Sharif Digital Repository

The phenomena of surface, interface, and size effects are the determinative factors in the prediction of the mechanical behavior of multiphase nanowires. The interatomic bond lengths and charge density distribution associated with the surface and interface layers of the relaxed configuration of such nanostructures, in the absence of any external loadings, differ from those of the bulk remarkably. Second strain gradient theory due to its competency in capturing the above mentioned effects will be employed to examine the relaxation of carbon-coated silicon nanowire, carbon nanoshell, and silicon nanowire. Using this theory their effective Young's modulus will also be estimated. To this end,... 

Reduction of stress concentrations in the area of pin-loaded holes is one of the greatest challenges in the design of multilayered fibre-reinforced composite structures. Among many approaches to decrease concentration effects, putting metallic inserts in the holes is a convenient method. In this research, finite element analysis is applied to assess the effects of manufacturing parameters on stress concentration in the vicinity of the holes in composite plates with inserts. Edge and pitch distance, thickness and materials of insert, clearance between insert and composite part, and stiffness of the adhesive filling the gap are studied in this article. Investigations show that the optimum... 

Increasing cuttings bed height is a serious concern during extended-reach well drilling. In order to predict and prevent cuttings bed height increase, it is essential to study how the critical parameters influence the cuttings transport, especially the drill pipe rotation effects on the cuttings transport process. In conventional models for cuttings transport, the dynamic behavior of particles due to drill pipe rotation is neglected or empirically simplified. This paper presents a coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) approach to simulate the cuttings transport considering the dynamic collision process. The fluid phase is treated as an Eulerian continuum... 

Application of the fiber contained fluids has been extensively increased in many industries. In the petroleum industry, fibrous fluids are utilized for different applications. For instance, they have been applied in drilling operations for hole cleaning and cutting removal. In this article, the results of the studies performed on the application of Hydrated Basil Seeds (HBS) as the herbal eco-friendly fiber on hole cleaning and filtration control were presented. In order to investigate the application of HBS on hole cleaning, Polyacrylamide (PA) was added to the pure water to provide the base fluid and HBS at different concentrations were suspended in the base fluid and the effect of HBS on... 

The effect of substitutional Li doping into NiOx hole transporting layer (HTL) for use in inverted perovskite solar cells was systematically studied. Li doped NiOx thin films with preferential crystal growth along the (111) plane were deposited using a simple solution-based process. Mott-Schottky analysis showed that hole carrier concentration (NA) is doubled by Li doping. Utilizing 4 % Li in NiOx improved the power conversion efficiency (PCE) of solar devices from 9.0 % to 12.6 %. Photoluminescence quenching investigations demonstrate better hole capturing properties of Li:NiOx compared to that of NiOx, leading to higher current densities by Li doping. The electrical conductivity of NiOx is...