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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.
571

Hydrologic and water quality performance of bioretention cells during plant senescence

Dhami, Jessica 11 March 2022 (has links)
Bioretention cells (also known as rain gardens) are a Low Impact Development (LID) method for sustainable stormwater management. An increasingly popular form of urban stormwater infrastructure, bioretention cells use an engineered, vegetated-soil-system to both reduce quantity and enhance quality of stormwater. The ability of bioretention systems to remove common pollutants from urban stormwater runoff, and reduce runoff volume through evapotranspiration, in a temperature climate during plant senescence were assessed in this full scale field-based study. Stormwater run-off simulations were conducted for 5-, 10-, and 25-year return period storm events at a field site in Victoria, British Columbia, Canada. Tests were run on both, a vegetated cell planted with a mix of Betula nigra, Betula nana, and Salix lutea, and a control cell with turfgrass. Influent and effluent field parameters were recorded for pH and dissolved oxygen (DO), in addition to lab analyses conducted to quantify COD, TN, TON, TP, ortho-phosphate, and TSS removal from the stormwater. Water quality and hydrologic performance were results were compared between the vegetated and control cell using a Wilcoxon Signed Rank Test. In addition, hydrologic results were correlated with daily Evapotranspiration (ET) and meteorological station data using Spearman’s Rho Correlation. The vegetated cells were more effective (p value < 0.05) at retention of water volume, DO, COD, and orthophosphate, when compared to the control. Strong correlations (p value < 0.05) were found between the retention of water volume, and each of ET, maximum temperature, average temperature, minimum temperature, and average wind, for only the vegetated cells. / Graduate
572

Tracking Neurocognitive Performance Following Concussion in High School Athletes

Covassin, Tracey, Elbin, R. J., Nakayama, Yusuke 01 December 2010 (has links)
Objective: To extend previous research designs and examine cognitive performance up to 30 days postconcussion. Method: A prospective cohort design was used to examine 2000 athletes from 8 mid-Michigan area high schools to compare baseline neurocognitive performance with postconcussion neurocognitive performance. All concussed athletes were readministered the Immediate Post Assessment and Cognitive Test (ImPACT) at 2, 7, 14, 21, and 30 days postconcussion. Results: A total of 72 high school athletes (aged 15.8 ± 1.34 years) sustained a concussion. A significant within-subjects effect for reaction time (F = 10.01; P= 0.000), verbal memory (F = 3.05; P = 0.012), motor processing speed (F= 18.51; P = 0.000), and total symptoms following an injury (F= 16.45; P= 0.000) was found. Concussed athletes demonstrated a significant decrease in reaction time up to 14 days postconcussion (P = 0.001) compared with baseline reaction time. Reaction time returned to baseline levels at 21 days postinjury (P = 0.25). At 7 days postinjury, impairments in verbal memory (P= 0.003) and motor processing speed (P= 0.000) were documented and returned to baseline levels by 14 days postinjury. Concussed athletes self-reported significantly more symptoms at 2 days postconcussion (P = 0.000) and exhibited a resolution of symptoms by 7 days postinjury (P = 0.06). Conclusion: High school athletes could take up to 21 days to return to baseline levels for reaction time. These data support current recommendations for the conservative management of concussion in the high school athlete.
573

Longitudinal Effects of Impact Fees and Special Assessments on the Level of Capital Spending, Taxes, and Long-Term Debt in American Cities

Jung, Changhoon, Roh, Chul Y., Kang, Younguck 01 September 2009 (has links)
This article examines whether the use of impact fees and special assessments affect the level of capital spending and two major own source revenues of local capital spending (taxes and long-term debt) by analyzing a panel of 695 American cities with populations over 20,000 during the time period of 1980-2000. Since impact fees and special assessments are heavily used in a growing community and because it covers less than half the costs of new development, the findings demonstrate that the private financing of public infrastructure (impact fees and special assessments) increases the level of local capital spending. It also leads to an increase in the level of long-term debt use. Although it provides partial tax relief, it is not a strong substitute for taxes. Thus, impact fees and special assessments are not a substitute for local capital spending. It is rather a supplemental revenue source to fund local capital infrastructure.
574

Using Simulation to Quantify the Impacts of Changes In Construction Work

Cor, Haldun 07 October 1998 (has links)
Work changes are alterations to the original scope of a contract. Work changes are inevitable in a typical construction project due to the complex nature of the construction industry. It is not possible to foresee these changes at the pre-construction or bidding stages. The changes may affect originally planned means and methods and, thus, may impact the quantity and type of the originally allocated resources such as time, labor, and equipment. In other words, work changes may involve time, money or both. Proper quantification of the impacts solely introduced by changes is therefore vital to all parties and to the success of a project. Failing to quantify impacts due to changes may have adverse consequences that may sometimes result in litigation. Several techniques are currently employed by the construction industry to quantify the impacts of changes. There are also a few simulation case studies used for productivity-related impact analysis. Certain simulation techniques and capabilities, such as modeling flexibility, involvement of historical data, and capability to compare alternatives enable simulation to be a promising tool for quantifying impacts due to changes. Despite the fact that simulation is becoming popular in the construction industry, up to this point in time, there are no established guidelines for the use of simulation in quantifying impacts due to work changes. Simulation still needs exploration with further research and applications that are specific to the problems of the construction industry. There is a solid need to explore the opportunities for employing simulation in quantifying impacts. The objective of this work is to explore the use of simulation in quantifying work change impacts. The study consists of a literature review on the relevant topics. It also analyzes and quantifies a case study in depth. The lessons learned from the case study showcase the procedure and potential of the methodology. The output of the research is valuable for practitioners who wish to employ simulation in quantifying impacts due to work changes. / Master of Science
575

An evaluation of environmental impact assessment procedure in the Lesotho Highlands Water Project : Phase 1

Nkopane, Setenane January 1997 (has links)
Environmental Impact Assessment is a procedure that ensures that the environmental consequences of development proposals are understood and adequately considered in the planning process. This important project planning requirement is often inadequately addressed in many developing countries - especially with regard to dam projects. Lesotho is a small developing country in Southern Africa which is currently engaged in a multi-phased dam project - the Lesotho Highlands Water Project (LHWP) - in order to utilize its most abundant natural resource - water. Planning for the LHWP incurred some irregularities, particularly with regard to environmental implications. The purpose of this study is to evaluate the environmental impact assessment procedures of the LHWP, Phase lA. This includes review of the environmental studies that were carried out and the findings of these studies; assessment of the familiarity of the Lesotho Highlands Development Authority (LHDA) staff with EIA procedures; and examination of the extent to which the communities in the project area were consulted regarding this project. The study is based on two surveys: firstly, within the Environment Division of the Lesotho Highlands Development Authority to assess the familiarity of staff members with proper EIA procedures. In this survey 28 self-administered questionnaires were issued, and 23 were collected. Secondly, structured interviews and unstructured group discussions were carried out in 14 villages to examine the extent to which the communities affected by the LHWP had been involved in the environmental impact assessments of Phase lA; and whether the impacts they experienced and the subsequent. Mitigation efforts had been considered comprehensively by the project proponents. Eighty interviews were conducted in six of the 14 villages selected in the study, in the remaining villages data was collected through group discussions. The groups consisted of 10 - 12 members (usually prominent persons) from the community. The study revealed that EIA for Phase 1 A of the LHWP was not carried out according to recognized standards. Environmental studies that were undertaken were done too late in the EIA process, and did riot facilitate the project planning. The study also found that the majority of LHDA staff members are not familiar with the details of the EIA process, and did not participate in Phase lA project planning. The communities affected by the LHWP were not given the opportunity to raise their concerns about the project. This is manifested by the magnitude and type of impacts which they have incurred because of the LHWP. Members of these communities therefore regard their livelihoods as being worse than before the project. It is thus recommended that LHDA should revise and significantly improve its project planning approaches - especially for the subsequent phases of the project. It is imperative· to incorporate public participation in the EIAs of these phases. Formulation of guideline sand legislation - in Lesotho as a whole - will ensure enforcement and compliance with sound environmental assessment procedures, and improve on LHDA's manpower capabilities with regard to EIA and environmental management. This in turn will enhance an environmentally sustainable development.
576

Assessing the effectiveness of Environmental Impact Assessment as a safeguard to biodiversity in the Cape Floristic Region of South Africa

Nortje, Griffin January 2017 (has links)
Environmental Impact Assessment (EIA) is subject to challenges that undermine this process as an effective safeguard to biodiversity. Internationally, effective EIA is hindered by the following issues: a low priority assigned to the consideration of biodiversity and a limited capacity to carry out assessments; a lack of formalised procedures and inconsistent methodologies to address biodiversity within the EIA framework; and a lack of formal requirements for post-project monitoring of biodiversity aspects. Traditionally effectiveness studies in this regard have focused on evaluating the procedural aspects of EIA, and have focused less on the substantive outcomes of the post-authorisation phase of a proposed project. While South Africa has a considerable body of literature pertaining to the procedural aspects of EIA, there remain two substantial gaps in the literature. Firstly, there is an evident absence of effectiveness studies in South Africa that focus primarily on biodiversity-specific procedure. Secondly, almost no research has been conducted in South Africa which investigates the outcomes of mitigation measures, mandatory monitoring, reporting and compliance with biodiversity aspects of EIA. This research therefore aims to fill these gaps by investigating the quality of information generated in five EIAs in the Western Cape. It also examines the implementation success of mitigation measures aimed at managing unavoidable impacts in the post-authorisation phase of these projects. This research has adopted a case study methodological approach. Five EIAs were selected from a sample of 9. In no order of significance, the variables considered most important in the sampling protocol were: the presence of a biodiversity-related specialist report; availability of environmental assessment documentation; overall cases to represent at least two different local jurisdictions; and the uniqueness of adopted biodiversity-related mitigation measures. The primary method used to evaluate the quality of biodiversity-related information is a Key Performance Indicator analysis, whereby the performance of cases is measured against legal and best-practice reporting principles. The substantive outcomes of EIA have been investigated by means of site inspections and interviews with key stakeholders. This research has found that the five cases performed well with complying with best-practice EIA procedure, indicating a 53% full compliance, 29% partial compliance and 18% of best-practice principles were not complied with at all. This research has shown that direct impacts on biodiversity (such as the physical removal of indigenous vegetation) are adequately identified, and indirect impacts (typically those impacting off-site and on ecological processes) are poorly identified in EIA. Therefore, the information required to avoid impacts on biodiversity is available, but this research has found that it is underutilized in this regard. Notably, avoidance of impacts was undermined inadequate site and layout alternatives and poor decision making in terms of the regular authorisation of irreversible impacts on biodiversity. Conversely, only 18% of mitigation measures were fully complied with, 36% were partially complied with, and 45% of mitigation measures were not complied with. These results indicate a poor performance of EIA in the implementation stage of a project lifecycle. This research has concluded this is most likely due to a poor conversion of recommended mitigation measures into conditions of authorisation and a limited capacity of the competent authority to perform compliance monitoring.
577

Towards a model for environmental assessment and management of boreholes in communal areas in Namibia

De Wet, Neil January 1997 (has links)
This was the final statement in a report, prepared for the Namibian Programme to Combat Desertification (NAPCOD), which researched the process, praxis and environmental impacts of borehole provision in communal areas in Namibia (ENGEO, 1997).¹ This dissertation is a response to this concluding statement. It presents a theoretical model which provides a comprehensive yet simple environmental assessment and management framework to inform, guide and manage the provision of boreholes in communal areas in Namibia. The model has been designed to be cost effective, appropriate for its context and 'user-friendly'. Most importantly, the model aims to present a system which would promote principles of sustainability and, consequently, sustainable development in terms of borehole provision in communal areas in Namibia.
578

Environmental evaluation of proposed alternative roads to the Mohale dam

Heydenrych, Reuben January 1993 (has links)
Bibliography: p. 109-111. / This is an academic report submitted in partial fulfilment of the degree Master of Environmental Science. It is written to demonstrate the competence of the writer in undertaking work in the field of Environmental Impact Assessment. The main purpose of the report is the comparative evaluation of two proposed alternative roads, the "Western Access Route" (WAR) and the "Least Cost Alternative Route" (LCAR). Since this is an academic report, it will not be used as a decision-making document and it will not be submitted to the proponent of the alternative roads.
579

NM2002 impact assessment : impact assessment report

Lochner, Paul January 1992 (has links)
Bibliography: p. 94-95. / The purpose of this report is to: * assess the biophysical and socio-economic impacts of closure of De Beers Namaqualand Mines (DBNM) * provide preliminary suggestions for mitigation measures. DBNM anticipate that they will close in approximately 10 years' time. By the year 2002, all diamond deposits which are currently economically viable to mine on a large-scale would have been exploited. Closure is anticipated to have a significant impact on DBNM employees, their households, and towns where the households of employees live. Furthermore, closure is anticipated to have a significant impact on the Namaqualand economy. Therefore, DBNM commissioned the EEU to undertake an assessment of the impacts resulting from mine closure, to ascertain the effects on their employers and their affected households and communities. Through discussions with DBNM the scope for this assessment was established: * Briefly to describe the current biophysical, social and economic environments in Namaqualand and identify different trends in the region. * To assess in detail the socio-economic impacts resulting from the closure of DBNM. In addition, this report considers the impacts on the biophysical environment resulting from the closure of DBNM, because the socio-economic well-being of employees from rural areas of Namaqualand and Transkei is intrinsically linked to changes in the biophysical environment. Lastly, this report also contains preliminary suggestions for mitigating the impacts of closure.
580

Experiments on Drop-impact Splashing, Singular Jets and Coalescence in Emulsions

Tian, Yuansi 06 1900 (has links)
This dissertation describes experiments on drop dynamics. It is split into two main parts: The first investigates the breakup of liquid during the impact of a drop on a pool surface, with focus on the smallest and fastest splashed satellite droplets. The second part studies the much slower coalescence of two minute water droplets in oil inside a micro-channel, with applications to separation of water droplets from crude oil emulsions. First, we study drop-on-liquid impacts in high-speed experiments with extreme time and spatial resolutions using up to 5 million frames-per-second video imaging. This is used to identify and explain two primary mechanisms which produce the smallest and fastest splashed secondary droplets, i.e. ejecta sheets and singular jets. Using a novel 25-m-tall vacuum tube we generate very large impact velocities, to reach regimes in parameter-space never studied before. During the earliest stage of the impact a fast-moving horizontal ejecta sheet emerges from the neck between drop and pool. The breakup of this sheet forms a myriad of micron-size droplets. The ejecta bending is dominated by air resistance, which we investigate under reduced ambient pressures and successfully model based on Bernoulli suction which pulls down the ejecta to hit the pool surface. The ejecta can initially bend up or down depending on the relative viscosities of the drop and pool, bending up if the pool is less viscous. Singular jets are produced by the collapse of drop-impact craters for deep pools, when a dimple forms at the bottom of the crater focusing the energy into a micron-sized region, with jetting velocities over 100 m/s. We use Gerris to study the fine details, obscured in the experiments. In the second part, we study the coalescence of water droplets inside an oil emulsion, developing an empirical relation between the coalescence interaction time tc and the modified shear-rate. This is done by tracking 3-D drop trajectories inside a microchannel, with two perpendicular high-speed cameras. For droplets in crude oil, we implement near-infrared visualization in an innovative device to quantify demulsifier efficiency, using mono-disperse micro-droplets.

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