An investigation of solubility and diffusion of oxygen in refractory metals Quarterly report, Jan. - Mar. 1966

Solubility and diffusion of oxygen in refractory metals measured by electrical resistivit

Solubility and diffusion of oxygen in tantalum

Solubility of oxygen in tantalum determined by resistivity techniqu

Multivariate analysis of nonlinearity in sandbar behavior

International audienceAlongshore sandbars are often present in the nearshore zones of storm-dominated micro- to mesotidal coasts. Sandbar migration is the result of a large number of small-scale physical processes that are generated by the incoming waves and the interaction between the wave-generated processes and the morphology. The presence of nonlinearity in a sandbar system is an important factor determining its predictability. However, not all nonlinearities in the underlying system are equally expressed in the time-series of sandbar observations. Detecting the presence of nonlinearity in sandbar data is complicated by the dependence of sandbar migration on the external wave forcings. Here, a method for detecting nonlinearity in multivariate time-series data is introduced that can reveal the nonlinear nature of the dependencies between system state and forcing variables. First, this method is applied to four synthetic datasets to demonstrate its ability to qualify nonlinearity for all possible combinations of linear and nonlinear relations between two variables. Next, the method is applied to three sandbar datasets consisting of daily-observed cross-shore sandbar positions and hydrodynamic forcings, spanning between 5 and 9 years. Our analysis reveals the presence of nonlinearity in the time-series of sandbar and wave data, and the relative importance of nonlinearity for each variable. The relation between the results of each sandbar case and patterns in bar behavior are discussed, together with the effects of noise. The small effect of nonlinearity implies that long-term prediction of sandbar positions based on wave forcings might not require sophisticated nonlinear models

Investigation of solubility and diffusion of oxygen in refractory metals Second quarterly report, 1 Oct. - 31 Dec. 1965

Electric resistivity measurements to determine solubility and diffusion of oxygen in tantalum, columbium, and alloy

An investigation of solubility and diffusion of oxygen in refractory metals First quarterly report, 1 Jul. - 30 Sep. 1965

Determination of solubility limits and diffusion constants of oxygen in pure tantalum and niobium and in alloys by electrical resistivity measurement