Sharif Digital Repository

Controlling the nonlinear processes is very important in industry. In this thesis, model predictive control is considered as a nonlinear control strategy and two nonlinear models, namely wiener and Hammerstein models are used and their identification methods are described. State-space model is also considered and closed-loop stability has been studied. Another strategy for controlling the nonlinear process is global linearization control. Some concepts and related theorems for this strategy are stated. PID controller is used as a linear controller for this strategy. In this model for estimating the state and load, two nonlinear observers are used. Stability analysis of output feedback... 

Airport Traffic Control Towers (ATCTs) are among the most critical structures in an airport that are expected to keep their level of serviceability after severe strong earthquakes. Therefore analysis and design of these structures need a detailed investigation on the seismic behavior of the structure based on the structural characteristics. In this study three different existing reinforced concrete ATCTs have been investigated. As important parameters of earthquake design of structures, response modification factor (R-factor) of these towers will be determined. R-factor reduces elastic force level to design force level and contains the effect of ductility, overstrength. In Iranian seismic... 

The objective of this thesis is to investigate the application of graph theory in managing emergency evacuations of passengers from airplanes and space stations. Given the critical importance of passenger safety and the necessity for optimized design of emergency evacuation routes, this research aims to provide a mathematical and analytical framework to reduce evacuation time under critical conditions. Common methods in this field are typically based on costly and time-consuming simulations that require significant financial and temporal resources. Instead of relying on these approaches, this study explores the application of analytical and mathematical methods, particularly graph theory.... 

Recent violation of security properties of e-voting protocols not using provable security, indicates the importance of provable security. In this thesis, we use the provable security approach to analyze security properties of e-voting protocols.In addition to presenting an efficient and provably secure protocol, the minimal assumptions to achieve privacyin e-voting protocols are analyzed. The firstcon-tribution of this thesis is presenting an efficient and provably secure coercion-resistant protocol, which is a variant of the JCJ e-voting protocol (Juels et al.,2010). It decreases the total number of JCJ’s operations fromO(n2) to O(n). The second contribution of this thesis is proving the... 

In the contest of conversion of water to hydrogen and oxygen there is a need for catalysts which will effectively support the oxidation of water. In nature, photosystem II relies on manganese for the oxidation of water. The water oxidizing complex (WOC) contains a cluster of four manganese atoms. In the past few years, there has been a tremendous surge in research on the synthesis of various manganese compounds aimed at simulating WOC of PS II. In this project, several manganese oxides as heterogeneous catalysts in water oxidation have been synthesized and characterized by FT-IR, X-ray diffraction, TGA, XPS, SEM and BET. Some of these oxides are able to oxidize water in the presence of... 

Multicore platforms prepare a great opportunity to implement fault-tolerance techniques. Task replication is a well-established technique to obtain high reliability against transient faults. However, replicated executions can increase power consumption more than Thermal Design Power (TDP) constraint. TDP is considered as the highest sustainable power that a chip can dissipate before being forced to exploit a performance throttling mechanism, e.g. Dynamic Thermal Management (DTM). If the chip violates its TDP constraint, it automatically restarts or significantly reduces its performance to prevent a permanent damage. Therefore, due to the unwanted system restarts, DTM techniques may not be... 

The primary objective of this thesis is to provide solutions addressing some security loopholes in continuous variables quantum key distribution protocols. The coherent detection method is utilized in this particular quantum key distribution scheme, which is a phase-sensitive detection. To measure in the quantum noise limit in the detection part, we need a local optical oscillator, which must possess a high intensity and a consistent phase correlation with the quantum signal. Therefore, reconstructing the emitter’s reference phase in the receiver’s detection system is considered as one of the most critical challenges in these protocols. In order to attain this goal, in the early versions of... 

In most of the engineering applications, the mechanical behavior of materials in high strain rate deformations differs from their behavior in quasi-static deformations. In some engineering problems like impact loading on structures, metal forming and explosive forming, the range of strain rate is about . Taylor impact test is one of the experiments used for characterizing the dynamic behavior of materials in high strain rate deformations. In the Taylor impact test a rigid cylindrical projectile is impacted normally onto a hard and massive surface (anvil), the projectile deforms by mushrooming at the impact end. With plastic wave propagation analysis, the plastic deformation of projectile is... 

Safety is an important factor in the nuclear power plants due to its inherent human and environmental hazards. Therefore, in order to ensure the safety of the plant and proper functioning of its various components, a series of commissioning tests should be conducted according to international nuclear power plants standards, before its operational exploitation. On the other hand, safety of the plant can be guaranteed by modeling transient states and possible scenarios of accidents in different situations. In this study, a commissioning test of Bushehr Nuclear Power Plant (BNPP) and its associated accident is modelled by gathering geometric data and information about the facilities... 

The air distribution is the main factor of contaminant transportation in cleanrooms. The experimental method is the most reliable one for investigation of flow field, which the difficulties associated with it, has limited not only the examination of the flow field in cleanrooms, but also the improvement of their qualities. Most of the experimental researches in indoor air quality concern conventional rooms and do not take into account specific supply-exhaust diffuser configurations, which are used in cleanrooms. Using small-scale models can reduce the complexity and the cost of measurements. In this research, the 3D velocity field of a small-scale cleanroom is measured in three different... 

In the first part of this thesis, the application of metal oxide nanoparticles in oxidative degradation of methylene blue is discussed. Nanoparticles of manganese tungstate (MnWO4) were prepared via an impregnation method using Mn(NO3)2.4H2O and WO3 as a source of Mn and W, respectively. The morphology of the manganese tungstate nanoparticles was studied in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). MnWO4 nanoparticles showed severe catalytic performance for the degradation of organic dye (methylene blue) in the presence of tertiary-butyl hydrogen peroxide, TBHP, as the oxidant at room temperature in water. Mn doped ZnO... 

In this study, the revolving door effect on the bank’s performance is investigated through two paths: return on assets as an expression of banks' performance and capital adequacy ratio as a bank financial health indicator and the quality of central bank supervision. We assume these two variables are affected by conflict of interest. The form of conflict of interest used in this research is revolving doors. The board directors of commercial banks, who have previously worked in the central bank, create conflict-of-interest data. Twenty-seven commercial banks were investigated in this research between 2012 and 2022. the conflict-of-interest gap variable was defined in order to separate the...