Dissertations / Theses on the topic 'Spatial stability analysis'
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FLORES, EMERSON ALEX FIGUEROA. "PROBABILISTIC ANALYSIS OF SLOPE STABILITY CONSIDERING SPATIAL VARIABILITY OF SOIL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=12093@1.
Full textFreqüentemente as análises de estabilidade de taludes são feitas por métodos determinísticos, nos quais é obtido um Fator de Segurança (FS). Estes métodos não quantificam as incertezas existentes nas variáveis de entrada (parâmetros de resistência) na análise. Tampouco mostram detalhes sobre qual variável afeta mais o resultado. Os métodos probabilísticos permitem superar estes problemas. A presente pesquisa tem como objetivo comparar dois métodos probabilísticos geralmente utilizados (Estimativas Pontuais e Segundo Momento). Três projetos utilizados comumente na geotecnia são analisados: barragem de rejeitos, talude de solo e aterro sobre argila mole.Um aspecto importante na análise probabilística é a quantificação adequada do desvio padrão. É sabido que as propriedades dos solos mostram uma correlação no espaço, pelo que o desvio padrão calculado por métodos clássicos da estatística é superestimado em comparação ao valor real no campo. El-Ramly (2001) desenvolveu uma metodologia para o cálculo da probabilidade de ruptura considerando a correlação espacial das propriedades do solo. Esta metodologia é de difícil aplicação prática. Serão, portanto, avaliadas na presente pesquisa as técnicas geralmente usadas de probabilidade e estabilidade de taludes, juntamente com um fator de correção proposto por Vanmarcke (1977a). Estas técnicas de probabilidade de estabilidade de taludes são factíveis de serem utilizadas junto com este fator de correção. Verificou-se que o Método de Segundo Momento é de mais fácil utilização, e portanto adequado para emprego em projetos geotécnicos.
The analysis of slope stability is often determined by deterministic methods, in which a Factor of Security (FS) is obtained. These methods do not quantify the uncertainty in the input variables (strength parameters). Neither these methods show details which variable affects mostly the outcome results. The probabilistic methods allow overcoming these restrictions. This study aims at comparing two probabilistic methods of general use (Point Estimates and First Order Second Moment). Three projects commonly used in geotechnical engineering are analyzed: tailings dam, slope soil and embankment on soft clay. An important aspect of the probabilistic analysis is the proper quantification of the standard deviation. It is known that the soil properties show a correlation in space, so the standard deviation, calculated by traditional methods of statistics, is overestimated when compared to the real field value. El-Ramly (2001) developed a methodology for calculating the probability of failure considering the spatial correlation of the soil properties. This methodology is difficult to apply in practice. The present study will therefore evaluate the techniques generally used in probability of failure of slopes. These probability techniques applied to slope stability can be used together with a correction factor proposed by Vanmarcke (1977b). The Second Moment Method was found to be easier to use, and therefore more suitable for geotechnical projects.
MULLER, ANDRE LUIS. "NUMERICAL BOREHOLE STABILITY ANALYSIS CONSIDERING SPATIAL VARIABILITY AND FLUID-MECHANICAL COUPLING." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10457@1.
Full textEm geral, a análise da estabilidade e a análise das respostas de poços de petróleo são realizadas de forma determinística em relação às propriedades mecânicas e hidráulicas do meio rochoso. No entanto, sabe- se que os meios rochosos e em particular rochas sedimentares, podem mostrar um considerável grau de heterogeneidades, em micro, meso e macro-escala. Essas heterogeneidades produzem variabilidade espacial nas propriedades mecânicas e hidráulicas dos meios rochosos. Essa variabilidade mostra em geral um caráter espacial pronunciado. O presente estudo propõe o desenvolvimento de procedimentos de análise numérica, utilizando elementos finitos, de processos fluido mecânicos acoplados, monofásicos e bifásicos, que levem em conta a variabilidade espacial de propriedades hidráulicas e mecânicas e a variabilidade das condições iniciais de tensões e poro pressões. Nesse estudo, empregam-se os procedimentos numéricos desenvolvidos em duas fases distintas. Na análise probabilística da estabilidade de poços e na análise probabilística das respostas dos poços durante a produção, considerando o acoplamento fluido mecânico com fluxo bifásico.
In general, borehole stability analysis and borehole response analysis are carried out considering that both hydraulic and mechanical parameters of the rock mass are deterministic. However, it is a well known fact, that rock masses and in particular sedimentary rock masses may show a considerable degree of heterogeneity, in micro, meso and macro scale. These heterogeneities produce spatial variability in mechanical and hydraulic properties of the rock medium. This variability can be very pronounced. The present work proposes the development of numerical analysis procedures, using finite elements, in order to analyze single and two phases flow, coupled fluid mechanical processes that take into account the spatial variability of hydraulic and mechanical properties and the variability of the initial stresses and pore pressures. In this study, the developed numerical procedures are used in two distinct phases. In the borehole stochastic stability analysis and in the borehole stochastic response analysis during the production, considering fluid mechanical coupling and two phase flow.
Burke, Tommy. "Evaluation of visualisations of geographically weighted regression, with perceptual stability." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/15680.
Full textWu, Kai. "Vibration and Stability of Continuous Systems| New Parametric Instability Analysis and Spatial Discretization Method." Thesis, University of Maryland, Baltimore County, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10841201.
Full textParametric instability in a system is caused by periodically varying coefficients in its governing differential equations. Parametric instability regions of a second-order non-dispersive distributed structural system in this work are obtained using the wave solution and the fixed point theory without spatially discretizing the governing partial differential equation. The parametric instability regions are classified as period-1 and period- i (i > 1) instability regions, where the former is analytically obtained, and the latter can be numerically calculated using bifurcation diagrams. The parametric instability phenomenon is characterized by a bounded displacement and an unbounded vibratory energy, due to formation of infinitely compressed shock-like waves. Parametric instability in a taut string with a periodically moving boundary is then investigated. The free linear vibration of the taut string is studied first, and three corresponding nonlinear models are introduced next. It is shown that the responses and vibratory energies of the nonlinear models are close to those of the linear model, which indicates that the parametric instability in the linear model can also exist in the nonlinear models.
A new global spatial discretization method for one- and two-dimensional continuous systems is investigated. General formulations for one- and two-dimensional systems that can achieve uniform convergence are established, whose displacements are divided into internal terms and boundary-induced terms. For one-dimensional systems, natural frequencies, mode shapes, harmonic steady-state responses, and transient responses of a rod and a tensioned Euler-Bernoulli beam are calculated using the new method and the assumed modes method, and results are compared with those from exact analyses. The new method gives better results than the assumed modes method in calculating eigensolutions and responses of a system, and it can use sinusoidal functions as trial functions for the internal term rather than possibly complicated eigenfunctions in exact analyses. For two-dimensional systems, natural frequencies and dynamic responses of a rectangular Kirchhoff plate that has three simply-supported boundaries and one free boundary with an attached Euler-Bernoulli beam are calculated using both the new method and the assumed modes method, and compared with results from the finite element method and the finite difference method, respectively. Advantages of the new method over local spatial discretization methods are fewer degrees of freedom and less computational effort, and those over the assumed modes method are better numerical property, a faster calculation speed, and much higher accuracy in calculation of high-order spatial derivatives of the displacement.
Nardelli, P. H. (Pedro Henrique Juliano). "Analysis of the spatial throughput in interference networks." Doctoral thesis, Oulun yliopisto, 2013. http://urn.fi/urn:isbn:9789526201818.
Full textTiivistelmä Tässä työssä tutkitaan häiriörajoitteisten langattomien verkkojen tila-alueen suorituskykyä, olettaen verkkosolmujen sijoittuvan 2-ulotteisen Poissonin pisteprosessin mukaisesti, sekä olettaen lähettimien hyödyntävän Gaussisia pisteestä-pisteeseen -koodeja. Suorituskykyanalyysi pohjautuu stokastiseen geometriaan, tietoliikenneteoriaan sekä informaatioteoriaan. Suljetun muodon suorituskyky-yhtälöitä hyödyntäen arvioidaan suorityskykymetriikoita eri skenaarioissa. Työn aluksi esitetään uusi monihyppyverkkojen informaatiotehokkuuteen perustuva metriikka. Sen avulla voidaan tutkia onko tehokkaampaa käyttää useita lyhyen hypyn linkkejä vai pienempää määrää pidempien hyppyjen linkkejä. Yhden hypyn verkoissa tutkitaan mediaanpääsyprotokollia asynkronisissa verkoissa pakettien uudelleenlähetykseen perustuen ja verrataan tätä synkroniseen lähetykseen ilman vapaan kanavan tunnistusmekanismia. Työssä tutkitaan myös linkin efektiivisen suorituskyvyn ja verkon tila-alueen suorituskyvyn optimointia, jotta sopiva yhdistelmä mediaan pääsyn todennäköisyydelle, koodausnopeudelle ja uudelleenlähetysten maksimilukumäärälle löytyisi ja samalla maksimoisi jokaisen käytetyn metriikan ehdollistettuna paketin menetyksille ja jonon stabiilisuudelle. Lisäksi arvioidaan maksimaalista odotettavaa nettosiirtonopeutta tietyllä alueella, eli tila-alueen kapasiteettia, Gaussimaisen pisteestä-pisteeseen koodien kapasiteettialueisiin perustuen kahta eri dekoodaussääntöä hyödyntäen: (i) olettaen häiriön olevan kohinaa tai (ii) ilmaisemalla voimakkaimmat häiriösignaalit ja olettaen muiden olevan kohinaa. Jälkimmäinen osoittautui tehokkaammaksi menetelmäksi. Työssä osoitetaan myös, että samalla dekoodaussäännöllä ja verkon tiheydellä tila-alueen kapasiteetin saavuttava menetelmä on aina tehokkaampi kuin tavanomainen tila-alueen suorituskykyyn perustuva kiinteän siirtonopeuden menetelmä. Saavutettujen tulosten valossa työssä esitetään yleisiä suunnittelumenetelmiä mukautuville ad hoc -algoritmeille, joiden avulla voidaan parantaa tiedonsiirtoa häiriörajoitteisissa verkoissa, ehdollistettuna verkon solmujen sisäisille ja ulkoisille rajoitteille
Lutz, Eric Robert. "Spatial and temperal analysis of snowpack strength and stability and environmental determinants on an inclined, forest opening." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/lutz/LutzE0509.pdf.
Full textBressan, Nicola. "Spatial and temporal analysis of soil moisture patterns in an Alpine site in north Italy." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textDiaz, Diaz Eliecer Rodrigo. "Hierarchical spatial structure and levels of resolution of intertidal grazing and their consequences on predictability and stability at small scales." Thesis, Rhodes University, 2009. http://hdl.handle.net/10962/d1005393.
Full textPeltonen, Joanna. "Effective Spatial Mapping for Coupled Code Analysis of Thermal–Hydraulics/Neutron–Kinetics of Boiling Water Reactors." Doctoral thesis, KTH, Kärnkraftsäkerhet, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122088.
Full textQC 20130516
Peltonen, Joanna. "Development of effective algorithm for coupled thermal-hydraulics : neutron-kinetics analysis of reactivity transient." Licentiate thesis, Stockholm : Skolan för teknikvetenskap, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11033.
Full textBagheri, Shervin. "Stability analysis and control design of spatially developing flows." Licentiate thesis, KTH, Mechanics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4769.
Full textMethods in hydrodynamic stability, systems and control theory are applied to spatially developing flows, where the flow is not required to vary slowly in the streamwise direction. A substantial part of the thesis presents a theoretical framework for the stability analysis, input-output behavior, model reduction and control design for fluid dynamical systems using examples on the linear complex Ginzburg-Landau equation. The framework is then applied to high dimensional systems arising from the discretized Navier–Stokes equations. In particular, global stability analysis of the three-dimensional jet in cross flow and control design of two-dimensional disturbances in the flat-plate boundary layer are performed. Finally, a parametric study of the passive control of two-dimensional disturbances in a flat-plate boundary layer using streamwise streaks is presented.
Preda, Valentin. "Robust microvibration control and worst-case analysis for high pointing stability space missions." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0785/document.
Full textNext generation satellite missions will have to meet extremely challenging pointing stability requirements. Even low levels of vibration can introduce enough jitter in the optical elements to cause a significant reduction in image quality. The success of these projects is therefore constrained by the ability of on-board vibration isolation and optical control techniques to keep stable the structural elements of the spacecraft in the presence of external and internal disturbances.In this context, the research work presented in this thesis combines the expertise of the European Space Agency (ESA), the industry (Airbus Defence and Space) and the IMS laboratory (laboratoire de l’Intégration du Matériau au Système) with the aim of developing new generation of robust microvibration isolation systems for future space observation missions. More precisely, the thesis presents the development of an Integrated Modeling, Control and Analysis framework in which to conduct advanced studies related to reaction wheel microvibration mitigation.The thesis builds upon the previous research conducted by Airbus Defence and Space and ESA on the use of mixed active/passive microvibration mitigation techniques and provides a complete methodology for the uncertainty modeling, robust control system design and worst-case analysis of such systems for a typical satellite observation mission. It is shown how disturbances produced by mechanical spinning devices such as reaction wheels can be significantly attenuated in order to improve the pointing stability of the spacecraft even in the presence of model uncertainty and other nonlinear phenomenon.Finally, the work introduces a new disturbance model for the multi harmonic perturbation spectrum produced by spinning reaction wheels that is suitable for both controller synthesis and worst-case analysis using modern robust control tools. This model is exploited to provide new ways of simulating the image distortions induced by such disturbances
Bordenave, Charles. "Analyse stochastique des réseaux spatiaux." Phd thesis, Ecole Polytechnique X, 2006. http://pastel.archives-ouvertes.fr/pastel-00001902.
Full textOtto, Thomas [Verfasser], Thomas [Akademischer Betreuer] Boeck, Jörg [Akademischer Betreuer] Schumacher, and Günther [Akademischer Betreuer] Brenn. "Spatio-Temporal Stability Analysis in Two-Phase Mixing Layers : Effect of a Velocity Deficit near the Interface / Thomas Otto. Gutachter: Jörg Schumacher ; Günther Brenn. Betreuer: Thomas Boeck." Ilmenau : Universitätsbibliothek Ilmenau, 2012. http://d-nb.info/1027300545/34.
Full textVerdoit-Jarraya, Marion. "Caractérisation et modélisation de la dynamique spatiale et saisonnière de populations démersales et benthiques exploitées de la Mer Celtique." Paris 6, 2003. http://www.theses.fr/2003PA066596.
Full textCheong, Lap-Man, and 張立民. "Spatial Stability Analysis of Asymmetric Vortices over Cone-Cylinder Body at High Incidence." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/21415727844961651617.
Full text國立成功大學
航空太空工程學系碩博士班
95
The objective of this work is to study the asymmetric vortices structure and the induced side force on a cone-cylinder body at high incidence. Both control-free and micro-balloon actuated flows were simulated. In the control-free case the effect of small geometric irregularity on the apex was studied first to see the sensitivity of the natural vortical flow development over a cone-cylinder body. Flow control enforced with micro-balloon actuation was then investigated. A previously developed incompressible flow solver which employs the artificial compressibility and the Osher-Chakravarthy upwind MUSCL type total variation diminishing scheme was used. Time-accuracy is achieved by implicit ALU(Approximate Lower/Upper factorization) time-marching augmented by Newton sub-iterations. Geometric alteration was modeled using blowing/suction boundary conditions. Results show that the asymmetry of the natural vortical structure changes with the circumferential position of the imposed disturbance on the apex. Moreover, at sensitive forcing locations, the strength of the disturbances may cause sudden structural change of the separated vortical flow when the volume flux, which simulates the disturbance on the apex, exceeds certain threshold value. The original weak separated vortices situated remotely from the body surface migrate closer to the body surface, while the original strong vortices get pushed far away from the body. The flip of the influential vortical structure results in the side force reversal of the cone-cylinder body. For the controlled flow study, blowing and suction strength was adjusted to yield similar micro-balloon height generated in the experiment. It was observed that, in the same effective forcing region, the enforcement of balloon control over the weak vortex side causes the basic pattern change of the vortex structure. A newly generated organized vortex structure in the vicinity of the original weak vortex side takes the role of the influential vortex, making the side force change significantly in the reversed trend.
Van, Helden Michael John. "Measurement and Modeling of Anisotropic Spatial Variability of Soils for Probabilistic Stability Analysis of Earth Slopes." 2013. http://hdl.handle.net/1993/19683.
Full textLutz, Eric Robert. "Spatial and temporal analysis of snowpack strength and stability and environmental determinants on an inclined, forest opening." 2009. http://etd.lib.montana.edu/etd/2009/lutz/LutzE0509.pdf.
Full textDiaz, Diaz Eliecer Rodrigo. "Hierarchical spatial structure and levels of resolution of intertidal grazing and their consequences on predictability and stability at small scales /." 2008. http://eprints.ru.ac.za/1558/.
Full textLiang, Chen. "Spatial simulation based riverbank slope instability and susceptibility assessment in the Lower River Murray." Thesis, 2015. http://hdl.handle.net/2440/98718.
Full textThesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Civil, Environmental & Mining Engineering, 2015.