Sharif Digital Repository

The present paper discusses the possibility of adding recycled polymer fibres to high performance concrete (HPC). Fibres used in this study were recovered from discarded car timing belts. To investigate different characteristics of the concrete specimens several destructive and non-destructive tests, such as compressive strength, modulus of rupture, flexural toughness, ultrasonic velocity and electrical resistance tests were carried out. In addition, slump flow tests were conducted on the fresh concrete. Experimental results from the study showed that the use of low percentages (up to 0.5%) of waste fibres improved the modulus of rupture and flexural toughness. Based on ultrasonic and... 

In recent years, fuel cells have been proposed as an alternative option to conventional energy conversion systems. Fuel cell is an electrochemical system that can convert chemical energy to electrical energy without combustion. High efficiency, low temperature performance, poor pollution, good reliability, flexibility in the production potential, low start-up time and high life expectancy are the major advantages of this system. The most important barriers to the use of fuel cells are high cost polymer membrane and using expensive platinum catalysts. Modeling of fuel cells in general will meet two objectives. The first, due to the complexity of the processes taking place within the cell,... 

The airport terminal is difficult to plan and design due to the different components and the intricate complexity of its parts. At the airport terminal, we face a queue system which simulation is always a good way to analyze. In addition, computer simulation using modern softwares with the capability to model different types of systems, including the airport terminal, while being less realistic than analytical models, is less costly than operational Exercise.In this study, a supportive approach for better and specific management of Iranian airport terminal buildings with discrete-event simulation is proposed, considering the need for managing the airport terminals building in the country and... 

Limited water resources in Iran have made dams an important part of the country’s infrastructure. As a result of the large number of in-progress and expected dam projects in the country, consideration of sustainability factors during planning, construction and operation phases of dam projects can create significant economical, social and environmental impacts in the long term. To come up with an inclusive sustainable development, new sustainability assessment approaches seek for sustainable development at the entire project’s life-cycle; they are looking for sustainable development at all design, construction, operation, maintenance and even demolition phases. In this research we have... 

The servomechanisms have wide industrial application such as robotics, Computer Numerical Control (CNC) machines, automated manufacturing and solar tracking. Several methods have already been proposed for servo motor control that the most important of them are Proportional Integral Derivative (PID), H2/H--, intelligent based controllers, and model predictive control. Problem specifications and user requirements, will determine the appropriate approach in each case. The aim of this thesis is construction of a real-life camera stabilizer to be used in the motion picture industry. Effects of base movement on the performance should be decreased by choosing appropriate sensors and control... 

Millimeter wave imaging systems have unique features and have been used extensively in a variety of applications including medical imaging, construction operations, places with high security such as airports, Nondestructive testing and etc. These systems provide high resolution, due to the order of wavelength which is several millimeter or centimeter in this band. Also in places with high security and for detecting the concealed objects under people’s clothing, these waves can easily pass through the materials and investigate the person’s body without causing health problems. A wide variety of these imaging systems , each with different design parameters and resolutions, have been proposed.... 

The purpose of this study is to identify and evaluate the risks of new contracts for Iranian oil contract IPC response to these risks During the past three decades Public attention on studies related to the risk of spread with great speed So that the review process as an effective and comprehensive common And covers almost all aspects of life. In theory, any contract associated with the degree of risk. Risks cannot be completely eliminated therefore; scientific approach to the problem of risk is nothing Apart from its management. With the development of the oil and gas industry, identify and manage risk is also of special importance in regulating international oil contracts and has been... 

Subwavelength metallic slit structures allow extraordinary transmission of light (EOT) at certein frequencies.In recent years, the effect of graphene layer on EOT has been investigated, which is used in the design of terahertz modulators. The electrostatic tuning ability of graphene electrical conductivity controls the resonance frequency and the amount of incident radiation absorption. Because of the single atomic thickness of graphene, the wide range control of incident light can not be achieved alone. However, by placing this layer with various 1-D and 2-D patterns on periodic metallic layers with EOT ability, high light modulations can be obtained. In particular, the structure of the... 

This thesis examines a new electromagnetic mode called line mode. This mode occurs when the boundaries have complementary surface impedances. It is possible to control the mode confinement by changing the surface impedance values. Impedance surfaces with non-complementary impedances guides the quasi-line mode, which is a mode between the line mode and the edge mode. Essential features of the line wave are its singularity over the line, its broad bandwidth, and its robustness to certain defects. Another significant characteristic of a line wave is that unlike surface waves in which it is not possible to change the spin orientation, in a line wave, the spin orientation can be altered by... 

Old urban texture has always been one of the concerns of Government due to its high extent and vulnerability. In recent decades, various programs have been implemented to improve and develop old urban texture. According to experts in this field, the government has faced many challenges in old urban texture development projects in recent years, some of which have caused the project to deviate from its first purpose or not be fully implemented. One of the most important challenges in this field, according to the multiple stakeholders, has been the proper stakeholders management. In this research, a framework based on building information modeling is presented to develop old urban texture. In... 

In this thesis, the optimal control structure selection and design of sparse multi-variable control systems is addressed. A fundamental challenge which frequently emerges in engineering, social, and economic sciences, is the optimal selection of a subset of elements, in order to maximally fulfil a design objective. In practice, it is required to solve this underlying selection problem in conjunction with a non-linear or non-convex optimization which is designed to ensure desired performance. The requirement to solve these two problems simultaneously is what makes it inherently difficult; one which has thus far eluded efforts to develop a systematic means of determining its solution. In spite... 

Annually there are many small-scale industry projects implemented in Iran, most of which are financed by local financial institutes. The financing agreements between project owners and financial institutes are usually formed and finalized during the initiation phase and are based on feasibility studies done at the early stages; before project design and construction begin. However, in many cases actual costs of projects exceed the costs estimated in feasibility studies which have been approved by financial institutes. Limited financial resources in the country, from one side, and the lengthy process of increasing the project financing limit, from another side, cause delays in the project... 

Eigenvalue analysis is a fundamental tool in control issues, however, in some abnormal matrixes it can lead to an incorrect judgment of the matrix dynamic behavior. Pesudospectra, as an eigenvalue generalization, can provide more extensive information of the system dynamic behavior, whereas, the obtained data from eigenvalue analysis can be incomplete. In applying robust controllers, the concept of uncertainty has been attracted researcher interest in system modelling, nevertheless, the controller implementation may not be fault free or the parameters may vary over time. In this project the aforementioned issue will be studied and additionally, the pseudospectra will be employed to design a... 

Nowadays, maintenance management is very important in manufacturing industries and reducing the time and cost of maintenance can have a significant impact on their performance. Traditional maintenance management systems have weaknesses such as poor user interface, lack of visualization and high complexity, limited access to required documents. On the other hand, in the process of implementation of maintenance management in manufacturing industries, weaknesses in teamwork and poor information flow between different groups, especially production and maintenance groups, are evident. For this purpose, a framework has been presented in this study to improve the process of maintenance management... 

Nowadays, the construction industry has undergone extensive changes, with the advent of new technologies, it has departed from the traditional project implementation methods. One of these technologies is Virtual Reality, which is becoming more widespread in various stages of the life cycle of a project from design to delivery. Providing an opportunity for people to see the details of the final construction before completing the project could be regarded as one of the capabilities of this technology. Also, evaluating the project’s features at the time of construction and having a close understanding of product’s reality are the other beneficial aspects of VR. Meanwhile, the emergence and...