Sharif Digital Repository

In past decades, we have seen the rise of integration density in chips making it possible to design a whole system on a single chip. The previously designed interconnection architectures for multiprocessors systems cannot directly be applied in on-chip systems (especially when the number of processor elements increases) since they require a different type of a cost-performance trade-off. This is why the interconnection networks of systems-on-chip (SoC) are such a problem. Network-on-chip (NoC) was being proposed as a scalable and reusable communication platform for SoCs, which makes use of the network model to develop efficient on-chip communication infrastructures. The NoC has a layered and... 

Institutional investors are among the main players of capital market and stock market. These investor’s activities on the one hand affect directly on indices, and on the other hand on transactions of other players in the stock market. In case the transactions of stockholders are not based on sufficient information and merely based on imitation of other investors, herding behavior would be taken place within them.In this study, using two methods of Lakonishok (1992) & Sias (2004), we consider herding behavior amongst the Institutional investors of Iran stock market.In both methods, weekly and monthly data are used for testing herding behavior in the short-run and quarterly data for the... 

In this work a mathematical model has been developed to predict large deformation of work piece in friction stir welding process. Commercially finite element package; ABAQUS is used to solve the governing equations while an elasto-viscoplastic materials behavior is utilized in the model. The model is capable of considering the effects of process parameters such as welding speed and tool geometry on various aspects of the process including temperature and stress distribution within the work piece as well as tool, and velocity and strain fields with in the work piece. Experimental works have been carried out to assess the accuracy of the model and also to determine the effects of various... 

Impulsive waves generated by landslides and slamming on horizontal cylindrical members of a jacket are examples of phenomena which cause damage on structures and endanger human life. Importance of wave generated by land slide was a motivation for a large number of analytical, experimental and numerical studies. Recently, numerical methods that do not use a grid have been used in order simulation and prediction of damage in these sophisticated hydrodynamic problems. One of these modern methods is Smoothed Particle Hydrodynamics (SPH). A general model based on Smoothed Particle Hydrodynamics, “SPHysics”, was developed jointly by researchers to promote the development and use of SPH within the... 

In this study, an alkaline bath for co-deposition of Fe and Pd was selected. In order to investigate the mechanism of deposition, each of the metals iron and palladium electrodeposited from selected bath separately; and the kinetics of electrodeposition by electrochemical techniques such as linear voltammetry, cyclic voltammetry, chronoamperometry and chronopotentiometry were evaluated. Electrodeposition processes of Fe, Pd and their alloy were irreversible and under diffusion of reducing agents are controlled. Moreover the electroreduction of palladium from utilized bath was performed in two steps. At following, the mechanism of iron– palladium alloy electrocrystallization was discussed and... 

Ray-tracing method is extensively used for wave propagation analysis of indoor and outdoor environment for narrowband systems. The main goal of this research is to extend ray-tracing method for site-specific modeling of wideband electromagnetic propagation. In this thesis, Time-domain reflection and transmission coefficients have been computed for dielectric half-space and dielectric slab with frequency dependent permittivity. First, analytical form of Fresnel reflection coefficient for vertical and parallel polarizations in time-domain have been computed for dispersive half-spaces with lossy, extended Debye, two-pole Debye and multi-pole Debye models. By using these time-domain... 

Metallic multilayer composites provide remarkable mechanical, electrical and magnetic properties. These kinds of composites have been recently processed by severe plastic deformation (SPD) methods. Accumulative roll bonding (ARB) is one of the SPD processes in which accumulation of strain by repeating cycles, leads to the ultra fine grained materials. The goal of this research is manufacturing of Al/Ni composite sheets by ARB process considering the effects of thickness and number of initial sheets on their mechanical properties and microstructures. The initial composites were produced by commercially pure Al and Ni as the matrix and the reinforcement, respectively. Thickness of the Al... 

Gas injection is a well-known enhanced recovery method which can improve recovery using two different displacement processes, miscible and immiscible. Typical non-hydrocarbon gases which have been utilized in these processes are carbon-dioxide and nitrogen. These gases are usually injected separately and have been rarely utilized together as a tertiary recovery process.
In this paper, we have focused on sequential carbon-dioxide and nitrogen gas injection as a novel EOR method. The periodic injections of carbon-dioxide and nitrogen have been repeated for six injection pore volumes. Sensitivity analysis of injection pressure, injection volume and injection rate have been also investigated... 

An α-labeling of a graph is a special case of graceful labeling which was introduced in the late 1960’s. Despite the large number of papers published on this subject in literature, there are few particular techniques to find labeling of graphs. There are still many open problems on this subject, some of which are well-known in Graph Theory. In this thesis, first we present and solve several new mathematical and constraint programming models to find α-labeling of 2-regular graphs. Then, a comparison between their results is discussed. Since, proposed models can only label small size graphs; a tabu search algorithm for labeling the big size 2-regular graphs has been developed. By labeling... 

This thesis represents the obstacle avoidance of a fixed-wing small aircraft using optical flow information of cameras mounted on the aircraft. The thesis consists of two main sections. In section one, the ideal optical flow has been simulated based on the camera model, complete six DOF of flight equations, and the geometry of the environment. An analytical formula has been derived to relate the obstacle detection distance to the maneuverability of the aircraft. Having the obstacle detection distance, the control and navigation algorithms have been developed to achieve a collision-free flight for the aircraft in urban canyons and junctions. The effect of some parameters such as approach... 

Modelling passengers’ itinerary choice behaviour is valuable to understand the increasingly competitive airline market and predicting air travel demand. Research in the choice behaviour of air travellers has evolved to include an analytical focus on variation in the sensitivities of travellers to factors influencing itinerary choice. That is, some choice studies have moved beyond a focus on assumed representative, mean-level sensitivities toward a goal of representing the distribution of preferences across a sample. An important issue that remains is whether the insight gained in previous studies, which focussed on preferences in mature markets with relatively high per-capita rates of air... 

Using materials with better mechanical properties is always advantageous. Many sectors, including automotive and aerospace industries, are always seeking new materials with better mechanical properties and lower weight. A lighter vehicle means lower emission and higher fuel efficiency. Thus, developing new methods to investigate novel materials is very important. One of these novel materials are Metal Matrix NanoComposites (MMNCs). MMNCs are fabricated using nano scale particles embedded in metallic matrix. High strength, stiffness, and hardness are the three most important mechanical properties of MMNCs. Introducing a suitable way of modeling these materials is important since it will... 

Crude oil and petroleum products at the time of extraction, production and transportation cause serious contaminations in soil, water and environment. Biological methods have shown a promising effect for the cleanup of these hydrocarbon pollutants. Bioremediation employs the metabolic activity of microorganisms capable of using oil as their energy and carbon source. Biological methods are also less expensive than other cleanup technologies such as incineration and landfill. Large number of microbial stains have been discovered in nature, capable to degrade oil and petroleum products. Biological cleaning of oil contamination by microorganisms occurs naturally in the environment. It has been... 

Capacitor setting and reconfiguration are of main means of loss reduction and voltage profile improvement in distribution system operation. Cooperation between these two strategies can effectively minimize power losses in distribution system automation. Also, from the medium and long term viewpoint, capacitor placement and reconfiguration can be used for loss reduction and reliability enhancement. In this section, the sum of losses cost, capacitor investment cost and reliability cost should be minimized. Regarding the need to solve two non-linear combinatorial optimization problems simultaneously, metaheuristic algorithms are used in this thesis. Specifically, Elitist Genetic Algorithm,... 

The present study was aimed at developing a model to optimize the sizing of wind turbines according to the region’s wind condition and the capital costs of each part of the turbine. The proposed model, which consists of technical aerodynamic, economic and optimization sub-models, is used to achieve maximum annual energy production by a fixed cost of a single or a number of wind turbines. A cost model has been used to determine the detailed cost of the turbine’s components. The model’s results are presented for two regions in Iran, Khaf and Ahar, and the optimized configurations for a single turbine and a wind farm have been investigated.A case study for the region- Manjil that has some... 

Usually the structures are designed based on the fixed-base assumption; however this assumption is not always correct and the bed flexibility should be considered. This effect which is called soil-structure interaction, change the response of structure on both elastic and inelastic behavior. In the regulations for the design of structures on flexible base, generallysoil-structure system is replaced with an equivalent fixed base structure; in the way that the design force of soil-structure system with reasonable accuracy can be estimated by equivalent fixed-base structure. In some regulations, dynamic characteristics of equivalent structure have been determined on elastic state and the... 

Human tracking is an essential step in many computer vision-based applications. As single view tracking may not be sufficiently robust and accurate, tracking based on multiple cameras has been widely considered in recent years. This thesis presents a distributed human tracking method in a smart camera network and introduces a particle filter design based on Histogram of Oriented Gradients (HOG) and color histogram. The proposed adaptive motion model also estimates the target speed from the history of its latest displacement and improves the robustness of the tracker by decreasing the probability of missing targets. In addition, a distributed data fusion method is proposed which fuses the... 

Cogeneration or combined heat and power (CHP) which simultaneously produces electricity and heat energy from sequential use of single fuel source, has been introduced increasingly for industrial, commercial and residential applications due to its high energy efficiency. While the capital costs of CHP systems are comparatively higher than the conventional systems, their proper selection and optimal sizing and also optimal operation could result in shorter capital recovery period and lower cost of energy supply. Essentially the technical, economic and environmental performances of CHP system are closely dependent on its design and operation strategy. This project presents an optimization... 

Nowadays, one of the most important challenges in the design of digital circuits is their susceptibility to the strike of high energy particles which leads to the Single Event Transient (SET) and Multiple Event Transients (MET). In fact, technology scaling which results in lower supply voltage, higher operating frequency, and lower nodal capacitance, makes today’s digital circuits more susceptible not only to high energy particles but also to low energy particles. Moreover emerging deep sub-micron technologies and the integration of more cells in today’s chips have caused higher probability of MET occurrences. A lot of research has tried to reduce the soft error rate due to high energy... 

The application of internal combustion engine is vast in different context, such as transportation and power generation. Therefore to investigation of these objects and the importance of flame front development, a combustion chamber with constant volume is designed and manufactured. The chamber designing is based on the experimental knowledge and numerical simulation of chamber and glasses. The combustion chamber made of stainless steel and contained transparent quartz glasses in both side of it to provide the ability of using schlieren photography method and investigation of flame. The great advantage of present chamber is the capability of different type of combustion, including fuel and...