Experimental work evaluated the dependence of the thickness of the cutting edge, its roughness and assessment of appearance with regard to the defects resulting from the diameter of the focal spot during oxidative cutting Yb:YAG laser. Other variables include the experiment: process parameters such as laser power, cutting speed, oxygen pressure and focus position. Experiment is based on the Taguchi tables. Test samples were cut off from sheet thickness 10, 15 and 20 mm. Representatives of conventional steel were S235JRC+N, S235JR, S235JR+N and steel type RAEX developed for laser and plasma cutting. Samples were evaluated according to the ČSN EN ISO 9013. The evaluation of samples was into classes according to standards of quality. Hardness measurements were performed on the samples thickness 20 mm of convectional steel and steel type RAEX.

The implementation of Unmanned Aerial Vehicles (UAVs) and Structure‐from‐Motion (SfM) photogrammetry in assessing forest structures for forest inventory and biomass estimations has shown great promise in reducing costs and labour intensity while providing relative accuracy. Tree Height (TH) and Diameter at Breast Height (DBH) are two major variables in biomass assessment. UAV-based TH estimations depend on reliable Digital Terrain Models (DTMs), while UAV-based DBH estimations depend on reliable dense photogrammetric point cloud. The main aim of this study was to evaluate the performance of multirotor UAV photogrammetric point cloud in estimating homogeneous and heterogeneous forest structures, and their comparison to more accurate LiDAR data obtained from Aerial Laser Scanners (ALS), Terrestrial Laser Scanners (TLS), and more conventional means like manual field measurements. TH was assessed using UAVSfM and LiDAR point cloud derived DTMs, while DBH was assessed by comparing UAVSfM photogrammetric point cloud to LiDAR point cloud, as well as to manual measurements. The results obtained in the study indicated that there was a high correlation between UAVSfM TH and ALSLiDAR TH (R2 = 0.9258) for homogeneous forest structures, while a lower correlation between UAVSfM TH and TLSLiDAR TH (R2 = 0.8614) and UAVSfM TH and ALSLiDAR TH (R2 = 0.8850) was achieved for heterogeneous forest structures. A moderate correlation was obtained between UAVSfM DBH and field measurements (R2 = 0.5955) for homogenous forest structures, as well as between UAVSfM DBH and TLSLiDAR DBH (R2 = 0.5237), but a low correlation between UAVSfM DBH and UAVLiDAR DBH (R2 = 0.1114). This research has demonstrated that UAVSfM can be adequately used as a cheaper alternative in forestry management compared to more highcost and accurate LiDAR, as well as traditional technologies, depending on accuracy requirements.

Background: Effects of cardiovascular (CV) risk factors on the diameter of the thoracic aorta have not been fully studied. This study examined the associations between CV risk factors and diameter of thoracic aorta. Materials and Methods: Study population comprised of 1273 asymptomatic adults aged ≥18 years from Central Appalachia region of the United States who participated in a coronary artery screening between January 2014 and December 2016. Descriptive statistics and multiple linear regression analyses were performed to examine associations between multiple CV risk factors and diameters of the thoracic aorta. Results: Mean (±SD) age of participants was 57.9±9.7 years; that of body mass index (BMI) was 29.4±5.9. The mean aortic sinus, ascending aorta, and descending aorta diameter were 34.1±4.4 mm, 33.8±4.4 mm, and 26.0±3.6 mm, respectively. Increasing age, being male, and having a higher BMI were associated with wider aortic sinus, ascending aorta, and descending aorta diameters. Hypertension (p < 0.05) and obesity (p < 0.0001) were significantly associated with wider diameter for all measured aortic diameters. Participants with diabetes had wider descending aorta compared to those without (26.6±3.9 mm vs. 25.9±3.5 mm, P = 0.012). Participants who had ever smoked a cigarette had significantly wider descending aorta diameter compared to never smokers (26.3±3.6 mm vs. 25.9±3.5 mm, p = 0.031). Conclusions: The study results suggest that decreasing BMI and management of CV risk factors such as hypertension and modifying behavioral risk factors such as smoking are likely to be emphasized in order to decrease the rate of aortic dilatation and subsequent aortic dissection, if aortic dilatation is detected during a CT scan.

Anticipated climate change and increasing wood demand require dependable diameter growth models for adaptive forest management. We used a mixed-effects modeling approach with Forest Inventory and Analysis (FIA) data to fit diameter growth models for loblolly pine, other softwood species (slash pine, shortleaf pine, and longleaf pine), sweetgum, and other hardwood (southern red oak, red maple, and water oak) species. Climatic variables coupled with individual tree attributes and competition factors improved climate insensitive models. Growth of loblolly pine and sweetgum was positively correlated with mean temperature of the coldest month. Mean temperature of the warmest month negatively influenced diameter growth of loblolly pine and other hardwood species. Growing season precipitation and summer precipitation balance had negative effects on the growth of softwood and hardwood species, respectively. Inclusion of FIA plot as random effect improved model fit statistics and residual distribution of climate sensitive models. These findings will be useful to managers for recalibrating diameter growth models resulting in improved biomass yield and volume estimates that will better inform decisions.

Cavitation is a phenomenon that occurs in liquids when the pressure drops below the vapor pressure of the liquid. Previous research has verified that cavitation bubble collapse is a dynamic and destructive process. An understanding of the behavior of cavitation is necessary to implement this destructive mechanism from an axisymmetric jet for underwater material removal. This work investigates the influence of jet pressure and nozzle diameter on the behavior of a cloud of cavitation bubbles generated by a submerged high-pressure water jet. First, this investigation is put into context with a condensed historical background of cavitation research. Second, a description of the cavitation-generating apparatus is given. Next, the experimental methods used to explore the behavior of the cavitation clouds are explained. Finally, the results of the investigation, including propagation distance, cloud width and area, pulsation frequency, and cloud front velocity are presented. Among the results is a discussion of the significant experimental factors affecting the behavior of the cavitation clouds. It is shown that the Reynolds number, specifically the diameter of the nozzle, has a significant effect on the measurements. In some cases the jet pressure, and subsequent jet velocity, had a less significant effect than was expected. Overall, this research describes the cavitation cloud formed when a submerged high-speed water jet discharges.

A dimensionally compatible system of equations for stand basal area, volume, and basal area and volume growth was derived using dimensional analysis. These equations are analytically and numerically consistent with dimensionally compatible individual tree volume and taper equations and share parameters with them. Parameters for the system can be estimated by fitting individual tree taper and volume equations or by fitting stand level basal area and volume equations. In either case the parameters are nearly identical. Therefore, parameters for the system can be estimated at the tree or stand level without changing the results. Data from a thinning study in loblolly pine (Pinus taeda L.) plantations established on cutover site-prepared lands were used to estimate the parameters. However, the developed system of equations is general and can be applied to other tree species in other locales. / Ph. D.

Высокие риски возникновения ценовых войн обуславливают неблагоприятную конъюнктуру на российском рынке труб большого диаметра, что подтверждает актуальность тематики исследования. Целью магистерской диссертации является разработка формулы расчета цены на трубу большого диаметра для российского рынка, которая поспособствует стабилизации ситуации. Цена, рассчитываемая по формуле, может учитывать всевозможные индикаторы рынка. Если она максимально приближена к текущим рыночным тенденциям, а также позволяет снизить риски неоправданного изменения цены, то такой механизм является наилучшим способом регулирования на рынке труб большого диаметра. В качестве источников информации использовалась учебно-методическая и научно-исследовательская литература, статистические данные Федеральной службы государственной статистики, данные бухгалтерской и управленческой отчетности предприятий. / High risks of price wars cause unfavorable conditions on the Russian market of large diameter pipes, which confirms the relevance of the research topic. The purpose of the master's thesis is to develop a formula for calculating the price of a large diameter pipe for the Russian market, which will contribute to the stabilization of the situation. The price calculated using the formula can take into account various market indicators. If it is as close as possible to current market trends, and also reduces the risks of unjustified price changes, then this mechanism is the best way to regulate the market for large diameter pipes. Educational and research literature, statistical data of the Federal state statistics service, and data on accounting and management reports of enterprises were used as sources of information.

Hurricane Katrina had a devastating impact on bottomland hardwood forests in 2005 resulting in damage to nearly 1.2 billion cubic meters of timber. Following such a natural disaster, natural regeneration is typically not a viable option because the seed source has been destroyed on site. Therefore, an economically efficient method of artificial regeneration is considered the most appropriate technique for reforesting these damaged areas. However, few studies have evaluated comparative research that examined early survival and growth performance of various oak species and stock types in such planting settings. This project was implemented in an effort to expand upon what is already known from previous artificial regeneration attempts on Hurricane Katrina damaged lands. Bareroot, conventional containerized, and large potted EKOgrownTM seedlings of cherrybark oak (Quercus pagoda Raf.) and willow oak (Quercus phellos L.) were planted on two sites located in south Mississippi. Survival was assessed monthly and at the end of each growing season, whereas height and groundline diameter (GLD) were measured immediately post planting and at the end of each growing season. Analysis of variance (ANOVA) and Tukey-Kramer multiple comparisons procedure (MCP), where appropriate, were performed to determine any significant differences. After the first growing season, cherrybark oak did not exhibit a substantial difference regarding survival performance when compared to willow oak (75.5 percent and 76.5 percent, respectively). After two growing seasons, willow oak exhibited considerably greater survival (74.0 percent) overall when compared to cherrybark oak (70.5 percent). Bareroot seedlings had the highest survival (87.2 percent). Conventional containerized seedlings had unacceptable survival (47.5 percent) and EKOgrownTM seedlings had acceptable survival (82.0 percent). EKOgrownTM seedlings demonstrated the best overall GLD growth of all planting stocks (3.9 mm respectively). Bareroot seedlings had the second best overall GLD growth (1.5 mm) and conventional containerized had the least amount of overall GLD growth (0.8 mm). Overall height growth when comparing all three planting stocks bareroot, conventional containerized, and EKOgrownTM were similar to one another (-3.5cm, -0.8cm, and -3.6cm respectively). Therefore, based on an overall consideration of cost and performance, bareroot seedlings are considered the most effective option of the two species considered for artificial regeneration utilized in this study.

Solar images are one of the most important sources of available information on the current state and behaviour of the sun, and the PICARD satellite is one of several ground and space-based observatories dedicated to the collection of that data. The PICARD satellite hosts the Solar Diameter Imager and Surface Mapper (SODISM), a telescope aimed at continuously monitoring the Sun. It has generated a huge cache of images and other data that can be analysed and interpreted to improve the monitoring of features, such as sunspots and the prediction and diagnosis of solar activity. In proportion to the available raw material, the little-published analysis of SODISM data has provided the impetus for this study, specifically a novel method of contributing to the development of a system to enhance, detect and segment sunspots using new hybrid methods. This research aims to yield an improved understanding of SODISM data by providing novel methods to tabulate a sunspot and filling factor (FF) catalogue, which will be useful for future forecasting activities. The developed technologies and the findings achieved in this research will work as a corner stone to enhance the accuracy of sunspot segmentation; create efficient filling factor catalogue systems, and enhance our understanding of SODISM image enhancement. The results achieved can be summarised as follows: i) Novel enhancement method for SODISM images. ii) New efficient methods to segment dark regions and detect sunspots. iii) Novel catalogue for filling factor including the number, size and sunspot location. v) Novel statistical method to summarise FFs catalogue. Image processing and partitioning techniques are used in this work; these methods have been applied to remove noise and detect sunspots and will provide more information such as sunspot numbers, size and filling factor. The performance of the model is compared to the fillers extracted from other satellites, such as SOHO. Also, the results were compared with the NOAA catalogue and achieved a precision of 98%. Performance measurement is also introduced and applied to verify results and evaluate proposal methods. Algorithms, implementation, results and future work have been explained in this thesis.

No description available.