Cerebral small vessel disease (SVD) is highly prevalent in older adults and is a predictor of stroke, dementia, and death. SVD is also associated with cognitive dysfunction, gait problems, and urinary incontinence. SVD is diagnosed based on white matter hyperintensities on T2 weighted scans. This thesis investigates the cardiac frequency component of resting state functional magnetic resonance imaging data in young healthy adults, older healthy adults, and older adults with pronounced SVD. A cardiac pulsatility metric is defined, and a tissue type contrast is observed between white matter, grey matter, and cerebrospinal fluid. Aging and disease effects are observed on cardiac pulsatility in white matter. The increased pulsatility may reflect the pathology of venous collagenosis and draining vein stenosis. Developing a better understanding of the etiology of SVD is an important step towards treating the disease.

Submerged arc welding (SAW) is commonly used for fabricating large diameter linepipes, pressure vessels and wind turbine towers due to its high deposition rate, high quality welds, ease of automation and low operator skill requirement. In order to achieve high melting efficiency required for high productivity, best weld quality and good mechanical properties in manufacturing industries, the welding process parameters need to be optimized. In this study, the effect of SAW current and speed on the physical and mechanical properties of ASME SA516 Gr. 70 (pressure vessel steel) and ASTM A709 Gr. 50 (wind turbine tower steel) were investigated. Three welding currents (700 A, 800 A and 850 A) and four travel speeds (5.9, 9.3, 12.3 and 15.3 mm/s) were used to weld sample plates measuring 915 mm x 122 mm x 17 mm. The weld quality and properties were evaluated using weld geometry measurements, visual inspection, ultrasonic inspection, hardness measurements, optical microscopy, tensile testing, Charpy impact testing and scanning electron microscopy. It was found that the physical and mechanical properties of the weldments were affected by SAW parameters. Severe undercuts were found at high travel speed and welding current. Low heat input caused lack of penetration defects to form in the weldments. The welding process melting efficiency (WPME) achieved was up to 80%. The hardness of the coarse grain heat affected zone (CGHAZ) and the weld metal increased with travel speed. The toughness of both materials increased with increasing travel speed and welding current. The yield and tensile strengths of the weldments of SA516 Gr.70 and A709 Gr.50 steels were within the same range as those of their respective parent metals because all test specimens broke in the parent metals. Also, the parent metals of both steels had the highest fracture strain and percent elongation. The percentage elongation increased with travel speed but decreased with welding current.

The lymphatic system is responsible for several vital roles in human body, one of which is maintaining fluid and protein balance. There is no central pump in the lymphatic system and the transport of fluid against gravity and adverse pressure gradient is maintained by the extrinsic and intrinsic pumping mechanisms. Any disruption of the lymphatic system due to trauma or injury can lead to edema. There is no cure for lymphedema partly because the knowledge of the function of the lymphatic system is lacking. Thus, a well-developed model of the lymphatic system is crucial to improve our understanding of its function. Here we used a lumped parameter approach to model a chain of lymphangions in series. Equations of conservation of mass, conservation of momentum, and vessel wall force balance were solved for each lymphangion computationally. Due to the lack of knowledge of the parameters describing the system in the literature, more accurate measurements of these parameters should be pursued to advance the model. Because of the difficulty of the isolated vessel and in-situ experiments, we performed a parameter sensitivity analysis to determine the parameters that affect the system most strongly. Our results showed that more accurate estimations of active contractile force and physiologic features of lymphangions, such as length/diameter ratios, should be pursued in future experiments. Also further experiments are required to refine the valve behavior and valve parameters.

Submerged arc welding (SAW) is commonly used for fabricating large diameter linepipes, pressure vessels and wind turbine towers due to its high deposition rate, high quality welds, ease of automation and low operator skill requirement. In order to achieve high melting efficiency required for high productivity, best weld quality and good mechanical properties in manufacturing industries, the welding process parameters need to be optimized. In this study, the effect of SAW current and speed on the physical and mechanical properties of ASME SA516 Gr. 70 (pressure vessel steel) and ASTM A709 Gr. 50 (wind turbine tower steel) were investigated. Three welding currents (700 A, 800 A and 850 A) and four travel speeds (5.9, 9.3, 12.3 and 15.3 mm/s) were used to weld sample plates measuring 915 mm x 122 mm x 17 mm. The weld quality and properties were evaluated using weld geometry measurements, visual inspection, ultrasonic inspection, hardness measurements, optical microscopy, tensile testing, Charpy impact testing and scanning electron microscopy. It was found that the physical and mechanical properties of the weldments were affected by SAW parameters. Severe undercuts were found at high travel speed and welding current. Low heat input caused lack of penetration defects to form in the weldments. The welding process melting efficiency (WPME) achieved was up to 80%. The hardness of the coarse grain heat affected zone (CGHAZ) and the weld metal increased with travel speed. The toughness of both materials increased with increasing travel speed and welding current. The yield and tensile strengths of the weldments of SA516 Gr.70 and A709 Gr.50 steels were within the same range as those of their respective parent metals because all test specimens broke in the parent metals. Also, the parent metals of both steels had the highest fracture strain and percent elongation. The percentage elongation increased with travel speed but decreased with welding current.

Submerged arc welding (SAW) is often the method of choice in pressure vessel fabrication. This process features high production rates, welding energy and/or welding speed and requires minimal operator skill. The selection of appropriate parameters in SAW is essential, not only to optimize the welding process in order to maintain the highest level of productivity, but also to obtain the most desirable mechanical properties of the weld.<p> The focus of this study was to investigate the effect of welding speed on the properties of SA516 Grade 70. Plates of SA516 Gr. 70 steel 17 mm x 915 mm x 122 mm were submerged arc welded with a welding current of 700 A and welding speeds of 15.3, 12.3 and 9.3 mm/s. Following the welding; strength, microstructure, hardness and impact toughness of the specimens were examined. Charpy impact testing was performed according to ASTM E 23 on specimens notched in the weld metal (WM) and in the heat-affected zone (HAZ), to measure the impact toughness. Fractography was performed on broken specimens using optical and scanning electron microscopy in order to correlate the mechanisms of fracture with the impact toughness values.<p> The highest hardness values were in the coarse-grained HAZ followed by the WM with the lowest hardness in the parent metal (PM). The HAZ had higher impact toughness than the WM and PM for all welding speeds. The slowest welding speed (9.3 mm/s) obtained complete penetration and therefore produced the most visually sound weld. The fastest welding speed (15.3 mm/s) had the narrowest HAZ and showed good ductile-to-brittle transition behaviour for both the WM and HAZ specimens, but produced incomplete penetration defects. Welding speed had little affect on the notch toughness of the HAZ with only a 9 J rise in upper shelf energy and an 8 °C drop in the impact transition temperature (ITT) with increased welding speed from 9.3 to 15.3 mm/s. However, for the WM, there was a 63 J drop in the upper shelf energy but also a 41 °C improvement of the ITT between the 9.3 and 15.3 mm/s welding speeds.

Die Geometrie eines Druckbehälters wird unter Zuhilfenahme parametrischer Bezierkurven und durch die Integration einer externen Mathcad-Analyse in Creo hinsichtlich einer harmonischen, meridianen Spannungsverteilung optimiert.

Simulation-News in Creo 1.0 & Creo 2.0 - Mechanica (neu: Simulate) Druckbehälter: Schraubenvorspannung / Betriebslast - Live-Präsentation in Creo 2.0 Berechnung eine Druckbehälters unter Berücksichtigung von: Schraubenvorspannung, Betriebslast, zeitabhängiger Lastaufbringung

Marine shipping industry is the biggest economy of the global logistics, the cost that the vessel runs includes: personnel's salary, insurance, shipping administration expense, port charges, maintenance and fuel, etc.. Among them port charges and fuel are estimated can probably take 70% of the total operating cost, and the proportion of the fuel cost may be up to 50%. So the fuel cost is a main reason for influencing the operation performance of shipping. Because the international oil price runs high in recent years, besides designing the optimization with ship type, vessel technology and development move towards the innovative study and application of the power-saving technology, in order to reduce the operating cost. In addition, in shipping management, it is main directions to move towards maximization of ship and energy-conservation to reduce the expenditure of the cost. Until high oil price and the whole world might face economic depression unfavorable factor, the motive force of shipping is unable to store, unable to reuse, so how to popularize energy-conserving actuating device and relevant environmental protection assists the energy-saving equipment, trader to boat last economic benefits greatest and how effective management energy and last greatest benefit, study the focal point for this thesis. This thesis is in Professor Zhang Yu-Shan's guidance, starts from the operating cost of shipping, discusses shipping machines and impact on operating cost of auxiliary energy- saving equipment, investigate of the shipping business to analyze and prove it. To feedback my experiences engaged in the relevant trade of the past 20 years.

The performance of Vessel Traffic Service (VTS) depends upon not only the facilities but the training and operational competence of the VTS operators. In this research, the current status and training scheme of four major VTS ports are reviewed. A fuzzy Analytic Hierarchy Process (AHP) model is subsequently developed to evaluate the training effectiveness of the VTS operators. The approach proposed enables experts to linguistically express opinions with degrees of truth of which the relationships are continuous. This solves the mapping problems between linguistic terms and discrete numerals resulting from traditional AHP methods. Four hierarchies comprising the factors of goals, competence, modules and subjects are constructed. The weights and priority of the elements for each hierarchy are acquired. The Grey Interval Measure method is also applied to analyze the training effectiveness and competence of the VTS operators by calculating the upper and lower bounds of the VTS-operator evaluations. The operational competence of VTS operators is judged by the experts invited. Finally, the interrelationships between the performance and the background indices are appreciated and the alternatives enhancing the performance of the VTS operators are identified. The measures include the recruitment of personnel with higher educational and professional backgrounds and enhancement of the professional trainings for the existing employees. The subjects of the training are also identified in this study. The contents and course hours should be appropriately organized and more attentions should be paid to the topics with higher weights. If the consistency with regard to the training schemes for the four VTS ports can be enhanced to a certain level, the quality of the VTS performance in Taiwanese waters will be increased. The marine safety will also be improved and marine environmental pollutions will be reduced.

A building project of new generation warship is required for national security, after long-term purchase plan and thoughtful evaluation. Based on the national policy, of ¡§Naval vessel built in native shipyard¡¨ to effectively build warships in native shipyard with limited manpower, under a planned quality management system, is the objective of this thesis. This thesis will start with the project management of shipyard for building warships in native shipyards. By collecting the quality management pattern of native shipyards, which had been involved in building projects of warships, personal investigation in the past experience, and information from interviewing experts, establish the key success hierarchy structure of quality management system for native shipyards to build warships. In addition, employ Analytic Hierarchy Process (AHP) to analyze the results of questionnaires of experts¡¦ interview to conduct the study of priority weighing. The objective of this thesis is to find important reference information for native shipyards and navy project managing authorities for warship building. Seven kernel items in shipyard quality management including the management of manpower resource, the management of design, the management of purchase, the management of production, the management of quality and quality document, the management of vendors, and the management of industrial safety and sanitation are explored. It is expected to achieve the most effective arrangement, planning, and execution under limited human resources, and to stabilize the quality of warship building by executing practice and the priority of those kernel items for future warship building projects.