Strömungsmechanik: Open Access

A one-dimensional MacCormack explicit finite difference model is developed for simulating hydraulics and bed changes in irrigation channels. The Saint-Venant equations describing unsteady flow in open channels and the continuity equation for the conservation of sediment mass are numerically solved. These equations are highly nonlinear and therefore do not have analytical solutions. For this purpose the MacCormack scheme is used. The scheme is second order accurate; it is a coupled solution as it is a two-step predictor corrector method. Model gives results in terms of bed level changes, flow depth and discharge provided physical boundaries of the system are valid for simulation time. Model execution and accuracy is very sensitive to time step and stability. The simulated results show a good agreement with previous studies in the downstream section, and can predict an average value of measured profile in the upstream section. The application of this model to Chashma Right Bank Canal in Pakistan and results of the model are compared with the published results gave very convincing result.

Doped oxide materials of 90% of TiO2 was doped with 10% of SnO2 that target has been deposited at a substrate temperature of 250°C for 1 hour by using DC Sputtering technique. The as synthesized target was TiO2-SnO2 was used to deposit on the glass substrates. The deposited oxide thin film was characterized for their structural, surface morphological, electrical and optical properties. X-ray diffraction is used for studying the nature and structure, scanning electron, atomic force microscopy and transmission electron microscopy are used to identify the surface morphology of the prepared films. The Van der Pauw technique is employed to measure electrical resistivity and Hall mobility of the film. Wide varieties of methods are available for measuring thin film thicknesses. Stylus profilometry will be helpful to find the thickness of the film, structural studies by X-ray, and micros structural analysis of the film.

Nanocrystalline materials such as Sn doped In2O3 Indium Tin Oxide (ITO) were prepared by the Combustion technique and characterized. Presence of electronic centers in Nanocrystalline ITO is observed from Raman studies and the same has been confirmed by photoluminescence studies. The oxidation properties of ITO were studied by X-ray Diffractmeter grain sizes are confirmed by structural studies. As against the expectation of oxide on individual Nano grains of In-Sn alloy, ITO Nano grains grew into faceted Nano grains on heat treatment in air and O2 atmosphere. The growth of ITO under O2 atmosphere showed pentagon symmetry. This Nanocrystalline ITO has been studied using Electron paramagnetic resonance (EPR) measurements. Structural studies by X-Ray Diffraction (XRD) showed the presence of dominant β phase with a minor quantity of α phase. In EPR, isotopic chemical shift peaks were observed and they are assigned to originate from the α, β phases of ITO and grain boundary component respectively. From this study, different atomic arrangements were identified in grain boundaries compared to the same within the grain in Nanocrystalline ITO. The atomic arrangement in the grain boundary seems to be somewhat different from regular periodic arrangement whereas inside the grain there is a good periodic arrangement of atoms. Above 5 mol%, Sn ions form correlated clusters, which lead to broadening. These EPR spectra were formed to contain two different components, one from the single isolated ions and the other from the clusters.