Sharif Digital Repository

Asphaltenedeposition is a major problem during natural depletion and EOR processes due to formation damage issues. It is necessary to reveal asphaltene deposition mechanisms and its effective parameters to prepare an acceptable prevention strategy. Therefore, different natural depletion and EOR experiments must performed on core samples. In this research, Effect of CO2 injection on asphaltene deposition phenomena has been surveyed. Two carbonate core samples and one sandstone core sample was used in experiments. The oil used in these experiments was recombinedoilfrom one of Iranian offshore oilfield.In order to estimate permeability reduction during experiment, injection of oil and CO2 was... 

Alborz-I array with 20 detectors will be established at Sharif University of Technology, to study Extensive Air Showers with energies around the knee of cosmic ray spectrum. In this thesis studies related to construction of this array is performed in two parts. First part is dedicated to evaluate detectors of Alborz-I array. Each detector consists of a plane plastic scintillator, 50×50×2 cm3 each, which is enclosed in a pyramidal light enclosure with a 5 cm photomultiplier tube at the vertex of the light enclosure. In order to optimize the height of the light enclosure, two parameters are considered: efficiency and uniformity of different parts of the detector. By building and comparing four... 

The release of toxic materials causes tragic accidents every year. There are various techniques in order to mitigate the release effect of these materials such as Application of air jets, steam curtains and water curtains. In this study first, previous works are reviewed in order to select the best technique for the mitigation of heavy toxic gas release. Then CFD modeling is used to simulate this technique.
A field situation in which chlorine gas was released upwind of water spray was simulated using the open-source software FDS (Fire Dynamic Simulator), a CFD model. Only mechanical effects of water sprays are considered; hence the effect of absorbtion is neglected. Finally tha... 

The release of toxic materials causes tragic accidents every year. There are various techniques in order to mitigate the release effect of these materials such as Application of air jets, steam curtains and water curtains. This study presents numerical calculations to reproduce the continuous ammonia release dispersion with and without the mitigating influence of a downwind water curtain using computational fluid dynamic (CFD) software ANSYS Fluent 15.0. The RNG model coupled with Lagrangian discrete phase model (DPM) was used to simulate the dilution effectiveness of the water curtain system. The ammonia absorption was taken into account by means of user-defined functions (UDF). The... 

Considering the supply and demand market of natural gas, methanol, propylene and ethylene and the propylene value chain, it is expected that the design of the propylene production process from methanol produced from natural gas and its implementation in Iran country can significantly flourish the production of polypropylene, acrylonitrile and Etc. On the other hand, with the industrialization of this process, the uncontrolled export of methanol from Iran to countries such as China and the devaluation of methanol will be prevented. In this report, the process of producing synthetic gas from natural gas using autothermal reactor and heat exchange reforming, separation and storage of carbon... 

Fire is the most likely type of process accident which occurs in industrial plants. Among all different types of fire, pool fire is the most frequent one, so there are extensive researches done about pool fire. One of the research areas that has drawn a lot of attention in recent years, is pool fire modeling. Results obtained from fire modeling are quite applicable in different fields of safety engineering such as Quantitative Risk Assessment (QRA) or fire proofing studies of process equipment. But fire modeling is an inherently complex process. Because there are several aspects involved such as multi-phase flow, turbulent mixing, combustion and different mechanisms of heat transfer. This... 

Mass or large-scale storage of hydrogen, as a clean source of energy, should be conducted in underground formations in order to be used as a reliable energy source at the peak of consumption. In this regard, underground formations such as aquifers and depleted hydrocarbon reservoirs are the most favorable and secured media for hydrogen storage. However, detailed understanding of the flow dynamics of hydrogen-water in these media is critical to maximize hydrogen storage and recovery and tackle the existing uncertainities which exist in the flow functions. To fill this gap, this research aims at a detailed pore-scale investigation of the effect of flow regime, hydrogen compressibility, and... 

Sustainable and renewable energy sources are of fundamental importance in the development of strategic and sustainable economies. Therefore, in recent decades, water electrolysis has been widely used to produce pure hydrogen and oxygen without emitting carbon materials and is considered as a method for producing electrical energy alongside other renewable sources (such as wind and solar energy). Here, we report the synthesis of CoFe double-layered hydroxides (CoFe-LDHs) and their application as electrocatalysts for water splitting in alkaline environments. CoFe-LDHs were prepared via a new hydrothermal route from the metal-organic framework MIL-88A (MOF). The Co to Fe ratio in LDHs was... 

There are different well-established strategies for making a process plant inherently safer. The benefits of applying these strategies on reducing the overall risk inside a plant are obvious. However, some of these changes are rejected many times because they appear to be too costly. But if the effects of applying inherently safer design strategies are investigated not only on the processing costs of a plant but also on the potential accident costs, the decision would in fact be different. In this paper an optimization procedure is proposed which integrates both processing and accident costs for different design schemes. In this procedure, some of the design variables are chosen with regard... 

Due to the replacement of fossil fuel with cleaner products, the reduction of fuel consumption in transportation until 2045, the excessive production of fuel oil in refineries and the growth of feed demand from downstream chemical units, have made countries to upgrade their refineries or construct Petro-refineries. The Petro-refinery is a new generation of refinery and its main purpose is to supply chemicals to downstream units. The products of these units will have more valuable than fuel refineries. Steam cracking unit, aromatic unit and propane dehydrogenation unit are important units that are in Petro-refineries. In this research, all refinery units were technically and economically... 

The present study was aimed at investigating the relationship between reading comprehension ability as probably the most vital language skill especially in academic contexts (Farrell, 2009) and critical thinking as one of the most debated issues among scholars in modern education (Ku, 2009; Rudd, 2006). To this end, 200 male and female university students studying English Translation and Literature were chosen as the participants who sat for two tests. The first was a reading section of a retired TOEFL test provided by educational testing service in which the participants' scores were regarded as their reading comprehension ability. The second was the California Critical Thinking Skills... 

Up to now, compared with the comprehensive research for developing robust watermarking algorithms, no equal attention has been devoted to the proposition of benchmarks tailored to assess the watermark robustness. In addition, almost all the state of the art benchmarks only integrate a number of common image processing operations like geometrical transformations to remove watermarks. However, the quality of the processed image is often too degraded to permit further commercial exploitation. Moreover, to the best of our knowledge, the design of these tools does not take into account the statistical properties of the images and watermarks in the design of attacks. In spite of the significant... 

Gas detection systems are now recognized as an essential component of safety in process units.but their successful performance depends strongly on the number and location of the detectors.As for the limited resources available (detectors), the placement of gas detectors can be considered as an optimization problem with different objective functions. In this research, an attempt was made to provide models and methods that quantitatively and from a practical point of view to optimum locate the detectors. Initially, a risk-based method was presented that defines the necessary steps for the arrangement of fire gas detectors with the aim of covering the maximum risk of leakage scenarios (risk:... 

In order to better understand the performance of the Iranian health insurance industry, household decisions to purchase private health insurance are analyzed using a two-stage (Heckman) model on Survey of Family Income and Expenditure data. Probit and OLS regressions are used to examine the factors influencing the probability and amount of private health insurance purchased. Generally, factors affecting the probability of having insurance also influence the amount of insurance coverage purchased. The results show the importance of some demographics on the insurance decision, particularly age, gender and marital status. Socio-economic factors such as education, income, employment sector,... 

Among probable hazards in chemical industries: vapor cloud explosion (VCE) is one of the worst and most destructive ones. More than half of the major process inci¬dents, according to the statistics, are VCEs. VCE causes the most serious consequences; therefore, it attracts many attentions to itself. Accordingly, plenty of researches have been done for the purpose of protection against VCE effects. All efforts in this field can be categorized in two different main activities; firstly, prescribing safety distances between groups of hazardous equipment and vulnerable areas, secondly, using facilities which reinforce vulnerable areas against explosion blasts. Regardless to which category is... 

Domino accidents are one types of incidents that lead to irreparable damage to industrial units. Since the consequences of such incidents are far more than the first level incident, consideration of this issue and the provision of appropriate strategies for identifying and evaluating this type of incident is very important. Major efforts have been made in the area of process safety is in risk assessment and identify possible scenarios and their probability of occurrence, and have not addressed the financial consequences of an incident. In this research, an algorithm has been developed to estimate the financial losses incurred with an industrial unit due to a domino incident and various... 

Emissions of carbon dioxide (CO2) from fossil fuels are a potential issue for the global climate. One way to meet this challenge is to electrochemically convert CO2 molecules to reduced carbon species such as formates, alcohols, hydrocarbons, etc., which is a difficult process due to the poor kinetics of CO2 reduction. Therefore, the use of catalysts, while preventing undesirable side reactions, can also play an important role in reducing CO2. In this study, a two-step synthesis of CuS (1, 5, 12, 24 hr) @ Cu-MOF has been reported as an advanced electrocatalyst for CO2 reduction in neutral pH environments. Bismuth has been used to improve the electrocatalytic properties of the samples. Bi-CuS... 

The seasonal fluctuations in economics variables relate to the different behavior of economic agents across different seasons. In past, seasonality has been viewed as a redundant feature that needs to be removed from data before economic analysis. From 1988, modeling seasonality has become the major concern of many economists; moreover, it was seen that many economic analysis and forecasts could be flawed if seasonality is ignored. In the present research, periodic times series approach is used for the first time in modeling the seasonality feature of the housing market. Regarding the importance of the housing sector in economy from micro and macroeconomic points of view, using a more... 

Electrochemical water splitting which consists of two half-reactions, namely; the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is an important process in electrochemical energy storage and sustainable production of energy. Therefore, the development of cost-effective and efficient electrocatalysts for water splitting has attracted a lot of interest. In this work, a new nanocomposite was prepared from cobalt diselenide and cerium (IV) oxide derived from calcination of a cerium-based metal-organic framework (Ce-MOF), via hydrothermal and electrodeposition methods. The structure and morphology of synthesized materials were investigated by XRD, FE-SEM, EDX, and BET... 

The continual deterioration and insufficient strength of reinforced concrete (RC) structures has been a vital problem in the field of civil engineering such an extent that traditional methods of strengthening found to be inconvenient. Nowadays by increasing demands for retrofitting of structures, it necessitates the application of efficient, inexpensive and unobtrusive methods of strengthening. Common way on retrofitting was to use of steel plates externally bonded to RC members. Although this technique has proven to be reasonably effective, it has several distinct disadvantages such as susceptibility of the steel plates to corrode and the excessive weight of steel plates when used in...