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The thermo-chemical relaxation of nitrogen hypersonic flows behind strong shocks and in nozzle expansions is investigated with 1D flow simulations and detailed vibrational kinetics. This work aims at deriving from detailed vibrational models accurate reduced models easy to implement in multidimensional reentry flow codes. First, nonequilibrium couplings between vibrational excitation, dissociation and recombination reactions are considered. Vibrational kinetics is described using accurate vibrational state-to-state rate constant databases of the literature completed with the forced harmonic oscillator model. The key role of multiquanta vibration-translation processes on the relaxation of the vibrational distribution function and the dissociation/recombination processes is put forward behind shocks and in nozzles. The vibrational distributions, which deviate strongly from equilibrium for nozzle expansions, are driven by vibration-translation processes and dissociation/recombination processes. A macroscopic model using groups of vibrational levels is developed to derive consistently the chemical and vibrational energy source terms from the vibrational state-to-state database.This model successfully reproduces the thermal, chemical and vibrational distribution function dynamics predicted by the state-to-state model with one group of levels behind a shock wave, and with three groups of levels in nozzle expansions. In a second step, the detailed vibrational model is extended to ionized nitrogen flows, including in particular a detailed modeling of the resonant electronvibration processes. Behind shocks, these processes control the rate of ionization by feeding energy to the electrons, up until the time when the elastic electron-ion exchanges takes over. It is shown that the widely used assumption of equilibrium between the electron and vibration temperatures predicts a too fast relaxation behind shock waves. In nozzle expansions, it is shown that for low electron concentration, the electron temperature is driven by electronvibration processes. Moreover, it is found that electrons are strongly coupled to low vibrational levels, and that more levels are coupled when the electron temperature increases. Coupling of the flow field with radiation is performed using the tangent slab approximation, and it is shown that the population of a metastable and two higher electronic levels are strongly impacted. Finally, the macroscopic model is extended to ionized nitrogen flows and is successfully applied on shock waves with one group of levels and with three groups of levels in nozzle expansions. In particular, the proposed macroscopic model represents more accurately the electron-vibration coupling than the widely used Landau-Teller model.

It is shown in the literature that the NAT devices have become a convenient way to hide the identity of malicious behaviors. In this thesis, the aim is to identify the presence of the NAT devices in the network traffic and (if possible) to predict the number of users behind those NAT devices. To this end, I utilize different approaches and evaluate the performance of these approaches under different network environments represented by the availability of different data fields. To achieve this, I propose a machine learning (ML) based approach to detect NAT devices. I evaluate my approach against different passive fingerprinting techniques representing the state-of-the-art in the literature and show that the performance of the proposed ML based approach is very promising even without using any payload (application layer) information.

In a globalizing world, trade has become essential to supporting the needs and wants of billions of people. Virtually everyone now consumes resource commodities and manufactured products traded all over the world; the ecological footprints of nations are now scattered across the globe. The spatial separation of material production (resource exploitation) from consumption eliminates negative feedbacks from supporting eco-systems. Most consumers remain unaware of the impacts that their trade dependence imposes on distant ecosystems (out of sight out of mind). I take the first steps in developing a conceptual and practical framework for an ‘interregional ecology’ approach to exploring and analyzing sustainability in an increasingly interconnected world. Such an approach accounts for some of the ‘externalities’ of globalization and international trade. It underscores the increasing dependence and impact of almost any country on resources originating from others and recognizes that the sustainability of any specified region may be increasingly linked to the ecological sustainability of distant supporting regions. I empirically describe and quantify some of the interregional material linkages between selected countries. I document the flows of renewable resources into the U.S. and quantify the U.S. external material footprint (EF) on specific countries. I then document the physical inputs involved in production of most agricultural export products from Costa Rica and Canada. Finally, I focus on major export products such as bananas, coffee and beef in Costa Rica and agricultural activities in the Canadian Prairies and document some of the ecological consequences (loss of habitat, soil degradation, water contamination and biodiversity loss) of that production. My research findings show increasing U.S. imports, increasing reliance on external sources and growing external ecological footprints. They also show how production activities mostly for overseas consumption led to changes in ecological structure and function in the studied export countries. This dissertation adds a missing trans-national dimension to the sustainability debate effectively integrating the policy and planning domain for sustainability in one region with that in others. While my research focuses mainly on documenting the nature and magnitude of interregional connections I also consider some of the implications of the interregional approach for sustainability planning.

ABSTRACT TWO ESSAYS ON MANAGERIAL BEHAVIORS IN THE MUTUAL FUND INDUSTRY LENG LING ESSAY 1: DOES MUTUAL FUND WINDOW-DRESSING PROMOTE FUND FLOWS? I investigate the effectiveness of window-dressing as a potential strategy to be used by mutual fund managers to promote fund flows. Using a rank gap measure as a proxy for the likelihood that window-dressing has occurred, I find that fund investors as whole punish those managers who are suspected to have engaged in window-dressing. That is, I find a negative relation between the window-dressing measure and net fund flows in subsequent quarters after controlling for fund performance, size, expense ratio, and other pertinent characteristics. I also find that window-dressing leads to higher trading activities and lower fund performance. ESSAY 2: A LIFE CYCLE ANALYSIS OF PERFORMANCE AND GROWTH IN U.S. MUTUAL FUNDS I propose a five-stage growth model to describe the life cycle evolution of mutual funds and show that mutual funds exhibit distinctive performance, size, expense ratios, asset turnover, and other pertinent characteristics through stages of incubation, high-growth, low-growth, maturity, and decline. I also investigate the viability of managerial strategies to affect a fund’s life cycle evolution and find that changing a declining fund’s investment objective is effective in rejuvenating asset growth and thus repositioning the fund to younger life cycle stages. However, the strategy of adding portfolio managers appears to have no such rejuvenation effect.

The Purpose of the Dissertation is to analize and specify the capability of cargo flow forecasting in ports, through assessment and modelling the distribution of cargo flows throughout competitor ports, by considering certain factors that might cause considerable changes into ports or port environment.

Baigiamajame darbe atlikta importo, eksporto ir tranzito informacinių srautų Lietuvoje analizė per 2006 m. sausio 1 d. - 2007 m. birželio 30 d laikotarpį. Išanalizuoti kreipimaisi į Informacinių technologijų paslaugų centrą dėl minėtus srautus aptarnaujančių sistemų problemų. Pateiktos išvados ir pasiūlymai. Efektyvus informacinių technologijų panaudojimas atlieka svarbų vaidmenį Lietuvos muitinės sistemos veikloje. Pastaruoju metu tiek mūsų šalyje, tiek ir tarptautiniu mastu aktyviai diskutuojama apie kuo spartesnį elektroninės muitinės aplinkos sukūrimą Europos Sąjungoje, dar veiksmingesnį informacinių technologijų pritaikymą atliekant prekių importo, eksporto bei tranzito srautų statistinę analizę, vykdant muitinio įforminimo dokumentų apdorojimą. Šio magistro baigiamojo darbo tikslas – atlikti muitinio įforminimo proceso informacinių srautų Lietuvoje analizę ir identifikuoti pagrindines problemas bei pateikti pasiūlymų dėl šių problemų sprendimo. Magistro baigiamąjį darbą sudaro trys dalys. Pirmoje darbo dalyje trumpai pristatoma Lietuvos muitinės istorija, aptariamos pagrindinės šiuolaikinės muitinės veiklos kryptys ir funkcijos, ypač akcentuotas Muitinės informacinių sistemų centro vaidmuo Lietuvos muitinės sistemoje. Antroje dalyje apžvelgiami prekių importo, eksporto bei tranzito procesai bei informacinių technologijų panaudojimas muitinio įforminimo dokumentų apdorojime. Trečioji dalis skirta muitinio įforminimo proceso informacinių srautų statistinei analizei... [toliau žr. visą tekstą] / In the Master’s paper the analysis of the import, export and transit flows of goods in Lithuania during the period from 1 January 2006 till 30 June 2007 is performed. The calls to Information Technology Service Centre regarding the problems of the systems servicing these flows is analysed. Some conclusions and proposals are submitted. The effective use of information technology (IT) plays an important role in the activities of the Lithuania’s customs system. Currently the issues of a faster creation of an EU-wide e-Customs, more efficient use of IT in performing the statistical analysis of the import, export and transit flows of goods or in processing customs documents have been seriously considered both nationally and internationally. The goal of this Master’s paper is to perform the analysis of information flows of the customs documents processing, to identify the problems as well as to present some proposals for the solution to these problems. The Master’s paper consists of three parts. In the first part a brief overview of the customs’ history in Lithuania is presented, the main current functions and activities of the Lithuanian customs are described and much attention is paid to the role of the Customs Information System Centre in the Lithuanian customs system. The second part is devoted to the survey of the import, export and transit processes of goods as well as the use of IT in the Lithuanian customs. In the third part a thorough statistical analysis of... [to full text]

This thesis concerns the occurrence of the large-scale bed and plan forms known as alternate bars and meandering, and the internal structures of the flow associated with their formation. The work is to be viewed as an extension of previous work by da Silva (1991), Yalin (1992), and Yalin and da Silva (2001). As a first step in this work, the criteria for occurrence of alternate bars and meandering of Yalin and da Silva (2001) is re-considered in view of additional field and laboratory data from the recent literature and data resulting from two series of experimental runs carried out in two sediment transport flumes. This leads to a number of modifications of the boundary-lines in the related existence-region diagram of Yalin and da Silva. The size of the largest horizontal coherent structures (HCS’s) of an alternate bar inducing flow was then investigated experimentally on the basis of three series of flow velocity measurements. These were carried out in a 21m-long, 1m-wide straight channel, conveying a 4cm-deep flow. The bed consisted of a silica sand having a grain size of 2mm; its surface was flat. The measurements were carried out using a Sontek 2D Micro ADV. The horizontal burst length was found to be between five and seven times the flow width. The effect of the HCS’s on the mean flow was also investigated. A slight internal meandering of the flow caused by the superimposition of burst-sequences on the mean flow was clearly detectable. Finally, with the aid of three new series of measurements in the same channel, an attempt was made to penetrate the dynamics and life-cycle of the HCS’s. For this purpose, quadrant analysis was used; the cross-sectional distribution of relevant statistical turbulence-related parameters was investigated; and cross-correlations of flow velocity along the flow depth and across the channel were performed. The analysis indicates that the HCS’s originate near the channel banks, with the location of ejections and sweeps being anti-symmetrically arranged with regard to the channel centreline, and then evolve so as to occupy the entire depth of the water and the entire width of the channel. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2010-03-09 10:20:53.596

In the present doctoral work we have developed and tested a model for dissolved oxygen (DO) transfer from water to underlying flat and cohesive sediment beds populated with DO-absorbing bacteria. The model couples Large-Eddy Simulation (LES) of turbulent transport in the water-column, a biogeochemical model for DO transport and consumption in the sediment, and Darcy’s Law for the pore water-driven solute dispersion and advection. The model’s predictions compare well against experimental data for low friction-Reynolds numbers (Re). The disagreement for higher Re is investigated by progressively increasing the complexity of the model. A sensitivity analysis shows that the sediment-oxygen uptake (or demand, SOD) is approximately proportional to the bacterial content of the sediment layer, and varies with respect to fluid dynamics conditions, in accordance to classic high-Schmidt-number mass-transfer laws. The non- linear transport dynamics responsible for sustaining a statistically steady SOD are investigated by temporal- and-spatial correlations and with the aid of instantaneous visualizations: the near-wall coherent structures modulate the diffusive sublayer, which exhibits complex spatial and temporal filtering behaviours; its slow and quasi-periodic regeneration cycle determines the streaky structure of the DO field at the sediment-water interface (SWI), retained in the deeper layers of the porous medium. Oxygen depletion dynamics are then simulated by preventing surface re-areation with turbulent mixing driven by an oscillating low-speed current — an idealization of hypolimnetic DO depletion in the presence of a non-equilibrium periodic forcing. The oxygen distribution exhibits a self-similar pattern of decay with, during the deceleration phase, oscillations modulated by the periodic ejection of peaks of high turbulent mass flux (pumping oxygen towards the SWI), generated at the edge of the diffusive sublayer at the end of the acceleration phase. These fronts of highly turbulent mixing propagate away from the SWI, at approximately constant speed, in layers of below-average oxygen concentration. Finally, the model has been tested in a real geophysical framework, reproducing published in-situ DO measurements of a transitional flow in the bottom boundary layer of lake Alpnach. A simple model for the SOD is then derived for eventual inclusion in RANSE biogeochemical management-type models for similar applications. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2012-07-04 11:13:24.936

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