Vias de síntese linear e convergente: qual é mais verde?

A comparative study of a convergent and the linear synthetic pathway with respect to their relative greenish allowed the quantification of the advantages of the former with respect to atomic productivity as well as robustness. The calculations show that convergent pathways provide a decrease of costs together with a decrease of E factor and an increase of atomic economy which means that greenish is accompanied by an economic advantage. The influence of other features of the convergent pathways synthesis on the improvement of the synthesis greenish is discussed qualitatively.

Utilização do sensor linear de luz ILX554 em espectroscopia óptica

This technical note describes the construction of a low-cost optical detector. This device is composed by a high-sensitive linear light sensor (model ILX554) and a microcontroller. The performance of the detector was demonstrated by the detection of emission and Raman spectra of the several atomic systems and the results reproduce those found in the literature.

Dinâmica não-linear e reagente limitante: um exemplo de bifurcação transcrítica

The nonlinear analysis of a general mixed second order reaction was performed, aiming to explore some basic tools concerning the mathematics of nonlinear differential equations. Concepts of stability around fixed points based on linear stability analysis are introduced, together with phase plane and integral curves. The main focus is the chemical relationship between changes of limiting reagent and transcritical bifurcation, and the investigation underlying the conclusion.

O USO DE UM SENSOR DE LUZ LINEAR COMO RECURSO DIDÁTICO PARA DEMONSTRAR PRINCÍPIOS DE DIFRAÇÃO E ESPECTROSCOPIA

This article presents a discussion on light diffraction by slits and grids as well as the development of an experimental apparatus which provides quantitative observation of the phenomenon. We conducted a brief historical survey on the evolution of the wave theory of light and the role of diffraction in the context of optical spectroscopy. We also reviewed the use of Huygens’ principle to calculate the intensity pattern obtained when light is diffracted by slits and compared the predictions with experimental results obtained using the apparatus developed. Finally, the use of the apparatus in an optical spectroscopy experiment was demonstrated.

Applications and Markets of Linear Motors

A steady increase in practical industrial applications has secured a place for linear motors. They provide high dynamics and high positioning accuracy of the motor, high reliability and durability of all components of the system. Machines with linear motors have very big perspectives in modern industry. This thesis enables to understand what a linear motor is, where they are used and what situation there is on their market nowadays. It can help to understand reasonability of applying linear motors on manufacture and benefits of its application.

Generalização de um modelo linear de impedância eletroquímica

Em geral, a função de um modelo de impedância para processos de eletrodo simples é deduzida de um modelo elétrico equivalente, denominado circuito de Randles. Neste trabalho estudou-se a generalização dessa função, mediante a introdução de um parâmetro não-elétrico, relacionado com a flexibilidade do ângulo de fase e da magnitude. A função foi ajustada às medidas experimentais de impedância obtidas de um sistema constituído de uma liga Ti-10%Al (m/m) em solução de cloreto de sódio 0,9%, variando-se a amplitude de perturbação. Verificou-se que a função generalizada foi adequada para descrever a impedância do sistema analisado, reduzindo as distorções entre a curva experimental e a curva teórica. Além disso, os melhores resultados foram obtidos para sinais de perturbação do sistema com amplitude igual a 10 mV.

Centralized Motion Control of a Linear Tooth Belt Drive: Analysis of the Performance and Limitations

A centralized robust position control for an electrical driven tooth belt drive is designed in this doctoral thesis. Both a cascaded control structure and a PID based position controller are discussed. The performance and the limitations of the system are analyzed and design principles for the mechanical structure and the control design are given. These design principles are also suitable for most of the motion control applications, where mechanical resonance frequencies and control loop delays are present. One of the major challenges in the design of a controller for machinery applications is that the values of the parameters in the system model (parameter uncertainty) or the system model it self (non-parametric uncertainty) are seldom known accurately in advance. In this thesis a systematic analysis of the parameter uncertainty of the linear tooth beltdrive model is presented and the effect of the variation of a single parameter on the performance of the total system is shown. The total variation of the model parameters is taken into account in the control design phase using a Quantitative Feedback Theory (QFT). The thesis also introduces a new method to analyze reference feedforward controllers applying the QFT. The performance of the designed controllers is verified by experimentalmeasurements. The measurements confirm the control design principles that are given in this thesis.

Design and analysis of a transversal-flux switched-reluctance-linear-machine pole-pair

The Switched Reluctance technology is probably best suited for industrial low-speed or zerospeed applications where the power can be small but the torque or the force in linear movement cases might be relatively high. Because of its simple structure the SR-motor is an interesting alternative for low power applications where pneumatic or hydraulic linear drives are to be avoided. This study analyses the basic parts of an LSR-motor which are the two mover poles and one stator pole and which form the “basic pole pair” in linear-movement transversal-flux switchedreluctance motors. The static properties of the basic pole pair are modelled and the basic design rules are derived. The models developed are validated with experiments. A one-sided one-polepair transversal-flux switched-reluctance-linear-motor prototype is demonstrated and its static properties are measured. The modelling of the static properties is performed with FEM-calculations. Two-dimensional models are accurate enough to model the static key features for the basic dimensioning of LSRmotors. Three-dimensional models must be used in order to get the most accurate calculation results of the static traction force production. The developed dimensioning and modelling methods, which could be systematically validated by laboratory measurements, are the most significant contributions of this thesis.

Towards input/output-free modelling of linear infinite-dimensional systems in continuous time

This dissertation describes a networking approach to infinite-dimensional systems theory, where there is a minimal distinction between inputs and outputs. We introduce and study two closely related classes of systems, namely the state/signal systems and the port-Hamiltonian systems, and describe how they relate to each other. Some basic theory for these two classes of systems and the interconnections of such systems is provided. The main emphasis lies on passive and conservative systems, and the theoretical concepts are illustrated using the example of a lossless transfer line. Much remains to be done in this field and we point to some directions for future studies as well.

Problemas com o uso de programação linear com posterior arredondamento da solução ótima, em regulação florestal

O principal objetivo deste trabalho foi avaliar, com a ajuda da Programação Inteira, as conseqüências do uso da Programação Linear com posterior arredondamento das respostas, com ênfase na regulação de florestas eqüiâneas. Para isto, um problema de regulação florestal simplificado foi idealizado e resolvido pelo modelo I, por meio de Programação Linear, Programação Linear com posterior arredondamento e Programação Inteira. Ao final, concluiu-se que o arredondamento das respostas obtidas pelo modelo resolvido por Programação Linear levou a uma solução inviável para o problema de regulação proposto. O mesmo não ocorreu com o modelo de Programação Inteira, que apresentou um plano de regulação factível e otimizado, mostrando que, do ponto de vista matemático, respostas com arredondamento da solução de modelos de Programação Linear não devem ser adotadas.

Objective Evaluation of Nasal Dimensions in Children with Acoustic Rhinometry

Aims: This study was carried out to investigate the usefulness of acoustic rhinometry in the evaluation of intranasal dimensions in children. The aim was to define reference values for school children. In addition, the role of the VAS scale in the subjective evaluation of nasal obstruction in children was studied. Materials and methods: Measurements were done with Acoustic Rhinometry A1. The values of special interest were the minimal cross-sectional area (MCA) and the anterior volume of the nose (VOL). The data for reference values included 124 voluntary school children with no permanent nasal symptoms, aged between 7 and 14 years. Data were collected at baseline and after decongestion of the nose; the VAS scale was filled in before measurements. The subjects in the follow-up study (n=74, age between 1 and 12 years) were receiving intranasal spray of insulin or placebo. The nasal symptoms were recorded and acoustic rhinometry was measured at each control visit. Results: In school children, the mean total MCA was 0.752 cm2 (SD 0.165), and the mean total VOL was 4.00 cm3 (SD 0.63) at baseline. After decongestion, a significant increase in the mean TMCA and in the mean TVOL was found. A correlation was found between TMCA and age, and between TVOL and height of a child. There was no difference between boys and girls. A correlation was found between unilateral acoustic values and VAS at baseline, but not after decongestion. No difference wasfound in acoustic values or symptoms between the insulin and placebo group in the follow-up study of two years. Conclusions: Acoustic rhinometry is a suitable objective method to examine intranasal dimensions in children. It is easy to perform and well tolerated. Reference values for children between 7 and 14 years were established.

Combinação linear ponderada na definição de áreas prioritárias à conectividade entre fragmentos florestais em ambiente SIG

A fragmentação florestal de origem antrópica é um dos resultados do processo desordenado de uso e ocupação do solo, especialmente em paisagens intensamente cultivadas. Neste contexto, o presente trabalho objetivou definir áreas prioritárias, para favorecer a conectividade entre os fragmentos florestais, visando ações de recuperação florestal na Bacia do Rio Pardo, SP, utilizando a abordagem multicriterial denominada Combinação Linear Ponderada.Na definição dos critérios e, posteriormente, dos pesos de fatores, empregou-se a Técnica Participatória. Os fatores considerados importantes ao objetivo do trabalho foram: proximidade entre fragmentos de maior área nuclear, proximidade da cobertura florestal, proximidade da rede hidrográfica, distância aos centros urbanos, declividade, erodibilidade do solo. Considerando que as variáveis que interferem na escolha de áreas prioritárias à restauração florestal na Bacia do Rio Pardo-SP contribuem com pesos diferenciados no processo final de decisão, estabeleceu-se uma hierarquia, de acordo com a importância de cada fator para a aptidão da área. O fator de maior peso foi proximidade entre fragmentos de maior área nuclear (0,3713), seguido de proximidade da cobertura florestal (0,1911), proximidade da rede hidrográfica (0,1516), distância aos centros urbanos (0,1168), declividade (0,0840) e erodibilidade (0,0854).O resultado obtido foi um mapa de áreas prioritárias, com cinco graus de prioridade. A priorização de áreas ocorreu de maneira a promover, primeiro a união dos fragmentos de floresta com maior área nuclear e, a partir dessa união, a sucessiva expansão dessas regiões de prioridade muito alta tendendo a muito baixa. A metodologia mostrou-se adequada ao mapeamento de áreas prioritárias à restauração florestal, em bacias hidrográficas. Uma vez que fragmentos com maiores áreas nucleares sejam conectados com fragmentos pequenos, onde estes são predominantes na paisagem, estes promoverão a formação de fragmentos maiores a partir da formação de corredores florestais e da recomposição da vegetação.

Motivational Influences on Transfer: Dimensions and Boundary Conditions

The focus of this dissertation is the motivational influences on transfer in higher education and professional training contexts. To estimate these motivational influences, the dissertation includes seven individual studies that are structured in two parts. Part I, Dimensions, aims at identifying the dimensionality of motivation to transfer and its structural relations with training-related antecedents and outcomes. Part II, Boundary Conditions, aims at testing the predictive validity of motivation theories used in contemporary training research under different study conditions. Data in this dissertation was gathered from multi-item questionnaires, which were analyzed differently in Part I and Part II. Studies in Part I employed exploratory and confirmatory factor analysis, structural equation modeling, partial least squares (PLS) path modeling, and mediation analysis. Studies in Part II used artifact distribution meta-analysis, (nested) subgroup analysis, and weighted least squares (WLS) multiple regression. Results demonstrate that motivation to transfer can be conceptualized as a three-dimensional construct, including autonomous motivation to transfer, controlled motivation to transfer, and intention to transfer, given a theoretical framework informed by expectancy theory, self-determination theory, and the theory of planned behavior. Results also demonstrate that a range of boundary conditions moderates motivational influences on transfer. To test the predictive validity of expectancy theory, social cognitive theory, and the theory of goal orientations under different study settings, a total of 17 boundary conditions were meta-analyzed, including age; assessment criterion; assessment source; attendance policy; collaboration among trainees; computer support; instruction; instrument used to measure motivation; level of education; publication type; social training context; SS/SMC bias; study setting; survey modality; type of knowledge being trained; use of a control group; and work context. Together, the findings cumulated in this thesis support the basic premise that motivation is centrally important for transfer, but that motivational influences need to be understood from a more differentiated perspective than commonly found in the literature, in order to account for several dimensions and boundary conditions. The results of this dissertation across the seven individual studies are reflected in terms of their implications for theory development and their significance for training evaluation and the design of training environments. Limitations and directions to take in future research are discussed.