854 resultados para State feedback design


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El trabajo se propone analizar diferentes relaciones entre la universidad, la empresa privada y el Estado al momento del surgimiento del diseño industrial y de la comunicación visual, inscriptas bajo el ala del diseño como disciplina institucionalizada. Para tal fin haremos hincapié en las trayectorias de individuos y grupos que promovieron los nuevos espacios como cátedras, carreras, institutos, y departamentos en las universidades, departamentos y agencias en las empresas, e impulsaron la investigación y la formación especializada en una agencia estatal. A este respecto nos planteamos la reconstrucción y análisis de las posiciones y los tramas de relaciones sociales entre los actores, los liderazgos e ideas que confluyeron en ese marco institucionalizador. A fines de la década del ´50 se abrieron espacios en instituciones estatales ?universidades nacionales y agencias del Estado- desde los que se promovió la formación e investigación en diseño industrial y comunicación visual. Al mismo tiempo, en medio del proceso de industrialización que demandaba nuevos especialistas, las empresas privadas abrieron secciones específicas dedicadas a proyectar diseños integrales para sus productos. Para entender los sistemas de valores sobre los que se originaron estos espacios indagaremos en los documentos, artículos, libros y bienes materiales ?entre otros- que los propios actores pusieron en circulación en ese tiempo y lugar. Haremos foco en las categorías de análisis y en las definiciones por ellos dictadas en ese momento sobre el diseño. El impulso a esta nueva disciplina se abordará desde la complejidad de las trayectorias de estos agentes entendiendo la pluralidad de intereses, afinidades y razones dadas en los ámbitos público y privado. Desde esta perspectiva intentaremos dar cuenta de las historias de los individuos involucrados y de los grupos que integraron esos espacios, y su injerencia en la creación de una agencia estatal. Así podremos constatar los factores que determinaron las políticas de cambio, las prácticas y los métodos de estudio propuestos en la universidad, la empresa privada y el Estado

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El trabajo se propone analizar diferentes relaciones entre la universidad, la empresa privada y el Estado al momento del surgimiento del diseño industrial y de la comunicación visual, inscriptas bajo el ala del diseño como disciplina institucionalizada. Para tal fin haremos hincapié en las trayectorias de individuos y grupos que promovieron los nuevos espacios como cátedras, carreras, institutos, y departamentos en las universidades, departamentos y agencias en las empresas, e impulsaron la investigación y la formación especializada en una agencia estatal. A este respecto nos planteamos la reconstrucción y análisis de las posiciones y los tramas de relaciones sociales entre los actores, los liderazgos e ideas que confluyeron en ese marco institucionalizador. A fines de la década del ´50 se abrieron espacios en instituciones estatales ?universidades nacionales y agencias del Estado- desde los que se promovió la formación e investigación en diseño industrial y comunicación visual. Al mismo tiempo, en medio del proceso de industrialización que demandaba nuevos especialistas, las empresas privadas abrieron secciones específicas dedicadas a proyectar diseños integrales para sus productos. Para entender los sistemas de valores sobre los que se originaron estos espacios indagaremos en los documentos, artículos, libros y bienes materiales ?entre otros- que los propios actores pusieron en circulación en ese tiempo y lugar. Haremos foco en las categorías de análisis y en las definiciones por ellos dictadas en ese momento sobre el diseño. El impulso a esta nueva disciplina se abordará desde la complejidad de las trayectorias de estos agentes entendiendo la pluralidad de intereses, afinidades y razones dadas en los ámbitos público y privado. Desde esta perspectiva intentaremos dar cuenta de las historias de los individuos involucrados y de los grupos que integraron esos espacios, y su injerencia en la creación de una agencia estatal. Así podremos constatar los factores que determinaron las políticas de cambio, las prácticas y los métodos de estudio propuestos en la universidad, la empresa privada y el Estado

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Este trabalho apresenta o controle de posição e orientação de um modelo não linear de Plataforma de Stewart com seis graus de liberdade construído no ambiente de sistemas multicorpos ADAMS® desenvolvido pela Mechanical Dynamics, Inc. O modelo não linear é exportado para o ambiente SIMULINK® desenvolvido pela MathWorks, Inc., onde o controle de posição e orientação é realizado a partir da linearização do modelo e a aplicação de um sistema seguidor com realimentação de estados. Utililiza-se, também o SIMULINK® para implementar a dinâmica de um sistema servoválvula e cilindro hidráulico com um servocontrole de pressão e assim simular o comportamento dinâmico de um simulador de vôo com acionamento hidráulico. A utilização destes pacotes comerciais visa obter uma economia de tempo e esforço na modelagem de sistemas mecânicos complexos e na programação para obtenção da resposta do sistema no tempo, além de facilitar a análise de várias configurações de Plataformas de Stewart

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Taking its inspiration from the ongoing debate on whether this time will be different for Greece and whether Syriza will deliver on its reform promises to the European partners, this Commentary expresses bemusement that the public debate on such an important issue as well as internal discussions among senior policy-makers frequently resort to ‘gut feelings’ or simple stereotypes. To counteract this tendency, the author presents a simple analytical framework that can be used to assess the likelihood that a government will deliver on its reform agenda. Its purpose is not to allow for a precise probabilistic calculation, but to enable better structuring of the knowledge we have. It emphasises that the change depends NOT only on the capacity of the state to design and deliver policies, but even more crucially on state autonomy from both illegitimate and legitimate interests and cognitive models used by policy-makers to make sense of the world.

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The humanity reached a time of unprecedented technological development. Science has achieved and continues to achieve technologies that allowed increasingly to understand the universe and the laws which govern it, and also try to coexist without destroying the planet we live on. One of the main challenges of the XXI century is to seek and increase new sources of clean energy, renewable and able to sustain our growth and lifestyle. It is the duty of every researcher engage and contribute in this race of energy. In this context, wind power presents itself as one of the great promises for the future of electricity generation . Despite being a bit older than other sources of renewable energy, wind power still presents a wide field for improvement. The development of new techniques for control of the generator along with the development of research laboratories specializing in wind generation are one of the key points to improve the performance, efficiency and reliability of the system. Appropriate control of back-to-back converter scheme allows wind turbines based on the doubly-fed induction generator to operate in the variable-speed mode, whose benefits include maximum power extraction, reactive power injection and mechanical stress reduction. The generator-side converter provides control of active and reactive power injected into the grid, whereas the grid-side converter provides control of the DC link voltage and bi-directional power flow. The conventional control structure uses PI controllers with feed-forward compensation of cross-coupling dq terms. This control technique is sensitive to model uncertainties and the compensation of dynamic dq terms results on a competing control strategy. Therefore, to overcome these problems, it is proposed in this thesis a robust internal model based state-feedback control structure in order to eliminate the cross-coupling terms and thereby improve the generator drive as well as its dynamic behavior during sudden changes in wind speed. It is compared the conventional control approach with the proposed control technique for DFIG wind turbine control under both steady and gust wind conditions. Moreover, it is also proposed in this thesis an wind turbine emulator, which was developed to recreate in laboratory a realistic condition and to submit the generator to several wind speed conditions.

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Barnsley College’s level 3 and 4 diplomas in digital learning design are delivered in one year, enabling apprentices to be employed alongside their studies in the college’s innovative learning design company, Elephant Learning Designs. The limited time this allows for delivery and assessment has prompted course leaders to rethink their approach to course structure, assessment and feedback design, and the role of technology in evidence collection.

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High performance InGaAsP/InGaAsP strained compensated multiple-quantum-well (MQW) electroabsorption modulators (EAM) monolithically integrated with a DFB laser diode have been designed and realized by ultra low metal-organic vapor phase epitaxy (MOVPE) based on a novel butt joint scheme. The optimization thickness of upper SCH layer for DFB and EAM was obtained of the proposed MQW structure of the EAM through numerical simulation and experiment. The device containing 250(mu m) DFB and 170(mu m) EAM shows good material quality and exhibits a threshold current of 17mA, an extinction ratio of higher than 30 dB and a very high modulation efficiency (12dB/V) from 0V to 1V. By adopting a high-mesa ridge waveguide and buried polyimide, the capacitance of the modulator is reduced to about 0.30 pF corresponding to a 3dB bandwidth more than 20GHz.

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In this paper, we investigate an amplify-and-forward (AF) multiple-input multiple-output - spatial division multiplexing (MIMO-SDM) cooperative wireless networks, where each network node is equipped with multiple antennas. In order to deal with the problems of signal combining at the destination and cooperative relay selection, we propose an improved minimum mean square error (MMSE) signal combining scheme for signal recovery at the destination. Additionally, we propose two distributed relay selection algorithms based on the minimum mean squared error (MSE) of the signal estimation for the cases where channel state information (CSI) from the source to the destination is available and unavailable at the candidate nodes. Simulation results demonstrate that the proposed combiner together with the proposed relay selection algorithms achieve higher diversity gain than previous approaches in both flat and frequency-selective fading channels.

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Cross-layer techniques represent efficient means to enhance throughput and increase the transmission reliability of wireless communication systems. In this paper, a cross-layer design of aggressive adaptive modulation and coding (A-AMC), truncated automatic repeat request (T-ARQ), and user scheduling is proposed for multiuser multiple-input-multiple-output (MIMO) maximal ratio combining (MRC) systems, where the impacts of feedback delay (FD) and limited feedback (LF) on channel state information (CSI) are also considered. The A-AMC and T-ARQ mechanism selects the appropriate modulation and coding schemes (MCSs) to achieve higher spectral efficiency while satisfying the service requirement on the packet loss rate (PLR), profiting from the feasibility of using different MCSs to retransmit a packet, which is destined to a scheduled user selected to exploit multiuser diversity and enhance the system's performance in terms of both transmission efficiency and fairness. The system's performance is evaluated in terms of the average PLR, average spectral efficiency (ASE), outage probability, and average packet delay, which are derived in closed form, considering transmissions over Rayleigh-fading channels. Numerical results and comparisons are provided and show that A-AMC combined with T-ARQ yields higher spectral efficiency than the conventional scheme based on adaptive modulation and coding (AMC), while keeping the achieved PLR closer to the system's requirement and reducing delay. Furthermore, the effects of the number of ARQ retransmissions, numbers of transmit and receive antennas, normalized FD, and cardinality of the beamforming weight vector codebook are studied and discussed.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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In some practical problems, for instance in the control systems for the suppression of vibration in mechanical systems, the state-derivative signals are easier to obtain than the state signals. New necessary and sufficient linear matrix inequalities (LMI) conditions for the design of state-derivative feedback for multi-input (MI) linear systems are proposed. For multi-input/multi-output (MIMO) linear time-invariant or time-varying plants, with or without uncertainties in their parameters, the proposed methods can include in the LMI-based control designs the specifications of the decay rate, bounds on the output peak, and bounds on the state-derivative feedback matrix K. These design procedures allow new specifications and also, they consider a broader class of plants than the related results available in the literature. The LMIs, when feasible, can be efficiently solved using convex programming techniques. Practical applications illustrate the efficiency of the proposed methods.

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The transistor laser is a unique three-port device that operates simultaneously as a transistor and a laser. With quantum wells incorporated in the base regions of heterojunction bipolar transistors, the transistor laser possesses advantageous characteristics of fast base spontaneous carrier lifetime, high differential optical gain, and electrical-optical characteristics for direct “read-out” of its optical properties. These devices have demonstrated many useful features such as high-speed optical transmission without the limitations of resonance, non-linear mixing, frequency multiplication, negative resistance, and photon-assisted switching. To date, all of these devices operate as multi-mode lasers without any type of wavelength selection or stabilizing mechanisms. Stable single-mode distributed feedback diode laser sources are important in many applications including spectroscopy, as pump sources for amplifiers and solid-state lasers, for use in coherent communication systems, and now as TLs potentially for integrated optoelectronics. The subject of this work is to expand the future applications of the transistor laser by demonstrating the theoretical background, process development and device design necessary to achieve singlelongitudinal- mode operation in a three-port transistor laser. A third-order distributed feedback surface grating is fabricated in the top emitter AlGaAs confining layers using soft photocurable nanoimprint lithography. The device produces continuous wave laser operation with a peak wavelength of 959.75 nm and threshold current of 13 mA operating at -70 °C. For devices with cleaved ends a side-mode suppression ratio greater than 25 dB has been achieved.

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Dealing with the ever-growing information overload in the Internet, Recommender Systems are widely used online to suggest potential customers item they may like or find useful. Collaborative Filtering is the most popular techniques for Recommender Systems which collects opinions from customers in the form of ratings on items, services or service providers. In addition to the customer rating about a service provider, there is also a good number of online customer feedback information available over the Internet as customer reviews, comments, newsgroups post, discussion forums or blogs which is collectively called user generated contents. This information can be used to generate the public reputation of the service providers’. To do this, data mining techniques, specially recently emerged opinion mining could be a useful tool. In this paper we present a state of the art review of Opinion Mining from online customer feedback. We critically evaluate the existing work and expose cutting edge area of interest in opinion mining. We also classify the approaches taken by different researchers into several categories and sub-categories. Each of those steps is analyzed with their strength and limitations in this paper.