Current observation and analysis based on mooring systems in the Andaman Sea

The basic structure and intraseasonal evolution of currents in the southeastern Andaman Sea was analyzed based on data collected in 2017 from two subsurface moorings(C1 and C5).Periodic variation in the upper ocean currents of the Andaman Sea was investigated by combining observational and satellite data.Mooring observations show that rapid changes of current speed and direction occurred in May and June,with a significant increase in current velocity at the C1 mooring.In the second half of the year,southward flow dominated at the C1 mooring,and alternating northward and southward flows were evident at the C5 mooring during the same period but the northward flow prevailed in boreal winter.In addition,analysis of the power spectra of the upper currents revealed that the tidal period at both moorings is primarily semidiurnal with weaker energy than that of the low-frequency currents.The upper ocean currents at the C1 and C5 moorings exhibited intraseasonal variation of 30-60 d and 120 d,while the zonal current at the C1 mooring exhibited a notable period of approximately 180 d.Further analysis indicated that the variability of currents in the Andaman Sea is influenced primarily by equatorial Kelvin waves and Rossby wave packets.Moreover,our results suggest that equatorial Kelvin waves from the eastern Indian Ocean entered the Andaman Sea in the form of Wyrtki Jets and propagated primarily along two distinct pathways during the observation period.In addition to coastal boundary Kelvin waves,it was found that a branch of the Wyrtki Jet that directly enters the Andaman Sea and flows northward along the slope of the continental shelf,and reflected Rossby wave packets by topography.

Intraseasonal variability of the Kuroshio observed via mooring at 18°N

Insufficient observations near the origin of the Kuroshio have led to incomplete understanding of the intraseasonal variability(ISV)of the Kuroshio.Direct measurements of the Kuroshio velocity were performed with an array of three profiler moorings(122.7°E,123°E,and 123.3°E)along 18°N from January 2018 to February 2020.The ISV of the Kuroshio at 18°N was investigated based on a combination of mooring observations and global high-resolution HYbrid Coordinate Ocean Model reanalysis data.The estimated time-averaged transport in the upper 350 m across the observation transect was 6.5±2.6 Sv(1.0 Sv=10^(6)m^(3)/s).Two significant ISV peaks at 50-60 and~100 d were recognized in the power spectra of the meridional velocity and transport.Further analysis indicated that the ISV at 50-60 d was caused by westward-propagating eddies at average propagation speed of~13 cm/s and wavelength of~635 km.Another ISV peak at~100 d was mainly caused by northward-propagating eddies generated in the North Equatorial Current region.Further investigation indicated that the ISV of the Kuroshio at 18°N is dominated by meridional transport,rather than by the zonal migration of the Kuroshio main axis.Our findings provide a better understanding of the ISV of the Kuroshio east of Luzon Island.

一类树的邻接矩阵的Moore-Penrose广义逆

根据矩阵结构性质,利用分块矩阵技巧给出任意点数、任意长直径的毛毛虫树邻接矩阵的Moore-Penrose广义逆的具体形式,为进一步研究毛毛虫树的代数性质提供理论支撑.

Study on the Characteristics of A New Hybrid Mooring System for DualPlatform Joint Operations

As the sustainable exploitation of marine resources develops,dual-platform joint operation has caught increasing attention.Dual-platform joint operation requires smaller relative motion between the two sub-platforms,which is normally difficult to be satisfied by the traditional mooring system.Therefore,a new hybrid mooring system is developed and studied in this article.To ensure safety during platform movements,both the number of anchor chains and the relative motion between the two sub-platforms are reduced in the new hybrid mooring system.By performing numerical simulations based on three-dimensional potential flow theory in AQWA and physical experiments,the performances of both the new hybrid and traditional mooring systems under two different wave conditions(i.e.,working wave and freak wave conditions) are systematically investigated.Regarding the new hybrid mooring system,the relative stability between the two sub-platforms of the new system is better,and the platforms can restore stability faster when affected by freak waves.

Motion simulation of moorings using optimized LSTM neural network

Mooring arrays have been widely deployed in sustained ocean observation in high resolution to measure finer dynamic features of marine phenomena.However,the irregular posture changes and nonlinear response of moorings under the effect of ocean currents face huge challenges for the deployment of mooring arrays,which may cause the deviations of measurements and yield a vacuum of observation in the upper ocean.We developed a data-driven mooring simulation model based on LSTM(long short-term memory)neural network,coupling the ocean current with position data from moorings to predict the motion of moorings,including single-step output prediction and multi-step prediction.Based on the predictive information,the formation of the mooring array can be adjusted to improve the accuracy and integrity of measurements.Moreover,we proposed the cuckoo search(CS)optimization algorithm to tune the parameters of LSTM,which improves the robustness and generalization of the model.We utilize the datasets observed from moorings anchored in the Kuroshio Extension region to train and validate the simulation model.The experimental results demonstrate that the model can remarkably improve prediction accuracy and yield stable performance.Moreover,compared with other optimization algorithms,CS is more efficient and performs better in simulating the motion of moorings.

Orthogonal Frequency Division Multiplexing Adaptive Technology for Multinode Users of Seawater Channel Based on Inductively Coupled Mooring Chain

As an important part of buoy-type ocean monitoring systems,the inductively coupled mooring chain solves the problem of data cotransmission through the multinode sensors that it carries,which is significant for the rapid acquisition of fish,hydrology,and other information.This paper is based on a seawater channel transmission model with a depth of 300 m and a bandwidth of 2 MHz.An orthogonal frequency division multiplexing(OFDM)technology is used to overcome the multipath effect of signal transmission on a seawater medium.The adaptive technology is integrated into the OFDM,and an improved joint subcarrier and bit power allocation algorithm is proposed.This algorithm solves the problem of dynamic subcarrier allocation during the cotransmission of underwater multinode user data in seawater channels.The results show that the algorithm complexity can be reduced by 0.18126×10^(-2)s during one complete OFDM system data transmission by the improved greedy algorithm,and a total of 216 bits are transmitted by the OFDM.The normalized channel capacity can be improved by 0.012 bit s^(-1)Hz^(-1).At the bit error ratio(BER)of 10^(-3),the BER performance can be improved by approximately 6 d B.When the numbers of users are 4 and 8,the improved algorithm increases the channel capacity,and the higher the number of users,the more evident the channel capacity improvement effect is.The results of this paper have an important reference value for enhancing the transmission performance of inductively coupled mooring chain underwater multinode data.

Mathematical Modeling of Moored Ship Motion in Arbitrary Harbor utilizing the Porous Breakwater

The motion of the moored ship in the harbor is a classical hydrodynamics problem that still faces many challenges in naval operations,such as cargo transfer and ship pairings between a big transport ship and some small ships.A mathematical model is presented based on the Laplace equation utilizing the porous breakwater to investigate the moored ship motion in a partially absorbing/reflecting harbor.The motion of the moored ship is described with the hydrodynamic forces along the rotational motion(roll,pitch,and yaw)and translational motion(surge,sway,and heave).The efficiency of the numerical method is verified by comparing it with the analytical study of Yu and Chwang(1994)for the porous breakwater,and the moored ship motion is compared with the theoretical and experimental data obtained by Yoo(1998)and Takagi et al.(1993).Further,the current numerical scheme is implemented on the realistic Visakhapatnam Fishing port,India,in order to analyze the hydrodynamic forces on moored ship motion under resonance conditions.The model incorporates some essential strategies such as adding a porous breakwater and utilizing the wave absorber to reduce the port’s resonance.It has been observed that these tactics have a significant impact on the resonance inside the port for safe maritime navigation.Therefore,the current numerical model provides an efficient tool to reduce the resonance within the arbitrarily shaped ports for secure anchoring.

实方阵的Moore-Penrose广义逆的MCG算法探究

证明了矩阵Moore-Penrose逆的唯一性以及建立了求矩阵Moore-Penrose逆的算法。首先将求矩阵的Moore-Penrose逆转为求解含有三个矩阵变量的矩阵方程组,其次建立求该矩阵方程组的修正共轭梯度算法(MCG算法),给出了MCG算法的性质和收敛性证明,对于任意给定的初始矩阵该算法能在有限步迭代计算后得到矩阵的Moore-Penrose逆。最后给出数值算例,证明MCG算法在求解矩阵Moore-Penrose逆中具有很高的计算效率。

Current Status and Future Trends for Mooring Systems of Floating Offshore Wind Turbines

With the increasing demand of energy and the limitation of bottom-fixed wind turbines in moderate and deep waters,floating offshore wind turbines are doomed to be the right technical choice and they are bound to enter a new era of rapid development.The mooring system is a vital system of a floating wind turbine for station-keeping under harsh environmental con­ditions.In terms of existing floating wind turbine projects,this paper is devoted to discussing the current status of mooring systems and mooring equipment.This paper also presents the mooring analysis methods and points out the technical difficulties and challenges in mooring design,in­stallation,operation and maintenance stages.Finally,the developing trends of the mooring system are summarized,aiming to provide a reference for future mooring research.

Dynamic Analysis of Semi-Submersible Production Platform Under the Failure of Mooring Lines

This paper quantitatively studies the transient dynamic response of a semi-submersible production platform with the loss of one or several positioning mooring lines.A semi-submersible platform,production risers,and positioning mooring lines are all included in the numerical simulation.Increased motion of the semi-submersible platform,tension variation of the remaining mooring lines/risers and the risk of mooring line or riser clashing are all investigated through fully coupled time-domain analysis.Combined environmental loads are selected from irregular waves and the steady current varying from very rough to extreme sea conditions.Three dimension radiation/diffraction theories and Morison’s equation are applied to calculate first-order wave force and second-order mean drift force of floating semi-submersible platform.Nonlinear time-domain finite element methods are employed to analyze the behavior of mooring lines and risers.Results show that the failure of mooring lines seriously reduce the platform’s stability performance.The tension of the rest lines is also increased accordingly.Remaining lines which are closer to the failed lines will have larger tension increase to compensate.Line-Line distance provides practical information for the risk of clashing investigation.

长方矩阵的Γ_(α,β)-Moore-Penrose群逆

PATRICIO等讨论了环中元素的Drazin-Moore-Penrose(DMP)可逆性,在矩阵环中得到了一些结果.讨论了长方矩阵的Γα,β-Moore-Penrose群逆,给出了长方矩阵的Γα,β-Moore-Penrose群逆存在的几个充要条件以及Γα,β-Moore-Penrose群逆的几个计算公式,把已有的平方矩阵的结果推广到了长方矩阵中.

环上长方形矩阵的加权群-Moore-Penrose可逆性

研究了具有对合的环上长方形矩阵的W加权群-Moore-Penrose可逆性。给出了环上长方形矩阵的W加权Moore-Penrose逆和W加权群逆的存在性的特性。环上长方形矩阵的W加权群-Moore-Penrose逆可以被刻画和计算出来。这推广了具有对合的环上平方矩阵的群-Moore-Penrose逆的结果。结果也适用于(加法)范畴中的态射.

Moore响度模型的数值计算方法

响度是最重要的声音属性之一,响度的计算是进行客观评价的基础,也是计算大多数心理声学评价参数的基础,在心理声学和声品质评价等领域具有重要意义。文章对基于Moore模型的响度计算方法进行了详细研究,阐述了算法的基本原理和计算技巧,给出了许多典型的计算结果,并对模型的改进提出了建议。

基于Moore值的河南省就业结构滞后时间测算及趋势预测

对河南省产业结构和就业结构Moore值进行计算的基础上,利用灰色关联分析测度了河南省就业结构滞后产业结构的时间,该滞后时间为10 a。运用灰色Verhulst模型对河南省就业结构的演化进行了预测,结果显示,河南省就业结构调整至与产业结构相符至少需要8 a时间。

关于Moore自动机可逆性的一些结果

主要讨论了Moore自动机(弱)可逆的一些性质,并给出了当|S|=|Y|时,Moore自动机(弱)可逆的充要条件。

从MOOC到MOORE——面向创新能力培养的军校研究生混合式课程教学

大规模在线开放课程(MOOC)的兴起和发展给军队院校研究生课程教学改革带来了巨大的机遇。在新的形势下,如何利用好开放的、国际互动性强的世界一流大学的优质MOOC课程资源,引导和培养军校学员的创新精神和创新能力,从MOOC到MOORE(大规模在线开放研究),需要深入研究和实践。通过分析MOOC的现状和不足,以创新能力培养为导向,提出引入MOOC到课堂形成混合式教学,调整学员和教师角色,提升研究生教学效率,加快创新人才培养和创新成果生成。

一种串匹配的快速Boyer-Moore算法

在对经典的Boyer-Moore和Quick Search串匹配算法进行分析的基础上,提出了一种更加快速的串匹配算法Quick Boyer-Moore(QBM)。QBM算法利用当前尝试中的已匹配子串、匹配失败字符信息以及与当前窗口下一个字符的位置信息,以在每一次跳跃中获得更大的跳跃距离,从而使算法具有更高的效率。在真实语料上的实验结果表明,QBM算法的效率较显著地高于原始的BM算法及其改进算法Improved Boyer-Moore(IBM)。

Moore模型与响度计算中的关键问题

基于Moore响度计算模型,从人耳听觉原理出发,给出了该模型的详细计算步骤,对关键参数进行了详细分析,计算了部分声信号的响度值,与美国国家标准(ANSI)进行了比较,验证了方法的正确性。

GIS局部放电在线监测超高频Moore分形天线研究

设计了一种应用于气体绝缘全封闭组合电器(gas insulated substation,GIS)局部放电在线监测的超高频Moore分形天线。首先从理论上分析了该天线的多频特性,使用ANSYS HFSS对Moore分形天线和Hilbert分形天线进行了仿真对比,仿真结果显示Moore分形天线方向性良好,并根据仿真结果制作了天线实物。采用矢量网络分析仪对天线进行实测,测试结果显示Moore分形天线在电压驻波VSWR<5时具有更多频段。最后,在实验室搭建了GIS局放测试平台,使用两种分形天线进行对比测量,结果表明,Moore分形天线特性良好,可用于GIS局部放电在线监测。

Moore机与Mealy机之间的转换研究

本文从本质上归纳了二种时序机 Mealy机与 Moore机之间的转换效果 ,根据二者的输出序列相差一个时钟周期的特点提出了二种十分简单的转换技术 .设计实例表明它们易于理解且十分简便有效 .