Sharif Digital Repository

One of the issues that today is considered by planners and system operators in power systems, especially the Iranian power grid, is the high variation and the lack of uniformity of load curves in different hours of the day. This has led to the use of all installed capacity of the country's production only in peak hours, and in the low and intermediate times, a large amount of installed capacity is out of the circuit, which means Unused capital. This problem is more or less seen in world power networks with high load variation curves. Also, the production of renewable energies has always been fluctuating, and the production of power control to improve this fluctuation is very important. This... 

Electrostatic precipitators (ESPs) are widely recognized for their pivotal role in the collection of dust and particulate matter. ESPs are essential to ensure a particle- and dust-free atmosphere in industrial and non-industrial work environments. With the ever-increasing significance of maintaining air quality at the desired standards, the role of ESPs has gained paramount importance in mitigating airborne pollutants and protecting public health. Achieving higher collection efficiency for particulate matter and attaining cleaner air is of great importance in the design and selection of precipitators. On the other hand, particle collection efficiency is considered as a crucial factor for ESP... 

The problem of PM pollutants has become one of the main environmental concerns of Tehran city due to the growth of city population and industrialization. As a consequence of this problem there is an increasing trend in the number of unhealthy days in Tehran in terms of air quality in recent years. Solving this problem needs strict regulations to limit the amount of pollutants released from vehicles, industries and power plants. To help this cause, this study investigates the effect of emissions and climate change under RCP scenarios on future PM2.5 concentration in Tehran by using WRF-SMOKE-CMAQ modeling system. The result of simulation of climate conditions under RCP8.5 scenario in 2050... 

Several dust storms originated from western countries deserts of Iran hit different cities in Iran and substantially elevates PM10 levels. To the date, some studies on trend and origin of the dust storm have been carried out. However, not enough information is available on the contribution of different deserts around the country to the aerosol concentration in Iranian cities. In this study, the deserts of potential dust sources have been identified and their contributions to PM10 concentration in Tehran have been investigated. The PM10 data collected over a 5 year period from 2006 to 2010 at monitoring stations in Tehran were used. A statistical approach was implemented in order to determine... 

The article describes a new algorithm for the en-route conflict detection and resolution problem for flying aircrafts. In this new algorithm both horizontal and vertical maneuvers are considered. The proposed conflict resolution trajectories are optimized in the sense that they respect minimum deviation from the original path planned by all aircraft involved in the discovered conflict. The proposed horizontal maneuvers consists of three consecutive turns that guarantees return to the original path and can be done in both cooperative or non-cooperative manner. The algorithm searches different scenarios for conflict resolution between multiple aircrafts while preventing secondary conflicts.... 

In the present work, wet air oxidation of phenol over 7/3 MnO2/CeO2 composite oxide catalyst in trickle-bed and packed-bubble column reactors was modeled. Complexity of wet air oxidation reactions and catalyst poisoning with carbonaceous groups, on the surface and in the pores of catalyst, make the modeling process complicated. Plurality of mass balance equations which are confirmed in the catalyst pellet and in dynamic and static bed phase, also the equation of catalyst deactivation, lead us solve them simultaneously. In addition, the equations are two dimension and unsteady state and carbon of oxidation intermediates are present which make the modeling process more complicated. We are... 

The purpose of this study is to investigate the distribution of air flow and temperature in electric machines. The fluid flow equations are solved by using the characteristic Galerkin. The unsteady equations of the air flow and heat transfer between the rotor, stator and radial cooling channels of the generator are solved by finite element method. Tetrahedral elements are used, but hexahedral elements can also be used. The upwind method is used to discretize the convection terms, but the central difference for the diffusion parts, that is equal to Petrov-Galerkin method in steady state situation. Due to the large number of channels and specific geometry, to reduce the computation costs, the... 

Nowadays more than half of the world’s population lived in urban areas. That proportion is set to rise to 67% by 2050. This will cause urban mobility with serious problems. The concept of Urban Air Mobility (UAM) is proposed to avoid the problem to become a catastrophy. Due to environmental issues and also high operating costs, using copters as an air-taxi was not justifiable. As the technology in e-VTOL flourished, the desire of using of these vehicles in such a transportation system was increased. In this paper, besides previous investigations, the e-VTOL’s performance parameters’ influence on the characteristic of a civil air-taxi network is under investigation. In addition, this paper... 

In the building, can be used variaty of Heating, Ventilating and Air conditioning systems. Among the items that affect to select the hvac system can be pointed to building thermal demand and system energy consumpsion. simulation of this systems is one of the ways that can compare hvac systems in the building. according to Iran needs for preparation of software for optimization of energy carriers consumption in building proportional with existing matrials and equipment in the country, in this research has been tried methodology and modeling of hvac systems in the way developed that producted software is capable simply and practical for engineers be operational in a residential unit. In realy... 

Recent progress in developing Artificial Neural Network (ANN) meta-models has paved the way for reliable use of these models in the prediction of air pollutant concentrations in urban atmosphere. However, improvement of prediction performance, proper selection of input parameters and model architecture remain key challenges to their practical use. This study’s main objectives are: selecting proper input parameters for ANN meta-models, optimizing the ANN models to achieve the most accurate hourly prediction for a case study (City of Tehran), coupling the ANN method with filtered input data and evaluating its privilege. In the current study the ANNs were constructed to predict criteria... 

Particuale matters, as a criterion for evaluationg the air quality, have been one of the most important air pollutants through the last decade. Considering the adverse health effects of particulate matters, the importance of monitoring pollutant’s concentration is inevitable. While there are monitoring stations for evaluating the air quality, our knowledge is so limtted since there are few stations working, so there is a spatial and temporal gap. On the other hand, chemical transport models and remote sensing provide us a better chance to track the air quality thoroughly. Since chemical transport models are our only way of filling the gaps, they should be rigorous and accurate. In this study... 

Knowledge of Air-water two phase flows is significant to different engineering systems such as chemical reactors and power plant and petrochemical and petroleum industry. One of the most industrial cases of two phase flow is two phase flow in vertical large pipes. Because of gravity, two phase flow in Vertical pipes is different from horizontal pipes. Considering these flows can play a significant role in long-term reliability and safety of industrial systems. There are many parameters that effect on flow characteristics such as length and diameter of pipe and shape and condition of air inlet. Effect of air inlet is on the shape of bubbles and this can effects on flow pattern and another... 

In recent years, due to fires in mines around the world, the need to study the dynamic behavior of fire to understand how it spreads and design an appropriate fire extinguishing system to reduce damage to people and underground facilities has been felt. Mine fires are usually caused by external sources such as cable connections, methane gas explosions, or coal self-ignition due to oxygen uptake and rising temperatures.In this research, using Fire Dynamic Simulator (FDS) software, after drawing the geometry of a coal tunnel corridor in progress and creating a fire model through pyrolysis of PVC, fire extinguishing was performed by nozzles. If the nozzle does not succeed in extinguishing the... 

Building simple and effective models are essential to many applications, such as building performance diagnosis and optimal control. Detailed physical models are time consuming and often not cost-effective. Black box models require large amount of training data and may not always reflect the physical behaviors. In this study, a method is proposed to simplify the building thermal model and to identify the parameters of the simplified model. For instance, predicting the next-24-hour load in a building is essential for the optimal control of heating, ventilating and air-conditioning (HVAC) systems that use thermal or cool storage technology. In the first phase of this study, equations for... 

The lubricating oil is commonly used to cool down the moving parts of turbine gas systems. In many applications, this oil is cooled down using a recirculating water circuit. The water is then cooled down using an air-cooled heat exchanger. Any deficiency in aerothermodynamic design of such heat exchanger would result in high temperature of gas turbine moving parts such as bearings. Obviously, this mal-performance has adverse effect on the lifetime of these parts and their maintanence aspects. Since the good performance of air-cooled heat exchanger has numerous advantages for the performance of related gas turbine unit, it is mandatory to design these heat exchangers in minimum sizes and... 

In this study, for removing ammonia from air, biofilters which is suitable method for removing odors, volatile organic compounds and toxic materials are used. Biofiltration is an efficient, easy and cost effective, environmental friendly process for degradation of ammonia from waste air. Aim of this study is comparative study of biofilters application for ammonia elimination from industrial sites.In order to remove ammonia, two columns with 14 cm inner diameter were used. One of the columns is filled with vermicompost and mineral shell (mineral shell : vermicompost, 1 : 4) and another column is filled with concentrated sludge and scallop (scallop : concentrated sludge, 2 : 3). Each of the... 

To gain commercial competitive advantage in a constantly changing business environment, demand forecasting is very crucial for an organization in order to make right decisions regarding manufacturing and inventory management. The objective of this thesis is to propose a forecasting technique which is modeled by artificial neural-fuzzy networks. The effectiveness of the proposed approach to the demand forecasting issue is demonstrated using real-word data. Then we investigate a suitability of a decision-making model for airline route planning based on the so called “Game Theory”. The model is helpful to decide whether a new route is, in fact, needed. Different case studies reveal that... 

This research deals with pricing private automobiles entering a congested area in urban CBD to reduce auto-related air pollution. There are two factors affecting the pollution level: car volumes, and the weather condition. A Markov decision process is employed to find the optimal tolls and determine the prices for different states of the system, under several weather conditions. The demand for travel is elastic. It is assumed that users change modes in the short run. In longer terms, the part of the demand with shopping, recreation, or similar flexible trip purposes change the respective demand levels according to the price level. The study attempts to estimate elastic demand functions for... 

According to development of industry in every field such as nanotechnology and micro electro mechanical system (MEM) fabricating of high speed machining with micro dimension has been expanded. Micro spindles are such a device which is useful in many industries such as air space and electronic field. These machines can work in high speed and production rate with vast variety of features. Their dimensions are in millimeter range. So they can manufacture miniature features. Fabricating and technical science production of a high speed micro spindle with speed of more than 100000 RPM (micro macro milling) is purpose of this project. After to literature review according to science of micro... 

Poly (lactate-co-glycolate) is a typical biocompatible and biodegradable synthetic polymer. Addition of TiO2 nanoparticles improved compressive modulus of PLGA scaffolds and reduced fast degradation. Porous 3D scaffolds, which are synthesized using biocompatible and biodegradable materials, could provide suitable microenvironment and mechanical support for optimal cell growth and function. A novel method has been applied to fabricate PLGA/TiO2 scaffolds without using any organic solvent or porogen for nucleation compared to former ways, with aim of improving the biocompatibility, macroscale morphology and well inter-connected pores efficacy: Air-Liquid Foaming. Adjustment of the foaming...