Sharif Digital Repository

Nowadays, cardiovascular diseases are among the most prevalent cause of death worldwide. Besides, atherosclerosis is a cardiovascular disease happening with the continuous narrowing of vessels, especially medium and large-sized arteries. Moreover, the human aorta is vulnerable to this phenomenon. Atherosclerosis happens when the excess LDL in the blood flow penetrates the arterial wall. Then, the LDL is oxidized, thereby recruiting monocytes as the response against oxidized LDL. After monocytes enter the arterial wall, they differentiate and become macrophages. Macrophages then transform into foam cells by ingesting the oxidized LDL. The fatty foam cells are eventually responsible for the... 

To produce polyurea, a secondary or higher amine must be combined with a diisocyanate. For this purpose, we first combined diethylenetriamine, and hexamethylene diisocyanate, which did not have good mechanical properties due to the aliphatic nature of the molecules. Then, instead of hexamethylene diisocyanate, we used MDI, which was mixed using a mechanical mixer but became a paste that was not suitable for coating applications. To reduce the viscosity of MDI, propylene carbonate was added to improve mixing, but the gel time also increased. Because the solvent was non-polar and the amine was polar, it was decided to add the solvent, amine, and polyvinyl alcohol as surfactants to allow faster... 

Lightweight aluminum and magnesium alloy sheets do not generally possess as much strength as steel sheets and their strength need to be increased by a suitable process such as Accumulative Roll Bonding (ARB). One of the most important limitations of ARB is the low ductility and formability of the sheets produced by this process. In the present research conducted on the 5083 aluminum and AZ31 magnesium alloy sheets efforts have beem made to overcome this limitation by heating up the sheets whether during metal forming process as hot deformation or as distinct controlled annealing process subsequent to the deformation, in order to develop the application domain of the sheets. Results... 

Phospholipid membranes and vesicles play important roles in the cellular functioning, otein signaling and material transport inside cells. Protein-embedded vesiclesare also used for targeted drug delivery. In this thesis, we use molecular dynamicsmethods and study (i) the formation of vesicles from flat lipid bilayers (ii) the mechanicalproperties of vesicles under compressive forces (iii) the shape variations ofvesicles with and without transmembrane proteins (iv) protein clustering.We grow our vesicles from lipid bilayers, which may contain proteins with differentconcentrations. We start with a random initial distribution of proteins that allowsus to monitor the clustering and... 

Energy and environment crisis in past decades raised concerns about fossil fuels use and has accelerated renewable energy application in terms of solar electric, solar thermal and wind turbines. Due to the fluctuating nature in renewable resources, renewable electric power generation has a stochastic nature that makes it difficult to use by the electricity consumers. Energy storage plays a key role to put more control on renewable power generation.Lead-acid battery is a storage technology that is widely used in photovoltaic systems. Battery investment and maintenance costs account for a big part of photovoltaic system costs. Charging and discharging profiles of the battery has a great impact... 

The design and development process of menu systems has always been a focus of researchers and engineers in the fields of software engineering and human-computer interaction. Considering the large and complex nature of the design space, it is nec- essary to provide automatic methods that aid designers during the design process. In this study, natural language processing is used to investigate the semantic relationship between menu system commands. Users expect related commands to be conveniently located next to each other, and a properly designed interface satisfies this need. As a result of this research, a fast-text-based model is developed that uses the data of past menu systems. In a... 

The potential future use of hydrogen as a transportation fuel must be evaluated from a supply chain perspective. However, the main challenge in motivating the hydrogen supply chain network is the lack of existing hydrogen infrastructure. Strategic decisions for planning sustainable infrastructure can be analyzed hierarchically in time-related stages (2025-2030-2035). Meanwhile, a time- and location-based design has been specifically applied to a few selected ports in southern Iran, with limited focus on a national or countrywide scale. This study proposes a mixed-integer linear programming (MILP) optimization model to logically design the hydrogen supply chain, considering primary energy... 

There is a major interest to manufacturers of automobile and aerospace parts towards the tailor-welded blanks (TWBs) to reduce the weight and cost of the parts and improve their performance. In this work, formability of four groups of TWBs (two groups with similar thicknesses and different steels and two groups with similar steels and different thicknesses) are investigated. To produce the TWBs, DX54, E275 and E335 steel sheets were used. The results indicate that the inclined laser beam causes the sample failure from the weld zone in the tensile test. Setting the focal point on the top surface of the sheets results in enhancement of yield strength in comparison to the other positions. ... 

The purpose of this project is to correct the surface defects of the reverse osmosis membrane. The membrane tested in this project was a thin film made of three layers of polyester, polysulfone and polyamide. These three layers provide mechanical resistance to operating pressure, suitable substrate for polyamide layer synthesis and membrane selectivity, respectively.In order to improve the surface properties and modify the reverse osmosis membrane, it was first attempted to coat it with a protective layer of polyvinyl alcohol, then by modifying this layer and improving the properties of polyvinyl alcohol and synthesizing the sulfite agent on it by the esterification reaction, to the best... 

These days the usage of welded tailor blanks with sufficient stability and flexibility is accelerating rapidly in order to production of slighter parts and reduction of fuel consumption in transportation means. Therefore, the conjuncture of blanks by welding methods is highly considerable before forming and ultimate production. Friction Stir Welding is greatly appealing to industry as one of the newest methods of solid state welding in production of TWB blanks. In this research, the feasibility study of Friction Stir Welding of thin Al 1100 – H18 alloy blanks with 1.5, 2 and 2.5mm thickness has been evaluated first. After creation of sound welds with same thicknesses, Friction Stir Welding... 

Al 5083 is a non-heat treatable alloy that widely used in the aerospace and automotive industry due to its low density and high strength. However, poor wearing behavior and low elastic modulus restrict its engineering applications. Metal matrix composites (MMCs) have advantages of high strength and modulus by reinforcement of second phase. Also, MMCs have excellent dimensional stability, damping capacity and wear, creep and fatigue resistances as compared with the corresponding monolithic alloys. Vast loss in ductility and toughness occurs by non- deformable ceramic reinforcements. For the surface engineering purposes, ceramic particles are added in the surface layers of components, whereas... 

Emission of the greenhouse gases is a great concern and use of lightweight materials in transport vehicles has found a major importance in this respect. Metal/polymer laminated composites are of great interest due to their special mechanical properties and thoughness. Application of metal/polymer sheets is limited because of low bonding strength of metals and polymers in these sheets, which is not sufficient, to endure the stresses and strains during deformation processes such as deep drawing and bending. In this research, roll bonding of AA5052/Polypropylene sheets is investigated and the effects of bonding parameters on strength are evaluated and finally the bonding mechanisms during... 

This study provides a comprehensive understanding of the digital transformation process in a constrained environment, offering practical insights for practitioners and a robust basis for future academic research. Conducted within the manufacturing industry in Iran, this research explores how companies navigate and succeed in digital transformation under the constraints of global sanctions. Employing an extreme case study methodology, the research focused on a leading organization renowned for its innovation and patented technologies. This organization offered a unique perspective on digital transformation under restrictive conditions, meeting all requirements for an "extreme case" in... 

With the advancement of GPUs and the availability of massive datasets, the main reasons behind the emergence of large language models, human life has been profoundly impacted. Large language models, due to their numerous applications and their increasing development, have influenced various aspects of human life, and this influence continues to grow. As a result, large language models are being used to solve a wide range of problems. However, using these models for problem-solving requires appropriate training data and significant computational resources. Because deep models can be attacked, leading to the extraction of their training data, preserving the privacy of training data in the... 

Acidic gases separation from hydrocarbon mixtures is very important in natural gas industry. In this study, the separation of CO2 and H2S from CH4 investigates by experimental and molecular dynamics simulation approaches. For achievement to this goal, it is used two polymeric families, as be divided to polyurethanes and PEBAX copolymers. It is used 4 polyurethane membranes as are named PU-1, PU-2, PU-Ether, and PU-Ester from polyurethanes group. Also, it is applied 5 PEBAX commercial membranes have be known PEBAX-2533, PEBAX-4033, PEBAX-5533, PEBAX-4011, and PEBAX-1074. It is compared between simulation and experimental works and found that there is good agreement between... 

This study deals with the heuristic solution of flexible flow shop scheduling problems with unrelated parallel machines. No preemption of jobs is allowed. As an objective function, this paper considers the minimization of total tardiness. As a first step to propose solution, two different mixed integer mathematical models are developed which tackle the problem at hand. The problem is NP-hard and thus the developed mathematical program can only solve problem instances for small sizes in a reasonable amount of time. The next step is to build heuristics which can provide feasible solutions in polynomial time for larger problem instances. Then in the study develops a constructive heuristic for... 

In this study, membrane distillation process was used for treatment of high salinity waters. The focus of this study is to simulate and build a setup of membrane distillation process. Since the membrane distillation process is based on the driving force of the temperature difference, the required temperature is provided by both the use of heaters and the use of solar energy. To increase the feed temperature by solar energy, a black polymer coating on the main membrane is used. The main membrane used in this process is PVDF polymer and the polymer coated on the surface is the PAN polymer. After simulating and constructing the laboratory setup, the influence of a variety of parameters on the... 

Study of the structural flexibility of large-scale wind turbine components on aeroelastic performance is important under the existence of critical atmospheric conditions. Prediction and control the critical deformations, identifying maximum local deformation and modeling the forces involved, are required. Aeroelasticity analysis is a suitable method for studying the coupling effects of wind turbine aerodynamics, dynamics and structures. This research has been done by modeling wind turbine components including blades, hub, nacelle and tower, taking into account aerodynamic couplings, dynamics and structures. Considering the large scale of reference wind turbine, nonlinear equations have added...