Sharif Digital Repository

In the recent years, increasing concerns about the environmental issues necessitatecientists and industrial people to introduce clean and zero emissions vehicles to the global market. Relying on this acute demand,Hybrid Electric Vehicles (HEVs) are knownas one potential solution to lessen the negative effects of transportation industry on ecological systems.HEVs combine an Internal Combustion Engine (ICE) with an Electric Motor/Generator (EMG) and an Energy Storage System (ESS) to produce a fuel efficient and low or zero pollutant powertrain. Increasing the number of components in the powertrain requires a sophisticated strategy to control all drive-line components suitably. Surely, the best... 

Hole-transporter-free perovskite solar cells with structure of TiO2/ZrO2/C triple-layer scaffold filled with perovskite are great alternative to the conventional ones due to the possibility of making full printable low-cost and stable devices. In the present work, the impacts of the structures of the quadruple layer scaffold in the form of TiO2/ZrO2/NiO/C and triple layer scaffold in the form of TiO2/ZrO2/C on their photovoltaic performance are studied. In addition, the effects of thickness and deposition method of each layer were investigated as well as the effect of compounding of the carbon counter electrode. All devices were constructed by a simple printable method. Electrochemical... 

Analysis of performance of fetal heart is very important for monitoring its health. In recent years a lot of research is performed on recording electronic signals from mother abdomen which consist of combination of maternal ECG and fetal ECG. Purpose of this thesis is investigating methods. For evaluation of different methods simulated ECG dataset and Dalsy dataset as real data were used. In this thesis Wavelet and EMD denoising as single channel methods and ICA, PiCA and deflation as multichannel methods are used. At last novel combinations of these methods is proposed which outperforms existing methods  

Interictal EEG signals are very critical in diagnosis of epilepsy. Analysis of interictal EEG signals is very challenging due to contamination by various undesired signals like background EEG, muscular activity, noise, etc. Thus denoising of interictal signals has been an active research field in recent years. Primary purpose of this thesis is to denoise interictal EEG signals by using different combinations of ICA-based and wavelet denoising approaches. Then a new direction is pursued by using Morphological Component Analysis (MCA) which is a method for solving source separation problems based on morphological diversity of sources. Afterward MCA is modified by considering more prior... 

In present research in-situ groundwater remediation by permeable reactive barriers is considered and the main goal is to find the optimal dimension of reactive walls and also to find the most efficient reactive media. Here, computer simulation is done via MODFLOW. Different barrier lengths, widths, depths and distances between trenches have been considered and contaminant removal percentage calculated in all situations. Based on the research achievements increasing the barrier length has led to reduction of contaminant removal percentage because flow gradient and flow density decrease by length increase. As the results show, contaminant removal percentage increases by width increase because... 

Peak Floor Acceleration (PFA) is a necessary requirement in Industrial Buildings for the design of equipment, piping, cable tray and ventilation duct supports. The seismic analysis of equipments needs the determination of PFA at the points where the equipments are fixed on the supporting structure. The classical spectral methods (SRSS, CQC) do not allow this determination which can be done in using the time integration method. This last approach needs to perform numerous calculations with various realizations of the seismic excitation. This thesis aims to present a method allowing calculating the response properties of a linear elastic shear building structure loaded by a transient... 

The short life of Polymer Electrolyte Membrane (PEM) fuel cells is one of the critical criteria to their commercialization. A longer operation life time should be achieved to reach high reliability, low $/kWh cost and to use fuel cells as economical alternative energy systems.Therefore,diagnosing degradation mechanisms and the causes of power loss in fuel cell life time is of great importance. Operating conditions affect output power density and performance degradation. To achieve maximum power generation through fuel cell life time, a model is needed which is able to estimate power density and performance degradation simultaneously regarding to operating conditions. In present work, a... 

The electric power industry is experiencing important changes brought about by the deregulation. Electric power generators and users engage in power transactions which take place over the transmission system and create losses. Transmission losses represent up to 1⎯5% of the total generation, and cost millions of dollars per year. Consequently, the problem of “who should pay for losses” arises and the satisfactory sharing of the transmission system utilization costs among all market participants has become a key issue. Unfortunately, losses are expressed as a nonlinear function of line flows, and it becomes almost impossible to calculate exactly the losses that are incurred by each generator,... 

This research investigates the possibility of using the component mode synthesis (CMS) method in experimentation. It should be noted that the original idea for this project originated from an industrial problem. The main issue in this problem was the lack of sufficient equipment to conduct tests on very large structural modes and the high computational cost for their analysis. Therefore, a test platform was constructed using a scaled-down sample (approximately 1:25) with connections that closely resembled real connections. This assembly was then tested separately, and the results were compared with analytical analyses. After updating and correcting the model in several stages, the structure... 

In this thesis, bayesian network has been used in analyzing the failure of a structural component. The design life of a structural component of a system can be limited or unlimited depending on the working conditions considered by the designers. However, usually during the operation of an industrial system or device, a structural component of it fails prematurely, in other words, its actual life is less than the design life. In this case, the failure must be analyzed to find the causes and factors. The method of work is such that first, according to the problem and the type of failure, the required analyzes and studies are considered. Then, a number of samples of the components, whose... 

This thesis examines the modal characteristics of the payload after connecting to the carrier via the adapter. Basically, the modal characteristics of a payload change after connection to the carrier due to the different stiffness of the coupling mechanism. In this report, it is attempted to split and model the assembly structural system into two substructures interconnected by the V band clamp mechanism. Then, each of the substructures analyze individually and the modal characteristics of the integrated system are extracted using the infrastructure coupling methods. The coupling method is the "Component Mode synthesis" (CMS) method and input data, dynamic and modal characteristics required... 

In this thesis, due to the importance of pressurized structures, method or methods that can be used to monitor the health of important structures, such as pressurized pipes (gas transmission and distribution lines or hydraulic lines), are considered. A key point in monitoring such structures is to ensure the function of pipes, elbows, Tee junctions, composite to composite and composite to metal joints. The topic that will be discussed more than anything else here is to monitor the health of the structure in the presence of cracks in some layers of composite pieces. In fact, it must be recognized before cracking occurs in all layers of composite pieces and causing overall damage to the... 

Interpreting data of infrastructures monitored to detect damage of a structural is one of the most challenging issues of structural health monitoring (SHM). Especially, when environmental factors such as temperature, wind and humidity affect the data and the situation become more complicated. In this study, two methods of analysis free model of moving principal components analysis (MPCA) and robust regression analysis (RRA) have recently been considered for monitoring infrastructures compared with a variety of methods of data interpretation and results are presented. In this study, the performance of different ways in different loading conditions and arrangement of sensors have been... 

Nowadays, the structural health monitoring is considered as an essential element in improving the performance of the structures. The role and importance of the issues in this area have been reached to the point that different ideas and policies are developed for the safety margin over the useful life of the structures. To analyze more accurately, a real model of a turbine blade is required. This issue would be taken into more consideration when the scale of the turbine gets larger. Changing of the design philosophies over time results in effective changes in the design process and maintenance procedures. Any single of these inspections has different importance according to users' demands. In... 

Retrofitting of old mechanical structures by composite materials is one of the most important issues of the world.High reproducing and replacement cost of structures leads to, researchers try to retrofitting old structures and increase their capabilities and so increase their service age. Their research results leads to decreasing cost in one hand and introduce new application of composites in aviation industry in the other hand.Retrofitting mechanical structures show us the important of elements with more stress than the others. The probability of failure is more in these element than the other that we call critical element.These elements in fact are critical parts of an aerial structures... 

Nowadays, some of the major problems of the airplane industry is that airplanes’ fleet are approaching to the end of their defined life, inability to buy new planes and obtaining aircraft’s parts for repairing process. Therefore, in order to increase the life of the aging aircrafts, some essential process such as modeling processes, identify principal structure elements to strengthen and repair them should be done to all these airplanes, all these processes refer as aging process. Aging programs initiated in some countries, such as America, Australia, Britain and Canada from about thirty-five years ago, technological approaches inventing new ways to start repairing worn metallic structures... 

The substructuring method provides a suitable tool to conduct modal analysis of large and complicated structures. In this method the original structure is decomposed into simpler and smaller substructures, and the dynamic properties of the resulting substructures are first evaluated independently. The original structure’s dynamic properties are subsequently estimated by coupling the substructures’ dynamic results. In this procedure, the boundary conditions need to be imposed in such a way that the overall behaviour of the original structure is properly represented. Substructuring method can be used in different types of dynamic analysis. The focus of this paper is on the modal type of... 

Climate change and its Environmental issues become fundamental challenges in recent years, and countries have to try find various solutions about it, such as developing renewable energy technologies. Multiple studies have been conducted on the importance of innovation in technology development and technological changes in different countries. Many studies have addressed the concept of the innovation system and evaluated the role of various institutions and actors. The innovation system as one of the concepts branched from the innovation system focuses on the importance of interactions between actors, the role, and nature of knowledge in a particular industry or sector. Hence, investigating... 

Asset pricing models are one of the most important tools in investment management and portfolio allocation. Multi-factor asset pricing models try to explain the relationship between risk and expected return through a limited number of macroeconomic, fundamental or statistical factors. Usually, these models are suggested based on the US market and its intrinsic qualities. Although, there are some similarities between the Iranian and the US market, these economies are structurally different and therefore, proposing a proper multi-factor model based on the Iranian market’s fundamental characteristics will greatly improve the understanding of risk-return relationship in this market. In this... 

Asset pricing models are one of the most important tools in investment management and portfolio allocation. Multi-factor asset pricing models try to explain the relationship between risk and expected return through a limited number of macroeconomic, fundamental or statistical factors. Usually, these models are suggested based on the US market and its intrinsic qualities. Although, there are some similarities between the Iranian and the US market, these economies are structurally different and therefore, proposing a proper multi-factor model based on the Iranian market’s fundamental characteristics will greatly improve the understanding of risk-return relationship in this market. In this...