Classification of stellar spectra with SVM based on within-class scatter and between-class scatter

Support Vector Machine (SVM) is a popular data mining technique, and it has been widely applied in astronomical tasks, especially in stellar spectra classification. Since SVM doesn’t take the data distribution into consideration, and therefore, its classification efficiencies can’t be greatly improved. Meanwhile, SVM ignores the internal information of the training dataset, such as the within-class structure and between-class structure. In view of this, we propose a new classification algorithm-SVM based on Within-Class Scatter and Between-Class Scatter (WBS-SVM) in this paper. WBS-SVM tries to find an optimal hyperplane to separate two classes. The difference is that it incorporates minimum within-class scatter and maximum between-class scatter in Linear Discriminant Analysis (LDA) into SVM. These two scatters represent the distributions of the training dataset, and the optimization of WBS-SVM ensures the samples in the same class are as close as possible and the samples in different classes are as far as possible. Experiments on the K-, F-, G-type stellar spectra from Sloan Digital Sky Survey (SDSS), Data Release 8 show that our proposed WBS-SVM can greatly improve the classification accuracies.     

基于区域监测站的BDS定轨策略分析

围绕影响轨道精度和实时性的5个要素（模糊度分类固定、测站数量、定轨弧长、太阳光压模型和多系统组合）展开研究,得出区域测站分布下的定轨优选策略。实验表明,选取中国区域27个均匀分布的地面区域监测站,利用72 h弧长观测数据,采用ECOM 5参数简化太阳光压摄动模型、BDS/GPS双系统联合定轨可达到较好的精度,其中GEO卫星轨道精度约291 cm,IGSO/MEO卫星轨道精度优于11 cm。若BDS单系统采用上述策略进行定轨,也可达到GEO卫星299 cm和IGSO/MEO卫星14.4 cm的近似等价定轨精度。     

Iron Regulation of Wetland Vegetation Performance Through Synchronous Effects on Phosphorus Acquisition Efficiency

Iron-rich groundwater flowing into wetlands is a worldwide environmental pollution phenomenon that is closely associated with the stability of wetland ecosystems. Combined with high phosphorus(P) loading from agricultural runoff, the prediction of the evolution of wetland vegetation affected by compound contamination is particularly urgent. We tested the effects of anaerobic iron-rich groundwater discharge in a freshwater marsh by simulating the effect of three levels of eutrophic water on native plants(Glyceria spiculosa(Fr. Schmidt.) Rosh.). The management of wetland vegetation with 1–20 mg/L Fe input is an efficient method to promote the growth of plants, which showed an optimum response under a 0.10 mg/L P surface water environment. Iron-rich groundwater strongly affects the changes in ecological niches of some wetland plant species and the dominant species. In addition, when the P concentration in a natural body of water is too high, the governance effect of eutrophication might not be as expected. Under iron-rich groundwater conditions, the δ~(13)C values of organs were more depleted, which can partially explain the differences in δ~(13)C in the soil profile. Conversely, the carbon isotope composition of soil organic carbon is indicative of past changes in vegetation. The results of our experiments confirm that iron-rich groundwater discharge has the potential to affect vegetation composition through toxicity modification in eutrophic environments.     

Effects of feeding time on complement component C7 expression in Pelteobagrus vachellii subject to bacterial challenge

Journal of Oceanology and Limnology - Shifting the feeding time for fish from daytime to nighttime could alter their digestive behavior, disturb their metabolism, and may affect immune-related...     

InSAR滑坡探测技术研究——以金沙江乌东德水电站段为例

采用3类InSAR产品和DEM数据开展金沙江流域乌东德水电站段的潜在滑坡探测,成功识别出多处已知和未知的滑坡点,并探测出滑坡体的形态及稳定性,提供了一种高效的大范围滑坡探测技术。同时采用小基线集InSAR技术对金坪子滑坡进行监测,不仅获得该滑坡的空间分区特征,也获取重点滑坡区的时间序列结果,并且与地面监测结果比较,精度达1.8 cm。展示了不同InSAR技术在不同尺度滑坡调查与监测中的应用特点。     

哈拉哈塘地区东河砂岩段-角砾岩段沉积模式探讨

塔北的哈拉哈塘地区是东河砂岩油气勘探的重点地区,该地区目前已发现并探明了东河塘和哈得4两个东河砂岩油气藏,油气储量丰富,显示出良好的勘探前景。基于哈拉哈塘地区东河砂岩段和角砾岩段的岩性段穿时沉积现象异常明显,根据层序地层学原理和方法对哈拉哈塘地区东河砂岩段一角砾岩段进行了重新分层和对比,在层序分层等时地层框架的基础上重新进行了东河砂岩段一角砾岩段沉积模式研究,弄清该地区地层分布规律、演化规律、砂体分布及储层分布规律对该地区的油气勘探具有重要指导意义。     

长江源区生态及灾害地质调查与防治对策

简述了长江源区自然地理和生态地质环境特征,分析了环境恶化的主要原因及防治对策。     

中国南方发现大型文石笋

中国南方大量石笋剖面研究表明,石笋矿物组成有方解石、文石、方解石-文石三种类型。石笋沉积纹(微)层结构构造特征大同小异,但是文石石笋的放射状纹(微)层构造更显著。文石石笋沉积生长的气候环境是滴水多而稳定,水温低、气温略高的冷、湿的洞穴气候条件。文石转变为方解石常保留文石的针状、柱状晶形,并存在于石笋沉积生长的始终。文石结构构造转化在常温或低温、常压或低压下自调整作用的成晶成岩环境进行,其强度取决于所在洞穴气候环境、滴水在石笋的渗流和石笋的含水度。转化作用不影响同位素分馏,石笋同时全面记录古气候环境信息。研究文石石笋对重建古气候环境、成岩成矿作用都有重要理论和实践意义。     

"九五"数字化地震前兆台站整体接入因特网的研究

介绍了如何将"九五"数字化前兆台站设备整体接人因特网,提供了一种非常简便、实用的整体接人方案.台站原来的构成模式没有改变,台网中心和台站熟悉的原工作方式得到了保留,实现了台站网络化的目标,使现有台网在因特网环境下能够正常运行.它能够与"十五"新建的前兆台网进行集成,便于整个台网的统一管理.     

怀念敬爱的赵九章所长

今年是我们敬爱的赵九章所长(原中国科学院地球物理研究所)诞辰100周年。抚今思昔,半个世纪前的情景,让我永记不忘。记得当我刚从学校毕业踏上工作岗位时,我的专业学习忽然从微观的原子世界(我在学校学的是金属物理专业)转变为要研究浩翰宇宙中的地球物理,这种转变使我感觉到自