Nonlinear Analysis of a Two-Parachute System Undergoing Pendulum Motion

Motion resembling that of a pendulum undergoing large-amplitude limit cycle oscillation was observed during a series of flight tests of an unoccupied Orion Capsule Parachute Assembly System (CPAS) comprised of two parachutes and a capsule payload. Large excursions away from vertical by the capsule could cause it to strike the ground or ocean at a large angle with respect to vertical, or at a large horizontal speed. These conditions are undesirable because they would endanger the occupants of the capsule in an actual mission. A simplified planar dynamics model in conjunction with a nonlinear normal force coefficient vs. angle of attack model serves as the basis of an analytical investigation of the fundamental dynamics of this pendulum motion. Output error methodology from system identification theory was used to identify the parameters of the nonlinear aerodynamics model. The identified model yielded excellent comparison with portions of flight test data where the pendulum motion occurred. Due to the inherent nonlinear nature of the pendulum motion limit cycle, traditional nonlinear analysis techniques were applied to gain further insight into the system. Lyapunovs direct method provided mathematical proof in the absolute stability of the pendulum mode. Describing Function method was used to predict the amplitude and frequency of the limit cycle oscillation. Finally, phase plane analysis allowed easy visualization on the size and shape of the limit cycle with respect to variations in key aerodynamic parameters

Industrial transformation and upgrade model of local industrial clusters: the case of Zhongshan city, China

This thesis focuses on the difficulties of transforming and upgrading Zhongshan specialized town and solutions for development. Under the background that the economy of Zhongshan has entered into the post-industrialization era, innovation-driven development has become the inevitable way to transform and upgrade Zhongshan specialized town economy. The purpose of the dissertation is to seek and crack the development dilemma of the transition between old and new momentums and find feasible solutions. Firstly, the thesis describes how Zhongshan used to be an industrial-based traditional specialized town which mainly depended on rural competition, and how this traditional and characteristic economic development and factor-based growth model became unsustainable. Afterwards, we have done a comparative analysis of the current positioning, resource and endowments of Zhongshan in the Guangdong-Hong Kong-Macao Greater Bay Area. We also explain in the study the mechanisms and historical evolution of the cluster economy of Zhongshan specialized towns through a cluster analysis. Then, we developed a case study on Zhongshan lighting town Guzhen town and its specialized town intellectual property right protection mechanism as an example of innovation and high-tech enterprises fixation. Finally, we use a framework with four dimensions, which are Guangdong-Hong Kong-Macao Greater Bay Area urban agglomerations, Zhongshan clustering economy, traditional industry knowledge economy, and innovation entities (high-tech enterprises) to develop a model of transformation and upgrading for Zhongshan.A presente dissertação foca nas dificuldades de transformação e elevação do nível de desempenho de Zhongshan, uma região tecnológica altamente especializada do sul da China. Tendo em conta que a economia de Zhongshan entrara na era pós-industrial, o elemento da inovação tornou-se inevitável no desenvolvimento e recapacitação da sua economia. O objeto principal deste trabalho está na descoberta de novas soluções de desenvolvimento regional e na quebra do dilema de transição entre a velha e a nova economia industrial. A parte inicial do trabalho descreve como tem sido o desenvolvimento de Zhongshan que partira de uma base industrial tradicional de âmbito rural e que se tornou insustentável devido ao esgotamento do modelo de crescimento baseado em factores. Desenvolvemos, ainda, um estudo comparativo com base em cluster analysis a respeito do posicionamento estratégico e dos recursos, contrapondo Zhongshan e as mais importantes cidades da grande área da baía de Guangdong que incluem Hong Kong e Macau. Seguidamente, desenvolvemos um caso de estudo sobre a cidade de Guzhen da região de Zhongshan. A cidade de Guzhen é especializada em iluminação, protegida em termos de direitos de propriedade intelectual e colonizada por um vasto leque de empresas de base tecnológica inovadora. Por fim, construímos um modelo de análise e prospetiva baseado em quatro dimensões, a saber, a aglomeração urbana de Área da Grande Baía de Guangdong – Hong Kong – Macau, a economia em cluster de Zhongshan, a economia industrial tradicional e a inovação tecnológica para desenhar um modelo de desenvolvimento transformacional e de elevado desempenho para a região de Zhongshan