The equatorial Pacific upwelling zone has been suspected of playing an important role in the global atmospheric CO2 changes associated with glacial-interglacial cycles. In order to assess the influencing scope of the ...The equatorial Pacific upwelling zone has been suspected of playing an important role in the global atmospheric CO2 changes associated with glacial-interglacial cycles. In order to assess the influencing scope of the surface water deglacial δ13C minimum in the tropical low-latitude Pacific, the core DGKS9603, collected from the middle Okinawa Trough, was examined for δ13C records of planktonic fo-raminifera N. dutertrei and G. ruber. The planktonic fo-raminiferal δ13C records show a clear decreasing event from 20 to 6 cal. kaBP., which is characterized by long duration of about 14 ka and amplitude shift of 0.4×10-3. Its minimum value occurred at 15.7 cal kaBP. The event shows fairly synchrony with the surface water deglacial δ13C minimum identified in the tropical Pacific and its marginal seas. Because there is no evidence in planktonic foraminiferal fauna and δ18O records for upwelling and river runoff enhancement, the broad deglacial δ13C minimum event in planktonic foraminiferal records展开更多
The planktonic foraminiferal faunal census of core MD 05-2894 (7°2.25′N, 111°33.11′E, water depth 1982 m), retrieved from the southern South China Sea (SCS) during the "Marco Polo" cruise in 2005...The planktonic foraminiferal faunal census of core MD 05-2894 (7°2.25′N, 111°33.11′E, water depth 1982 m), retrieved from the southern South China Sea (SCS) during the "Marco Polo" cruise in 2005, was performed to investigate the abundance changes of a subsurface dweller, Pulleniatina obliquiloculata. The results display that the abundance of P. obliquiloculata nearly declines to zero during 16.0―14.9 ka, corresponding to the Heinrich 1 (H1) cold interval. The unexpected decrease of P. obliquiloculata occurs in the adjacent cores, roughly between 17 and 14.8 ka based on the previous studies. Accordingly, the Pulleniatina Minimum Event in the last deglaciation can serve as a good stratigraphical indicator, at least in the southern SCS. To further explore the changes of sea surface temperature (SST) and subsurface seawater temperature (SSST), we made parallel Mg/Ca measurements on surface dweller Globigerinoides ruber and subsurface dweller P. obliquiloculata tests. Since the last deglaciation, the SSTs show a continuous increasing trend towards the late Holocene, while the warming of the subsurface water is punctuated by a 2℃-cooling interval across the deglacial Pulleniatina Minimum Event. Both increased δ18O differences between G. ruber and P. obliquiloculata, and increased temperature differences between surface and subsurface water suggest a shoaling of the mixed layer during the deglacial Pulleniatina Minimum Event. Therefore, we consider that the significant changes in the upper ocean structure are responsible for the Pulleniatina Minimum Event during the last deglaciation in the southern SCS.展开更多
针对基于数据分发服务的分散式组网导航系统(decentralized networked navigation system based on DDS,DDS-DNNS)单定位节点状态估计问题,考虑节点能量约束及传感器增益退化,以Bayes理论为基础,设计了具有随机事件触发机制(stochastic ...针对基于数据分发服务的分散式组网导航系统(decentralized networked navigation system based on DDS,DDS-DNNS)单定位节点状态估计问题,考虑节点能量约束及传感器增益退化,以Bayes理论为基础,设计了具有随机事件触发机制(stochastic event-triggered,SET)的DDS-DNNS最小均方误差状态估计器。其中,SET机制通过比较是否传输测量值对应的后验估计的差异来决定测量值的重要程度。以此为基础,选取Wasserstein距离作为度量来表示后验估计的差异,并利用Wasserstein距离的性质及Bayes定理证明了后验估计是Gaussian的,从而得到了估计器的类Kalman滤波递推形式以及SET机制的显式表达式。证明了估计器的预测误差协方差有界,且上界和下界均收敛,同时,证明了平均信息传输率有界并推导得到了上界和下界的表达式。利用算例仿真演示了如何通过平均信息传输率的上界和下界确定调整矩阵,模拟了SET机制中一阶矩信息和二阶矩信息对SET机制的影响,同时采用比较实验验证了估计器的有效性。展开更多
[ Objective] The research aimed to study temporal-spatial change characteristics of the extremely low temperature climate event in winter of China. [MethodI By using actual probability distribution threshold value met...[ Objective] The research aimed to study temporal-spatial change characteristics of the extremely low temperature climate event in winter of China. [MethodI By using actual probability distribution threshold value method, EOF analysis method and the daily minimum temperature data in winter of 1961 -2008 at 195 observatories of China, temporal-spatial change characteristics of the extremely low temperature climate event in win- ter of China in 48 years were analyzed. [ Result] Threshold value calculated by actual probability distribution was higher than that by traditional method, and increase magnitude in east was bigger than that in west, which could describe climatic change situation in China in 48 years better than traditional method. Cold night number in winter of China did not decrease as latitude declined, and it was more in south and north and was less in Yellow River basin and northwest China. Cold night number was the most in northeast Inner Mongolia. Interannual change of the cold night number presented decline tendency. From the 1960s to the eady 1970s, cold night number consistently increased, and change in middle and late periods of the 1960s was severe. From the early 1970s to the middle 1980s, fluctuation of the cold night number was bigger, and increase of the cold night number was the most in 1976. Cold night number from 1986 to the 21= century continuously declined. Change of the cold night number was the most obvious in east region, Guizhou and north Guangxi. Cold night number in northeast China and north Inner Mongolia presented inverting change relationship with that in Yunnan - Kweichow Plateau and Hexi Corridor. [ Conclusion] The research provided reference for eady warning of the extremely low temoerature event in China.展开更多
为全面评估航空器小于管制规定间隔事件中的管制员工作状态,提出1种管制员工作状态量化评估方法。首先,基于关键词的词频和共现频率挖掘小于管制规定间隔事件的致因,并在此基础上改进人因分析和分类系统(human factors analysis and cla...为全面评估航空器小于管制规定间隔事件中的管制员工作状态,提出1种管制员工作状态量化评估方法。首先,基于关键词的词频和共现频率挖掘小于管制规定间隔事件的致因,并在此基础上改进人因分析和分类系统(human factors analysis and classification system,HFACS)模型,构建小于管制规定间隔事件的管制员工作状态评估指标体系,合并相同致因因素以最终得到该事件的致因链条。其次,分析各层指标之间的关系,并构建事件致因复杂网络,通过网络的度中心性、介数中心性和PageRank值计算指标的综合权重,进而通过线性加权量化管制员工作状态的危险指数。最后,基于中国民用航空安全信息系统实际案例分析验证管制员工作状态量化评估方法。研究结果表明:繁忙空域/流量大、硬件设备故障、现场管理缺位是综合权重排名前3的关键致因因素;改进的HFACS模型能够全面揭示导致小于管制规定间隔事件发生的人为因素及其耦合关系,最终得到了341条事件致因链条;管制员工作状态评估结果与事件调查报告的结论基本一致,可验证本文所提方法的合理性。研究结果可为管制员工作状态评估提供参考。展开更多
基金This work was supported jointly by SSTC andSOA, China and IFREMER, France and also by the National Natural Science Foundation of China (Grant Nos. 49736210 and 40176019)the National Major Basic Research and Development Project (Grant No. G20000467)
文摘The equatorial Pacific upwelling zone has been suspected of playing an important role in the global atmospheric CO2 changes associated with glacial-interglacial cycles. In order to assess the influencing scope of the surface water deglacial δ13C minimum in the tropical low-latitude Pacific, the core DGKS9603, collected from the middle Okinawa Trough, was examined for δ13C records of planktonic fo-raminifera N. dutertrei and G. ruber. The planktonic fo-raminiferal δ13C records show a clear decreasing event from 20 to 6 cal. kaBP., which is characterized by long duration of about 14 ka and amplitude shift of 0.4×10-3. Its minimum value occurred at 15.7 cal kaBP. The event shows fairly synchrony with the surface water deglacial δ13C minimum identified in the tropical Pacific and its marginal seas. Because there is no evidence in planktonic foraminiferal fauna and δ18O records for upwelling and river runoff enhancement, the broad deglacial δ13C minimum event in planktonic foraminiferal records
基金Supported by National Basic Research Program of China (Grant No.2007CB815900)National Natural Science Foundation of China (Grant No. 40621063)China Ocean Mineral Resources Research and Development Association (Grant No. DY 115-01-2-3)
文摘The planktonic foraminiferal faunal census of core MD 05-2894 (7°2.25′N, 111°33.11′E, water depth 1982 m), retrieved from the southern South China Sea (SCS) during the "Marco Polo" cruise in 2005, was performed to investigate the abundance changes of a subsurface dweller, Pulleniatina obliquiloculata. The results display that the abundance of P. obliquiloculata nearly declines to zero during 16.0―14.9 ka, corresponding to the Heinrich 1 (H1) cold interval. The unexpected decrease of P. obliquiloculata occurs in the adjacent cores, roughly between 17 and 14.8 ka based on the previous studies. Accordingly, the Pulleniatina Minimum Event in the last deglaciation can serve as a good stratigraphical indicator, at least in the southern SCS. To further explore the changes of sea surface temperature (SST) and subsurface seawater temperature (SSST), we made parallel Mg/Ca measurements on surface dweller Globigerinoides ruber and subsurface dweller P. obliquiloculata tests. Since the last deglaciation, the SSTs show a continuous increasing trend towards the late Holocene, while the warming of the subsurface water is punctuated by a 2℃-cooling interval across the deglacial Pulleniatina Minimum Event. Both increased δ18O differences between G. ruber and P. obliquiloculata, and increased temperature differences between surface and subsurface water suggest a shoaling of the mixed layer during the deglacial Pulleniatina Minimum Event. Therefore, we consider that the significant changes in the upper ocean structure are responsible for the Pulleniatina Minimum Event during the last deglaciation in the southern SCS.
文摘针对基于数据分发服务的分散式组网导航系统(decentralized networked navigation system based on DDS,DDS-DNNS)单定位节点状态估计问题,考虑节点能量约束及传感器增益退化,以Bayes理论为基础,设计了具有随机事件触发机制(stochastic event-triggered,SET)的DDS-DNNS最小均方误差状态估计器。其中,SET机制通过比较是否传输测量值对应的后验估计的差异来决定测量值的重要程度。以此为基础,选取Wasserstein距离作为度量来表示后验估计的差异,并利用Wasserstein距离的性质及Bayes定理证明了后验估计是Gaussian的,从而得到了估计器的类Kalman滤波递推形式以及SET机制的显式表达式。证明了估计器的预测误差协方差有界,且上界和下界均收敛,同时,证明了平均信息传输率有界并推导得到了上界和下界的表达式。利用算例仿真演示了如何通过平均信息传输率的上界和下界确定调整矩阵,模拟了SET机制中一阶矩信息和二阶矩信息对SET机制的影响,同时采用比较实验验证了估计器的有效性。
文摘[ Objective] The research aimed to study temporal-spatial change characteristics of the extremely low temperature climate event in winter of China. [MethodI By using actual probability distribution threshold value method, EOF analysis method and the daily minimum temperature data in winter of 1961 -2008 at 195 observatories of China, temporal-spatial change characteristics of the extremely low temperature climate event in win- ter of China in 48 years were analyzed. [ Result] Threshold value calculated by actual probability distribution was higher than that by traditional method, and increase magnitude in east was bigger than that in west, which could describe climatic change situation in China in 48 years better than traditional method. Cold night number in winter of China did not decrease as latitude declined, and it was more in south and north and was less in Yellow River basin and northwest China. Cold night number was the most in northeast Inner Mongolia. Interannual change of the cold night number presented decline tendency. From the 1960s to the eady 1970s, cold night number consistently increased, and change in middle and late periods of the 1960s was severe. From the early 1970s to the middle 1980s, fluctuation of the cold night number was bigger, and increase of the cold night number was the most in 1976. Cold night number from 1986 to the 21= century continuously declined. Change of the cold night number was the most obvious in east region, Guizhou and north Guangxi. Cold night number in northeast China and north Inner Mongolia presented inverting change relationship with that in Yunnan - Kweichow Plateau and Hexi Corridor. [ Conclusion] The research provided reference for eady warning of the extremely low temoerature event in China.
