O turismo entrou em um período de forte expansão após a Segunda Guerra Mundial que perdura até os dias atuais. O aumento da circulação de turistas repercute na geração de renda e empregos para os países visitados, além do enriquecimento adquirido através das trocas culturais. Este crescimento tem despertado o interesse da comunidade científica, bem como profissional, com o intuito de explorar as metodologias para a modelagem e previsão da demanda turística. Estimativas acuradas da demanda servem de apoio para corretas tomadas de decisão por parte dos gestores quanto ao dimensionamento adequado de recursos financeiros, especialmente frente à realização de um evento de grandes proporções. Neste sentido, este trabalho tem por objetivos verificar quais são as técnicas atualmente mais utilizadas para previsão de demandas turísticas através de revisão da literatura, desde 2005 até 2015; utilizar dois métodos de modelagem (ARIMA e RNA) para modelar e prever a demanda turística de duas sedes olímpicas recentes; comparar essas previsões com as previsões obtidas por cinco métodos de combinação de previsões (médias aritmética, harmônica e geométrica, variância mínima e regressão linear) e; aplicar o método mais acurado para prever a demanda turística do Brasil. Os resultados foram avaliados através de três medidas de acurácia. Em virtude da realização dos Jogos Olímpicos em 2016, a demanda brasileira para este período foi modelada e prevista e a previsão foi ajustada segundo um ajuste matemático sazonal, objetivando ganho de acurácia. Foi observado ganho de acurácia quando as previsões foram combinadas e, na série brasileira, o ajuste adotado indicou um acréscimo de 175% na demanda original para agosto de 2016. / Tourism has experienced a strong increase since the end of World War II. The increase in tourist circulation results in income and employment expansion, besides the cultural enrichment involved in such experiences. This growth has attracted attention from the scientific community as well as professional, with the objective of exploring the methodologies for tourism demand modelling and forecasts. Accurate demand estimates serve as support for correct decision making by managers especially considering financial resource scaling for major events. In this sense, this study aims to verify which techniques are more currently used for forecasting tourism demand through review of the literature from 2005 to 2015; using two modeling methods (ARIMA and ANN) to make models and forecasting the tourism demand of two recent Olympic hosts; comparing these forecasts with the forecasts obtained for five methods of combining forecasts (arithmetic, harmonic and geometric means, minimum variance and linear regression) and; applying the most accurated method to forecast the tourism demand in Brazil. The results were evaluated using three different accuracy measurements. By virtue of the 2016 Olympic Games, the Brazilian tourism demand was modeled and the forecast was adjusted by a seasonal mathematical adjustment, designed for better precision. A gain in preciseness was observed when forecasts were combined and, for the Brazilian series, the adopted adjustment indicated an increase of 175% when compared with the original demand for August 2016.

O principal objetivo desta Dissertação foi o de se definir uma metodologia de planejamento de transportes que fosse sintetizada e menos onerosa que a do processo tradicional e, principalmente, que permitisse dispensar a pesquisa domiciliar, atividade demorada, trabalhosa e cara. O trabalho consistiu de uma análise superficial de diversos trabalhos existentes, elegendo quatro deles para uma análise mais detalhada, o que permitiu definir a metodologia proposta. O método baseia-se na determinação de produções e atrações de viagens a partir do conhecimento do número de unidades de uso de solos (residências, lojas, escritórios, indústrias, etc.) existentes na área de estudo, com suas respectivas características, aplicando-se-lhes taxas transferidas de outros estudos. As produções e atrações de viagens são distribuídas utilizando-se o modelo gravitacional, com parâmetros da função impedância transferidos de outros estudos. A divisão modal e a alocação de tráfego seguem o padrão tradicional, tendo sido indicada a utilização de programas de computador para a realização de alocação de equilíbrio. Segue o modelo de quatro etapas, onde a diferença fundamental está no fato de que, por não se dispor de dados completos, por causa da não realização das entrevistas de O/D domiciliares, são realizados diversos procedimentos de ajustes com o objetivo de se verificar o grau de compatibilidade das taxas transferidas utilizadas. O trabalho restringiu-se à alocação de tráfego na rede viária para o ano base, e à comparação com o fluxo observado, verificando-se que o processo conduz a um resultado aceitável. / The main aim of this work was the definition of a transportation planning methodology that was synthesized and less expensive than the one presented by the traditional process, and, more than this, which could be done without household research. A superficial analysis of several works was conducted, and four of them were chosen for a more detailed analysis, which allowed to define the proposed methodology. The method is based on the determination of trip production and trip attraction once the number of houses, shops, offices, industries, etc. present in the area of study is known, as well as their respective characteristics, and taxes from other studies were used. The trip distribution was performed using the gravitational model, applying parameters of the impedance function transferred from other studies. The modal split and the traffic assignment follow the traditional standard and the use of computational programs to perform the equilibrium assignment has been indicated. It follows the four steps model, where the fundamental difference is that, because complete data were not available, once household O/D interviews were not performed, several adjusting procedures were performed, to verify the degree of compatibility of the used transferred taxes. The work is limited to traffic assignment in the road network for the base year, and to the comparison with the observed flow, and it was verified that the process leads to an acceptable result.

O objetivo do presente trabalho foi analisar a trajetória de desaceleração, vivenciada pela economia brasileira, a partir dos anos 1990 até 2013, com o foco nas restrições impostas ao crescimento econômico – do lado da oferta, de demanda e institucionais – e suas implicações fundamentais. Apoiado nas principais interpretações teóricas e também na literatura empírica sobre a insuficiência do crescimento econômico no Brasil, elaborou-se uma investigação teórico-histórico-empírica, a fim de identificar os principais obstáculos existentes, investigando-se o seu papel na determinação da trajetória verificada nas últimas décadas. O procedimento metodológico envolveu três etapas. Na primeira, buscou-se explicitar um aparato teórico-conceitual, a partir de uma resenha literária sobre a temática do crescimento econômico, com ênfase nos fatores que podem restringir o referido processo, de acordo com três abordagens principais: a economia tradicional (ortodoxa), a vertente keynesiana-neoestruturalista e a visão da economia institucional. A segunda etapa realizou uma discussão reflexiva que identificou o contexto do surgimento e a evolução dos obstáculos relevantes ao crescimento sustentado no Brasil. Na terceira etapa, desenvolveu-se uma análise econométrica que se dividiu em duas partes: a primeira utilizou a metodologia para dados em painéis, para inferir as correlações entre algumas variáveis selecionadas e o crescimento econômico em um conjunto de 67 países entre 1990 e 2013, e a segunda realizou uma análise de séries temporais, visando avaliar a relação entre as restrições ao crescimento e a trajetória de baixo dinamismo, verificada a partir dos anos 1990. Os principais resultados da pesquisa sugeriram a existência de uma relação forte e direta entre a presença das restrições – de oferta, de demanda e institucionais – e o desempenho pífio da economia brasileira, que ocorreu em razão da deterioração dos canais fundamentais para o crescimento sustentado: o investimento, a produtividade e o setor externo, justificando o quadro de semiestagnação que caracterizou as últimas décadas. / The objective of this study was to analyze the trend of deceleration experienced by the Brazilian economy, from the years 1990 to 2013 with a focus on restrictions on economic growth - on the supply side, demand and institutional ones - and its fundamental implications. Supported by the main theoretical interpretations and also by the empirical literature on the failure of economic growth in Brazil, we elaborated a theoretical and historical-empirical research to identify the main obstacles, investigating its role in determining the trend observed in recent decades. The methodological procedure involved three steps. At first, we tried to clarify a theoretical and conceptual apparatus, through a literature review on the economic growth, with emphasis on factors that may restrict this process, according to three main approaches: the traditional (Orthodox) economy, the Keynesian-neoestruturalist vision and the institutional economics. The second stage held a reflective discussion which identified the emergence of the context and the evolution of relevant obstacles to the resumption of economic growth in Brazil. In the third stage, we dedicated to an econometric analysis was divided into two parts developed: the first used the methodology for data panels aiming to infer some correlations between selected variables and economic growth in a set of 67 countries between 1990 and 2013 and, the second, we conducted a time series analysis to evaluate the relationship between the constraints to growth and the trajectory of low dynamism observed from the early 1990. The main results of this study suggested the existence of a strong and direct relationship between the presence of restrictions – of the supply and demand side and institutional ones - and the weak performance of the Brazilian economy, which took place due to the deterioration of basic channels for sustained growth: investment, productivity and the external sector, justifying the semi-stagnation framework that characterized the last decades.

Este trabalho tem como objetivo analisar o impacto da oferta e da demanda por trabalho qualificado sobre o diferencial de salários entre trabalhadores de elevada e baixa qualificação para o Brasil, durante o período de 1992 a 2009. Para tanto, foi utilizado um modelo microeconômico de oferta e demanda por trabalho qualificado, sendo que a qualificação é determinada pelos anos completos de escolaridade. Dessa maneira, foi constatada uma elevação do diferencial de salários entre o trabalho de elevada qualificação (com ensino superior) e baixa qualificação (com ensino médio ou ensino básico) no período de 1992 a 2001, que foi impulsionada pelo efeito da demanda por trabalho qualificado. Por sua vez, no período de 2002 a 2009, foi constatada uma pequena diminuição desse diferencial, determinada pela intensificação da oferta relativa de trabalho qualificado que ocorreu durante esse período. / The objective of this dissertation is to assess the impact of supply and demand for skills in the wage differentials between skilled and unskilled workers in Brazil, during 1992 and 2009. To do so, a microeconomic model of supply and demand for skill was used where a worker\'s skill is directly linked with its educational level. In this matter, a rise in the skill premium (wage differentials between college and less than college workers) was observed between 1992 and 2001, driven by the demand for skilled labor. Adversely, during 2002 and 2009, a slight decrease in the skill premium was observed which was driven by the intensification of the relative supply of skilled workers.

This thesis evaluates and presents streaming server solutions in terms of price and performance with focus on delivering high quality video movies over broadband. The general results that have been found are that Darwin Streaming Server for Linux is recommended for a distributed solution with many nodes in the network where large distribution cost per movie is acceptable, Darwin Streaming Server for Windows is not recommended and Windows Media 9 Series is recommended in distributions where few servers can be used in the streaming network and low cost per delivered object is highly desirable. / Rapporten presenterar en utvärdering av streaming server lösningar med avseende på pris och prestanda. Fokus ligger på att utvärdera möjligheterna att streama hög kvalitets video över bredband. De generella resultaten är att Darwin Streaming Server för Linux är rekommenderad för en distribuerad lösning som kräver många noder i nätverket och höga distributionskostnader är acceptabla. Darwin Streaming Server för Windows är inte rekommenderad och Windows Media 9 Series rekommenderas när få streaming servrar kan användas och där låga distributionskostnader är viktiga. / georg.westin@home.se

Due to the increasing integration of renewable energy generations, the overvoltage and overload issues in transmission networks have become more significant, and they may occur at various locations. To mitigate the overvoltage issues, traditional solutions which often consider the installation of reactive power compensators such as shunt reactors, SVC, STATCOM may not be cost-effective. To mitigate the overload issues, traditional methods using direct or price-based demand control will affect customers’ electrical experience in that they are inconvenienced greatly. This thesis discusses the flexible tap changing techniques that utilise existing parallel transformers in distribution networks to provide reactive power absorption and demand response services for transmission systems. Among them, the tap stagger technique operates parallel transformers in small different tap positions, i.e. staggered taps, to result in more reactive power absorption from upstream networks. In addition, the tap changing technique changes voltages in the range of statutory limits through the adjustment of tap positions in order to change network demands without directly affecting customers. The aggregated reactive power absorption or demand response from many pairs of parallel transformers in distribution networks could be sufficient to provide VAr or demand support to transmission networks. Network capability studies have been carried out in OpenDSS simulation software to investigate the VAr absorption capability by using tap staggering technique and the demand reduction capability by using tap changing technique. The studies are based on two UK HV distribution networks (132-33kV) with 11 and 28 primary substations (33/11 or 6.6 kV) respectively, and the techniques are applied to parallel transformers in primary substations. Based on the results of the two networks, the capabilities of the whole ENW and the UK distribution networks have been estimated respectively by using linear estimation method. In addition, the VAr absorption capability of the tap stagger technique has been validated by using site trial data. The results show an average VAr absorption capability of 0.89MVAr for a primary substation, 315MVAr for ENW networks and about 2500MVAr for the UK at stagger level 4 and show an average demand reduction capability of 3.1% of the original demand at tap down level 3. The results of capability studies together with the validations results confirm that the flexible tap changing techniques are able to provide transmission networks with effective VAr support and demand response services. To assess network VAr absorption and demand response capability more precisely, this thesis also proposes an online load profile estimation method to estimate the load profiles of the network more accurately if not all substations in the network are monitored. The method uses Peak Load Share values, Euclidean Distance, and some load measurements to estimate load profiles. The method has been validated and compared with a traditional aggregation-based method. The results show an average estimation error of 13% ~ 23% in different conditions using the proposed method, and show an average estimation error reduction from about 47% (using the traditional method) to about 13% (using the proposed method). The results indicate that the developed method has a considerable improvement on the accuracy of load profile estimation.

Denna studie handlade om arbetsmiljöfaktorer utifrån variablerna socialt stöd, krav, kontroll och rollförväntningar för lärare. Huvudsyftet var att undersöka om det fanns några skillnader mellan variablerna beroende på vart skolan är lokaliserad (förort, närförort, centrala Stockholm) eller typ av skola (friskolor och kommunala). Datainsamlingen skedde via webbenkäter. Urvalet bestod av 116 lärare (32 män och 84 kvinnor, åldersspann 25-65). Det fanns signifikanta skillnader gällande socialt stöd; lärare som arbetade i friskolor hade mer socialt stöd än lärare vid kommunala skolor. Lärare som arbetade i friskolor hade mer stöd från chef och familj. Lärare som arbetade i grundskola hade mer stöd från arbetskamrater samt mer beslutskontroll än de lärare som arbetade i gymnasieskolor. Kommunala skolor hade mer rollkonflikter, positiva utmaningar samt mer inlärningskrav än lärare vid friskolor. Det fanns inga signifikanta skillnader på arbetsmiljöfaktorer beroende på skolans lokalisering.

Master of Science / Department of Agricultural Economics / Jeffrey M. Peterson / Understanding irrigation water demand is vital to policy decisions concerning water scarcity. This thesis evaluates irrigation water-use responses to changes in prices, while accounting for cross-sectional characteristics of irrigators’ resource settings. An irrigator’s profit-maximizing decision is modeled in two stages. In the first stage, he decides which crop to plant, and in the second stage he decides how much water to apply given the crop choice. This thesis employs an econometric modeling technique not previously used in the irrigation water demand literature, a multinomial logit selectivity model. This econometric technique allows the intensive (change in water use for each crop in the short run) and extensive (change in water use in the long run due to changes in crop-choice) margin effects to be computed in a simultaneous equation system. A multinomial logit selectivity model has applications to many resource issues in production agriculture where the two-stage decision process is common. The model is estimated from field-level data on water use and crop-choice for a 25-county region in western Kansas over the period 1991-2004. Water use was found to be highly inelastic to the price of natural gas, but becomes more elastic as the price increases. The intensive margin effect was significant for natural gas price. The extensive margin effect only comprised half the total effect under high natural gas prices and was negligible for low prices. However, the extensive margin effect under high natural gas prices declined over time due to more efficient irrigation systems and improved crop varieties. The intensive margin effect explained most of the water use response from changes in other variables, including corn price. An increase in corn price has a negligible extensive margin effect because corn is most often substituted with alfalfa, which has a similar water requirement. Inelastic demand implies that policies aiming to conserve the Ogallala Aquifer by increasing the price of water will not accomplish their purpose and will affect irrigators’ incomes. More effective policies would be voluntary or mandatory quantity restrictions. However, efficient restrictions would need to account for spatial variation in the rate of depletion and the remaining saturated thickness.

The Cloud infrastructure has become an ideal platform for large-scale applications, such as Video-on-Demand (VoD). As VoD systems migrate to the Cloud, new challenges emerge. The complexity of the Cloud system due to virtualization and resource sharing complicates the Quality of Experience (QoE) management. Operational failures in the Cloud can lead to session crashes. In addition to the Cloud, there are many other systems involved in the large-scale video streaming. These systems include the Content Delivery Networks (CDNs), multiple transit networks, access networks, and user devices. Anomalies in any of these systems can affect users’ Quality of Experience (QoE). Identifying the anomalous system that causes QoE degradation is challenging for VoD providers due to their limited visibility over these systems. We propose to apply end user QoE in the management and control of large-scale VoD systems in the Cloud. We present a QoE-based management and control systems and validate them in production Clouds. QMan, a QoE based Management system for VoD in the Cloud, controls the server selection adaptively based on user QoE. QWatch, a scalable monitoring system, detects and locates anomalies based on the end-user QoE. QRank, a scalable anomaly identification system, identifies the anomalous systems causing QoE anomalies. The proposed systems are developed and evaluated in production Clouds (Microsoft Azure, Google Cloud and Amazon Web Service). QMan provides 30% more users with QoE above the “good” Mean Opinion Score (MOS) than existing server selection systems. QMan discovers operational failures by QoE based server monitoring and prevents streaming session crashes. QWatch effectively detects and locates QoE anomalies in our extensive experiments in production Clouds. We find numerous false positives and false negatives when system metric based anomaly detection methods are used. QRank identifies anomalous systems causing 99.98% of all QoE anomalies among transit networks, access networks and user devices. Our extensive experiments in production Clouds show that transit networks are the most common bottleneck causing QoE anomalies. Cloud provider should identify bottleneck transit networks and determine appropriate peering with Internet Service Providers (ISPs) to bypass these bottlenecks.

In a developing country such as India, 44% of the population does not have access to power and for many others, the power supply is unreliable. A nanogrid, defined as “a single domain for voltage, reliability and administration”, is a possible solution to distribute power to such off-grid areas. Built from the bottom up, nanogrids have the ability to function independently, using locally generated power (such as solar power) as the power source. Such grids enable residents to lead more productive lives, with improved access to power. This thesis designs a new communication protocol for nanogrids to enable matching demand to short-term limited supply. A review of the existing local grid projects in off-grid areas in developing countries is covered – outlining the cost per kWh incurred by the customer, the communications (if any) defined in each local grid and the supply duration of the local grid. A communication protocol for a nanogrid is presented, defining a list of messages required to enable communication and the use of the Link Layer Discovery Protocol (LLDP) to implement this list. A simulation evaluation of a nanogrid deployed in an off-grid rural area of a developing country is presented. Keeping three distinct days – a sunny, cloudy and rainy day and three months – summer, monsoon and winter in mind, we demonstrate how communication about the local power price of the nanogrid can be used to modulate demand in connected loads, matching present demand with short-term limited supply. Simulation results show that the nanogrid model with communication enabled results in ~95% reduction in unmet demand for the month of December with an initial battery level of 20% (the worst case scenario). These results indicate that a grid can distribute adequate power to the loads attached to it for a month in different seasons. Such a grid, with communication about power can have a great impact in developing countries, where reduced power supply or a brownout is preferred to no power supply or a blackout.