Sharif Digital Repository

In this research the appilication of a new method named Endurance Time (ET) analysis in seismic analysis of multi span bridges in linear and nonlinear ranges is investigated. Endurance Time is a time history based method of seismic analysis. In this method structure is subjected to an intensifying predefined acceleration function and different damage indices of the structure are evaluated through analysis time. The Endurance Time criterion and the Endurance Time acceleration functions have been generated in previous researchs of ET group. Using 7 earthquake records which are selected from hundred ones of PEER database based on FEMA p695 recommendations, several scaling methods are used to... 

In recent years, due to the economical concerns in the structural design, many researches are devoted to introduce new frameworks for optimization of the construction cost as well as maintenance and rehabilitation costs in the life time. The bridges are the most crucial components of the transportation networks and their appropriate performances assures the flow in the transportation network. Hence, the reliability and response of such infrastructures especially in the emergency conditions and the state of servicibality after the hazards like earthquake play a key role in the social life. So far the design procedure of such infrastructures are only limited to the serviceability conditions as... 

One of the main challenges in the design of wireless sensor networks (WSNs) is minimizing the energy consumption while simultaneously maximizing the performance of sensors. In this thesis, we have considered WSNs based on beacon enabled IEEE 802.15.4/Zigbee Standards with low rate applications like temperature, humidity and light sensing, which mainly have been used in a smart home environment, and proposed a cross-layer design to overcome this challenge. The design involves an optimizer module that captures the application layer and MAC sub layer behaviors. Based on these behaviors, the optimizer dynamically changes the rate of node’s traffic at the application layer and the priority of... 

We present a home energy management system that is able to manage home energy demand and resources to achieve minimum household payment in electricity dynamic pricing.Communication is used to collect needed data from the home energy system members and users in order toimprove demand and resources management. Some of the needed data comes from appliances and solar panels by wireless sensor network and some other is received from home users by a user interface.
Two algorithms are proposed that the first algorithm goal is to minimizing household payment and the second algorithm goals are flexible implementiation and decreasing household payment. To decrease household payment, these... 

Data mining (DM) is one of the newest techniques which is used in decision making. DM helps the specialist to find the valuable knowledge which is hidden in data, with different techniques. DM has many research areas such as scientific research, medical fields, health care, fraud detection, marketing and customer relationship, sport, and games, and where ever there is data. Unfortunately, in our country, DM is not engaged seriously and there are fallacies of DM that weaken its efficiency. In this thesis, which is prepared in two sections, at the first section different techniques of DM are described and in the second section DM process is performed for a real world problem. For this purpose,... 

A major breakthorugh in all-optical wireless and wired communication networks is taking place in the last mile such as access networks. In this case، study-ing various multiple-access techniques in all-optical domain، especially optical code-division multiple-access (OCDMA) technique is of utmost importance. In this thesis we study several key signalings and modulation techniques in the con-text of their performance، energy and throughput efficiency for OCDMA systems. In particular we introduce novel multilevel signaling techniques for OOC-based fiber-optic CDMA systems and present their corresponding all-optical receiver structures using advanced optical devices such as optical-logic-gate... 

In this thesis a mutliScale model based on the Cauchy-Born hypothesis and via usage of XFEM is proposed for crack modeling. By solving an example, the important of surface effects in the surface stresses region is shown. Considering not being able to model the surface effects with the Cauchy-Born method, the boundary Cauchy-Born method for modeling crack effects is used. Moreover, three Molecular Dynamics method for modeling crack will be proposed. According to the obtained results from these methods, it was deduced that for calculating the correct surface stresses in Molecular Dynamics the mutual interaction of upper and lower atoms of crack should be omitted. Finally, the validation of... 

Modeling and Control of Ethylene Oxide Reactor In this thesis, steady and dynamic modeling of an ethylene oxide fixed bed reactor has been studied and one dimensional pseudo homogeneous model was used for simulating the reactor. Kinetic parameters were obtained by minimizing an object function and using the genetic algorithm. A good agreement is observed between simulation and experimental results. In steady state condition, the influence of some parameters such as shell temperature, feed rate were investigated on the performance of the reactor. The heat of reaction is used to produce steam. A dynamic model for steam drum was also considered and used for control purpose. A PI controller was... 

This thesis presents the development of a Finite Element Model (FEM) for a new type of Beam-Column Semi-Rigid steel connection. This connection consists of a steel semi cylinder connected to a plate and inserted on the top and bottom of the beam connecting it to the column by welding. It seems that changing the geometry of the semi cylinders and their weld lengths can have a great influence on the rigidity or flexibility of the connection. Therefore, meaningful categories of the connection with different semi cylinder geometries and weld lengths have been modeled and investigated by means of a Finite Element Modeling software ABAQUS, and their moment-rotation curves were driven. Also the... 

The conventional cameras and displays do not have the ability to record and display the full brightness of the world around us. These deficiencies have led to the development of methods known as High Dynamic Range Imaging. Most of the work done in this field falls into two groups: compression of the light range and its expansion. In compression, the brightness range is intended to display content with a high dynamic range in simple displays. But the goal of expanding the brightness range is to reconstruct HDR content from a low dynamic range one. In addition to the above classification, this field is also categorized based on the type of content (image or video). In this study, the...