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    Black carbon and PM2.5 monitoring campaign on the roadside and residential urban background sites in the city of Tehran

    , Article Atmospheric Environment ; Volume 218 , 2019 ; 13522310 (ISSN) Taheri, A ; Aliasghari, P ; Hosseini, V ; Sharif University of Technology
    Elsevier Ltd  2019
    Fine particulate matter characterized as PM2.5 is the most important criteria air pollutant in the city of Tehran. Tehran is one of the most polluted cities of the Middle East based on annual mean PM2.5 concentrations. Tehran emission inventory shows the large contribution of mobile sources to the total particles. PM2.5 source apportionment studies show large fraction of black carbon (BC) in the total mass of PM2.5, especially during the cold seasons. BC is the product of incomplete combustion that is mainly derived from diesel engines and rich-burned gasoline carburetor engines on scooters and light-duty vehicles. The present study shows the results of a large experimental campaign in which... 

    Evaluation of tehran clean air action plan using emission inventory approach

    , Article Urban Climate ; Volume 27 , 2019 , Pages 446-456 ; 22120955 (ISSN) Shahbazi, H ; 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... 

    Mechanisms of joint formation throughout semisolid stir welding of AZ91 magnesium alloy

    , Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 23, Issue 9 , September , 2013 , Pages 2585-2590 ; 10036326 (ISSN) Hosseini, V. A ; Aashuri, H ; Kokabi, A ; Sharif University of Technology
    Joining in the semisolid state is considered a possible method to join alloys to each other. The mechanisms taking part in semisolid stir welding of AZ91 alloys were investigated. Two 7.5 mm-thick AZ91 pieces and a 2 mm-thick Mg-25%Zn interlayer piece were placed in a heating plate. After holding for 3 min at a desired temperature, the weld seam was stirred by a rotational tool. The heating plate was travelled on a trolley at a constant speed of 4.6 cm/min. In addition, one sample was welded without interlayer. Evolution of welding as a function of stirring rate, tool shape and temperature was studied throughout this welding process with scanning electron and optical microscopes. Interlayer... 

    Effect of reformer gas blending on homogeneous charge compression ignition combustion of primary reference fuels using multi zone model and semi detailed chemical-kinetic mechanism

    , Article Applied Energy ; Volume 179 , 2016 , Pages 463-478 ; 03062619 (ISSN) Neshat, E ; KhoshbakhtiSaraya Saray, R ; Hosseini, V ; Sharif University of Technology
    Elsevier Ltd  2016
    This study mainly aims to investigate the effect of reformer gas (RG) addition on the performance of homogeneous charge compression ignition (HCCI) engines using a multi zone model. The developed model is validated using a wide range of experimental data of a cooperative fuel research engine. Blended fuels of isooctane and n-heptane, known as primary reference fuels, with different octane numbers are used as the main engine fuel. A semi detailed chemical-kinetic mechanism containing 101 species and 594 reactions is used to simulate the combustion of blended fuels. The study is performed with different percentages of RG (0–30%). The results show that RG reduces the rate of some H abstraction... 

    A hierarchical sub-chromosome genetic algorithm (Hsc-ga) to optimize power consumption and data communications reliability in wireless sensor networks

    , Article Wireless Personal Communications ; Volume 80, Issue 4 , 2015 , Pages 1579-1605 ; 09296212 (ISSN) Hosseini, E. S ; Esmaeelzadeh, V ; Eslami, M ; Sharif University of Technology
    High reliability and low power consumption are among the major requirements in design of wireless sensor networks (WSNs). In this paper, a multi-objective problem is formulated as a Joint Power consumption and data Reliability (JPR) optimization problem. For this purpose, a connected dominating set (CDS)-based topology control approach is proposed. Our objective is to self-organize the network with minimum interference and power consumption. We consider the power changes into a topology with minimum CDS infrastructure subject to connectivity constraints. Since this problem is NP-hard, it cannot be dealt with using polynomial-time exact algorithms. Therefore, we first present a genetic... 

    Investigation of the effect of reformer gas on PRFs HCCI combustion based on exergy analysis

    , Article International Journal of Hydrogen Energy ; Volume 41, Issue 7 , 2016 , Pages 4278-4295 ; 03603199 (ISSN) Neshat, E ; Saray, R. K ; Hosseini, V ; Sharif University of Technology
    Elsevier Ltd  2016
    Lack of a direct method to control combustion timing is one of the main disadvantages of homogeneous charge compression ignition (HCCI) engines. Fuel blending, in which two fuels with different auto-ignition characteristics are blended, can be used to control combustion timing. Utilizing different additives is another method for HCCI combustion control. The aim of this research is investigation on the effect of reformer gas addition on the availability terms in HCCI engines fueled with primary reference fuels (PRFs). A multi zone model (MZM) coupled with a semi detailed chemical kinetics mechanism is used for calculation of different terms of exergy analysis. Heat and mass transfer between... 

    Investigating the effect of the heat transfer correlation on the predictability of a multi-zone combustion model of a hydrogen-fuelled spark ignition engine

    , Article Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ; Volume 230, Issue 1 , 2016 , Pages 70-81 ; 09544070 (ISSN) Tabatabaie, T ; Ehteram, M. A ; Hosseini, V ; Sharif University of Technology
    SAGE Publications Ltd  2016
    Research on the heat transfer in hydrogen-fuelled spark ignition engines indicates that the two most common heat transfer correlations, namely the Annand correlation and the Woschni correlation, cannot perfectly predict the heat flux during the engine cycle. This questions the accuracy of thermodynamic hydrogen engine models because the heat transfer is one of the important submodels in the development of a thermodynamic model. In addition, the Hohenberg correlation and the Shudo-Suzuki correlation have not been evaluated for hydrogen engines. In this study, a thermodynamic model of the closed cycle of a spark ignition engine is developed with a multi-zone combustion submodel to predict the... 

    An experimental study on low temperature combustion in a light duty engine fueled with diesel/CNG and biodiesel/CNG

    , Article Fuel ; Volume 262 , 2020 Ghaffarzadeh, S ; Nassiri Toosi, A ; Hosseini, V ; Sharif University of Technology
    Elsevier Ltd  2020
    Low temperature combustion potentially can improve engine efficiency coupled with the benefits of low nitrogen oxides, and particulate matter emissions, and vice versa high unburned hydrocarbon and carbon oxide emissions through in-cylinder fuel reactions. In this survey, the experiments were carried out using a modified one-cylinder reactivity controlled compression ignition engine, dual-fueled diesel/compressed natural gas and biodiesel/CNG, to investigate the effects of direct injection strategies on the engine combustion efficiency and emission characteristics. Different ratios of biodiesel blends at different premixed ratios were applied to the dual-fuel engine. The results showed that... 

    Modeling particle deposition in the respiratory system during successive respiratory cycles

    , Article Scientia Iranica ; Volume 27, Issue 1 B , February , 2020 , Pages 215-228 Nemati, H ; Saidi, M. S ; Hosseini, V ; Sharif University of Technology
    Sharif University of Technology  2020
    This study uses a 5-lobe symmetric model to investigate total, lobar and generational particle deposition fractions in the lungs during successive cycles. It was found that for the particle size between 0.05 and 2 μm and the tidal volumes greater than 1000 ml, the effect of successive cycles helped predict more deposition fraction per cycle up to about 16% than that of a single cycle. The mentioned range of tidal volumes corresponds to light or heavy physical activities. Therefore, it can be understood that people, when physically active, exposed to particulate matter within the mentioned size range are at higher health risk as compared to both the resting state and the same state... 

    A comparison of light-duty vehicles' high emitters fractions obtained from an emission remote sensing campaign and emission inspection program for policy recommendation

    , Article Environmental Pollution ; Volume 286 , 2021 ; 02697491 (ISSN) Hassani, A ; Safavi, S. R ; Hosseini, V ; Sharif University of Technology
    Elsevier Ltd  2021
    Urban transportation is one of the leading causes of air pollution in big cities. In-use emissions of vehicles are higher than the emission control certification levels. The current study uses a roadside remote sensing emission monitoring campaign to investigate (a) fraction of high emitters in the light-duty vehicle (LDV) fleet and their contributions to the total emissions, (b) emission inspection (I/M) programs' effectiveness, and (c) alternate fuel (natural gas) encouragement policy. LDVs consist of passenger or freight transport vehicles with four wheels equivalent to classes M1 and N1 of European union vehicle classifications. The motivation is to assess the current emission inspection... 

    Investigating various effects of reformer gas enrichment on a natural gas-fueled HCCI combustion engine

    , Article International Journal of Hydrogen Energy ; Vol. 39, issue. 34 , November , 2014 , p. 19799-19809 Voshtani, S ; Reyhanian, M ; Ehteram, M ; Hosseini, V ; Sharif University of Technology
    Homogenous charge compression ignition (HCCI) combustion has the potential to work with high thermal efficiency, low fuel consumption, and extremely low NOx-PM emissions. In this study, zero-dimensional single-zone and quasi-dimensional multi-zone detailed chemical kinetics models were developed to predict and control an HCCI combustion engine fueled with a natural gas and reformer gas (RG) blend. The model was validated through experiments performed with a modified single-cylinder CFR engine. Both models were able to acceptably predict combustion initiation. The result shows that the chemical and thermodynamic effects of RG blending advance the start of combustion (SOC), whereas dilution... 

    Characterization of newly developed semisolid stir welding method for AZ91 magnesium alloy by using Mg-25%Zn interlayer

    , Article Materials Science and Engineering A ; Volume 565 , 2013 , Pages 165-171 ; 09215093 (ISSN) Hosseini, V. A ; Aashuri, H ; Kokabi, A. H ; Sharif University of Technology
    Semisolid stir joining of AZ91 alloy was investigated by using mechanical stirring and Mg-25. wt%Zn interlayer. A 2. mm-thick interlayer was located between two 7.5. mm-thick AZ91 pieces. Then, they were heated to 530. °C, the semisolid temperature of both base metal and interlayer. A stirrer with a rotational speed of 1600. rpm was introduced into the weld seam. Optical microscopic and scanning electron microscope (SEM) investigation, microhardness test, shear punch test (SPT), and three points bending test were carried out to assess the properties of the joint. Results showed three distinctive zones: stir zone (SZ), compacted zone (CZ), and diffusional-mechanical affected zone (DMAZ). SEM... 

    A GIS based emission inventory development for Tehran

    , Article Urban Climate ; Volume 17 , 2016 , Pages 216-229 ; 22120955 (ISSN) Shahbazi, H ; Taghvaee, S ; Hosseini, V ; Afshin, H ; Sharif University of Technology
    Elsevier  2016
    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,... 

    Effect of welding parameters on semisolid stir welding of Mg–9Al–1Zn magnesium alloy

    , Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 26, Issue 10 , 2016 , Pages 2586-2594 ; 10036326 (ISSN) Hosseini, V. A ; Aashuri, H ; Kokabi, A. H ; Sharif University of Technology
    Nonferrous Metals Society of China  2016
    Semisolid stir welding of AZ91 was investigated with focus on the joining temperature and rotational speed. An Mg–25%Zn interlayer was located between two AZ91 pieces and the system was heated up to the semisolid state of base metal and interlayer. The weld seam was stirred using a drill-tip at different joining temperatures and rotational speeds. Optical and scanning electron microscopes were employed to study microstructure, cavity formation, and segregation. Hardness profile and shear punch test were also employed to rank the welds based on their quality and homogeneity. Results showed that the lowest cavity content (2.1%) with the maximum ultimate shear strength (about 188 MPa) was... 

    Optimization of head CT protocol to reduce the absorbed dose in eye lenses and thyroid: A phantom study

    , Article Iranian Journal of Medical Physics ; Volume 16, Issue 1 , 2019 , Pages 64-74 ; 1735160X (ISSN) Kalhor, P ; Changizi, V ; Hosseini, A ; Jazayeri, E ; Sharif University of Technology
    Mashhad University of Medical Sciences  2019
    Introduction: Utilization of computed tomography (CT) scans is increasing annually. This study aimed to reduce the absorbed dose of sensitive organs in the head (eye lenses and thyroid) and to assess changes in resultant images quality in head scans when the radiation dose is decreased. Material and Methods: An anthropomorphic phantom was examined with head protocols in both helical and sectional modes using two 16-slice CT scanners. The entrance surface dose of eye lenses and thyroid was measured with standard protocols and after reducing the mAS and kilo-voltage using thermo-luminescence dosimeters (TLDs). Results: In sectional mode with standard protocol, the highest surface dose was 2.3... 

    Air pollution trends in Tehran and their anthropogenic drivers

    , Article Atmospheric Pollution Research ; Volume 11, Issue 3 , 2020 , Pages 429-442 Torbatian, S ; 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... 

    Secondary organic aerosol formation from untreated exhaust of gasoline four-stroke motorcycles

    , Article Urban Climate ; 2021 , Volume 36 ; 22120955 (ISSN) Esmaeilirad, S ; Setyan, A ; Wang, J ; Hosseini, V ; Sharif University of Technology
    Elsevier B.V  2021
    This study investigates the secondary organic aerosol (SOA) formation potential of carburetor motorcycles exhaust. This type of two-wheeler is a popular means of transport in many Asian cities. A volatility-based numerical model was employed to predict SOA formation from a fleet of motorcycles in Tehran, capital of Iran. The fleet was a combination of four-stroke, gasoline-powered motorcycles with different engine displacement volumes. Total hydrocarbon (THC) emission factors of all motorcycles were previously measured in a chassis dynamometer laboratory according to cold start Euro-3 emissions certification test procedures. Due to incomplete combustion and lack of control on exhaust... 

    Agent-based time delay margin in consensus of multi-agent systems by an event-triggered control method: Concept and computation

    , Article Asian Journal of Control ; 2022 ; 15618625 (ISSN) Hosseini, S.H ; Tavazoei, M. S ; Kuznetsov, N. V ; Sharif University of Technology
    John Wiley and Sons Inc  2022
    This paper deals with defining the concept of agent-based time delay margin and computing its value in multi-agent systems controlled by event-triggered based controllers. The agent-based time delay margin specifying the time delay tolerance of each agent for ensuring consensus in event-triggered controlled multi-agent systems can be considered as complementary for the concept of (network) time delay margin, which has been previously introduced in some literature. In this paper, an event-triggered control method for achieving consensus in multi-agent systems with time delay is considered. It is shown that the Zeno behavior is excluded by applying this method. Then, in a multi-agent system... 

    Beneficial Role of oxygen in co and propylene oxidation over a pt-pd-based wiremesh catalyst as a retrofit emission control device for four-stroke gasoline spark-ignited motorcycles

    , Article Energy and Fuels ; Volume 35, Issue 12 , 2021 , Pages 10122-10133 ; 08870624 (ISSN) Lotfollahzade Moghaddam, A ; Hamzehlouyan, T ; Hosseini, V ; Mayer, A ; Sharif University of Technology
    American Chemical Society  2021
    Over 200 million motorcycles in use worldwide account for a substantial portion of global mobile source total hydrocarbons (THC) and carbon monoxide (CO) emissions. In Tehran, capital of Iran, ultrarich inefficient combustion in gasoline-fueled motorcycles results in significantly high CO and THC emissions. Motorcycle catalysts can reduce CO and C3H6(as a representative hydrocarbon) emission factors by 60-80%. In the present work, CO and propylene oxidation over a commercial Pt-Pd-based wiremesh catalyst is studied in a flow reactor setup under simulated conditions relevant to 125 cc four-stroke gasoline carburetor motorcycles. Steady-state individual and co-oxidation tests for CO and... 

    A novel regression imputation framework for Tehran air pollution monitoring network using outputs from WRF and CAMx models

    , Article Atmospheric Environment ; Volume 187 , 2018 , Pages 24-33 ; 13522310 (ISSN) Shahbazi, H ; Karimi, S ; Hosseini, V ; Yazgi, D ; Torbatian, S ; Sharif University of Technology
    Elsevier Ltd  2018
    Missing or incomplete data in short or long intervals is a common problem in measuring air pollution. Severe issues may arise when dealing with missing data for time-series prediction schemes or mean analysis. This study aimed to develop a new regression imputation framework to impute missing values in the hourly air quality data set of Tehran and enhance the applicability of Tehran Air Pollution Forecasting System (TAPFS). The proposed framework was designed based on three types of features including measurements of other stations, WRF and CAMx physical models. In this framework, elastic net and neuro-fuzzy networks were efficiently combined in a two-layer structure. The framework was...