Study of CuO Nano-particles/CuTl-1223 Superconductor Composite

Synthesis and characterization of (CuO) _x /Cu_0.5Tl_0.5Ba₂Ca₂Cu₃O_10?δ ; {(CuO) _x /CuTl-1223} composites with x=0 %, 10 %, 15 % and 20 % have been reported. The fluctuations induced conductivity (FIC) analysis of (CuO) _x /CuTl-1223 composite has been carried out using Aslamazov-Larkin (AL) and Lawrence-Doniach (LD) models in the temperature regime well above the critical temperature (T>T _c ). The electrical resistivity versus temperature curves of as-prepared and oxygen post-annealed (CuO) _x /CuTl-1223 composite were fitted by using above mentioned models to extract the microscopic parameters such as zero temperature coherence length along c-axis{ξ _c (0)}, inter-layer coupling (J), dimensional critical exponent (λ) and inter-grain coupling constant (α) etc. It has been observed that the cross-over temperature (T _o ) fits very well the two-dimensional (2D) and three-dimensional (3D) AL equations and shifts towards the lower temperature regime with the enhanced weight percentage of CuO nano-particles. The shifting of AL 3D region to higher temperature after oxygen post-annealing indicates the restoration of oxygen and optimization of charge carriers in conducting CuO₂ planes. The gradual decrease in the value of inter-grain coupling constant (α) with the increase of CuO nano-particles content reflects an improvement in the inter-grain coupling resulting into an increase in the coherence length (ξ _c ) along the c-axis. Almost all superconductivity parameters have been improved after oxygen post-annealing. The suppression of superconductivity parameters in the composite with x=20 % limits the optimum doping level of CuO nano-particles in (CuO) _x /CuTl-1223 composite.     

Fuzzy entropy based optimization of clusters for the segmentation of lungs in CT scanned images

In this paper, we have proposed a method for segmentation of lungs from Computed Tomography (CT)-scanned images using spatial Fuzzy C-Mean and morphological techniques known as Fuzzy Entropy and Morphology based Segmentation. To determine dynamic and adaptive optimal threshold, we have incorporated Fuzzy Entropy. We have proposed a novel histogram-based background removal operator. The proposed system is capable to perform fully automatic segmentation of CT Scan Lung images, based solely on information contained by the image itself. We have used different cluster validity functions to find out optimal number of clusters. The proposed system can be used as a basic building block for Computer-Aided Diagnosis. The technique was tested against the 25 datasets of different patients received from Aga Khan Medical University, Pakistan. The results confirm the validity of technique as well as enhanced performance.     

Impingement cooling of gas turbine components

Impingement cooling heat transfer data were obtained for test geometries relevant to full coverage gas turbine combustion chamber wall cooling with the full flame tube pressure loss across the impingement plate. An impingement hole pitch to diameter ratio (X/D) of between 10 and 13 is appropriate for this application and two test geometries within this range were studied. The impingement gap to hole diameter ratio (Z/D) was the main parameter studied together with the hole Reynolds number. A significant influence of Z/D on the heat transfer was found and a general correlation equation derived. Evidence of enhanced impingement heat transfer for Z/D less than unity was found.     

Synthesis and characterization of indium phosphide films prepared by co-evaporation technique

Polycrystalline indium phosphide films were successfully deposited on glass and Si substrates by co-evaporating indium and phosphorus from appropriate crucibles. Microstructural studies indicated the average crystallite size to be ∼78 nm. X-ray diffraction pattern indicated reflections from (111), (220) and (311) planes only. The surface roughness of the films was estimated to be 30 nm and the band gap as determined from the transmittance versus wavelength traces was found to be ∼1.42 eV. The PL spectrum measured at 300 K was dominated by a strong peak located ∼1.41 eV. The intensity of this peak increased significantly when recorded at lower (10 K) temperatures and shifted towards higher energy (∼1.54 eV). XPS studies indicated two peaks ∼444.5 eV and ∼451.9 eV, corresponding to peaks of 3d_5/2 and 3d_3/2 of In 3d core while the P 2p peak at ∼128.8 eV was assigned to only P in InP. Characteristics Raman peaks for InP at ∼303 cm⁻¹ (TO) and ∼342 cm⁻¹ (LO) were observed.     

Influence of chloride ions and hot weather on isolated rusting steel bar in concrete based on NDT and electro-chemical model evaluation

The most prominent durability concern for reinforced concrete (RC) structures is the corrosion of steel reinforcement in concrete. RC buildings exposed to chloride and high temperature environments like sea and deserts suffer from accelerated corrosion of rebars. The chloride attack and increase in the electro-chemical reaction rate of corrosion due to high temperature is a thermodynamic phenomenon influenced by several parameters and some of them are being neglected in the past research works. The purpose of this present paper is therefore, to model and verify by NDT the coupled effects of chloride and temperature on corrosion of reinforcement throughout the life of concrete buildings by incorporating realistic thermodynamic model evaluations and actual field condition NDT. The model evaluation has been accomplished by the use of concrete durability model as a computational platform on which the corrosion based reinforced concrete building performance and quality at early age and throughout the life of concrete structure is examined in both space and time domains under environmental actions of chloride and temperature. On this line, the thermodynamic modeling evaluation of concrete forms the fundamental core of the theoretical approach to achieve both the scientific knowledge and engineering simulations of altering materials. The NDT results for the effect of chloride and temperature on corrosion have been compared with the DuCOM electro-chemical thermodynamic corrosion model evaluation and are found to be in close agreement with each other.     

Desulfurization of Model Oil through Adsorption over Activated Charcoal and Bentonite Clay Composites

Adsorption of dibenzothiophene (DBT) from model oil was investigated using composites of pure activated charcoal and pure bentonite clay. DBT adsorption was carried out in batch mode experiments at laboratory scale, where the developed composite materials showed a synergistic effect in removal of DBT from the model oil in terms of improved surface acidity of the pure activated charcoal and mesoporous structure of the pure bentonite clay. Thermodynamics, kinetics, and optimization of various adsorption parameters were investigated. Kinetic analyses proved that DBT adsorption followed pseudo-second-order kinetics. To study the thermodynamics of the adsorption, different isotherm adsorption models were applied. The Langmuir isotherm best fitted to the adsorption data. Various thermodynamic parameters were evaluated, including Gibbs free energy, entropy, and enthalpy.     

Influence of carbon nanomaterials on the properties of cement and concrete

Results of investigations of the influence of an addition of carbon nanomaterials to a cement paste on its properties, the morphological characteristics of the cement-hydration products, and the structure and strength of the concrete obtained on the basis of this paste are presented.