大连港外海域船舶尾迹光学特征研究

通过大连港外海上实验测量船舶含气泡尾迹表观光学特征(如离水辐亮度、遥感反射率),分析了尾迹气泡对极度混浊的Ⅱ类水体海水表观光学特征的影响.实验结果证明:无论在可见光还是近红外波段,尾迹气泡都增强了海水表观光学量,如"耘海"船尾迹遥感反射率在可见光波段相对背景海水提高了50%,在近红外波段相对提高了159%.数据分析结果表明在此种水体中,气泡使得尾迹海水水色变黄,而不是在Ⅰ类水体中使水色变绿.随着观测点在尾迹中的位置靠近目标船,气泡数密度不断增加,遥感反射率也随之增强.     

Population abundance and seasonal migration patterns indicated by commercial catch-per-unit-effort of hakes (Merluccius capensis and M. paradoxus) in the northern Benguela Current Large Marine Ecosystem

We developed generalised additive models (GAMs) to estimate standardised time-series of population abundance indices for assessment purposes and to infer ecological and behavioural information on northern Benguela hakes, Merluccius capensis and M. paradoxus, using haul-by-haul commercial trawl catch-rate data as proxies for hake densities. The modelling indicated that individual ship identifiers should be used rather than general vessel characteristics, such as vessel size. The final models explained 79% and 68% of the variability in the commercial catch rates of M. capensis and M. paradoxus, respectively. The spatial density patterns were consistent and confirmed existing knowledge about these species in the northern Benguela system. Furthermore, seasonal migration patterns were described for the first time and were found to correspond to the known spawning areas and seasons for M. capensis and M. paradoxus. Spatial density patterns were validated using the geostatistical modelling results of fisheries-independent trawl survey data. Improved understanding of the relationships between fleet dynamics and fish movement can be achieved by taking into consideration the present catch-rate model and spatial and seasonal distribution maps. We conclude that the yearly standardised CPUE time-series are problematic as proxies for total stock abundance because of spatial coverage issues. Consequently, such CPUE data should not be used for stock-size assessments and fisheries advice concerning northern Benguela hakes until this is solved. We generally recommend the exclusion of standardised CPUE time-series from stock assessments when important and changing parts of the stock distribution cannot be targeted by the fishery, such as due to closed areas or seasons.     

基于分区间泛化Kriging近似模型的船舶局部结构形状优化

为提高Kriging近似模型在船舶结构性能多维度响应预测方面的适用性,对常规Kriging近似模型进行分区间泛化改进:一是对设计样本点的各个维度(分量)进行划区,并在每一个分区间内采用最优拉丁超立方(OLhd)取样;二是引入比例系数w1组合高斯与指数型相关函数提高模型对数据的泛化能力,从而在每个划分的区间内建立泛化的Kriging近似模型。通过SCH测试函数,验证了构造的分区间泛化Kriging模型有效性。结合参数化建模和改进Kriging近似模型对某过渡肘板和舱口角隅边界进行形状优化,优化第一阶段由改进的近似模型通过多岛遗传算法得到全局初步的最优解,第二阶段在初步解的基础上缩小优化变量范围,由少量的FEM计算即可在小范围内搜寻到精确的最优设计变量。结果表明:分区间泛化Kriging近似模型在预测多维度响应时较常规Kriging模型预测精度更高;分阶段的形状优化流程在保证极小误差和缩小计算成本的情况下能够得到理想的应力分布和重量优化结果,有助于船舶结构的轻量化研究。     

基于结构特征的SAR船只类型识别能力分析

1 引言 SAR是船只探测的有效手段,利用SAR影像不仅可以检测船只目标,而且还可以提取船只的长度、宽度以及航速、航向等信息.随着星载SAR空间分辨率的提高,使基于星载SAR影像的船只类型识别成为可能.利用星载SAR可以检测出大面积范围内的船只和初步识别其类型.     

雷暴对流起电机制理论分析

本文用一维分层模式理论分析了地面降雨、尖端放电、对流运动以及云外电导率变化对雷暴电结构的影响。分析指出,云内对流强度明显地影响着雷暴电结构,强烈的地面降雨和尖端放电可使地面电场强度显著减小,甚至极性翻转。闪电和云顶附近的下沉气流是维持雷暴向上提供充电电流的重要条件。在雷暴中,对流起电机制是一个不可忽略的重要过程。     

利用遥感技术监测船舶航速的方法研究

主要讨论了两种利用遥感技术提取水面运动船舶的航速方法：利用波高谱信息提取航速和利用船尾迹中的横波信息提取航速。作者介绍了这两种方法的原理，描述了利用遥感技术提取船舶航速的工作流程，并利用模拟和实测的船尾迹波高数据对这两种方法进行了验证。从计算结果看，两种方法精度都能满足仅要求航速量级的需求者，利用波高谱信息的方法误差（10％左右）小于利用横波信息的方法误差（20％左右）。该项研究为实时或近实时探测运动船舶航速提供了新的方法。     

三维激光扫描技术在船体外形测量中的试验性研究

介绍了三维激光扫描技术的测量原理,进行了21 m长船体外形测量的试验性研究,证明了其在快速、高效获取船体三维数据、提取船体型线方面有着较大的优越性。     

The Wave Energy Concentration at the Agulhas Current off South Africa

The case of a freak wave collision with the ship in the Agulhas current is described. The explanation of the appearance of the freak wave as a result of wind-wave transformation in the Agulhas current is given. Swell is captured and intensified by the counter-current and is located in the neighbourhood of the maximum value of the current velocity, as a result of which there is a great concentration of wave-energy density. The superposition of wind and sea with swell transformed by the current promotes the formation of the freak waves. Using a simple mathematical analysis, an optimal ship track is proposed which could reduce the risk of collision with a freak wave.     

关于商业性地勘工作的几点认识

本文初步总结了市场经济国家的商业性地勘工作主要特点,对我国今后开发商业性地勘地作所要解决的问题做了探讨,并就冶金地质队伍如何更好地适应今后商业性地质工作提出了建议。     

船行波对H-ADCP 影响分析研究

作为当今世界上最先进的测流仪器，水平式声学多普勒流速剖面仪（Horizontal Acoustic Doppler Current Profiler，H-ADCP） 因其精度高、速度快等突出优势在河流中的应用越来越广泛，但在航运业发达地区，由于受船行波的影响，很难得到稳定可靠的流速数据，阻碍了H-ADCP在平原河网地区的应用和推广。目前技术上很难做到完全消除船行波的影响，本文将H-ADCP应用在平原河网地区对流速进行测量，并分析了船行波对测量精度的影响。从H-ADCP设备选型、测量和安装方式、测量预处理、数据后处理等多方面入手，可以有效消减船行波对H-ADCP 的影响，从而提高测流精度。同时，通过实验测量断面一天内平均流速变化情况，得到受船行波影响后的流速波形，然后采用数据处理手段，验证了所提方法的可行性。