基于LabVIEW的“海院1号”波浪发电平台浮筒取能效率数据采集系统设计

浮筒取能效率测试是波浪发电平台研究的重要组成部分。传统的测试系统不但测量精度低,而且自动化程度低、操作复杂。为此,该文基于“海院1号”波浪发电平台,采用虚拟仪器LabVIEW软件开发了浮筒取能效率数据采集系统。文中介绍了“海院1号”波浪发电平台及其浮筒,进行了测试系统的设计,实现了浮筒取能效率测试的数据采集、数据管理、曲线拟合及绘制、生成报表、信号分析以及数据处理等工程。对实际运行效果进行分析,结果表明该系统具有精度高、运行稳定可靠、自动化程度高、人机界面友好以及操作简单等特点,具有重要的工程实践意义。     

低阻通风船体的远程控制测试平台开发（英文）

This paper addresses the development and testing of a remotely controlled boat platform with an innovative air-ventilated hull. The application of air cavities on the underside of ship hulls is a promising means for reducing hydrodynamic drag and pollutant emissions and increasing marine transportation efficiency. Despite this concept’s potential, design optimization and high-performance operation of novel air-cavity ships remain a challenging problem. Hull construction and sensor instrumentation of the model-scale air-cavity boat is described in the paper. The modular structure of the hull allows for easy modifications, and an electric propulsion unit enables self-propelled operation. The boat is controlled remotely via a radio transmission system. Results of initial tests are reported, including thrust, speed, and airflow rate in several loading conditions. The constructed platform can be used for optimizing air-cavity systems and testing other innovative hull designs. This system can be also developed into a high-performance unmanned boat.     

A havelock source panel method for near-surface submarines

A panel method is described for calculating potential flow around near-surface submarines. The method uses Havelock sources which automatically satisfy the linearized free-surface boundary condition. Outputs from the method include pressure field, pressure drag, wave resistance, vertical force, trim moment and wave pattern. Comparisons are made with model tests for wave resistance of Series 58 and DARPA SUBOFF hulls, as well as with wave resistance, lift force and trim moment of three length-to-diameter variants of the DSTO Joubert submarine hull. It is found that the Havelock source panel method is capable of determining with reasonable accuracy wave resistance, vertical force and trim moment for submarine hulls. Further experimental data are required in order to assess the accuracy of the method for pressure field and wave pattern prediction. The method is implemented in the computer code “HullWave” and offers potential advantages over RANS-CFD codes in terms of speed, simplicity and robustness.     

A non-geometrically similar model for predicting the wake field of full-scale ships

The scale effect leads to large discrepancies between the wake fields of model-scale and actual ships, and causes differences in cavitation performance and exciting forces tests in predicting the performance of actual ships. Therefore, when test data from ship models are directly applied to predict the performance of actual ships, test results must be subjected to empirical corrections. This study proposes a method for the reverse design of the hull model. Compared to a geometrically similar hull model, the wake field generated by the modified model is closer to that of an actual ship. A non- geometrically similar model of a Korean Research Institute of Ship and Ocean Engineering (KRISO)’s container ship (KCS) was designed. Numerical simulations were performed using this model, and its results were compared with full-scale calculation results. The deformation method of getting the wake field of full-scale ships by the non-geometrically similar model is applied to the KCS successfully.     

Experimental and numerical investigations on vibration characteristics of a loaded ship model

In this paper, vibration characteristics of the structure in the finite fluid domain are analyzed using a coupled finite element method. The added mass matrix is calculated with finite element method (FEM) by 8-node acoustic fluid elements. Vibration characteristics of the structure in finite fluid domain are calculated combining structure FEM mass matrix. By writing the relevant programs, numerical analysis on vibration characteristics of a submerged cantilever rectangular plate in finite fluid domain and loaded ship model is performed. A modal identification experiment for the loaded ship model in air and in water is conducted and the experiment results verify the reliability of the numerical analysis. The numerical method can be used for further research on vibration characteristics and acoustic radiation problems of the structure in the finite fluid domain.     

Numerical calculation of supercavitating flows over the disk cavitator of a subsonic underwater projectile

To deal with the effect of compressible fluids on the supercavitating flow over the subsonic disk cavitator of a projectile, a finite volume method is formulated based on the ideal compressible potential theory. By using the continuity equation and Tait state equation as well as Riabouchinsky closure model, an “inverse problem” solution is presented for the supercavitating flow. According to the impenetrable condition on the surface of supercavity, a new iterative method for the supercavity shape is designed to deal with the effect of compressibility on the supercavity shape, pressure drag coefficient and density field. By this method, the very low cavitation number can be computed. The calculated results agree well with the experimental data and empirical formula. At the subsonic condition, the fluid compressibility will make supercavity length and radius increase. The supercavity expands, but remains spheroid. The effect on the first 1/3 part of supercavity is not obvious. The drag coefficient of projectile increases as the cavitation number or Mach number increases. With Mach number increasing, the compressibility is more and more significant. The compressibility must be considered as far as the accurate calculation of supercavitating flow is concerned.     

使用有限元分析以改善重载运输车轴

分析了北美铁路货运发生的车轴故障,介绍了使用有限元对F级和K级车轴进行应力分析计算,研究车轴尺寸变化对应力的影响,并提出了改善重载车轴设计的建议.     

轿车与6岁儿童行人不同方位碰撞中下肢损伤分析

Euro NCAP发布的行人模型认证技术公告TB024的最新版本对6岁儿童行人模型认证提出了单独要求,旨在加强对儿童行人的保护.本研究应用符合Euro NCAP技术公告(TB024)规定并且具有详细解剖学结构的6岁儿童行人有限元模型,设置了4组不同方位行人-汽车碰撞仿真试验,以探究不同碰撞方位下的儿童下肢损伤机理.结果...     

ISS-based robust adaptive fuzzy algorithm for maintaining a ship's track

This paper focuses on the problem of linear track keeping for marine surface vessels. The influence exerted by sea currents on the kinematic equation of ships is considered first. The input-to-state stability(ISS) theory used to verify the system is input-to-state stable. Combining the Nussbaum gain with backstepping techniques,a robust adaptive fuzzy algorithm is presented by employing fuzzy systems as an approximator for unknown nonlinearities in the system. It is proved that the proposed algorithm that guarantees all signals in the closed-loop system are ultimately bounded. Consequently,a ship's linear track-keeping control can be implemented. Simulation results using Dalian Maritime University's ocean-going training ship 'YULONG' are presented to validate the effectiveness of the proposed algorithm.     

Determinants of the property damage costs of bulk barge accidents

This study investigates determinants of the vessel, cargo, and other-property damage costs of bulk barge accidents in US inland waterways. Tobit estimation of a three-equation recursive model suggests that, in bulk barge accidents: (1) vessel damage cost is greater for collision, fire/explosion, and material/equipment failure accidents than for groundings; (2) cargo damage cost is greater at night and when the weather is foggy and increases with barge age; and (3) otherproperty damage cost is greater for multi-vessel accidents, but decreases with barge size. A dollar of vessel damage cost increases other-property damage cost by $1.38, while a dollar of cargo damage cost increases this cost by $6.90. An important result for formulating bulk barge accident cost-reduction policies is that a given determinant might have a negative effect on one type of damage cost but a positive effect on another.