Sharif Digital Repository

Today, accidents are considered as one of the main causes of human mortality in the world. According to the World Health Organization, about 1.35 million people die in accidents each year, and 20 to 50 million people are injured because of accidents. In our country, about 17000 people are killed in traffic accidents annually. The mentioned statistics clarify the significance of paying attention to traffic accidents and identifying the factors that lead to them, as well as considering the strategies and policies for reducing accident rates. Due to the fundamental role of human factors in the occurrence of car accidents, the use of models that include the personality and attitude of drivers... 

This thesis is concerned with the robust control of multiple integrator systems, subjected to input saturation and external disturbance. Since nested saturation method has been demonstrated to be an effective tool for control of a chain of integrators, a feedback law using nested saturation is proposed. In order to deal with disturbance, an extended state observer is applied to nested saturation controller and a comprehensive analysis of stability is also presented. The existence of constant parameters in the proposed controller makes the design conservative which results in performance degradation in some cases at the presence of disturbance. To overcome this issue, an adaptive approach... 

The Iranian Nuclear waste management Company is responsible for the safe disposal of the low-level radioactive waste resulting from the various processes of nuclear fuel cycle and other radioactive-related activities. The safety assessment of waste disposal requires the measurement of transport parameters of radioactive nuclides in the soil around the disposal site. In this project, the transport parameters of cobalt nucleus in the Naeein disposal soil were measured using two static (batch) and dynamic (column experiment) methods. In the static method, the distribution coefficient was determined by performing batch adsorption experiments, and then the retardation factor for the soil disposal... 

Algorithms for online identification of parameters of a satellite’s moment of inertia tensor based on two methods (recursive least squares and Kalman Filter) is presented and compared with each other. It is assumed that the satellite actuators are three orthogonal reaction wheels. The only available sensor is a 3-axis rate gyro, which measures the angular velocity of satellite in body coordinate system. For validation of algorithms on earth, a similar identifier was designed for a satellite simulator. Due to difference in Dynamics of satellite and satellite simulator, capability of identifying center of gravity was added to algorithms. In order to account for friction in air bearing of... 

In present work, hydroxyapatite nano-rods are synthesized using a simple sol-gel method with calcium nitrate and potassium dihydrogenphosphate as calcium and phosphorus precursors respectively and ammonia was used for adjusting the pH=9. To obtain rod shape hydroxyapaite powder, multi wall carbon nanotubes were added to the solution, nHA powder was calcinated at 60 and 450 ℃. In second step, chitosan-gelatin/nanoHA solution were prepared by blending chitosan and gelatin in different concentrations with nanoHA powder, then the solution was freeze dried to maintain a composite scaffold. The prepared HA powder and bio-composite scaffold were characterized by X-ray diffraction (XRD), field... 

Although voltage control and stability issues are not new to the electricity industry, but nowadays, in most modern power systems, special attention has been paid to this issue. Once, only weak systems with long lines were involved in voltage instability, while today due to heavy loading, voltage stability is a serious concern even in developed networks. Over tim, with increasing demand for electricity and emergence of electricity market and economic constraints, power systems are more exposed to voltage instability and even voltage collapse. Therefore, reliable operation of the system in such circumstances requires evaluating voltage stability of the network at both stages of planning and... 

With the growing trend of IoT, especially in critical areas like health system and city management, and the expectations of even higher growth with the advent of 5G networks, the security and preserving of users' privacy in IoT has gained significant importance. Anomaly detection is one of the approaches to monitor IoT devices which enables the identification of anomalous behaviors. This anomalous behavior could indicate malware infection, physical malfunctions, or tampering.Deep learning has been a common approach for anomaly detection for the past few years. The solutions are mostly suggested in a special purpose manner and because they are based on a particular deep learning model, they... 

Nowadays, various policies are adopted by transportation managers and planners. These policies aim to improve system performance, reduce user costs, control and reduce air pollution, reduce noise pollution, and ultimately reduce congestion. A set of these policies in the form of transportation demand management is presented in the literature. A common way to find the effect of a policy on user behavior is to use questionnaires. Other causal inference models have been proposed in disciplines such as statistics, political science, marketing science, epidemiology, and psychology. The purpose of these models is to find the causal effect of an intervention (treatment) on a system. These studies... 

It is difficult and time-consuming to calculate the reaction rate directly. For turbulence modeling methods such as RANS or LES, various statistical methods are used to model turbulence-kinetics interactions. The purpose of this study is to implement the linear eddy model in CANTERA open source-code. This code instantly simulates one-dimensional, quasi-one-dimensional laminar flames with different chemical kinetics in which the effects of viscosity and molecular diffusion are implemented like a laminar flame. The effects of turbulence are simulated by a series of stochastic processes called triple maps. This research can provide a linear eddy model in different types of one-dimensional... 

As the number of patients waiting for receiving kidney transplantation increases all over the world, the average waiting time for a patient in queue rises too, and consequently, the rate of death goes beyond the accepted level. Also, unbalanced numbers of donors and patients with same blood type make the problem bolder. The aim of this research is to design a queuing model in which kidney could be transplanted from deceased donors to patients with different but compatible blood type (Cross-Transplantation) in order to make the average waiting time for patients with different blood type closer to each other. In other words, the transplant system is supposed to make a decision whether to... 

The blood pressure (BP) is one of the most vital signs to monitor human health. Hypertension is a major public health problem that is associated with morbidity and mortality. In the past decades, the number of people with hypertension disease has been increased. According to Ministry of Health, 54 percent of hypertensive patients are unaware of this health threat. Therefore, accurate and continuous measurement of BP is essential for its prevention and treatment. Traditional non-invasive methods of BP monitoring use an inflatable cuff, which causes discomfort due to occlusion of the artery and can not be used continuously. Numerous studies have attempted to present methods without using a... 

Dye-sensitized solar cells (DSSCs), belonging to the third-generation of photovoltaic cells, aim to mimic the process of photosynthesis for electricity generation. Titanium dioxide nanoparticles (TiO2) have been widely employed as photoanodes in DSSCs. However, the photoelectric conversion efficiency (PCE) of these solar cells is hindered by electron-hole recombination at the photoanode-electrolyte interface. To address this issue, two-dimensional graphitic carbon nitride (g-C3N4), synthesized from inexpensive urea, has been utilized to modify TiO2-based photoanodes. In this study, g-C3N4/TiO2 composite photoanodes with varying mass ratios were fabricated using an in-situ synthesis method.... 

In this thesis, we generalize the concepts of kernels, weak stationarity and white noise from undirected to directed graphs (digraphs) based on the Jordan decomposition of the shift operator. We characterize two types of kernels (type-I and type-II) and their corresponding localization operators for digraphs. We analytically study the interplay of these types of kernels with the concept of stationarity, specially the filtering properties. We also generalize graph Wiener filters and the related optimization framework to digraphs. For the special case of Gaussian processes, we show that the Wiener filtering again coincides with the MAP ‌estimator. We further investigate the linear minimum... 

The widespread use of the Android operating system has made it an attractive target for attackers. In the field of malware identification and mitigation, the use of machine learning methods has seen significant advancements due to their ability to identify unknown malware. One of these methods is graph-based techniques in constructing malware detection systems, which have achieved high success rates in identifying malware. However, machine learning methods suffer from the vulnerability of being misled by adversarial examples. One important aspect in both malware detection systems and adversarial attacks is the limitations imposed on software modification. Any changes made to the application... 

With everyday increasing application of gas turbine in different industries, fast and accurate tools for design, analysis and performance estimation of gas turbines have found many proponent; Compressors, as one of the most important parts of gas turbines, are no exception to this ordinance. Although development of Computational Fluid Dynamics (CFD) method was a great aid to improve the accuracy of this tools, complexity and being time consume make them uncommon and unpopular during preliminary design and analysis process. So it could be imply that simple analysis methods, such as 1D, 2D and quasi-3D, are not only not abandoned, but also very practical and most applied in preliminary design,... 

In this study we addressed the problem of separated waste management. Investigating the literature on location routing problem, reverse logistics, waste management, and countries’ performance in the field, we proposed a novel method for gathering household waste that inspired from prosperous metropolises and took into account the particular situations of developing countries. As a matter of fact, the proposed method is an extension of location routing problem; it’s a bi-echelon network of facilities and multi-compartment vehicles connected via reverse cross docks. The problem is formulated using a mixed-integer linear model with 3 economic, social, and environmental functions; with respect... 

Ground squeezing is defined as time-dependent shear displacement of rock mass that causes the decrease of the calculated excavation area of tunnels.Ground squeezing is one of the phenomenons that causes serious problems including the collapse of tunnels’ walls and TBM jamming during the construction of tunnels. Hence, the assessment of ground squeezing is an essential issue in tunneling. In this thesis, different ground squeezing potential prediction methods will be assessed. These methods consist of empirical, semi-emperical, analytical, and numerical methods. After assessing the ground squeezing potential, if it is evaluated high for a project, it will be required to consider the... 

The study of the interaction between ellipsoid particles and the flat wall is the basis for understanding phenomena such as the passage of colloidal particles through the membrane and the order resulting from the presence of the wall in liquid crystals. Previous studies on liquid crystal systems confined between two walls have shown that topological constraints and the surface interaction of particles with the wall change the order behavior and create a surface layer near them. The thickness of this surface layer is about a few molecules, and this helps to achieve the result observed in the laboratory, in computer simulations. LAMMPS software is one of the most powerful codes available for... 

In general, separation of gas mixtures is grouped in three different methods: adsorption and dissolve methods, membranes and filter methods, and cryogenic methods. One of the most novel and efficient techniques in the latter method, is the supersonic separation where all the expansion, liquefaction, and separation processes are performed within a converging-diverging nozzle with no complex or moving part. This research is focused on methane purification. A one-dimensional model is developed for design and performance analysis of supersonic separators incorporating real gas model, variable specific heat, condensation, and swirling flow. Further, an axisymmetric numerical simulation of the... 

In this thesis the hourly concentration of different gaseous air pollutants in Tehran is modeled using Land Use Regression (LUR) and Artificial Neural Network, separately. Both models are provided with the same set of input data; the first step is to find these data. Since traffic affects air pollution, information about traffic conditions is one of the main inputs in air pollution modeling. Therefore, to obtain traffic information, in this thesis, first a novel method is developed to extract and analyze Google Maps traffic data. In this method, image processing is used along with the Geographic Information System (GIS) to count the number of pixels of different traffic colors for each road...