Lower groups of coal seams are presently being mined from water-inrush from coal floors in order to have safe production in the Yanzhou coal mining area. We need to evaluate the risk in the lower groups of coal seams ...Lower groups of coal seams are presently being mined from water-inrush from coal floors in order to have safe production in the Yanzhou coal mining area. We need to evaluate the risk in the lower groups of coal seams in mines. Based on a systematic collection of hydrogeological data and some data from mined working faces in these lower groups, we evaluated the factors affecting water-inrush from coal floors of the area by a method of dimensionless analysis. We obtained the order of the factors affecting water-inrush from coal floors and recalculated data on depths of destroyed floors by multiple linear regression analysis and obtained new empirical formulas. We also analyzed the water-inrush coefficient of mined working faces of the lower groups of coal seams and improved the evaluation standard of the water-inrush coefficient method. Finally, we made a comprehensive evaluation of water-inrush risks from coal floors by using the water-inrush coefficient method and a fuzzy clustering method. The evaluation results provide a solid foundation for preventing and controlling the damage caused by water of an Ordovician limestone aquifer in the lower group of coal seams in the mines of Yanzhou. It provides also important guidelines for lower groups of coal seams in other coal mines.展开更多
Using reanalysis data as a benchmark, the authors evaluate the performance of an Atmospheric General Circulation Model （AGCM） named GAMIL （Grid-point Atmospheric Model of LASG/IAP）. GAMIL is used to simulate the t...Using reanalysis data as a benchmark, the authors evaluate the performance of an Atmospheric General Circulation Model （AGCM） named GAMIL （Grid-point Atmospheric Model of LASG/IAP）. GAMIL is used to simulate the tropospheric temperature anoma- lies associated with the El Nifio-Southern Oscillation （ENSO） in boreal winters for the period 1980-99. The results show that the symmetrical components of tem- perature anomalies simulated by GAMIL closely resem- ble those in the reanalysis data in spatial patterns, espe- cially in the Northern Hemisphere. The limitation of the model is that the simulated cold anomaly over South Asia is located to the east of the reanalysis. The observed tem- perature anomalies in the South Pacific and the high lati- tudes of the Southern Hemisphere are not evident in the simulation. The maximum value is 0.8 K smaller and the minimum value is -0.4 K smaller than the reanalysis. The difference between the simulation and the reanalysis is more evident in the regional features of the asymmetrical components of the temperature anomalies. Our results demonstrate that the previously discovered weak response of the GAMIL model to specified sea surface temperature forcing is dominated by the symmetric （asymmetric） component in the tropics （extra-tropics）.展开更多
In the process of accurate interpretation of multi-wave seismic data,we wanted to solve the problem of multi-wave information recognition.Based on techniques of elastic wave forwarding,targeting the geological model o...In the process of accurate interpretation of multi-wave seismic data,we wanted to solve the problem of multi-wave information recognition.Based on techniques of elastic wave forwarding,targeting the geological model of a reservoir of an oil field exploration area,we used a high-order staggered-grid difference technology to simulate many shots of seismic records of nonzero offset shots,implemented multi-wave seismic data processing to acquire the CMP of P waves and converted waves,NMO traces of CCP pre stacks,including AVA information and superposition profiles.Based on the AVA calculation of the model,the layer parameters of the model and the forwarding wave field relations of the P-S wave,we also compared and studied the correspondence between P waves and converted waves.The results of our analysis show that the results from simulation and from the AVO analysis are consistent.Significant wave field differences between P waves and converted waves in the same reservoir were found,which are helpful in recognizing and interpreting the multi-wave information in this area.We made use of the multi-wave data to provide the important guidelines for reservoir prediction.展开更多
During 1979–2004, the East Asian summer precipitation has experienced another significant decadal shift around the early 1990 s. Based on three radiosonde temperature datasets and four reanalysis datasets, this paper...During 1979–2004, the East Asian summer precipitation has experienced another significant decadal shift around the early 1990 s. Based on three radiosonde temperature datasets and four reanalysis datasets, this paper examines the decadal change of the East Asian summer tropospheric temperature around the early 1990 s. The results show that the meridional gradient of layer mean upper tropospheric temperature for 200–500 h Pa(here after UTT, UTT is upper tropospheric temperature) also underwent an obvious decadal decrease around 1992. The tropospheric temperature south to 35°N becomes decadal cooling, centered along the Yangtze River Valley, while the tropospheric temperature north to 35°N shows a decadal warming, centered in Northwest China-Mongolia. JRA-25 reanalysis is better than the other reanalysis datasets in revealing this decadal change. This decadal shift of East Asian summer UTT may be ascribed to the decadal change of the ENSO period from low-frequency oscillation(4–6 yr) to quasi-biennial oscillation since 1992. It behaves as an increase of ENSO developing events and a reduction of ENSO decaying events. It leads to stronger forcing of ENSO developing summer and weaker forcing of ENSO decaying summer, leading to the dominant role of monopole cooling mode of East Asian UTT after 1992, in contrast to the dominant role of dipole mode of East Asia UTT before 1992. The summer UTT difference between 1993–2004 and 1979–1992 shows a "South cooling-North Warming" pattern, and thereby contributes to the interdecadal decrease of East Asian summer UTT meridional gradient around 1992.展开更多
Discriminating internal layers by radio echo sounding is important in analyzing the thickness and ice deposits in the Antarctic ice sheet.The signal processing method of synthesis aperture radar(SAR)has been widely us...Discriminating internal layers by radio echo sounding is important in analyzing the thickness and ice deposits in the Antarctic ice sheet.The signal processing method of synthesis aperture radar(SAR)has been widely used for improving the signal to noise ratio(SNR)and discriminating internal layers by radio echo sounding data of ice sheets.This method is not efficient when we use edge detection operators to obtain accurate information of the layers,especially the ice-bed interface.This paper presents a new image processing method via a combined robust principal component analysis-total variation(RPCA-TV)approach for discriminating internal layers of ice sheets by radio echo sounding data.The RPCA-based method is adopted to project the high-dimensional observations to low-dimensional subspace structure to accelerate the operation of the TV-based method,which is used to discriminate the internal layers.The efficiency of the presented method has been tested on simulation data and the dataset of the Institute of Electronics,Chinese Academy of Sciences,collected during CHINARE 28.The results show that the new method is more efficient than the previous method in discriminating internal layers of ice sheets by radio echo sounding data.展开更多
基金supports from the Natural Science Foundation of Shandong Province (No.Y2007F46)the Doctor Disciplines Special Scientific Research Foundation of Ministry of Education (No.20070424005)+1 种基金China Coal Industry Association Science and Technology Research Instructive Plan (No.MTKJ2009-290) the National Natural Science Foundation of China (No.50539080)
文摘Lower groups of coal seams are presently being mined from water-inrush from coal floors in order to have safe production in the Yanzhou coal mining area. We need to evaluate the risk in the lower groups of coal seams in mines. Based on a systematic collection of hydrogeological data and some data from mined working faces in these lower groups, we evaluated the factors affecting water-inrush from coal floors of the area by a method of dimensionless analysis. We obtained the order of the factors affecting water-inrush from coal floors and recalculated data on depths of destroyed floors by multiple linear regression analysis and obtained new empirical formulas. We also analyzed the water-inrush coefficient of mined working faces of the lower groups of coal seams and improved the evaluation standard of the water-inrush coefficient method. Finally, we made a comprehensive evaluation of water-inrush risks from coal floors by using the water-inrush coefficient method and a fuzzy clustering method. The evaluation results provide a solid foundation for preventing and controlling the damage caused by water of an Ordovician limestone aquifer in the lower group of coal seams in the mines of Yanzhou. It provides also important guidelines for lower groups of coal seams in other coal mines.
文摘Using reanalysis data as a benchmark, the authors evaluate the performance of an Atmospheric General Circulation Model （AGCM） named GAMIL （Grid-point Atmospheric Model of LASG/IAP）. GAMIL is used to simulate the tropospheric temperature anoma- lies associated with the El Nifio-Southern Oscillation （ENSO） in boreal winters for the period 1980-99. The results show that the symmetrical components of tem- perature anomalies simulated by GAMIL closely resem- ble those in the reanalysis data in spatial patterns, espe- cially in the Northern Hemisphere. The limitation of the model is that the simulated cold anomaly over South Asia is located to the east of the reanalysis. The observed tem- perature anomalies in the South Pacific and the high lati- tudes of the Southern Hemisphere are not evident in the simulation. The maximum value is 0.8 K smaller and the minimum value is -0.4 K smaller than the reanalysis. The difference between the simulation and the reanalysis is more evident in the regional features of the asymmetrical components of the temperature anomalies. Our results demonstrate that the previously discovered weak response of the GAMIL model to specified sea surface temperature forcing is dominated by the symmetric （asymmetric） component in the tropics （extra-tropics）.
基金the Doctor Research Fund for Universities of China (No.20070616004)the National High Technology Research and Development Program of China (No.2007AA060505)
文摘In the process of accurate interpretation of multi-wave seismic data,we wanted to solve the problem of multi-wave information recognition.Based on techniques of elastic wave forwarding,targeting the geological model of a reservoir of an oil field exploration area,we used a high-order staggered-grid difference technology to simulate many shots of seismic records of nonzero offset shots,implemented multi-wave seismic data processing to acquire the CMP of P waves and converted waves,NMO traces of CCP pre stacks,including AVA information and superposition profiles.Based on the AVA calculation of the model,the layer parameters of the model and the forwarding wave field relations of the P-S wave,we also compared and studied the correspondence between P waves and converted waves.The results of our analysis show that the results from simulation and from the AVO analysis are consistent.Significant wave field differences between P waves and converted waves in the same reservoir were found,which are helpful in recognizing and interpreting the multi-wave information in this area.We made use of the multi-wave data to provide the important guidelines for reservoir prediction.
基金supported by the National Natural Science Foundation of China(Grant Nos.41305072,41330423,41023002)the"Strategic Priority Research Program-Climate Change:Carbon Budget and Related Issues"of the Chinese Academy of Sciences(Grant No.XDA05110301)the Open Program of NUIST(Grant No.KLME1306)
文摘During 1979–2004, the East Asian summer precipitation has experienced another significant decadal shift around the early 1990 s. Based on three radiosonde temperature datasets and four reanalysis datasets, this paper examines the decadal change of the East Asian summer tropospheric temperature around the early 1990 s. The results show that the meridional gradient of layer mean upper tropospheric temperature for 200–500 h Pa(here after UTT, UTT is upper tropospheric temperature) also underwent an obvious decadal decrease around 1992. The tropospheric temperature south to 35°N becomes decadal cooling, centered along the Yangtze River Valley, while the tropospheric temperature north to 35°N shows a decadal warming, centered in Northwest China-Mongolia. JRA-25 reanalysis is better than the other reanalysis datasets in revealing this decadal change. This decadal shift of East Asian summer UTT may be ascribed to the decadal change of the ENSO period from low-frequency oscillation(4–6 yr) to quasi-biennial oscillation since 1992. It behaves as an increase of ENSO developing events and a reduction of ENSO decaying events. It leads to stronger forcing of ENSO developing summer and weaker forcing of ENSO decaying summer, leading to the dominant role of monopole cooling mode of East Asian UTT after 1992, in contrast to the dominant role of dipole mode of East Asia UTT before 1992. The summer UTT difference between 1993–2004 and 1979–1992 shows a "South cooling-North Warming" pattern, and thereby contributes to the interdecadal decrease of East Asian summer UTT meridional gradient around 1992.
基金supported by the National Hi-Tech Research and Development Program of China("863"Project)(Grant No.2011AA040202)the National Natural Science Foundation of China(Grant No.40976114)
文摘Discriminating internal layers by radio echo sounding is important in analyzing the thickness and ice deposits in the Antarctic ice sheet.The signal processing method of synthesis aperture radar(SAR)has been widely used for improving the signal to noise ratio(SNR)and discriminating internal layers by radio echo sounding data of ice sheets.This method is not efficient when we use edge detection operators to obtain accurate information of the layers,especially the ice-bed interface.This paper presents a new image processing method via a combined robust principal component analysis-total variation(RPCA-TV)approach for discriminating internal layers of ice sheets by radio echo sounding data.The RPCA-based method is adopted to project the high-dimensional observations to low-dimensional subspace structure to accelerate the operation of the TV-based method,which is used to discriminate the internal layers.The efficiency of the presented method has been tested on simulation data and the dataset of the Institute of Electronics,Chinese Academy of Sciences,collected during CHINARE 28.The results show that the new method is more efficient than the previous method in discriminating internal layers of ice sheets by radio echo sounding data.
