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Ulanovska, Anastazja. "Ekonominio modelio tyrimas su Dynare ir Winbug programomis." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2011~D_20140627_171859-84042.
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Šiame darbe buvo nagrinėjamas dinaminis stochastinis stacionarus modelis aprašytas I.Carabenciov, I.Ermolaev, Ch.Freedman, M.Juillard, O.Kamenik, D.Korshunov, D.Laxton „A Small Quarterly Projection Model of the US Economy“ straipsnyje. Duomenis pateikė „Euromonitor International“ įmonė. Modelyje naudojami keturi Jungtinių Valstijų ekonomikos rodikliai: realus bendras vidaus produktas, nedarbo lygis, infliacija ir federalinių fondų palūkanų norma. Rodikliai stebimi 1994 m. І ketv. – 2009 m. ІІ ketv. laikotarpiu. Darbo tikslas – pakartoti „A Small Quarterly Projection Model of the US Economy“ straipsnio rezultatus. Buvo pasirinkti du programavimo paketai – Dynare ir Winbugs. Modelis buvo suprogramuotas dvejomis skirtingomis programomis, kurios remiasi Bajeso metodologija. Po to, gauti rezultatai buvo lyginami su straipsnyje pateiktais rezultatais. Atlikus visus skaičiavimus buvo gauti tokie rezultatai: su Dynare puikiai pavyko pakartoti modelio rezultatus. Su Winbugs programa gauti rezultatai nepilnai sutapo su straipsnyje pateiktais rezultatais. Iš to galima buvo padaryti išvada, kad Dynare programa labiau tinka dinaminių stochastinių stacionarių modelių vertinimui. Šio darbo rezultatai bus labai naudingi tyrimo planuotojams bei vykdytojams. Modelio rezultatai bus įtraukti į globalųjų modelį, kuris apjungs dar kelių valstybių modelius.In the research paper a dynamic stochastic general equilibrium described in I.Carabenciov, I.Ermolaev, Ch.Freedman, M.Juillard, O.Kamenik, D.Korshunov, D.Laxton article „A Small Quarterly Projection Model of the US Economy“ was analyzed. The data for analysis was provided by “Euromonitor International“ company. The benchmark model has only four variables: real gross domestic product (GDP), unemployment rate, consumer price index, federal funds rate. The model is estimated over sample period from 1994QI till 2009QII. The aim of the research was to reiterate the results given in the article „A Small Quarterly Projection Model of the US Economy“. For this aim two programming packages were chosen – Dynare and Winbugs. The model was programmed using two different programs, both based on Bayesian methodology. Afterward the results were compared with results presented in the article. After all the calculations were done, the results were following: model was successfully repeated with Dynare. Although the results obtained with Winbugs program differed from the results given in the article. It therefore concluded that Dynare program is more suitable for the assessment of stationary stochastic dynamic models.
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Greco, T. "NETWORK META-ANALYSIS: A NOVEL APPROACH BASED ON A HIERARCHICAL DATA STRUCTURE." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/344198.
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INTRODUCTION
Meta-analysis is a powerful tool to cumulate and summarize the knowledge in a research field through statistical instruments, and to identify the overall measure of a treatment’s effect by combining several study-specific results. However, it is a controversial tool, because even small violations of certain rules can lead to misleading conclusions. Pooling data through meta-analysis can create problems, such as non linear correlations, multifactorial rather than unifactorial effects, limited coverage, or inhomogeneous data that fails to connect with the hypothesis. When head-to-head treatment comparisons are not available or conclusive, the limitations of standard (i.e. pairwise) meta-analyses can be overcome by network meta-analyses (NMA) which can provide estimates of treatment efficacy or safety of multiple treatment regimens. Different treatment strategies are analyzed by statistical inference methods rather than simply summing up trials that evaluated the same intervention compared to another intervention, standard care, or placebo. If a first trial compares drug A to drug B, showing that drug A is significantly superior to drug B, and a second trial investigates the same or a similar patient population comparing drug B versus drug C (demonstrating that drug B is equivalent to drug C), NMA may allow to infer that drug A is also potentially superior to drug C for this given patient population, even though there was no direct test of drug A against drug C.
CONTENTS
In this thesis we provided and discussed methods to overcome the limits of standard (univariate) meta-analysis, focusing on the ability to cope with multiple treatments and to deal with correlated data where correlation can derive from multiple endpoints, time-varying responses or from clustered observation.
In the first chapter we explore the principal steps (from writing a prospective protocol of analysis to results’ interpretation) in order to minimize the risk of conducting a mediocre meta-analysis and to support researchers to accurately evaluate the published findings.
The second chapter represents an overview of conceptual and practical issues of a network meta-analysis. We start from general considerations on network meta-analysis to specifically appraise how to collect study data, structure the analytical network, and specify the requirements for different models and parameter interpretations. Specifically, we outline the key steps, from literature search to sensitivity analysis, necessary to perform a valid network meta-analysis on binomial data.
In the third party of this work, we focus our attention on data which can be analyzed with a binomial model applying the Bayesian hierarchical approach and using Markov Chain Monte Carlo approach. We also apply this analytical approach to a case study on the beneficial effects of anesthetic agents in order to further clarify the statistical details of the models, diagnostics, and computations. We presented a practical guide with the actual WinBUGS and SAS codes to allow transparency and ease of replication of all steps that are required when carrying out such quantitative syntheses.
In the fourth chapter we propose an alternative frequentist approach to estimate consistency and inconsistency models for a network meta-analysis. We discuss the multilevel network meta-analysis which include a three-level data structure: subjects within studies at the first level, studies within study designs at the second level and design configuration at the third level. We discuss multilevel modeling which may be carried out within widely available statistical programs such as SAS software, and we compare the results of a published Bayesian network meta-analysis on a binary endpoint which examines the effect on mortality of desflurane, isoflurane, sevoflurane, and total intravenous anaesthetics at the longest follow-up available.
In the final chapter we compare the Bayesian and the novel frequentist-multilevel approach in performing network meta-analysis on publicly available data and we investigate the descriptive characteristics that may contribute to decrease or increase the potential difference between the estimates derived from the two approaches. The two approaches were compared in terms of the difference between the pooled estimates or their standardized values, and of the Euclidean distance.
BAYESIAN NETWORK META-ANALYSIS
Suppose that J trials provide mixed comparisons among K treatments and that a is the trial-specific reference treatment. The random effect model is defined by:
yja= β0+eja for j=1,2,...,J; a=1,2,…,K-1
yjk= β0j+δj,ak+ejk for j=1,2,...,J; a=2,3,…,K; b
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Ascencio, Flores Daniel R., and A. Juan Hernández. "Winkul Hacienda Lodge." Tesis, Universidad de Chile, 2016. http://repositorio.uchile.cl/handle/2250/143340.
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TESIS PARA OPTAR AL GRADO DE MAGÍSTER EN ADMINISTRACIÓN
Daniel Ascencio F. [Parte I], Juan Hernández A. [Parte II]El turismo es una de las industrias de más rápido crecimiento en el mundo y lo ha sido particularmente en Chile en los últimos años. Este Sector Industrial, además, es el principal promotor de la conservación del medio ambiente y del patrimonio cultural de las comunidades. La búsqueda por conocer nuevas latitudes, culturas, costumbre y el interés cada día más fuerte por acercarse a la vida natural, incentivan la inquietud de viajar. Los datos entregados por la Subsecretaría de Turismo y Sernatur en su informe de Turismo Receptivo Anual 2015 y respaldados por la Organización Mundial de Turismo (OMT), muestran que durante el 2015 las llegadas de turistas a nivel mundial se incrementaron en un 4%, mientras que América del Sur creció un 5,4%. En Chile se registró un significativo 21,9% de aumento en las visitas de extranjeros versus el año 2014, llegando a 4.478,3 (Miles) de turistas, muy por sobre la tasa de crecimiento media de un 7,4% entre 2008-2015. Los ingresos por turismo receptivo en nuestro país representan el 4%, registrándose MMUS$2.431,1 durante el año 2015 aumentando un 9,8% comparado con 2014. Las estimaciones futuras de la industria turística en Chile son muy auspiciosas, tomando en cuenta la visión del Ministerio de Economía de posicionar a Chile como un destino de clase mundial. La Subsecretaría de Turismo anunció la concreción de un aumento del fondo de promoción, el cual aumentará de US$13 millones el 2015 a US$21,5 el 20171 con el objetivo de lograr la visita de 5,4 millones de turistas al año 20202, desde los 4 millones de turistas registrados en 2014 y esperando un aumento de su gasto promedio en un 50%. Estos son los principales argumentos que motivan la creación de Winkul Hacienda Lodge, un centro turístico “All Inclusive” de alto estándar enclavado en la Pre cordillera de la Región de Los Lagos en el Sur de Chile, cercano al Volcán Osorno, entre los Lagos Rupanco y Llanquihue, dueño de una belleza natural que motiva a la aventura y/o al relajo según se quiera. Como antecedente previo, se puede mencionar que la generación de riqueza del Proyecto (VAN) en los primeros 6 años de funcionamiento es de M$286.182,33, con una Tasa Interna de Retorno del 21,15% real anual y la recuperación de la Inversión en 4,02 años.
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Lindsey, Heidi Lula. "An Introduction to Bayesian Methodology via WinBUGS and PROC MCMC." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2784.
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Bayesian statistical methods have long been computationally out of reach because the analysis often requires integration of high-dimensional functions. Recent advancements in computational tools to apply Markov Chain Monte Carlo (MCMC) methods are making Bayesian data analysis accessible for all statisticians. Two such computer tools are Win-BUGS and SASR 9.2's PROC MCMC. Bayesian methodology will be introduced through discussion of fourteen statistical examples with code and computer output to demonstrate the power of these computational tools in a wide variety of settings.
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Teo, Chun Sang Justin. "Gradient projection anti-windup scheme." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/63043.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 205-217).
It is a well-recognized fact that control saturation affects virtually all practical control systems. It leads to controller windup, which degrades/limits the system's closed-loop performance, and may cause catastrophic failures if it induces instability. Anti-windup compensation is one of two main approaches to mitigate the effects of windup, and is conceptually and practically attractive. For the idealized case of constrained linear time invariant (LTI) plants driven by LTI controllers, numerous anti-windup schemes exist. However, most practical control systems are inherently nonlinear, and anti-windup compensation for nonlinear systems remains largely an open problem. To this end, we propose the gradient projection anti-windup (GPAW) scheme, which is an extension of the conditional integration method to multi-input-multi-output (MIMO) nonlinear systems, using Rosen's gradient projection method for nonlinear programming. It achieves controller state-output consistency by projecting the controller state onto the unsaturated region induced by the control saturation constraints. The GPAW-compensated controller is a hybrid controller defined by the online solution to either a combinatorial optimization subproblem, a convex quadratic program, or a projection onto a convex polyhedral cone problem. We show that the GPAW-compensated system is obtained by modifying the uncompensated system with a passive operator. Qualitative weaknesses of some existing anti-windup results are established, which motivated a new paradigm to address the anti-windup problem. It is shown that for a constrained first order LTI plant driven by a first order LTI controller, GPAW compensation can only maintain/enlarge its region of attraction (ROA). In this new paradigm, we derived some ROA comparison and stability results for MIMO nonlinear as well as MIMO LTI systems. The thesis is not that the GPAW scheme solves a centuries-old open problem of immense practical importance, but rather, that it provides a potential path to a solution. We invite the reader to join us in this quest at the confluence of nonlinear systems, hybrid systems, projected dynamical systems, differential equations with discontinuous right-hand sides, combinatorial optimization, convex analysis and optimization, and passive systems.
by Chun Sang Justin Teo.
Sc.D.
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Esmeral, Jorge Sofrony. "Anti-windup synthesis using Riccati equations." Thesis, University of Leicester, 2007. http://hdl.handle.net/2381/30250.
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This thesis studies the design and implementation of anti-windup compensators for systems with magnitude and rate-limited actuators; the thesis contains four main contributions. The first is the development of a new method for anti-windup compensator design, based on the solution of a single Riccati equation, for systems with magnitude saturated actuators. The second contribution shows how this new method can be adapted to systems with rate saturation. The third contribution describes the application of the anti-windup techniques developed to a complex experimental aircraft model in order to reduce the susceptibility to pilot-induced-oscillations. The thesis culminates with a description and analysis of the implementation of these anti-windup compensators on a real aircraft and the subsequent flight tests. The flight test results clearly illustrate the advantages of employing anti-windup compensation in terms of improved handling qualities and reduced susceptibility pilot-induced-oscillations.
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Alli-Oke, Razak Olusegun. "Robustness and optimization in anti-windup control." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/robustness-and-optimization-in-antiwindup-control(8b98c920-90c3-4fbc-95a8-0cc7ae2a607a).html.
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This thesis is broadly concerned with online-optimizing anti-windup control. These are control structures that implement some online-optimization routines to compensate for the windup effects in constrained control systems. The first part of this thesis examines a general framework for analyzing robust preservation in anti-windup control systems. This framework - the robust Kalman conjecture - is defined for the robust Lur’e problem. This part of the thesis verifies this conjecture for first-order plants perturbed by various norm-bounded unstructured uncertainties. Integral quadratic constraint theory is exploited to classify the appropriate stability multipliers required for verification in these cases. The remaining part of the thesis focusses on accelerated gradient methods. In particular, tight complexity-certificates can be obtained for the Nesterov gradient method, which makes it attractive for implementation of online-optimizing anti-windup control. This part of the thesis presents a proposed algorithm that extends the classical Nesterov gradient method by using available secant information. Numerical results demonstrating the efficiency of the proposed algorithm are analysed with the aid of performance profiles. As the objective function becomes more ill-conditioned, the proposed algorithm becomes significantly more efficient than the classical Nesterov gradient method. The improved performance bodes well for online-optimization anti-windup control since ill-conditioning is common place in constrained control systems. In addition, this thesis explores another subcategory of accelerated gradient methods known as Barzilai-Borwein gradient methods. Here, two algorithms that modify the Barzilai-Borwein gradient method are proposed. Global convergence of the proposed algorithms for all convex functions is established by using discrete Lyapunov theorems.
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Stenberg, Conny. "Regulatorer med styrsignalsbegränsning." Thesis, Linköping University, Department of Electrical Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1796.
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This thesis studies the negative impact that control signal saturation may have on a controlled system. Different methods that are used to compensate for this problem are also studied and evaluated. Both sensitivity to disturbances and the effect the method has on the systems'ability to follow a reference signal will be examined. Stability will be discussed, but no conclusions whether the systems are stabilized or not can be drawn.
Control signal saturation will lead to a slower behavior in general. For controllers with integral action this performance degradation will cause an extended growth in the integrating part of the controller. This leads to large overshoots and possibly to instability.
As an alternative to the more ad-hoc based methods, model based predictive control is studied. This metod can explicitly handle constrained control signals. Here, too, sensitivity to disturbances and the effect the method has on the systems'ability to follow a reference signal is examined.
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Cramond, Paige Marie 1983. "Space: Movement and Location in Wintu." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/11509.
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xii, 75 p.Wintu is a moribund Penutian language once spoken in the Sacramento River Valley in Northern California. Presently unexplored is Wintu expression of movement and location. Several avenues exist for nouns and verbs. Nouns receive optional locative suffixation, or location may be implied in the absence of a noun. Verbs may receive locative prefixes and/or an implied trajectory may be inherent to a verb's semantics; inherent location may also be expressed by nouns. In more complicated cases, nouns appear to receive established verbal morphology, or the nominal locative suffix or verbal locative prefixes occur in unusual contexts. In order to reach primary conclusions, it was necessary to address other difficulties, including nominal aspect, unclear word-class boundaries, inconsistent glossing, lack of native speakers and an overall paucity of information. Primary data consist of texts recorded and transcribed in the 1970s and two English/Wintu dictionaries; analysis was based on forms from these documents.
Committee in charge: Prof. Scott DeLancey, Chairperson; Prof. Spike Gildea, Member
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Izquierdo, David Orlando Diaz. "Análise experimental do efeito aerodinâmico de dispositivos de asa e ponta de asa em uma aeronave tipo \"Blended Wing Body\"." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18148/tde-26072016-104731/.
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Este trabalho tem por objetivo analisar o comportamento aerodinâmico de dispositivos de ponta de asa e Fences acoplados em uma aeronave Blended Wing Body (BWB) através de testes em túnel de vento. A BWB é um projeto de aeronave alternativo que faz parte do conceito de aeronaves sustentáveis. O Laboratório de Aeronaves da Escola de Engenharia de São Carlos, Universidade de São Paulo, vem realizando uma série de pesquisas sobre este assunto. Em trabalhos anteriores com o modelo BWB foram observados a presença tanto de um escoamento transversal na parte externa quanto um forte vórtice no meio do modelo. A fim de melhorar o primeiro protótipo o Droop, bem como um arranjo de três Fences foram adicionados no modelo BWB. Além disso, os dispositivos Winglets e C-wing foram considerados neste estudo. Entre o desenvolvimento de aeronaves, vários dispositivos têm sido estudados e implementados em aeronaves convencionais. Estes tem várias vantagens, tais como a melhoria da eficiência aerodinâmica e a redução do arrasto induzido e efeitos positivos no rendimento do avião. Os dispositivos de ponta da asa criam uma força aerodinâmica em que um do seus componentes atua na direção do voo, esta também pode contribuir para a redução da intensidade dos vórtices nas pontas da asa, reduzindo o arrasto induzido. Pesquisas em aeronaves não convencionais mostraram que BWB poderia ter melhores características aerodinâmicas do que uma aeronave convencional. Aindústriaaeronáuticaestáprocurandoareduçãodoscustosoperacionais,bemcomo a adaptação das aeronaves para a restrição legislativa das emissões de gases e poluição sonora. Nas últimas décadas, esta redução não teve uma melhora significativa em termos de valores absolutos para configurações convencionais, isso fez com que novas e mais eficientes configurações têm sido estudadas. A interferência dos diferentes dispositivos no modelo BWB foram analisados em teste em túnel de vento. Os experimentos foram realizados no Laboratório de Aeronaves da Escola de Engenharia de São Carlos, Universidade de São Paulo. Foi utilizado um túnel de vento fechado com uma seção de teste de 1.7x1.3x3 [m]. O ângulo de ataque foi variado desde -4º a 20º e Re = 390.000. Os resultados mostram que os dispositivos nas pontas da asa melhoraram o desempenho da aeronave, bem como a eficiência aerodinâmica. Com relação aos Fence este comportamento não foi observado. Entre tanto, em ângulos elevados a eficiência foi aumentada. Através da técnica de visualização oil flow observou-se que o escoamento sobre a asa foi redirecionado diminuindo o coeficiente de arrasto em ângulos de ataque elevados.This work aims to analyze the aerodynamic behavior of wingtip devices and Fences coupled on a Blended Wing Body aircraft (BWB) through wind tunnel tests. The BWB is an alternative of airship design which makes up part of the Green aircraft concept. The Aircraft Laboratory of the School of Engineering of São Carlos-University of São Paulo has been carrying out a lot of research into this subject. In previous works with a BWB model, the presence both of a cross flow on the external part and a stronger vortex in the middle of the model have been observed. In order to improve the first prototype a Droop as well as an arrangement of three Fences were added on the BWB model. Furthermore the Winglets, C-wing devices were considered in this study. Among the aircraft development, several devices have been studied and implemented in conventional aircraft. These ones had several advantages such as improving the aerodynamic efficiency and induced drag reduction and getting positive effects on aircraft performance. The wingtip devices create an aerodynamic force in which one of this components acts in the flight direction, also these can contribute to the reduction of the wingtip vortices strength, reducing the induced drag. Researches in non conventional aircraft has shown that BWB could have better aerodynamic characteristics than a conventional aircraft. The aeronautical industry is looking for the reduction of direct operational cost, as well as the adaptation of aircrafts to the demanding legislative restriction of gas emissions and noise pollution. In the last few decades this reductions has not had a significant improvement in terms of absolute values for conventional configurations, this has meant that new and more efficient configurations have been studied. The interference of the different devices on the BWB model were analyzed in wind tunnel test. The experiments were carried out in the Aircraft Laboratory of the School of Engineering of São Carlos-University of São Paulo. A closed wind tunel with a section work of 1.7x1.3x3 [m] was used. The angle of attack was varied from -4º to 20º and Re = 390.000. The results shows that the wing tip devices improved the aircraft performance as well as the aerodynamic efficiency. Regarding the Fences this behavior was not observed. However, at higher angles the efficiency was increased. Through oil flow visualization it was observed that the flow over the wing was redirected decreasing the drag coeficient at higher attack angles.
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Svensson, Henrik. "MEPS och WinBygg 2000 : En studie av kalkyleringsprogram vid skadereglering." Thesis, Jönköping University, JTH, Civil Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-10729.
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Uppdragsgivaren, Erik Larssons Byggnads AB, utför skadereglering på uppdrag av flera olika försäkringsbolag i Tranemo, Svenljunga och Ulricehamn kommun. Året 2008 var företaget involverat i sammanlagt 104 försäkringsskador.
Den ersättning som tillfaller Erik Larssons Byggnads AB grundar sig i det närmaste uteslutande på de kostnader kalkyleringsprogrammen MEPS och WinBygg 2000 beräknat.
Examensarbetet är en studie om användandet av de olika kalkylprogrammen i kombination med respektive avtal haft betydelse för lönsamheten vid skadereglering. Skillnader mellan programmens kalkyler samt hur dessa överensstämmer med verkligt utfall undersöks. Brister i nuvarande arbetssätt kartläggs och förbättringar föreslås.
Målet är att resultat och slutsatser skall kunna vara en hjälp vid framtida kalkylering och upphandling av skadeuppdrag - att lönsamheten på så sätt kan förbättras för Erik Larssons Byggnads AB.
En fullständig inventering av företagets skadekalkyler genomfördes. Vid denna delades skador från varje försäkringsbolag in i skadetyp, omfattning och kostnad. Som utgångspunkt valdes därefter tre slutkalkyler i MEPS. Dessa kopierades i WinBygg 2000, så identiska förlagan i MEPS som möjligt. Alla kalkyler jämfördes sedan med verkligt utfall.
Examensarbetet visar att den ersättning som tillföll Erik Larssons Byggnads AB i stor utsträckning påverkades av åt vilket försäkringsbolag skaderegleringen utfördes. WinBygg 2000 kalkylerade genomgående lägre skadekostnader i jämförelse med MEPS. Störst skillnad var det mellan UE-arvode och transportkostnader.
Vid skadeinventeringen upptäcktes även att två för entreprenören gynnsamma möjligheter sällan eller aldrig utnyttjades år 2008.
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Ofodile, Nkemdilim Anulika. "Decentralized anti-windup compensator designs for small unmanned aerial vehicles." Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/39848.
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This thesis studies the design and implementation of anti windup compensators for UAVs with magnitude and rate saturated actuators. The focus is on two types of UAVs; a Quadrotor UAV and a Fixed wing UAV. Decentralized anti-windup compensators are designed to address the problem of magnitude saturation in Quadrotor UAVs. The developed anti-windup compensators are founded on an LMI-based approach previously used in literature to provide global stabilty guarantees with some level of performance guarantees. The work on the decentralized anti-windup compensators for Quadrotor UAVs are further improved on by replacing the use of LMIs in the determination of the anti windup compensator parameters with approximate linear based guidelines after a Lure-Postinikov Lyapunov function is used to provide global stability guarantees. This approach applies not only to Quadrotor UAVs but also to a wide class of systems that contain double integrators. The developed anti-windup compensators were designed and implemented for an experimental Quadrotor UAV where both simulation results and flight test results clearly show the ability of the anti-windup compensators to reduce the effect of magnitude saturation in Quadrotor UAVs. Finally, the thesis describes the design of decoupled multivariable anti-windup compensators to tackle the problem of rate saturation on a fixed wing UAVs. Simulation results obtained demonstrate that these anti-windup compensators are capable of managing the system responses during periods of rate saturation.
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Cattarius, Jens. "Numerical Wing/Store Interaction Analysis of a Parametric F16 Wing." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/29122.
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A new numerical methodology to examine fluid-structure interaction of a wing/pylon/store system has been developed. The aeroelastic equation of motion of the complete system is solved iteratively in the time domain using a two-entity numerical code comprised of ABAQUS/Standard and the Unsteady-Vortex-Lattice Method. Both codes communicate through an iterative handshake procedure during which displacements and air loads are updated. For each increment in time the force/displacement equilibrium is found in this manner.
The wing, pylon, and store data considered in this analysis are based on an F16 configuration that was identified to induce flutter in flight at subsonic speeds. The wing structure is modeled as an elastic plate and pylon and store are rigid bodies. The store body is connected to the pylon through an elastic joint exercising pitch and yaw degrees of freedom. Vortex-Lattice theory featuring closed ring-vortices and continuous vortex shedding to form the wakes is employed to model the aerodynamics of wing, store, and pylon.
The methodology was validated against published data demonstrating excellent agreement with documented key phenomena of fluid-structure iteration. The model correctly predicts the effects of the pylon induced lateral flow disruption as well as wing-tip-vortex effects. It can identify the presence of aerodynamic interference between the store, pylon, and wing wakes and examine its significance with respect to the pressure and lift forces on the participating bodies. An elementary flutter study was undertaken to examine the dynamic characteristics of a stiff production pylon at near-critical airspeeds versus those of a soft-in-pitch pylon. The simulation reproduced the stabilizing effect of the stiffness reduction in the pitch motion. This idea is based on the concept of the decoupler pylon, introduced by Reed and Foughner in 1978 and flight tested in the early 1980's.
NOTE: (3/07) An updated copy of this ETD was added after there were patron reports of problems with the file.Ph. D.
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Potts, Jonathan Roger. "Disc-wing aerodynamics." Thesis, University of Manchester, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569224.
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Disc-wings are a class of un-powered, axi-symmetric flight vehicles that use spin to achieve acceptably stable flight characteristics. Examples of commonly encountered disc-wings include the Frisbee sports disc, the athletics discus and the clay pigeon. Historically, it appears that most disc-wing designs have been based on trial and error approaches. The main aim of the present work is to develop a theory of flight for spinstabilised disc-wings that can be used to inform the process of their design. This theory of flight is based both on theoretical analysis and experimental data. It is shown from a simple trim and stability analysis that a disc-wing with positive camber will trim at a positive angle of attack. However, for most axi-symmetric crosssectional shapes, the aerodynamic centre is ahead of the centre of the disc (which by definition is the disc centre of gravity). Hence, the static margin is negative and the disc is unstable in pitch. In practice, a disc-wing must be spun in order to fly successfully. The imparted angular momentum due to the spin means that, through precessional effects, the destabilising pitching moments tend to result in a rolling motion rather than a pitching motion. Thus, without spin, a disc-wing would tumble soon after release. With spin however, the discwing will not tumble, instead it tends to exhibit a relatively benign roll to the left or right, depending on the spin direction. The aerodynamic characteristics of various disc-wing geometries based around a Frisbee sports disc are investigated through a series of wind tunnel experiments on a spinning and non-spinning disc. It is shown that the basic lift and drag characteristics are consistent with those expected for a finite wing of the same aspect ratio. The pitching moment characteristic is key to understanding the resulting disc dynamics. A comparison of pitching moment curves is given, for a number of different cross-sectional profiles, some tested as part of the present work and some taken from data found in the literature. It is shown that the Frisbee cross-section is unique in that the pitching moment is zero at around 9° angle of attack, approximately coincident with the angle attack for best lift to drag ratio, and that the disc is approximately neutrally stable in this region. It is these characteristics that enable a typical Frisbee to fly successfully. Spin has almost negligible effect on aerodynamic forces and moments. Force and moment data is supported by surface pressure data, and by on and off surface flow visualisation. Surface pressure data shows that the aerodynamic centre of the Frisbee cross-section is shifted aft by the presence of an aft pressure peak that is not present on other cross-section shapes. The aft pressure peak is a function of both the upper surface geometry and the presence of the cavity on the under surface of the disc. Flow visualisation and pressure data are used to propose a model of disc-wing flow topology that is dependant on the angle of attack and includes leading edge separation and reattachment, recirculating cavity flow and a pair of trailing vortices. To understand further disc-wing flight dynamics and the effect of aerodynamic characteristics, a six-degree of freedom disc-wing simulation model was developed using Matlab. The simulation is validated against published Frisbee trajectory data obtained from free-flight experiments. Flight profiles are also discussed for a number of different launch conditions consistent with a range of typical Frisbee throws. The simulation is also used to demonstrate that with control moments from suitable control effectors, it is possible to generate a number of proscribed manoeuvres, including a spiral turn and a spiral roll.
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Huang, Haidong. "Optimal design of a flying-wing aircraft inner wing structure configuration." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7439.
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Flying-wing aircraft are considered to have great advantages and potentials in
aerodynamic performance and weight saving. However, they also have many
challenges in design. One of the biggest challenges is the structural design of
the inner wing (fuselage). Unlike the conventional fuselage of a tube
configuration, the flying-wing aircraft inner wing cross section is limited to a
noncircular shape, which is not structurally efficient to resist the internal
pressure load. In order to solve this problem, a number of configurations have
been proposed by other designers such as Multi Bubble Fuselage (MBF),
Vaulted Ribbed Shell (VLRS), Flat Ribbed Shell (FRS), Vaulted Shell
Honeycomb Core (VLHC), Flat Sandwich Shell Honeycomb Core (FLHC), Y
Braced Box Fuselage and the modified fuselage designed with Y brace
replaced by vaulted shell configurations. However all these configurations still
inevitably have structural weight penalty compared with optimal tube fuselage
layout. This current study intends to focus on finding an optimal configuration
with minimum structural weight penalty for a flying-wing concept in a preliminary
design stage.
A new possible inner wing configuration, in terms of aerodynamic shape and
structural layout, was proposed by the author, and it might be referred as
‘Wave-Section Configuration’. The methodologies of how to obtain a structurally
efficient curvature of the shape, as well as how to conduct the initial sizing were
incorporated.
A theoretical analysis of load transmission indicated that the Wave-Section
Configuration is feasible, and this was further proved as being practical by FE
analysis. Moreover, initial FE analysis and comparison of the Wave-Section
Configuration with two other typical configurations, Multi Bubble Fuselage and
Conventional Wing, suggested that the Wave-Section Configuration is an
optimal design in terms of weight saving. However, due to limitations of the
author’s research area, influences on aerodynamic performances have not yet
been taken into account.
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Kirkham, Ruth S. "Wing pattern determination and wing colour development in Heliconius melpomene (lepidoptera)." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236498.
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NARAYANAN, VIJAY. "STRUCTURAL ANALYSIS OF REINFORCED SHELL WING MODEL FOR JOINED-WING CONFIGURATION." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1116214221.
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Viviescas, Rafael Mauricio Morales. "The robustness of constrained cross-directional control and anti-windup systems." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489013.
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Soares, Claudio Eduardo. "Controladores baseados no princípio do modelo interno com ação Anti-Windup." Universidade do Estado de Santa Catarina, 2011. http://tede.udesc.br/handle/handle/1908.
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Previous issue date: 2011-04-28Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The controllers based on the internal model principle have found emphasis on control systems due to its ability to perform robust tracking of signals whose generator models are embedded in their internal structures. Controllers with integral, resonant and repetitive terms are examples of this principle. However, the control systems are subject to physical limitations that restrict their operation under certain conditions. The amplitude saturation of the control action is the most common type of restriction found in real systems. The impacts of the saturation of control action are known as windup and its consequences for systems with integral action have already been exhaustive examined. However, the impacts of saturation of control action are not restricted to this type of controller. Other controllers based on the internal model principle are also affected by the windup phenomenon due to saturation of the action control. The impacts of the windup phenomenon for resonant, multi-resonant and repetitive controllers are investigated in this dissertation and an anti-windup technique is suggested to mitigate the impacts of the control saturation on these controllers. The proposed anti-windup technique is based on the conditional integration technique, originally developed for the controllers with integral action, and it is named conditional update. Simulation results are presented to validate the proposed technique.
Os controladores baseados no princípio do modelo interno têm encontrado destaque no controle de sistemas devido a sua capacidade de realizar o rastreamento robusto dos sinais cujos modelos geradores estejam embutidos nas suas estruturas internas. Os controladores com ação integral, ressonantes e repetitivos são exemplos da aplicação deste princípio. Contudo, os sistemas de controle estão sujeitos a limitações físicas que restringem suas condições de operação. A saturação da amplitude da ação de controle é o tipo de limitação mais comum encontrada nos sistemas reais. Os impactos da saturação da ação de controle são conhecidos como windup e suas consequências para os sistemas com ação integral já foram exaustivamente analisadas. Porém, os impactos da saturação da ação de controle não se restringem a este tipo de controlador. Outros controladores baseados no princípio do modelo interno também são afetados pelo fenômeno windup decorrente da saturação da ação de controle. Os impactos do fenômeno windup sobre os controladores ressonantes, multiressonantes e repetitivos são investigados nesta dissertação e uma técnica anti-windup é sugerida para atenuar os impactos da saturação da ação de controle sobre estes controladores. A técnica anti-windup proposta é baseada na técnica da integração condicional, originalmente desenvolvida para os controladores com ação integral e, por isso, denominada de atualização condicional. Resultados de simulação são apresentados para validação da técnica proposta.
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Spera, Shelley M. "Metal and Pesticide Preservation in the Winous Point Marshes, Sandusky, Ohio." University of Toledo / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1092324052.
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Hadade, Neto Antonio. "Técnicas anti-windup em estruturas de controle PID, RST e GPC." Florianópolis, SC, 2005. http://repositorio.ufsc.br/handle/123456789/102669.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.Made available in DSpace on 2013-07-16T01:35:46Z (GMT). No. of bitstreams: 1 223414.pdf: 3157424 bytes, checksum: 9aa3342abef55c59abdda0259106f8e7 (MD5)
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Bombieri, Eduardo. "Alternative LMI formulations applied to a dynamic anti-windup synthesis method." reponame:Repositório Institucional da UFSC, 2014. https://repositorio.ufsc.br/xmlui/handle/123456789/129617.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Automação e Sistemas, Florianópolis, 2014.Made available in DSpace on 2015-02-05T21:18:17Z (GMT). No. of bitstreams: 1 329960.pdf: 1016550 bytes, checksum: 247c4dee44c73c24ff2947f7c9e4d4aa (MD5) Previous issue date: 2014
Abstract : The synthesis of modern anti-windup controllers for saturated systemsis a very important problem specially when high performance and guaranteeof stability are required. For such objectives it is not possible toavoid the system saturated behavior and special techniques must beused for analysis and synthesis of controllers for linear systems subjectto control saturation.In this work the existing results on analysis and synthesis of a classof anti-windup compensators based on the formulation of LMI (LinearMatrix Inequalities) problems for minimization of a L2 energy criteriaor enlargement of the domain of asymptotic stability are studied. TheseLMI problems use Lyapunov stability conditions as well as a representationof the saturation through modified sector conditions. Additionally,conditions for pole placement on the anti-windup controller are used.Then, considering the Projection Lemma, an alternative LMI formulationis proposed for the considered problem. This formulation is shownto be a generalization of existing methods and the results of both formulationsare compared using a numerical example.Finally the advantages and disadvantages of the proposed LMI formulationare highlighted. The additional degree of freedom in the LMIproblem is probably the main contribution for future research since theresulting flexibility can be exploited to include additional objectives tothe synthesis problem.
A síntese de controladores para sistemas com saturação é um problema especialmente importante quando há requisitos de alto desempenho e garantias formais de estabilidade. Em face de tais objetivos rigorosos não é possível evitar o comportamento saturado do sistema e técnicas especiais precisam ser empregadas na análise e síntese de controladores para estes sistemas não-lineares. Neste trabalho de mestrado é estudado uma técnica existente para a análise e síntese de uma classe de compensadores anti-windup modernos baseados na formulação de problemas LMI (Desigualdades Matriciais Lineares, em inglês). Esta técnica pode considerar a minimização de um critério de energia L-2 ou a maximização de um domínio de estabilidade assintótica. Em ambos os casos o problema LMI formulado utiliza um critério de estabilidade baseado em Lyapunov bem como condições de setor modificadas para a representação das saturações. Adicionalmente, são utilizadas condições para a obtenção de controladores anti-windup com restrições de posicionamento dos polos do controlador. Então, utilizando o Lema da Projeção, uma formulação alternativa para o problema LMI considerado é proposta. Esta formulação é uma generalização dos métodos existentes e os resultados de ambas formulações são comparados usando um exemplo numérico. Por fim, as vantagens e desvantagens dessa formulação alternativa para o problema LMI são destacadas. O fato de que esta nova formulação fornece um grau de liberdade adicional ao problema LMI é provavelmente a principal contribuição para trabalhos futuros, visto que esta flexibilidade pode permitir a inclusão de objetivos adicionais ao problema de síntese do controlador anti-windup.
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Ma, Xinyuan. "Research on dynamic correlation based on stochastic time-varying beta and stochastic volatility." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/120023/1/Xinyuan_Ma_Thesis.pdf.
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This research used monthly returns of Chinese industry sectors that capture China economic status to investigate the relationship between the return of individual industry indices and a market portfolio. To understand characteristics of the relationships and their response to the presence of market fluctuation, this study examined both the impact from good and bad news. Factors like market value and market capitalization were incorporated to capture investors' expectation towards individual industries. These factors are essential as they classify industries into popular ones that take dominant position and unpopular ones that take less dominant position of China's stock market.
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Elliott, Michael Stephen. "An investigation into the wing rock of an 80 degree delta wing." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341947.
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Trussa, Colin Weidner. "Low-Speed Aerodynamic Characteristics of a Delta Wing with Deflected Wing Tips." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586450691890636.
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Naccarato, Vincent, Joong Yang Lee, Meng Hsi Wu, Ittai Bar Ilan, James Efird, Benjamin Elzner, Darrell Morgan, et al. "The distributed air wing." Thesis, Monterey California. Naval Postgraduate School, 2014. http://hdl.handle.net/10945/42717.
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Approved for public release; distribution is unlimitedThe development of advanced anti-access/area denial (A2AD) threats by potential adversaries presents a significant challenge to the United States Navy. The proliferation of these threats makes operating an aircraft carrier from contested waters a high-risk endeavor. If a carrier must be withheld from the battle or is put out of action, the entire capability of the air wing is lost. The Systems Engineering process was applied to this problem by exploring a concept called the Distributed Air Wing (DAW). This high-level concept includes various methods to distribute and disperse naval air capabilities from their centralized location on an aircraft carrier. This study outlines the development and analysis of three conceptual designs that fall under the concept of the DAW: a dispersed land and sea basing concept that utilizes carrier-borne Navy and Marine Corps aircraft, a seaborne unmanned aircraft courier system, and a carrier-based unmanned air-to-air vehicle. The analysis within shows that a mixture of these alternatives in varying degrees delivers the Fleet’s most critical capabilities— Intelligence, Surveillance and Reconnaissance (ISR), Offensive/Defensive Counter Air, and Surface/Land Strike— with less risk than the current Carrier Air Wing (CVW) force structure and operational doctrine.
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Scanlan, Michelle. "A Wing to Fly." ScholarWorks@UNO, 2007. http://scholarworks.uno.edu/td/526.
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Spiering, David E. "Crowns and Wing Nuts." Bowling Green State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1272044928.
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Chabada, Martin. "Návrh křídla letounu UAV v kategorii do 600 kg." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442849.
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The main aim of the this diploma thesis is the wing design of the UAV aircraft, including the appropriate material choice, calculation of the wing load and also strength analysis. Other goals include the design of the location and volume of fuel tanks, as well as the design of wingspan reduction after landing.
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Ortseifen, Andreas [Verfasser]. "Entwurf von modellbasierten Anti-Windup-Methoden für Systeme mit Stellbegrenzungen / Andreas Ortseifen." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2013. http://d-nb.info/1108094414/34.
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Johansson, Alexander. "Distributed PI Control in Multi-Agent Systems: From Anti-Windup to Topology." Thesis, KTH, Reglerteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-206433.
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In this thesis, we study the impact of input saturation on multiagentsystems, which are controlled by the recently developed DAPI (DistributedAveraging Proportional Integral) control scheme. We are alsostudying modern anti-windup synthesis for these systems. Specically,we are constructing anti-windup compensators through a method thatminimizes an upper bound of the L2-gain globally for asymptotically stablecontrol systems. Both static and dynamic anti-windup compensatorsare constructed. Numerical examples of a water tank and a microgrid areconsidered. It is veried in simulations that the constructed compensatorssuccessfully prevent windup caused by actuator saturation, and that thedynamic compensator has better performance. The performance of thesecompensators are also compared with the classical anti-windup method,called back calculation.During our study of anti-windup compensators, we found a partiallyrelated problem, which is also included in the thesis. The problem is toarrange the edge weights in a multi-agent system such that the L2-gainis minimized. This problem does not include input saturation but theconnection is the minimization of an upper bound of the L2-gain and themulti-agent systems. For the considered class of multi-agent systems, weestablish a connection between the algebraic connectivity and an upperbound of the L2-gain.Denna uppsats är en studie om hur insignalsmättnad påverkar multiagentsystem som är reglerade med den nyutvecklade DAPI (DistributedAveraging Proportional Integral) regulatorn. Vi studerar också modernametoder för att dämpa effekten av insignalsmättnad. Mer specifikt,så konstruerar vi anti-uppvridningskompensatorer genom en metod somminimerar en övre gräns för L2-förstärkningen globalt för asymptotisktstabila reglersystem. Både statiska och dynamiska anti- uppvridningskompensatorerkonstrueras. Vi undersöker två numeriska exempel: det ena ärett vattentankexempel och det andra ett elektriskt mikronät. Vi verifierargenom simulationer att de konstruerade kompensatorerna framgångsriktdämpar effekten av insignalsmättnad och att den dynamiska kompensatornpresterar bättre. Prestandan är också jämförd med en klassiskanti-uppvridningskompensator.Under vår studie av anti-uppvridningskompensatorer så hittade vi ettintressant ödesnätverksproblem som också är inkluderat i uppsatsen.Detta problem inkluderar inte insignalsmättnad men kopplingen till restenav uppsatsen är minimering av en övre gräns av L2-förstärkningen ochmulti-agent system. För den studerade klassen av ödesnätverk härledervi en koppling mellan den algebraiska konnektiviteten hos ödesnätverketoch en övre gräns på L2-förstärkningen. Denna övre gräns är verifierad isimulationer.
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Raley, Jack. "Efficient DC-DC switch regulator applied iterative learning and anti-windup control /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p1457288.
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Thesis (M.S.)--University of California, San Diego, 2008.Title from first page of PDF file (viewed November 14, 2008). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 65-66).
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Kadel, Rajendra. "A Latent Mixture Approach to Modeling Zero-Inflated Bivariate Ordinal Data." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4701.
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Multivariate ordinal response data, such as severity of pain, degree of disability, and satisfaction with a healthcare provider, are prevalent in many areas of research including public health, biomedical, and social science research. Ignoring the multivariate features of the response variables, that is, by not taking the correlation between the errors across models into account, may lead to substantially biased estimates and inference. In addition, such multivariate ordinal outcomes frequently exhibit a high percentage of zeros (zero inflation) at the lower end of the ordinal scales, as compared to what is expected under a multivariate ordinal distribution. Thus, zero inflation coupled with the multivariate structure make it difficult to analyze such data and properly interpret the results. Methods that have been developed to address the zero-inflated data are limited to univariate-logit or univariate-probit model, and extension to bivariate (or multivariate) probit models has been very limited to date.
In this research, a latent variable approach was used to develop a Mixture Bivariate Zero-Inflated Ordered Probit (MBZIOP) model. A Bayesian MCMC technique was used for parameter estimation. A simulation study was then conducted to compare the performances of the estimators of the proposed model with two existing models. The simulation study suggested that for data with at least a moderate proportion of zeros in bivariate responses, the proposed model performed better than the comparison models both in terms of lower bias and greater accuracy (RMSE). Finally, the proposed method was illustrated with a publicly-available drug-abuse dataset to identify highly probable predictors of: (i) being a user/nonuser of marijuana, cocaine, or both; and (ii), conditional on user status, the level of consumption of these drugs. The results from the analysis suggested that older individuals, smokers, and people with a prior criminal background have a higher risk of being a marijuana only user, or being the user of both drugs. However, cocaine only users were predicted on the basis of being younger and having been engaged in the criminal-justice system. Given that an individual is a user of marijuana only, or user of both drugs, age appears to have an inverse effect on the latent level of consumption of marijuana as well as cocaine. Similarly, given that a respondent is a user of cocaine only, all covariates--age, involvement in criminal activities, and being of black race--are strong predictors of the level of cocaine consumption. The finding of older age being associated with higher drug consumption may represent a survival bias whereby previous younger users with high consumption may have been at elevated risk of premature mortality. Finally, the analysis indicated that blacks are likely to use less marijuana, but have a higher latent level of cocaine given that they are user of both drugs.
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Bazan, Guzman Jorge Luis, and Oscar Millones. "Una clasificación de modelos de regresión binaria asimétrica: el uso del BAYES-PUCP en una aplicación sobre la decisión del cultivo ilícito de hoja de coca." Economía, 2012. http://repositorio.pucp.edu.pe/index/handle/123456789/118039.
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En modelos econométricos clásicos de regresión binaria tradicionalmente se emplea la regresión logística, que se basa en el enlace simétrico logito. El propósito de este trabajo es presentar modelos de regresión binaria que, más bien, tengan enlaces asimétricos —aún no disponibles en software comercial—, cuando esta asimetría es más conveniente al investigador. Además, haciendo uso de un enfoque bayesiano con el programa WinBUGS, se implementa el programa BAYESPUCP, que facilitará la escritura de la sintaxis necesaria para implementar los modelos revisados. El BAYES-PUCP genera tanto las sintaxis de los modelos revisados así como de la estructura de los datos. El método es ilustrado con el caso de una muestra de agricultores que consideran la decisión de erradicar cultivos ilícitos de hoja de coca y, al mismo tiempo, se exploran factores asociados a esta decisión.
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Auenmüller, Christoph. "Automated Controller Design for a Missile Using Convex Optimization." Thesis, Luleå tekniska universitet, Rymdteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-60173.
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The focus of the present master thesis is the automation of an existing controllerdesign for a missile using two aerodynamic actuating systems. The motivation isto evaluate more missile concepts in a shorter period of time.The option used is trimming and linearization of a highly nonlinear missile at specic conditions. According to these conditions, either a two-dimensional operatingpoint grid dened by Mach number and height or three-dimensional operatingpoint grid dened by Mach number, height and angle of attack is generated forthe whole operating range of the missile. The controllers are designed at thesepoints using convex optimization. The convex set denes the pole placement areawhich is constrained by linear matrix inequalities according to the dynamic behaviorof the missile at the operating point conditions. These controllers describea validity area where the missile can be stabilized. This area consists all neighboringoperating points and denes therefore the grid density which can dier atspecic regions of the operating range. Controlling the missile to the target makesit necessary to apply gain-scheduling in order to get the manipulated variable byinterpolation of adjacent operating points. During this blending of the controllersa problem called windup can occur when an actuator is saturated. This mightlead to instability in worst case but can be counteracted by a model-recovery antiwindupnetwork which guarantees stability in the presence of saturation. Thisanti-windup design is automated by an ane linear parameter dependency of thegrid parameters and has the same validity area like the controllers.The whole design was successfully developed and tested in MATLAB/Simulink onmissiles using one or two aerodynamic actuating systems. The controllers have agood performance at small and high acceleration steps and the anti-windup keepsthe missile stable even though the actuators are saturated. Stability and robustnessof the controllers and anti-windup networks was veried as well as an airdefense maneuver where the missile starts at the ground and intercepts a targetat high altitude was successfully simulated for dierent grids and missiles.
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Bunzen, Jens. "Synthese enantiomerenreiner BINOL-Liganden zur Darstellung helicaler mehrkerniger Metallkomplexe." Aachen Shaker, 2009. http://d-nb.info/999594273/04.
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Vishwanathan, Ashwin. "Numerical investigation of wing morphing capabilities applied to a Horten type swept wing geometry." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4980.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains viii, 58 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 51-52).
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Sohaib, Muhammad. "Parameterized Automated Generic Model for Aircraft Wing Structural Design and Mesh Generation for Finite Element Analysis." Thesis, Linköpings universitet, Maskinkonstruktion, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71264.
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This master thesis work presents the development of a parameterized automated generic model for the structural design of an aircraft wing. Furthermore, in order to perform finite element analysis on the aircraft wing geometry, the process of finite element mesh generation is automated. Aircraft conceptual design is inherently a multi-disciplinary design process which involves a large number of disciplines and expertise. In this thesis work, it is investigated how high-end CAD software‟s can be used in the early stages of an aircraft design process, especially for the design of an aircraft wing and its structural entities wing spars and wing ribs. The generic model that is developed in this regard is able to automate the process of creation and modification of the aircraft wing geometry based on a series of parameters which define the geometrical characteristics of wing panels, wing spars and wing ribs.Two different approaches are used for the creation of the generic model of an aircraft wing which are “Knowledge Pattern” and “PowerCopy with Visual Basic Scripting” using the CATIA V5 software. A performance comparison of the generic wing model based on these two approaches is also performed. In the early stages of the aircraft design process, an estimate of the structural characteristic of the aircraft wing is desirable for which a surface structural analysis (using 2D mesh elements) is more suitable. In this regard, the process of finite element mesh generation for the generic wing model is automated. The finite element mesh is generated for the wing panels, wing spars and wing ribs. Furthermore, the finite element mesh is updated based on any changes in geometry and the shape of the wing panels, wing spars or wing ribs, and ensure that all the mesh elements are always properly connected at the nodes. The automated FE mesh generated can be used for performing the structural analysis on an aircraft wing.
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Abdul, Hamid Mohd Faisal. "Aerodynamic models for insect flight." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/aerodynamic-models-for-insect-flight(057be27b-265a-45a0-b8d0-dc3c02a62a77).html.
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Numerical models of insect flapping flight have previously been developed and used to simulate the performance of insect flight. These models were commonly developed via Blade Element Theory, offering efficient computation, thus allowing them to be coupled with optimisation procedures for predicting optimal flight. However, the models have only been used for simulating hover flight, and often neglect the presence of the induced flow effect. Although some models account for the induced flow effect, the rapid changes of this effect on each local wing element have not been modelled. Crucially, this effect appears in both axial and radial directions, which influences the direction and magnitude of the incoming air, and hence the resulting aerodynamic forces. This thesis describes the development of flapping wing models aimed at advancing theoretical tools for simulating the optimum performance of insect flight. Two models are presented: single and tandem wing configurations for hawk moth and dragonfly, respectively. These models are designed by integrating a numerical design procedure to account for the induced flow effects. This approach facilitates the determination of the instantaneous relative velocity at any given spanwise location on the wing, following the changes of the axial and radial induced flow effects on the wing. For the dragonfly, both wings are coupled to account for the interaction of the flow, particularly the fact that the hindwing operates in the slipstream of the forewing. A heuristic optimisation procedure (particle swarming) is used to optimise the stroke or the wing kinematics at all flight conditions (hover, level, and accelerating flight). The cost function is the propulsive efficiency coupled with constraints for flight stability. The vector of the kinematic variables consists of up to 28 independent parameters (14 per wing for a dragonfly), each with a constrained range derived from the maximum available power, the flight muscle ratio, and the kinematics of real insects; this will prevent physically-unrealistic solutions of the wing motion. The model developed in this thesis accounts for the induced flow, and eliminates the dependency on the empirical translation lift coefficient. Validations are shown with numerical simulations for the hover case, and with experimental results for the forward flight case. From the results obtained, the effect of the induced velocity is found to be greatest in the middle of the stroke. The use of an optimisation process is shown to greatly improve the flapping kinematics, resulting in low power consumption in all flight conditions. In addition, a study on dragonfly flight has shown that the maximum acceleration is dependent on the size of the flight muscle.
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Montero, Ryan M. "Analysis, Design and Testing of a Wind Tunnel Model to Validate Fiber-Optic Shape Sensing Systems." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23233.
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The ability to collect valuable data concerning the stress, strains, and shape profiles of aircraft and aircraft components during flight is important to fields such as structural health monitoring, gust alleviation, and flutter control. A research interest in the form of a NASA PhaseI SBIR called for possible systems that would be able to take accurate shape sensing data on a flexible wing aircraft. In a joint venture between Luna Technologies Inc. and Virginia
Polytechnic Institute and State University a flexible wing wind tunnel model was designed and constructed as a test article for the Luna Technologies Inc. fiber optic shape sensing system. In order to prove the capability of a fiber optic shape sensing system in a wind tunnel environment a flexible wing test article was constructed. The wing deflections and twists of the test article were modeled using a vortex lattice method called Tornado combined with simple beam theories. The beam theories were linear beam theories and the stiffness of the composite bodies was supplied by static testing of the test articles. The code was iterative in that it ran the VLM code to estimate the forces and moments on the wing and these were applied to a linear beam which gave the wing a new geometry which in turn was run through the VLM. The wind tunnel model was constructed at Virginia Tech using 3-D printing techniques for the fuselage and foam and fiberglass for the wings. On the bottom surface of the wings the Luna Technologies Inc. fiber optic shape sensing fiber was bonded along the leading and tailing edges. The swept-wing test article was experimentally tested in the Virginia Tech 6\'x6\' Stability Wind Tunnel at various airspeeds and the VLM based code results were in agreement, within margins of error and uncertainty, with the experimental results. The agreement of the analytical and experimental results verified the viability of using an iterative VLM code in combination with simple beam theories as a quick and relatively accurate approximation method for preliminary design and testing. The tests also showed that a fiber optic shape sensing system can be sufficiently tested in a wind tunnel environment, and if applied carefully could perhaps in the future provide useful shape and strain measurements.
Master of Science
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Browne, Michael John. "A unified strategy for windup prevention in control systems with multiple saturating actuators." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51629.
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Thesis (MScEng)--University of Stellenbosch, 2000.ENGLISH ABSTRACT: A unified method is proposed to treat saturation in both Multi-Input-Multi-Output MIMO and Single-Input-Single-Output controllers. This method offers superior performance over existing MIM 0 anti-saturation schemes. The anti-saturation problem is posed as a linear programming problem. A practical and efficient implementation of the algorithm is developed by transforming the problem into its dual linear programming form. The problem, in dual form, is then solved using the dual simplex method rather than the primal simplex method. The nature of the problem when expressed in dual form and the properties of the dual simplex method are harmonised to guarantee an initial basic feasible solution and an optimal bounded final solution in a finite, predictable and minimal number of iterations. The resultant controller never saturates, hence cannot windup. Furthermore the resultant controller always applies the optimal control effort to the plant to minimise the error signal input as follows: • The controller is governed such that while the future free response combined with the present forced response of the controller results in no saturation limits being exceeded, now or at some time in the future, the normal linear response of the controller prevails. • When the future free response combined with the present forced response of the controller will result in a saturation limit being reached, now or at some time in the future, the present time input signal into the controller is optimally governed to prevent the saturation limit from being exceeded at any future time.
AFRIKAANSE OPSOMMING: 'n Metode word voorgestel waarmee versadiging in enkel-inset enkel-uitset en meer-inset meeruitset (MIMU) stelsels beheer kan word. Die metode presteer beter as ander huidige teenversadiging- maatreels vir (MIMU) beheerders. Die teen-versadigings-probleem word as 'n lineere programmeringsprobleem herformuleer. 'n Praktiese en effektiewe implementering van die algoritme word verkry deur die probleem na die duale vorm te transformeer. Die probleem, in duale vorm, word opgelos met die duale simplex metode, in plaas van die direkte metode. Die eienskappe van hierdie formulering is 'n gewaarborgde, aanvanklike, bereikbare oplossing en 'n optimale, begrensde, finale oplossing in 'n eindige, voorspelbare en minimum aantal stappe. Die uiteindelike beheerder versadig nooit nie, en wen gevolglik nie op nie. Die beheerder wend altyd die optimale aanleg-inset aan om die foutsein te minimeer soos volg: • Wanneer die nul-inset gedrag saam met die huidige inset-gedrag geen beperkings nou of in die toekoms saloorskry nie, word geen beperkende aksie geneem nie, en tree die beheerder dus lineer op. • Sodra die toekomstige nul-inset gedrag saam met die huidige inset-gedrag, nou of later versadiging sou veroorsaak, word die huidige inset tot die beheerder optimaal begrens om latere versadiging te voorkom.
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Menon, Prathyush Purushothama. "Optimisation-based worst-case analysis and anti-windup synthesis for uncertain nonlinear systems." Thesis, University of Leicester, 2007. http://hdl.handle.net/2381/30245.
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This thesis describes the development and application of optimisation-based methods for worst-case analysis and anti-windup synthesis for uncertain nonlinear systems. The worst-case analysis methods developed in the thesis are applied to the problem of nonlinear flight control law clearance for highly augmented aircraft. Local, global and hybrid optimisation algorithms are employed to evaluate worst-case violations of a nonlinear response clearance criterion, for a highly realistic aircraft simulation model and flight control law. The reliability and computational overheads associated with different opti misation algorithms are compared, and the capability of optimisation-based approaches to clear flight control laws over continuous regions of the flight envelope is demonstrated. An optimisation-based method for computing worst-case pilot inputs is also developed, and compared with current industrial approaches for this problem. The importance of explicitly considering uncertainty in aircraft parameters when computing worst-case pilot demands is clearly demonstrated. Preliminary results on extending the proposed framework to the problems of limit-cycle analysis and robustness analysis in the pres ence of time-varying uncertainties are also included. A new method for the design of anti-windup compensators for nonlinear constrained systems controlled using nonlinear dynamics inversion control schemes is presented and successfully applied to some simple examples. An algorithm based on the use of global optimisation is proposed to design the anti-windup compensator. Some conclusions are drawn from the results of the research presented in the thesis, and directions for future work are identified.
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Taylor, Sarah E. "Biologically inspired wing planform optimization." Worcester, Mass. : Worcester Polytechnic Institute, 2009. http://www.wpi.edu/Pubs/ETD/Available/etd-052109-141751/.
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Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: low reynolds; flight; flow visualization; low aspect ratio; micro air vehicles; planform; wings; mav; mavs. Includes bibliographical references (leaves 105-106).
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Negi, Prabal. "Boundary layers over wing sections." Licentiate thesis, KTH, Stabilitet, Transition, Kontroll, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217984.
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The understanding of developing boundary layers over wings is an important topic from the perspective of industrial applications. An increased understanding would be consequential not only for achieving higher fuel efficiency but also in the design of aircraft control strategies. With these aims in mind, the current work aims to further the understanding of developing boundary layer over wingsections. The study is performed with two particular perspectives in mind -unsteady aerodynamic effects in a pitching airfoil and turbulent boundary layerstructure in non-equilibrium boundary layers over a stationary airfoil.The boundary layer evolution in unsteady natural laminar flow airfoils undergoing small-amplitude pitch-oscillations is investigated. For high Reynolds numbers the origins of the non-linear unsteady aerodynamic response of laminar airfoils is explained on the basis of quasi-steady assumptions. Temporal nonlinearitiesin aerodynamic forces are shown to be inherently linked to thenon-linearities of static aerodynamic force coefficients and that a simple phaselagconcept can model the observed non-linear unsteady response. On the other hand at lower Reynolds numbers, when there exists an unstable leading edgelaminar separation bubble, the unsteady response is dynamically rich and changes in boundary layer characteristics can be abrupt. Such quasi-steadyphase-lag concepts are no longer appropriate to explain the unsteady flow physics in such a case. For the case of stationary airfoils, flow statistics for flow around an airfoil at two different Reynolds numbers are compared to assess Reynolds number effects in non-equilibrium flows. Pressure gradient effects found to be stronger at low Reynolds numbers, leading to higher energy in the larger structures present in the outer part of the turbulent boundary layer.QC 20171121
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Benson, Christopher Lee. "Linear actuator powered flapping wing." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59892.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 58-59).
Small scale unmanned aerial vehicles (UAVs) have proven themselves to be useful, but often too noisy for certain operations due to their rotary motors. This project examined the feasibility of using an almost silent linear actuator to power a flapping wing UAV. In order to this, a wing was designed and installed into a test set-up to replicate normal flight conditions of flapping wing flight (FWF). The designs of the wing, the test set-up and the actual experiments were biomimetic, looking to approximate the flight of real birds. The main goal of this study was to characterize a novel new linear actuator being developed in the Bio-Instrumentation Lab at MIT based on important parameters for FWF including the mounting position, the frequency of oscillation and the amplitude of oscillation of the wing. Ultimately the linear actuator performed well under all of the tests and was only limited by the control software. When the frequency and amplitude of oscillation were raised, the force on the actuator increased. The mounting position ended up not having a correlation with the force on the actuator, leading one to believe that it is not a critical parameter for this actuator-wing system.
by Christopher L. Benson.
S.B.
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Leonard, Benjamin Yoshi. "Flapping Wing Flight Dynamic Modeling." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/34790.
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Highly agile, hover capable flapping wing flight is a relatively new area of study in engineering. Researchers are looking to flapping flight as a potential source for the next generation of reconnaissance and surveillance vehicles. These systems involve highly complicated physics surrounding the flapping wing motion and unusual characteristics due to a hover requirement not normally associated with conventional aircraft. To that end this study focuses on examining the various models and physical parameters that are considered in various other studies. The importance of these models is considered through their effect on the trim and stability of the overall system. The equations of motion are modeled through a quasi coordinate Lagrangian scheme while the aerodynamic forces are calculated using quasi-steady potential flow aerodynamics. Trim solutions are calculated using periodic shooting for several different conditions including hover, climb, and forward flight. The stability of the trim is calculated and examined using stroke-averaged and Floquet theory. Inflow and viscous effects are added and their effects on trim and stability examined. The effects of varying hinge location and the inclusion of stroke deviation in the wing kinematics are also explored. The stroke-averaged system was not found to be a direct replacement for the periodic system as the stability was different for the two systems. Inflow and viscosity were found to have large effects on the stability of the system and models accounting for the two should be included in future flight dynamic models.Master of Science
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Farrell, Joseph H. "DYNAMICALLY SCALED OBLIQUE FLYING WING." Thesis, The University of Arizona, 2009. http://hdl.handle.net/10150/192337.
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Dippold, Vance Fredrick III. "Numerical Assessment of the Performance of Jet-Wing Distributed Propulsion on Blended-Wing-Body Aircraft." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/34878.
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Conventional airliners use two to four engines in a Cayley-type arrangement to provide thrust, and the thrust from these engines is typically concentrated right behind the engine. Distributed propulsion is the idea of redistributing the thrust across most, or all, of the wingspan of an aircraft. This can be accomplished by using several large engines and using a duct to spread out the exhaust flow to form a jet-wing or by using many small engines spaced along the span of the wing. Jet-wing distributed propulsion was originally suggested by Kuchemann as a way to improve propulsive efficiency. In addition, one can envision a jet-wing with deflected jets replacing flaps and slats and the associated noise.
The purpose of this study was to assess the performance benefits of jet-wing distributed propulsion. The Reynolds-averaged, finite-volume, Navier-Stokes code GASP was used to perform parametric computational fluid dynamics (CFD) analyses on two-dimensional jet-wing models. The jet-wing was modeled by applying velocity and density boundary conditions on the trailing edges of blunt trailing edge airfoils such that the vehicle was self-propelled. As this work was part of a Blended-Wing-Body (BWB) distributed propulsion multidisciplinary optimization (MDO) study, two airfoils of different thickness were modeled at BWB cruise conditions. One airfoil, representative of an outboard BWB wing section, was 11% thick. The other airfoil, representative of an inboard BWB wing section, was 18% thick. Furthermore, in an attempt to increase the propulsive efficiency, the trailing edge thickness of the 11% thick airfoil was doubled in size. The studies show that jet-wing distributed propulsion can be used to obtain propulsive efficiencies on the order of turbofan engine aircraft. If the trailing edge thickness is expanded, then jet-wing distributed propulsion can give improved propulsive efficiency. However, expanding the trailing edge must be done with care, as there is a drag penalty. Jet-wing studies were also performed at lower Reynolds numbers, typical of UAV-sized aircraft, and they showed reduced propulsive efficiency performance. At the lower Reynolds number, it was found that the lift, drag, and pitching moment coefficients varied nearly linearly for small jet-flap deflection angles.
Master of Science
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Adegbindin, Moustaine Kolawole Agnide. "Control Power Optimization using Artificial Intelligence for Forward Swept Wing and Hybrid Wing Body Aircraft." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/74950.
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Many futuristic aircraft such as the Hybrid Wing Body have numerous control surfaces that can result in large hinge moments, high actuation power demands, and large actuator forces/moments. Also, there is no unique relationship between control inputs and the aircraft response. Distinct sets of control surface deflections may result in the same aircraft response, but with large differences in actuation power. An Artificial Neural Network and a Genetic Algorithm were used here for the control allocation optimization problem of a Hybrid Wing Body to minimize the Sum of Absolute Values of Hinge Moments for a 2.5-G pull-up maneuver. To test the versatility of the same optimization process for different aircraft configurations, the present work also investigates its application on the Forward Swept Wing aircraft. A method to improve the robustness of the process is also presented. Constraints on the load factor and longitudinal pitch rate were added to the optimization to preserve the trim constraints on the control deflections. Another method was developed using stability derivatives. This new method provided better results, and the computational time was reduced by two orders of magnitude. A hybrid scheme combining both methods was also developed to provide a real-time estimate of the optimum control deflection schedules to trim the airplane and minimize the actuation power for changing flight conditions (Mach number, altitude and load factor) in a pull-up maneuver. Finally, the stability derivatives method and the hybrid scheme were applied for an antisymmetric, steady roll maneuver.Master of Science
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Marques, Katia Antunes. "Análise bayesiana em modelos TRI de três parâmetros." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/45/45133/tde-02092008-214645/.
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Neste trabalho discutimos a análise bayesiana em modelos TRI (Teoria da Resposta ao Item) de três parâmetros com respostas binárias e ordinais, considerando a ligação probito. Em ambos os casos usamos técnicas baseadas em MCCM (método de Monte Carlo baseado em Cadeias de Markov) para estimação dos parâmetros dos itens. No modelo com respostas binárias, consideramos dois conjuntos de dados resultantes de provas com itens de múltipla-escolha. Para esses dados, foi feito um estudo da sensibilidade à escolha de distribuições a priori, além de uma análise das estimativas a posteriori para os parâmetros dos itens: discriminação, dificuldade e probabilidade de acerto ao acaso. Um terceiro conjunto de dados foi utilizado no estudo do modelo com respostas ordinais. Estes dados são provenientes de uma disciplina básica de estatística, onde a prova contêm itens dissertativos. As respostas foram classificadas nas categorias: certa, errada ou parcialmente certa. Utilizamos o programa WinBugs para a estimação dos parâmetros do modelo binário e a função MCMCordfactanal do programa R para estimar os parâmetros do modelo ordinal. Ambos os softwares são não proprietários e gratuitos (livres).In this dissertation the bayesian analysis for three parameters IRT (Item Response Theory) models with binaries and ordinals responses, considering the probit model, was discussed. For both cases, binary and ordinal, techniques based on MCCM (Monte Carlo Markov Chain) were used to estimate the items parameters. For binary response model, was considered two data sets from tests with multipla choices items. For these two data sets, a sensibility study of the priori distributions choice was considered, and also, an analyses of a posteriori estimates of the items parameters: discrimination, difficulties and guessing. A third data set is used to ilustrate the ordinal response model. This come from an elementar statistical course, where a test with open items is considered. The responses are classified in the following categories: correct, wrong or partial correct. The WinBugs software was used to estimate the parameters for the binary model and, for the ordinal model was considered the function MCMCordfactanal from R program.