Sharif Digital Repository

Renewable energies and their various types have been recognized as sustainable solutions to address the challenges arising from increasing energy consumption and environmental issues. The use of wind energy as one of the renewable energy sources has particular advantages, considering it as one of the most sustainable energy sources. One of the key factors in wind turbine development is the diversity and multiplicity in their structural designs. Therefore, the design of wind turbine structures with characteristics such as suitable strength, high energy efficiency, optimal cost, and high reliability is of great importance. By employing various sciences such as vibrations and optimization in... 

Nowadays, horizontal drill string is a powerful tool for drilling in the oil and gas industry and an efficient method for constructing underground tunnels in cities. Despite its many uses, this method is exclusive to limited countries and is considered among the most advanced methods for drilling. One of the most important problems in the field of horizontal drilling is the existence of destructive axial, torsional and lateral vibrations. If these vibrations are not controlled, they can cause irreparable damage to the plant and drilling well. Among the introduced vibrations, axial and torsional vibrations have a very dominant effect on the drilling process, so the purpose of this research is... 

Artificial intelligence (AI) has become an instrumental force in reshaping various sectors, especially in mobile networks. To realize AI as a service (AIaaS) and enable prompt decision-making, edge computing has risen as an innovative response, pushing computation closer to data sources. Although this is promising to reduce the dependency on remote cloud infrastructures and save the mobile devices’ energy, current methodologies display constraints in effectively distributing deep neural network (DNN) inference tasks, leading to possible resource underutilization and performance compromises. To tackle these issues, in this thesis, we study AIaaS at the edge and focus on renowned DNN... 

This study develops a new framework for the assessment of land subsidence occurrence rate. The proposed framework considers the combined effects of saturated and unsaturated soil behavior. Accordingly, the biot consolidation theory was used for investigating subsidence in the saturated zone while the soil shrinkage curve, i.e., the void ratio-suction curve, was used in the determination of unsaturated zone subsidence. Specifically, groundwater decline and land climate change were used as the main contributing factor in investigating the land subsidence in the saturated and unsaturated zone, respectively. The approach presented in this study is based on using numerical modeling in PLAXIS 2D... 

With the advent of new technologies in everyday human life, issues related to the use of vehicles have become crucial subjects of investigation. In this context, vibrations transmitted from the vehicle to the human body, especially in terms of long-term health effects, have garnered special attention and significance. The main objective of this research is to develop a control system for the active control of vibrations transmitted to the human body. To achieve this goal, a 5-DOF model of the human body has been employed as the study system. Considering the uncertainties in the parameters and dynamics of this model, H∞ and µ-synthesis methods have been utilized for robust control design. The... 

The objective of this study is development of a probabilistic framework that facilitates the investigation of the post-earthquake performance of a network of hospitals using the Hospital Network Resilience index which quantifies the ability of the hospitals to provide treatment to earthquake victims. Disasters such as earthquakes can damage the infrastructure systems of a community, disrupt the functionality, and lead to various direct and indirect economic, social and socioeconomic consequences. Over a decade, natural disasters such as earthquakes are estimated to have caused $1.3 trillion economic losses. The social and socioeconomic losses of natural disasters are equally significant as... 

The goal of this study is to investigate the effect of events such as earthquakes on businesses. Earthquakes can have a significant impact on the performance and profitability of businesses. Earthquakes can negatively affect the functionality of community infrastructure systems by damaging their components and this disruption in the functionality of the lifelines of the community can negatively affect the businesses that are dependent on their functionality. In addition, earthquakes will cause casualties and injuries, leading to a decrease in the workforce and the customers’ population. In such a situation, the activity of many businesses is disrupted and even stopped, which in turn has many... 

The soil-water retention curves (SWRC) is an unsaturated soil mechanics hydro chemical state surface, which expresses the relationship between the soil suction and water content. The soil-water retention curve could describe the water adsorption and desorption process that happened in soils. The difference between the desorption or drying retention curve and the adsorption or wetting retention curves in a specific soil specimen indicates the hydraulic hysteresis phenomenon. Generally, the amount of water remaining in the drying process is greater than the amount of water adsorbed in the wetting process at a certain amount of suction. Suction due to the combined effects of capillary and... 

In this thesis a method based on opinion formation in complex networks aiming to solve unconstrained optimization problem has been studied. Unconstrained optimization problem is the problem of searching for the best solution in the solution space. Optimization problems have many applications in various fields that due to advances in data storage and also appearance of new big data applications solving these problems in large scales gained much importance. Different methods have been proposed in order to solve such problems but because of high computational complexity, many of them do not show good performance. A category of methods called stochastic search methods are used to overcome the... 

Project cost overrun is one of the most frequently occurring issues in the construction industry. Past research studies have investigated the project cost overrun problem from various perspectives. However, to date, only a few studies have focused on the identification of the root causes of projects cost overruns. A close review of these studies reveals that the studies often provide limited insight into the root causes of project cost overrun. These studies fail to consider the impact of project delivery system as a defining project characteristic that may influence construction cost overruns. In addition, past studies have relied on surveys that are not necessarily precise and highly... 

There is many sources of uncertainty in the power plants such as continuous changes of the ambient temperature and the climate condition. The controller of the boiler-turbine unite should be robust against uncertainties and overcome the changes in the operating condition. In this regard, a robust adaptive variable structure control scheme (RAVCS) is proposed to control a nonlinear multi-input multi-output (MIMO) model of industrial boiler-turbine unite, in the presence of unknown parameters and bounded uncertainties as well as external disturbances. Moreover, a robust controller based on and in the presence of rational deviation in parameters, is designed. To investigate the zero... 

Air-handling unit (AHU) is one of the installations that is responsible to control the temperature and humidity inside a space using the heating, cooling, humidifier and drying air. At present, energy efficiency in building is an important issue to maintain the comfort conditions. One of the most common ways to optimize the performance of industrial installations is the use of control systems, which leads to the reduction in both of the costs and energy consumption. In this research, a multivariable nonlinear dynamic model of the AHU with one zone in the VAV (variable air volume) system for working in summer is considered. At first, introduction, limitations and driving the equations for the... 

Nowadays, oil has an important role in our life and most of its role can be seen on the transportation. Discovering and extraction of oil are very important to produce oil and receive it to costumer. When oil is discovered, the oil companies used to drill the ground to extract the oil but they can’t extract all of oil from its reservoir. So, researchers proposed to inject another fluid like water to the oil reservoir to extract oil. Oil is trapped in the porous media which has a lot of pores and some of them have a micro scale size and they contain oil. When water is injected to the reservoir it flows in this pore and interfaces with oil and they create a multiphase flow. The governing... 

One of the passive control systems that are used widely in today’s buildings are metallic yielding dampers. Metallic yielding dampers by absorbing earthquake input energy, prevent inelastic defromations form in beams and columns. In this research, the behavior of an innovated metallic yielding damper, named pistonic damper is investigated. This damper consists of a number of circular parallel plates with constant or variable thickness that dissipate seismic input energy by flexure yielding in small displacements. at large displacements stress field in plates is changed and this caused the stiffness and strength of damper are increased and show shell behavior. this kind of behavior... 

The main goal of this project is to design and implement an Endoscopic Sinus Surgery Simulator using a nonlinear model relating the force and displacement of the surgery tool interacting with the virtual sinus tissue. This model approximately matches the force-displacement data attained from the experiments conducted on the real sinus tissues. To simulate the behavior of the sinus tissue in a virtual environment, a haptic device is utilized which imitates the behavior of the surgery tool interacting with the tissue model. The haptic device in this project is a Falcon Robot. Because of the uncertainties in the parameters of the robot and the operator’s hand model (which is considered in the... 

No one bears thinking about undergoing a surgery by an unexpirienced surgeon, the consideration of which implies the prominence of effective surgical trainings. The advent of utilizing haptic interfaces as a novelty in this field has led to a more promising surgery education. These haptic interfaces consist of three communicating parts namely: operator’s hand, haptic robot, and tissue virtual environment. Design and implementation of a proper controller in order to stabilize the haptic interface during surgery simulation, with acceptable transparency, is still novel an otherwise challenging research field. In this thesis we consider an appropriate nonlinear model for both virtual tissue as... 

In this study, reform strategies to enhance private sector participation in infrastructure projects is provided. The study is presented in the form of words that government institutions could use in the highest level. the pattern used for this study is based on system thinking in which all components are in causal relationship with each other. It was made effort to policies and upstream objectives of the country be respected. To provide research content, content analysis of successful experiences in the world was done. Finally, obtained strategies was presented to the experts, reformed and important cases was investigated. Lack of information and difficult access to country's infrastructure...