Effect of alumina-formers addition on the isothermal oxidation of TI-AL based intermetallics

The main objective of this study is to investigate the effect of adding the alumina former elements on the isothermal oxidation behavior of Ti-Al based intermetallics. High temperature oxidation test was carried out on Ti-Al based intermetallics namely the Ti-48Al-0.5Ag, Ti-48Al-2Cr-1.5Ag and Ti-48Al-2Cr- 1.5Ag-0.5W oxidized isothermally at 900°C. The kinetic rates of oxidation for the intermetallics were near to parabolic and the addition of Chromium (Cr) increased the kinetic rate of oxidation. Examination on the surfaces of oxide scales by using the Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM) and the X-ray Diffraction (XRD), revealed that the phases formed on the scale surfaces were dependent on the composition of the base alloy and the kinetic rates of oxidation. Analysis of the scale cross section found that the adherence of the scale to the base alloy improved by the addition of the alumina former elements. Based on the Energy Dispersive X-ray (EDX) spot and line scan analysis performed on the cross sectional of the scale, all the intermetallics showed an Al-depleted zone and the formation of aluminum oxide in the scale even at the early stage of the scale development. This indicated that the outward diffusion of aluminum to form Al2O3 is promoted by the addition of alumina former elements. Microhardness-indentation results revealed that the hardness values were different across the cross section of the scale. The hardness was the highest in the scale due to the presence of high TiO2 content

Economic Growth Nonlinearities

Nonlinearities in growth have important implications for cross-country income inequality. In particular, they imply that countries may spend long periods of time in a low-growth poverty trap. However, finding evidence of such nonlinearities in the data and accounting for their emergence pose unique challenges to researchers.

Statistical Properties of Convex Clustering

In this manuscript, we study the statistical properties of convex clustering. We establish that convex clustering is closely related to single linkage hierarchical clustering and $k$-means clustering. In addition, we derive the range of tuning parameter for convex clustering that yields a non-trivial solution. We also provide an unbiased estimate of the degrees of freedom, and provide a finite sample bound for the prediction error for convex clustering. We compare convex clustering to some traditional clustering methods in simulation studies.Comment: 20 pages, 5 figure

The Epsilon-Expansion from Conformal Field Theory

Conformal multiplets of $\phi$ and $\phi^3$ recombine at the Wilson-Fisher fixed point, as a consequence of the equations of motion. Using this fact and other constraints from conformal symmetry, we reproduce the lowest nontrivial order results for the anomalous dimensions of operators, without any input from perturbation theory.Comment: 24 pages; v2 - references added, minor changes; v3 - refs and comments added, misprints corrected, version to appear in J.Phys.

Qualitative Analysis of Growth Parameters for PECVD Based Low Temperature Synthesis of Graphene Using Design of Experiments

Determination of key factors and parameters is necessary to design any process when number of factors are large. Design of Experiments technique is an important statistical tool to serve the purpose. This work demonstrates a method to perform qualitative analysis in order to determine cardinal control factors for Graphene growth at low temperature values using Fractional Factorial design. Graphene is synthesized using Plasma Enhanced Chemical Vapor Deposition (PECVD) method in this work. Attribute Response Analysis suggests that Graphene growth temperature, deposition time and RF power are important controlling factors. This is verified by Graphene growth using the predicted recipe

Stabilization Of Thickened-Activated Sludge Through The Anoxic-Aerobic Digestion Process

Aerobic digestion is widely used to treat waste-activated sludge and thickened sludge from wastewater treatment plant due to its shorter retention time and achieving the same efficiency in solids volume reduction compared to anaerobic digestion. However, the supernatant and filtrate from the aerobic digestion system contain high concentration of suspended solids. The nitrogen which had been embedded in sludge is solubilized to form ammonical and nitric nitrogen which in tum transferred to the liquor and cause the increase of nitrogen loading in sewage treatment plant. In this study, anoxic-aerobic digestion is applied to remove both the mixed-liquor volatile suspended solids (ML VSS) and soluble nitrogen simultaneously. The objectives of the study are to investigate and evaluate the removal efficiency of both ML VSS and soluble nitrogen by anoxic-aerobic digestion and compared to the aerobic control digesters, with and without lime control. By applying anoxic-aerobic digestion, a comparable of ML VSS reduction was gained to aerobic digestion. 66.12% and 63.00% of MLVSS destruction was found in both anoxic-aerobic digesters, with and without methanol addition respectively