Sharif Digital Repository

Using cryptographic hardware device is inevitable these days. Hence, the secret information inside these devices should be safe and non-attackable. Simple and differential Power analysis (SPA, DPA), a form of side channel attack, allows attacker to study circuit information leakage by analyzing and monitoring power consumption of a cryptographic hardware device to extract inside information and discovering the secret keys. In this thesis, first, a sample cryptographic hardware device is designed and implemented as an under attack system. Then, another device is designed as an attacker in order to attack the mention sample hardware by analyzing and monitoring its power consumption. A digital... 

Precise knowledge of the laws which govern a system is of interest for two reasons. First, it paves the way to understand the subtle behaviors of the system, which are not understandable from simpler models of the system. Second, it helps in the design of experimental requirements needed to observe these behaviors. The behavior of neutrons in a system, which could be a reactor or a detector, is stochastic from two perspectives. First of all, since the place of the atoms of a medium are randomly sited, at least from a neutrons point of view, the collision sites are random places, which contributes to the stochasticity of the transport phenomena. This type of randomness is somewhat similar to... 

The vortex tube is a simple device that injects compressed gas (air) tangentially into the vortex chamber through one or more injection nozzles. After entering, the flow becomes rotational and an axial cold flow goes towards the cold outlet and a peripheral hot flow goes towards the hot outlet. Besides all the different applications of the vortex tube, the main application of this device is cooling. Here, the goal is to optimize the geometry and physical conditions to improve the performance, which is done by using a commercial software and numerical analysis of a vortex tube to understand the flow physics and optimization. In this research, we use experimental and numerical data for... 

The purpose of this thesis is to design and implement a controller for a Ducted-Fan in the landing and take-off phase using a linear quadratic tuning method based on differential game theory. This is a control method with a robust control approach and tries to see all the disturbances and unmodulated dynamics in the form of the second actor and produce a control command according to the worst behavior of the second actor. For this purpose, 6 DOF Ducted-Fan have been modeled. then The proposed controller is designed for a linearized model around the hover point. In the next step, the performance of the proposed controller is compared with the SlidingMode Controller. Also, the parameters of... 

This thesis proposes a robust model predictive controller for airplanes that can handle severe crosswind and indeterminate conditions, such as ground effect, without prior knowledge of wind direction and magnitude. The controller is a combination of extended dynamic model control (EDMC) model predictive control and differential game using a 6DOF nonlinear airplane model developed in MATLAB. The controller's cost function is designed to minimize controller effort during maximum disturbance and tracking error of desired outputs simultaneously. Testing for the landing phase is performed using a control structure in MATLAB for the longitudinal and lateral planes of the airplane. The structure... 

In this research, a cooperative terminal guidance algorithm has been derived for simultaneous multi-interceptor collision with a target. This algorithm is obtained using the combination of model predictive control method and differential game theory. One of the features of this method is the calculation of the optimal guidance command in the form of an explicit relationship. Another feature of this method is its resistance to disturbances due to the use of differential game theory. The first innovation of this research is the use of this hybrid method to create a guidance algorithm, even in the non-cooperative guidance problem. The next innovation is in creating a cooperative terminal... 

This research presents three new guidance laws for trajectory tracking of an unmanned aerial vehicle in the presence of wind disturbances. The first method is a linear combination of line-of-sight and velocity-pursuit guidance laws, the parameters of which are tuned using a fuzzy system in an online manner. The second method is an adaptive optimal guidance law based on the differential game theory. The third method (main method) is a model predictive guidance law based on the differential game theory. In the main method, linear point mass equations of motion are used to predict the future path of the vehicle. Also, the linear model predictive control is used to achieve an optimal analytical... 

Control and reduction of gas turbines pollutants emissions are increasingly of major concern. Here we introduce and apply new algorithms for derivation of accurate and low cost skeletal chemical kinetics, optimization of global multi-step chemical kinetics, and optimization of geometry of Lean Premixed (LPM) dry low emission (DLE) combustors.A new reduction algorithm called SA-GEIE, based on sensitivity analysis of reaction mechanisms respect to ignition delay, flame temperature and pollutants concentration (NO and CO), is introduced. This algorithm is implemented to GRI-3.0 to produce a low cost methane oxidation skeletal mechanism with 118 reactions and 39 specie. The accuracy is assessed... 

In the current study, first, the presence history of dielectric barrier discharge (DBD) plasma actuator in flow control usages has been investigated. After recognizing the importance of plasma actuator in this branch of engineering, this active controller was modeled relying on computational fluid dynamics (CFD) knowledge to control flow separation. In order to model this actuator, physics based model called spilt-potential model and modifications done to improve it, were used. Using this model and solving two elliptic equations, electrical field and plasma charge density distribution are obtained in range of solution domain and body force from plasma actuator modeling in all computational... 

Designing Nonautonomous periodic systems such as helicopters, multirotors, monocopters or the dynamics of flapping wings requires stability analysis and careful examination in order to identify and determine their dynamic behaviour. In practice, analysis and design are interdependent and the design of nonlinear control systems involves an iterative process. To know the importance of identifying and to accurately implement methods to analyse this kind of systems in the field of aerospace, the flapping wing can be a good example. The issue of stability and the control of the flapping wings have not yet had a clear solution, and the current research including controller design based on linear... 

Nowadays, the axial transonic compressors are used widely in aircraft engines, oil and gas industry and etc. because of higher pressure ratio and more efficiency than the other compressors. The Major part of losses in transonic compressors is due to shock waves. In this study the idea of using Shock Control Bump as a passive flow control method has been used for weakening the shock waves. The Shock Control Bump is modeled with the Hicks-Henne function and added to the suction side of a section of the NASA rotor 67 blade. Validation of flow solver is done in both two and three dimensions. Single-point and multi-point optimizations are performed in the design condition and in two off-design... 

In the present work, the shape and position of internal cooling passages within an axial turbine blade have been optimized to achieve a uniform temperature distribution with the minimum cooling air flow while the maximum temperature is below the allowable value. Four cooling passages are made within the blade. The cross section shape of each passage is parameterized using a new method based on an 8-order Bezier curve. This curve which is represented in terms of Bezier control points has much flexibility and can produce a large variety of shapes. The shape of the blade surface profile remains unchanged during the optimization process. The numerical simulation has been carried out using... 

Streamline Curvature method is one of the most commonly used methods by industry for prediction of axial flow compressors. This method analyze axial compressor by solving radial equations in the meridional plane to locate streamlines and also by using empirical models to predict total pressure loss. Despite growth of CFD models, Streamline Curvature method has been considered as most practical method for compressor preliminary design and performance assessment because of it’s high speed and good precision. In the current work a C++ code (SLC) has been developed using streamline curvature for axial flow compressor performance analysis. This code receives compressor geometry, properties of... 

The development of the boundary layer and shock boundary layer interaction essentialy determine the performance boundaries of transonic aircrafts. Employing shock and boundary layer control has therefore a large potential for improving flight performance. Aerodynamic surfaces of these aircrafts usually have very closed design points and critical points so small changes in angle of attack and free stream mach number cause entering drag divergence. Adaptive wings are the aerodynamic surfaces that use additional devices to control the flow pattern for improvment of aerodynamic performance in different flight conditions. Shock Control Bump is a control mechanism that is used for shock wave... 

This dissertation is a survey on linear and nonlinear dynamics of single-walled carbon nanotubes (SWNTs) conveying fluid with different boundary conditions. A detailed review on Some of the most important studies on free vibration and instability of CNTs conveying fluid is done. By employing the nonlocal continuum field theory of Eringen and Von Karman nonlinear strains, an analytical model are developed. In linear analysis the natural frequencies and critical flow velocities are discussed. In nonlinear analysis effect of nonlocal parameter on Nonlinear dynamics of cantilevered SWNTs conveying fluid investigated by bifurcation diagram, phase plane and Poincare map. The numerical results... 

Social enterprises are organisations comprised of two conflicting logics: social and commercial. However, simultaneous commitment to both logics often leads to tensions, making social enterprises fragile organisations at the risk of mission drift. The extant literature on hybridity highlights two important overall strategies – integration and differentiation - for managing tensions. However, integration or differentiation alone can create additional problems, which is especially true in the case of differentiation, creating a situation comparable to black and white, with a salient faultline and heated conflicts. In this inductive qualitative case study, responding to the recent call in the... 

Previous studies and field evidences show that creating appropriate interactions between sales and marketing departments is a challenge for many organizations. The main objective of this research is to develop and elaborate a conceptual framework in which "cooperation mechanisms" between sales and marketing and it’s "consequences" determined and provide an explanation that shows how configuration of sales and marketing relationship affects its consequences. The results show that "organizational ambidexterity" is the core consequence in proper architecture of the relationship between sales and marketing. In the strategy literature, combination of the dual capabilities of exploration and... 

This study investigates the price elasticity of gasoline smuggling demand in Iran. For this purpose, a panel data of monthly gasoline consumption has been used that contains data for 160 regions of distribution for Iran's Oil Production Company between 2005 and 2014. The results of estimating the monthly elasticity of gasoline smuggling demand in each region show a significant impact of the gasoline price differential between Iran and its neighboring countries, as well as the distance of each region with the neighboring countries on the demand. The results of this study show that whenever gasoline prices increase inside the country, the inclination to smuggling has been decreased due to a... 

Today, many organizations are active in service industry, and many others are planning to take part in. Phone call is the simplest channel between an organization and the customers, and these organizations devise call centers to acquire, retain and create value for customers. On the other hand, human resource in call center is the key element to identify problems, and improve performance. This research aims to provide a competency model for a firm which provides access to internet and has a call center for after-sales support. BEI method with a process-driven approach was used to gather information from call center employees, and related themes were extracted from the information with theme...