A novel and promising method of software development is the interactive style of development, where code is written and incrementally tested simultaneously. Interpreted dynamic languages such as Ruby, Python, and Lua support this interactive development style. However, because they lack semantic analysis as part of a compilation phase, they do not provide type-checking. The programmer is only informed of type errors when they are encountered in the execution of the programfar too late and often at a less-informative location in the code. We introduce a typing system for Ruby, where types will be determined before execution by inferring principal typings. This system overcomes the obstacles that interactive and dynamic program development imposes on type checking; yielding an effective type-checking facility for dynamic programming languages. Our development is embodied as an extension to irb, the Ruby interactive mode, allowing us to evaluate principal typings for interactive development.

This thesis formulates a conceptual framework developed from field observations that describes the influence of surface depressions or potholes on runoff generation in the prairie pothole region of the North American prairies. The fill-and-spill of potholes results in intermittent surface water connectivity between potholes within the basin. The extent of connectivity between potholes is dependent on antecedent water levels. Dynamic connectivity between potholes results in dynamic contributing areas for runoff. The concept of connectivity is manifested in the conceptual curves presented in this thesis. These conceptual curves model the response of runoff events for landscape types found in the prairie pothole region, and capture the influence of the spatial distribution and extent of surface storage on contributing area. The conceptual curves differ due to variations in the spatial distribution and extent of surface storage volume.<p> An algorithm based on the conceptual framework proposed is presented. The algorithm, which uses the the D-8 drainage direction method, automates a methodology for identifying and quantifying runoff contributing area. The algorithm is applied in prairie pothole basins both to demonstrate its efficacy and to test the potential for using conceptual curves to describe the relationship between decreasing potential surface storage in the landscape and contributing area. The algorithm was applied to two digital elevation models (DEM) representative of the prairie pothole region. The first DEM was created using LiDAR elevation points at a 1 m resolution for the St. Denis watershed, and the second was created from orthophotos for the Smith Creek watershed at a 25 m resolution.<p> Fieldwork in the St. Denis watershed was carried out to both provide a basis for the conceptual framework proposed and to validate the results of the algorithm. The fieldwork involved gathering snow survey data, identifying and describing surface water conditions during a snow melt runoff event in 2006, and measuring pond levels from 2004 2007.<p> Results indicate that the proposed conceptual curves represent the non-linear relationship between potential surface storage and contributing area generated by the algorithm in the test basins. To test whether the underlying concepts of the algorithm were valid, the algorithm was used to model pond level depths measured in the St. Denis drainage basin after spring runoff in 2006 and 2007. An r2 value over 0.9 was calculated for the relationship between measured and modeled pond levels in both years. Based on this work, it is clear that any hydrologic study or model applied in the prairie pothole region should consider the effect of dynamic contributing areas on runoff generation.

For automotive plastic parts there is a clear demand on an increased quality of the FE models. This demand is related to the increased use of simulations, both due to a reduced number of prototypes and an increased number of load cases. There have been studies showing a change of dynamic properties in injection molded components. The conclusion from these studies are that the change depends on residual stresses built in during the injection process. This study use simple models to try to get a working method and from the results find out the basic relations between residual stresses and dynamic properties. A method was developed and the results showed that the residuals had a major impact on the dynamic properties. Continuation on this work would be to use more complex models, to try to mimic results from reference studies and tests.

The survey from US Department of Energy showed that about one-third of energy consumption in US is due to air conditioning and refrigeration systems. This significant usage of electricity in the HVAC industry has prompted researchers to develop dynamic models for the HVAC components, which leads to implementation of better control and optimization techniques. In this research, efforts are made to model a multi-evaporator system. A novel dynamic modeling technique is proposed based on moving boundary method, which can be generalized for any number of evaporators in a vapor compression cycle. The models were validated experimentally on a commercial supermarket refrigeration unit. Simulation results showed that the models capture the major dynamics of the system in both the steady state and transient external disturbances. Furthermore the use of MEMS (microelectromechanical) based Silicon Expansion Valves (SEVs) have reportedly shown power savings as compared to the Thermal Expansion Valves (TEVs). Experimental tests were conducted on a supermarket refrigeration unit fitted with the MEMS valves to explain the cause of these potential energy savings. In this study an advanced cascaded control algorithm was also designed to control the MEMS valves. The performance of the cascaded control architecture was compared with the standard Thermal Expansion Valves (TEVs) and a commercially available Microstaq (MS) Superheat Controller (SHC). The results reveal that the significant efficiency gains derived on the SEVs are due to better superheat regulation, tighter superheat control and superior cooling effects in shorter time period which reduces the total run-time of the compressor. It was also observed that the duty cycle was least for the cascaded control algorithm. The reduction in duty cycle indicates early shut-off for the compressor resulting in maximum power savings for the cascaded control, followed by the Microstaq controller and then the Thermal Expansion Valves.

The use of Mechanically Stabilized Earth (MSE) wall structures has increased dramatically in recent years. Traffic barriers are frequently placed on top of the MSE wall to resist vehicular impact loads. The barrier systems are anchored to the concrete in case of rigid pavement. Nevertheless, in case of flexible pavement, the barriers are constructed in an L shape so that the impact load on the vertical part of the L can be resisted by the inertia force required to uplift the horizontal part of the L. The barrier must be designed to resist the full dynamic load but the size of the horizontal part of the L (moment slab) is determined using an equivalent static load. Current design practice of barriers mounted on top of MSE retaining wall is well defined for passenger cars and light trucks. However, the information of this impact level is extrapolated to heavy vehicle impact. Therefore, the bases of this research is to develop design procedure and to help understand the dynamic behavior of a barrier-moment slab system on top of an MSE wall when subjected to heavy vehicle impact loads. In a first part, numerical analyses were conducted to better understand the behavior of the barrier-moment slab system when subjected to heavy vehicle impact loads. The full-scale impact simulations were used to develop the recommendation for designing and sizing the barrier-moment slab system. In a second part, the barrier-moment slab systems defined to contain heavy vehicle impact loads were placed on top of an MSE wall model to study the kinematic behavior of the system. Loads in the soil reinforcing strips and displacements on the barriers and wall components are evaluated to define recommendation for design of strip reinforcements against pullout and yielding. In a third part, a full-scale crash test on a barrier-moment slab system on top of an instrumented 9.8 ft. (3 m) high MSE wall is described and analyzed. The MSE wall and barrier system were adequate to contain and redirected the vehicle and, therefore, it served as verification of the proposed recommendation. Finally, conclusions are drawn on the basis of the information presented herein.

The leading edge flow structure of the NACA 0012 airfoil is experimentally investigated under dynamic stall conditions (M = 0.1; α = 16.7◦, 22.4◦; Rec = 1× 10^6) using planar particle image velocimetry. The airfoil was dynamically pitched about the 1/4 chord at a reduced frequency, k = 0.1. As expected, on the upstroke the flow remains attached in the leading edge region above the static stall angle, whereas during downstroke, the flow remains separated below the static stall angle. A phase averaging procedure involving triple velocity decomposition in combination with the Hilbert transform enables the entire dynamic stall process to be visualized in phase space, with the added benefit of the complete phase space composed of numerous wing oscillations. The formation and complex evolution of the leading edge vortex is observed. This vortex is seen to grow, interact with surrounding vorticity, detach from the surface, and convect downstream. A statistical analysis coupled with instantaneous realizations results in the modification of the classical dynamic stall conceptual model, specifically related to the dynamics of the leading edge vortex.

This thesis consists of three chapters pertaining to issues of long-term relationships in labour markets. In Chapter 1, I analyze a model of a two-period advice game. The decision maker chooses to retain or replace the advisor after the first period depending on the first period events. Even though the decision maker and the advisor have identical preferences, this potential replacement creates incentive for the advisor to avoid telling the truth. I show the condition under which the decision maker can find a random retention rule that induces a truthful report from the advisor, and I characterize an optimal retention rule that maximizes the decision maker's expected payoff. In Chapter 2, I propose a search theoretic model of optimal employment contract under repeated moral hazard. The model integrates two important attributes of the labour market: workers' work incentive on the job and their mobility in the labour market. Even though all workers and firms are ex ante homogeneous, these two factors jointly generate (1) wages and productivity that increase with worker's tenure and (2) endogenous dynamic heterogeneity of the labour productivity of the match. The interaction of these factors provides novel implications for wage dispersion, labour mobility, and the business cycle behaviour of macroeconomic variables. Lastly, in Chapter 3, I quantitatively assess wage dispersion and business cycle implications of the model developed in Chapter 2. In terms of wage dispersion, the model with on-the-job search with wage-tenure contracts seems to accommodate sizable frictional wage dispersion. The model, however, generates very small productivity difference among workers, and shows weak evidence that the productivity difference generated by the endogenous variations in incentives is responsible for frictional wage dispersion. In terms of business cycle implications, workers' endogenous effort choice first amplifies the effect of productivity shock on unemployment rate. Second, responses of workers to productivity shocks generate marked difference between the effects of temporary productivity shock and that of permanent shock. Third, the analysis shows the importance of the distributional effect on macroeconomic variables during the transitory periods after a shock.

This thesis aims to reveal the magnitude of the income elasticity of health expenditure and the impact of non-income determinants of health expenditures in the Canadian Provinces. Health can be seen as a luxury good if the income elasticity exceeds unity and as a necessity good if the income elasticity is below unity. The motivation behind the analysis of the determinants of health spending is to identify the forces that drive the persistent increase in health expenditures in Canada and to explain the disparities in provincial health expenditures, thereby to prescribe sustainable macroeconomic policies regarding health spending. Panel data on real per capita GDP, relative price of health care, the share of publicly funded health expenditure, the share of senior population and life expectancy at birth have been used to investigate the determinants of Canadian real per capita provincial total, private and government health expenditures for the period 1975-2002. Dynamic models of health expenditure are analyzed via Generalized Instrumental Variables and Generalized Method of Moments techniques. Evidence confirms that health is far from being a luxury for Canada and government health expenditures are constrained by the relative prices. Results also cast doubt upon the power of quantitative analysis in explaining the increasing health expenditures.

This thesis consists of three chapters pertaining to issues of long-term relationships in labour markets. In Chapter 1, I analyze a model of a two-period advice game. The decision maker chooses to retain or replace the advisor after the first period depending on the first period events. Even though the decision maker and the advisor have identical preferences, this potential replacement creates incentive for the advisor to avoid telling the truth. I show the condition under which the decision maker can find a random retention rule that induces a truthful report from the advisor, and I characterize an optimal retention rule that maximizes the decision maker's expected payoff. In Chapter 2, I propose a search theoretic model of optimal employment contract under repeated moral hazard. The model integrates two important attributes of the labour market: workers' work incentive on the job and their mobility in the labour market. Even though all workers and firms are ex ante homogeneous, these two factors jointly generate (1) wages and productivity that increase with worker's tenure and (2) endogenous dynamic heterogeneity of the labour productivity of the match. The interaction of these factors provides novel implications for wage dispersion, labour mobility, and the business cycle behaviour of macroeconomic variables. Lastly, in Chapter 3, I quantitatively assess wage dispersion and business cycle implications of the model developed in Chapter 2. In terms of wage dispersion, the model with on-the-job search with wage-tenure contracts seems to accommodate sizable frictional wage dispersion. The model, however, generates very small productivity difference among workers, and shows weak evidence that the productivity difference generated by the endogenous variations in incentives is responsible for frictional wage dispersion. In terms of business cycle implications, workers' endogenous effort choice first amplifies the effect of productivity shock on unemployment rate. Second, responses of workers to productivity shocks generate marked difference between the effects of temporary productivity shock and that of permanent shock. Third, the analysis shows the importance of the distributional effect on macroeconomic variables during the transitory periods after a shock.

Las aplicaciones paralelas presentan diversos problemas de prestaciones al ser cambiadas para ejecutar en entornos Grid. Las características del sistema pueden ser diferentes en cada ejecución y en algunos casos dentro de una misma ejecución. Los recursos remotos comparten enlaces de red y, los procesos de la aplicación comparten las maquinas con otros procesos. En esos escenarios se propone el uso de la técnica de sintonización dinámica de prestaciones para ayudar las aplicaciones a adaptarse a los cambios en las características del sistema con la intención de resolver los problemas de prestaciones. Esta tesis analiza el problema de la ejecución de aplicaciones paralelas en entornos Grid, herramientas para el análisis de prestaciones disponibles y modelos adecuados para la sintonización dinámica de aplicaciones paralelas en este tipo de entorno. De este análisis, se propone una arquitectura para sintonización dinámica de aplicaciones paralelas en entornos Grid llamada GMATE. Esta arquitectura incluye diversas contribuciones. En el caso donde un gestor de recursos de alto nivel decide el mapeo de procesos de la aplicación, se proponen dos aproximaciones para el seguimiento de procesos que habilita GMATE a localizar donde las capas de software del Grid ha mapeado los procesos de la aplicación. Una aproximación consiste en la integración de GMATE a las capas de software del Grid. La otra integra los componentes requeridos de GMATE dentro de los binarios de la aplicación. El primer enfoque requiere derechos de administración en cuanto que el segundo incrementa el binario del la aplicación, lo que torna más lento el arranque de la misma. Para respetar las políticas de las organizaciones propietarias de los recursos, todas las comunicaciones usan el mismo certificado de seguridad de la aplicación. Esas comunicaciones son hechas con base en las capas del Grid. Esta aproximación habilita la arquitectura a monitorizar y sintonizar los procesos de la aplicación de forma dinámica a las restricciones de cortafuegos de las organizaciones y políticas de uso de la red en las mismas. Para bajar la necesidad de comunicaciones en la arquitectura GMATE, se encapsula parte de la lógica requerida para colectar las medidas y para cambiar los parámetros de la aplicación en componentes encuestados que ejecutan dentro de espacio de memoria del proceso de la aplicación. Para colectar medidas, se ha creado componentes sensores que disminuyen la necesidad de comunicaciones llevando el procesamiento de eventos para dentro del proceso de la aplicación. Diferente de la instrumentación tradicional, los sensores pueden retrasar la transmisión de los eventos y ejecutar operaciones básicas como sumas, temporizadores, promedios o generación de eventos basados en umbrales. Esas capacidades reducen los requerimientos de comunicaciones que son útiles en situaciones de bajo ancho de banda. Se propone también el encapsulamiento de la lógica de cambio en las aplicaciones en componentes actuadores. Los actuadores son instalados en el flujo de ejecución de la aplicación y posibilita la sincronización y baja intrusión en cambio de variables y ejecución de funciones para modificar la aplicación. La arquitectura propuesta posibilita la comunicación entre sensores y actuadores lo cual habilita la sintonizaciones sencillas sin necesidad de comunicaciones. Para aplicar la sintonización dinámica en entornos Grid, necesitamos de un modelo de prestaciones que pueda ser usado en entornos con heterogeneidad de red y procesadores para guiar el proceso. Se propone un modelo de prestaciones basado en una heurística para lograr usar el máximo número de esclavos y el mejor tamaño de grano en una ejecución Maestro-Esclavo en sistemas Grid. Se considera que una clase de aplicaciones pueden ser desarrolladas con la capacidad de cambiar el tamaño de grano en tiempo de ejecución y que esa acción cambia la relación entre cómputo y comunicación. En el escenario donde usuarios reciben un conjunto de recursos para una ejecución paralela, esos recursos pueden configurar un sistema de múltiples clústeres. La heurística del modelo presentado permite guiar la selección de los recursos para disminuir el tiempo total de ejecución de la aplicación. Se intenta buscar el punto donde el maestro usa el máximo número de esclavos posible asignando prioridad a aquellos más rápidos. Se presentan los resultados de sintonización del tamaño de grano y número de esclavos en ejecuciones Maestro-Esclavo en entornos Grid donde se logra bajar el tiempo total de ejecución de la aplicación y aumentando la eficiencia de uso de los recursos. Se presentan las implementaciones de las aplicaciones multiplicación de matrices, N-Body y cargas sintéticas las cuales tienen diferentes grados en la relación entre cómputo y comunicación en escenarios de cambio del tamaño de grano. / When moving to Grid Computing, parallel applications face several performance problems. The system characteristics are different in each execution and sometimes within the same execution. Remote resources share network links and in some cases, the processes share machines using per-core allocation. In such scenarios we propose to use automatic performance tuning techniques to help an application adapt itself thus a system changes in order to overcome performance bottlenecks. This thesis analyzes such problems of parallel application execution in Computational Grids, available tools for performance analysis and models to suit automatic dynamic tuning in such environments. From such an analysis, we propose system architecture for automatic dynamic tuning of parallel applications on computational Grids named GMATE. Its architecture includes several contributions. In cases where a Grid meta-scheduler decides application mapping, we propose two process tracking approaches that enable GMATE to locate where a Grid middleware maps application processes. One approach consists of the integration of GMATE components as Grid middleware. The other involves the need to embed a GMATE component inside application binaries. The first requires site administration privileges while the other increases the application binary which slows down application startup. To obey organizational policies, all communications use the same application security certificates for authentication. The same communications are performed using Grid middleware API. That approach enables the monitoring and tuning process to adapt dynamically to organizational firewall restrictions and network usage policies. To lower the communication needs of GMATE, we encapsulate part of the logic required to collect measurements and change application parameters in components that run inside the processing space. For measurements collection, we create sensor components that reduce the communication needs by event processing inside the process space. Different from traditional instrumentation, sensors can postpone the event transmission and perform basic operations such as summarizations, timers, averages or threshold based event generation. That reduces the communication requirements in cases where network bandwidth is expensive. We also encapsulate the modifications used to tune the application in components called actuators. Actuators may be installed at some point in the program flow execution and provide synchronization and low overhead control of application variables and function executions. As sensors and actuators can communicate with each other, we can perform simple tuning within process executions without the need for communication. As the dynamic tuning is performance model-centric, we need a performance model that can be used on heterogeneous processors and network such Grid Systems. We propose a heuristic performance model to find the maximum number of workers and best grain size of a Master-Worker execution in such systems. We assume that some classes of application may be built capable of changing grain size at runtime and that change action can modify an application's compute-communication ratio. When users request a set of resources for a parallel execution, they may receive a multi-cluster configuration. The heuristic model allows for shrinking the set of resources without decreasing the application execution time. The idea is to reach the maximum number of workers the master can use, giving high priority to the faster ones. We presented the results of the dynamic tuning of grain size and the number of workers in Master-Worker applications on Grid systems, lowering the total application execution time while raising system efficiency. We used the implementation of Matrix-Multiplication, N-Body and synthetic workloads to try out different compute-communication ratio changes in different grain size selections.