Effects of Irregular Wave Groups on Pile Forces     

Yang Zhengji Zuo Qihua Senior Engineer  River  Harbour Department  Nanjing Hydraulic Research Institute  Nanjing Engineer  River  Harbour Department  Nanjing Hydraulic Research Institute  Nanjing 《中国海洋工程》1991,(2)

The wave forces on 1, 2 and 4 vertical circular piles under the action of several wave trains of the same wave parameters, such as Hs,Tp and Mo, but different wave group factor GF are measured in the laboratory. After comparing these forces, it may be concluded that the mean and significant wave forces are almost of no difference for the wave trains with different GF. When GF is larger, the one-tenth of the wave froce extreme is slightly increased and the maximum wave force is much larger than the ones with smaller GF, to which attention must be paid in engineering practice.  相似文献   

黑鲷(Acanthopagrus schlegeli)肿瘤坏死因子α cDNA的克隆及特征分析   总被引：1，自引：0，他引：1  

高春萍  蔡中华  宋林生  吴龙涛  池振明 《海洋与湖沼》2005,36(4):326-334

采用同源克隆的方法，从黑鲷中获得肿瘤坏死因子(TNFα)全长cDNA序列。该序列含1288个核苷酸，可编码253个氨基酸的TNF前体蛋白。它是一种跨膜蛋白，无糖基化位点和信号肽结构。黑鲷TNFα与其它鱼类的TNFα的相似性很高，占据进化上独立的分支；与哺乳类TNFα和TNFG源于共同的祖先。基因结构分析显示，该基因含有TNF家族pmfile和TNF家族的标签序列；在参与TNFα基因二硫键形成的两个半胱氨酸和TNFα三聚体形成的位点高度保守；空间结构模拟显示，它与哺乳类TNFα的空间结构相似，都是由两个β折叠片组成，每个折叠片包含5个反向平行的β链。表达研究结果表明，黑鲷TNFα在检测的各个组织中均为组成型表达，表现为在刺激与非刺激鱼体中，都可以检测到黑鲷TNFα的表达，但是其表达水平在不同组织中有很大差异。黑鲷TNFα在头肾、脾脏和鳃的表达量较高，而在心脏、肝脏、血液、肾脏和大脑中表达量较低。  相似文献   

Estimating the geostrophic velocity obtained by HF radar observations in the upstream area of the Kuroshio     

Ryoko Tokeshi  Kaoru Ichikawa  Satoshi Fujii  Kenji Sato  Shoichiro Kojima 《Journal of Oceanography》2007,63(4):711-720

A method to extract geostrophic current in the daily mean HF radar data in the Kuroshio upstream region is established by comparison with geostrophic velocity determined from the along-track altimetry data. The estimated Ekman current in the HF velocity is 1.2% (1.5%) and 48° (38°)-clockwise rotated with respect to the daily mean wind in (outside) the Kuroshio. Furthermore, additional temporal smoothing is found necessary to remove residual ageostrophic currents such as the inertial oscillation. After removal of the ageostrophic components, the HF geostrophic velocity agrees well with that from the altimetry data with rms difference 0.14 (0.12) m/s in (outside) the Kuroshio.  相似文献   

南海北部海区上层水体平均声速场的变化   总被引：1，自引：0，他引：1  

邱章  朱良生  许建林  宋运法 《海洋学报》2001,23(5):42-48

对所收集到的南海北部海区的温度、盐度和深度历史资料进行了声速的计算、统计与分析,结果表明该海区上层水体的平均声速场有较明显的年际变化:表层声速的平面分布显示出沿岸水与外海水强弱交替变化的特征,声速等值线的走向几乎与岸线平行,等声速线的值自近岸向外海增加,大陆架外缘海区声速的水平梯度较大;下层声速的分布以环流和水体共同作用的形式出现,50m层声速平面分布的趋势除冬季与表层稍为相似外,其余季节与表层有明显的差别,春、夏季节50m层声速自西向东增加,而秋季与其表层分布相反,自近岸向外海减小;声速的垂直分布受海水升温与降温的影响显著,春、夏季表层海水升温,海表声速最大,声速自海表随深度的增加而减小;秋、冬季表层附近水层降温,声速稍偏低,普遍出现正梯度现象,最大声速移至表层以下的水层,这个深度随季节的改变而改变,随海区的不同而不同.该海区的平均声速有年波动现象,表层波幅最大,随深度的增加波幅变小,至100m水层其波动的位相几乎与表层相反.  相似文献   

潮流沙脊的水力学问题探讨     

刘振夏  夏东兴 《海洋科学进展》1995,(4)

借用河流水力学顺直河道中有两个次生横向环流的假说来解释潮流沙脊的成因，水槽实验和实际观察也支持了这一观点．正是这一次生的纵轴横向环流（即螺旋流）将泥沙从沟槽带向脊顶，建造了大致与潮流方向平行的潮流沙脊．根据底质粒度成份和分布特点．可分为粗底质沙脊和细底质沙脊两类．前者组成物质偏粗，底质分布为脊细槽粗，后者组成物质偏细，底质分布为脊粗槽细．这是因为影响颗粒起动流速的主导因素不同，前者以重力为主，后者以颗粒间粘结力为主．它们都反映沟槽中流速大于脊顶处流速．  相似文献   

思林水电站通航建筑物高边坡稳定分析和评价     

徐力群  沈振中  俞凯加  吕军 《岩土力学》2008,29(Z1):42-46

应用ANSYS结构分析软件,模拟了思林水电站通航建筑物高边坡的地形、地质条件以及开挖的过程,建立边坡开挖的有限元计算分析模型,分析边坡在自然状态、分级开挖以及锚杆支护加固等工况下的应力、变形及其整体稳定性.定义单元的局部安全系数,得到了边坡开挖加固后稳定安全系数的分布.根据计算成果,指出现设计加固措施可以保证边坡稳定,无需增加其他工程措施.  相似文献   

甚高频电磁波多参数层析成像技术及其应用研究   总被引：1，自引：0，他引：1  

谭捍华  HUANG Jia-hui  黄家会  罗强  柳治国 《岩土力学》2008,29(12):3307-3310

电磁波速度或衰减层析成像技术单独用于岩溶勘察存在多解性缺陷,降低了应用的准确性.基于电阻率和相对介电常数直接反映溶洞与周围介质存在的电性差异,以电磁波速度和衰减层析成像理论为基础,提出了电阻率和相对介电常数层析成像理论,并应用于实例工程.通过对其电磁波速度、衰减、相对介电常数、电阻率4参数层析成像结果进行对比分析和钻探验证,证明了基于电磁波的电阻率和相对介电常数层析成像技术是可行的,形成了电磁波速度、衰减、相对介电常数、电阻率多参数层析成像综合分析方法,提高了电磁波层析成像技术探测溶洞及其充填情况的准确性.  相似文献   

Main Controlling Factors on Hydrocarbon Accumulation and Distribution in Marine Sedimentary Sequences in South China     

蔡立国  周雁  白振瑞 《中国地质大学学报(英文版)》2008,19(6):645-655

Multiple source rock assemblages were deposited in the sedimentary provinces in South China in geologic history,and some of them were destructed by and some survived against multiple tectonic movements.Therefore,multiple sources,mixed sources,and uneven distribution of sources occurred in the marine sedimentary basins in South China during the late stage of hydrocarbon pooling.Epidiagenesis of the marine carbonate reservoirs and its modification to reservoir poroperm characteristics determined the formation and the scale of natural gas pools.The exploration practices show that the large to medium gas fields mainly occur in areas with high-quality reservoirs.Detailed study of the paleo-oil accumulations and typical oil and gas reservoirs reveals that the basins experienced multiphase superimposition and modification,leading to the distribution of the Paleozoic paleo-oil accumulations and bitumen in the peripheral areas.The phenomenon that oil and gas production concentrates in the Sichuan basin indicates that the overall sealing conditions of a basin determine the oil/gas potentials and the scale of oil and gas production.This is a critical factor controlling the accumulation and distribution of gas in the marine sequences in South China.The early oil and gas pools in the Yangtze platform left billions of bitumen in the peripheral areas due to the destruction of seals.Since the Himalayan,"late-generation and late-accumulation" gas pools represented by the gas pools in the Sichuan (四川) basin were formed in the marine sedimentary sequences in South China as a result of the change of the sealing conditions.Current gas discoveries appear to be "paleo-generation and paleo-accumulation" gas pools but actually are "late-generation and late-accumulation" gas pools.These patterns of hydrocarbon pooling clearly depict themselves in western Sichuan basin and Weiyuan (威远)gas field.It is revealed that the gas pools in the Sichuan basin were mainly formed as a result of hydrocarbon phase change (thermal cracking of oil to gas),miscible migration,and dynamic equilibration since the Himalayan.A large number of gas pools were formed in the Himalayan and the gas pools in the marine sequences are characterized by late pooling; this kind of gas fields/pools are controlled by:(1) effectiveness of modification and superimposition of the marine basins,(2) effectiveness of the source rocks,(3) effectiveness of the overall preservation conditions,and (4) effectiveness of plays.  相似文献   

GPS单点测速的误差分析及精度评价 (英文)     

Fuhong Wang  Xiaohong Zhang  Jingsong Huang 《地球空间信息科学学报》2008,11(2):133-138

Error sources which decrease the accuracy of GPS in absolute velocity determination have been changed since SA was turned off. Firstly, quantities of all kinds of error sources that influence velocity determination are analyzed. The potential accuracy of GPS absolute velocity determination is derived from both theory and field GPS data simulation. After that, two tests were carried out to evaluate the performance of GPS absolute velocity determination in the case of a static and an airborne GPS receiver and INS （Inertial Navigation System） instrument in kinematic mode. In static mode, the receiver velocity has been estimated to be several mm/s with the carrier-phase derived Doppler measurements, and several cm/s with the receiver generated Doppler measurements. In kinematic mode, GPS absolute velocity estimates are compared with the synchronized measurements from the high accuracy INS. The root mean square statistics of the velocity discrepancies between GPS and INS come up to dm/s. Moreover, it has a strong correlation with the acceleration or jerk of the aircraft.  相似文献   

寨上金矿床控矿因素及成矿远景分析     

王增涛  赵天心  李春生  孙延光 《陕西地质》2008,26(1):8-16

文章综述了寨上金矿床的地质特征,分析了控矿因素,认为泥盆系和二叠系是矿区的矿源层,构造对成矿有决定性的作用,说明了断裂与成矿的关系,从成矿地质环境、工程控制程度和物化探异常三个方面分析了成矿远景,指出矿区有着较大的找矿潜力。  相似文献