Uncertainty in marine weather routing

Weather routing methods are essential for planning routes for commercial shipping and recreational craft. This paper provides a methodology for quantifying the significance of numerical error and performance model uncertainty on the predictions returned from a weather routing algorithm. The numerical error of the routing algorithm is estimated by solving the optimum path over different discretizations of the environment. The uncertainty associated with the performance model is linearly varied in order to quantify its significance. The methodology is applied to a sailing craft routing problem: the prediction of the voyaging time for an ethnographic voyaging canoe across long distance voyages in Polynesia. We find that the average numerical error is an order of magnitude smaller than the performance model uncertainty. These results illustrate the significance of considering the influence of numerical error and performance uncertainty when performing a weather routing study.     

Hydrodynamic Tidal Model of the Persian Gulf Based on Spatially Variable Bed Friction Coefficient

The aim of this study is to develop a two-dimensional hydrodynamic tidal model for the Persian Gulf (PG2017) using 2D-MIKE21 software. The advantages of present study is accounting for the spatial variation of bed friction coefficient besides a precise bathymetry together with a 23-year of combined records of satellite altimetry data. We found that the bed friction coefficient has a significant effect on sea level changes in the region under our modeling consideration. Since the tidal behavior in the northern part of the Qeshm Island is significantly different from the other parts of the Persian Gulf, to present a more accurate hydrodynamic tidal model, the Gulf is divided into two regions where the bed friction coefficient is modeled separately for each region. The root mean square value of the differences between the amplitude of dominant constituents; M2, S2, K1, and O1 derived from the PG2017 model and that of 98 altimetry and coastal tide gauge stations are respectively equal to 1.6, 1.9, 2.8, and 1.3?cm. Moreover, comparing the PG2017 model efficiency with the FES2014, OSU12, EOT11a, DTU10, and Admiralty models shows that the PG2017 model has an improvement of 22.1%, 47.2%, 43.2%, 44.2%, and 57.6% in terms of relative error, respectively.     

A New Wavelet Method for Identification of Eddies and Assessment of Incidents on Islands of the Eastern Caribbean

Using two dimensional continuous wavelet transforms, a novel method for identification of mesoscale eddies is presented to facilitate extraction of characteristics for area, amplitude, type, and location from maps of sea level anomalies. In comparison with the previously established growing method for eddy identification, it is found that the wavelet method identifies more than twice the number of eddies and is particularly better at resolving small eddies down to the 0.25 degree resolution of the data. Such research into eddy identification and tracking is significant to the assessment of eddies with potential to impact on coastlines of small islands. The method is applied to the identification of eddies on tracks towards islands of the Eastern Caribbean over 23?years. Spatial and temporal variation in rate of occurrence and magnitude is established. For Barbados there is an average of 9 anticyclonic incidents a year with maximum amplitude of typically 0.22?m in the dry seasons and 0.16?m in the wet seasons. Seasonal variation is reversed for the other islands with twice the number of anticyclonic incidents having maximum amplitudes of about 0.20?m annually.     

基于分光光度法的多量程海水营养盐原位传感器检测系统设计

针对传统海水营养盐检测方法不能满足海水营养盐长期原位监测需求的问题,研制了一种基于分光光度法的多量程海水营养盐原位传感器检测系统,通过对系统的高度集成及对多量程检测、低功耗技术、漏液保护技术的应用,实现了对海水5项营养盐参数快速、宽范围、高精度的原位测量。经过实验室和青岛中苑码头现场测试,表明本营养盐传感器检测系统具有低功耗、高可靠性能,可满足对5项营养盐参数的快速精确测量要求,实现了对海水营养盐参数的原位监测,为相关部门及时了解海洋生态环境和水体富营养化程度提供了数据支持,具有重大现实意义。     

基于深度学习的钨钼找矿靶区预测方法研究

随着矿产勘查工作由浅部矿向深部隐伏矿、由易识别矿向难识别矿发展,找矿难度日益增大,地质专家越来越重视新理论、新方法、新技术的应用。深度学习作为人工智能的前沿领域/技术,对于实现矿产资源预测“智能化预测评价”具有得天独厚的优势。本文以陕西省镇安县西部钨钼矿集区单元素化探异常原始数据为基础,提出了基于深度学习的钨钼矿产评价方法。该方法以归一化地球化学数据作为模型训练数据,通过深度学习中深度自编码网络方法实现异常值提取进而识别重点成矿有利地段,实现矿产资源找矿远景区定性预测。研究结果表明,在对957条单元素化探异常原始数据分类且做好模型标签后,整个过程在计算机的“黑盒子”中自动完成学习和预测,相较于传统预测研究方法,本文方法具有自动化程度高和客观性强的特征。此外,本文利用已知矿点构建训练数据集,采用随机森林方法对预测区进行矿产资源找矿靶区预测圈定,为进一步缩小找矿靶区范围提供科学依据。     

用随机有限断层方法模拟2016-11-13新西兰Mw7.8地震

在未来大地震发震构造已知的前提下,提出用经验公式确定大地震断层长度、宽度、地震矩和滑动分布等参数,并用随机有限断层方法预测未来大地震。用随机有限断层方法模拟2016-11-13新西兰M_W7.8地震的12个基岩台站地震动时程和反应谱,并用模拟的频谱幅值与记录频谱幅值平均比值确定模拟误差。结果表明,在周期为0~10 s的范围内,模拟误差在0.92~1.08之间,不同频率模拟误差的标准差变化范围不超过1。95%的置信区间宽度随频率无明显变化,模拟结果反映了地震动记录的平均效果。用准随机方法重新获取新西兰大地震断层初始破裂点和位错滑动分布,模拟地震动并计算模拟误差随频率的变化,得到与最初模型相似的结论,从而进一步证实了本文提出的获取震源参数并用随机有限断层方法预测未来大地震的可靠性,且其特别适用于大地震远场模拟。     

基于共轭梯度搜索的病态问题处理方法

在最小二乘平差准则基础上,把病态平差问题转化为无约束的二次规划问题,并利用优化理论分析病态对平差解的影响。通过共轭梯度搜索算法在可行域中寻找最优步长因子,自动寻找最速下降方向,并给出迭代初值的设置方法。分析近似计算中病态问题与局部最优解的关系,讨论局部最优解的快速迭代方法,并通过实例验证算法的有效性,计算迭代的速度。由于整个过程没有对法方程系数矩阵进行求逆计算,该算法可用于处理大规模系数矩阵高病态的平差问题。     

基于全球分布的地震观测数据估计0S0模态的特征频率及品质因子

选取2011-03-11日本MW9.3地震后全球地震台站记录的约220 h波形数据,基于一定的判断准则,筛选出质量较高的448个垂向观测数据,采用频域AR方法对0S0模态的特征频率和品质因子进行估值,并以信噪比为权重进行加权平均,得到特征频率f=0.814 658 4±5.3×10-7,品质因子Q=5 586±12。该结果与已有研究成果相比精度更高,有助于约束现有地球介质密度和衰减模型,使其更接近真实地球。     

基于机器学习的高精度高分辨率气象因子时空估计

气象变量常作为重要的影响因子出现在环境污染、疾病健康和农业等领域,而高分辨率的气象资料可作为众多研究的基础数据,对推进相关研究的发展意义重大。本文以中国大陆为研究区域,利用2015年824个气象站点的气温、相对湿度和风速3套数据,结合不同的解释变量组合,分别构建了各自的GAM和残差自编码器神经网络（简称残差网络）模型,以10倍交叉验证判断模型是否过拟合。研究结果表明：① GAM和残差网络方法都不存在过拟合问题,同GAM相比,残差网络显著提高了模型预测的精度（3个气象因素的交叉验证CV R²平均提高了0.21,CV RMSE平均降低了37%）,其中相对湿度模型的提升幅度最大（CV R²:0.85 vs. 0.52,CV RMSE:7.53% vs. 13.59%）;② 残差模型的结果较普通克里格插值结果和再分析资料更接近站点观测数据,表明残差网络可作为高分辨率气象数据研制的可靠方法。此外,研究还发现在相对湿度模型中加入臭氧浓度和气温、在风速模型中加入GLDAS风速再分析资料,可提升模型的性能。     

青藏高原东南缘构造应力场重构

采用有限元方法,针对青藏高原东南缘建立更细致、更精确的三维有限元弹性模型。选取9种不同的应力边界条件,分别进行优化分析后处理,将对应台站形变模拟值与GPS实测值进行误差分析,最终选取最佳方案作为古构造应力场。结果表明,青藏高原东南缘4 Ma BP的古应力场主要起源于中国大陆周围板块的相互作用,特别是印度板块NNE向强烈碰撞作用,成为中国大陆尤其是西南部青藏高原地区构造应力场最主要的动力来源,控制各个块体相互作用的方式和运动格局。青藏高原东南缘古应力场主要包括几个力源：西北部青藏高原侧向挤压造成的WE向应力约105 MPa;西南部直接来自于印度板块的NE-WS向应力约70 MPa;南部NS向作用力33 MPa;东南部扬子块体侧向NW-SE阻挡力56 MPa;北东部受扬子块体强烈EW向阻挡力90 MPa。这些力源共同作用于青藏高原东南缘,形成现今复杂应力场。