Sharif Digital Repository

In this study, the analytical treatment of an anchor plate buried in a transversely isotropic half-space and subjected to a normal point load is addressed. In reality, the tension face of the anchor plate is detached from the soil and the edges of the detached zone extend to a region greater than the anchor plate area. To simulate this situation, the anchor plate is modeled as a rigid circular disk located in a penny-shaped crack and it is in smooth contact with only single face of the crack. With the aid of an appropriate displacement potential function and Hankel transform, the governing equations of the problem are written as a set of triple integral equations. Employing some mathematical... 

Recently, the multi-level and multi-facility industrial problem in supply chain management (SCM) has been widely investigated. Supply chain network design (SCND) is one of the most important strategic decisions in supply chain management. The problem is an important management problem in SCM and aggregates the strategic and tactical and operational level of supply chain planning. The supply networks comprise a number of manufacturing sites, a number of warehouses and distribution centers of unknown locations to be selected from a set of potential locations, and finally a number of customer zones at fixed locations. The system is modeled mathematically as a mixed-integer linear programming... 

In this thesis the performance of the all optical AND gates, based the Four Wave Mixing process (FWM), for application in optical communication and computing systems, has been investigated. In the performance analysis of these AND gates, we mainly focus on its application in the receivers of the Optical Code Division Multiple Access (OCDMA) systems. For analyzing the performance of these receivers we utilize the existing mathematical model for FWM [1-5], which leads to the nonlinear Schrodinger (NLS) coupled equations. The attenuation, chromatic dispersion and Raman scattering effects have been taken into account in this model and the scalar approximation, for approximating the relation... 

When increased emissions are combined with a carbon tax or emissions trading system, the result is a supply chain with increased costs attributable to the emission generated on the different parts of supply chain. Most traditional supply chain design models do not take emissions and carbon costs into account. Hence, there is a need to incorporate emission costs into a supply chain optimization model to see how the optimal supply chain configuration may be affected by the additional expenses. This thesis presents a mathematical programming model for the design of green supply chains. The costs of carbon dioxide equivalent emissions were incorporated in the objective function, along with the... 

This study aimed to estimate and simulate the phenomenon of buzz in a supersonic air intake and examine the effects of turbulence models on the accuracy and quality of modeling this phenomenon was divided into two parts. In the first part, turbulence models and characteristics of each of them in modeling supersonic flow was studied as well as available researches were investigated to achieve appropriate numerical method for numerical analysis of intakes using turbulence models. In the second part, one axial symmetry intake of the compound density type was taken which designed for Mach number of 2.0 in order to achieve accurate numerical methods and validate it to model intakes flow. With ... 

In this thesis, while a comprehensive study of different methods for the characterization of the optical fibers is done, a unique and effective method is being introduced for the characterization of the dispersion coefficient of Highly Nonlinear Fibers (HNLFs). The proposed method is based on the Brillouin Optical Time Domain Analysis (BOTDA) of a wave generated by the Four Wave Mixing (FWM) interaction. The current method, which includes an experimental scheme and an algorithm for solving the inverse problem, offers high sensitivity and experimental accuracy at the longitudinal resolution of 1 meter. The noise level has been considerably reduced by understanding different sources of the... 

external radiation therapy is a methods of cancer treatment or improvement of cancer-related complications. various techniques have been developed for external beam radiation therapy. Among which, Intensity Modulated Radiation Therapy (IMRT), due to its ability to adjust the intensity of radiation beams, has a higher capacity to generate appropriate dose distribution based on tumor size and volume. Intensity Modulated Radiation Therapy is one of the most commonly used procedures of delivering radiation to cancerous tissues, with the aim of reaching the prescripted dose in the target volume while minimizing damage to nearby healthy organs. Two decisions are of fundamental importance: to... 

Miniator car is the first Iranian car that its platform is utterly produced in Iran and would be introduced to the market soon. One of the most important matters for this car’s entrance to the market is considering and responding to the customer needs and requirements. In this thesis the customer needs are identified using the conjoint analysis and Kano method. Using the Kano method the installable elements in introduction phase on Miniator car are classified based on the customers’ point of view. Via conjoint analysis the optional elements of type two of Miniator are identified and then the desirability of each type of Miniator is specified. At last appropriate marketing solutions are... 

Facility Layout Problem (FLP) is known as one of the classical problems in industrial engineering which have acquired high attractiveness to researchers. Therefore, in this study, a practical mathematical model is formulated and solved
In order to have a real and practical model, robust optimization is applied to FLP. Therefore, it is supposed to have dynamic values for departments' dimensions. This assumption is very critical to generate an effective and acceptable layout. We consider that each dimension of a department can be changed in a given interval. Due to this assumption, we introduce two new parameters which are called width and length deviation coefficients, respectively.... 

In this study we are looking for an optimum way to select a multi-asset portfolio. Usually portfolios only contain stocks and bonds. Here we examine if adding other sort of assets like gold, currencies, bank deposit and gilt-edged securities are optimum or not. We are doing a comprehensive research of adding other kinds of assets to the portfolio. With modeling and solving the real situation, data and constraints of Iranian financial market we decide to whether add other assets to our portfolio or not. The results show in recent years low risk assets are optimum to add to the portfolio as it is was anticipated to the major economic of Iran  

The co-existance of rarefied and near-continuum flow regimes is widelyencountered in analyzing the multiscale flow problems, e.g., micro-and nanoflows. Previous investigations have revealed that the continuum-based simulation methods would suffer from the lack of accuracy to predict the rarefied flow regimes. On the other hand, the molecular simulation methods are not computationally efficient in simulating the near-continuum flow regimes. Therefore, the use of hybrid simulation methods has been recommended as a serious alternative to simulate the multiscale flow problems. These methods apply the molecular methods in solving the rarefied flow regions and the continuum methods in solving the... 

Composite membranes are one of the promising membranes for overcoming the limitations of conventional membranes in gas separation application by improving the permeability and selectivity. However, it is still very challenging to achieve adhesion interface between the top selective layer and the bottom support layer. The present study demonstrates that this challenge can be overcome appropriately by utilizing a series of adhesive polymer as selective layer to prepare composite membrane. To this end, in the first section a series of acrylate-terminated polyurethanes (APUs) based on poly(ethylene glycol) (PEG) with different molecular weights (Mn) of 600, 1000, 1500, 2000 and 4000 g/mol,... 

High mixing efficiency and high liquid-liquid mass transfer rate are two key features of spinning disk contactors. This work presents the experimental investigation of mixing and liquid-liquid mass transfer characteristics in a new double coaxial spinning disks contactor. The micromixing efficiency was investigated using a standard system of competitive parallel reaction known as iodide/iodate test reaction. The influences of various operating conditions such as the rotational speed of the disks, the direction of rotation, the feed radial location, the feed distribution pattern, the distance between the disks, and the feed flow rate on the mixing quality were examined carefully. The obtained... 

Medical engineering advances in total joint replacements and society’s rising demand for long lasting materials, have proven it essential to manufacture materials that are more similar to the original tissue in the fields of mechanical, tribological and biological properties. Ultra High Molecular Weight Polyethylene(UHMWPE), is a polymer widely used in arthroplasty applications due to its biocompatibility, chemical stability and proper mechanical properties. In this study, UHMWPE-HAp nanocomposites reinforced with Zirconia and Graphene were manufactured aiming to reach a structure that is more compatible with bone tissue and also to improve overall properties. First, using ultrasonication... 

In this research, multi-scale modeling of mixed-mode failure mechanism of quassi-brittle materials is presented. For modeling a realistic crack growth in heterogeneious media, crack initiation criterion, crack growth orientation and the macroscopic cohesive law are derived from a microscopic sample. As a microscopic crack initiation criterion, acoustic tensor is investigated and scaled acoustic tensor has been proposed by comparison its results with maximum principal tensile stress. For crack growth direction based on micro-scale, acoustic tensor and multiscale aggregating discontinuities has been investigated and multiscale aggregating discontinuities by comparison results of these methods... 

In this study, the pervaporation method was used for desulfurization of gasoline. Thiophene was used as a sulfur agent and n-heptane as a representative of hydrocarbon compounds in gasoline. The composite membranes of the active PDMS layer containing the UiO-66 metal-organic framework nanoparticles are based on porous membrane PVDF. The effect of adding PVP polymer on the porosity of the PVDF membrane has been investigated. Scanning electron microscopy (SEM), Fourier transform infrared spectrum (FTIR) and X-ray diffraction (XRD) have been used to characterize nanoparticles and synthesized membranes. The effect of adding nanoparticles on the membrane performance and its sowelling effect in... 

In this thesis, we focus on some internal organization issues of the supply chain; in particular, we analyze some network design problems which are typical of producer companies. The aim is to optimize the flow of goods through the literature distribution network, from the plants where the goods are produced (supply points) to the demand points, which are essentially distributors such as wholesalers or retailers. The system addresses a class of distribution network design problems, which is characterized by multiple product families, a central manufacturing plant site, multiple central warehouses and distribution center, and retail outlets (customer zones) which demand multiple units of... 

In most countries Frequency control services as one of the Ancillary services are presented in market scheme. Frequency control are used in different levels to balance generation and demand. Each reserve levels is implemented with specific characteristics and rules. Clearance of energy and one control reserve has some drawbacks so in this thesis we try to clear energy and different reserve levels simultaneously. Each reserve level is determined with special criteria. This criterion in primary reserve is frequency deviation restriction and unit commitment risk in territory reserve that is determined by system operator. In this thesis these two criteria are formulated in linear form and... 

Increasing demand in power systems necessitates the Generation Expansion Planning (GEP) which is to determine the type, size, and location of new generating units in a planning horizon. The final solution of GEP is based on the minimum cost and/or optimum reliability taking into account various constraints such as capacity of units and lines, operating constraints, and budget restrictions. This paper presents a model based on scenarios for generation expansion planning and units retirement decision. The proposed model could be used by vertically integrated utilities as well as the ISOs in electricity markets to obtain generation expansion schemes. In this approach, uncertainty of units are... 

Low effiencies of equipments and lack of forecasting heat integration in some oil regions are the reasons of primary energy losses in these regions. Also there have been difficulties in providing electric power demands in regions separate from the state electricity network which is a barrier in front of exploiting all the potentials of the region. This research introduces a model that can lead to selection of optimal configuration of equipments and units in order to establish a CCHP system that answers variable electric, heating and cooling demands ensuring a safe margin of power generation. The model simultaneously has the ability to select between existing and new installable equipments....