基于在线海流数据的自然能驱动无人艇能源最优路径规划

为了有效地利用在线监测到的海流和风数据,减少能源消耗以提高自然能驱动无人艇的续航力,以“驭浪者”号自然能驱动无人艇为研究对象,提出一种基于在线海流数据的能源最优路径规划方法。通过“驭浪者”号实船试验得到的最小回转半径对粒子群算法进行改进,设计距离最优的路径规划算法。考虑到海流和风对“驭浪者”号能源消耗的影响,建立海流和风影响下能源消耗模型;在静态海流环境中,以能源最优为目标对粒子群算法进行改进,探索能源最优的路径规划算法。根据“驭浪者”号在线监测到的海流和风信息,得到随时间-空间变化的动态海流数据,对能源最优的路径规划算法进行优化,提出基于在线监测海流数据的能源最优路径规划算法。通过仿真试验,对比距离最优的路径规划算法和基于在线监测海流数据的能源最优路径规划算法在相同工况下能源消耗情况,验证所提出算法的可行性和有效性。

杭州湾地波雷达观测的海流数据取样率分析

根据杭州湾口区两台地波雷达5个半月观测的资料,对其中的3 189个有效观测时次的海流数据取样率(CSR)在空间和时间上的变化规律进行了分析,结果表明,在两台雷达波交叉观测的中心区域各测点的地波雷达观测的海流数据取样率高于外围区域,在中心区域海流数据取样率可达98%以上,向外围区域海流数据取样率逐渐平缓递减,到边缘区域海流数据取样率仅在20%以下;地波雷达观测的海流数据取样率有明显的日变化,白天海流数据取样率明显低于夜间;17时海流数据平均取样率达到最低值(约49%),然后很快上升,至02时达最高值(约74%),然后再缓慢下降至17时为止。同时在10时和20时地波雷达观测的海流数据取样率呈现两个相对低值点,可能与人们在这两个时段通讯繁忙所造成的干扰有一定的关系。海流流速对地波雷达观测的海流数据取样率也有较大影响,呈负相关,流速大时海流数据取样率比流速小时的要低,在海流数据取样率大于98%的中心区域,流速和海流数据取样率的相关系数小于-0.8,在海流数据取样率大于60%的区域,流速和海流数据取样率的相关系数小于-0.6,体现明显的相互关联。地波雷达观测的海流数据取样率和潮汐有着每日4次的良好相干,而似乎和风没有显著的关系。希望这些分析对地波雷达以后的推广使用能积累一些经验和参考意见。

GPS与基于海流数据库的推算船位的数据融合

当前 ,潜艇在水下可获得的导航信息十分有限。因此 ,如何利用现有的装备来提高水下导航的精度一直是水下导航界关注的热点。本文构造了基于GPS的水面导航信息融合子系统和基于海流数据库的水下导航信息融合子系统。并对两种子系统的联合滤波进行探讨 ,并利用联合滤波来对水下导航信息融合子系统进行修正来提高水下导航信息的精度。经过大量的计算机仿真实验证明。该方法十分有效。大大提高了水下导航的精度和系统的稳定性。

基于海流数据库的水下导航信息融合方法探讨

如何提高水下导航的精度一直是导航界关注的热点问题。特别是对于缺少高精度导航信息源的水下载运工具,这个问题显得尤为突出和急需解决。针对这种现状,本文对几种常用水下导航信息融合算法进行了比较,创造性地提出了通过建立完善的海流数据库,以此来增加一个精度较高的导航信息源,并提出了一种适用于水下载运工具的导航信息融合算法,通过大量的计算机模拟仿真实验和海试证明,该方法能大大提高水下导航的精度,并具有很强的实用性。

基于海流数据库的Kalman滤波在水下导航中的应用(英文)

定位精度对载体至关重要。提高定位精度有2种方式:一是增加高精度导航设备;二是利用数据处理方法。水下载体缺乏高精度的导航设备,但其又需要在水下保持长时间的精确航行。通过建立高精度的海流数据库,然后利用数据融合算法对水下导航信息进行处理来获得高精度的位置信息,该数据融合算法实质是基于海流数据库的Kalman滤波。通过大量的仿真实验和海试证明,该算法具有很强的实用性和有效性。

GPS与基于海流数据库的推算船位的数据融合

当前 ,潜艇在水下可获得的导航信息十分有限。因此 ,如何利用现有的装备来提高水下导航的精度一直是水下导航界关注的热点。该文构造了基于GPS的水面导航信息融合子系统和基于海流数据库的水下导航信息融合子系统。对两种子系统的联合滤波进行探讨 ,并利用联合滤波来对水下导航信息融合子系统进行修正以提高水下导航信息的精度。经过大量的计算机仿真实验证明 ,该方法十分有效 ,大大提高了水下导航的精度和系统的稳定性。

用VB+ADO对海流数据库的访问

对海流数据库的访问,以VB编程,利用ADO模型的Connection、Command和Recordset三个主体对象实现。其数据访问应用程序包括连接数据源、执行访问命令、存储命令、检测错误等步骤。VB访问不同数据源,其连接ADO数据源的方法有:ADO编程、数据环境设计器和ADOData控件。

一种座底式剖面海流计实时监测仪设计

为了有效解决在近海定点海流座底观测中声学多普勒剖面海流计投放后容易倾倒的问题,设计一种座底式剖面海流计实时监测仪,确保仪器投放完毕后能垂直向上工作,以正常获取剖面海流数据。采用数字三轴加速度传感器及液晶显示系统,在数据实时可读性、稳定可靠性方面具有一定的技术优势。该设备实用性强,操作简单方便,提高了现场操作人员的工作效率与设备投放成功率,节省了大量的人力、物力和财力。

基于海流的卡尔曼滤波在船舶导航上的应用

针对船舶的导航精度提高的问题,采用基于海流数据的卡尔曼滤波算法获得的海流信息,并通过对船舶经纬度、海流分量和航向、航速等非线性微分方程进行线性化处理,得出其相应的转移矩阵,然后推算出船舶在某时刻的测量向量和测量矩阵.最后对各个方程式进行卡尔曼滤波计算,并通过对系统的仿真所得到的误差曲线验证了该方法的有效性,最终通过该方法保证系统模型的实时性.

基于LIC的海流动态模拟与可视化

线积分卷积(LIC)方法是一种针对矢量场数据的可视化技术,本文主要研究了LIC方法应用于海洋流场的可视化质量改进问题。主要包括以下几点改进:根据海流运动方向改变稀疏背景噪声的指向以使流线变得更加细长明亮;针对稀疏噪声中海流变化剧烈的区域流线会出现分叉的问题,采用忽略稀疏背景噪声流线追踪时非主流线部分的纹理点的积分计算方法来解决此问题,同时可以省去不必要纹理点的积分计算的开支,加快显示速度;采用赋予海流随机的初始相位的方法来解决稀疏噪声循环动画突兀的问题;通过流线的运动速度快慢或者流线的颜色来表示海流速度大小;通过对海流数据进行插值并改善边界流线追踪条件的方法可形成完整细致的全球海流图像。实验结果表明,该方法可以生成纹理对比强烈、细节清晰、动画连贯的高质量海流运动图像,具有良好的可视化效果。

AUV水下导航信息融合方法研究

通过构建一种虚拟导航设备,并将其作为Kalman滤波的量测信息构成一个水下导航信息处理方法。计算机仿真模拟和海试结果分析表明,带数据库Kalman是一个非常实用的方法,能有效提高水下推算船位的精度。

北太平洋低纬西边界流系特征变化研究

利用美国国家环境预报中心(NCEP)的长时间序列(1983—2012年)海流再分析资料,对北太平洋低纬度西边界流的表层分布特征、流量月变化特征及其之间的相关性进行了初步分析。结果表明:北太平洋低纬度西边界流具有明显的季节变化特征,在位置变化上表现出夏季北移,冬季南移的特征;在流速变化上表现出夏强冬弱的特征;在流量运输上表现出NEC、KC和MC的春夏季节流量运输大于秋冬季节的流量运输,而NECC则相反的特征。另外,从各海流与NEC的相关性分析上看,NEC与KC、MC为正相关,与NECC为负相关。

Observational evidence of the Yellow Sea warm current

The Yellow Sea Warm Current (YSWC) is one of the principal currents in the Yellow Sea in winter. Former examinations on current activity in the Yellow Sea have not observed a stable YSWC because of the positioning of current meters. To further understand the YSWC, a research cruise in the southern Yellow Sea was carried out in the winter of 2006/2007. Five moorings with bottom-mounted acoustic Doppler current profilers (ADCP) were deployed on the western side of the central trough of the Yellow Sea. The existence and distributional features of the YSWC were studied by analyzing three ADCP moorings in the path of the YSWC in conjunction with conductivity-temperature-depth (CTD) data over the observed area in the southern Yellow Sea. The results show the following. (1) The upper layer of the YSWC is strongly influenced by winter cold surge; its direction and speed often vary along a south-north axis when strong cold surges arrive from the north. (2) The YSWC near the bottom layer is a stable northwest flowing current with a speed of 4 to 10 cm/s. By combining the analyses of the CTD data, we speculate that the core of the YSWC may lie near the bottom. (3) On a monthly average timescale, the YSWC is stably oriented with northward flow from the sea surface to the sea floor.

Tidal current observation in the southern Yellow Sea in the summers of 2001 and 2003

Direct current observations in the Yellow Sea interior are very scarce due to intense fishing and trawling activities. Most previous studies on tides in the area were based on coastal measurements or satellite altimeter sea levels and have not been rigorously compared with direct measurements. In this paper, tidal currents are studied with current profiles from three bottom-moored Sontek Acoustic Doppler Profilers (ADPs) deployed in the southern Yellow Sea in summer of 2001 and 2003. The measured current series were dominated by tidal currents. Maximum velocities are between 40–80 cm/s at the mooring stations. M2 current is the most dominant primary tidal constituent, while MS4 and M4 are the most significant shallow water tides with much smaller amplitudes than the primary tides.

A STUDY OF PARTITIONING Q VECTOR ON BACKGROUND CONDITIONS OF A TORRENTIAL RAINFALL OVER SHANGHAI,CHINA ON 25 AUGUST 2008

A rainfall that occurred during 0200–1400 Beijing Standard Time(BST)25 August 2008 shows the rapid development of a convective system,a short life span,and a record rate of 117.5 mm h-1for Xujiahui station since 1872.To study this torrential rainfall process,the partitioning method of Q vector is developed,in which a moist Q vector is first separated into a dry ageostrophic Q vector(DQ)and a diabatic-heating component.The dry ageostrophic Q vector is further partitioned along isothermal lines in the natural coordinate to identify different scale forcing in adiabatic atmosphere,and the large-scale and convective condensational heating in non-uniform saturated atmosphere,convective condensational heating, and Laplace of diabatic heating that includes radiative heating and other heating and cooling processes,are calculated to study the forcing from diabatic heating.The effects of the environmental conditions on the development of the rainfall processes are diagnosed by performing the partitioning of Q vector based on 6-hourly NCEP/NCAR Final Analysis(FNL)data with the horizontal resolution of 1°×1°.The results include the following:(1)a low-pressure inverted trough associated with the landfall of Typhoon Nuri (2008),a strong southwesterly jet along the western side of the subtropical high,and an eastward-propagating westerly low-pressure trough provide favorable synoptic conditions for the development of torrential rainfall;(2)the analysis of DQ vector showed that the upward motions forced by the convergence of DQ vector in the lower troposphere(1000–600 hPa)favor the development of torrential rainfall.When DQ vector converges in the upper troposphere(500–100 hPa),upward motions in the whole air column intensify significantly to accelerate the development of torrential rainfall;(3)the partitioning analysis of DQ vector reveals that large-scale forcing persistently favors the development of torrential rainfall whereas the mesoscale forcing speeds up the torrential rainfall;(4)the calculations of large-scale condensational heating in non-uniform saturated atmosphere,convective condensational heating, and Laplace of diabatic heating showed that the forcing related to diabatic heating has the positive feedback on the convective development,and such positive feedback decays and dissipates when the convective system propagates eastward and weakens.

Current observations in the southern Yellow Sea in summer

Current data from three moored Acoustic Doppler Profilers (ADPs) deployed in the southern Yellow Sea at sites A (1-24.17°E, 34.82°N), B (122.82°E, 35.65°N) in summer 2001 and site C (120.85°E, 34.99°N) in summer 2003 were analyzed in this paper. Features of the tidal and residual currents were studied with rotary spectral and cross-spectral methods. Main achievements were as follows: 1) Tides dominated the currents. At sites A and B, the semidiurnal tidal current was basically homogeneous in the whole depth, taking a clockwise rotation at site A, and near-rectilinear counterclockwise rotation at site B; while the diurnal tidal current was strong and clockwise near the surface, but decreased and turned counterclockwise with depth; at site C, semidiurnal tidal current dominated and diurnal current took the second, both of which were counterclockwise and vertically homogeneous. Inertial motion contributed to the clockwise component of diurnal fluctuations; 2) The 3-5d fluctuation of residual current was found at site C and attributed to the response of current to meridional wind, with a lag time of approximately 1.8d; 3) Mean residual flows at sites A and B in 2001 probably suggested an anticyclonic inner circulation in the middle of the southern Yellow Sea in summer.

Dynamics of the Currents in the Strait of Khuran in the Persian Gulf

The Strait of Khuran is among the most important marine habitats in the Persian Gulf. It is the location of the largest Avicennia Marina mangroves along the Persian Gulf shoreline and is a major nursery region for the fish and to breeding, wintering and migrant water birds. This paper presents dynamics of the currents in the Strait of Khuran using the current data collected by fixed current meters. The analysis of the data showed that the currents in the Strait of Khuran were highly dominated by tidal forcing with mixed semi diurnal behavior. The tidal currents were strong and reached to a maximum velocity of 123 cm/s in the spring tide. Tidal analysis showed that the tidal current constituents （M2, $2, N2, K1, O1） are dominant with M2 component as the major one. The tidal currents occurred basically along the strait. The results show a westward residual flow along the strait with an average of 5.6 cm/s during the study. The direction of the flow indicates that any pollution discharged into the industrial developing eastern part of the strait has the potential to affect the sensitive ecosystem in the western part.

Logistic Regression for Evolving Data Streams Classification

Logistic regression is a fast classifier and can achieve higher accuracy on small training data.Moreover,it can work on both discrete and continuous attributes with nonlinear patterns.Based on these properties of logistic regression,this paper proposed an algorithm,called evolutionary logistical regression classifier(ELRClass),to solve the classification of evolving data streams.This algorithm applies logistic regression repeatedly to a sliding window of samples in order to update the existing classifier,to keep this classifier if its performance is deteriorated by the reason of bursting noise,or to construct a new classifier if a major concept drift is detected.The intensive experimental results demonstrate the effectiveness of this algorithm.

Assimilation of High Frequency Radar Data into a Shelf Sea Circulation Model

High Frequency(HF) radar current data is assimilated into a shelf sea circulation model based on optimal interpolation(OI) method. The purpose of this work is to develop a real-time computationally highly efficient assimilation method to improve the forecast of shelf current. Since the true state of the ocean is not known, the specification of background error covariance is arduous. Usually, it is assumed or calculated from an ensemble of model states and is kept in constant. In our method, the spatial covariances of model forecast errors are derived from differences between the adjacent model forecast fields, which serve as the forecast tendencies. The assumption behind this is that forecast errors can resemble forecast tendencies, since variances are large when fields change quickly and small when fields change slowly. The implementation of HF radar data assimilation is found to yield good information for analyses. After assimilation, the root-mean-square error of model decreases significantly. Besides, three assimilation runs with variational observation density are implemented. The comparison of them indicates that the pattern described by observations is much more important than the amount of observations. It is more useful to expand the scope of observations than to increase the spatial interval. From our tests, the spatial interval of observation can be 5 times bigger than that of model grid.

Model for seawater fouling and effects of temperature,flow velocity and surface free energy on seawater fouling

A kinetic model was proposed to predict the seawater fouling process in the seawater heat exchangers.The new model adopted an expression combining depositional and removal behaviors for seawater fouling based on the Kern–Seaton model.The present model parameters include the integrated kinetic rate of deposition(k d)and the integrated kinetic rate of removal(k r),which have clear physical signi ficance.A seawater-fouling monitoring device was established to validate the model.The experimental data were well fitted to the model,and the parameters were obtained in different conditions.SEM and EDX analyses were performed after the experiments,and the results show that the main components of seawater fouling are magnesium hydroxide and aluminum hydroxide.The effects of surface temperature,flow velocity and surface free energy were assessed by the model and the experimental data.The results indicate that the seawater fouling becomes aggravated as the surface temperature increased in a certain range,and the seawater fouling resistance reduced as the flow velocity of seawater increased.Furthermore,the effect of the surface free energy of metals was analyzed,showing that the lower surface free energy mitigates the seawater fouling accumulation.