Laboratory scale experiments with water surface waves

The thesis presents the development, implementation and results of two series of experiments, at large and small scale, for the study of surface gravity waves. A number of measurement techniques are developed and implemented to capture space and time evolution of waves on a water surface in gravity, gravity-capillary and capillary ranges with the purpose to study the statistics of wave turbulence in terms of frequency and wave number spectra.The first series of experiments was conducted in a large wave tank of size 12 m x 6 m x 1.6 m filled with water to a depth of 0.9 m. A wave maker comprised of eight panels is controlled by a computer to generate waves at typically two frequencies; these waves are directed at different angles. Surface elevation of the resulting turbulent wave field is measured via capacitance wire probes and a fluorescent laser technique that is capable of capturing wave profiles at sufficient frame rate to access both wavenumber and frequency statistics. Following the processing of these data a comprehensive set of results describe characteristics of the life cycle of the experiment including the rise of the wave field to its statistically stationary state and the decay of the regime after energy pumped into the system from the wave maker has ceased.The first series of experiments was conducted in a large wave tank of size 12 m x 6 m x 1.6 m filled with water to a depth of 0.9 m. A wave maker comprised of eight panels is controlled by a computer to generate waves at typically two frequencies; these waves are directed at different angles. Surface elevation of the resulting turbulent wave field is measured via capacitance wire probes and a fluorescent laser technique that is capable of capturing wave profiles at sufficient frame rate to access both wavenumber and frequency statistics. Following the processing of these data a comprehensive set of results describe characteristics of the life cycle of the experiment including the rise of the wave field to its statistically stationary state and the decay of the regime after energy pumped into the system from the wave maker has ceased.Across both series of experiments the implementation of data acquisition techniques forms a significant contribution to the work undertaken and a comprehensive set of tools for measurement and analysis of data from surface waves is developed

Advanced solar concentrator mass production, operation, and maintenance cost assessment

The object of this assessment was to estimate the costs of the preliminary design at: production rates of 100 to 1,000,000 concentrators per year; concentrators per aperture diameters of 5, 10, 11, and 15 meters; and various receiver/power conversion package weights. The design of the cellular glass substrate Advanced Solar Concentrator is presented. The concentrator is an 11 meter diameter, two axis tracking, parabolic dish solar concentrator. The reflective surface of this design consists of inner and outer groups of mirror glass/cellular glass gores

Study on the neuronal circuits implicated in postural tremor and hypokinesia

The effect of various tegmentary lesions at the level of the pontomesenchphalon in monkeys on motor function was observed. The importance of the monoaminergic mechanisms of the brainstem is discussed. The results also show the importance of the descending tegmentary rubral system and the rubroolivocerebellar circuit in controlling peripheral motor activity. The destruction of the sensory motor cortex proves to be a more effective way of eliminating spontaneous or harmaline induced tremor than the complete interruption of the pyramidal system on the level of the cerebral peduncle

Predictive mapping of saline wetland soils in the Canadian prairie pothole region through landscape analysis

Non-Peer Reviewe

Rapid surface-water volume estimations in beaver ponds

Beaver ponds are surface-water features that are transient through space and time. Such qualities complicate the inclusion of beaver ponds in local and regional water balances, and in hydrological models, as reliable estimates of surface-water storage are difficult to acquire without time- and labour-intensive topographic surveys. A simpler approach to overcome this challenge is needed, given the abundance of the beaver ponds in North America, Eurasia, and southern South America. We investigated whether simple morphometric characteristics derived from readily available aerial imagery or quickly measured field attributes of beaver ponds can be used to approximate surface-water storage among the range of environmental settings in which beaver ponds are found. Studied were a total of 40 beaver ponds from four different sites in North and South America. The simplified volume–area–depth (V–A–h) approach, originally developed for prairie potholes, was tested. With only two measurements of pond depth and corresponding surface area, this method estimated surface-water storage in beaver ponds within 5%on average. Beaver pond morphometry was characterized by a median basin coefficient of 0.91, and dam length and pond surface area were strongly correlated with beaver pond storage capacity, regardless of geographic setting. These attributes provide a means for coarsely estimating surface-water storage capacity in beaver ponds. Overall, this research demonstrates that reliable estimates of surface-water storage in beaver ponds only requires simple measurements derived from aerial imagery and/or brief visits to the field. Future research efforts should be directed at incorporating these simple methods into both broader beaver-related tools and catchment-scale hydrological models

Does the 1/f frequency-scaling of brain signals reflect self-organized critical states?

Many complex systems display self-organized critical states characterized by 1/f frequency scaling of power spectra. Global variables such as the electroencephalogram, scale as 1/f, which could be the sign of self-organized critical states in neuronal activity. By analyzing simultaneous recordings of global and neuronal activities, we confirm the 1/f scaling of global variables for selected frequency bands, but show that neuronal activity is not consistent with critical states. We propose a model of 1/f scaling which does not rely on critical states, and which is testable experimentally.Comment: 3 figures, 6 page

Real-time phase-shift detection of the surface plasmon resonance

We investigate a method to directly measure the phase of a laser beam reflected from a metallic film after excitation of surface plasmon polaritons. This method permits real time access to the phase information, it increases the possible speed of data acquisition, and it may thus prove useful for increasing the sensitivity of surface plasmon based sensors

Contribution of ephemeral wetlands to annual nitrous oxide flux from an agricultural landscape

Non-Peer ReviewedMeasurement of soil nitrous oxide emissions from soil in the Canadian Prairie Region rarely includes uncultivated ephemeral wetlands (UW) within agricultural landscapes. Accurate inventories and a better understanding spatial and temporal variability for soil N2O in agricultural terrains requires flux measurements from non-agricultural areas of the field. The purpose of this study was to measure soil nitrous oxide flux from an agricultural landscape that includes UW. Measurements were taken weekly and bi-weekly from July to October of 2003 and from March to October of 2004 and 2005. Cumulative emissions were highest from concave elements (cultivated ephemeral wetlands) (CV) elements in 2003 and 2004 and highest from the basin centers (BC) of UW in 2005. High flux events were associated with rainfall in 2003, and the recession of standing water at CV and BC elements in 2004 and 2005. However, there are differences between ephemeral wetlands in their emission response to water recession. Accounting for aerial extent of landscape units reveals that CV elements make greatest contribution to total yearly flux. Beneficial management practices intended to reduce annual emissions from this site should be designed to reduce emission from CV elements and UW should not be cleared for crop production. Sampling designs for measurement of emissions from UW need not distinguish between riparian grass and riparian tree elements within the UW

Saskatchewan Soil Information System (SKSIS)-The Launch!

Non-Peer Reviewe