Sharif Digital Repository

Cognitive radio faces specific challenges due to its special spectrum access scheme. Providing required QoS and preventing irrecoverable interference on the primary users is among the crucial requirements. Beam forming is one of the interference avoidance schemes utilized in MIMO networks. Most of the studies on this scheme assume that each symbol is transmitted via vectors in order to grant desired beam forming and specific combinations in the receiver. Since transmitting multiple symbols at every transmission can provide higher data rates, it seems necessary to exploit beam forming through matrixes instead of vectors. In this thesis, by neglecting the interference of the secondary user,... 

Energy consumption and pollutions especially carbon dioxide emissions are two of the main challenges in the cement industry. 5-7 percent of world’s carbon dioxide emissions is due to cement production while 900 kg of carbon dioxide is emitted for the production of a tone of cement. The main source of carbon dioxide emissions in a cement plant is the combustion of fuel to provide heating demands and also converting the ore into clinker. Therefore, any improvement in energy efficiency in a cement plant could reduce carbon dioxide emissions resulting from the combustion. Important ways of energy recovery in a cement plant are using the energy recovered from the exhaust gas in the preheater... 

Nowdays much of the organic solid waste and wastewater is buried using centralized and traditional methods. This leads to many problems, including groundwater pollution, methane emissions into the atmosphere and rapid transmission of disease. In order to avoid these problems, using a decentralized approach can be a good solution. In this study, recovery of organic waste and wastewater of residential buildings using anaerobic digester as a decentralized way, have been examined. Using experiments, the optimum mass ratio of organic solid waste and wastewater is obtained as 80% and 20% respectively. Biogas production model is developed using mass balance and Balance of electrons in redox... 

Nowadays, classic energy supply systems are rapidly shifting towards more efficient, with less pollution, and more economic energy systems. In the meantime, the growing dependence of human activities on energy sources and the reduction of fossil fuels resources as the main source of energy supply at present time, has led to fundamental changes in the energy policy of communities. The use of distributed power generation systems utilizing renewable energy sources is one of the solutions that have been proposed in this regard. This research aims to develop a local energy supply network for a specific rural district using energy sources in place, so that the area is energy self-sufficient and... 

Population growth require increasing demand of Energy. The fossil fuels are the main source of energy. However, they are main source of carbon dioxide emissions. Considerable amount of fossil fuels is used in the power plants. Increasing trend of electricity consumption as well as the lack of alternative fuels such as renewables in the short time will increase the consumption of fossil fuels and emissions. The most important greenhouse gas emitted from the power plants is carbon dioxide. That's why the separation of carbon dioxide from the gas stream of power plants is necessary.Separation of the carbon dioxide by adsorption is considered in this project both experimentally and... 

In recent years, access to clean energy sources is the major instruments for sustainable development. Limitation of energy resources and the problems resulting from the use of fossil fuels was caused attention to biomass in different countries as a stable source of renewable energy. Organic waste in municipal solid waste and domestic wastewater are biomasses that can be used as a raw material used in the production of energy. Practical studies show that quality and quantity of municipal solid waste to produce biogas and bioethanol in Iran is very appropriate. In this process, the household solid waste and wastewater are in the anaerobic digestion reactors and fermentation systems without any... 

Excessive usage of fossil fuels and emissions of GreenHouse Gases (GHG) have led to many environmental problems such as climate change. The carbon dioxide emission accounts for 82% of GHG emissions and has the highest retention time in the atmosphere. The study on carbon dioxide is an important issue recently. The carbon dioxide emission from the energy and industrial sectors are 30% and 21%, respectively. It is possible to capture carbon dioxide from the flue gas may be utilized as material and fuel. Developing the utilization of carbon dioxide to replace storage is a solution for implementing carbon capture. The carbon planning model, is based on the selection of technology that is... 

Fossil fuel usage caused global warming and other environmental problems. Recently, biofuels are considered as an important alternative. However, the efficient usage of water and energy in their production may accelerate their diffusion. ETBE is a kind of oxidizing fuel additive that can be biologically produced from the ethanol reaction. High water and energy consumption in the production and separation process is still a challenge. In this work, the ETBE production from lignocellulosic feed are considered. Then, the effect of different parameters are investigated by performing sensitivity analysis. In the next step, the optimal pathway of water and energy use in the production of ETBE are... 

The aim of this research is retrofit of a crude oil distillation refinery unit in terms of water and energy. To do this, the refinery distillation unit is ategorized to different zones from the perspective of water and energy to determine the saving potentials. The energy network consists of the four sub-types includes exchangers and the water network consist of seven sub-sets including water and steam. In the next stage, the retrofit of the energy network and the process heat exchangers are done by using pinch analysis in the commercial software and discussed the economical possibility of pinch analysis for 20 heat exchangers in the crude oil preheating unit. Using the flow of flashed crude... 

Collaboration of different agencies working together in a geographical location to reduce waste and optimize the sharing of resources such as energy, raw materials, water, technology, information, etc., made Eco Industrial Parks (EIPs) as a significant step toward sustainability. EIPs has been the focus of increased attention in recent years. Much of the research on industrial parks is related to water and energy network design. This project seeks to identify suitable water network designs for eco industrial parks by identifying the challenges associated with industrial parks. Then, by presenting nonlinear mathematical model and related optimization solution, the superiority of the proposed... 

With the growing development of urban communities and population, the demand for water and treated sewage water has grown significantly. The environmental damage of polluted water has resulted in passing of new and strict environmental laws on wastewater discharge recently. In the present research, a hybrid system involving a power, heat and cool cogeneration and a carbon dioxide capture system has been designed for a typical wastewater treatment plant. The plant is optimized from economic and environmental criteria. The anaerobic digester is modeled using the ADM1 model. The biogas is directed into the hydrogen sulfide removal filter to remove the impurities and into the heat exchanger to... 

Continuous increase of energy demand, scarcity of resources, as well as environmental limitations have led to the need to reduce carbon emissions. In this research, an MINLP model based on the mathematical optimization formulation is proposed to reach this issue in a large cogeneration unit. Advantage of the hierarchical approach for carbon management are avoiding individual carbon reduction policies, and embedding emission control techniques in a hierarchical mathematical model that helps us to select the most appropriate policies and prioritize each other. In the carbon management hierarchy, the optimization of the base cycle is done at the first stage. Then, the use of renewable energies... 

According to the increasing population, the demand for electricity and its generation increased significantly. Increasing production of energy cause to degrade the environment. Given that about 92 percent of Iran's electricity is supplied by fossil fuel power plants, the importance of considering the negative role of power plants in environmental degradation is twice. In this study, the environmental impacts and sustainability of two steam and combined cycle power plants in Iran have been evaluated using emergy and life cycle analyses and their integration. In addition, the effects of fuel change and application of emission control methods on results of the life cycle and emergy analyses... 

This work presents a mathematical model for retrofitting the steam power plants in a refinery site. This problem is formulated as a mixed-integer nonlinear program (MINLP). Feasible retrofit alternatives suggested by experienced field engineers are investigated in sequence to examine the saving of those possible modifications. Furthermore, techno economic simulation of water and energy recovery systems from boiler flue gasses has been examined to obtain the optimal condition of these systems. For heat recovery, a systematic model for using organic Rankine cycle has been developed and results showed that toluene is the best possible working fluid in this case. Finally, water absorption cycle... 

In recent years, there has been the extensive researches on energy and water efficiency due to the increasing stress on these resources. Therefore, the water-energy nexus in large industries, especially power plants, has become very important. In the present study, the water and energy nexus has been analyzed using energy analysis tools, exergy, economic and environmental in a combined cycle power plant. The nexus are observed in the boiler blow-downs, leakage of steam traps, cooling of the air entering the compressor and injection of steam into the combustion chamber, which have been studied in different scenarios to improve water and energy consumption and reduce environmental impact. In... 

Increasing population growth and scarcity of fresh water resources have created the challenge of water supply, especially in the Mena region. Thus, many countries in the region have turned to innovation in the development of high-energy seawater desalination technologies. Utilizing the waste heat of refineries in the desalination industry can reduce costs and preserve the environment. In this article, effective ways to use the waste heat of other flue recovery steam of Bandar Abbas oil refinery are investigated. The integration of the heat recovery system consisting of recuperative heat exchangers and heat pipes with thermal desalination plants is investigated by multi-stage flash and... 

The growing amounts of generation of electronic wastes (e-waste) and their increasing environmental impacts require a special optimal waste management strategy. Many different methods have been developed to managing e-waste. To make the best choices according to the conditions of each system, having an adequate knowledge of all methods and comparing them is the most important point. This research aims to design a system for managing e-waste by selecting mobile phones as an example of electronic waste and find the optimal condition of the system to increase economic benefits and reduce environmental impact. Recycling and landfill are selected as the main methods in this project. Four lines... 

Preserving and promoting the health of citizens in a society is one of the most important problems addressed in any country. The power sector discharges a huge volume of carbon dioxide which intensifies the climate change and consequent human health problems.The goal of this study is to evaluate the ultimate effect of climate change caused by power plant emissions on the human health using life cycle analysis approach for different provinces in Iran. An integrated model has been developed to evaluate the impact of climate change due to power plant emissions on the human health. This model includes the equations regarding the variations in carbon dioxide concentration in the atmosphere,... 

Iran has many fossil fuels resources and today due to several reasons such as the environmental effects caused by burning these fuels, the depletion of fossil resources and energy security, the pattern of fuel production and consumption has changed.In recent years biofuels received the attention of researchers all over the world due to the sustainability of energy supply and their positive environmental effects. The agricultural wastes and Residues may be used to produce biofuels. Qazvin province, with its high potential of agriculture, can provide many sources of agricultural waste and residues for the production of biofuels. In this research, the aim is to optimize the biofuels supply... 

Due to the increase in population and the migration of people from rural to urban areas, the amount of municipal solid waste is increasing. Therefore, waste management is one of the most important social, economic, and even cultural issues in society now. In this research, one of the methods of waste management, i.e. energy production from waste based on municipal solid waste incinerators, will be investigated. Considering the sensitive environment of Mazandaran province, this province was chosen as the study area of the research. In the methodology of this research, after pre-processing the waste data of the case study, these data were determined as input conditions to the...