Zugl.: Metz und Saarbrücken, Univ., Diss., 2006

No description available.

Thèse de doctorat : Langues et littératures étrangères : Allemand : Metz : 2006. / Thèse soutenue sur ensemble de travaux. Bibliogr. p. 377-410. Index des noms propres p. 411-416. Annexes.

Thesis (B.A.Hons. 1973) from the Dept. of History, University of Adelaide.

Thesis (B.A.(Hons.)) --University of Adelaide, Dept. of History, 1974.

Universiẗat, Diss.--Bonn, 2008.

Thesis (doctoral)--Utrecht.

Thesis (doctoral)--Utrecht.

In this study the dynamic induced velocity field of a model helicopter rotor - excited in collective and cyclic pitch at frequencies extending to 1.5 times the nominal shaft speed - is investigated using mainly hot-wire and laser Doppler anemometry. The dynamic induced velocities are found to vary significantly with radial station and frequency. For cyclic excitations, azimuthal variations are also observed. The results point to the dynamic induced flow being influenced by the distribution of shed vorticity in the wake and cannot be explained using simple momentum theory. Vertical variations of the measured inflow response are also observed, with phase changes possibly partly due to transmission type delays. At frequencies above shaft speed a change in character of the induced flow is seen and around shaft speed an increase in the general level of turbulence is found. The available data on the dynamic induced velocity field of a rotor under controlled excitation, are substantially extended. The measured induced flow response was compared to that predicted using the Pitt and Peters dynamic inflow model. In the 'collective' case good agreement was found, suggesting that the primary inflow model parameters such as the inflow gain and apparent mass are correct with some evidence that a higher order inflow representation might be desirable. A novel method is used to infer the aerodynamic hub loading, which could not be directly measured, from the blade flapping data. This is used to isolate the inflow response using the Pitt and Peters dynamic inflow model and the results are compared with experimental measurements. The method shows the Pitt and Peters dynamic inflow representation to be adequate in the 'collective' case. In the 'cyclic' case, the inferred hub loads were very sensitive to the blade model and hence conclusions for this case are limited. A literature survey and review of the Pitt and Peters dynamic inflow model are also given

Beginning in the late 1930s, fire exclusion has drastically altered the vegetation dynamics of the southern Appalachian Mountains. Extremely low fire frequency has allowed for more shade-tolerant species to invade once predominantly open forests and has made it almost impossible for fire-dependent species to establish on a site. One such species is the endangered Peters Mountain mallow (Iliamna corei Sherff.) located on Peters Mountain in The Nature Conservancy s Narrows Preserve in Giles County, Virginia. This paper focuses on the fire history and stand dynamics of Peters Mountain and how fire exclusion has altered the forest composition. The historic fire frequency and successional changes discovered here may provide an insight into management strategies for the mallow. Seventy-nine fire scarred cross-sections were taken and aged to determine fire history dates and frequencies. Three 50x20 meter plots were set up on opposing aspects: northwest and southeast. The aspects were chosen at the direction of The Nature Conservancy personnel. All trees within were identified, cored and aged to determine species composition and the establishment dates of all trees. Fire history analysis revealed a mean fire interval of 2.48 years, a Weibull median fire interval of 2.18 years and a 25 percent scarred class mean fire interval of 12.5 years. Stand dynamic results show that Quercus montana has established on Peters Mountain prior to fire exclusion and remains the dominate species on the landscape. An increased number of fire intolerant species (including Acer rubrum, Sassfras albidum, Nyssa sylvatica) have been establishing on Peters Mountain during the decades of decreased fire frequency, suggesting a shift in forest composition. Frequent fires are suggested for mallow management and oak forest maintenance.