海上航标的信息化表述方法

航标是海上交通运输的重要设施,航标的信息化应用对海上航行和支持国家经济建设具有重要意义。对航标的类型、作用进行了一般性的论述,分析了航标功能作用的各种物理特性表达方式,以海上航标为例描述了应用层面对功能作用的不同物理特性表现形式,探讨了航标信息化过程中的数字化和可视化表述方法,最后阐述了航标信息系统中表述方法的多样性和选用原则。     

DELPH平台下PLC控制多楔带测试机的设计

多楔带性能优越,得到了广泛的实际应用。文章介绍了在delphi平台下PLC控制的多楔带测量机的实现,包括PLC的通讯设置、上位机的界面等,高精度地自动测量多楔带的各种参数。     

装备维修备件需求预测模型研究

准确的备件需求预测是合理有效地进行备件保障各项工作的基础,在综合分析考虑备件消耗影响因素的基础上,建立了备件需求预测模型。该模型可用于备件的管理决策,提高备件保障率。     

一种基于模型的水声弱信号检测方法(英文)

Detection of weak underwater signals is an area of general interest in marine engineering. A weak signal detection scheme was developed; it combined nonlinear dynamical reconstruction techniques, radial basis function (RBF) neural networks and an extended Kalman filter (EKF). In this method chaos theory was used to model background noise. Noise was predicted by phase space reconstruction techniques and RBF neural networks in a synergistic manner. In the absence of a signal, prediction error stayed low and became relatively large when the input contained a signal. EKF was used to improve the convergence rate of the RBF neural network. Application of the scheme to different experimental data sets showed that the algorithm can detect signals hidden in strong noise even when the signal-to-noise ratio (SNR) is less than −40d B.     

边界任意弹性约束薄板的横向振动(英文)

This paper presents an analytical study on the influence of edge restraining stiffness on the transverse vibrations of rectangular plate structure. An improved Fourier series method was employed to analyze the transverse vibration of plate structure with general elastically restrained boundary conditions. A linear combination of a double Fourier series and eight auxiliary terms was sought as the admissible function of the flexural displacement of the plate, each term being a combination of a polynomial function and a single cosine series expansion. The auxiliary terms were introduced to ensure and improve the smoothness of the original displacement function and its derivatives at the boundaries. Several numerical examples were given to demonstrate the validity and accuracy of the current solution. The influences of translational and rotational stiffness on the natural frequencies and mode shapes of plate were analyzed by numerical results. The results show that the translational stiffness has bigger influence on the natural frequencies than the rotational stiffness. It is generally well known that little change of the rotational stiffness has little influence on the mode shapes of plate. However, the current work shows that a very little change of rotational stiffness value may lead to a large change of the mode shapes of a square plate structure.     

错层式钛合金球鼻首导流罩结构形式研究

针对有特殊声学要求的球鼻首导流罩,为满足其透声要求,提出错层式钛合金球鼻首导流罩的结构形式。首先提出了基本结构形式,分析了这种结构形式下连接结构的水密性、结构方案的经济性。运用有限元计算方法对结构强度进行了校核,并对声学性能进行了分析。研究表明：这一结构形式能够满足声呐特殊的工作要求,且结构设计可行。     

一种新型船舶建造进坞浮箱的设计

本文介绍了一种为西江船厂建造的10艘34m金枪渔船从广西柳州出海而专门设计的进坞浮箱,对浮体形式优选、渔船进出坞过程的稳性、浮箱本身的稳性、浮箱与船体间的连接方法设计,及该浮箱的实际应用情况进行了论述。     

未知环境中水下无人航行器的路径规划方法

针对水下无人航行器路径规划需要提前获得海图以得到全局障碍物信息,难以做到未知环境下实时规划路径的问题,提出一种对探测空间进行采样并判断采样点是否具有障碍,最终将探测到的障碍结果加权赋值给A*算法待扩展点的方法,实现了探测与路径规划同步进行,同时考虑到航行器的运动学约束,将A*算法的搜索域修正为圆域并且仅搜索在运动学约束...     

Highway Tunnel Blasting Vibrations and Cracking of Adjacent Residential Houses北大核心CSCD

A systematic analysis and discussion of the causes of house cracking are conducted by testing the blast vibration velocity of typical neighboring houses, analyzing the types of house cracking, monitoring the characteris-tics of house cracks and calculating the temperature stress at the roof and wall based on an assessment of highway tunnel blasting vibrations leading to cracking of neighboring houses. The results show that the main cause of house cracking adjacent to the tunnel is temperature stress, not blasting vibration. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

基于实测数据的最大波高公式探究

在海岸及海洋防灾减灾以及设计波浪的推算中,最大波高的计算是至关重要的。基于瑞利分布的最大波高公式,不能体现谱宽因素的影响,由该公式得出的理论最大波高要高于实际值。通过分析挪威海10年实测波浪定点观测数据,发现随着谱宽的增加,H_(max)/H_s逐渐减小,并拟合出包含谱宽参数的最大波高公式,简单易用,实用性强。