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Size Exclusion Mechanism, Suspension Flow through Porous Medium  [PDF]
Hooman Fallah, Afrouz Fallah, Abazar Rahmani, Mohammad Afkhami, Ali Ahmadi
International Journal of Modern Nonlinear Theory and Application (IJMNTA) , 2012, DOI: 10.4236/ijmnta.2012.14017
Abstract:

A lot of investigations have been done in order to understand the mechanisms of the transport of particulate suspension flow through porous medium. In general, Deep Bed Filtration studies have been conducted to analyse the mechanism involved in the processes of capturing and retaining particles occurs throughout the entire depth of the filter and not just on the filter surface. In this study, the deep bed filtration mechanism and the several mechanisms for the capture of suspended particles are explained then the size exclusion mechanism has been focused (particle capture from the suspension by the rock by the size exclusion). The effects of particle flux reduction and pore space inaccessibility due to selective flow of different size particles will be included in the model for deep bed filtration. The equations for particle and pore size distributions have been derived. The model proposed is a generalization of stochastic Sharma-Yortsos equations. Analytical solution for low concentration is obtained for any particle and pore size distributions. As we will see, the averaged macro scale solutions significantly differ from the classical deep bed filtration model.

A hybrid TOPSIS-BSC method for strategic planning
Mohammad Reza Shojaee,Mehdi Fallah,Mohsen Fallah
Management Science Letters , 2012,
Abstract: For years, tangible assets used to be the most important precious wealth of organizations. However, the recent advances in technology has changed this concept and today, intangible assets such as human resources, customers, processes are playing essential roles on making strategies. In this paper, we present a study to setup appropriate strategies using the implementation of balanced score card in four perspectives of customers, processes, learning and financial. The proposed study of this paper gathers important factors through three different brainstorming sessions and prioritize them using TOPSIS method. Based on the results of MCDM technique, selecting appropriate target market for penetration is the number one priority followed by having good accounting system and preparing for more diversified production. These are the most important items influencing strategic planning. Therefore, the study uses BSC for the first two important strategies and discusses possible actions for productivity improvement.
External Cake Build Up at Surface of Porous Medim  [PDF]
Hooman Fallah, Ali Ahmadi, Mohammad Afkhami Karaee, Hasan Rabbani
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.24015
Abstract: Deep bed filtration of carrier water with particles occurs in numerous processes of environmental, chemical, petroleum and civil engineering. For example in the petroleum industry, deep bed filtration of drilling fluid happens during well drilling; it also takes place near to injection wells during seawater injection or produced water re-injection causing in- jectivity reduction. In this work, the filtration theory and its mathematical model are given and the filtration coefficient will be discussed. Then the transition time, the time at which the initial layer of external filter cake is completely formed has been derived mathematically. The transition time can be obtained by calculating the trapping efficiency as a function of the number of previously deposited particles where very few particles can invade the rock and the external filtration begins to build. The prediction of particle capturing and particle retention by mathematical model is an essen- tial stage during planning and design of above-mentioned industrial processes.
Effect of Fluid Flow Characteristics on Migration of Nano-Particles in Porous Media  [PDF]
Saeed Sourani, Mohammad Afkhami, Yousef Kazemzadeh, Hooman Fallah
Geomaterials (GM) , 2014, DOI: 10.4236/gm.2014.43008
Abstract:
Inter-particle and molecular forces are of most important forces affecting fines migration. Investigating the impact of these types of forces requires information about electrical properties of constitutive component and Nano-sized solids. Surface potential is a well-known parameter, which can be used to measure aforementioned forces. The force balance among electrical, gravity, drag and buoyance forces tracing on a particle can be estimated using fluid properties and physical properties of reservoir such as surface potential, pore size distribution and fine size distribution. The task is to set these forces at conditions that fine migration does not take place. This paper investigates the impact of several parameters that could influence pertinent forces. Effect of ionic strength of flowing fluid is taken into account to evaluate Debye length that determines double layer forces. The impact of injection rate on a parameter named erosion number is also studied. The results of this study show that how introducing salts and injection rate can affect stability of fines on their locations.
Importance of Double Layer Force between a Plat and a Nano-Particle in Restricting Fines Migration in Porous Media  [PDF]
Saeed Sourani, Mohammad Afkhami, Yousef Kazemzadeh, Houman Fallah
Advances in Nanoparticles (ANP) , 2014, DOI: 10.4236/anp.2014.33014
Abstract:
Fines migration is defined as separation of a Nano-sized particle by fluid flow in porous media and its migration along some distances and its entrapment in a narrow pore throat or its settlement on pore wall. Although this phenomenon happens in scales of Nano-meters, it can lead to sever irretrievable damages. This damage includes permeability reduction that causes drastic oil recovery reduction. There are several forces impacting a fine that is placed on a pore wall. Some of most important forces affecting settlement of a fine in porous media in presence of a fluid are electrical forces. Electrical forces consist of several long and short range forces. This study focuses on a long range force called Double Layer Force (DLF) that beside Van der Waals is one of most powerful electrical forces. DLF is a repulsive force that can repel a particle from pore wall and result separation of a Nano-sized solid which subsequently moves along with flowing fluid and clogs a throat. The DLF depends on the solid material (reservoir rock and fine) and fluid properties (i.e. ionic strength, pH). This study investigates how each of these parameters affects DLF and introduces proper conditions for reservoir water flooding for controlling fines migration.
PHOTOACTIVE POLYACRYLONITRILE FIBERS COATED BY NANO-SIZED TITANIUM DIOXIDE: SYNTHESIS, CHARACTERIZATION, THERMAL INVESTIGATION
MOAFI,HADI FALLAH; FALLAH SHOJAIE,ABDOLLAH; ALI ZANJANCHI,MOHAMMAD;
Journal of the Chilean Chemical Society , 2011, DOI: 10.4067/S0717-97072011000100020
Abstract: anatase nanocrystals were successfully synthesized and deposited onto polyacrylonitrile fibers with photocatalytic self-cleaning activity using the sol-gel process at low temperature. the original and treated samples have been characterized by several techniques such as scanning electron microscopy, fourier transform infrared spectroscopy, x-ray diffraction, diffuse reflectance spectroscopy, thermogravimetric analysis and differential scanning calorimetry. the tio2 nanoparticles, have been found to form a homogeneous thin film on the fiber surface. the photocatalytic activity, tested by measuring the degradation of adsorbed eosin yellowish dye. the photoactivity of the titanium dioxide coated fibres is much higher than that observed in case of untreated fibers. the photocatalytic self-cleaning properties of the treated fibers was fully maintained performing several cycles of photodegradation. this preparation technique can be also applied to new fabrics to create self-cleaning properties in them. the thermogravimetric study of pan/tio2 composite showed a slight increase of weight loss in the second step, which implied that, the dehydrogenation and oxygen uptake reactions would be promoted by the tio2 to some extent.
PHOTOACTIVE POLYACRYLONITRILE FIBERS COATED BY NANO-SIZED TITANIUM DIOXIDE: SYNTHESIS, CHARACTERIZATION, THERMAL INVESTIGATION
HADI FALLAH MOAFI,ABDOLLAH FALLAH SHOJAIE,MOHAMMAD ALI ZANJANCHI
Journal of the Chilean Chemical Society , 2011,
Abstract: Anatase nanocrystals were successfully synthesized and deposited onto polyacrylonitrile fibers with photocatalytic self-cleaning activity using the sol-gel process at low temperature. The original and treated samples have been characterized by several techniques such as scanning electron microscopy, fourier transform infrared spectroscopy, x-ray diffraction, diffuse reflectance spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The TiO2 nanoparticles, have been found to form a homogeneous thin film on the fiber surface. The photocatalytic activity, tested by measuring the degradation of adsorbed Eosin Yellowish dye. The photoactivity of the titanium dioxide coated fibres is much higher than that observed in case of untreated fibers. The photocatalytic self-cleaning properties of the treated fibers was fully maintained performing several cycles of photodegradation. This preparation technique can be also applied to new fabrics to create self-cleaning properties in them. The thermogravimetric study of PAN/TiO2 composite showed a slight increase of weight loss in the second step, which implied that, the dehydrogenation and oxygen uptake reactions would be promoted by the TiO2 to some extent.
Corneal endothelial cell density and morphology in normal Iranian eyes
Mohammad Hashemian, Sasan Moghimi, Masood Fard, Mohammad Fallah, Mohammad Mansouri
BMC Ophthalmology , 2006, DOI: 10.1186/1471-2415-6-9
Abstract: Specular microscopy was performed in 525 eyes of normal Iranian people aged 20 to 85 years old. The studied parameters including mean endothelial cell density (MCD), mean cell area (MCA) and coefficient of variation (CV) in cell area were analyzed in all of the 525 eyes.MCD was 1961 ± 457 cell/mm2 and MCA was 537.0 ± 137.4 μm2. There was no statistically significant difference in MCD, MCA and CV between genders (Student t-test, P = 0.85, P = 0.97 and P = 0.15 respectively). There was a statistically significant decrease in MCD with age (P < 0.001, r = -0.64). The rate of cell loss was 0.6% per year. There was also a statistically significant increase in MCA (P < 0.001,r = 0.56) and CV (P < 0.001, r = 0.30) from 20 to 85 years of age.The first normative data for the endothelium of Iranian eyes seems to confirm that there are no differences in MCD, MCA and CV between genders. Nevertheless, the values obtained in Iranian eyes seem to be different to those reported by the literature in Indian and American populations.Monolayer of corneal endothelial cell covers the posterior surface of descemet's membrane. In normal cornea dimension of endothelial cells are uniform. Corneal endothelium is metabolically active and responsible for keeping the corneal stroma in its usual dehydrated state of 70% water [1-3].Prior to 1970s, the study of corneal endothelium was limited to biomicroscopic evaluation for guttata, fold and keratic precipitates. Nowadays specular microscope has made the evaluation of endothelium possible. The aim of quantitative specular microscopic analysis is to assign values to endothelial cells that can provide a measure of their functional states. It makes the measurement of mean cell density (MCD), mean cell area (MCA) possible as well as measurement of variations in cell size (polymegathism) and cell shape (polymorphism). The specular microscope has been used to establish and compare normative data for endothelium parameters among ethnic groups [4-6] as wel
Field Scale Simulation Study of Miscible Water Alternating CO2 Injection Process in Fractured Reservoirs  [PDF]
Mohammad Afkhami Karaei, Ali Ahmadi, Hooman Fallah, Shahrokh Bahrami Kashkooli, Jahangir Talebi Bahmanbeglo
Geomaterials (GM) , 2015, DOI: 10.4236/gm.2015.51003
Abstract: Vast amounts of world oil reservoirs are in natural fractured reservoirs. There are different methods for increasing recovery from fractured reservoirs. Miscible injection of water alternating CO2 is a good choice among EOR methods. In this method, water and CO2 slugs are injected alternatively in reservoir as miscible agent into reservoir. This paper studies water injection scenario and miscible injection of water and CO2 in a two dimensional, inhomogeneous fractured reservoir. The results show that miscible water alternating CO2 gas injection leads to 3.95% increase in final oil recovery and total water production decrease of 3.89% comparing to water injection scenario.
Stochastic Stability of Linear Gyroscopic Dynamic Systems
Leila Fallah Araghi,Mohammad Reza Arvan
Lecture Notes in Engineering and Computer Science , 2009,
Abstract:
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