Sharif Digital Repository

The recent work investigates the heat transfer attributes in the flow of engine oil which comprises of nano-particles such as Cu and TiO2. The performance of Copper and Titanium oxide is over looked in the flow of engine oil. The energy equation is amended by the features of thermal radiation, viscous dissipation, and heat generation. The mathematical model signifies the porosity, entropy generation and moving flat horizontal surface with the non-uniform stretching velocity. Quasi-linearization, which is a persuasive numerical technique to solve the complex coupled differential equations, is used to acquire the numerical solution of the problem. Flow and heat transfer aspects of Cu–TiO2 in... 

Pure tin oxide nanoparticles ware synthesized via Co-precipitation method. The as-synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS). X-ray diffraction shows that tetrahedral shaped nanoparticles of crystallite size 47.35nm were prepared successfully. The crystallinity was established due the reduction in distortion ratio and dislocation density. The value of strain showed that the nanoparticles fabricated were of high stability. The direct and indirect optical band gap of as-synthesized SnO2 nanoparticles were determined from the reflectance... 

X-ray photoemission spectroscopy (XPS) of Cu1-xTl xBa2Ca2Cu3O10-δ (Cu1-xTlx-1223) superconductors thin films is studied. These films were prepared by amorphous phase epitaxy method on the SrTiO 3 substrate. This compound has Cu1-xTlxBa 2O4-δ charge reservoir layer and three CuO 2 planes. The atoms in the CuO2 planes have strong covalent bonding, while the some of the atoms in Cu1-xTl xBa2O4-δ charge reservoir, such as oxygen (Oδ) have predominantly secondary bonding and could be removed from the unit cell. The deliberate or inadvertent removal of the oxygen from the unit cell may change the charge state of the constituent atoms in the charge reservoir layer. The charge state of the atoms in... 

The X-ray photoemission (XPS) measurements of Cu1-xTlxBa2Ca2 Cu3-yZnyO10-δ (y = 0, 2.65) superconductors have been performed and compared. These studies revealed that the charge state of thallium in the Cu0.5Tl0.5Ba2O4-δ charge reservoir layer in Zn doped samples is Tl1+, while it is a mix of Tl1+ and Tl2+ in Zn free samples. The binding energy of Ba atoms in the Zn doped samples is shifted to higher energy, which when considered along with the presence of Tl1+ suggested that it more efficiently directed the carriers to ZnO2 and CuO2 planes. The evidence of improved inter-plane coupling witnessed in X-ray diffraction is also confirmed by XPS measurements of Ca atoms in the Zn doped samples.... 

Alkalis, surfactants and/or polymers are usually injected in the injector wells so that the injection fluids can sweep through the reservoir and mobilize/recover more oil. However, the formation of stable emulsion due to the residual chemicals in the recovered crude oil poses problems in the primary separation process. This study focuses on the effect of Alkali-Surfactant-Polymer injection on creaming and coalescence of crude oil and water emulsion produced in the primary gravity separator. In addition, a model is developed in this work to predict the separation effectiveness of oil and water emulsion containing ASP. In this work, the effect of ASP on the stability and the separation of... 

Alkalis, surfactants and/or polymers are usually injected in the injector wells so that the injection fluids can sweep through the reservoir and mobilize/recover more oil. However, the formation of stable emulsion due to the residual chemicals in the recovered crude oil poses problems in the primary separation process. This study focuses on the effect of Alkali-Surfactant-Polymer injection on creaming and coalescence of crude oil and water emulsion produced in the primary gravity separator. In addition, a model is developed in this work to predict the separation effectiveness of oil and water emulsion containing ASP. In this work, the effect of ASP on the stability and the separation of... 

X-ray photo-emission spectroscopy (XPS) studies of Cu1-xTlxBa2Ca3Cu4 O12-y superconductor thin films have been carried out for understanding the mechanism of superconductivity and to find out the reasons for the increase of zero resistivity critical temperature Tc(R = 0) with post-annealing in a nitrogen atmosphere. It is observed from these studies that reduction of charge state of thallium is a source of doping of carriers to the CuO2 planes. The reduced charge state of thallium (i.e. Tl1+) promotes lower oxygen concentration in the charge reservoir layer, which possibly results in movement of electrons to the conducting CuO2 planes. The higher density of electrons in the CuO2 planes... 

Providing home hemodialysis (HHD) therapy is a complex process that not only requires the use of a complex technology but also involves a diverse group of stakeholders, and each stakeholder has their requirements and may not share a common interest. Bringing them together will require the alignment of their interests. A process management perspective can help to accomplish the alignment of their interests. To align their interests, it is crucial to identify interest groups and understand their interests. The main objective of this paper is to identify the stakeholders and represents their interests as a list of requirements in the HHD process. An extensive literature review has been carried... 

The features of heat transferral capability between metallic (Cu) and non-metallic (TiO2) nanoparticles suspended in the engine-oil (EO) third-grade base-liquid has been analysed under the influence of strong magnetic field. The numerical investigation of system of coupled differential equations for third-grade nanofluid flow model is accomplished via Quasi-linearization method (QLM). The stretching horizontal sheet is heated through convective heat process assuming the special effects of thermal radiation, joule heating, heat generation and viscous dissipation in the energy equation. The mass suction and slip velocity at the boundary of the sheet has been taken into account to enhance... 

This study focuses on a forward looking approach in which deep eutectic solvents (DESs), a new class of designer solvents, were impregnated into micro porous polyvinylidene fluoride (PVDF) membrane for the separation of CO2 from CH4. Three types of DESs were prepared by mixing and heating of hydrogen bond acceptor (choline chloride) with either malic acid, tartaric acid or oxalic acid as hydrogen bond donor. The Fourier transform infrared spectroscopy confirmed the hydrogen bond interactions in the resulting DES. Thermal gravimetric analysis (TGA) was used to evaluate the thermal stability of the prepared membranes. The DES based supported liquid membranes were investigated systematically to... 

The current study revealed the effectiveness of polypropylene (PP) fibers and cement to enhance the strength of black cotton soil. PP fibers and cement with different concentrations were mixed with black cotton soil. The strength of PP fiber and cement-based soil samples was measured in terms of unconfined compressive strength (UCS) and California Bearing ratio (CBR). Specimens for UCS and CBR tests were prepared at 2%, 4%, 6% and 8% of cement (by dry weight of soil) and seven percentages of polypropylene fibers i.e. 0.0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 0.6% (by dry weight of soil). Fourier transform infrared (FTIR) analysis confirmed the presence of polypropylene and cement contents in... 

The current study revealed the effectiveness of polypropylene (PP) fibers and cement to enhance the strength of black cotton soil. PP fibers and cement with different concentrations were mixed with black cotton soil. The strength of PP fiber and cement-based soil samples was measured in terms of unconfined compressive strength (UCS) and California Bearing ratio (CBR). Specimens for UCS and CBR tests were prepared at 2%, 4%, 6% and 8% of cement (by dry weight of soil) and seven percentages of polypropylene fibers i.e. 0.0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 0.6% (by dry weight of soil). Fourier transform infrared (FTIR) analysis confirmed the presence of polypropylene and cement contents in... 

NiZn nanoferrites doped with rare-earth cations having stoichiometric composition such as Ni0.5Zn0.5R0.02Fe1.98O4 (R = Tb, Pr, Ce, Gd, Y) were prepared by sol–gel technique. The same amount of Ni and Zn with constant ratio of different rare-earths ions were doped to investigate the variations in the properties. X-ray diffraction (XRD), Field emission electron microscope (FESEM), and vibrating sample magnetometer (VSM) were used to investigate the structure, morphology, and magnetic properties of rare-earth doped NiZn nanoferrites, respectively. X-ray density, bulk density, and porosity were also calculated. Phase, crystallite size, structure, d-spacing, lattice parameter, micro strain, and... 

NiZn nanoferrites doped with rare-earth cations having stoichiometric composition such as Ni0.5Zn0.5R0.02Fe1.98O4 (R = Tb, Pr, Ce, Gd, Y) were prepared by sol–gel technique. The same amount of Ni and Zn with constant ratio of different rare-earths ions were doped to investigate the variations in the properties. X-ray diffraction (XRD), Field emission electron microscope (FESEM), and vibrating sample magnetometer (VSM) were used to investigate the structure, morphology, and magnetic properties of rare-earth doped NiZn nanoferrites, respectively. X-ray density, bulk density, and porosity were also calculated. Phase, crystallite size, structure, d-spacing, lattice parameter, micro strain, and... 

The emerging trend of distribution generation with existing power system network leads uncertainty factor. To handle this uncertainty, it is a provocation for the power system control, planning, and operation engineers. Although there are numerous techniques to model and evaluate these uncertainties, but in this paper the integration of Copula theory with Improved Latin-hypercube Sampling (ILHS) are incorporated for Probabilistic load Flow (PLF) evaluation. In probabilistic research approaches, the dominant interest is to achieve appropriate modelling of input random variables and reduce the computational burden. To address the said problem, Copula theory is applied to execute the modelling... 

Novel PVA/PEG cross-linked membranes were prepared with (0–20 wt. %) of silica nanoparticles. The presence of both the polymers and additive was confirmed by FTIR analysis. The thermal properties of the membranes were analyzed by TGA and DSC analysis. The morphological and mechanical properties of the membranes were studied by SEM analysis and tensile testing, respectively. The gas permeation performances of the membranes were examined using state-of-the-art gas permeability cell. It was found that permeability of all the gases increased with the increase of silica loading, whereas ideal selectivity of carbon dioxide with respect to nitrogen and methane increased up to 10 wt. % loading and... 

Rare earth elements (REEs) are becoming significant due to their huge applications in many industries, large-scale mining and refining activities. Increasing usage of such metals pose negative environmental impacts. In this research ICP-MS has been used to analyze soil samples collected from former ex-mining areas in the depths of 0–20 cm, 21–40 cm, and 41–60 cm of residential, mining, natural, and industrial areas of Perak. Principal component analysis (PCA) revealed that soil samples taken from different mining, industrial, residential, and natural areas are separated into four clusters. It was observed that REEs were abundant in most of the samples from mining areas. Concentration of the... 

The dearth of efficient, robust, and economical electrocatalysts for water oxidation is dubiously the key obstacle for renewable energy devices, so synthesis of efficient, and cost-effective metal-based water oxidation catalysts is vital. Herein, Co3O4, Co9S8 catalysts and their heterostructure Co3O4/Co9S8 were synthesized and evaluated as water oxidation electrocatalysts. The characterization of Co3O4, Co9S8, and Co3O4/Co9S8 electrocatalysts was performed using Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques. The heterostructure Co3O4/Co9S8 (1.46 V) exhibited water oxidation electrocatalysis at extremely low onset potential compared to... 

Rare earths (REs) play a key role in distorting spinel structure by creating some defects at the lattice sites and make them suitable for magnetodielectric applications. In the present study, the nanoferrites of CuRE0.02Fe1.98O4, where REs = Y3+, Yb3+, Gd3+, were prepared using one step sol–gel method. The prepared samples are copper ferrite (CFO), yttrium doped copper ferrite (Y-CFO), ytterbium doped copper ferrite (Yb-CFO) and gadolinium doped copper ferrite (Gd-CFO), respectively. The single-phase structure of all the REs doped nanoferrites was determined by X-ray diffraction (XRD) analysis. The porosity, agglomerations and grain size of the REs doped copper ferrite were examined using... 

The bonding temperature is an important parameter for optimization of the Transient Liquid Phase (TLP) bonding process in order to achieve a sound joint with good mechanical properties. However, the bonding temperature used can also be restricted by the microstructural stability of the base metal. In this study, the effect of bonding temperature (1050-1200 °C) on the joint microstructure and mechanical properties was studied for TLP bonding of FSX-414 superalloy using MBF-80 interlayer with thickness of 50 μm. Increasing bonding temperature from 1050 to 1150 °C caused reduction in the time required for complete isothermal solidification in agreement with models based on the diffusion induced...