Sharif Digital Repository

Due to their low volatility, negligible flammability, and high regeneration capacity, ionic liquids have attracted a lot of attention in chemical and process engineering fields. Regarding the limited access to the laboratory facilities, developing theoretical methods such as equations of state is important in this research field. Thus, data for density and viscosity of pure ionic liquids and vapor pressure data for binary mixtures of ionic liquids and acidic gas have been collected and validated from the IL Thermo website for 42 ionic liquids. By consideration of theoretical studies and comparison of the performance of different cubic equations of state in predicting the aforementioned... 

With considering the existence of carbonyl sulfide in natural gas and crude oil, we need to study the absorption of this gas in aqueous alkanolamine solutions. In this project the solubility of carbonyl sulfide in different pressures and two temperatures of 313.15 and 348.06 K have been measured.The absoption of carbonyl sulfide in aqueous alkanolamine solutions is a very slow process. In this study we used different methods for measuring the required data. Befor the experiments we calibrated the set up with reliable data. Finaly the results simulated with Deshmakh-Mather thermodynamic model, numerically. The simulation results show a good agreement with experimental data  

Inrecent years,research onionic liquidsarehighly developed. Because ofthe uniqueproperties ofionic liquidssuch asnegligiblevapor pressureandthermalstability for use inlarge areasofmajor industries have been considered.However,ionic liquids because they have lessenvironmental wasteas an alternative to convention alorganic solventssuch asaminesalkanolanarise.Ionic liquid sassolventsfor theremoval ofacid gases such as water and gasare investigated. The solubility of CO2 and H2S in the [Emim] [OTF] (1-ethyl-3-methylimidazolium triflate) in the temperature range 303.15 to 343.15 K and pressures up to 2 MPa has been studied experimentally. In order to capture modeling, the model equations of state... 

Formation of gas hydrates is a challenge in the oil and gas industry. Gas hydrate formation can be prevented by several methods. One of these methods is to utilize of inhibitor components. The gas hydrate inhibitors can affect hydrate formation from two aspects, i.e., thermodynamic or kinetic. In this work, thermodynamic and kinetic effects of [Emim][BF4] ionic liquid on growth and dissociation of methane hydrate crystal were investigated using molecular dynamics simulation. Molecular dynamics simulation is powerful tool to investigate the thermophysical, structural, and dynamic properties of methane hydrate and the formation, dissociation, and inhibition mechanisms at the molecular scale.... 

Removal of some hazardous and toxic components of natural gas is of a great importance in industries. Thus solubility measurement of these components in appropriate solvents is a necessary task. Methylmercaptan due to its high toxicity as one of these components is separated by means of Alkanolamines. In this project a physical solubility experimental setup for absorption Methylmercaptan (CH3SH) in 48wt%, 35wt% and 25wt% MDEA aqueous solutions at 50°C and in pressures between (0.7 to 3)bar was designed and developed. The suggested setup can be used for measurement of solubility of gases (physical and chemical) in different solutions. The performance basis of the system is on precise... 

Ionic liquids (IL's) are found to be potentially suitable solvents for the chemical process industry, especially due to their negligible vapor pressure which can result in a major decrease of solvent loss and the environmental harm. One of the foreseeable industrial applications in the field of natural gas processing is the replacement of traditional organic solvents (usually alkanol amines) presently used for the absorption of H2S from sour gases, by suitable IL's. Ionic liquids have been proposed for the separation of gas mixtures. In particular, ionic liquids have been suggested for the removal of the acid gases, hydrogen sulfide, and carbon dioxide, from natural gases and refinery gases.... 

New experimental results are presented for the solubility of carbon dioxide and hydrogen sulfide sulfide in six imidazolium-based ionic liquids included 1-octyl-3-methylimidazolium tetrafluoroborat ([C8mim][BF4]), 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]), 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide ([C8mim][Tf2N]), 1-octyl-3-methylimidazolium trifluoromethanesulfonate ([C8mim][TfO]), 1-hexyl-3-methylimidazolium trifluoromethanesulfonate ([C6mim][TfO]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4mim][TfO]) at temperatures range from 303.15 to 353.15 K and pressures up to about 2.5 MPa. The solubilities of the mixture of CO2/H2S in... 

Intrusion Detection Systems (IDSs) are among the mostly used security tools in computer networks. While they are promising technologies, they pose some serious drawbacks: When utilized in large and high traffic networks, IDSs generate high volumes of low level alerts which are hardly manageable. In addition, IDSs usually generate redundant or even irrelevant (false) alerts. One technique proposed to circumvent such drawbacks is alert correlation, which extracts useful and high-level alerts, and helps in making timely decisions when a security breach occurs. This thesis will survey current alert correlation techniques, and introduces a real-time and data-mining–based algorithm for alert... 

In order to control accesses in semantic environments, a semantic-based access control and policy specification language should be choosen. Upon to them, some security mechanisms should be designed and implemented. Several access control models and policy specification languages have been arisen, but seldom have focused on designing mechanisms to satisfy their models in any environment. In this thesis, we focus on implementation aspects of access control in semantic environments. We chose semantic web as our studying environment and an extension of the SBAC model named MA(DL)2 as our access control model. To control accesses in the selected environment, we divide semantic web into some... 

The purpose of this research is to monitor the health of structures using the updated finite element model, in which digital images are used to optimize the numerical model. Structural Health Monitoring (SHM) is always an important and significant issue that has attracted the attention of many researchers in recent years. In general, some researches have been conducted in this field using physical sensors that provide discrete data to the system for analysis. Using cameras to monitor the structure makes it possible to extract continuous and integrated data from the structure using digital images, which is a significant advantage compared to physical sensors.In this research, a steel... 

Although Machine Learning (ML) and especially Deep Learning (DL) has shown significant success in solving complex problems, recent studies have shown that ML algorithms are vulnerable to adversarial attacks. So far, ML algorithms have been designed to run in benign environments. However, the increasing use of ML algorithms in security-sensitive applications motivated adversaries to focus on their vulnerabilities. In the adversarial environment, an adversary can interfere in the training and inference processes of ML algorithms. Adversarial examples are one of the most critical vulnerabilities of ML models at the inference time. Adversarial examples are maliciously crafted inputs that cause... 

The formation of gas hydrates in oil and gas industries has been the subject of long-standing problems. For example, the hydrate formation may occur and block gas pipelines which can lead to safety hazards. All of these will result in catastrophic economic losses and ecological risks. Therefore, various methods were developed to mitigate the formation of gas hydrate. In many cases, the hydrate inhibition by adding kinetic and thermodynamic inhibitors to the system is the only viable option. But recently using ionic liquids as novel hydrate inhibitors and the discovery of dual function thermo-kinetic inhibitors have been studied. In this project the performance of six imidazolium-based ionic... 

Aluminum Bronzes have many applications in marine environments. These alloys suffer from both hot cracking and cold cracking. In order to overcome the hot cracking and cold cracking, Semisolid Stir Joining method and a proper thermal cycle was used respectively. Effects of temperature, stirring rate, and tool type were investigated in Semisolid Stir joining method. In this method, butt joint design was used in order to place specimens, and the specimens were heated up to specific temperatures (920, 925, 930°C). A stirrer (Cylindrical and Grooved tool) with three rotational speeds (800, 1200, 1600 RPM) was introduced into the stir weld seam. Welded specimens were cooled to the 900°C... 

Deep neural networks attain high performance on many domains and gaining more attention from real-world businesses in recent years. With the emergence of Machine Learning as a Service (MLaaS), users have the opportunity to produce their model on these platforms and make it available to others through the prediction APIs. However, studies have shown that an adversary can produce a surrogate model with similar characteristics to the victim's model by accessing these APIs. Aside from ruining the victim's business plan, studies have shown that an adversary can implement more sophisticated attacks on the victim's model by accessing a surrogate model. Due to the adversary's inaccessibility to the... 

Polymerase Chain Reaction (PCR) is a process in which a special piece of a gene is amplified millions of times over a short period. The advancement of gene amplification devices over the past years and attention to droplet-based methods have led to the development of droplet digital PCR. This method is very accurate in the diagnosis of diseases, so it can identify several different types of defective genes at the same time. In the present study, a microfluidic droplet-based chip was designed and fabricated for digital PCR amplification. The chip consists of microchannels for droplet formation as well as a reservoir to store droplets. Droplet formation was carried out by the flow-focusing...