There is a lack of fundamental studies by means of state of the art numerical and scale modeling techniques scrutinizing the theoretical and technical aspect of air table separators as well as means to comprehend and improve the efficiency of the process. The dissertation details the development of a workable empirical model, a numerical model and a scale model to demonstrate the use of a laboratory air table unit. The modern air-based density separator achieves effective density-based separation for particle sizes greater than 6 mm. Parametric studies with the laboratory scale unit using low rank coal have demonstrated the applicability with regards to finer size fractions of the range 6 mm to 1 mm. The statistically significant empirical models showed that all the four parameters, i.e, blower and table frequency, longitudinal and transverse angle were significant in determining the separation performance. Furthermore, the tests show that an increase in the transverse angle increased the flow rate of solids to the product end and the introduction of feed results in the dampening of airflow at the feed end. The higher table frequency and feed rate had a detrimental effect on the product yield due to low residence time of particle settlement. The research further evaluated fine particle upgrading using various modeling techniques. The numerical model was evaluated using K-Epsilon and RSM turbulence formulations and validated using experimental dataset. The results prove that the effect of fine coal vortices forming around the riffles act as a transport mechanism for higher density particle movement across the table deck resulting in 43% displacement of the midlings and 29% displacement of the heavies to the product side. The velocity and vector plots show high local variance of air speeds and pressure near the feed end and an increase in feed rate results in a drop in deshaling capability of the table. The table was further evaluated using modern scale-modeling concepts and the scaling laws indicated that the vibration velocity has an integral effect on the separation performance. The difference between the full-scale model and the scaled prototype was 3.83% thus validating the scaling laws.

O principal objetivo dessa tese foi contribuir para a discussão sobre o seguro de renda e sua adoção no Brasil. No primeiro artigo buscou-se fornecer argumentos para posteriores discussões no que se refere ao seguro de renda. Para isso, o artigo apresentou o seguro de renda, seu funcionamento e como ele se desenvolveu nos dois principais países que o utilizaram, sendo eles os Estados Unidos e Canadá. Buscou-se ainda apresentar as principais características desse modelo de seguro, e quais são os principais modelos existentes. Esse artigo também teve como objetivo contribuir teoricamente para o desenvolvimento do tema no que se refere ao contrato ótimo de um seguro de renda. Como resultados, observou-se que a determinação endógena do prêmio e dos custos da seguradora para um contrato ótimo de seguro (de renda) são fundamentais para a solução (principalmente afetando as condições de primeira ordem) assim como os efeitos marginais de determinadas restrições impostas do ponto de vista de Pareto. Além disso, buscouse nesse trabalho tratar, do ponto de vista teórico, a capacidade de proteção de um seguro de renda quando comparado a um portfólio composto por seguros tradicionais de produtividade e mecanismos de proteção de preços, como mercados futuros ou opções. Observou-se uma limitação dos resultados e de uma melhor análise quantitativa dada a ausência de uma forma funcional, porém foi possível observar alguns resultados interessantes no que se refere à substituição entre a adoção de seguros (tradicionais) e derivativos agrícolas para proteção de preços. O segundo artigo teve como objetivo expor formas de calcular as taxas de prêmio de um hipotético seguro de renda no formato dos seguros americanos Income Protection ou Revenue Assurance, para milho para municípios do Paraná/BR, por meio do uso de cópulas na distribuição conjunta entre preços e produtividade. Buscou-se com isso contribuir para a obtenção de taxas mais precisas. Os resultados mostraram que existem significativas diferenças entre as taxas de prêmio entre os diferentes municípios e, ainda mais com relação aos diferentes meses de vencimento dos preços futuros utilizados na análise. Além disso, outras análises revelaram que o adequado planejamento do plantio, por exemplo, pelo produtor rural irá lhe garantir menores taxas de prêmio. Como uma das conclusões do trabalho, observa-se que esse tipo de ferramenta, levando-se em conta as características do país, poderia ser utilizado, principalmente com o ajuste de subvenções por parte do governo federal e/ou estadual. / The main objective of this thesis was to contribute to the discussion of income insurance and its adoption in Brazil. In the first article we attempted to provide arguments for further discussions about income insurance. The paper presented how it works and how it has developed in two major countries: the United States and Canada. It also sought to present the main characteristics of this insurance model, and what are the main existing models. This article also aims to contribute to the theoretical development of the subject with regard to the optimal contract for a income insurance policy. As a result, it was observed that the endogenous determination of the premium and costs of insurance for an optimal contract is the key to the solution (mainly affecting the first order conditions) as well as the marginal effects of certain restrictions, in view of Pareto Optimal. In addition, we sought to address in this paper, in the theoretical point of view, the protective capabilities of a secure income when compared to a \"portfolio\" composed by traditional insurance productivity and price protection mechanisms such as futures or options. There was a limitation of the results and better quantitative analysis given the absence of a functional form, but there have been some interesting results regarding the replacement of the adoption of insurance (traditional) and derivatives for the protection of agricultural prices. The second article aims to explain ways to calculate premium rates for hypothetical income insurance in the form of American Income Protection or Revenue Assurance for corn for municipalities of Parana/BR, through the use of copulas in the joint distribution between prices and productivity. Was sought to help to obtain more accurate rates. The results showed that there are significant differences in premium rates between different cities and even more about the different months of maturity of the futures prices used in the analysis. In addition, further analysis revealed that the proper planning of planting, for example, will guarantee for the farmer a lower premium rates. As one of the conclusions of the study, notes that these types of tool, taking into account the characteristics of the country, could be used, especially with the setting of grants by the federal government and/or state.

Various methods have been used, including airborne radars, LIDAR, observation of flying birds, towers, tethered balloons, and aircraft to gain both a qualitative and quantitative representation of how heat and moisture are transported to higher altitudes and grow the boundary or mixing layer by thermal updrafts. This paper builds upon that research using an instrumented glider to determine the structure and build a mathematical model of thermals in a desert environment. During these flights, it was discovered that the traditional view of a thermal as a singular rising plume of air did not sufficiently explain what was being observed, but rather another phenomenon was occurring. This paper puts forth the argument and a mathematical model to show that thermals actually take the form of a hexagonal convection cell at higher levels in the convective boundary layer when the thermal acts as if unrestrained by borders as in non-linear cases of free convection.

Various methods have been used, including airborne radars, LIDAR, observation of flying birds, towers, tethered balloons, and aircraft to gain both a qualitative and quantitative representation of how heat and moisture are transported to higher altitudes and grow the boundary or mixing layer by thermal updrafts. This paper builds upon that research using an instrumented glider to determine the structure and build a mathematical model of thermals in a desert environment. During these flights, it was discovered that the traditional view of a thermal as a singular rising plume of air did not sufficiently explain what was being observed, but rather another phenomenon was occurring. This paper puts forth the argument and a mathematical model to show that thermals actually take the form of a hexagonal convection cell at higher levels in the convective boundary layer when the thermal acts as if unrestrained by borders as in non-linear cases of free convection.

The isotropy of a glass can be broken by the application of a mechanical stress giving rise to a phenomenon of birefringence. Some lead-containing glass compositions are known to prevent this phenomenon and they are called zero-stress optic glass. Mueller’s theory of photoelasticity attempts to explain the structural origin of the photoelastic response in glass and crystal. Zwanziger’s empirical model is able to predict the photoelastic response of a glass based on its composition and the crystal structure of its constituents. Lead-, tin-, antimony-, zinc-, and cadmium-containing glasses were investigated in the binary silicate, borate, and phosphate systems. The stress optic coe?cient of these binary glasses was measured experimentally using the S´enarmont method or found in the literature. Solid-state Nuclear Magnetic Resonance spectroscopy and M¨ossbauer spectroscopy were mainly used to investigate the local environment of the cations. The photoelastic response of a glass and its structure were correlated, and the results were compared with the expectations arising from Mueller’s theory and Zwanziger’s empirical model. The theory and the model were both tested and their reliability was discussed. Zero-stress optic glasses are of technological interest, but new environmental regulations forbids the use of lead in materials, including glass. From experimental results and literature, a global strategy to design new zero-stress optic glasses was established. New lead-free zero-stress optic glasses were discovered with properties similar to the lead-containing zero-stress optic glass (high index of refraction, transparency, no coloration). The study of the structural dependence of the photoelastic response of oxide glass contributed to identify new parameters in?uencing the photoelasticity, such as covalency, polarizability and natural deformation of the additive.

O principal objetivo dessa tese foi contribuir para a discussão sobre o seguro de renda e sua adoção no Brasil. No primeiro artigo buscou-se fornecer argumentos para posteriores discussões no que se refere ao seguro de renda. Para isso, o artigo apresentou o seguro de renda, seu funcionamento e como ele se desenvolveu nos dois principais países que o utilizaram, sendo eles os Estados Unidos e Canadá. Buscou-se ainda apresentar as principais características desse modelo de seguro, e quais são os principais modelos existentes. Esse artigo também teve como objetivo contribuir teoricamente para o desenvolvimento do tema no que se refere ao contrato ótimo de um seguro de renda. Como resultados, observou-se que a determinação endógena do prêmio e dos custos da seguradora para um contrato ótimo de seguro (de renda) são fundamentais para a solução (principalmente afetando as condições de primeira ordem) assim como os efeitos marginais de determinadas restrições impostas do ponto de vista de Pareto. Além disso, buscouse nesse trabalho tratar, do ponto de vista teórico, a capacidade de proteção de um seguro de renda quando comparado a um portfólio composto por seguros tradicionais de produtividade e mecanismos de proteção de preços, como mercados futuros ou opções. Observou-se uma limitação dos resultados e de uma melhor análise quantitativa dada a ausência de uma forma funcional, porém foi possível observar alguns resultados interessantes no que se refere à substituição entre a adoção de seguros (tradicionais) e derivativos agrícolas para proteção de preços. O segundo artigo teve como objetivo expor formas de calcular as taxas de prêmio de um hipotético seguro de renda no formato dos seguros americanos Income Protection ou Revenue Assurance, para milho para municípios do Paraná/BR, por meio do uso de cópulas na distribuição conjunta entre preços e produtividade. Buscou-se com isso contribuir para a obtenção de taxas mais precisas. Os resultados mostraram que existem significativas diferenças entre as taxas de prêmio entre os diferentes municípios e, ainda mais com relação aos diferentes meses de vencimento dos preços futuros utilizados na análise. Além disso, outras análises revelaram que o adequado planejamento do plantio, por exemplo, pelo produtor rural irá lhe garantir menores taxas de prêmio. Como uma das conclusões do trabalho, observa-se que esse tipo de ferramenta, levando-se em conta as características do país, poderia ser utilizado, principalmente com o ajuste de subvenções por parte do governo federal e/ou estadual. / The main objective of this thesis was to contribute to the discussion of income insurance and its adoption in Brazil. In the first article we attempted to provide arguments for further discussions about income insurance. The paper presented how it works and how it has developed in two major countries: the United States and Canada. It also sought to present the main characteristics of this insurance model, and what are the main existing models. This article also aims to contribute to the theoretical development of the subject with regard to the optimal contract for a income insurance policy. As a result, it was observed that the endogenous determination of the premium and costs of insurance for an optimal contract is the key to the solution (mainly affecting the first order conditions) as well as the marginal effects of certain restrictions, in view of Pareto Optimal. In addition, we sought to address in this paper, in the theoretical point of view, the protective capabilities of a secure income when compared to a \"portfolio\" composed by traditional insurance productivity and price protection mechanisms such as futures or options. There was a limitation of the results and better quantitative analysis given the absence of a functional form, but there have been some interesting results regarding the replacement of the adoption of insurance (traditional) and derivatives for the protection of agricultural prices. The second article aims to explain ways to calculate premium rates for hypothetical income insurance in the form of American Income Protection or Revenue Assurance for corn for municipalities of Parana/BR, through the use of copulas in the joint distribution between prices and productivity. Was sought to help to obtain more accurate rates. The results showed that there are significant differences in premium rates between different cities and even more about the different months of maturity of the futures prices used in the analysis. In addition, further analysis revealed that the proper planning of planting, for example, will guarantee for the farmer a lower premium rates. As one of the conclusions of the study, notes that these types of tool, taking into account the characteristics of the country, could be used, especially with the setting of grants by the federal government and/or state.

This dissertation focuses on copper release in drinking water. Qualitative and quantitative assessment of Cu and Fe corrosion by process water quality was assessed over one year in a field study using finished waters produced from seven different treatment process and eighteen pilot distribution systems (PDSs) that were made from unlined cast iron and galvanized steel pipes, and lined cement and PVC pipes taken from actual distribution systems. Totally seven different waters were studied, which consisted of three source waters: groundwater, surface, and simulated brackish water designated as G1, S1, and RO. With certain pre-established blending ratios, these three waters were blended to form another three waters designated as G2, G3, and G4. Enhanced surface water treatment was CFS, ozonation and GAC filtration, which was designated as S1. The CFS surface water was nanofiltered, which is S2. All seven finished waters were stabilized and chloraminated before entering the PDSs. Corrosion potential was compared qualitatively and quantitatively for all seven waters by monitoring copper and iron release from the PDSs. This dissertation consists of four major parts. (1) Copper corrosion surface characterization in which the solid corrosion products formed in certain period of exposure to drinking water were tried to be identified with kinds of surface techniques. Surface characterization indicated that major corrosion products consists of cuprite (Cu2O) as major underneath corrosion layer and tenorite (CuO), cupric hydroxide (Cu(OH)2) on the top surface. In terms of dissolution/precipitation mechanism controlling the copper concentration in bulk solution, cupric hydroxide thermodynamic model was developed. (2) Theoretical thermodynamic models were developed to predict the copper release level quantitatively based on controlling solid phases identified in part (1). These models are compared to actual data and relative assessment is made of controlling solid phases. (3) Non-linear and linear regression models were developed that accommodated the release to total copper for varying water quality. These models were verified using independent data and provide proactive means of assessing and controlling copper release in a varying water quality environment. (4) Simulation of total copper release was conducted using all possible combinations of water quality produced by blending finished waters from ground, surface and saline sources, which involves the comparison of copper corrosion potentials among reverse osmosis, nanofiltration, enhanced coagulation, lime softening, and conventional drinking water treatment.

<p>Predicting core losses in electromagnetic and electromechanical devices such as electric machines is crucial to avoid overheating or oversizing. This work focuses on predicting core loss under a dc bias condition which results in hysteresis loop distortion and an increase in the core loss. The interest in dc biased materials is to facilitate design of electric drive systems wherein the electric machine core is subject to a dc bias such as in homopolar machines. Owing to their simplicity and ease of use, Steinmetz-based models are considered in this work. Herein, four models based on Steinmetz Equations are studied and compared for dc offset sinusoidal field intensity waveforms. The model parameters are then characterized for a sample of M15 steel. Finally, the four models are compared with regards to their accuracy and performance under saturated conditions.</p>

This thesis presents a model for the procedures of manufacturing Fused Filament Fabrication (FFF) components by calculating required process parameters using empirical equations. Such an empirical model has been required within the FFF field of research for a considerable amount of time and will allow for an expansion in understanding of the fundamental mathematics of FFF. Data acquired through experimentation has allowed for a data set of geometric characteristics to be built up and used to validate the model presented. The research presented draws on previous literature in the fields of additive manufacturing, machine engineering, tool-path programming, polymer science and rheology. Combining these research fields has allowed for an understanding of the FFF process which has been presented in its simplest form allowing FFF users of all levels to incorporate the empirical model into their work whilst still allowing for the complexity of the process. Initial literature research showed that Polylactic Acid (PLA) is now in common use within the field of FFF and therefore was selected as the main working material for this project. The FFF technique, which combines extrusion and Computer Aided Manufacturing (CAM) techniques, has a relatively recent history with little understood about the fundamental mathematics governing the process. This project aims to rectify the apparent gap in understanding and create a basis upon which to build research for understanding complex FFF techniques and/or processes involving extruding polymer onto surfaces.

This thesis presents a model for the procedures of manufacturing Fused Fila ment Fabrication (FFF) components by calculating required process parameters using empirical equations. Such an empirical model has been required within the FFF field of research for a considerable amount of time and will allow for an ex pansion in understanding of the fundamental mathematics of FFF. Data acquired through experimentation has allowed for a data set of geometric characteristics to be built up and used to validate the model presented. The research presented draws on previous literature in the fields of additive manufacturing, machine engi neering, tool-path programming, polymer science and rheology. Combining these research fields has allowed for an understanding of the FFF process which has been presented in its simplest form allowing FFF users of all levels to incorporate the empirical model into their work whilst still allowing for the complexity of the process. Initial literature research showed that Polylactic Acid (PLA) is now in common use within the field of FFF and therefore was selected as the main working mate rial for this project. The FFF technique, which combines extrusion and Computer Aided Manufacturing (CAM) techniques, has a relatively recent history with lit tle understood about the fundamental mathematics governing the process. This project aims to rectify the apparent gap in understanding and create a basis upon which to build research for understanding complex FFF techniques and/or pro cesses involving extruding polymer onto surfaces.