Sharif Digital Repository

Acidizing is one of the widely used practices of formation damage remediation. The success of this rather expensive job depends on the precise design and operation. Though, improper execution of an acid job, not only does not improve the formation damage but also can contribute to even more damage itself. For this purpose, it is critically important to thoroughly design an acidizing job conducting extensive lab experiments and utilizing numerical tools before operation in order for a successful acidizing. Unlike, carbonate acidizing, the chemistry of sandstone acidizing is very complex and challenging because of the wide variety of minerals and aqueous species present in the system. Hence, a... 

We consider a special class of Congestion Games enhanced with a notion of time.Network Routing problems, such as road traffic networks, computer neworks, and evacuation problems are some applications of this class of games. Two subclasses of these games, namely atomic and non-atomic is considered in this article, both of them introduced in 2009. Some of the existing results are Nash equilibria existence proof for “single-source single-sink” case, and a mechanism for improving price of anarchy in the non-atomic subclass. There are also some results in the atomic subclass of this game.We extend both models of atomic and non-atomic subclasses to “multi-source,multi-sink” configurations. We call... 

In the framework of the Standard Model of Particle Physics, Quantum Chromodynamics (QCD) is known to be the only theory which describes the strong nuclear force. Because of the property of asymptotic freedom, perturbative methods fail to describe QCD at low energies. Here, mesons and baryons build the main degrees of freedom of QCD. To describe the dynamics of mesons at low energies, nonperturbative methods are used. The Nambu–Jona-Lasinio (NJL) model is one of the most important effective models, which is used to study the nonperturbative phenomena of QCD at low energies. The Lagrangian density of this model includes a local four-fermion term,which descibes the interaction between the... 

Quantum Chromodynamics (QCD) is the theory of strong interaction. Two main properties of QCD in low energies are chiral symmetry breaking and confinement. At finite temperature, QCD exhibits a certain transition from a chirally broken phase to a chirally restored phase and liberation of color charge. Lattice QCD at finite temperature shows a crossover transition at vanishing or small chemical potential while the model-dependent studies, e.g. the Nambu-Jona--Lasinio model predicts a first-order phase transition at large chemical potentials. The first order and crossover transition lead to the existence of a critical point in the phase diagram of QCD. Determining the nature of the phase... 

Simultaneous planning of project scheduling and material procurement can improve the project execution costs. Hence, the issue considering this approach that each activities requirement can be distributed on the duration of it, has been addressed here by a mixed-integer programming model (named model 2). The proposed model facilitates the procurement decisions by accounting for a number of suppliers offering a distinctive discount formula from which to purchase the required materials. This paper proposed a genetic algorithm combining with a heuristic method to deal with the problem. The underlying factors of the solution methods are calibrated by the Taguchi method to obtain robust... 

Polyampholyte hydrogels are hydrophilic networks that contain both positively- and negatively-charged functional groups on their structure. Polysulfobetaines are the most important type of polyampholytes, which have been extensively studied. However, these hydrogels exhibited poor gel strength causing limitation of their applications. Consequently, much attention has been focused on the preparation of nanocomposite hydrogels with high gel strength and lower cost using organomodified clays. In this project, Novel polyampholytic superabsorbing nanocomposites based on the zwitterionic sulfobetaine monomer [3-(methacrylamido)propyl)]dimethyl(3-sulfopropyl) ammonium hydroxide (MPDSAH) were... 

The necessity of electrical energy, high cost of big power plants and high voltage transmission lines and also progressing of restructuring science has lead to the increasing of tendency to use the distributed generation in electrical industry. Among of different types of distributed generations, fuel cell power plants because of many advantages such as high efficiency, low emission, modular structure and ect., have a high potential to be used in power systems. The fuel cells produce electrical energy by chemical reactions. Due to the necessity of having the knowledge related to the chemical reaction which are effective on fuel cell, to study the fuel cell performance, this type of... 

High resolution and low power analog to digital converters are used in wireless communication receivers, Sensor Networks and Medical Instrumentations. Reducing power consumption at a high conversion rate is one of the most basic challenges for these converters. Pipelined SAR structure is considered for 40-50 MS/s and 10-12 bits, and is of interest because of consuming low power and using a small area. Besides using Pipelined SAR structure, circuit level and system level modifications are also proposed to decrease the power consumption. The ADC is designed in 0.18µm CMOS technology with 1.2v supply voltage. The results show 4.5mW power consumption, when ENOB is 11.04bit, which is very low...