Sharif Digital Repository

In this project, the physics of the thermal infrared spectrum was first studied, focusing on thermal modeling of hidden objects, and field experiments were conducted. Then, with the main goal of the project, which was to design and build an economical thermography system to be used as a complement to other scanners such as millimeter wave or X-ray, the main parameters of thermal infrared image detectors (FPA) available on the market were reviewed and the appropriate option was selected and purchased. In the next step, a comprehensive study was carried out on the specifications and performance of the selected sensor, and the image reconstruction mechanism was described and implemented in... 

The applications of science and technology of materials grows rapidly nowadays One of the major aspect of this science discuss about the growth of thin films via deposition of molecules and atoms. By this way we can diagnose physical and chemical properties of thin films whose applications in electronics, computer, microelectronic industry, material engineering telecommunications and so advances every day. In this way we smell out the process of the growth of diamond like carbon (DLC) thin films whose importance is extended nowadays. By acknowledgement of variables that influence the dynamics of film formation we make a big jump in attaining the optical, physical and electrical properties of... 

Transonic speed is one of the most important flight regimes. There are two main significances related to it. First, all of the supersonic air vehicles should pass through this regime to reach to their final speed. Second, nowadays most of the commercial airplanes fly in nearsonic speeds. According to nonlinear nature of the flow through the speeds, the related researchers haven’t been successful in development of a comprehensive theory as well as subsonic and supersonic ones. So, transonic flow is one of the most critical regimes in wind tunnel testing. In order to eliminate the shock-boundary layer interaction and wave cancellation, perforated walls and side suction are used in test section... 

This project is aimed to design a controller for nonlinear systems that satisfy a prescribed performance while guaranteeing close-loop stability. To do this, the controller must be designed in such a way that the transient response of the system has had these performance indices and does not exceed them. These performance indices predefine some constraints for systems’ output.A comprehensive form for the model system, the unknown dynamics of the system, consideration of a variety of constraints on the system input, usage of the time-finite method for the residence time and consideration of just one tuning parameter to reduce the computation load, are among the other benefits for the proposed... 

Plasma Electrolytic Oxidation (PEO) method was used for the preparation of ceramic coatings on Aluminum 5052 substrate in a silicate-based electrolyte containing different concentrations of ZrO2 nanoparticles. Before the addition of nanoparticles into the electrolyte, determining process parameters including current density, coating time, and frequency were examined carefully. After studying corrosion behavior, thickness, and coating morphology in different circumstances, the frequency of 50Hz, the current density of 150mA/cm2, and the coating time of 20 minutes were chosen as the optimum parameters. After that and with the usage of those parameters, ZrO2 nanoparticles were added to the... 

When we talk about the large-scale structure of the cosmos and the cosmic web, one of the important issues is to examine the location of the structures formed. We use statistical characteristics to check the cosmic web. Nearest neighbor distribution, two-point correlation, count in cell, etc. are some of the parameters that help us in this way. Our main problem in this project is to examine these statistical parameters in large scale structure for two different time periods. First, in the time period near the present age(z ≈ 0), we want to check these parameters for the dark matter halos that have formed the structure, and secondly, for the initial conditions and transition to high... 

This research is dedicated to specific issues in the field of Aerial Vision Based Navigation (VBN). It focuses mainly on vehicles with no pilot such as RPVs and small aircraft; having in mind their safety which must be close to commercial applications. Various methods have been studied and the simplest one; which is based on observation, identification and utilization of landmarks is selected for detailed implementation. In this work, we concentrate on using a single-camera while flying in an unknown environment (MonoSLAM). Other available sensors are accelerometer and GPS receiver to keep the cost down. Different studies show that using a low-cost single camera system is much more efficient... 

In this project, bioleaching has been investigated as a solution for detoxification and metal recovery of spent hydrocracking catalysts of Tehran petroleum refinery which is listed as a hazardous waste. In this project four stages has been accomplished as follows: 1- Adaptation of Penicillium simplicissimum and Aspergillus niger with different heavy metals present in a spent hydrocracking catalyst, individually and with mixture of metals as well as adaptation by spent catalyst which the cumulative action of multi-metals enhanced the toxic effect; 2- The one-step, two-step, and spent medium bioleaching of the spent catalyst by the adapted fungi in batch cultures were investigated and... 

An assessment of the relative speeds and payload capacities of airborne and waterborne vehicles highlights a gap which can be usefully filled by a new vehicle concept, utilizing both hydrodynamic and aerodynamic forces. A high speed marine vehicle equipped with aerodynamic surfaces (called a Flying Boat, 'Aerodynamically Alleviated Marine Vehicle') is one such concept. The purpose of this thesis is to evaluate the performance of a Flying Boat before take-off in head sea condition. First, performance will be assessed in calm water, and then will be evaluated in waves. Performance is defined as the variation of Resistance Force and Trim Angle of a vessel in an arbitrary interval. This... 

Design, fabrication and performance of the reciprocating micropumps with actuated fluid slug have been investigated. In these micropumps, pumping principle is based on reciprocating movement of a fluid slug. The fluid slug must be conductive in magnetohydrodaynamic micropump to be actuated by Lorentz force and have good magnetic properties in ferrofluidic micropumps to be actuated by an external magnetic field.
On the other hand, a theory is developed in ahead of design and fabrication process to diagnose the critical and the most influential parameters. Magnetohydrodynamic micropumps in 4 distinict design using nozzle-diffuser element, passive ball valve and active mercury valve have... 

Soil-Structure Interaction (SSI) has been widely studied theoretically and experimentally due to its importance effects on the responses of structures. In experimental studies, acceleration responses recorded during previous earthquakes are generally used in order to investigate the contribution of underlying soil to the response of soil-structure systems. Since acceleration responses are affected by higher modes of vibration, studying the effect of SSI on dynamic characteristics of higher modes are of great importance in these studies. However recent theoretical studies indicate that the influence of SSI on the higher vibrational modes is very much dependent on the behavioral model (bending... 

In this study, the factors affecting cavitation in the crest of an ogee spillway were investigated. One of the factors affecting the occurrence of cavitation on the ogee crest is the ratio of the head to the design head. As the head ratio increases, the probability of cavitation on the crest increases. The value of the head is also an effective parameter for the occurrence of cavitation. The spillway crest curve is also one of the factors affecting the occurrence of cavitation on the ogee-crested spillways. In this study, the ogee crested spillway that consists of three circular arcs upstream has been investigated. 5 different head ratios have been used. For this study, OpenFOAM software,... 

Internal corrosion is one of the most common defects in pipelines. In recent decades, the use of offshore natural oil and gas resources has increased dramatically, followed by the use of offshore pipelines to transport products. At the same time, numerous accidents and explosions in offshore pipelines and their economic and environmental consequences underscore the importance of ensuring safe operation. Pipeline integrity management has been developed to ensure the safe and correct operation of pipelines. Integrity management starts with planning, then leads to inspection, then evaluation, and finally to corrective action, and this loop is repeated regularly. In this loop, the importance of... 

Due to adverse health problems with lumbar spine among professional drivers associated with exposure to whole body vibration (WBV), studying the effect of vibrations and parameters influencing WBV is of great importance. This study aims to simulate whole body vibration for a ground vehicle occupant and calculate loads that lumbar spine tolerate during harmonic sinusoidal vibrations. Moreover, this study determines the effect of lumbar spine angle, seat specifications (angles and materials), and vibration frequency on the results. To this end, a detailed viscoelastic lumbar spine (L1-S1) has been modeled using FE method which has been replaced with the simplified spine model in HYBRID III... 

Use of wireless sensor networks (WSNs) to record environmental data such as temperature, sound level, and light intensity has grown dramatically. The specification of the locations of sensors is important. Using tools such as global positioning system (GPS) to find the location of sensors is not economical. Sensors can record their distances from neighboring sensors. On the other hand, the locations of some sensors are fixed. In wireless sensor network localization (SNL), we want to find the location of sensors using the available information. An approach for solving the SNL problem is to model the problem as an optimization problem and use an interior point method for its solution. Interior... 

We present two projected structured algorithms for solving nonlinearly constrained nonlinear least squares problems. The first algorithm makes use of a line search scheme and the second algorithm utilizes a combined trust region-line search scheme. These approaches are based on an adaptive structured scheme due to Mahdavi-Amiri and Bartels of the exact penalty method of Coleman and Conn for nonlinearly constrained optimization problems. The structured adaptation also makes use of the ideas of Nocedal and Overton for handling quasi-Newton updates of projected structured Hessians and appropriates the structuring scheme of Dennis, Martinez and Tapia. For robustness of the first algorithm, we... 

Self-Compacting Concrete (SCC), a new generation of concrete that are used in different applications. This concrete is compressed without external energy, under its own weight. This study investigating the fracture properties of self-compacting concrete containing steel fibers. For this purpose, steel fibers with different percentages are added to SCC. Also samples with different water to cement ratio and different maximum aggregate size were made and their impact on the fracture parameters of self-compacting concrete containing steel fibers were investigated. In order to achieve the desired objectives in this study, two different methods are used according to RILEM standards which include... 

Support vector regression (SVR) in the field of machine learning attracted much attention because of its attractive features and high efficiency for high-dimensional and nonlinear data. Although support vector regression has shown to be very effective for prediction problems, it is necessary to adjust the parameters contained therein to obtain the desired output with error rates. In the past, this was done manually, by trial and error. Over time and by development of optimization algorithms, one of the newest methods to solve such problems is the meta-heuristic optimization algorithms. Therefore, in this thesis, we use the firefly optimization algorithm, which is a population-based... 

In this research, a traffic signal control strategy is implemented to preserve privacy and reduce network traffic vulnerability against cyber attacks while maintaining the confidentiality of traffic data. Considering a traffic control method based on a macroscopic SAF model, a comprehensive secure computational scheme is designed, involving multiple servers to perform computations needed for obtaining the control signal. A secret sharing method is employed for encrypting traffic data among multiple servers, where servers directly operate on the encrypted data, securely calculate time-space intersection phases, and, thus, curious computational servers or malicious actors, who may have access... 

Line search-based methods are known as a category of the most efficient iterative algo- rithms for solving unconstrained optimization problems. Among them, the conjugate gradient method is of particular importance in solving large-scale contemporary world problems due to its simplicity of structure, low memory requirement and strong convergence characteristics. In spite of the desirable numerical behavior of the conjugate gradient method, this method generally lacks the descent property even for uniformly convex objective functions. To overcome this defect, some effective modifications have been presented in the literature. Amidst, the three-term extension attracted the attention of many...