The research program involved both numerical and experimental work. The numerical analysis was conducted to simulate the static and dynamic behaviour of the 81 m meteorological FRP guyed tower under wind and ice loading. The FRP tower consisted of 16 segments each made of 3 cells connected together to form an equilateral triangle having equal sides of 450 mm. The segments were interconnected using internal sleeves. Various non-linear finite element models were developed to study a number of design parameters for the 81 m FRP tower such as, different laminates containing a variety of stacking sequences of laminate orientations with various thicknesses, different cable diameters, and appropriate guy cable spacing levels. The effect of pre-stressing the guy cables up to 10 % of their breaking strength was investigated. The effect of fibre volume fraction on the design of the FRP tower was also examined. Furthermore, an 8.6 m FRP tower segment was designed using the finite element analysis and subject to the same loading conditions experienced by the bottom section of the 81 m FRP tower. A modal analysis was carried out for both the 8.6 m FRP tower segment with and without a mass on the top as well as for the 81 m FRP guyed tower to evaluate the vibration performance of these towers. The experimental work involved extensive material testing to define the material properties for use in the analysis of the 81 m FRP tower. It also involved the design and fabrication of a special collapsible mandrel for fabricating the FRP cells for the 8.6 m tower segment. The 8.6 m tower was tested horizontally under static lateral loading to 80 % of its estimated failure load using a “whiffle tree” arrangement, in order to simulate a uniformly distributed wind loading. Later, the same FRP tower was erected in a vertical position and was tested with and without a mass on top under dynamic loading to obtain the natural frequencies. Lastly, a comparative study was conducted between two 81 m FRP towers having different fibre volume fractions and a steel tower having a circular cross section.

No description available.

The research program involved both numerical and experimental work. The numerical analysis was conducted to simulate the static and dynamic behaviour of the 81 m meteorological FRP guyed tower under wind and ice loading. The FRP tower consisted of 16 segments each made of 3 cells connected together to form an equilateral triangle having equal sides of 450 mm. The segments were interconnected using internal sleeves. Various non-linear finite element models were developed to study a number of design parameters for the 81 m FRP tower such as, different laminates containing a variety of stacking sequences of laminate orientations with various thicknesses, different cable diameters, and appropriate guy cable spacing levels. The effect of pre-stressing the guy cables up to 10 % of their breaking strength was investigated. The effect of fibre volume fraction on the design of the FRP tower was also examined. Furthermore, an 8.6 m FRP tower segment was designed using the finite element analysis and subject to the same loading conditions experienced by the bottom section of the 81 m FRP tower. A modal analysis was carried out for both the 8.6 m FRP tower segment with and without a mass on the top as well as for the 81 m FRP guyed tower to evaluate the vibration performance of these towers. The experimental work involved extensive material testing to define the material properties for use in the analysis of the 81 m FRP tower. It also involved the design and fabrication of a special collapsible mandrel for fabricating the FRP cells for the 8.6 m tower segment. The 8.6 m tower was tested horizontally under static lateral loading to 80 % of its estimated failure load using a “whiffle tree” arrangement, in order to simulate a uniformly distributed wind loading. Later, the same FRP tower was erected in a vertical position and was tested with and without a mass on top under dynamic loading to obtain the natural frequencies. Lastly, a comparative study was conducted between two 81 m FRP towers having different fibre volume fractions and a steel tower having a circular cross section.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

Thesis (M.Sc.)(Meteorology)--University of Pretoria, 2004. / Title from opening screen (viewed March 11th, 2005). Summaries in Afrikaans and English. Includes bibliographical references.

Thesis (M.S.)--Wisconsin. / Includes bibliographical references (leaves 87-88).

The main object of this thesis was to investigate the possibility of integrating a visualization of meteorological data in an interactive GIS-based simulation environment. The work was carried out at at the Swedish Defence Research Agency (FOI). Focus was put on meteorological parameters affecting radar signals. The task consisted of mapping of existing visualization methods used for weather and investigating suitable data sources and structures. Furthermore, the work was implemented in Java and NASA's API WorldWind. The result was evaluated through a semi-structured interview held with a focus group at FOI. The data chosen was model data describing precipitation rate from the European organization ECMWF's open database. A software module was developed to decode and structure the data which were later fetched and visually represented using symbols from the MIL-STD-2525 standard. The main conclusion drawn from the interview was that the proposed implementation was suitable for some scenarios. Alternative visualisations have to be developed from which the user will be able to choose from. The data module serves together with the symbols as a good start for further visualizaiton work.

<p> Soil moisture is at the centre of the water balance and is of great concern with regards to crop growth and yield, irrigation planning, fertilization, climate change and non-point source pollution control. Information on soil moisture is not widely available, resulting in researchers relying on mathematical models to gain insight into soil moisture conditions. This thesis primarily focuses on long-term soil moisture characteristics, under given climate, soil and vegetation conditions. Long-term soil moisture characteristics are best described by statistics such as average soil moisture, and its standard deviation and frequency/probability distribution. After an extensive review of existing explicit or implicit soil moisture models, a deterministic water balance model was developed to simulate soil moisture at a point within the root-zone. The hydrological processes involved in the water balance are modelled using well-established methods. The continuous simulation model is unique from other leading deterministic models as it introduces the ecohydrological perspective by modelling actual evapotranspiration as a function of plant access to soil moisture. The validation of the model demonstrates that simplified soil moisture modelling is rational and practical.</p> <p> Soil moisture modelling is dependent on various input parameters related to the climate, soil and vegetation. Both local and global sensitivity analyses were carried out to investigate which input parameters influence the soil moisture regime the most. The analyses concluded that parameters representing soil texture are most important and thereby indicated that evapotranspiration is the most dominant process as it is significantly controlled by these parameters. Due to concerns of the impact of climate change and urban stormwater management, a better understanding of urban area soil moisture dynamics is required. The applicability of the continuous simulation model was demonstrated by investigating the influence of global warming on long-term soil moisture and evapotranspiration. Statistical analyses carried out on the post-simulated long-term soil moisture values clearly showed that even though temperatures are increasing, soil moisture and evapotranspiration have also increased because of the overall increase in precipitation. This phenomenon gives insight into the precipitation characteristics being strong enough to overpower the soil moisture loss process of evapotranspiration. As a part of the overall research, an analysis on antecedent soil moisture values for the purpose of urban stormwater management was performed. Empirical equations were derived to obtain antecedent soil moisture values from soil characteristics. Antecedent soil moisture information is essential in the application of the design storm approach while designing urban stormwater management infrastructure.</p> <p> The main purpose for the development and use of the deterministic model was to better understand the statistics and sensitivity of soil moisture and not as a predictive tool.</p> / Thesis / Doctor of Philosophy (PhD)

<p> Simultaneous solar radiation and meteorological observations were taken from an instrumented tower located in southwestern Lake Ontario. During the four month period of this study (July-November, 1969) it was found that short-term fluxes of incoming global radiation could be predicted with a standard error which was better than 0.05 cal cm^-2min^-1 under cloudless conditions. Under cloudy conditions the lowest standard of prediction error (0.14 cal cm^-2min^-1) was obtained using a model which takes into account cloud type transmission. Under cloudless conditions the Fresnel curve underpredicts the albedos observed for low zenith angles and overpredicts when the zenith angle is high. This is mostly due to a backscatter effect estimated to be between 1.5 to 2% and to the albedo of diffuse radiation which was confirmed to be 6.5 to 7%.</p> / Thesis / Master of Science (MSc)

No description available.