Monopile Foundation Offshore Wind Turbine Simulation and Retrofitting

Offshore wind turbines (OWT) provide a renewable source of energy with great proximity to many large cities. This has caused a major increase in OWT development and implementation, primarily in Europe, but spreading throughout the world. There are a multitude of different foundation options, each with their own benefits. The most common types are: monopile, jacket, TLP, Semi-Submersible, and SPAR. The monopile foundation OWT has been proven to be the most economic selection for water depths up to approximately 25m. This thesis has analyzed strictly monopile foundations due to their previous success and popularity. Three different chapters have been created to cover the two different research papers contained in this thesis. Chapter one utilizes the software ANSYS to complete a multi-hazard computational fluid dynamic (CFD) analysis of a monopile foundation OWT. A dynamic analysis was performed on the structure, with a p-y curve soil-structure interaction implemented. Chapter two aims to verify the plausibility of a retrofit solution to a significant problem certain previously installed monopiles have developed. The annulus grout of the transition zone of the structure has been determined to be under-designed, and thus has experienced crushing. This allows the tower to slightly slide down the monopile, increasing the chances of total structural failure. A retrofit bolted connected has been implemented, and proven to significantly increase the limiting shear capacity of the structure. The research paper in chapter three is focused on developing the retrofit solution into a more applicable design. Using a response surface methodology (RSM) an optimized design criteria has been generated based on six geometric/material parameters of the bolted connection: horizontal spacing, vertical spacing, bolt diameter, number of bolts in vertical columns, pre-tensioning load on bolt, and modulus of elasticity

Regional Impact Models

This survey of regional input-output models and their use in impact analysis evolved from over twenty years of experience in constructing regional economic models and in teaching about them. Its objectives are to present this family of models in an easily understood format, to show that the models we use in economics are well-structured, and to provide a basis for understanding applications of these models in impact analysis. The models are presented in such a way that understanding the logic and algebra of the simplest economic-base model leads to an understanding of the only slightly more complex regional and interregional input-output models in common use today. The advanced models become matrix-algebra extensions of the simple models.https://researchrepository.wvu.edu/rri-web-book/1006/thumbnail.jp

Bed-Site Selection by Neonatal White-tailed Deer in Central North Dakota

Understanding bed-site selection and vegetation characteristics provides valuable information for population management (Verme 1977, Huegel et al. 1985a, Nelson and Woolf 1987). Predation and other natural-caused mortalities of white-tailed deer (Odocoileus virginianus) neonates are most likely to occur within the first 60 days of life; a time period when selected habitat characteristics are vital to survival (Verme 1977, Huegel et al. 1985a, Nelson and Woolf 1987, Grovenburg et al. 2010). Prior to the study of Grovenburg et al. (2010), limited research had been completed on bed-site selection of neonatal white-tailed deer in the grasslands of the Northern Great Plains. In north-central South Dakota, increase in vertical height of vegetation was the most important habitat characteristic at bed sites, which likely pertained directly to protection from predation and thermal insulation (Grovenburg et al. 2010, 2012a). Our objective was to describe the physical and vegetative characteristics of bed sites selected by neonatal white-tailed deer in the grassland dominated landscape of central North Dakota. We hypothesized that neonatal whitetailed deer would select bed sites characterized by relatively high understory vegetation to moderate ambient temperatures resulting in favorable microclimates for maintaining thermal neutrality while providing concealment from predator

NOTES: BED-SITE SELECTION BY NEONATAL WHITE-TAILED DEER IN CENTRAL NORTH DAKOTA

Understanding bed-site selection and vegetation characteristics provides valuable information for population management (Verme 1977, Huegel et al. 1985a, Nelson and Woolf 1987). Predation and other natural-caused mortalities of white-tailed deer (Odocoileus virginianus) neonates are most likely to occur within the first 60 days of life; a time period when selected habitat characteristics are vital to survival (Verme 1977, Hue- gel et al. 1985a, Nelson and Woolf 1987, Grovenburg et al. 2010). Prior to the study of Grovenburg et al. (2010), limited research had been completed on the bed-site selection of neonatal white-tailed deer in the grasslands of the Northern Great Plains. In north-central South Dakota, increase in vertical height of vegetation was the most important habitat characteristic at bed sites, which likely pertained directly to protection from predation and thermal insulation (Grovenburg et al. 2010, 2012a). Our objective was to describe the physical and vegetative characteristics of bed sites selected by neonatal white-tailed deer in the grassland dominated landscape of central North Dakota. We hypothesized that neonatal white-tailed deer would select bed sites characterized by relatively high understory vegetation to moderate ambient temperatures resulting in favorable microclimates for maintaining thermal neutrality while providing concealment from predators. We studied neonatal white-tailed deer in Burleigh County in central North Dakota, which comprised an area of 2,652 km2. The study area was located within the Northwestern Glaciated Plains level III Ecoregion (Bryce et al. 1998) and was characterized by significant surface irregularity and high concentration of wetlands (United States Department of Agriculture 2011). Long-term (30-year) mean summer temperatures ranged from 13.1° C to 27.5° C and mean (30- year) annual precipitation was 44.9 cm (North Dakota State Climate Office 2012). Nearly all land within the region was used for agricultural purposes. Grasslands and croplands dominated the landscape at 66.2% and 21.0%, respectively. Additionally, wetlands and water comprised 7.4%, developed land 5.2%, and other land uses \u3c1% of the landscape (United States Department of Agriculture 2011). Furthermore, Burleigh County had 4,884 ha in Wildlife Management Areas, 6,844 ha in National Wildlife Refuges, and 4,546 ha in Waterfowl Production Areas (C. Penner, North Dakota Game and Fish Department, personal communication)

Habitat Selection of White-tailed Deer Fawns and their Dams in the Northern Great Plains

Habitat availability can affect important life-history traits such as survival; however, little information exists on how microhabitat characteristics found at parturition sites selected by dams and bed sites selected by their offspring differ fromthe surrounding area and from each other. Therefore, we assessed how vegetation affected maternal parturition and offspring bed site selection for white-tailed deer (Odocoileus virginianus) in the Northern Great Plains. Dams selected for sites with decreased vegetation height, potentially improving their visibility, which may increase their ability to escape approaching predators. Conversely, there was no variation between vegetative characteristics at neonate bed sites and their associated random sites, indicating grasslands provide adequate concealment for neonates. Dams possess the ability to flee from approaching predators, thus increasing the importance of visibility while giving birth. Conversely, neonates depend on fear bradycardia as their main antipredator defense, so concealment is more important. Our results suggest that vegetation structure is an important characteristic to white-tailed deer as habitat needs vary between adults and neonates