Rubber friction is an important aspect to tire engineers, material developers and pavement engineers because of its importance in the estimation of forces generated at the contact, which further helps in optimizing tire and vehicle performances, and to estimate tire wear. It mainly depends on the material properties, contact mechanics and operating condition. There are two major contributions to rubber friction, due to repeated viscoelastic deformation from undulations of surface called hysteresis and due to Vander Waals interaction of the molecules called adhesion. The study focuses on analytical modeling of friction for stationary sliding of rubber block on rough surfaces. Two novel approaches are discussed and compared. Frictional shear stress is obtained from the energy dissipated at the contact interface due to the elastic deformations of rubber block at different length scales. Contact mechanics theories based on continuity approach combined with stochastic processes to estimate the real contact area, mean penetration depth and true stresses at contact depending on operating conditions. Rubber properties are highly temperature dependent. Temperature model developed based on heat diffusion relation is integrated to consider the effects of temperature rise due to frictional heating. Model results are validated with theoretical results of literature. Simulation results of friction model is obtained for Compound A sliding on rough surface. Material properties are obtained using Dynamic Mechanical Analysis and Time temperature superposition. Influence of the friction models under different conditions are discussed. Model results are validated with experimental data from Dynamic friction tester on a 120-grit surface followed by future works. / Master of Science

Um atuador planar de indução é um dispositivo baseado no mesmo princípio de funcionamento de um motor linear de indução, onde a interação de um campo magnético viajante produzido pelo primário do dispositivo com uma superfície de boa condutividade elétrica induz correntes parasitas que levam à produção de uma força de propulsão. O movimento planar sobre essa superfície é produzido através da movimentação linear em dois eixos ortogonais. Uma aplicação deste movimento é na propulsão de uma plataforma equipada com câmeras e sensores para a realização da inspeção em uma superfície metálica, que se beneficiaria da força normal que o motor planar de indução produz quando acionado sobre uma superfície ferromagnética para anexar a plataforma à superfície. Um modelo analítico que fornece equações para o campo elétrico e magnético é apresentado, e simulações numéricas baseadas no método dos elementos finitos são realizadas para avaliar o comportamento do dispositivo utilizando três tipos diferentes de superfícies como secundário: um secundário com duas camadas formadas por uma chapa de alumínio com outra de aço por baixo; apenas a chapa de alumínio; e apenas a chapa de aço. As distribuições de campo magnético calculadas por estes dois modelos teóricos mostram boa concordância entre si, e são utilizadas para calcular as forças de propulsão e normal produzidas pelo atuador. Medidas experimentais são realizadas em um protótipo de atuador planar de indução, e seus resultados são comparados com os resultados obtidos nos modelos teóricos, mostrando uma boa concordância e potencial para a aplicação do atuador planar de indução na inspeção de superfícies horizontais. / An induction planar actuator is a device that, based on the operating principle of a linear induction motor, in which the interaction between a travelling magnetic field produced by the primary of the device and a conducting surface generates eddy currents in the surface and leads to the generation of a thrust force. The device produces planar motion over this surface through movement on two orthogonal axis. An application of this movement is in a platform for the inspection of metallic surfaces, which is driven by the planar induction motor and equipped with cameras and sensors to inspect the surface. This application benefits from the normal force produced by the induction planar actuator operating over a ferromagnetic surface to attach the driving platform to it. An analytical model with equations for the electric and magnetic fields is presented, and numerical simulations based on the finite element method are carried out to assess the behaviour of the device using three different surfaces as secondary: a double-layered secondary formed by an aluminum plate over a steel plate; a aluminum only plate; and a single steel plate. The distributions for the magnetic field computed through these theoretical models show good agreement, and are employed to evaluate the thrust and normal forces produced by the planar induction actuator. Experimental measurements are made on a prototype of the device, and the results are compared to the results of the theoretical models, showing good agreement and potential in the application of the induction planar motor for the inspection of horizontal metallic surfaces.

<div>The purpose of this research is to analyze the overall energy consumption of an industrial compressed air system, and identify the impact of various energy saving of individual subsystem on the overall system. Two parameters are introduced for energy consumption evaluation and potential energy saving: energy efficiency (e) and process effectiveness (n). An analytical energy model for air compression of the overall system was created taking into consideration the modeling of individual sub-system components: air compressor, after-cooler, filter, dryer and receiver. The analytical energy model for each subsystem included energy consumption evolution using the</div><div>theoretical thermodynamic approach. Furthermore, pressure loss models of individual components along with pipe friction loss were included in the system overall efficiency calculation.</div><div>The efficiency analysis methods and effectiveness approach discussed in this study were used to optimize energy consumption and quantify energy savings. The method</div><div>was tested through a case study on a plant of a die-casting manufacturing company. The experimental system efficiency was 76.2% vs. 89.3% theoretical efficiency. This showed model uncertainty at ~15%. The effectiveness of reducing the set pressure increases as the difference in pressure increase. The effectiveness of using outside air for</div><div>compressors intake is close to the compressors work reduction percentage. However, it becomes more effective when the temperature difference increase. This is mainly due to extra heat loss. There is potential room of improvement of the various component using the efficiency and effectiveness methods. These components include compressor, intercooler and dryer. Temperature is a crucial parameter that determines the energy consumption applied by these components. If optimum temperature can be determined, plenty of energy savings will be realized.</div>

Oil production from EOR and waterflood processes supplies a considerable amount of the world's oil production. Therefore, the screening and selection of the best EOR process becomes important. Numerous steps are involved in evaluating EOR methods for field applications. Binary screening guides in which reservoirs are selected on the basis of reservoir average rock and fluid properties are consulted for initial determination of applicability. However, quick quantitative comparisons and performance predictions of EOR processes are more complicated and important than binary screening that are the objectives of EOR forecasting. Forecasting (predicting) the performance of EOR processes plays an important role in the study, design and selection of the best method for a particular reservoir or a collection of reservoirs. In EOR forecasting, we look for finding ways to get quick quantitative results of the performance of different EOR processes using analytical model/s before detailed numerical simulations of the reservoirs under study. Although numerical simulation of the reservoirs is widely used, there are significant obstacles that restrict its applicability. Lack of necessary reservoir data and time consuming computations and analyses can be barriers even for history matching and/or predicting EOR/waterflood performance of one reservoir. There are different forecasting (predictive) models for evaluation of different secondary/tertiary recovery methods. However, lack of a general purpose EOR/waterflood forecasting model is unsatisfactory because any differences in results can be caused by differences in the model rather than differences in the processes. As the main objective of this study, we address this deficiency by presenting a novel and robust analytical-base general EOR and waterflood forecasting model/tool (UTF) that does not rely on conventional numerical simulation. The UTF conceptual model is based on the fundamental law of material balance, segregated flow and fractional flux theories and is applied for both history matching and forecasting the EOR/waterflood processes. The forecasting model generates the key results of isothermal EOR and waterflooding processes including variations of average oil saturation, recovery efficiency, volumetric sweep efficiency, oil cut and oil rate with real or dimensionless time. The forecasting model was validated against field data and numerical simulation results for isothermal EOR and waterflooding processes. The forecasting model reproduced well (R2> 0.8) all of the field data and reproduced the simulated data even better. To develop the UTF for forecasting when there is no injection/production history data, we used experimental design and numerical simulation and successfully generated the in-situ correlations (response surfaces) of the forecasting model variables. The forecasting model variables were proven to be well correlated to reservoir/recovery process variables and can be reliably used for forecasting. As an extension to the abilities of the forecasting model, these correlations were used for prediction of volumetric sweep efficiency and missing/dynamic pore volume of EOR and waterflooding processes. / text

Spin torque oscillators (STOs) are microwave oscillators with an attractive blend of features, including a more-than-octave tunability, GHz operating frequencies, nanoscale size, nanosecond switching speed and full compatibility with CMOS technology. Over the past decade, STOs' physical phenomena have been explored to a greater extent, their performance has been further improved, and STOs have already shown great potential for a wide range of applications, from microwave sources and detectors to neuromorphic computing. This thesis is devoted to promoting the STO technology towards its applications, by means of implementing the STO's electrical model, dedicated CMOS integrated circuits (ICs), and STO-CMOS IC integration. An electrical model, which can capture magnetic tunnel junction (MTJ) STO's characteristics, while enabling system- and circuit-level designs and performance evaluations, is of great importance for the development of MTJ STO-based applications. A comprehensive and compact analytical model, which is based on macrospin approximations and can fulfill the aforementioned requirements, is proposed. This model is fully implemented in Verilog-A, and can be used for efficient simulations of various MTJ STOs. Moreover, an accurate phase noise generation approach, which ensures a reliable model, is proposed and successfully used in the Verilog-A model implementation. The model is experimentally validated by three different MTJ STOs under different bias conditions. CMOS circuits, which can enhance the limited output power of MTJ STOs to levels that are required in different applications, are proposed, implemented and tested. A novel balun-low noise amplifier (LNA), which can offer sufficient gain, bandwidth and linearity for MTJ STO-based magnetic field sensing applications, is proposed. Additionally, a wideband amplifier, which can be connected to an MTJ STO to form a highly-tunable microwave oscillator in a phase-locked loop (PLL), is also proposed. The measurement results demonstrate that the proposed circuits can be used to develop MTJ STO-based magnetic field sensing and microwave source applications. The investigation of possible STO-CMOS IC integration approaches demonstrates that the wire-bonding-based integration is the most suitable approach. Therefore, a giant magnetoresistance (GMR) STO is integrated with its dedicated CMOS IC, which provides the necessary functions, using the wire-bonding-based approach. The RF characterization of the integrated GMR STO-CMOS IC system under different magnetic fields and DC currents shows that such an integration can eliminate wave reflections. These findings open the possibility of using GMR STOs in magnetic field sensing and microwave source applications. / <p>QC 20151112</p>

Les technologies RFID présentent des avantages non négligeables en comparaison aux technologies d'identification actuelles. Cependant, l'intégration de ces technologies dans les chaînes logistiques implique souvent des coûts élevés. Ainsi, les entreprises doivent conduire des analyses poussées pour évaluer l'impact des RFID sur le fonctionnement et l'économie des chaînes logistiques et décider de l'intégration ou non de ces technologies.Dans cette thèse nous nous concentrons sur la modélisation et l'analyse de l'introduction des technologies RFID dans les chaînes logistiques. Nous présentons d'abord une information générale sur les technologies RFID. Nous analysons ensuite la littérature sur l'intégration des RFID dans les chaînes logistiques en focalisant sur les défis et les avantages liés à l'intégration de ces technologies. Nous développons deux approches (analytique et par simulation) afin d'évaluer les impacts qualitatifs et quantitatifs des technologies RFID sur le fonctionnement et le profit des chaînes logistiques. Nous développons aussi une analyse du retour sur investissement (ROI), pour comparer les revenus obtenus à l'aide des technologies RFID avec les coûts associés à leur intégration. D'autre part, nous nous intéressons à l'amélioration des avantages de RFID dans les chaînes logistiques. Nous comparons les impacts de l'intégration de différentes RFID dans les chaînes logistiques par un remplacement simple des technologies d'identification actuelles et par la réorganisation des chaînes logistiques utilisant les nouvelles possibilités des technologies RFID. Les résultats obtenus dans ce travail mettent en évidence des perspectives intéressantes pour des études futures. L'originalité de cette étude est que nous comparons les impacts de plusieurs technologies RFID en les intégrant aux systèmes actuels et en reconstruisant des chaînes logistique grâce aux possibilités offertes par des technologies RFID. Notre modèle de simulation à événements discrets peut être utilisé comme un outil d'aide à la décision pour les sociétés qui visent à intégrer des technologies RFID.L'originalité de cette étude est que nous comparons les impacts de plusieurs technologies RFID en les intégrant aux systèmes actuels et en reconstruisant des chaînes logistique par les possibilités offertes par des technologies RFID. Notre simulation peut être utilisée comme un outil d'aide à la décision pour les sociétés qui considèrent l'intégration de technologies RFID. / In the last few years, RFID technologies have drawn considerable interests as one of the possible solutions to overcome these supply chain problems. However, integrating these technologies in supply chains induces large costs. Thus, companies must evaluate the impacts of RFID technologies on supply chain performances and economics, in order to decide whether these technologies should be integrated or not.In this thesis we focus on modeling and analyzing the impacts of introducing RFID technologies in supply chain. We first provided a basic knowledge of RFID technologies that includes the working process, the challenges and the obstacles of applying RFID technologies in supply chains. We then reviewed the literature and discussed the challenges and benefits related to integrating RFID in supply chains. Finally, we developed analytical and simulation approaches to evaluate qualitative and quantitative impacts of RFID technologies on supply chain performances and profits. We also developed ROI (Return On Investment) analysis, to compare the benefits obtained by RFID technologies with the costs associated to the integration of these technologies. Furthermore, we focused on how the benefits of RFID technologies can be improved by re-engineering supply chains using the characteristics of RFID technologies. Results obtained in this thesis highlight interesting perspectives for future studies. The main originality of this study is to compare the impacts of integrating different RFID technologies to supply chains by just replacing current identification technologies and by re-engineering supply chains using the new possibilities provided by RFID technologies. Our simulation can also be used as a decision support tool by companies that integrate RFID technologies.

[pt] O teste de injetividade é um procedimento que tem por objetivo extrair informações sobre um reservatório de petróleo a partir da injeção de um fluido (usualmente, água) no reservatório. Com base na resposta de pressão medida durante o tempo de teste, pode-se inferir uma série de características acerca do reservatório, tais como permeabilidade equivalente, condição de fronteira do reservatório e volume de óleo recuperável. O teste de injetividade é dividido em dois períodos: um de fluxo, durante o qual ocorre a injeção de água no reservatório; e o segundo de falloff, no qual o poço é fechado e o fluxo ao longo do reservatório cessa. Os modelos analíticos hoje existentes são capazes de descrever bem tanto o período de injeção quanto o de falloff apenas para reservatórios com uma camada. Nos reservatórios com múltiplas camadas, somente o período de injeção tem uma formulação conhecida. Portanto, esse trabalho tem como objetivo propor uma solução analítica para o período de falloff em reservatórios com múltiplas camadas. A precisão da solução proposta foi avaliada a partir da comparação com um simulador numérico de fluxo para uma série de casos. Os resultados mostraram boa concordância entre os dados numéricos e o modelo proposto. Além disso, os dados do falloff obtidos com a solução analítica foram usados para estimar a permeabilidade equivalente do reservatório. Os valores encontrados apresentaram precisão satisfatória para todos os casos. / [en] The injectivity test is a procedure used to collect information over a petroleum reservoir by injecting a fluid (commonly, water) into the reservoir. According to the pressure response measured during the test, several reservoir features might be inferred, such as equivalent permeability, outer boundary condition and recoverable oil volume. Injectivity test consists of two different stages: the flow period and the falloff period. During the former, occurs the water injection into the rock formation. The latter stage is marked by the well shut-in and, hence, a zero-flow pulse propagates along the reservoir. Over the past years, accomplishments have been made regarding the pressure behavior in multilayer reservoirs under single-phase flow and injectivity tests in single-layer reservoirs. However, an analytical solution for pressure behavior in multilayer reservoirs is well known just during the flow period. Therefore, this work attempts to develop an analytical model for the falloff period in multilayer reservoirs. The accuracy of the proposed solution was assessed by comparison with a finite difference flow simulator. Results showed a close agreement between the analytical model and numerical data. Moreover, falloff data obtained by the analytical solution was used to estimate the reservoir equivalent permeability. Calculated values presented a satisfactory accuracy for all cases.

Este trabalho apresenta um modelo analítico para a análise de vazão (throughput) da camada MAC do IEEE 802.11. A proposta se diferencia da maioria dos desenvolvimentos realizados na área por apresentar uma modelagem de ambientes com estações não-saturadas, levando em consideração o perfil do tráfego gerado pelas camadas superiores ao nível de enlace. Dessa maneira, o modelo permite uma análise do desempenho de aplicações reais sobre redes sem fio, a partir de resultados provenientes de um modelo matemático, enquanto diversos outros trabalhos avaliam somente situações de saturação das estações. Simulações utilizando Network Simulator 2 e comparações com resultados obtidos em trabalhos análogos desenvolvidos por outros pesquisadores validam o modelo proposto. Cenários com variações na quantidade de estações e carga oferecida à rede são avaliados utilizando o modelo teórico e comparados aos resultados simulados, provendo uma análise do comportamento dos limites de vazão do sistema. As estruturas do IEEE 802.11 MAC foram estudadas a fim de embasar o desenvolvimento do modelo proposto. Também foi realizada uma pesquisa a respeito de Cadeias de Markov, que serve como estrutura básica para a descrição do IEEE 802.11 DCF. / This work provides an analytical model to compute the IEEE 802.11 DCF throughput. The proposed analysis differs from most of the related work by presenting scenario modeling with unsaturated stations, accounting for the traffic characteristics generated by the upper layers to the data link layer. As a consequence, the proposed model allows for an accurate analysis of real applications over wireless networks, based on mathematical model results, while several other researches evaluate only saturate stations situations. Simulations ran using Network Simulator 2 and comparisons with results obtained on similar works developed by other researchers are used to validate the proposed model. Scenarios with different number of stations and offered loads are evaluated using the theoretical model and compared to the simulated results, providing an analysis on the behavior of the maximum throughput provided by the network. A study was made on the structures and mechanisms of IEEE 802.11 MAC in order to support the development of the proposed model. A research on Markov Chains was also done, since it is the basic structure used to describe the IEEE 802.11 DCF.

Um atuador planar de indução é um dispositivo baseado no mesmo princípio de funcionamento de um motor linear de indução, onde a interação de um campo magnético viajante produzido pelo primário do dispositivo com uma superfície de boa condutividade elétrica induz correntes parasitas que levam à produção de uma força de propulsão. O movimento planar sobre essa superfície é produzido através da movimentação linear em dois eixos ortogonais. Uma aplicação deste movimento é na propulsão de uma plataforma equipada com câmeras e sensores para a realização da inspeção em uma superfície metálica, que se beneficiaria da força normal que o motor planar de indução produz quando acionado sobre uma superfície ferromagnética para anexar a plataforma à superfície. Um modelo analítico que fornece equações para o campo elétrico e magnético é apresentado, e simulações numéricas baseadas no método dos elementos finitos são realizadas para avaliar o comportamento do dispositivo utilizando três tipos diferentes de superfícies como secundário: um secundário com duas camadas formadas por uma chapa de alumínio com outra de aço por baixo; apenas a chapa de alumínio; e apenas a chapa de aço. As distribuições de campo magnético calculadas por estes dois modelos teóricos mostram boa concordância entre si, e são utilizadas para calcular as forças de propulsão e normal produzidas pelo atuador. Medidas experimentais são realizadas em um protótipo de atuador planar de indução, e seus resultados são comparados com os resultados obtidos nos modelos teóricos, mostrando uma boa concordância e potencial para a aplicação do atuador planar de indução na inspeção de superfícies horizontais. / An induction planar actuator is a device that, based on the operating principle of a linear induction motor, in which the interaction between a travelling magnetic field produced by the primary of the device and a conducting surface generates eddy currents in the surface and leads to the generation of a thrust force. The device produces planar motion over this surface through movement on two orthogonal axis. An application of this movement is in a platform for the inspection of metallic surfaces, which is driven by the planar induction motor and equipped with cameras and sensors to inspect the surface. This application benefits from the normal force produced by the induction planar actuator operating over a ferromagnetic surface to attach the driving platform to it. An analytical model with equations for the electric and magnetic fields is presented, and numerical simulations based on the finite element method are carried out to assess the behaviour of the device using three different surfaces as secondary: a double-layered secondary formed by an aluminum plate over a steel plate; a aluminum only plate; and a single steel plate. The distributions for the magnetic field computed through these theoretical models show good agreement, and are employed to evaluate the thrust and normal forces produced by the planar induction actuator. Experimental measurements are made on a prototype of the device, and the results are compared to the results of the theoretical models, showing good agreement and potential in the application of the induction planar motor for the inspection of horizontal metallic surfaces.

Este trabalho apresenta um modelo analítico para a análise de vazão (throughput) da camada MAC do IEEE 802.11. A proposta se diferencia da maioria dos desenvolvimentos realizados na área por apresentar uma modelagem de ambientes com estações não-saturadas, levando em consideração o perfil do tráfego gerado pelas camadas superiores ao nível de enlace. Dessa maneira, o modelo permite uma análise do desempenho de aplicações reais sobre redes sem fio, a partir de resultados provenientes de um modelo matemático, enquanto diversos outros trabalhos avaliam somente situações de saturação das estações. Simulações utilizando Network Simulator 2 e comparações com resultados obtidos em trabalhos análogos desenvolvidos por outros pesquisadores validam o modelo proposto. Cenários com variações na quantidade de estações e carga oferecida à rede são avaliados utilizando o modelo teórico e comparados aos resultados simulados, provendo uma análise do comportamento dos limites de vazão do sistema. As estruturas do IEEE 802.11 MAC foram estudadas a fim de embasar o desenvolvimento do modelo proposto. Também foi realizada uma pesquisa a respeito de Cadeias de Markov, que serve como estrutura básica para a descrição do IEEE 802.11 DCF. / This work provides an analytical model to compute the IEEE 802.11 DCF throughput. The proposed analysis differs from most of the related work by presenting scenario modeling with unsaturated stations, accounting for the traffic characteristics generated by the upper layers to the data link layer. As a consequence, the proposed model allows for an accurate analysis of real applications over wireless networks, based on mathematical model results, while several other researches evaluate only saturate stations situations. Simulations ran using Network Simulator 2 and comparisons with results obtained on similar works developed by other researchers are used to validate the proposed model. Scenarios with different number of stations and offered loads are evaluated using the theoretical model and compared to the simulated results, providing an analysis on the behavior of the maximum throughput provided by the network. A study was made on the structures and mechanisms of IEEE 802.11 MAC in order to support the development of the proposed model. A research on Markov Chains was also done, since it is the basic structure used to describe the IEEE 802.11 DCF.