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Geometric accuracy improvement of VHR satellite imagery during orthorectification with the use of ground control pointsHenrico, Ivan January 2016 (has links)
Conducting single frame orthorectification on satellite images to create an ortho-image requires four basic components, namely an image, a geometric sensor model, elevation data (for example a digital elevation model (DEM)) and ground control points (GCPs). For this study, orthorectification was executed numerous times (in three stages) and each time components were altered to test the geometric accuracy of the resulting ortho-image. Most notably, the distribution and number of ground control points, the quality of the elevation source and the geometric sensor model or lack thereof were altered. Results were analysed through triangulating and comparing the geolocation accuracy of the ortho-images. The application of these different methods to perform orthorectification encompass the aim of this paper, which was to investigate and compare the positional accuracies of ortho-images under various orthorectification scenarios and provide improved geometric accuracies of VHR satellite imagery when diverse ground control and elevation data sources are available. By investigating the influence that the distribution and number of GCPs and the quality of DEMs have on the positional accuracy of an ortho-image, it became clear that a reasonable increase in the number of uniformly distributed GCPs combined with progressively accurate DEMs will ultimately improve the quality of the orthorectified product. The results also showed that when more GCPs were applied, the smaller the difference in accuracy was between the different DEMs utilised. It was interesting to note that when it is suitable to manually collect well-distributed GCPs using a GPS handheld device over the study area then a very accurate result can be expected. Nonetheless, it is also important to note that if it is not possible/practical to achieve the latter, satellite based GCP collection do provide a very good alternative. It was also determined that utilising GCPs which were extracted from vector road layers to only cover specific areas in the image scene produced less favourable results. Several contributions towards improved orthorectification procedures were made in this study. These include the development of an automatic GCP extraction script (A-GCP-ES), written in the Python scripting language with the purpose to ease the process of manually placing GCPs on an input image when repeatedly performing orthorectification. / Thesis (PhD)--University of Pretoria, 2016. / Geography, Geoinformatics and Meteorology / PhD / Unrestricted
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The Effects of Elevation on Foraging Behavior of Bats in Southern AppalachiaLong, Victoria 01 August 2020 (has links)
There are limited studies on bat activity in higher elevations in the Appalachian region. Levels of bat activity were compared in south central Appalachia at low (< 914.4 m) and high (> 1, 524 m) elevations in open, forest edge, and riparian habitats. Additionally, habitat suitability was modeled for a common species, big brown bat (Eptesicus fuscus). The study started May 27th 2019, and sites were monitored biweekly until October 2nd 2019. Six species and one genus were recorded during the study. Species from the Myotis genus were grouped together because of similar call characteristics. Results show that species were significantly more active in the lower elevations (F= 44.22, p
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Hg concentration in humus soils in different Arctic and Subarctic tundra vegetation types : Including a method comparison for analyzing metals in humus soils / Kvicksilverkoncentration i humusjordar i olika arktiska och subarktiska vegetationstyper : Inklusive en metodjämförelse för metallanalys i humusjordarSandvärn, Alice January 2022 (has links)
Heavy metals, such as mercury (Hg), have a long residence time in the atmosphere and can be transported long distances and deposited in the Arctic via wet and dry deposition. Still, there are few studies on the complex mercury cycle and how different plant groups absorb Hg. In this study, I investigated if and/or how Hg concentrations differ between different humus soils in tundra vegetation types in Alaska and Abisko. I also investigated the potential changes in Hg deposition with increasing elevation in Abisko (500, 750, and 1000 m a.s.l). Further, a comparison between the analyzing methods XRF (X-ray fluorescence) and HF digestion was evaluated to investigate if XRF is a suitable method for analyzing heavy metals in the humus layer of soils. To achieve this, humus soil samples from four different vegetation types in Alaska and two from Abisko were analyzed with a Hg analyzer (DMA-80 Direct Mercury Analyzer) and a handheld XRF. The results show that Hg concentration was highest in heath vegetation for Alaska and Abisko. Meanwhile, increasing elevation had no impact on Hg concentration in general, nor was there a difference within the two vegetation types. The comparison between HF digestion and XRF resulted in a positive linear relationship for P, Fe, and Al. The results highlight that Hg concentration differs between humus soil due to different vegetation types, although there is no clear explanation to the distribution of Hg in aboveground vegetation. Litterfall and precipitation may influence Hg concentrations with elevation, and the XRF samples need to be replicated multiple times to avoid errors, as my study shows.
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Terrain Object recognition and Context Fusion for Decision SupportLantz, Fredrik January 2008 (has links)
A laser radar can be used to generate 3D data about the terrain in a very high resolution. The development of new support technologies to analyze these data is critical to the effective and efficient use of these data in decision support systems, due to the large amounts of data that are generated. Adequate technology in this regard is currently not available and development of new methods and algorithms to this end are important goals of this work. A semi-qualitative data structure for terrain surface modelling has been developed. A categorization and triangulation process has also been developed to substitute the high resolution 3D model for this data structure. The qualitative part of the structure can be used for detection and recognition of terrain features. The quantitative part of the structure is, together with the qualitative part, used for visualization of the terrain surface. Substituting the 3D model for the semi-qualitative structures means that a data reduction is performed. A number of algorithms for detection and recognition of different terrain objects have been developed. The algorithms use the qualitative part of the previously developed semi-qualitative data structure as input. The taken approach is based on matching of symbols and syntactic pattern recognition. Results regarding the accuracy of the implemented algorithms for detection and recognition of terrain objects are visualized. A further important goal has been to develop a methodology for determining driveability using 3D-data and other geographic data. These data must be fused with vehicle data to determine the properties of the terrain context of our operations with respect to driveability. This fusion process is therefore called context fusion. The recognized terrain objects are used together with map data in this method. The uncertainty associated with the imprecision of the data has been taken into account as well. / <p>Report code: LiU-Tek-Lic-2008:29.</p>
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Tako-Tsubo Syndrome as a Consequence of Transient Ischemic AttackAbi-Saleh, Bernard, Iskandar, Said B., Schoondyke, Jeffrey W., Fahrig, Stephen 01 December 2006 (has links) (PDF)
An 82-year-old woman presented to the emergency department with chest pain after sustaining a transient ischemic attack 1 week prior to presentation. Electrocardiography revealed ST-segment elevation in leads I, II, aVF, and V3 through V6. Coronary angiography demonstrated nearly normal coronaries but left ventriculography showed apical akinesis and basal hyperkinesis. One month later her follow-up echocardiography showed no wall motion abnormalities. Several reports of tako-tsubo syndrome or transient left ventricular apical ballooning have been described, especially in Japan. We present a case with the typical features of the syndrome after a cerebrovascular accident.
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Impact of Chronic Kidney Disease on Revascularization and Outcomes in Patients with ST-Elevation Myocardial InfarctionPanchal, Hemang B., Zheng, Shimin, Devani, Kalpit, White, Christopher J., Leinaar, Edward F., Mukherjee, Debabrata, Mamas, Mamas, Banerjee, Subhash, Bhatt, Deepak L., Jneid, Hani, Samady, Habib, Mehran, Roxana, Gharacholou, Shahyar M., Paul, Timir K. 01 July 2021 (has links)
Chronic kidney disease (CKD) in patients with ST-elevation myocardial infarction (STEMI) is associated with worse outcomes. We assessed the impact of CKD on guideline directed coronary revascularization and outcomes among STEMI patients. The Nationwide Inpatient Sample dataset from 2012-2014 was used to identify patients with STEMI using International Classification of Diseases, Ninth Revision, Clinical Modification codes. Patients were categorized as non-CKD, CKD without dialysis, and CKD with dialysis (CKD-HD). Outcomes were revascularization, death and acute renal failure requiring dialysis (ARFD). A total of 534,845 were included (88.9% non-CKD; 9.6% CKD without dialysis, and 1.5% CKD-HD). PCI was performed in 77.4% non-CKD, 56.2% CKD without dialysis, and 48% CKD-HD patients (p < 0.0001). In-hospital mortality and ARFD were significantly higher in CKD patients (16.5% and 40.6%) compared with non-CKD patients (7.12% and 7.17%) (p < 0.0001). In-hospital mortality was significantly lower in patients treated revascularization compared with patients treated medically (non-CKD: adjusted odds ratio (aOR) 0.280, p < 0.0001; CKD without dialysis: aOR 0.39, p < 0.0001; CKD-HD: aOR 0.48, p < 0.0001). CKD was associated with higher length of hospital stay and cost (5.86 ± 13.97, 7.57 ± 26.06 and 3.99 ± 11.09 days; p < 0.0001; $25,696 ± $63,024, $35,666 ± $104,940 and $23,264 ± $49,712; p < 0.0001 in non-CKD, CKD without dialysis and CKD-HD patients respectively). In conclusion, CKD patients with STEMI receive significantly less PCI compared with patients without CKD. Coronary revascularization for STEMI in CKD patients was associated with lower mortality compared to medical management. The presence of CKD in patients with STEMI is associated with higher mortality and ARFD, prolonged hospital stay and higher hospital cost.
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Geographic Information System Topographic Factor Maps for Wildlife ManagementMcCombs, John Wayland II 30 July 1997 (has links)
A geographic information system (GIS) was used to create landform measurements and maps for elevation, slope, aspect, landform index, relative phenologic change, and slope position for 3 topographic quadrangles in Virginia. A set of known observation points of the Northern dusky flying squirrel (Glaucomys sabrinus) was used to build 3 models to delineate sites with landform characteristics equivalent to those known points. All models were built using squirrel observation points from 2 topographic quadrangles. The first model, called "exclusionary", excluded those pixels with landform characteristics different from the known squirrel pixels based on histogram analyses. Logistic regression was used to create the other 2 models. Each model resulted in an image of pixels considered equivalent to the known squirrel pixels. Each model excluded approximately 65% of the Highland study area, but the exclusionary model excluded the fewest known squirrel pixels (12.62%). Both logistic regression models excluded approximately 10% more known squirrel pixels than the exclusionary approach. The models were tested in the area of a third quadrangle with points known to be occupied by squirrels. After the model was applied to the third topographic quadrangle, the exclusionary model excluded the least amount of full-area pixels (79.30%) and only 14.81% of the known squirrel pixels. The second logistic regression excluded 81.16 % of the full area and no known squirrel pixels. All models proved useful in quickly delineating pixels equivalent to areas where wildlife were known to occur. / Master of Science
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The Effects of Elevation and Vegetation Type on Snow Accumulation and Melt in Logan Canyon, UtahThies, Paul R. 01 May 1973 (has links)
Snow accumulation and melt characteristics were studied in Logan Canyon, Utah. Three replications of aspen, conifer, and open field types at 6300, 7100,and 8000 feet were measured for snow depth and water content during 1972. Elevation was found to have the greatest effect on snow water content. The gradient of increasing water content with rise ln elevation was found to be .51 inches/100 feet in the zone from 6300 to 7100 feet and 1.9 inches/100 feet from 7100 to 8000 feet. The cooler temperatures at higher elevations partially account for the 8000 foot zone beginning to melt 40 days after the 7100 foot zone, and the 7100 foot zone trailing the 6300 foot zone by 20 days. Although the snow at the 8000 foot elevation began melting later than the lower zones, it melted at twice the rate. Vegetation cover type has no significant effect on the amount of snow deposited. However, the conifer type protects the snowpack from solar radiation causing the snowpack to have a significantly lower density than the snowpack assocaited with either aspen or open field. The snowpack under the conifer canopy melts 30 percent slower and remains 17 days longer.
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IMPROVEMENT OF RICE CROPPING IN SALINE SOILS IN THE NORTH CENTRAL COASTAL REGION OF VIETNAM / ベトナム北中部沿岸部の塩性土壌地帯における稲作農業の改良に関する研究Nguyen Ho Lam 23 January 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第18694号 / 農博第2091号 / 新制||農||1029(附属図書館) / 学位論文||H27||N4888(農学部図書室) / 31627 / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 舟川 晋也, 教授 縄田 栄治, 教授 間藤 徹 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
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Advancements in geospatial monitoring of structuresBaldwin, Jordan Keith 12 May 2023 (has links) (PDF)
The need for advancements in geospatial monitoring of structures has evolved naturally as structures have become larger, more complex, and technology has continued to rapidly develop. Greater building heights generally lead to greater challenges for surveyors, limiting the practical use of traditional measurement methods. For this reason, a new complimentary method was developed and implemented to support elevation monitoring activities during construction of the Salesforce Tower in San Francisco, California. While some studies have explored the use of strain gauges to monitor strain development within individual members, the primary contribution of this work is that it presents a practical and proven to be implementable approach to estimating elevation changes throughout a multi-story reinforced concrete core wall tower during construction while utilizing strain measurements acquired at intermittent levels.
Construction in urban landscapes has the potential to impact existing infrastructure. Identifying and mitigating any associated construction impacts is critical to public safety and construction progress. The development of Automated Motorized Total Stations (AMTS) has provided an effective means to monitor deformations in structures adjacent to construction activity. AMTS provides real time results so that movements may be immediately identified and addressed. However, the design, implementation, management, and analysis of these systems has frequently been problematic. Inadequate monitoring specifications have led to systems that fail to perform as intended even when project requirements were satisfied. A collection of monitoring specifications and AMTS projects have been reviewed to identify why certain problems have occurred and recommendations have been made to increase the probability of success on monitoring projects. A deformation monitoring approach that defines location specific threshold values based on a statistical analysis of baseline measurements is also presented in this dissertation. Identifying potential causes for monitoring specifications to fail to perform as intended and a deformation monitoring approach that defines location specific threshold values are secondary contributions of this dissertation.
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