A series of studies was undertaken at Plastic Lake-1 (PC1) to determine the sources and controls on S cycling in small headwater catchments on the Precambrian Shield in south-central Ontario. Two observations were made about the S cycle in this region: (1) all streams exhibit highly coherent temporal patterns in SO4 concentrations and export, and (2) most catchments exported more SO4 in stream water than is received in bulk deposition during the past 2 decades. Synchronous temporal patterns in annual SO4 concentrations in both upland and wetland-draining streams were related to changes in climate, specifically those factors that determine catchment dryness. The number of days with no stream flow or stream flow below a critical threshold was a good predictor of the average stream SO4 concentration in a particular year. Sulphate chemistry in the PC1 outflow is highly dependent on processes occurring in a conifer <i>Sphagnum</i> swamp located immediately upstream of the chemical sampling station. Hydrologic inputs to the swamp during the summer determine whether S is retained or released from peat on an annual basis. Drying and re-wetting of <i>Sphagnum</i>-derived peat caused a substantial increase in soluble SO4 in laboratory experiments, which was slightly enhanced at higher temperature, but alternating moisture conditions had no immediate effect on <i>Sphagnum</i>. Despite large inter-annual changes in SO4 release, over the long-term (<i>i. e. </i> 20-years) SO4 inputs and exports from the swamp are in approximate balance. In contrast, the upland portion of PC1 (<i>i. e. </i> PC1-08) consistently exports more SO4 than is input in bulk deposition in every year of record. Even when inputs are increased to account for potential underestimates in dry deposition or weathering, the majority of catchments in this region exhibit net export in many years. Two internal sources are suggested to account for negative budgets: desorption and mineralization. Adsorption/desorption reactions respond directly to changes in SO4 input concentration, and lysimeter data indicate the importance of these processes for buffering short-term changes in SO4 concentration in LFH percolate. Desorption may be the primary direct response of upland soil to decreasing SO4 inputs in deposition and may substantially extend the period of net SO4 export in catchments that have large adsorbed SO4 pools such as PC1. However, the adsorbed pool may be sustained by continuous net release from mineralization, and should also be considered in budget calculations. Mineralization was shown to be responsive to drying and re-wetting events and temperature, although results varied among different materials. Sulphate release from mineral soil did not appear to be influenced by changing moisture, temperature or deposition chemistry in laboratory experiments, although adsorption/desorption reactions may have largely masked small changes in SO4 release <i>via</i> mineralization. The magnitude of organic S storage in mineral soil indicates that this pool could be an important source of export over the long-term. While it is unknown why (or if) mineralization is a net source of SO4 to drainage streams, changes in climate and/or deposition could potentially influence SO4 release from organic compounds. Soil moisture and temperature are important controls on microbial processes in soil, and changes in climate that bring about changes in soil moisture or temperature conditions could affect decomposition and mineralization processes. Similarly, historically high inputs of S and N in deposition may have brought about slow shifts in litter quality (<i>i. e. </i> decreased C:N, C:S) which could also potentially influence decomposition and mineralization rates. In order to predict the future response of surface water chemistry to changes in SO4 (and N) deposition, it is important to consider not only the magnitude of S pools in soil, but also the potential for SO4 cycling between pools. Likewise, models that predict changes in stream SO4 by adsorption isotherm data alone will underestimate the importance of desorption unless the potential for continual replenishment of the adsorbed pool through the relatively slower process of mineralization is also considered. In general, predictions of recovery from S deposition can only be made from a complete understanding of S pools, transformations, and the effects of climate, which are superimposed upon the long-term trend in deposition.

Previous work demonstrates conflicting evidence regarding the influence of snowmelt timing on forest net ecosystem exchange (NEE). Based on 15years of eddy covariance measurements in Colorado, years with earlier snowmelt exhibited less net carbon uptake during the snow ablation period, which is a period of high potential for productivity. Earlier snowmelt aligned with colder periods of the seasonal air temperature cycle relative to later snowmelt. We found that the colder ablation-period air temperatures during these early snowmelt years lead to reduced rates of daily NEE. Hence, earlier snowmelt associated with climate warming, counterintuitively, leads to colder atmospheric temperatures during the snow ablation period and concomitantly reduced rates of net carbon uptake. Using a multilinear-regression (R-2=0.79, P<0.001) relating snow ablation period mean air temperature and peak snow water equivalent (SWE) to ablation-period NEE, we predict that earlier snowmelt and decreased SWE may cause a 45% reduction in midcentury ablation-period net carbon uptake.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Master of Agribusiness / Department of Agricultural Economics / Allen M. Featherstone / The landscape of the United States seed industry has changed substantially over the last 100 years. In the mid-1930s, there were 115 active seed corn companies marketing seed in the United States. By the 1980s, there were 303 hybrid seed corn companies and in 2016 there were 140 active hybrid seed corn companies in the United States. As the seed industry continues to evolve, so will the logistics and methods of which seed is sold to farm customers. The purpose of this thesis is to analyze and determine if a seed business expansion provides a positive net present value and rate of return for the management based on the capital costs of the investment and estimated income opportunities. Based on historical information of the existing business and the new market territory opportunities, a ten year projected cash flow was estimated to provide a basis for the net present value and internal rate of return analysis. Sensitivity analysis was applied to different variables in the cash flow model to identify variables of risk and the impact on the projected cash flow and net present value analysis. The projected cash flow model and net present value analysis provides management a basis for the decision to expand their existing business. The conclusion of the net present value and internal rate of return analysis was that the expansion of the seed business was profitable under most sensitivity scenarios. Recommendations were made for additional research that could be performed to maximize and diversify the business’s product offerings and net income.

Our thesis deals with a communication on social network Facebook. The primary goal was a probe of chat communication on this new platform. In the introduction part, we tried to summarize existing knowledges of czech linguist scientists concerning with electronic communication; subsequently, we focused on a definition of internet communication, it's classification, positive and negative aspects and description of particular types of "computer communication". Simultaneously, we were exploring so called social network, predominantly Facebook, it's basic functions, possible ways of communication mediated by this medium and particularities of chat in comparison with a synchronous webchat. Research part analyze chat communication on Facebook from wider standpoint of communication situation and from point of view of text structure. It was an effort to compare chat and immediate spoken dialog, to classify and to interpret basic type sof chat communication and to describe it's specific features. Conclusion of the paper is dedicated to irony on Facebook - classification of it's particular types and following of it's making and signalizing were based on analysis. We tried to point out especially the particularities of chat communication and it's connection with a spoken dialog.

Master of Agribusiness / Department of Agricultural Economics / Allen M. Featherstone / The oat processing industry is a competitive industry and maintaining a cost advantage is important for the industry supply chain. General Mills continuously looks to maintain a competitive advantage in the oat supply chain because it is important for strategic short and long term planning. The purpose of this thesis is to analyze supply chain scenarios to determine where future investments should be made. The analysis looks at an existing location, a refurbished location and a Greenfield site. The analysis projects income statements and net cash flows to determine the conclusions using Net Present Value. The question answered is "Should the company continue to invest in the existing supply chain or should it look to different alternatives in the form of a refurbished or Greenfield plant site for production of oat flour?" The analysis found important relationships between the variables that can influence net cash flow and ultimately NPV. However, given the information from this analysis, a determination was made that the existing facility is still the best investment. Future analysis should be used and the company should plan to analyze this issue again in a five to ten year time frame to maintain its competitive advantage.

Distributed systems are shared by a large number of users that generate task-based workloads. The sharing of hardware and software by multiple workloads mandates the need for security mechanisms that protect the artifacts of individual tasks. Additionally, these systems must meet user-based performance expectations, a factor that must be addressed during the security service selection process. Current performance-based security service selection methodologies use flat GSPN models that suffer from exponential evaluation complexity as the model size increases. Due to this limitation, these methodologies cannot evaluate models representing the scale of current distributed systems. To address the evaluation complexity problem the hierarchical methodology presented in this report was designed to avoid the system size limitations of the current flat GSPN model-based methodologies. The methodology relies only on general performance models capable of modeling platform-independent systems designs. The refactoring methodology uses a divide-and-conquer approach to evaluate the entire system model. Using model-refactoring techniques the input model is modified into a hierarchy of subsystem models using abstraction to isolate performance measurement to component level. This technique further increases the effectiveness of the performance evaluation by avoiding the duplicate evaluation of identical components. Therefore increasing the number of alternate security service components results in a linear complexity growth of the entire system model. Thus, the limiting factor of the hierarchical methodology is the size of the largest component rather than the previous system size limitation. The experimental results show that the hierarchical model-based methodology is able to scale beyond system model sizes that can be evaluated using current flat GSPN-based performance evaluation methodologies. This scalability improvement implies that the hierarchical technique can evaluate models containing up to 50 individual components using the current GSPN tools. Thus the contribution of this hierarchical technique will continue to improve with subsequent advancements in GSPN model evaluation techniques.

Thesis advisor: Karen Arnold / Traditional aged college students currently enrolled at institutions of higher education have never known a time without technology and through social media, can interact and engage with one another regardless of physical space. Technology provides fast, easy, efficient, and constant means of communication, and students use social media while simultaneously engaging in campus activities. The purpose of this study was to examine the relationship between student use of socially interactive technology (SIT) and engagement and involvement in the undergraduate experience. Social media included in this study refers to cell phones, text messaging, Instant Messaging, email, and social networking sites (SNS). Borrowing items from the Net Generation Survey and the National Study for Student Engagement (NSSE) an instrument was created to analyze time dedicated to technology, use by demographics, technology as a predictor student of engagement, as well as qualitative data. Results from 154 participants show that students use technology for approximately eight hours per day, male students in the sample are overrepresented at the lowest levels of social media use, and social media types are correlated with one another. Following a factor analysis on the independent technology items and the dependent engagement items, regression analyses were employed to explore this relationship. Qualitative data illustrate that technology use can distract students from academic activities, and limits interpersonal communication. Conversely, it is beneficial in that students are constantly updated on class discussions, campus events, and with peers and family. Given these findings, because of students' frequent use of technology while engaged or involved in campus activities, concerns regarding the quality of these experiences are discussed. Additionally, redefining the traditional meaning of campus involvement is appropriate. / Thesis (PhD) — Boston College, 2011. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Leadership and Higher Education.

Este trabalho descreve a utilização da Rede de Petri como ferramenta de análise e desenvolvimento da automação de uma Micro-usina de cogeração piloto de 130 kW. O projeto foi implantado no centro laboratorial de qualidade de energia da Escola Politécnica da Universidade de São Paulo. O objetivo principal desta Micro-usina é estudar as principais variáveis inerentes à qualidade de energia e funcionalidades destes tipos de sistemas automatizados. A utilização da Rede de Petri (RP) permitiu prever a alcançabilidade, vivacidade, segurança e reversibilidade do programa aplicativo desenvolvido e implantado em um controlador programável (CLP) de última geração. Através de uma rede de comunicação de protocolo aberto foi possível a troca de informações entre o CLP e os módulos de controle.dos geradores (G1 e G2). Entradas e saídas digitais foram utilizadas para monitorar e comandar as chaves de transferência automática (Close e Open Transition) e também os disjuntores motorizados. As operações realizadas são sinalizadas no painel local de controle e transferência (PCT) assim como, via rede Ethernet, na interface remota de supervisão e controle (SCADA).No estudo de caso da Micro-usina de cogeração foram identificadas um total de 24 posições (Position) distintas, considerando as quatro fontes de geração atuais e os dois centros de consumo de energia. Através de uma IHM local ou um supervisório remoto (SCADA) é possível a mudança entre as posições (topologia) permitindo realizar as principais manobras de paralelismo momentâneo e transitório dos grupos geradores com a concessionária. No programa aplicativo do CLP foi implementado o intertravamento de segurança para todos os equipamentos comandados, assumindo sempre o desconhecimento, por parte do operador, dos critérios e seqüências de segurança exigidos para execução das transições entre topologias (pior caso). / This study is about the usage of the Petri Net as an analysis and development tool of the automation of a pilot micro plant of 130 kW. The project was carried out in the energy quality laboratory center at the Escola Politécnica de São Paulo. Its main goal was to study the most important variables related to the quality of energy and the functionalities of the automatized system types. By using the Petri Net, it was possible to foresee the attainment, vivacity, reliability and reversibility of the software, developed and installed in a state-of-the-art programmable logical controller (PLC). Through an open protocol communication network, information was exchanged between the PLC and the generators (G1 and G2) control modules. Digital inputs and outputs were used to monitor and switch the automatic transfer keys (Close and Open Transition) and the motor switches. The procedures done were shown on a local panel of control and transfer, as well as on the Ethernet, at a remote supervision and control interface (SCADA). In this case study, 24 different positions were identified, taking into account the four sources of generation at the moment and the two centers of energy consumption. Through local IHM or remote supervision (SCADA), it was possible to switch positions (topology) and perform the main maneuvres of momentary and transitional parallelism from generator groups to concessionary. As to the PLC application program, a security block was set to all commanded devices, assuming that the operator was unaware of the criteria and security steps needed to proceed with transitions in topology (worst case).

In the last couple of decades, there has been an increased awareness of the effects that electricity generation has on the environment through the emission of greenhouse gases and the depletion of natural resources. This realisation, coupled with an increased drive towards ensuring the sustainability of the energy supply system, has lead many, including the United Kingdom government to investigate the options for moving away from traditional fossil fuel-burning generation methods towards “lowcarbon” generators, such as renewables and nuclear power. Specifically, wind power, the more mature systems (with the exception of hydro power) of the available renewable energy supply, and nuclear power, a technology seen as producing large amounts of electricity with very few associated greenhouse emissions, have been promoted but also pitted against each other by analysts and policy makers. This work aims to provide a balanced analysis of wind power and nuclear power with respect to their effects on the natural environment. As such, modeling has been undertaken of a Generation III+ nuclear reactor, an onshore wind farm located in southern Scotland and an offshore wind farm near the Thames estuary while environmental indicators have been created to permit the comparative assessment of these three electricity generation technologies, in a U.K. context. These indicators thus facilitate an assessment of the energy requirements, the associated greenhouse gas emissions, the natural resource requirements, as well as the displaced carbon dioxide emissions from operation of each power plant. A parametric analysis has also been conducted to show the range of likely variations in each indicator’s values. The results of this research show that all three technologies demonstrate similar performance with respect to their energetic and environmental impacts. More specifically, the wind farms demonstrate better energy gain ratios than the nuclear power plant when they are credited for not depleting non-renewable fuel sources. The wind farms also are shown to pay back their energy investments faster than the nuclear power plant. On the other hand, the nuclear power plant is found to produce slightly lower greenhouse gas emissions than either onshore or offshore wind farms. With respect to the assessment of natural resource depletion, it is estimated that both wind farms need more land per unit of electricity produced than the nuclear power plant, but all three power plants permanently sequester similar amounts of water. The wind farms and the nuclear power plant are found to have similar performance with respect to their material requirements, while the calculation of the avoided emissions factors for all technologies are of similar orders of magnitude. All results are shown to be highly sensitive to the assumptions made about the prospective lifecycles, and as such caution should be exercised when drawing conclusions about any comparative advantages. Nethertheless both technologies are clearly shown to have lower environmental impacts than traditional electricity generation technologies.