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121.
Based on high-resolution analysis to a 280-cm long sediment core obtained from the muddy area in the central Yellow Sea, we examined the provenance of muddy sediments and discussed the changing marine sedimentary environment since the middle Holocene. The results indicated that fine-grained sediments in the muddy area were mainly derived from the Huanghe(Yellow River) and Changjiang(Yangtze River) with considerable stepwise variations during the past 6.6 kyr. The Yellow Sea Warm Current was initiated at 6 kyr when the sea level was high together with the enhanced East Asian Winter Monsoon. These in combination established the framework of shelf circulation in the Yellow Sea that began to trap the river-derived fine-grained sediments. From 4.9 kyr to 2.8 kyr, both the Kushiro Current and East Asian Monsoon were significantly weakened, reducing the delivery of Changjiang sediments to the muddy area. As a result, the sediments were mainly originated from the Huanghe. From 2.8 kyr to 1.5 kyr the continuously weakened East Asian Winter Monsoon and enhanced Yellow Sea Warm Current entrapped more fine-grain sediments. Whereas the enhanced East Asian Winter Monsoon and the human caused increase in sediment load of the Huanghe since 1.5 kyr, and direct delivery of Huanghe sediments to the Yellow Sea during 1128–1855 AD might dominated the sedimentation in the study area. The stepwise variations of the sediment provenance and composition of the Central Yellow Sea muddy sediments are of importance to understanding the formation of muddy deposit in the central Yellow Sea and the associated variations of marine environment since the middle Holocene. 相似文献
122.
电感耦合等离子体发射光谱法测定锑精矿中多种微量元素 总被引:3,自引:2,他引:1
建立了电感耦合等离子体发射光谱法(ICP-OES)测定锑精矿中10种微量元素Zn、Cd、Pb、Si、Mn、Fe、Mg、Ca、Cu、Ag的快速定量分析方法。探讨了锑精矿的溶样方法,发现采用氢溴酸挥锑后用浓酸溶解样品,稳定性较好。优化了仪器参数条件,对样品中各元素做加标回收试验。与原子吸收光谱法测定比较,方法检出限低,精密度(RSD,n=11)均小于6%,回收率为89.4%~108.0%,能满足进出口对锑精矿中杂质元素的检测要求。 相似文献
123.
Tinghua Ai Shu Ke Jingzhong Li 《International journal of geographical information science》2017,31(2):297-319
As a basic and significant operator in map generalization, polyline simplification needs to work across scales. Perkal’s ε-circle rolling approach, in which a circle with diameter ε is rolled on both sides of the polyline so that the small bend features can be detected and removed, is considered as one of the few scale-driven solutions. However, the envelope computation, which is a key part of this method, has been difficult to implement. Here, we present a computational method that implements Perkal’s proposal. To simulate the effects of a rolling circle, Delaunay triangulation is used to detect bend features and further to construct the envelope structure around a polyline. Then, different connection methods within the enveloping area are provided to output the abstracted result, and a strategy to determine the best connection method is explored. Experiments with real land-use polygon data are implemented, and comparison with other algorithms is discussed. In addition to the scale-specificity inherited from Perkal’s proposal, the results show that the proposed algorithm can preserve the main shape of the polyline and meet the area-maintaining constraint during large-scale change. This algorithm is also free from self-intersection. 相似文献
125.
吉林省石炭纪岩相古地理特征及沉积相模式 总被引:2,自引:0,他引:2
本文通过大量的实际资料分析对吉林省石炭纪沉积相进行了划分:早石炭世划分为两个相区,6个相带;晚石炭世划分为5个相区,8个相带,并建立了沉积相模式。 相似文献
126.
河南省县级综合气象业务平台的建设及应用 总被引:1,自引:0,他引:1
河南省气象局组织开发的以标准化、规范化、统一数据环境和信息网络为支撑,集气象综合观测、气象预警预报、公共气象服务、农业气象服务、一键式发布和业务管理为一体的"河南省县级综合气象业务平台",为县级综合气象业务的开展提供集约高效的工作平台,为加快基层气象业务现代化建设、全面推进县级气象机构综合改革提供坚实的支撑。平台采用集约化的数据环境和B/S架构,利用跨平台的Java语言开发,采用开源框架结构设计,平台的运维在省级信息中心,减轻了基层业务人员的运维工作量。 相似文献
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