利用轨道参数修正的无控制点星载SAR图像几何校正方法

使用距离多普勒模型进行SAR图像几何校正时,卫星轨道误差、系统成像参数误差和DEM高程的误差会影响几何校正精度。本文提出了一种基于轨道参数修正的星载SAR图像几何校正方法。首先利用多项式对卫星轨道进行参数化,然后使用模拟SAR图像与真实SAR图像进行匹配得到控制点来修正轨道参数,最后利用修正后的参数进行几何精校正,从而提高几何校正精度。该方法无需地面控制点,适用于不易于人工测量获取地面控制点地区的SAR图像几何校正,与基于模拟SAR图像匹配并使用多项式改正的几何校正方法相比,本文方法具有更高的精度。使用Radarsat-2图像进行试验,并使用地面实测GPS控制点验证了本方法的有效性。     

埕岛油田海域波—底相互作用

基于1976，1993年埕岛油田海域测深资料，应用HISWA浅水海浪数值计算模式，研究风暴浪入侵该海域导致的波-底相互作用后果。数值计算结果表明，海区固定点海底冲刷导致波场强化；波参数增量与冲刷深度有关；海底水质点轨道流速峰值，底摩擦耗散峰值及临界波高值相对水深分布均表明，该海域深水区海底冲刷将减弱，浅水区海底冲刷将加强。     

Study on optimization of parameters in a biological model

~lOWThere is a great progreSS tO apply inathernatics m~ in studying marine ~. Because of more Parameters than there that can be speified aCCOrding to the finite dsts, itS parameters had tO be ~hly evaluated in geneal. On the other side, the ~ ~ter fitting in a cendn area is USually unfit in another area for the complication Of ~ iodf.It was lucky that the pwhlerns, how to evalUate the Parameters as ~y as ~ie ina~ with the available dsta and how to judge to what a extent the ParameterS s…     

桩柱周围海底冲刷深度计算及动力参数的选取

通过６０年代以来研究的桩柱周围海底冲刷深度计算模式的对比分析表明,我国学者王汝凯等人提出的“普遍冲刷深度”、“局部冲刷深度”和“总冲刷深度”的计算模式在科研和生产实践中是可行的,能给设计和施工提供科学的和有价值的参数。各种冲刷深度的计算模式如下：普遍冲刷深度ｌｇ（Ｓｕ０／ｎ＋０．０５）＝－０．６６３＋０．３６４９ｌｇα（１）局部冲刷深度ｌｇ（Ｓｕ１／ｈ）＝－１．２９３５＋０．１９１７ｌｇβ（２）总     

A Study on Crack Detection with Modal Parameters of A Jacket Platform

Crack detection procedures by different modal parameters are analyzed for identitying a crack and its location and magnitude in a jacket plafform. The first ten natural frequencies and modal shapes of the jacket models are obtained by numerical experiments based on NASTRAN Code. A crack at different locations and of different magnitudes is imposed in the model at the underwater beams. Then, the modal evaluation parameters are calculated numerically, to illustrate the evaluation of modal parameter criteria used in jacket crack detection. The sensitivities of different modal parameters to different cracks are analyzed. A new technique is presented for predicting the approximate location of a breakage in the absence of the data of an intact model. This method can be used to detect a crack in underwater menbers by use of incomplete mode shapes of the top members of the jacket.     

不定积分变换法对二度体磁异常的研究Ⅰ-水平圆柱体、直立薄板的不定积分变换

作者从二度磁性体的磁异常公式出发,推导出各异常的不定积分变换结果,并由变换结果绘制不定积分变换的磁异常参量图.本文选取2种规则形态磁性体,在取不同空间几何参数的条件下,讨论它们不定积分变换后参量图的曲线变化规律,并总结其异常特征,而后将其与积分变换前的参量图对比进行磁异常讨论和效果分析.该方法能反映一些重要的地质信息,将有助于实际的磁异常解释.     

Damage Localization of Offshore Platforms Under Ambient Excitation

In this paper Nondestructive Damage Detection (NDD) for offshore platforms is investigated under operational conditions. As is known, there is no easy way to measure ambient excitation, so damage detection methods based on ambient excitation have become very vital for the Structural Health Monitoring (SHM) of offshore platforms. The modal parameters (natural frequencies, damping ratios and mode shapes) are identified from structural response data with the Natural Excitation Technique (NExT) in conjunction with the Eigensystem Realization Algorithm (ERA) . A new method of damage detection is presented, which utilizes the invariance property of element modal strain energy. This method is to assign element modal strain energy to two parts, and defines two damage detection indicators. One is compression modal strain energy change ratio (CMSECR); the other is flexural modal strain energy change ratio (FMSECR). The present modal strain energy is obtained by incomplete modal shape and structural stiffness matr     

黄河口滨海区潮流速度铅直分布及其粗糙度参量的初步研究

在我校与美国俄勒岗大学等单位联合黄河口调查期间,作者用简易方法对该区潮流铅直分布进行了专门观测。将获得的资料与一种浅海理论公式计算值进行了比较。首次计算了该区粗糙度参量Z_0值的分布。提出了最大潮流速铅直分布与相对粗糙度参量的关系。     

福建3个港湾和闽南—台湾浅滩海域光学参数的研究

本文根据现场浮游植物光合作用速率和叶缘素a 的测定值,以及海水光强度的衰减变化,计算了海水消光系数,推导了福建东山湾、罗源湾、厦门西港和闽南-台湾浅滩海域海水消光系数与透明度的经验关系式;讨论了悬浮颗粒对不同深度下浮游植物生长速率的影响。结果表明,福建近岸海域光学参数的差异主要在于悬浮物质的贡献;不同季节,生物活动对光学参数也有所影响。最大光合作用速率一般出现在光衰减为10%～30%,频率分布因子为70%～80%。     

海口港沉积参量遥感研究

利用卫星遥感对同一地区重复成像的特点，采用从港湾不同时相的影像中提取不同潮位的水域面积的方法，建立潮位面积算式和采用分层求和的方法，建立沉 积参量算式。利用沉积参量算式和潮位面算式计算了海口港两个同时段的０ｍ以浅的沉积参量；１９６５－１９８４年时段沉积总量为４．５９×１０＾８ｍ＾３，沉积速率为２．４×１０＾５ｍ＾３／ａ；１９８４－１９９０年时段，沉积总量为－８．４×１０＾５ｍ＾３，沉积速率为－１．