Coal gasification fine slag(CGFS)is a solid waste produced in the process of coal gasification.The separation of residue carbon in CGFS is essential for its resource utilization.In this study,the basic physical proper...Coal gasification fine slag(CGFS)is a solid waste produced in the process of coal gasification.The separation of residue carbon in CGFS is essential for its resource utilization.In this study,the basic physical properties of CGFS were analyzed and the effect of physical separation experiments were carried out.The gravity separation results indicated that the coarser particle size fraction achieved a good separation effect.The High-carbon product has a yield of 12.53% with an ash content of 16.84%,and the High-ash product has a yield of 17.85%with an ash content of 98.15% were obtained.Theoretical calculations indicated that the apparent density difference between residue carbon and ash minerals in the water phase environment was the basis for achieving separation.The Rich-ash product was further separated by magnetic separation,and both magnetic field characteristics,water elutriation frequency and grinding time had impacts on the magnetic separation effect.Compared to gravity separation alone,the combined gravity-magnetic separation further enhanced the separation effect of residue carbon and ash minerals.The ash content of the Rich-ash product decreased from 80.56% to 69.52% due to the removal of high-ash Fe oxides,and the yield of combined separation tailings increased from 17.85% to 41.75%.The characterization results obtained through SEM-EDS,VSM,XRD and XRF analysis demonstrated significant differences in saturation magnetization,mineral composition and peak intensity among magnetic separation products,confirming that the feasibility of magnetic separation.The research findings contribute to a better understanding of the separation mechanism and provide a new separation process for efficiently enriching residue carbon from CGFS,also facilitate the step utilization of separation products.展开更多
Seismic safety assessment of gravity dams has become a major concern in many regions of the world while the effects of vertical seismic accelerations on the response of structures remain poorly understood.This paper f...Seismic safety assessment of gravity dams has become a major concern in many regions of the world while the effects of vertical seismic accelerations on the response of structures remain poorly understood.This paper first investigates the effect of including vertical accelerations in the sliding response analysis of gravity dams subjected to a range of historical ground motion records separated in two groups according to their source-to-site distance.Analyses showed that the incidence of vertical accelerations on the sliding response of gravity dams is significantly higher for near-source records than for far- source records.The pseudo-static 30% load combination rule,commonly used in practice to account for the non-simultaneous occurrence of the peak horizontal and vertical accelerations,yielded good approximations of the minimum safety factors against sliding computed from time-history analyses.A method for empirically estimating the vertical response spectra based on horizontal spectra,accounting for the difference in frequency content and amplitudes between the two components is investigated.Results from analyses using spectrum compatible horizontal and vertical synthetic records also approximated well the sliding response of a gravity dam subjected to series of simultaneous horizontal and vertical historical earthquake records.展开更多
The features of precursors of crustal deformation and gravity before some strong earthquakes in North China have been analyzed. The results show that, before strong earthquakes, a close tectonics-dependent dynamic pro...The features of precursors of crustal deformation and gravity before some strong earthquakes in North China have been analyzed. The results show that, before strong earthquakes, a close tectonics-dependent dynamic process should exist in large areas and the media in the epicentral area should change their state. With these results as a basis, an improved combination-hardening model has been put forward. When the adjusting element moves, the tectonic movements is intensified in large areas and the density of deep media on both sides of faults will be changed. In the stress concentration element, there will be a media hardening process due to the continuous accumulation of energy. It is such a mechanism that results in the various steps of precursors.展开更多
Since April 2002,the Gravity Recovery and Climate Experiment Satellite(GRACE)has provided monthly total water storage anomalies(TWSAs)on a global scale.However,these TWSAs are discontinuous because some GRACE observat...Since April 2002,the Gravity Recovery and Climate Experiment Satellite(GRACE)has provided monthly total water storage anomalies(TWSAs)on a global scale.However,these TWSAs are discontinuous because some GRACE observation data are missing.This study presents a combined machine learning-based modeling algorithm without hydrological model data.The TWSA time-series data for 11 large regions worldwide were divided into training and test sets.Autoregressive integrated moving average(ARIMA),long short-term memory(LSTM),and an ARIMA-LSTM combined model were used.The model predictions were compared with GRACE observations,and the model accuracy was evaluated using fi ve metrics:the Nash-Sutcliff e effi ciency coeffi cient(NSE),Pearson correlation coeffi cient(CC),root mean square error(RMSE),normalized RMSE(NRMSE),and mean absolute percentage error.The results show that at the basin scale,the mean CC,NSE,and NRMSE for the ARIMA-LSTM model were 0.93,0.83,and 0.12,respectively.At the grid scale,this study compared the spatial distribution and cumulative distribution function curves of the metrics in the Amazon and Volga River basins.The ARIMA-LSTM model had mean CC and NSE values of 0.89 and 0.61 and 0.92 and 0.61 in the Amazon and Volga River basins,respectively,which are superior to those of the ARIMA model(0.86 and 0.48 and 0.88 and 0.46,respectively)and the LSTM model(0.80 and 0.41 and 0.89 and 0.31,respectively).In the ARIMA-LSTM model,the proportions of grid cells with NSE>0.50 for the two basins were 63.3%and 80.8%,while they were 54.3%and 51.3%in the ARIMA model and 53.7%and 43.2%in the LSTM model.The ARIMA-LSTM model significantly improved the NSE values of the predictions while guaranteeing high CC values in the GRACE data reconstruction at both scales,which can aid in fi lling in discontinuous data in temporal gravity fi eld models..展开更多
基金supported by the National Natural Science Foundation of China(52104262)the Joint Funds of the National Natural Science Foundation of China(U23A20131)the National Key Research and Development Plan(2023YFB4103501,2022YFB4101604).
文摘Coal gasification fine slag(CGFS)is a solid waste produced in the process of coal gasification.The separation of residue carbon in CGFS is essential for its resource utilization.In this study,the basic physical properties of CGFS were analyzed and the effect of physical separation experiments were carried out.The gravity separation results indicated that the coarser particle size fraction achieved a good separation effect.The High-carbon product has a yield of 12.53% with an ash content of 16.84%,and the High-ash product has a yield of 17.85%with an ash content of 98.15% were obtained.Theoretical calculations indicated that the apparent density difference between residue carbon and ash minerals in the water phase environment was the basis for achieving separation.The Rich-ash product was further separated by magnetic separation,and both magnetic field characteristics,water elutriation frequency and grinding time had impacts on the magnetic separation effect.Compared to gravity separation alone,the combined gravity-magnetic separation further enhanced the separation effect of residue carbon and ash minerals.The ash content of the Rich-ash product decreased from 80.56% to 69.52% due to the removal of high-ash Fe oxides,and the yield of combined separation tailings increased from 17.85% to 41.75%.The characterization results obtained through SEM-EDS,VSM,XRD and XRF analysis demonstrated significant differences in saturation magnetization,mineral composition and peak intensity among magnetic separation products,confirming that the feasibility of magnetic separation.The research findings contribute to a better understanding of the separation mechanism and provide a new separation process for efficiently enriching residue carbon from CGFS,also facilitate the step utilization of separation products.
基金Natural Seienee and Engineering Researeh Couneilof Canada(NSERC),Hydro-Qucbcc,Alcanthe "fonds Pour la Formation de Chereheurs et l'Aide ala Recherehe"(FCAR) of Quebec
文摘Seismic safety assessment of gravity dams has become a major concern in many regions of the world while the effects of vertical seismic accelerations on the response of structures remain poorly understood.This paper first investigates the effect of including vertical accelerations in the sliding response analysis of gravity dams subjected to a range of historical ground motion records separated in two groups according to their source-to-site distance.Analyses showed that the incidence of vertical accelerations on the sliding response of gravity dams is significantly higher for near-source records than for far- source records.The pseudo-static 30% load combination rule,commonly used in practice to account for the non-simultaneous occurrence of the peak horizontal and vertical accelerations,yielded good approximations of the minimum safety factors against sliding computed from time-history analyses.A method for empirically estimating the vertical response spectra based on horizontal spectra,accounting for the difference in frequency content and amplitudes between the two components is investigated.Results from analyses using spectrum compatible horizontal and vertical synthetic records also approximated well the sliding response of a gravity dam subjected to series of simultaneous horizontal and vertical historical earthquake records.
基金This project is one of the research achievements of the "Ninth Five-Year Plan" under No. 95-04, CSB, China.
文摘The features of precursors of crustal deformation and gravity before some strong earthquakes in North China have been analyzed. The results show that, before strong earthquakes, a close tectonics-dependent dynamic process should exist in large areas and the media in the epicentral area should change their state. With these results as a basis, an improved combination-hardening model has been put forward. When the adjusting element moves, the tectonic movements is intensified in large areas and the density of deep media on both sides of faults will be changed. In the stress concentration element, there will be a media hardening process due to the continuous accumulation of energy. It is such a mechanism that results in the various steps of precursors.
基金financially supported by The National Natural Science Foundation of China (42374004)the Open Fund of Hubei Luojia Laboratory (220100045)the Natural Science Foundation of Sichuan Province (2022NSFSC1047)。
文摘Since April 2002,the Gravity Recovery and Climate Experiment Satellite(GRACE)has provided monthly total water storage anomalies(TWSAs)on a global scale.However,these TWSAs are discontinuous because some GRACE observation data are missing.This study presents a combined machine learning-based modeling algorithm without hydrological model data.The TWSA time-series data for 11 large regions worldwide were divided into training and test sets.Autoregressive integrated moving average(ARIMA),long short-term memory(LSTM),and an ARIMA-LSTM combined model were used.The model predictions were compared with GRACE observations,and the model accuracy was evaluated using fi ve metrics:the Nash-Sutcliff e effi ciency coeffi cient(NSE),Pearson correlation coeffi cient(CC),root mean square error(RMSE),normalized RMSE(NRMSE),and mean absolute percentage error.The results show that at the basin scale,the mean CC,NSE,and NRMSE for the ARIMA-LSTM model were 0.93,0.83,and 0.12,respectively.At the grid scale,this study compared the spatial distribution and cumulative distribution function curves of the metrics in the Amazon and Volga River basins.The ARIMA-LSTM model had mean CC and NSE values of 0.89 and 0.61 and 0.92 and 0.61 in the Amazon and Volga River basins,respectively,which are superior to those of the ARIMA model(0.86 and 0.48 and 0.88 and 0.46,respectively)and the LSTM model(0.80 and 0.41 and 0.89 and 0.31,respectively).In the ARIMA-LSTM model,the proportions of grid cells with NSE>0.50 for the two basins were 63.3%and 80.8%,while they were 54.3%and 51.3%in the ARIMA model and 53.7%and 43.2%in the LSTM model.The ARIMA-LSTM model significantly improved the NSE values of the predictions while guaranteeing high CC values in the GRACE data reconstruction at both scales,which can aid in fi lling in discontinuous data in temporal gravity fi eld models..
