Thermal stream loadings from both natural and anthropogenic sources have significant relevance with respect to ecosystem health and water resources management, particularly in the context of future climate change. In recent years, there has been an increase in field-based research directed towards characterizing thermal energy transport exchange processes that occur at the surface water/groundwater interface of streams. In spite of this effort, relatively little work has been performed to simulate these exchanges and elucidate their roles in mediating surface water temperatures and to simultaneously take into account all the pertinent hydrological, meteorological and surface/variably-saturated subsurface processes. To address this issue, HydroGeoSphere, a fully-integrated surface/subsurface flow and transport model, was enhanced to include fully-integrated thermal energy transport. HydroGeoSphere can simulate water flow, evapotranspiration, and advective-dispersive heat and solute transport over the 2D land surface and water flow and heat and solute transport in 3D subsurface variably-saturated conditions. In this work, the new thermal capabilities of HydroGeoSphere are tested and verified by comparing HydroGeoSphere simulation results to those from a previous subsurface thermal groundwater injection study, and also by simulating an example of atmospheric thermal energy exchange. A proof of concept simulation is also presented which illustrates the ability of HydroGeoSphere to simulate fully-integrated surface/subsurface thermal energy transport. High-resolution 3D numerical simulations of a well-characterized reach of the Pine River in Ontario, Canada are also presented to demonstrate steady-state thermal energy transport in an atmosphere-groundwater-surface water system. The HydroGeoSphere simulation successfully matched the spatial variations in the thermal patterns observed in the river bed, the surface water and the groundwater. Transient simulations of the high-resolution Pine River domain are also presented. Diurnal atmospheric conditions were incorporated to illustrate the importance of fluctuations in atmospheric parameters on the entire hydrologic regime. The diurnal atmospheric input fluxes were found to not only change the temperatures of the surface and subsurface throughout the cycle, but also the magnitude and direction of the transfer of thermal energy between the surface and subsurface. Precipitation events were also simulated for the Pine River domain using three different rainfall rates. The surface temperatures responded quickly to the rainfall events, whereas the subsurface temperatures were slower to respond in regions where infiltration was not significant. A thermal energy signal from the precipitation event was evident in the subsurface, and dissipated once the rainfall ceased. This indicates that temperature can potentially be used as a tracer for hydrograph separation. The potential of a thermal energy tracer for hydrograph separation was investigated using HydroGeoSphere simulations of the Borden rainfall-runoff experiment. These results matched both measured and previous simulation results using a bromide tracer. The hydrograph separation results from the thermal energy tracer were sensitive to temperature conditions in the subsurface, although this sensitivity reduced considerably when the precipitation event and subsurface temperatures were significantly different. The contribution of each atmospheric component to thermal energy transport was investigated using the Pine River and Borden examples. Each atmospheric component was individually neglected from the simulation of both sites to investigate their impact on thermal energy transport. The results show that longwave radiation dominates the atmospheric inputs for the Borden example, whereas shortwave radiation dominates in the Pine River example. This indicates that the atmospheric contributions to the thermal energy distribution are site-specific and cannot be generalized. In addition, these results indicate that the atmospheric contributions should not be ignored; measuring atmospheric data in the field is an important component in developing an accurate thermal energy transport model. The addition of thermal energy transport to HydroGeoSphere provides a valuable tool for investigating the impact of anthropogenic and non-anthropogenic changes to the atmospheric and hydrological thermal energy system. This computational framework can be used to provide quantitative guidance towards establishing the conditions needed to maintain a healthy ecosystem.

Thermal stream loadings from both natural and anthropogenic sources have significant relevance with respect to ecosystem health and water resources management, particularly in the context of future climate change. In recent years, there has been an increase in field-based research directed towards characterizing thermal energy transport exchange processes that occur at the surface water/groundwater interface of streams. In spite of this effort, relatively little work has been performed to simulate these exchanges and elucidate their roles in mediating surface water temperatures and to simultaneously take into account all the pertinent hydrological, meteorological and surface/variably-saturated subsurface processes. To address this issue, HydroGeoSphere, a fully-integrated surface/subsurface flow and transport model, was enhanced to include fully-integrated thermal energy transport. HydroGeoSphere can simulate water flow, evapotranspiration, and advective-dispersive heat and solute transport over the 2D land surface and water flow and heat and solute transport in 3D subsurface variably-saturated conditions. In this work, the new thermal capabilities of HydroGeoSphere are tested and verified by comparing HydroGeoSphere simulation results to those from a previous subsurface thermal groundwater injection study, and also by simulating an example of atmospheric thermal energy exchange. A proof of concept simulation is also presented which illustrates the ability of HydroGeoSphere to simulate fully-integrated surface/subsurface thermal energy transport. High-resolution 3D numerical simulations of a well-characterized reach of the Pine River in Ontario, Canada are also presented to demonstrate steady-state thermal energy transport in an atmosphere-groundwater-surface water system. The HydroGeoSphere simulation successfully matched the spatial variations in the thermal patterns observed in the river bed, the surface water and the groundwater. Transient simulations of the high-resolution Pine River domain are also presented. Diurnal atmospheric conditions were incorporated to illustrate the importance of fluctuations in atmospheric parameters on the entire hydrologic regime. The diurnal atmospheric input fluxes were found to not only change the temperatures of the surface and subsurface throughout the cycle, but also the magnitude and direction of the transfer of thermal energy between the surface and subsurface. Precipitation events were also simulated for the Pine River domain using three different rainfall rates. The surface temperatures responded quickly to the rainfall events, whereas the subsurface temperatures were slower to respond in regions where infiltration was not significant. A thermal energy signal from the precipitation event was evident in the subsurface, and dissipated once the rainfall ceased. This indicates that temperature can potentially be used as a tracer for hydrograph separation. The potential of a thermal energy tracer for hydrograph separation was investigated using HydroGeoSphere simulations of the Borden rainfall-runoff experiment. These results matched both measured and previous simulation results using a bromide tracer. The hydrograph separation results from the thermal energy tracer were sensitive to temperature conditions in the subsurface, although this sensitivity reduced considerably when the precipitation event and subsurface temperatures were significantly different. The contribution of each atmospheric component to thermal energy transport was investigated using the Pine River and Borden examples. Each atmospheric component was individually neglected from the simulation of both sites to investigate their impact on thermal energy transport. The results show that longwave radiation dominates the atmospheric inputs for the Borden example, whereas shortwave radiation dominates in the Pine River example. This indicates that the atmospheric contributions to the thermal energy distribution are site-specific and cannot be generalized. In addition, these results indicate that the atmospheric contributions should not be ignored; measuring atmospheric data in the field is an important component in developing an accurate thermal energy transport model. The addition of thermal energy transport to HydroGeoSphere provides a valuable tool for investigating the impact of anthropogenic and non-anthropogenic changes to the atmospheric and hydrological thermal energy system. This computational framework can be used to provide quantitative guidance towards establishing the conditions needed to maintain a healthy ecosystem.

Lead (Pb) levels in tap water below the established water safety guideline are now considered harmful, thus detecting sub-parts-per-billion level Pb is important. This thesis reports on a miniaturized Copper (Cu)−based electrochemical sensor fabricated from thick film electrodes for their superior sensing performance. These thick film electrodes are based on highly conductive rolled-annealed Cu foil that has a compact bulk structure, but these advantages are often offset by the fact that RA Cu foil is difficult to bond to a substrate due to poor film-adhesion property and lack of mechanical interlocks. For this reason, we develop a direct bonding process for Cu/polymer. An integrated three-electrode planar configuration is then fabricated on the bonded specimen to achieve a fully-functional sensor that can detect 0.2 μg/L (0.2 ppb) Pb2+ ions from a 100 μL sample in only 30 s. This is the most rapid detection of Pb featured to date by an all Cu-based sensor. This thesis first focuses on improving substrate adhesion of RA Cu foil to liquid crystal polymer (LCP). This is achieved by a surface activated bonding process where Cu and LCP surfaces are treated with low-power reactive ion etching oxygen plasma followed by low-pressure contact at 230 °C. This treatment produces hydroxyl (OH−) groups on Cu and LCP surfaces making them highly hydrophilic. When Cu and LCP are contacted and heated, the OH− chains condense by dehydration and form an intermediate oxide layer. This layer mainly develops as Cu2O nanoparticles from the plasma-treated Cu side due to thermal oxidation in air. These nanoparticles diffuse into the polymer substrate when heated under mechanical pressure, resulting in a strongly bonded flexible specimen for the sensor. A simple, inexpensive, and production-friendly fabrication process is then developed for these sensors. Following direct bonding, flexible Cu/LCP is fed into a LaserJet printer for a one-step transfer of polyester resin−based electrode mask on Cu. This is followed by etching, packaging, and a chlorinating process to achieve a fully-functional integrated sensor. The sensing performance of directly bonded Cu/LCP is comparable to that of commercially available Cu/polyimide (PI) laminate. Our approach holds promise towards realizing low-cost integrated water quality monitoring systems. / Thesis / Master of Applied Science (MASc) / Lead contamination in tap water has major health risks for which monitoring of its levels is important. In this thesis, we develop a low-cost copper/polymer-based lead sensor. The sensor is fabricated from high-quality metal foil electrodes that are integrated to a polymer substrate by a direct bonding process. This enables strong adhesion of foil-based electrodes to the substrate that is crucial to the sensor performance and packaging integrity. We investigate the bonding mechanism between copper and polymer to understand the fundamentals of materials integration. These findings will lead to the development of polymer-based sensors and integrated systems. The bonded sensor bases are mechanically flexible, which facilitates a rapid and low-cost fabrication process using a laser printer. The developed sensor has a fast response time (30 s) and can detect very low levels of lead, thus making it suitable for water quality monitoring applications in under-developed and developed countries with legacy water systems that have not been upgraded yet.

Transfer between community colleges and four-year institutions has become more common as student mobility increases. Accordingly, the higher education system has coped with the fluidity by establishing articulation agreements that facilitate pathways from one institution to another. The forward-facing policies and guides to inform students on those pathways are known to be complicated, leading to the development of web-based tools like Transferology to help students navigate the system. Still, credit loss is common, whether through misunderstandings, lack of awareness, or changing degree plans. A proliferation of literature examines the experiences of transfer students and other agents in the process like community college advisors, but few pieces interrogate the underlying website structures that facilitate those experiences as the unit of analysis. Information related to facilitating transfer from one institution to another is often fragmented across multiple webpages or policies and uses language not optimal for communicating with students – creating what are called "information asymmetries" between the students and institutions. The premise of an exchange having information asymmetries is that one or more parties in the exchange have more or better information than the others, leading to an imbalance in power. In the case of higher education, transfer students – and their advisors by extension – can be subjected to manipulation by the invisible hands of the four-year institutions through language gaps and scattered sources of information. Accordingly, this dissertation explored four-year university websites, a major point of contact students have with information on transfer, to address the following main research question: "How are information asymmetries in curricular policies/procedures apparent for engineering students on institutional webpages in terms of language and fragmentation?" The subsequent research question synthesized the results of the first question: "Looking across information asymmetry measures, what are the different narratives of information asymmetry that integrate themes of language and fragmentation across institutions?" A fully integrated mixed methods design using all existing data was employed to address the two research questions. A stratified random sample was taken with respect to institution size based on their Carnegie classifications (n = 38). The collection of relevant public webpages based on a set of keywords from the sampled institutions was transformed into three network measures - hierarchy, centrality, and nonlinear – that were used in cluster analyses to group the institutions based on their information structures. Sequential mixed methods sampling was used to choose institutions purposefully from each cluster based on notable features recorded during the first stage of data collection. Two-cycle coding followed the cluster analysis by elaborating on the networks formed during data collection. I used joint displays to organize the networks and In-Vivo codes in the same picture and develop themes related to fragmentation and language simultaneously. K-means and K-medoids cluster methods both produced the same four cluster solution illustrating one aspect of information asymmetries through fragmentation. The clustering solution highlighted four major network patterns, plus one cluster mixing two of the patterns: 1) linear browsing, 2) centralized expansive browsing, 3) branched browsing, and 4) mixed browsing. Further qualitative analysis of the sampled institutions revealed several types of missteps where information is obscured through language or dispersed in the network. I explored a subset of 16 institutions and identified four themes related to fragmentation (unlinked divergence, progressive disclosure, lack of uniformity, and neighborhood linking) and six themes related to language (hedging transferability and applicability, legalese handwaving, building rapport, exclusivity, deviance from common practice, and defining terms). The missteps were contextualized further using six narratives with institutional examples. This work characterized the information design for transfer students as a messy web of loosely connected structures with language that complicates understanding. Integrated narratives illustrate a landscape of loosely coupled information structures that become more expansive as state initiatives interact with already existing local agreements. Moreover, institutional websites describing transfer processes use communication strategies similar to private companies writing online privacy policies. In light of the themes of information asymmetries, opportunities for supporting transfer were highlighted. For example, institutions are encouraged to create visual representations of the transfer credit process, ensure terms are defined upfront while minimizing jargon, and avoid linking to information that is easily summarizable on the current page. This research would be of interest to institutions looking to improve the presentation of their transfer information by critically examining their designs for the missteps described here. In addition, engineering education practitioners and researchers studying transfer student pathways and experiences will find the results of interest – especially in considering how to support the students despite the large information gaps. Finally, those looking to implement a fully integrated mixed methods design or use existing/archival data in their own context will find the use of mixing strategies of interest. / Doctor of Philosophy / Transfer between community colleges and four-year institutions has become more common as student mobility increases, especially for engineering. Institutions have coped with this inter-institutional movement by establishing agreements with each other that facilitate pathways between programs. The forward-facing policies and guides to inform students on such pathways are known to be complicated, leading to the development of web-based tools like Transferology to help students navigate the system. Despite these advances, transfer students continue to struggle in their information search. The purpose of this dissertation was to describe the extent to which information for engineering transfer students is scattered across multiple web-based sources and written in a manner not conducive to understanding. I used a fully integrated mixed methods design to create narratives capturing the interactions between the more quantitative idea of scatter using network analysis and the more qualitative aspect of language-use using visually based two-cycle coding across 38 U.S. four-year institutions. All data was readily available online, which were transformed and combined using several mixing strategies to form integrated stories of information asymmetries. The resulting narratives characterized the information design for transfer students as a messy web of loosely connected structures with language that complicates understanding. Moreover, institutional websites describing transfer processes use communication strategies similar to private companies writing online privacy policies. In light of the themes of information asymmetries, opportunities for supporting transfer were highlighted. This work will be of interest to those interested in engineering transfer student experiences and pathways. Also, those looking to implement fully integrated mixed methods approaches or make extensive use of existing data, especially mixing during analysis, will see strategies applicable in their own work.

Expatriates’ adjustment to the host-country culture is a dynamic and gradual process. This process can be facilitated by cross-cultural training. The relationship between cross-cultural training and crosscultural adjustment has been explored to a great extent in the literature, however scholars have mainly put focus on how this relationship unfolds in the context of MNCs offering CCT in-house. Consequently, this leaves an interesting uninvestigated gap in terms of how fully integrated relocation service companies work with cross-cultural services and how their work can facilitate cross-cultural adjustment. This qualitative case-study therefore aims to examine the relationship between crosscultural training provided by a relocation service company and the expatriate adjustment process. An extensive review on existing theories concerning cross-cultural adjustment, cross-cultural training and cross-cultural learning are presented. After this, the case study examines how Nordic Relocation Group (NRG), a relocation service company in Sweden, operates in terms of providing cross-cultural services. The findings indicate that the relocation service company’s services are divided into different phases, whereby the timing and content of services offered varies as the expatriates’ international assignment develops over time. This form of tailoring the cross-cultural training and the content of their services supports the notion of sequential training, which within IHRM literature, is proposed as optimal in order to facilitate the expatriate’s adjustment process. Moreover, the results further indicate that the way in which NRG works with cross-cultural services, in terms of strategy, sequential order, and specific CCT activities offered, promotes effective cross-cultural learning. Consequently, the CCT strategies offered by the relocation service company can be viewed as being aligned with best practice.

A fully integrated, fast-locking fractional-N frequency synthesizer is proposed and demonstrated in this work. In this design, to eliminate the need for large, inaccurate capacitors and resistors in a loop filter, an analog continuous-time loop filter whose performance is sensitive to process and temperature variations and aging has been replaced with a programmable digital Finite Impulse Response (FIR) filter. In addition, using the adaptive loop gain control proportional to the frequency difference, the frequency-locking time has been reduced. Also, the phase noise and spurs have been reduced by a Multi-stAge noise SHaping (MASH) controlled Fractional Frequency Detector (FFD) that generates a digital output corresponding directly to the frequency difference. The proposed frequency synthesizer provides many benefits in terms of high integration ability, technological robustness, fast locking time, low noise level, and multimode flexibility. To prove performance of the proposed frequency synthesizer, the frequency synthesizers analysis, design, and simulation have been carried out at both the system and the circuit levels. Then, the performance was also verified after fabrication and packaging.

abstract: Power management integrated circuit (PMIC) design is a key module in almost all electronics around us such as Phones, Tablets, Computers, Laptop, Electric vehicles, etc. The on-chip loads such as microprocessors cores, memories, Analog/RF, etc. requires multiple supply voltage domains. Providing these supply voltages from off-chip voltage regulators will increase the overall system cost and limits the performance due to the board and package parasitics. Therefore, an on-chip fully integrated voltage regulator (FIVR) is required. The dissertation presents a topology for a fully integrated power stage in a DC-DC buck converter achieving a high-power density and a time-domain hysteresis based highly integrated buck converter. A multi-phase time-domain comparator is proposed in this work for implementing the hysteresis control, thereby achieving a process scaling friendly highly digital design. A higher-order LC notch filter along with a flying capacitor which couples the input and output voltage ripple is implemented. The power stage operates at 500 MHz and can deliver a maximum power of 1.0 W and load current of 1.67 A, while occupying 1.21 mm2 active die area. Thus achieving a power density of 0.867 W/mm2 and current density of 1.377 A/mm2. The peak efficiency obtained is 71% at 780 mA of load current. The power stage with the additional off-chip LC is utilized to design a highly integrated current mode hysteretic buck converter operating at 180 MHz. It achieves 20 ns of settling and 2-5 ns of rise/fall time for reference tracking. The second part of the dissertation discusses an integrated low voltage switched-capacitor based power sensor, to measure the output power of a DC-DC boost converter. This approach results in a lower complexity, area, power consumption, and a lower component count for the overall PV MPPT system. Designed in a 180 nm CMOS process, the circuit can operate with a supply voltage of 1.8 V. It achieves a power sense accuracy of 7.6%, occupies a die area of 0.0519 mm2, and consumes 0.748 mW of power. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2019

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Les composants de puissance grand gap présentent d'ores et déjà des caractéristiques statiques et dynamiques supérieures à leurs homologues en silicium. Mais ces composants d'un nouvel ordre s'accompagnent de différences susceptibles de modifier le fonctionnement de la cellule de commutation. Les travaux qui furent menés au cours de cette thèse se sont intéressés aux composants grand gap et à leur commande au sein d'un convertisseur de puissance synchrone robuste, haut rendement et haute densité de puissance. En particulier deux points critiques ont été identifiés et étudiés. Le premier est la grande sensibilité des composants grand gap aux composants parasites. Le second est l'absence de diode parasite interne entre le drain et la source de nombreux transistors grand gap. Pour répondre aux exigences de ces nouveaux composants et en tirer le meilleur profit, nous proposons des solutions innovantes, robustes, efficaces et directement intégrables aux circuits de commande. Des circuits de commande entièrement intégrés ont ainsi été conçus spécifiquement pour les composants grand gap. Ceux-ci permettent entre autres le contrôle précis des formes de commutation par l'adaptation de l'impédance de grille, et l'amélioration de l'efficacité énergétique et de la robustesse d'un convertisseur de puissance à base de composants grand sans diodes par une gestion dynamique et locale de temps morts très courts. / Wide band gap devices already demonstrate static and dynamic performances better than silicon transistors. Compared to conventional silicon devices these new wide band gap transistors have some different characteristics that may affect power converter operations. The work presented in this PhD manuscript deals with a specific gate drive circuit for a robust, high power density and high efficiency wide band gap devices-based power converter. Two critical points have been especially studied. The first point is the higher sensitivity of wide band gap transistors to parasitic components. The second point is the lack of parasitic body diode between drain and source of HEMT GaN and JFET SiC. In order to drive these new power devices in the best way we propose innovative, robust and efficient solutions. Fully integrated gate drive circuits have been specifically developed for wide band gap devices. An adaptive output impedance gate driver provides an accurate control of wide band gap device switching waveforms directly on its gate side. Another gate drive circuit improves efficiency and reliability of diode-less wide band gap devices-based power converters thanks to an auto-adaptive and local dead-time management.