Sharif Digital Repository

Risk management is the systematic application of management policies, procedures and processes related to risk analysis, assessment and control activities. Risk management is the process of documenting the final decisions made and identifying and applying criteria that can be used to bring risk to an acceptable level. Costs have been studied separately as less attention has been paid to the combination of these two factors. In this study, the combined effect of these two factors on projects in the first place and then on construction, operation and transfer projects has been investigated. The statistical population of the present study consists of 250 contractors and employers of... 

One of the features of a project is its uniqueness, if two sets of activities are the same neither of them will longer be included in the project definition. A method in two projects with the same nature may yield inverse results of each other. Therefore, it is necessary to study the parameters affecting the project carefully before any action. So far, some research has been conducted in this area and it has been tried to perform case study on qualitative and quantitative parameters of the project. By investigating a number of common factors in most civil engineering projects, especially megaprojects, the present study attempts to identify and examine exquisite and effective parameters and... 

Startups mostly originated from creating an idea and introduced themselves as a new plan for optimization and development in societies. Being exquisite foreclosed any prediction of their future for their owners. On the other hand, the destination of an idea to be a product needs a solution. If the solution matches the structural behavior of the society, it will survive. Simulation of the structural behavior of society through genetic science creates a suitable gadget for the investigation of genetic logic. It accumulated the response of stakeholders of society in that subject according to the standard index in the format of information and database completely and meticulously. It depicts the... 

Project is defined as all activities with a definite beginning (start) and end (finish) aiming to achieve a defined target through defined resources. Literature reviews in the field of project management have shown the importance of project management capabilities for evaluation and optimization. There are many factors in project management which can lonely disrupt the timing and progress of the project. One of the most important factors that in effective and unfortunately has been less measured due to its intangible characteristic in the project is known to be the "human factor". This factor is involved from the first day a project starts and will continue till the end of the project.... 

This thesis contributes to development of a microscopic simulation of arterial traffic flow to estimate the impact of behaviour and culture of Iranian drivers on fuel consumption. To accomplish this task it is necessary to use a simulation software. But as existing simulation softwares include assumptions which are not applicable to traffic culture and architecture in Iran, a new software was developed. This software is based on non-lane disciplined driving parameters. The output is an estimation of average consumed fuel by a vehicle in general or a specified service condition. This estimation is an important parameter in decision making and planning for the future traffic and environmental... 

3D bioprinting is an additive manufacturing method that facilitates the deposition of the desired cells and biomaterials at any pre-defined location. This technique also enables control over the internal structure and external dimensions of printed constructs. Among various biomaterials used as bioinks, the bioinks derived from decellularized extracellular matrixes (dECMs) have attracted significant attention due to their bioactivity and being a rich source of biochemical cues. Here in this study, the decellularized amnion membrane (dAM) has been selected as the main component of the bioink formulation because of its biocompatibility, low immunogenicity, antibacterial property, abundance,... 

The main focus of this project is the fabrication of surface engineering scaffolds based on polyurethane and titanium dioxide. The research's aim is the creation of the synergistic properties of TiO2 and PU as a new strategy for engineering artificial autologous blood vessels. In the first section, PU-TiO2 nanocomposites were synthesized by co-insitu synthesis of nanoparticles and polymer. The nanocomposite films were prepared by solvent casting and thermally induced phase separation methods. Mechanical and biological properties of films were compared with pure PU film. In solvent casting method, the outcomes revealed that the rate of endothelialization of the nanocomposite scaffold after 7... 

Tissue engineering has the potential to revolutionize our health care system. Conceptually, lost or malfunctioning tissues will be replaced by man-made biological substitutes to restore, maintain, or improve function. Tissue engineering has already shown great promise to contribute to treatments of a myriad of diseases including osteoarthritis, cancer, diabetes, skin burns, cardiovascular conditions and various traumatic injuries. Tissue engineering is a highly multidisciplinary discipline that demands integration of knowledge, tools and skills from biology, chemistry, engineering and medicine. Integrating nano- and microtechnologies into clinically sized implants represents a major... 

In the last half century, the recording of the electrophysiological activities of the neurons has been one of the most effective methods for neuroscience development. One of the techniques used to record the activity of the nerve cells is the use of multi-electrode arrays (MEAs). Current MEAs still face limitations such as low signal-to-noise ratio (SNR) and low spatial resolution. There is a need to develop arrays that are smaller in size and have less impedance to achieve better spatial resolution and lower noise levels. The main focus of this research is on the designing and fabrication of multi-electrode arrays and improvement of their properties using nanostructures and conductive... 

Passenger cars (PCs) are of particular importance among mobile air pollutants emissions sources due to their population and significant share in air pollutants emissions and gasoline consumption. Moreover, ownership and use intensity of PCs are affected by socio-economic situation. The present study projects the future trends of air pollutants emissions and fuel consumption from PCs in Tehran by 1415 and assesses the effect of economic situation on the emission trends and effectiveness of emission reduction polices. Accordingly, the present study develops an interdisciplinary modeling framework, which combines econometric models with a bottom-up emission estimation model to simulate the... 

The issue under discussion in this paper is to optimize the fuel consumption of the Toyota Prius hybrid car. In order to solve this problem, the ADVISOR design model used by NREL in the Matlab / Simulink environment has been used. Various parts of this model are described. The optimization performed on this issue is based on the emotional controller. This controller works by simulating learning in animals based on encouraging and punishing them. With the introduction of the controller, the model and its inclusion in the fuel consumption control and its implementation have achieved good results. In the initial state and the controller in the model, the fuel consumption was 4.9 liters per 100... 

Dish-stirling system with an efficiency of nearly 30% is the most efficient technology among solar energy technologies. This system includes four main parts; Parabolic dish, solar tracker, receiver and Stirling engine and generator. In this system, first parabolic dish concentrates sun rays on its focus. A receiver is put on the focus to receive the heat radiated from dish. This receiver transfers the heat to a Stirling engine. In Stirling engine, expansion and contraction of gas helps piston to move and finally rotational mechanical work is done. With coupling a generator and Stirling engine we can generate electricity. Also for keeping the focus of sun rays on receiver we should have sun... 

Nowadays, electricity generation technology from renewable resources, especially solar energy has been very popular; specifically off-grid systems which have the ability of decentralized electricity generation. Dish/Stirling system is one of the most efficient technologies with capability of decentralized electricity generation from solar energy. The purpose of this study is design, optimization and analysis of a 10 KW Dish/Stirling system for different working location in Iran.
A mathematical model is introduced to analyze all the heat losses in different system components including parabolic dish, cavity receiver and Stirling engine. All the calculations are done with MATLABTM... 

According to, increasing use of energy in the world, issues such as increasing reenhouse gas’ emission, rising temperature on planet earth and air pollution have appeared Carbon dioxide is a major greenhouse gas that has a significant impact on increasing the temperature of earth. In recent years, attentions to carbon dioxide capturring and sequestration technologies have been increased. In this project molten carbonate fuel cell which is used as a new method for separating carbon dioxide from gaseous compounds of combustion process, is discussed. The aim of the project is to, investigate technical and
economic feasibility of using molten carbonate fuel cell for separating carbon... 

In this project, a co-generation system with the operation capacity of less than 1000 kilowatts has been studied. The main purpose of this project is to help decision makers in order to choose proper combination of micro turbines and/or reciprocating engines, with certain rating capacity, as the prime movers of this co-generation system. Some factors that have been considered in the decision making process are prime mover operation in various ambient temperatures, various altitudes and part-load conditions and also operational restrictions such as power to heat ratio, maintenance cost ratio and prime movers plant factor and also economic characteristics such as investment and operating cost... 

Thermo photovoltaic (TPV) is temperature oriented power generation system in which an emitter with temperature value around 1200℃ is usually used for radiation to the cells.Iron and steel industry as a fundamental industry has the most potential of interest for using TPV for recovering of energy. In steel casting unit there is rather high amount of radiation with temperature around 1000℃ which can be recovered by TPV system. The main aim of this dissertation is developing a mathematical model as well as verification of the model experimentally, in which the model is extended for possible using in iron and steel industry.The key modeling parameters of TPV include: open circuit voltage, short... 

The Engine of a vehicle is an energy conversion system, where specific chemical energy is converted in to heat in a combustion chamber. In order to reduce thermal tension in the cylandr, part of heat is removed with the help of circulating water and it is dissipated in the radiator. As a result, part of input energy is wasted in to the atmosphere through cooling system in each cycle of engine. Heat recovery in the cooling system and preheating combustion air of fuel could enhance energy efficiency and it may contribute to fuel economy. Heat recovery may be realized with the help of heat pipes. Heat pipes may be utilized for heat recovery and preheating fuel or air whichare inlet to the... 

Increased exploitation of energy resources has led to growing attention to the CHP systems due to their high efficiency. High energy loss in power transmission network, which is about 20 %, is an additional reason for growing attention to CHP. In addition to that, utilization of small scale CHP systems has provided ground for growing competition with distributed generators based on renewable energy resources. Selection of optimal technology based on economical and environmental criteria requires application of analytical tool. An analytical tool could avail itself of identifying optimal program for operation of cogeneration systems. The present research work has been implemented to develop... 

During the last 5 decades, the operation of scramjet engines has not been without limitations and technical challenges; i.e., the start-up speed of the engine. Conventional scramjet engines do not have the ability to start from a standstill and even at a flight Mach lower than 5. Therefore, reducing the start-up speed of the scramjet engine is not only very attractive in terms of operation but it will also reduce many technical challenges. The purpose of this research is to identify and analyze the flight speed to start the scramjet engine and the requirements to achieve it. In this regard, first by examining the quasi-one-dimensional equations of gas dynamics, the effect of the static... 

Increasing the surge margin of compressors and preventing surge and stall phenomena have always been one of the main concerns of gas turbine engines. This research aims to numerically investigate the fluid injection effects on the surge margin in centrifugal compressors. In this regard, the NASA CC3 compressor is selected for validation purposes. Considering the available geometrical data, a simulation is performed by using Ansys software, and results are compared with those available from public literature.After the performance and accuracy of the fluid injection simulation results are validated, fluid injection is implemented in the newly selected location and its impact on the compressor...