• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 624
  • 452
  • 136
  • 93
  • 46
  • 24
  • 14
  • 12
  • 6
  • 6
  • 5
  • 3
  • 2
  • 2
  • 2
  • Tagged with
  • 1793
  • 751
  • 476
  • 259
  • 211
  • 183
  • 164
  • 151
  • 144
  • 143
  • 142
  • 119
  • 118
  • 113
  • 112
  • 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.
241

Impacts of gold mine waste on the water quality in the West Rand region & the associated risk to Anglogold Ashanti

Sakoane, Malebabo 14 February 2007 (has links)
Student Number : 9612464Y - MSc dissertation - School of Mining Engineering - Faculty of Engineering and the Built Environment / This study was conducted at the West Rand Region, part of South African-based AngloGold operations. The study assesses the impacts of gold mining on the water quality and the change in landuse resulting from the mining activities on the West Rand Region. This was achieved by collecting historical data relating to the tailings dams and both surface and groundwater qualities between 1998 and 2003. The landuse information was gathered from the topographic map of Carltonville and remotely sensed data in the form of aerial photographs, landsat data and ASTER images. The data was analysed in a GIS ILWIS. The sizes of the tailings dams have not changed significantly during the study period. The size of the plantation also shows a decreasing trend due to pollution from the tailings dams. The area surrounding the Anglo Gold mining operations is sparsely-vegetated due to both poor soils and the impacts of mining activities. The surface water quality is poor and this water has negative impacts on the environment following accidental discharges and has potential negative impacts from seepage through the unlined dams. The quality of the groundwater is generally good with the exceptions of BH 18, MBH 8, MBH 5 and MBH 3 whose pollution arises from North mine tailings dams and North boundary dam. MBH 5 shows an improvement in water quality over time. The potential generation of AMD from the tailings dams is inhibited by the neutral pH of the tailings. In order to improve the environment in the West Rand Region and to prevent further pollution, planting of indigenous trees to make up for shrinking plantation and lining of the dams be undertaken. Stricter maintenance and monitoring of both the sewage plants and the dams be implemented to avoid accidental discharges of poor quality water into the environment. A study to accurately quantify the groundwater pollution arising from both the tailings dams and other surface water bodies should be undertaken.
242

Economic Contributions of Forest-Based Industries in the South

Dahal, Ram Prasad 17 May 2014 (has links)
The South is one of the leading timber producing regions in the world. Monitoring economic contribution of the forest products industry in the South over time is thus crucial in addressing critical economic issues and in understanding important industry trends. This study reports the economic impacts for the four forest-based industry (forestry, lumber and wood products, paper and allied products, and wood furniture) for 13 southern states, individually as well as regionally, and compares to 2001, the last comprehensive study of the industry in the South. During the study period, the industry’s employment decreased by 33.35% and earnings in real terms decreased by 18.44%. However, value of shipments and manufacturing valueded for the industry in real terms increased by 59.21% and 68.22% respectively. Therefore, despite of disproportionate impacts of the current recession and decline in housing starts, the industry still is an important component of the South’s economy.
243

Assessing Tornado watches for Accuracy, Impacts on Daily Activities, and Potential Economic Impacts

Gutter, Barrett Frank 11 August 2017 (has links)
During 2007 – 2015, a total of 2,359 tornado watches were issued by the Storm Prediction Center and 10,840 tornadoes were confirmed. The objective of the first part of this study analyzed the accuracy of tornado watches for the nine-year period of 2007 – 2015. In addition to accuracy, fatalities, lead times, valid watch times, and areas were calculated for each tornado watch. 58.80% of the tornado watches had at least one tornado inside the tornado watch and 27.43% had at least one tornado outside the tornado watch. Of the 10,840 tornadoes, 56.70% were inside a tornado watch, 9.69% were outside a tornado watch, and 33.62% occurred when there was no tornado watch in effect. The average valid time for a tornado watch was 6 hours and 50 minutes and the average lead time for a tornado was 2 hours and 8 minutes. The second objective utilized a survey to determine participant knowledge and better understand “watch severity response”. A majority of the survey respondents accurately identified the difference between a tornado watch and a tornado warning. Most of the respondents described their weather knowledge as ‘moderately knowledgeable,’ ‘very knowledgeable,’ or ‘slightly knowledgeable.’ TV meteorologists, the NWS, and weather apps are the most common sources for daily weather information and information regarding a tornado watch. 81.63% of the respondents correctly identified if they were under a tornado watch during 2016. As the severity of the watch or the length of the activity increased, the likelihood of the respondent continuing the activity decreased. 38.87%, 54.76%, and 79.18% of the respondents ‘probably would not’ or ‘definitely would not’ continue an activity, lasting any duration, during a severe thunderstorm watch, a tornado watch, or a PDS tornado watch, respectively. The final objective attempts to categorize simple economic response to various watch severity types. The percent of respondents who would not continue an activity, based on the severity of the watch, was applied to a variety of watches that occurred during 2016. The economic loss associated with a watch ranged from $498,332.15 – $107,126,919.19.
244

Resource Analysis of Small-diameter Tree Above-ground Biomass in Mississippi

Tiruveedhula, Mohan P 30 April 2011 (has links) (PDF)
Small diameter trees refer to the trees with diameter at breast height (DBH) ranging from 5 to 11 inches. This research focuses on the resource analysis and spatial distribution of small-diameter tree (SDT) volume in Mississippi by a set of grouping variables including DBH class, species, stand size, forest cover type, ownership, and county groups. Regression and spatial interpolation techniques were used to predict the SDT volume for pine, hardwood, and mixed forest covers. Regression analysis resulted in a low regression coefficient (R2) without inventory data for all the forest cover types. The mean SDT volume to the total volume was greatest for pine (0.6), followed by mixed (0.4), and hardwood (0.3) forest cover. Non-spatial estimates indicated the total volume within respective groups. The spatial and non-spatial estimates of SDT resources can guide forest management personnel to effectively focus their management efforts.
245

Quantifying the effects of boat wakes on intertidal oyster reefs in a shallow estuary

Campbell, Donna 01 January 2015 (has links)
There have long been concerns about the negative impacts of recreational boating activity in the Indian River Lagoon system (IRL), especially in Mosquito Lagoon (ML), the northernmost part of the IRL. My research is focused on the impacts of boat wakes on intertidal reefs formed by the eastern oyster, Crassostrea virginica. There has been a 24% loss of oyster habitat in ML since 1943, where natural oyster reefs have been replaced by dead oyster reefs which do not serve the same ecological function. While there is anecdotal and correlative evidence that this loss is a result of boat wakes, no studies to date have confirmed dead reefs can be a direct result of boat wakes. Therefore, I addressed the following questions: (1) What wake heights are generated by a range of boat types, and (2) What amount of oyster movement and erosion occurs as a result of these boat wakes? A series of boat pass experiments addressed the first question; these results were utilized in experiments at Florida Institute of Technology's wave tank to observe sediment erosion and oyster movement as a result of specific wake heights. Model selection was used for both the field and wave tank experiments to determine which variables contributed most to explaining the wake heights, erosion, and oyster movement that occurred. Wake heights ranging from 0.05 cm to 20.80 cm were documented contacting the oyster reefs from the boat passes, with a mean of 2.95 cm. Boat type was less important than speed or distance when determining wake height. My wave tank results document that wake heights as small as 2 cm contacting oysters are capable of moving individual and clusters of oysters. Minimum distances for boats to travel in order to maintain wakes smaller than 2 cm at reefs are suggested for management purposes based on regression equations. This could minimize the amount of movement that occurs when oysters are subjected to boat wakes. The results of this study can help resource managers implement boating policies in Mosquito Lagoon, and contribute greatly to conserving this important ecosystem engineer.
246

Freight Truck Traffic Associated with the Port of Oakland: A Case Study of Roadway Impacts

Hinkamp, James 01 December 2011 (has links) (PDF)
The Port of Oakland (“Port”) is the 5th largest container seaport by volume in the U.S. and the largest in Northern California. Maritime shipping activity at the Port exceeds 2 million import and export twenty-foot equivalent unit (TEU) containers annually. Containers may be full or empty, but nonetheless typically require hinterland shipment and intermodal transfer between maritime and land-based freight distribution systems. The freight trucking mode (“drayage”) handles approximately 80% of all TEU throughput at the Port, thus constituting the majority of landside Port traffic. The Port is also situated adjacent to dense urban development thereby exacting certain external impacts. Drayage impacts on regional roadway infrastructure proximate to the Port are explored, to expand knowledge of freight network conditions and relevant policies addressing the topic in the San Francisco Bay Area. Statistical regression analysis and elasticity results estimate a certain level of impact on nearby freight corridors of I-80, I-680, and I-880. Drayage traffic has continued to increase since 2000, as a function of increasing TEU throughput occurring at the Port. Policies to address stable freight flow and infrastructure maintenance are ongoing, although additional studies are also recommended to ascertain comprehensive network impacts.
247

Simulation des effets de détérioration de surfaces rigides pour un rendu réaliste

Paquette, Éric January 2002 (has links)
Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.
248

Methods for Engineers to Understand, Predict, and Influence the Social Impacts of Engineered Products

Stevenson, Phillip Douglas 07 December 2022 (has links)
Engineered products can impact the day-to-day life of their users and other stakeholders. These impacts are often referred to as the product's social impacts. Products have been known to impact the people who use them, design them, manufacture them, distribute them, and the communities where they exist. Currently, there are few methods that can help an engineer identify, quantify, predict, or improve a product's social impact. Some companies and organizations have tried to identify their impacts and, for example, set goals for achieving more sustainable business practices. However, engineers, in large part, do not have methods that can help improve the sustainability and social impacts of their products. Without new methods to help engineers make better product decisions, products will continue to have unanticipated negative impacts and will likely not reach their true social impact potential. Engineers working in the field of Engineering for Global Development (EGD) are especially in need of methods that can help improve the social impacts of their products. One of the purposes of creating products in EGD is to help solve problems that lead to improved quality of life for people and communities in developing countries. The research in this dissertation presents new methods developed to help engineers understand, predict, and improve the social impact of their products. Chapter 2 introduces the Product Impact Metric, a simple metric engineers can use to quantify their products impact on improving the quality of life of impoverished individuals in developing countries. Chapter 3 introduces a method that engineers can use to create product-specific social impact metrics and models. These models are used to predict the social impacts of an expanded US-Mexico border wall on immigrants, border patrol officers, and local communities. Chapter 4 shows a method that allows engineers to create social impact models for individuals within a population. Using data available through online databanks and census reports, the author predicts the social impact of a new semi-automated cassava peeler on farmers in the Brazilian Amazon. In Chapter 5, the author presents a method for engineers to optimize a product according to its social impact on multiple stakeholders. Inspired by existing literature on multi-stakeholder decision making, eight different optimization problem formulations are presented and demonstrated in an example with the cassava peeler. Chapter 6 presents the author's experience in co-designing a semi-automated cassava with the Itacoatiara Rural Farming Cooperative. The peeler was designed and built by the author and is used as the example in Chapters 4 and 5. Finally, Chapter 7 shows the conclusions the author has in completing this research. Comments are made as to the difficulties encountered in this research (specifically data quality and validation), and the author makes suggestions of possible future work.
249

The Effects of Attention-Deficit/Hyperactivity Disorder on the Association between Repetitive Head Impacts and Post-Season Concussion Symptoms

Lynch, James D. 04 November 2020 (has links)
No description available.
250

Distribution and direct impacts of marine debris on the Mississippi commercial shrimping

Rodolfich, Alyssa 06 August 2021 (has links)
Commercial shrimpers in the Mississippi Sound frequently encounter marine debris in their nets, which results in loss of time, loss of catch, and added repair costs. Yet, the spatial and temporal distribution of this marine debris and the economic impact faced by shrimpers in the Mississippi Sound is not well known. This study measured the quantity and economic impact of marine debris by surveying 20 commercial shrimpers. Participants logged marine debris encounters, fishing data, and damage to fishing gear during the July 2020 through December 2020 shrimping season. It was found that shrimpers encounter marine debris 19% of all tows, and the majority of all marine debris encountered by shrimpers (79%) was derelict crab traps. Additionally, 10% of all tows reported direct impacts.

Page generated in 0.0397 seconds