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81.
在羌塘中部大沙河-果干加年山剖面展金岩群中发现珊瑚化石赫氏鲍斯维耳剌毛虫Chatetes(Boswellia)heritschi Sokolov,说明展金岩群中存在晚石炭世的生物时代证据。但是该化石并不是属于冈瓦纳冷水生物区的,而是来自温水环境的特提斯型生物区。在荣玛乡黑石山剖面中发现大量中二叠世 科化石,既出现典型的冈瓦纳相冷水生物,如Wannerophyllam 、Monodiexodina等,也存在大量暖水型的生物,如田氏朱森 Chusenella tieni Chen、散尔多希瓦格 Schwagerina sanerduoensis Nieet Song、假孙氏假纺锤 Pseudofusulina pseudosuni Sheng等。化石特征属于冈瓦纳相与特提斯相的混合类型。研究表明,羌塘中部的喀喇昆仑—龙木错—双湖一带是石炭纪、二叠纪冈瓦纳和特提斯生物混生区,不存在明显的生物大区界线。推测龙木错-双湖蛇绿岩带所代表的洋盆可能仅为特提斯南缘弧盆系统中的小盆地。 相似文献
82.
A GIS-implemented, deterministic approach for the automated spatial evaluation of geometrical and kinematical properties of
rock slope terrains is presented. Based on spatially distributed directional information on planar geological fabrics and
DEM-derived topographic attribute data, the internal geometry of rock slopes can be characterized on a grid cell basis. For
such computations, different approaches for the analysis and regionalization of available structural directional information
applicable in specific tectonic settings are demonstrated and implemented in a GIS environment. Simple kinematical testing
procedures based on feasibility criteria can be conducted on a pixel basis to determine which failure mechanisms are likely
to occur at particular terrain locations. In combination with hydraulic and strength data on geological discontinuities, scenario-based
rock slope stability evaluations can be performed. For conceptual investigations on rock slope failure processes, a GIS-based
specification tool for a 2-D distinct element code (UDEC) was designed to operate with the GIS-encoded spatially distributed
rock slope data. The concepts of the proposed methodology for rock slope hazard assessments are demonstrated at three different
test sites in Germany. 相似文献
83.
Atmospheric air temperature data from 92 stations in China’s radiosonde network were used to analyze changes in the freezing
level height (FLH), glacier snow line, and ice edge from 1958–2005 (48 years) and to examine the impact of these changes on the
cryosphere. In general, the FLH, glacier snow line, and ice edge exhibited latitudinal zonation, declining from south to north.
Trends in the FLH, glacier snow line, and ice edge showed spatial heterogeneity during the study period, with prevailing upward
trends. Temporally, the FLH, glacier snow line, and ice edge trends differed on various time scales. 相似文献
84.
Despite vigorous tidal and wind mixing, observations in an estuarine tidal inlet in the Wadden Sea show that during part of
the tidal cycle, vertical stratification and internal waves may still develop. Acoustic Doppler current profiler (ADCP) and
conductivity, temperature, depth observations, collected over the past 6 years at 13 h anchor stations (ASs), reveal that
these occur especially during slack tide, when there is little wind and large freshwater discharge from nearby Lake IJssel.
Measurements with a moored ADCP show that in the same tidal phase, strong cross-channel circulation develops, which may suddenly
reverse circulation sense due to passing density fronts. In the vertically stratified phase that follows after the front passage,
propagating mode-one solitary internal waves are observed. These are resonantly generated during decelerating tidal ebb currents
when the (shear) flow passes a transcritical regime (Froude number equal to 1). A combination of photographs (including one
from the International Space Station), bathymetric data, and ASs data leads to the discovery of yet another source of internal
waves in this area, produced during slackening tide by propagating lee waves that develop over a deep trench. We suggest that
both the cross-channel circulation as well as the (solitary) internal waves may locally be of importance for the (re)distribution
and transport of sediments and nutrients and may influence tidally averaged transports. 相似文献
85.
热带海气相互作用波及其不稳定性 总被引:8,自引:1,他引:8
本文利用一个简单的海气耦合模式,讨论了热带海洋和大气中Rossby波的相互作用。结果指出,海洋和大气中向西传播的Rossby波耦合后,不仅存在着向西传播的波动,而且还可以产生一类向东传的新波。这种向东传播的波动出现在波长较长的波段范围内,这个范围的大小受海气相互作用强度的制约。另外,波动可以出现不稳定性,向西和向东传的波均有不稳定现象发生,不稳定增长率也受海气相互作用强度的制约。最后,根据所得到的海气相互作用波,对ENSO现象作了一个可能的解释。 相似文献
86.
对国家级自动气象站供电系统深入研究,通过对蓄电池充放电进行细微控制,设计报警电路、寿命检测电路和远程监控上位机软件系统,实时监测蓄电池状态,对蓄电池长期处于浮充状态致使其寿命缩减的设计缺陷进行改进。该系统采用Freescale高性能处理器和以AD8210为核心的高边电流检测电路,实时对分流电阻的微电流进行检测,及时阻止危害蓄电池使用寿命的过充和过放,通过声光报警电路和数据通信电路将交流电断电报警、蓄电池电压、使用寿命和充电间隔等信息传送到Labview编写的上位机软件,提醒观测员及时处理,同时配合RTC时钟模块,每3个月自动对蓄电池进行充放电维护,不仅有效延长了蓄电池的使用寿命,还解决了蓄电池充放电维护问题,减少了国家站备份蓄电池每两年更换造成的资源浪费。 相似文献
87.
为了探讨琼东南盆地华光凹陷海底天然气水合物稳定带的分布规律,定量研究了静水压力、底水温度、地温梯度和气源组分对水合物稳定带的影响程度。在此基础上,分析了华光凹陷现今甲烷水合物稳定带的厚度分布。最后,综合各因素的历史演化过程,初步探讨了华光凹陷1.05 Ma BP以来天然气水合物稳定带的演化。结果表明:(1)气源组分和海底温度的变化对研究区内水合物稳定带的影响较大;水合物稳定带厚度与海底温度呈良好的线性负相关性。(2)水深超过600 m的海域具备形成天然气水合物的温压条件;超过600 m水深的海域水合物稳定带厚度大部分超过 100 m,其中西北部稳定带的最大厚度超过300 m,是有利的水合物勘探区。(3)华光凹陷1.05 Ma BP以来天然气水合物稳定带厚度经历了快速增厚–窄幅变化–快速减薄和恢复的过程。麻坑群与水合物稳定变化敏感区在空间上具有较好的叠合关系。结合前人的研究成果,推测其形成与天然气水合物的分解释放有关。 相似文献
88.
Feng He Haishen Wen Dahui Yu Jifang Li Bao Shi Caifang Chen Jiaren Zhang Guoxiong Jin Xiaoyan Chen Dan Shi Yanping Yang 《中国海洋大学学报(英文版)》2010,9(4):395-398
Follicle stimulating hormone β (FSHβ) of Japanese flounder (Paralichthys olivaceus) plays a key role in the regulation of gonadal development.This study aimed to investigate molecular genetic characteristics of the FSHβ gene and elucidate the effects of single nucleotide polymorphisms (SNPs) of FSHβ on reproductive traits in Japanese flounder.We used polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) and sequencing of the FSHβ gene in 60 individuals.We identified only an SNP (T/C) in the coding region of exon3 of FSHβ.The SNP (T/C) did not lead to amino acid changes at the position 340 bp of FSHβ gene.Statistical analysis showed that the SNP was significantly associated with testosterone (T) level and gonadosomatic index (GSI) (P0.05).Individuals with genotype TC of the SNP had significantly higher serum T levels and GSI (P0.05) than that of genotype CC.Therefore, FSHβ gene could be a useful molecular marker in selection for prominent reproductive trait in Japanese Flounder. 相似文献
89.
This paper reported the results of the determination of Ag, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sr and Zn in Common Chanterelles (Cantharellus cibarius) Fr. and surface soil layer (0-10 cm) underneath the fruiting bodies. Mushrooms and soils were collected from a lowland site in the Hel Peninsula (Baltic Sea coast) and a high mountain site in the Tatra Mountains. The trace elements were determined using validated method and inductively coupled plasma - atomic emission spectroscopy (ICP-AES). Common Chanterelles that emerged at sites poor in mineral nutrients podzols of the Hel Peninsula forests efficiently bioconcentrated several essential trace elements (K, P, Co, Cu, Mn, Na, Zn), while the abundance of those elements in carpophores was around half less compared to specimens from Zakopane region and which emerged in soils much richer in minerals. Common Chanterelles collected at two spatially distant background areas in Poland were only weakly contaminated with metals such as Ag, Cd, Hg and Pb. The maximum tolerable Cd and Pb contents of certain cultivated mushrooms are regulated in the European Union by law and these hazardous metals in C. cibarius were far below tolerance limits set. 相似文献
90.
The extraction of object features from massive unstructured point clouds with different local densities, especially in the presence of random noisy points, is not a trivial task even if that feature is a planar surface. Segmentation is the most important step in the feature extraction process. In practice, most segmentation approaches use geometrical information to segment the 3D point cloud. The features generally include the position of each point (X, Y and Z), locally estimated surface normals and residuals of best fitting surfaces; however, these features could be affected by noisy points and in consequence directly affect the segmentation results. Therefore, massive unstructured and noisy point clouds also lead to bad segmentation (over-segmentation, under-segmentation or no segmentation). While the RANSAC (random sample consensus) algorithm is effective in the presence of noise and outliers, it has two significant disadvantages, namely, its efficiency and the fact that the plane detected by RANSAC may not necessarily belong to the same object surface; that is, spurious surfaces may appear, especially in the case of parallel-gradual planar surfaces such as stairs. The innovative idea proposed in this paper is a modification for the RANSAC algorithm called Seq-NV-RANSAC. This algorithm checks the normal vector (NV) between the existing point clouds and the hypothesised RANSAC plane, which is created by three random points, under an intuitive threshold value. After extracting the first plane, this process is repeated sequentially (Seq) and automatically, until no planar surfaces can be extracted from the remaining points under the existing threshold value. This prevents the extraction of spurious surfaces, brings an improvement in quality to the computed attributes and increases the degree of automation of surface extraction. Thus the best fit is achieved for the real existing surfaces. 相似文献