Sharif Digital Repository

Understanding the fresh groundwater lens (FGL) behavior and potential threat of climatic-induced seawater intrusion (SWI) are significant for the future water resources management of many small islands. In this paper, the FGL of Kish Island, an arid-region case in the Persian Gulf, Iran, is modeled using two-dimensional (2D) and three-dimensional (3D) simulations. These simulations are based on the application of SUTRA, a density-dependent groundwater numerical model. Also, the numerical model parameters are calibrated using PEST, an automated parameter estimation code. Firstly a detailed conceptualization of the FGL model is completed to understand the sensitivity of the FGL to some... 

An effect-directed analysis (EDA) of fresh and artificially weathered (evaporated, photooxidized) samples of North Sea crude oil and residual heavy fuel oil is presented. Aliphatic, aromatic, and polar oil fractions were tested for the presence of aryl hydrocarbon receptor (AhR) agonist and androgen receptor (AR) antagonist, demonstrating for the first time the AR antagonist effects in the aromatic and, to a lesser extent, polar fractions. An extension of the typical EDA strategy to include an N-way partial least-squares (N-PLS) model capable of relating the comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS) data set to the bioassay data... 

To quantify the core barrel motion (CBM) in a pressurized water reactor, a scaling factor can be calculated to convert the Root Mean Square (RMS) value of the ex-core signals (%) to the core barrel motion amplitude (mil) (Thompson et al., 1980). In the current paper, a scaling factor is calculated using the direct and adjoint methods for a typical VVER-1000 reactor. The scaling factor is calculated using the perturbed parameters that result from CBM. The results show that the calculated scaling factors are not the same in one and two-dimensional modeling, and strongly depend on the ex-core detector location. The linearity assumption of relative detector response versus the small displacement... 

Rapid growth of digital music data in the Internet during the recent years has led to increase of user demands for search based on different types of meta data. One kind of meta data that we focused in this paper is the emotion or mood of music. Music emotion recognition is a prevalent research topic today. We collected a database including 280 pieces of popular music with four basic emotions of Thayer's two Dimensional model. We used a two level classifier the process of which could be briefly summarized in three steps: 1) Extracting most suitable features from pieces of music in the database to describe each music song; 2) Applying feature selection approaches to decrease correlations... 

A twodimensional model, based on conservation of mass, momentum and energy equations, is represented in this paper in which the coke combustion process, for iron ore sintering in a packed bed, is simulated numerically. The aforementioned packed bed consists of iron ore, coke, limestone and moisture. The main objective of iron ore sintering is producing resistant agglomerates which can be used in blast furnaces. For this purpose, the sinter mixture is partially melted in high temperature and finally molten is allowed to cool. The molten production and subsequently, the solidification process are totally dependent on composition and components of mixture. Changes in bed porosity, caused by... 

The standard percolation theory uses objects of the same size. Moreover, it has long been observed that the percolation properties of the systems with a finite distribution of sizes are controlled by an effective size and consequently, the universality of the percolation theory is still valid. In this study, the effect of power law size distribution on the critical exponents of the percolation theory of the two dimensional models is investigated. Two different object shapes i.e., stick-shaped and square are considered. These two shapes are the representative of the fractures in fracture reservoirs and the sandbodies in clastic reservoirs. The finite size scaling arguments are used for the... 

In this paper, a novel structure for MOSFET like CNTFETs (MOSCNTs) is proposed, combining the advantages of both high and low dielectrics to improve output characteristics. In this structure, the gate dielectric at the drain side is selected from a material with low dielectric constant to form smaller capacitances, while a material with high dielectric constant is selected at the source side to improve on current and reduce leakage current. The new structure is simulated based on the Schrödinger-Poisson formulation. Obtained results show that the proposed configuration has lower off and higher on current in comparison with low-k MOSCNTs. Also, using a two-dimensional model, a wide range of... 

Meshless methods are a relatively new type of numerical methods that have attracted the attention of many researchers over the past years. So far, a number of meshless methods have been developed and applied to solve problems in various fields of engineering, including solid mechanics and geotechnical problems. The Element-Free Galerkin (EFG) method is adopted in this study for solving the governing partial differential equations of equilibrium and continuity of pore fluid flow for numerical simulation of coupled hydro-mechanical problems. For this purpose, the weak form of the governing equations is derived by applying the weighted residual method and Galerkin technique. The penalty method... 

In this paper, we consider the restricted version of the well-known 2D line simplification problem under area measures and for restricted version. We first propose a unified definition for both of sum-area and difference-area measures that can be used on a general path of n vertices. The optimal simplification runs in O(n 3) under both of these measures. Under sum-area measure and for a realistic input path, we propose an approximation algorithm of O n2 time complexity to find a simplification of the input path, where is the absolute error of this algorithm compared to the optimal solution. Furthermore, for difference-area measure, we present an algorithm that finds the optimal... 

Models play an important role in fuel cell design and development. One of the critical problems to overcome in the proton exchange membrane (PEM) fuel cells is the water management. In this work a steady state, two-dimensional, isothermal model in a single PEM fuel cell using individual computational fluid dynamics code was presented. Special attention was devoted to the water transport through the membrane which is assumed to be combined effect of diffusion, electro-osmotic drag and convection. The effect of current density variation distribution on the water content (λ) in membrane/electrode assembly (MEA) was determined. In this work the membrane heat conductivity is considered as a... 

A series of wind tunnel tests are performed to examine the flow field over a swept wing under various conditions. The wing has a laminar flow airfoil section, similar to those of the NACA 6-series. Static pressure distributions over the upper surface of the wing, in both chordwise and spanwise directions, are measured at different angles of attack. The data is employed to predict the transition point at each chordwise section. The skewness parameter of the pressure data shows that this factor drops to zero in the transition region. A comparison of the calculated transition point on the wing surface with that obtained from the 2D computational method shows reasonable agreement over a portion... 

Fluid flow behavior in a porous medium is a function of the geometry and topology of its pore space. The construction of a three dimensional pore space model of a porous medium is therefore an important first step in characterizing the medium and predicting its flow properties. A stochastic technique for reconstruction of the 3D pore structure of unstructured random porous media from a 2D thin section training image is presented. The proposed technique relies on successive 2D multiple point statistics simulations coupled to a multi-scale conditioning data extraction procedure. The Single Normal Equation Simulation Algorithm (SNESIM), originally developed as a tool for reproduction of... 

In this study, a pure Lagrangian algorithm for numerical simulation of fluid-structure interaction problems is proposed based on the Smoothed Particle Hydrodynamics (SPH) method. A new treatment of boundary conditions at the interfaces is introduced that provides the possibility of simultaneous integration of governing equations for all particles, regardless of its material type. The proposed algorithm is capable of dealing with large deformations of hypo elastic solids. The method is validated by comparison of numerical results with other numerical simulations and also examining the consistent behaviors of the algorithm for different parameters  

In this paper, a two-dimensional numerical approach is used to study the effect of micro combustor height, mass flow rate and external convection heat transfer coefficient on the temperature and species mass fraction profiles. A premixed mixture of H2-Air with a multi-step chemistry is used. The transient gas phase energy and species conservation equations result in an Advection-Diffusion-Reaction system that leads to two stiff systems of PDEs. In the present work, the computational domain is solved through the Strang splitting method, which is suitable for a nonlinear stiff system of PDEs. A revised boundary condition for the velocity equation is applied and its effect on the flow...