The presence of partial discharges (PD) in high voltage components is generally a sign of defects and degradation in the electrical insulation. To diagnose the condition of high voltage insulation, PD measurements is commonly used. The Variable Frequency Phase Resolved PD Analysis (VF-PRPDA) technique measures PD at variable frequency of the applied voltage. With this technique, the frequency dependence of PD can be utilized to extract more information about the insulation defects than is possible from traditional PD measurements at a single applied frequency. In this thesis the PD process in a disc-shaped cavity is measured and modelled at variable frequency (0.01 - 100 Hz) of the applied voltage. The aim is to interpret the PD frequency dependence in terms of physical conditions at the cavity. The measurements show that the PD process in the cavity is frequency dependent. The PD phase and magnitude distributions, as well as the number of PDs per voltage cycle, change with the varying frequency. Moreover, the PD frequency dependence changes with the applied voltage amplitude, the size of the cavity and the location of the cavity (insulated or electrode bounded). A physical model is presented and used to dynamically simulate the sequence of PDs in the cavity at different applied frequencies. The simulations show that essential features in the measured PD patterns can be reproduced. The PD frequency dependence is interpreted as a variation in influence on the PD activity from the statistical time lag of PD and the charge transport in the cavity surface, at different applied frequencies. The simulation results also show that certain cavity parameters, like the cavity surface conductivity and the rate of electron emission from the cavity surface, change with the time between consecutive PDs, and accordingly with the applied frequency. This effect also contributes to the PD frequency dependence. / QC 20100722

This paper reviews the effectiveness of vehicle activated signs. Vehicle activated signs are being reportedly used in recent years to display dynamic information to road users on an individual basis in order to give a warning or inform about a specific event. Vehicle activated signs are triggered individually by vehicles when a certain criteria is met. An example of such criteria is to trigger a speed limit sign when the driver exceeds a pre-set threshold speed. The preset threshold is usually set to a constant value which is often equal, or relative, to the speed limit on a particular road segment. This review examines in detail the basis for the configuration of the existing sign types in previous studies and explores the relation between the configuration of the sign and their impact on driver behavior and sign efficiency. Most of previous studies showed that these signs have significant impact on driver behavior, traffic safety and traffic efficiency. In most cases the signs deployed have yielded reductions in mean speeds, in speed variation and in longer headways. However most experiments reported within the area were performed with the signs set to a certain static configuration within applicable conditions. Since some of the aforementioned factors are dynamic in nature, it is felt that the configurations of these signs were thus not carefully considered by previous researchers and there is no clear statement in the previous studies describing the relationship between the trigger value and its consequences under different conditions. Bearing in mind that different designs of vehicle activated signs can give a different impact under certain conditions of road, traffic and weather conditions the current work suggests that variable speed thresholds should be considered instead.

Physical habitat for instream biota derives from a combination of stream system structural and hydraulic phenomena. Consequently, the quantity and quality of physical habitat is dynamic both over time and in space along the river, laterally, longitudinally and vertically. Its characterization through stream assessment and classification leads to a better understanding of factors that determine and limit habitat extent and quality. This thesis investigates the effects of space and time on nearshore aquatic habitat in the gravel reach of Fraser River, British Columbia by employing a large river, stage-adaptive habitat classification system. The distribution and abundance of habitat are spatially quantified at the reach scale (32 km), and temporally quantified through a period of about 60 years at several adjacent gravel bars (7 km), and at approximately 500 m3 s-1 increments in discharge during the declining limb of the flood hydrograph at two well-developed gravel bars. Of the ten habitat types evaluated, the bar edge habitat type is most abundant by length and number of units. However, its relative importance is reduced when weighted by fish-habitat association characteristics. Preferred habitat types (channel nook, eddy pool and open nook) are frequent and available to aquatic organisms, and most common at well-developed bars and in zones of equilibrium long-term sedimentation. Preferred habitat was at a maximum 30 years ago when major new bars developed and the thalweg shifted, effectively increasing the amount of bar shoreline and nearshore habitat. This increase is due to substantial change in river planform morphology following a 30-year period of large annual floods. However, amounts of habitat did not increase exclusively during periods of higher than average flows, or decrease exclusively during periods of lower than average flows. Instead, habitat abundance response to flow may occur with a two- or three-year lag. Short term changes in stage are critical to amount of preferred habitat. Optimal discharge for maximum preferred habitat vailability is in the range of approximately 2500 m3 s-1 to 4000 m3 s-1, which approximates long term mean flow. As flow increases, the proportion of preferred habitat compared with total bar shoreline decreases. Comparison with the 2006 flow duration curve shows that 15 – 30 % of discharges are optimal for maximum fish density and biomass. These discharges occurred during April 27 to May 17 and July 14 to August 7, 2006.

The automotive industry has been in a marathon of advancement over the past decades. This is partly due to global environmental concerns about increasing amount of air pollutants such as NOx (oxides of nitrogen), CO (carbon monoxide) and particulate matters (PM) and decreasing fossil fuel resources. Recently due to stringent emission regulations such as US EPA (Environmental Protection Agency) and CARB (California Air Resource Board), improvement in fuel economy and reduction in the exhaust gas emissions have become the two major challenges for engine manufacturers. To fulfill the requirements of these regulations, the IC engines including gasoline and diesel engines have experienced significant modifications during the past decades. Incorporating the fully flexible valvetrains in production IC engines is one of the several ways to improve the performance of these engines. The ultimate goal of this PhD thesis is to conduct feasibility study on development of a reliable fully flexible hydraulic valvetrain for automotive engines. Camless valvetrains such as electro-hydraulic, electro-mechanical and electro-pneumatic valve actuators have been developed and extensively studied by several engine component manufacturers and researchers. Unlike conventional camshaft driven systems and cam-based variable valve timing (VVT) techniques, these systems offer valve timings and lift control that are fully independent of crankshaft position and engine speed. These systems are key technical enablers for HCCI, 2/4 stroke-switching gasoline and air hybrid technologies, each of which is a high fuel efficiency technology. Although the flexibility of the camless valvetrains is limitless, they are generally more complex and expensive than cam-based systems and require more study on areas of reliability, fail safety, durability, repeatability and robustness. On the contrary, the cam-based variable valve timing systems are more reliable, durable, repeatable and robust but much less flexible and much more complex in design. In this research work, a new hydraulic variable valve actuation system (VVA) is proposed, designed, prototyped and tested. The proposed system consists of a two rotary spool valves each of which actuated either by a combination of engine crankshaft and a phase shifter or by a variable speed servo-motor. The proposed actuation system offers the same level of flexibility as camless valvetrains while its reliability, repeatability and robustness are comparable with cam driven systems. In this system, the engine valve opening and closing events can be advanced or retarded without any constraint as well as the final valve lift. Transition from regenerative braking or air motor mode to conventional mode in air hybrid engines can be easily realized using the proposed valvetrain. The proposed VVA system, as a stand-alone unit, is modeled, designed, prototyped and successfully tested. The mathematical model of the system is verified by the experimental data and used as a numerical test bench for evaluating the performance of the designed control systems. The system test setup is equipped with valve timing and lift controllers and it is tested to measure repeatability, flexibility and control precision of the valve actuation system. For fast and accurate engine valve lift control, a simplified dynamic model of the system (average model) is derived based on the energy and mass conservation principles. A discrete time sliding mode controller is designed based on the system average model and it is implemented and tested on the experimental setup. To improve the energy efficiency and robustness of the proposed valve actuator, the system design parameters are subjected to an optimization using the genetic algorithm method. Finally, an energy recovery system is proposed, designed and tested to reduce the hydraulic valvetrain power consumption. The presented study is only a small portion of the growing research in this area, and it is hoped that the results obtained here will lead to the realization of a more reliable, repeatable, and flexible engine valve system.

Med utgångspunkt i den livliga debatt som fördes kring bonusutbetalningar i samband med finanskrisen och det skadade förtroende för rörliga ersättningar den resulterade i syftar denna studie till att undersöka hur man idag återskapar legitima rörliga ersättningssystem. Studien ämnar även svara på frågan varför organisationer, trots stora kostnader, väljer att använda sig av rörliga ersättningssystem. Med agentteorin och nyinstitutionell teori som referensramar genomfördes en kvalitativ undersökning vilken bestod av sex semi-strukturerade expertintervjuer. Tre av dessa intervjuer genomfördes med representanter för tre olika organisationer, två av intervjuerna gjordes med oberoende konsulter som specialiserat sig på utformning av rörliga ersättningssystem och slutligen intervjuades en jurist som arbetar med föreskrifter gällande rörlig ersättning inom den finansiella sektorn. Analys av intervjuerna hanterades med etnografisk kvalitativ metodik som utgångspunkt för att skapa ett kodschema kopplat till vår teori. Två analysmodeller användes sedermera på de koder vi fick fram: Den komparativa analysen och den idealtypcentrerade analysen. I studien framkommer att organisationer alltmer använder sig av transparenta system för sina rörliga ersättningar i syfte att legitimera dessa. Alltfler anställda tenderar även att innefattas i det rörliga ersättningssystemet, oberoende av vilken befattning och funktion de har i organisationen, detta för att skapa en större acceptans för systemet. Resultatet visar att det dock fortfarande finns en klick anställda som i många fall står utanför de nyskapade rörliga ersättningssystemen: den högsta ledningen. Vidare finner vi i studien att organisationer använder rörliga ersättningssystem som en styrteknik; i och med att de kopplat ersättning till måluppfyllnad skapas en acceptans för systemet och ifrågasättande av de uppsatta målen minskar. / Based on the lively debate on bonus payments that took place due to the financial and damaged the trust for variable compensation systems, this study aims to answer the question of how to recover legitimate variable compensation for this present day. The study also intends to answer the question of why organizations, despite great expense, choose to use variable compensation systems. Using the New Institutional theory and the Agency theory as frameworks, a qualitative study is performed consisting of six semi-structured expert interviews. Three of these interviews were conducted with representatives of the three organizations, two of the interviews were conducted by independent consultants specializing in the design of variable compensation systems and the last interview was conducted with an expert on variable compensation in the financial sector. The analysis of the interviews was performed with an ethnographic quantitative methodology as a basis to create a coding scheme linked to the proposed theories. From this approach, the interviews were narrowed down to codes which were then analyzed with two different analytical models: the comparative analysis and the ideal type centered. The study shows that organizations tend to increasingly exceed the transparency in the compensation system in order to legitimize them. In addition, variable compensation systems tend to include a greater number of employees, at various levels and functions within the organization, with the purpose of creating a greater acceptance of the system. Despite this, there are still a group of employees which, to some extent, are outside the system: the top management and directors. Furthermore, this study finds that organizations tend use variable compensation as a control technique, due to the connection between compensation and performance that creates an acceptance of the system and decreases the questioning of goal-setting.

Ce travail de thèse porte sur l'étude de composites magnétoélectriques laminaires dans le but de réaliser des dispositifs innovants intégrés sur silicium tel que l'inductance RF variable. Grâce au couplage mécanique entre des couches adjacentes magnétostrictive ultra douce et piézoélectrique, il est possible d'obtenir un couplage magnétoélectrique indirect qui est supérieur de plusieurs ordres de grandeur à celui des matériaux multiferroïques naturels. Dans un premier temps, nous avons utilisé l'approche phénoménologique basée sur les énergies pour décrire le panorama des effets attendus dans des composites magnétoélectriques laminaires (multicouches). Ensuite, des composites magnétoélectriques macroscopiques à base de substrats piézoélectriques de type MFC et de couches minces de FeCoB ont été réalisés. L'étude du couplage magnétoélectrique en fonction de la composition de FeCoB a permis de déterminer les propriétés clés des matériaux, notamment le rapport λs/Ms, qui sont essentielles pour obtenir un effet magnétoélectrique élevé. Un coefficient magnétoélectrique record de 250 V∙cm‐1Oe‐1 a été obtenu. Par ailleurs, un microscope à effet Kerr a été spécialement développé pour pouvoir observer de manière quasi-instantanée la modification de la structure en domaines sous l'effet de la tension électrique dans ces composites. Pour la première fois, l'observation directe de la rotation de l'axe facile d'aimantation sous commande électrique a été réalisée. La deuxième partie de ce manuscrit est consacrée à la conception, simulation, fabrication et caractérisation d'un dispositif MEMS hybride d'inductance variable intégrée. Ce dispositif exploite l'effet magnétoélectrique indirect entre un élément moteur en PZT (sol gel) et un élément inductif à base de FeCoB. Etant donné le caractère multiphysique hors norme de ce dispositif, un ensemble de tests électriques, mécaniques, optiques et magnétiques a été déployé tout au long de la fabrication. Les résultats concluent à une preuve de concept partiellement fonctionnelle en raison principalement d'une mauvaise gestion des contraintes internes liées à la fabrication. Les pistes d'amélioration aux niveaux du design, des matériaux et des procédés sont identifiées.

A drainage basins runoff response can be determined by the connectivity of generated runoff to the stream network and the connectivity of the downstream stream network. The connectivity of a drainage basin modulates its ability to produce streamflow and respond to precipitation events and is a function of the complex and variable storage capacities along the drainage network. An improved means to measure and account for the dynamics of hydrological connectivity at the basin scale is needed to improve prediction of basin scale streamflow. The overall goal of this thesis is to improve the understanding of hydrological connectivity at the basin scale by measuring hydrological connectivity at the Baker Creek Research Basin during 2009. To this end, the objectives are to 1) investigate the dynamics of hydrological connectivity during a typical water year, 2) define the relationship between the contributing stream network and contributing area, 3) investigate how hydrological connectivity influences streamflow, and 4) define how hydrological connectivity influences runoff response to rainfall events. At a 150 km2 subarctic Precambrian Shield catchment where the poorly-drained heterogeneous mosaic of lakes, exposed bedrock, and soil filled areas creates variable contributing areas, hydrological connectivity was measured between April and September 2009 in 10 sub-basins with a particular focus on three representative sub-basins. The three sub-basins, although of similar relative size, vary considerably in the dominant typology and topology of their constituent elements. At a 10 m spatial resolution, saturated areas were mapped using both multispectral satellite imagery and in situ measurements of storage according to land cover. To measure basin scale hydrological connectivity, the drainage network was treated as a graph network with stream reaches being the edges that connect sub-catchment nodes. The overall hydrological connectivity of the stream network was described as the ratio of actively flowing relative to potentially flowing stream reaches, and the hydrological connectivity of the stream network to the outlet was described as the ratio of actively flowing stream reaches that were connected to the outlet relative to the potentially flowing stream reaches. Hydrological connectivity was highest during the spring freshet but the stream network began to disintegrate with its passing. In some drainage basins, large gate keepers were able to maintain connectivity of the stream network downstream during dry periods. The length of the longest stream was found to be proportional to contributing area raised to a power of 0.605, similar to that noted in Hacks Law and modified Hacks Law relationships. The length of the contributing stream network was also found to be proportional to contributing area raised to a power of 0.851. In general, higher daily average streamflows were noted for higher states of connectivity to the outlet although preliminary investigations allude to the existence of hysteresis in these relationships. Elevated levels of hydrological connectivity were also found to yield higher basin runoff ratios but the shape of the characteristic curve for each basin was heavily influenced by key traits of its land cover heterogeneity. The implications of these findings are that accurate prediction of streamflow and runoff response in a heterogeneous drainage basin with dynamic connectivity will require both an account of the presence or absence of connections but also a differentiation of connection type and an incorporation of aspects of local function that control the flow through connections themselves. The improved understanding of causal factors for the variable streamflow response to runoff generation in this environment will serve as a first step towards developing improved streamflow prediction methods in formerly glaciated landscapes, especially in small ungauged basins.

This thesis contains the numerically investigations of the performance of a run-around membrane energy exchanger (RAMEE) at different outdoor air conditions and the effects of non-uniform exchanger channels. The RAMEE is a new type of building ventilation air energy recovery system that allows heat and moisture to be transferred between isolated supply and exhaust air streams. Two liquid-to-air membrane energy exchangers (LAMEEs) are placed in the supply and exhaust air ducts and transfer heat and moisture between air and a circulating liquid desiccant that couples the two LAMEEs together. The ability of the system to transfer heat and moisture between isolated supply and exhaust ducts makes it appropriate for numerous HVAC applications (e.g., hospitals and building energy retrofits). <p> The performance of the RAMEE at different outdoor air conditions is shown to be highly variable due to the coupling of the heat and moisture transfer by the desiccant. This coupling allows the humidity ratio between the indoor and outdoor air to influence the heat transfer and the moisture transfer is influenced by the difference between the indoor and outdoor air temperatures. The coupling produces some complex RAMEE performance characteristics at some outdoor air conditions where the effectiveness values (i.e., sensible, latent, and total) were shown to be less than 0% or greater than 100%. Effectiveness and operating correlations are developed to describe these complex behaviours because existing correlations do not account for the coupling effects. The correlations can serve as design and operation tools for the RAMEE which do not require the use of an iterative computational numerical model.<p> Non-uniform exchanger channels are present in the RAMEE because of pressure differences between the air and solution channels which deform the membrane into the air channel. The non-uniform channels are analytically shown to create maldistributed fluid flows and variable heat and mass transfer coefficients. The combined effects of these two changes lead to a reduction in the RAMEE effectiveness, which increases as the size of the membrane deformation increases. The reduction in total effectiveness for an exchanger where the membrane has a peak deflection of 10% of the nominal air channel thickness operating at a NTU of 12 was shown to be 12.5%. These results of non-uniform exchanger channels agree with previously conducted experimental results.

Le domaine de la traction électrique a suscité un très grand intérêt dans les dernières années. La conception optimale de l'ensemble moteur électrique de traction - onduleur doit prendre en compte une variété de critères et contraintes. Étant donnée la liaison entre la géométrie du moteur et la stratégie de commande de l'onduleur, l'optimisation de l'ensemble de traction doit prendre en considération, en même temps, les deux composants.L'objectif de la thèse est la conception d'un outil d'optimisation appliqué à un système de traction électrique légère qu'emploie un moteur à réluctance variable alimenté (MRVCE) par un onduleur triphasé en pont complet. Le MRVCE est modélisé en utilisant la technique par réseau de perméances. En même temps, la technique de commande électronique peut être facilement intégrée dans le modèle pour effectuer l'analyse dynamique du fonctionnement du moteur. L'outil d'optimisation réalisé utilise l'algorithme par essaim de particules, modifié pour résoudre des problèmes multi-objectif. Les objectifs sont liés à la qualité des caractéristiques de fonctionnement du moteur, en temps que les variables d'optimisation concernent la géométrie du moteur aussi que la technique de commande. Les performances de l'algorithme sont comparées avec ceux de l'algorithme génétique (NSGA-II) et d'une implémentation classique de l'algorithme par essaim de particules multi-objectif.Finalement, un prototype de moteur à réluctance variable est construit et le fonctionnement du MRVCE alimenté depuis l'onduleur triphasé en pont complet est implémenté et les outils de modélisation et d'optimisation sont validés

The feasibility of using optical sensors and non-nitrogen limiting reference crops to determine post-emergent nitrogen fertilizer requirements of canola was evaluated. Normalized difference vegetation index was well suited for estimating yield potential and nitrogen status. Although sensor-based nitrogen management was generally agronomically feasible for canola, the economic benefits of doing so remain uncertain because of the added cost of applying post-emergent nitrogen. / February 2008