走锚预报数学模型

本文通过对锚泊船进行受力分析和受力计算，应用船舶操纵基本方程，建立了风流浪等外力作用下，锚泊船在浅水、低速、大漂角中的运动方程。通过对船舶运动与锚链受力及锚链受力与锚抓力之间的关系进行研究，提出了一般运输船单锚泊时，在设定的海况下进行走锚预报的数学模型。并利用计算机对实船进行模拟计算，取得了与实际情况比较符合的效果。本文对研制开发走锚预报器提供了理论依据，对于提高锚泊安全性作了一种新的尝试。     

Investigation of turbulent flows in a waterjet intake duct using stereoscopic PIV measurements

Stereoscopic particle image velocimetry measurements were made in a wind tunnel using a prototype waterjet model. The main wind tunnel provided the vehicle velocity and a secondary wind tunnel was set up as the waterjet propulsion model. Pressure distributions along the ramp and lip sides inside the duct were measured for three jet velocity to vehicle velocity ratios. Three-dimensional velocity fields were obtained at the intake entrance and the nozzle exit of the waterjet system. The flow into the duct was faster in the lip region than on the ramp side. Because of the variation in intake geometry from a rectangular to a circular section and because of the sudden curvature change on the lip side, a pair of counter-rotating vortices was observed in the mean velocity field at the nozzle exit. In addition, the turbulent kinetic energy correlated with the vortex pair was stronger on the lip side than in other areas. Dominant large-scale structures were extracted by using a snapshot proper orthogonal decomposition analysis. It was found that most of the turbulent kinetic energy was attributed to at least three vortices near the nozzle exit. This detailed three-dimensional velocity field will be useful for the verification of CFD simulations applied to the waterjet system.     

Effects of wind strength and wave height on ship incident risk: Regional trends and seasonality

Oceanographic conditions like wind strength and wave height affect the risk of shipping incidents. Seasonal variations and trends in these effects are studied for weather-related incidents and pollution incidents, for six major ship types and for six regions across the globe. The employed database of more than five million observations combines information from various sources on oceanographic conditions, ship particulars, and incidents. The magnitude of wind and wave effects is found to vary by ship type, region, season, and period, and most of these effects are larger during the autumn and winter season and in recent periods.     

基于单分类算法OSVM船用燃气轮机状态评估

针对船舶综合监控系统中存储有海量设备正常运行时的数据没有得到充分利用，此外设备退化时的故障数据难以获取，无法训练传统的多分类退化检测模型，提出利用单分类算法OSVM来建立模型,从而实现退化检测，在该过程中只需用正常样本数据来训练模型，并在一个经过实船数据验证过的模拟器产生的数据集上进行了实验。结果显示，只需要400个正常样本就可训练出准确的退化检测模型，该模型在精确度，召回率，特异性，正确率，AUC五个指标都有很好表现，此外，该退化检测模型有很好的扩展性，也可被用于其他机械设备的状态评估中。     

多轴混合动力特种车辆空气动力学特性分析与改进设计

建立某多轴混合动力特种车辆整车外流场仿真模型,采用计算流体力学方法分析整车外流场特性。根据分析结果对驾驶室进气格栅、驾驶室与货箱之间的上部连接、驾驶室下部进风口三个部位进行优化设计。在优化设计过程中,特别关注提升各车桥分布式驱动电机的散热效果,并根据局部外流场特性确定车桥处的电机风扇朝向布置。结果表明,优化后的整车风阻系数降低了6.4%,各车桥均可通过底盘底部的气流分支进行良好冷却,确保满足驱动电机的散热需求。     

百叶窗翅片式散热器性能数值模拟与优化

文章以某百叶窗翅片式散热器为研究对象,取传热因子j、摩擦因子f、综合性能因子JF为量化指标,借助Fluent软件模拟散热器在不同工况下的流场、温度场及压力场分布情况,研究散热器的传热及流阻性能,并通过风洞试验验证仿真结果的可靠性。结合试验结果设计了一种新型孔状百叶窗翅片散热器,与传统百叶窗翅片散热器相比,传热因子最大提高了14.6%,摩擦因子最大减小了9.8%,综合性能因子提高了9.8%-14%,传热及流阻性能有明显提升。     

Comparative analysis between operational weather prediction models and QuikSCAT wind data near the Galician coast

Wind measurements from SeaWinds scatterometer on the NASA QuikSCAT satellite and wind forecasts from two different operational numerical models provided by MeteoGalicia were compared for a 4-year period (2002–2005) in Galician coast environment. Available wind data buoy measurements were also used to complement the analysis. A statistical analysis based on mean errors, root mean square errors and complex correlation was performed from spatial, temporal and directional points of view.In the spatial comparison no significant differences between models and satellite were observed and the error magnitudes of the models are compatible with typical QuikSCAT errors. The suitability of satellite wind estimations for data assimilation in these models must be further investigated. Negative bias of models with respect to the satellite was also confirmed with buoy data, in such a way that models overestimation is smaller than the satellite one. Big errors in wind direction appear in southeasterly and southwesterly winds for both satellite and models, contributing to high RMSE values when compared to buoy data. These errors were mainly attributed to the effect of insufficient spatial resolution near shore.     

基于数值模拟的多用途船风阻力优化研究

以19000t多用途船为研究对象,提出一种基于数值模拟的风阻减阻优化方法。首先,模拟计算迎风状态下船体和上层建筑的风阻力;然后,根据风阻力高压力区域分布结果定性设计风阻力减阻结构方案;最后提出一种基于数值模拟优化的最优减阻结构计算方法,定量计算出最优的风阻力优化结构设计方案。     

大风区铁路避风增加费研究

我国穿越西北大风地区的铁路项目越来越多,现行的相关标准虽然考虑大风施工降效问题,但费用标准偏低且未涵盖技术规程规定等要求的禁止作业情况所需费用,有必要进一步研究完善风区避风增加费。以百里风区施工图投资检算为研究样本,依据现有规范、规程划分避风停工工程范围,按照统计的避风时间占总施工时间的比例以及避风停工施工降效计算避风增加费用。研究结论:(1)风沙地区施工增加费用问题可按大风施工降效费、大风避风增加费和防风加固费等3个方面考虑,宜区分不同情况分别进行处理;(2)风区避风增加费计算方法可为类似项目的费用计算积累丰富经验,同时可为概(预)算编制办法的修订提供参考依据。     

风载荷对货物装载加固强度的影响

介绍自然风载荷及铁路客货列车交会时风压的基本特点,定性分析了风载荷对货物装载加固强度的影响,并借助共用车装载空集装箱的方案进行定量的分析。