大洋钻探与冲绳海槽地质

本文简要回顾大洋钻探计划实施十余年来所取得的成果，评述了西太平洋边缘海盆的研究概况，提出东海大陆边缘的重大地质问题是陆缘的构造演化历史和动力学过程，弧后扩张中心的热液成矿作用以及海洋沉积层序记录的古气候和古海洋环境变化，指出矿物－地球化学在大洋钻探研究中的重要性。     

New Maikhanellid Shells and Siphogonuchitid Spicule Bundles from the Cambrian Fortunian Stage of South China

Maikhanellids are a distinct group of Cambrian Fortunian small shelly fossils by the cap-shaped profiles and scaly shell ornamentation. According to the individual shell shape and ornamentation feature types of 50 maikhanellids fossils which were collected from Xixiang botia, we confirmed the family Maikhanellidae content of six genera, which are Maikhanella, Ramenta, Purella, Ramentoides, Yunnannopleura and Mediata. Unlike the halkieriid animals whose shells and spicules are articulated on different body parts, maikhanellids were presumably yielded by siphogonuchitid spicules penetrating the intermediate matrix (the "spicule shell" hypothesis), and this is the reason that some researchers treated maikhanellids and co-occurring siphogonuchitids as synonyms. The affinities of Maikhanellids and siphogonuchitids remain debatable. Here, we report three dimensionally phosphatized maikhanellid shells and siphogonuchitid spicule bundles from the Cambrian Fortunian small shell faunas of South China. They differ from all the previously reported maikhanellids and siphogonuchitids, and may represent new types. The intact and smooth surface underneath the partially preserved scales of the shells challenges the "spicule-shell" hypothesis. The present siphogonuchitid spicules differ from the maikhanellid scales in size, morphology, and .arrangement pattern, thus the spicules might not be derived from the shells. Whether the shells and spicule bundles were articulated on different body parts of the same animals remains unknown.     

Spatio-temporal analysis of the geographical centroids for three major crops in China from 1949 to 2014

Spatial distribution changes in major crops can reveal important information about cropping systems. Here, a new centroid method that applies physics and mathematics to spatial pattern analysis in agriculture is proposed to quantitatively describe the historical centroids of rice, maize and wheat in China from 1949 to 2014. The geographical centroids of the rice area moved 413.39 km in a 34.32° northeasterly (latitude 3.08°N, longitude 2.10°E) direction at a speed of 6.36 km/year from central Hunan province to Hubei province, while the geographical centroids of rice production moved 509.26 km in the direction of 45.44° northeasterly (latitude 3.22°N, longitude 3.27°E) at a speed of 7.83 km/year from central Hunan province to Henan province. The geographical centroids of the maize area and production moved 307.15 km in the direction of 34.33° northeasterly (latitude 2.29°N, longitude 1.56°E) and 308.16 km in the direction of 30.79° northeasterly (latitude 2.39°N, longitude 1.42°E), respectively. However, the geographical centroids of the wheat area and production were randomly distributed along the border of Shanxi and Henan provinces. We divided the wheat into spring wheat and winter wheat and found that the geographical centroids of the spring wheat area and production were distributed within Inner Mongolia, while the geographical centroids of winter wheat were distributed in Shanxi and Henan provinces. We found that the hotspots of crop cultivation area and production do not always change concordantly at a larger, regional scale, suggesting that the changing amplitude and rate of each crops’ yield differ between different regions in China. Thus, relevant adaptation measures should be taken at a regional level to prevent production damage in those with increasing area but decreasing production.     

基于Sentinel-1雷达影像的成都市地面沉降InSAR监测分析

利用2017-03~2018-03共30景Sentinel-1A SAR数据,分别采用PSI和SBAS技术获取成都市主城区地面形变分布信息,结合地面水准资料对InSAR结果进行精度评估,并初步分析地面沉降的原因。结果表明,成都市大部分区域稳定,平均形变速率主要集中在-5~5 mm/a;地面沉降主要位于一环线以外地区,地铁5、6号线主要站点及周边不均匀沉降明显,最大沉降速率达到20 mm/a;在成华区和锦江区等部分新建城区有不同程度的地面沉降,速率为5~15 mm/a,PSI和SBAS结果相关性较高。     

高原复杂地理参数对雷电活动的影响分析

雷电活动参数作为反映区域雷电活动特征的重要指标,地形对其影响不容忽视。利用2014—2018年青海省地闪数据、数字地形高程数据以及HWSD土壤数据集,定量分析海拔、坡度、坡向以及土壤电阻率对青海省地闪分布特征的影响。结果表明：（1） 青海省地闪主要集中在海拔3150~4850 m、坡度0~35°的地区,其中东北坡向地闪次数最多,东南坡向地闪次数最少,地闪对应的土壤电阻率主要集中于100 Ω·m。（2） 地闪密度随海拔的升高先增大后减小,随坡度的增大而减小;地闪平均强度随海拔的升高先减小后增大,随坡度的增大而增大。（3） 选取92°27′00″~97°44′24″E、31°40′48″~34°16′48″N地闪活跃区域,对其1 km×1 km网格内地闪数据与地理参量平均值进行相关性分析,所选区域内地闪密度与平均海拔呈正相关关系,与平均坡度呈负相关关系;而地闪强度与平均海拔呈负相关关系,与平均坡度呈正相关关系。     

权重平衡有向网络下分布式约束优化的连续时间算法设计

本文研究权重平衡有向网络下分布式约束优化问题的求解,其中网络的全局目标函数是由每个智能体的局部目标函数的和构成,全局的约束是由每个智能体的局部约束的交构成.为了分布式求解该问题的最优解,首先引入智能体的局部共轭函数将其转换为Fenchel对偶问题.其次,从Fenchel对偶问题出发,提出一类基于奇异摄动系统的分布式连续时间算法.在局部目标函数和其梯度分别满足强凸和Lipschitz（李普希兹）连续的情况下,结合凸分析方法和Lyapunov（李雅普诺夫）稳定性理论,结果表明所提算法能够获得原问题和对偶问题的最优值.最后,数值仿真进一步验证了所提算法的有效性.     

Cell contact-dependent lethal effect of the dinoflagellate Heterocapsa circularisquama on phytoplankton–phytoplankton interactions

We used bi-algal culture experiments to investigate and verify the roles of growth interaction between Heterocapsa circularisquama and Prorocentrum dentatum in monospecific bloom formation. Growth of H. circularisquama was slightly inhibited when inoculated at 10² cells mL^–1 along with P. dentatum at 10⁴ cells mL^–1. In other combinations of inoculation densities, P. dentatum density rapidly decreased to extremely low levels in the presence of H. circularisquama. We used a mathematical model to simulate growth and interactions of H. circularisquama and P. dentatum in bi-algal cultures. The model indicates that one species will always inhibit the growth of the other and that the relative initial cell densities of the species are critical in determining the outcome. When cultured together under conditions without cell contact, growth of H. circularisquama and P. dentatum was not inhibited. As with P. dentatum, the growth of Heterosigma akashiwo and Skeletonema costatum was inhibited in intact cell suspensions with H. circularisquama, but a nontoxic species, Heterocapsa triquetra, did not affect the growth of P. dentatum or the other species. Similarly, cell suspensions of H. circularisquama showed hemolytic activity toward rabbit erythrocytes, but those of H. triquetra did not. In addition, the cell-free supernatant of H. circularisquama cultures showed no significant hemolytic activity. These results suggest that H. circularisquama causes lethality in P. dentatum by direct cell contact in which live-cell-mediated hemolytic activity might be a contributing factor.     

绿洲生态环境动态调控模型及系统概念设计应用

绿洲是荒漠中的特殊景观 ,在干旱、半干旱地理系统中有着重要的生态意义 ,是该系统中物质、能量和信息交流的主要界面。绿洲的生态环境脆弱 ,随着人类活动的加剧 ,绿洲生态系统的稳定性 ,将面临更加严峻的考验。利用先进的空间信息技术 (包括遥感和 GIS) ,可以建立绿洲生态环境动态调控系统 ,使之服务于绿洲的稳定、可持续发展。本文依据水资源的供需平衡原理和水资源利用与生态环境之间的耦合关系对基于遥感 (RS)和 GIS的绿洲生态环境动态调控的模型进行了概念设计,并在此基础上讨论了绿洲生态环境动态调控系统的设计。     

华北高速天津段公路气象数据质量控制分析

应用缺测分析、气候学界限值检查、历史极值检查、时间一致性检查、要素一致性检查和利用要素时间曲线人工检查等方法,对华北高速公路天津段公路自动气象站的能见度、相对湿度、气温、地温、风速等气象要素的数据质量进行分析,通过分析发现由于仪器故障造成数据缺测及在一定时间内恒定不变或变率太小是自动气象站存在的主要问题。在极少数情况下,存在超过界限值的错误数据;历史极值检查、时间一致性检查和要素时间曲线人工检查等方法对可疑数据错误检出率不高,现有检查域值还需要不断完善。