Sharif Digital Repository

Using single RAID HW-Controller in data storage systems can become a single point-of-failure. Hence, it will affect system availability. As a result, in enterprise-class storage systems, utilizing dual-HW-Controller architecture for managing redundant array of independent disks is prevalent to enhance performance and reliability. Employing such architecture, however, faces major challenges. One of these challenges is the synchronization of dual-HW-based controllers in case RAID arrays revealing erratic behaviours. No thorough study has been done for evaluating dual-controller architecture synchronization mechanisms and its performance. In this thesis, different configurations of enterprise... 

Study of the structural flexibility of large-scale wind turbine components on aeroelastic performance is important under the existence of critical atmospheric conditions. Prediction and control the critical deformations, identifying maximum local deformation and modeling the forces involved, are required. Aeroelasticity analysis is a suitable method for studying the coupling effects of wind turbine aerodynamics, dynamics and structures. This research has been done by modeling wind turbine components including blades, hub, nacelle and tower, taking into account aerodynamic couplings, dynamics and structures. Considering the large scale of reference wind turbine, nonlinear equations have added... 

Uranium recovery from wastes produced in every stage of nuclear fuel cycle is very important from both the economic and environmental points of view. Zircon, zirconium-containing ore that is the input feed to Zirconium sponge production factories, contains considerable amounts of uranium compounds. The majority of this uranium will enter to the different waste streams of the plant. In this study, by analyzing the waste streams of the Zirconium Production Plant (ZPP) located at Isfahan, Iran, total mass balance of uranium in waste streams was identified. It was concluded that bottom residuals at furnaces of the chlorination unit is the primary uranium-containing waste stream. The preliminary... 

The vulnerability of women in the labor market is a well-established fact, but it can be long-lasting when a shock hits them. We examine women’s labor market conditions in a developing country with a substantial set of cultural norms and provide evidence that a job destructive shock persists longer among women. Specifically, probability of remaining unemployed after 20 months is about 50% for women while it is 10% for men. These findings are exacerbated for women who have not worked for more than 5 years and probably have lost their network or are new entrants in the job market. Moreover, women in the private sector, which is a more competitive market in Iran with respect to public jobs, are... 

Environmental problems have been one of the considerable issues since the irreversible characteristics of nature and its effect on human life were recognized. Scientists have proposed a variety of solutions in order to overcome such problems. Green marketing can be regarded as one of the solutions in this area. Similar to most other issues, this concept has been noticed less in developing countries compared to developed countries. Therefore, researchers in this study conducted a comprehensive research on the concept of green marketing in Iran focusing on consumers’ behavior.
To achieve relevant results, two types of research were conducted: qualitative and quantitative. The results of... 

Fog computing environment consists of several devices which distribute across an arbitrary topology. Each of these devices is capable of carrying out a designated computation simultaneously with other devices. One of the common ways of describing a computation is through the usage of workflows. Workflow is a flexible and formal way of modeling tasks and their requirements for execution. A workflow is essentially a DAG. Therefore, it can model the data dependency between tasks quite accurately. The complex structure of a workflow in conjunction with the homogenous nature of devices in a fog environment makes it difficult to find a resource management algorithm to minimize execution time, used... 

Aspect-Oriented Software Development (AOSD) concentrates on separation of global cross-cutting concerns, or aspects. The weaknesses of Object-Oriented Software Development (OOSD) in localizing orthogonal concerns simultaneously leads to distributing them across several modules, and thereby creating modules that have to deal with various concerns. This usually results in poor modularization and difficulties in tracing certain requirements (especially nonfunctional requirements) to their implementations. The AOSD approach determines the common aspects that exist across modules created through OOSD, and modularizes them. Thus, AOSD takes the next step in creating modular software. Applying this... 

In this thesis, a power switch with a smart driver is designed. 4-ampere current can pass through the switch, and the driver is capable of switching the load with 50 kHz frequency. The smart driver consists of an internal oscillator, internal regulator, charge pump, current limit, a level shifter, overtemperature and over/under voltage circuit. All these circuits are designed and developed in high voltage BCD 0.18 um process and well discussed in the thesis. All four kinds of protections are designed and implemented; open load detection, short circuit detection, over temperature shut down, UV and OV detection. Charge pump idea is used instead of the bootstrap method, which makes it possible... 

This thesis proposes a probabilistic framework for evaluating and enhancing the community recovery process following an earthquake occurrence. This framework serves as a recovery decision support tool, aiming to enhance community resilience through the optimal allocation of limited available resources following a disaster occurrence. To this end, Bayesian network and agent-based simulation are integrated, each of which forming one of the modules of the proposed framework. The first module, namely, the Bayesian network, leads to situational awareness of the status of the community after the earthquake by fusing data from various sources. The data, such as the earthquake event characteristics... 

This project focuses on the design of fuel drop tanks for airplanes that add minimal drag and positive lift to the flying object. This will obviously effect the stability and dynamic performance of the airplane. To reduce adverse dynamic effects the tank was divided to several segment with a special emptying sequence. The add-on tank has to have no interference with the object existing systems and require minimum structural changes in the object. Several designs were proposed and the one gaining highest marks was selected. The flow field and the dynamic behavior of combined vehicle and drop tanks were studied using FE simulations. The result shows that adding a drop tank with optimized... 

The purpose of this study is to investigate the distribution of air flow and temperature in electric machines. The fluid flow equations are solved by using the characteristic Galerkin. The unsteady equations of the air flow and heat transfer between the rotor, stator and radial cooling channels of the generator are solved by finite element method. Tetrahedral elements are used, but hexahedral elements can also be used. The upwind method is used to discretize the convection terms, but the central difference for the diffusion parts, that is equal to Petrov-Galerkin method in steady state situation. Due to the large number of channels and specific geometry, to reduce the computation costs, the... 

Economical strategy of developed countries imposes to improve energy efficiency and a rational renewable energies usage in the buildings. Ground source heat pumps are one of the most important tools in the way moving toward this goal. This study focuses on studying the effect of applying different refrigerants in the direct expansion ground source heat exchangers. In order to compare the performance of the ground source heat pumps using different refrigerants, a specific methodology is presented and implemented. First on this study, the thermal performance of a geothermal borehole filled with both CO2 and a zeotropic mixture of CO2 and R32 (20/80) is studied and the quality, temperature, and... 

Cancer can be defined as a stochastic phenomenon. Thus, the tumor growth can be defined as a stochastic process. A Cancer tumor can be analyzed by its geometric shape. Furthermore, computing fractal dimension of shapes is a useful technique to analyze chaosity and complexity of shapes. This approach can be used to compare results from laboratory with simulated results of a mathematical model. A stochastic model of tumor growth will be presented. And some geometrical properties will be analyzed through computer simulation of the model