Dissertations / Theses on the topic 'Bubbles'
To see the other types of publications on this topic, follow the link: Bubbles.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Bubbles.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Pierce, Michael M. (Michael Murray). "Japanese Real Estate Investment Trusts : champagne bubbles or price bubble." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33179.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaves 79-81).
In September 2001 the Japanese real estate industry marked a new era of real estate investments by issuing on the Tokyo Stock Exchange the first Japan Real Estate Investment Trust (JREIT). The initial JREIT performance was not so impressive. Now, as the Japanese economy continues to recover and more investors are looking to real estate securitization as a means of limiting balance sheet liability and increase real estate investment liquidity, the JREIT is becoming a popular investment vehicle. On the surface the public securitization of real estate seems a great opportunity for the average investor to participate in real estate investment while keeping liquidity. What is the real story behind the JREIT: Are the assets in the JREIT overpriced? Is the race to issue new JREITs forming a price bubble in the Tokyo central business district? Is the JREIT a safe investment, or it just a way for real estate firms to pass off the associated risks of overpriced real estate? This paper will consider the status of the Japanese economy, the real estate industry, and the JREIT market from its beginnings to current levels.
by Michael M. Pierce.
S.M.
2
Hogan, C. J. "Cosmic Radiation Bubbles|Cosmic Structure from Radiation-Blown Bubbles." Steward Observatory, The University of Arizona (Tucson, Arizona), 1988. http://hdl.handle.net/10150/623920.
Full text
3
McMahon, Andrew Martin. "Modelling the flow behaviour of gas bubbles in a bubble column." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/5441.
Full textAbstract:
Includes abstract.Includes bibliographical references (leaves 96-99).
The bubble column reactor is commonly used in industry, although the fluid dynamics inside are not well understood. The challenges associated with solving multi phase flow problems arise from the complexity of the governing equations which have to be solved, which are typically mass, momentum and energy balances. These time-dependent problems need to include effects of turbulence and are computationally expensive when simulating the hydrodynamics of large bubble columns. In an attempt to reduce the computational expense in solving bubble column reactor models, a "cell" model is proposed which predicts the velocity flow field in the vicinity of a single spherical bubble. It is intended that this model would form the fundamental building block in a macroscale model framework that does predict the flow of multiple bubbles in the whole column. The non-linear Navier-Stokes (NVS) equations are used to model fluid flow around the bubble. This study focusses on the Reynolds number range where the linear Stokes equations can be used to accurately predict the flow around the bubble. The Stokes equations are mathematically easier to solve than the NVS equations and are thus less computationally expensive. The validity of the NVS model was tested against experimental data for the flow of water around a solid sphere and was found to be in close agreement for the Reynolds number range 25 to 80. The simulation results from the Stokes flow model were compared with those from the NVS flow model and were similar at Reynolds numbers below 1. The application is then in the partitioning of the bubble column into regions governed by either Stokes or NVS equations.
4
Buchsteiner, Henri. "Valuation and bubbles." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610800.
Full text
5
Chong, Jieyang. "Dating mildly explosive bubbles using a rolling window." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/98930/1/Jieyang_Chong_Thesis.pdf.
Full textAbstract:
Recent research on date-stamping asset pricing bubbles has focussed on the use of recursive and rolling-recursive regressions. This thesis evaluates a simpler and perhaps neglected approach to the date-stamping of bubbles – the rolling window unit root testing approach – and provides a comprehensive comparison of its performance against the recursive and rolling-recursive methods. The rolling window approach is easier to implement than the recursive and rolling-recursive methods in that it is computationally less demanding and does not require non-standard limit theory. Results of simulation experiments as well as empirical applications suggest that the rolling window approach is superior to the two alternative methods.
6
Yurdakul, Saruhan. "Electrophoresis of electrogenerated bubbles." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/58542.
Full textAbstract:
The fundamental understanding of the interfacial charge on gas bubbles and the consequences of such charge are essential in understanding the behaviour of physicochemical systems involving liquid/gas and solid/liquid/gas interfaces. Such interfaces are involved in many industrial processes such as electrolytic gas evolution, particle flotation and bubble coalescence. The knowledge of such interfaces will aid mass transfer calculations. This thesis describes the application of a laser Doppler anemometer (LDA) system to the measurement of bubble electrophoretic mobilities, giving a measure of adsorbed charge. Single bubbles were electrogenerated in surfactant-free electrolytes, characterised by bubble rise rates, and their behaviour investigated in an electric field applied parallel to the direction of rise, so that, depending on the field direction, an increase or a decrease in the rise velocities was obtained. This field orientation served to decouple the hydrodynamic and field-induced charge polarisation. The velocity measurements using LDA showed a large degree of scatter despite numerous modifications to the optics and the signal processing. This culminated in the belief that a double LDA system was necessary to optimise the reliability and accuracy of the technique. Measurements using a Kodak high speed camera and recording system showed that the bubbles were negatively charged over the pH range studied (3-11), as indicated by their migration towards the anode under the influence of an applied electric field, with mobilities showing a radius and field dependence, implying that the adsorbed charge at the gas/electrolyte interface was mobile and polarisable. Large mobilities (10-60 x 10"® m2 s"^ V"^) were observed in comparison with results from previous bubble electrophoresis experiments with lateral fields. This was explained in terms of the enhanced charge polarisation occurring in the parallel electric field to the rise vector. A qualitative explanation for the decoupling of the hydrodynamic and field-induced charge polarisation has also been provided. In a separate series of experiments, under sufficient field conditions to overcome buoyancy forces, rising bubbles were stopped and held stationary. It was shown by extrapolation that bubbles possessed an iso electric point between pH 2 and 3, being positively charged below pH 2 and negatively charged above pH 3, supporting the hypothesis that the preferential adsorption of OH /H+ ions gives rise to the net charge. A laser reflection technique was investigated to measure the thickness of a liquid film formed between a bubble and the planar gas/electrolyte interface when they are in close proximity of each other. Preliminary investigations on macroscopic soap films showed the technique to be suitable for studying film thinning rates, though further refinement is necessary to study microscopic transient films. Electrophoresis measurements using a high speed camera have shown that bubbles preferentially adsorbed OH-/H+ ions from the solution in the absence of surfactants. This charge resided on a highly mobile interface and could be polarised by the actions of the hydrodynamics and the electric field. The laser Doppler anemometer system requires further development to achieve more accurate bubble velocity profiles in order to detect the small changes that occur.
7
Geerolf, François. "Bubbles and asset supply." Paris, Institut d'études politiques, 2013. http://www.theses.fr/2013IEPP0029.
Full textAbstract:
Ce travail de thèse est composé de cinq chapitres unis par une idée commune; celle que l'accumulation de capital n'est plus le facteur limitant de la croissance dans nos économies dévelopées, ce que je montre dans le chapitre 1. Dans ce contexte, un excès d'épargne peut naturellement conduire à l'émergence de bulles spéculatives. En particulier, ces bulles ont davantage tendance à apparaître sur les actifs qui peuvent être utilisés en garantie pour les emprunts, et ceux qui sont difficiles à vendre à découvert - notamment les actifs immobiliers. Je montre aussi que les bulles rationnelles peuvent très bien croître plus rapidement que le taux d'intérêt, et exploser de manière endogène aux contraintes institutionnelles. Une politique monétaire accommodante peut favoriser l'émergence de ces bulles comme les décourager, suivant le type d'actifs considéré (chapitre 2). Dans le chapitre 3, je montre que les bulles spéculatives peuvent amener simultanément une hausse de la consommation, de la production, de l'investissement, et des heures travailllées; elles pourraient donc être une alternative aux chocs de productivité pour expliquer les cycles macroéconomiques. Dans les économies ouvertes, les bulles immobilières expliquent ainsi les variations de comptes courants comme on le voit dans le chapitre 4, les actifs immobiliers étant majoritairement détenus par les résidents. Enfin, le chapitre 5 montre que la taxation du capital joue ici un rôle ambigu: d'un côté, elle décourage l'accumulation du capital; mais de l'autre, elle rend les liquidités disponibles pour l'accumulation du capital en diminuant l'offre d'actifs, notamment celle liée à la rente foncièreThis dissertation is composed of five chapters, all of which are united by the idea that capital is not scarce any more in our economies, and that the resulting low interest rates environment can open up the possibility for the emergence of rational speculative bubbles. The first chapter of the thesis uses national accounts and balance sheets data to show that capital income coming from investment is much lower than was previously thought, always lower than investment in Japan, which points to the idea of excess savings. In the second chapter of this thesis, I show that leverage and short-sales constraints are crucial in understanding the formation and the location of rational speculative bubbles. It generates procyclical leverage without the assumption of "scary bad news", return predictability, and equilibrium default. It helps us think about the effect of margin requirements, financial deregulation, and that of central bank's actions on asset prices. In chapter 3, I show that rational speculative bubbles can drive the business cycle, inducing positive comovement between consumption, hours worked, investment and production, thus being an alternative to productivity shocks to drive macroeconomic fluctuations. The results in chapter 4 suggest that asset overvaluations could drive international business cycles as well, inducing current account deficits. Finally, the chapter 5 is a first step towards thinking about capital taxation in a world with very abundant savings: on the one hand, capital taxation crowds out capital accumulation by discouraging savings, but on the other hand it reduces asset supply and thus helps free resources for investment
8
Yang, Ching-Ting. "Stretching bubbles: pressure releasing." Thesis, University of Iowa, 2017. https://ir.uiowa.edu/etd/5686.
Full textAbstract:
My pieces are inspired by bubble wrap. I was inspired by a Japanese toy which you can squeeze it unlimited times to help people to release there pressures. As the same way, some people like to pop the bubbles from bubble wraps. I used this idea to make my jewelry projects to represent how people act while they suffer from stress and how they release pressure. Based on this idea, you can see the shapes or forms of my works have various possibilities, some of them are simple but others are complicated assemblies. People have various ways to handle stress. Wearing jewelry shows not only their personality but also their emotion. While they sometimes choose their jewelry pieces based on beauty they also choose them based on their emotions.
I transformed two-dimensional flat sheets of bubble wrap into three-dimensional forms by stretching and folding them. I also experimented with various materials including plastic, resin, metal, and wood. Most of my works are brooches, rings, and necklaces.
9
Yang, Chun. "Attachment of fine gas bubbles onto a solid surface and electrokinetics of gas bubbles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0013/NQ60043.pdf.
Full text
10
憲司, 吉田. "Study on non-spherical vibration of bubbles and interaction among bubbles in ultrasonic field." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB10315263/?lang=0, 2009. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB10315263/?lang=0.
Full text
11
Barkey, Wolf Frederik Dirk. "Swept and unswept separation bubbles." Thesis, University of Cambridge, 1987. https://www.repository.cam.ac.uk/handle/1810/250906.
Full textAbstract:
The effect of sweep on separation bubbles as occurring in the subsonic flows past thin flat plates with rectangular leading edges has been studied experimentally. The distance between separation and reattachment, at high Reynolds number, was about 5.5 times the plate thickness in the flow region undisturbed by end effects. This distance was independent of sweepback for sweep angles up to and including 45o. The chordwise distribution of a static-pressure coefficient and a coefficient of the intensity of the static-pressure fluctuations, both measured on the surface of the plate and based upon the free-stream velocity component normal to the leading edge, were independent of the sweep angle up to and including 30o to a first approximation. The spectra of the static-pressure fluctuations, however, displayed some qualitative changes with increasing sweep angle. The distribution of a coefficient of the chordwise skin-friction component, based upon the free-stream velocity component normal to the leading edge, was independent of sweep up to and including 30o to a crude first approximation. The chordwise velocity profiles non-dimensionalised by the local external chordwise velocity component, were independent of sweep up to and including 45o in the separation bubble but downstream of reattachment small but persistent changes occurred with increasing sweep angle. Smoke-flow visualisations in the swept and the unswept flow at low Reynolds number displayed the presence of typical vortex loops in the reattachment region, many of which broke up and were partially entrained into the separation bubble.
12
Nedelcu, Sorin. "Mathematical models for financial bubbles." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-178610.
Full textAbstract:
Financial bubbles have been present in the history of financial markets from the early days up to the modern age. An asset is said to exhibit a bubble when its market value exceeds its fundamental valuation. Although this phenomenon has been thoroughly studied in the economic literature, a mathematical martingale theory of bubbles, based on an absence of arbitrage has only recently been developed. In this dissertation, we aim to further contribute to the developement of this theory.
In the first part we construct a model that allows us to capture the birth of a financial bubble and to describe its behavior as an initial submartingale in the build-up phase, which then turns into a supermartingale in the collapse phase. To this purpose we construct a flow in the space of equivalent martingale measures and we study the shifting perception of the fundamental value of a given asset.
In the second part of the dissertation, we study the formation of financial bubbles in the valuation of defaultable claims in a reduced-form setting. In our model a bubble is born due to investor heterogeneity. Furthermore, our study shows how changes in the dynamics of the defaultable claim's market price may lead to a different selection of the martingale measure used for pricing. In this way we are able to unify the classical martingale theory of bubbles with a constructive approach to the study of bubbles, based on the interactions between investors.Finanz-Blasen sind seit der Entstehung der Finanzmärkte bis zur heutigen Zeit gegenwärtig. Es gilt, dass ein Vermögenswert eine Finanzblase aufweist, sobald dessen Marktwert die fundamentale Bewertung übersteigt. Obwohl dieses Phänomen in der Wirtschaftsliteratur ausgiebig behandelt wurde, ist eine mathematische Martingaltheorie von Blasen, die auf der Abwesenheit von Arbitragemöglichkeiten beruht, erst in letzter Zeit entwickelt worden. Das Ziel dieser Dissertation ist es einen Beitrag zur Weiterentwicklung dieser Theorie zu leisten. Im ersten Abschnitt konstruieren wir ein Model mit Hilfe dessen man die Entstehung einer Finanz-Blase erfassen und deren Verhalten anfänglich als Submartingal in der build-up phase beschrieben werden kann, welches dann in der collapse phase zu einem Supermartingal wird. Zu diesem Zweck entwickeln wir einen Zahlungsstrom im Raum der äquivalenten Martingalmaße und wir untersuchen die zu dem Vermögenswert passende Verschiebung des fundamentalen Werts. Der zweite Teil der Dissertation beschäftigt sich mit der Bildung von Finanz-Blasen bei der Bewertung von Forderungen, die mit Ausfallrisiken behaftet sind, in einer reduzierten Marktumgebung. In unserem Model ist die Entstehung einer Blase die Folge der Heterogenität der Investoren. Des Weiteren zeigen unsere Untersuchungen, inwieweit Veränderungen der Dynamik des Marktpreises einer risikobehafteten Forderung zu einer Veränderung des zur Bewertung verwendeten Martingalmaß es führen kann. Dadurch sind wir in der Lage die klassische Martingaltheorie von Finanz-Blasen mit einem konstruktivem Ansatz zur Untersuchung von Finanz-Blasen zu vereinigen, der auf den Interaktionen zwischen Marktteilnehmern basiert.
13
Munro, James. "Coalescence of bubbles and drops." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/288543.
Full textAbstract:
When two fluid drops come close enough together to touch, surface tension quickly pulls the drops together into one larger drop. This is an example of a singular fluid flow, as the topology of the interface changes at the moment of contact. Similarly, when a pair of bubbles touch, the surface topology changes and a singular flow begins. Since the stress from surface tension depends on the surface curvature, these singularities are often characterised by divergent fluid velocities. Experimental observation or numerical simulation of these flows is therefore difficult due to the high velocities and small lengthscales. In this thesis, I will find multi-scale theoretical solutions for the singular flows during the initial stages of the coalescence of bubbles and drops, solving for the velocity field in the fluid and the rate of coalescence. Each solution has several lengthscales, and on each lengthscale, we must solve some form of the Navier--Stokes equations. I will employ a variety of analytical and numerical techniques to solve for the flow on each scale. These asymptotic solutions are valid at early times; future numerical simulations of the subsequent flow could be initialised with these solutions, rather than the actual singularity. In the course of solving for these singular flows, I will also describe the solution for the motion of a stretched fluid edge, the retraction of a narrow fluid wedge, the capillary flow around a parabola, and the effect of a time-dependent force on a fluid half-space. These fundamental flows have applications outside of coalescence, which I will outline throughout the thesis.
14
Cox, Raymond John. "Inert gas bubbles in aluminium." Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/847339/.
Full textAbstract:
Thin aluminium foils have been implanted, primarily with argon ions but also with other inert gases. In the as implanted condition and after annealing to a series of temperatures, the clustering of the inert gases to form bubbles and the subsequent bubble growth have been studied by analytical electron microscopy. The consecutive use of transmission electron microscopy with X-ray analysis and electron diffraction has enabled measurements of the proportion of gas located in the visible bubble population and the gas density within bubbles. The information obtained using these techniques has indicated that sub-microscopic argon bubbles are immobile and may remain so up to temperatures as high as 500°C. Together with this observation it is shown that there is a considerable delay in achieving the equilibrium thermal vacancy concentration. It has also been found that at temperatures close to the melting point gas resolution will cause a net loss of gas from bubbles to the metal/oxide interface at the foil surface. During ion implantations at elevated temperatures it was observed that precipitates, later found to be oxides, were associated with bubbles. This led to the realisation that oxygen would be knocked-in from the surface oxide during all ion implantation experiments. Further experiments were carried out to assess the effects of a surface oxide on inert gas bubble behaviour. Amongst other effects the oxide will slow down bubble growth by migration and coalescence as it will inhibit diffusion at the bubble surface.
15
Mårtensson, Måns. "User perspectives on filter bubbles." Thesis, Malmö högskola, Fakulteten för kultur och samhälle (KS), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-21656.
Full textAbstract:
This study derives from a located a gap in the methodological coverage and ways inwhich filter bubbles previously have been problematised. It is structured to through auser perspective to find ways in which users navigation and experience is influencedby personalised consumption. Through interview studies of digital natives, two mainfocuses of navigation and experience have been chosen with the aim to bring nuancedperspectives to the current state of filter bubbles. The first, using the theoreticalframework of uses and gratifications sets out to answer: In what ways do digitalnatives navigation contest the personalisation of their news consumption?I found that most interview participants have developed both thorough and individualways of navigating in their news consumption process. Personalising filters are bysome seen as assets to optimize content and by others as thresholds that enforcerestrictive behaviour. However, most participants seem to be mildly concerned orunaware of personalising features in their news navigation.The second focus of user experience seeks to clarify the motives behind usernavigation by answering: In what ways do digital natives experience of theirnavigation contest the personalisation of theirs and others news consumption?I find that some participants consider the impact of their own interactions withtheir personalised consumption, but do not understand the extents of it. I also find thatshared social norms and traditional media permeate the critical view that allparticipants carry with them through their navigation. I use these findings to introducea suggestion to problematise personalisation through user experience as a way ofbenchmarking filter bubbles that to my knowledge have not been used before.Lastly, by looking at the navigations and experiences of the participantsthrough a theoretical framework of power, I conceptualise their interactions asmotives of counter power towards a personalisation to answer:How can the motives of digital natives navigation be contextualised as acts of counterpower towards their personalised news consumption?I identify both interactions as motives of counter power with some participants’ newsconsumption, and experiences of subjectivity to power in others. But can’t determineto which extents it relates to the personalisation or other factors in the participantsnews consumption.
16
Ramanan, Sisir. "Essays in asset price bubbles." Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7357/.
Full textAbstract:
This thesis studies the field of asset price bubbles. It is comprised of three independent chapters. Each of these chapters either directly or indirectly analyse the existence or implications of asset price bubbles. The type of bubbles assumed in each of these chapters is consistent with rational expectations. Thus, the kind of price bubbles investigated here are known as rational bubbles in the literature. The following describes the three chapters. Chapter 1: This chapter attempts to explain the recent US housing price bubble by developing a heterogeneous agent endowment economy asset pricing model with risky housing, endogenous collateral and defaults. Investment in housing is subject to an idiosyncratic risk and some mortgages are defaulted in equilibrium. We analytically derive the leverage or the endogenous loan to value ratio. This variable comes from a limited participation constraint in a one period mortgage contract with monitoring costs. Our results show that low values of housing investment risk produces a credit easing effect encouraging excess leverage and generates credit driven rational price bubbles in the housing good. Conversely, high values of housing investment risk produces a credit crunch characterized by tight borrowing constraints, low leverage and low house prices. Furthermore, the leverage ratio was found to be procyclical and the rate of defaults countercyclical consistent with empirical evidence. Chapter 2: It is widely believed that financial assets have considerable persistence and are susceptible to bubbles. However, identification of this persistence and potential bubbles is not straightforward. This chapter tests for price bubbles in the United States housing market accounting for long memory and structural breaks. The intuition is that the presence of long memory negates price bubbles while the presence of breaks could artificially induce bubble behaviour. Hence, we use procedures namely semi-parametric Whittle and parametric ARFIMA procedures that are consistent for a variety of residual biases to estimate the value of the long memory parameter, d, of the log rent-price ratio. We find that the semi-parametric estimation procedures robust to non-normality and heteroskedasticity errors found far more bubble regions than parametric ones. A structural break was identified in the mean and trend of all the series which when accounted for removed bubble behaviour in a number of regions. Importantly, the United States housing market showed evidence for rational bubbles at both the aggregate and regional levels. In the third and final chapter, we attempt to answer the following question: To what extend should individuals participate in the stock market and hold risky assets over their lifecycle? We answer this question by employing a lifecycle consumption-portfolio choice model with housing, labour income and time varying predictable returns where the agents are constrained in the level of their borrowing. We first analytically characterize and then numerically solve for the optimal asset allocation on the risky asset comparing the return predictability case with that of IID returns. We successfully resolve the puzzles and find equity holding and participation rates close to the data. We also find that return predictability substantially alter both the level of risky portfolio allocation and the rate of stock market participation. High factor (dividend-price ratio) realization and high persistence of factor process indicative of stock market bubbles raise the amount of wealth invested in risky assets and the level of stock market participation, respectively. Conversely, rare disasters were found to bring down these rates, the change being severe for investors in the later years of the life-cycle. Furthermore, investors following time varying returns (return predictability) hedged background risks significantly better than the IID ones.
17
Evripidou, Andria C. "Essays on speculative financial bubbles." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49811/.
Full textAbstract:
This thesis contributes to the study of long-run relationships between financial assets. We develop a methodology for testing the hypothesis of co-bubbling behaviour in two series, employing a variant of the stationarity test of Kwiatkowski et al. (1992) which uses a conditional 'wild' bootsrap scheme to control size. We subsequently use our method to test for the presence of co-bubbles in a series of different markets. We look at commodities such as gold and silver and the housing market. There is a plethora of research on the efficacy of unit root tests for detecting explosive rational asset price bubbles. However, the migration of these bubbles and the possibility of co-bubbling behaviour of two series have seldom been researched. In the second chapter of this thesis we apply our model to the commodities market and find that the prices of gold and silver co-bubble in the period following the financial crisis. In the third chapter we investigate the migration of speculative housing bubbles between UK geographic regions. In the third chapter we analyse the co-bubbling relationship between rental and housing prices. We find that an explosive bubble behaviour in rental prices will lead to a bubble behaviour in house prices. The two series co-bubble over a period of time of around two years.
18
Moore, Lowell. "Bubbles matter: An assessment of the contribution of vapor bubbles to melt inclusion volatile budgets." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/47784.
Full textAbstract:
H2O and CO2 concentrations of the glass phase in melt inclusions (MI) are commonly used both as a barometer and to track magma degassing behavior during ascent due to the strong pressure dependence of H2O and CO2 solubilities in silicate melts. A requirement for this method to be valid is that the glass phase in the MI must represent the composition of the melt that was originally trapped. However, melt inclusions commonly contain a vapor bubble that formed after trapping. Such bubbles may contain CO2 that was originally dissolved in the melt. In this study, we determined the contribution of CO2 in the vapor bubble to the overall CO2 content of MI based on quantitative Raman analysis of the vapor bubbles in MI from the 1959 Kilauea Iki, 1960 Kapoho, 1974 Fuego volcano, and 1977 Seguam Island eruptions. The bubbles contain up to 90% or more of the total CO2 in some MI. Reconstructing the original CO2 content by adding the CO2 in the bubble back into the melt results in an increase in CO2 concentration by as much an order of magnitude (1000s of ppm), corresponding to trapping pressures that are significantly greater (by 1 to >3 kbars) than one would predict based on analysis of the volatiles in the glass alone. Many MI also showed the presence of a carbonate mineral phase; failure to include its contained CO2 when reconstructing the CO2 content of the originally trapped melt may introduce significant errors in the calculated volatile budget.Master of Science
19
Parini, Michael R. "Biofilm Removal Using Bubbles and Sound." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd958.pdf.
Full text
20
Bjarnason, Thorir. "Stochastic volatility, convex prices and bubbles." Thesis, Uppsala University, Department of Mathematics, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-120913.
Full text
21
Ebiogwu, Ambrose Chika. "Metal refining reactions in rising bubbles." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37680.
Full text
22
Henry, Christine L., and christine henry@alumni anu edu au. "Bubbles, Thin Films and Ion Specificity." The Australian National University. Department of Applied Mathematics, Research School of Physical Sciences and Engineering, 2009. http://thesis.anu.edu.au./public/adt-ANU20091117.073007.
Full textAbstract:
Bubbles in water are stabilised against coalescence by the addition of salt. The white froth in seawater but not in freshwater is an example of salt-stabilised bubbles. A range of experiments have been carried out to investigate this simple phenomenon, which is not yet understood.¶
The process of thin film drainage between two colliding bubbles relates to surface science fields including hydrodynamic flow, surface forces, and interfacial rheology. Bubble coalescence inhibition also stands alongside the better known Hofmeister series as an intriguing example of ion specificity: While some electrolytes inhibit coalescence at around 0.1M, others show no effect. The coalescence inhibition of any single electrolyte depends on the combination of cation and anion present, rather than on any single ion.¶
The surfactant-free inhibition of bubble coalescence has been studied in several systems for the first time, including aqueous mixed electrolyte solutions; solutions of biologically relevant non-electrolytes urea and sugars; and electrolyte solutions in nonaqueous solvents methanol, formamide, propylene carbonate and dimethylsulfoxide. Complementary experimental approaches include studies of terminal rise velocities of single bubbles showing that the gas-solution interface is mobile; and measurement of thin film drainage in inhibiting and non-inhibiting electrolyte solution, using the microinterferometric thin film balance technique.¶
The consolidation of these experimental approaches shows that inhibiting electrolytes act on the non-equilibrium dynamic processes of thin film drainage and rupture between bubble surfaces and not via a change in surface forces, or by ion effects on solvent structure. In addition, inhibition is driven by osmotic effects related to solute concentration gradients, and ion charge is not important.¶
A new model is presented for electrolyte inhibition of bubble coalescence via changes to surface rheology. It is suggested that thin film stabilisation over a lifetime of seconds,
is caused by damping of transient deformations of film surfaces on a sub-millisecond timescale. This reduction in surface deformability retards film drainage and delays film rupture. It is proposed that inhibiting electrolyte solutions show a dilational surface viscosity, which in turn is driven by interfacial concentration gradients. Inhibiting electrolytes have two ions that accumulate at the surface or two ions that are surface excluded, while non-inhibiting electrolytes have more evenly distributed interfacial solute. Bubble coalescence is for the first time linked through this ion surface partitioning, to the ion specificity observed at biological interfaces and the wider realm of Hofmeister effects.¶
23
Berg, Thomas Hendrik van den. "Theeffect of bubbles on developed turbulence." Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/57626.
Full text
24
Durga, Kalpana Priyadarsini. "Stabilisation of bubbles using natural fibres." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521450.
Full text
25
Steele, Corre. "Popping Bubbles: Cryptanalysis of Homomorphic Encryption." Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-theses/453.
Full textAbstract:
Imagine an encryption scheme where it is possible to add and multiply numbers without any knowledge of the numbers. Instead one could manipulate encryptions of the numbers and then the decryption of the result would give the result of the arithmetic on the original numbers. Encryption algorithms with this property are called homomorphic and have various applications in cloud computing. Homomorphic encryption schemes exist but are generally so inefficient that they are not practical. This report introduces a toy cryptosystem called Bubbles: a somewhat homomorphic encryption scheme created by Professor Martin and Professor Sunar at Worcester Polytechnic Institute. We will show that the original scheme is insecure and may be efficiently "popped". We will then examine two variations of the scheme that introduce noise to increase security and show that Bubbles is still vulnerable except when parameters are carefully chosen. However these safe parameter choices make Bubbles more inefficient than other recent homomorphic schemes.
26
Harfield, Caroline Jane. "Bubbles : sensors for the micro world." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:540aa6cc-e381-4a10-9750-739b065b5668.
Full textAbstract:
It has been proposed that coated gas microbubbles, currently used as ultrasound contrast agents could also be used as microscale sensors due to the sensitivity of their acoustic response to changes in their environment. However, their behaviour is not fully understood and there remains considerable scope for improving their characterisation. The aim of this thesis is to improve the theoretical description of microbubble dynamics under ultrasound excitation with the ultimate aim of assessing the regimes in which they could be exploited most effectively as sensors. Previous theoretical and experimental work relating to the confinement and acoustic excitation of microbubbles is reviewed. Specifically, optical trapping as a method for the isolation and manipulation of individual bubbles is studied for use in developing a sensor. An assessment of the existing models’ validity is undertaken. This is followed by the development of models for optical trapping of single microbubbles, and the coupled radial and translational motion of a microbubble under ultrasound excitation, which includes time dependent phenomena. The latter model is used to perform a sensitivity analysis to determine the uncertainty associated with using microbubbles as sensors. The potential for uniquely characterising the shell of the microbubble from experimental data is also assessed. Subsequent chapters present the results from a combination of computer simulations and experimental data, used to develop and assess the validity of the new models for describing microbubble behaviour. Particularly, the model is used to simulate the response of a dilute suspension of microbubbles undergoing large amplitude oscillations and single microbubbles undergoing lipid shedding. The optimal regimes in which microbubbles may be utilised as sensors for liquid physical properties and local pressure variations are then assessed. Finally, a summary of the conclusions and areas for further work is presented.
27
Peng, Congmin. "Essays on bubbles in financial markets." Thesis, University of Essex, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.635991.
Full textAbstract:
This thesis consists of three substantial chapters on topics related to bubbles in financial markets, an Introduction and Conclusion. A sharp increase in Chinese house prices combined with the extraordinary lending growth during the 2000s has led to concerns of an emerging real estate bubble. The first essay studies (nominal and real) house prices relative to fundamental house values. Housing constitutes a large fraction of most household portfolios and its characteristics are in contrast to what prevails in most financial markets as arbitrage is limited and hence correction toward fundamental values can be a prolonged process. Using a time-varying present value approach, our findings suggest evidence of bubbles in the Chinese housing market nationally and in representative cities using both nominal and real data. We also find that price dynamics have an important role to play in determining house prices. Moreover, the results reveal that the dominant driving force of house price deviations from fundamental values might be the less than fully rational behaviour of investors rather than fundamental factors. This seems plausible in an emerging market such as China.
28
Vogel, Harold. "Financial market bubbles : characteristics and theory." Thesis, University of London, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534026.
Full text
29
Asaoka, Shintaro. "Essays on the Theory of Bubbles." Kyoto University, 2020. http://hdl.handle.net/2433/253470.
Full text
30
Newswander, Chad B. "Presidential Security: Bodies, Bubbles, & Bunkers." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/77042.
Full textAbstract:
The purpose of this research is to show how the idea of presidential security is a construct that has taken on several different meanings and rationalities in the American context due to shifting power relations, new practices of presidential security, and the constant re-formulation of the friend/enemy distinction. The United States Service has had to continually think and re-think the concept of presidential security in order to provide suitable protection for the President of the United States. In creating these spaces of protection, the practices of the Secret Service have slowly contributed to re-constituting the sovereign to fit the agency's particular logics and rationalities. The capturing of the Chief Executive Officer does not only rest on disciplinary techniques that restrict, but are also founded on the truth production of the Secret Service: presidents begin to accept and internalize the modus operandi of the Secret Service. They begin to self-monitor their own desires and actions related to security concerns. The walls of protection are coupled with a conscious capitulation to accept the barriers of protection. The cage is no longer only imposed from without, but also emerges internally.
By problematizing how this evolving security bubble encapsulates the president, this dissertation is able to examine how the Secret Service begins to reshape and reformulate key democratic governance values by protecting the public and private body of the president through a disciplinary apparatus that seeks to control and contain as well as display and deliberate. Democratic norms that privilege openness have to be challenged, if not curtailed, to adequately protect the Chief Executive Officer. Everyone and everything is a risk that must be inspected, catalogued, and watched, even the president cannot be trusted with his own safety.
With its mission to protect, the Secret Service has constructed an organizational operation to ostracize the other, permanently put the president behind protective procedures, and present a pleasing public persona fitting to the status of the POTUS. These overt actions have allowed an administrative agency to redefine key democratic governance values. The agency has been able to delineate who is a suspicious other, justify the placement of barricades that separate the president from the people, instill a preventive/security ethos in the Office of the President, and display the president as the apex of a constitutional order. Because of its successes and failures, presidential protection has become normal, acceptable, legitimate, and absolutely necessary, which has provided the Service the ability to give shape to a particular rationality concerning what the president can and cannot do. This constitutive role of a public agency has had a dramatic impact on how the people come to experience and interact with the POTUS.
The development of the Secret Service and its protective procedures, however, has been sporadic and tenuous. For the past 100 years, this emerging rationality was produced by a multitude of sources that have helped construct the idea and practice of presidential security. The subjects of insecurity and security mutually created the idea of POTUS endangerment and safety. Enemies of the state have helped mold state action while friends of the president have sought to project an image of presidential grandeur. In this context, the Service has had to secure territorial spaces in order to conceal and confuse threats while simultaneously having to display and disclose the presidential body to the public. The capacity to control threats and to coordinate the presidential spectacle has enabled the Service to direct the body and mind of the POTUS. With this disciplinary apparatus in place, the Secret Service is able to construct bubbles and bunkers that are designed to protect and trap the president's two bodies.Ph. D.
31
Rafferty, Filofteia Laura. "X-ray Bubbles in Galaxy Clusters." Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1187802140.
Full text
32
Yang, Qian. "Stock bubbles : The theory and estimation." Thesis, Brunel University, 2006. http://bura.brunel.ac.uk/handle/2438/3597.
Full textAbstract:
This work attempts to make a breakthrough in the empirical research of market inefficiency by introducing a new approach, the value frontier method, to estimate the magnitude of stock bubbles, which has been an interesting topic that has attracted a lot of research attention in the past. The theoretical framework stems from the basic argument of Blanchard & Watson’s (1982) rational expectation of asset value that should be equal to the fundamental value of the stock, and the argument of Scheinkman & Xiong (2003) and Hong, Scheinkman & Xiong (2006) that bubbles are formed by heterogeneous beliefs which can be refined as the optimism effect and the resale option effect. The applications of the value frontier methodology are demonstrated in this work at the market level and the firm level respectively. The estimated bubbles at the market level enable us to analyse bubble changes over time among 37 countries across the world, which helps further examine the relationship between economic factors (e.g. inflation) and bubbles. Firm-level bubbles are estimated in two developed markets, the US and the UK, as well as one emerging market, China. We found that the market-average bubble is less volatile than industry-level bubbles. This finding provides a compelling explanation to the failure of many existing studies in testing the existence of bubbles at the whole market level. In addition, the significant decreasing trend of Chinese bubbles and their co-moving tendency with the UK and the US markets offer us evidence in support of our argument that even in an immature market, investors can improve their investment perceptions towards rationality by learning not only from previous experience but also from other opened markets. Furthermore, following the arguments of “sustainable bubbles” from Binswanger (1999) and Scheinkman & Xiong (2003), we reinforce their claims at the end that a market with bubbles can also be labelled efficient; in particular, it has three forms of efficiency. First, a market without bubbles is completely efficient from the perspective of investors’ responsiveness to given information; secondly, a market with “sustainable bubbles” (bubbles that co-move with the economy), which results from rational responses to economic conditions, is in the strong form of information-responsive efficiency; thirdly, a market with “non-sustainable bubbles”, i.e. the bubble changes are not linked closely with economic foundations, is in the weak form of information-responsive efficiency.
33
Zeng, Yan. "Bubbles and mismatches in DNA melting." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1324387071&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full text
34
Ingallinera, Adriano. "A Radio Characterization of Galactic Bubbles." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1380.
Full textAbstract:
This work was aimed to the radio characterization of the galactic bubbles discovered by the MIPSGAL survey conducted with the Spitzer Space Telescope. To get to this goal, a series of continuum and spectral line observations were carried out with the Very Large Array and with the Green Bank Telescope.
35
MAZZON, ANDREA. "Asset price bubbles in financial networks." Doctoral thesis, Gran Sasso Science Institute, 2018. http://hdl.handle.net/20.500.12571/10581.
Full textAbstract:
Asset price bubbles are commonly defined as the difference between the market value of an asset and its fundamental value. In this work, we study the two main stages characterizing the evolution of an asset price bubble: a first phase when the bubble takes place and blows up, and a second period when the burst of the bubble can affect financial institutions, leading to a crisis. Networks play an essential role in our analysis: we study how an investors network influences the evolution of the bubble through trading effects via contagion between investors, and in which way a bubble alters the structure of a banking network due to preferential attachment mechanisms in investments between financial institutions.
The first part of the thesis is devoted to the analysis of the first phase of the evolution of a bubble. In our approach, we follow the so called martingale theory of bubbles, recently developed starting from the assumption of absence of arbitrage. However, we slightly move the focus of the analysis: whereas the classic martingale theory of bubble spotlights the fundamental price of an asset, assuming that the market price is exogenously given, we start from a constructive model given by Jarrow et al. [2012], where the fundamental value is exogenously given and the market price can deviate from it due to illiquidity effects. This makes it possible to directly model the fast increase of the market value commonly observed when a bubble takes place. We embed this model in the martingale theory of bubbles, finding a flow of equivalent local martingale measures for the market wealth of the asset such that the fundamental wealth is justified as the expectation of discounted future earnings. In particular, we model the dynamics of the bubble as influenced by a contagion mechanism spreading among investors within a financial network. We show that the spread of contagion strongly depends on some characteristics of the network. In this way, the structure of the network affects the evolution of the bubble, through the impact of the trades on the price due to the illiquidity effects mentioned above.
On the other hand, we study the effects on the economy of the burst, and show how a bubble can influence the structure of a banking network. We consider a banking network represented by a system of stochastic differential equations coupled by their drift. We assume a core-periphery structure, and that the banks in the core hold a bubbly asset. The banks in the periphery have not direct access to the bubble, but can take initially advantage from its increase by investing on the banks in the core. Investments are modeled by the weight of the links, which is a function of the robustness of the banks. In this way,
a preferential attachment mechanism towards the core takes place during the growth of the bubble. We then investigate how the bubble distort the shape of the network, both for finite and infinitely large systems, assuming a non vanishing impact of the core on the periphery. Due to the influence of the bubble, the banks are no longer independent, and the law of large numbers cannot be directly applied at the limit. This results in a term in the drift of the diffusions which does not average out, and that increases systemic risk at the moment of the burst. We test this feature of the model by numerical simulations.
36
Harris, Ashley M. "Acoustic properties of toroidal bubbles and construction of a large apparatus." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1675.
Full textAbstract:
Approved for public release, distribution is unlimitedWhen a burst of air is produced in water, the result can be a toroidal bubble. This thesis is concerned with experimental investigations of three acoustical properties of toroidal bubbles: (i) propagation through high-intensity noise, (ii) emission, and (iii) scattering. In (i), an attempt to observe a recent prediction of the acoustic drag on a bubble is described, which is analogous to the Einstein-Hopf effect for an oscillating electric dipole in a fluctuating electromagnetic field. No effect was observed, which may be due to insufficient amplitude of the noise. In (ii), observations of acoustic emissions of volume oscillations of toroidal bubbles are reported. Surprisingly, the emission occurs primarily during the formation of a bubble, and is weak in the case of very smooth toroidal bubbles. In (iii), we describe an experiment to observe the effect of a toroidal bubble on an incident sound field. In addition to the acoustical investigations, we describe the construction of a large hallway apparatus for further investigations and for hands-on use by the public. The tank has cross section 2 feet by 2 feet and height 6 feet, and the parameters of reservoir pressure and time between air bursts are adjustable by the observer.
Lieutenant, United States Navy
37
Cooperstein, Shana. "BLOWING BUBBLES, BURSTING BULLES: AN ANALYSIS OF MANET'S BOY BLOWING BUBBLES AND THE POLITICIZATION OF HOMO BULLA." Master's thesis, Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/216764.
Full textAbstract:
Art HistoryM.A.
This paper analyzes the political dimensions surrounding visual and literary allusions to soap bubbles. Traditionally, iconographic studies consider soap bubbles within the history of northern Baroque vanitas, attaching to bubbles notions of ephemerality and transience. Building on these interpretations, eighteenth- and nineteenth-century French artists and writers created a complex metaphor for soap bubbles that relied on their impermanence and fragility, as well as their illusory nature. By coupling the earliest conceptual meanings of soap bubbles with their almost imperceptible formal properties, the bubble blower came to symbolize deceivers, or figures creating illusions or delusions. Eventually, this transformed vanitas symbolism became harnessed to political critiques and representative of chimerical assertions of papal authority, calumny, and false promises of liberal reform. I not only describe the alternative meanings associated with soap bubbles in eighteenth- and nineteenth-century France, but also I situate Edouard Manet's Les Bulles de savon (1867) within this trajectory. While most scholars interpret Manet's painting and accompanying prints as a continuation of, and legacy to, the Dutch vanitas tradition, I illustrate how the artistic and political milieu in which Manet worked mirrored earlier criticisms employing allusions to bubbles.
Temple University--Theses
38
Gustavsson, Marcus, and Daniel Levén. "The Predictability of Speculative Bubbles : An examination of the log-periodic power law model." Thesis, Linköpings universitet, Nationalekonomi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-120378.
Full textAbstract:
In this thesis we examine the ability of the log-periodic power law model to accurately predict the end of speculative bubbles on financial markets through modeling of asset price dynamics on a selection of historical bubbles. The methods we use are based on a nonlinear least squares estimation which yields predictions of when the bubble will change regime.We find evidence which support the occurrence of LPPL-patterns leading up to the change in regime; asset prices during bubble periods seem to oscillate around a faster-than-exponential growth. In most cases the estimation yields accurate predictions, although we conclude that the predictions are quite dependent on at which point in time the prediction is conducted. We also find that the end of a speculative bubble seems to be influenced by both endogenous speculative growth and exogenous factors. For this reason we propose a new way of interpreting the predictions of the model, where the end dates should be interpreted as the start of a time period where the asset prices are especially sensitive to exogenous events. We propose that negative news during this time period results in a regime shift of the bubble. This study is the first to address both the possibilities and the limitations of the LPPL-model, and should therefore be considered as a contribution to the academia.
39
Rajapakse, Sumanasiri D. N. "An experimental study on the effect of viscosity on micro-bubble size distribution and rise velocity in a bubble column." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2022. https://ro.ecu.edu.au/theses/2527.
Full textAbstract:
Dissolved air flotation (DAF) is a proven solid-liquid separation technology that is being used in water and wastewater treatment as an alternative process to conventional sedimentation operation. Due to its smaller footprint and ability to cater for higher liquid loading rates, it is ideal in many urban water treatment plants where space is limited and is usually designed for larger capacities. DAF systems generate microscale air bubbles to lift suspended particles in influent solution to the top of a rectangular tank and remove them by scrapers. Due to the recent focus on different applications of micro and nanoscale air bubbles across many industrial operations, researchers and engineers are trying to explore the application of DAF in other industries such as mineral ore processing, chemical industries, and sludge thickening operation in wastewater treatment plants (WWTPs). However, these applications have yielded low treatment efficiencies and less predictable performances, which demands more studies on the use of DAF in the high solid concentration of solid-liquid separation applications. While higher solid concentrations alter several physicochemical parameters in influent, an increase in slurry solution viscosity is a major concern. As a result, this thesis sought to identify the effect of viscosity on the microbubble (MB) size distribution and rise velocities which are identified as among the main factors affecting DAF performance.
A laboratory-scale micro bubble generation system attached with a bubble column was designed and built to investigate the effect of viscosity on system dynamics. Shadow imaging technology and particle image velocimetry were utilised to measure bubble size distribution and bubble rise velocities respectively for different viscosities. Solutions were prepared by mixing commercially available Xanthan Gum powder in different concentrations. The results of these experiments identified interesting variations of bubble sizes and rise velocities concerning viscosity (ranging from 1 mPas to 67.6 mPas). An increase in viscosity reduced bubble sizes and narrowed size distribution (from 60 - 200 μm to 30 – 70 μm) while reducing mean bubble rise velocities from 57 mm/s to 9 mm/s. The results of these experimental studies were critically analysed, and it was identified that reduction of bubble coalescence in high viscous solutions resulted in smaller bubble sizes, while increased drag forces slow down the rise velocity of bubbles. Moreover, this study provides essential baseline information for future studies when trying to improve DAF efficiency in high solid content applications during solidliquid separation operations.
40
Dawson, Geoffrey. "The motion of bubbles and capsules in tubes of varying geometry." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/the-motion-of-bubbles-and-capsules-in-tubes-of-varying-geometry(73af1916-b4c4-431e-91d0-40e3c03208d2).html.
Full textAbstract:
This thesis addresses aspects of the transport of bubbles and capsules (a thin elastic membrane enclosing a viscous fluid) by means of a viscous flow in complex vessel geometries. It focusses on two related themes: (i) the trapping of air bubbles in a sudden streamwise tube expansion and (ii) the extreme deformation of bubbles and capsules in a localised tube constriction. Air bubbles of different volumes were trapped in a tube with a square cross-section, which contains a sudden streamwise expansion in tube width. The liquid filling the tube was driven by constant volume-flux flow, and experiments were performed in both millimetric and micrometric tubes to identify the range of flow rates for which bubbles could get trapped. The gradients in surface energy generated by the broadening of the bubble into the expansion depend strongly on bubble volume and the expansion length. It is shown that in order for a trapped bubble to release from the expansion, the work of the pressure forces due to flow past the bubble must exceed the change in surface energy required to squeeze into the narrower channel. This criterion for trapping was verified by direct pressure measurements and a capillary static model, which uses three-dimensional Surface Evolver calculations. The extreme deformation of bubbles and capsules was investigated using a localised constriction of the tube width. Both bubbles and capsules were shown to adopt highly contorted configurations and exhibit broadly similar features over a wide range of flow rates, suggesting that the deformation was primarily imposed by the geometry through viscous shear forces. However, bubbles and capsules also display distinguishing features. Bubbles can breakup and exhibit thinning of the rear of the bubble at a critical flow rate, which is associated with a divergence of the rear tip speed and curvature. In contrast, the capsule membrane can wrinkle and fold, and the membrane thickness imposes the value of the maximum curvature locally available to the capsule.
41
Ghosh, Ambarish. "Experiments with electron bubbles in liquid helium /." View online version; access limited to Brown University users, 2005. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3174609.
Full text
42
Pannella, Pierluca. "Essays on credit booms and rational bubbles." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63421.
Full textAbstract:
Why are credit booms and bubbles harmful to the economy? A dominant view points to
the risk of bust. Traditional theories of bank runs and recent theories of rational bubbles
describe the costs of jumping to a bad equilibrium when the economy accumulates too much
debt. In this work, I propose a theory of rational bubbles where the boom, not the ensuing
bust, reduces the output by promoting a misallocation of factors.
In the model presented in Chapter 2, financial markets are imperfect and the rise of a bubble
alleviates credit constraints and boosts capital accumulation. However, capital accumulation
occurs in unproductive sectors and aggregate output is reduced. The result is driven by the
fact that heterogeneous borrowers have an advantage with respect to issuing different types of
debt contracts. In normal times, High-productive borrowers have higher collateral and thereby
attract most of the funds. In bubbly times, borrowers can also issue “bubbly debt,” a debt
that is repaid with future debt. The possibility to keep a pyramid scheme and raise bubbly
debt depends on the probability of surviving in the market. Therefore, a bubble misallocates
resources towards borrowers with low fundamental risk, even if they invest in projects with
lower productivity.
In Chapter 3, I propose an augmented version of the model with nominal rigidities. The
goal is to explain the timing of expansions and recessions during “bubbly episodes.” In this
version of the model, the initial boom in output is caused by a positive demand effect; the
long run reduction in TFP is driven by a misallocation process. In this chapter, I also analyze
the optimal policy prescriptions. In particular, I stress the importance of the central bank
monopoly on the issuing of bubble-like instruments.
Finally, Chapter 4 presents an investigation of American banks’ balance sheets motivated
by the theory of the previous chapters. I test models of credit bubbles versus models of liquidity
transformation. I provide evidence that the recent expansion in liquid debt instruments can
be interpreted by the emergence of a bubble on bank’s liabilities.Arts, Faculty of
Vancouver School of Economics
Graduate
43
Omota, Florin. "Adhesion of catalyst particles to gas bubbles." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2005. http://dare.uva.nl/document/77898.
Full text
44
Meer, Sander Martijn van der. "Ultrasound contrast agents resonances of coated bubbles /." Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/57925.
Full text
45
Ignatieva, Ekaterina. "Adaptive Bayesian sampling with application to 'bubbles'." Connect to e-thesis, 2008. http://theses.gla.ac.uk/356/.
Full textAbstract:
Thesis (MSc(R)) - University of Glasgow, 2008.MSc(R). thesis submitted to the Department of Mathematics, Faculty of Information and Mathematical Sciences, University of Glasgow, 2008. Includes bibliographical references.
46
Alam, Mahbubul. "Direct numerical simulation of laminar separation bubbles." Thesis, Queen Mary, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313069.
Full text
47
von, Aulock Felix W. "Bubbles, Crystals and Cracks in Cooling Magma." Thesis, University of Canterbury. Geological Sciences, 2013. http://hdl.handle.net/10092/7880.
Full textAbstract:
Ascent of magma results in drastic drops of pressure and temperature during eruption. Exsolution or dissolution of water changes the physical and chemical properties of the magma and can promote or inhibit the formation of bubbles, crystals and cracks. The microstructural relations between bubbles, crystals and cracks are important records of processes immediately before and during volcanic eruptions and during deposition of volcanic products. This is an integrated study of analyses, conceptual and numerical models of textural relations, and water distribution patterns of natural and experimentally altered samples.
Synchrotron Fourier transform infrared spectroscopy and focal plane array detectors open new possibilities for the analysis of the spatial distribution of volatiles in volcanic rocks. New ways of sample preparation, measurements and data analyses helped to create water distribution maps with spatial resolutions that are close to the diffraction limit (~3 μm). In order to constrain eruptive processes and mechanisms of lava emplacement, I describe textural features in volcanic glasses including bubbles, flow bands of crystals or bubbles, spherulites and different generations of cracks. In experiments, bubbles were grown under isobaric conditions, at one or two cooling steps, their textures were described and volume changes tracked. Water distribution patterns in the glass around the textures were described and categorized, and where possible, diffusion modeling was used to infer temperature- and timescales of formation.
Rocks that are quenched within short periods of time after bubble growth preserve negative gradients of water toward the bubble margins. These gradients are generally not observed if the sample is kept at high temperatures for extended periods. If, however, a second step of cooling is added, water may be re-dissolved into the surrounding melt, which may lead to the complete resorption of bubbles. A conceptual of water redistribution during bubble resorption or collapse is used to interpret water heterogeneities across linear flow banding. These heterogeneities can be caused by shearing of bubbly magma, leading to collapse, degassing and resorption of water into the melt, creating a bubble free melt. Anhydrous spherulitic crystals grow both above and below the glass transition temperature (Tg) redistributiong water into the surrounding melt. Below Tg, cracks form and are successively hydrated by magmatic water from crystal growth or by meteoric water at temperatures far below Tg. The hydrated perlitic cracks in the samples of this study formed at elevated temperatures and are distinct from cracks formed at ambient temperatures without hydrated margins.
This study shows that the heterogeneous distribution of water in volcanic rocks preserves the complex and non-linear degassing and cooling history of eruptive products. The timescales and temperatures discovered here provide new ways to interpret textural observations, water distribution patterns and signals of shallow volcanic unrest.
48
Isikan, Mustafa Osman. "Collapse of steam bubbles in subcooled water." Thesis, University of Strathclyde, 1986. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21478.
Full textAbstract:
Condensation, of steam bubbles generated at an orifice and rising freely through water, subcooled from 5 K to 36.6 K at pressures of 1 bar and 2 bar, has been analysed theoretically and experimentally. Orifice diameters were 1 mm and 2 mm, and steam flow rates of 0.5, 1 and 1.5 g/min were used. The data indicate a decrease in collapse Fourier number with increase in either Jakob number or steam flow rate, or with a decrease in pressure, while change in orifice diameter does not have a significant effect on collapse Fourier number. Average values of heat transfer coefficient around the collapsing bubbles have been determined to be between 0.15 . 10⁵ - 0.35 . 10·⁵ W/m·²K. The effect of bubble distortion and of local heating of the liquid, close to the orifice, due to condensation of the bubbles, have both been included in the quasi-steady state theory which has been presented. The experimental data is compared with the theoretical predictions. A semi-empirical correlation for bubble rise height has been proposed, which is also based on the quasi-steady theory combined with a correlation for the velocity of steam bubbles condensing in subcooled water.
49
Ho, Man-suen, and 何敏璇. "Speculative bubbles in the real estate market." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31251663.
Full text
50
Watson, Yvonne. "Electrochemical investigations of acoustically driven gas bubbles." Thesis, University of Southampton, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288192.
Full text