Дисертації: "Equilibrium stability"

1

Matros, Alexander. "Stochastic stability and equilibrium selection in games." Doctoral thesis, Stockholm : Economic Research Institute, Stockholm School of Economics (Ekonomiska forskningsinstitutet vid Handelshögsk.) (EFI), 2001. http://www.hhs.se/efi/summary/571.htm.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

2

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.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Lennon, Bernard Andrew. "Equilibrium and stability of inflatable membrane structures." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620672.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Liu, Ying. "Limit equilibrium methods for slope stability analysis." Click to view the E-thesis via HKUTO, 2002. http://sunzi.lib.hku.hk/hkuto/record/B42576684.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Sofer, Miguel Marcelo. "On equilibrium, stability and nonlocality in elasticity theory /." [S.l.] : [s.n.], 1991. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9420.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Huang, Yi-Min. "Magnetohydrodynamic equilibrium and stability of centrifugally confined plasmas." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1774.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Thesis (Ph. D.) -- University of Maryland, College Park, 2004.
Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

7

Howell, David Frederick. "The stability of Z-pinches with equilibrium flows." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313803.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Galletly, Diana Archer. "Modelling the equilibrium and stability of slit tubes." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620186.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Hakkarainen, S. Pekka (Simo Pekka). "Equilibrium and stability studies of strongly shaped Tokamaks." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14374.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Melville, J. P. "The equilibrium and stability of solar coronal magnetic fields." Thesis, Edinburgh Napier University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383676.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Lin, Bor-Chyuan. "Performance and stability of non-equilibrium MHD disk generators." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/42185.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Wilson, Fiona. "Equilibrium and stability properties of collisionless current sheet models." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3548.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The work in this thesis focuses primarily on equilibrium and stability properties of collisionless current sheet models, in particular of the force-free Harris sheet model. A detailed investigation is carried out into the properties of the distribution function found by Harrison and Neukirch (Physical Review Letters 102, 135003, 2009) for the force-free Harris sheet, which is so far the only known nonlinear force-free Vlasov-Maxwell equilibrium. Exact conditions on the parameters of the distribution function are found, which show when it can be single or multi-peaked in two of the velocity space directions. This is important because it may have implications for the stability of the equilibrium. One major aim of this thesis is to find new force-free equilibrium distribution functions. By using a new method which is different from that of Harrison and Neukirch, it is possible to find a complete family of distribution functions for the force-free Harris sheet, which includes the Harrison and Neukirch distribution function (Physical Review Letters 102, 135003, 2009). Each member of this family has a different dependence on the particle energy, although the dependence on the canonical momenta remains the same. Three detailed analytical examples are presented. Other possibilities for finding further collisionless force-free equilibrium distribution functions have been explored, but were unsuccessful. The first linear stability analysis of the Harrison and Neukirch equilibrium distribution function is then carried out, concentrating on macroscopic instabilities, and considering two-dimensional perturbations only. The analysis is based on the technique of integration over unperturbed orbits. Similarly to the Harris sheet case (Nuovo Cimento, 23:115, 1962), this is only possible by using approximations to the exact orbits, which are unknown. Furthermore, the approximations for the Harris sheet case cannot be used for the force-free Harris sheet, and so new techniques have to be developed in order to make analytical progress. Full analytical expressions for the perturbed current density are derived but, for the sake of simplicity, only the long wavelength limit is investigated. The dependence of the stability on various equilibrium parameters is investigated.

13

Aryal, Krishna Prasad. "Slope Stability Evaluations by Limit Equilibrium and Finite Element Methods." Doctoral thesis, Norwegian University of Science and Technology, Department of Civil and Transport Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1868.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This thesis deals with slope stability evolutions carried out by commonly used limit equilibrium (LE) and finite element (FE) methods. The study utilizes two LE based software (SLOPE/W and SLIDE) and one FE based software (PLAXIS). The principal difference between these two analyses approaches is that the LE methods are based on the static of equilibrium whereas FE methods utilise the stress‐strain relationship or constitutive law.

To fulfil one of the aims of the study, the LE based methods are compared based on the factor of safety (FOS) obtained for various load combinations. The comparison is mainly based on simplified slope geometry and assumed input parameters. Among the LE methods, the Bishop simplified (BS), Janbu simplified (JS) and Janbu GPS methods are compared with the Morgenstern‐Price method (M-PM). The two latter methods satisfy both force and moment equilibriums. In addition, M-PM allows a variable interslice force function. These LE methods are well established for many years, and thus some of them are still commonly used in practice for stability analysis. Simplicity and relatively good results are the advantages of these methods.

The comparative study among the LE methods shows that BSM is as good as M-PM for normal condition in circular shear surface (SS) analysis. Similarly, JSM is as good as M‐PM for plane SS analysis. Moreover, the study shows that BSM is insensitive to interslice forces in circular SS analysis, whereas JSM is insensitive to interslice forces in plane SS analysis.This is true for the analyses without any external forces acting in slopes. With some external forces, both methods may be sensitive to the interslice force function, and thus the analyses may result in either higher or lower FOS compared with M-PM. Even if the M-PM assumes an interslice force function in analysis, the method is found suitable, because the method satisfies both force and moment equilibrium conditions. The comparison between Janbu’s GPS method and the M‐PM shows a very good agreement with nominal difference (<2%) in the FOS.

Moreover, the M-PM has been compared with results from the FE analyses. Compared with the FE (PLAXIS) analyses, the LE (M-PM) analyses may estimate 5 – 14% higher FOS, depending on the conditions of a dry slope and a fully saturated slope with hydrostatic pore pressure distributions. For fully saturated conditions in the slope, inaccurate computation of stresses in LE methods may have resulted in larger difference in the computed FOS.

Since, the FE software is based on stress-strain relationship, stress redistributions are surely better computed even for a complicated problem. This has been found one of the advantages in FE simulations. A parameter study shows that the application of a positive dilatancy angle in FE analysis can significantly improve the FOS (4 - 10%). On contrast, the shear surface optimization in LE (M-PM in SLOPE/W) analysis results in lower FOS, and thus minimizing the difference in FOS compared with FE analysis. Thus, the optimisation of the circular SS in LE analyses and application of dilatancy angle in FE analyses may provide very good agreement in FOS keeping the variations less than 5%.

Instability of natural and built-in slopes has been a serious geotechnical challenge, particularly in mountainous countries like Nepal, where a large number of water-induced disasters are experienced every year. Since the country lies in a relatively active earthquake zone, earthquake events may adversely affect the long-term stability of slopes along the highways, around hydropower installations and elsewhere. The selected case study from the Middle Marsyangdi Hydroelectric Project (MMHEP) in Nepal was carried out, focusing on both the groundwater and earthquake effects on long-term stability of slopes. In addition, the analyses were performed for pore pressure distributions by seepage analyses and pseudo-static and dynamic earthquake events imposed in the case slopes.

Another important contribution of this study has been the investigations of the shear strength parameters for the case study slopes. The investigation ranges from the basic index tests, which were carried out to characterize material properties and establish a basis for building-in the test specimens, to the most advanced triaxial tests. Additionally, both consolidated drained and undrained triaxial tests were conducted, aiming to find any differences in the strength parameters. A total of twenty-four triaxial tests from four different soil samples, taken from the case study slopes, were conducted to define the Mohr-Coulomb failure envelope, and thus obtained the effective shear strength parameters (c’, φ’) for stability evaluations. In addition, the coefficients of permeability were investigated as an important input for seepage analyses.

Two slopes, one located at the dam site and the other at the powerhouse of the MMHEP, were evaluated for long-term stability conditions. The study, carried out using the monitored groundwater table, reveals that the groundwater is the potential destabilizing factor in the slopes. Both hydrostatic pore pressure distributions with phreatic surface correction and seepage analysis were carried out in the stability analysis. The pore pressure distributions from the seepage analyses indicated critically stable slopes particularly at the toe areas. However, a significant improvement in the FOS was found with lowered groundwater table. Moreover, the study, carried out for the pseudo-static analysis with the selected earthquake acceleration coefficient, shows that otherwise stable slopes become critical in earthquake events. However, the case slopes were found to have higher FOS than the recommended minimum value for such conditions. The dynamic earthquake simulations indicate both positive excess pore pressure and suction developed during the earthquakes. The applied earthquake acceleration of 0.15g (35% of PGA, where PGA = 4.2 m/s2)) shows critical conditions in the slopes. Moreover, larger accumulated displacements were found close to the slope surface compared to the inner side of the slopes. In addition, the dynamic analyses further indicate plastic points all over the slopes and increased shear strains in a particular location.

Nevertheless, the difference in FOS found from the LE and FE analyses may have a little interest, if there is a large uncertainty in the input parameters. Therefore, priority should be given to investigate the shear strength parameters and precise mapping of the slope geometry before selecting an appropriate analysis method. Most preferably, a slope should be analyzed by FE methods, else otherwise by LE based M‐PM or GPS method with investigated input parameters.

14

Zou, Jieping. "Nonlinear stability and statistical equilibrium of forced and dissipated flow." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/32124.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

A global analysis for the hydrodynamical system defined for a homogeneous, incompressible layer of fluid on the β-plane is performed in both infinite and finite function space. Its application to global stability has yielded an algorithm for characterizing flows based on the existence of initially growing perturbations as opposed to the normal mode analysis; its application to the search for optimal initial perturbations has led to the least upper bound of energy growth rate; its application to multiple equilibria has given rise to a necessary condition for their existence; its application to the study of the relationship of modal to nonmodal growth rates has uncovered the cause underlying many aspects of the limitation of the modal stability analysis including the failure to predict transient growth of disturbances in stable flows and the underestimation of the intensity of initial development of instability in unstable flows. Numerical illustrations made for some specific flows have strengthened the general results, suggesting that a stability analysis of a hydrodynamical system without a global analysis is likely to be limited in many important aspects. The local analysis of asymptotic behavior of nonmodal disturbances to hyperbolic equilibria of the system have established: a) for any subcritical flow outside of monotonic, global stability regime, there exists a finite neighborhood around the origin of RM such that a disturbance initialized in this neighborhood will ultimately decay to zero after it exhibits Orr's temporal amplification; b) for any supercritical flow, there exists a finite neighborhood adjacent to the origin of RM such that a disturbance initialized in this neighborhood will persist as t→∞; and c) the nature of the persistent disturbances is related to the nature of the nonhyperbolic point in parameter space of interest. The numerical experiments are seen to confirm these predictions. Closure modeling of forced-dissipated statistical equilibrium of perturbed flows arising from initially uniform zonal flows over random topography is done with special regard to the correlation between disturbance and underlying topography and the resulting stress. Such an exercise has led to, on one hand, the numerical results for topographical stress suggesting clearly the significance of this force in overall momentum budget of large scale ocean circulations. On the other hand, it has led to an appreciation that the detailed conservation of energy and potential enstrophy, which holds regardless of the presence of dissipation in the system, provides a means for systematic investigation of nonlinear transfer of the these quantities among interacting triads, an area not accessible to other approaches.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

15

Potgieter, Jean-Timothy. "Finite element versus limit equilibrium stability analyses for surface excavations." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/63001.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Limit equilibrium methods are widely and routinely used in practice. In several codes, limit equilibrium methods are recommended to evaluate the stability of a lateral support systems, such as soil-nails and anchors, to an acceptable defined factor of safety. For decades, limit equilibrium methods have been used successfully in providing an acceptable margin of safety against failure (movements, which can be significantly more complex, is not considered). However, due to the advances in computational power offered by personal computers, finite element modelling has become increasingly accessible. Since the idea immerged of using a strength reduction factor in finite element displacement analyses, an increase in the use thereof to calculate the factor of safety has been observed. However, the use of finite elements has often led to misinterpretation of the results. Several authors have cautioned engineers to the complexities involved in using finite element analyses to model geotechnical problems. Studies have been conducted comparing the use of finite elements to other methods. However, most of these studies consider only slope problems. Few studies have been conducted for lateral support systems. Several codes of practice use the numerical quantity of ‘factor of safety’ to define the suitability of geotechnical design. Whether finite element- or limit equilibrium methods are used, the accurate calculation of the factor of safety remains paramount to quantifying the stability of a geotechnical structure. The aim of this research is to compare limit equilibrium and finite element methods in evaluating the stability, in terms of factor of safety, of soil-nailed and anchored lateral support systems in surface excavations. This was done by using four methods of analysis to calculate the factor of safety. Two traditional limit equilibrium methods were used (trail wedge and method of slices). The newer, finite element strength reduction technique was used. Finally, a hybrid method which combines a finite element analysis with limit equilibrium slip surface analysis was used. These methods of analysis were applied to three different geometries. A uniform slope without any reinforcing was analysed. This was followed by the analysis of an 8.5m soil-nail supported face and a 17m face supported by anchors. A parametric study was conducted for the soil-nailed and anchored excavations. Material properties (friction angle, cohesion etc.), modelling parameters (boundary distances, mesh resolution etc.) and engineering design variables (reinforcement capacity etc.) were varied in order to observe the influence on the factor of safety. It is concluded that limit equilibrium methods, such as a trial wedge method and the method of slices, compare well with each other throughout the analyses. Using a combination of finite elements with a slip surface analysis compares poorly with the other methods. By using the finite element strength reduction technique, an optimised failure mechanism is found. The finite element strength reduction technique compares well with limit equilibrium methods if the following two conditions are met: • The same failure mechanism is evaluated for both methods; and • the capacity of reinforcement is consistently specified in both methods.
Dissertation (MEng)--University of Pretoria, 2017.
Civil Engineering
MEng
Unrestricted

16

Culverwell, Ian Dennis. "Resistive Z-pinch equilibria and stability." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47833.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

17

St-Amour, Amelie. "Equilibrium configurations of three-body tethered satellite systems and their stability." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33995.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

In this thesis, an analytical investigation of the dynamics of three-body tethered satellite systems is presented. The analysis is performed for two cases: two-dimensional and three-dimensional motion. At first, the equations governing the motion of such systems are obtained assuming that the system center of mass moves in a circular orbit around the Earth. Then, the various equilibrium configurations are obtained. The equilibrium configurations are classified in eleven groups. Three of these groups are collinear configurations, and the others are triangular configurations. A stability analysis is performed for each equilibrium configuration. It is found that two of the collinear configurations are marginally stable. These are configurations with the three masses on the local vertical. The other collinear configurations are unstable. The triangular configurations are unstable except for some systems with a small middle mass. The results for two-dimensional motion are consistent with those for three-dimensional motion.

18

HOLANDA, AUREA SILVA DE. "ANALYSIS OF THE EQUILIBRIUM AND STABILITY OF PLATES WITH CONTACT CONSTRAINTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2000. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2002@1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Neste trabalho é desenvolvida uma metodologia baseada no Método dos Elementos Finitos para estudar o equilíbrio e a estabilidade de placas apoiadas em fundações elásticas. A formulação utilizada para a análise de placas é válida para a análise linear e não-linear de placas isotrópicas ou ortotrópicas, perfeitas ou inicialmente imperfeitas. Esta formulação é baseada nas teorias de placas de Mindlin e von Kármán e na teoria de cascas abatidas proposta por Marguerre. As placas podem estar apoiadas em fundações lineares ou não-lineares, que são modeladas utilizando elementos finitos isoparamétricos. A fundação não-linear contém termos cúbicos e quadráticos, de modo a permitir uma representação mais realista do seu comportamento. Na obtenção dos caminhos não-lineares de equilíbrio das estruturas, diferentes métodos incrementais-iterativos são utilizados. Com o objetivo de considerar o problema de contato unilateral, duas formulações que utilizam técnicas de Programação Matemática são implementadas, sendo uma para a análise linear e outra para a análise não-linear. Além dessas formulações, o problema de contato unilateral pode ser tratado através do uso de um modelo constitutivo de fundação não resistente à tração também implementado neste trabalho. Exemplos de equilíbrio e de estabilidade são apresentados e, quando possível, os resultados são comparados com os existentes na literatura. Através destes exemplos, estuda-se a influência da não-linearidade da placa e da fundação, das imperfeições geométricas iniciais e do tipo de contato (unilateral ou bilateral) na capacidade de carga e estabilidade da placa. Também é discutida a influência do uso de diferentes malhas de elementos finitos nestes resultados, bem como a eficiência computacional das metodologias utilizadas para lidar com o contato unilateral.
In this work, a finite element formulation to study the equilibrium and the stability of plates on elastic foundations is developed. This formulation can be used for linear and nonlinear analyses of isotropic or orthotropic, perfect or initially imperfect plates. It is based on Mindlin`s and von Kármán`s plate theories and on the shallow shell theory proposed by Marguerre.The plates can be on linear or non-linear foundations modeled using isoparametric finite elements. The non-linear foundation contains cubic and quadratic terms to allow a more realistic representation of its behavior. In order to obtain the equilibrium path of the structure, different incremental-iterative methods are employed.Two different strategies are implemented to solve the unilateral contact problem. In the first one, two formulations that use optimization techniques are developed, one for the linear analysis and the other one for non-linear analysis. The second strategy modifies the constitutive relation of the foundation in order to simulate its tensionless behavior.Equilibrium and stability examples are presented and, whenever possible, the results are compared with the ones found in the literature. In these examples, the influence of the non-linearities of the plate and the foundation, of initial geometric imperfections, and of the type of contact (unilateral or bilateral) on the load capacity and stability of the plate is studied. The influence of different finite element meshes on the results and the computational efficiency of the methodologies used to solve the unilateral contact problem are also discussed.
En este trabajo se desarrolla una metodología basada en el Método de los Elementos Finitos para estudiar el equilibrio y la estabilidad de placas apoyadas en fundaciones elásticas. La formulación utilizada para el análisis de placas es válida para el análisis lineal y no lineal de placas isotrópicas o ortotrópicas, perhechas o inicialmente imperhechas. Esta formulación tiene como base las teorías de placas de Mindlin y von Kármán y en la teoría propuesta por Marguerre. Las placas pueden estar apoyadas en fundaciones lineales o no lineales, que son modeladas utilizando elementos finitos isoparamétricos. La fundación no lineal contiene términos cúbicos y cuadráticos, de modo que permita una representación más realista del su comportamiento. En la obtención de los caminos no lineales de equilibrio de las extructuras, se utilizaron diferentes métodos incrementales iterativos. Con el objetivo de considerar el problema de contacto unilateral, se implementan dos formulaciones que utilizan técnicas de Programación Matemática, una para el análisis lineal y otra para el análisis no lineal. Además de esas formulaciones, el problema de contacto unilateral puede ser tratado a través del uso de un modelo constitutivo de fundación no resistente a la tracción, que también es implementado en este trabajo. Se presentan ejemplos de equilíbrio y de estabilidad y, cuando posible, se comparan los resultados con los existentes en la literatura. A través de estos ejemplos, se estudia la influencia de la no linealidad de la placa y de la fundación, de las imperfecciones geométricas iniciales y del tipo de contacto (unilateral o bilateral) en la capacidad de carga y la estabilidad de la placa. También se discute la influencia del uso de diferentes mallas de elementos finitos em estos resultados, así como la eficiencia computacional de las metodologías utilizadas para tratar el contacto unilateral.

19

Caleo, Andrea. "Differential rotation, radiative equilibrium, and local hydrodynamic stability in stellar interiors." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:b7521f19-0dd0-4dc0-985d-0934d673c9cc.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The problem of angular momentum transport in the radiative zone of the Sun and other stars is currently one of the most discussed in stellar astrophysics. A wide range of local and global instabilities acting in differentially rotating stars have been studied and incorporated in stellar evolutionary codes. In this thesis, I revisit two of the hydrodynamic processes that are thought to operate, namely the Eddington-Sweet (ES) circulation and a global motion induced by the Goldreich-Schubert-Fricke (GSF) instability, and investigate stellar models in which these mechanisms are suppressed. In particular: The data from helioseismology show that the upper radiative zone of the Sun is in near-uniform rotation, but they have a significant uncertainty. I discuss the possibility of patterns of differential rotation compatible with the constraint of perfect radiative equilibrium, which implies the absence of ES circulation. I show that this constraint leads to a set of ordinary differential equations for the stellar rotation profile, which are solved numerically. I find that these models can be quite close to uniform rotation, and compatible with the data from helioseismology. I investigate the dynamical stability of these models. It is shown that while a naive approach would suggest that the GSF instability would distrupt the rotation of these stars, this does not happen in reality. I present a study of the local stability of stratified, weakly magnetized, differentially rotating uids to non-axisymmetric perturbations with finite heat conductivity, kinematic viscosity, and resistivity. The models are found to be locally stable under rather general circumstances. Even if the molecular viscosity is very small compared to the heat conductivity, it suffices to suppress the GSF instability. I examine the onset of the GSF instability in the core of red giant stars, where, according to recent observations, strong differential rotation may be present. I derive constraints on the amount of shear necessary for the GSF instability to operate at different depths, and show that very strong shear is required. In general, the effectiveness of the GSF instability in transporting angular momentum is currently overstated.

20

Warren, Sean N. "Limit equilibrium stability analysis utilizing geotechnical data at Mount Baker, Washington /." abstract and full text PDF (UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1461537.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Thesis (M.S.)--University of Nevada, Reno, 2008.
"December 2008." Includes bibliographical references (leaves 109-112). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web. Library also has electronic version on CD-ROM

21

Chen, Xing 1956. "Hot electron plasma equilibrium and stability in the Constance B mirror experiment." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14580.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Maeda, Takashi. "Phase equilibrium and beta stability in Ti-rich Ti-V-Al alloys." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47166.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Sedin, Victor. "Stability Analysis of Equilibrium Points and Symmetry Curves in Discrete Cosmological Models." Thesis, KTH, Fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208202.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

24

Ichiguchi, Katsuji. "Numerical Studies of Three-Dimensional Equilibrium and Stability for Stellarator/Heliotron Configurations." Kyoto University, 1989. http://hdl.handle.net/2433/74743.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

25

Paul, Pascal. "Essays on financial stability and monetary policy." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:49999782-6173-4e2b-8645-cab0b1561595.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This thesis consists of three self-contained chapters. Chapter I. The first chapter develops a dynamic general equilibrium model which includes financial intermediation and endogenous financial crises. Consistent with the data, financial crises occur out of prolonged (credit) boom periods and are initiated by a moderate adverse shock. The mechanism which gives rise to boom-bust episodes around financial crises is based on an interaction between the maturity mismatch of the financial sector and an agency problem which results in procyclical lending. I show how to model these features in a tractable way, giving a realistic representation of the financial sector's balance sheet and its lending behavior. The chapter provides empirical evidence on the behavior of the U.S. financial sector's market leverage which is (i) acyclical, (ii) rose mildly prior to the Great Recession, and (iii) increased sharply during the crisis; the model is consistent with these empirical facts. It also predicts and replicates the Great Recession, when confronted with a historical series of structural shocks. Finally, the framework is extended to include price rigidities, nominal debt contracts, and monetary policy. Within this version, I analyze the impact of monetary policy on financial stability and show that a U-shaped pattern of the policy target rate is most likely to increase financial instability. Chapter II. The second chapter models the economy as a time varying vector autoregression, consisting of economic and financial variables. The interest lies in the time varying response of these variables to a monetary policy shock. Monetary policy shocks are identified as the surprise component in policy announcements extracted from price changes in Federal Funds futures around such announcements. These monetary policy surprises enter the model as an exogenous variable. The framework is used to obtain evidence on the time varying response of stock prices to the monetary policy surprises. Stock prices always persistently decrease following a monetary tightening and more strongly than fundamentals imply - with an increase in risk-premia accounting for the difference. However, the response of stock prices varies over time. They decrease less during a boom and a perceived bubble period than during a recession. The findings suggest that so-called "leaning against the wind policies" may be ineffective since stock prices are less responsive during periods when such policies would disinflate asset bubbles using contractionary monetary policy. Chapter III. The third chapter augments a monetary dynamic general equilibrium model with a bubble as considered in [Miao_Wang_2015]. A bubble may exist in firms' stock market values and firms borrow against their inflated stock market values. Within this framework, I analyze the relation between monetary policy and the bubble. I find that contractionary monetary policy decreases the bubble which tightens borrowing constraints and amplifies the reaction of investment and output. These results are in contrast to the ones in Gali (2014) who considers a bubble of the classic rational type and finds that contractionary monetary policy can increase bubbles.

26

Мірошниченко, Ганна Олександрівна, Анна Александровна Мирошниченко та Hanna Oleksandrivna Miroshnychenko. "Основи взаємозв’язку понять "рівновага", "стійкість" і "стабільність" банківської системи". Thesis, Українська академія банківської справи Національного банку України, 2010. http://essuir.sumdu.edu.ua/handle/123456789/62235.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

З огляду на те, що дослідження поняття рівноваги економічної системи є центральним у структурі економічних знань і є важливою умовою розвитку національної економіки, існує проблема розуміння даного поняття. Таким чином, доцільно дослідити основи взаємозв’язку між такими основними економічними поняттями, як рівновага, стійкість і стабільність банківської системи.
Given that the study of the concept of equilibrium of the economic system is central to the structure of economic knowledge and is an important condition for the development of the national economy, there is a problem of understanding this concept. Thus, it is advisable to explore the basics of the relationship between such basic economic concepts as equilibrium, stability and stability of the banking system.
Should investigate the basis of the relationship between basic economic concepts such as balance, stability and stability of the banking system.

27

Martínez, Sepulveda Juan Francisco. "Essays in financial stability under financial frictions." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:4e2a5663-c0a5-43dc-8fe7-f6fa05048e76.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This thesis is a collection of essays where I explore and extend the study of the role of financial frictions for the determination of asset prices, financial stability, and economic resilience. The frictions included in the analysis are individual and aggregate uncertainty, agent heterogeneity, money, liquidity and default. The first essay is an empirical study that motivates my research objectives. This work starts with the exploration of the role of liquidity on asset prices, specifically on sovereign bonds of emerging countries. I present a comprehensive model where I developed a novel methodology for finding the role of liquidity in the determination of asset prices during the financial crisis. In the second essay, illuminated by the empirical findings, I apply and expand the general equilibrium theory of money, default and financial stability. The contributions at the theoretical level are the extension of two-period model with discrete state space to the infinite horizon dynamic stochastic setting, and the inclusion of liquidity restrictions. In the third essay, I further extend this framework, allowing for production technology and endogenous market liquidity. Given the theoretical setting, I have analyzed the responses of financial stability and economic performance variables to real and financial shocks. Finally, in the fourth essay I produce an empirical application of this work. I apply a novel semi-parametric financial stability metric, and evaluate its relevance for the determination of asset prices, in the presence of liquidity restrictions. As a result, this thesis suggest plausible explanations for financial and economic issues that conventional models have not dealt with adequately.

28

Firat, Seyhan. "Critical assessment of existing slope stability formulae and application to slope stabilisation." Thesis, University of South Wales, 1998. https://pure.southwales.ac.uk/en/studentthesis/critical-assessment-of-existing-slope-stability-formulae-and-application-to-slope-stabilisation(339ddd93-e0c1-466d-8278-143beca4fb20).html.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

In this research, extensive use has been made of limit equilibrium methods of analysis for studying the stability of slopes. For the determination of the factor of safety (FOS) of slopes, the usual two-step process has been adopted; (a) assuming a slip surface for the soil mass, and (b) using the appropriate limit equilibrium equation(s). Eight wellknown limit equilibrium methods have been programmed to calculate different FOS values. The comparative performance of the various analyses has been carried out successfully using case studies. The innovative use of Gauss quadrature to calculate the FOS values has been shown to reducet he iterative sequencesd ramatically with no loss of accuracy. A visco-plastic flow model has been proposed to estimate lateral forces on piles used for slope stabilisation. The present research data occupies an "in-between" position to the previously reported values, with the variation trend being confirmed satisfactorily in all cases. Slope stabilisation due to the presence of a row of piles has been investigated using two distinct lateral load estimations. These include theories of plastic deformation and the proposed visco-plastic flow which are modelled and implemented in a computer program. Eight well-known methods of slope stability analyses have been adopted and computer coded to re-calculate FOS values for a slope reinforced by a row of piles. A Finite Element computer program has been developed to evaluate the displacement, bending moment and shear force along the pile axis. The pile is analysed at two levels above and below the slip failure surface.

29

Celli, Michele <1980&gt. "Stability, viscous dissipation and local thermal non-equilibrium in fluid saturated porous media." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2485/1/Celli_Michele_PhD_Thesis.pdf.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

In this thesis, the field of study related to the stability analysis of fluid saturated porous media is investigated. In particular the contribution of the viscous heating to the onset of convective instability in the flow through ducts is analysed. In order to evaluate the contribution of the viscous dissipation, different geometries, different models describing the balance equations and different boundary conditions are used. Moreover, the local thermal non-equilibrium model is used to study the evolution of the temperature differences between the fluid and the solid matrix in a thermal boundary layer problem. On studying the onset of instability, different techniques for eigenvalue problems has been used. Analytical solutions, asymptotic analyses and numerical solutions by means of original and commercial codes are carried out.

30

Celli, Michele <1980&gt. "Stability, viscous dissipation and local thermal non-equilibrium in fluid saturated porous media." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2485/.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

In this thesis, the field of study related to the stability analysis of fluid saturated porous media is investigated. In particular the contribution of the viscous heating to the onset of convective instability in the flow through ducts is analysed. In order to evaluate the contribution of the viscous dissipation, different geometries, different models describing the balance equations and different boundary conditions are used. Moreover, the local thermal non-equilibrium model is used to study the evolution of the temperature differences between the fluid and the solid matrix in a thermal boundary layer problem. On studying the onset of instability, different techniques for eigenvalue problems has been used. Analytical solutions, asymptotic analyses and numerical solutions by means of original and commercial codes are carried out.

31

Medina, Ruiz Hamlet. "TCP and network coding : equilibrium and dynamic properties." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112165.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Lors d'une communication dans un réseau, les nœuds intermédiaires se contentent en général de retransmettre les paquets de données qu'ils reçoivent. Grâce au codage de réseau (NC), ces nœuds intermédiaires peuvent envoyer des combinaisons linéaires des paquets qu'ils ont reçus. Ceci permet une meilleure exploitation de la capacité du réseau et une plus grande robustesse à l'égard de pertes.Cette thèse s'intéresse à une implantation du NC en lien avec TCP (TCP-NC). Grâce à la redondance introduite par le NC, une partie des pertes liées à des liens sans fils peut être compensée. Elle propose en particulier un mécanisme d'adaptation de la redondance introduite par le codage de réseau. Une première partie de cette thèse est consacrée à l'analyse de la dynamique de TCP-NC avec Random Early Detection (RED) comme mécanisme de gestion des files d'attente en utilisant les outils d'optimisation convexe et issus de l’automatique. Nous caractérisons l'équilibre du réseau et les propriétés de stabilité de TCP-Reno en présence de NC. Dans une seconde partie, cette thèse propose un algorithme d'adaptation de la redondance introduite par NC. Dans TCP-NC avec redondance adaptative (TCP-NCAR), cet ajustement se fait grâce à un schéma de différenciation des pertes, qui estime la répartition des pertes entre erreurs de transmission dues aux liens sans fils et pertes liées à la congestion. Les propriétés d'équilibre et de stabilité de TCP-NCAR/RED sont caractérisées. Les résultats théoriques et de simulation montrent que TCP-NCAR adopte une redondance proche de l'optimum quand les taux de perte de paquets sur les liens sans fils sont petits. En outre, le modèle linéarisé autour de l'équilibre montre que TCP-NCAR augmente la taille de la région de stabilité de TCP-Reno
Communication networks today share the same fundamental principle of operation: information is delivered to their destination by nodes intermediate in a store-and-forward manner.Network coding (NC) is a technique that allows intermediate nodes to send out packets that are linear combinations of previously received information. The main benefits of NC are the potential throughput improvements and a high degree of robustness, which is translated into loss resilience. These benefits have motivated deployment efforts for practical applications of NC, e.g., incorporating NC into congestion control schemes such as TCP-Reno to get a TCP-NC congestion protocol. In TCP-NC, TCP-Reno throughput is improved by sending a fixed amount of redundant packets, which mask part of the losses due, e.g., to channel transmission errors. In this thesis, we first analyze the dynamics of TCP-NC with random early detection (RED) as active queue management (AQM) using tools from convex optimization and feedback control. We study the network equilibrium point and the stability properties of TCP-Reno when NC is incorporated into the TCP/IP protocol stack. The existence and uniqueness of an equilibrium point is proved, and characterized in terms of average throughput, loss rate, and queue length. Our study also shows that TCP-NC/RED becomes unstable when delay or link capacities increases, but also, when the amount of redundant packets added by NC increases. Using a continuous-time model and neglecting feedback delays, we prove that TCP-NC is globally stable. We provide a sufficient condition for local stability when feedback delays are present. The fairness of TCP-NC with respect to TCP-Reno-like protocols is also studied. Second, we propose an algorithm to dynamically adjust the amount of redundant linear combinations of packets transmitted by NC. In TCP-NC with adaptive redundancy (TCP-NCAR), the redundancy is adjusted using a loss differentiation scheme, which estimates the amount of losses due to channel transmission errors and due to congestion. Simulation results show that TCP-NCAR outperforms TCP-NC in terms of throughput. Finally, we analyze the equilibrium and stability properties of TCP-NCAR/RED. The existence and uniqueness of an equilibrium point is characterized experimentally. The TCP-NCAR/RED dynamics are modeled using a continuous-time model. Theoretical and simulation results show that TCP-NCAR tracks the optimal value for the redundancy for small values of the packet loss rate. Moreover, simulations of the linearized model around equilibrium show that TCP-NCAR increases the size of the TCP-Reno stability region. We show that this is due to the compensator effect of the redundancy adaptation dynamics to TCP-Reno. These characteristics of TCP-NCAR allow the congestion window adaptation mechanism of TCP-Reno to react in a smooth way to channel losses, avoiding some unnecessary rate reductions, and increasing the local stability of TCP-Reno

32

Albataineh, Nermeen. "SLOPE STABILITY ANALYSIS USING 2D AND 3D METHODS." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1153719372.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Badasyan, Narine. "Game Theoretic Models of Connectivity Among Internet Access Providers." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/11193.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The Internet has a loosely hierarchical structure. At the top of the hierarchy are the backbones, also called Internet Access Providers (hereafter IAPs). The second layer of the hierarchy is comprised of Internet Service Providers (hereafter ISPs). At the bottom of the hierarchy are the end users, consumers, who browse the web, and websites. To provide access to the whole Internet, the providers must interconnect with each other and share their network infrastructure. Two main forms of interconnection have emerged â peering under which the providers carry each otherâ s traffic without any payments and transit under which the downstream provider pays the upstream provider a certain settlement payment for carrying its traffic. This dissertation develops three game theoretical models to describe the interconnection agreements among the providers, and analysis of those models from two alternative modeling perspectives: a purely non-cooperative game and a network perspective. There are two original contributions of the dissertation. First, we model the formation of peering/transit contracts explicitly as a decision variable in a non-cooperative game, while the current literature does not employ such modeling techniques. Second, we apply network analysis to examine interconnection decisions of the providers, which yields much realistic results. Chapter 1 provides a brief description of the Internet history, architecture and infrastructure as well as the economic literature. In Chapter 2 we develop a model, in which IAPs decide on private peering agreements, comparing the benefits of private peering relative to being connected only through National Access Points (hereafter NAPs). The model is formulated as a multistage game. Private peering agreements reduce congestion in the Internet, and so improve the quality of IAPs. The results show that even though the profits are lower with private peerings, due to large investments, the network where all the providers privately peer is the stable network. Chapter 3 discusses the interconnection arrangements among ISPs. Intra-backbone peering refers to peering between ISPs connected to the same backbone, whereas inter-backbone peering refers to peering between ISPs connected to different backbones. We formulate the model as a two-stage game. Peering affects profits through two channels - reduction of backbone congestion and ability to send traffic circumventing congested backbones. The relative magnitude of these factors helps or hinders peering. In Chapter 4 we develop a game theoretic model to examine how providers decide who they want to peer with and who has to pay transit. There is no regulation with regard to interconnection policies of providers, though there is a general convention that the providers peer if they perceive equal benefits from peering, and have transit arrangements otherwise. The model discusses a set of conditions, which determine the formation of peering and transit agreements. We argue that market forces determine the terms of interconnection, and there is no need for regulation to encourage peering. Moreover, Pareto optimum is achieved under the transit arrangements.
Ph. D.

34

Scapello, Justin Thomas. "Solvent extraction of a polar solute using colloidal liquid aphrons : stability, equilibrium and mass transfer." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265955.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Karim, Ishtak. "Equilibrium and stability studies of plasmas confined in a dipole magnetic field using magnetic measurements." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/41294.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.
Includes bibliographical references (p. 185-188).
The Levitated Dipole Experiment (LDX) is the first experiment of its kind to use a levitated current ring to confine a plasma in a dipole magnetic field. Unlike most other confinement devices, plasma compressibility stabilizes and allows the plasma to attain a peak beta on the order of unity. Various magnetic sensors have been designed, calibrated, installed, and operated to reconstruct the plasma pressure profile through least-squares fitting to model profiles. Although both isotropic and anisotropic models are used, the latter is critical in deducing the correct beta values for the electron cyclotron resonance heated (ECRH), anisotropic LDX plasmas. The simpler isotropic models give accurate spatially integrated quantities of the pressure profile. The reconstruction of LDX plasmas requires overcoming unique obstacles. Because the floating coil is superconducting, care must be taken when interpreting magnetic signals, which measure the sum of the plasma current and the decrease in the floating coil current. The coupling of these two quantities, in addition to the large physical distances between the sensors and the plasma, makes the magnetic measurements sensitive mostly to the plasma dipole moment. A family of current and pressure profiles with the same dipole moment can therefore fit the measurements equally well. The ambiguity in determining the pressure profile is resolved by supplementing the magnetics with X-ray emissivity data. Internal flux loops close to the plasma will be added in the future to resolve higher order moments.
(cont.) A peak beta of more than 26 % has been measured by the magnetic sensors to date. The high beta plasmas are shown to have supercritical pressure profiles that exceed the MHD limit. The finding confirms that the ECRH produced hot electrons that carry most of the pressure are minimally sensitive to the limit. The MHD gradient limit is slightly increased by incorporating pressure anisotropy, but magnetic data routinely gives a best fit profile that substantially exceeds even the anisotropic limit. It has yet to be seen whether the kinetic analog of the MHD interchange mode, or the hot electron interchange mode (HEI), plays a significant role in limiting the hot electron density gradient. The HEI's have been magnetically measured and shown to correlate with drops in flux measurements. Lastly, it is revealed that LDX plasmas display a linear scaling of stored energy with plasma current (known as the D-P-S relation), much like magnetospheric plasmas. This scaling is used to estimate the energy confinement time of LDX plasmas with different heating frequency compositions.
by Ishtak Karim.
Sc.D.

36

Loehr, John Erik. "Development of a hybrid limit equilibrium-finite element procedure for three-dimensional slope stability analysis /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Arhinful, Daniel Andoh. "Lorenzův systém: cesta od stability k chaosu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417087.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The theory of deterministic chaos has generated a lot of interest and continues to be one of the much-focused research areas in the field of dynamics today. This is due to its prevalence in essential parts of human lives such as electrical circuits, chemical reactions, the flow of blood through the human system, the weather, etc. This thesis presents a study of the Lorenz equations, a famous example of chaotic systems. In particular, it presents the analysis of the Lorenz equations from stability to chaos and various bifurcation scenarios with numerical and graphical interpretations. It studies concepts of non-linear dynamical systems such as equilibrium points, stability, linearization, bifurcation, Lyapunov function, etc. Finally, it discusses how the Lorenz equations serve as a model for the waterwheel (in detail), and the convection roll for fluid.

38

McClung, Nigel. "Essays in Regime Switching Policy and Adaptive Learning in Dynamic Stochastic General Equilibrium." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23707.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This dissertation studies monetary-fiscal policy interactions and adaptive learning applications in regime-switching DSGE models. A common thread through my research is understanding how policymakers may be affected by the interaction of policy regime change and agents' beliefs about past, current or future policy in general equilibrium. The work I present in this dissertation shows that conventional and unconventional policy outcomes, as well as the existence, uniqueness and expectational stability of rational expectations solutions, depend heavily on the expectational effects of time-varying policy. These findings suggest that uncertainty over future fiscal policy may curb the effectiveness of monetary policy, or otherwise constrain the actions of central bankers. In carrying out this research agenda, my work also examines the relationship between determinacy and expectational stability in a general class of Markov-switching DSGE models.

39

Patel, Keyurkumar S. "Automatic generation of global phase equilibrium diagram from equation of state." [Tampa, Fla] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002327.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Fournier, Mathew. "Investigations into the Shear Strength Reduction method using distinct element models." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2492.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This thesis reports a detailed investigation into the use of the Shear Strength Reduction (SSR) method to determine factor of safety values in discontinuum models using the Universal Distinct Element Code. The SSR method depends on the definition of failure within the model and two different criteria were compared: the numerical unbalanced force definition and a more qualitative displacement-monitoring based method. A parametric study was first undertaken, using a simple homogeneous rock slope, with three different joint networks representing common kinematic states. Lessons learned from this study were then applied to a more complex case history used for validation of the SSR method. The discontinuum models allow for the failure surface to propagate based on constitutive models that better idealize the rockmass than simpler methods such as limit equilibrium (e.g. either method of slices or wedge solutions) and even numerical continuum models (e.g. finite difference, finite element). Joints are explicitly modelled and can exert a range of influences on the SSR result. Simple elasto-plastic models are used for both the intact rock and joint properties. Strain-softening models are also discussed with respect to the SSR method. The results presented highlight several important relationships to consider related to both numerical procedures and numerical input parameters. The case history was modelled similar to how a typical forward analysis would be undertaken: i.e. simple models with complexities added incrementally. The results for this case generally depict a rotational failure mode with a reduced factor of safety due to the presence of joints within the rockmass when compared to a traditional limit equilibrium analysis. Some models with large persistence of steeply dipping joints were able to capture the actual failure surface. Softening models were employed in order to mimic the generation and propagation of joints through the rockmass in a continuum; however, only discontinuum models using explicitly defined joints in the model were able to capture the correct failure surface.

41

Nsabimana, Adelit. "Stability of the money demand function and monetary inflation in the East African community." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/9163.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This research attempts to evaluate the stability of money demand functions and estimate monetary inflation models in the East African Community (EAC), using quarterly aggregate data that range from 2000Q1 to 2012Q3. We used Johansen co-integration analysis to estimate and analyse the stability of the M3 money demand model for each country member of the EAC. From this estimation, we derived a country-specific measure of money overhang. We compared its forecasting power of future inflation with that of money stock growth, and money stock available in the economy. Regarding country-specific money demand functions, with the exception of Uganda, we identified a reasonable and stable country-specific M3 money demand model. Also, for predicting future inflation, the estimation results showed that M3 money stock growth is more reliable in Burundi and in Kenya, while M3 money overhang is preferable in Rwanda and M3 money stock in Tanzania. As both country-specific and regional (EAC area) information on monetary quantity growth and its impact on price level is important to know in a monetary union, we considered the EAC area as a single market and attempted to estimate the aggregate (EAC area) demand functions for broad money M2 and M3 using Johansen co-integration analysis. The estimated long-run aggregate money demand models M2 and M3 appeared to be stable over the sample period. However, the aggregate M2 and M3 at the EAC level were proven to be weakly exogenous, which should discard them for consideration at the EAC level as the intermediate targets variables in order to achieve the overall objective of price stability in the EAC region. Instead, short-term interest rate should be given a prominent role in monetary policy framework at the EAC level.

42

Vyambwera, Sibaliwe Maku. "Mathematical modelling of the HIV/AIDS epidemic and the effect of public health education." Thesis, University of Western Cape, 2014. http://hdl.handle.net/11394/3360.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

>Magister Scientiae - MSc
HIV/AIDS is nowadays considered as the greatest public health disaster of modern time. Its progression has challenged the global population for decades. Through mathematical modelling, researchers have studied different interventions on the HIV pandemic, such as treatment, education, condom use, etc. Our research focuses on different compartmental models with emphasis on the effect of public health education. From the point of view of statistics, it is well known how the public health educational programs contribute towards the reduction of the spread of HIV/AIDS epidemic. Many models have been studied towards understanding the dynamics of the HIV/AIDS epidemic. The impact of ARV treatment have been observed and analysed by many researchers. Our research studies and investigates a compartmental model of HIV with treatment and education campaign. We study the existence of equilibrium points and their stability. Original contributions of this dissertation are the modifications on the model of Cai et al. [1], which enables us to use optimal control theory to identify optimal roll-out of strategies to control the HIV/AIDS. Furthermore, we introduce randomness into the model and we study the almost sure exponential stability of the disease free equilibrium. The randomness is regarded as environmental perturbations in the system. Another contribution is the global stability analysis on the model of Nyabadza et al. in [3]. The stability thresholds are compared for the HIV/AIDS in the absence of any intervention to assess the possible community benefit of public health educational campaigns. We illustrate the results by way simulation The following papers form the basis of much of the content of this dissertation, [1 ] L. Cai, Xuezhi Li, Mini Ghosh, Boazhu Guo. Stability analysis of an HIV/AIDS epidemic model with treatment, 229 (2009) 313-323. [2 ] C.P. Bhunu, S. Mushayabasa, H. Kojouharov, J.M. Tchuenche. Mathematical Analysis of an HIV/AIDS Model: Impact of Educational Programs and Abstinence in Sub-Saharan Africa. J Math Model Algor 10 (2011),31-55. [3 ] F. Nyabadza, C. Chiyaka, Z. Mukandavire, S.D. Hove-Musekwa. Analysis of an HIV/AIDS model with public-health information campaigns and individual with-drawal. Journal of Biological Systems, 18, 2 (2010) 357-375. Through this dissertation the author has contributed to two manuscripts [4] and [5], which are currently under review towards publication in journals, [4 ] G. Abiodun, S. Maku Vyambwera, N. Marcus, K. Okosun, P. Witbooi. Control and sensitivity of an HIV model with public health education (under submission). [5 ] P.Witbooi, M. Nsuami, S. Maku Vyambwera. Stability of a stochastic model of HIV population dynamics (under submission).

43

Hagerfors, Jonas. "Jämförelse av beräkningsprogrammen Novapoint Geosuite Stability och Geoslope SLOPE/W med avseende på släntstabilitet." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-384294.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This thesis deals with the difference between two calculation programs for slope stability, namely Geoslope SLOPE/W and Novapoint GeoSuite Stability. The purpose of the thesis is to compare the two calculation programs with regard to the analysis of slope stability, as well as the two programs' handling of data. The two calculation programs use different Limit equilibrium methods to calculate safety factor and sliding surfaces for slopes. It can be expected that the result should be similar to one another, as well as the fact that both the calculation programs use different Limit equilibrium methods, but also when large differences in both safety factor and critical sliding surface give unreliable results. The thesis will also address the factors that may lie behind the fact that a possible stability failure should take place in a slope, as it gives an increased understanding of the analyzes that have been done. The work was carried out by modeling slopes with identical geometric relationships and identical material properties in the two calculation programs, a safety factor and a critical sliding surface for the slopes were developed for both programs and then compared with each other.
Föreliggande examensarbete behandlar skillnaden mellan två beräkningsprogram när det kommer till släntstabilitet, nämligen Geoslope SLOPE/W och Novapoint GeoSuite Stability. Syftet med examensarbetet är att jämföra de båda beräkningsprogrammen avseende vid undersökning av släntstabilitet, samt de två programmens hantering av data. De två beräkningsprogrammen använder sig av liknande Limit equilibrium-metoder för att beräkna säkerhetsfaktor samt glidytor för slänter. Man kan förvänta sig att resultatet bör vara varandra likt då dels att de både beräkningsprogrammen använder sig av liknande Limit equilibrium-metoder, men också då stora skillnader i både säkerhetsfaktor och kritisk glidyta ger opålitligt resultat. Examensarbetet kommer även ta upp de faktorer som kan ligga bakom att ett eventuellt brott ska ske i en slänt, då det ger ökad förståelse för de analyser som gjorts. Arbetet utfördes genom att slänter med identiska geometriska relationer samt identiska materialegenskaper modellerades i de båda beräkningsprogrammen, en säkerhetsfaktor samt kritisk glidyta för slänterna togs fram för båda programmen och jämfördes sedan med varandra.

44

Gerhardsson, Andreas. "Stability of monoatomic nanowires : a first-principles study." Thesis, Linköpings universitet, Teoretisk Fysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68764.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Monoatomic chain formation for Ag, Au, Pd and Pt has been investigated using a model for the tip structure. First-principles calculations, mostly spin polarized, were performed within the framework of the Density Functional theory. Results are presented and discussed on the basis of the electronic structure. Tendencies for chain formation were noted for Ag, Au and Pt.

45

Franca, Paulo Ricardo Behrens da. "Analysis of slope stability using limit equilibrium and numerical methods with case examples from the Águas Claras Mine, Brazil." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq20637.pdf.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Nookhwun, Nuwat. "An analysis of the relationship between monetary policy, business cycles and financial stability." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:d56b4883-1eee-4d26-9b12-554414791969.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The thesis sheds light on key policy issues emerging from the recent Global Financial Crisis. The first chapter studies whether expansionary monetary policy contributes to bank risk-taking, in the case of Asia. I rely on panel data analysis covering 432 banks in 9 Asian countries over the year 2000-2011. The ratio of risky assets to total assets serves as a risk-taking indicator. The results support the existence of the bank risk-taking channel, which is more pronounced for banks listed on the stock market. I also report new findings with respect to how banks take more risk following monetary expansion. Importantly, evidence of excessive leverage is not found. The second chapter constructs a model for analyzing bank risk-taking. I embed firm heterogeneity, endogenous default risk and capital adequacy regulation into both RBC and NK DSGE models. A subset of the firms can partially default on their loans obligation but subject to non-pecuniary default penalty. With those financial frictions in place, I find that standard macroeconomic shocks can induce banks to engage in higher risk-taking. The chapter then explores the effectiveness of several macro-prudential tools in mitigating risk-taking. I find countercyclical capital buffers and risky to total asset ratio targeting to be effective. The third chapter emphasises the spillover effects of shocks originating in the housing and financial market on the real economy. I embed endogenous mortgage default into a New Keynesian model that features housing and the banking sector. The latter faces capital regulation. We study two key shocks, namely shocks to the variance of idiosyncratic housing shock and shocks to the penalty on capital regulation. Both are instrumental in causing a surge in mortgage default and loans risk premium, which constrains bank lending activity. The chapter later introduces three macroprudential measures to explore whether they improve economic stability and welfare.

47

Ferrara, Marco Ph D. Massachusetts Institute of Technology. "Axisymmetric equilibrium and stability analysis in Alcator C-Mod, including effects of current profile, measurement noise and power supply saturation." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53265.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 147-150).
The vertical position of elongated tokamak plasmas is unstable on the time scale of the eddy currents in the axisymmetric conducting structures. In the absence of feedback control, the plasma would drift vertically and quench on the wall, a situation known as Vertical Displacement Event (VDE), with serious consequences for machine integrity. As tokamaks approach reactor regimes, VDE's cannot be tolerated: vertical feedback control must be robust against system uncertainty and the occurrence of noise and disturbances. At the same time, adaptive routines should be in place to handle unexpected events. The problem of robust control of the vertical position can be formulated in terms of identifying which variables affect vertical stability and which ones are not directly controlled/controllable; identifying the physical region of these variables, and the corresponding most unstable equilibria; and designing the control system to stabilize all equilibria with sufficient margin. The margin should be enough to allow the system to tolerate realistic scenarios of noise and disturbances. A set of metrics is introduced to characterize the problem of vertical stability: the stability margin describes the plasma-wall interaction and the open-loop growth rate; the maximum controllable displacement looks at the vertical stabilization power supplies and their ability to handle noise and off-normal events; the gain and phase margins quantify the linear stability of the feedback control loop.
(cont.) The dependence of these metrics on relevant plasma parameters is proven with analytic calculations and numerical simulations: in particular, it is shown that the stability margin is a decreasing function of the plasma internal inductance, for a given plasma elongation. An upper bound of the value of the internal inductance is derived and validated with database analysis, which describes the most unstable equilibrium for given values of the external elongation and the edge safety factor. The stability metrics are evaluated for typical and ITER-like C-Mod plasmas to give an example of the C-Mod operational space and of feasible control conditions. The vertical stabilization system should be able to tolerate realistic scenarios of noise and disturbances. The main sources of noise and pick-ups in Alcator C-Mod are identified and their effects on the measurement and control of the vertical position are evaluated. Broadband noise may affect controllability of C-Mod plasmas at limit elongations and may become an issue with high-order controllers, therefore two applications of Kalman filters are investigated. A Kalman filter is compared to a state observer based on the pseudo-inverse of the measurement matrix and proves to be a better candidate for state reconstruction for vertical stabilization, provided adequate models of the system, the inputs, the intrinsic and measurement noise and an adequate set of diagnostic measurements are available. A single-input single-output application of the filter for the vertical observer rejects high frequency noise without destabilizing high-elongation plasmas, however does not match the performance of an optimized low-pass filter.
(cont.) Aggressive control targets and large off-normal events can cause a control current to rail. The magnetic topology is consequently perturbed and the plasma might become uncontrollable. An adaptive anti-saturation control routine is demonstrated which avoids an impending saturation by interpolating in real-time to a safe equilibrium. This approach becomes necessary when poor redundancy of control coils may require mid-shot pulse rescheduling, as opposed to an adaptation in control.
by Marco Ferrara.
Ph.D.

48

JADANZA, RICCARDO DANILO. "Morse index and linear stability of relative equilibria in singular mechanical systems." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2599754.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

We have focussed on the study of the linear stability of some particular periodic orbits (called relative equilibria) in planar singular mechanical systems with SO(2)-symmetry, and we have achieved the results using quite advanced mathematical techniques. These involve some homotopy invariants, such as the spectral flow, and some index theory, namely a theorem stating the equality between the Morse index of an orbit seen as a critical point of a Lagrange action functional and the Maslov index of the fundamental solution of the associated Hamiltonian system. Moreover, what we have found meets one of its most important applications in a generalised n-body problem, that is, an n-body problem with a more general potential.

49

Chakrabarti, Subhadip. "Network Formation and Economic Applications." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/11256.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Networks, generically, refer to any application of graph theory in economics. Consider an undirected graph where nodes represent players and links represent relationships between them. Players can both form and delete links by which we mean that they can both form new relationships and terminate existing ones. A stable network is one in which no incentives exist to change the network structure. There can be various forms of stability depending on how many links players are allowed to form or delete at a time. Under strong pairwise stability, each player is allowed to delete any number of links at a time while any pair of players can form one link at a time. We introduce a network-value function, which assigns to each possible network a certain value. The value is allocated according to the component-wise egalitarian allocation rule, which divides the value generated by a component equally among members of the component (where a component refers to a maximally connected subgraph). An efficient network is one that maximizes the network value function. We show that there is an underlying conflict between strong pairwise stability and efficiency. Efficient networks are not necessarily strongly pairwise stable. This conflict can be resolved only if value functions satisfy a certain property called "middlemen-security". We further find that there is a broad class of networks called "middlemen-free networks" for which the above condition is automatically satisfied under all possible value functions. We also look at three network applications. A peering contract is an arrangement between Internet Service Providers under which they exchange traffic with one another free of cost. We analyze incentives for peering contracts among Internet service providers using the notion of pairwise stability. A hierarchy is a directed graph with an explicit top-down structure where each pair of linked agents have a superior-subordinate relationship with each other. We apply the notion of conjunctive permission value to demonstrate the formation of hierarchical firms in a competitive labor market. Comparative or targeted advertising is defined as any form of advertising where a firm directly or indirectly names a competitor. We also examine a model of targeted advertising between oligopolistic firms using non-cooperative game theoretic tools.
Ph. D.

50

Vereen, Kalimah. "An SCIR Model of Meningococcal Meningitis." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/710.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

A model for meningitis is developed by adding a class of carriers to the basic SIR model. This model is used to analyze the impact a vaccination program can have on the health of the population of epidemic prone countries. Analysis of the model shows the local stability of the disease free equilibrium, the existence of an endemic equilibrium and computation of the reproduction number, ℜ0 . Using a MATLAB program we simulate a time course of the model using parameters gathered from the World Health Organization. The numerical solution demonstrates that our reproduction number was correct. We thenconcluded that a high infection transmission rate requires a high vaccine rate.

Дисертації з теми "Equilibrium stability"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями