Sharif Digital Repository

This study consists of two parts: steady state calculations and neutron noise calculations in the frequency domain for two rectangular and hexagonal geometries. In the steady state calculation, the neutron diffusion and its adjoint equations are approximated by two-dimensional coordinates in two-group energy and are solved using the average current nodal expansion method. Then, by considering the node size in the dimensions of a fuel assembly, different orders of flux expansion are investigated. For verification purposes, the calculations have been performed by power iteration method for two test problems of BIBLIS-2D and IAEA-2D. For rectangular geometry with increasing flux expansion order... 

In order to reduce investment and operation costs of the power systems, transmission expansion planning is inevitable. In fact, transmission expansion planning is to determine when, where and how many lines need to be added to power system with a minimum of investment and operating costs. In this thesis, transmission expansion planning has been performed at uncertainty in generation and N-1 criterion condition where uncertainty in generation means uncertainty in the moment of adding power plant to power system. In previous studies, transmission expansion planning was performed with DC-load flow in which, the power loss and voltage profiles were ignored due to the approximation in the... 

In this research, we focused on demonstration of features and advantages of supercritical fluids technology to formation of fine particles (nano and micro scales) from bulk materials (solid) and synthesized metal oxides nanoparticles. Therefore, using two different fluids, carbon dioxide and water, and two completely different methods, the Rapid expansion of supercritical solution and supercritical hydrothermal, were used to produce fine particles of drug (acetaminophen) and nano metal oxide (zirconium dioxide and bismuth ferrite). The summary of this research are as follows:1. The solubility of acetaminophen in SuperCritical-Carbon Dioxide (SC-CO2) with and without menthol as a cosolvent... 

One of the challenges which increasing penetration of renewable energy sources with variable generation brings is the need for more flexibility in the power system. A promising way to overcome the challenge is to have local sources of the flexibility in distribution level. To this end, we present a new model for multi-stage distribution system expansion planning which jointly considers expanding the network assets and increasing the flexibility at local level by installing conventional dispatchable distributed generator units and energy storage systems. Demand response is also considered as another source of the flexibility which can be utilized by the system operator. Since deviating from... 

Expansion planning of distribution network assets is of importance to reliably supply the growing demand. Growing penetration of distributed energy resources (DERs) including renewable based distributed generators (DGs), conventional DGs, energy storage systems, and demand response (DR) resources in the network as well as their operational advantages make it necessary to address the investment planning of these resources in addition to the network assets. In order to effectively utilize the DERs and to solve the challenges arisen by their increasing penetration, active distribution networks (ADNs) are introduced which offer active network management capability. Passing through traditional... 

Climate change has overshadowed various aspects of human life due to rising greenhouse gases such as carbon dioxide. The importance of this issue prompted humans to take steps to reduce carbon dioxide emissions from human activities. Turning to geothermal energy instead of using fossil fuels was one of the strategies chosen for this purpose. Geothermal reservoirs are used to exploit this energy. In geothermal reservoirs, cold water is injected through a fracture network and receives heat from the hot rocks; then, the hot water is pumped out. Due to their high transmissivity compared to the surrounding rock matrix, Fractures are the primary conductors in geothermal reservoirs. Flow-through... 

The increasing variability of renewables and volatile chronological net-load in modern smart grids engenders significant operational risks of an uncertain sufficiency of flexible capacity. Assessing the operational flexibility of the grid with high penetration of renewable resources remains an issue of critical importance. Operational flexibility insufficiency may bring about two major problems: 1) there may exist no feasible solution for operation under uncertain conditions due to insufficient available flexibility capacity;2) even if the solution feasibility criterion is ensured, dispatch limitations of the flexible resources may force the system operating point to deviate from the optimal... 

Tapered-in fluidized beds, have unique dynamic characteristics compared to cylindrical fluidized beds, because of the velocity gradient in the axial direction. Therefore in the recent years, tapered fluidized beds were widely used in various processes such as biochemical reactions, biological, crystallization, gasification, liquefaction, etc. In this study, a two-dimensional gas-solid model using Eulerian-Eulerian approach along with the kinetic theory of granular solid in a tapered-in fluidized bed was applied. Moreover, the tapered-in fluidized beds were compared with the tapered-out fluidized beds and cylindrical fluidized beds in order to investigate the hydrodynamic behavior of the... 

The present M.Sc. thesis consists of two sections including the static calculation and neutron noise calculation in rectangular and hexagonal geometries. The multi-group, two dimensional neutron diffusion equations and corresponding adjoint equations are solved in the static calculation. The spatial discretization of equations is based on Average Current Nodal Expansion Method (ACNEM). Size of nodes is the same size of the fuel assemblies in modeling both of rectangular and hexagonal geometries. The results are benchmarked against the valid results for BIBLIS-2D and IAEA-2D benchmark problems. In the second section, neutron noise calculations are performed for two types of noise sources,... 

The present work has proposed an integrated methodology for combined gas & electricity distribution network expansion planning, which considers network expansion constraints (substation installation, feeder/pipeline installation, etc), load growth, and conversion technologies. The planning aims to determine the optimal reinforcement of existing energy network to meet the load growth in the planning horizon. To take the advantages of new technologies, CHP, fuel cell, & microturbine have been included in the problem.This paper employs gravitational search algorithm (GSA) to solve multi-objective problem, including minimization of cost, voltage drop, & pressure drop. GSA that introduced in... 

Increasing in size and complexity of digital designs has made manufacturing process more complex and enforces more complexity in verification of designs. This makes it essential to address critical verification issues at the early stages of design cycle. Such a complicated designs needs to be tested for fabrication faults as well as functional faults. Several attempts have been made to raise the quality of testing methods with automatic test pattern generation (ATPG) and design for testability (DFT) methods in logic and lower levels. Although these techniques try to increase the testability of a circuit considerably, but there are always some overheads in area, power and performance.... 

Cosmology is a knowledge that deals with the matter of creation of the world, its current structure and its end. This scientific field that was a subject discussed by the scientific, philosophical and religious groups has nowadays taken the attention of many scientists and researchers. The philosophers of science, also, are not exemptions from theses groups and cosmology, as a topic common between philosophy and science, is one of the points that are under discussion in the field of philosophy of science. On the other hand, the religions, also, have noticed this issue. Koran that is the most complete divine book sent from God, has taken account of the creation and the Creator as the axis of... 

Emphasis on the expansion of education in Iran's development strategy and increasing demand for higher education in the 2000s required the country to develop higher educational institutes. Unprecedented growth of these institutes in the second half of 2000s was so vast that in 2008 all the counties in Iran had at least one institute. These institutes were established even in the smallest counties in order to solve the problem of transportation for its settlers, and on the other hand, developing higher education institutes in larger cities resulted in an increase in the acceptance rate of these institutes and their accessibility for the people. Moreover, lower accessibility to higher... 

Increasing the fuel cost and concerns about pollutions have facilitated the use of renewable energies. Wind power as a renewable energy has been considered as a good representative for conventional resources of electrical energy. The biggest obstacles for efficient use of the wind energy are changeability and uncontrollability in wind farm generation and to be far from the demand center. Also, conventional approaches cannot be applied to analyze the effects of this energy on power system. With increment in the penetration of the wind energy in power system, the necessity of considering its effects, especially large scale wind farm, in transmission expansion planning (TEP) studies is... 

This study presents a multi-objective optimization framework for transmission expansion planning in restructured electricity markets under uncertainty considerations. Deregulation of power system has introduced new objectives and requirements for transmission expansion planning problem. Also, the unbundling of electricity industry introduced new uncertainties and escalated the existing ones in network planning. Under these circumstances there is an emerging need for new planning models to cope with restructured electricity industry requirements.The conventional least-cost approaches which represent the transmission expansion planning as a single objective optimization problem could not... 

Transmission expansion planning is an important part of power system planning that it task is to determine the optimal structure of transmission network based on load growth and to consider the future plan of system generation for a specified time period. The development of generation plans based on renewable resources, cost and time-consuming transmission expansion plans have caused that transmission planning to become a fundamental challenge. Therefore, in recent year’s decision makers of power systems are following the alternative ways of transmission expansion planning with lower cost and economic appropriate justification. Using of energy storage systems have cause to a delay on... 

Regarding the issue that significant amount of energy consumption in the world is dedicated to heating and cooling of the buildings, by using traditional methods of heating and cooling, the environment is facing serious problems like green house gases. There were various techniques for decreasing the amount of contaminants stem from this process. Heat-exchanger energy piles are one of the most common methods that will result in economic usage of energy resources. Assessing the long-term behavior of the energy piles requires comprehensive understanding of the complex interaction between soil and pile subjected to mechanical and thermal loadings. Several numerical and analytical methods have... 

Gas transmission networks, as one of the most important energy transport networks, are used to transport gas from production facilities to major gas consumers. These networks possess very complex behavior due to their severely nonlinear equations, their temporal and spatial broadness, the compressibility feature of the fluid that passes through them, and their relationship and interdependency with other energy material generation, transportation, and distribution infrastructures through multi-vector energy systems. Hence, the management and coordination of these networks are challenging. In this regard, the most demanding problem of such networks is their expansion planning due to the... 

This study presents an experimental and numerical investigation on the compressive behavior of a new type of composite column which consists of both solid and hollow concrete-filled UPVC tube with and without GFRP wraps.Composite construction has been often more economical than traditional concrete construction, because this system realizes the most effective use of concrete, and composite members in the structural system.The enormous potential of using plastic tubes in composite systems will be illustrated by this research. It is an economical type of column in construction.This research aims to study the behavior of UPVC-confined columns under axial compression. A sum of 132 specimens are... 

In this research the effect of Si, Cu and Ni alloying elements on the structure and mechanical properties of the A336 alloy is investigated. Expriments were done in two situations, casting and heat treated and the results for all samples with different amount of alloying elements are compared and the effect of heat treating is also investigated. Results show that with increasing the amount of Si and Cu and decreasing the amount of Ni strength and hardness of the cast alloy are 134 MPa and 65 HB and they increase to 187 MPa and 89 HB in heat treated alloy. The elongation and coefficient of linear expansion are decreased from 2.3% and 21.94 μm/m.K to 1.1% and 21.62 μm/m.K. Also the T6 heat...