Sharif Digital Repository

The effect of the anomalous magnetic moment of quarks on thermodynamic properties of the chiral condensate is studied, using a two-flavor Nambu-Jona-Lasinio model at finite temperature T, chemical potential μ, and in the presence of a uniform magnetic field eB. To this purpose, the Schwinger linear-in-B ansatz for the anomalous magnetic moment of quarks is considered in terms of the nonperturbative Bohr magneton. In a two-dimensional flavor space, it leads to the correction TSch=κQeB in the energy dispersion relation of quarks. Here, Q is the quark charge matrix. We consider three different sets for κ, and numerically determine the dependence of the constituent quark mass on T,μ, and eB for... 

Utilizing an extended two-flavor Nambu-Jona Lasinio (NJL) model, we review some of the effects of external magnetic fields on two-flavor color superconducting phase (2SC) at moderate baryon densities in the QCD phase diagram. The effective action of the extended NJL model consists of two mass gaps as functions of three intensive quantities, the temperature, the quark chemical potential and the external magnetic field. The nonzero values of the mass gaps, chiral and diquark condensates, induce spontaneous chiral and color symmetry breaking, respectively, and as a result two different phases of quark matter appear. We find the transition curves between these phases as well as the critical... 

Using low power electronic devices for space applications to reduce the mass and energy consumption has lead to electromagnetic interference (EMI) problem. Electronic enclosures are used to shield electronic devices against EMI. In the past, electromagnetic shielding has been mainly the only criteria considered in electronic enclosure design. However, there are several structural and thermal requirements for selection of shielding materials which should also be taken into account. In this research work, three quantitative materials selection methods, i.e. Digital Logic (DL), Modified Digital Logic (MDL), and Z-transformation, are employed to select the best material from among a list of... 

A two-flavor color-superconducting Nambu-Jona-Lasinio model is introduced at finite temperature T, chemical potential μ, and in the presence of a constant magnetic field e∼B. The effect of (T,μ,e∼B) on the formation of chiral- and color-symmetry-breaking condensates is studied. The complete phase portrait of the model in T-μ, μ-e∼B, and T-e∼B phase spaces for various fixed e∼B, T, and μ is explored. A threshold magnetic field e∼Bt0.5GeV2 is found, above which the dynamics of the system are solely dominated by the lowest Landau level, and the effects of T and μ are partly compensated by e∼B  

The directional weak decay constants of neutral pions are determined at finite temperature T, chemical potential μ and in the presence of a constant magnetic field B. To do this, we first derive the energy dispersion relation of neutral pions from the corresponding effective action of a two-flavor, hot and magnetized Nambu–Jona-Lasinio model. Using this dispersion relation, including nontrivial directional refraction indices, we then generalize the partially conserved axial vector current relation of neutral pions and derive the Goldberger-Treiman as well as the Gell–Mann-Oakes-Renner relations consisting of the directional quark-pion coupling constant g(μ)qqπ0 and the weak decay constant... 

The color neutral two-flavor superconducting phase of cold and dense quark matter is studied in the presence of constant magnetic fields and at moderate baryon densities. In the first part of the paper, a two-flavor effective Nambu-Jona-Lasinio model consisting of a chiral symmetry breaking (χSB) mass gap σB, a color superconducting (CSC) mass gap ΔB and a color chemical potential μ8 is introduced in the presence of a rotated U(1) magnetic field B. To study the phenomenon of magnetic catalysis in the presence of strong magnetic fields, the gap equations corresponding to σB and ΔB, as well as μ8 are solved in the lowest Landau level approximation. In the second part of the paper, a detailed... 

Application of the existing materials selection methods is not much popular in space environment. This is in spite of involvement of the selection process in this field with a wide range of influential factors (e.g. conventional mechanical properties and over 21 space environmental effects). In this paper an introductory road map for employing systematic materials selection methods in the field by engaging the selection process with mechanical properties and only one of the space environmental factors is presented. Here, selected case studies, which are involved with outgassing phenomenon of materials in vacuum condition, highlight the incapability of some of the methods in dealing with such... 

The properties of noninteracting σ and π0 mesons are studied at finite temperature, chemical potential, and in the presence of a constant magnetic field. To do this, the energy dispersion relations of these particles, including nontrivial form factors, are derived using a derivative expansion of the effective action of a two-flavor, hot and magnetized Nambu-Jona-Lasinio model up to second order. The temperature dependence of the pole and screening masses as well as the directional refraction indices of magnetized neutral mesons are explored for fixed magnetic fields and chemical potentials. It is shown that, because of the explicit breaking of the Lorentz invariance by the magnetic field,... 

A cooperative supply chain seeks to coordinate its members to produce and distribute products along the chain, for minimum overall costs to satisfy customer demand. An integrated multi-period, multiple product and multiple stage supply chain is formulated using a flow networks framework. A Cooperative Supply Chain Optimizer (CSCO), as a central software entity taking advantage of Grid technology, connects and gathers necessary operational information from members of the corporate supply chain. The CSCO then guides supply chain members on ordering decisions, for a minimum overall cost of the entire supply chain, while continuously re-directing the members as new data becomes available. The... 

A mechanism for supply chain coordination models the entire supply chain with multiple members in four stages to satisfy customer demand with minimum total costs. Previous coordination mechanisms research applied restrictive assumptions on the number in the supply chain stages and members in each stage, disallowing a case of multi-product. Flow networks concept is proposes as a coordination mechanism for supply chains with multiple members, multiple stages and multi-products, where each product is composed of several basic components. A supply chain optimizer (SCO), actually an e-hub, gathers supply chain state information. After necessary computations, it informs members of the supply chain... 

Single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were synthesized in aqueous solutions containing FeCl2, FeCl3, FeSO4 and Fe2(SO4)3. The effects of iron charge and the counter ions on the formation of carbon nanotubes (CNTs) were investigated. Thermogravimetric (TG) analysis indicated that carbon multilayer structures including CNTs and multishell graphite particles were formed in deionized (DI) water without the iron precursor. SWCNTs were also synthesized in the presence of the iron ions. It was also found that the mole ratio of [Fe2+]/[Fe3+] in the solution has a significant influence on the purity of CNTs and the process yield. The highest yield was... 

Nowadays there are more than thirty maturity models in different knowledge areas. Maturity model is an area of interest that contributes organizations to find out where they are in a specific knowledge area and how to improve it. As Information Resource Management (IRM) is the concept that information is a major corporate resource and must be managed using the same basic principles used to manage other assets, assessment of the current IRM status and reveal the improvement points can play a critical role in developing an appropriate information structure in organizations. In this paper we proposed a framework for information resource management maturity model (IRM3) that includes ten best... 

This paper presents a new mechanism with unique and prominent features for a helical swimmer robot. "Double Helices Propulsion Mechanism" consists of two parallel helices with a single axis rotating in the same direction. The outer helix acts as the main propulsion component, and the inner helix, which is made of a Shape Memory Alloy (SMA), controls the forward velocity during swimming. This mechanism, by varying the geometrical parameters of its helical tail, can change the forward velocity of the helical swimmer robot that is required by its predefined missions. In order to study the effects of geometric parameters on the forward velocity in the single helical swimmer, a hydrodynamic model... 

Data Envelopment Analysis (DEA) is a method to measure the efficiency of a DMU (Decision Making Unit, e.g. school, public agencies and banks). One of the ways for determining rank of DMUs is efficient score of each DMU. An interesting research issues is to discriminate between efficient DMUs. In literatures, supper efficiency is an applicable method for ranking efficient DMUs. The main drawback of this method is an inability of this method to rank non-extreme efficient DMUs. Therefore, this issue reduces the usefulness of this method. In this paper we propose a new ranking system for non-extreme efficient DMUs (Decision Making Units) based upon the omission of DMUs from reference set of the... 

The purpose of this paper is to present a polynomial time algorithm which determines the lot sizes for purchase component in Material Requirement Planning (MRP) environments with deterministic time-phased demand with zero lead time. In this model, backlog is not permitted, the unit purchasing price is based on the all-units discount system and resale of the excess units is possible at the ordering time. The properties of an optimal order policy are argued and on the basis of them, a branch and bound algorithm is presented to construct an optimal sequence of order policies. In the proposed B&B algorithm, some useful fathoming rules have been proven to make the algorithm very efficient. By... 

Optimum materials selection is a very important task in design process of every product. There are various materials selection methods like Ashby's method or digital logic methods such as DL and MDL. In the present research work the Z-transformation method is proposed for scaling the material properties to overcome the shortcoming of MDL method. The results show that despite the simple scaling function used, the ranking procedure is as powerful as MDL method and even it is superior to MDL when it ranks the less important materials existing among a list of candidate materials  

In this study, the effects of pulse current parameters on corrosion resistance and mechanical properties of anodized coatings were evaluated. Hardness measurements, polarization and electrochemical impedance spectroscopy tests were employed to investigate the mechanical properties and corrosion behavior of these coatings. Also, field emission scanning electron microscopy (FE-SEM) was used to analyze the surface morphology and microstructure of the coatings. It was found that the properties of anodized coatings were dependent on various parameters, among which, time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were optimized. Analysis of Variance... 

Calculation of camera projection matrix, also called camera calibration, is an essential task in many computer vision and 3D data processing applications. Calculation of projection matrix using vanishing points and vanishing lines is well suited in the literature; where the intersection of parallel lines (in 3D Euclidean space) when projected on the camera image plane (by a perspective transformation) is called vanishing point and the intersection of two vanishing points (in the image plane) is called vanishing line. The aim of this paper is to propose a new formulation for easily computing the projection matrix based on three orthogonal vanishing points. It can also be used to calculate the...