Sharif Digital Repository

All studies conducted in this field have been carried out in developed countries, yielding unique and diverse finding. These differences in results stem from the varying transportation approaches of each country, leading to entirely different policy recommendation. Therefore, these research aims to analyze urban transportation energy consumption patterns in Iran, a country with distinctive approaches to energy consumption in transportation and urbanization. This study gathers data from 80 Iranian cities over 10-year period, defining dependent, independent and control variables, and employ multiple regression analysis alongside the optimal model to derive conclusion. The findings indicate... 

The purpose of this thesis is sliding mode control of a roll-pitch seeker by considering the zenith pass problem. This problem takes place when the target appears in front of the seeker’s head. First, the mathematical model of the roll and pitch frames is obtained by the Newton-Euler equations of motion. Then, a MIMO sliding mode controller is designed. The performance of the controller is investigated in the presence of model uncertainties and seeker disturbances. The results indicate that the designed controller is robust enough and provides a suitable performance in the stabilization, tracking and guidance loops.
 

The main objective of all managers of the economic organizations, manufacturing and industrial companies and service providers is to take steps toward improvement and effective use of different resources like workforce, capital, materials, energy and information. To attain the desired productivity, managers have to observe requirements such as establishment of a working organizational structure, effective implementation methods, safe equipment and tools, balanced working atmosphere and qualified human force as the most important factor. Therefore productivity culture should be publicized throughout the organization, and human force should be considered as the main component of this process.... 

Considering the advantages of optical communications and code division multiple access technique, Optical Code Division Multiple Access Networks (OCDMANs) was introduced. Thence, many researchers have suggested methods for creating Quality of Service (QoS) differentiated classes in OCDMANs. In this thesis, we have comprehensive review on the QoS assignment methods and enhance them by offering new techniques. In physical layer, we concentrate on variable chip rate OCDMANs and in MAC sub-layer, a new algorithm named Adaptive Level Control (ALC) is introduced. Then, we focus on the physical design of OCDMANs. Firstly, we solve the problem of one-class OCDMAN and introduce few simple and... 

Nowadays, Gas turbines are developing more than before and one of the most important components of these turbines improving continuously is their combustor. In the recent years strict standards for controlling the amount of pollutants releasing from aero engines have been established and these standards are moving towards limiting these pollutants. Hence one of the most important criteria of combustor design is keeping its emissions at a lowest possible amount. In this study, at first an algorithm for combustor design has been calculated and then by means of this algorithm the combustor of CF6-80E1A4 engine is designed again. The amount of the produced emissions of the designed combustor has... 

Taking into account the impact of advertising on the reference price, we propose an optimal pricing strategy for supply chains in competitive industries subject to reference price effect. Most of researches do not consider the competition among supply chains. An industry with two competing supply chains is considered. Each supply chain includes a manufacturer who sells his/her product via a retailer. There are two types of structures: integrated and decentralized (it is assumed that the relation in a chain is Manufacturer– Stackelberg). Each manufacturer offers wholesale price to his/her retailer anticipating the retailer’s order quantity. In addition, the retailers choose their retail... 

In this study, industrial steel (DIN 17135) underwent a new purification process with the aim of removing non-metallic inclusions and producing clean steel. Samples of steel were levitated in synthetic slag from the CaO-CaF2-Al2O3 system by an electromagnetic field. The effect of time, temperature and slag composition factors on the inclusions content of sample has been investigated. The images of the optical microscope were evaluated according to the ASTM E 45 standard, which according to the extracted results, the removal process was done to the desired extent. On the other hand, as the time and temperature of the process and the weight percentage of CaF2 increase, the number and size of... 

In this study, the cooperative inertial navigation systems are used to prevent the error growth of the inertial navigation system in unmanned aerial vehicles that fly in group. Here, the navigation problem is defined for a group of unmanned vehicles, flying with full six degrees of freedom and the objective is to estimate the navigation information of all cooperators. Due to the nonlinear equations, the decentralized extended Kalman filter is used to estimate the states of the system. This means that there is a Kalman filter in each vehicle. The inputs of this filter are the range and the bearing angles between the vehicle and the cooperators, the estimated position of the cooperators and... 

In this study, integrated navigation systems that utilize velocity-matching algorithm and are used in automatic landing of Unmanned Aerial Vehicles (UAV) are investigated. At first, the accuracy of the navigation system in the landing phase is analyzed and the relationship between the accuracy of inertial sensors, flight parameters and the accuracy of the navigation system is derived analytically. Then, by integrating the dynamic model of the UAV and the inertial measurement unit, a new algorithm for navigation of fixed-wing UAVs is presented. The integration mechanism of the proposed algorithm is tightly coupled; hence, it is capable to eliminate the errors of UAV model and inertial system.... 

Consistent growth in volume and dynamic behavior of traffic mandates new requirements for fast and adaptive resource allocation in modern optical networks.Elastic optical networks have been proposed to provide a competitive and scalable solution by creating tunable high-capacity optical communication networks in which network elements are configured according to the actual need to minimize resource usage for the specified service requirements. Resource allocation with quality of service constraints is one of the most challenging problems in elastic optical networks which is conventionally formulated as a complex mixed-integer nonlinear optimization program.In this research work, we focus on... 

The perpuse of this thesis is to design and fabricate a laboratory one degree of freedom stable platform under turbulences by model-based design method. To do this, different parts of the system were first modeled in the Solidworks software and then fabricated with various tools. With proper assembly of electronic and mechanical components, the original body of the system was created. Then, the controller motor with a stable platform which is attached to it was modeled and simulated in MATLAB software. Then, the parameters of the equations were calculated using standard identification tests and TCACS optimization algorithm. One of the challenges of this thesis is the malfunction of the... 

In this research, a cooperative terminal guidance algorithm has been derived for simultaneous multi-interceptor collision with a target. This algorithm is obtained using the combination of model predictive control method and differential game theory. One of the features of this method is the calculation of the optimal guidance command in the form of an explicit relationship. Another feature of this method is its resistance to disturbances due to the use of differential game theory. The first innovation of this research is the use of this hybrid method to create a guidance algorithm, even in the non-cooperative guidance problem. The next innovation is in creating a cooperative terminal... 

Mobile edge computing (MEC) is a promising technology that aims to resolve cloud computing’s issues by deploying computation resources at the edge of mobile network and in the proximity of users. The advantages of MEC include reduced latency, energy consumption, and load on access and mobile core networks, to name but a few. Despite all the aforementioned advantages, the mobility of mobile network users causes the traditional MEC architecture to suffer from several issues, such as decreased efficiency and frequent service interruption. One of the methods to manage users’ mobility is virtual machine (VM) migration, where the VM containing the user’s task is migrated to somewhere closer to... 

Hybrid engines are one of a variety of chemical propulsion systems that have been given special attention in recent years by various industries such as space and defense. The most important reasons for considering this type of system are its high safety, its affordable price compared with liquid fuel propulsion systems, the possibility of switching on and off and changing thrust. This system has a lot of disadvantages as well. This system cannot meet all the needs of different industries due to the low regression rate and, consequently, the limitation of the operating range, thrusts and special impulse. As a result, increasing the fuel regression rate in these engines can greatly expand... 

Optical impairments, as a challenging obstacle in optical communication systems, have been under deep attention of optical engineers in recent years. These impairments can be divided into two categories of linear and nonlinear impairments. Dispersion is a significant linear impairment leads to broadening of the optical signal and interference between transmitted symbols during detection. Nonlinear impairments such as cross-phase modulation (XPM) and self-phase modulation (SPM) also distort the transmitted signal through the fiber, causing interference at the receiver and degrading the system's performance. An appropriate solution for compensating optical fiber impairments is to utilize... 

In the present study, an adaptive sliding mode control method was employed to control a fish robotic system using the method of hardware in the loop. Following the introduction of the nonlinear model for the robot, elongated body theory, suggested by Lighthill, was used to analyze fish movements. Lighthill’s theory inspired from slender body theory in aerodynamics scope could be viable to exercise upon the carangiform mode of swimming. By simplifying Lighthill’s equations in planar motion of fish robot, the number of degrees of freedom exceeds the number of the control variables. In view of the fact that the presented model is an under-actuated model, there exist some parametric and... 

Sarcheshme Copper refinery is using ion exchange columns to supply deionized water to the refinery. Every day, 240 cubic meters of waste water from ion exchange columns process are released in nature. The main purpose of this research is to use membrane distillation to purify this wastewater, which reduces the fresh water requirement and at the same time prevents environmental pollution. Membrane distillation technology is capable to purify the high salinity wastewater that other conventional membrane technologies are not able to purify. In this study, the PTFE membrane was used due to its high permeability and low surface energy with pore size of 0.22 μm and membrane thickness of 0.2 to... 

The performance evaluation involves a process by which the employees are periodically and officially evaluated. Major reasons of performance evaluation include, among others, identification of efficient employees and granting bonuses to them to create stimuli to improve their and other employees' performances. The main objective of performance evaluation constitutes study of people's performances in the organization in order for directors to take proper and required decisions to enhance both quantities and qualities of the employees' works. The performance evaluation is deemed to be a major critical function of the management of human resources to facilitate organizational effectiveness. In... 

Content-Based Image Retrieval has been an active research area in recent years, due to the vast amount of digital media available via the Internet. In this work we formulate contentbased image retrieval as machine learning problem using the relevance feedback technique and propose a learning algorithm adapted to specific properties of image retrieval. After studying specific properties of image retrieval as a machine learning problem, we propose a Bayesian framework for image retrieval based on one-class learning and test it on different image datasets. The proposed method is a kernel based approach and can also utilize domain knowledge in the form of prior knowledge in constructing a model... 

The most important task of a power system is generating and transmitting electricity for consumers, according to electricity quality standards. One of these quality criteria is preservation of grid frequency close to nominal value with continuity of energy delivery to consumers. Electricity is a specific commodity that its generation and consumption should be equal continually; otherwise the network frequency will change and may become unstable, causing severe damage to the network equipment. There for different control and protective actions are deployed to maintain balance between generation and consumption, and thus to keep grid frequency close to nominal value. Characteristics of...