Sharif Digital Repository

Excessive water production in highly heterogeneous mature reservoirs (water flooded or affected by water zones) leads to increased production costs. Water production causes sediment formation, creation of corrosion, water treatment and disposal, and finally due to the inefficiency of production, it leads to closure of the well.Among the methods introduced to reduce water production, the use of polymers and gels as an affordable and effective method has been widely used in enhanced oil recovery processes. The main mechanism in this method is blocking or limiting the major paths of water flow (fractures or high permeability zones) and thereby increasing sweep efficiency in water injection.... 

We investigate heat transfer between parallel plates separated by liquid argon using three-dimensional molecular dynamics (MD) simulations incorporating with 6-12 Lennard-Jones potential between molecule pairs. We use thermal walls constructed from the oscillating molecules, which are connected to their original positions using linear spring forces. Channel walls are maintained at specific temperatures using a recently developed interactive thermal wall model. This approach is much more effective than the one which uses a fixed lattice wall modeling to simulate the heat transfer between wall and fluid. Heat flux and temperature distribution in nanochannels are calculated for channel height... 

Slosh phenomenon is described as the motion of the fluid’s free surface in a tank or partially-filled container. This motion can induce undesired forces that can change the path of a vehicle. In some liquid carrying vehicles these undesired changes is sensed by the driver or control system and can lead to instability. Some examples of this phenomenon are aircrafts, rockets, ships and fuel carrier trucks.
In this project, a coupling between the dynamics of the vehicle and the contained fluid is implemented for in depth understanding of the interactions. This is done by Co-Simulation. With the help of Co-Simulation, corrective control actions can be taken and the design of more powerful... 

In recent decades, we have faced the enormous growth of data and graph volumes. This requires modern ways of computation and storage systems and algorithms. MapReduce is a known way of processing Big Data in a Parallel and primarily Distributed setting. Theoretical models (e.g., Massively Parallel Computation) for Algorithms using this paradigm commonly evaluate the number of rounds and needed communication. We study the Minimum Spanning Tree (MST) as a fundamental graph problem. This problem in MapReduce is harder for sparse graphs. We introduce an algorithm that performs well comparing previous studies, especially for sparse graphs.We present an empirical study by implementing some... 

In the current situation, kidney transplantation is the most appropriate and least costly treatment for patients with end-stage renal disease (ESRD). Related or altruistic living donors, as well as deceased donors, are considered as a supply source for donated kidneys. Researches have shown deceased donor kidney may not work as well as a living donor kidney because the deceased donor kidney is outside the donor's body for a longer time. If the donor has an incompatibility with the patient (in terms of the blood group, HLA, etc.), a kidney exchange between the pairs can be used to resolve the issue and make the transplantation possible. Pairs with blood group compatibility have also... 

Despite of significant developments of optical trapping in past decays, trapping of small nanometer-sized particle faces some difficulties. Optical force reduces rapidly by decreasing the size of the particle because of reducing the particle’s polarizability. So, it is necessary to increase the intensity of incident beam to attain a stable trap. However, it can lead to damage of particle before getting trapped. Self induced back-action(SIBA) is one of the proposed solutions to overcome this problem. In this phenomena particle plays an active role in trapping by changing the surrounding electromagnetics field. In this thesis, we show that SIBA is a phenomenon that appears when we extend the... 

Taking into account the fast and ever-increasing pace of data growth, clustering algorithms emerge as the key tools for data analysis in new researches. Clustering remain as a method for decomposing data into clusters, in such a way that similar data coalesce in the same group. Different algorithms conduct clustering according to a series of initial hypotheses, without being informed about the clusters’ form and aims. Hence, in case with no conformity between initial hypothesis and the clustering aim, one cannot expect adequate response from the clustering algorithm. Exploitation of side information in clustering can play an impactful role in introduction of real models into clustering... 

Considering the limited number of works on investigation of solidification characteristics of Al-Zn-Mg-Cu cast alloys as well as the applications of this alloy system in aerospace industries, the solidification conditions of Al 713 alloy were investigated in this study. In order to achieve this goal, a number of experiments were designed and conducted including quantometry, thermal analysis, metallography and hardness measurements. In this thesis, effects of cooling rate on secondary dendritic arms spacing as well as solidification parameters including nucleation temperature, solidification time and temperature range, dendrite coherency point and formation temperature of intermetallic... 

Because of increasing usage of modified polymers and consequent necessity for investigation and modeling of mechanical behavior of these materials, it is important to get a yield criterion for these materials. For this purpose the Gurson yield criterion presented for porous metals, was modified with regard to mechanical properties of polymers. Indeed pressure sensitivity of polymers and their large elastic strain during deformation, makes using of Gurson yield criterion problematic for modified polymers.
For modification of Gurson criterion, macroscopic hydrostatic yield stress equation was derived for a thick-walled spherical shell of epoxy and then Gurson criterion was modified with... 

The low female labor force participation rate in the Iranian labor market relative to the global average and even to countries that do not differ significantly from the socio-economic characteristics of our country is one of the important questions of the Iranian labor market. In this study, we seek to answer the question of whether the economic participation rate of married women will increase if the gender gaps in wages, job findings and job losses among women and men are eliminated in the Iranian labor market. To answer this question using household expenditure and income data and labor force data, we show that between the two categories of occupations, in terms of the share of women's... 

Hyperbolic branching Brownian motion is a branching diffusion process in which individual particles follow independent Brownian paths in the hyperbolic plane H2, and undergo binary fission(s) at rate λ > 0. It is shown that there is a phase transition in λ : For λ ≤ 1/8 the number
of particles in any compact region of H2 is eventually 0, w.p.1, but for λ > 1/8 the number of particles in any open set grows to ∞ w.p.1. In the subcritical case (λ ≤ 1/8) the set Λ of all limit points in ∂H2 (the boundary circle at ∞) of particle trails is a Cantor set, while in the supercritical case (λ > 1/8) the set Λ has full Lebesgue measure. For λ ≤ 1/8 it is shown that w.p.1 the Hausdorff dimension of Λ... 

Fatigue crack growth can have harmful effects on the reliability rotary machine. While an early warning to crack, can be used to extend the life of these expensive machines and increase reliability.Structural Vibration Condition Monitoring as a primary fault detection method, achieved to a lot amazing result and for this reason studies vibration behavior of cracked rotational shaft is a big issue for engineers of dynamic machine.In this research, first check the fault detection methods based on structural vibration condition monitoring, mode shape methods were extracted. Then by modeling rotational shaft in computer and creation of crack on it, fault detection quality of these methods have... 

In the present study, the effects of increasing the value of shale gas production, either due to increased production or price increases, have been studied on economic variables such as employment, wage, property value and the number of births. In this regard, the data for each of these variables was used at the county level in the United States of America between 2000 and 2011. In order to estimate the desired effects, counties are divided into two types of boom and non-boom counties. The findings indicate that increasing natural gas production will lead to more employment and wage growth in boom counties than non-boom counties. Also, during the period of increasing production, the value of... 

It is important to provide an appropriate and economically method with technical and engineering considerations to stabilize excavated underground spaces. The necessity of this, especially for the construction of underground metro stations located in the cities which faces many problems, is more evident. In this research, it has been tried to introduce an optimal method according to the type of area for the construction of the underground station. In order to obtain stress and strain condition in structural elements and surface deformations due to different stages of excavating, numerical modeling in FLAC3D has been used. By examining the parameters that affect the sustainability of this... 

In this study, we aim to learn representations from microscopic cell images that effectively capture the features of drugs affecting the cells, allowing us to identify effective drugs for treating a disease. We employ two parallel learning paths using predictive and generative models. Specifically, we have achieved a predictive model on the RxRx19a dataset that, unlike previous models, is interpretable, optimized, and robust to dras- tic changes in drug properties. Additionally, we have developed the first generative model on this dataset, which not only generates high-quality images but also discovers a meaningful latent space. This latent space divides the representation into relevant... 

Co-movement between inflation and nominal interest in response to an interest rate shock, dubbed neo-fisherianism, has been the subject of contentious debate since the advent of non-inflationary ZLB environment. We design an economic model rich with banking features to understand the economic responses to permanent and long-term interest rate shocks. We find that responses to a permanent positive interest rate shock depend on the monetary authorities’ speculation of the new long-term inflation rate, with the most probable outcome being a permanent increase in inflation. Responses to a long-term positive interest rate shock depict an increase and then decrease in inflation. We also discover... 

Spray-wall impingement is one of the phenomenon that associated in different subject such as spray cooling, combustion chamber and gas turbine. With the impingement of spray to the wall, liquid film begins to form. Wall film characteristics is still an important subject to study. Due to the various stages of liquid film formation from injection of spray till spray-wall impingement, the investigation of this phenomenon is far more complicated. This paper is meant to provide detailed data on spray-wall impingement and wall film formation physics with the help of computational analysis of OpenFOAM . A Lagrangian-Eulerian method based on discrete phase model (DPM) was employed to model... 

Influence of excavating the Tehran metro line 7 tunnel on surface settlement, stresses and deformations induced in Towhid tunnel is investigated using numerical modeling. Construction of Metro tunnel as the new one must be carried out without imposing any damage to the Towhid tunnel as the existing tunnel. Towhid tunnel is a set of twin tunnels along the Chamran highway in Tehran. The tunnels were constructed using sequential excavation method and lined with cast in place reinforced concrete; on the other side metro line 7 is being constructed using 2 EPB tunnel boring machines and lined with reinforced concrete segments. This research consists of the study of the effects of pillar width,...