Shock Waves Generated in the Presence of Barriers in Gas Explosions

This paper examines conditions that generates shock waves in a gas explosion through experiment. The result shows that the presence of barrier and thin film, which is similar to air door and stopping in underground coal mines, is very important for the generation of shock waves in a gas explosion. When there are physical barriers, the speed of transmission would be very fast and shock waves will result in the process; when the film is destroyed in gas explosion, shock waves will also appear which would result in an increase in explosion power. Therefore, in order to weaken the gas explosion and prevent the generation of shock waves, the number of barriers should be reduced, and the air door and stopping in tunnels should be strengthened in coal mines. The result of research is very important to prevent gas explosion and decrease the power of such explosions

Detectable anthropogenic changes in daily-scale circulations driving summer rainfall shifts over eastern China

Wetting in the south while drying in the north during the last few decades constitutes the well-known ‘southern flood–northern drought’ (SFND) precipitation pattern over eastern China. The fingerprint of anthropogenic influence on this dipole pattern of regional precipitation trends has not been confirmed, especially for forced changes in relevant dynamics at the synoptic scale. Using a process-based approach involving model experiments both with and without anthropogenic inputs, it is demonstrated that the occurrences of daily circulation patterns (CPs) governing precipitation over eastern China during 1961–2013 have been altered by human influence. Due to anthropogenic forcing, CPs favoring SFND have become more likely to occur at the expense of CPs unfavorable to SFND. Regression analysis shows that changes recorded in the occurrence of CPs from the factual simulations could explain a large part of the precipitation trends over eastern China. CP frequencies driven by purely natural forcing do not reproduce this dipole pattern nor the inferred magnitude of precipitation trends over eastern China. These results suggest that human influence has played a critical role in shaping the contrasting north–south precipitation trends

Attribution of extreme precipitation in the lower reaches of the Yangtze River during May 2016

May 2016 was the third wettest May on record since 1961 over central eastern China based on station observations, with total monthly rainfall 40% more than the climatological mean for 1961–2013. Accompanying disasters such as waterlogging, landslides and debris flow struck part of the lower reaches of the Yangtze River. Causal influence of anthropogenic forcings on this event is investigated using the newly updated Met Office Hadley Centre system for attribution of extreme weather and climate events. Results indicate that there is a significant increase in May 2016 rainfall in model simulations relative to the climatological period, but this increase is largely attributable to natural variability. El Ni ̃no years have been found to be correlatedwith extreme rainfall in the Yangtze River region in previous studies—the strong El Ni ̃no of 2015–2016 may account for the extreme precipitation event in 2016. However, on smaller spatial scales we find that anthropogenic forcing has likely played a role in increasing the risk of extreme rainfall to the north of the Yangtze and decreasing it to the south

A simple method for solving unidirectional methane gas flow in coal seam based on similarity solution

The equation used to model the unidirectional flow of methane gas in coal seams is usually formulated as a nonlinear partial differential equation, which needs to be solved numerically with a computer program. Nevertheless, for people without access to the computer program, the conventional numerical method may be inconvenient. Thus, the objective here is to seek some method simpler than the conventional one for solving the flow problem. A commonly used model of the unidirectional methane gas flow is considered, where the methane adsorption is described by the Langmuir isotherm and the free gas is treated as real gas. By introducing the similarity solution, a simple method for solving the flow model is proposed, which can be done on a hand calculator. It is shown by two examples that the gas pressure profile obtained by the proposed method agrees well with the direct numerical solution of the flow model. Keywords: Coalbed methane, Migration, Unidirectional flow, Similarity solution, Simplified solving, Numerical metho

High-efficiency and high-luminance three-color white organic light-emitting diodes with low efficiency roll-off

For the first time, double blue emitting layers have been functioned as the main exciton generation zone to achieve high-performance three-color phosphorescent white organic light-emitting diodes (WOLEDs). The WOLED exhibits the maximum forward-viewing external quantum efficiency (EQE) and power efficiency (PE) of 21.2% and 50.0 lm/W, respectively. Even at 1000 c d / m2, the forward-viewing EQE and PE are as high as 18.0 % and 32.5 lm / W, respectively, indicating low efficiency roll-off. Besides, the WOLED shows a maximum luminance of 81156 c d / m2. Moreover, by manipulating the excitons distribution, a WOLED can achieve a high color rendering index of 80. The findings may provide a new opportunity to achieve high-efficiency, high-luminance and low efficiency roll-off WOLEDs.Published versio