Ice response to an underwater body moving in a frozen channel

Strains in the ice cover of a frozen channel, which are caused by a body moving under the ice at a constant speed along the channel, are studied. The channel is of rectangular cross section, the fluid in the channel is inviscid and incompressible. The ice cover is modeled by a thin viscoelastic plate clamped to the channel walls. The underwater body is modeled by a three-dimensional dipole. The intensity of the dipole is related to the speed and size of the underwater body. The problem is considered within the linear theory of hydroelasticity. For small deflections of the ice cover the velocity potential of the dipole in the channel is obtained by the method of images without account for ice deflection in the leading order. The problem of a dipole moving in the channel with rigid walls provides the hydrodynamic pressure on the upper boundary of the channel, which corresponds to the ice cover. This pressure distribution does not depend on the deflection of the ice cover in the leading approximation. The deflections of ice and the strains in the ice cover are independent of time in the coordinate system moving together with the dipole. The problem is solved numerically using the Fourier transform along the channel, the method of normal modes across the channel, and the truncation method for resulting infinite systems of linear equations. It was revealed that the strains in the ice strongly depend on the speed of the dipole with respect to the critical speeds of the hydroelastic waves propagating along the frozen channel. The width of the channel matters even it is much larger than the characteristic length of the ice cover.     

全姿态水下移动平台模式切换姿态控制研究

为了适应复杂海洋环境中多样性的观探测任务需求,本文提出了一种融合Argo浮标、水下滑翔机（Glider）和自治式水下机器人（Autonomous Underwater Vehicle,AUV） 3种工作模式的全姿态水下移动平台（All-attitude Multimode Underwater Vehicle,AMUV）。首先,基于3种水下移动平台的工作原理,建立了AMUV的六自由度动力学模型;然后,针对动力学模型中的非线性耦合特性及模式切换过程中的驱动位形变化等问题,基于比例、积分、微分控制器（Proportional Integral Derivative,PID）与模糊控制概念,设计了不依赖于数学模型的自适应模糊PID姿态控制器,实现了AMUV多模式切换过程中的姿态控制;最后,开展多模式切换控制仿真实验,将自适应模糊PID控制器与传统PID控制器仿真结果进行对比,并设计了全模式任务工况,仿真结果表明,本文提出的控制器能够精确和稳定地控制AMUV进行多种工作模式的相互切换。     

广西天气预报视频会商系统网管软件的操作及常见问题诊断

简要介绍广西天气预报视频会商系统中心控制平台的基本操作方法,并针对在业务运行中出现的常见故障,进行原因分析,并找出解决方法。     

Design of a prototype ocean current turbine—Part I: mathematical modeling and dynamics simulation

The “C-Plane” is a submerged variable depth ocean current turbine that is tethered to the sea floor and uses sustained ocean currents to produce electricity. As part of the development of a $\frac{1}{30}$th scale physical model of the C-Plane, a mathematical model and dynamics simulation of the prototype was developed and is presented in this paper. This three-dimensional mathematical model represents the C-Plane as a rigid body with moveable control surfaces that is moored with three linear elastic cable elements. Gravitational, buoyancy, hydrodynamic, cable, gyroscopic, and inertial forces are included and a PC-based dynamics simulation is created. The simulation demonstrates that the C-Plane is stable and capable of changing depth in all expected operating conditions. The C-Plane prototype can fly level from a height of 3 to 6 m using the configuration suggested in this paper. The maximum ascent rates of the C-Plane with a water speed of 0.3 m/s are 0.015 m/s when the pitch is fixed at 0° and 0.030 m/s when the pitch is fixed at 4°. The maximum descent rates of the C-Plane are 0.018 m/s when the pitch is held at 0° and 0.031 m/s if the pitch is held at −4°.     

闽江口水下三角洲的形成与演变 Ⅱ．水下三角洲平原

闽江口水下三角洲的形成与演变全文从分析控制或影响闽江口水下三角洲发育的环境因素、入手,探讨了闽江口水下三角洲的地貌特征、成因及演变。研究结果表明,闽江口水下三角洲属于构造－潮控型三角洲,其地貌特征和成因与典型的潮成三角洲既有共同点,也存在着较大的差异。此外,其近期地貌的发育和演变亦受到人类工程活动的重大影响。这些结论可为闽江口航道综合整治工程提供科学理论依据。本文为其第二部分,主要探讨闽江口水下三角洲平原的地貌特征及演变。     

MS-FORTRAN图形接口及其应用程序设计方法

本文着重讨论了 Ｍ ｉｃｒｏｓｏｆｔ Ｆ Ｏ Ｒ Ｔ Ｒ Ａ Ｎ ５．１ 系统（下面简称 Ｍ Ｓ Ｆ５．１ 系统）的图形接口、数据结构以及输出图元的过程,并用实例说明了图形应用程序的设计方法。     

基于WEB方式下的DST视频终端中远程监控技术的实现

文章提出并实现了一种基于现有硬件视频会商/会议系统的在线可控的远程监控功能。通过和鼎视通技术人员合作,利用DST视频终端,通过B/S的方式,依托高可靠的音频、视频处理技术,以"全程全网全视频"系统为嵌入点,开发并实现了远程实时监控功能。用户可以通过身份认证和优先级别授权使用该系统,实现对远程站点的实时监控。     

改进Yolo-v3的视频图像火焰实时检测算法

为解决现有视频图像火焰检测方法精度低、速度慢的问题,提出了改进Yolo-v3的视频火焰实时检测算法.首先,在特征提取阶段,通过进一步融合多尺度特征提高网络对图像浅层信息的学习能力,以实现小火焰区域的精准识别;其次,在目标检测阶段,利用改进的K-means聚类算法优化多尺度先验框以适应火焰不同尺寸;最后,在改进Yolo-...