4,050 research outputs found
T.J. Stiles: “The Commodore’s Patriotism: Cornelius Vanderbilt’s Path to the Founding of Vanderbilt University”
No full textIncludes descriptive metadata provided by producer in MP4 file: "Chancellor's Lecture Series - Videos - T.J. Stiles: 'The Commodore’s Patriotism: Cornelius Vanderbilt’s Path to the Founding of Vanderbilt University'." By Vanderbilt University. T.J. Stiles, Pulitzer Prize-winning author and historian, speaks Sept. 29, 2010 as part of the Chancellor's Lecture Series. Stiles wrote the 2009 biography The First Tycoon: The Epic Life of Cornelius Vanderbilt. Chancellor Nicholas Zeppos introduces Stiles. Stiles takes questions after his lecture
Cwbr Author Interview: Custer\u27s Trials: A Life On The Frontier Of A New America
Full text linkInterview with T.J. Stiles, author of Custer\u27s Trials: A Life on the Frontier of a New America Interviewed by Tom Barber
Civil War Book Review (CWBR): The Civil War Book Review is pleased to speak with T.J. Stiles, winner of multiple awards for biography and author of Jesse James: Last Rebel of the Civil War and The First Tycoon: The Epic Life of Cornelius Vanderbilt. Today we get to discuss his most recent work Custer\u27s Trials: A Life on the Frontier of a New America. Mr. Stiles, thank you for joining us today. T.J. Stiles: Thanks very much for interviewing me...
Ecotechnologies applied on agricultural irrigation and drainage channels- case study Taichung Irrigation Association in Taiwan
No full textGiant epithelial ingrowth induced by blunt injury after automated lamellar keratoplasty.
No full textTidal flat landscape formation and evolution
No full textTidal flat landscape formation and evolution are closely related to the biotic and abiotic processes that take place in the intertidal environments. Extensive studies have been carried out on the relevant agents such as hydrodynamics, sediment transport and the related ecosystem (vegetation and benthic communities) dynamics. However, the feedback mechanism among multiple agents is complex and many key aspects are currently understudied. In times of accelerating global change, knowledge of the mechanisms that drive tidal flat evolution is of great importance to ecosystem conservation and restoration. This thesis addresses the currently understudied subjects related to intertidal hydrodynamic processes as well as the intertidal landscape developments, which are of great economic and ecological importance.Hydraulic EngineeringCivil Engineering and Geoscience
Drag forces on vegetation due to waves and currents
No full textVegetation in coastal areas plays an important role in its environment. In addition, vegetation can also be utilized for coastal protection. Incoming wave energy could be effectively attenuated by the upstanding vegetation plants. The reduced wave energy results in stabilized seabed and harmonious environment in coastal zones. Nowadays, an increasing number of projects have been carried out to apply vegetation as a soft measure for coastal protection. Wave energy dissipation by vegetation is primarily induced by the work done by drag force acting on the vegetation. A drag coefficient (CD) is introduced to characterize the flow resistance from the plant stems. Knowledge of CD is of great importance for understanding and predicting the wave dissipation process. In previous studies, relations between CD and Reynolds number (Re) have been proposed in pure current or pure wave. In addition, relations between CD and the Keulegan-Carpenter number (abbreviated as KC and KC=Uw*Tw/d, Tw is the wave period and d is the plant stem diameter) have also been suggested. In Keulegan-Carptenter number, the wave period Tw is also considered. Since waves are oscillatory flow, it would be preferable to use the KC number to describe the behaviour of CD in wave-present conditions. However, contradictory conclusions are found in the literature on the CD-KC relation in pure wave condition. Monotonous decreasing of CD with KC has been reported for multiple vegetation mimics. On the contrary, the rise-and-fall variation trend has been observed in pure wave, but only for single cylinder. It is noted that the transition point (from rise to fall) occurs when KC value is small, which is often left out in the experiment with multiple vegetation mimics in previous studies. Hence, it is necessary to investigate the variation trend of CD-KC for multiple vegetation mimics in pure wave with a wider KC range. Moreover, background tidal currents may also play a role in the wave dissipation process. It is often the case that when the tide penetrates the coastal wetlands during flooding phase, waves propagate in the same direction as the tidal currents. The underlying current may affect the behaviour of oscillatory wave flow during the energy-damping process and the CD-KC relation. Yet, the CD-KC relation in combined current-wave flow has not been reported in previous studies. In order to fill the knowledge gap in the CD-KC relation, an experimental approach was adopted by using the laboratory flume to replicate such complicated hydrodynamics. The flume is 40m long and 0.8m wide, with a patch of rigid wooden cylinders as vegetation mimics installed over the entire channel width over a 6m long test section. Pure wave can be generated by the wave generator. The underlying current can be made by using a water circulation system in the flume. After the generation of underlying current, waves could be generated afterwards and propagate together with the underlying current in the flume. The velocity was measured using EMS within the vegetation patch. Direct measurement data of the force on individual rods within the array were collected by attchaching the rods to the force sensors and embedding them in the false bottom of the flume. Three densities of the vegetation mimics were investigated for two water depths in this study. The results of the experiments reveal a rise-and-fall variation trend of CD-KC for multiple vegetation mimics in pure wave. The rise-part occurs when KC is small, around KC=3 to 10 and this phenomenon could be phycisally explained based on the changes in vortexes shedding directions. In this range of KC, the vortexes motions would change its propagation direction from lateral to oblique and longitudally parallel with the incoming flow. It is the changes in vortexes directions that lead to the increase of flow resistance experienced by the cylinder. Beyond this range of KC, the vortexes motion would keep moving longitudinally parallel and behave much the same way as in steady current. Natuarally, similar to the behaviour found in steady current conditions, the values of CD would decrease gradually and converge to 1. In the combined current-wave flow conditions, it is necessary to make a distinction between oscillatory-dominated flow and unidirectional-dominated flow. For small underlying current applied in this study, the flow could be regarded as oscillatory-dominated. It is found that the similar rise-and-fall pattern of CD-KC relation occurs in this kind of combined flow. And the transition point of KC locates at around KC=10, which is also the case found in pure wave conditions. But the peak value of CD would decrease a little bit. However, for larger underlying current conditions, the combined flow is similar to pure current. Consequently, the peak values of CD would collapse. Thus, the values of CD obtained in these conditions are stable and close to 1. The experimental results suggest the vegetation density as well as the water depths has limited effects on the values of CD and its variation trend with KC. It is recommended to carry further investigation concerning the influence on CD caused by vegetation density (N) and relative vegetation height (?) in future studies. The product of this thesis is a general description and explaination for the variation trend of CD-KC in pure wave and combined current-wave flow conditions. Physically, more insights have been gained about the evolution of vortex shedding in different flow conditions, say from pure wave to combined current-wave flow conditions. Moreover, both the calibration approach (used by Mendez and Losada, 2004, etc.) and direct measurement method have been utilised for data processing. The direct measurement method is recommended to apply in all the complicated flow conditions. As to the calibration approach, it should not be applied to obtain CD values in combined current-wave flow.Hydraulic EngineeringHydraulic EngineeringCivil Engineering and Geoscience
Erosion-corrosion resistance of engineering materials in various test conditions
Full text linkErosion–corrosion is a complex phenomenon which involves the interaction between the mechanical processes of solid particle erosion and the electrochemical processes of corrosion. A whole range of issues is faced by a designer when trying to obtain relevant information on erosion–corrosion performance of a material. Amongst the constraints are the dispersed test conditions and test rigs available in the literature making comparisons and quantifying erosion–corrosion wear rates of different materials very difficult. The aim of this work is to evaluate the repeatability of erosion–corrosion experiments and to investigate the role of different parameters influencing erosion–corrosion. The materials tested in this work are stainless steel (SS316L/UNS S31603), carbon steel (AISI 1020/UNS G10200) and nickel-aluminium bronze (NAB/UNS C63200). A slurry pot erosion tester was used as the test apparatus and test parameters such as erodent size, erodent concentration, flow velocity and test solutions were varied to study their effect on erosion–corrosion. SEM analysis showed that a similar erosion–corrosion mechanism is seen for SS316L and NAB with formation of multiple extruded lips and platelets typically seen for erosion dominated material. In contrast the surface of AISI 1020 revealed the formation of craters, pits and shallow indentations which suggests that corrosion mechanism has a dominant influence on the material. Error rates in tests were found to have an average of 5.5% which are relatively low indicating good repeatability of test measurements and data from the test rig. The erosion–corrosion resistance of AISI 1020, SS316L and NAB were compared and it was found that SS316L showed the lowest erosion–corrosion mass loss rates in all test conditions followed by NAB and then AISI 1020. However in terms of synergistic ranking, NAB showed the best resistance to the combined action of erosion and corrosion with the highest negative synergy value. Positive synergy was evident for AISI 1020 in 3.5% NaCl and SS316L in 0.3 M HCl. A wear map is presented to evaluate erosion–corrosion trends of the materials. This work combines the assessment of test repeatability, variation in test conditions and comparison of material performance which are key stages in a material selection process
Quantitative evaluation of habitat requirements of fish communities by development of environment matrix
No full textLong-term spatial organization of understorey vegetation in boreal Pinus sylvestris stands with different fire histories
No full textWe examined the composition and spatial structure of the understorey vegetation at two sites with different fire histories in a mature Pinus sylvestris L. forest in eastern Finland. The entire study area had regenerated after a fire in the early 19th century. Besides, a part of the area was subsequently hit by a surface fire in 1906, which divided the study area into two parts. Vegetation and environmental variables measured from the these two parts, the 1800+ burn site and the 1906 burn site, have considerably different spatial pattern. Deciduous shrubs and ground layer, consisting primarily of bryophytes, had a more distinct patch structure at the 1800+ burn site than at the 1906 burn site, while with lichens the situation was the reverse. Cover of the field layer, dominated by evergreen shrubs, was significantly higher at the 1800+ burn site than at the 1906 burn site. At both sites, the spatial pattern of plant functional types was obviously strongly regulated by the spatial influence of living trees. Gradual formation of strong clonal patch structures of V. myrtillus, V. vitis-idaea and mosses, seems to be another important process affecting the properties of the understorey vegetation. The post-fire recovery of the understorey community was slow: in the 1906 burn site, the community composition and spatial structure were still in transition after almost 90 years since the last fire
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