Математичне моделювання впливу шквального вітру на технічні та рослинні структури на урбанізованих територіях

Stormy events in recent years have shown that the destructive effects of wind on urban technical structures and plants pose a special threat. The paper provides an overview of mathematical models and approaches to experimental and theoretical studies of the problems associated with the effects of wind gusts and tornadoes on urban areas. Computer simulations of wind action on standard multistorey buildings in Ukraine are given. The coefficients of normal and shear components of forces and moments of forces acting on the surface of buildings, as well as vortex tracks over the residential complex at different wind speeds from moderate to severe have been computed. The calculations were performed by the finite element method using the model of turbulent air flow in the package AnSys2020. It is shown how with the help of a slight change in shape (roofs, additional passages, shields) the destructive effects of wind on the buildings and plants, as well as the threat to human life can be reduced. Pages of the article in the issue: 39 - 45 Language of the article: UkrainianШтормові події остатніх років показали, що особливу загрозу складає руйнівний вплив вітру на міські технічні споруди та рослині насадження. В доній роботі наведений огляд математичних моделей і підходів до експериментального і теоретичного дослідження проблем, пов’язаних з впливом шквального вітру і торнадо на урбанізованих територій. Наведені комп’ютерні симуляції вітрової дії на стандартні багатоповерхівки мікрорайонів України. Обчислені коефіцієнти нормальних та зсувних компонент сил і моментів сил, які діють на поверхні будинків, а також вихрові сліди та території мікрорайонів при різних швидкостях вітру від помірних до шквальних. Розрахунки проведені методом скінчених елементів з використанням моделі турбулентної течії повітря в пакеті AnSys2020. Показано, як за допомогою незначної зміни форми (дахи, додаткові проходи, щити) можна зменшити руйнівний вплив вітру на будинки і загрозу життю людей

Generalized harmonic modeling technique for 2D electromagnetic problems : applied to the design of a direct-drive active suspension system

The introduction of permanent magnets has significantly improved the performance and efficiency of advanced actuation systems. The demand for these systems in the industry is increasing and the specifications are becoming more challenging. Accurate and fast modeling of the electromagnetic phenomena is therefore required during the design stage to allow for multi-objective optimization of various topologies. This thesis presents a generalized technique to design and analyze 2D electromagnetic problems based on harmonic modeling. Therefore, the prior art is extended and unified to create a methodology which can be applied to almost any problem in the Cartesian, polar and axisymmetric coordinate system. This generalization allows for the automatic solving of complicated boundary value problems within a very short computation time. This method can be applied to a broad class of classical machines, however, more advanced and complex electromagnetic actuation systems can be designed or analyzed as well. The newly developed framework, based on the generalized harmonic modeling technique, is extensively demonstrated on slotted tubular permanent magnet actuators. As such, numerous tubular topologies, magnetization and winding configurations are analyzed. Additionally, force profiles, emf waveforms and synchronous inductances are accurately predicted. The results are within approximately 5 % of the non-linear finite element analysis including the slotted stator effects. A unique passive damping solution is integrated within the tubular permanent magnet actuator using eddy current damping. This is achieved by inserting conductive rings in the stator slot openings to provide a passive damping force without compromising the tubular actuator’s performance. This novel idea of integrating conductive rings is secured in a patent. A method to calculate the damping ratio due to these conductive rings is presented where the position, velocity and temperature dependencies are shown. The developed framework is applied to the design and optimization of a directdrive electromagnetic active suspension system for passenger cars. This innovative solution is an alternative for currently applied active hydraulic or pneumatic suspension systems for improvement of the comfort and handling of a vehicle. The electromagnetic system provides an improved bandwidth which is typically 20 times higher together with a power consumption which is approximately five times lower. As such, the proposed system eliminates two of the major drawbacks that prevented the widespread commercial breakthrough of active suspension systems. The direct-drive electromagnetic suspension system is composed of a coil spring in parallel with a tubular permanent magnet actuator with integrated eddy current damping. The coil spring supports the sprung mass while the tubular actuator either consumes, by applying direct-drive vertical forces, or regenerates energy. The applied tubular actuator is designed using a non-linear constrained optimization algorithm in combination with the developed analytical framework. This ensured the design with the highest force density together with low power consumption. In case of a power breakdown, the integrated eddy current damping in the slot openings of this tubular actuator, together with the passive coil spring, creates a passive suspension system to guarantee fail-safe operation. To validate the performance of the novel proof-of-concept electromagnetic suspension system, a prototype is constructed and a full-scale quarter car test setup is developed which mimics the vehicle corner of a BMW 530i. Consequently, controllers are designed for the active suspension strut for improvement of either comfort or handling. Finally, the suspension system is installed as a front suspension in a BMW 530i test vehicle. Both the extensive experimental laboratory and on-road tests prove the capability of the novel direct-drive electromagnetic active suspension system. Furthermore, it demonstrates the applicability of the developed modeling technique for design and optimization of electromagnetic actuators and devices

Low Power Resonant Rotary Global Clock Distribution Network Design

Along with the increasing complexity of the modern very large scale integrated (VLSI) circuit design, the power consumption of the clock distribution network in digital integrated circuits is continuously increasing. In terms of power and clock skew, the resonant clock distribution network has been studied as a promising alternative to the conventional clock distribution network. Resonant clock distribution network, which works based on adiabatic switching principles, provides a complete solution for on-chip clock generation and distribution for low-power and low-skew clock network designs for high-performance synchronous VLSI circuits.This dissertation work aims to develop the global clock distribution network for one kind of resonant clocking technologies: The resonant rotary clocking technology. The following critical aspects are addressed in this work: (1) A novel rotary oscillator array (ROA) topology is proposed to solve the signal rotation direction uniformity problem, in order to support the design of resonant rotary clocking based low-skew clock distribution network; (2) A synchronization scheme is proposed to solve the large scale rotary clocking generation circuit synchronization problem; (3) A low-skew rotary clock distribution network design methodology is proposed with frequency, power and skew optimizations; (4) A resonant rotary clocking based physical design flow is proposed, which can be integrated in the current mainstream IC design flow; (5) A dynamic rotary frequency divider is proposed for dynamic frequency scaling applications. Experimental and theoretical results show: (1) The efficiency of the proposed methodology in the construction of low-skew, low-power resonant rotary clock distribution network. (2) The effectiveness of the dynamic rotary frequency divider in extending the operating frequency range of the low-power resonant rotary based applications.Ph.D., Electrical Engineering -- Drexel University, 201

Dimensionamento e otimização de ilha de potência para suprimento de eletricidade de unidades de produção de petróleo visando a redução de emissões de CO2

Orientador: Waldyr Luiz Ribeiro GalloTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecânicaResumo: Este trabalho de doutorado foi inspirado nas tendências atuais do setor de exploração de petróleo de gás em diminuir o impacto ambiental nas atividades de exploração e produção. Empresas deste ramo tem investido em pesquisas para diminuir a emissão de gases de efeito estufa. Neste sentido, esta tese propõe uma configuração inovadora de suprimento de energia para unidades de extração de petróleo offshore. Uma plataforma flutuante dedicada à geração de energia substitui às turbinas individuais em pelo menos três plataformas convencionais de produção de petróleo. Para desenhar e otimizar essa "ilha de potência" foi necessário simular blocos de ciclos combinados, conformados por turbinas a gás, turbinas a vapor, caldeiras de recuperação de calor, condensadores e bombas, principalmente. Cada equipamento foi projetado e integrado a uma otimização de algoritmos genéticos. Foram analisados diversos casos: Caldeiras de um e dois níveis de pressão; turbinas a gás convencionais e customizadas, e configurações isoladas da ilha de potência e conexão com a rede em terra. Igualmente, foram realizadas otimizações de objetivo simples e multi-objetivo para entender as diferenças e benefícios de cada solução, otimizando em primeiro lugar objetivos simples como eficiência em plena carga, peso e custo. Para depois realizar uma otimização considerando as variações de carga ao longo do tempo de vida do campo petrolífero, utilizado simulações fora de condições de projeto do ciclo combinado, estabelecendo os objetivos de eficiência média, relação peso/potência e valor presente líquido. Os resultados apontam que a aplicação de uma ilha de potência teria uma potencial diminuição de emissões de CO2 na ordem de 13,1 e 23,4% com respeito ao cenário base. Em detrimento do desempenho econômico, precisando de uma taxa de carbono de 61 a 122 USD por tonelada para ser economicamente viável. A opção de enviar energia à terra possui ganhos econômicos, resultando em valores presentes líquidos maiores a zero, porém com incremento das emissões em até 68%Abstract: This PhD thesis was inspired by the current trends of oil and gas industry in reducing the environmental impact on its exploration and production activities. Companies in this field have invested in research to reduce the emission of greenhouse gases. In this sense, this thesis proposes an innovative configuration of energy supply for offshore oil extraction units. A floating platform dedicated to power generation replaces individual turbines on, at least, three conventional oil production platforms. To design and optimize this "power island" or "power hub" it was necessary to simulate combined cycle blocks, composed by gas turbines, steam turbines, heat recovery steam generators, condensers and pumps, mainly. Each equipment was designed and integrated within a genetic algorithm optimization. Several scenarios were analyzed, the scenarios considered: one and two pressure level heat recovery units, conventional and customized gas turbines, and two connection configurations, isolated grid a connection to shore. Likewise, simple and multi-objective optimizations were performed to understand the differences and benefits of each solution, optimizing at first objectives at full load, namely: weight, costs and efficiency. After analyzing combined cycle design points, simulations of the combined cycle off-design performance were elaborated, in order to perform optimizations considering the load variations over the oilfield lifetime, establishing objectives of: average efficiency, weight-to-power ratio and net present value. The results indicate that the application of a power island would have a potential decrease of CO2 emissions in the order of 13.1% and 23.4% with respect to the base scenario, with penalties in economic performance. A carbon trading market, with carbon certificate prices around 61 to 122 USD/ton could make this type of offshore grid more viable, when considering most optimistic layouts regarding efficiency and economic performance. The option of exporting electricity to land has economic gains, resulting in net present values higher than zero, but with an increase in emissions of up to 68%DoutoradoTermica e FluidosDoutor em Engenharia MecânicaCAPE

A printable uniplanar chipless UWB-RFID tag using multiple resonators

Session 1: Physical Design and Optimization (I)The 3rd International EURASIP Workshop on RFID Technology (RFID 2010), La Manga del Mar Menor, Cartagena, Spain, 6-7 September 2010. In Proceedings of RFID 2010, 2010, p. 1-