波浪作用下斜坡上单桩周围海床孔隙水压力响应特性试验研究

单桩基础周围斜坡海床中的波致孔隙水压力响应与纯斜坡海床存在较大差异。为了解不同波高、波周期条件下,单桩基础周围波浪传播变形及其对斜坡海床孔压振荡响应的影响,在波浪水槽末端铺设了长6 m、坡度1∶16的斜坡砂床进行试验。通过改变桩身位置和波浪参数,测量斜坡段各处波面形态,采集单桩周围孔隙水压力,分析了桩身位置及波浪参数对斜坡海床孔压响应的影响。结果表明：相同入射波条件下,随距坡脚水平距离增加,波高、近底流速和桩周孔隙水压力幅值都随之增大;桩周孔隙水压力幅值分布规律为：桩前孔压幅值明显大于桩侧与桩后孔压幅值。当Keulegan-Carpenter数大于6时,随着波高和波周期增大,马蹄涡产生的负压区使得桩侧海床孔隙水压力与纯斜坡海床孔隙水压力差值迅速增加。     

中小地震震源参数的求解及其相似关系

根据广东数字地震台网记录的区域性地震记录,利用遗传算法采用由"三段几何衰减模型"拟合得到的广东地区的衰减模型,得到广东地区Q值与频率的关系(Q(f)=454 8f0 37),由此衰减模型反演得到各台站的场地响应,最终得到72个中小地震的震源参数;并研究了广东地区震源参数的特征及其相似关系。这些地震的地震矩在1012N·m与1014N·m之间,求出与地方震震级之间的相似关系;该地区中小地震的应力降在0 02到3 2MPa之间,未显示与地震的规模(地震矩)有明显的依赖关系。     

MODIS影像的大气校正及在太湖蓝藻监测中的应用

MODIS 数据有免费、波段丰富、时间分辨率高等优点,是进行太湖蓝藻监测的重要数据源,由于MODIS传感器接收的是地物反射太阳辐射的信号,太阳辐射与地球大气的相互作用会引起传感器接收到的信号失真,为了提高利用MODIS数据监测太湖蓝藻的精度,必须对其进行大气校正.本文介绍了FIAASH大气校正模型的基本原理,并对2007年4月25日MODIS数据的前七个波段进行试验,对比分析了影像大气校正前后的NDVI值以检测大气校正的效果;分析表明,大气校正前后NDVI的变化趋势基本上相同,但大气校正后的NDVI动态范围更大,校正后NDVI的平均值和标准差增大,大气校正在一定程度上有效地降低了大气对遥感影像的影响,达到了增强信息的目的;最后,利用大气校正获取的地表真实反射率数据的第二波段与第一波段的比值,运用阈值法提取蓝藻信息,经试验当阈值为1.9时提取出来的蓝藻分布图基本上与实际相符.利用MODIS影像可以快速、及时地监测蓝藻爆发的位置及爆发程度.     

井下地震计的P波接收函数正演计算及其稳定性研究——以首都圈地区为例

井下地震计波形记录的P波垂向分量存在频谱极小（spectrum null）现象,导致接收函数的结果不稳定.本文以首都圈地区为例,基于平面波入射的传播矩阵理论,发展了用于计算井下地震计的接收函数正演方法.在此基础上,分析了井下地震计波形垂向分量频谱极小现象,研究其对接收函数稳定性的影响.结果表明,井下地震计波形记录垂向分量的频谱极小开始出现的频率和地震计的埋深相关.该现象可造成反卷积提取的接收函数不稳定,且不稳定情况出现在频谱极小附近的频段,可通过选择合适的高斯因子压制其对接收函数的影响.     

常Q滞弹性介质地震波动数值模拟——时域本构优化逼近

在地震波动模拟中计入常Q滞弹性阻尼,可有效降低模拟波形的误差.就时域有限差分和有限元模拟而言,常基于广义标准线性体建立阻尼介质的时域本构逼近.广义标准线性体由若干标准线性体并联得到,增加标准线性体个数能有效提高模拟精度,但计算量及计算存储将成倍增长.目前尚未有普适的标准线性体个数优化取值方案.本文基于广义标准线性体参数的非线性优化拟合方法,详细分析了时域本构逼近误差的影响因素,清楚揭示了逼近误差仅取决于频带宽度,与频带上下限取值无关这一特性,阐明了构建具有普适性标准线性体个数优化取值方案的可行性.论证了波形模拟精度主要取决于波传播距离与模拟波长的比值以及标准线性体的个数取值.综合考虑上述两个控制因素,结合在波动正反演问题中广为采纳的波形时频误差衡量准则,对不同Q值介质给出了标准线性体个数优化取值表.进一步,本文提出采用不同个数标准线性体以近似不同Q值的阻尼介质时域本构,解决了以往波动数值模拟中统一采用相同个数标准线性体而导致的计算量及计算存储浪费或模拟精度低下等问题,并基于数值实验验证了这一方法的精度.本文工作对推进滞弹性介质波动数值模拟及其在全波形反演问题中的应用具有理论价值和实践意义.     

中华蛸寄生丛集球虫(顶复亚门:丛集球虫科)新种的形态学与分子生物学研究

丛集球虫(顶复亚门:类锥体纲:丛集球虫科)是头足类消化道中一类常见寄生虫,在福建连江海域以及浙江南麂岛周边海域采捕到的中华蛸(Octopussinensis)盲囊及肠组织内发现一丛集球虫新种,命名为多刺丛集球虫Aggregata octaculeata sp. nov.。光学显微镜和扫描电镜下观察发现,中华蛸体内的多刺丛集球虫存在配子生殖阶段和孢子生殖阶段,其中,孢子生殖阶段成熟卵囊呈近球形或椭球形,长径653.6—806.5μm,短径588.1—787.1μm。孢子囊为卵球形或椭球形,长径22.4—26.1μm,短径20.5—24.6μm,孢子囊壁为双层,外部光滑,内层多刺。孢子囊内子孢子呈卷曲状,数目范围8—13个,子孢子长度为22.2—28.6μm,宽度为3.0—5.0μm。基于18SrRNA基因构建的系统发育树进一步证实该物种隶属于丛集球虫属,并高度支持了属内[(中华丛集球虫A. sinensis+A. octopiana)+A. eberthi]+多刺丛集球虫A. octaculeata的系统发生关系。     

几种不同矩阵算法的遥感图像几何精纠正效果比较

分别采用Gauss、Householder及Givens三种变换形式进行遥感图像几何精纠正试验，并将试验结果与商业遥感软件PCI的纠正结果进行比较。结果表明，Givens算法在一至五次多项式纠正中，其总体精度优于其它算法。     

PRESENT KINEMATICS CHARACTERISTICS OF THE NORTHERN YUMUSHAN ACTIVE FAULT AND ITS RESPONSE TO THE NORTHEASTWARD GROWTH OF THE TIBETAN PLATEAU

Qilian Shan and Hexi Corridor, located in the north of Tibetan plateau, are the margin of Tibetan plateau's tectonic deformation and pushing. Its internal deformations and activities can greatly conserve the extension process and characteristics of the Plateau. The research of Qilian Shan and Hexi Corridor consequentially plays a significant role in understanding tectonic deformation mechanism of Tibetan plateau. The northern Yumushan Fault, located in the middle of the northern Qilian Shan thrust belt, is a significant component of Qilian Shan thrust belt which divides Yumushan and intramontane basins in Hexi Corridor. Carrying out the research of Yumushan Fault will help explain the kinematics characteristics of the northern Yumushan active fault and its response to the northeastward growth of the Tibetan plateau.Because of limited technology conditions of the time, different research emphases and some other reasons, previous research results differ dramatically. This paper summarizes the last 20 years researches from the perspectives of fault slip rates, paleao-earthquake characteristics and tectonic deformation. Using aerial-photo morphological analysis, field investigation, optical simulated luminescence(OSL)dating of alluvial surfaces and topographic profiles, we calculate the vertical slip rate and strike-slip rate at the typical site in the northern Yumushan Fault, which is(0.55±0.15)mm/a and(0.95±0.11), respectively. On the controversial problems, namely "the Luotuo(Camel)city scarp" and the 180 A.D. Biaoshi earthquake, we use aerial-photo analysis, particular field investigation and typical profile dating. We concluded that "Luotuo city scarp" is the ruin of ancient diversion works rather than the fault scarp of the 180 A.D. Biaoshi earthquake. Combining the topographic profiles of the mountain range with fault characteristics, we believe Yumu Shan is a part of Qilian Shan. The uplift of Yumu Shan is the result of Qilian Shan and Yumu Shan itself pushing northwards. Topographic profile along the crest of the Yumu Shan illustrates the decrease from its center to the tips, which is similar to the vertical slip rates and the height of fault scarp. These show that Yumu Shan is controlled by fault extension and grows laterally and vertically. At present, fault activities are still concentrated near the north foot of Yumu Shan, and the mountain ranges continue to rise since late Cenozoic.     

A BRIEF INTRODUCTION TO THE NEW METHOD FOR RIVER PROFILE ANALYSIS: Integral Approach

The topography and geomorphology of active orogens result from the interaction of tectonics and climate. In most orogens, a fluvial channel is most sensitive to the coupling between tectonics, lithology, and climate. Meanwhile, the related signals have been recorded by both the drainage geometry and channel longitudinal profile. Thus, how to extract tectonic information from fluvial channels has been a focused issue in geologic and geomorphologic studies. The well known stream-power river incision model bridges the gap between tectonic uplift, river incision and channel profile change, making it possible to retrieve rock uplift pattern from river profiles. In this model, the river incision rate depends on the rock erodibility, contributing drainage area and river gradient. The steady-state form of the river incision model predicts a power-law scaling between the drainage area and channel gradient. Via a linear regression to the log-transformed slope-area data, the slope and intercept are channel concavity and steepness indices, respectively. The concavity relates to lithology, climatic setting and incision process while the channel steepness can be used to map the spatial pattern of rock uplift. For its simple calculation process, the slope-area analysis has been widely used in the study of tectonic geomorphology during past decades. However, to calculate river slope, the coarse channel elevation data must be smoothed, re-sampled, and differentiated without any reasonable smooth window or rigid mathematical fundamentals. One may lose important information and derive stream-power parameters with high uncertainties. In this paper, we introduce the integral approach, a procedure that has been widely used in the latest four years and demonstrated to be a better method for river profile analysis than the traditional slope-area analysis. Via the integration to the steady-state form of the stream-power river incision equation, the river longitudinal profile can be converted into a straight line of which the independent variable is the integral quantity χ with the unit of distance and the dependent variable is the relative channel elevation. We can calculate the linear correlation coefficient between elevation and χ based on a series of concavity values and find the best linear fit to be the reasonable channel concavity index. The slope of the linear fit to the χ value and elevation is simply related to the ratio of the uplift rate to the erodibility. Without calculating channel slope, the integral approach makes up for the drawback of the slope-area analysis. Meanwhile, via the integral approach, a steady-state river profile can be expressed as a continuous function, which can provide theoretical principle for some geomorphic parameters (e.g., slope-length index, hypsometric integral). In addition, we can determine the drainage network migration direction using this method. Therefore, the integral approach can be used as a better method for tectonogeomorphic research.     

南黄海OBS数据转换横波分析及其地质意义

多分量地震勘探在减小地球物理反演问题多解性的同时提供了更丰富的地下信息,可以从量化的意义上真正实现岩性勘探.由于地壳结构的复杂性及转换横波的特殊性,南黄海地壳结构研究中基本未涉及横波.本文使用南黄海OBS数据,在不同剖面上对比分析纵横波走时、视速度以及质点运动轨迹,基于纵波理论模型对转换横波震相进行射线追踪和走时试算,识别并拟合了来自不同地层的转换横波震相.研究表明,北部坳陷中主要发生了PPS转换,转换界面为陆相沉积层底界面.千里岩隆起区除了发生转换界面为陆相沉积底界面的PPS转换还有转换界面为海底的PSS转换.断层活动引起岩石破碎,高波速比特征的断层边界为胶莱盆地在海上部分的边界圈定再添证据.千里岩地区高速地层成分含有花岗岩,其纵横波速比为1.67~1.68;推测北部坳陷中的海相沉积北-南地层不同,依次为碳酸盐岩及砂岩两类地层.