Sharif Digital Repository

The purpose of this study was to find the optimal position and slip force of friction dampers, for improving the seismic performance of regular and irregular steel structures and comparison of dampers final pattern of these buildings.In this regard, one to six floor regular and irregular buildings were designed. These buildings were modeled three-dimensionally in the OpenSees Software, and were subjected to horizontal components of seven far field accelerogram in order to investigate the need for their rehabilitation. The results of the time history analysis of these buildings showed that inter-story drifts exceeds the acceptance criteria which has been assumed 2.5% according to the Life... 

Nowadays, extensive use of Hardware Trojan Horses (HTH) or backdoors is more prevalent than ever. We could count disruption, disabling, eavesdropping and sending out internal information as misuse.
In this project, we embed hardware trojan in a Programmable Logic Controller, and present different methods to detect and neutralize them. This is an important issue, as PLCs should work in a safe environment especially in industrial environments while keeping the information intact is significant as even a slight intentional malfunction could cause data to be lost or disclosed, and result in a catastrophe. Subsequently, features of hardware of PLCs should be examined and the right place of... 

Today, incremental manufacturing processes are rapidly evolving and expanding. These processes are used for the rapid fabrication of prototypes as well as the fabrication of parts with high geometric complexity and high dimensional accuracy. These processes are used in various fields such as manufacturing industrial parts, medicine, precision casting, etc. One of the most important incremental manufacturing processes that has received much attention today is the selective laser processing process. One of the problems of this process is the limitation in the use of different polymers for processing. Polyamide 12 currently has about 90% market share due to its high processability. However,... 

For the preliminary design of isolated structures, it is necessary to select the appropriate damping ratios in each mode. The inherent modal damping in this type of structures is small. On the contrary, a significant value of damping is induced by dampers in isolator system into structural modes. The purpose of this study is to determine the Modal damping ratios in isolated structures. In this regard, shear structures of 2 to 10 floors with linear behavior in both superstructure and isolation level have been analyzed. The Structures have been modeled taking advantage of OpenSees. Samples are analyzed under sinusoidal loading applied to each floor. In order to achieve modal damping, an... 

Garbage leachate which contains suspended and soluble pollutants is produced due to the decomposition of organic substances by microbial activities. Moreover, other sources of water such as surface runoff, rainfall, and groundwater – which in many cases may percolate through the garbage-, can intensify leachate production which in turn imposes considerable impacts on the main elements of the environment, such as water, soil, and air, and has health effects on human beings. Therefore, minimization of leachate production is an important issue in the solid waste management considering economic, social, cultural, and many other aspects. On Kish Island, despite the favorable climatological... 

Drilling fluid is one the most important part of drilling operations in the oil and gas wells digging. From an economic point of view, almost 25 to 45% of drilling costs are allocated to drilling fluid. Drilling fluids consist of several components with different physical and structural forms which can be assumed as complex fluids. Optimum performance of the drilling process could be obtained through the dynamic fluid computation which requires a reliable mathematical model capable to predict transient-state and steady-state rheological behavior of drilling fluid. Generalized Newtonian models, such as the Bingham-plastic model, the power model, and the Herschel-Bulkley model, are the most... 

This thesis presents the synthesis of terpolymers composed of acrylamide (AM), styrene (St), and maleic anhydride (MAH) monomers, utilizing varying concentrations of the reaction components. The synthesis was conducted via inverse emulsion of water in cyclohexane (20/100), employing AIBN as initiator and Span80 as a surfactant. Various analytical techniques, including FTIR, NMR, SEM, viscometry, DLS, GPC, EA, EDS were performed on the samples. Additionally, the impact of polymer addition in water on the reduction of pressure drop was evaluated. Acrylamide is an inexpensive and water-soluble monomer that serves as a primary building block for producing high molecular weight polymers that are... 

Viscosifiers or thickeners are responsible for regulating the rheological properties of fluids to control flow and are widely used in various industries. Polyacrylamides modified with hydrophobic groups are among the most important viscosifiers in various industries, which are mainly produced by two methods: inverse emulsion polymerization and micellar polymerization. The aim of this study is to compare the two mentioned polymerization methods for the synthesis of polyacrylamides modified with hydrophobic groups with acrylamide monomers (main monomer), styrene (water-repellent monomer) and maleic anhydride (hydrophilic auxiliary monomer) and also to compare the effect of using two different... 

Today air pollution has become one of the major urban management concerns. Air pollution could have dangerous effects on human health in short time or long time in many situations. Numerical modelling is one of the most applicable among different ways for predicting pollutant concentration like field measurement, physical model in wind tunnel, and simulation. Modelling of pollutant dispersion is a way for estimating concentration and aggregation of the pollutant near the surface and with different distances from pollution source. In different dispersion models, one of simplest is the Gaussian model. In this approach it is supposed that emission plume obeys from Gaussian distribution and is... 

• Brachiation robot is a kind of under-actuated robots. A brachiating robot is a type of a mobile arm that is capable of moving from branch to branch similar to a long-armed ape. The purpose of this thesis is control of a two link Brachiation robot. The purpose of this thesis is control of a two link Brachiation robot using neural network and geometry control. For this purpose a genetic algorithm based training Neural Network is used to produce a suitable path for the second link of the robot and then using input-output linearization method, the second link is controlled to follow the path. The simulations shows that the Nero Controller designed in this thesis is suitable. The controller can... 

With the advent of quantum computers, the security of cryptographic primitives, including digital signature schemes, has been compromised. Therefore, a kind of signature scheme has been introduced to resist these computers. These schemes are based on hard problems that have so far resisted against quantum computers, known as post-quantum schemes. One group of these schemes is based on the hard problems of coding theory, which are called code-based cryptographic schemes. The first code-based cryptosystem was the McEliece encryption scheme. A number of code-based signature schemes are based on the McEliece encryption scheme. Some of these schemes use three matrices including a non-singular... 

As the global demand for data has continued to increase exponentially, researchers have begun exploring the concept of semantic communication as an effective tool to meet this demand. Semantic communication transcends the boundaries of conventional telecommunication systems, focusing on the transmission as well as accurate retrieval of meaning at the source and destination, respectively, rather than transmitting and recovering merely symbols. One approach in semantic communication emphasizes the significance of information, rather than its meaning, to achieve efficient and goal-oriented communication. One key metric in goal-oriented communication is the Age of Information (AoI). AoI is a... 

Dry reforming methane is a process during which two greenhouse gases, CH4 and CO2, using Ni-based catalysts, are altered into valuable H2 and CO gases, which are very useful from an economic and environmental point of view. The main problem with Ni-based catalysts is the formation of carbon in the dry methane reforming, which leads to rapid deactivation of the catalyst. In this research, a 10Ni-5Co/Al2O3 bimetallic catalyst was prepared by one-pot microwave-assisted combustion synthesis with a stoichiometric amount of fuel (urea) and without the use of additives. The catalyst was then calcined for 12 h at 550oC. The structure, chemical composition, particle distribution, and morphology of... 

Fixation devices and implants are the most applied devices in orthopedic operation and dentistry. Interference screw is one of these devices that is made by biodegradable nanocomposite polymeric materials in this project. The purpose of this project is designing interference screw, applicable to body, and doing related tests since in vivo tests. For this purpose, hand injection molding, was designed to prepare screws in laboratory scale, first. For making samples, poly(D,L) lacticacid, nano hydroxyapatite as reinforce and polyethylene glycol as plasticizer were used. These samples were made by combination of solvent casting and melt processing methods. Adding nano hydroxyapatite and...