scholarly journals Simulation and measurement of air quality in the traffic congestion area

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Shin Yu ◽  
Chang Tang Chang ◽  
Chih Ming Ma
Keyword(s):  
Air Quality ◽  
Traffic Congestion ◽  
Traffic Management ◽  
Reference Model ◽  
Dispersion Model ◽  
Fluid Model ◽  
Three Dimensional ◽  
Vehicle Speed ◽  
Management Plans ◽  
Dimensional Distribution

AbstractThe traffic congestion in the Hsuehshan tunnel and at the Toucheng interchange has led to traffic-related air pollution with increasing concern. To ensure the authenticity of our simulation, the concentration of the last 150 m in Hsuehshan tunnel was simulated using the computational fluid dynamics fluid model. The air quality at the Toucheng interchange along a 2 km length highway was simulated using the California Line Source Dispersion Model. The differences in air quality between rush hours and normal traffic conditions were also investigated. An unmanned aerial vehicle (UAV) with installed PM2.5 sensors was developed to obtain the three-dimensional distribution of pollutants. On different roads, during the weekend, the concentrations of pollutants such as SOx, CO, NO, and PM2.5 were observed to be in the range of 0.003–0.008, 7.5–15, 1.5–2.5 ppm, and 40–80 μg m− 3, respectively. On weekdays, the vehicle speed and the natural wind were 60 km h− 1 and 2.0 m s− 1, respectively. On weekdays, the SOx, CO, NO, and PM2.5 concentrations were found to be in the range of 0.002–0.003, 3–9, 0.7–1.8 ppm, and 35–50 μg m− 3, respectively. The UAV was used to verify that the PM2.5 concentrations of vertical changes at heights of 9.0, 7.0, 5.0, and 3.0 m were 45–48, 30–35, 25–30, and 50–52 μg m− 3, respectively. In addition, the predicted PM2.5 concentrations were 40–45, 25–30, 45–48, and 45–50 μg m− 3 on weekdays. These results provide a reference model for environmental impact assessments of long tunnels and traffic jam-prone areas. These models and data are useful for transportation planners in the context of creating traffic management plans.

A review of turbulence in the very stable nocturnal boundary layer and its implications for air quality

2005 ◽  
Vol 29 (2) ◽  
pp. 171-188 ◽  
Author(s):  
J. A. Salmond ◽  
I. G. McKendry
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Spatial Scales ◽  
Vertical Mixing ◽  
Three Dimensional ◽  
Nocturnal Boundary Layer ◽  
Dimensional Distribution ◽  
Temporal And Spatial ◽  
Fraser Valley ◽  
Spatial And Temporal Characteristics

Turbulence in the very stable nocturnal boundary layer is weak and typically characterized by intermittent bursts of activity. It often exists in isolated layers or pockets generated primarily from localized shear instabilities. As a result, turbulence is rarely in equilibrium with the conditions of the underlying surface. Given the layered structure of the nocturnal boundary layer, the spatial and temporal characteristics of turbulent activity (and resulting vertical mixing) can have a significant affect on local air quality at hourly to diurnal scales. However, while there is a wealth of information concerning turbulent processes operating during daytime conditions, until recently comparatively few studies have focused on the nocturnal case. Nevertheless the three-dimensional distribution of pollutants in the nocturnal boundary layer may have a significant impact on local pollutant budgets at a variety of temporal and spatial scales. This paper reviews recent progress in our understanding of the structure of, and processes operating in, the very stable nocturnal boundary layer. Then, drawing upon case studies from the Lower Fraser Valley, of British Columbia, Canada, it considers the implications of these developments for pollutant transport and surface air quality.

Reducing uncertainty in emission estimates using perturbed emissions ensembles and novel observations: A focus on Beijing

2020 ◽  
Author(s):  
Le Yuan ◽  
David Carruthers ◽  
Christina Hood ◽  
Roderic L. Jones ◽  
Olalekan A.M. Popoola ◽  
...  
Keyword(s):  
Air Quality ◽  
High Resolution ◽  
Dispersion Model ◽  
Low Cost ◽  
Time Lag ◽  
Three Dimensional ◽  
Expert Elicitation ◽  
Control Measures ◽  
Emissions Inventory ◽  
Emission Changes

<p>The time lag between the occurrence of emissions and the compilation of an inventory is inevitable. When an emissions inventory is used to simulate air quality, uncertainties in the emissions are propagated into uncertainties in the modelled pollutant concentrations. Such uncertainties can be particularly high in regions undergoing rapid emission changes. Beijing, for instance, has implemented a series of pollution control measures over the past several years and various studies have confirmed significant decreases in the emissions of pollutants such as CO and NO<sub>X</sub>. Hence, it is crucial to quantify and constrain the uncertainties in existing emission estimates for this region.</p><p>We sample the uncertainties in an emissions inventory for Beijing using a high-resolution advanced Gaussian dispersion model with perturbed emissions ensembles (PEEs), and constrain these uncertainties using a comprehensive set of in situ observations, including vertically resolved measurements made from a tower in central Beijing using low-cost sensors. We first construct a PEE by varying key emission parameters including source sectors, vertical and diurnal profiles within their uncertainty ranges estimated through expert elicitation. By removing the baseline contribution to the concentrations, we are able to evaluate the performance of the PEE in simulating the local signal. Based on knowledge gained from the initial PEE, we design a second PEE with optimised uncertainty ranges with which we constrain the uncertainties in the base emission estimates.</p><p>Our study shows the applicability of perturbed emissions ensembles and high-resolution, three-dimensional observations in systematically sampling and constraining emission uncertainties. This method has wide implications for air quality modelling, particularly in regions with rapid emission changes or for studies in which emissions inventories are out-dated.</p>

scholarly journals Toward Development of a Framework for Prediction System of Local-Scale Atmospheric Dispersion Based on a Coupling of LES-Database and On-Site Meteorological Observation

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 899
Author(s):  
Hiromasa Nakayama ◽  
Toshiya Yoshida ◽  
Hiroaki Terada ◽  
Masanao Kadowaki
Keyword(s):  
Dispersion Model ◽  
Atmospheric Dispersion ◽  
Three Dimensional ◽  
Local Scale ◽  
Prediction System ◽  
Meteorological Observation ◽  
Accurate Analysis ◽  
Energy Agency ◽  
Class Interval ◽  
Dimensional Distribution

An accurate analysis of local-scale atmospheric dispersion of radioactive materials is important for safety and consequence assessments and emergency responses to accidental release from nuclear facilities. It is necessary to predict the three-dimensional distribution of the plume in consideration of turbulent effects induced by individual buildings and meteorological conditions. In this study, first, we conducted with meteorological observations by a Doppler LiDAR and simple plume release experiments by a mist-spraying system at the site of Japan Atomic Energy Agency. Then, we developed a framework for prediction system of local-scale atmospheric dispersion based on a coupling of large-eddy simulation (LES) database and on-site meteorological observation. The LES-database was also created by pre-calculating high-resolution turbulent flows in the target site at mean wind directions of class interval 10°. We provided the meteorological observed data with the LES-database in consideration of building conditions and calculated the three-dimensional distribution of the plume with a Lagrangian dispersion model. Compared to the instantaneous shots of the plume taken by a digital camera, it was shown that the mist plume transport direction was accurately simulated. It was concluded that our proposed framework for prediction system based on a coupling of LES-database and on-site meteorological observation is effective.

Dynamic Camera Calibration in Support of Intelligent Transportation Systems

2002 ◽  
Vol 1804 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Suree Pumrin ◽  
Daniel J. Dailey
Keyword(s):  
Camera Calibration ◽  
Intelligent Transportation Systems ◽  
Traffic Management ◽  
Three Dimensional ◽  
Simulated Data ◽  
Quantitative Information ◽  
Transportation Systems ◽  
Vehicle Speed ◽  
Camera Model ◽  
The Earth

An algorithm with which to estimate mean vehicle speed from roadside cameras owned by a traffic management agency is presented. These roadside cameras are not calibrated nor are calibration marks available in the scene. However, estimating camera calibration coefficients is the most important step in extracting quantitative information about the three-dimensional world from the two-dimensional image. Within this frame-work an algorithm is presented that performs a simplified dynamic calibration and estimates mean vehicle speed. Many algorithms depend on point correspondences between the earth coordinates and the image coordinates as well as targets of known shape to obtain accurate results. However, in the work presented, the goal is to estimate the mean of a distribution of vehicle speeds, and it is demonstrated that a simplified form of calibration is adequate for making an accurate mean speed estimate. Dynamic camera calibration is performed with training sets of 10-s video sequences. The proposed method detects moving vehicles in a set of consecutive frames. This information, together with mean vehicle dimension estimates, is used to create scaling factors that are used to infer a relationship between motion in the image and motion in the earth coordinate system. The proposed algorithm has a camera model with a reduced number of camera calibration parameters. The algorithm is validated with simulated data and actual traffic scenes.

Three-dimensional distribution of ribulose-1, 5-bisphosphate carboxylase/oxygemase during the early development of proplastids in dark-grown Euglena cells transferred to an inorganic medium

1990 ◽  
Vol 48 (3) ◽  
pp. 906-907
Author(s):  
Tomoko Ehara ◽  
Shuji Sumida ◽  
Tetsuaki Osafune ◽  
Eiji Hase
Keyword(s):  
Cell Suspension ◽  
Euglena Gracilis ◽  
Carbon Materials ◽  
Three Dimensional ◽  
Peripheral Region ◽  
Plastid Development ◽  
Bisphosphate Carboxylase ◽  
Inorganic Medium ◽  
Ribulose 1 ◽  
Dimensional Distribution

As shown previously, Euglena cells grown in Hutner’s medium in the dark without agitation accumulate wax as well as paramylum, and contain proplastids showing no internal structure except for a single prothylakoid existing close to the envelope. When the cells are transferred to an inorganic medium containing ammonium salt and the cell suspension is aerated in the dark, the wax was oxidatively metabolized, providing carbon materials and energy 23 for some dark processes of plastid development. Under these conditions, pyrenoid-like structures (called “pro-pyrenoids”) are formed at the sites adjacent to the prolamel larbodies (PLB) localized in the peripheral region of the proplastid. The single prothylakoid becomes paired with a newly formed prothylakoid, and a part of the paired prothylakoids is extended, with foldings, in to the “propyrenoid”. In this study, we observed a concentration of RuBisCO in the “propyrenoid” of Euglena gracilis strain Z using immunoelectron microscopy.

scholarly journals Dip angles of active faults from the surface to the seismogenic zone inferred from a 2D numerical analysis of visco-elasto-plastic models: a case study for the Osaka Plain

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Hayami Nishiwaki ◽  
Takamoto Okudaira ◽  
Kazuhiko Ishii ◽  
Muneki Mitamura
Keyword(s):  
Urban Areas ◽  
Active Faults ◽  
Three Dimensional ◽  
Seismogenic Zone ◽  
Earthquake Ground Motion ◽  
Convex Curve ◽  
Seismic Reflection Profile ◽  
Geological Structures ◽  
Dimensional Distribution ◽  
Dip Angle

AbstractThe geometries (i.e., dip angles) of active faults from the surface to the seismogenic zone are the most important factors used to evaluate earthquake ground motion, which is crucial for seismic hazard assessments in urban areas. In Osaka, a metropolitan city in Japan, there are several active faults (e.g., the Uemachi and Ikoma faults), which are inferred from the topography, the attitude of active faults in surface trenches, the seismic reflection profile at shallow depths (less than 2 km), and the three-dimensional distribution of the Quaternary sedimentary layers. The Uemachi and Ikoma faults are N–S-striking fault systems with total lengths of 42 km and 38 km, respectively, with the former being located ~ 12 km west of the latter; however, the geometries of each of the active faults within the seismogenic zone are not clear. In this study, to examine the geometries of the Uemachi and Ikoma faults from the surface to the seismogenic zone, we analyze the development of the geological structures of sedimentary layers based on numerical simulations of a two-dimensional visco-elasto-plastic body under a horizontal compressive stress field, including preexisting high-strained weak zones (i.e., faults) and surface sedimentation processes, and evaluate the relationship between the observed geological structures of the Quaternary sediments (i.e., the Osaka Group) in the Osaka Plain and the model results. As a result, we propose geometries of the Uemachi and Ikoma faults from the surface to the seismogenic zone. When the friction coefficient of the faults is ~ 0.5, the dip angles of the Uemachi and Ikoma faults near the surface are ~ 30°–40° and the Uemachi fault has a downward convex curve at the bottom of the seismogenic zone, but does not converge to the Ikoma fault. Based on the analysis in this study, the dip angle of the Uemachi fault zone is estimated to be approximately 30°–40°, which is lower than that estimated in the previous studies. If the active fault has a low angle, the width of the fault plane is long, and thus the estimated seismic moment will be large.

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