• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 261
  • 56
  • 47
  • 38
  • 31
  • 21
  • 19
  • 12
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • Tagged with
  • 626
  • 193
  • 95
  • 85
  • 83
  • 77
  • 69
  • 65
  • 55
  • 49
  • 43
  • 42
  • 40
  • 39
  • 37
  • 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.
181

Removal of hydrocarbons from urban stormwater runoff by gravity separation /

Boe, Jennifer Barber, January 1993 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 89-94). Also available via the Internet.
182

Dynamics of the wind field expansion associated with extratropically transitioning tropical cyclones

Evans, Allen Clark, January 2006 (has links)
Thesis (M.S.)--Florida State University, 2006. / Advisor: Robert Hart, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed Sept. 26, 2006). Document formatted into pages; contains xiii, 98 pages. Includes bibliographical references.
183

EFFECTS OF EXPERIMENTAL STORM SURGE AND SEDIMENTATION ON PITCHER PLANTS (SARRACENIA PURPUREA) AND ASSOCIATED ASSEMBLAGES IN A COASTAL PINE SAVANNA

Abbott, Matthew John 01 December 2012 (has links)
Sea-level rise and stronger hurricanes associated with global climate change will likely result in farther reaching storm surges that will greatly affect coastal ecosystems. These surges can transport nutrients, salt water, and sediment to nutrient poor, fresh (i.e. low salinity) pine savannas. Purple pitcher plants (Sarracenia purpurea ) are pine savanna inhabitants that could potentially be at a disadvantage because their pitcher morphology and stout structure may leave them prone to collecting saline water and sediment after a surge. In this study, separate field and greenhouse experiments were conducted to test the effects of storm surge water salinity and sediment type on pine savanna soil characteristics, plant community structure, and pitcher plant vitality. In the field, plots (containing &ge genet of S. purpurea ) were experimentally storm surged with fresh or saline water crossed with one of four sediment types (local, foreign, fertilized foreign, or no sediment). Saline water inundation resulted in significantly higher pitcher plant mortality than the fresh water treatment combinations. However, a subsequent prescribed fire and regional drought affected the study area during the next growing season, resulting in the decline of all the pitcher plants to zero or near zero percent cover. Soil data revealed that the combination of salt water and fertilized sediment resulted in short-term increases in soil-water conductivity and nitrogen availability. Interestingly, there were no significant differences in plant community structure between treatments, suggesting that the community as a whole is not as vulnerable as the pitcher plants to the cumulative effects of multiple stressors (i.e. storm surge, fire, and drought) operating in this system. Indicator species analysis revealed that some species were significant indicators of certain treatments; thus suggesting that pitcher plants are not the only species affected by storm surge. In the greenhouse, pitcher plants received various forms of sediment (i.e. no sediment, sterile sediment, or one of two levels of fertilized sediment) within their pitchers to determine if nutrient uptake is either inhibited or enhanced. Plants that received sterile sediment had higher carbon:nitrogen ratios and higher leaf mass per unit area. Eutrophic sediment deposition resulted in a temporary decrease in relative growth rate as well as changes in pitcher morphology. There were no differences in chlorophyll content and photosynthetic rates between treatments. Both the field and greenhouse experiments indicate that global climate change may indirectly contribute to the further decline of southeastern purple pitcher plant populations in the future.
184

Využití víceokruhového dopravního problému při optimalizaci dopravních tras

Rumreichová, Lenka January 2014 (has links)
Rumreichová, L. The use of multiple-tours transport problem in the optimization of transport routes. Master thesis. Brno: Mendel University in Brno. 2013. The master thesis deals with the possibilities of using methods of the operations research in the creation of distribution routes. This thesis is based on the analysis of the original solutions to distribution lines. The aim is to suggest a new distribution solution using appropriate optimization methods. The thesis is a comparison of the original and optimized solution with suggestions for possible improvements. Proposal for the new solution is performed using Mayer`s methods and available software.
185

Stereo 3D-SMS microscopy of large sample volume

Mittelstädt, Haugen 14 December 2018 (has links)
No description available.
186

Stormwaterbesoedeling in die Lourensrivier-opvanggebied

Habets, Maurice January 1993 (has links)
Thesis (Master Diploma (Civil engineering)--Cape Technikon, Cape Town,1993 / Stormwater pollution is a major problem in many of the areas where it is present. Due to the changing nature in terms of quality and quantity of stormwater, which has its origin in many different places, it is difficult to control and identify the source of pollution. Some of the pollutants present in stormwater run-off include oxygen-demanding substances, suspended solids, trace metals, toxic organic compounds (eg. chlorinated hydrocarbons), nutrients, refuse, plastics and pathogenic bacteria and viruses. This thesis identifies and discusses the problems in the Lourensriver catchment area, and produce practical solutions to decrease the pollution. The report consists of four sections. Part I : Part 2 : Part 3 : Part 4 : Evaluation of the existing area and identification of the problem. Literamre study. Control of Stormwater ie. storing, treatment and disposal. Presencation of steps to be followed to rectify the problem. If the findings and recommendations are followed, it should make a positive contribution to the wellbeing of the catchment area. The findings of this report could also be applied to areas with similar problems. The following recommendations are made for the Lourens River: " Monitor and strict implementation of the Wateract (1936). " In the Lower zone, pollution can be diluted and flushed out by ways of the closure of Melkschloot. " Design of any new development must take place in such a manner so as the stormwater discharge after development will be of the same quality and quantity as before construction. " Creation of permeable surfaces in established areas. " Delay of rainwater flow out of all areas. " Construction of additional sedimentation and detention dams for the storing and treatment of stormWater. " Awareness programmes to inform the public and industry. " Implementation of preventative measurements. " Establishment of controlling body's to ensure co-ordination betvieen various institutions and local government. " Monitor of run-off from industrial and agricultural terrain and identifying of unlawful practices. Strict anti-littering and dumping actions. Placing of waste storage bins in residential and industrial areas. Permits for the usage of poisons and the monitor there off. Encouragement of cleaning up actions and groups. Encouragement and increase of street cleaning operations. Construction of effective catchment basins to remove sol ids before it ends up in the stormwater pipes. Regular cleaning of catchment basins. Regular flushing of stormwater pipes. Construction of marshlands. Construction of reedbeds.
187

Seasonal predictability of North American coastal extratropical storm activity during the cold months

Pingree-Shippee, Katherine 01 May 2018 (has links)
Extratropical cyclones (ETCs) are major features of the weather in the mid- and high-latitudes and are often associated with hazardous conditions such as heavy precipitation, high winds, blizzard conditions, and flooding. Additionally, severe coastal damage and major local impacts, including inundation and erosion, can result from high waves and storm surge due to cyclone interaction with the ocean. Consequently, ETCs can have serious detrimental socio-economic impacts. The west and east coasts of North America are strongly influenced by ETC storm activity. These coastal regions are also host to many land-based, coastal, and maritime socio-economic sectors, all of which can experience strong adverse impacts from extratropical storm activity. Society would therefore benefit if variations in ETC storm activity could be predicted skilfully for the upcoming season. Skilful prediction would enable affected sectors to better anticipate, prepare for, manage, and respond to variations in storm activity and the associated risks. The overall objective of this dissertation is to determine the seasonal predictability of North American coastal extratropical storm activity during the cold months (3-month rolling seasons – OND, NDJ, DJF, JFM – during which storm activity is most frequent and intense) using Environment and Climate Change Canada’s Canadian Seasonal to Interannual Prediction System (CanSIPS). This dissertation describes research focused on three themes: 1.) reanalysis representation of North American coastal storm activity, 2.) potential predictability of storm activity and climate signal-storm activity relationships for the North American coastal regions, and 3.) seasonal prediction of storm activity in CanSIPS. Research Theme 1 evaluates six global reanalysis datasets to determine which best reproduces observed storm activity in the North American coastal regions, annually and seasonally, during the 1979-2010 time period using single-station surface pressure-based proxies; ERA-Interim is found to perform best overall. Research Theme 2, using ERA-Interim, investigates the potential predictability of extratropical storm activity (represented by mean sea level pressure [MSLP], absolute pressure tendency, and 10-m wind speed) during the 1979-2015 time period using analysis of variance. The detected potential predictability provides observation-based evidence showing that it may be possible to predict storm activity on the seasonal timescale. Additionally, using composite analysis, the El Niño-Southern Oscillation, Pacific Decadal Oscillation, and North Atlantic Oscillation are identified as possible sources of predictability in the North American coastal regions. Research Theme 2 provides a basis upon which seasonal forecasting of extratropical storm activity can be developed. Research Theme 3 investigates the seasonal prediction of North American coastal storm activity using the CanSIPS multi-model ensemble mean hindcasts (1981-2010). Quantitative deterministic, categorical deterministic, and categorical probabilistic forecasts are constructed using the three equiprobable category framework (below-, near-, and above-normal conditions) and the parametric Gaussian method for determining probabilities. These forecasts are then evaluated against ERA-Interim using the correlation skill score, percent correct score, and Brier skill score to determine forecast skill. Baseline forecast skill is found for the seasonal forecasts of all three storm activity proxies, with MSLP forecasts found to be most skilful and 10-m wind speed forecasts the least skilful. Skilful seasonal forecasting of North American coastal extratropical storm activity is, therefore, possible in CanSIPS. / Graduate
188

Design of Logan City's Stormwater Conveyance System

Beck, Kade Jacob 01 April 2017 (has links)
Logan City is located in northern Utah's Cache County. The average annual rainfall for Cache Valley is between 15 and 20 inches (PRISM 2016). Several times a year, the incomplete storm water system causes flooding, which risks industrial and agricultural lands. The current system collects storm water between 200 West and 1000 West, and discharges the water directly along 1000 West. Cutler Reservoir, Swift Slough, and the Lower Bear River in Cache Valley do not comply with water quality regulations. The Clean Water Act of 1972 mandates that all municipal separate storm sewer systems (MS4) comply with EPA regulations, expressed as Total Maximum Daily Loads (TMDLs). Logan City's untreated storm water might contribute to the pollution in these water bodies. The pollution threatens surface water, groundwater, and wildlife in the area. Logan City plans to implement a new wastewater treatment process. However, the new treatment process is not designed to use the existing polishing ponds. Consequently, Logan City hopes to use these polishing ponds to treat storm water. The implementation of this design improves storm water management. 10th West Engineers (10WE) had three goals. First, design a system to transport water form the discharge locations to the holding pond. Second, design a system that provides irrigation users access to water during a storm. Third, comply with the goals of the client: design a gravity-fed system, minimize effect on wetlands, and produce an economical design.
189

Process-based modelling of storm impacts on gravel coasts

McCall, Robert Timothy January 2015 (has links)
Gravel beaches and barriers occur on many high-latitude, wave-dominated coasts across the world. Due to their natural ability to dissipate large amounts of wave energy, gravel coasts are widely regarded as an effective and sustainable form of coastal defence. However, during extreme events waves may overtop, overwash, and even lower, the crest of the gravel beach, flooding the hinterland. In the evaluation of the safety of gravel coasts against flooding, coastal managers currently rely on models that have been shown in previous studies to be inaccurate. The research in this thesis attempts to improve the current predictive capacity of gravel beach storm response by developing a new process-based model to simulate storm impacts on gravel coasts. The numerical model developed in this thesis, called XBeach-G, is a morphodynamic, depth-averaged, cross-shore profile model, based on the XBeach model for sandy coasts (Roelvink et al., 2009). The model simulates the morphological response of gravel beaches and barriers to storms by solving: (1) intra-wave flow and surface elevation variations using a non-hydrostatic extension of the non-linear shallow water equations; (2) groundwater processes, including infiltration and exfiltration, using a Darcy-Forchheimer-type model; and (3) bed load transport of gravel using a modification of the Van Rijn (2007a) bed load transport equation to include flow acceleration effects, which are shown to be significant on coarse-grained beaches. The model is extensively validated for hydrodynamics, groundwater dynamics and morphodynamics using detailed data collected in physical model experiments, as well as data collected in the field on four natural gravel beaches in the UK and one in France. Validation results show that the model has high quantitative skill in simulating observed hydrodynamics on gravel beaches across a wide range of forcing conditions, in particular with regard to wave transformation, wave run-up and wave overtopping. Spatial and temporal variations in groundwater head are shown to be well represented in the model through comparison to data recorded in a physical model experiment. Validation of the morphodynamic component of XBeach-G shows that the model has high model skill (median BSS 0.75) in simulating storm impacts on five gravel beaches during ten storm events, with observed morphodynamic response ranging from berm-building to barrier rollover. The model is used to investigate hydrodynamic processes on gravel beaches during storms, where it is found that incident-band variance is elemental in the generation of wave run-up on gravel beaches. Furthermore, simulations of wave run-up during high-energy wave events show a distinct disparity between run-up predicted by empirical relations based on the Iribarren parameter and wave steepness, and run-up predicted by XBeach-G, where predictions by the empirical relations substantially underestimate observed wave run-up. Groundwater processes are shown, by means of sensitivity simulations, to strongly affect the morphodynamic response of gravel beaches and barriers to storms. The research in this thesis supports the hypothesis that infiltration in the swash is a key driver for the berm-building response of gravel beaches and helps to reduce erosion of the upper beach during storms. Through model simulations on a schematic gravel barrier it is shown that groundwater processes effectively increases the capacity of gravel barriers to withstand storms with 1-3 m higher surge levels than if groundwater processes did not occur. Reducing the width of a barrier leads to a lowering of this capacity, thereby reducing the resilience of the barrier to extreme storm events. Despite its strong influence on gravel beach morphodynamics, it is found that infiltration plays a relatively small role on wave run-up levels on most natural gravel beaches (median R 2% run-up level reduction of 8%). Application of the model in validation simulations and sensitivity simulations in this thesis, as well as in storm hindcast simulations discussed by McCall et al. (2013) shows the value of using the process-based XBeach-G model in coastal flooding analysis over the use of empirical tools. While no model can be considered entirely accurate, application of XBeach-G in all hindcast overwash simulations has lead to reasonable estimates of overtopping discharge and of morphological change, which is a significant improvement over the frequently substantial errors of the empirical tool designed for this purpose.
190

Spatial–temporal Modelling for Estimating Impacts of Storm Surge and Sea Level Rise on Coastal Communities: The Case of Isle Madame in Cape Breton, Nova Scotia, Canada

Pakdel, Sahar January 2011 (has links)
More frequent and harsh storms coupled with sea level rise are affecting Canada’s sensitive coastlines. This research studies Isle Madame in Cape Breton, Nova Scotia which has been designated by Natural Resource Canada as a sea level rise vulnerable coastal community in Canada. The research models the spatial and temporal impacts of sea level rise from storm surge by focusing on identifying vulnerable areas in the community via geographical information systems (GIS) using ArcGIS, as well as modeling dynamic coastal damage via system dynamics using STELLA. The research evaluates the impacts in terms of the environmental, social, cultural, economic pillars that profile the coastal community for a series of modelled Storm Scenarios. This research synthesizes information from a variety of sources including the coastal ecology and natural resources, as well as human society and socioeconomic indicators included in the four mentioned pillars. The objective of the research is to determine vulnerable areas on Isle Madame susceptible to storm damage, and consequently, to improve local community knowledge and preparedness to more frequent harsh storms. This research therefore presents a dynamic model for the evaluation of storm impacts in Isle Madame designed with the goal to help the community ultimately to plan and implement a strategy to adapt to pending environmental change.

Page generated in 0.0671 seconds