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A New Technique for Measuring Runup Variation Using Sub-Aerial Video ImagerySalmon, Summer Anne January 2008 (has links)
Video monitoring of beaches is becoming the preferred method for observing changes to nearshore morphology. Consequently this work investigates a new technique for predicting the probability of inundation that is based on measuring runup variation using video. Runup is defined as the water-level elevation maxima on the foreshore relative to the still water level and the waterline is defined as the position where the MWL intersects the beach face. Tairua, and Pauanui Beaches, on the north east coast of the North Island of New Zealand, were used as the field site in this study and represent two very different beaches with the same incoming wave and meteorological conditions. Tairua is most frequently in an intermediate beach state, whereas Pauanui is usually flatter in nature. In order to rectify runup observations, an estimate of the runup elevation was needed (Z). This was estimated by measuring the variation of the waterline over a tidal cycle from time-averaged video images during a storm event and provided beach morphology statistics (i.e. beach slope (α) and beach intercept (b)) used in the rectification process where Z=aX+b. The maximum swash excursions were digitized from time-stacks, and rectified to provide run-up timeseries with duration 20 minutes. Field calibrations revealed a videoed waterline that was seaward of the surveyed waterline. Quantification of this error gave a vertical offset of 0.33m at Tairua and 0.25m at Pauanui. At Tairua, incident wave energy was dominant in the swash zone, and the runup distributions followed a Rayleigh distribution. At Pauanui, the flatter beach, the runup distributions were approximately bimodal due to the dominance of infragravity energy in the swash signal. The slope of the beach was a major control on the runup elevation; runup at Pauanui was directly affected by the deepwater wave height and the tide, while at Tairua there was no correlation. Overall, the results of the study indicate realistic runup measurements, over a wide range of time scales and, importantly, during storm events. However, comparisons of videoed runup and empirical runup formulae revealed larger deviations as the beach steepness increased. Furthur tests need to be carried out to see if this is a limitation of this technique, used to measure runup. The runup statistics are consistently higher at Tairua and suggests that swash runs up higher on steeper beaches. However, because of the characteristics of flatter beaches (such as high water tables and low drainage efficiencies) the impact of extreme runup elevations on such beaches are more critical in regards to erosion and/ or inundation. The coastal environment is of great importance to Māori. Damage to the coast and coastal waahi tapu (places of spiritual importance) caused by erosion and inundation, adversely affects the spiritual and cultural well-being of Māori. For this reason, a chapter was dedicated to investigating the practices used by Māori to protect and preserve the coasts in accordance with tikanga Māori (Māori protocols). Mimicking nature was and still is a practice used by Māori to restore the beaches after erosive events, and includes replanting native dune plants and using natural materials on the beaches to stabilize the dunes. Tapu and rahui (the power and influence of the gods) were imposed on communities to prohibit and prevent people from free access to either food resources or to a particular place, in order to protect people and/ or resources. Interpretations of Māori oral histories provide insights into past local hazards and inform about the safety and viability of certain activities within an area. Environmental indicators were used to identify and forecast extreme weather conditions locally. Māori knowledge of past hazards, and the coastal environment as a whole, is a valuable resource and provides a unique source of expertise that can contribute to current coastal hazards management plans in New Zealand and provide insights about the areas that may again be impacted by natural hazards.
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Det upphöjda landet : vetenskapen, landhöjningsfrågan och kartläggningen av Sveriges förflutna, 1860-1930Nordlund, Christer January 2001 (has links)
Taking the establishment of Ice Age theory as its point of departure, the present dissertation examines aspects of geological, plant geographical and archaeological research on shoreline displacement conducted in Sweden during the period 1860-1930, and the significance of this research for the perception of "the Swedish landscape" and its post-glacial history. The research is analyzed on three levels under the rubrics "The Highest Shoreline and the Ancylus Lake", "The Question of Land Elevation", and "Charting Swedens Past", respectively. Taken together, these levels capture the varying perceptions and exchanges of opinion of the nature of shoreline displacement and the contexts in which they were applied. The present study is conducted via a theoretical and methodological approach where both the ideas and the practices of science are studied: activities in the field and at the various institutions (primarily the Swedish Geological Survey, its museum and the Geological Society of Stockholm); arguments and hypotheses presented in artides and handbooks, including visual images, diagrams and maps; social networks, career paths and controversies. Particular attention is paid to the relationship between science and nationalism, and comparisons are made with research conducted in an imperialist context. Ice Age theory helped initiate research whose purpose was to discover how the Swedish naturai and cultural landscape carne into being. The foremost task of geology became studying geographic evolution during the Quaternary epoch, how the land had "risen from ice and water". Plant geography studied how and whence plant life had migrated and how vegetation had evolved under the influence of biological, geological and climatological factors. In a similar manner, archaeologists studied the migration and dissemination of mankind during the StoneAge. When natural scientists primarily used "natural landmarks" as its source material, archaeologists relied on "archaeological finds", which were invested with scientific value but also became symbols of national collective memory. Through this survey, national identity was unifìed with the territory itself and its evolutionary history. Knowledge about shoreline displacement became significant for geology, plant geography and archaeology, which in turn encouraged interdisciplinary collaboration, but also locked the researchers into a similar way of thinking about the nature of shoreline displacement. According to this "thought style", the phenomenon was first and foremost the result of the vertical movement of the land rather than movement in the ocean surface. Up until the 1870s, the Ice Age was thought to have been followed by one single subsidence and elevation; during the 1880s, two such land oscillations; three during the 1910s and by the 1920s, five. Only toward the end of the 1920s did Swedish researchers begin to accept a multi-factor explanation, which succeeded in finally subverting the reigning thought style. According to this explanation, shoreline displacement was not solely the result of changes in the land or the sea, but of both. / digitalisering@umu
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Geographic Indexing and Data Management for 3D-VisualisationOttoson, Patrik January 2001 (has links)
No description available.
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Cost-effectiveness and Value of Further Research of Treatment Strategies for Cardiovascular DiseaseHenriksson, Martin January 2007 (has links)
Economic evaluations provide a tool to estimate costs and health consequences of competing medical technologies, ultimately to aid decision makers when deciding which medical technologies should be funded from available resources. Such decisions inevitably need to be taken under uncertainty and it is not clear how to approach them in health care decision-making. Recent work in economic evaluation has proposed an analytic framework where two related, but conceptually different decisions need to be considered: (1) should a medical technology be adopted given existing evidence; and (2) whether more evidence should be acquired to support the adoption decision in the future. The proposed analytic framework requires a decision-analytic model appropriately representing the clinical decision problem under consideration, a probabilistic analysis of this model in order to determine cost-effectiveness and characterise current decision uncertainty, and estimating the value of additional information from research to reduce decision uncertainty. The main aim of this thesis is to apply the analytic framework on three case studies concerning treatment strategies for cardiovascular disease in order to establish whether the treatment strategies should be adopted given current available information and if more information should be acquired to support the adoption decisions in the future. The implications for policy and methodology of utilising the analytic framework employed in the case studies are also discussed in this thesis. The results of the case studies show that a screening programme for abdominal aortic aneurysm in 65-year-old men is likely to be cost-effective in a Swedish setting and there appears to be little value in performing further research regarding this decision problem; an early interventional strategy in non-ST-elevation acute coronary syndrome is cost-effective for patients at intermediate to high risk of further cardiac events in a UK setting; endarterectomy in patients with an asymptomatic carotid artery stenosis is cost-effective for men around 73 years of age or younger in a Swedish setting and conducting further research regarding this decision problem is potentially worthwhile. Comparing the results of the present analyses with current clinical practice shows a need for changing clinical practice in Sweden regarding screening for abdominal aortic aneurysm and endarterectomy in patients with asymptomatic carotid artery stenosis. Furthermore, employing the analytic framework applied in the case studies can improve treatment guidelines and recommendations for further research. In particular, treatment guidelines ought to consider in which particular subgroups of patients an intervention is cost-effective. The case studies indicate that it is feasible to apply the analytic framework for economic evaluation of health care. Methodological development can improve the accuracy with which cost-effectiveness and value of information is estimated, but may also lead to comprehensive and complex evaluations. The nature of the decision problem should determine the level of comprehensiveness required for a particular evaluation.
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High-resolution Permafrost Distribution Modelling for the Central and Southern Yukon, and Northwestern British Columbia, CanadaBonnaventure, Philip P. 19 April 2011 (has links)
Basal Temperature of Snow (BTS) measurements were used as the primary inputs to a high resolution (30 x 30 m grid cells) empirical-statistical regional permafrost probability model for the southern and central Yukon, and northernmost British Columbia (59° - 65°N). Data from seven individual study areas distributed across the region were combined using a blended distance decay technique, with an eighth area used for validation. The model predictions are reasonably consistent with previous permafrost maps for the area with some notable differences and a much higher level of detail. The modelling gives an overall permafrost probability of 52%. North of 62°N, permafrost becomes more extensive in the lowland areas whereas farther south permafrost is typically common only above treeline.
Significant differences exist between the mountain environments of the Yukon and the Swiss Alps where the BTS method originated and as a result different modelling approaches had to be developed. This work therefore: (1) develops additional explanatory variables for permafrost probability modelling, the most notable of which is equivalent elevation, (2) confirms the use of ground truthing as a requirement for empirical-statistical modelling in the Yukon and (3) uses a combination of models for the region in order to spatially predict between study areas.
The results of this thesis will be of use to linear infrastructure route-planning, geohazard assessment and climate change adaptation strategies. Future work employing the model will allow the effects of scenario-based climate warming to be examined.
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A GPU Stream Computing Approach to Terrain Database Integrity MonitoringMcKeon, Sean Patrick 10 July 2009 (has links)
Synthetic Vision Systems (SVS) provide an aircraft pilot with a virtual 3-D image of surrounding terrain which is generated from a digital elevation model stored in an onboard database. SVS improves the pilot's situational awareness at night and in inclement weather, thus reducing the chance of accidents such as controlled flight into terrain. A terrain database integrity monitor is needed to verify the accuracy of the displayed image due to potential database and navigational system errors. Previous research has used existing aircraft sensors to compare the real terrain position with the predicted position. We propose an improvement to one of these models by leveraging the stream computing capabilities of commercial graphics hardware. "Brook for GPUs," a system for implementing stream computing applications on programmable graphics processors, is used to execute a streaming ray-casting algorithm that correctly simulates the beam characteristics of a radar altimeter during all phases of flight.
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High-resolution Permafrost Distribution Modelling for the Central and Southern Yukon, and Northwestern British Columbia, CanadaBonnaventure, Philip P. 19 April 2011 (has links)
Basal Temperature of Snow (BTS) measurements were used as the primary inputs to a high resolution (30 x 30 m grid cells) empirical-statistical regional permafrost probability model for the southern and central Yukon, and northernmost British Columbia (59° - 65°N). Data from seven individual study areas distributed across the region were combined using a blended distance decay technique, with an eighth area used for validation. The model predictions are reasonably consistent with previous permafrost maps for the area with some notable differences and a much higher level of detail. The modelling gives an overall permafrost probability of 52%. North of 62°N, permafrost becomes more extensive in the lowland areas whereas farther south permafrost is typically common only above treeline.
Significant differences exist between the mountain environments of the Yukon and the Swiss Alps where the BTS method originated and as a result different modelling approaches had to be developed. This work therefore: (1) develops additional explanatory variables for permafrost probability modelling, the most notable of which is equivalent elevation, (2) confirms the use of ground truthing as a requirement for empirical-statistical modelling in the Yukon and (3) uses a combination of models for the region in order to spatially predict between study areas.
The results of this thesis will be of use to linear infrastructure route-planning, geohazard assessment and climate change adaptation strategies. Future work employing the model will allow the effects of scenario-based climate warming to be examined.
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Gps Based Altitude Control Of An Unmanned Air Vehicle Using Digital Terrain Elevation DataAtac, Selcuk 01 June 2006 (has links) (PDF)
In this thesis, an unmanned air vehicle (UAV) is used to develop a prototype base test platform for flight testing of new control algorithms and avionics for advanced UAV system development applications. A control system that holds the UAV at a fixed altitude above the ground is designed and flight tested. Only the longitudinal motion of the UAV is considered during the controller design, hence its lateral motions are controlled manually by a remote control unit from the ground. UAV& / #8217 / s altitude with respect to the mean sea level and position are obtained by an onboard global positioning system (GPS) and this information is transmitted to the ground computer via radio frequency (RF) communication modules. The altitude of the UAV above the ground is calculated by using the digital terrain elevation data (DTED). A controller is designed and its gains are tuned to maintain this flight altitude at a desired value by using the mathematical model developed to represent the longitudinal dynamics of the UAV. Input signals generated by the controller for elevator deflections are transmitted back to the UAV via RF communication modules to drive onboard servomotors to generate desired elevator deflections. All controller computations and RF communications are handled by a MATLAB® / based platform on a ground computer. UAV flight tests are carried out at two different autopilot modes / namely, mean sea level (MSL) altitude hold mode and above ground level (AGL) altitude hold mode. The developed platform worked properly during flight tests and proved to be reliable in almost every condition. Moreover, the designed controller system is demonstrated to be effective and it fulfills the requirements.
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Geographic Indexing and Data Management for 3D-VisualisationOttoson, Patrik January 2001 (has links)
No description available.
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USE OF LIDAR-DERIVED TERRAIN AND VEGETATION INFORMATION IN A DECIDUOUS FOREST IN KENTUCKYStaats, Wesley A. 01 January 2015 (has links)
The use of Light Detection and Ranging (LiDAR) information is gaining popularity, however its use has been limited in deciduous forests. This thesis describes two studies using LiDAR data in an Eastern Kentucky deciduous forest. The first study quantifies vertical error of LiDAR derived digital elevation models (DEMs) which describe the forests terrain. The study uses a new method which eliminates Global Positioning System (GPS) error. The study found that slope and slope variability both significantly affect DEM error and should be taken in to account when using LiDAR derived DEMs. The second study uses LiDAR derived forest vegetation and terrain metrics to predict terrestrial Plethodontid salamander abundance across the forest. This study used night time visual encounter surveys coupled with zero-inflation modeling to predict salamander abundance based on environmental covariates. We focused on two salamander species, Plethodon glutinosus and Plethodon kentucki. Our methods produced two different best fit models for the two species. Plethodon glutinosus included vegetation height standard deviation and water flow accumulation covariates, while Plethodon kentucki included only canopy cover as a covariate. These methods are applicable to many different species and can be very useful for focusing management efforts and understanding species distributions across the landscape.
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