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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

A cumulative effects approach to wetland mitigation

Nielsen, Jesse Lee 30 March 2010
Wetlands are among the most ecologically productive lands in the world, but every year they continue to be lost due to increasing pressures from agriculture, industrial development, urbanization and the lack of effective mitigation to deal with such pressures. Despite environmental assessment processes, policies, and regulations to ensure the mitigation of affected wetlands, wetlands continue to experience a loss in areal extent, but more importantly, a functional net-loss. This is attributed, in large part, to the lack of incorporating cumulative effects principles into project-based wetland impact assessment and mitigation. The majority of activities that affect wetlands are either assessed at the screening level, where cumulative effects are rarely considered, or are deemed insignificant and do not trigger any formal environmental assessment process. As a result, the mitigation of cumulative effects on wetlands is often insufficient or completely lacking in development planning and decision-making. Part of the challenge is that there currently does not exist methodological guidance as to how to identify wetland cumulative effects and corresponding mitigation needs early in the project design process. This research presents a methodological framework and guidance for the integration of cumulative effects in decision-making for project-based, wetland impact mitigation. The framework provides a means for the early indication, assessment, and mitigation of the potential cumulative effects of project developments on the wetland environment, with the objective of ensuring a no-net-loss of wetland functions.
52

Characterization of the movement of spray drift past a shelterbelt

Peterson, Jonathan Christian 29 April 2008
Pesticide use is an important component of the agricultural industry. Pesticides are typically applied to crops as a droplet spray, and these droplets are susceptible to off-target movement due to wind, which is called spray drift. It has recently been recognized that shelterbelts may protect vulnerable downwind areas from spray drift. There is a need to characterize the movement of spray drift past a shelterbelt to better understand the extent of this protection and the variables which affect it. The variables investigated in this research may be classified as meteorological conditions, spray application settings, and shelterbelt properties.<p>This research investigated the movement of spray drift past a 5 m tall carragana/chokecherry shelterbelt. Spray was applied using a conventional sprayer that travelled on a path that was upwind and parallel to the shelterbelt. A tracer substance was mixed into the spray solution, and the deposition and airborne concentration of drift was measured using a variety of collectors placed at perpendicular distances up- and downwind of a shelterbelt. The mass of drift deposit on the collectors was determined using spectrofluoremetry and standard solutions.<p>When the spray swath was a distance of 3H (where H is the height of the shelterbelt) upwind of the shelterbelt, it was found that the ground deposition of drift at a distance of 0.5H downwind of the shelterbelt was reduced by approximately 74%, compared to the drift deposit at 0.5H upwind. The reduction over the same downwind distances was 29% in the open field setting. The airborne drift cloud was attenuated by the shelterbelt and the airborne concentration of drift exiting the shelterbelt was reduced by approximately 85% of the entering drift. The airborne drift concentration profile indicated that there was a greater proportion of drift travelling over the top of the shelterbelt rather than passing through the shelterbelt, with the peak concentration occurring at approximately 1.2H.<p>Qualitative and multiple linear regression analyses were used to determine the significance of a number of meteorological and controlled variables on the deposition of drift. It was found that the mass of drift deposited downwind of the shelterbelt increased with a higher wind speed, higher temperature, and lower relative humidity. For the range of meteorological conditions sampled, the effect of wind direction and atmospheric stability were found to be insignificant. Finer spray qualities and higher shelterbelt optical porosity produced greater airborne drift and deposition downwind of the shelterbelt. With increasing upwind sprayer distance, the mass of drift deposited within the shelterbelt decreased.
53

Environmental effects assessment of oil and gas development on a grassland ecosystem

Nasen, Lawrence Christopher 15 December 2009
The northern Great Plains of Saskatchewan is one of the most significantly modified landscapes in Canada. While the majority of anthropogenic disturbance to Saskatchewans grasslands is the result of agricultural practices, oil and gas activity are of increasing concern to grassland conservation efforts. Although such developments require formal regulatory approval (Environmental Impact Assessment), follow-up and monitoring of the effects of oil and gas development on grasslands is not common practice. In the absence of empirical based follow-up and monitoring, the actual environmental effects of petroleum and natural gas (PNG) development on grassland ecology and the spatial extent of development are largely unknown.<p> This thesis examines the spatial and temporal extent of PNG development and its effects on grassland ecology within a PFRA (Prairie Farm Rehabilitation Administration) pasture in southwest Saskatchewan. The extent of the changes to infrastructure and the actual impacts from development within the study area were documented from 1955 to 2006. The actual impacts of oil and gas activity on grassland ecology were determined by analyzing ground cover characteristics, soil properties, and community composition at lease sites and compared to reference pasture sites. Associated with construction practices, lease sites had low herbaceous, Lycopodiaceae, litter, organic horizon (Ah) thickness, and soil compaction values. Lease sites were also found to have low desirable species diversity, range health values, and greater undesirable species presence. Impacts from development were amplified at active, highly productive lease sites. The impacts associated with PNG development were also found to persist for more than 50 years, and extend 20m 25m beyond the physical footprint of infrastructure. This research will contribute to monitoring and mitigation measures for oil and gas development within Saskatchewan and Canadian grasslands.
54

The Impact of Biofuel and Greenhouse Gas Policies on Land Management, Agricultural Production, and Environmental Quality

Baker, Justin Scott 2011 May 1900 (has links)
This dissertation explores the combined effects of biofuel mandates and terrestrial greenhouse gas GHG mitigation incentives on land use, management intensity, commodity markets, welfare, and the full costs of GHG abatement through conceptual and empirical modeling. First, a simple conceptual model of land allocation and management is used to illustrate how bioenergy policies and GHG mitigation incentives could influence market prices, shift the land supply between alternative uses, alter management intensity, and boost equilibrium commodity prices. Later a major empirical modeling section uses the U.S. Forest and Agricultural Sector Optimization Model with Greenhouse Gases (FASOMGHG) to simulate land use and production responses to various biofuel and climate policy scenarios. Simulations are performed to assess the effects of imposing biofuel mandates in the U.S. consistent with the Renewable Fuels Standard of the Energy Independence and Security Act of 2007 (RFS2). Simulations are run for several climate mitigation policy scenarios (with varying GHG (CO2) prices and eligibility restrictions for GHG offset activities) with and without conservation land recultivation. Important simulation outputs include time trajectories for land use, GHG emissions and mitigation, commodity prices, production, net exports, sectoral economic welfare, and shifts in management practices and intensity. Direct and indirect consequences of RFS2 and carbon policy are highlighted, including regional production shifts that can influence water consumption and nutrient use in regions already plagued by water scarcity and quality concerns. Results suggest that the potential magnitude of climate mitigation on commodity markets and exports is substantially higher than under biofuel expansion in isolation, raising concerns of international leakage and stimulating the “Food vs. Carbon” debate. Finally, a reduced-form dynamic emissions trading model of the U.S. economy is developed using simulation output from FASOMGHG and the National Energy Modeling System to test the effect of biofuel mandate expansion and domestic offset eligibility restrictions on total economy-wide GHG abatement costs. Findings are that while the RFS2 raises the marginal costs of offsets, full abatement costs depend on a number of policy factors. GHG payment incentives for forest management and non-CO2 agricultural offsets can increase full abatement costs by more than 20%.
55

Documenting & Using Cognitive Complexity Mitigation Strategies (CCMS) to Improve the Efficiency of Cross-Context User Transfers

Bhagat, Rahul January 2011 (has links)
Cognitive complexity mitigation strategies are methods and approaches utilized by users to reduce the apparent complexity of problems thus making them easier to solve. These strategies often effective because they mitigate the limitations of human working memory and attention resources. Such cognitive complexity mitigation strategies are used throughout the design, development and operational processes of complex systems. Thus, a better understanding of these strategies, and methods that leverage them, can help improve the efficiency of such processes. Additionally, changes in the use of these strategies across various environments can identify cognitive differences in operating and developing across these contexts. This knowledge can help improve the effectiveness of cross-context user transfers by suggesting change management processes that incorporate the degree of cognitive difference across contexts. In order to document cognitive complexity mitigation strategies and the change in their usage, two application domains are studied. Firstly, cognitive complexity mitigation strategies used by designers during the engineering design process are found through an ethnographic immersion with a participating engineering firm, followed by an analysis of the designer's logbooks and validation interviews with the designers. Results include identification of five strategies used by the designers to mitigate design complexity. These strategies include Blackbox Modeling, Whitebox Modeling, Decomposition, Visualization and Prioritized Lists. The five complexity mitigation strategies are probed further across a larger sample of engineering designers and the usage frequency of these strategies is assessed across commonly performed engineering design activities which include the Selection, Configuration and Parametric activities. The results indicate the preferred use of certain strategies based on the engineering activity being performed. Such preferential usage of complexity mitigation strategies is also assessed with regards to Original and Redesign projects types. However, there is no indication of biased strategy usage across these two project characterizations. These results are an example of a usage-frequency based difference analysis; such analyses help identify the strategies that experience increased or reduced usage when transferring across activities. In contrast to the first application domain, which captures changes in how often strategies are used across contexts, the second application domain is a method of assessing differences based on how a specific strategy is used differently across contexts. This alternative method is developed through a project that aims to optimize the transfer of air traffic controllers across different airspace sectors. The method uses a previously researched complexity mitigation strategy, knows as a structure based abstraction, to develop a difference analysis tool called the Sector Abstraction Binder. This tool is used to perform cognitive difference analyses between air traffic control sectors by leveraging characteristic variations in how structure based abstractions are applied across different sectors. This Sector Abstraction Binder is applied to two high-level airspace sectors to demonstrate the utility of such a method.
56

Characterization of the movement of spray drift past a shelterbelt

Peterson, Jonathan Christian 29 April 2008 (has links)
Pesticide use is an important component of the agricultural industry. Pesticides are typically applied to crops as a droplet spray, and these droplets are susceptible to off-target movement due to wind, which is called spray drift. It has recently been recognized that shelterbelts may protect vulnerable downwind areas from spray drift. There is a need to characterize the movement of spray drift past a shelterbelt to better understand the extent of this protection and the variables which affect it. The variables investigated in this research may be classified as meteorological conditions, spray application settings, and shelterbelt properties.<p>This research investigated the movement of spray drift past a 5 m tall carragana/chokecherry shelterbelt. Spray was applied using a conventional sprayer that travelled on a path that was upwind and parallel to the shelterbelt. A tracer substance was mixed into the spray solution, and the deposition and airborne concentration of drift was measured using a variety of collectors placed at perpendicular distances up- and downwind of a shelterbelt. The mass of drift deposit on the collectors was determined using spectrofluoremetry and standard solutions.<p>When the spray swath was a distance of 3H (where H is the height of the shelterbelt) upwind of the shelterbelt, it was found that the ground deposition of drift at a distance of 0.5H downwind of the shelterbelt was reduced by approximately 74%, compared to the drift deposit at 0.5H upwind. The reduction over the same downwind distances was 29% in the open field setting. The airborne drift cloud was attenuated by the shelterbelt and the airborne concentration of drift exiting the shelterbelt was reduced by approximately 85% of the entering drift. The airborne drift concentration profile indicated that there was a greater proportion of drift travelling over the top of the shelterbelt rather than passing through the shelterbelt, with the peak concentration occurring at approximately 1.2H.<p>Qualitative and multiple linear regression analyses were used to determine the significance of a number of meteorological and controlled variables on the deposition of drift. It was found that the mass of drift deposited downwind of the shelterbelt increased with a higher wind speed, higher temperature, and lower relative humidity. For the range of meteorological conditions sampled, the effect of wind direction and atmospheric stability were found to be insignificant. Finer spray qualities and higher shelterbelt optical porosity produced greater airborne drift and deposition downwind of the shelterbelt. With increasing upwind sprayer distance, the mass of drift deposited within the shelterbelt decreased.
57

Environmental effects assessment of oil and gas development on a grassland ecosystem

Nasen, Lawrence Christopher 15 December 2009 (has links)
The northern Great Plains of Saskatchewan is one of the most significantly modified landscapes in Canada. While the majority of anthropogenic disturbance to Saskatchewans grasslands is the result of agricultural practices, oil and gas activity are of increasing concern to grassland conservation efforts. Although such developments require formal regulatory approval (Environmental Impact Assessment), follow-up and monitoring of the effects of oil and gas development on grasslands is not common practice. In the absence of empirical based follow-up and monitoring, the actual environmental effects of petroleum and natural gas (PNG) development on grassland ecology and the spatial extent of development are largely unknown.<p> This thesis examines the spatial and temporal extent of PNG development and its effects on grassland ecology within a PFRA (Prairie Farm Rehabilitation Administration) pasture in southwest Saskatchewan. The extent of the changes to infrastructure and the actual impacts from development within the study area were documented from 1955 to 2006. The actual impacts of oil and gas activity on grassland ecology were determined by analyzing ground cover characteristics, soil properties, and community composition at lease sites and compared to reference pasture sites. Associated with construction practices, lease sites had low herbaceous, Lycopodiaceae, litter, organic horizon (Ah) thickness, and soil compaction values. Lease sites were also found to have low desirable species diversity, range health values, and greater undesirable species presence. Impacts from development were amplified at active, highly productive lease sites. The impacts associated with PNG development were also found to persist for more than 50 years, and extend 20m 25m beyond the physical footprint of infrastructure. This research will contribute to monitoring and mitigation measures for oil and gas development within Saskatchewan and Canadian grasslands.
58

A cumulative effects approach to wetland mitigation

Nielsen, Jesse Lee 30 March 2010 (has links)
Wetlands are among the most ecologically productive lands in the world, but every year they continue to be lost due to increasing pressures from agriculture, industrial development, urbanization and the lack of effective mitigation to deal with such pressures. Despite environmental assessment processes, policies, and regulations to ensure the mitigation of affected wetlands, wetlands continue to experience a loss in areal extent, but more importantly, a functional net-loss. This is attributed, in large part, to the lack of incorporating cumulative effects principles into project-based wetland impact assessment and mitigation. The majority of activities that affect wetlands are either assessed at the screening level, where cumulative effects are rarely considered, or are deemed insignificant and do not trigger any formal environmental assessment process. As a result, the mitigation of cumulative effects on wetlands is often insufficient or completely lacking in development planning and decision-making. Part of the challenge is that there currently does not exist methodological guidance as to how to identify wetland cumulative effects and corresponding mitigation needs early in the project design process. This research presents a methodological framework and guidance for the integration of cumulative effects in decision-making for project-based, wetland impact mitigation. The framework provides a means for the early indication, assessment, and mitigation of the potential cumulative effects of project developments on the wetland environment, with the objective of ensuring a no-net-loss of wetland functions.
59

To Act or Not to Act : Muncipial Authority over Green House Gas Mitigation

Kikerpuu, Tiina January 2010 (has links)
The purpose of this study is twofold. Firstly, it is a feasibility study intended to contribute tofurther research on the municipal authority to mitigate green house gas emissions. This will bedone by studying the municipal authority on green house gas mitigation measures in threeSwedish municipalities. To fulfil the purpose the following questions are set to be answered.What is the municipal authority over green house gas mitigation measures in these threemunicipalities?- What is the formal ability of municipalities in Sweden to act on GHG mitigation?- What measures do these three municipalities use to mitigate GHG emissions?- How do the municipalities consider their climate authority?The study focused on measures within three sectors; traffic and transport; energy, andinformation and out-reaches. Transport and energy make up the main sources of GHGemissions in the municipalities, and information was a common measure.4 categories of authority were developed; Legal authority, Economic authority, Climatecompetence and Collaborations, this to get a picture of what influenced climate authority. Theidea for this came from previous research that involved aspects similar to the categories. Theresult showed that municipal climate authority is quite relative, the categories are relevant, butpolitical will and ambitions on tackling climate change are decisive. In the transport sector themunicipal authority was restricted due to the authority of other actors. The authority in theenergy sector was limited because national legislation had precedence.The municipal climate authority is considered strong within its own organisation, themunicipal role as wide and involving many responsibilities. The role was described as widerthan the municipal authority. Most of the climate measures are directed towards themunicipality’s own organisation, the premises of the municipality and the services it provides.Outside the municipal organisation and services, but within its geographic unit, in the specificmeasures developed in this study, the climate authority was weaker and mainly exercisedthrough collaborations. The municipalities are not using their climate authority in full. Byimplementing measures like climate considerations in public procurement, their authoritycould be improved.
60

Magneto-rheological tuned liquid column dampers (MR-TLCDs) for vibration mitigation experiment of structures.

Luo, Yuan-Tzuo 02 September 2010 (has links)
With the progress of civilization, buildings and residential constructions become taller and taller. Seismic design for buildings to resist earthquakes also attracts more attentions. The common vibration energy dissipation devices such as TMD, TLD, etc. have been popular but they have limitations such as requirement for large space to install and difficult to be installed after the building is finished. TLCD as an alternative may improve these defects. The new developed MR-TLCD system has the advantages of real-time control and is reversible. Based on the theorem of TLCD, the control equation of MR-TLCD considered the fluid viscosity. The parameters of external control magnetic force and properties of MR-fluid inside the tube needed in damping ratio calculation were measured in the experiment, where a model free vibration experiment was performed. A MR-TLCD system of which the damping ratio was designed in harmony with optimal damping ratio. The comparison was also made for the damping effect of traditional TLCD, MR-TLCD(uncontrolled), MR-TLCD(passive controlled) under dynamic loadings of various frequencies and amplitudes. The experimental results showed that MR-TLCD is more suitable in large amplitude external force. TLCD plays the best vibration mitigation effect when the external force is resonant to the structure, but MR-TLCD is better in other frequency range. It is encouraging that the application of MR-TLCD can have larger scope than TLCD. Keyword: vibration mitigation, experiment, TLCD, MR-TLCD

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