Search for: air
Total 752 records
Simulation of the time structure of Extensive Air Showers with CORSIKA initiated by various primary particles at Alborz-I observatory level, Article New Astronomy ; Volume 61 , 2018 , Pages 5-13 ; 13841076 (ISSN) ; Moghaddam, S. M ; Sharif University of Technology
Elsevier B.V 2018
A detailed simulation of showers with various zenith angles in atmosphere produced by different primary particles including gamma, proton, carbon, and iron at Alborz-I observatory level (35∘43′N, 51∘20′E, 1200 m a.s.l= 890 gcm−2), in the energy range 3 × 1013 eV–3 × 1015 eV, has been performed by means of the CORSIKA Monte Carlo code. The aim of this study is to examine the time structure of secondary particles in Extensive Air Showers (EAS) produced by the different primary particles. For each primary particle, the distribution of the mean values of the time delays of secondary particles relative to the first particle hitting the ground level in each EAS, <τi>=
, and the distribution...
Article Urban Climate ; Volume 27 , 2019 , Pages 446-456 ; 22120955 (ISSN) ; Hassani, A ; Hosseini, V ; Sharif University of Technology
Elsevier B.V 2019
The city of Tehran, the capital of Iran, has been facing severe air quality problems. The air quality of Tehran has been stated as unhealthy over one-third of year during the last two decades. According to the last emission inventory of Tehran for the base year of 2013 mobile sources contribute by about 6, 46, 98, 87, and 70% of total primary SOx, NOx, CO, VOC and PM emission. A number of policies have been implemented in Tehran during the last two decades to tackle the air quality issue. Concentrated mostly on transportation sector, these policies aimed to improve fuel quality and emission performance of vehicles. Nevertheless, there is no quantified evaluation regarding the effectiveness...
Article Experimental Astronomy ; Volume 13, Issue 1 , 2002 , Pages 39-57 ; 09226435 (ISSN) ; Anvari, A ; Ghomi, M. K ; Purmohammad, D ; Samimi, J ; Rachti, M. L ; Sharif University of Technology
We have studied Extensive Air Showers (EAS) with two small arrays of 1 m2 scintillation detectors in Tehran, 1200 m above sea level. The distribution of air showers in zenith and azimuth angles has been studied and a cosn θ distribution with n = 7.2×0.2 was obtained for zenith angle distribution. An asymmetry has been observed in the azimuthal distribution of EAS of cosmic rays because of magnetic field of the Earth. Amplitudes of the first and the second harmonics of observed distribution depend on zenith angle as AI≈(0.02 + 0.35 sin2 θ)×0.02, and AII(0.03 + 0.42 sin4 θ)×0.03. Meanwhile, the uncertainties arising from the instrument, transit location of shower particles in the scintillator...
Application of Dependency Structure Matrix to airspace sectorization and improving the distribution of the workload among controllers, Article 16th International Dependency and Structure Modelling Conference, DSM 2014 ; 2014 , p. 149-156 ; Malaek, S. M. B ; Sharif University of Technology
This work investigates the application of Dependency Structure Matrix (DSM) to problems with fast dynamics, such as airspace sectorization. The aim of this paper is to use a powerful mathematical tool to distinguish relevant agents in a busy airspace with a logical and meaningful distribution of the workload among air traffic controllers. This approach will help prevent controllers from getting exhausted in busy airspaces and increase the overall capacity of the airspace. It could also serve as a logical interface to simulate the chance of human error in a controlled aerodrome. Different case-studies by the authors reveal that adding realtime capabilities to the existing platform can be very...
Article International Journal of Civil Engineering ; Volume 15, Issue 2 , 2017 , Pages 195-203 ; 17350522 (ISSN) ; Fazelian, M ; Sarkardeh, H ; Sharif University of Technology
Springer International Publishing 2017
Air–water flow is a complex and challenging subject in many engineering fields as well as hydraulic engineering; and discovery of its characteristics can help the engineers to predict and analyze a probable phenomenon. In the present paper, development of a device capable of measuring the flow velocity, air concentration, diameter and counts of bubbles in air–water flows is described. The heart of the present device is two resistive probes with a novel configuration. Being pressure and corrosion resistant and also having negligible resistivity in the flow are some of the unique features of the employed needles. Moreover, sampling frequency and time can be adjusted for the intended...
Developing air exchange rate models by evaluating vehicle in-cabin air pollutant exposures in a highway and tunnel setting: case study of Tehran, Iran, Article Environmental Science and Pollution Research ; 2018 ; 09441344 (ISSN) ; Arhami, M ; Delavarrafiee, M ; Ketabchy, M ; Sharif University of Technology
Springer Verlag 2018
The passengers inside vehicles could be exposed to high levels of air pollutants particularly while driving on highly polluted and congested traffic roadways. In order to study such exposure levels and its relation to the cabin ventilation condition, a monitoring campaign was conducted to measure the levels inside the three most common types of vehicles in Tehran, Iran (a highly air polluted megacity). In this regard, carbon monoxide (CO) and particulate matter (PM) were measured for various ventilation settings, window positions, and vehicle speeds while driving on the Resalat Highway and through the Resalat Tunnel. Results showed on average in-cabin exposure to particle number and PM10 for...
Article ASME 2007- 26th International Conference on Offshore Mechanics and Arctic Engineering 2007, OMAE2007, San Diego, CA, 10 June 2007 through 15 June 2007 ; Volume 4 , 2007 , Pages 283-292 ; 0791842703 (ISBN); 9780791842706 (ISBN) ; Rad, M ; Amini, H ; Rishehri, M ; Sharif University of Technology
Air cavity ship concept has received some interest due to its potential on viscous resistance reduction for high speed craft. Air-cavity ships (ACS) are advanced marine vehicles that use air injection at the wetted hull surfaces to improve a vessel's hydrodynamic characteristics. Air is supplied through nozzles under a profiled bottom to generate an air cavity beneath such a ship, so that a steady air layer separates a part of the bottom from contact with water, consequently reducing hydrodynamic resistance. Resistance tests were conducted with two forms: first of which was planning catamaran hull form, and second one was an alternative form with an air cavity injection under its bottom...
M.Sc. Thesis Sharif University of Technology ; Sohrabpour, Mostafa ; Khalafi, Hossein
Total air particulate matter of the city of Isfahan has been measured for elemental characterization in four principal directions of the city and during the year 2007-2008. High volume air samplers using whatman 41 filters have been utilized and instrumental neutron activation analysis has been used as the analytical method. Twenty one elements arising from seasonal and geographical distributions of the various elements have been determined. These distribution patterns have been discussed in view of the prevailing wind direction, location of the industrial facilities, and the Pearson correlation coefficients
M.Sc. Thesis Sharif University of Technology ; Erhami, Mohammad
In recent years, in Tehran, air pollution became one of the major problems in this city. Among air pollutants, particle matter (PM) is very important in aspect of negative effect on environment and human health. Effective control of these particles requires correct determination of rules and adopting appropriate managing policy which are mostly very cost-consuming. Rules determination and adopting appropriate policy is very challenging in Tehran due to lack of sufficient information about concentration dispersion of such particles. The aim of this study is to recognize the factors of producing PM10 and appropriate understanding of changes of particle matter concentration of Tehran by...
Feasibilty Study of Using Condensation in Increasing Diameter of Airborne Particulate Matter to Enhance Control Efficiency, M.Sc. Thesis Sharif University of Technology ; Arhami, Mohammad
Particles with aerodynamic diameter of less than 10 μm can effectively pass through respiratory system and deposit on pulmonary areas wich cause adverse health effects. These particles are divided in to coarse particles (diameter: 2.5 to 10 μm) and fine particles (diameter < 2.5 μm). Fine particles can be more harmful for human’s health and harder to remove by air pollution control machines compare to coarse particle so it is crucial to find methods to enlarge the size of these particles. In this regards common methods such as utilizing electricity are costly and not efficient enough. Hence other economical and efficient methods such as using condensation are eamined. In this study the...
M.Sc. Thesis Sharif University of Technology ; Shamsaei, Abolfazl ; Ghaemian, Mohsen
The purpose of this study is to investigate the entrapment and movement of air pockets in the bottom outlet of dams and numerical simulation of the process of entrapment and entrainment of air pockets. One of the most common problems with bottom outlets is the air-water mixture flow. The main purpose of this study is to investigate the causes of air pockets in pressurized tunnels before service and emergency gates in the bottom outlets and to provide effective solutions to prevent the occurrence of unwanted air entrapment and many problems resulting from it. To do this, using FLOW-3D flow simulator, the way of entraping air pockets in the Bottom outlet of Darian Dam has been investigated and...
Permissible emission limit estimation via iterative back-calculation: Case of Assaluyeh energy zone, southern Iran, Article Integrated Environmental Assessment and Management ; Volume 14, Issue 1 , 2018 , Pages 130-138 ; 15513793 (ISSN) ; Saboohi, Y ; Tsatsaronis, G ; Sharif University of Technology
In the present research work, an environmental policy procedure for setting a cap on emissions, as a crucial step in any total emission control system, has been provided and evaluated. It is shown that general regulations on emission intensities and rates do not guarantee that ambient air quality standards are met in intense industrial zones. Local emission limits are necessary to meet ambient air quality standards in these zones. To that end, we used dispersion simulators to back-calculate pollutant concentration thresholds for a large and intense energy system in the Assaluyeh region of southern Iran. Verified modeling results indicate 218 d of pollutant concentration threshold exceedance...
M.Sc. Thesis Sharif University of Technology ; Shayegan, jalaloddin ; Massoudinejad, Mohammad Reza
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...
Article 12th International Conference on Indoor Air Quality and Climate 2011, 5 June 2011 through 10 June 2011 ; Volume 2 , June , 2011 , Pages 1082-1083 ; 9781627482721 (ISBN) ; Sajadi, B ; Tian, Y ; Goldasteh, I ; Ahmadi, G ; Ferro, A. R ; Sharif University of Technology
Article Urban Climate ; Volume 17 , 2016 , Pages 216-229 ; 22120955 (ISSN) ; Taghvaee, S ; Hosseini, V ; Afshin, H ; Sharif University of Technology
Tehran with a population of 8.2 million urban residents, suffers from rapid urbanization in recent years resulting in severe air pollution. The aim of this study is to develop a high resolution emission inventory of primary air pollutants for Tehran. Tehran pollution sources are classified into two major categories. Mobile sources, including vehicles such as passenger car, taxi, motorcycle, pickup, minibus, bus and truck, and stationary sources; consisting of industries, general service and household, energy conversion, terminals and gas stations. The emission of SOx, NOx, CO, VOCs and PM in the year of 2013 were estimated as 37.411 kt, 85.524 kt, 506.690 kt, 83.640 kt and 8.496 kt,...
Characterizing the effect of traffic density on ambient CO, NO2, and PM2.5 in Tehran, Iran: an hourly land-use regression model, Article Transportation Letters ; 2017 , Pages 1-11 ; 19427867 (ISSN) ; Jamshidi, H ; Samimi, A ; Sharif University of Technology
Economic development and population growth in Tehran has increased demand for goods movement and road transportation. This trend has increased mobile source emissions and citizens’ exposure, imposing severe health risks. We used the framework of Land-Use Regression models to quantify the effect of real-time traffic, within buffer distance, on hourly exposure of CO, NO2, and PM2.5. Effect of residential, industrial, and governmental land-use in addition to the effect of pollution sources, such as construction sites and airport were assessed on air pollution. Meteorological variables were also employed to adjust between day variations. R-squared of the models were 38, 27, and 38% for CO, NO2,...
Article Energy for Sustainable Development ; Volume 39 , 2017 , Pages 21-28 ; 09730826 (ISSN) ; Bahadori, M. N ; Dehghani Sanij, A. R ; Sharif University of Technology
Elsevier B.V 2017
Passive cooling systems such as wind towers or wind catchers can create thermal comfort for building residents in hot and dry regions. This paper introduces an experimental study of a modular design of wind tower called the modular wind tower with wetted surfaces. Air temperature, relative humidity (RH) and airflow velocity parameters were measured at different times and at points when the velocity of the ambient air was zero. The results show that the modular wind tower can decrease the air temperature by an average of 10 °C and increase the relative humidity of airflow in a building by approximately 36% on average. Additionally, the wind tower can create the airflow velocity entering the...
Performance optimization of polymeric porous membrane-based liquid desiccant air dehumidifier used in air conditioning system, Article International Journal of Energy and Environmental Engineering ; Volume 11, Issue 1 , December , 2020 , Pages 55-71 ; Fazelpour, F ; Mousavi, S. A ; Sharif University of Technology
In this study an experimental design was developed to optimize the performance and structure of a membrane-based parallel-plate liquid desiccant dehumidifier used in air conditioning regeneration system which operates under high humidity weather conditions. We conducted a series of polymeric porous membranes with different compositions fabricated that were prepared with various weight percentages of polysulfone (PSU), mixed with N-methyl-2-pyrrolidone (NMP) and dimethyl form amide (DMF) solvents. Furthermore, the designed experiments were performed under various operating conditions, indicating that the dehumidification efficiency declines with increasing flow rate, temperature, and...
Impact of mobile source emission inventory adjustment on air pollution photochemical model performance, Article Urban Climate ; Volume 32 , 2020 ; Hosseini, V ; Sharif University of Technology
Elsevier B.V 2020
Coupled weather forecasting and chemical transport models are useful tools to evaluate air pollution episodes in big cities for the purpose of forecasting and air pollution abatement measures' evaluation. However, large set of accurate data of various sources and modeling calibrations are needed for such complex modeling system to be reliable. The problem becomes more obvious when the model is operated over a domain in which there is a general lack of accurate input data such as emission inventory data. The current study investigates the possibility of model tuning for more accurate prediction of air pollutant concentrations in the city of Tehran in an air pollution episode as a case study....
Article Atmospheric Pollution Research ; Volume 11, Issue 3 , 2020 , Pages 429-442 ; Hoshyaripour, A ; Shahbazi, H ; Hosseini, V ; Sharif University of Technology
Elsevier B.V 2020
An assessment of trends in main air pollutant concentrations (including CO, SO2, NO2, O3, PM2.5, and Asbestos) is conducted for the years 2005–2016 for the city of Tehran, Iran. The focus has been on the contribution of anthropogenic emissions to the observed trend, particularly the role of related mitigation plans implemented in the period of interest. A significant decreasing trend (about 50%) was observed in CO and SO2 concentrations during the considered time interval, which was explained by improvement plans in fuel quality and vehicle emission standards. While a substantial elevation (more than 50%) in NO2 levels was detected over the study period, variant trends were observed during...