新型船用吸声材料泡沫铝

扼要介绍了用熔体发泡法制造泡沫铝的制造过程 ,泡沫铝孔径为 2～ 7mm,孔隙率为 80 %～ 90 % ,最大制品尺寸为 60 0 m× 60 0 mm× (8～ 40 0 ) mm。重点研究了泡沫铝的吸声性能、热学性能、阻尼性能、机械性能、吸湿性能及无毒性能。结果表明 ,泡沫铝是一种综合性能良好的新型吸声材料。平均吸声系数可达 0 .4～ 0 .5 2 ,且随孔径的减小 ,孔隙率、厚度的增大 ,吸声性能提高。压缩加工对泡沫铝的吸声性能有很大影响 ,压缩率为 40 %时 ,吸声性能最好。泡沫铝导热系数仅为未发泡铝的 1 /60 0 ,远远低于大理石 ,也低于石棉板 ;耐火温度可达 80 0℃。其内耗比致密铝高 3～ 7倍 ,比高阻尼 Zn-Al合金高 2～ 4倍。其强度为几个 MPa数量级。它不吸湿 ,吸湿率为 0 .0 % ,无毒性。     

荧光磁粉探伤裂纹智能识别图像处理研究

磁粉探伤的发展趋势是自动化、智能化,而工件表面状况、真伪裂纹、工况条件等使得现有的检测识别方法难以满足工件表面裂纹缺陷自动检测识别的需要。在分析工件表面荧光磁粉图像特征及裂纹缺陷特征的基础上,研究表征裂纹邻域像素空间相关度的二维直方图分布,提出基于多重分块极值的图像边缘检测算法。根据裂纹邻域像素空间相关度参数,以及裂纹缺陷的长宽比、圆形度等特征,设计了基于Fisher线性判别方法的工件裂纹识别算法。以此为基础的荧光磁粉探伤工件裂纹缺陷自动检测识别技术,应用于列车轮轴检测线实时检测,裂纹缺陷的有效检出率达99%。     

大功率电力机车变形吸能元件加工难点及解决措施

对大功率电力机车的牵引缓冲装置变形吸能元件支撑板的功能、结构、主要工艺难点进行分析,介绍一种新型的加工工艺方法,大大地提高了其生产效率.     

汽车吸能转向机构与驾驶员碰撞的仿真与试验

利用非线性有限元方法建立了可收缩吸能转向机构与驾驶员所组成碰撞系统的仿真模型，深入讨论了碰撞仿真模型初始条件与边界条件的处理方法、材料非线性本构关系的选择、接触对摩擦系数的确定。并按照GB11557规定的要求，对人体模块有限元模型进行了验证。分析计算了吸能转向机构与人体模块碰撞时上下套管间的收缩位移和作用在转向柱上的碰撞力，并通过相应的碰撞台架试验验证了仿真结果的正确性。     

太阳能游船光伏逆变器控制系统EMC设计

从船舶环境和光伏逆变器的基本原理和功能出发,分别对太阳能游船EMC干扰源和干扰路径进行分析,通过信号滤波与保护、工艺设计和试验测试,实现高可靠性的太阳能游船光伏逆变器控制系统研究和设计,为太阳能游船的光伏逆变器控制系统研究提供基本EMC设计思路与实现技巧。     

轻集料吸水与释水过程影响因素的试验研究

试验研究了轻集料的品种、密度等级、级配、环境湿度等因素对其吸水、释水过程的影响。结果表明,轻集料的品种对其吸水、释水过程影响最为显著,页岩陶粒的吸水快,0.5 h接近饱水,吸水率小,而粘土陶粒吸水相对缓慢,20 h才接近饱水,吸水率大;页岩陶粒的释水明显比粘土陶粒快,但释水速度均远小于吸水速度,且两种陶粒释水速度的差距明显小于吸水速度的差距;密度等级对页岩陶粒的吸水、释水过程影响较大,而对粘土陶粒的吸水、释水过程影响较小。     

基于危货指数的省级水运安全监管系统研究

受建设时间跨度大、技术条件等限制,加上机构改革,水运安全监管系统存在着展示不系统、覆盖不全面、数据不规范等问题,面对严峻的安全形势、复杂的内河水网和海量的船舶动态信息,现有的安全监管系统不能满足需求.本文分析了省级水运安全监管的内涵,提出危货指数的定义,并以危货指数为核心设计了省级水运安全监管系统,涵盖了运行监测、安全...     

Air pollution history elucidated from anthropogenic spherules and their magnetic signatures in marine sediments offshore of Southwestern Taiwan

Kaohsiung City and its neighborhood in the southwestern coastal plain of Taiwan have suffered serious air pollution since the region became the largest center for heavy-industry on the island. In order to unravel the air pollution history of the region, four ²¹⁰Pb- and ¹³⁷Cs-dated sediment box cores recovered in 2006 from offshore of this area were chosen for magnetic and petrographic analyses. The data were used to distinguish changes in concentration, composition and grain size of magnetic particles in the sediments due to inputs of anthropogenic magnetic spherules. Sedimentation rates have been reasonably constant for the last one hundred years, except at the core tops which were affected by a turbidite layer induced by a typhoon in 2005. Down-core profiles of mass-specific magnetic susceptibility (χ) and saturation isothermal remanent magnetization (SIRM) are similar among the cores, and reflect similar trends to magnetic spherule counts. This reveals that χ and SIRM of modern marine sediments can be used as air pollution indicators for nearby industrialized upwind areas. The studied record indicates that industrialization of the area was gradual during 1950–1980 and boomed afterward, resulting in a high production of airborne magnetic spherules, which is consistent with evidence for poor air quality at that time. Optical and scanning electron microscopic (SEM) surveys of magnetic extracts indicate that the magnetic spherules have grain sizes ranging from a few micrometers up to 50 μm and consist mainly of iron oxides with variable Si, Al, and Ca contents. X-ray diffraction analysis on magnetic extracts from different depths in the cores further indicates that magnetite and pyrrhotite, which are derived from terrigenous detritus, form the magnetic constituents of the sediments before the area was industrialized. In contrast, during the industrial boom, anthropogenic magnetite and hematite spherules became the dominant magnetic particles in the sediments. Down-core profiles of hard isothermal remanent magnetization (HIRM) below the turbidite layer also reveal similar trends to the corresponding magnetic spherule counts, which indicate that the concentration of hematite in the sediments is also closely related to the extent of air pollution. In addition, relatively low values of χ_ARM/χ, which are indicative of coarse magnetic grains, started to occur when large magnetite spherules became significant during the industrialized period. The air pollution history elucidated from our sediment core data not only reflects the development of Kaohsiung from a small village to a highly industrialized metropolitan area in the 20th century, but it is also consistent with the most recent air pollution trends revealed by real time air quality measurements of PM₁₀. Our results demonstrate the usefulness of magnetic parameters for delineating the air pollution history of coastal marine sediments down-wind of nearby industrialized regions.     

磁屏蔽对机车信号环线测试的影响及改进方案

针对传统的机车信号测试环线安装在钢轨内侧轨腰,存在磁屏蔽、安装成本高、施工和维护困难等缺点,在分析了磁屏蔽产生的原因后,设计并实现了一种综合成本低廉、安装方便,避免构成磁屏蔽的机车信号环线测试的技术方案。该技术方案在钢轨上或者水泥地面上通过尼龙支架固定测试环线。实践证明,使用尼龙支架固定测试环线的安装方式效果良好、设计合理,能满足机车信号的正常检测,达到了优化的预期目标。     

汽车工业用磁流变液器件应用前景分析

简要介绍了磁流变液和磁流变效应，详细分析了磁流变液的性能及其影响因素，将其与电流变流进行了对比，表明磁流变液具有很多优点，在此基础上，介绍了磁流变液应用于汽车工业的结构形式，以及在制动，传动和减振降噪域应用的一些器件。对磁流变液应用于汽车的前景进行了分析并指出了存在的问题。