Sharif Digital Repository

Digital computer simulation and employing the concepts of the experimental design, and other analytical tools for evaluating its output have attracted many of the scientists and researchers interests in the recent decades. The importance of this topic has been increasing and more related analytical tools have been introduced to the scientific literature. One of the powerful tools for simplifying accelerating the optimization process of simulation results, are the use of the metamodels. Use of these powerful tools becomes more eminent when the simulation runs are expensive. By the use of the metamodels the needs of conducting sampling for obtaining some more new points from direct simulating... 

Data Stream is a sequence of continuous data which in recent years, its management and processing is widely introduced in different research areas of computer science such as distributed systems. Although clustering single data stream systems have many usages, the emergence of systems and applications that their main equirement is clustering of multiple data stream that increases rapidly and reveals the need for further research in this area.Sources that are generating data stream have limited memory and processing power.On the other hand, we need information about the entire data stream and require that the information sends to a central site to produce the final result of data mining. As a... 

The AISC Seismic Design Provisions include capacity design requirements for steel plate shear walls since 2005. This system consist of thin web plates that infill frame panels with steel beams as horizontal boundary elements (HBEs), and columns as vertical boundary elements (VBEs). The thin unstiffened web plates are expected to buckle in shear at low load levels and develop tension field action, providing ductility and energy dissipation through tension yielding of the web plate. HBEs are designed for stiffness and strength requirements and are expected to anchor the tension field formation in the web plates. VBEs are designed for yielding of web plates and plastic hinge formation at the... 

Let X = fx1; : : : ; xng be the set of vertices of a hypergraph H and E = fe1; : : : ; emg be the set of its edges. The incidence matrix of hypergraph H is an n m and (0; 1)-matrix, N, such that nij = 1 if xi 2 ej and nij = 0, otherwise. A zero-sum flow for H is a vector with non-zero entries that is in the null space of N. A zero-sum k-flow is a flow with non-zero integer entries that absolue value of each entry is at
most k 1. In this thesis we study the existence of zero-sum flows for designs and hypergraphs. Also we consider zero-sum 3-flows in 2-Steiner designs  

An analytical method is developed for description of the assembly process and dimensional error propagation in planar truss structures using two core concepts of “triangular unit cell” and “redundant member”.In order to clarify backbone of the developed method, its connections with other studies in the fields of tolerance analysis, robust design and structural optimization are discussed.Subsequently, triangular unit cell is defined as the basic element of internally determinate trusses and a suitable formulation is derived for calculating its dimensional error propagations characteristics.It is shown that having such a model for a single unit cell is sufficient for tolerance analysis of the... 

Supply chains are socio-technical engineering systems which now days perform in more uncertain operational environment than before. These systems have been vulnerable because of increasing the number of natural disasters, competitiveness and changing the demand. So these systems in order to be survived in such high uncertain environment need to enhance some capabilities in their structure. In this research by considering an assumed auto supply chain, we try to develop an approach to cover uncertainties in operational environment of this system. At the next step, we use design structure matrix modeling to model the interactions between system elements before and after scenario occurring.... 

Turbojet engine combustors play a key role to convert energy with very high rates. To reach this goal, the combustor must satisfy many conflicting requirements. Complexity of the flow field inside the combustormakes the 2D or 3D analysis very difficult. In this thesis, a quasi one-dimensional software is developed applying empirical and analytical 1D relations. Using data for a mini-turbojet engine, the range of some important design parameters is extracted and then a new combustor is designed using both velocity and pressure loss methods. Different disigns are investigated and are compared by employing an extended version of the simulation software. Due to the unacceptable performance... 

When today’s aircrafts reach the end of their service lifes, fatigue cracks are found to have developed along rivet holes and other highly stressed regions of the aircraft. In order to extend life of these aircrafts, repairs have been made to arrest these cracks. Composite repair patches provide an innovative repair technique, which can enhance the way aircrafts are maintained. In this thesis, composite patch design is presented based on axiomatic design technique. Axiomatic design is investigated design methodology for large or complex system design. Tools to enable successful application of axiomatic design are expressed as axioms and process for axiomatic system design. The patch design... 

One of the fields, in which graph theory and computer science have been appleid,is architectural design. Some of these applications are presented in this thesis. This thesis has two parts, the first part peresents a systematic pathway for design of a floor plan when given the list of cells, the required dimensions of each cell and the matrix of required adjacencies between the cells. (Based on the article by Hashimshony(1988)) The second part is about the application of Evolutionary Algorithm (EA) in ar-chitucture. The architectural layout design problems, which is concerned with the finding of the best adjacencies between functional spaces among many possible ones under given constraints,... 

The brushless DC Limited-Angle Torque Motor (LATM) has been widely used in area of aerospace equipment, robot drives, optical scanning systems and any drive systems that require limited motion, ranging from the simple ON-OFF servo valves to the accurate tracking of a reference signal. This paper presents the optimum design procedures of a brushless direct current limited-angle torque motor. According to a request from industry, a two-pole torque motor with a toroidal armature winding was designed based on analysis of magnetic equivalent circuit of motor structure, and using selected ferromagnetic material and rare-earth permanent magnets (PM). To select the best design solution and optimize... 

The hub networks are applied for commodity flows in the systems, among whose nodes the direct connections are both impossible and expensive. The dependency and interaction of demands are dealt with in this thesis. The dependency of demands are the results of some significant aspects, the most important of which are selecting or not selecting a node as a station, allocating or not allocating a demand to a hub, and associating with a path, to name but a few. Then, the ideas of hub location problem, interaction model, and eventually commodity transportation have been considered together.
In this master thesis, a model having a quadratic and non-linear objective function has been developed.... 

Considering the advantages of optical communications and code division multiple access technique, Optical Code Division Multiple Access Networks (OCDMANs) was introduced. Thence, many researchers have suggested methods for creating Quality of Service (QoS) differentiated classes in OCDMANs. In this thesis, we have comprehensive review on the QoS assignment methods and enhance them by offering new techniques. In physical layer, we concentrate on variable chip rate OCDMANs and in MAC sub-layer, a new algorithm named Adaptive Level Control (ALC) is introduced. Then, we focus on the physical design of OCDMANs. Firstly, we solve the problem of one-class OCDMAN and introduce few simple and... 

In this thesis, in the first part, a promising electrochemical sensor was developed based on a layer by layer process by electropolymerization of pyrrole in the presence of new coccine (NC) as dopant anion on the surface of the CNTs pre-coated glassy carbon electrode (GCE). The modified electrode was used as a new and sensitive electrochemical sensor for voltammetric determination of sumatriptan (SUM). The results showed a remarkable increase in the anodic peak current of SUM in comparison to the bare GCE. In the second part, the electropolymerization of pyrrole was performed in the presence of Nitrazine Yellow (NY) as a dopant anion on the surface of the electrode precoated with CNTs. The... 

In this thesis, the satellite constellation orbit design for regional coverage is investigated. The orbits of satellites in a constellation for Earth observation missions play a crucial role in performance and characteristics of the mission; for example the image resolution, the area of coverage, and the coverage interval. In this thesis the problem is to find the optimal initial orbital elements for meeting the earth observation mission objectives for one or several sites. The cost functions are the total coverage time, the maximum gap time, time average gap, altitude, and number of satellites. The problem is solved in a multi-objective manner for different combination of two of the above... 

The observed response of medium rise buildings during sever earthquakes worldwide has indicated that RC buildings with shear walls behave considerably better than other buildings. The conviction that shear walls are inherently brittle still prevails amongst engineers, and therefore, they usually prefer to choose moment resisting RC frames without shear walls. In this study, a number of RC frames, with and without shear walls are designed in accordance with the seismic codes, and are then subjected to an assemble of severe earthquakes. The results of timehistory nonlinear analyses of these models are then used to investigate the effect of the presence of shear walls within the framework of... 

In this work, magnetite (Fe3O4) nanoparticles with an average siz21.9nm
modified by oleic acid were prepared by the coprecipitation method, which can linked well with organic molecules because of the presence of C-O-C on their surface. Then magnetic poly(lactic acid) (PLA)/ poly(ethylene glycol) (PEG) microspheres were prepared by the single emulsion solvent evaporation technology. The incorporation of magnetit nanoparticles and dox into the PLA matrix was confirmed by FTIR. XRD and VSM confirmed the existence of MNPs in the microspheres which maintained superparamagnetic behavior with a saturation magnetization of 50.69 emu/g.Electron microscopy SEM showed that the magnetic microspheres... 

There are different well-established strategies for making a process plant inherently safer. The benefits of applying these strategies on reducing the overall risk inside a plant are obvious. However, some of these changes are rejected many times because they appear to be too costly. But if the effects of applying inherently safer design strategies are investigated not only on the processing costs of a plant but also on the potential accident costs, the decision would in fact be different. In this paper an optimization procedure is proposed which integrates both processing and accident costs for different design schemes. In this procedure, some of the design variables are chosen with regard... 

In this dissertation, a system consisting of two oscillating and amplifier lasers was designed and constructed. The aim was to use this combination to measure important parameters of CuBr vapor laser. Therefore, two separate Thyratrons switching by a two-pulse control circuit with an arbitrary time delay have been used. Due to the sensitivity of these lasers to tube pressure, two quartz tubes with specific designs was used. This enables us to get a proper vacuum as well as to prevent from impurities in the windows, in a short range of time. In this system, the output light from oscillator is led to the amplifier and after a proper delay time, amplifying was observed.
Based on... 

Uncertainty-based Multidisciplinary Design Optimization (UMDO) is a growing approach in design of complex engineering which has been of great interest to many design bureau and research center especially in field of aerospace. The UMDO goal is to achieve a global optimum design using effective disciplines, interdisciplinary relations and appropriate uncertainty modeling. In this regard, choosing main analysis, design discipline, uncertainty modeling and their content fitness, formulating the problem structure, interaction of disciplines, modeling level of fidelity and the optimization method are the most important challenge of the MDO problem so UMDO is a new trend of MDO, and have been the... 

In this thesis, we determine the optimal capacity of the power plants considering site specifications and Flow Duration Curve and evaluating economic parameters. Finally a design with more sufficient economical and hydrualical performance would be selected. The optimization algorithm used in this thesis is called "Charged System search" that is one of the newest meta-heuristic algorithms. This algorithm is inspired by the coulomb and gauss's laws of electrostatics in physics and utilizes a number of charged particles which influence each other based on their fitness values and their separation distances considering the governing law of coulomb.The proposed method in this thesis can be...