The unprecedented COVID-19 pandemic has caused a traffic tie-up across the world. In addition to home quarantine orders and travel bans, the social distance guideline of about six feet was enacted to reduce the risk of contagion. However, with recent life gradually returning to normal, the crisis is not over. In this research, a moving train test and a Gaussian puff model were employed to investigate the impact of wind raised by a train running on the transmission and dispersion of SARS-CoV-2 from infected individuals. Our findings suggest that the 2 m social distance guideline may not be enough; under train-induced wind action, human respiratory disease-carrier droplets may travel to unexpected places. However, there are deficiencies in passenger safety guidelines and it is necessary to improve the quantitative research in the relationship between train-induced wind and virus transmission. All these findings could provide a fresh insight to contain the spread of COVID-19 and provide a basis for preventing and controlling the pandemic virus, and probe into strategies for control of the disease in the future.
Previous studies have shown that vertical greening has a significant cooling and energy-saving effect, most of which are applied to opaque walls. However, windows are the critical factor contributing to the indoor thermal environment. This study developed a modular vertical greening shading device (MVGSD), and introduces its detailed structure: water supply mode, plant selection, and substrate preparation. To investigate the thermal performance of MVGSD, a structural model test was carried out. The results show that MVGSD has a noticeable effect on indoor temperature. Specifically, the greatest indoor temperature can be reduced by 4 °C and effectively low the concentration of CO2 (The CO2 absorption rate is 53.1%). In addition, the characteristics of the louver shading and MVGSD were compared, and it was found that the indoor temperature by using MVGSD is 2.6 °C lower than the louver. It is also worth mentioning that indoor humidity is improved by MVGSD, which has a beneficial effect on the thermal comfort of human beings.
A running train induces a slipstream around it, which is closely related to its aerodynamic features and crucial for the safety of people and structures near the track. However, the effect of crosswinds is almost inevitable when the train runs on a bridge. In this work, an experimental study using moving model testing technology was conducted to investigate the effects of wind speeds, train speeds, and yaw angles on the aerodynamic performance of a Fuxing Hao high-speed train running on a bridge under the influence of crosswind. The results show that, for the crosswind cases, the slipstream velocities on the leeward side of the train are generally higher than those in the no-crosswind cases. Moreover, the results were compared for the cases with the same effective yaw angle of 21.8° but different train speeds (6 m/s, 8 m/s) and wind speeds (15 m/s, 20 m/s), which suggests the method of the resultant wind’s yaw angle is no longer valid when the train runs on a bridge due to the aerodynamic interactions.
The present paper reports a numerical investigation on the aerodynamic performance of a CRH2 high-speed train and bridge system under the strong cross wind. Effects of the train running speed on the train-bridge system were addressed comprehensively. For a running train, the aerodynamic drag and overturning moment on the head coach are larger than those on the other coaches, especially the trailing one. Reynolds number has significant effects on the train-bridge system with the yaw angle of oncoming wind of 42° and 90°. With the increase of the train running speed or the yaw angle of oncoming wind, the drag and lift of both the train and the bridge increases gradually, especially those on the head coach of the train.
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