Academic literature on the topic 'Dissipative controller'
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Journal articles on the topic "Dissipative controller"
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Liu, Long, and Ming Li. "Dissipative Control for Nonlinear Neutral Delay Systems." Applied Mechanics and Materials 48-49 (February 2011): 439–42. http://dx.doi.org/10.4028/www.scientific.net/amm.48-49.439.
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The problem of delay-dependent dissipative control for nonlinear neutral delay systems is dealt with. We develop the design method of dissipative static state feedback controller such that the closed-loop system is absolutely stable and strictly-dissipative. Sufficient conditions for the existence of the quadratic dissipative controller are obtained by using linear Matrix Inequality(LMI) approach. Furthermore, a procedure of constructing such a controller from the solution of LMI is given. It is shown that the solvability of a dissipative controller design is implied by the feasibility of LMIs.
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Zhang, Yujie, Xiujuan Liu, Junxia Jiang, and Yongshan Xiao. "Dissipativity-based resilient asynchronous control for Markov jump systems with sector-bounded nonlinearities." Transactions of the Institute of Measurement and Control 40, no. 9 (May 9, 2018): 2821–30. http://dx.doi.org/10.1177/0142331218765295.
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The resilient asynchronous dissipative control problem for Markov jump systems with sector-bounded nonlinearities in the discrete-time domain are examined in this study. The jumps between the system modes and controller modes are considered to be nonsynchronous. The mode transition of the controllers is governed by a nonstationary Markov chain, which can model the asynchronous jumps to different degrees that are also mode-dependent. The nonlinear functions are assumed to belong to sector sets with arbitrary boundaries. The sector boundaries can have positive and/or negative slopes, and therefore, we cover the most general case in our approach. Using the special structure of the system and by constructing a new multiple Lyapunov function, sufficient conditions regarding the existence of desired resilient asynchronous dissipative controllers are obtained in terms of linear matrix inequalities, which ensure the closed-loop system is stochastically stable and strictly dissipative. The designed controller can tolerate additive uncertainties in the controller gain matrix, which results from controller implementations. A numerical example is presented to show the effectiveness of the proposed theoretical results.
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Gawronski, W. K., and J. T. Sawicki. "Balanced Dissipative Controllers for Flexible Structures." Journal of Dynamic Systems, Measurement, and Control 119, no. 1 (March 1, 1997): 5–9. http://dx.doi.org/10.1115/1.2801215.
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A balanced approach to shaping the closed-loop properties of the dissipative controllers for flexible structures is presented. In the balanced representation the properties of flexible structures are introduced, and a simple method of designing of the dissipative controllers is obtained. It relates the controller gains with the closed-loop pole locations. The examples illustrate the accuracy of the design method.
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Tang, K. S., K. F. Man, and S. Kwong. "Nonlinear Dissipative Controller for Chaotic System." IFAC Proceedings Volumes 28, no. 14 (June 1995): 709–14. http://dx.doi.org/10.1016/s1474-6670(17)46912-6.
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Sakthivel, R., M. Rathika, and Srimanta Santra. "Dissipative Analysis and Synthesis of Control for TS Fuzzy Markovian Jump Neutral Systems." Mathematical Problems in Engineering 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/364184.
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This paper is focused on stochastic stability and strictly dissipative control design for a class of Takagi-Sugeno (TS) fuzzy neutral time delayed control systems with Markovian jumps. The main aim of this paper is to design a strictly dissipative controller such that the closed-loop TS fuzzy control system is stochastically stable, and also the disturbance rejection attenuation is obtained to a given level by means of theH∞performance index. Intensive analysis is carried out to obtain sufficient conditions for the existence of desired dissipative controller which ensures both the stochastic stability and the strictly dissipative performance. The main advantage of the proposed technique is that it is possible to obtain the dissipative controller with less control effort and also, as special cases, robustH∞control with the prescribedH∞performance under given constraints and passivity control can be obtained for the considered systems. Also, the existence condition of the fuzzy dissipative controller can be obtained in terms of linear matrix inequalities. Finally, a practical example based on truck-trailer model is provided to demonstrate the effectiveness and feasibility of the proposed design technique.
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Zhang, Yi, Yile Zhang, Jinghao Li, and Baoyan Zhu. "Dissipative Output Tracking Control of Linear Systems with Time Delay." Abstract and Applied Analysis 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/324741.
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The problem of dissipative output tracking control of linear systems with time delay is investigated. Firstly, an augmented system is constructed to describe dissipative output tracking control error, and the concept of dissipative output tracking is defined. Based on this, some sufficient conditions are derived in terms of linear matrix inequalities (LMIs) technique, which ensure that the augmented system is dissipative and stable; then design methods of dissipative output tracking state-feedback controller are provided, and the desired controller gain can be expressed through the solutions of LMIs. Finally, a numerical simulation example is given to illustrate the validity of the proposed results.
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Nguyen, Thanh Binh, and Hyoung-Kyu Song. "Further Results on Robust Output-Feedback Dissipative Control of Markovian Jump Fuzzy Systems with Model Uncertainties." Mathematics 10, no. 19 (October 3, 2022): 3620. http://dx.doi.org/10.3390/math10193620.
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This paper investigates an improved criterion to synthesize dissipative observer-based controllers for Markovian jump fuzzy systems under model uncertainties. Since fuzzy-basis functions include some immeasurable state variable or uncertain parameters, there are differences in the fuzzy-basis functions between controller and plant, which is a mismatched phenomenon. This work presents the first attempt for applying double-fuzzy summation-based Lyapunov functions for the observer-based control scheme of the Markov jump fuzzy system regarding the mismatched phenomenon. To be specific, the dissipative conditions are formulated in terms of uncertain parameterized bilinear matrix inequalities. Based on the improved relaxation techniques, a linear-matrix-inequality (LMI)-based algorithm is proposed in the framework of sequence linear programming matrix method. The obtained observer-based controller ensures that the closed-loop system is stochastically stable, and the dissipative performances produce less conservative results compared to preceding works via two numerical examples.
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Sun, Liying, and Renming Yang. "Adaptive Parallel Simultaneous Stabilization of a Class of Nonlinear Descriptor Systems via Dissipative Matrix Method." Mathematical Problems in Engineering 2018 (August 30, 2018): 1–13. http://dx.doi.org/10.1155/2018/1019569.
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This paper investigates the adaptive parallel simultaneous stabilization and robust adaptive parallel simultaneous stabilization problems of a class of nonlinear descriptor systems via dissipative matrix method. Firstly, under an output feedback law, two nonlinear descriptor systems are transformed into two nonlinear differential-algebraic systems by nonsingular transformations, and a sufficient condition of impulse-free is given for two resulting closed-loop systems. Then, the two systems are combined to generate an augmented dissipative Hamiltonian differential-algebraic system by using the system-augmentation technique. Based on the dissipative system, an adaptive parallel simultaneous stabilization controller and a robust adaptive parallel simultaneous stabilization controller are designed for the two systems. Furthermore, the case of more than two nonlinear descriptor systems is investigated. Finally, an illustrative example is studied by using the results proposed in this paper, and simulations show that the adaptive parallel simultaneous stabilization controllers obtained in this paper work very well.
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Hu, Shr-Shiung, Pao-Hwa Yang, and B. C. Chang. "A Computational Issue and Modified Formulas for Nonlinear Dissipative Controllers." Journal of Dynamic Systems, Measurement, and Control 125, no. 3 (September 1, 2003): 475–80. http://dx.doi.org/10.1115/1.1590686.
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Ball, Helton, and Walker (BHW) derived the nonlinear dissipative controller formulas with the assumption implying that no stable mode uncontrollable from the exogenous input. The assumption is more restrictive than that considered in DGKF. In this paper, we address the numerical difficulty encountered by BHW’s controller formulas when the assumption is not satisfied. Next, we propose a modified nonlinear dissipative controller and successfully remove the numerical difficulty. We also show that the linear version of the proposed controller formulas is identical to the DGKF H∞ controller. An example is given to demonstrate constructing the proposed controller and simulating the closed-loop pulse responses.
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Xie, Yun, Zhuangyu Liu, Xiaoli Luan, and Jiwei Wen. "Dissipative dynamic output feedback control for switched systems via multistep Lyapunov function approach." Transactions of the Institute of Measurement and Control 41, no. 15 (June 17, 2019): 4254–62. http://dx.doi.org/10.1177/0142331219854867.
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The conservatism reduction problem of dissipative dynamic output feedback (DOF) control for a class of average dwell time switched system is investigated via a multistep Lyapunov function (LF) approach. First, a larger dissipative region with guaranteed stability and specifically, smaller [Formula: see text] level can be achieved by increasing a predictive step N, which means the monotonic requirement of LF is relaxed. Then, based on the results of dissipative analysis, a robust dissipative DOF controller is further designed. Unlike the traditional method that introduces equality constraint to obtain numerical testable conditions with heuristic nature, a less conservative controller is designed, where the LF matrix is formulated without structural constraint.
Dissertations / Theses on the topic "Dissipative controller"
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Rocha, Téo Lenquist da 1979. "Attenuation of noise and vibration using piezoelectric patches and dissipative shunt circuits = Atenuação de ruído e vibração utilizando pastilhas piezoelétricas e circuitos elétricos dissipativos." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265941.
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Orientador: Milton Dias JúniorTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-25T08:49:57Z (GMT). No. of bitstreams: 1 Rocha_TeoLenquistda_D.pdf: 5484630 bytes, checksum: 40d5122ff01ee4077957ffbc79369379 (MD5) Previous issue date: 2014
Resumo: Ruído em um veículo é geralmente causado pela vibração de vários componentes. Por exemplo, vibrações causadas pelo motor podem causar vibração de um painel levando a ruído no interior da cabine. O controle de tal ruído e vibração pode ser conseguido através da aplicação de uma manta visco-elástica ou de outro material de amortecimento adequado sobre o componente do automóvel; no entanto, materiais de amortecimento convencional geralmente têm uma alta densidade, que pode conduzir a um aumento significativo na massa total do sistema de isolamento acústico. Uma alternativa para redução de peso emprega pastilhas piezocerâmicas ligadas em série a um circuito Resistor - Indutor ( RL ), funcionando como um amortecedor de vibração sintonizado; daí o termo ressoador piezoelétrico é utilizado. No presente trabalho, a capacidade de amortecimento de ressonadores piezoelétricos é comparada a tratamentos convencionais de amortecimento em uma sequência de três experimentos. Investigações iniciais são realizadas em uma chapa de aço instalada entre câmaras reverberante e anecóica para permitir medições de transmissão do som através da placa. Uma abordagem integrada utilizando análise modal e técnicas de visualização de campo acústico é utilizada para identificar os modos mais relevantes para a propagação do ruído. Na sequência, simulação por elementos finitos e análise teórica são utilizados para auxiliar na escolha dos valores dos componentes elétricos e no posicionamento dos resonadores piezoelétricos para atuação maximizada. Medições de Perda de Transmissão Sonora e Funções de Resposta em Frequência são realizadas para demonstrar o controle de vibração estrutural e o isolamento acústico resultante. Na sequência, os elementos de projeto deste experimento são replicados no painel de instrumentos de um veículo. Com o painel de instrumentos instalado entre salas reverberante e anecóica, a contribuição dos ressonadores piezoelétricos sobre a perda de transmissão sonora é demonstrada em uma estrutura complexa. Finalmente, ressonadores piezoeléctricos são utilizados para atenuar a vibração induzida pelo funcionamento de motor no painel traseiro de um veículo. Nesta aplicação prática, o efeito do controle de vibração e da atenuação de ruído interno são avaliados em condições operacionais. O trabalho é concluído com uma discussão sobre os resultados alcançados e os benefícios de redução de massa proporcionados pela técnica de amortecimento proposta
Abstract: Noise in a vehicle is generally caused by the vibration of various automotive components, such as the dash board, door panels, roof, or the like. For example, vibrations caused by the engine may cause a dash panel to vibrate leading to noise inside the cabin. The control of such noise and vibration may be achieved by placing a viscoelastic or other suitable damping material on the automotive component; however, conventional damping materials usually have a high density, which can lead to significant increases in the overall mass of the sound insulation system. A lightweight alternative employs piezoceramic patches connected in series to a Resistor-Inductor (R-L) circuit, performing as a tuned vibration absorber; hence the term piezoelectric resonator is used. In the present work, the damping capacity of piezoelectric resonators is compared to conventional damping treatments in a sequence of three experiments. Initial investigations are carried out in a steel plate installed between reverberant and anechoic rooms, to enable measurements of sound transmission through the plate. An integrated approach using component modal analyses and assessments of sound pressured distribution is employed to identify the most relevant modes to the noise propagation. In sequence, FE simulation and theoretical analysis are used to support the choice of the electrical components values and the placement of piezoelectric patches for maximized actuation. Measurements of Sound Transmission Loss (STL) and Frequency Response Function (FRF) are conducted to demonstrate the structural vibration control and its resulting sound insulation. Furthermore, design elements of this experiment are replicated into a vehicle dash panel. With the dash panel installed between reverberant and anechoic rooms, the contribution of piezoelectric resonators on the sound transmission loss is proven to be effective in a complex structure. Finally, piezoelectric resonators are employed to attenuate the vibration induced by powertrain excitation in the back panel of a vehicle. In this practical application, the effect of structural vibration control and interior noise attenuation are evaluated in operational conditions. The work is concluded with a discussion on the achieved results and mass saving benefits of the proposed lightweight damping technique
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica
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Dai, Zhenting. "Coherent and Dissipative Transport in Metallic Atomic-Size Contacts." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/19880.
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Thin-film niobium mechanically controlled break junctions and resistively shunted niobium mechanically-controlled break junctions were developed and successfully microfabricated. Using these devices, high-stability atomic size contacts were routinely produced and investigated both in the normal and superconducting states. Investigations of the two-level conductance fluctuations in the smallest contacts allowed the calculation of their specific atomic structure. Embedding resistive shunts close to the superconducting atomic-sized junctions affected the coherence of the electronic transport. Finally, point contact spectroscopy measurements provide evidence of the interaction of conduction electrons with the mechanical degrees of freedom of the atomic-size niobium contacts.
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Kim, Jong Un. "Error rate and power dissipation in nano-logic devices." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/2224.
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Current-controlled logic and single electron logic processors have been investigated with respect to thermal-induced bit error. A maximal error rate for both logic processors is regarded as one bit-error/year/chip. A maximal clock frequency and an information channel capacity at a given operation current are derived when a current-controlled logic processor works without error. An available operation range in a current-controlled processor with 100 million elements is discussed. The dependence of an error-free condition on temperature in single electron logic processors is derived. The size of the quantum dot of single electron transistor is predicted when a single electron logic processor with the a billion single electron transistors works without error at room temperature.
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BENADDI, AHMED. "Stabilisation de quelques systemes distribues au moyen des controles non dissipatifs." Université Louis Pasteur (Strasbourg) (1971-2008), 2000. http://www.theses.fr/2000STR13171.
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La stabilisation des equations d'evolution presentant un caractere dissipatif regissant notamment des systemes distribues gouvernes par des feedbacks ont fait l'objet, ces dernieres annees, d'importants travaux. Afin de pouvoir tenir compte de certains phenomenes (non-positivite du controle), l'absence de la dissipation parait comme une hypothese incontournable, mais provoque des difficultes essentielles. Les travaux de cette these sont consacres a l'etude du taux de decroissance de l'energie d'une equation des ondes en dimension 1, d'un systeme couple d'equations des ondes et d'un systeme couple des equations de poutre de rayleigh, dans le cadre de feedbacks non dissipatifs. Le but de la premiere partie est d'etendre dans le cas d'un potentiel positif le resultat de freitas et zuazua (1996) ou ils ont mis en evidence une base de riesz formee des vecteurs propres du generateur infinitesimal du semi-groupe associe au probleme d'evolution. En utilisant la methode de tir, nous etablissons le developpement asymptotique des valeurs propres et des vecteurs propres de l'equation des ondes amorties. Nous montrons que les parties reelles des valeurs propres admettent une asymptote verticale. Ainsi, nous montrons que, si l'amortissement est plus positif que negatif, l'energie du systeme decroit exponentiellement vers zero. Nous considerons dans la deuxieme partie un systeme couple de deux equations des ondes en presence d'un amortissement positif. En utilisant une methode proposee par rao (1997), nous etablissons d'abord le developpement asymptotique des valeurs propres et des vecteurs propres. Puis, nous montrons que le systeme des vecteurs propres generalises de l'operateur associe forme une base de riesz. Ceci nous permet d'etablir le taux de decroissance de l'energie. Cette idee est developpee dans le cas d'un systeme couple de deux equations des ondes avec un amortissement a signe indefini. Nous etablissons a la fin de ce travail la stabilisation exponentielle des equations des ondes et des equations de poutre de rayleigh couplees avec des controles distribues differents et a signe indefini.
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White, Samuel Lewis. "Controlled Damage Rocking Systems for Accelerated Bridge Construction." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2014. http://hdl.handle.net/10092/9186.
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Bridge substructures are generally constructed using cast-in-place concrete and designed to undergo inelastic deformation in earthquake events. Although this construction approach has proven to be economical and provides adequate seismic performance through the formation of ductile plastic hinges, there are downsides relating to construction speed and quality, and post-earthquake repairability.
This thesis explores two categories of Accelerated Bridge Construction (ABC) connection types, which use precast concrete instead of cast-in-place concrete to offer advantages including increased construction speed and quality. High Damage (HD) ABC connection types emulate the seismic behaviour of cast-in-place construction through the formation of ductile plastic hinges.
Controlled Damage (CD) ABC connection types use unbonded post-tensioned precast connections to offer additional advantages including reduced residual drifts, limited and controlled damage and simple repair options. Novel buckling-restrained, fused mild steel energy dissipators suitable for use in CD connections are also developed and tested. These designs utilise 'dry' fabrication to simplify the fabrication process and minimise cost.
Half-scale experimental testing is carried out to demonstrate both the assembly processes and behaviour under reversed cyclic uniaxial and biaxial loading representing an earthquake event. Following benchmark testing, repair strategies are applied to the CD connection types and the columns are tested again, representing a subsequent earthquake event. Good results are obtained from all cases with relatively straightforward construction and repair processes. With further developments and testing, the connection types proposed can provide competitive alternatives to conventional bridge pier design with regard to seismic performance and life cycle costs, with the additional benefits associated with precast construction.
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Alburqueque, Valdivia Marlon Jesus. "Conversor ressonante para geração de ozônio aplicado à água de processos de higienização industrial, com controle digital /." Ilha Solteira, 2019. http://hdl.handle.net/11449/181188.
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Orientador: Carlos Alberto CanesinResumo: No presente trabalho de dissertação, é analisado e desenvolvido um conversor ressonante com o objetivo de produzir ozônio, aplicado à água de processos de higienização industrial. Na atualidade, no ano de 2018, dois dos fatores de grande importância no desenvolvimento de conversores para geração de ozônio são: a eficiência energética, isto é, quanta energia é aproveitada em relação à energia total fornecida ao conversor, e a outra é a produção de ozônio fazendo uso dessa energia aproveitada. Os dois fatores não necessariamente estão relacionados, por exemplo, para dois conversores distintos com a mesma energia disponível, pode acontecer que em um deles possa ser produzido maiores concentrações de ozônio com um menor aproveitamento de energia. Portanto, este trabalho enfatiza a melhoria da eficiência energética na produção de ozônio, empregando comutação suave nas estruturas envolvidas do conversor ressonante proposto, o que resulta em uma eficiência energética de 91,57%. A estrutura do conversor proposto apresenta dois estágios em cascata, o primeiro deles, um conversor que é responsável por gerar um barramento CC estável de 400,5 V e que atende aos requisitos de fator de potência e distorção harmônica total com valores de 0,994 e 5,79%(para a corrente de entrada), respectivamente, e o segundo, um inversor ressonante capaz de fornecer uma tensão de 4,4 kV com uma frequência de 10 kHz que atua como fonte de alimentação de um reator conformado por câmaras de descarga usadas em ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: In the present dissertation, it is studied and developed a resonant converter in order to produce ozone, applied in water treatment for cleaning processes. Currently, in the year 2018, two of the factors of great importance in the development of converters for ozone generation are: energy efficiency, that is, how much energy is used in relation to the total energy supplied to the converter, and the other is the production of ozone making use of this energy harnessed. The two factors are not necessarily related, for example, for two different converters with the same energy available, it can happen that in one of them can be produced higher concentrations of ozone with a lower use of energy. Therefore, this work emphasizes the improvement of energy efficiency in the production of ozone using soft switching in the involved structures of the proposed resonant converter, which results in an energy efficiency of 91.57%. The structure of the proposed converter has two stages in cascade, the first one, a converter that is responsible for generating a stable DC bus of 400.5 V and that meets the requirements of power factor and total harmonic distortion with values of 0.994 and 5.79% (for the input current), respectively, and the second, a resonant inverter capable of providing a voltage of 4.4 kV with a frequency of 10 kHz which acts as a power supply for a reactor formed by discharge chambers used in ozone generation applications by electric discharge. Naturally, relevant ozone info... (Complete abstract click electronic access below)
Mestre
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Cavalheiro, Thiago. "Avaliação de atenuadores acústicos dissipativos de dutos de sistema de ar-condicionado de aeronaves." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/169414.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2015.Made available in DSpace on 2016-10-19T12:52:05Z (GMT). No. of bitstreams: 1 338249.pdf: 4347153 bytes, checksum: 59db61187240b302a71f5038f99837d7 (MD5) Previous issue date: 2015
Este trabalho aborda a atenuação do ruído de dutos do sistema de ar- condicionado de aeronaves para fins de controle dos níveis de ruído interno de cabine. A atenuação do ruído de banda larga que se propaga no interior dos dutos desse sistema é tipicamente função dos atenuadores dissipativos, revestidos internamente com material poroso. Materiais fibrosos de baixa densidade e estrutura flexível, usados na indústria aeroespacial, se adequam às restrições de volume e massa impostas, sendo aplicados neste propósito. O objetivo deste trabalho é avaliar uma metodologia de predição da perda de transmissão de um atenuador dis-sipativo, composto por material fibroso de estrutura flexível, aplicado em duto de seção circular. Para isso, utiliza-se um modelo em elementos finitos, no qual o material poroso é considerado como um fluido equiva-lente. A caracterização acústica dos materiais porosos é feita através de um método inverso, que faz uso de medições em tubo de impedância e algoritmo de otimização. Uma discussão dos modelos analíticos de pro-pagação acústica em dutos dissipativos de comprimento infinito também é apresentada, primeiramente considerando o material poroso localmen-te reativo e, em seguida, não-localmente reativo. Dois procedimentos experimentais distintos, baseados nas normas ISO 7235 e ASTM E2611, foram empregados para validar o modelo desenvolvido. Os resultados de perda de transmissão obtidos por meio do modelo proposto apresenta-ram boa concordância em relação aos resultados experimentais.
Abstract : This work covers the noise attenuation in ducts of the aircraft air-conditioning system with the purpose to control the noise levels in the cabin. Attenuation of broadband noise which propagates in the ducts of that system is typically a role of dissipative mufflers, lined with porous material. Porous materials with low density and limp frame, usually employed in the aerospace industry, are suitable to the imposed volume and mass constraints, being largely applied for that purpose. The objec-tive of this work is to predict the transmission loss of a dissipative muffler composed by limp frame fiber material applied in a round duct. To do so, a finite element model is developed in which the porous mate-rial is treated as a equivalent fluid. The acoustic characterization of po-rous materials is performed through an inverse method, which uses im-pedance tube measurements and an optimization algorithm. A discussi-on on the analytical models of acoustic propagation in dissipative ducts with infinite length is also presented, firstly using a locally reactive porous material assumption and, then, a non-locally reactive porous material assumption. Two different experimental procedures based on ISO 7235 and ASTM E2611 standards were conducted to validate the developed model. Transmission loss obtained through the proposed model have good agreement compared to the experimental results.
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Cavalheiro, Thiago. "Avaliação de atenuadores acústicos dissipativos de dutos de sistema de ar-condicionado de aeronaves." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/162636.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2015.Made available in DSpace on 2016-05-24T17:30:25Z (GMT). No. of bitstreams: 1 338249.pdf: 4347153 bytes, checksum: 59db61187240b302a71f5038f99837d7 (MD5) Previous issue date: 2015
Este trabalho aborda a atenuação do ruÃdo de dutos do sistema de ar- condicionado de aeronaves para fins de controle dos nÃveis de ruÃdo interno de cabine. A atenuação do ruÃdo de banda larga que se propaga no interior dos dutos desse sistema é tipicamente função dos atenuadores dissipativos, revestidos internamente com material poroso. Materiais fibrosos de baixa densidade e estrutura flexÃvel, usados na indústria aeroespacial, se adequam à s restrições de volume e massa impostas, sendo aplicados neste propósito. O objetivo deste trabalho é avaliar uma metodologia de predição da perda de transmissão de um atenuador dis-sipativo, composto por material fibroso de estrutura flexÃvel, aplicado em duto de seção circular. Para isso, utiliza-se um modelo em elementos finitos, no qual o material poroso é considerado como um fluido equiva-lente. A caracterização acústica dos materiais porosos é feita através de um método inverso, que faz uso de medições em tubo de impedância e algoritmo de otimização. Uma discussão dos modelos analÃticos de pro-pagação acústica em dutos dissipativos de comprimento infinito também é apresentada, primeiramente considerando o material poroso localmen-te reativo e, em seguida, não-localmente reativo. Dois procedimentos experimentais distintos, baseados nas normas ISO 7235 e ASTM E2611, foram empregados para validar o modelo desenvolvido. Os resultados de perda de transmissão obtidos por meio do modelo proposto apresenta-ram boa concordância em relação aos resultados experimentais.
Abstract : This work covers the noise attenuation in ducts of the aircraft air-conditioning system with the purpose to control the noise levels in the cabin. Attenuation of broadband noise which propagates in the ducts of that system is typically a role of dissipative mufflers, lined with porous material. Porous materials with low density and limp frame, usually employed in the aerospace industry, are suitable to the imposed volume and mass constraints, being largely applied for that purpose. The objec-tive of this work is to predict the transmission loss of a dissipative muffler composed by limp frame fiber material applied in a round duct. To do so, a finite element model is developed in which the porous mate-rial is treated as a equivalent fluid. The acoustic characterization of po-rous materials is performed through an inverse method, which uses im-pedance tube measurements and an optimization algorithm. A discussi-on on the analytical models of acoustic propagation in dissipative ducts with infinite length is also presented, firstly using a locally reactive porous material assumption and, then, a non-locally reactive porous material assumption. Two different experimental procedures based on ISO 7235 and ASTM E2611 standards were conducted to validate the developed model. Transmission loss obtained through the proposed model have good agreement compared to the experimental results.
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Coleone, Ana Carla. "Avaliação da dissipação do inseticida malation utilizado em nebulização a ultrabaixo volume no controle da dengue: avaliação ecotoxicológica e de risco ambiental." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/6/6134/tde-05062014-134246/.
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A dengue é um dos principais problemas de Saúde Pública da atualidade. É transmitida por mosquitos do gênero Aedes, sendo a espécie Aedes aegypti o vetor responsável pela transmissão no Brasil. O principal alvo de controle da doença é seu vetor, sendo o controle químico amplamente utilizado em todas as regiões atingidas. Como forma de prevenção ou em períodos de epidemia, torna-se necessária a eliminação dos mosquitos adultos, sendo indicada a nebulização a ultrabaixo volume (UBV) a frio do organofosforado malation por meio do uso de equipamentos pulverizadores acoplados a veículos. Este inseticida utilizado pode sofrer desvios durante e após a aplicação a UBV, caracterizando-se como um potencial agente de desequilíbrio ecológico, podendo atingir e gerar efeitos danosos em organismos não alvos aquáticos e terrestres. Este trabalho teve como objetivo desenvolver e validar um método de análise para o malation em cromatografia líquida de alta eficiência e obter recuperação do inseticida em níveis aceitáveis em água e solo, avaliar seu período de dissipação e tempo de meia vida (t1/2) nestas matrizes e classificá-lo quanto à toxicidade aguda e ao risco ambiental de acordo com diferentes autores, para o microcustáceo Daphnia magna, para a minhoca Eisenia foetida, para o peixe mato grosso (Hyphessobrycon eques) e para a macrófita Lemna minor. O método foi considerado adequado para análise do malation. A recuperação obtida para água foi de 97 por cento e para solo, 96 por cento . Efeitos tóxicos decorrentes da exposição ao inseticida foram observados para todos os organismos, sendo a Daphnia magna a espécie mais sensível aos testes de toxicidade aguda, com alto risco de intoxicação ambiental oriundo do uso peridomiciliar do malation. Em solo, o composto permaneceu na superfície com t1/2 de 4,5 h e sofreu lixiviação após ocorrência de chuva, sendo detectado por até 29 dias após a aplicação. Em água, o t1/2 foi de 0,1 h em pH 9.0 não sendo mais detectado a partir do segundo dia após aplicação. Em pH 7.0 e 5.0, esse período estendeu-se por até 7 dias, sendo o t1/2 de 3,2 e 4,4 d, respectivamente.Dengue is one of the major public health problems nowadays. It is transmitted by mosquitoes of the genus Aedes, and the Aedes aegypti specie is the vector responsible for transmission in Brazil. The main target to control the disease is its vector, and the chemical control is widely used in all affected regions. As a preventive measure or in epidemic periods, it becomes necessary to eliminate adult mosquitoes, being indicated the ultralow volume nebulization of malathion organophosphate in cold way through the use of sprinklers attached to vehicles. This used insecticide can suffer deviation during and after application ULV, characterizing itself as a potential agent of environmental imbalance, with the possibility of reach and generate harmful effects on aquatic and terrestrial non-target organisms. This work had the objective to develop and validate a method of analysis for malathion in high performance liquid chromatography and obtain recovery of insecticide in acceptable levels in water and soil, evaluate its dissipation period and half-life time in these matrices and classify it on acute toxicity and environmental risk according to different authors, to the microcrustacean Daphnia magna, to the earthworm Eisenia foetida, to the fish Hyphessobrycon eques and to the macrophyte Lemna minor. The method was considered appropriate for analysis of malathion. The obtained recovery for water was 97 per cent and for soil, 96 per cent . Toxic effects resulting from exposure to the insecticide were observed for all organisms, resulting that Daphnia magna is the most sensitive species to the acute toxicity tests, with high risk of environmental intoxication originated from malathion peridomicilary use. In soil, the compound remained on the surface with t1/2 of 4.5 h and suffered lixiviation after rain occurrence, being detected for up to 29 days after application. In water, the t1/2 was 0.1 h in pH 9.0 and was not detected from the second day after application. In pH 7.0 and 5.0, this period was extended for up to 7 days, being the t1/2 of 3.2 and 4.4 d, respectively.
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Minelli, Andrea. "Studio di configurazioni di sistemi dissipativi di tipo fluido viscoso per la riduzione della risposta sismica di strutture." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25527/.
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Nel presente lavoro di tesi viene analizzato un sistema alternativo utile al raggiungimento della protezione sismica delle strutture. In particolare, invece di consentire alla struttura di subire deformazioni inelastiche sfruttando la propria duttilità strutturale per dissipare energia, si ricorre a sistemi di controllo passivi quali i dissipatori fluido viscosi e le loro configurazioni all’interno o all’esterno di un sistema strutturale per diminuire l’energia dissipata dalla sola struttura e ridurre la risposta sismica.
Nei primi due capitoli vengono analizzati i sistemi per il controllo strutturale, da quello tradizionale basato su criteri di resistenza e duttilità a quelli passivi, fino ad arrivare a quelli attivi. Particolare attenzione viene rivolta alla comprensione del funzionamento e delle leggi che governano i dissipatori fluido viscosi. Nel terzo capitolo vengono studiati i metodi di analisi, i criteri di progettazione e modellazione dei dispositivi fluido viscosi per arrivare a dimensionare i dispositivi da inserire nel sistema strutturale. Inoltre vengono studiate le diverse configurazioni che possono assumere i dispositivi fluido viscosi all’interno o all’esterno di una struttura, valutandone i vantaggi e gli svantaggi. Una volta presa familiarizzazione col software di calcolo fem e delle analisi time history, nel capitolo quattro si valuta l’effetto delle diverse configurazioni interne o esterne dei dispositivi lineari e non lineari e la diversa distribuzione delle proprietà dei dispositivi lungo l’altezza della struttura di studio. Si procede con il valutare attraverso analisi dinamiche modali non lineari la risposta della struttura di studio priva di dispositivi e le risposte della struttura equipaggiata con diverse configurazioni di dispositivi, per poi confrontarle per arrivare a delle conclusioni in merito alla loro efficacia.
Books on the topic "Dissipative controller"
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Morris, K. A. Dissipative controller designs for second-order dynamic systems. Hampton, Va: Institute for Computer Applications in Science and Engineering, 1990.
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Jer-Nan, Juang, Langley Research Center, and Institute for Computer Applications in Science and Engineering., eds. Dissipative controller designs for second-order dynamic systems. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1990.
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National Aeronautics and Space Administration (NASA) Staff. Robust Control of Uncertain Systems Via Dissipative Lqg-Type Controllers. Independently Published, 2018.
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Lozano, R., B. Brogliato, B. Maschke, and O. Egeland. Dissipative Systems Analysis and Control: Theory and Applications. Springer, 2000.
Find full textBook chapters on the topic "Dissipative controller"
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Gawronski, Wodek K. "Dissipative Controllers." In Dynamics and Control of Structures, 131–41. New York, NY: Springer New York, 1998. http://dx.doi.org/10.1007/978-0-387-21855-7_8.
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Pluhacek, Michal, Roman Senkerik, Donald Davendra, and Ivan Zelinka. "Designing PID Controller for DC Motor by Means of Enhanced PSO Algorithm with Dissipative Chaotic Map." In Advances in Intelligent Systems and Computing, 475–83. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-32922-7_49.
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Gawronski, Wodek. "Balanced Dissipative Controllers." In Balanced Control of Flexible Structures, 147–59. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/3540760172_7.
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Bassani, R., and M. D'Acunto. "Nanotribology: Heat Production and Dissipative Processes in Friction." In Interface Controlled Materials, 310–15. Weinheim, FRG: Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/352760622x.ch50.
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Garrett, Steven L. "Attenuation of Sound." In Understanding Acoustics, 673–98. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44787-8_14.
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Abstract We will capitalize on our understanding of thermoviscous loss to develop an understanding of the attenuation of sound waves in fluids that are not influenced by proximity to solid surfaces. Such dissipation mechanisms are particularly important at very high frequencies and short distances (for ultrasound) or very low frequencies over geological distances (for infrasound). The Standard Linear Model of viscoelasticity introduced the nondimensional frequency, ωτR, that controlled the medium’s elastic (in-phase) and dissipative (quadrature) responses. Those response curves were “universal” in the sense that causality linked the elastic and dissipative responses through the Kramers-Kronig relations. That relaxation-time perspective is essential for attenuation of sound in media that can be characterized by one or more relaxation times related to those internal degrees of freedom that make their equation of state a function of frequency. Examples of these relaxation-time effects include the rate of collisions between different molecular species in a gas (e.g., nitrogen and water vapor in air), the pressure dependence of ionic association-dissociation of dissolved salts in sea water (e.g., MgSO4 and H3BO3), and evaporation-condensation effects when a fluid is oscillating about equilibrium with its vapor (e.g., fog droplets in air or gas bubbles in liquids).
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Isailović, Ivan, Augusto Cannone Falchetto, and Michael P. Wistuba. "Energy Dissipation in Asphalt Mixtures Observed in Different Cyclic Stress-Controlled Fatigue Tests." In RILEM Bookseries, 693–703. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-017-7342-3_56.
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Joelianto, Endra. "Robust H∞ PID Controller Design Via LMI Solution of Dissipative Integral Backstepping with State Feedback Synthesis." In Robust Control, Theory and Applications. InTech, 2011. http://dx.doi.org/10.5772/15821.
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Haddad, Wassim M., and Sergey G. Nersesov. "Hybrid Decentralized Maximum Entropy Control for Large-Scale Systems." In Stability and Control of Large-Scale Dynamical Systems. Princeton University Press, 2011. http://dx.doi.org/10.23943/princeton/9780691153469.003.0013.
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This chapter introduces a novel class of fixed-order, energy- and entropy-based hybrid decentralized controllers for achieving enhanced energy dissipation in large-scale vector lossless and vector dissipative systems based on subsystem decomposition. These dynamic decentralized controllers combine a logical switching architecture with continuous dynamics to guarantee that the system plant energy is strictly decreasing across switchings. The general framework leads to hybrid closed-loop systems described by impulsive differential equations. The chapter also constructs hybrid dynamic controllers that guarantee that each subsystem-subcontroller pair of the hybrid closed-loop system is consistent with basic thermodynamic principles. Special cases of energy-based hybrid controllers involving state-dependent switching are described, and several illustrative examples are given and an experimental test bed is designed to demonstrate the efficacy of the proposed approach.
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Bruno Lodi, Matteo, and Alessandro Fanti. "Biomedical Applications of Biomaterials Functionalized with Magnetic Nanoparticles." In Smart Nanosystems for Biomedicine, Optoelectronics and Catalysis. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.89199.
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The combination of magnetic nanoparticles and a biocompatible material leads to the manufacturing of a multifunctional and remotely controlled platform useful for diverse biomedical issues. If a static magnetic field is applied, a magnetic scaffold behaves like an attraction platform for magnetic carriers of growth factors, thus being a potential tool to enhance magnetic drug delivery in regenerative medicine. To translate in practice this potential application, a careful and critical description of the physics and the influence parameter is required. This chapter covers the mathematical modeling of the process and assesses the problem of establishing the influence of the drug delivery system on tissue regeneration. On the other hand, if a time-varying magnetic field is applied, the magnetic nanoparticles would dissipate heat, which can be exploited to perform local hyperthermia treatment on residual cancer cells in the bone tissue. To perform the treatment planning, it is necessary to account for the modeling of the intrinsic nonlinear nature of the heat dissipation dynamic in magnetic prosthetic implants. In this work, numeric experiments to investigate the physiopathological features of the biological system, linked to the properties of the nanocomposite magnetic material, to assess its effectiveness as therapeutic agents are presented.
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Hassine, Siwar Ben Haj, and Bouraoui Ouni. "Typical Design of Synchronous Controller to Minimize Response Time and Power." In Handbook of Research on Power and Energy System Optimization, 292–321. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-3935-3.ch009.
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As power dissipation and time constraint have become vital challenges during the creation of a digital circuit, researchers' and designers' efforts have increased to figure out new ways of preserving power through the study of its sources and its impacts as well as through the decrease of response time to obtain faster treatments. However, it is widely acknowledged that these two parameters are antagonistic in synchronous systems. In fact, current technologies have managed to further decrease the response time to have a faster circuit at the cost of a considerable simultaneous augmentation in its power or vice versa, which leaves no option for designers but to choose from these two important parameters. Hence, the main objective of this chapter is to propose a design method that simultaneously builds a low power design and provides a faster circuit. For the achievement of that purpose, a controller based on a finite state machine (FSM) has been chosen as an example of synchronous system to prove that the new proposed design can optimize both parameters: time and power.
Conference papers on the topic "Dissipative controller"
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Haddad, Wassim M., Dennis S. Bernstein, and Y. William Wang. "Dissipative H2/h∞ controller synthesis." In 1993 American Control Conference. IEEE, 1993. http://dx.doi.org/10.23919/acc.1993.4792846.
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Lin, Qiongbin, Fuwen Yang, and Wu Wang. "Dissipative fuzzy controller for networked nonlinear system with missing data." In 2009 Chinese Control and Decision Conference (CCDC). IEEE, 2009. http://dx.doi.org/10.1109/ccdc.2009.5194942.
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Sredojev, Sonja, and Ray Eaton. "Model predictive controller for a class of nonlinear dissipative systems." In 2014 American Control Conference - ACC 2014. IEEE, 2014. http://dx.doi.org/10.1109/acc.2014.6859043.
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Li, Hong, Hongyang Cai, and Shuhui Shi. "Non-fragile dissipative control for uncertain singular systems via PD controller." In 2016 Chinese Control and Decision Conference (CCDC). IEEE, 2016. http://dx.doi.org/10.1109/ccdc.2016.7530991.
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Dong, Zhe, Xiaojin Huang, and Liangju Zhang. "Output-Feedback Load-Following Control of Nuclear Reactors Based on a Dissipative High Gain Filter." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29056.
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Due to the existing serious climate and environment problems caused by burning fossil fuels, nuclear energy is now rapidly developed. Power-level control for nuclear reactors is significant for not only regular operating but also safety issues. The advances in computer technology, information processing, and control theory in the past decades allow the applications of advanced controllers with higher performance. In this paper, the separation principle for the recently established dissipation based high gain filter (DHGF) is presented, which guarantees the closed-loop stability of the system interconnected with a state-feedback controller and the DHGF. Then, the feasibility of applying the DHGF to the load-following control of nuclear reactors has then been verified. Finally, the DHGF with a well designed state-feedback power-level controller has been successfully applied to realize the load-following control for a nuclear heating reactor (NHR). Numerical simulation results has shown the high performance of the DHGF and the feasibility of the DHGF-based output feedback control strategy, and influence of the observer gain to the control and observation performance has also been analyzed.
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Umoh, Edwin A. "Bounds of Fuzzy Controller output scaling gains for stabilization of a dissipative chaotic system." In 2013 IEEE International Conference on Emerging & Sustainable Technologies for Power & ICT in a Developing Society (NIGERCON). IEEE, 2013. http://dx.doi.org/10.1109/nigercon.2013.6715658.
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Matiakis, Tilemachos, and Sandra Hirche. "Delay-independent stability of (Q, S, R)-dissipative networked systems with a distributed controller." In 2009 European Control Conference (ECC). IEEE, 2009. http://dx.doi.org/10.23919/ecc.2009.7074756.
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Anubi, Olugbenga M., and Carl D. Crane. "Nonlinear Control of Semi-Active MacPherson Suspension System." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71179.
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This paper presents the control design and analysis of a non-linear model of a MacPherson suspension system equipped with a magnetorheological (MR) damper. The model suspension considered incorporates the kinematics of the suspension linkages. An output feedback controller is developed using an ℒ2-gain analysis based on the concept of energy dissipation. The controller is effectively a smooth saturated PID. The performance of the closed-loop system is compared with a purely passive MacPherson suspension system and a semi-active damper, whose damping coefficient is tunned by a Skyhook-Acceleration Driven Damping (SH-ADD) method. Simulation results show that the developed controller outperforms the passive case at both the rattle space, tire hop frequencies and the SH-ADD at tire hop frequency while showing a close performance to the SH-ADD at the rattle space frequency. Time domain simulation results confirmed that the control strategy satisfies the dissipative constraint.
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Innocenti, Giacomo, and Michele Basso. "An approach to event-triggered control of unstable dissipative systems exemplified via PI controller Giacomo Innocenti." In 2018 17th European Control Conference (ECC). IEEE, 2018. http://dx.doi.org/10.23919/ecc.2018.8550453.
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Balas, Mark J., and Susan A. Frost. "A Stabilization of Fixed Gain Controlled Infinite Dimensional Systems by Augmentation With Direct Adaptive Control." In ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/smasis2017-3726.
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Linear infinite dimensional systems are described by a closed, densely defined linear operator that generates a continuous semigroup of bounded operators on a general Hilbert space of states and are controlled via a finite number of actuators and sensors. Many distributed applications are included in this formulation, such as large flexible aerospace structures, adaptive optics, diffusion reactions, smart electric power grids, and quantum information systems. We have developed the following stability result: an infinite dimensional linear system is Almost Strictly Dissipative (ASD) if and only if its high frequency gain CB is symmetric and positive definite and the open loop system is minimum phase, i.e. its transmission zeros are all exponentially stable. In this paper, we focus on infinite dimensional linear systems for which a fixed gain linear infinite or finite dimensional controller is already in place. It is usually true that fixed gain controllers are designed for particular applications but these controllers may not be able to stabilize the plant under all variations in the operating domain. Therefore we propose to augment this fixed gain controller with a relatively simple direct adaptive controller that will maintain stability of the full closed loop system over a much larger domain of operation. This can ensure that a flexible structure controller based on a reduced order model will still maintain closed-loop stability in the presence of unmodeled system dynamics. The augmentation approach is also valuable to reduce risk in loss of control situations. First we show that the transmission zeros of the augmented infinite dimensional system are the open loop plant transmission zeros and the eigenvalues (or poles) of the fixed gain controller. So when the open-loop plant transmission zeros are exponentially stable, the addition of any stable fixed gain controller does not alter the stability of the transmission zeros. Therefore the combined plant plus controller is ASD and the closed loop stability when the direct adaptive controller augments this combined system is retained. Consequently direct adaptive augmentation of controlled linear infinite dimensional systems can produce robust stabilization even when the fixed gain controller is based on approximation of the original system. These results are illustrated by application to a general infinite dimensional model described by nuclear operators with compact resolvent which are representative of distributed parameter models of mechanically flexible structures. with a reduced order model based controller and adaptive augmentation.
Reports on the topic "Dissipative controller"
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Gambill, Daniel, Matthew Stoklosa, Sean Matus, Heidi Howard, and Garrett Feezor. White Sands Missile Range Thurgood Canyon watershed : analysis of Range Road 7 for development of best management practices and recommendations. Engineer Research and Development Center (U.S.), September 2022. http://dx.doi.org/10.21079/11681/45622.
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Thurgood Canyon, located on White Sands Missile Range (WSMR), contains an alluvial fan that is bisected by a primary installation road and is in the proximity of sensitive fish habitats. This project was initiated to determine if and how sensitive fish habitats at the base of the fan are impacted by the existing drainage infrastructure and to assess the condition and sustainability of the existing transportation infrastructure. Findings show that the current drainage infrastructure maintains flow energy and sediment carrying capacity further down the fan than would occur in its absence. However, frequent to moderately rare (small to medium) flood events dissipate over 2 km from sensitive habitat, and overland flow and sediment do not reach the base of the fan. Controlled flow diversion is recommended upstream of the road to mitigate infrastructure or habitat impacts during very rare (very large) flood events. A comprehensive operation and management approach is presented to achieve sustainable transportation infrastructure and reduce the likelihood of impacts to the sensitive habitat.
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Gerstl, Zev, Thomas L. Potter, David Bosch, Timothy Strickland, Clint Truman, Theodore Webster, Shmuel Assouline, Baruch Rubin, Shlomo Nir, and Yael Mishael. Novel Herbicide Formulations for Conservation-Tillage. United States Department of Agriculture, June 2009. http://dx.doi.org/10.32747/2009.7591736.bard.
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The overall objective of this study was to develop, optimize and evaluate novel formulations, which reduce herbicide leaching and enhance agronomic efficacy. Numerous studies have demonstrated that CsT promotes environmental quality and enhances sustainable crop production, yet continued use of CsT-practices appears threatened unless cost effective alternative weed control practices can be found. The problem is pressing in the southern portion of the Atlantic Coastal Plain region of the eastern USA where cotton and peanut are produced extensively. This research addressed needs of the region’s farmers for more effective weed control practices for CsT systems. HUJI: CRFs for sulfentrazone and metolachlor were developed and tested based on their solubilizion in cationic micelles and adsorption of the mixed micelles on montmorillonite. A better understanding of solubilizing anionic and nonionic organic molecules in cationic micelles was reached. Both CRFs demonstrated controlled release compared to the commercial formulations. A bioassay in soil columns determined that the new sulfentrazone and metolachlor CRFs significantly improve weed control and reduced leaching (for the latter) in comparison with the commercial formulations. ARO: Two types of CRFs were developed: polymer-clay beads and powdered formulations. Sand filter experiments were conducted to determine the release of the herbicide from the CRFs. The concentration of metolachlor in the initial fractions of the effluent from the commercial formulation reached rather high values, whereas from the alginate-clay formulations and some of the powdered formulations, metolachlor concentrations were low and fairly constant. The movement of metolachlor through a sandy soil from commercial and alginate-clay formulations showed that the CRFs developed significantly reduced the leaching of metolachlor in comparison to the commercial formulation. Mini-flume and simulated rainfall studies indicated that all the CRFs tested increased runoff losses and decreased the amount of metolachlor found in the leachate. ARS: Field and laboratory investigations were conducted on the environmental fate and weed control efficacy of a commercially available, and two CRFs (organo-clay and alginate-encapsulated) of the soil-residual herbicide metolachlor. The environmental fate characteristics and weed control efficacy of these products were compared in rainfall simulations, soil dissipations, greenhouse efficacy trials, and a leaching study. Comparisons were made on the basis of tillage, CsT, and conventional, i.e no surface crop residue at planting (CT). Strip-tillage (ST), a commonly used form of CsT, was practiced. The organo-clay and commercial metolachlor formulations behaved similarly in terms of wash off, runoff, soil dissipation and weed control efficacy. No advantage of the organo-clay over the commercial metolachlor was observed. Alginate encapsulated metolachlor was more promising. The dissipation rate for metolachlor when applied in the alginate formulation was 10 times slower than when the commercial product was used inferring that its use may enhance weed management in cotton and peanut fields in the region. In addition, comparison of alginate and commercial formulations showed that ST can effectively reduce the runoff threat that is commonly associated with granular herbicide application. Studies also showed that use of the alginate CRF has the potential to reduce metolachlor leaching. Overall study findings have indicated that use of granular herbicide formulations may have substantial benefit for ST-system weed management for cotton and peanut production under Atlantic Coastal Plain conditions in the southeastern USA. Commercial development and evaluation at the farm scale appears warranted. Products will likely enhance and maintain CsT use in this and other regions by improving weed control options.
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Wu, Yingjie, Selim Gunay, and Khalid Mosalam. Hybrid Simulations for the Seismic Evaluation of Resilient Highway Bridge Systems. Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, November 2020. http://dx.doi.org/10.55461/ytgv8834.
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Bridges often serve as key links in local and national transportation networks. Bridge closures can result in severe costs, not only in the form of repair or replacement, but also in the form of economic losses related to medium- and long-term interruption of businesses and disruption to surrounding communities. In addition, continuous functionality of bridges is very important after any seismic event for emergency response and recovery purposes. Considering the importance of these structures, the associated structural design philosophy is shifting from collapse prevention to maintaining functionality in the aftermath of moderate to strong earthquakes, referred to as “resiliency” in earthquake engineering research. Moreover, the associated construction philosophy is being modernized with the utilization of accelerated bridge construction (ABC) techniques, which strive to reduce the impact of construction on traffic, society, economy and on-site safety. This report presents two bridge systems that target the aforementioned issues. A study that combined numerical and experimental research was undertaken to characterize the seismic performance of these bridge systems. The first part of the study focuses on the structural system-level response of highway bridges that incorporate a class of innovative connecting devices called the “V-connector,”, which can be used to connect two components in a structural system, e.g., the column and the bridge deck, or the column and its foundation. This device, designed by ACII, Inc., results in an isolation surface at the connection plane via a connector rod placed in a V-shaped tube that is embedded into the concrete. Energy dissipation is provided by friction between a special washer located around the V-shaped tube and a top plate. Because of the period elongation due to the isolation layer and the limited amount of force transferred by the relatively flexible connector rod, bridge columns are protected from experiencing damage, thus leading to improved seismic behavior. The V-connector system also facilitates the ABC by allowing on-site assembly of prefabricated structural parts including those of the V-connector. A single-column, two-span highway bridge located in Northern California was used for the proof-of-concept of the proposed V-connector protective system. The V-connector was designed to result in an elastic bridge response based on nonlinear dynamic analyses of the bridge model with the V-connector. Accordingly, a one-third scale V-connector was fabricated based on a set of selected design parameters. A quasi-static cyclic test was first conducted to characterize the force-displacement relationship of the V-connector, followed by a hybrid simulation (HS) test in the longitudinal direction of the bridge to verify the intended linear elastic response of the bridge system. In the HS test, all bridge components were analytically modeled except for the V-connector, which was simulated as the experimental substructure in a specially designed and constructed test setup. Linear elastic bridge response was confirmed according to the HS results. The response of the bridge with the V-connector was compared against that of the as-built bridge without the V-connector, which experienced significant column damage. These results justified the effectiveness of this innovative device. The second part of the study presents the HS test conducted on a one-third scale two-column bridge bent with self-centering columns (broadly defined as “resilient columns” in this study) to reduce (or ultimately eliminate) any residual drifts. The comparison of the HS test with a previously conducted shaking table test on an identical bridge bent is one of the highlights of this study. The concept of resiliency was incorporated in the design of the bridge bent columns characterized by a well-balanced combination of self-centering, rocking, and energy-dissipating mechanisms. This combination is expected to lead to minimum damage and low levels of residual drifts. The ABC is achieved by utilizing precast columns and end members (cap beam and foundation) through an innovative socket connection. In order to conduct the HS test, a new hybrid simulation system (HSS) was developed, utilizing commonly available software and hardware components in most structural laboratories including: a computational platform using Matlab/Simulink [MathWorks 2015], an interface hardware/software platform dSPACE [2017], and MTS controllers and data acquisition (DAQ) system for the utilized actuators and sensors. Proper operation of the HSS was verified using a trial run without the test specimen before the actual HS test. In the conducted HS test, the two-column bridge bent was simulated as the experimental substructure while modeling the horizontal and vertical inertia masses and corresponding mass proportional damping in the computer. The same ground motions from the shaking table test, consisting of one horizontal component and the vertical component, were applied as input excitations to the equations of motion in the HS. Good matching was obtained between the shaking table and the HS test results, demonstrating the appropriateness of the defined governing equations of motion and the employed damping model, in addition to the reliability of the developed HSS with minimum simulation errors. The small residual drifts and the minimum level of structural damage at large peak drift levels demonstrated the superior seismic response of the innovative design of the bridge bent with self-centering columns. The reliability of the developed HS approach motivated performing a follow-up HS study focusing on the transverse direction of the bridge, where the entire two-span bridge deck and its abutments represented the computational substructure, while the two-column bridge bent was the physical substructure. This investigation was effective in shedding light on the system-level performance of the entire bridge system that incorporated innovative bridge bent design beyond what can be achieved via shaking table tests, which are usually limited by large-scale bridge system testing capacities.
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THE SEISMIC PERFORMANCE OF DOUBLE TUBE BUCKLING RESTRAINED BRACE WITH CAST STEEL CONNECTORS. The Hong Kong Institute of Steel Construction, March 2022. http://dx.doi.org/10.18057/ijasc.2022.18.1.2.
Full textAbstract:
The special concentrically braced frame (SCBF) is an aseismic structure, but its bracing system exhibits brittle failure and premature buckling connected with the weld fracture of the gusset plate and the post-buckling of the braces; thus, maximizing the role of energy dissipation is difficult. Here, this paper proposes a system of double-tube buckling-restrained brace with cast steel connectors for steel SCBFs. The large inelastic deformation of the bracing system is mainly concentrated in the ductile cast connectors under the earthquake, and the degree of buckling and post-buckling of braces can be reduced. Cyclic loading tests were conducted on two groups of specimens with different parameters, then the deformation trend, stress distribution, energy dissipation capacity, and stiffness degradation of the specimens were analyzed. The improved measures of increasing the width–thickness ratio of the energy dissipation plate and stiffener and casting the end right-angle tip tightly for a certain length of cast connector in Group 2 specimens, which overcomes the brittle fracture caused by the crack of the connection segment due to flexural buckling in Group 1 specimen tests, was evaluated. The cast steel connector conducts the main energy dissipation member that exhibits good ductile and energy absorption performance, and the advantages of using improved ductile cast steel connectors to obtain the energy dissipation of BRBs are illustrated. The test results provided direct evidence that the seismic performance of specimens is closely associated with the length of the energy dissipation segment of the cast connector and the overstrength factor of axial force. Also, the strength, rigidity, deformation, and energy dissipation performance of the members can be independently controlled by reasonably designing the cast connector. Our results provide the underlying insights needed to guide the design of the bracing connector.