正二十面体六边形全球离散格网编码运算

全球离散格网系统是指把地球表面按照一定规则离散分割成多分辨率层次结构的格网单元,广泛应用于海量多源空间数据的组织、管理和分析中。六边形全球离散格网具有优良的几何特性,非常适合于空间数据的处理,如何进一步提高六边形全球离散格网编码运算的效率仍是当前研究的重点。本文采用正二十面体施耐德投影四孔径六边形全球离散格网模型,基于六边形三轴坐标与编码的二进制数的对应关系构建四孔六边形的基础编码结构,将二十面体划分为32个基础六边形,并将之分为3种基础六边形剖分瓦片,在每个六边形剖分瓦片采用基础编码结构进行编码,建立了四孔六边形全球离散格网编码,同时设计了并实现了四孔六边形编码与六边形三轴坐标之间的快速转换,基于此构建了一种高效的四孔六边形全球离散格网编码运算方案,包括编码的算数运算、空间拓扑运算和邻域检索运算及跨面运算。与现有的六边形全球离散格网编码运算方案相比,本文的方案进一步提高了编码算数运算、空间拓扑运算和邻域检索运算的效率,编码加法运算是HLQT的2～3倍,邻域检索运算分别是HLQT的3～5倍和H3的2～3倍,且受格网编码层次的影响较小,编码的跨面邻域检索运算时间略高于面内的运算,可以为全...     

Effects of Seawater Acidification on Early Development of Clam Cyclina sinensis

Anthropogenic emission of atmospheric carbon dioxide(CO_2) has led to a rapid increase in atmospheric CO_2 concentration. Increasing atmospheric CO_2 can reduce seawater pH and carbonate ions, which may adversely affect the survival of the larvae of calcareous animals. Cyclina sinensis is a commercially and ecologically important species in several Asian countries. Living in coast shallow waters, this species has experienced the coastal environmental changes frequently throughout its life cycle. In this study, we simulated possible future seawater pH values including 8.2, 7.8 and 7.4 and examined the effects of ocean acidification on the early development of C. sinensis. Clam embryos were incubated for 48 h(2 d) in control and high-CO_2 seawater to compare embryogenesis, larval growth and swimming behavior. Fertilization rate was quite sensitive to pH, and moderate acidification could induce a significant decrease in fertilization rate. However, only extreme acidification could bring significant negative effect to hatching rate, body size, and average path velocity of trochophora. Moreover, with seawater acidification, C. sinensis needs much more time to reach the same developmental stage, which increases the risk of larva survival. Together with recent studies demonstrating negative impacts of high CO_2 on fertilization and larva swimming behavior, the results imply a future decrease of C. sinensis populations in oceans if its acclimation to the predicted environmental alteration does not occur.     

Morphological and molecular diagnoses of Polydora brevipalpa Zachs,1933(Annelida: Spionidae) from the shellfish along the coast of China

Shell-boring species Polydora brevipalpa Zachs, 1933 is redescribed based on morphological observations and molecular approach for future unambiguous identification. Genetic distance analyses showed that the interspecific polydorid variation(16.7%–25.6%) was at least 15 times higher than the intraspecific one(0.2%–0.9%) based on the cytochrome c oxidase subunit I(CO1) gene sequences of polydorids. However, 18 S rDNA variation pattern demonstrated a rather narrow barcoding gap, with the interspecific polydorid variation(0.5%–5.6%) being very close to the intraspecific one(0.0%–0.4%). As such, the CO1 gene exhibited better DNA barcode for identification of polydorids than the 18 S rDNA gene because of the su ciently large barcoding gaps. Analysis of molecular variance results based on CO1 gene sequences showed that most variations in sequences(97.79%) lay within groups of adult worms and egg capsules rather than between them. This indicated that egg capsules from Crassostrea gigas(Thunberg,1793) in Ningbo and Nantong were related to the adult worms from Patinopecten yessoensis(Jay, 1857) in Dalian, and both of them belonged to P. brevipalpa. This result was further supported by parsimony network analysis, which showed that egg capsules collected from dif ferent localities and adult worms shared a single haplotype. This study was the first to report both P. brevipalpa infestation on C. gigas and to utilise the known CO1 sequences of the adult polydorids to validate morphologically unidentified egg capsules or early larvae. P. brevipalpa was most possibly brought to Chinese waters through transportation of Pa. yessoensis brood stock from Japan.     

弹性波正演模拟中PML吸收边界条件的改进

在弹性波有限差分正演模拟中, 完全匹配层(PML) 吸收边界条件是使用广泛、吸收效果最好的吸收边界条件.在目前的两种PML实现方法中, 分裂形式的完全匹配层(SPML) 方法计算存储量大、编程实现复杂; 非分裂形式的完全匹配层(NPML) 方法计算效率低、计算过程复杂.针对传统PML吸收边界条件在实现过程中存在的问题, 推导出了一种简洁有效的非卷积实现的NPML吸收边界条件, 既不需要对场分量进行分裂, 也不需要做复杂的卷积运算.分析结果表明, 本文实现的NPML吸收边界条件不仅具有良好的吸收衰减性能, 而且计算方程简单, 编程实现容易, 占有内存更小.      

格网计算法在空间格局分析中的应用--以贵州景观空间格局分析为例

格网地图与格网计算都是基于空间坐标系统来描述、分析、虚拟区域地理现象的有效方法之一。在空间格局分析应用中具有广阔的前景。景观类型的格网地图不仅能反映它们的空间分布,还能反映它们各自占据的生态空间情况。同时,格网地图还能将景观的空间异质性定量化、空间化和图形可视化表达。在格网地图和格网分析法的基础上,可以利用空间自相关分析、半方差分析等空间统计分析方法对景观的空间格局作进一步的深入研究。     

自动气象站数据采集系统的传感器接口

自动气象站观测系统在气象领域中应用广泛,数据采集器是系统中的关键部件,改进了低功耗、多功能、多通道、智能化控制等性能.传感器接口包括DAC实现的可调恒压源和可调恒流源、稳压二极管实现的前端保护、多路模拟开关实现的通道控制和测量类型控制、精密线性光耦合器实现的隔离电路、DAC和仪表放大器实现的增益控制等硬件部件.设计单片机程序实现电路的各种控制及要求功能.经制板、调试,该数据采集器能正常运行.     

上海天文台佘山工作站夜天亮度的变化

使用1994—2007年在1．56m反射望远镜CCD照相机拍摄的资料，测定了上海天文台余山工作站夜天亮度的变化。由于上海城市的发展，佘山工作站的夜天亮度在V波段从每平方角秒约19mag变到15．8mag，也就是说，夜天亮度自1994年以来变亮了约20倍。国际上优良台站的夜天亮度在V波段等于或暗于21．5mag。上述夜天亮度是优良台站的200多倍。现在在佘山工作站使用1．56m反射望远镜对暗于V=14mag的星做精确测光已经很困难了。     

高海拔宇宙线观测站LHAASO概况

宇宙线发现百年以来,宇宙线起源仍然是一个谜.研究宇宙线起源主要在甚高能(VHE)伽马射线天文学和宇宙线物理学两个领域交叉展开.新一代高海拔宇宙线观测站(LHAASO)拥有高海拔、全天候和大规模优势,利用多种探测手段对宇宙线开展联合观测,大幅提升对伽马射线和宇宙线的鉴别能力.LHAASO将开展全天区伽马源扫描搜索以大量发现新伽马源,将获得30TeV以上伽马射线探测的最高灵敏度,将在宽达5个数量级的能量范围内精确测量宇宙线分成份能谱,为揭开宇宙线起源谜团给出重要判据.系统介绍了LHAASO的探测器结构、性能优势和科学目标.     

红外相机OASIS的偏振器设计

介绍为日本冈山天文台１．８８ｍ镜红外相机（ＯＡＳＩＳ）研制的红外偏振器．该偏振器与ＯＡＳＩＳ配备可实现～４．１′视场的近红外成像偏振观测．偏振器包括可旋转的消色差半波片和固定的致冷偏振片,通过旋转半波片对入射光的调制取得线偏振测量．实际观测给出ＪＨＫ波段的偏振效率分别为８６．３％、９７．０％和９７．５％．并给出了ＯＡＳＩＳ偏振观测与前人观测结果的比较     

分子外流源L1211中近红外HH天体的发现

报告分子外流源Ｌ１２１１ 中新发现的１２ 个近红外ＨＨ 天体．在Ｌ１２１１ 的～４’区域,取得了ＪＨＫ’宽带和Ｈ２ 　ｖ ＝ １０ 　Ｓ（１） 发射线窄带的近红外图像．分析表明,新探测到的许多红外源与浓密分子云物理成协,其中有２０ 多个源表现出典型的Ｔ Ｔａｕｒｉ 星、Ｈｅｒｂｉｇ Ａｅ／Ｂｅ星和原恒星的红外超．Ｌ１２１１ 中的ＩＲＡＳ点源没有被观测到,可能是更深地埋于分子云中．对红外观测和分子线观测消光估计的比较显示,小于２μｍ 的近红外观测还不足以揭示深埋于分子云的整个年轻星团．根据近红外ＨＨ 天体的形态分布和红外源性质,能进一步证认这些ＨＨ 天体的激发源．其结果表明,Ｌ１２１１ 分子云中具有多个红外源驱动的多个外流活动