scholarly journals CFD Simulation of the Dispersion of Exhaust Gases in a Traffic Loaded Street of Astana, Kazakhstan

2016 ◽  
Vol 9 (2) ◽  
pp. 158-166
Author(s):  
Ardak Akhatova ◽  
Assylan Kassymov ◽  
Meruyert Kazmaganbetova ◽  
Luis Ramon Rojas-Solórzano
Keyword(s):  
Cfd Simulation ◽  
Maximum Level ◽  
Weather Conditions ◽  
Control Measures ◽  
Convergence Criterion ◽  
Emission Rates ◽  
Wall Functions ◽  
Mesh Density ◽  
Volume Method ◽  
Future Work

The aim of this paper is to consider one of the most traffic-loaded regions of Astana city (Kazakhstan) and to determine the concentration of carbon-monoxide (CO) in the air during the peak hours. CFD analysis based on the SolidWorks-EFD platform was used to simulate the dispersion of contaminants given the estimated emission rates and weather conditions at the crossroad of Bogenbay Batyr and Zhenis Avenues in Astana. Turbulence prediction was based on k-ε model with wall functions. The governing equations were discretized using the finite volume method and a 2nd order spatial scheme. The mesh verification was based on 1% convergence criterion for a 50% of mesh density increment; air pressure near the wall of a selected building was chosen as the parameter to control the convergence. Numerical results are presented for prevailing conditions during all 4 seasons of the year, demonstrating that the highest levels of CO are recorded in summer and reach the values up to 11.2 ppm which are still lower than the maximum level admitted for humans. Nevertheless, obtained results show that Astana is gradually becoming a city that is likely to reach the critical levels of pollutants in the nearest future if control measures are not taken with enough anticipation. As for a future work, it is proposed to perform in-situ validation of specific scenarios to check and support the results obtained with CFD and to develop then specific policies for tackling the problem before it becomes evident.

scholarly journals CFD Simulation of the Dispersion of Exhaust Gases in a Traffic Loaded Street of Astana, Kazakhstan

2016 ◽  
Vol 9 (2) ◽  
pp. 158-166
Author(s):  
Ardak Akhatova ◽  
Assylan Kassymov ◽  
Meruyert Kazmaganbetova ◽  
Luis Ramon Rojas-Solórzano
Keyword(s):  
Cfd Simulation ◽  
Maximum Level ◽  
Weather Conditions ◽  
Control Measures ◽  
Convergence Criterion ◽  
Emission Rates ◽  
Wall Functions ◽  
Mesh Density ◽  
Volume Method ◽  
Future Work

The aim of this paper is to consider one of the most traffic-loaded regions of Astana city (Kazakhstan) and to determine the concentration of carbon-monoxide (CO) in the air during the peak hours. CFD analysis based on the SolidWorks-EFD platform was used to simulate the dispersion of contaminants given the estimated emission rates and weather conditions at the crossroad of Bogenbay Batyr and Zhenis Avenues in Astana. Turbulence prediction was based on k-ε model with wall functions. The governing equations were discretized using the finite volume method and a 2nd order spatial scheme. The mesh verification was based on 1% convergence criterion for a 50% of mesh density increment; air pressure near the wall of a selected building was chosen as the parameter to control the convergence. Numerical results are presented for prevailing conditions during all 4 seasons of the year, demonstrating that the highest levels of CO are recorded in summer and reach the values up to 11.2 ppm which are still lower than the maximum level admitted for humans. Nevertheless, obtained results show that Astana is gradually becoming a city that is likely to reach the critical levels of pollutants in the nearest future if control measures are not taken with enough anticipation. As for a future work, it is proposed to perform in-situ validation of specific scenarios to check and support the results obtained with CFD and to develop then specific policies for tackling the problem before it becomes evident.

scholarly journals Assessment of Emission Reduction and Meteorological Change in PM2.5 and Transport Flux in Typical Cities Cluster during 2013–2017

2021 ◽  
Vol 13 (10) ◽  
pp. 5685
Author(s):  
Panbo Guan ◽  
Hanyu Zhang ◽  
Zhida Zhang ◽  
Haoyuan Chen ◽  
Weichao Bai ◽  
...  
Keyword(s):  
Air Quality ◽  
Action Plan ◽  
Influence Factors ◽  
Pollution Prevention ◽  
Weather Conditions ◽  
Yangtze River Delta ◽  
Control Measures ◽  
Joint Control ◽  
Air Quality Model ◽  
Quality Model

Under the Air Pollution Prevention and Control Action Plan (APPCAP) implemented, China has witnessed an air quality change during the past five years, yet the main influence factors remain relatively unexplored. Taking the Beijing-Tianjin-Hebei (BTH) and Yangtze River Delta (YRD) regions as typical cluster cities, the Weather Research Forecasting (WRF) and Comprehensive Air Quality Model with Extension (CAMx) were introduced to demonstrate the meteorological and emission contribution and PM2.5 flux distribution. The results showed that the PM2.5 concentration in BTH and YRD significantly declined with a descend ratio of −39.6% and −28.1%, respectively. For the meteorological contribution, those regions had a similar tendency with unfavorable conditions in 2013–2015 (contribution concentration 1.6–3.8 μg/m3 and 1.1–3.6 μg/m3) and favorable in 2016 (contribution concentration −1.5 μg/m3 and −0.2 μg/m3). Further, the absolute value of the net flux’s intensity was positively correlated with the degree of the favorable/unfavorable weather conditions. When it came to emission intensity, the total net inflow flux increased, and the outflow flux decreased significantly across the border with the emission increasing. In short: the aforementioned results confirmed the effectiveness of the regional joint emission control and provided scientific support for the proposed effective joint control measures.

scholarly journals DOING L2 SPEECH RESEARCH ONLINE: WHY AND HOW TO COLLECT ONLINE RATINGS DATA

2021 ◽  
pp. 1-24
Author(s):  
Charles L. Nagle ◽  
Ivana Rehman
Keyword(s):  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Control Measures ◽  
Mixed Effects Models ◽  
Amazon Mechanical Turk ◽  
Intraclass Correlation Coefficients ◽  
Online Ratings ◽  
Speech Research ◽  
Future Work ◽  
Local Laboratory

Abstract Listener-based ratings have become a prominent means of defining second language (L2) users’ global speaking ability. In most cases, local listeners are recruited to evaluate speech samples in person. However, in many teaching and research contexts, recruiting local listeners may not be possible or advisable. The goal of this study was to hone a reliable method of recruiting listeners to evaluate L2 speech samples online through Amazon Mechanical Turk (AMT) using a blocked rating design. Three groups of listeners were recruited: local laboratory raters and two AMT groups, one inclusive of the dialects to which L2 speakers had been exposed and another inclusive of a variety of dialects. Reliability was assessed using intraclass correlation coefficients, Rasch models, and mixed-effects models. Results indicate that online ratings can be highly reliable as long as appropriate quality control measures are adopted. The method and results can guide future work with online samples.

scholarly journals The study of the numerical diffusion in computational calculation

2020 ◽  
Vol 310 ◽  
pp. 00039
Author(s):  
Kamila Kotrasova ◽  
Vladimira Michalcova
Keyword(s):  
Heat Transfer ◽  
Differential Equation ◽  
Numerical Simulation ◽  
Continuity Equation ◽  
Cfd Simulation ◽  
Flow Process ◽  
Ansys Fluent ◽  
Numerical Diffusion ◽  
Mesh Density ◽  
Computational Calculation

The numerical simulation of flow process and heat transfer phenomena demands the solution of continuous differential equation and energy-conservation equations coupled with the continuity equation. The choosing of computation parameters in numerical simulation of computation domain have influence on accuracy of obtained results. The choose parameters, as mesh density, mesh type and computation procedures, for the numerical diffusion of computation domain were analysed and compared. The CFD simulation in ANSYS – Fluent was used for numerical simulation of 3D stational temperature flow of the computation domain.

The Message of “APEC Blue” for the Prevention and Control of Urban Air Pollution in China

2016 ◽  
Vol 04 (04) ◽  
pp. 1650027
Author(s):  
Rong ZHU
Keyword(s):  
Air Pollution ◽  
Emergency Response ◽  
Prevention And Control ◽  
Urban Air Pollution ◽  
Pollution Prevention ◽  
Warning System ◽  
Weather Conditions ◽  
Control Measures ◽  
Atmospheric Pollutant ◽  
And Control

Analysis of the meteorological conditions for atmospheric pollutant dispersion before and after the 2014 APEC meeting shows very significant effects of air pollution prevention and control measures on the meeting. It proves that the proper measures to control air pollution in the Beijing-Tianjin-Hebei Region are: establishing a regional emergency response mechanism to reduce emissions in the case of heavy air pollution, strengthening the local emergency response measures for emission reduction, and enhancing the early warning system for weather conditions conducive to heavy air pollution.

Fast CFD Simulation of Horizontal Axis Wind Turbines

2010 ◽  
Author(s):  
Fabio De Bellis ◽  
Luciano A. Catalano ◽  
Andrea Dadone
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Cfd Simulation ◽  
Flow Distribution ◽  
Horizontal Axis ◽  
Wall Functions ◽  
Mesh Topology ◽  
Numerical Predictions ◽  
Horizontal Axis Wind Turbines ◽  
Time Required

The numerical simulation of horizontal axis wind turbines (HAWT) has been analysed using computational fluid dynamics (CFD) with the aim of obtaining reliable but at the same time affordable wind turbine simulations, while significantly reducing required overall resources (time, computational power, user skills), for example in an optimization perspective. Starting from mesh generation, time required to extract preliminary aerodynamic predictions of a wind turbine blade has been shortened by means of some simplifications, i.e.: fully unstructured mesh topology, reduced grid size, incompressible flow assumption, use of wall functions, commercial available CFD package employment. Ansys Fluent software package has been employed to solve Reynolds Averaged Navier Stokes (RANS) equations, and results obtained have been compared against NREL Phase VI campaign data. The whole CFD process (pre-processing, processing, postprocessing) has been analysed and the chosen final settings are the result of a trade-off between numerical accuracy and required resources. Besides the introduced simplifications, numerical predictions of shaft torque, forces and flow distribution are in good agreement with experimental data and as accurate as those calcuted by other more sophisticated works.

A Comprehensive Review of Spirit Drink Safety Standards and Regulations from an International Perspective

2017 ◽  
Vol 80 (3) ◽  
pp. 431-442 ◽  
Author(s):  
Xiao-Na Pang ◽  
Zhao-Jie Li ◽  
Jing-Yu Chen ◽  
Li-Juan Gao ◽  
Bei-Zhong Han
Keyword(s):  
Maximum Level ◽  
The United States ◽  
International Perspective ◽  
Control Measures ◽  
Alcoholic Beverages ◽  
Hydrocyanic Acid ◽  
The European Union ◽  
Safety Standards ◽  
Standards And Regulations

ABSTRACT Standards and regulations related to spirit drinks have been established by different countries and international organizations to ensure the safety and quality of spirits. Here, we introduce the principles of food safety and quality standards for alcoholic beverages and then compare the key indicators used in the distinct standards of the Codex Alimentarius Commission, the European Union, the People's Republic of China, the United States, Canada, and Australia. We also discuss in detail the “maximum level” of the following main contaminants of spirit drinks: methanol, higher alcohols, ethyl carbamate, hydrocyanic acid, heavy metals, mycotoxins, phthalates, and aldehydes. Furthermore, the control measures used for potential hazards are introduced. Harmonization of the current requirements based on comprehensive scope analysis and the risk assessment approach will enhance both the trade and quality of distilled spirits. This review article provides valuable information that will enable producers, traders, governments, and researchers to increase their knowledge of spirit drink safety requirements, control measures, and research trends.

scholarly journals A Satellite Data-Driven Framework to Rapidly Quantify Air Basin-Scale NO<sub>x</sub> Emission and Its Application to the Po Valley during the COVID-19 Pandemic

2021 ◽  
Author(s):  
Kang Sun ◽  
Lingbo Li ◽  
Shruti Jagini ◽  
Dan Li
Keyword(s):  
Emission Rate ◽  
Control Measures ◽  
Nox Emission ◽  
Data Driven ◽  
Anthropogenic Emissions ◽  
Emission Rates ◽  
Po Valley ◽  
Basin Scale ◽  
Emission Changes ◽  
Business As Usual

Abstract. The evolving nature of the COVID-19 pandemic necessitates timely estimates of the resultant perturbations to anthropogenic emissions. Here we present a novel framework based on the relationships between observed column abundance and wind speed to rapidly estimate air basin-scale NOx emission rate and apply it at the Po Valley in Italy using OMI and TROPOMI NO2 tropospheric column observations. The NOx chemical lifetime is retrieved together with the emission rate and found to be 15–20 h in winter and 5–6 h in summer. A statistical model is trained using the estimated emission rates before the pandemic to predict the trajectory without COVID-19. Compared with this business-as-usual trajectory, the real 2020 emission rates show two distinctive drops in March (−41 %) and November (−35 %) that correspond to tightened COVID-19 control measures. The temporal variation of pandemic-induced NOx emission changes qualitatively agree with Google and Apple mobility indicators. The overall net NOx emission reduction in 2020 due to the COVID-19 pandemic is estimated to be 21 %.

scholarly journals Numerical Investigation of the Savonius Vertical Axis Wind Turbine and Evaluation of the Effect of the Overlap Parameter in Both Horizontal and Vertical Directions on Its Performance

Symmetry ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 821 ◽  
Author(s):  
Mohammad Ebrahimpour ◽  
Rouzbeh Shafaghat ◽  
Rezvan Alamian ◽  
Mostafa Safdari Shadloo
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Weather Conditions ◽  
Vertical Axis ◽  
Power Coefficient ◽  
External Diameter ◽  
Vertical Axis Wind Turbine ◽  
Complex Process ◽  
Overlap Ratio ◽  
Volume Method

Exploiting wind energy, which is a complex process in urban areas, requires turbines suitable for unfavorable weather conditions, in order to trap the wind from different directions; Savonius turbines are suitable for these conditions. In this paper, the effect of overlap ratios and the position of blades on a vertical axis wind turbine is comprehensively investigated and analyzed. For this purpose, two positive and negative overlap situations are first defined along the X-axis and examined at the different tip speed ratios of the blade, while maintaining the size of the external diameter of the rotor, to find the optimum point; then, the same procedure is done along the Y-axis. The finite volume method is used to solve the computational fluid dynamics. Two-dimensional numerical simulations are performed using URANS equations and the sliding mesh method. The turbulence model employed is a realizable K-ε model. According to the values of the dynamic torque and power coefficient, while investigating horizontal and vertical overlaps along the X- and Y-axis, the blades with overlap ratios of HOLR = +0.15 and VOLR = +0.1 show better performances when compared to other corresponding overlaps. Accordingly, the average Cm and Cp improvements are 16% and 7.5%, respectively, compared to the base with a zero overlap ratio.

Effect of the Soil Inclination on Natural Convection in Half-Elliptical Greenhouses

2020 ◽  
Vol 50 ◽  
pp. 70-78
Author(s):  
Djedid Taloub ◽  
Abdelkarim Bouras ◽  
Zied Driss
Keyword(s):  
Natural Convection ◽  
Cfd Simulation ◽  
Numerical Study ◽  
Boussinesq Approximation ◽  
Elliptic Cavity ◽  
Horizontal Cavity ◽  
Inclined Cavity ◽  
Volume Method ◽  
Heat Transfers ◽  
Work Done

A numerical study of the natural convection of laminar heat transfers in the stationary state in a half-elliptic inclined cavity, which represents a continuation of the work done, we studied the influence of the tilt of the cavity by varying the angle — entered 0 degrees, which corresponds to the horizontal cavity, up to 15 degrees. For each value of δ we varied the Rayleigh number from 2.13 103 to 106. The system of equations governing the problem solved numerically by the fluent calculation code based on the finite volume method. Based on the Boussinesq approximation. Both bottom and upper walls maintained at a constant temperature. The interest of this study is to see the influence of the tilt of the half-elliptic cavity on the structure of the flow and the distribution of temperature. These results can exploited in semi-elliptic agricultural greenhouses that rest on sloping soils. We chose a Prandtl number 0.71 that corresponds to the air. Keywords: Heat transfer; half-elliptical; Natural convection; Laminar flow; Multicellular; CFD simulation

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