An investigation on texture property correlation in annealed CP-Titanium

Rapid industrial development and advances in the fields of engineering and related technologies during the last five decades have led to the extensive use of traditional metals and their alloy counterparts. Ti is one such metal which has gained popularity in the aerospace and defence related applications due to its wide range of mechanical properties like excellent specific strength , stiffness, corrosion and erosion resistance, fracture toughness and capability to withstand significant temperature variations. The present investigation is a step at correlating the crystallographic orientation and mechanical properties of commercially pure Ti (CP-Ti). Annealed CP-Ti specimens were prepared along the rolling direction, perpendicular to the rolling direction and 45o to the rolling direction. The specimens were then deformed to failure under uniaxial tension test in tensile test. Crystallographic textures of the specimens were measured before and after tensile deformation. Correlation of texture and mechanical properties was investigated. Subsequently, hardness of different grains/orientations of CP-Ti was measured through nano-indentation, grain average misorientation, elastic stiffness and Taylor factor measurement

Non-equilibrium inelastic electronic transport: Polarization effects and vertex corrections to the self-consistent Born approximation

We study the effect of electron-vibron interactions on the inelastic transport properties of single-molecule nanojunctions. We use the non-equilibrium Green's functions technique and a model Hamiltonian to calculate the effects of second-order diagrams (double-exchange DX and dressed-phonon DPH diagrams) on the electron-vibration interaction and consider their effects across the full range of parameter space. The DX diagram, corresponding to a vertex correction, introduces an effective dynamical renormalization of the electron-vibron coupling in both the purely inelastic and the inelastic-resonant features of the IETS. The purely inelastic features correspond to an applied bias around the energy of a vibron, while the inelastic-resonant features correspond to peaks (resonance) in the conductance. The DPH diagram affects only the inelastic resonant features. We also discuss the circumstances in which the second-order diagrams may be approximated in the study of more complex model systems.Comment: To be published in PR

Web Usage Mining: An Implementation

Web usage mining is the area of data mining which deals with the discovery and analysis of usage patterns from Web data, specifically web logs, in order to improve web based applications. Web usage mining consists of three phases, preprocessing, pattern discovery,and pattern analysis. After the completion of these three phases the user can find the required usage patterns and use these information for the specific needs. In this project, the DSpace log files have been preprocessed to convert the data stored in them into a structured format. Thereafter, the general procedures for bot-removal and session-identification from a web log file, have been written down with certain modifications pertaining to the DSpace log files, in an algorithmic form. Furthermore, analysis of these log files using a subjective interpretation of a recently proposed algorithm EIN-WUM has also been conducted. This algorithm is based on the artificial immune system model and uses this model to learn and extract information present in the web data i.e server logs. This algorithm has been duly modified according to DSpace@NITR Website structure

Growth of Oriented Au Nanostructures: Role of Oxide at the Interface

We report on the formation of oriented gold nano structures on Si(100) substrate by annealing procedures in low vacuum (\approx10-2 mbar) and at high temperature (\approx 975^{\circ} C). Various thicknesses of gold films have been deposited with SiOx (using high vacuum thermal evaporation) and without SiOx (using molecular beam epitaxy) at the interface on Si(100). Electron microscopy measurements were performed to determine the morphology, orientation of the structures and the nature of oxide layer. Interfacial oxide layer, low vacuum and high temperature annealing conditions are found to be necessary to grow oriented gold structures. These gold structures can be transferred by simple scratching method.Comment: 13 pages, 3 figures, Accepted in J. Appl. Phy

Effect of simultaneous application of field and pressure on magnetic transitions in La0.5{_{0.5}}Ca0.5{_{0.5}}MnO3{_{3}}

We study combined effect of hydrostatic pressure and magnetic field on the magnetization of La${_{0.5}}$Ca${_{0.5}}$MnO${_{3}}$. We do not observe any significant effect of pressure on the paramagnetic to ferromagnetic transition. However, pressure asymmetrically affects the thermal hysteresis across the ferro-antiferromagnetic first-order transition, which has strong field dependence. Though the supercooling (T*) and superheating (T**) temperatures decrease and the value of magnetization at 5K (M$_{5K}$) increases with pressure, T* and M$_{5K}$ shows abrupt changes in tiny pressure of 0.68kbar. These anomalies enhance with field. In 7Tesla field, transition to antiferromagnetic phase disappears in 0.68kbar and M$_{5K}$ show significant increase. Thereafter, increase in pressure up to $\sim$10kbar has no noticeable effect on the magnetization

Effect of Helical Winding Angle on External Pressure based Buckling of Partially Filled Thin Composite Cylindrical Shells

Effect of helical winding angle on buckling load of thin composite tubes is investigated in this work.  Experiments are conducted on both empty and partially filled S2 glass tubes to estimate contribution of strength to the tubes by the filler material.  Chosen filler material mechanically simulates behavior of typical solid propellant used in aerospace application.   FE analysis with non-linear effect correlates well with the experimental data.  Three series of experiments are conducted to quantify effect of helical winding angle and increase in volumetric loading fraction(VLF).  Results confirm appreciable improvement in strength of filled tubes for higher VLF.  For the chosen pattern of winding, lower winding angle provides more strength to the tubes against external pressure buckling.  &nbsp

Mechanisms for electron transport in atomic-scale one-dimensional wires: soliton and polaron effects

We study one-electron tunneling through atomic-scale one-dimensional wires in the presence of coherent electron-phonon (e-ph) coupling. We use a full quantum model for the e-ph interaction within the wire with open boundary conditions. We illustrate the mechanisms of transport in the context of molecular wires subject to boundary conditions imposing the presence of a soliton defect in the molecule. Competition between polarons and solitons in the coherent transport is examined. The transport mechanisms proposed are generally applicable to other one-dimensional nanoscale systems with strong e-ph coupling.Comment: 7 pages, 4 figures, accepted for publication in Europhys. Let