Sharif Digital Repository

One of issues of human in this time is questions about epistemology. Human sometimes faced with this qustion that "Is it any knowledge for human being". Sometime he or she answers this question: yes and search for any knowledge around him or her. In the context of philosophy of science these question are very imortant. In philosophy of science one of major question is how many of factors in science is subjective and how many is objective? It is obvious that one of solution to answer this question is investigation of factors that construct the knowledege. Furthermore in this thesis I try to answer that question in context of Hikmat' Motealieh. In this context all of factors that involved in... 

The problem of developing optimal pricing and inventory allocation strategies has been extensively studied over the past two decades. However, most of the literature in this area assumes that customers are myopic price-takers, and do not respond to firm pricing strategically. In this study, we present review on a class of problems that consider a firm selling a finite number of items over a finite time horizon facing stochastic demand and a group of customers who act strategically by timing their purchases. We first review the optimal purchasing policy for the customers, and pricing policy for the firm that is the best response policy to the customer’s strategic behavior. Then we present a... 

The interaction of the vortices and helicopter’s blades is the most significant source of generating the main rotor’s noise, especially in landing and rising. The kind of this noise is broadband and it is produced because of establishing the vortices behind the forward blade, their interaction with backward blade, changing their structures and creating turbulency loading. The known method for modeling of the interaction of the vortices structures and solid surfaces is the simple compounding the rod and airfoil. In this project, by using this method, the noise of the interaction of vortex and blade is modeled in the Reynolds number of 48000 with LES and FW-H Analogy as a hibrid method in... 

Proteins are one of the most important bio-molecules. they play an important role in every aspect of living organisms. The information for synthesizing these important molecules is coded in the DNA of that organism. After the coded data is read and transcribed by some other bio-molecules that are proteins themselves, the protein is made and starts it's biological function in different organs. For this reason, investigating properties of proteins helps us to better understand how life works. Understanding the dynamics of proteins, which are some polymers with special energy landscape properties, has attracted the attention of physicists in the 20th century. Proteins are chains of amino... 

Rapid growth of technology and the increase in availability of fast communication means caused transportation planners to pay attention to solutions of demand management with an aproach to information technology. Replacement of traditional shopping with internet shopping can be seen as a suitable solution to reduce traffic and polution. Purpose of this research is to probe teleshopping choice and the frequency of doing that, simultaneously, using copula model as the most common aproach of joint models in recent years. In this research, the binary logit model is used to build the model for teleshopping choice and the order logit model is used to build the frequency model. The data sample is... 

Pipe freezing has become well established in industry as a method of short-termisolation in order to carry out maintenance or repairs. It is often necessary to repair system components without plant shutdown or drainage of system having many piping structures which may have hazardous or expensive fluid. Therefore, a series of tests has been arranged to investigate the ice plug formation in two standard pipes with different diameter size. The freeze zone on the pipe has been created by means of an aluminum jacket which liquid nitrogen flows in it. In the tests the freezing time, amount of liquid nitrogen usage andthe pressure tolerance of ice plug have been determined. Moreover, the numerical... 

Due to the developments in technology, digital equipments, networks, storage devices, a lot of videos have been produced so far. Due to the dayly high growth rate of videos and their data, organizing and managing of them is difficult for applications such as interactive television, digital libraries, video surveillance, etc.However, for these kinds of usage from videos, at first the video will need to decompose into a hierarchical structure such as shot, scene, subscenes, scene and story unit. In order to achieve these goals, after the determination of shot boundaries and the allocation of key frames for each shot, similarity between each two shots are measured using key frames. According to... 

Despite the many applications of optical devices, compared to other topics, little research has been done in this field in Iran. Therefore, the purpose of this treatise was to make and characterize new optical devices to be a start to the development and increase of knowledge and familiarity with these parts. Due to the existence of sufficient knowledge about the production and use of two-dimensional materials in the country, the development of optical devices based on two-dimensional materials and the construction of light detectors with these materials were considered. Among the two-dimensional materials, tin-based two-dimensional materials such as SnS2 and SnSe2 were chosen due to their... 

In recent years, the area of research on micro flying robots has been developed due to the development in micro manufacturing technologies. Due to extra advantages of these flying robots, they are implemented in military and civilian missions such as identifying, espionage, aerial relays, traffic surveillance, rescue, aid, etc. Ability to fly in specified areas, without human injuries, low manufacturing and energy costs, easy and fast implementation, Easy Maintenance, etc, which are some advantages of these robots. We can control these robots manually by remote controllers (RC) or by Auto guidance systems. On the other hand, these robots are used in research laboratories for testing new... 

Range Profile (RP) is known as one of the most important tools for radar target recognition. The main problem with range profile for radar target recognition is its sensitivity to aspect angle. To overcome this problem, range profiles are assumed to have the same statistical characteristics in small frames of aspect angles or context dependent models such as HMM may be used. All methods presented, seems to have some shortcomings to offer a model based on physical circumstances of target maneuver. For example in such models, consecutive samples of RPs in an aspect frame are assumed to be statistically independent with the same distribution (IID). Here we propose dynamic system (DS) for... 

The present thesis aims at investigating the dynamic interaction of slosh and aeroelasticity in the fuel contained aero vehicles. The main approach in this research is to develop reduced order models for description of the coupled system. In this regard, boundary element method is used to develop slosh dynamic model. Axisymmetric boundary element method with non-symmetric boundary conditions is used to develop slosh dynamic model for axisymmetric containers. Zoning method is used to develop slosh dynamic model for the multi-baffled tanks and based on it, slosh equivalent mechanical model is developed for multi-baffled tanks. Finite element method along with modal technique is used to develop... 

There are numerous ways available to achieve low temperatures that cryocoolers might be among the most important of them. In the meantime, the pulse tube refrigerator has a special place due to its simple geometry and not be using any moving parts. This simple property make the pulse tube refrigerator one of the most popular methods to achieve low temperatures. Nowadays, a pulse tube refrigerator is used for cooling in the range of 4 to 123 Kelvin in two form of one-stage and two-stage and up to an approximate power of 1 KW. Today, due to the temperature and the amount of power required for cooling, as well as the time it takes to reach that temperature, this chiller is used in medical,... 

The preferences of participants can have negative impacts on the efficiency and welfare of peer-to-peer energy communities. If the preferences of participants lead to suboptimal market participation and energy consumption, it can result in price fluctuations, increased costs, and reduced participation in peer-to-peer energy markets, ultimately diminishing community welfare. To demonstrate the effect of participants preferences in the peer-to-peer market, a fully decentralized peer-to-peer energy market for prosumers equipped with photovoltaic production and storage is designed and modeled. In the proposed market, prosumers are divided into buyers and sellers and can trade energy bilaterally.... 

During the last few years, the study of urban environment structures is considered as a research field of interest in remote sensing. In satellite observations of the earth's surface, continuous imaging in terms of time and space has caused the remote sensing technique to be proposed as a useful and efficient tool for the analysis of urban areas. Obtaining quantitative spatial information from the urban environment in fields such as determining the height of buildings plays an essential role in urban planning, monitoring damage to buildings, establishing communication bases and digital cities. During the last two decades, the use of Tomosar approach in order to reconstruct the structures of... 

In this thesis we consider the effect of random locations of users in the capacity analysis of SIR-based power control systems and comparison to the strength-based systems, for the first time. Unlike previous works we do not consider a simple deterministic uniform model for the analysis. We provide simulations and analytical solutions for calculating the interference statistics, based on which, we not only calculate the interference statistics, but also study the effect of locating a user in every location in the network coverage area and its share in the interference. We also calculate each cell’s share in every statistics of the interference. In this thesis, based on the common assumption... 

In synthetic aperture radar (SAR) satellites, the nadir echo is defined as the backscattered signal from the point directly below the satellite on the earth surface. If the timing of the radar is such that the nadir echo arrives at the receiver while the receiver is turned on for receiving the desired signal, it could damage the receiver or disrupt the resulting SAR image, unless it is suppressed enough by proper design of antenna radiation pattern. In current SAR satellites, ”avoiding” this phenomenon is associated with two problems: 1) limiting the swath width, 2) imposing stringent restrictions on the selection of pulse repeatition frequency (PRF). Therefore, ”suppressing” the nadir echo,... 

Localization of radio sources has various applications in civil and military communications. Some of important localization methods consist of Angle of Arrival (AoA) estimation of the illuminated signals from the interested sources. Between various Direction Finding (DF) methods, subspace based methods are of special importance, because of their high resolution and accuracy. And from beginning of invention, because of new challenges, have been focus of numerous researches. In this thesis, first we explain the most important subspace based DF methods called MUSIC and root-MUSIC. Then a novel modification for root-MUSIC is introduced. In our new method the computational complexity of... 

In order to study the interaction of sloshing and structural vibrations of baffled tanks a reduced order model based on modal analysis of structure model and boundary element method for fluids motion is developed. For this purpose the governing equations of elastic structure and incompressible flow used to derive simple models to simulate both fields. Using the modal analysis technique the structural motions are applied to the fluid model and on the other hand by using boundary element method the fluid loads are applied to the structural model. Based on this formulation a code is developed which is applicable to an arbitrary elastic tank with arbitrary arrangement of baffles. Results... 

The aim of this article is ancestral control of a set of 3-wheel robots with non-holonomics dynamics for hunting and covering around moving target. Robots have mass and inertia and the wheels' mass have been considered in the dynamics of robots. The output of controller is wheel's torque and front wheel's steering torque. Moving target dynamics has been considered in a way that it is escaping from invader and the target has holonomics dynamic. To derive the equation of motion, Kane's dynamics procedure has been used. Robots are equipped to sensors for distance assessment, vision angle assessment and also signal receiver antenna. To estimate relative position and variables of other robots'...