6-DOF主动波浪补偿液压平台的结构优化分析

开展6-DOF船用主动波浪补偿液压平台结构优化设计,旨在提升波浪补偿液压平台承载和空间补偿能力,减小补偿平台体积和质量。依据海浪运行形态给定六自由度船用波浪补偿液压平台所需的补偿参数指标,利用虚拟样机技术,在ADAMS软件仿真环境中建立该平台的参数化模型;以其最大负载为优化目标,对该参数化模型的结构尺寸进行优化,得到该平台结构尺寸的优化结果。结果表明：优化后,六自由度船用波浪补偿液压平台的负载能力较最初增加了约15%,支腿液压缸的行程减小了约13%,平台负载能力提升且结构更加紧凑合理。为检验此次对平台结构尺寸优化的有效性,利用SolidWorks软件建模,并导入ADAMS软件中仿真,检验了模型的补偿能力。     

FeCuNbSiB非晶带材/环氧树脂复合材料界面设计及其吸波性能

针对FeCuNbSiB非晶带材与环氧树脂基体不浸润的难题,本文通过表面化学改性,在FeCuNbSiB非晶带材两面分别生成一层厚度5μm~10μm、相结构为Cu_0.75Fe_2.25O₄和Fe₃O₄的界面层。界面层与带材结合强度高,与环氧树脂浸润性好;以FeCuNbSiB非晶带材为增强材料,同时按FSS网络设计的FeCuNbSiB非晶带材/环氧树脂铺层在13-18GHz频带出现R=-5dB~-10dB的吸收峰。增加铺层数,吸收峰值不变,但吸收峰频带往低频率方向移动。利用此特性可以修正其它复合材料的雷达波吸波特性,拓宽吸收频带,增加吸波性能。     

露天矿垂直与斜深孔爆破特征分析

根据永平铜矿实际爆破情况,运用爆轰理论,对露天矿垂直与倾斜两种中深孔的爆破特征进行了分析.分析从底盘抵抗线、孔网参数、大块与粮底、钻孔效率与作业成本和爆破地震效应五个方面入手,阐述了两种不同类型钻孔的不同爆破作用机制及其爆玻效果,肯定了倾斜孔在露天台阶爆破中所具有的独特优越性.     

小波分析在信号消噪中的应用

用小波分析进行信号消噪常用多尺度小波变换和小波包变换.多尺度小波变换是将信号分解成高频和低频成分,低频包含信号的主要性能,高频含较多噪声,将高频平滑后再重建即可消噪.其消噪处理有强制、默认阈值和给定软/硬阈值3种方法.小波包变换消噪是将信号的小波包分解、计算最佳小波包基、分解系数的阈值化处理及重构原来信号实现消噪.并给出了几个Matlab消噪函数:多尺度一维小波分解和重构wavedec及waverec、消噪默认阈值ddencmp和消噪函数wdencmp;小波包变换的ddencmp 和wdencmp函数.试验表明,此方法具有较高的有效性和实用性.     

基于声全息的故障诊断方法

基于振动信号的故障诊断方法在某些场合下存在着局限性.机械噪声蕴含着丰富的设备状态信息,而且具有非接触式测量的优点,可以部分地替代振动信号,用于故障诊断.传统的噪声诊断方法主要基于频谱分析,无法反映声源位置和强度 /的变化信息,只能进行初步的故障诊断.基于此,提出一种基于声全息的故障诊断方法.该方法采用由少量传声器组成的阵列测量声压,应用波叠加法重构物体的外部声场,可以方便快速地进行声场可视化.一旦准确地重建出物体的外部声场,就可以利用这些全息场的信息进行故障诊断.通过建立基于全息图的正常状态与故障状态的模板,将机器的运行信息与这些模板对比,就可以判定机器的运行状态,从而进行故障诊断.采用由多个脉动球组成的声源模型进行了数值仿真,并在消声室内对两只音箱噪声源进行了试验研究,都准确地识别出辐射体声场状态变化,找出了故障.从而验证了该方法的正确性和实用性,为其在现场应用打下基础.     

A comparison of two meshing schemes for CFD analysis of the impulse turbine for wave energy applications

This paper presents the comparison of a three-dimensional Computational Fluid Dynamics (CFD) analysis with empirical performance data of a 0.6 m Impulse Turbine with Fixed Guide Vanes used for wave energy power conversion. Pro-Engineer, Gambit and Fluent 6 were used to create a 3-D model of the turbine. A hybrid meshing scheme was used with hexahedral cells in the near blade region and tetrahedral and pyramid cells in the rest of the domain. The turbine has a hub-to-tip ratio of 0.6 and results were obtained over a wide range of flow coefficients. Satisfactory agreement was obtained with experimental results. The model yielded a maximum efficiency of approximately 54% as compared to a maximum efficiency of around 49% from experiment. A degree of insight into flow behaviour, not possible with experiment, was obtained. Sizeable areas of separation on the pressure side of the rotor blade were identified toward the tip. The aim of the work is to benchmark the CFD results with experimental data and to investigate the performance of the turbine using CFD and to with a view to integrating CFD into the design process.     

《小型汽油机振动测试方法》试验方法的讨论

标准GB/T 10398-1989《小型汽油机振动测试方法》提出了小型通用汽油机振动的试验方法,但是未规定振动测试设备参数的设置。在试验中,仪器参数的设置对试验结果有着重要的影响。通过相关理论及实际的试验分析了仪器参数设置对试验结果的影响,并提出相应的解决方法。     

Directivity analysis of ultrasonic waves on surface defects using a visualization method

Ultrasonic testing uses the directivity of the ultrasonic wave, which propagates in one direction. The directivity is expressed as the relationship between the propagation direction and its sound pressure. The directivity of an ultrasonic wave is related to the choice of probe arrangement, testing sensitivity and scanning pitch, and correct measurement of defect size and location. This paper investigated the directivity of ultrasonic waves, which are scattered from a slit defect located in simulated butt weld joint using a visualization method. When the defect size was smaller than the wavelengths, clear directivity in the reflected wave was observed. When the ratio of defect size to wavelength is greater than 1.5, measured directivities almost agree with the theoretical directivity. The directivity of shear waves scattered from the slit defect varied according to probe direction (Far defect, Near defect). The angle of reflection wave became similar to angle of incidence as the height of excess metal in welded joint increased.     

小波变换在管道泄漏在线监测中去噪的应用

对小波变换的基本理论进行了简要的阐述 ,并提出了利用小波变换模极大值消除工程背景噪声的方法 ,给出了小波变换模极大值的算法。最后本文将小波分析方法与波动法结合起来应用到管道泄漏的在线监测中 ,实验结果证明了该方法可以有效地提高波动法对管道泄漏诊断的精度 ,显示了小波变换对信号的去噪声、滤波以及定位等方面具有广泛的应用前景。     

一种有效的转换波静校正方法

转换波技术由于具有常规P波勘探无法相比拟的优点而成为当前地震勘探中的一门新技术。而静校正在转换波勘探中是处理的重点和难点。为此很多学者专家为此提出了各自的解决办法,但是由于转换波静校正问题的复杂性,该问题至今仍尚未圆满解决。本文首先在转换波的CRP（共接收点）叠加剖面上追踪拾取同相轴,然后结合纵波对应层位的地下构造求取接收点的横波静校正量。该方法通过对理论模型和实际资料的试算验证了其有效性。