compact dimensions, low cost and easy to manufacture are met by these antennas, which on the other hand has a narrow band, gain and low directivity disadvantages. In the design phase, the antenna sizing results were from the resonance frequency fr of 2.45GHz, substrate thickness (h) of 0.8mm, FR4 of dielectric constant of 4.4, and 50 input impedance. In the simulation stage from the HFSS software, parametrizations were made in order to optimize the performance of the patch antenna with one element, where the parameterizations were very sensitive to optimizations, besides a study of the impact of the choice of the tangent of losses and substrate dimensions on performance parameters such as gain and directivity. In the arrangement configuration, two strands were studied, series feeding, and in parallel. In the series arrays were designed in the simulator, two and four elements, analyzing the variation of parameters such as the distance between the elements, thickness and length of the feed line, thickness and length of the marriage structure, and the antenna format itself. The construction of the four-element series arrangement and the comparison between simulated and practical results were made proving that the project was successful. In the parallel arrangement, it was developed with power supply through a power slitting, for eight elements. The comparison of the projects with the reflection coefficient (|S11|), all presented better results than the minimum stipulated for similar projects (S11− 10dB). As for directivity, the addition of elements made the radiation pattern more directive according to the plane of addition of the elements. Finally, four series...Exibir mais