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This paper mainly studies the interdependence structure and risk transmission between China's north–south capital flow and the stock market and foreign exchange market. The results show that the correlation between southward capital and the mainland stock market is stronger, and the correlation between northward capital and the Hong Kong stock market is stronger. The correlation between northward capital and RMB exchange rate is greater than that between southward capital and RMB exchange rate. After the outbreak of COVID-19, the correlation between capital flows and the stock market has strengthened, while the correlation with the foreign exchange market has weakened. Furthermore, there is a bidirectional risk transmission between the north–south capital flow and China's stock market and foreign exchange market. In general, the north–south capital flow has a greater impact on the stock market, and the exchange rate of RMB/US dollar has a greater impact on the north–south capital flow. This study has implications for investors and policymakers. [ABSTRACT FROM AUTHOR]

In this paper, we first proposed a statistical test for the detrended multiple moving average cross-correlation coefficient DMMC (s). The DMMC (s) mainly was used to analyze the correlation between the dependent variable y and other n independent variables x i . We proved that DMMC (s) approximately obeys the chi-square distribution. We studied the statistical properties of the DMMC (s) between normally distributed random sequences and power-law ARFIMA long memory random sequences. Furthermore, we discussed the influence of the cross-correlation among the target variable and independent variables on DMMC (s). Finally, we further study the application of DMMC (s) to China's stock markets and China carbon emission trading markets to investigate multiple cross-correlation. The empirical results show that there is a strong multiple correlation between China's Shanghai, Shenzhen and Hong Kong stock markets, while the correlation between China's carbon markets is not significant. This paper provides new ideas and theoretical support for exploring the correlation between multiple variables, which has implications for investors and policymakers. [ABSTRACT FROM AUTHOR]

It has been reported that systematic bias exists in gauge measurements, which are usually used as the evaluation benchmark, so it is crucial to investigate the impacts of gauge data bias on the evaluation of satellite precipitation products. Six satellite precipitation products (IMERG, CMORPH, GSMaP, PERSIANN, PERSIANN−CCS, and PDIR−Now) and gauge data are collected from 2003 to 2015 in the arid region of Northwestern China. A daily correction for precipitation biases from wind-induced undercatch, wetting loss, and trace error is made for gauge measurements. The changes in metrics, including four continuous and four categorical metrics, are calculated to illustrate how the gauge data bias impacts the evaluation of six satellite precipitation products. The results show the following: The overall performances of six satellite precipitation products are undervalued by the gauge bias. Compared to other satellite products, the performance of IMERG is the best, whether before or after bias correction. However, the performances of all six satellite products are still not good enough even after bias correction and need to be improved. The impacts of gauge bias on the evaluation of the satellite precipitation products also differ by subregion, season, satellite precipitation product, precipitation intensity, and precipitation phase. In conclusion, the impacts of the gauge bias on the performance assessment of satellite products are obvious over the study region, implying that bias correction for gauge measurements is needed to obtain an accurate understanding of the performance of satellite precipitation products if choosing the gauge data as the evaluation benchmark. [ABSTRACT FROM AUTHOR]

Evaluating the accuracy of the satellite and reanalysis precipitation products is very important for understanding their uncertainties and potential applications. However, because of underestimation existing in commonly used evaluation benchmark, gauge precipitation data, it is necessary to investigate the influence of systematic errors in gauge data on the performance evaluation of satellite and reanalysis precipitation datasets. Daily satellite-based IMERG and model-based ERA5-Land, together with gauge precipitation data, were collected with the period from 2005 to 2016 over China in this study. Daily corrections for precipitation biases from wind-induced undercatch, wetting loss, and trace error were made for gauge measurements. A set of metrics, including relative bias, Kling-Gupta efficiency, frequency bias, and critical success index, were used to evaluate and intercompare the performances of IMERG and ERA5-Land against original and bias-corrected gauge data in different locations, years, seasons, climatic zones, classes of precipitation events, and precipitation phases. The results have shown that: After removing the bias in gauge data, the relative biases of IMERG and ERA5-Land both significantly decline. The noticeable changes of their accuracy occur and vary with different locations, years, seasons, climatic zones, and precipitation phases. Furthermore, the frequency biases of IMERG and ERA5-Land rise in no precipitation events and decline in light, moderate, heavy, and extreme precipitation events. The detection capability of IMERG and ERA5-Land in no and light precipitation events is also obviously affected. Therefore, this study has demonstrated the significant influence of systematic gauge precipitation errors on the assessment of IMERG and ERA5-Land and reinforces the necessity to remove negative bias in gauge data before using it as the benchmark. [ABSTRACT FROM AUTHOR]

With the reduction and depletion of shallow energy, the mining depth of coal around the world is increasing year by year, and the mining depth of some coal mines in China has reached kilometers. The main roadway near the goaf with the deep high static stress is very easy to be damaged after being disturbed by the mine earthquake. Taking the main roadway in the no. 1 mining area of Gaojiapu coal mine in Binchang mining area, Shaanxi Province, China, as the engineering background, the high-energy mine earthquake monitored by the on-site microseism is equivalently simulated through the dynamic module of FLAC3D, and the spatial-temporal rotation characteristics of the principal stress of roadway surrounding rock under the disturbance of mine earthquake are studied and analyzed and put forward corresponding prevention and control measures. Research shows early stage of mine earthquake disturbance, roadway roof is first affected, and the principal stress of the roof has the trend of deflection to the side of the goaf. In the middle stage of mine earthquake disturbance, the main body of roof principal stress deflects to the side of goaf, and the deflection range is large. In the later stage of mine earthquake disturbance, the principal stress directions in the surrounding rock reverse rotation, and the reverse rotation angle of the principal stress direction in the roof is the largest. Finally, the asymmetric distribution characteristics of principal stress rotation are verified by using the asymmetric deformation phenomenon on both sides of roadway surrounding rock. Based on the rotation characteristics of principal stress under the dual influence of mine earthquake disturbance and goaf, optimize the layout scheme and blasting parameters of blasting pressure relief holes. The transmission direction of principal stress can be changed by blasting pressure relief method; meanwhile, the transmission of principal stress can be blocked; through the comparison of microseismic activity law before and after pressure relief, pressure relief effect is good. The research results can provide a certain reference basis for coal mine roadway pressure relief and reducing disaster conditions. [ABSTRACT FROM AUTHOR]

In order to get the law of rainwater infiltration and the law of progressive water damage, the slope of Tianshang bridge foundation in Yunnan Province of China is taken as the engineering basis. The site investigation of the damaged slope is carried out. The traditional Green-Ampt model is improved by considering the ponding effect of dynamic water flow on the slope surface. Based on the variation characteristics of wetting front obtained by the improved infiltration model, the progressive failure process of slope with continuous infiltration is simulated by FLAC3D software. The results show that the water damage of Tianshang bridge slope is mainly caused by the slope absorbing a lot of rainwater in a short time, which has obvious time discontinuity characteristics in time, and shows obvious multi-layer progressive failure characteristics in failure space. The wetting front characteristics obtained by the improved Green-Ampt infiltration model are more consistent with the engineering practice. The water accumulation effect of surface water gradually weakens with the increase of the wet front depth. The slope failure develops gradually from the toe to the top and from shallow to deep. The intermittent failure characteristics provide surplus time for the engineering treatment, the gravel soil slope should be treated after a small-scale water damage occurs. [ABSTRACT FROM AUTHOR]

With the reduction and depletion of shallow energy, the mining depth of coal around the world is increasing year by year, and the mining depth of some coal mines in China has reached kilometers. The main roadway near the goaf with the deep high static stress is very easy to be damaged after being disturbed by the mine earthquake. Taking the main roadway in the no. 1 mining area of Gaojiapu coal mine in Binchang mining area, Shaanxi Province, China, as the engineering background, the high-energy mine earthquake monitored by the on-site microseism is equivalently simulated through the dynamic module of FLAC3D, and the spatial-temporal rotation characteristics of the principal stress of roadway surrounding rock under the disturbance of mine earthquake are studied and analyzed and put forward corresponding prevention and control measures. Research shows early stage of mine earthquake disturbance, roadway roof is first affected, and the principal stress of the roof has the trend of deflection to the side of the goaf. In the middle stage of mine earthquake disturbance, the main body of roof principal stress deflects to the side of goaf, and the deflection range is large. In the later stage of mine earthquake disturbance, the principal stress directions in the surrounding rock reverse rotation, and the reverse rotation angle of the principal stress direction in the roof is the largest. Finally, the asymmetric distribution characteristics of principal stress rotation are verified by using the asymmetric deformation phenomenon on both sides of roadway surrounding rock. Based on the rotation characteristics of principal stress under the dual influence of mine earthquake disturbance and goaf, optimize the layout scheme and blasting parameters of blasting pressure relief holes. The transmission direction of principal stress can be changed by blasting pressure relief method; meanwhile, the transmission of principal stress can be blocked; through the comparison of microseismic activity law before and after pressure relief, pressure relief effect is good. The research results can provide a certain reference basis for coal mine roadway pressure relief and reducing disaster conditions. [ABSTRACT FROM AUTHOR]

Deep high static loading roadway is extremely prone to rock burst under dynamic load disturbance. The "force-energy criterion" for the failure of surrounding rock in such deep roadways and the "energy criterion" for the rock burst was established by considering the stress and energy evolution characteristics of rock burst under this circumstance. Under the engineering background of the main roadway in No.1 mining area of Gaojiapu Coal Mine in Binchang Mining Area, Shaanxi Province, China, the partial stress field and distortion energy field of surrounding rock in the main roadway and the spatial-temporal evolution laws under dynamic load disturbance were simulated and analyzed by using a built-in dynamic module of FLAC3D. Results show that after the dynamic load disturbance, the partial stress and distortion energy are concentrated in the shallow part at two walls of the roadway in the early phase. With the continuous propagation of dynamic load stress wave, the partial stress and distortion energy are transferred to the deep part. The sudden high-energy release occurred in the peak zone of partial stress, leading to the plastic failure of coal and rock mass. Subsequently, the distortion energy was fully accumulated in the original plastic zone and transferred from shallow surrounding rocks to the deep surrounding rocks in the roadway, where the partial stress and distortion energy of coal and rock mass reached the yield conditions. Thus, the original plastic zone was sharply expanded, thereby forming a new plastic zone. The coal and rock mass experienced an approximately static failure when no residual energy (ΔU) was found in it. When ΔU > 0, the rock mass experienced dynamic failure, and ΔU was mainly the volume transformation energy, which is approximately one-half of the total elastic strain energy. ΔU was transformed into the initial kinetic energy of broken coal and rock mass. Thus, the coal and rock mass are burst out. In severe cases, this condition was manifested by the rock burst in the main roadway. An optimization scheme of prevention and control measures for rock burst was proposed on the basis of the above conclusions. The microseismic activity laws before and after the unloading were compared, and a good effect was achieved. The research results can lay a theoretical foundation for predicting and preventing rock bursts in coal mines by actively regulating the disaster-pregnant environment and mitigating the disaster-inducing conditions. [ABSTRACT FROM AUTHOR]