The effect of vegetation on the dissipation of waves is important in understanding the vegetation's role in protecting coastal communities during extreme events such as hurricanes and tsunamis. Numerical modeling makes it possible to study the flow through vegetation fields, but it is important to understand the flow dynamics around one piece of vegetation and validate the numerical model used, before the dynamics of an entire vegetated patch can be modeled and understood. This project validated GPUSPH, a Lagrangian mesh-free numerical model, by determining the optimal characteristics to obtain accurate simulations for flow through a flume with and without an obstruction. The validation of GPUSPH and determination of optimal characteristics was accomplished by varying model particle spacing, sub-particle scale (SPS) turbulence inclusion in the conservation of momentum equation, and kernel weighting function for two test cases. The model particle spacing sets the initial distance between the moving grid points, known as particles, in the system. The SPS turbulence term is intended to account for turbulence generated at the sub-particle scale between the particles. The kernel weighting functions used are the quadratic kernel and the cubic spline kernel. These kernels determine how much influence surrounding particles have on the flow characteristics of an individual particle. The numerical results of these tests were compared with experimental results to obtain conclusions about the accuracy of these simulations. Based on comparisons with experimental velocities and forces, the optimal particle spacing was found to occur when the number of particles was in the high 100,000s for single precision calculations, or mid-range capabilities, for the hardware used in this project. The sub-particle scale turbulence term was only necessary when there was large-scale turbulence in the system and created less accurate results when there was no large-scale turbulence present. There was no definitive conclusion regarding the best kernel weighting function because neither kernel had overall more accurate results than the other. Based on these conclusions, GPUSPH was shown to be a viable option for modeling free-surface flows for certain conditions concerning the particle spacing and the inclusion of the subparticle scale turbulence term.

El objetivo del presente estudio es el de identificar las tendencias en la traducción de elementos culturales específicos en traducciones de inglés a croata y, posteriormente, correlacionarlas con los desarrollos que ocurrieron en el contexto general en el que se produjeron las traducciones. El estudio se propuso probar hipótesis que predicen una tendencia creciente por emplear tipos de soluciones de asimilación al traducir elementos culturales específicos y también relacionar esta tendencia con los mayores flujos de traducción. Las hipótesis se evalúan usando un corpus de novelas de detectives traducidas en tres períodos: principios de los 60, finales de los 70 y la década del 2000. Los datos cuantitativos obtenidos por medio de análisis textuales se unen con datos cualitativos obtenidos en entrevistas son los agentes de las traducciones. En la conclusión se discuten estos resultados con el objetivo de establecer posibles correlaciones entre los datos del análisis textual, los datos de las entrevistas y los datos extratextuales con las variables contextuales.

Continuous increase in resource demand and associated with it environmental impact, by-products and wastes,  are  going  to  put  strains  on  the  global  ecosystem  including  humans.  The  thesis  was  based  on  the assumption that: The household scale holds important information on flows of resources and statistical  relations between them. This master thesis was pilot-study of the project “Quantifying Household Metabolism” which was carried out by Urban Metabolism Research Group (UMRG) at Chalmers University of Technology. The thesis intends to develop methods to quantify fluxes of consumption and waste generation through individual household. The data was collected in two Swedish households and the collection period in the master project was 2.5 months on solid waste and 1 month on biowaste. The data was collected on a daily basis and from three streams: shopping receipts, recyclable solid waste and biowaste from kitchen. The data gathered by the proposed method illustrated a  pattern  of  consumption  and  waste  generation  through  individual  household  based  on  t h e   two  studied households. Although the proposed method avoided the errors happened in pervious study methods (Survey), the  deficiencies  and  potential  risks  exited.  The  indicators  developed  to  evaluate  the  situation  of  household metabolism  failed  to  apply  to  the  testing households  in pilot-study.  The applied data collection procedure was manual  and  laborious,  and  accumulated  errors  easily  happened  when  it  carry  out  in  a  long  term.  Several automatic possibilities could be introduced in the future study.

Our essay focuses on short-term capital inflows and their effects on China’s economy.The reason for this work was the increasing vulnerability of China’s economy and the risk of newupcoming world financial crisis, all because of uncontrollable amounts of speculative capitalflows. Because of this problem, we raised a main question that we try to answer in this essayhowto reduce the possibility and the severity of the future financial crisis in China? In order tosolve this problem, first we searched for the existing theory of capital flows, mainly short-termcapital inflows. We analysed why investors choose capital flows and some specific countries,why it is profitable, but also risky and what could be done by countries, to stop these inflows orat least to diminish their effect on domestic markets. After that, we looked for past experiencesof countries faced with surges of capital flows and their measures for controlling them, weanalysed, if the theoretical tools were actually effective in reality. To finish the model, weapplied these measures to China’s economy and gave our viewpoint on what could be changedin order to avoid the dangers of short-term capital inflows. Last, we sum up the whole essay andsuggest the best mix of measures that China could use to control capital inflows as well as theireffects on the economy.

This research presents an experimental study of the formation of drops of suspensions consisting of a viscous liquid and spherical, neutrally buoyant, noncolloidal particles. Pendant drop formation and low Reynolds number jetting of suspensions are investigated, as is the transition between the two. Throughout, the particles utilized are on the order of 100 μm and the orifice from which the drops are formed is on the order of 1 mm. The presence of the particulate phase causes the structure at pinch-off in the pendant drop regime to change noticeably from that of pure liquids. Thick cone-like structures, termed "spindles" here, form at either end of the slender thread and are the result of particle motions during necking. These spindles become more pronounced with increasing particle concentration. Depending on particle concentration, the particles can have either a destabilizing effect (low concentration) on drop formation or a stabilizing one (high concentration). At low concentrations, the particles lead to earlier rupture of the thread and much shorter jet lengths, while at elevated concentrations the particles stabilize the thread after rupture and lead to fewer satellite drops as well as induce jetting at lower flower rates. A two-stage model has been proposed to describe the necking process for particle-laden suspensions in the pendant drop regime. The first stage occurs when the thread is thick relative to the particles and the effect of the particles can be attributed solely to a change in the effective viscosity of the mixture. The second stage occurs nearer pinch-off when the thread has thinned to only a few particle diameters. In this stage the individual particle motions within the thread determine the behavior and the thread ultimately ruptures over a region of the thread devoid of particles.

In order to extend fluid-based flow control techniques that have been demonstrated at low subsonic speeds to high speed flows, it is necessary to develop actuators having sufficient momentum to control and manipulate high speed flows. Two fluidic actuation approaches are developed where the control jet may reach supersonic velocities and their performance is characterized. The first actuator is a compressible synthetic (zero net mass flux) jet. This is an extension of previous work on synthetic jets with an increase in driver power yielding substantial pressurization of the cavity such that the flow is compressible. The jet is generated using a piston/cylinder actuator, and the effects of variation of the orifice diameter, actuation frequency, and compression ratio are investigated. Operation in the compressible regime uniquely affects the time-dependent cylinder pressure in that the duty cycle of the system shifts such that the suction phase is longer than the blowing phase. The structure of the jet in the near-field is documented using particle image velocimetry and Schlieren flow visualization. In the range investigated, the stroke length is sufficiently long that the jet flow is dominated by a starting jet rather than a starting vortex (which is typical of low-speed synthetic jets). A simple, quasi-static numerical model of the cylinder pressure is developed and is in generally good agreement with the experimental results. This model is used to assess system parameters which could not be measured directly (e.g., the dynamic gas temperature and mass within the cylinder) and for predictions of the actuator performance beyond the current experimental range. Finally, an experiment is described with self-actuated valves mounted into the cylinder head which effectively icrease the orifice area in suction and overcome some of the limitations inherent to compressible operation. The second actuation concept is the combustion-driven jet actuator. This device consists of a small-scale (nominally 1 cc) combustion chamber which is filled with premixed fuel and oxidizer. The mixture is ignited using an integrated spark gap, creating a momentary high pressure burst within the combustor that drives a high-speed jet from an exhaust orifice. At these scales, the entire combustion process is complete within several milliseconds and the cycle resumes when fresh fuel/oxidizer is fed into the chamber and displaces the remaining combustion products. The actuator performance is characterized by using dynamaic measurements of the combustor pressure along with Schlieren flow visualization, limited dynamic thrust measurements, and flame photography. The effects of variation in the following system parameters are investigated: fuel type and mixture ratio, exhaust orifice diameter, chamber aspect ratio, chamber volume, fuel/air flow rate, ignition/combustion frequency, and spark ignition energy. The resulting performance trends are documented and the basis for each discussed. Finally, a proof-of-concept experiment demonstrates the utility of teh combustion-driven jet actuators at low-speed for transitory reattachment of a separated flow over an airfoil at high angles of attack.

In this thesis the author develops techniques to study contact structures via Riemannian geometry. The main observation is a relation between characteristic surfaces of contact structures and zero sets of solutions to certain subelliptic PDEs. This relation makes it possible to derive, under a symmetry assumption, necessary and sufficient conditions for tightness of contact structures arising from a certain class of invariant curl eigenfields. Further, it has implications in the energy relaxation of this special class of fluid flows. Specifically, the author shows existence of an energy minimizing curl eigenfield which is orthogonal to an overtwisted contact structure. It provides a counterexample to the conjecture of Etnyre and Ghrist posed in their work on hydrodynamics of contact structures.

A novel computational approach, Two Level Simulation (TLS), was developed based on the explicit reconstruction of the small-scale velocity by solving the small-scale governing equations on the domain with reduced dimension representing a collection of one-dimensional lines embedded in the three-dimensional flow domain. A coupled system of equations, that is not based on an eddy-viscosity hypothesis, was derived based on the decomposition of flow variables into the large-scale and the small-scale components without introducing the concept of filtering. Simplified treatment of the small-scale equations was proposed based on modeling of the small-scale advective derivatives and the small-scale dissipative terms in the directions orthogonal to the lines. TLS approach was tested to simulate benchmark cases of turbulent flows, including forced isotropic turbulence, mixing layers and well-developed channel flow, and demonstrated good capabilities to capture turbulent flow features using relatively coarse grids.

The work presented in this dissertation concerns continued development, validation and verification of the partially averaged Navier-Stokes (PANS) method - a variable resolution closure model for turbulence. Linear eddy viscosity models (LEVM), which are popular because of their simplicity and affordability in terms of computational cost have fundamental deficiencies and cannot be trusted to accurately represent turbulence in realistic complex flows. The more high fidelity approaches such as large eddy simulations (LES) and direct numerical simulations (DNS) are out of realm of engineering applicability because of their high requirements in computing power. PANS, a variable resolution approach considered in this study, lies between LEVM and LES in terms of computational cost and is designed to prudently utilize the available computing power to improve accuracy. This dissertation presents the various studies performed to characterize the PANS fluctuations and extend the model for use in various wall bounded flows. The road map towards our goal includes: (i) Comparing a-priori and a-posteriori eddy viscosity values to establish whether PANS is capable of producing the pre-specified level of reduction. (ii) Investigating the scaling of PANS fluctuations for different levels of prescribed resolution and establishing if the fluctuations abide by known turbulence scaling laws. (iii) Extending PANS to k-w formulation which is better suited for wall-bounded shear flows, and (iv) Modifying the present LEVM to yield reasonable behavior in the rapid distortion limit where the turbulence is elastic in nature which ultimately affects PANS performance. Results reported in this dissertation illustrate that the PANS closure yields reliable and predictable reduction in the modeled viscosity. The accuracy of the simulations improve as the effective damping is reduced by lowering the specified viscosity providing credibility to the PANS method as a bridging model that performs as intended.

<p>This thesis is an assessment of the dynamics of trade affinities and how they have influenced trade flows in the European continent. The focus is how trade affinities have altered over a time span of four time periods stretching from the 1970s up to today and how these alterations have influenced globalization.</p><p>A total of 41 countries belonging to the European continent have been selected. Furthermore four variables were selected to represent trade affinities; distance, border, colony, and language. These have been selected as they are generally believed to be static and thus should not change over time. Also, this thesis aims to show the separate influence of each trade affinity as other papers usually estimate trade affinities as one collective variable.</p><p>By the use of a gravity model 9 variables are tested in order to determine their influence on trade flows. This is done through a regression with a log-log equation where the dependent variable is Export and the affinity variables are estimated as dummy variables.</p><p>The regression is divided into four time periods in order to more easily determine how the trade affinity variables have altered in influence on trade flows in Europe. The first time period represent an average of the time period 1974-1976, the second 1984-1986, the third 1994-1996 and the fourth 2004-2006.</p><p>The regression results illustrate that the majority of the selected variables are significant but most importantly that the trade affinity variables are proven to have altered over the time periods. The performance of a Wald estimation gives an indication that trade affinities are in fact dynamic although the results are not entirely significant for all variables.</p><p>Based on the results, it is apparent that trade affinities still have a significant effect on trade flows in the European continent. Although, their effects have altered to become less significant in some cases while others have become stronger they all jointly share the attributes of affecting trade. These alterations can in turn be interpreted as dependent on the globalization process of the European continent. As globalization has progressed some affinities have decreased in influence while others have regained new importance.</p>