Orientador: Samuel da Silva / Resumo: Os métodos de análise modal tradicionalmente são limitados aos sistemas vibrando em regime linear de movimento. Assim, quando as estruturas sofrem altas amplitudes de excitação ou são muito flexíveis, gerando possíveis vibrações não-lineares, estes métodos acabam perdendo a sua validade e as propriedades características. Com base nesta motivação, este trabalho apresenta um estudo detalhado para mostrar quais as limitações de se aproximar por parâmetros modais sistemas vibrando em regime de movimento não linear. Para ilustrar a formulação, assume-se uma viga engastada e livre emulando um oscilador de Duffing com não linearidade concentrada, suave e polinomial (rigidez cúbica). Observa-se que para regimes de excitação baixa, pode-se extrair parâmetros modais do modelo e ajustá-los para níveis de excitação mais altos quando se induz vibração não-linear pelo aumento do nível da amplitude de excitação. Para situações de vibração não-linear opta-se por aproximar os sinais e saídas pelo método de superfície de resposta e identificar a dependência amplitude-frequência para extração de modos normais não-lineares. Os resultados apresentados com a formulação descrita neste trabalho permitem adaptar adequadamente as ferramentas convencionais de análise modal linear para validade e aplicação direta em casos de vibração em regime não linear, quando estes ainda são considerados de fraca influência. / Abstract: Modal analysis methods have traditionally been limited to systems vibrating in linear motion regime. Thus, when the structures undergo high excitation amplitudes or are very flexible, generating possible nonlinear vibrations, these methods end up losing their validity and characteristic properties. Based on this motivation, this work presents a detailed study to show the limitations of approaching by modal parameters systems vibrating in nonlinear regime. To illustrate the formulation, a cantilever beam is assumed to emulate a Duffing oscillator with concentrated, smooth, polynomial nonlinearity (cubic stiffness). It is observed that for low excitation regimes, one can extract modal parameters from the model and adjust them to higher excitation levels when inducing nonlinear vibration by increasing the excitation amplitude level. For nonlinear vibration situations, we choose to approximate the signals and outputs by the response surface method and identify the amplitude-frequency dependence for extraction of nonlinear normal modes. The results presented with the formulation described in this work allow to adapt adequately the conventional tools of linear modal analysis for validity and direct application in cases of vibration in nonlinear regime, when they are still considered of low influence. / Mestre

本研究可分為兩部份，第一部份以CBD為中心，向外擴展之地價空間結構變化情形之測試，主要是方法上的應用。運用較富彈性且能符合多核心都市測試需要之三次雲形函數來測試台北市之地價空間結構。研究發現都市發展方向會影響地價空間結構之變化，而傳統單核心模型之單一核心之假設及無考慮方向性，並不能充份描述現代大都市之真實空間結構。 　　第二部份則為了解各核心對地價影響情形，及在空間上互動關係進行多核心模型之測試。研究發現地價為都市空間中多核心互動的結果。而相同屬性、規模的核心間有排斥效果，不同屬性、規模的核心間則有吸引效果。藉由多核心之分散健全發展，與交通建設之密切配合，將可使都市之地價及都市空間結構更加健全發展。 / This research is divided to two parts. First part is to test the structural variance of the land price which extends by CBD. The method, the cubic spline function, is flexible and it can match the need of the polycentric city. From the test, we find the different directions which will affect the spatial structural variance of the land price. But the factor of the direction isn't included in the hypothesis of the traditional monocentric model, and it can't be described the true spatial structure of modern city sufficiently. 　　Another is the test that to understand the land price variance situation by the different centers and the interactions of them.By this test, it shows that land price is the result of the polycentric interactions of urban spatial structure. We also find there is a repelling effect between the same character and scale centers; vise versa.

<p>The aim of this thesis was to investigate amphiphilic molecules in aqueous solution. The work was divided into two parts. In the first part the effects of different counterions on phase behavior was investigated, while the second part concerns the 1-monooleoyl-rac-glycerol (MO)/n-octyl-β-D-glucoside (OG)/2H2O-system. </p><p>The effects of mixing monovalent and divalent counterions were studied for two surfactant systems, sodium/calcium octyl sulfate, and piperidine/piperazine octanesulfonate. It was found that mixing monovalent and divalent counterions resulted in a large decrease in cmc already at very low fractions of the divalent counterion. Moreover, the degree of counterion binding for piperidine in the piperidine/piperazine octanesulfonate system was much higher than predicted, probably due to the larger hydrophobic moiety of piperidine.</p><p>The effects of hydrophobic counterions were studied for eight alkylpyridinium octanesulfonates (APOS). The results were discussed in terms of packing constraints. The anomalous behavior of the 2H2O quadrupolar splittings in the lamellar phases was explained by the presence of two or more binding sites at the lamellae surface. </p><p>The MO/OG/water system was studied in general and the MO-rich cubic phases in particular. When mixing MO and OG it was found that OG-rich structures (micelles, hexagonal and cubic phase of space group Ia3d) could solubilize quite large amounts of MO, while the MO-rich cubic structures where considerable less tolerant towards the addition of OG. The micelles in the OG-rich L1 phase were found to remain rather small and discrete in the larger part of the L1 phase area, but at low water concentration and high MO content a bicontinuous structure was indicated. Only small fractions of OG was necessary to convert the MO-rich cubic Pn3m structure to an Ia3d structure, and upon further addition of OG a lamellar (La) phase formed. Since the larger part of the phase diagram contains a lamellar structure (present either as a single La phase or as a dispersion of lamellar particles together with other phases), the conclusion was that introducing OG in the MO structures, forces the MO bilayer to become more flat. Upon heating the cubic phases, structures with more negative curvature were formed. The transformation between the cubic structures required very little energy, and this resulted in the appearance of additional peaks in the diffractograms.</p>

<p>The interactions between anionic, crosslinked gels and cationic surfactants have been investigated. When exposed to oppositely charged surfactant, the gel collapses into a dense complex of polyion and micelles. During deswelling, the gel phase separates into a micelle-rich, collapsed surface phase, and a swollen, micelle-free core, both still part of the same network. As more surfactant is absorbed, the surface phase grows at the expense of the core, until the entire gel has collapsed. Polyacrylate (PA) gels with dodecyl- (C₁₂TAB), and cetyltrimethylammonium bromide (C₁₆TAB), as well as hyaluronate gels with cetylpyridinium chloride, have been studied. </p><p>Kinetic experiments have been performed on macro- as well as microgels, using micromanipulator assisted light microscopy for the latter. A surfactant diffusion controlled deswelling model has been employed to describe the deswelling. The deswelling kinetics of PA microgels have been shown to be controlled by surfactant diffusion through the stagnant layer surrounding the gel, as the surface phase is relatively thin for the major part of the deswelling. For macroscopic PA gels the surface phase is thicker, and the kinetics with C₁₂TAB were therefore also influenced by diffusion through the surface phase, while for C₁₆TAB they were dominated by it. </p><p>Relevant parameters have also been determined using equilibrium experiments. An irregular, balloon-forming deswelling pattern, mainly found for macrogels, as well as unexpectedly long lag times and slow deswelling for microgels, are reported and discussed. </p><p>The microstructure of fully collapsed PA/C₁₂TAB complexes has been studied using small-angle X-ray scattering. A cubic <i>Pm3n</i> structure was found at low salt concentration, which melted into a disordered micellar phase as the salt concentration was increased. Further increasing the salt concentration dissolved the micelles, resulting in no ordering.</p>

The aim of this thesis was to investigate amphiphilic molecules in aqueous solution. The work was divided into two parts. In the first part the effects of different counterions on phase behavior was investigated, while the second part concerns the 1-monooleoyl-rac-glycerol (MO)/n-octyl-β-D-glucoside (OG)/2H2O-system. The effects of mixing monovalent and divalent counterions were studied for two surfactant systems, sodium/calcium octyl sulfate, and piperidine/piperazine octanesulfonate. It was found that mixing monovalent and divalent counterions resulted in a large decrease in cmc already at very low fractions of the divalent counterion. Moreover, the degree of counterion binding for piperidine in the piperidine/piperazine octanesulfonate system was much higher than predicted, probably due to the larger hydrophobic moiety of piperidine. The effects of hydrophobic counterions were studied for eight alkylpyridinium octanesulfonates (APOS). The results were discussed in terms of packing constraints. The anomalous behavior of the 2H2O quadrupolar splittings in the lamellar phases was explained by the presence of two or more binding sites at the lamellae surface. The MO/OG/water system was studied in general and the MO-rich cubic phases in particular. When mixing MO and OG it was found that OG-rich structures (micelles, hexagonal and cubic phase of space group Ia3d) could solubilize quite large amounts of MO, while the MO-rich cubic structures where considerable less tolerant towards the addition of OG. The micelles in the OG-rich L1 phase were found to remain rather small and discrete in the larger part of the L1 phase area, but at low water concentration and high MO content a bicontinuous structure was indicated. Only small fractions of OG was necessary to convert the MO-rich cubic Pn3m structure to an Ia3d structure, and upon further addition of OG a lamellar (La) phase formed. Since the larger part of the phase diagram contains a lamellar structure (present either as a single La phase or as a dispersion of lamellar particles together with other phases), the conclusion was that introducing OG in the MO structures, forces the MO bilayer to become more flat. Upon heating the cubic phases, structures with more negative curvature were formed. The transformation between the cubic structures required very little energy, and this resulted in the appearance of additional peaks in the diffractograms.

The interactions between anionic, crosslinked gels and cationic surfactants have been investigated. When exposed to oppositely charged surfactant, the gel collapses into a dense complex of polyion and micelles. During deswelling, the gel phase separates into a micelle-rich, collapsed surface phase, and a swollen, micelle-free core, both still part of the same network. As more surfactant is absorbed, the surface phase grows at the expense of the core, until the entire gel has collapsed. Polyacrylate (PA) gels with dodecyl- (C12TAB), and cetyltrimethylammonium bromide (C16TAB), as well as hyaluronate gels with cetylpyridinium chloride, have been studied. Kinetic experiments have been performed on macro- as well as microgels, using micromanipulator assisted light microscopy for the latter. A surfactant diffusion controlled deswelling model has been employed to describe the deswelling. The deswelling kinetics of PA microgels have been shown to be controlled by surfactant diffusion through the stagnant layer surrounding the gel, as the surface phase is relatively thin for the major part of the deswelling. For macroscopic PA gels the surface phase is thicker, and the kinetics with C12TAB were therefore also influenced by diffusion through the surface phase, while for C16TAB they were dominated by it. Relevant parameters have also been determined using equilibrium experiments. An irregular, balloon-forming deswelling pattern, mainly found for macrogels, as well as unexpectedly long lag times and slow deswelling for microgels, are reported and discussed. The microstructure of fully collapsed PA/C12TAB complexes has been studied using small-angle X-ray scattering. A cubic Pm3n structure was found at low salt concentration, which melted into a disordered micellar phase as the salt concentration was increased. Further increasing the salt concentration dissolved the micelles, resulting in no ordering.

No description available.

The main goal of this thesis is to develop Bayesian model for studying the influence of covariate on dependence between random variables. Conditional copula models are flexible tools for modelling complex dependence structures. We construct Bayesian inference for the conditional copula model adapted to regression settings in which the bivariate outcome is continuous or mixed (binary and continuous) and the copula parameter varies with covariate values. The functional relationship between the copula parameter and the covariate is modelled using cubic splines. We also extend our work to additive models which would allow us to handle more than one covariate while keeping the computational burden within reasonable limits. We perform the proposed joint Bayesian inference via adaptive Markov chain Monte Carlo sampling. The deviance information criterion and cross-validated marginal log-likelihood criterion are employed for three model selection problems: 1) choosing the copula family that best fits the data, 2) selecting the calibration function, i.e., checking if parametric form for copula parameter is suitable and 3) determining the number of independent variables in the additive model. The performance of the estimation and model selection techniques are investigated via simulations and demonstrated on two data sets: 1) Matched Multiple Birth and 2) Burn Injury. In which of interest is the influence of gestational age and maternal age on twin birth weights in the former data, whereas in the later data we are interested in investigating how patient’s age affects the severity of burn injury and the probability of death.

The main goal of this thesis is to develop Bayesian model for studying the influence of covariate on dependence between random variables. Conditional copula models are flexible tools for modelling complex dependence structures. We construct Bayesian inference for the conditional copula model adapted to regression settings in which the bivariate outcome is continuous or mixed (binary and continuous) and the copula parameter varies with covariate values. The functional relationship between the copula parameter and the covariate is modelled using cubic splines. We also extend our work to additive models which would allow us to handle more than one covariate while keeping the computational burden within reasonable limits. We perform the proposed joint Bayesian inference via adaptive Markov chain Monte Carlo sampling. The deviance information criterion and cross-validated marginal log-likelihood criterion are employed for three model selection problems: 1) choosing the copula family that best fits the data, 2) selecting the calibration function, i.e., checking if parametric form for copula parameter is suitable and 3) determining the number of independent variables in the additive model. The performance of the estimation and model selection techniques are investigated via simulations and demonstrated on two data sets: 1) Matched Multiple Birth and 2) Burn Injury. In which of interest is the influence of gestational age and maternal age on twin birth weights in the former data, whereas in the later data we are interested in investigating how patient’s age affects the severity of burn injury and the probability of death.

The aim of this study is to get some approach which can help in improving the predictions of daily temperature of Umeå. Weather forecasts are available through various sources nowadays. There are various software and methods available for time series forecasting. Our aim is to investigate the daily maximum temperatures of Umeå, and compare the performance of some methods in forecasting these temperatures. Here we analyse the data of daily maximum temperatures and find the predictions for some local period using methods of autoregressive integrated moving average (ARIMA), exponential smoothing (ETS), and cubic splines.  The forecast package in R is used for this purpose and automatic forecasting methods available in the package are applied for modelling with ARIMA, ETS, and cubic splines. The thesis begins with some initial modelling on univariate time series of daily maximum temperatures. The data of daily maximum temperatures of Umeå from 2008 to 2013 are used to compare the methods using various lengths of training period. On the basis of accuracy measures we try to choose the best method. Keeping in mind the fact that there are various factors which can cause the variability in daily temperature, we try to improve the forecasts in the next part of thesis by using multivariate time series forecasting method on the time series of maximum temperatures together with some other variables. Vector auto regressive (VAR) model from the vars package in R is used to analyse the multivariate time series. Results: ARIMA is selected as the best method in comparison with ETS and cubic smoothing splines to forecast one-step-ahead daily maximum temperature of Umeå, with the training period of one year. It is observed that ARIMA also provides better forecasts of daily temperatures for the next two or three days. On the basis of this study, VAR (for multivariate time series) does not help to improve the forecasts significantly. The proposed ARIMA with one year training period is compatible with the forecasts of daily maximum temperature of Umeå obtained from Swedish Meteorological and Hydrological Institute (SMHI).