Sevan钻井储油平台双层底结构的运动响应数值计算分析

为研究双层底结构Sevan钻井储油平台在南海海况下的运动响应特性,建立SEVAN650平台的ANSYS有限元模型,将模型导入水动力分析软件AQWA进行数值计算,得出双层底结构SEVAN650钻井储油平台的垂荡、横摇、纵摇运动响应幅值算子曲线,进而分析SEVAN650平台在南海海况风暴自存状态下的运动特性。研究表明,在风暴自存状态下,双层底平台的垂荡、横摇、纵摇的固有周期大于单层底平台。随着双层底平台直径的增加,平台的固有周期和垂荡最大响应幅值逐渐增加,平台横摇和纵摇最大响应幅值先增加后减小,在直径87.5 m时达到峰值,双层底结构的使用效率逐渐降低。由于双层底直径85 m平台的固有周期已在风暴情况波浪周期外,在风暴作用下平台不会发生共振,因此SEVAN650双层底直径85 m平台能够满足在我国南海生产作业。

SEVAN650圆筒钻井平台动力定位系统设备配置研究

近年在全球获得的重大勘探发现中，有50％来自海洋，主要是深水海域。SEVAN650圆筒深水钻井平台是具有3000m水深作业能力，并且配备了DP3系统，其DP3动力定位系统是深海钻井的关键设备之一。分析海洋工程装备动力系统的船级符号、配置选型，并结合分析结构介绍SEVAN650圆筒深水钻井平台的动力定位系统的设备配置情况。

Using Remote Sensing Technologies for the Research of the Transformation of Ecosystems （Case Study： Lake Sevan Basin）

In mountain regions such as Lake Sevan basin, landscape-ecological problems are manifested sharply. Lake Sevan basin lies in the east of the RA （Republic of Armenia） and is characterized by unique natural and economic peculiarities. It covers an area of 4,891 km^2, or 16% of the entire territory of the country. The article considers the dynamics of the ecosystems of Lake Sevan basin through remote sensing data. To achieve the stated goal, multi-zonal satellite images Landsat ETM （Enhanced Thematic Mapper Plus）, Landsat TM （Thematic Mapper） and Landsat MSS （Multispectral Scanner） were applied. All satellite imagery data was geometrically and atmospherically corrected. Temporal changes were determined using both a supervised classification approach and NDVI （normalized difference vegetation index） in that time series. Supervised procedure, a hierarchical land cover classification system was used to detect the different land cover classes in the Lake Sevan basin, Armenia. According to this system, four land cover categories exist in this area： （1） water; （2） vegetation-bare; （3） man-altered land; （4） vegetated land, which indicate that for the last 40 years the study area has displayed expansion of man-made landscapes and vegetation-bare sites, ecosystems having lower biomass and reduction of woodlands. NDVI values and the area they covered indicate that between 1973 and 2011, the area of almost non-vegetated lands increased approximately by three times. The main cause of such changes is activation of erosion processes as a result of a climate warming.

大型海洋工程装备的浮态制造方法研究

为解决传统方法制造大型海工装备周期长,对船坞要求高,下水困难的问题,提出了浮态制造方法。浮态制造方法是以水的浮力为支撑在水面上以分层制造,逐层叠加的方式直接制造产品的新方法,主要应用于大型海工装备的合拢装配。介绍了浮态制造基本原理和制造规范,并以浮态制造方法指导了SEVAN 650的建造,包括平台选择,分段划分及底层水下旋转。SEVAN 650的成功建造验证了浮态制造方法的可行性,可以解决大型海工装备下水难的问题,缩短制造周期。