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Projeto de sistemas de controle multivariáveis robustos com especificações no domínio do tempo.; Robust multivariable control systems design with time domain specifications.

Leonardi, Fabrizio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/11/2002 PT
Relevância na Pesquisa
15.9%
Este trabalho discute o projeto de compensadores multivariáveis robustos com especificações no domínio do tempo. Primeiramente faz-se a análise dos compensadores por observadores de estados como forma de atingir tais objetivos. Mostra-se que, em certas condições, essa estrutura equivale à dos observadores proporcionais-integrais e apresentam-se as condições de estabilidade nominal. Evidencia-se também que é possível tratar esse problema de controle como um problema de "model matching" ou como um problema de controle com dois graus de liberdade. Mostra-se também que o projeto do compensador é equivalente ao projeto de sistemas de controle por realimentação estática da saída. Essa equivalência implica que, embora os compensadores por observadores sejam cômodos à incorporação de especificações temporais, sua estrutura é limitada para garantir que especificações gerais sejam satisfeitas. Contorna-se então essa limitação estendendo-se o estudo ao caso dos compensadores sem essa restrição estrutural. O problema de "model matching" e o problema de controle 2﷓D são considerados como forma indireta de incorporar-se as especificações temporais e condições de projeto são obtidas reduzindo-se os possíveis conservadorismos dos projetos usuais. Ainda neste sentido...

Detecção e localização de falhas via observadores de estado e de ordem reduzida; Faults detection and isolation using reduced-order state observers

Gilberto Pechoto de Melo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 14/08/1998 PT
Relevância na Pesquisa
45.96%
Um dos fatores do grande interesse no desenvolvimento de novas técnicas de detecção de falhas é devido ao aumento da demanda da indústria em relação a segurança de seus sistemas, sendo eles supervisionados e monitorados para que as falhas sejam sanadas o mais rápido possível e que os distúrbios em operação normal não causem uma deterioração da performance dos mesmos. Neste trabalho, desenvolveu-se uma metodologia para detecção e localização de falhas em sistemas mecânicos utilizando observadores de estado de ordem reduzida. O método pode reconstruir os estados não medidos ou os valores provenientes de pontos de difícil acesso no sistema. Os parâmetros de interesse sujeitos a falhas são escolhidos, projetando-se um observador global otimizado para análise de todo o sistema considerando possíveis perturbações aleatórias na excitação, na resposta e falhas nos sensores. Projeta-se também observadores robustos a estes parâmetros de interesse, que localizam possíveis falhas ou irregularidades no sistema. Para os componentes que necessitem de um acompanhamento periódico devido às suas grandes solicitações ou falhas constantes, montam-se observadores com um sistema de alarmes que gera uma curva de tendências em um sistema automático para detecção e localização de falhas desenvolvido neste trabalho. Para os sistemas simulados e experimental...

Redes neurais artificiais dinâmicas aplicadas a detecção automática de eventos comportamentais

Canena, Ângeluz da Costa
Fonte: Florianópolis Publicador: Florianópolis
Tipo: Dissertação de Mestrado Formato: 99 p.| il., grafs., tabs.
POR
Relevância na Pesquisa
15.65%
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.; Registros comportamentais realizados de forma automatizada reduzem a influência de erros causados por fadiga e alerta sob os quais um observador humano está sujeito. O método de registro automático estudado em (CRISPIM, 2011) apresentou-se eficiente, embora não diferencie a ordem temporal de posturas a formar padrões de comportamento e suas diferentes durações. Neste trabalho investigamos o uso de uma rede neural artificial anteroalimentada com atrasos de tempo focados na entrada, através da qual foi possível observar o efeito de diferentes atrasos na detecção das diferentes categorias de comportamento (I - Imobilidade, L - Locomoção, V - Exploração vertical e A - Auto-limpeza). Além disso, foi feita uma comparação entre a detecção automática pelos classificadores treinados e a classificação por observadores humanos. Exceto pelo desempenho na detecção da categoria "A", os valores médios deste foram altos (Índices Kappa >0,75 e AUC >0,8) no conjunto de amostras de validação (pré-processadas - balanceadas e sem transições). Já no teste uma grande redução no desempenho foi observada...

Interactions of cetaceans with Spanish and Portuguese fisheries in Atlantic waters : costs, benefits and implications for management; Interações entre cetáceos e as pescas portuguesas e espanholas em águas do Atlântico : custos, benefícios e implicações para a gestão

Goetz, Sabine
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
15.74%
With the aim to provide new insights into operational cetacean-fishery interactions in Atlantic waters, this thesis assesses interactions of cetaceans with Spanish and Portuguese fishing vessels operating in Iberian and South West Atlantic waters. Different opportunistic research methodologies were applied, including an interview survey with fishers (mainly skippers) and onboard observations by fisheries observers and skippers, to describe different types of interactions and to identify potential hotspots for cetacean-fishery interactions and the cetacean species most involved, and to quantify the extent and the consequences of these interactions in terms of benefits and costs for cetaceans and fisheries. In addition, the suitability of different mitigation strategies was evaluated and discussed. The results of this work indicate that cetaceans interact frequently with Spanish and Portuguese fishing vessels, sometimes in a beneficial way (e.g. cetaceans indicate fish schools in purse seine fisheries), but mostly with negative consequences (depredation on catch, gear damage and cetacean bycatch). Significant economic loss and high bycatch rates are, however, only reported for certain fisheries and associated with particular cetacean species. In Galician fisheries...

The effect of masker level uncertainty on intensity discrimination

Buss, Emily
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/2008 EN
Relevância na Pesquisa
15.71%
Thresholds were measured for detection of an increment in level of a 60-dB SPL target tone at 1 kHz, either in quiet or in the presence of maskers at 0.5 and 2 kHz. Interval-by-interval level rove applied independently to remote masker tones substantially elevated thresholds compared to intensity discrimination in quiet, an effect on the order of 10+ dB [10log(ΔI/I)]. Asynchronous onset and stimulus envelope mismatches across frequency reduced but did not eliminate masking. A pre-interval cue to signal frequency had no effect, but cuing masker frequency reduced thresholds, whether or not masker level was also cued. About 1–2 dB of threshold elevation in these conditions can be attributed to energetic masking. Decreasing the overall presentation level and increasing masker separation essentially eliminates energetic masking; under these conditions masker level rove elevates thresholds by approximately 7 dB when the target and masker tones are gated synchronously. This masking persists even when the flanking masker tones are presented contralateral to the target. Results suggest that observers tend to listen synthetically, even in conditions when this strategy reduces sensitivity to the intensity increment.

Lumbopelvic alignment on standing lateral radiograph of adult volunteers and the classification in the sagittal alignment of lumbar spine

Chanplakorn, Pongsthorn; Wongsak, Siwadol; Woratanarat, Patarawan; Wajanavisit, Wiwat; Laohacharoensombat, Wichien
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
15.65%
The analysis of the sagittal balance is important for the understanding of the lumbopelvic biomechanics. Results from previous studies documented the correlation between sacro-pelvic orientation and lumbar lordosis and a uniqueness of spino-pelvic alignment in an individual person. This study was subjected to determine the lumbopelvic orientation using pelvic radius measurement technique. The standing lateral radiographs in a standardized standing position were taken from 100 healthy volunteers. The measurements which included hip axis (HA), pelvic radius (PR), pelvic angle (PA), pelvic morphology (PR-S1), sacral translation distance (HA-S1), total lumbosacral lordosis (T12-S1), total lumbopelvic lordosis (PR-T12) and regional lumbopelvic lordosis angles (PR-L2, PR-L4 and PR-L5) were carried out with two independent observers. The relationships between the parameters were as follows. PR-S1 demonstrated positive correlation to regional lumbopelvic lordosis and revealed negative correlation to T12-S1. PA showed negative correlation to PR-S1 and regional lumbopelvic lordosis, but revealed positive correlation to HA-S1. T12-S1 was significantly increased when PR-S1 was lesser than average (35°–45°) and was significantly decreased when PR-S1 was above the average. PR-L4 and PR-L5 were significantly reduced when PR-S1 was smaller than average and only PR-L5 was significantly increased when PR-S1 was above the average. In conclusion...

Multiple input sliding mode control for autonomous diving and steering of underwater vehicles

Hawkinson, Todd D.
Fonte: Monterey, California: Naval Postgraduate School Publicador: Monterey, California: Naval Postgraduate School
Tipo: Tese de Doutorado
Relevância na Pesquisa
35.73%
Approved for public release; distribution is unlimited.; Design and analysis of multiple input autopilots using sliding modes in order to achieve accurate horizontal and vertical plane control of an autonomous underwater vehicle over a wide variation of speeds is presented. The simulated vehicle is equipped with two (fore and aft) sets of dive planes and two sets of rudders. In addition, two vertical and two horizontal thrusters are provided for control during low speed or hovering operations. The entire range of vehicle speeds from zero speed hovering to full speed ahead is divided into regions depending on control efficiency. Thrusters are used for low speed hovering, control surfaces for transition speeds. Linear quadratic regulator optimal control techniques coupled with the robustness properties of sliding mode control are utilized to provide the necessary control reversal which occurs during the transition from cruise to hover mode. Constant disturbances arising from underwater currents are effectively compensated resulting in accurate path keeping. As a consequence of the multiple input control methodology developed in this work, it is shown that both path and orientation accuracy can be achieved in moderate cross current environments. Finally...

Robust model-based fault diganosis [sic] for a DC zonal electrical distribution system

Stevens, John D.
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
Formato: xvi, 182 p. ; 28 cm.
Relevância na Pesquisa
25.83%
A key element of the U.S. Navy's transition to an electric naval force is an Integrated Power System (IPS) that provides continuity of service to vital systems despite combat damage. In order to meet subsequent survivability standards under a reduced manning constraint, the IPS system must include a fault tolerant control scheme, capable of achieving automated graceful degradation despite major disruptions involving cascading failures. Toward this objective, online modelbased residual generation techniques are proposed, which identify explicitly defined faults within a stochastic DC Zonal Electrical Distribution System (DC ZEDS). Two novel polynomial approaches to the design of unknown input observers (UIO) are developed to estimate the partial state and, under certain conditions, the unknown input. These methods are shown to apply to a larger class of systems compared to standard projection based approaches where the UIO rank condition is not satisfied. It is shown that the partial-state estimate is sufficient to the computation of residuals for fault diagnosis, even in such cases where full-state estimation is not possible. In order to reduce the complexity of the system, a modular approach to Fault Detection and Isolation (FDI) is presented. Here...

Comparative ecology, and conservation, of the Melithreptus genus in the Southern Mount Lofty Ranges, South Australia

Willoughby, Nigel
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 334324 bytes; 1439081 bytes; 1843878 bytes; 129916 bytes; application/pdf; application/pdf; application/pdf; application/pdf
Publicado em //2005 EN
Relevância na Pesquisa
15.71%
The work presented in this thesis aimed to do the following : 1. investigate the cause of decline of the three Melithreptus species of the Mt Lofty Ranges, with a particular emphasis on M. gularis due to its critical status in the ranges ; 2. investigate the ecology and behaviour of sympatric M. brevirostris and M. lunatus populations in the Mt Lofty Ranges ; and 3. suggest management options for the three species. Further, it became clear through the course of the project that an understanding of the decline in Melithreptus required : 1. comparisons with other honeyeater species, particularly widespread and abundant honeyeater species. Three species of Melithreptus occur in the Mt Lofty Ranges : Brown - headed Honeyeater Melithreptus brevirostris ; White - naped Honeyeater Melithreptus lunatus ; and Black - chinned Honeyeater Melithreptus gularis. Since at least the 1970 ' s all three species have been in decline within the ranges. One species has been reduced in both abundance and distribution within the region ( M. gularis ), while the other two are now recognised as having reduced in abundance. Melithreptus species in the Mt Lofty Ranges are sympatric with strikingly similar ecology. Melithreptus gularis is the largest of the three...

Hybrid dead-beat observers for a class of nonlinear systems

Karafyllis, Iasson; Jiang, Zhong-Ping
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.7%
This paper studies the reduced-order or full-order, dead-beat observer problem for a class of nonlinear systems, linear in the unmeasured states. A novel hybrid observer design strategy is proposed, with the help of the notion of strong observability in finite time. The proposed methodology is applied to a batch reactor, for which a hybrid dead-beat observer is obtained in the absence of the precise measurements of the concentration variables. Moreover, the observer is used for the estimation of the frequency of a sinusoidal signal. The results show that accurate estimations can be provided even if the signal is corrupted by high frequency noise.; Comment: 19 pages, 4 figures, submitted to Systems and Control Letters for possible publication

A Short Note for the Robustness Properties of Hybrid Dead-Beat Observers

Karafyllis, Iasson; Jiang, Zhong-Ping
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 18/02/2011
Relevância na Pesquisa
35.7%
A discussion of the robustness properties of the proposed observer with respect to measurement errors is provided for the recently proposed full-order and reduced-order, hybrid, dead-beat observer for a class of nonlinear systems, linear in the unmeasured states.; Comment: 9 pages

Explicit Reduced-Order Integral Formulations of State and Parameter Estimation Problems for a Class of Nonlinear Systems

Tyukin, I. Yu.; Gorban, A. N.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.7%
We propose a technique for reformulation of state and parameter estimation problems as that of matching explicitly computable definite integrals with known kernels to data. The technique applies for a class of systems of nonlinear ordinary differential equations and is aimed to exploit parallel computational streams in order to increase speed of calculations. The idea is based on the classical adaptive observers design. It has been shown that in case the data is periodic it may be possible to reduce dimensionality of the inference problem to that of the dimension of the vector of parameters entering the right-hand side of the model nonlinearly. Performance and practical implications of the method are illustrated on a benchmark model governing dynamics of voltage in generated in barnacle giant muscle.

The Copenhagen Interpretation as an Emergent Phenomenon

Hollowood, Timothy J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 18/02/2013
Relevância na Pesquisa
15.7%
The Copenhagen interpretation has been remarkably successful but seems at odds with the underlying linearity of quantum mechanics. We show how it can emerge in a simple way from the underlying microscopic quantum world governed by Schrodinger's equation without the need for observers or their brains. In order to achieve this, we assemble pieces of various pre-existing ideas. Firstly, we adopt a relational approach and use the eigenvectors of the reduced density matrix of a quantum sub-system, or equivalently the Schmidt decomposition, to define the `internal state' of a sub-system. Previous work has identified serious objections to such an interpretation because it apparently leads to macroscopic superpositions and physically unacceptable instabilities near degeneracies. We show that both these problems are solved if the sub-system consists of a large number of coarse grained degrees of freedom as one expects in order to make contact with the classical world. We further argue that coarse graining is a necessary ingredient because measuring devices have both finite spatial and temporal resolutions. What results is an interpretation in which both decoherence and coarse graining play key roles and from which the rules of the Copenhagen interpretation are seen to emerge in realistic situations that include the measurement of the position of a particle and a decay process.; Comment: 33 pages...

Control Contraction Metrics, Robust Control and Observer Duality

Manchester, Ian R.; Slotine, Jean-Jacques E.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.65%
This paper addresses the problems of stabilization, robust control, and observer design for nonlinear systems. We build upon recently a proposed method based on contraction theory and convex optimization, extending the class of systems to which it is applicable. We prove converse results for mechanical systems and feedback-linearizable systems. Next we consider robust control, and give a simple construction of a controller guaranteeing an L2-gain condition, and discuss connections to nonlinear H-infinity control. Finally, we discuss a "duality" result between nonlinear stabilization problems and observer construction, in the process constructing globally stable reduced-order observers for a class of nonlinear systems.; Comment: Conference submission and working paper

Reduced Order Dead-Beat Observers for a Bioreactor

Karafyllis, Iasson; Jiang, Zhong-Ping
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 25/06/2010
Relevância na Pesquisa
45.77%
This paper studies the strong observability property and the reduced-order dead-beat observer design problem for a continuous bioreactor. New relationships between coexistence and strong observability, and checkable sufficient conditions for strong observability, are established for a chemostat with two competing microbial species. Furthermore, the dynamic output feedback stabilization problem is solved for the case of one species.

Entangled spinning particles in charged and rotating black holes

Robledo-Padilla, Felipe; Garcia-Compean, Hugo
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
15.89%
Spin precession for an EPR pair of spin-1/2 particles in equatorial orbits around a Kerr-Newman black hole is studied. Hovering observers are introduced to ensure fixed reference frames in order to perform the Wigner rotation. These observers also guarantee a reliable direction to compare spin states in rotating black holes. The velocity of the particle due frame-dragging is explicitly incorporated by addition of velocities with respect the hovering observers and the corresponding spin precession angle is computed. The spin-singlet state is observed to be mixed with the spin-triplet by dynamical and gravity effects, thus it is found that a perfect anti-correlation of entangled states for these observers is deteriorated. Finally, an analysis concerning the different limit cases of parameters of spin precession including the frame-dragging effects is carried out.; Comment: 25+1 pages, 7 eps figures. Major changes were made through all the manuscript. Clarifications regarding modifications were introduced through the draft. Figures were changed and reduced in number. arXiv admin note: text overlap with arXiv:quant-ph/0307114

Monochromatic aberrations and point-spread functions of the human eye across the visual field

Navarro, Rafael; Moreno Barriuso, Esther; Dorronsoro, Carlos
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Artículo Formato: 359424 bytes; application/pdf
ENG
Relevância na Pesquisa
15.86%
8 pages, 6 figures.-- OCIS codes: 330.5370, 330.0330.-- PMID: 9729864 [PubMed].; The monochromatic aberrations of the human eye along the temporal meridian are studied by a novel laser ray-tracing method. It consists of delivering a narrow laser pencil into the eye through a given point on the pupil and recording the aerial image of the retinal spot with a CCD camera. The relative displacement of this image is proportional to the geometrical aberration of the ray (laser pencil) at the retina. We scanned the pupils of four observers in steps of 1 mm (effective diameter, 6.7 mm) and for five field angles (0°, 5°, 10°, 20°, and 40°). In addition, the aerial image for each chief ray is a low-pass-filtered version of the retinal pointspread function corresponding to a fully dilated pupil. The resulting spot diagrams, displaying the distribution of ray aberrations, are highly correlated with these point-spread functions. We have estimated the wavefront error by fitting Zernike polynomials (up to the fifth order). Despite the large variation found among observers, the overall rms wave-front error is relatively homogeneous. At the fovea, the average rms value was 1.49 mm when the second-order terms (defocus and astigmatism) were considered; this was reduced to 0.45 mm when the second-order terms were ignored. The rms values increase slowly...

A Comparison study of input scanning resolution requirements for AM and FM screening

Elsman, Kenneth
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
16.01%
The advent of computers and their impact on the graphic arts and printing industry has, and will continue to, change the methodology of working and workflow in prepress operations. The conversion of analog materials (prints, artwork, transparencies, studio work) into a digital format requires the use of scanners or digital cameras, coupled with the knowledge of output requirements as related to client expectations. The chosen input sampling ratio (sampling rate in relation to halftone screening) impacts output quality, as well as many aspects of prepress workflow efficiency. The ability to predict printed results begins with the correct conversion of originals into digital information and then an appropriate conversion into the output materials for the intended press condition. This conversion of originals into digital information can be broken down into four general components. First, the image must be scanned to the size of the final output. Second, the input sampling ratio must be determined, in relation to the screening requirements of the job. This ratio should be appropriate to the needs of the printing condition for the final press sheet. Third, the highlight, highlight to midtone and shadow placement points must be determined in order to achieve the correct tone reproduction. Fourth...

Nonlinear H-∞ Control: Practicality of Implementing the Cheap Sensor Case

Helton, J W; James, Matthew; McEneaney, W M
Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc) Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)
Tipo: Conference paper
Relevância na Pesquisa
35.65%
In [5] we introduced a recipe for nonlinear H∞ controllers which takes advantage of extra perfect measurements and stated a theorem to the effect that this controller yielded the best possible "H∞" performance. Pure state feedback is an extreme situat

Experimental Synchronization by Means of Observers

Martínez-Guerra,R.; Pérez-Pinacho,C. A.; Gómez-Cortés,G. C.; Cruz-Victoria,J. C.; Mata-Machuca,J. L.
Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
Relevância na Pesquisa
55.77%
In this paper we deal with the experimental synchronization of the Colpitts oscillator in a real-time implementation. Our approach is based on observer design theory in a master-slave configuration thus, a chaos synchronization problem can be posed as an observer design procedure, where the coupling signal is viewed as a measurable output and a slave system is regarded as an observer. A polynomial observer is used for synchronizing the Colpitts oscillator employing linear matrix inequalities. Finally, a comparison with a reduced order observer and a high gain observer is given to assess the performance of the proposed observer.