高速单体船航行性能与结构力学特征综合优化初步研究

建立高速单体船航行性能与结构力学特征综合优化的数学模型,将遗传算法改进成一种适应多目标和多约束的算法,并将其应用于高速单体船航行性能与结构力学特征综合优化计算问题,利用界面友好的VC 软件编程。优化结果表明,改进的遗传算法计算可靠、效率高,并为设计综合性能优良的高速单体船船型准备了良好的基础条件。     

Database of sail shapes versus sail performance and validation of numerical calculations for the upwind condition

A database of full-scale three-dimensional sail shapes is presented with the aerodynamic coefficients for the upwind condition of International Measurement System (IMS) type sails. Three-dimensional shape data are used for the input of numerical calculations and the results are compared with the measured sail performance. The sail shapes and performance were measured using sail dynamometer boat Fujin. This is a boat of 10.3-m length overall in which load cells and CCD cameras were installed to simultaneously measure the sail forces and shapes. At the same time, the sailing conditions of the boat, e.g., boat speed, heel angle, wind speed, and wind angle, were measured. The sail configurations tested were: mainsail with 130% jib, mainsail with 75% jib, and mainsail alone. Sail shapes were measured at several vertical positions for the shape parameters defined by: chord length, maximum draft, maximum draft position, entry angle at the luff, and exit angle at the leech, all of which finally yield three-dimensional coordinates of the sail geometry. The tabulated shape data, along with aerodynamic coefficients, are presented in this article. In addition, numerical flow simulations were performed for the measured sail shapes and the sailing conditions to investigate the capability and limitations of the methods through detailed comparison with the measurements. Two numerical methods were used: a vortex lattice method (VLM) and a Reynolds-averaged Navier–Stokes (RANS)-based computational fluid dynamics method. The sail shape database, in association with the numerical results, provides a good benchmark for the sail performance analysis of the upwind condition of IMS type sails.     

Analysis of velocity fluctuations and their intermittency properties in the surf zone using empirical mode decomposition

We consider here surf zone turbulence measurements, recorded in the Eastern English Channel using a sonic anemometer. In order to characterize the intermittent properties of their fluctuations at many time scales, we analyze the experimental time series using the Empirical Mode Decomposition (EMD) method. The series is decomposed into a sum of modes, each one narrow-banded, and we show that some modes are associated with the energy containing wave breaking scales, and other modes are associated with small-scale intermittent fluctuations. We use the EMD approach in association with a newly developed method based on Hilbert spectral analysis, representing the probability density function in an amplitude–frequency space. We then characterize the fluctuations in a stochastic framework using a cumulant generating function for all scales, and compare the results obtained from direct and classical structure function analysis, to EMD–Hilbert spectral analysis results, showing that the former method saturates at large scales, whereas the latter method is more precise in its scale approach. These results show the strength of the new EMD–Hilbert spectral analysis method for data presenting a strong forcing such as found in shallow water, wave dominated situations.     

船舶柴油机性能监测分析仪的研制

船舶柴油机性能监测分析仪是一种基于现代测试与计算机技术,能适用于实船环境的柴油机示功图测试设备,该仪器主要由压力传感器、曲轴转角传感器、数据采集器和计算机软件组成,具有上止点标定、示功图主要指示性能指标计算与分析、测量数据的数据库管理等和报表输出等功能,为船舶柴油机性能监测与故障诊断提供了有效的技术手段.     

一种船舶电力滤波器的仿真研究

在小型船舶电力推进系统中,变频驱动产生了严重的谐波污染,导致电力系统的容量大大增加,恶化电网电能质量,甚至影响了船舶安全运行.针对电力推进船舶电网存在的谐波污染问题,设计了电力滤波器的拓扑结构,制定其控制策略,分析该滤波器的工作原理,并进行计算机仿真,验证了该滤波器的有效性.     

导管架下水驳船的“浮托法”安装改造研究

导管架下水驳船是实施大型深水导管架下水的必要装备。“浮托法”安装模式是大型平台组块海上安装的发展趋势。对“海洋石油229”号导管架下水驳船“浮托法”安装改造前、后的总体性能进行了对比分析。     

斜拉索PE施工性能分析与安装参数选择

以苏通长江公路大桥为依托,通过斜拉索PE护套的施工性能试验,研究长、重索在提升过程中PE的拉伸受力情况、吊索夹具夹紧斜拉索时PE护套的抗压受力情况以及PE护套同索夹橡胶垫间的摩擦系数,从而选定相关施工参数。在整个斜拉索安装过程中没有出现任何索夹滑移或PE护套压伤的情况,确保了斜拉索的施工安全、质量与使用寿命。     

鄂东长江公路大桥宽箱梁C55高性能混凝土试验研究

结合鄂东长江公路大桥边跨预应力混凝土宽箱梁的施工,重点研究了掺入适量矿物掺合料、聚丙烯纤维对箱梁C55高性能混凝土的物理力学性能和长期耐久性的影响。试验结果表明,采用聚羧酸盐高效减水剂,掺入20％Ⅰ级粉煤灰或15％粉煤灰与10％矿粉复掺配制的箱梁C55高性能混凝土具有良好的工作性能、较高的早期强度和较大的后期强度增长,以及很高的抗氯离子渗透性和抗冻性,特别是具有较低水化热温升、较小收缩和徐变变形特性,有利于改善箱梁混凝土的抗裂性。     

静载锚固性能试验影响因素分析

结合铁路工程钢绞线一锚具组装件的静载锚固性能试验检测,对影响试验结果的各种因素进行了分析,并指出相应的解决措施。提出试验过程的有效控制是试验科学性和数据结果可靠性的有力保证。     

加纤维沥青混凝土用于桥面铺装的路用性能及施工研究

通过研究普通及纤维沥青混合料各项路用性能及力学性能,表明添加纤维能显著改善沥青混合料的高温稳定性、低温抗裂性及水稳定性能,并且能有效地增加混合料的整体性与柔韧性,适于作为桥面铺装材料。