Identification of ventilation corridors using backward trajectory simulations in Beijing

2021 ◽  
pp. 102889
Author(s):  
Yuepeng Xu ◽  
Weiwen Wang ◽  
Bingyin Chen ◽  
Ming Chang ◽  
Xuemei Wang
Keyword(s):  
Backward Trajectory ◽  
Trajectory Simulations

Doping effects on the geometric and electronic structure of tin clusters

2019 ◽  
Vol 21 (44) ◽  
pp. 24478-24488 ◽  
Author(s):  
Martin Gleditzsch ◽  
Marc Jäger ◽  
Lukáš F. Pašteka ◽  
Armin Shayeghi ◽  
Rolf Schäfer
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Beam Deflection ◽  
Functional Theory ◽  
Doping Effects ◽  
Depth Analysis ◽  
Trajectory Simulations

In depth analysis of doping effects on the geometric and electronic structure of tin clusters via electric beam deflection, numerical trajectory simulations and density functional theory.

scholarly journals Chemical characterization and synergetic source apportionment of PM<sub>2.5</sub> at multiple sites in the Beijing–Tianjin–Hebei region, China

2017 ◽  
Author(s):  
Xiaojuan Huang ◽  
Zirui Liu ◽  
Jingyun Liu ◽  
Bo Hu ◽  
Tianxue Wen ◽  
...  
Keyword(s):  
Motor Vehicle ◽  
Dominant Role ◽  
Chemical Compositions ◽  
Backward Trajectory ◽  
Entire Study ◽  
Background Site ◽  
Haze Pollution ◽  
Secondary Aerosols ◽  
Haze Formation ◽  
Urban Sites

Abstract. High frequencies of haze in China, especially in the Beijing–Tianjin–Hebei region, have received widespread attention in recent years. In this study, samples of filtered atmospheric fine particulate matter (PM2.5) were collected synchronously at three urban sites (Beijing, Tianjin, and Shijiazhuang) and at a regional background site (Xinglong) for one month during each season from June 2014 to April 2015. Chemical composition determination/analysis, chemical mass closure, positive matrix factorization (PMF) and backward trajectory clustering were employed to investigate the chemical speciation, haze formation mechanism, emission sources, and influences of regional transport in North China. Our results reported that the aerosol chemical compositions were very similar at the urban sites and the background site and mainly comprised organic matter (16.0 %–25.0 %), sulfate (14.4 %–20.5 %), nitrate (15.1 %–19.5 %), ammonium (11.6 %–13.1 %) and mineral dust (14.7 %–20.8 %). Sources apportionment of PM2.5 by PMF model revealed that secondary aerosols (background) and secondary inorganic aerosols (urban) were the dominant sources, which accounted for 29.2 %–45.1 % of PM2.5 throughout the entire study and played a vital role in the formation and development of haze pollution. Emissions of motor vehicle exhaust exerted a significant impact on haze formation at urban sites, particularly at Beijing; and coal combustion also played an dominant role in winter, especially at Shijiazhuang. Backward trajectory analysis revealed that haze pollution has remarkable regional characteristics and usually occurs when air masses originated from polluted industrial regions of the south prevailed, which accompanied by high PM2.5 loadings with high contributions of secondary aerosols. This study suggests that the control strategies to mitigate the haze formation in BTH region should be focused on the emission reduction of gaseous precursors from fossil fuel combustion, particularly from motor vehicles by improving the quality of oil products.

Introduction

2019 ◽  
pp. 1-28
Author(s):  
Paul Giles
Keyword(s):  
Backward Trajectory ◽  
High Modernism ◽  
Definition Of

Drawing on theories of temporality and anthropology, and focusing in particular on Paul Ricoeur’s notion of ‘retrodiction,’ this Introduction lays out a framework for understanding antipodean transnationalism. It reconsiders the canonical strains of early or ‘high’ modernism through late modernism’s backward trajectory and thus articulates ways in which modernism was always a more belated phenomenon than has generally been recognized. It argues that modernism systematically incorporated retrograde modes of burlesque and buffoonery whose formal perspectives can be understood intellectually as commensurate with their spherical geographic provenance. By reorganizing the time of modernism according to antipodean coordinates, we come to recognize how antipodean modernism’s twisted, recursive properties are integral to the definition of modernism within a global compass.

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