Sharif Digital Repository

Constraints are presented on the total width of the recently discovered Higgs boson, ΓH, using its relative on-shell and off-shell production and decay rates to a pair of Z bosons, where one Z boson decays to an electron or muon pair, and the other to an electron, muon, or neutrino pair. The analysis is based on the data collected by the CMS experiment at the LHC in 2011 and 2012, corresponding to integrated luminosities of 5.1fb -1 at a center-of-mass energy s=7TeV and 19.7fb -1 at s=8TeV. A simultaneous maximum likelihood fit to the measured kinematic distributions near the resonance peak and above the Z-boson pair production threshold leads to an upper limit on the Higgs boson width of ΓH... 

We have compared the electrical and magnetic properties of Ru(Gd 1.5-x Pr x )Ce 0.5Sr 2Cu 2O 10-δ (Pr/Gd samples) with x = 0.0, 0.01, 0.03, 0.033, 0.035, 0.04, 0.05, 0.06, 0.1 and RuGd 1.5(Ce 0.5-x Pr x ) Sr 2 Cu 2O 10-δ (Pr/Ce samples) with x = 0.0, 0.01, 0.03, 0.05, 0.08, 0.1, 0.15, 0.2 prepared by the standard solid-state reaction technique. We obtained the XRD patterns for different samples with various x. The lattice parameters versus x for different substitutions have been obtained from Rietveld analysis. To determine how the magnetic and superconducting properties of these layered cuprate systems can be affected by Pr substitution, the resistivity, and magnetoresistivity, with H ext... 

In this study, the effect of graphene nanoplatelets (GNP)/distilled water nanofluid on the thermal performance of evacuated tube solar collector (ETSC) water heater was experimentally investigated. The mass percentage of GNP was considered at 0.025, 0.5, 0.075 and 0.1 wt%. The physical and thermal properties of the GNP nanofluids including stability, specific heat capacity, viscosity and thermal conductivity were investigated. The thermal efficiency tests on the solar collector were carried out for varying volumetric flow rate of 0.5, 0.1, and 1.5 L/min while the ASHRAE standard 93–2003 was considered to calculate the efficiency of the collector. The results indicated that the solar... 

Despite many efforts into the study of fluids interaction in low salinity water flooding, they are not probing the basics of transport phenomena between the involved phases. This work is aimed to bring new understanding of fluid–fluid interaction during low salinity water flooding through a series of organized experiments in which a crude oil sample with known properties was kept in contact with different brine solutions of various ionic strengths. Measuring brine pH, conductivity and crude oil viscosity and density for a period of 45 days illustrates the strong effect of the contact time and ionic strength on the dissociation of polar components and physical properties of the crude oil and... 

Despite many efforts into the study of fluids interaction in low salinity water flooding, they are not probing the basics of transport phenomena between the involved phases. This work is aimed to bring new understanding of fluid–fluid interaction during low salinity water flooding through a series of organized experiments in which a crude oil sample with known properties was kept in contact with different brine solutions of various ionic strengths. Measuring brine pH, conductivity and crude oil viscosity and density for a period of 45 days illustrates the strong effect of the contact time and ionic strength on the dissociation of polar components and physical properties of the crude oil and... 

Adsorption and desorption of methane by activated carbon (AC) at constant temperature and at various pressures were investigated. The effect of moisture was also studied. A volumetric method was used, up to 40 bar, at a temperature of 273.5 K. Results of a dry AC sample were compared with those obtained from a moist sample and two different ACs with different physical and surface properties were used. As expected, the results showed that the existence of moisture, trapped in the AC pores, could lead to a decrease in the amount of methane adsorbed and a decrease in the amount of methane delivered during desorption. To model the experimental results, a large variety of adsorption isotherms... 

In this research, we will use an accelerator for MD simulations, called Atomic Approximation Method, which leads to more efficient simulations without harming the physical properties in simulations. The main idea of this method is to define a virtual material with lower number of atoms, which has the same physical properties as the original material. To demonstrate the validity of the proposed technique the modal analysis results are compared with the ones of the conventional molecular dynamics method. It is shown that this method accelerates conventional MD simulations significantly. Copyright © 2006 by ASME  

Physical and hydraulic properties of new stainless steel spring packing are introduced. The measured hydraulic properties are: dry and wetted packed bed pressure drop, loading and flooding points and the liquid holdups. The appropriate coefficients for predicting the mentioned hydraulic properties from different correlations are also reported. Hydraulic properties for this packing are compared with available packings. In spite of small size, the dry and wetted packed bed pressure drops of spring packing are less than similar Raschig and Protruded rings. The total liquid holdup of this packing is greater than other commercial packings. The big total liquid holdup and physical surface area are... 

In this study, the local composition based models such as the Wilson, the nonrandom two-liquid (NRTL), and the Wilson-NRF have been applied in correlation and estimation of density, viscosity, and surface tension of biodiesels. The thermodynamic models have been used in correlating the thermophysical properties for 215 experimental data points. These models have the interaction energy between each pair that is considered as adjustable parameters. To decrease the number of these adjustable parameters, it is assumed that the biodiesels are composed of two hypothetical components. The average absolute deviation (AADs) of the correlated density of biodiesels for the Wilson, the NRTL, and the... 

Purpose: This paper aims to numerically study the compositional flow of two- and three-phase fluids in one-dimensional porous media and to make a comparison between several upwind and central numerical schemes. Design/methodology/approach: Implicit pressure explicit composition (IMPEC) procedure is used for discretization of governing equations. The pressure equation is solved implicitly, whereas the mass conservation equations are solved explicitly using different upwind (UPW) and central (CEN) numerical schemes. These include classical upwind (UPW-CLS), flux-based decomposition upwind (UPW-FLX), variable-based decomposition upwind (UPW-VAR), Roe’s upwind (UPW-ROE), local Lax–Friedrichs... 

Effect of sandblasting of the copper electrode structures before deposition of gold thin film for micro electrical impedance tomography (EIT) system has been studied experimentally. The comparison has been performed on the unmodified copper electrodes and the sandblasted electrodes before deposition of gold layer, using structural analysis while their performance in EIT system has been measured and analyzed. The results of scanning electron microscopy and atomic force microscopy show that the sandblasting of the electrodes results in the deposition of gold film with smaller grain size and uniformly, comparing to the unmodified structure. The measurement of impedance shows that the... 

In this paper, the effects of flame retardant fillers mixture, zinc borate and aluminum hydroxide, on polypropylene including various ratios of their accumulated concentrations, have been studied. Maleic anhydrate grafted polypropylene and calcium stearate have been used to increase filler-matrix interactions and filler dispersion in matrix. Effects of filler types and their concentrations on fire resistibility of different composite samples have been determined via limiting oxygen index test method. Effects of foregoing parameters on the mechanical properties of prepared samples were also investigated. Recorded data shows that adding polypropylene, containing aluminum anhydrate lump,... 

Naturally fractured reservoirs (NFRs) contribute in large extent to oil and gas production to the ever increasing market demand of fossil energy. It is believed that the vertical displacement of oil during gas injection assisted by gravity drainage (GAGD) is one of the most efficient methods for oil recovery in these reservoirs. Hence, in this work, unconsolidated packed models of cylindrical geometry surrounded by fracture were utilized in order to perform a series of flow visualization experiments during which the contribution of different parameters such as the extent of matrix permeability, physical properties of oil (viscosity, density, and surface tension) and the withdrawal rate was... 

In the present study, a prediction model was derived for the effective angle of shearing resistance (φ′) of soils using a novel hybrid method coupling genetic programming (GP) and orthogonal least squares algorithm (OLS). The proposed nonlinear model relates φ′ to the basic soil physical properties. A comprehensive experimental database of consolidated-drained triaxial tests was used to develop the model. Traditional GP and least square regression analyses were performed to benchmark the GP/OLS model against classical approaches. Validity of the model was verified using a part of laboratory data that were not involved in the calibration process. The statistical measures of correlation...