Reduction of torsional vibrations due to electromechanical interaction in aircraft systems

With the growth of electrical power onboard aircraft, the interaction between the electrical systems and the engine will become significant. Moreover, since the drivetrain has a flexible shaft, higher load connections can excite torsional vibrations on the aircraft drivetrain. These vibrations can break the shaft if the torque induced is higher than the designed value, or reduce its lifespan if the excitation is constant. To avoid these problems, the electromechanical interaction between the electrical power system and the drivetrain must be evaluated. Past studies have identified the electromechanical interaction and introduced experimental setups that allow its study. However, strategies to reduce the excitation of the torsional vibrations have not been presented. This thesis aims to analyse the electromechanical interaction in aircraft systems and develop an advanced electrical power management system (PMS) to mitigate its effects. The PMS introduces strategies based on the load timing requirements, which are built on the open loop Posicast compensator. The strategies referred as Single Level Multi-edge Switching Loads (SLME), Multilevel Loading (MLL), and Multi-load Single Level Multi-edge Switching Loads (MSLME) are applied to different loads, such as pulsating loads, ice protection system, and time-critical loads, such as the control surfaces. The Posicast based strategies, eliminate the torsional vibrations after a switching event, by the addition of zeros that cancel the poles of the system. For this reason, the knowledge of the natural frequencies of the mechanical system is necessary. Experimentally, the system parameters are obtained through Fourier analysis of the step response and the strategies are applied. A robust analysis of the strategies allows the establishment of the range of uncertainty on the frequencies that allow the proper operation of the strategies. Simulation and experimental results show that the torsional vibrations can be reduced to values close to zero by the application of the strategy. Therefore, the PMS mitigates the electromechanical interaction between the electrical power system and the aircraft drivetrain

Voters, parties and representation in European multicultural democracies

This doctoral dissertation investigates immigrants’ political participation and representation in European democracies. It grounds on the observation that immigration to Europe has increased in the last years changing the ethnic and cultural landscape of the hosting democracies. These social phenomena raise several questions: How does immigration affect electoral democracies? Are immigrant and native voters alike? Or, does immigration emerge as a new social cleavage? Are parties concerned about immigration and open to include immigrant candidates? And, how are immigrants represented in national legislatures? This dissertation is an attempt to provide deep and systematized empirically founded insights on the transformations that national electorates, parties, and political institutions are experiencing in the so-called “age of migration” across Western European democracies

Support for insider parties: The role of political trust in a longitudinal-comparative perspective

European democracies have experienced drastic changes in electoral competition. Voter support for insider parties that have traditionally governed has declined while support for radical and populist parties has increased. Simultaneously, citizens’ declining political trust has become a concern, as confidence in political institutions and actors is low across numerous countries. Interestingly, the linkage between political trust and support for insider parties has not been empirically established but deduced from the fact that outsider parties are often supported by dissatisfied citizens. We address this gap adopting both an institutional- and an actor-centered approach by investigating whether trust in parliaments and in parties is associated with the electoral performance of insider parties on the aggregate level. Combining different data sources in a novel way, we apply time-series cross-section models to a dataset containing 30 countries and 137 elections from 1998 to 2018. Our results show that when political trust is low, particularly institutional trust, insider parties receive less electoral support. Hence, we provide empirical evidence that decreasing levels of political trust are the downfall of insider parties, thereby opening a window of opportunity for challenging outsider parties

Reduction of torsional vibrations due to electromechanical interaction in aircraft systems

With the growth of electrical power onboard aircraft, the interaction between the electrical systems and the engine will become significant. Moreover, since the drivetrain has a flexible shaft, higher load connections can excite torsional vibrations on the aircraft drivetrain. These vibrations can break the shaft if the torque induced is higher than the designed value, or reduce its lifespan if the excitation is constant. To avoid these problems, the electromechanical interaction between the electrical power system and the drivetrain must be evaluated. Past studies have identified the electromechanical interaction and introduced experimental setups that allow its study. However, strategies to reduce the excitation of the torsional vibrations have not been presented. This thesis aims to analyse the electromechanical interaction in aircraft systems and develop an advanced electrical power management system (PMS) to mitigate its effects. The PMS introduces strategies based on the load timing requirements, which are built on the open loop Posicast compensator. The strategies referred as Single Level Multi-edge Switching Loads (SLME), Multilevel Loading (MLL), and Multi-load Single Level Multi-edge Switching Loads (MSLME) are applied to different loads, such as pulsating loads, ice protection system, and time-critical loads, such as the control surfaces. The Posicast based strategies, eliminate the torsional vibrations after a switching event, by the addition of zeros that cancel the poles of the system. For this reason, the knowledge of the natural frequencies of the mechanical system is necessary. Experimentally, the system parameters are obtained through Fourier analysis of the step response and the strategies are applied. A robust analysis of the strategies allows the establishment of the range of uncertainty on the frequencies that allow the proper operation of the strategies. Simulation and experimental results show that the torsional vibrations can be reduced to values close to zero by the application of the strategy. Therefore, the PMS mitigates the electromechanical interaction between the electrical power system and the aircraft drivetrain

Comparación de dos sistemas de establecimiento de arroz (Oryza sativa L), desde el punto de vista productivo y económico.

60 p.Con el objetivo de comparar el sistema de establecimiento tradicional del arroz versus el sistema de siembra directa, se realizaron ensayos en parcelas demostrativas de 5000 m2, en dos localidades en las comunas de Linares y Longaví, Región del Maule, en la temporada 2012-2013. La siembra directa se realizó con una máquina sembradora de cero labranza y posterior inundación en el estado de plántula, mientras que la convencional fue con semilla pre-germinada y sembrada al voleo sobre cuadros inundados con 5 cm de agua.Se evaluó altura de plantas desde emergencia hasta maduración, y el rendimiento de granos y sus componentes agronómicos para lo cual se obtuvieron tres muestras de 2 m2 por parcela en el momento de cosecha. Además, se realizaron fichas técnicas para comparar los gastos involucrados en la producción de una hectárea de arroz.Los resultados del estudio determinaron que los rendimientos obtenidos fueron mayores en el sistema de siembra directa, así también el número de plantas por m2 y altura de estas, que en el sistema convencional. El peso de 1000 granos fue similar en ambos sistemas. Los resultados del análisis económico mostraron que la mejor relación beneficio costo se obtuvo en el sistema de siembra directa./ ABSTRACT: In order to compare the traditional rice establishment system versus the direct seeding system, tests were conducted in demonstrative plots of 5000 m2, in two locations in the towns of Linares and Longaví, Maule Region during the 2012-13 season. Direct seeding was done with a no-till seed drilling machine and subsequent flooding in the seedling stage, while the conventional was with pre-germinated and planted in coveron flooded squares with 5 cm of water. Plant height was evaluated from emergence to maturity, and grain yield and its agronomic components for which three samples of 2 m2 per plot were obtained at the time of harvest. In addition, data sheets were designed to compare the cost involved in the production of a hectare of rice.The results of the study determined that the yields were higher in the tillage system, so were the number of population of plants and plant height, than in the conventional system. The 1000 grain weight was similar in both systems. The results of the economic analysis showed that the best cost-benefit ratio was obtained in the tillage system

Mejor función motora en miembro superior y reorganización cortical en pacientes post accidente cerebro vascular posterior a la aplicación de la terapia de restricción inducida del movimiento: revisión sistemática

106 p.El accidente cerebrovascular isquémico es la enfermedad cerebrovascular más común en Chile. Una de sus consecuencias es un déficit motor que entorpece el desarrollo de las actividades de la vida diaria y disminuye la funcionalidad de los pacientes. Para mejorar este déficit se utilizan diferentes enfoques de rehabilitación, uno de ellos es la Terapia de Restricción Inducida del Movimiento. Ésta ha evidenciado ser efectiva para recuperar la movilidad del miembro superior a través de una alta carga terapéutica. Dicha terapia no se aplica en nuestro país, por lo cual el objetivo de la presente revisión bibliográfica fue determinar la efectividad de la terapia de restricción inducida y sus diferentes variaciones, según la literatura publicada entre los años 2010-2014. Para ello se realizó una búsqueda en bases de datos reconocidas suscritas por la Universidad de Talca y se aplicaron criterios de selección a los artículos obtenidos. Posteriormente se evalúo la calidad metodológica de los estudios seleccionados a través de una Escala PEDro modificada para estudios cuasiexperimentales y Escala PEDro para ensayos clínicos, finalmente se realizó un análisis de los estudios seleccionados. Entre los resultados, en todos los estudios seleccionados hubo una alta calidad metodológica, sin embargo, ningún ensayo clínico cumplió con la totalidad de los criterios de selección. También se obtuvo que la terapia de restricción inducida del movimiento y sus versiones modificadas demuestran ser efectivas para mejorar la funcionalidad del miembro superior parético tanto para pacientes secuelados en etapa aguda como en etapa crónica. Protocolos menos demandantes y sin restricción física pueden resultar más amigables, sin embargo, en nuestro país la elevada demanda de pacientes haría difícil la aplicación de esta terapia. Se pueden tomar elementos de esta para complementar las terapias actuale