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Zr-2.5 Nb pressure tubes in CANDU reactors are susceptible to delayed hydride cracking (DHC), which is a sub-critical cracking process requiring hydrogen diffusion to a stress concentrator, precipitation, growth and fracture of hydrides. Service-induced and manufacturing flaws are present in some pressure tubes and these flaws may act as crack initiators. An engineering approach has been developed to assess the susceptibility of flaws to DHC. In this methodology, DHC is separated into the initiation and growth stages, and in terms of initiation, flaws are classified as blunt, sharp or crack-like. The experiments performed in this thesis are related to crack-like flaws, which are assessed in terms of the threshold stress intensity factor, K1H, below which DHC cannot occur. There is a large scatter in the overall KIH data base and a lower bound value is conservatively used for flaw assessment. Systematic studies on un irradiated Zr-2.5 Nb pressure tube material have shown that KIH increases with decreasing hydrogen in solution, increasing deviation from the radial-axial plane of the tube, and increasing temperature, while thermal cycling has no significant effect on K1H. Therefore, it may be justifiable to use higher KIH values for assessing flaws with known orientation, hydrogen concentration at the flaw location and operating thermal history. If crack initiation is postulated, as part of a defence-in-depth approach, crack growth is assessed under two scenarios. (1) When the hydrogen concentration is sufficient for cracking to continue under sustained hot conditions, a leak-before-break assessment is performed. DHC velocity is required to determine the time for a crack to grow to the critical crack length for unstable fracture. This thesis shows that crack velocities at different temperatures depend strongly on the thermal history, which affects the hydrogen concentration in solution. Crack velocity increases with increasing hydrogen in solution. In addition, hydrogen supersaturation is required for cracking to occur at the reactor operating temperatures of 2S0-31O°C. (2) When the hydrogen concentration is insufficient for cracking to occur at normal operating temperatures, cracking can only occur during reactor cool-down when hydrides can precipitate as a result of the lowering of temperature. The amount of postulated crack growth per cool-down cycle depends on the crack initiation temperature during cooling. This thesis shows that the crack initiation temperature decreases with increasing cooling rate, and by applying a load-reduction of 20% prior to cooling. Cracking during cooling can be suppressed altogether by allowing the crack tip stress to relax by creep, followed by a load reduction of 15-20%. Recommendations are made regarding reactor loading and thermal history which can reduce the propensity for DHC. From the observations on hydride morphologies and fracture surface features of the DHC cracks under different test conditions, evidence is presented which supports the hydride/stress interaction diffusion model. The observations also demonstrate the inadequacies of the critical length criterion for fracture of a hydrided region.

A dual-station high frequency Wellen Radar (WERA), transmitting at 16.045 MHz, has been deployed along the Eastern Florida Shelf (EFS). From September 2004 to June 2005, a moored acoustic Doppler current profiler (ADCP) acquired subsurface current measurements within the radar footprint along the shelf break at 86-m depth. The shallowest ADCP bin located at 14-m depth is used as a comparison for the WERA surface measurements. The RMS differences range from 0.1 to 0.3 m s super -1 between the surface and 14-m depth, with good agreement over most of the period. Regression analyses indicate slopes near unity in the north-south (v-) component and approximately 0.5 for the east-west (u-) component velocities. Following validation of the HF radar surface current measurements, an assessment of the variability and character of eddies in the region is conducted for 2006. Optimal interpolation is utilized to create a uniform 45 km by 45 km grid of surface current data consisting of 1980 points in the inshore portion of the WERA domain. The Okubo-Weiss parameter is used to identify eddies as closed regions with values greater than a threshold of 2*10 super -8 s super -1. This method reveals a total of twenty-two eddy-like features over the year 2006. Given the asymmetric shape of the eddy regions, equivalent radii are computed as an estimate of eddy size with an annual average of 2.6 km. Eddy intensity is measured by maximum relative vorticity in the eddy region with an annual average of approximately 5f, where f is the local Coriolis parameter. Translational velocities are computed from the displacement of peak Okubo-Weiss parameter. This method tends to overestimate eddy speed given the shape-changing nature of the eddy regions. Nonetheless, the average translational velocity is 0.9 m s super -1 with a standard deviation of 0.4 m s super -1. Eddy tracks indicate a unique pattern in which eddies propagate inshore during the period of July to September and offshore during October to December related to position of the FC axis. The periodicity and spatial distribution of eddy events suggest that submesoscale eddy features are "wave-like" and centered along the strong topographical gradients between 200 to 600 m. By applying this methodology to other years of HF radar data, this statement can be tested with statistical confidence. In general, this study has shown the effectiveness of the Okubo-Weiss parameter in identifying eddy regions from a background field with large, ambient vorticity.

In order to understand the influence of topography and geometry to the flow and hydrological environments at Southeast coast of Taiwan, this study analyze data collected by tow-ADCPs in multiple cruises. The results are verified by Argos drifters. Field operations of tow-ADCP were carried out on April and September 2009 in the vicinity of Fugang harbor, Taitung. Drifters data were download from the web for the domain 15¢XN-25¢XN, 110¢XE-125¢XE during January 1st 1986 to July 31st 2010, with a total of 706 drift trajectories. The results show that: (1) There is a strong northward current near the coast of Taitung with maximum speed of 180 cm/s. The averaged flow velocity is 56 cm/s. The core of the current is centered at 10 km offshore in 200 m water depth. (2) The flow velocity decreases with depth. The average velocity is 97 cm/s in the upper 200 m, 42 cm/s in the middle layer 200m~400 m, and drop to 30 cm/s below 400 m. (3) The flow near the coast is deflected by the bottom topography, with upper layer flow to the northeast along the coastal line. The lower layer flows turn to west and southwest directions. (4) The transport estimated 3.3~7.2 Sv between Taiwan and LuDao (green island). (5) The flows are deflected by the ridge between LuDao and Cheng-Gong. The turns of flow can be explain by the conservation of vorticities, estimated 0.8*10-4s-1~1.2*10-4s-1. (6) The tidal current of is about a half of a knot, shoreward during flood with push Kuroshio northward. The tidal current is offshore during ebb. (7) The drifters data suggest there are eddies in this region. The surface current has seasonality, 80 cm/s in Spring , 100 cm/s in summer, 90 cm/s in fall, and 70 cm/s in winter.

In hydraulics, velocity distribution is needed to determine flow characteristics, like discharge, sediment discharge, head loss, energy coefficient, moment coefficient, and scour. However, the complicated interaction between water and sediment causes great difficulties in the measurement of flow and sediment discharge. Thus, the development of a method which can simulate the velocity distribution and sediment discharge in open channels is designable. Traditional methods for the estimation of velocity distribution, such as the Prandtl-von Karman logarithmic velocity and of sediment concentration distribution, such as the Rouse equation, are generally invalid at or near the channel bed and are inaccurate at the water surface. Considering the limitations of traditional methods, entropy based models have been applied, yet the assumption on the cumulative distribution function made in these methods limits their application. The objective of this research is to develop an efficient method to estimate velocity distribution and suspended sediment discharge in open channels using the Tsallis entropy. This research focuses on a better-organized hypothesis on the cumulative probability distribution function under more applicable coordinates, which should be transformable in different dimensions. Velocity distribution and sediment distribution are derived using the Tsallis entropy under the hypothesis that the cumulative probability distribution follows a non-linear function, in which the value of the exponent is shown to be related to the width-depth ratio of channel cross-section. Three different combinations of entropy and empirical methods for velocity and sediment concentration distribution are applied to compute suspended sediment discharge. Then advantages and disadvantages of each method are discussed. The velocity distribution derived using the Tsallis entropy is expected to be easy to apply and valid throughout the whole cross-section of the open channel. This research contributes to the application of entropy theory and shows its advantages in hydraulic engineering.

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The aim of this study was to develop and implement a low cost, high speed, flow visualisation tool for 3-D velocity measurement throughout time dependent particle seeded fluid flow volumes. To achieve this, a new high performance wind / water tunnel was designed and constructed using CFD as a design aid. The tunnel provided the necessary platform for obtaining consistent high quality images of fluid flow. Images were grabbed using low cost CCD cameras and downloaded via a PC mounted image capture board, to system RAM. The conventional high cost laser sheet illumination method was replaced with a low cost, portable floodlight system, which enabled both 2-D and 3-D flow volumes to be illuminated. For the 3-D image capture, stereo photogrammetric techniques were employed. Advanced calibration algorithms were developed which automatically detected camera positioning. This reduced the inherent human error associated with setting-up a complex imaging system. 2-D pattern matching and particle tracking algorithms were developed, optimised and tested using real and synthetically generated flow data, to establish practical limits for particle seeding density, particle image size, flow velocity and flow complexity. These results demonstrated that particle tracking was more suited to real-time 3-D applications. The developed algorithms formed the base of a Windows 95/Windows NT package for general purpose analysis of 2-D and 3-D single exposure image streams of particle seeded fluid flow.

Sludge disposal is a worldwide problem due to increasing volumes and respective environmental regulations. Currently the most common ways to dispose sludge are agricultural use, disposal in landfills, incineration and sea dumping. By drying sludge volumes can be decreased and the respective heating value increased. Sludge mainly originates from wastewater treatment. The Swedish pulp and paper mills produce approximately 400 000 - 500 000 metric tons of dry sludge each year. This includes roughly 60 000 metric tons of dry biosludge which mainly consists of bacteria and is difficult to dry due to high amounts of intercellular water. New drying methods for biosludge are hence needed. The purpose of this project is to investigate the possibility to dry biosludge in a high-velocity cyclone dryer since the technology has been shown to be able to handle sticky materials. The sludge used in this project originates from the biological wastewater treatment at the pulp and paper mill Metsä Board Husum, located in Husum, Sweden. The achieved dry matter contents and the specific energy consumption have been examined and compared with established drying methods.  Design of experiments has been used during the trials for optimizing the information attained from a limited number of trials including effects of inlet air temperature, sludge feeding rate and recycling of drying air. The respective factors were varied in three steps and relevant temperature, pressure, humidity, flow and material mass values were measured for analysing the process.  Models for attained dry matter content, specific energy consumption (total and of the fan), removed water and fan power were developed and had high statistical significance. The models showed that sludge dry matter content up to 80% could be achieved. The total specific energy consumption was over 1.6 kWh/kg H2O, which is higher than for established drying methods, but the specific energy consumption of the fan was as low as 0.7 kWh/kg H2O. The specific energy consumption of the fan was used to approximate dryer operation with excess heat during which it could compete with all established drying methods. A case where the excess heat available at Metsä Board Husum would be used to dry generated biosludge was investigated and supported a need for a priority order between maximizing sludge dry matter content and minimizing specific energy consumption of sludge drying. If sludge dry matter content is prioritised alternative drying methods may prove more suitable. To attain a better understanding of the high-velocity cyclone dryer and drying of biosludge the evaporation energy of sludge at different dry matter contents, the effects of various sludge inflow temperatures and the effect of fan rotation speed should be included future investigations. / Bortskaffande av slam har blivit ett världstäckande problem på grund av stora volymer och miljöreglering. De vanligaste sätten att bortskaffa slam är genom markanvändning, deponering, förbränning och dumpning i haven. Genom att torka slammet minskar volymen och värmevärdet ökar. Slammet har sitt ursprung i vattenrenings processer och svenska pappers- och pappersmassabruk producerar ungefär 400 000 – 500 000 ton slam per år i torrvikt. Av dessa är ungefär 60 000 ton biologiskt slam som till största del består av bakterier och är svårtorkat på grund av den höga andelen intercellulärt vatten. För att torka biologiskt slam behövs nya torkmetoder och syftet med detta projekt vara att undersöka möjligheten att torka biologiskt slam i en cyklontork då cyklontorken kan hantera kladdiga material. Slammet som använts under projektet kommer från pappersbruket Metsä Board Husum. Torrhalten som kunde uppnås och den specifika energin har undersökt och jämförts med etablerade torkmetoder. Design of experiments användes för att optimera informationen som går att få ut från ett begränsat antal försök och påverkan av inluftstemperaturen, matningshastigheten av slammet och positionen av spjället i luftåtervinningssystemet har undersökts. Faktorerna varierades i tre steg och temperaturer, tryck, luftfuktigheter, flöden och vikter har mätts för att analysera processen.  Modeller för torrhalten, den specifika energin (totalt och för fläkten), avdrivet vatten och fläkteffekten har beräknats med hög statistisk signifikans. Modellerna visar att upp till 80 % torrhalt kan nås. Den totala specifika energin ligger över 1.6 kWh/kg H2O vilket är högre än den specifika energin för etablerade torkmetoder men den specifika energin för fläkten kan understiga 0.7 kWh/kg H2O. Den specifika energin för fläkten kan approximera att torken körs med överskottsvärme och det är fallet kan cyklontorken konkurer med de etablerade torkmetoderna. Möjligheten att använda sig av överskottsvärmen på pappersbruket Metsä Board Husum för att torka deras biologiska slam har undersökts och en prioritering mellan hög torrhalt och låg specifik energi kommer behöva göras. Om hög torrhalt prioriteras kan andra torkmetoder vara att föredra. För att öka förståelsen för cyklontorken och torkning av biologiskt slam kan förångningsenergin för slammet vid olika torrhalter, effekten på torkresultaten från olika temperaturer på slammet in i cyklonen och effekten av olika effekter på fläkten undersökas.