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Sarofim, Marcus C., Chris Eliot Forest, David M. Reiner, and John M. Reilly. "Stabilization and Global Climate Policy." MIT Joint Program on the Science and Policy of Global Change, 2004. http://hdl.handle.net/1721.1/5423.
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Academic and political debates over long-run climate policy often invoke “stabilization” of atmospheric concentrations of greenhouse gases (GHGs), but only rarely are non-CO2 greenhouse gases addressed explicitly. Even though the majority of short-term climate policies propose trading between gases on a global warming potential (GWP) basis, discussions of whether CO2 concentrations should be 450, 550, 650, or perhaps as much as 750 ppm leave unstated whether there should be no additional forcing from other GHGs beyond current levels or whether separate concentration targets should be established for each GHG. Here we use an integrated modeling framework to examine multi-gas stabilization in terms of temperature, economic costs, carbon uptake, and other important consequences. We show that there are significant differences in both costs and climate impacts between different "GWP equivalent" policies and demonstrate the importance of non-CO2 GHG reduction on timescales of up to several centuries.<br>Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).<br>Sarofim was supported in part by a Martin Sustainability Fellowship
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Chai, Li. "Multirate periodic systems : robust model validation and stabilization /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202002%20CHAI.
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Glamheden, Mikael. "Stabilization of Constant Power Loads Using Model Predictive Control." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284685.
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This thesis considers stabilization of constant power loads (CPLs) fed by a dcpower source through an input filter, using model predictive control (MPC).Train propulsion systems generally utilize electrical motors whose output torqueis tightly regulated by power converters. Often, these systems behave as CPLs.When a CPL is coupled with an input filter it can lead to a stability problemknown as the negative impedance instability problem. Current state ofthe art regulators deal with this problem using classical frequency domainoptimization-based controllers, such asH1. This thesis instead proposes a linearparameter-varying model predictive controller (LPV-MPC). This advancedcontrol method solves the negative impedance instability problem while alsobeing capable of explicitly addressing signal constraints, which often exist inpower converter applications. The regulator is evaluated in MATLAB/Simulinkas well as in a software-in-the-loop (SIL) simulator. It has furthermore beenrealized in a real-time hardware-in-the-loop (HIL) simulator and tested in apower laboratory. Theoretical results show improved performance over conventionalH1 controllers, in terms of damping and control input use, undercertain operating conditions where the control input is limited. The resultscan be used as a benchmark of theoretical performance limits for design ofother regulators.<br>Detta examensarbete avhandlar stabilisering av konstanta effektlaster (CPL)matade med dc-effekt via ett ingångfilter, med hjälp av modellprediktiv reglering(MPC). Drivsystem i tåg använder vanligen elektriska motorer varsmoment regleras hårt utav effektomriktare. Dessa system beter sig ofta somen CPL. När en CPL sammankopplas med ett ingångfilter kan det leda till ettstabilitetsproblem känt som the negative impedance instability problem (ung.negativ-impedans-instabilitetsproblemet). Dagens främsta regulatorer angriperdetta problem genom att använda klassiska regulatorer baserade på optimeringi frekvensdomän, till exempel H1. I detta examensarbete föreslås iställeten linjär parametervarierande modellprediktiv regulator (LPV-MPC). Dennaavancerade reglermetod löser stabilitetsproblemet och kan samtidigt hanterasignalbegränsningar explicit. Signalbegränsningar är något som ofta finnsi tillämpningar som involverar kraftomriktare. Regulatorn utvärderas i MATLAB/Simulink samt i en mjukvarusimuleringsmiljö. Regulatorn har dessutomförverkligats i en hårvarusimuleringsmiljö och testats i ett labb för kraftelektronik.Teoretiska resultat visar på förbättrad prestanda i jämförelse med konventionellaH1-regulatorer, vad gäller dämpning och användning av styrsignal,i vissa arbetsfall när styrsignalen är begränsad. Resultaten kan användassom ett riktmärke som visar på gränser för teoretisk prestanda vid design avandra regulatorer.
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Afacan, Kamil. "Modeling And Control Of A Stabilization System." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605576/index.pdf.
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Elevation axis model of a barrel stabilization system is constructed. The
nonlinearities which are considered in the model are orifice flow
characteristics, coulomb friction, hard-stop limits, kinematics of the system
and unbalance on the barrel. A Simulink®<br>model for the servo valve,
actuation system and barrel is constructed. Servo valve identification is
made via the actual test data. Compressibility of the hydraulic fluid is taken
into consideration while modeling the actuation system. Friction model is
simulated for different cases. Controller of the system is constructed by two
PIDs, one for each of the velocity and the position loops. Velocity feed
forward can reduce the time to make a quick move by the system. The
disturbance is evaluated from a given road profile and disturbance feed
forward is applied to the system.
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Palomo, Monica. "Stabilization of enzymatically polymerized 2,4 dichlorophenol in model subsurface geomaterials." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/664.
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Kartalou, Georgia-Ioanna [Verfasser]. "Stabilization of dendritic spines in an Alzheimer mouse model / Georgia-Ioanna Kartalou." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2020. http://d-nb.info/1213094828/34.
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Zhang, Li Zhi. "Application of Bayesian model class selection on differential problems in geotechnical engineering." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2590616.
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Esterhuizen, Willem Daniël. "Stability and stabilization conditions for Takagi-Sugeno fuzzy model via polyhedral Lyapunov functions." Thesis, Boston University, 2012. https://hdl.handle.net/2144/12365.
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Thesis (M.S.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.<br>The Takagi-Sugeno (T-S) fuzzy model together with parallel distributed compensation forms a very effective framework for modeling, analysis and control design for nonlinear systems. A large body of theory exists that deals with this framework and most of the fundamental notions, such as stability, stabilizability, controller design, observer design, etc., have been studied extensively. A large number of the well-established results are based on quadratic Lyapunov functions. The main reason is that the stability and design conditions under quadratic Lyapunov functions are in the form of linear matrix inequalities which are easily solvable.
However, the class of quadratic Lyapunov functions are conservative, in the sense that there are systems for which their stability cannot be established by quadratic Lyapunov functions. A natural question to ask is: are there other candidate Lyapunov functions that are less conservative? It turns out that the class of polyhedral Lyapunov functions are universal for the T-S fuzzy model stability problem, that is if a T-S fuzzy system is stable, there exists a polyhedral Lyapunov function that proves the stability. This thesis is a first look at the applicability of polyhedral Lyapunov functions to the T-S fuzzy model-based framework for the stability analysis and control design of nonlinear systems.
First, two stability theorems are presented in this thesis. It is shown that the stability of a T-S fuzzy system via polyhedral Lyapunov functions can be established through linear programming. Next, the stabilization problem is investigated to find control laws that guarantee the stability of the closed-loop systems. Two stabilization theorems are presented which are derived from the stability theorems. The conditions of the stabilization theorems are in the form of nonconvex inequalities that are not readily solvable. Implementation examples are included in which solutions are found through either brute-force, or making the constraints convex in exchange for a loss of feasible space. Two relaxed stabilization theorems are also derived by taking advantage of certain aspects of the T-S fuzzy model.
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GONG, PENG. "A SUC MODEL STUDY FOR SOLIDIFICATION/STABILIZATION OF ORGANIC HAZARDOUS WASTES WITH REACTIVATED CARBON." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin983566537.
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Imsland, Lars. "Topics in nonlinear control. : Output Feedback Stabilization and Control of Positive Systems." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-355.
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<p>The contributions of this thesis are in the area of control of systems with nonlinear dynamics. The thesis is divided into three parts. The two first parts are similar in the sense that they both consider output feedback of rather general classes of nonlinear systems, and both approaches are based on mathematical programming (although in quite different ways). The third part contains a state feedback approach for a specific system class, and is more application oriented.</p><p>The first part treats control of systems described by nonlinear difference equations, possibly with uncertain terms. The system dynamics are represented by piecewise affine difference inclusions, and for this system class, piecewise affine controller structures are suggested. Controller synthesis inequalities for such controller structures are given in the form of Bilinear Matrix Inequalities (BMIs). A solver for the BMIs is developed. The main contribution is to the output feedback case, where an observer-based controller structure is proposed. The theory is exemplified through two examples.</p><p>In the second part the output feedback problem is examined in the setting of Nonlinear Model Predictive Control (NMPC). The state space formulation of NMPC is inherently a state feedback approach, since the state is needed as initial condition for the prediction in the controller. Consequently, for output feedback it is natural to use observers to obtain estimates of the state. A high gain observer is applied for this purpose. It is shown that for several existing NMPC schemes, the state feedback stability properties ``semiglobally'' hold in the output feedback case. The theory is illuminated with a simple example.</p><p>Finally, a state feedback controller for a class of positive systems is proposed. Convergence of the state to a certain subset of the first orthant, corresponding to a constant ``total mass'' (interpreting states as masses) is obtained. Conditions are given under which convergence to this set implies asymptotic stability of an equilibrium. Simple examples illustrate some properties of the controller. Furthermore, the control strategy is applied to the stabilization of a gas-lifted oil well, and simulations on a rigorous multi-phase dynamic simulator of such a well demonstrate the controller performance.</p>
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Monasterios, Perez Karin. "Structural adjustment and the collapse of the Bolivian model of accumulation." Ottawa, 1994.
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Jette-Nantel, Simon. "Implications of Off-Farm Income for Farm Income Stabilization Policies." UKnowledge, 2013. http://uknowledge.uky.edu/agecon_etds/15.
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This dissertation examines to what extent off-farm diversification may be an appropriate and accessible tool to mitigate the adverse effects from market failures and incompleteness in the crop and farm income insurance market. While the influence of the nonfarm sector has long been recognized as a primary force in shaping farm structure, off-farm income is rarely acknowledge as a risk management tool for operators and households of commercial farms. The dissertation develops a dynamic model that includes capital market imperfections, economies of scale in farm production, and the presence of adjustment costs in labor allocation decisions. The model provides a realistic characterization of the environment defining income and financial risks faced by farm operators, as well as the risk management alternatives available to them.
It is found that introducing off-farm labor can substantially mitigate the adverse effects of farm income risk on farm operators' and households' welfare, even for larger commercial farms. However, the diversification of labor by the main operator seems to impose labor and managerial constraints that can reduce the intensity and technical efficiency of the farm production. Alternatively, diversification at the household level through the allocation of spousal labor off the farm provides benefits in mitigating the adverse effects of farm income risk on farm production and efficiency, and on operators and households welfare. It thus provides an efficient risk management alternative that is consistent with most rationales that are invoked to justify farm policies.
Results suggest that the increasing incidence and importance of off-farm income within the farm population of most OECD countries is highly relevant in the design of effective farm policies This form of diversification can reduce the need and effectiveness of farm income stabilization polices. While it has been argued elsewhere that broader economic policies had a large influence in closing the income gap between farm and urban households, such policies may also have a role to play in addressing farm income risk issues and, in some cases, may represent more sustainable and efficient policy alternatives.
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Böck, Martin [Verfasser]. "Model Predictive and Flatness-based Path Following Control and Manifold Stabilization with Applications / Martin Böck." Aachen : Shaker, 2016. http://d-nb.info/1118258584/34.
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Kwok, Sabastein Yih Feng. "Stochastic analysis of coupled surface and subsurface flow model in steep slopes for slope stability analysis /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202003%20KWOK.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.<br>Includes bibliographical references (leaves 201-205). Also available in electronic version. Access restricted to campus users.
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Bozok, Omer Loehr J. Erik. "Response of micropiles in earth slopes from large-scale physical model tests." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6480.
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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 17, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. J. Erik Loehr. Includes bibliographical references.
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Al-Jhayyish, Anwer K. "Incorporating Chemical Stabilization of the Subgrade in Pavement Design andConstruction Practices." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1405480246.
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Johansen, David Linn. "Video Stabilization and Target Localization Using Feature Tracking with Video from Small UAVs." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1522.pdf.
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Wilson, L. G., S. P. Neuman, A. G. Guzman, T. P. Leo, and M. D. Osborn. "Effects of Channel Stabilization in Tucson Stream Reaches on Infiltration and Ground-Water Recharge: Volume I Model Studies." Water Resources Research Center. The University of Arizona, 1987. http://hdl.handle.net/10150/306944.
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Final Report to Pima County Department of Transportation and Flood Control District, June 1987.<br>Volume I Executive Summary: The increase in extreme flood events in Tucson stream channels has led to the use of channel stabilization procedures to mitigate flood damage. These procedures include bank protection with soil cement, channel modification, and grade control structures. The channel stabilization and grade control structures are typically constructed to depths up to 20 ft below the channel bottom. Channel modification generally consists of widening and straightening channels in bank-protected reaches. There is concern that structural changes in the rivers will reduce infiltration and recharge during the periodic flow events. Ground-water recharge occurs when water that has infiltrated at the land surface and percolated through the vadose zone reaches the water table. The vadose zone is the partially saturated geological region between the land surface and the water table. Recognizing this concern, Pima County contracted with the Water Resources Research Center of the University of Arizona, to estimate the effect of channel modification on infiltration and recharge by undertaking computer simulations of subsurface flow during a representative runoff event in modified and unmodified channels. The purpose of a companion study, which is reported in Volume II of this report, was to estimate the effect of channel modification in localized reaches on the basin-wide recharge regimen.
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Spånning, Anna C. "Towards Institutional Stabilization and Development? : A Study of Inter-Organizational Cooperation in the Tajik Cotton Industry." Doctoral thesis, Karlstads universitet, Avdelningen för politiska och historiska studier, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-4892.
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Close to two decades after the break-up of the Soviet Union, there is still a marked difference in developmental paths, including institutional as well as economic development and performance among the states emerging from the ruins of the vast empire. Turning attention to the least successful post-Soviet region, Central Asia, and Tajikistan in particular, this thesis provides a contribution to the discussion of how to institutionalize social power and build the foundations for political community in post-colonial societies. It is argued here that increased institutional stability may be achieved through inter-organizational cooperation among main actors within an institutional setting. Through the dispersion of intra- and inter-organizational effects of cooperation beyond the action situations where they are produced, several goals may be achieved. These are increased predictability, transparency and durability in governance, a more equitable distribution of wealth, and (in relation to the kinship-foundation of Tajik society) the embracing of kin-divisions in society. The study examines how and why organizations decide to get involved in cooperative collective activities within the Tajik cotton industry, an industry infamous for its unscrupulous financing schemes to which local investors tie farmers; schemes lacking business ethics and the interconnection of the social and economic with political relations. The study, through an embedded case study of one project (the Farmers’ Ownership Model), also examines the institutional implications of inter-organizational collective activities. The study’s empirical base is a combination of data derived from literature, reports, reviews of official documents, as well as from interviews and an expert survey conducted among organizational representatives with expert knowledge on the Tajik cotton industry. The results suggest that it is possible to divide the forms of cooperation into three broad categories; business based cooperation, development and support-based cooperation and unilateral cooperative activity. The latter category contains interactions based on helping as well as on coercion. The motives for cooperating follow the same divisions, with profit and position-related motives dominating business-based cooperation. Development and support-based cooperation are primarily motivated by non-profit factors, such as community-(re)building and knowledge enhancement, as well as position-related motives. Within the group of unilateral interactions, the same divisions valid for business-based cooperation (unilateral cooperative activity based on coercion) and development and support-based cooperation (unilateral cooperative activity based on helping) are found. The actors approached for this study confirm that the institutional setting is “difficult” and that the social and political climate is not supportive of inter-organizational cooperative collective activities. Despite this, the actors agree that the time is right for cooperative efforts. The implications of inter-organizational cooperative collective activities within the frameworks of the examined Farmers’ Ownership Model project are many and important from a stabilizing perspective. Numerous strategic effects have been identified, among which is the creation of the first open farmer-owned joint stock company in the country, providing crop financing, high quality input, and technical assistance to the farmers in the northern Sugd region. This is the most tangible effect, as is legislative change related to the marketing of cotton. The learning and knowledge-creation effects as a result of inter-organizational interactions within the project are also substantial. Client as well as non-client farmers have, through the technical assistance provided through the project company, managed to improve awareness in terms of their legal status. In addition, the technical assistance component of the project has served to improve productivity and the quality of the cotton grown. Despite indications of attitudinal changes within the action situations examined, there is no clear-cut evidence of trust effects at the institutional level. The results of empirical examination of the Tajik cotton industry to a large extent support the central thesis of the study.
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Tanna, Sailesh Kumar. "The design of simple optimal policy rules for macroeconomic stabilization with application to the National Institute model of the UK economy." Thesis, London South Bank University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329165.
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Kříž, Vlastimil. "Řídicí systém vzdušného průzkumného prostředku pro vnitřní prostředí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218869.
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This work deals with multi-rotor helicopters, known as copters. The first part is a review of existing solutions, and an appropriate platform for use as aerial reconnaissance vehicle is chosen. In the next part a mathematical model of copter is created and its parameters are estimated. Based on this model a state-space controller for control system is designed. This is then tested on the created model and implemented in real copter.
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Huhmann, Susanne [Verfasser]. "Stabilization of peptides by site-specific incorporation of fluorinated amino acids: Model studies and the development of fluorinated, peptide-based HIV-1 fusion inhibitors / Susanne Huhmann." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1176632922/34.
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Potluri, Tejaswy. "A Biomechanical Evaluation of Three Atlantoaxial Transarticular Screw Salvaging Fixation Techniques." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1271814240.
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Grove, Dale A. III. "Mathematical model of solid state thermo-oxidative stabilization of acrylic precursors for carbon fibers : evaluation of the properties of carbon fibers produced from melt-spun pan-based fibers." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/11111.
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Čamaj, Peter. "Stabilizační a autopilotní systém pro RC model letadla." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-221051.
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The master thesis deals with design and realization of stabilizing and autopilot system, which is used in radio controlled model planes. The thesis contains a proposal of hardware platform, which is able to control the plane model based on data measured from a sensor system. Moreover, this thesis describes a software implementation of individual modules, which is measured the onboard values. The basic principles of stabilization and autonomous flight control are also summarized. In conclusion, the system is subjected to flight tests.
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Erdal, Zeynep Kisoglu. "An Investigation of the Biochemistry of Biological Phosphorus Removal." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/26383.
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Although enhanced biological phosphorus removal (EBPR) and complete biological nutrient removal (BNR) systems can be operated successfully by experienced operators, the accuracy of design and strength of the scientific background need to be reinforced to enable accurate modeling and economically optimal design. One way to accomplish this would be through a better understanding of the biochemical mechanisms and microbial population dynamics that determine the reliability and efficiency of EBPR, and the utilization of this information to improve the design and operation of BNR plants. Such knowledge will also contribute to better structure of modeling tools that are used for design and educational purposes. The current body of knowledge is limited to observational studies that lack detailed biochemical explanations backed with a series of well planned experiments, and this has introduced uncertainties and inaccuracies into the biochemical and design models. Therefore, this study mainly covers a biochemical survey of the underlying metabolisms of active populations in BNR sludges. BNR biomass with biological phosphorus removal (BPR) capability was cultivated in continuous flow reactor (CFR) systems, configured as either University of Cape Town (UCT) and anoxic/oxic (A/O) systems. Following an acclimation period at 20°C, low temperature stress (5°C) was imposed on one UCT system for investigation of the response of the microbial consortium responsible from EBPR activity under cold temperature. Once a stable population with EBPR capabilities is established in each system, activities of ten enzymes that are hypothesized to be taking part in the EBPR metabolism were measured. These enzymes were selected among those that take part in major known pathways of bacterial energy and growth metabolism. Also, 13C-NMR was used as a tool to monitor the flux of labeled carbon in and out of pools of cellular storage; i.e. glycogen and polyhydroxyalkanoates (PHA). Combining the gathered information, accurate mass balances of carbons and reducing equivalents were calculated, eventually leading to determination of the biochemical pathways utilized by the EBPR consortium. Additionally, anaerobic stabilization of COD, a long debated but empirically established phenomenon, was addressed during the study. Considering the pathways proposed to be operative under different conditions imposed on the EBPR systems, a biochemical explanation for the occurrence of COD stabilization in wastewater treatment systems that incorporate anaerobic zones was proposed. Accordingly, depending on the pathways actively used by a microbial consortium, electrons stored in NADH and FADH2 can either be transferred to the terminal electron acceptor, oxygen, or they can be incorporated into storage polymers such as glycogen for future use. Such differences in metabolism reflect in the quantity of the oxygen consumed in the aerobic reactors. Thus, the correct incorporation of anaerobic stabilization of COD into process design would reduce design aeration requirements and result in economic savings during both construction and operation.<br>Ph. D.
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Sherikov, Alexander. "Balance preservation and task prioritization in whole body motion control of humanoid robots." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT032/document.
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Un des plus grands défis dans la commande des robots est de combler l'écart entre la capacité de mouvement de l'humain et des robots humanoïdes. La difficulté réside dans la complexité des systèmes dynamiques représentant les robots humanoïdes: la non linéarité, le sous-actionnement, le comportement non-lisse en raison de collisions et de frottement, le nombre élevé de degrés de liberté. De plus, les robots humanoïdes sont censés opérer dans des environnements non-déterministes, qui exigent une commande temps réel avancée.L'approche qui prévaut actuellement pour faire face à ces difficultés est d'imposer diverses restrictions sur les mouvements et d'employer des modèles approximatifs des robots. Dans cette thèse, nous suivons la même ligne de recherche et proposons une nouvelle approche pour la conception de contrôleurs corps entier qui préservent l'équilibre. L'idée principale est de tirer parti des avantages des modèles approximatifs et de corps entier en les mélangeant dans un seul problème de contrôle prédictif avec des objectifs strictement hiérarchisés.La préservation de l'équilibre est l'une des principales préoccupations dans la commande des robots humanoïdes. Des recherches antérieures ont déjà établi que l'anticipation des mouvements est essentiel à cet effet. Nous préconisons que l'anticipation est utile dans ce sens comme un moyen de maintenir la capturabilité du mouvement, i.e., la capacité de s'arrêter. Nous soulignons que capturabilité des mouvements prévus peut être imposée avec des contraintes appropriées. Dans la pratique, il est fréquent d'anticiper les mouvements du robot à l'aide de modèles approximatifs afin de réduire l'effort de calcul, par conséquent, un contrôleur séparé de mouvement du corps entier est nécessaire pour le suivi. Au lieu de cela, nous proposons d'introduire l'anticipation avec un modèle approximatif directement dans le contrôleur corps entier. En conséquence, les mouvements du corps entier générés respectent les contraintes de capturabilité et les mouvements anticipes du modèle approximatif prennent en compte les contraintes et les tâches désirées pour le corps entier. Nous posons nos contrôleurs du mouvement du corps entier comme des problèmes d'optimisation avec des objectifs strictement hiérarchisés. Bien que cet ordre de priorité soit commun dans la littérature, nous croyons qu'il est souvent mal exploité.Par conséquent, nous proposons plusieurs exemples de contrôleurs, où la hiérarchisation est utile et nécessaire pour atteindre les comportements souhaités. Nous évaluons nos contrôleurs dans deux scénarios simulés, où la tâche du corps entier du robot influence la marche et le robot exploite éventuellement un contact avec la main pour maintenir son équilibre en étant debout<br>One of the greatest challenges in robot control is closing the gap between themotion capabilities of humans and humanoid robots. The difficulty lies in thecomplexity of the dynamical systems representing the said robots: theirnonlinearity, underactuation, discrete behavior due to collisions and friction,high number of degrees of freedom. Moreover, humanoid robots are supposed tooperate in non-deterministic environments, which require advanced real timecontrol. The currently prevailing approach to coping with these difficulties isto impose various limitations on the motions and employ approximate models ofthe robots. In this thesis, we follow the same line of research and propose anew approach to the design of balance preserving whole body motion controllers.The key idea is to leverage the advantages of whole body and approximate modelsby mixing them within a single predictive control problem with strictlyprioritized objectives.Balance preservation is one of the primary concerns in the control of humanoidrobots. Previous research has already established that anticipation of motionsis crucial for this purpose. We advocate that anticipation is helpful in thissense as a way to maintain capturability of the motion, i.e., the ability tostop. We stress that capturability of anticipated motions can be enforced withappropriate constraints. In practice, it is common to anticipate motions usingapproximate models in order to reduce computational effort, hence, a separatewhole body motion controller is needed for tracking. Instead, we propose tointroduce anticipation with an approximate model into the whole body motioncontroller. As a result, the generated whole body motions respect thecapturability constraints and the anticipated motions of an approximate modeltake into account whole body constraints and tasks. We pose our whole bodymotion controllers as optimization problems with strictly prioritizedobjectives. Though such prioritization is common in the literature, we believethat it is often not properly exploited. We, therefore, propose severalexamples of controllers, where prioritization is useful and necessary toachieve desired behaviors. We evaluate our controllers in two simulatedscenarios, where a whole body task influences walking motions of the robot andthe robot optionally exploits a hand contact to maintain balance whilestanding
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Cox, Bruce. "Feedback Stabilization of Inverted Pendulum Models." VCU Scholars Compass, 2005. http://scholarscompass.vcu.edu/etd/1174.
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Many mechanical systems exhibit nonlinear movement and are subject to perturbations from a desired equilibrium state. These perturbations can greatly reduce the efficiency of the systems. It is therefore desirous to analyze the asymptotic stabilizability of an equilibrium solution of nonlinear systems; an excellent method of performing these analyses is through study of Jacobian linearization's and their properties. Two enlightening examples of nonlinear mechanical systems are the Simple Inverted Pendulum and the Inverted Pendulum on a Cart (PoC). These examples provide insight into both the feasibility and usability of Jacobian linearizations of nonlinear systems, as well as demonstrate the concepts of local stability, observability, controllability and detectability of linearized systems under varying parameters. Some examples of constant disturbances and effects are considered. The ultimate goal is to examine stabilizability, through both static and dynamic feedback controllers, of mechanical systems
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Novák, Pavel. "Návrh řídicího algoritmu pro stabilizaci letadla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230970.
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Master’s thesis: "Design of the control algorithm for aircraft stabilization" summarizes aircraft aerodynamics knowledge, from which nonlinear mathematical model of the aircraft and propeller propulsion system are created. Design of the control algorithm for angle position stabilization (for longitudinal motion) and the control algorithm for “Flight Path Angle hold“ and “Flight Level Change” modes is also presented here. Designed control algorithms are tested within the simulation of the real atmosphere at the end of the thesis.
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Krupiński, Szymon. "Suivi des structures offshore par commande référencée vision et multi-capteurs." Thesis, Nice, 2014. http://www.theses.fr/2014NICE4051.
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Cette thèse vise à rendre possible l’utilisation des véhicules sous-marins autonomes (AUVs) dans l’inspection visuelle des structures offshore. Deux tâches sont identifiées: le suivi des structures rectilignes et la stabilisation devant les cibles planaires. Les AUVs complétement actionnés et équipés d'une centrale inertielle, un DVL, un altimètre et une caméra vidéo sont visés. La dynamique en 6 d.d.l. d'un AUV est rappelée. L'architecture de contrôle reflétant la structure en cascade de la dynamique est choisie. Une boucle interne asservie la vitesse du véhicule à la consigne et une boucle externe calcule la vitesse de référence à partir des informations visuelles. Le suivi de pipe est assuré par l'asservissement visuel 2D qui calcule la vitesse de référence à partir des bords du pipeline détectés dans l’image. La convergence globale asymptotique et localement exponentielle de la position, de l’orientation et de la vitesse sont obtenues. Le contrôleur de stabilisation utilise la matrice d’homographie. Seule la connaissance imprécise de l’orientation de la cible est nécessaire. L’information cartésienne de la profondeur de la cible est estimée à l’aide d’un observateur. La convergence quasi-globale et localement exponentielle de ce contrôleur est démontrée. Afin de tester ces méthodes un simulateur a été développé. Des images de synthèse de haute-fidélité sont générées à partir de simulateur Morse. Elles sont traitées en temps réel à l’aide de la bibliothèque OpenCV. Un modèle Simulink calcule la dynamique complète des 6 d.d.l. du véhicule simulé. Des résultats détaillés sont présentés et mettent en avant les résultats théoriques obtenus<br>This thesis deals with a control system for a underwater autonomous vehicle given a two consequent tasks: following a linear object and stabilisation with respect to a planar target using an on-board camera. The proposed solution of this control problem takes advantage of a cascading nature of the system and divides it into a velocity pilot control and two visual servoing schemes. The serving controllers generate the reference velocity on the basis of visual information; line following is based on binormalized Pluecker coordinates of parallel lines corresponding to the pipe contours detected in the image, while the stabilisation relies on the planar homography matrix of observed object features, w.r.t. the image of the same object observed at the desired pose. The pilot, constructed on the full 6 d.o.f. nonlinear model of the AUV, assures that the vehicle’s linear and angular velocities converge to their respective setpoints. Both image servoing schemes are based on minimal assumptions and knowledge of the environment. Validation is provided by a high-fidelity 6 d.o.f. dynamics simulation coupled with a challenging 3D visual environment, which generates images for automatic processing and visual servoing. A custom simulator is built that consist of a Simulink model for dynamics simulation and the MORSE robot and sensor simulator, bound together by ROS message passing libraries. The OpenCV library is used for real-time image processing. Methods of visual data filtering are described. Thus generated experimental data is provided that confirms the desired properties of the control scheme presented earlier
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Rogers, Maile Anne. "Water Vapor Movement in Freezing Aggregate Base Materials." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4013.
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The objectives of this research were to 1) measure the extent to which water vapor movement results in water accumulation in freezing base materials; 2) evaluate the effect of soil stabilization on water vapor movement in freezing base materials; 3) determine if the corresponding changes in water content are sufficient to cause frost heave during winter; 4) determine if the corresponding changes in water content are sufficient to cause reductions in stiffness during spring; 5) evaluate relationships between selected material properties, freezing conditions, and the occurrence and impact of water vapor movement; and 6) numerically simulate heat and water movement in selected pavement design scenarios. The research involved extensive laboratory and field testing, statistical analyses, and numerical modeling. The results of the laboratory testing, which included gradations, Atterberg limits, soil classifications, specific gravity and absorption values, electrical conductivity values, moisture-density relationships, soil-water characteristic curves, moisture-stiffness curves, hydraulic conductivity values, and frost susceptibility assessments, were used to characterize each material and enable subsequent statistical analyses. Testing of both treated and untreated materials enabled investigation of a wide variety of material properties. The results of the field testing, which included temperature, moisture content, water potential, elevation, and stiffness data over time, provided the basis for comparing pavement sections with and without capillary barriers and established the framework for numerical modeling. In a pavement section with a capillary barrier underlying the base layer, water vapor movement from the subgrade through the capillary barrier may be expected to increase the water content of the base layer by 1 to 3 percent during a typical winter season in northern Utah for base materials similar to those studied in this research. During winter, cold temperatures create an ideal environment for water vapor to travel upward from the warm subgrade soil below the frost line, through the capillary barrier, and into the base material. Soil stabilization can lead to increased or decreased amounts of water vapor movement in freezing base materials depending on the properties of the stabilized soil, which may be affected by gradation, mineralogy, and stabilizer type and concentration. Accumulation of water from long-term water vapor movement into frost-susceptible base materials underlain by a capillary barrier can lead to frost heave of the base layer as it approaches saturation, as water available in the layer can be redistributed upwards to create ice lenses upon freezing. However, the incremental increase in total water content that may occur exclusively from water vapor movement during a single winter season in northern Utah would not be expected to cause measurable increases in thaw weakening of the base layer during spring. Because water in a base layer overlying a capillary barrier cannot drain until nearly reaching positive pore pressures, the base layer will remain indefinitely saturated or nearly saturated as demonstrated in this research. For materials similar to those studied in this research, potentially important material properties related to the occurrence of water vapor movement during freezing include dry density, percent of material finer than the No. 200 sieve, percent of material finer than 0.02 mm, apparent specific gravity, absorption, initial water content, porosity, degree of saturation, hydraulic conductivity, and electrical conductivity. The rate at which water vapor movement occurs is also dependent on the thermal gradient within the given material, where higher thermal gradients are associated with higher amounts of water vapor movement. The numerical modeling supported the field observations that the capillary barrier effectively trapped moisture in the overlying base material, causing it to remain saturated or nearly saturated throughout the monitoring period. Only non-frost-susceptible aggregate base materials should be specified for use in cold climates in conjunction with capillary barriers, and the base material in this case should be assumed to remain in a saturated or nearly saturated condition during the entire service life of the pavement. Further study is recommended on water vapor movement in freezing aggregate base materials.
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Wells, David Reese. "Stabilization of POD-ROMs." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/52960.
Full textAbstract:
This thesis describes several approaches for stabilizing POD-ROMs
(that is, reduced order models based on basis functions derived from the proper
orthogonal decomposition) for both the CDR (convection-diffusion-reaction)
equation and the NSEs (Navier-Stokes equations). Stabilization is necessary
because standard POD-ROMs of convection-dominated problems usually display
numerical instabilities.
The first stabilized ROM investigated is a streamline-upwind
Petrov-Galerkin ROM (SUPG-ROM). I prove error estimates for the SUPG-ROM and
derive optimal scalings for the stabilization parameter. I test the SUPG-ROM
with the optimal parameter in the numerical simulation of a convection-dominated
CDR problem. The SUPG-ROM yields more accurate results than the standard
Galerkin ROM (G-ROM) by eliminating the inherent numerical artifacts (noise) in
the data and dampening spurious oscillations.
I next propose two regularized ROMs (Reg-ROMs) based on ideas from large
eddy simulation and turbulence theory: the Leray ROM (L-ROM) and the
evolve-then-filter ROM (EF-ROM). Both Reg-ROMs use explicit POD spatial
filtering to regularize (smooth) some of the terms in the standard G-ROM. I
propose two different POD spatial filters: one based on the POD projection and a
novel POD differential filter. These two new Reg-ROMs and the two spatial
filters are investigated in the numerical simulation of the three-dimensional
flow past a circular cylinder problem at Re = 100. The numerical results
show that EF-ROM-DF is the most accurate Reg-ROM and filter combination and the
differential filter generally yields better results than the projection filter.
The Reg-ROMs perform significantly better than the standard G-ROM and decrease
the CPU time (compared against the direct numerical simulation) by orders of
magnitude (from about four days to four minutes).<br>Ph. D.
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Liu, Chao, and 劉超. "On the stabilization and related problems of beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B45015454.
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Hamache, Djawad. "Modélisation et commande d'un réseau électrique continu." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC027.
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Les travaux de cette thèse portent sur l’investigation d’approches de commande permettant d’aborder la stabilisation des réseaux électriques continus.En effet les interactions entre les différents éléments du réseau : sources, filtres et charges peuvent conduire à son instabilité. Ces interactions peuvent simplement être mises en évidence au moyen d’un cas d’étude de réseau contenant des charges à puissance constante (CPLs). Pour pallier les problèmes induits par les interconnexion de ces éléments, différentes approches de commande ont été évaluées afin d’assurer la stabilité et maintenir les performances du réseau dans tout son domaine de fonctionnement. La première approche concerne la synthèse par la méthode « backstepping », qui nécessite de reformuler le modèle du réseau sous une structure cascade. Toutefois, selon le moyen d’action disponible, cette approche peut se révéler difficile à mettre en œuvre lorsque plusieurs charges à puissance sont présentes. La deuxième approche fondée sur les méthodes de passivité synthétisant une commande par « injection d’amortissement ». Cette commande permet d’ajouter un amortisseur virtuel aux filtres d’entrée des charges afin de compenser l’effet d’impédance négative introduit par la CPL. Enfin, pour proposer une solution intégrée permettant de mieux répondre à la problématique de la stabilisation du réseau, une approche fondée sur une représentation sous forme multimodèle du système a été étudiée. Cette méthode permet aussi d’envisager la synthèse d’un observateur lorsque l’ensemble du vecteur d’état n’est pas mesuré. Afin de valider et de comparer les performances des différentes méthodes de commande, un réseau électrique DC type caractérisé par deux charges de nature différente et d’un organe de stockage réversible, a été défini où le seul actionneur considéré est l’organe de stockage utilisé ici dans un contexte de stabilisation<br>This work investigates control approachs for the stabilization of DC electrical networks. Interactions between different elements of a network i.e, sources, filters and loads may lead to instability. These interactions may be identified by styding a network containing constant power loads (CPLs). To address the problems caused by the interconnection of these elements, different control methods could be evaluated to ensure the stability and maintain network performances throughout its operating range. The first approach uses « backstepping »method, which requiers cascade structure models. However, according to available control input, this approach may be difficult to implement when multiple power loads are present. The second approach is based on passivity theory using « damping injection » control. This control law adds a virtual damper to the input filter loads in order to compensate the negative impedance effect introduced by the CPL. Finally, in order to provide an integrated solution for the problem of network stabilization, an approach based on multiple model representation of the system was investigated. This method also allows to consider the design of an observer when the entire state vector is not measured. To validate and compare the performance of different control methods, a DC electrical network characterized by two loads of different natures and a reversible storage device was defined. The storage device is the only control input considered for the stabilization
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Gavant, Fabien. "Contribution à des architectures de stabilisation d'images basées sur la perception visuelle et la physiologie du tremblement humain." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENT061/document.
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Avec l’intégration des appareils photos dans les appareils mobiles, leur démocratisation et la réduction de la taille de l’imageur, de l’optique et de la taille pixels, les photos sont de plus en plus sujettes au flou de bougé dû aux tremblements de la main. À cette tendance s’ajoute un accroissement constaté dans l’exigence de qualité d’image de la part des utilisateurs. Pour réduire ce flou, des systèmes de stabilisation d’image ont été développés. Néanmoins ceux-ci ne permettent pas de garantir la qualité de netteté des images et souffrent parfois d’une intégration limitée. En réponse à ces limitations, ces travaux de recherche proposent, d’une part, un modèle de tremblement physiologique permettant de simuler de manière fidèle les flous de bougé et, d’autre part, une étude sur la perception visuelle du flou permettant le développement d’une métrique de qualité. Enfin des architectures de stabilisations, exploitant ces nouveaux outils, sont proposées. Ces nouvelles architectures permettent de réduire le nombre de composants externes ainsi que de garantir la netteté des images stabilisées<br>With the integration of cameras in mobile devices, their democratization and the reduction of the imager’s size, the optical system dimensions and the pixels miniaturization, the photos become more and more subject to motion blur due to the hand tremor. In addition, the requirements in terms of image quality become higher and higher. Hence, in order to reduce this blur, several image stabilization systems have been developed. Nevertheless, they cannot guarantee the sharpness quality of resulting images and in some cases, they show integration difficulties. In order to overcome these limitations, the research work presented in this thesis proposes, first of all, a physiological tremor model that aims to simulate realistic camera shake and secondly, presents a study on visual perception of blur. This study enables the development of a quality metric. Finally, stabilization algorithms and architectures exploiting these new tools are presented. These new architectures reduce the number of external components and ensure sharp stabilized images
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Vasudevamurthy, Madhusudan. "Betaine analogues and related compounds for biomedical applications." Thesis, University of Canterbury. Chemical and Process Engineering, 2006. http://hdl.handle.net/10092/1096.
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Living cells accumulate compensatory solutes for protection against the harmful effects of extreme environmental conditions such as high salinity, temperature and desiccation. Even at high concentrations these solutes do not disrupt the normal cellular functions and at times counteract by stabilizing the cellular components. These properties of compensatory solutes have been exploited for stabilizing proteins and cells in vitro. Betaines are widespread natural compensatory solutes that have also been used in other applications such as therapeutic agents and polymerase chain reaction (PCR) enhancers. Some biomedical applications of novel synthetic analogues of natural betaines were investigated. Natural compensatory solutes are either dipolar zwitterionic compounds or polyhydroxyl compounds, and the physical basis of compensation may differ between these, so one focus was on synthetic betaines with hydroxyl substituents. The majority of the synthetic solutes stabilized different model proteins against stress factors such as high and low temperatures. The presence of hydroxyl groups improved protection against desiccation. The observed stabilization effect is not just on the catalytic activity of the enzyme, but also on its structural conformation. Synthetic compensatory solutes have a potential application as protein stabilizers. Dimethylthetin was evaluated as a therapeutic agent and found to be harmful in a sheep model. However, from the study we were able to generate a large-animal continuous ambulatory peritoneal dialysis (CAPD) model and showed that glycine betaine could be added to the dialysis fluid in chronic renal failure. Some synthetic compensatory solutes reduce the melting temperatures of DNA better than most natural solutes. Synthetic solutes were identified that have potential to enhance PCR and could replace some reagents marketed by commercial suppliers. Density, viscosity and molecular model data on the solutes showed correlations with the biochemical effects of the solutes, but no physical measurements were found that reliably predicted their potential for biotechnological applications.
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Zhu, Kunping. "Stability analysis and stabilization of fuzzy state space models." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980973309.
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Xu, Rong. "Optimal sliding mode control and stabilization of underactuated systems." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1185815577.
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Mohamed, Ramadan Haitham Saad. "Non-linear control and stabilization of VSC-HVDC transmission systems." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112046/document.
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L'intégration des liaisons à courant continu dans les systèmes électriques permet d’accroitre les possibilités de pilotage des réseaux, ce qui permet d’en améliorer la sûreté et de raccorder de nouveaux moyens de production. Pour cela la technologie VSC-HVDC est de plus en plus plébiscitée pour interconnecter des réseaux non synchrones, raccorder des parcs éoliens offshore, ou contrôler le flux d’énergie notamment sur des longues distances au travers de liaisons sous-marines (liaison NorNed). Les travaux de cette thèse portent sur la modélisation, la commande non-linéaire et la stabilisation des systèmes VSC–HVDC, avec deux axes de travail. Le premier se focalise sur la conception et la synthèse des lois de commandes non-linéaires avancées basées sur des systèmes de structures variables (VSS). Ainsi, les commandes par modes glissants (SMC) et le suivi asymptotique de trajectoire des sorties (AOT) ont été proposées afin d’assurer un degré désiré de stabilité en utilisant des fonctions de Lyapunov convenables. Ensuite, la robustesse de ces commandes face à des perturbations et/ou incertitudes paramétriques a été étudiée. Le compromis nécessaire entre la robustesse et le comportement dynamique requis dépend du choix approprié des gains. Ces approches robustes, qui sont facile à mettre en œuvre, ont été appliquées avec succès afin d’atteindre des performances dynamiques élevées et un niveau raisonnable de stabilité vis-à-vis des diverses conditions anormales de fonctionnement, pour des longueurs différentes de liaison DC. Le deuxième vise à étudier l’influence de la commande du convertisseur VSC-HVDC sur l'amélioration de la performance dynamique du réseau de courant alternatif en cas d’oscillations. Après une modélisation analytique d’un système de référence constitué d’un groupe connecté à un convertisseur VSC-HVDC via un transformateur et une ligne, un contrôleur conventionnel simple PI est appliqué au niveau du convertisseur du système pour agir sur les oscillations rotoriques de la machine synchrone. Cette commande classique garantie une amélioration acceptable des performances dynamiques du système; surtout pour l'amortissement des oscillations de l'angle de puissance de la machine synchrone lors de défauts<br>The integration of nonlinear VSC-HVDC transmission systems in power grids becomes very important for environmental, technical, and economic reasons. These systems have enabled the interconnection of asynchronous networks, the connection of offshore wind farms, and the control of power flow especially for long distances. This thesis aims the non-linear control and stabilization of VSC-HVDC systems, with two main themes. The first theme focuses on the design and synthesis of nonlinear control laws based on Variable Structure Systems (VSS) for VSC-HVDC systems. Thus, the Sliding Mode Control (SMC) and the Asymptotic Output Tracking (AOT) have been proposed to provide an adequate degree of stability via suitable Lyapunov functions. Then, the robustness of these commands has been studied in presence of parameter uncertainties and/or disturbances. The compromise between controller’s robustness and the system’s dynamic behavior depends on the gain settings. These control approaches, which are robust and can be easily implemented, have been applied to enhance the system dynamic performance and stability level in presence of different abnormal conditions for different DC link lengths. The second theme concerns the influence of VSC-HVDC control on improving the AC network dynamic performance during transients. After modeling the Single Machine via VSC-HVDC system in which the detailed synchronous generator model is considered, the conventional PI controller is applied to the converter side to act on damping the synchronous machine power angle oscillations. This simple control guarantees the reinforcement of the system dynamic performance and the power angle oscillations damping of the synchronous machine in presence of faults
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Zhu, Kunping [Verfasser]. "Stability Analysis and Stabilization of Fuzzy State Space Models / Kunping Zhu." Aachen : Shaker, 2006. http://d-nb.info/1166513394/34.
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Veselý, Jiří. "Elektronicky přeladitelný harmonický oscilátor." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218599.
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This masters project describes properties and primary parameters of active function blocks (OPA, VCA, OTA, CFA, CC) usable in construction of harmonic oscillators. Basic principles of harmonic generators, especially feedback oscillators, are introduced. In next section are presented five particular schematics of harmonic tuned oscillators. For this oscillators are indicated basic formulas, essential qualities performed by simulations and results of sensitivity and tolerance analysis. In the last part of diploma thesis there are selected three circuits which are made and their features are measured.
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Wable, Milind Vishnu. "Investigation of hypothesized anaerobic stabilization mechanisms in biological phosphorus removal systems." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/27531.
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Musa, Zulkarnain 1964. "An accelerated conjugate direction procedure for slope stability analysis." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276912.
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CSLIP2 (De Natale, 1987) is the only slope stability program that utilizes a "direction set" optimization routine in its search for the minimum safety factor. However, CSLIP2 which employs Powell's Conjugate Direction Method permits only the horizontal and vertical directions (x and y) to be used as the initial direction set. The efficiency of the existing search routine is improved by replacing the x-y coordinate directions with initial directions that are parallel to and perpendicular to the principal axis of the safety factor contours.
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Fedorková, Lucie. "Metody stabilizace nestabilních řešení diskrétní logistické rovnice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400443.
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Diplomová práce pojednává o stabilizaci diskrétního logistického modelu pomocí několika řídících metod. Je zde provedena především stabilizace rovnováh, 2-periodických cyklů a 3-periodických cyklů. Ke stabilizaci systému je využito proporčního zpětně-vazebního řízení, zpětně-vazebního řízení s časovým zpožděním a řízení založeného na predikci. U každé metody je diskutovaná stabilizační množina pro řídící zesilovač spolu s oblastmi stability pro odpovídající kontrolovaná řešení. Všechny teoretické výsledky jsou ilustrovány grafickými interpretacemi v softwaru MATLAB. Podpůrné výpočty jsou provedeny pomocí softwaru Maple.
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Laveau, Marie. "Asynchronous Self-Stabilizing Stable Marriage." Electronic Thesis or Diss., université Paris-Saclay, 2020. http://www.theses.fr/2020UPASG008.
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Le Problème du Mariage Stable (SMP) est un problème d'appariement où les participants ont des préférences à propos de leurs partenaires potentiels.L'objectif est de trouver un appariement optimal (stable dans un sens) au regard des préférences. Ce type d'appariement a de très nombreuses applications comme les affectations d'étudiants à des universités (APB ou ParcourSup), celles des internes en médecine aux hôpitaux, les choix des donneurs pour les patients en attente d'organe, la mise en rapport des taxis et de leurs clients ou encore la diffusion de contenu sur Internet.Certaines de ces applications peuvent être traitées de manière centralisée tandis que d'autres, de par leur nature distribuée et la complexité de leurs données, nécessitent un traitement différent. Par exemple, dans le contexte du Cloud-Computing, des machines virtuelles sont émulées par des machines réelles situées sur la terre entière.Un algorithme centralisé causerait des délais considérables dans les prises de décision tout en étant sensible aux défaillances, ce qui est inconcevable pour un service supposé disponible à tout moment. D'un autre côté, chaque fois que des personnes sont impliquées dans un appariement, elles ont le droit de garder privées leurs données personnelles et en particulier leur liste de préférences, qui peut contenir des informations sensibles.Par conséquent, il est souhaitable que les listes de préférence des personnes ne soient jamais transmises sur Internet, et encore moins rassemblées pour un traitement centralisé.C'est pourquoi la distribution, la tolérance aux défaillances (par auto-stabilisation) et la confidentialité sont les trois principaux mots-clés de cette thèse.Dans ce contexte, nous proposons deux solutions distribuées auto-stabilisantes. De telles solutions tolèrent les défaillances (e.g., corruptions de mémoire ou de messages) transitoires (ou de courte durée) de n'importe quels noeuds.La confidentialité des listes de préférences est garantie par les deux algorithmes que nous proposons : les listes ne sont pas partagées et seules des queries binaires et leurs réponses sont échangés.Une différence entre ces algorithmes est le modèle de communication : le premier algorithme utilise le modèle à état tandis que le second algorithme utilise le modèle à registre plus général.Dans les deux modèles, les exécutions se déroulent par pas atomiques et un démon (démon distribué inéquitable) exprime la notion d'asynchronisme.Avec ce démon, le temps de stabilisation peut être borné en terme de moves (pas locaux).Cette mesure de complexité permet d'évaluer avec précision la puissance de calcul nécessaire ou l'énergie dissipée par les exécutions de l'algorithme.Ce n'est pas le cas quand la complexité est évaluée en rounds, puisque le nombre de moves effectués dans un round n'est pas nécessairement borné.Le premier algorithme, basé sur la méthode centralisée de Ackermann et al. (SICOMP' 2011), résout le SMP en O(n⁴) moves.Il permet également de résoudre certaines variantes du SMP telles que le mariage stable avec indifférence, avec partenaires inacceptables, etc.Le point de départ du deuxième algorithme est le schéma de détection locale/correction globale de Awerbuch et al. (DA' 1994) : un algorithme non auto-stabilisant (devant être initialisé) mais avec la propriété d'être vérifiable localement peut être combiné avec un détecteur et un algorithme de réinitialisation.De cette combinaison résulte un algorithme auto-stabilisant.Malheureusement, la définition de la vérifiabilité locale de DA '1994 ne s'applique pas à notre cas (en particulier en raison du démon inéquitable).Nous proposons donc une nouvelle définition.De plus, nous concevons un algorithme de réinitialisation (reset) asynchrone, distribué et auto-stabilisant.L'algorithme résultant résout le SMP en θ(n)² moves<br>The Stable Marriage Problem (SMP) is a matching problem where participants have preferences over their potential partners.The objective is to find a matching that is optimal (stable in certain sens) with regard to these preferences.This type of matching has a lot of widely used applications such as the assignment of children to schools, interns to hospitals, kidney transplant patients to donors, as well as taxi scheduling or content delivery on the Internet.Some applications can be solved in a centralized way while others, due to their distributed nature and their complex data, need a different treatment.For example, when applying this problem to the Cloud-Computing context, virtual machines are emulated by real machines located all over the world.A centralized algorithm would cause unbearable delays and be sensible to failures, which is inconceivable for a service meant to be available at any time.On the other hand, when humans are to be matched or involved in a matching, they have the right to keep their personal data private and in particular their list of preferences.Consequently, the preference lists should not be transmitted on the Internet, and even less gathered for a centralized treatment.This is why, distribution, fault-tolerance (by self-stabilization) and privacy are the three main keywords of this thesis.In order to handle these challenges, we provide two distributed self-stabilizing solutions.Such solutions tolerate transient (or short-lived) failures (e.g., memory or message corruptions) of any nodes.The privacy of the preference lists is guaranteed by the two proposed algorithms: lists are not shared, only some binary queries and responses are transmitted.One of the differences between the two algorithms is the communication model: the first algorithm uses the state model while the second algorithm uses the more general register model.In both models, executions proceed in atomic steps and a daemon (distributed unfair daemon) conveys the notion of asynchrony.Under this daemon, the stabilization time can be bounded in term of moves (local computations).This complexity metrics allows to evaluate the necessary computational power or the energy consumption of the algorithm's executions.This is not the case when the stabilization time is measured in rounds since an unbounded number of moves may be executed during a round.The first algorithm, based on the centralized method of Ackermann et al. (SICOMP' 2011), solves the problem in O(n⁴) moves.It also solves some variants of SMP such as the Stable Marriage with indifference, with unacceptable partners, etc.The starting point of the second algorithm is the local detection/global correction scheme of Awerbuch et al. (DA' 1994): a non-self-stabilizing algorithm (with initialization) that satisfies the property of local checkability can be combined with a detector and a reset algorithms.The result of this composition is a self-stabilizing version of the given algorithm.Unfortunately, local checkability definition of DA '1994 does not apply to our case (in particular due to the unfair daemon).Consequently, we propose a new definition.Furthermore, we design a distributed self-stabilizing asynchronous reset algorithm. Using it, the resulting composed algorithm solves SMP in θ(n)² moves in a self-stabilizing way
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Shrestha, Rakshya. "Deep soil mixing and predictive neural network models for strength prediction." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607735.
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Liu, Ying, and 劉影. "Limit equilibrium methods for slope stability analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B42576684.
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Samoylova, M. "STABILIZATION OF BLOCH OSCILLATIONS OF ULTRACOLD ATOMS IN A RING CAVITY." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/274589.
Full textAbstract:
The work presented in this thesis is dedicated to studies of stabilization of Bloch oscillations of ultracold atoms in a one-dimensional vertical optical lattice under the influence of the gravitational force. The atoms simultaneously interact with both the lattice potential and a unidirectionally pumped optical ring cavity whose vertical arm is collinear with the optical lattice. In the proposed scheme, the atoms not only exchange photons between the optical lattice laser beams, but also collectively scatter light from the pump into the reverse cavity mode.
The initial investigation of the system without the cavity allows understanding of the importance of the perfectly adiabatic atomic motion in the observation of stable Bloch oscillations and how easily the adiabaticity can be broken due to a very fast switch-on of the lattice or its amplitude and phase modulation. Under certain parameter regimes, adding the ring cavity to the system provides a surprisingly positive feedback on the atomic dynamics. It is found that, while acting back on the atoms, the cavity field establishes a mode-locking mechanism which assists adiabatic rapid passages between adjacent momentum states. Thus, the cavity-induced feedback mechanism enforces the adiabaticity of the process and reveals a regime where the Bloch oscillations are self-synchronized for long times. This stabilization technique is shown to steer the atoms to the lowest Bloch band preventing the problem of interband tunneling. A demonstration is also made of the ability of the system to stabilize the atomic Bloch oscillations against technical amplitude or phase noise and even suppress dephasing due to the atom-atom interactions.
Furthermore, the response of the system to the atomic motion is generated in the form of perfectly detectable periodic bursts of light emitted into the counter-propagating cavity mode. Thus, the system offers a continuous and reliable non-destructive method to monitor the Bloch oscillations dynamics without perturbing their periodicity by detecting the scattered light transmitted through the cavity. All features studied in this work may be crucial for future improvements of the design of atomic gravimeters based on recording Bloch oscillations.
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Boeckmann, Andrew Z. "Load transfer in micropiles for slope stabilization from tests of large-scale physical models." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4633.
Full textAbstract:
Thesis (M.S.) University of Missouri-Columbia, 2006.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 22, 2007) Includes bibliographical references.
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Savard, Marielle. "Impact of Canadian stabilization programs on pork exports to the United States." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55675.
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