Sharif Digital Repository

Today, the world is facing the limited resources of fossil fuels and the pollution caused by them. One of the best alternatives that can be offered to fossil fuels is the use of hydrogen in fuel cell technology. Polymer electrolyte membrane fuel cell is one of the types of fuel cell that has a significant advantage over other types of fuel cell in terms of low working temperature and high performance speed. In order to become more widespread, the fuel cell must be freed from the two problems of uncertainty and short life. These two factors can be improved by using a condition monitoring system in both stationary and transportation applications. By using continuous status monitoring and error... 

Polymer membrane fuel cell is a rich source of renewable energy. Two problems of short life and low reliability in fuel cells are the main problems of this system. The difference in partial pressure of hydrogen and oxygen causes serious damage to the fuel cell and inefficiency of the electricity production capacity. On the other hand, the life and optimal performance of the fuel cell depends on the moisture content of the membrane because the membrane needs sufficient moisture to pass ions. Transparent fuel cells can be used to study the water in the fuel cell. With direct imaging of this type of fuel cells, the phenomenon of water creation in the fuel cell can be studied with the help of... 

PMMA bone cement lacks biodegradability and the ability to bond with surrounding bone tissue. Therefore, the development of a new generation of bioactive bone cements that are biodegradable and possess adequate mechanical properties as well as desirable setting time is receiving remarkable interest.In this study, we have developed novel mineral-based bioactive bone cements. Our mineral bioactive bone cements were composed of Calcium Sulfate Hemihydrate, Bioactive Glass, and Tricalcium Silicate. Firstly, a binary system composed of Calcium Sulfate Hemihydrate and Bioactive Glass was optimized based on mechanical and setting behavior. Secondly, Tricalcium Silicate was added to the powder phase... 

The unique properties of phase change materials (PCMs), such as high latent heat and nearly constant phase change temperature, have made them a suitable option for use in thermal energy storage systems and thermal management systems. However, the low thermal conductivity of these materials has imposed limitations on their widespread use in industries. In this study, for the first time, the effect of injecting a boiling fluid (BF) into the PCM container to enhance heat transfer and accelerate the solidification process has been experimentally investigated. In this regard, paraffin wax and acetone have been selected as the PCM and the BF, and the effects of parameters such as the initial... 

Underwater robots are capable of performing a wide range of underwater operations such as research, sampling, hydrography, rescue, and more. These robots are generally categorized into two main types: remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs). AUVs offer significant advantages due to their lack of reliance on human operators, including extended operational range, longer operational duration, and reduced human risk. In the design process of any underwater robot, a specific dynamic model is developed based on the robot’s geometric features and the specifications of its appendages, including control surfaces, thrusters, and buoyancy tanks. This involves... 

Early detection of prostate cancer using biosensors has been a subject of research for nearly two decades due to its critical importance. The timing of detection plays a crucial role in determining treatment success rates. However, a significant limitation of these studies has been the cost and limited sensitivity of the sensors. In this research, various treatments used in biosensors were compared and necessary parameters to develop a sensitive, low-cost sensor have been subject of optimization. For this reason, we used pencil graphite and graphite sheet electrodes, both of which have potential for low-cost production on a large scale. Additionally, we tested graphene oxide, amine-treated... 

The challenges of urbanization have been the focus of researchers since the past. With the expansion of urbanization and massive migration of people from villages to cities, these challenges became more important in our country. These issues, which exist in many other countries in a serious manner, are discussed in the branch of urban economy in the world. This thesis is arranged in three chapters, in each of which one of the aspects related to urban economy and housing is discussed. In the first chapter, the effects of the construction of Mehr housing on the value of nearby residential properties are investigated using difference-in-difference method. It is shown that the construction of... 

The goal of this research is to elucidate the mechanism of Cell recognition in molecularly imprinted polymers (MIPs) using already utilized techniques. Our approach employs a more flexible non-covalent imprinting method which starts from a readily available polymer and utilizes an aqueous environment for both MIP synthesis and testing. Cell MIPs against MG-63 cell were synthesized. The synthesis procedure was optimized to obtain better binding characteristics to the targeted cell. Adsorption of target cell onto imprinted Alginate Spheres was facilitated by these macromolecular fingerprints as revealed by various microscopical examinations The imprinted Spheres showed high selectivity toward... 

Business Processes are a set of activities which is designed for produce specific output for specific customer or market. Nowadays business processes have a significant role in organizations and they progress to mechanized business processes and transform them to executable workflows. Existence of complex domains with particular requirements from one hand and scale of business projects on the other hand, make existing business processes, which only consider structure and flow of work, are not enough for fulfillment of organizational requirements. By provision of semantics into business processes, which Semantic Web technologies is used in them, business processes become more flexible and... 

Platelet-rich plasma as a juvenile to the narrow repertoire of orthopedic medicine, has risen hope to attain a generic autologous regenerative formula for different conditions. Vast plethora of GFs, cytokines and chemokines has endowed PRP with excellent regenerative properties, however not all of them would favor different conditions. Vascular endothelial growth factor has been demonstrated to be involved in the progress of Osteoarthritis by amplifying the catabolic processes which deteriorate the extracellular matrix of cartilage. Though cumbersome, the result of eliminating VEGF from platelet lysate would be promising. VEGF isolation from platelet lysate requires selectivity. By employing... 

The aim of this study is the fabrication of 3D porous PCL scaffolds contain core-shell fibers for cartilage tissue engineering. The novel fabrication method is co-axial wet electrospinning simultaneously. These tablets like scaffolds have superior porosity and pore sizes for cell culturing and cell-cell interaction as they have good mechanical properties for cartilage tissue engineering in comparison to 2D electrospun scaffolds. The structure of these 3D scaffolds is mimicking the ECM of cartilage. This study presents the coaxial electrospinning of PCL nanofibers encapsulated with bovine serum albumin and platelet rich plasma for demonstration of controlled release and bioactivity retention,... 

Due to largre number of patients treated by dialysis and its significant increasing progress, dialysis efficiency and patients' life quality are of great interest.Dialyzer, the dialysis beating heart, has the role of cleaning blood by removing toxic solutes and balancing volume of bood's water through hollow fiber membranes. In this thesis, firstly we tried to focus on performance characteristics of dialyzer by studying effective parameters influencing dialyzer efficiency and ultimately we set two important performance characteristics, ultrafiltration coefficient and solute clearance, as our goal parameters for evaluating dialyzer's yield. To this purpose, we designed an experimental set... 

After passing many iterations of tests, video games still suffers from major bugs after they’ve been released. One of these problems is the incompatibility between the video game and target audience’s computers. In this thesis, we have proposed a testing strategy by utilizing Cloud Computing infrastructure for video games and Deep Convolutional Neural Networks. We used a simple algorithm to make the graphical output of a video game partially deterministic and thus it’s possible for us to compare different instances of the game in Draw Call level. We’ve used two separate Deep Convolutional Neural Networks for 1. detecting visual artifacts in frames and 2. comparing pairs of Draw Calls for... 

The main goal of petroleum reservoir simulation is finding of Pressure (P) and Saturation (S) of fluid in different places of prose media environment of the reservoir in a specific time interval. In this project we will implement a distributed reservoir simulator of a cluster. In fact parallelization of reservoir simulator is finding a method to decompose the reservoir domain into some region and assigning each region to a computer in a cluster of parallel computers in order to minimize the total amount of dependency of regions to each other and messages between nodes in the parallel network according to fluid equation in the system and finaly minimize' the duration of simulation. In this... 

Thyroid gland is one of the important internal organs of the body that is responsible for T3 and T4 hormones secretion. Concentration of these hormones directly influences growth of body, thus measurement concentration of thyroid hormones is one of the most common experiments all of the world, specially in our country that Hypothyroidism is common among people. Secretion of hormones in thyroid gland controlled by TSH (thyroid Stimulating Hormone) that released from Pituitary gland. TSH concentration is opposite of level of thyroid secretion. Because of interconnected relationship between these three hormones, measurement of each of them is so important. Many researches for developing... 

The ongoing Covid-19 pandemic has driven our attention to a simulation of virus dispersion to complete our understanding of airborne transmission. A myriad of studies have shown that respiratory diseases such as MERS, SARS, and COVID-19 can be transmitted by virus-laden droplets released during coughs, sneezing, and normal breathing. To mitigate and prevent the spread of such infectious diseases, investigation of the transmission routes is of great importance. This study has been fueled to harness the CFD tool to simulate the virus-laden droplets dispersion in hospitals inwards. Because of the limitations intertwined with experimental works such as the risk of infection of experimenters, and... 

Drug delivery systems (DDS), which, are sensitive to tumor medium have high importance. one of the most important problem of current treatment of cancer is damage of the normal tissue, which, it is expected to solve by smart drug delivery systems. In such cases, one or more features of cancer medium cause to release of the drug. One of features of cancer medium is high concentration of reactive oxygen species and hydrogen peroxide in the most common between them. The purpose of this study is to build a drug delivery system, which it is sensitive to hydrogen peroxide. This carrier has 4 main parts. The first part is anti-cancer drug, which, it is located in the carrier. Second part is... 

Cancer is a class of diseases characterized by out-of-control cell growth. Cancer is among the leading causes of death worldwide.Cancer modeling is increasingly being recognized as a powerful tool to refine hypotheses, focus experiments, and enable predictions that are more accurate.We investigate a three-dimensional multiscale model of vascular tumour growth, which couples blood flow, angiogenesis, vascular remodelling, nutrient/growth factor transport, movement of, and interactions between, normal and tumour cells. We constructed a hybrid multi- scale agent-based model that combines continuous and discrete methods.Each cell is represented as an agent. The agents have rules that they must... 

Corneal diseases are one of the most common causes of blindness worldwide. The most common way to treat these diseases is to replace the damaged cornea with the donor cornea by corneal transplant. But limitations such as donor tissue deficiency, the risk of disease transmission and transplant rejection have made treatment of these diseases very difficult. A cornea made by tissue engineering can be used as a suitable alternative because of the limitations mentioned for corneal transplantation with donated tissue. At the same time, similarity of the scaffold to normal corneal tissue, both in terms of matrial and structural properties, is essential for proper repair of this scaffold by cells... 

The emerging blockchain technology has introduced a new approach in today's industry, creating new opportunities in technical, financial, and economic domains. With the emergence of blockchain-based platforms such as Ethereum and the capability of smart contracts, the possibility of creating decentralized systems has arisen. One of the most popular decentralized systems in the realm of finance is crowdfunding platforms that assist technical and academic projects in need of capital for industrialization. Startups or research-academic projects secure the necessary funding by selling initial offering tokens to both small and large-scale investors. In this research, we aim to present an...