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This study examines the future spatial distributions and long-term trends of the sea ice concentration (SIC) and the sea ice thickness (SIT) in the Arctic, along with the potential impacts of the Temperature at Surface (TAS), using the outputs of six models under four forcing scenarios of the Coupled Model Intercomparison Project Phase 6 (CMIP6). The results show that, under the four forcing scenarios, the SIC exceeds 50% and the SIT is approximately 1.5 m in most parts of the Arctic in 2030, 2040, and 2050. However, in the regions of East Greenland, the Barents Sea, the Kara Sea, and the Chukchi Sea, the SIC and SIT are comparatively lower and thinner. Both the SIC and the SIT exhibit declining trends during 2015—2050. Specifically, under the high-forcing scenario, the SIC in some regions decreases by over 1% per year. In 2050, under the high-forcing scenario, the SIC in most of the Arctic exceeds 90% during winter and spring months. The SIC reveals a decreasing trend in every month. The SIT exceeds 1 m from winter to summer in most regions, while it is less than or equal to 0.5 m in the fall. From December to May, the SIT exhibits a decreasing trend across the Arctic, with some localized increases observed in other months. Regarding the long-term trend up to 2100, the SIC and SIT in the Central Arctic, the East Greenland Sea, and the Chukchi Sea decrease over time, with the fastest reduction in the Central Arctic, meanwhile the TAS continues to rise in these three regions. Additionally, the spatial distribution and long-term trend between the TAS and the SIC are opposite, implying the possible impact of the TAS on the SIC. These findings provide valuable insights into the future sea ice in the Arctic under different forcing scenarios.

The minimum measured wind speed of the existing anemometer can not meet the requirements of precise wind measurement under the condition of low wind speed in mines. In order to solve this problem, based on the principle of ultrasonic time difference method wind speed measurement, a high-precision mine ultrasonic anemometer with low starting wind speed is designed. Two ultrasonic transmitting probes and two ultrasonic receiving probes are arranged alternately to form two ultrasonic propagation paths. The downwind and upwind propagation times of ultrasonic waves in a specific wind speed field are measured respectively, and the average wind speed between the transmitting probes and the receiving probes is solved by using the superposition effect of the propagation speed of ultrasonic waves in the air and the wind speed (the effect of temperature on the wind speed measurement can be ignored). In order to analyze the effect of ultrasonic probe direction on the accuracy and reliability of measurement, four different probe arrangement modes are used to carry out the experiment. The results show that the more serious the ultrasonic probe direction dislocation is, the larger the standard deviation and fluctuation range of wind speed. Therefore, the infrared orientation device is used to calibrate the installation position of the anemometer to reduce the measurement error caused by the ultrasonic probe direction dislocation. The moving average method is used to smooth the original wind speed waveform curve to eliminate random noise and improve the stability of output wind speed. By analyzing the factors affecting measurement precision, it is determined that the ultrasonic emission frequency is 40 kHz and the standby time is 100 ms. The theoretical calculation and experimental results show that the resolution of the anemometer is 0.01 m/s, the measurement error is ±0.1 m/s, and the starting wind speed is lower than 0.1 m/s, which can meet the precise wind measurement requirements of the mine roadway with low wind speed.

Gold-assisted exfoliation can fabricate centimeter- or larger-sized monolayers of van der Waals (vdW) semiconductors, which is desirable for their applications in electronic and optoelectronic devices. However, there is still a lack of control over the exfoliation processes and a limited understanding of the atomic-scale mechanisms. Here, we tune the MoS2-Au interface using controlled external pressure and reveal two atomic-scale prerequisites for successfully producing large-area monolayers of MoS2. The first is the formation of strong MoS2-Au interactions to anchor the top MoS2 monolayer to the Au surface. The second is the integrity of the covalent network of the monolayer, as the majority of the monolayer is non-anchored and relies on the covalent network to be exfoliated from the bulk MoS2. Applying pressure or using smoother Au films increases the MoS2-Au interaction, but may cause the covalent network of the MoS2 monolayer to break due to excessive lateral strain, resulting in nearly zero exfoliation yield. Scanning tunneling microscopy measurements of the MoS2 monolayer-covered Au show that even the smallest atomic-scale imperfections can disrupt the MoS2-Au interaction. These findings can be used to develop new strategies for fabricating vdW monolayers through metal-assisted exfoliation, such as in cases involving patterned or non-uniform surfaces. [ABSTRACT FROM AUTHOR]

The existing mine wind speed sensor arrangement methods have problems as follows. The determined sensor branch cannot measure the wind speed accurately because the wind speed is smaller than the sensor start wind speed. Most of the methods need to be listed multiple matrices and the calculation is complicated. Moreover, the sensor positions selected by some methods are unreasonable. In order to achieve mine full coverage air volume monitoring without blind area, and to monitor the air volume variation in all roadways with the minimum number of wind speed sensors, the coverage of sensor branches is analyzed by using the directed path matrix, and the optimal arrangement of wind speed sensors based on the directed path matrix method is proposed. This method determines the unique directed path matrix based on the wind flow direction of the ventilation network diagram, determines the coverage of the branches, and selects the branch with the largest coverage to determine the position of the wind speed sensor. The results show that the optimal arrangement of wind speed sensors based on directed path matrix method can achieve mine full coverage air volume monitoring without blind area, and the number of sensors is less than or equal to the number of independent directed paths. Calculation analysis shows that when sensors are arranged according to this method, there is a measurement error of 6% in one sensor branch, the lowest impact on the ventilation network is 0.52, and the lowest impact on other branches is 0. Moreover, the calculation error decreases as the number of sensors increases. If the impact of sensor branch error on the ventilation network is controlled to be less than 1, more than 12 wind speed sensors should be arranged.

Variations in Arctic sea ice are apparent not only in its extent and thickness but also in its internal properties under global warming. The microstructure of summer Arctic sea ice changes due to varying external forces, ice age, and extended melting seasons, which affect its optical properties. Sea ice cores sampled in the Pacific sector of the Arctic obtained by the Chinese National Arctic Research Expedition (CHINARE) during the summers of 2008 to 2016 were used to estimate the variations in the microstructures and inherent optical properties (IOPs) of ice and determine the radiation budget of sea ice based on a radiative transfer model. The variations in the volume fraction of gas bubbles (Va) of the ice top layer were not significant, and the Va of the ice interior layer was significant. Compared with 2008, the mean Va of interior ice in 2016 decreased by 9.1 %. Meanwhile, the volume fraction of brine pockets increased clearly during 2008–2016. The changing microstructure resulted in the scattering coefficient of the interior ice decreasing by 38.4 % from 2008 to 2016, while no clear variations can be seen in the scattering coefficient of the ice top layer. These estimated ice IOPs fell within the range of other observations. Furthermore, we found that variations in interior ice were significantly related to the interannual changes in ice ages. At the Arctic basin scale, the changing IOPs of interior ice greatly changed the amount of solar radiation transmitted to the upper ocean even when a constant ice thickness is assumed, especially for thin ice in marginal zones, implying the presence of different sea ice bottom melt processes. These findings revealed the important role of the changing microstructure and IOPs of ice in affecting the radiation transfer of Arctic sea ice. [ABSTRACT FROM AUTHOR]

Flash evaporation processes are widely adopted in the desalination, food processing, waste heat recovery and other industries for heat extraction or product separation. In this paper, a pressure-driven phase transition model is developed by improving the Lee model and combined with the VOF (Volume of Fluid) method to numerically simulate the flash evaporation process. In this modified Lee phase transition model, the driving force for the rates of the local phase transition is calculated using the local temperature and static pressure magnitude. Numerical simulations are carried out in a water-circulating flash chamber and compared with the experimental results to obtain the values of the time relaxation parameters. And the non-equilibrium fraction of the outlet water can be effectively obtained under different conditions of flow rate, inlet temperature and initial liquid level height. The time relaxation factor takes values from 0.195 to 0.43 (Pout,v = 19.9 kPa) and from 0.31 to 0.92 (Pout,v = 31.2 kPa) with increasing superheat. In addition, the model can effectively represent the evolution of the unstable flow flash evaporation from the initial rapid boiling state to dynamic equilibrium. [ABSTRACT FROM AUTHOR]

In order to achieve rapid determination of coal seam permeability, the calculation method of coal seam permeability coefficient was studied. Based on the Darcy's law in the flow of gas in the coal seam, the relationship equation between the gas pressure of the borehole and the gas permeability coefficient of the coal seam is established under the radial unsteady flow state. The gas permeability coefficient of the coal seam is obtained by coordinate transformation and integral transformation. Solve the expression. The analysis and verification of the field measured data show that the expression of the analytical solution of the coal seam permeability coefficient is consistent with the variation of the borehole pressure-time curve, which can provide a theoretical basis for the rapid determination of coal seam permeability.

Landfast ice (LFI) plays a crucial role for both the climate and the ecosystem of the Antarctic coastal regions. We investigate the snow and LFI mass balance in Prydz Bay using observations from 11 sea ice mass balance buoys (IMBs). The buoys were deployed offshore from the Chinese Zhongshan Station (ZS) and Australian Davis Station (DS), with the measurements covering the ice seasons of 2009–2010, 2013–2016, and 2018. The observed annual maximum ice thickness and snow depth were 1.59 ± 0.17 and 0.11–0.76 m off ZS and 1.64 ± 0.08 and 0.11–0.38 m off DS, respectively. Early in the ice growth season (May–September), the LFI basal growth rate near DS (0.6 ± 0.2 cmd-1) was larger than that around ZS (0.5 ± 0.2 cmd-1). This is attributed to cooler air temperature (AT) and lower oceanic heat flux at that time in the DS region. Air temperature anomalies were more important in regulating the LFI growth rate at that time because of thinner sea ice having a weaker thermal inertia relative to thick ice in later seasons. Interannual and local spatial variabilities for the seasonality of LFI mass balance identified at ZS are larger than at DS due to local differences in topography and katabatic wind regime. Snow ice contributed up to 27 % of the LFI total ice thickness at the offshore site close to ground icebergs off ZS because of the substantial snow accumulation. Offshore from ZS, the supercooled water was observed at the sites close to the Dålk Glacier from July to October, which reduced the oceanic heat flux and promoted the LFI growth. During late austral spring and summer, the increased oceanic heat flux led to a reduction of LFI growth at all investigated sites. The variability of LFI properties across the study domain prevailed at interannual timescales, over any trend during the recent decades. Based on the results derived from this study, we argue that an increased understanding of snow (on LFI) processes, local atmospheric and oceanic conditions, as well as coastal morphology and bathymetry, are required to improve the Antarctic LFI modeling. [ABSTRACT FROM AUTHOR]