袭港热带气旋持续时间长期频率分析     

陶山山  宋佳玲  廖振焜  董胜 《中国海洋大学学报(自然科学版)》2020,(2):135-141

香港经常受到西北太平洋热带气旋的影响,对该地区热带气旋持续时间的研究有助于经济社会的稳定发展。按照气象和天文台警告信号,热带气旋分为不同的强度等级。建立热带气旋持续时间的Poisson-Weibull复合分布模型,相应获得持续时间重现值的求解公式,分别用于不同热带气旋分类下持续时间多年一遇重现值的计算中。基于1987-2016年袭港热带气旋数据的分析结果表明,Poisson-Weibull分布适用于不同的持续时间分类样本;强的热带气旋经常会伴随较长的持续时间,这将会对该地区造成更为严重的破坏,这可为防灾减灾提供参考。  相似文献   

International Silica Cycle Workshop held in Hangzhou     

TR&#;GUER Paul  RAN Lihu  CHAI Fei  CHEN Jianfang 《海洋学报(英文版)》2018,37(12):129-129

正Silicon is the second most abundant element on the planet Earth. Its electronic configuration is close to that of carbon, but the aqueous environment prevailing on our planet gives advantages to carbon compounds at the expenses of siliceous compounds.Silicified organisms, however, are everywhere on Earth, particularly in the marine realm where siliceous diatoms play a key role in the ocean biological carbon pump. Thus, a better understanding of the processes that control the silica cycle at global scale is crucial.  相似文献   

温度骤降对大黄鱼Larimichthys crocea鱼卵与仔鱼的影响          下载免费PDF全文

周孔霖  杜萍  寿鹿  廖一波  刘永叶  黄伟 《海洋学研究》2018,36(4):68-75

滨海电厂温排水停止排放以及季节更替、寒潮来袭等现象会引起海水温度降低,从而对鱼类等变温生物产生冷冲击效应。本研究通过模拟水温骤降情形,以孵化率、死亡率、畸形率等为指标,探讨了温度骤降对大黄鱼早期发育阶段(鱼卵和仔鱼)的冷冲击作用。研究发现,大黄鱼仔鱼(3日龄)对温度骤降的敏感性略高于鱼卵。在大黄鱼鱼卵和仔鱼的适温范围内,当水温由22 ℃骤降至19 ℃或16 ℃时,鱼卵的孵化率和死亡率无明显变化,而胚胎发育和仔鱼的生长发育均减缓,仔鱼的死亡率提高;水温超出适温范围,由22 ℃骤降至13 ℃或10 ℃时,对鱼卵和仔鱼造成致命的冷冲击伤害,48 h累积死亡率分别为84.6%~100%和72.1%~98.2%。由此推测:当水温骤降超出适温范围后,大黄鱼的早期发育阶段遭受致命的冷冲击伤害,从而影响种群补充和年龄结构。  相似文献   

Soil nutrients in relation to vertical roots distribution in the riparian zone of Three Gorges Reservoir,China     

Rong-hua Zhong  Jin-ming Hu  Yu-hai Bao  Fei Wang  Xiu-bin He 《山地科学学报》2018,15(7):1498-1509

Since the impoundment of the Three Gorges Reservoir (TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts on soil nutrients in the water level fluctuation zone of TGR. Roots of four predominant herbaceous plants in the study area, specifically, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, and their corresponding relation with soil nutrient contents were investigated. Root surface area density was determined with WinRHIZO, and the relationships of root distribution with soil depths and soil nutrient contents were studied. The results indicates that most roots are distributed in the top soil layer of 0–10 cm. Estimated root surface area density for the selected grass species ranges from 0.16 to 13.44 cm2/cm3, and decreases exponentially with an increase in soil depth. Soil organic matter and total nitrogen contents are significantly lower on bare control area than the corresponding values on the grasslands. Total nutrient contents on grasslands of C. dactylon and H. compressa are higher than those of other grass areas. Root length density and root surface area density are significantly correlated with soil organic matter and total nitrogen content for the four grasslands. The present results suggests that plant roots have significant effects on the distribution of soil nutrients in soil profiles in the riparian zone along the TGR. Nevertheless, additional investigations are needed to reveal the specific interactions between plant roots distribution, soil nutrients and water level fluctuations.  相似文献   

两种造礁石珊瑚对海水酸化和溶解有机碳加富的响应*     

郭亚娟  周伟华  袁翔城  廖健祖  江雷  黄晖 《热带海洋学报》2018,37(1):57-63

文章选择鹿回头近岸海域常见的板叶角蜂巢珊瑚(Favites complanata)和十字牡丹珊瑚(Pavona decussata)为研究对象, 采用室内连续培养的方法, 探究两种不同造礁石珊瑚对酸化和溶解有机碳(DOC)加富的响应。结果表明: 酸化(pH 7.6)并不会影响两种珊瑚的钙化速率和生长速率; 但DOC加富(524.03±78.42μmol•L^-1)使两种珊瑚的钙化速率分别降低67%和47%、生长速率降低59%和40%。当二者共同作用时, 两种珊瑚的钙化速率降低30%和11%、生长速率降低46%和59%, 大多没有DOC单独作用时强烈, 表现出一定的拮抗作用。两种珊瑚共生虫黄藻叶绿素荧光指数(F_v/F_m)均升高后降低, 板叶角蜂巢珊瑚F_v/F_m最先降低。实验表明, 这两种珊瑚虽然对海洋酸化的敏感度不高, 但是对有机物加富有不同的响应, 板叶角蜂巢珊瑚更为敏感, 可能导致这两种珊瑚在未来环境变化中有不同命运。  相似文献   

多时相Landsat影像的平原河网区不透水面信息提取方法与应用     

周峰  廖钰冰  李娜 《测绘通报》2020,(1):94

不透水面是衡量城市生态环境的重要指标，针对平原河网区不透水面与水体、裸土等地物较难区分的问题，以苏北里下河平原快速城镇化区为研究对象，利用多时相Landsat影像为数据源，基于像元光谱特征及其季节性变化分析，构建了基于时序NDWI、NDVI和NDBI的决策树模型，并利用GIS空间分析技术对不透水面的时空变化特征进行了分析。结果表明：多时相光谱信息可有效改善水体、裸土和稀疏植被等像元与不透水面的混分，2005年和2016年的不透水面分类总体精度和Kappa系数均在0.85以上，合理反映了不透水面以向东和向南扩张为主的趋势特征，年均扩张速度约为6.7 km²。研究成果为该区城镇化下的生态环境效应研究提供数据基础，同时可为其他平原河网区不透水面信息提供借鉴和参考。  相似文献   

多视密集匹配并行传播GPU-PatchMatch算法     

邓非  颜青松  肖腾 《测绘学报》2020,49(2):181-190

针对多视密集匹配的效率较低的问题,提出了GPU-PatchMatch多视密集匹配算法。该算法使用GPU提高PatchMatch的计算效率;同时充分利用稀疏场景信息,对深度信息进行规则初始化;为提高传播效率,使用了金字塔红黑板并行传播深度信息。最后在DTU、Strecha和Vaihigen数据集上进行了试验,并与常用的多视密集匹配算法进行对比。试验结果表明,本文算法在重建效率上有较大提高,与CPU算法(PMVS、MVE、OpenMVS)相比有7倍以上提升,与GPU算法相比也有2.5倍以上提升,表明本文算法的有效性。  相似文献   

A hierarchical indexing strategy for optimizing Apache Spark with HDFS to efficiently query big geospatial raster data     

Fei Hu  Yongyao Jiang  Yun Li  Weiwei Song  Daniel Q. Duffy 《International Journal of Digital Earth》2020,13(3):410-428

ABSTRACT

Earth observations and model simulations are generating big multidimensional array-based raster data. However, it is difficult to efficiently query these big raster data due to the inconsistency among the geospatial raster data model, distributed physical data storage model, and the data pipeline in distributed computing frameworks. To efficiently process big geospatial data, this paper proposes a three-layer hierarchical indexing strategy to optimize Apache Spark with Hadoop Distributed File System (HDFS) from the following aspects: (1) improve I/O efficiency by adopting the chunking data structure; (2) keep the workload balance and high data locality by building the global index (k-d tree); (3) enable Spark and HDFS to natively support geospatial raster data formats (e.g., HDF4, NetCDF4, GeoTiff) by building the local index (hash table); (4) index the in-memory data to further improve geospatial data queries; (5) develop a data repartition strategy to tune the query parallelism while keeping high data locality. The above strategies are implemented by developing the customized RDDs, and evaluated by comparing the performance with that of Spark SQL and SciSpark. The proposed indexing strategy can be applied to other distributed frameworks or cloud-based computing systems to natively support big geospatial data query with high efficiency.  相似文献   

黔中—渝南铝土矿含矿岩系微量元素区域分布特征及物质来源探讨          下载免费PDF全文

刘平  韩忠华  廖友常  聂坤 《贵州地质》2020,37(1):1-13

黔中—渝南成矿带石炭纪铝土矿含矿岩系,分别形成于修文、息烽—遵义和黔北—渝南三个沉积区,大多数铝土矿属产于碳酸盐岩侵蚀面上的、少数为产于泥页岩侵蚀面上的硬水铝石沉积型铝土矿床。修文沉积区铝土矿中Zr、RE2O3含量最多,息烽—遵义沉积区铝土矿中Ga含量最多,黔北—渝南沉积区Li含量最多,各有特色。修文沉积区铝土矿含矿岩系的母岩,是其下伏寒武系碳酸盐岩与下奥陶统页岩、灰岩、白云岩;息烽—遵义沉积区含矿岩系的母岩为下伏下奥陶统页岩、灰岩及白云岩;黔北—渝南沉积区含矿岩系的母岩,是下伏下志留统泥、页岩和上石炭统石灰岩。碳酸盐岩中Al2O3与稳定的微量元素含量甚少,要演变成大面积铝土矿,必须要配以足够的含Al2O3和微量元素较多的泥、页岩,才可能满足形成大规模铝土矿的物质需求。  相似文献   

蛭龙活血通瘀胶囊及其拆方对AS大鼠ET-1、NO的影响          下载免费PDF全文

郑利珠  张诗意  廖慧玲 《应用海洋学学报》2020,36(12):139

目的：观察蛭龙活血通瘀胶囊及其拆方对动脉粥样硬化（AS）大鼠内皮素（ET）-1和一氧化氮（NO）的影响,并探讨其组方的合理性。方法：随机将110只健康雄性SD大鼠分为11组,分别为空白组、模型组、阿托伐他汀组、全方组和拆方1~7组,每组各10只,除空白组外其余各组均制备AS大鼠模型。阿托伐他汀组大鼠予以阿托伐他汀钙片干预,全方组予以黄芪、桂枝、大血藤、地龙、水蛭干预,拆方1组予以黄芪、桂枝、大血藤干预,拆方2组予以黄芪、地龙、水蛭干预,拆方3组予以黄芪干预,拆方4组予以桂枝、地龙干预,拆方5组予以桂枝、水蛭干预,拆方6组予以大血藤、地龙干预,拆方7组予以大血藤、水蛭干预,于实验第120天后检测各组大鼠治疗前后的血清ET- 1、NO水平。结果：蛭龙活血通瘀胶囊全方组较拆方组降低血清ET-1浓度和提高血清NO浓度的作用更为明显,诸药中影响大鼠血清ET-1、NO含量最显著的是黄芪。结论：蛭龙活血通瘀胶囊全方组中多种药味合用后,对降低AS大鼠血清ET-1和提高NO含量有明显的协同作用,方中多种药物均可保护内皮功能,且影响大鼠血清ET-1、NO含量最显著的药味是黄芪。  相似文献