地下爆炸各向同性源和补偿线性矢量偶极源共同作用对Rg波低谷点的影响

本文利用地震面波激发理论计算了两种震源不同相对强度、相对埋深及源时间函数情况下的Rg波频谱,研究地下爆炸中各向同性(ISO)源和补偿线性矢量偶极(CLVD)源共同激发的Rg波信号低谷点特性.结果表明,由于两种震源相对强度、相对埋深及源频谱的影响,混合信号低谷点频率与单一CLVD源激发的信号有很大差异,因此实际地下爆炸中...     

An internal-external optimized convolutional neural network for arbitrary orientated object detection from optical remote sensing images

Due to the bird's eye view of remote sensing sensors, the orientational information of an object is a key factor that has to be considered in object detection. ...     

Seasonal variation of airborne fungi of the Tiantishan Grottoes and Western Xia Museum,Wuwei, China

In this study, a systematic survey of cultural airborne fungi was carried out in the occurrence environments of wall paintings that are preserved in the Tiantishan Grottoes and the Western Xia Museum, China. A bio-aerosol sampler was used for sampling in four seasons in 2016. Culture-dependent and -independent methods were taken to acquire airborne fungal concentration and purified strains; by the extraction of genomic DNA, amplification of fungal ITS rRNA gene region, sequencing, and phylogenetic analysis, thereafter the fungal community composition and distribution characteristics of different study sites were clarified. We disclosure the main environmental factors which may be responsible for dynamic changes of airborne fungi at the sampling sites. The concentration of cultural airborne fungi was in a range from 13 to 1,576 CFU/m³, no significant difference between the two sites at the Tiantishan Grottoes, with obvious characteristics of seasonal variation, in winter and spring were higher than in summer and autumn. Also, there was a significant difference in fungal concentration between the inside and outside of the Western Xia Museum, the outside of the museum was far more than the inside of the museum in the four seasons, particularly in the winter. Eight fungal genera were detected, including Cladosporium, Penicillium, Alternaria, and Filobasidium as the dominant groups. The airborne fungal community structures of the Tiantishan Grottoes show a distinct characteristic of seasonal variation and spatial distribution. Relative humidity, temperature and seasonal rainfall influence airborne fungal distribution. Some of the isolated strains have the potential to cause biodeterioration of ancient wall paintings. This study provides supporting information for the pre-warning conservation of cultural relics that are preserved at local sites and inside museums.     

Local high-temperature phenomena within magnetic clouds

In this study,three methods were used to analyze 17 large-scale local high-temperature regions with durations exceeding 2 h within magnetic clouds(MCs)observed by advanced composition explorer from 1998 to 2008.Results show that five of these large-scale regions may have been caused by flare heating;seven of the regions may have been caused by nonuniform expansion when MCs propagated in the solar-terrestrial space;four large-scale high temperature regions may likely result from combined non-uniform expansion and flare heating;and only one large-scale local high-temperature region was not related to either flare heating nor non-uniform expansion.No evidence indicated that magnetic reconnection occurred or had occurred within the high-temperature regions.Based on our results,we infer that such local high-temperature phenomena within MCs are caused primarily as a result of flare heating and non-uniform expansion,either separately or jointly,and that magnetic reconnection plays only a minor role in the formation of high-temperature regions.     

湖北永兴洞降水对2015年厄尔尼诺的响应

通过对湖北永兴洞为期3年（2013年6月至2016年7月）的地表降水δ¹⁸O观测,发现该地点降水δ¹⁸O在2015夏季显著偏正。利用HYSPLIT后向轨迹方法对永兴洞降水水汽来源进行分析,结果表明在厄尔尼诺事件的影响下2015年夏季来自远源印度洋的水汽显著减少,而近源太平洋水汽相对增多,即降水δ¹⁸O因"环流效应"而偏正。本研究提供的观测证据表明永兴洞石笋δ¹⁸O记录在重建ENSO主导下的亚洲季风大气环流方面具有重要潜力。

     

柴达木盆地一里坪盐湖成盐卤水成分变化及其意义 ——来自LA-ICP-MS分析石盐流体包裹体组成的证据

一里坪盐湖是柴达木盆地一个以富锂卤水为主的干盐湖,蕴藏有丰富的卤水钾锂资源,目前对成矿过程中卤水的成分及其演变规律方面的研究较少.论文选取一里坪盐湖中部钻孔HC2105岩芯的石盐为主要对象,利用激光剥蚀-电感耦合等离子质谱法开展了单个石盐原生流体包裹体成分分析,探讨恢复了一里坪盐湖地区晚更新世以来成盐期的古卤水成分.结...     

山西下川遗址流水腰地点的细石叶工业

下川遗址流水腰地点（35°23'13"N,111°58'46"E）位于山西省垣曲县历山镇文堂村东北约1500 m处,海拔1554.9 m,发掘面积为12 m²,其中上文化层的年代约为17 cal.ka B.P.,石制品共计1182件。石制品原料以燧石为主,脉石英次之,还有一些硅质泥岩、玛瑙等。细石核以船形石核为主,兼有少量的半锥形石核。工具以刮削器、圆头刮削器、楔形析器为主,雕刻器、两端尖状器、两面尖状器很有特色。根据这些出土遗物的特征,该地点上文化层的文化性质为典型的以船形石核为主的细石叶文化,主要来源于下川遗址细石叶文化早期传统,同时受到来自吕梁山区和泥河湾盆地同期文化的影响。流水腰地点的发掘为研究山区旧-新石器时代过渡阶段的文化演变提供了新材料。

     

西北太平洋九州-帕劳海脊北部KPR12岩芯40万年来有机碳来源、埋藏特征及其环境响应

西北太平洋海陆相互作用强烈,受黑潮和亚洲大陆风尘输入影响显著,是研究海洋沉积物中有机碳埋藏与陆源输入、海洋初级生产力和海洋环境演化关系的理想靶区。本研究基于采自九州-帕劳海脊北部的重力活塞647 cm长的KPR12岩芯,分析了总有机碳（TOC）、总氮（TN）、有机碳稳定碳同位素组成（δ¹³C_TOC）、蛋白石（Opal）以及粒度等指标,初步探讨了近40万年来轨道尺度沉积有机碳的来源、埋藏特征及其影响机制。岩芯的TOC含量平均值为0.214%,呈冰期较高、间冰期较低的旋回特征。岩芯沉积物粒度的不同端元反映了研究区风尘输入大致呈冰期较高的趋势。岩芯的δ¹³C_TOC（-25.24‰~-21.04‰,平均值为-22.59‰）显示有机质以海源为主（约62%）,海源有机碳含量趋势与TOC的变化一致。研究区不同时期陆源物质的输入受风尘输送和黑潮的综合控制,黑潮增强可能对该区间冰期陆源有机碳贡献的升高有一定影响。岩芯中TOC与Opal含量的相关性分析表明,海洋初级生产力可能不是控制该岩芯有机碳含量变化的主要原因。冰期-间冰期旋回中的深层水通风条件、黑潮和北太平洋中层水的发育以及陆源细颗粒物质输入可能共同影响着本区沉积有机碳的降解与埋藏保存。

     

陕西地洞河高分辨率石笋记录的DO18季风增强事件

千年尺度事件的结构特征和区域响应是理解和认识冰期气候变化及动力机制的关键。本文基于陕西汉中宁强县地洞河一支长417 mm石笋DDH1的11个U-Th年代和417个氧同位素（δ¹⁸O）数据,重建了末次冰期（64.8~33.2 ka B.P.）亚洲季风演化历史。石笋δ¹⁸O记录在64.7±0.2 ka B.P.和59.3±0.1 ka B.P.快速负偏,分别指示了DO18事件的开始和H6事件的结束。在DO18事件结束过程,石笋δ¹⁸O记录在64.0~60.4 ka B.P.持续正偏,振幅达2.9 ‰,反应季风逐渐减弱,但未出现明显转型阶段。其总体形态与大西洋Cariaco盆地岩芯反射率、南极冰芯的记录较为一致,但是不同于格陵兰冰芯的记录。因地洞河所处青藏高原、秦岭叠加影响的区域,纬度和地形的双重影响使得其石笋δ¹⁸O记录较其他地区偏负,振荡幅度更大。因地形阻挡了高纬信号,使得低纬甚至南半球的信号突现出来,ITCZ的移动、南半球温度和水汽潜热的释放作用在这一区域尤为显著。