This dissertation proposes a modular fast direct (MFD) analysis method for a class of problems involving a large fixed platform region and a smaller, variable design region. A modular solution algorithm is obtained by first decomposing the problem geometry into platform and design regions. The two regions are effectively detached from one another using basic equivalence concepts. Equivalence principles allow the total system model to be constructed in terms of independent interaction modules associated with the platform and design regions. These modules include interactions with the equivalent surface that bounds the design region. This dissertation discusses how to analyze (fill and factor) each of these modules separately and how to subsequently compose the solution to the original system using the separately analyzed modules. The focus of this effort is on surface integral equation formulations of electromagnetic scattering from conductors and dielectrics. In order to treat large problems, it is necessary to work with sparse representations of the underlying system matrix and other, related matrices. Fortunately, a number of such representations are available. In the following, we will primarily use the adaptive cross approximation (ACA) to fill the multilevel simply sparse method (MLSSM) representation of the system matrix. The MLSSM provides a sparse representation that is similar to the multilevel fast multipole method. Solutions to the linear systems obtained using the modular analysis strategies described above are obtained using direct methods based on the local-global solution (LOGOS) method. In particular, the LOGOS factorization provides a data sparse factorization of the MLSSM representation of the system matrix. In addition, the LOGOS solver also provides an approximate sparse factorization of the inverse of the system matrix. The availability of the inverse eases the development of the MFD method. Because the behavior of the LOGOS factorization is critical to the development of the proposed MFD method, a significant part of this dissertation is devoted to providing additional analyses, improvements, and characterizations of LOGOS-based direct solution methods. These further developments of the LOGOS factorization algorithms and their application to the development of the MFD method comprise the most significant contributions of this dissertation.

Patterned resistive sheets (PRS) are resistive sheets with periodic patterns which provide further advantages to the functionality of the microbolometer. This study examines the potential of both single- and double-layer designs to achieve spectral selectivity in both broadband and narrowband absorption in the microbolometer's application. First, important design parameters, including rules and processes, are established. These include descriptions of sheet resistance, air gap, material refractive index, thicknesses of dielectric and bolometric layers, mirror, pattern shape and size, and unit cell period. Moreover, interactions among these elements are examined. Second, single-layer designs using dipole and slot PRS are introduced as initial designs for the reduced thermal mass design. Applying holes without changing spectral selectivity are investigated for narrowband application. Moreover, the method to tune the change of spectral selectivity is introduced. Third, newly stacked two-color design is suggested. The out-of-band transmission and reflection characteristics of the dipole and slot PRS are investigated to increase the absorption of each layer. Additionally, different pattern shapes, such as the circular patch and square patch, are investigated for easier fabrication. / text

The topic of Markov Random Fields (MRFs) has been well studied in the past, and has found practical use in various image processing, and machine learning applications. Where coding is concerned, MRF specific schemes have been largely unexplored. In this thesis, an overview is given of recent developments and challenges in the lossless coding of MRFs. Specifically, we concentrate on difficulties caused by computational intractability due to the partition function of the MRF. One proposed solution to this problem is to segment the MRF with a cutset, and encode the components separately. Using this method, arithmetic coding is possible via the Belief Propagation (BP) algorithm. We consider two cases of the BP algorithm: MRFs with only simple cliques, and MRFs with complex cliques. In the latter case, we study a minimum radius condition requirement for ensuring that all cliques are accounted for during coding. This condition also simplifies the process of conditioning on observed sites. Finally, using these results, we develop a systematic procedure of clustering and choosing cutsets. / Thesis (Master, Mathematics & Statistics) -- Queen's University, 2013-08-12 14:50:00.596

Global sea levels are expected to rise as a result of climate change, which will lead to the inundation and erosion of low lying coastal areas and accelerate the intrusion of seawater into sub-surface sediments. Many of the UK’s legacy nuclear facilities are located in close proximity to the shore, raising questions regarding the potential mobilisation of radionuclides during sea level rise. Here batch and column experiments were used to simulate and investigate the effect of these processes on the mobilisation of key radionuclides Tc, 90Sr and U from oxic and reduced sediments under sea level rise scenarios. Strontium-90 was rapidly mobilised from exchangeable surface sites from oxic sediments during inundation and erosion scenarios with seawater (≈ 60%). Strontium release was driven by ion exchange between Sr90 and Mg2+ cations present in high concentrations in seawater. Uranium release from oxic and reduced sediments was kinetically controlled, characterised by slow release from a range of binding sites, promoted by the formation of U-carbonate complexes. Uranium mobilisation was slower from reduced sediments compared with oxic sediments under seawater flow conditions; therefore reduced sediments would act as a longer term source of U to marine environments. Release was more extensive from initially nitrate reducing sediments (53%) compared with extensively iron reducing sediments (38%), with the difference in release explained by the longer contact period of U(VI) with the iron reducing sediment relative to the nitrate reducing sediment which would lead to slower desorption. Additionally, U(IV) species would be released more slowly than U(VI) species sorbed to the sediments. The release of Tc was dependent on sediment re-oxidation coupled with the oxidation of Tc(IV) to Tc(VII). Batch experiments showed that only a small proportion of Tc was rapidly (within 5 days) released from the sediments into seawater and groundwater which suggests that the majority of any Tc(IV) contamination will be released slowly as the seawater plume migrates through the sediments. Technetium release was slowest, and ultimately limited to the greatest extent (17%), in initially Fe-reducing sediments, when they were re-oxidised in seawater. Thus the cycling of iron and the impact of the water chemistry on iron mineralogy were important for hindering Tc release. Column experiments showed that iron minerals were less effective at retarding Tc release under flow-through conditions. Kinetically controlled and solubility limited Fe dissolution led to on-going Tc release from the sediments, i.e. the retarding effect of iron phases was temporary and significantly more Tc was mobilised (79-93%) compared with the batch experiments (17-45%). This study has shown for the first time that radionuclides will be released from reduced and oxic sediments as a result of future sea level rise. Contaminated sediments have the potential to act as a secondary source of radionuclide contamination entering the marine environment from coastal nuclear sites. This information is essential when siting new nuclear facilities and when developing effective remediation, decommissioning and management strategies for legacy coastal sites.

Drop Towers provide brief terrestrial access to microgravity environments. When used for capillary fluidics research, a drop tower allows for unique control over an experiment's initial conditions, which enables, enhances, or otherwise improves the study of capillary phenomena at significantly larger length scales than can normally be achieved on the ground. This thesis provides a historical context for the introduction of a new, highly accessible, 2.1s tower design used for capillary research and presents a variety of demonstrative experimental results for purely capillarity-driven flows leading to bubble ingestion, sinking flows, multiphase flows, and droplet ejections. The focus of this thesis is paid to capillarity-driven droplet ejection including historical significance, mathematical models, criteria for ejection and experimental validation. A scale analysis provides a single parameter Su+ which is used to predict the flow velocity at the base of the nozzle. By simplifying the flow in the nozzle we identify two criteria for auto-ejection, the nozzle must be `short' and the velocity of the flow must be sufficient to invert the liquid meniscus and overpower surface tension at the nozzle tip such that We⁺ > 12. Drop tower experiments are conducted and compared to analytical predictions using a regimemap. This thesis also includes results from experiments experiments conducted in a stationary ground-based laboratory and aboard the International Space Station which clearly demonstrate droplet ejection in regimes from transient liquid jets to large isolated drops. Droplets generated in a microgravity environment are 106 times larger than 1g₀ counter-parts.

On considère un écoulement compressible bidimensionnel, autour d'une cavité ouverte. Des d'instabilité, auto-entretenues par l'effet de rétroaction de l'écrasement de la couche de cisaillement sur le bord aval de la cavité, génèrent des émissions acoustiques qu'il faut réduire. Des simulations numériques directes (DNS) permettent d'obtenir, avec ou sans actionnement, un modèle précis de l'écoulement. A partir des champs issus de la simulation, des décompositions orthogonales de modes propres (POD) sont proposées pour bâtir, par projection de Galerkin sur les équations isentropiques, des modèles d'ordre réduit non linéaires en prenant en compte l'actionnement (le contrôle). Pour éviter la divergence temporelle, les coefficients du système dynamique non forcé sont calibrés par diverses approches originales dont une basée sur la sensiblité modale. A partir du système dynamique forcé par un actionnement multifréquentiel (présent aussi dans les DNS), un contrôle en boucle fermée linéaire quadratique gaussien est proposé sur un système linéarisé. La reconstruction de l'état est basée sur une estimation stochastique linéaire sur 6 points de pression. Le contrôle optimal obtenu s'avère être périodique à la fréquence du second mode de Rossiter, qui est exactement celles des instabilits auto-entretenues dans la cavité. Par introduction de ce contrôle dans les simulations numériques directes, nous avons obtenu une réduction du bruit (faible) sur la fréquence du contrôle. / We consider a two dimensional compressible flow around an open cavity. The Flow around a cavity is characterised by a self-sustained mechanism in which the shear layer impinges on the downstream edge of the cavity resulting in an acoustic feedback mechanism which must be reduced. Direct Numerical Simulations (DNS) of the flow at a representative Reynolds number has been carried to obtain pressure and velocity fields, both for the case of unactuated and multi frequency actuation. These fields are then used to extract energy ranked coherent structures also called as the Proper Orthogonal Decomposition (POD) modes. A Reduced Order Model is constructed by a Galerkin projections of the isentropic compressible equations. The model is then extended to include the effect of control. To avoid the divergence of the model while integrating in time various calibration techniques has been utillized. A new method of calibration which minimizes a linear functional of error, based on modal sensitivity is proposed. The calibrated low order model is used to design a feedback control of the Linear Quadratic Gaussian (LQG) type, coupled with an observer. For the experimental implementation of the controller, a state estimate based on the observed pressure measurements at 6 different locations, is obtained through a Linear Stochastic Estimation (LSE). The optimal control obtained is periodic with a frequency corresponding to the second Rossiter mode of the cavity. Finally the control obtained is introduced into the DNS to obtain a decrease in spectra of the cavity acoustic mode.

Antiretroviral drugs have revolutionized HIV care and enabled better management of the infection thus allowing patients survive for many years. One proposed approach to increase access to such drugs in sub-Saharan Africa is to use of a reduced-dose alternative of the drug efavirenz, with 400 mg rather than regular 600 mg dose. This effectively would provide medication for 50 percent more persons with the same amount of active ingredient. However, antiretroviral drugs require high patient adherence to achieve intended therapeutic effect, and it is unclear if a reduced-dose therapy would have sufficient efficacy, and if it would lead to an increased risk of viral resistance. The time profile of drug plasma concentration and corresponding long-term viral load was estimated using integrated population PK/PD simulations, with model parameters based on selected research studies. The results suggest a reduced dose 400 mg, rather than 600 mg regular dose, efavirenz in HIV therapy would place strict demands on patients to maintain very high adherence levels, at least 80-90 percent, to maintain sufficient drug concentration in blood plasma, and to minimize risk of viral failure. However, it is relatively rare for HIV therapy programs in sub-Saharan Africa to consistently achieve such high adherence levels. In addition, if patients are co-administered rifampin, a drug widely used in TB care, this increases hepatic metabolism and plasma clearance rate, resulting in further reduced average drug plasma concentration. These findings suggest a reduced dose efavirenz treatment alternative may be most (only) relevant for patient categories expected to maintain high adherence; and in particular among persons who have been confirmed to have CYP2B6 genotype consistent with inherently lower drug metabolism. At usual adherence levels it is estimated a reduced dose alternative may increase the share of patients at risk of viral failure by 5 to 15 percent vs. regular dose of 600 mg.

Master of Science / Department of Food, Nutrition, Dietetics and Health / Sara K. Rosenkranz / Evidence from physical activity interventions suggests that women, in particular, may overcompensate for exercise energy expenditure by increasing caloric intake. Sedentary behavior and poor diet quality are independent risk factors for many major chronic diseases including cardiovascular disease (CVD). It is unknown whether insufficiently active women alter dietary quality or caloric intake when participating in an intervention to reduce sedentary behavior. Insufficiently active women (n=49) working full-time sedentary jobs were randomized into one of two 8-week sedentary interventions occurring during the work week [short breaks (SB) (1-2 min every half hour, n=24) or long breaks (LB) (15 min twice daily, n=25)]. Dietary information was collected through 3-day food records at baseline, week 4 and week 8. Dietary quality was assessed using the Alternative Healthy Eating Index 2010 (AHEI-2010). CVD risk factors (systolic and diastolic blood pressure (BP), fasting cholesterol, triglycerides, and blood glucose, and body mass index) were assessed at baseline and week 8. For all participants there were no changes in AHEI-2010 scores over time (baseline: M=53.4, 95% CI [49.2, 57.6], week 4: M=50.3, 95% CI [45.9, 54.7], week 8: M=48.4, 95% CI [44.1, 52.7], p>0.05). Average caloric intake in the SB group (baseline: M=1943.8 kcals/day, 95% CI [1716.2, 2171.5], week 4: M=1728.8 kcals/day, 95% CI [1462.4, 1995.2], week 8: M=1616.8 kcals/day, 95% CI [1450.2, 1783.4]) decreased significantly from baseline to week 4 (p=0.015) and baseline to week 8 (p=0.002). There were no significant changes in caloric intake in the LB group (p>0.05) at either time point. In all participants, absolute changes in LDL were positively correlated with absolute changes in caloric intake (r=0.473, p=0.005). There were no other significant associations between changes in dietary quality or caloric intake with changes in any other CVD risk factor (p>0.05). Following an 8-week sedentary intervention in the workplace, insufficiently active women did not alter their dietary quality, but decreased caloric intake. Future research should explore sedentary interventions compared to physical activity interventions in women as a means to create negative energy balance, as sedentary breaks throughout the day may be effective for improving health outcomes.

As there is a rapid growth in the field of wireless communications, the demand for various multimedia services is also increasing. The data that is being transmitted suffers from distortions through source encoding and transmission over errorprone channels. Due to these errors, the quality of the content is degraded. There is a need for service providers to provide certain Quality of Experience (QoE) to the end user. Several methods are being developed by network providers for better QoE.The human tendency mainly focuses on distortions in the Region of Interest(ROI) which are perceived to be more annoying compared to the Background(BG). With this as a base, the main aim of this thesis is to get an accurate prediction quality metric to measure the quality of the image over ROI and the BG independently. Reduced Reference Image Quality Assessment (RRIQA), a reduced reference image quality assessment metric, is chosen for this purpose. In this method, only partial information about the reference image is available to assess the quality. The quality metric is measured independently over ROI and BG. Finally the metric estimated over ROI and BG are pooled together to get aROI aware metric to predict the Mean Opinion Score (MOS) of the image.In this thesis, an ROI aware quality metric is used to measure the quality of distorted images that are generated using a wireless channel. The MOS of distorted images are obtained. Finally, the obtained MOS are validated with the MOS obtained from a database [1].It is observed that the proposed image quality assessment method provides better results compared to the traditional approach. It also gives a better performance over a wide variety of distortions. The obtained results show that the impairments in ROI are perceived to be more annoying when compared to the BG.

<p>Asymptotic Modal Analysis (AMA) is a computationally efficient and accurate method for studying the response of dynamical systems experiencing banded, random harmonic excitation at high frequencies when the number of responding modes is large. In this work, AMA has been extended to systems of coupled continuous components as well as nonlinear systems. Several prototypical cases are considered to advance the technique from the current state-of-the-art. The nonlinear problem is considered in two steps. First, a method for solving problems involving nonlinear continuous multi-mode components, called Iterative Modal Analysis (IMA), is outlined. Secondly, the behavior of a plate carrying a nonlinear spring-mass system is studied, showing how nonlinear effects on system natural frequencies may be accounted for in AMA. The final chapters of this work consider the coupling of continuous systems. For example, two parallel plates coupled at a point are studied. The principal novel element of the two-plate investigation reduces transfer function sums of the coupled system to an analytic form in the AMA approximation. Secondly, a stack of three parallel plates where adjacent plates are coupled at a point are examined. The three-plate investigation refines the reduction of transfer function sums, studies spatial intensification in greater detail, and offers insight into the diminishing response amplitudes in networks of continuous components excited at one location. These chapters open the door for future work in networks of vibrating components responding to banded, high-frequency, random harmonic excitation in the linear and nonlinear regimes.</p> / Dissertation