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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.
341

Multiple Scales of Beach Morphodynamic Processes: Measurements and Modelling

Cheng, Jun 20 November 2015 (has links)
Multiple scales of beach morphodynamic processes ranging from those of wave-breaking induced turbulence, individual wave, storm, seasonal, to inter-annual are examined in this dissertation based on both laboratory and field data. These processes were simulated using process-based numerical models and data-driven models. At a microscale, separating turbulence from orbital motion under breaking waves in the surf zone is essential to understanding wave-energy dissipation. Velocity data under monochromatic and random waves in the large-scale sediment transport facility (LSTF) were analyzed. Moving averaging provides a simple method for extracting turbulence from velocity measurements under random breaking waves collected at a reasonably high frequency. Various moving averaging time intervals were examined. An optimum moving averaging interval of approximately 30° to 42° phase angle (relative to peak wave period) allows a reasonable extraction of turbulence. An adaptive moving averaging with variable averaging time at wave crest and trough are proposed to improve the effect of turbulence extraction. At a mesoscale, hydrodynamic conditions associated with onshore migration of a sandbar and the subsequent equilibrium state of a stable bar were examined in the LSTF. Wave and near bottom velocity across the surf zone were measured during the onshore sandbar migration. The near-bottom velocity skewness indicates that before the sandbar reached equilibrium, the velocity was skewed offshore in the nearshore region, and skewed onshore seaward of the bar. The velocity skewness pattern reversed when the beach profile reached equilibrium and the sandbar became stable. The peak onshore directed acceleration was greater than the peak offshore directed acceleration throughout the surf zone during the periods of both onshore migrating and stable sandbar. The macroscale portion of the study examines the beach processes, particularly the morphodynamics of nearshore bar, at storm and seasonal scales. The bar height and bar position were extracted from bimonthly surveyed beach-profiles spaced at 300 m along the 22-km long Sand Key barrier island, West-Central Florida from October 2010 to August 2015. Seasonal beach cycle in the study area is illustrated by onshore sandbar migration during the summer and offshore sandbar migration during the winter, while subaerial beach remains rather stable. Alongshore variations of onshore and offshore sandbar migration were observed over storm events. The water depth over the pre-storm sandbar crest, or the bar crest elevation, is a major factor controlling the onshore or offshore sandbar movement. The offshore moving sandbar tends to have a shallower pre-storm bar crest, while the onshore moving sandbar tends to have a deeper pre-storm bar crest. A dynamic equilibrium bar height of 0.5 m for the study area was identified. The sandbar tends to evolve toward this equilibrium height during the seasonal cycle. The energetic conditions associated with Tropical Storm Debby caused a deviation from the above dynamic equilibrium conditions. The sandbar at most of the profile locations became higher than the pre-storm bar height regardless of the initial height of being greater or less than 0.5 m. After the storm, the higher and shallower bar experienced substantial erosion, the eroded sand was deposited in the trough landward. This resulted in a lower sandbar height, returning to the dynamic equilibrium height of 0.5 m. The Unibest-TC model (Walstra et al., 2012) is able to capture the measured trend of bar migration. The Modelling results suggest that offshore bar migration is dominated by suspended sediment transport. While onshore bar migration is driven mainly by bedload transport. At megascale, a data-driven model was developed to predict beach-profile evolution at multiple-annual scale. Empirical Orthogonal Function analysis was conducted on a time-series beach profile (R61) to identify temporal and spatial trends. Trends in the temporal EOF are modeled using a simple curve fitting. In this case, logarithmic and linear trends were identified. After the trend in temporal EOF values are identified, the curve fitting can be calibrated with 14-month data. The calibrated temporal EOF curve yielded accurate reproduction of profiles. The close examination of multiple scales of beach processes provides a comprehensive understanding of nearshore morphodynamics.
342

Potential Impacts of Accelerated Sea-Level Rise and Hurricane-Induced Storm Surge in Western Pasco County, Florida

Harris, Kittiya 29 June 2017 (has links)
Sea levels have risen approximately 20 cm since the beginning of the 20th century and more than 3 cm in the past 20 years, suggesting that global sea level rise is accelerating. As sea levels continue to rise and storms become more intense, coastal property and populations become more susceptible to damage. Florida is especially vulnerable to hurricane-induced storm surge (HSS) and the onset of accelerated sea-level rise (ASLR) due to its extensive coastline and high population density along the coast. The main purpose of this research is to assess the potential economic impacts of ASLR and HSS for two of western Pasco County’s municipalities, Port Richey and New Port Richey. A Geographic Information System is used to determine the spatial extent at a high-resolution of coastal inundation, the economic loss based on property value and road expenditure due to this inundation, and its impact on critical infrastructure. The results from this study showed coastal flooding generated by 0.5m SLR amounted to 48.8% land loss and $217,108,692 of property loss. Monetary losses from inundated properties shifted dramatically from 1.0m to 1.5m SLR, from $295 million to $417 million, suggesting that the tipping point could only be a half-meter SLR. Based on the 2.0m SLR results, most of major highway US-19 was completely flooded, property tax losses amounted to approximately $7.1 million, and road expenditure was approximately $158 million. Data provided in this study can be useful for coastal management and planning in Port Richey and New Port Richey.
343

Ecological implications for sustainable stormwater systems in the tallgrass prairie region

Culbertson, Trisha L. January 1900 (has links)
Master of Science / Department of Biological & Agricultural Engineering / Stacy L. Hutchinson / Urban stormwater is one of the leading causes of water quality impairment and stream channel degradation in the United States. In an effort to address the negative effects of stormwater runoff on receiving aquatic systems, Best Management Practices for stormwater, including ecologically-designed stormwater systems, are becoming more common across the urban landscape. Throughout eastern Kansas and the rest of the Midwestern United States, prairie grasses are beginning to receive attention for their potential to enhance infiltration within these systems. However, the function of vegetated stormwater systems and the influence of factors such as vegetation age on infiltration and system performance are not well understood because monitoring data for these systems is limited. When performance data is collected, it often pertains only to the hydraulic and water quality aspects of the system but neglects any assessment of the integrity of the ecosystem functions on which the system's performance is dependent. The objective of this study was to address the need for an assessment tool that considers the ecological integrity, or health, of ecologically-designed stormwater systems, as well as to fill the gap in the literature regarding the function of ecologically-designed stormwater systems in the tallgrass prairie region. Since many of the eco-based stormwater practices in the region rely upon the establishment of native prairie grasses to enhance infiltration on the site, the specific focus of this study was to gain a better understanding of infiltration processes in ecologically-designed systems and the extent of our ability to regain these processes through prairie restoration in previously disturbed urban sites. To address these objectives, two stormwater systems at different stages of vegetative maturity were examined. In general, ecosystem health scores were higher for the more mature system and could be used to guide future management decisions at both sites. Results from the hydraulic analysis indicate the function of the system may improve over the course of the growing season, but statistical relationships between system age and infiltration rate could not be established.
344

Urban stormwater injection via dry wells in Tucson, Arizona, and its effect on ground-water quality

Olson, Kevin Laverne, 1954-, Olson, Kevin Laverne, 1954- January 1987 (has links)
My deepest respect and appreciation are extended to Dr. L. Gray Wilson for providing the opportunity to conduct this research, for his advice and assistance during the course of the research, and for his review of and suggestions for improving this manuscript. I would also like to thank Michael Osborn for his assistance. This research was funded by the City of Tucson. The assistance and direction provided by Mt. Bruce Johnson and Mt. Joe Babcock at Tucson Water are gratefully acknowledged. My thanks are also extended to Dr. Daniel D. Evans, Dr. L.G. Wilson, and Dr. Stanley N. Davis for serving on my thesis committee. Bruce Smith's assistance is gratefully acknowledged. Bruce spent two long days with 110-degree temperatures In a parking lot describing the lithology of sediment samples collected during the drilling phase of this research. He also determined the moisture content and particle size distribution on samples collected from the borehole. The assistance of Ralph Marra and Steve Brooks is also gratefully acknowledged. Ralph waded through city and county bureaucracies to determine zoning at each dry-well site. Steve assisted with collecting dry-well settling chamber sediment samples.
345

Betydelsen av död ved för biologisk mångfald. Eninventering av vedlevande skalbaggar påSkillingaryds skjutfält 2016.

Höglind, Sofia January 2017 (has links)
The military area Skillingaryds skjutfält is considered to harbor a great amount of value for saproxylic beetles, despite the fact that no inventory has been made, because of the high amount of dead wood. After the storms Gudrun (2005) and Per (2007) the County Administrative Board of Jönköping decided to leave a large amount of dead wood in the area to promote biodiversity. During the summer of 2016 the area was surveyed with window traps that were emptied three times. 121 species of saproxylic beetles belonging to 41 families were found during this time. Of these species there were three red listed: Uloma culinaris, Pseudanidorus pentatomus and Orchesia minor. Aside from the red listed species one species that indicate high nature values, Necydalis major, was found and four rare species from the genus Hylis sp. which are rare due to intense forestry. In comparison to other studies Skillingaryds skjutfält exhibit a less interesting fauna than expected. The reason for this is believed to be overgrowth, lack of variation and canopy closure that limits sun exposure. The summer of 2016 was quite mediocre in both temperature and sunny days which also may have affected the results. Since there hasn’t been any previous study of the saproxylic fauna in the area it is impossible to say if the windthrow from the big storms has affected the fauna in any direction. But since it is a known fact that storms generate dead wood it can be concluded that the increase of dead wood should have affected the fauna. This study is the start-up of a proposed continual survey and to draw any conclusions, comparison to other similar studies has been made. It should be emphasized that this study does not give the full picture of the saproxylic fauna and that there probably are more species living in the area than presented here.
346

Impacts of storm and flood events on suspended particulate matter dynamics in the Gulf of Lions. Contributions of gliders to a multi-platform approach. / Impacts des évènements de tempête et de crue sur la dynamique des particules en suspension dans le Golfe du Lion. Contributions des gliders dans l'approche multiplateforme

Many, Gael 14 October 2016 (has links)
La dynamique des matières en suspension joue un rôle primordial au sein de la zone côtière en étant le principal vecteur de matière particulaire depuis les sources (rivières) vers les puits (marges continentales, canyons sous-marins, océan profond). Le suivi de cette dynamique, notamment pendant les évènements de crues des fleuves et des tempêtes, est primordial afin d’estimer les budgets sédimentaires des marges continentales, de suivre l’évolution des habitats benthiques et de déterminer le rôle de cette dynamique dans le transport de contaminants. Cette thèse a pour objet l’étude des impacts de tels évènements sur la dynamique des particules en suspension au sein du Golfe du Lion (Méditerranée). Une approche multiplateforme, couplant les différentes plateformes de mesures existantes (campagne en mer, glider, satellite, mouillage, bouée côtière) et basée sur la mesure de la turbidité en terme quantitatif et qualitatif a été adoptée. Les résultats ont permis de décrire 1) la dynamique des néphéloïdes en fonction des forçages (vents, vagues, courants) durant des évènements de crue du Rhône et de tempête marine, 2) la variabilité spatiale et temporelle de l’assemblage particulaire lors de ces mêmes évènements par une caractérisation in situ et 3) de montrer le rôle des plateformes autonomes du type gliders dans le suivi de la dynamique des matières en suspension en zone côtière. / Coastal suspended particulate matter dynamics play a main role in the fate of land-derived material from the source (rivers) to sink (continental margins, submarine canyons, deep sea). The monitoring of this dynamic, especially during flooding and storm conditions, is decisive to understand factors impacting sedimentary budgets of continental margins, health of benthic habitats and spread of contaminants. The aim of this PhD is to study the impacts of such events on the suspended particles dynamics over the shelf of the Gulf of Lions (NW Mediteranean). A multi-platform approach, combining existing observation platforms (survey, glider, satellite, mooring and coastal buoy) and based on the measurement of the turbidity was adopted. Results enabled to describe 1) the impacts of forcings (winds, waves, currents) on the dynamics of nepheloid layers during flooding and storm conditions, 2) the variability of the particle assemblage during such events through an in situ characterization and 3) the role of gliders in the monitoring of suspended particles dynamics within the coastal zone.
347

Simulating organization of convective cloud fields and interactions with the surface

Hoffmann, Alex January 2013 (has links)
The mesoscale organization and structure of convective clouds is thought to be rooted in the thermodynamic properties of the atmosphere and in the turbulent to mesoscale dynamics of the flow. Such structure may contribute to the transition between shallow and deep convection. The thermodynamic state of the boundary layer is forced by the amount of surface fluxes from below. Conversely, landscape patterns and land-cover heterogeneity may equally give rise to focused regions for deep convection triggering, in particular when patch sizes exceed 10 km. Since the convective boundary layer has a mediating function between the surface and deep storm clouds, the connection between surface and upper atmosphere is not straightforward. It is generally believed to involve local erosion of the capping inversion layer, the build-up of a moist energy supply, gradual humidification of the lower-free troposphere that reduces dry air entrainment into burgeoning deeper clouds, and thermal mesoscale circulations that can generate moisture convergence and locally forced ascent. To what extent microscale realistic surface heterogeneity and an interactive surface response matter to shallow and deep convection and its organization remains an open question. In this dissertation, we describe the coupling of a physiology-based vegetation model (HYBRID) and of a sea surface flux algorithm (COARE) to the cloud-resolving Active Tracer High-resolution Atmospheric Model (ATHAM). We investigate the full diurnal cycle of convection based on the example of the Hector storm over Tiwi Islands, notably the well-characterized event on 30th November 2005. The model performs well in terms of timing and cloud dynamics in comparison to a range of available observations. Also, ATHAM-HYBRID seems to do well in terms of flux partitioning. Whilst awaiting more thorough flux validation, we remain confident that the interactive surface response of both HYBRID and COARE is suited for the purpose of simulating convective-scale processes. We find the storm system evolution in 3D simulations to be robust with respect to differences in surface configuration and initialization. Within our 3D sensitivity runs, we could not identify a strong dependence on either realistic surface heterogeneity in the island landscape or on the interactive surface response. We conclude that in our case study at least, atmospheric (turbulent) dynamics likely dominate over surface heterogeneity effects, provided that the bulk magnitude of the surface energy fluxes, and their partitioning into sensible and latent heat (Bowen ratio), remain unaltered. This is consistent with 2D sensitivity studies, where we find model grid-spacing and momentum diffusion, governing the dynamics, to have an important influence on the overall evolution of deep convection. Fine grid-spacing is necessary, as the median width of updraught cores mostly does not exceed 1000 m. We associate this influence with the dry air entrainment rate in the wake of rising parcels, and with how resolution and diffusion act on coherent structures in the flow. In 2D sensitivity studies with differences in realistic heterogeneities of surface properties, we find little evidence for a clear deterministic influence of these properties on the transition between shallow and deep convection, in spite of largely different storm evolutions across the various runs. In these runs, we tentatively ascribe triggering to stochastic features in the flow, without discarding the relevance of convergence lines produced by mesoscale density currents, such as the sea breeze and cold pool storm outflows.
348

Emotionally triggered involuntary violent behaviour not attributed to a mental disorder : conceptual criteria and their reliability

Joubert, Pierre M. January 2015 (has links)
Emotionally triggered involuntary violent behaviour not attributed to a mental disorder: conceptual criteria and their reliability. This study conceptualised emotionally triggered involuntary violent behaviour (ETIVB), developed criteria for the identification of ETIVB, and examined their validity and reliability. South Africa criminal courts allow for a defence called “non-pathological criminal incapacity”. It refers inter alia to extreme emotional arousal triggering involuntary violent behaviour. This is usually called an “emotional storm” or a so-called “psychological blow automatism”. Psychiatrists are often called to give expert testimony in this regard, but there is no conceptual clarity or criteria upon which to base it. This difficulty is compounded by the requirement set by the criminal courts that the behaviour may not be attributed to a mental disorder (in this thesis the terms mental disorder and mental illness are used interchangeably). The first advance in obtaining clarity was afforded by focusing on the behaviour as distinct from 1) legal and jurisprudential considerations as well as 2) whether the behaviour is (not) attributed to mental disorder. The subsequent research questions driving the study were, “what counts as ETIVB?” In particular, what counts respectively as „emotional triggered‟, „involuntary‟, „violent‟, and „behaviour‟. Through conceptual methods suggested in the work of J.L. Austin, draft ETIVB-criteria were developed and then repetitively applied to a set of 28 cases. Twenty seven of these cases involved a charge of murder. The other one had behaved violently, but was not charged. The criteria were refined and their content validity derived by a repetitive to-and-fro process between comparative exploration of the concepts and their empirical application to the set of cases. The criteria were formulated into an instrument by which a psychiatrist can identify ETIVB. In addition provision was made to record whether ETIVB is, or is not, attributed to specific causes including mental disorder, but only as an attribution that follows after ETIVB has been identified. The ETIVB-instrument was subjected to reliability testing among 14 psychiatrists and 10 psychiatrists in training. They applied the ETIVB-criteria to a set of 5 externally validated case summaries. The participants had first been trained in the use of the instrument by considering other example cases. Statistical analyses of inter-rater reliability were performed. The modified kappa agreement ranged from 0.388 (fair) to 0.636 (substantial) across study cases for all criteria A.1 – H.1. The criteria for violence had exceptionally high inter-rater agreement, all being 0.947 and higher. The complexity of the ETIVB-construct transpired when inter-rater reliability analyses were compared between cases in that different cases posed different challenges for inter-rater agreement. The reliability testing across cases however, showed which less agreed-upon items would benefit from refinement. / Thesis (PhD)--University of Pretoria, 2015. / gm2015 / Psychiatry / PhD / Unrestricted
349

Amerikanska marinkårens taktik med pansarvärnsrobotför-band i Operation Desert Storm : Av relevans för svenska armén idag?

Vrenngård, Thomas January 2012 (has links)
Föreliggande arbete tar sin utgångspunkt i en observation av hur United States Marine Corps (USMC) använde pansarvärnsrobotförband förvånansvärt aggressivt under Gulfkriget 1991. Med syftet att studera denna taktik och att därigenom skapa en ökad förståelse för pansarvärnsrobotförbandens taktiska möjligheter/begränsningar skapas en problemformulering som undersöker vilken relevans USMC:s taktik med pansarvärnsrobotförband i Operation DESERT STORM har för svenska armén idag? För att kunna besvara denna övergripande fråga bryts den ned till tre forskningsfrågor som beskriver vilken taktik som karaktäriserade USMC:s pansarvärnsrobotförband, därefter förklarar motiven för denna taktik och slutligen värderar vilka lärdomar som svenska armén kan dra från detta 2012. Resultatet visar att marinkårens taktik i huvudsak har låg relevans på grund av de unika förutsättningar avseende terräng, siktförhållanden och teknikasymmetri som förelåg i Persiska viken 1991. Terrängen var nästan helt platt vilket gav god effekt för pansarvärnsrobotarnas övertag i skjutavstånd gentemot irakiska stridsvagnar. Oljerök och dimma gjorde att deras termiska sikten kunde verka där inga irakiska motsvarigheter fanns. Konceptet Combined Anti Armor Team bedöms värt att beakta för armén inom ramen för kombinerade vapen och slutförande av Insatsorganisation 2014.
350

Storm water pollution patrol: A thematic unit for use in elementary classrooms

Sánchez, Linda Ann 01 January 1996 (has links)
No description available.

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