Sharif Digital Repository

The study of flood control operation in large scale multipurpose reservoir systems is deals with various objectives, such as flood damage reduction, hydropower generation and reliability of the system for supplying demands after flood seasons. The introduction of these objectives, introduces a conflict in objective function where tradeoff must be made. The purpose of this study is helping to decision making process in evaluation, planning and operation phases through preparing the Pareto curves that include various optimum alternatives for operation. For this purpose, we develop a multiobjective optimization model, based on use the mixed-integer linear programming. This model considers two... 

Introduction: Today, backward and forward scattering tomography of dispersive medium is of great interest because of its broad applications, especially in medical imaging, of breast cancer, Distinguishing different tissues of the body from each other is one of the necessities. Increasing the quality of the image by just a few percents has great improvement on the tomography resolution.
Materials and Methods: In this project we made phantom of the tissue and tumor from Intralipid 10% plus Agarose and Indian ink for soft tissue and plastic fibers as tumor having birefringence factor of 0.001.After putting the plastic tumor in soft tissue phantom, the polarized white light and a digital... 

Hydrophilic polymers are widely used in enhanced oil recovery (EOR) processes to increase water viscosity during polymer flooding. However, these polymers increase the viscosity of injected water in undesirable strands, before reaching considerable positions that make some problems in polymer flooding process such as thermal, mechanical, bacterial degradation, surface absorption and undesirable plugging. In this study, a novel core-shell structure of polyacrylamide as an active polymer and nanoscale coating polystyrene as a shell polymer was designed and prepared to intelligently control mobility ratio in oil reservoirs and overcome weakness and limitations of classical polymer flooding.... 

Regardless of the traffic model and its application, an essential input of transportation models is the amount of demand which is usually described using Origin-Destination (OD) matrices. Due to high costs and time of direct development of such matrices, they are estimated indirectly from traffic measurements recorded from the network. Dynamic Origin-Destination demand provides valuable information on within-day fluctuation of traffic demand which could be used in analyzing congestion dissipation. In addition, they are essential inputs of dynamic traffic assignment (DTA) models. The current study presents a fuzzy approach to dynamic OD estimation problem. The problem is designed as a two... 

Nucleosynthesis and CMB data clearly indicate that most of the matter in the universe is dark and of course, nonbaryonic. In the particle physics, many particles have been proposed to explain relic density of Dark Matter. These candidates can be classified according to whether they have decoupled from the thermal bath or were created in a nonthermal process. In the first class, thermal relics can be categorized into relativistic and nonrelativistic particles, at the moment of decoupling. The relics which were relativistic are called Hot Dark Matter, while those relics which were none relativistic constitute Cold Dark Matter. The goal of this thesis is investigation of cold dark matter... 

Due to restrictions on connecting beams to columns in steel structures when moment-resisting connections in two perpendicular directions are employed, the use of ordinary wide-flange sections or fabricated boxes becomes impractical. Application of Cruciform sections, especially when fabricated from two split-I sections (IPE sections) seems to be a reasonable solution to this problem. In this study, using Finite Elements Method and a commercial FEM software, the nonlinear behaviour of a number of cruciform columns, already tested by others, were modeled numerically. After reaching results in acceptable agreement with those of the tests, potentially suitable sections for fabrication of... 

Propylene Copolymers and terpolymers with small amount of 1-butene& ethylene can greatly improve the properties of polypropylene material such as low temperature toughness, printing performance, transparency, process ability and so on, leading to expanding of its application. Poly(propylene-co-1-butene) performance intensely relies on its composition and chain structure. The copolymerization catalyzed by Ziegler-Natta catalyst, which is a multy-active central system. The Ziegler-Natta catalyst TiCl4/ Mg(OEt)2/ DIBP was used for copolymerization. The microstructure of copolymers were characterized by FTIR. The influence of different comonomer ratios on the copolymerization has been... 

The extended drought in the Orumieh River Basin has caused severe problems for Orumieh Lake. Due to the fact that agriculture is the biggest user of water resources in this region, effective management of groundwater and surface water resources plays an important role in management of Orumieh lake`s condition. In this situation, “water trading” by designing an efficient “smart market” seems to be a viable option; A market with lower transaction costs which can be adaptable to changing demands and being able to optimize economic benefit within the environmental constraints. This market works by reallocating water among users who intend to sell their excess water and those who prefer to buy... 

Nowadays, one of the most challenging issues concerning the manufacturing industries is the shortage of available resources and their increased costs. As a matter of the fact, for these industries, optimizing the processes is not something to be ignored and one of the most important goals is reducing the costs of manufacturing and increasing the profits of sales. On the other hand, in actual situations, due to the complexities of optimization problem and numerous calculations, the classical methods would be limited to very simplistic cases in which most of the practical changes are ignored. In such problems, the need to use strong optimization techniques like the genetic algorithm is evident... 

Knowing the magnitude of the maximum strain before necking is of utmost importance in the processes of designing sheet metals. Thus, numerous experimental and theoretical efforts have been done to answer these questions. In order to predict allowed strains in biaxial stretching, an experimental diagram was introduced called “Forming Limit Diagram” in which major strain is plotted versus minor strain and if the corresponding point to the strain on the sheet is higher than this diagram, necking will occur. One of the most popular methods of obtaining forming limit diagrams is using a hemispherical rod for shaping sheet, which is named as “Nakazima Test” and then the critical strains are... 

Cluster analysis is one of the basic tools for exploring the underlying structure of a given data set. It is being used in a wide variety of engineering and scientific disciplines. It can be broadly defined as the process of dividing a set of objects into clusters, each representing
a meaningful sub-group of data. Clustering techniques require the definition of a similarity measure between patterns. This similarity measure is not easy to specify in the absence of any prior knowledge about cluster shapes. Recently, constrained clustering has been emerged as an efficient approach for data clustering and learning the similarity measure between patterns. It has become popular because it can... 

The phenomenon of drought causes many damages which is not limited to arid and semi-arid areas and may have destroying effects on groundwater resources of any region. To investigate the drought effects on one of the Lake Urmia’s sub-basin, the precipitation data in 25 rain stations in period of 45 years (2011-1976) was used. After completing and restoring data, and checking the randomness and homogeneity of them, standardized precipitation index (SPI) with different time scales has been calculated. According to that, the monitoring maps of drought using ArcGIS tool with regard to best interpolation method was created in order to identify the sensitive areas in dry years.
Moreover,... 

Investigation of electrohydrodynamic behavior of fluids under electric fields is a challenging and impressive matter in condensed matter physics. In this thesis, inspired from previous works on liquid film motor, a new phenomenon has been observed and its properties has been investigated.Here by making a new device named “Liquid Film Electric Generator” we produced potential difference on the rotating suspended liquid film under electric field. The power conducted by electrodes has been generated on the surfaces of the film. By this method, under electric field of 1000 V/cm, micro-watt electric power can be achieved on a liquid film of diameter of about 1 cm.We explained this phenomenon on... 

In this project, by using the image processing method, the strain rate in the deformed sheets is measured, and then compared with experimental results. Scratches are first drawn on the surface of the sheet. After the deformation, photographs of the surface are taken, by using image processing method as well as the use of special techniques, the strain is obtained fast with accurately. By determining the strain, tension will also be achieved through Levy Mises relations. In this project, by using this method, the strain is calculated on surfaces with simple geometry, such as sphere (spherical surface of the sheet in the FLD test), as well as surfaces whose surface geometry is unknown and... 

In Fourier domain optical coherence tomography, we can measure the optical thickness (refractive index n times thickness d), of sample’s layers. In this work, we introduce a new method for measurement of refractive index and physical thickness of multiple layers simultaneously by Fourier domain optical coherence tomography, without additional information about the structure of the sample under investigation. The input data to the formulation are the optical path lengths (OPLs) and suitable set of wavenumber of the FD-OCT interference spectrum. The output of simulation suggest that, the accuracy of the extracted parameters depend on the difference in the refractive index gradient of sample... 

Sheet metal forming is widely being used in the production fields. Improve of quality, production rate and efficiency of this process are important. Temperature and strain rate are the most effective parameters on the formability of sheet metals. Utilizing forming limit diagram is the most common method of determining the formability. In this study, forming limit diagram of AA3003 aluminum alloy is extracted in different temperatures and velocities using simulation of Nakazima test with Abaqus finite element software. The simulation results, indicate that at 250°C formability is about 3 times more than that at room temperature. increasing the velocity of the punch in low strain rates causes... 

Nowadays climate change is a crucial environmental challenge in the world. In addition, population growth, growing demand for water and subsequently increase in water resources development plans have challenged basin management. So that the water resources systems are not responsive to the needs and the demand for water has outpaced the available water resources. Dams and reservoirs are the most effective water supply systems that alter the unequal temporal and spatial distribution of water. In addition to supply of drinking water, ecological requirements, hydroelectric power generation and downstream irrigation, they have an important role in minimizing the damages caused by flood and... 

For the preliminary design of isolated structures, it is necessary to select the appropriate damping ratios in each mode. The inherent modal damping in this type of structures is small. On the contrary, a significant value of damping is induced by dampers in isolator system into structural modes. The purpose of this study is to determine the Modal damping ratios in isolated structures. In this regard, shear structures of 2 to 10 floors with linear behavior in both superstructure and isolation level have been analyzed. The Structures have been modeled taking advantage of OpenSees. Samples are analyzed under sinusoidal loading applied to each floor. In order to achieve modal damping, an...