On-line identification and convergence analysis of excitation-force and drag-force models for moored floating structures

This work presents an approach to identify hydrodynamic models for incident, diffraction and viscous forces acting on a moored floating structure. An important aspect treated here is the analysis of the unknown initial condition of the hydrodynamic state for the potential-radiation force. There is established its influence on the parameter convergence and the long-term effects. Afterwards the persistency of excitation of the regressor is analyzed in the case of both poor and rich excitation conditions. Theoretical results show that asymptotic convergence of the estimates takes place under arbitrary conditions of the wave excitation. A case study consisting in the identification of a moored semisubmersible is carried out to exemplify the application of the approach.     

通载浮桥的水弹性响应分析

浮桥具有重要的军事用途，在民用上也已受到越来越广泛的重视。为了使浮桥的设计既安全又经济，就必须对浮桥的载荷和强度有一个比较精确的评估。浮桥载荷具有移动性，并可能同时遭受风、浪、流联合作用，浮桥在这些载荷联合作用下的动响应分析在理论上将是一个很具挑战性的问题。通过资料的收集和整理，对国内外相关研究的现状作了介绍，并指出了研究的主要方向。     

超大型海洋浮式储油系统的风险评估

对超大型海洋浮式储油系统的危险灾害识别、失效概率计算、失效后果评估、风险准则评定和风险管理决策等几个主要步骤进行了风险分析,计算结果为在设置防坡堤情况下,储油船漂移的概率为2 217×10-6,沉没的概率为6 778×10-8,结构损坏的概率为6 300×10-7,总的经济损失为70万人民币;在未设置防波堤的情况下,储油船漂移的概率为3 167×10-3,沉没的概率为9 683×10-5,结构损坏的概率为9 000×10-4,总的经济损失为9 91亿人民币。结果表明,采取合理的措施,如在储油船系泊地点设置防波堤,以降低风险水平是十分必要的。     

吐鲁番盆地近30年沙尘天气分布特征

通过对吐鲁番盆地1971—2000年30年沙尘天气发生日数的分析，得出了沙尘天气年平均、四季分布空间分布特征及年代际变化特征，分析了沙尘天气形成的原因。     

塔里木盆地一次浮尘天气的卫星云图特征

根据常规气象观测资料、GMS-5静止气象卫星的红外云图和可见光图像，分析了1999年4月25至5月4日塔里木盆地浮尘天气。分析结果表明，红外云图和可见光图像能够监测盆地浮尘的变化，浮尘呈灰色，纹理均匀，边界清晰。浮尘区的TBB在0～-15℃之间变化，与地面能见度有着较好的对应关系，大范围浮尘区的反射率在30％～36％之间，浮尘区反射率等值线稀疏，云区反射率等值线密集。     

High Resolution, Deep-Tow Seismic Survey to Investigate the Methane Hydrate Stability Zone in the Nankai Trough

Abstract. A high frequency deep-tow seismic survey was carried out in the Nankai Trough area in 1996. The objective of the survey was to obtain high resolution seismic sections and velocity profiles of the methane hydrate zone, inferred from the strong BSR events seen on conventional seismic data in the area. A special feature of the survey is that both the source and the streamer cable are towed close to the seabed. This special acquisition geometry requires special data processing to handle the varying source and receiver depths. A CMP floating datum processing sequence was designed which led to high quality sections of the shallow geology. A key step in the processing was devising a residual statics technique to compensate for errors in the measured depths.
The processing sequence was applied to a number of lines, totaling 200 km. The final data quality was highly variable. Some lines produced high quality sections and others, much poorer sections with few interpretable events. Conventional seismic data in the area also shows variation in the data quality so part of the reason is a variation in the sub-sea geology, but the deep-tow data is much more sensitive to change in conditions than conventional data. With the current acquired data and processing sequence the deep-tow system offers most advantages when 1) the water depth is around 1 km or greater, 2) the seabed and underlying geology is not too complex, and 3) the acquisition proceeds smoothly with regular shotpoints, slowly varying depths, and with accurate positioning.     

中部大城市流动人口的回流意愿及其影响因素——以武汉市为例

人口回流是新世纪中国人口流动的最新趋势之一,亟待对其特征与机制开展深入研究。本文以武汉为例,采用描述性统计和二元Logistic回归方法,揭示中部地区大城市省内与省际流动人口的回流意愿及其影响因素。研究发现：① 流动人口的回流意愿总体偏低,省内流动人口低于省际流动人口。② 性别、教育、家庭结构、家庭年收入及家庭经济状况满意度等内源因素驱动流动人口回流,流动人口在流入地的社会信任、身份认同等外源因素则对回流有抑制作用。③ 省内流动人口回流受个体、地区因素影响较大,省际流动人口回流更易受家庭、社会因素影响。因此,新型城镇化建设要重视不同流动人口回流机制的差异性。建议通过精准施策,一方面增强省际流动人口定居意愿,一方面促进省内流动人口就近城镇化。     

地震勘探技术在裴沟矿31采区的应用

在山区地震勘探中,由于复杂多变的岩性及地表的剧烈起伏影响地震成像的品质,本文以裴沟矿井31采区为例,首先在数据采集阶段针对不同地表条件采用不同设备成孔,保证原始数据质量;其次在资料处理阶段通过＂两步＂静校正方法解决山区高程及岩性变化引起的成像问题,获得高质量的处理成果。经过矿井生产的初步验证可知,所采用的技术手段正确,所取得的地质成果精度较高。     

2010 年夏季大连溢油事件期间北黄海漂流浮标移动轨迹的数值模拟

采用双层单向嵌套的普林斯顿大学海洋模式(POM)对2010年夏季大连溢油事件期间北黄海释放的表层漂流浮标的移动轨迹进行了数值模拟,模拟结果与实测轨迹基本吻合,模拟的表层流速纬向和经向分量与观测数据的相关系数在两观测点分别达到了0.6548,0.3659和0.4836,0.3961,均明显大于95%置信区间下的显著性临界值0.1946,但是模拟的浮标移动速度明显慢于观测。模拟出的速度时间序列在变化趋势上与实测吻合良好,但是流速数值相对于观测整体上偏小。该数值模拟系统能够较准确地模拟出2010年大连溢油事件期间北黄海的流场及漂流浮标的运动趋势,为北黄海的环境预警、灾害评估等相关研究提供有益的参考。     

悬浮桩水平振动的动力刚度

通过将悬浮桩截面下土体等效为土桩,利用桩的水平振动土阻抗结果,分析了桩、土桩构成的组合桩在频率域内的动力响应,给出了黏弹性土层中黏弹性悬浮桩水平振动动力刚度的半解析解,得到了动力刚度随各种物性参数的变化曲线。在此基础上,研究了物性参数对刚度的影响,对比了细长桩和短粗桩的响应差异。结果表明,悬浮桩水平振动的动态刚度受桩长、土的软硬程度、水平激振频率等的影响,这些结果可以为工程设计提供参考依据。