Design of inductive sensors for magnetic testing of steel ropes

The design and operating principles of four inductive sensors for magnetic testing of steel ropes are presented. The magnetic concentrators can maintain the same shape as in Hall-effect leakage flux sensors, but the output signals of the inductive sensors are quite different and depend on the speed of testing. Although the inductive sensors are not as versatile as Hall-effect sensors, they are simpler in operation and can still find applications, especially in the initial and middle stages of the deterioration of the rope.     

一种改进排序匹配算法在DDM中的应用与实现

数据分发管理功能是降低网络冗余数据的有效手段,它是实现HLA-RTI的关键技术。结合IEEE1516介绍了数据分发管理过滤机制以及传统的匹配方法,在分析排序算法匹配原理的基础上,给出了排序算法实现订购区域与公布区域的匹配策略,针对排序算法在区域数目较大时出现的运行时间长、存储空间占用大的弊端,提出了一种改进的排序算法。通过仿真实验表明改进后的排序算法在区域数目较大时所需的时间开销较少,并且在区域边长发生变化的情况下具有较好的平稳性。     

Improved fish migration optimization method to identify PEMFC parameters

In a worldwide environment context where the emergency need to decrease pollutant emissions is an important issue, the research for solutions is increasing. Fuel cell technology is anticipated to become a practicable approach for solving the problem of pollution due to its environmentally friendly characteristics. In this work, a novel problem formulation is suggested for the efficient recognition of PEMFC parameters which the solving is by using the Improved Fish Migration Optimizer (IFMO) technique. After coding the steps of the algorithm in MATLAB, the objective function is resolved for the fuel cell. Comprehensive simulations evaluate the formulation performance with the suggested and traditional objective functions; then, the outcomes are compared. To confirm the suggested formulation ascendancy compared to the traditional curve-fitting method, a complete assessment based on convergence rate, the value of the objective function, and the value of absolute voltage error are performed. The achieved value of the objective function, absolute voltage error, and average time of computation is 0.005, 0.4, and 1.63, respectively. Environmentally, the combustion of hydrogen and its use in PEMFC produce no carbon dioxide.     

Influences of processing conditions on mechanical properties of recycled epoxy-anhydride vitrimers

The chemically crosslinked network structures make epoxies, the most common thermosets, unable or hard to be recycled, causing environmental problems and economic losses. Epoxy-based vitrimers, polymer networks deriving from epoxy resins, can be thermally malleable according to bond exchange reactions (BERs), opening the door to recycle epoxy thermosets. Here a series of experiments were carried out to study the effects of processing conditions (such as particle size distributions, temperature, time, and pressure) on recycling of an epoxy-anhydride vitrimer. Polymer powders from the epoxy-anhydride vitrimer with different size distributions were prepared and characterized, and the influence of particle size on the mechanical performance of recycled epoxy-anhydride vitrimers was investigated by dynamic mechanical analysis and uniaxial tensile test. Experimental results demonstrated that finer polymer powders can increase the contacting surfaces of recycled materials and thus result in high quality of recycled materials. In addition, the influences of other treating parameters, such as temperature, time, and pressure, were also discussed in this study. Adjusting these treating parameters can help the design of an optimized reprocessing procedure to meet practical engineering applications.     

库尔勒土壤环境中X70管线钢剥离涂层下的腐蚀特征

利用矩形剥离缝隙模型研究了库尔勒土壤模拟溶液中X70管线钢剥离涂层下的滞留液化学特征以及X70钢腐蚀特征.随着浸泡时间的延长,缝内滞留液的p H值逐渐下降直至稳定.Cl^-在缝内滞留液中有不同程度的聚集,其中在缝隙底部的质量浓度最高.SO₄^2-的质量浓度在腐蚀初期表现为随距离增加而降低,到腐蚀后期表现为随距离增加而升高.HCO₃^-和NO₃^-的质量浓度从漏点至缝底有小幅降低.阳离子的质量浓度变化不明显.缝内X70钢的腐蚀形貌表现为明显的点蚀,且随距漏点距离的增加,点蚀越严重.     

避免MCVC结构拓扑优化模型出现机构的方法

为了避免带体积约束的柔顺度最小化(minimum compliance with a volume constraint,MCVC)模型出现机构,借助带位移约束的重量最小化(minimum weight with a displacement constraint,MWDC)模型,寻找MCVC模型中安全可靠的物理的或者结构性能的参数阈值.99行程序和120行程序分别被用来求解MCVC和MWDC模型.通过对大量出现机构的病态算例进行研究分析发现,当迭代过程中的最大应变能比小于某个阈值时,或者当体积比大于某个阈值时,就可避免机构出现.然而,这2个阈值是依赖于问题的,即对于不同的结构与/或载荷工况,这2个阈值均会取不同的值.在本文测试的算例中,最大应变能比阈值的范围为4.59~12.38,体积比阈值的范围为0.15~0.26.     

平板式结合面动态建模与参数识别方法

用有限元法对含有平板式结合面的结构进行分析时, 平板本身对结合面层的影响往往会被忽略, 误差也由此产生.针对这种平板结合面刚度的传统计算方法的缺陷进行修正, 综合考虑结合面层和结合面板两者的弹性, 推导出平板式结合面的综合单元刚度矩阵.此刚度矩阵能应用于结合面的有限元计算及动态参数识别当中.通过算例将这种方法与传统方法进行对比验证, 前者具有更高的精确度和可靠性.该方法可应用于此类结构的精确建模与分析, 为解决其振动问题提供手段.     

基于过采样技术的高精度次声信号采集系统

次声电信号的检测要求系统具有很高的分辨率、宽动态范围以及强噪声抑制能力.过采样技术可以简化系统电路,降低生产成本,提高测控系统的分辨率以及现有模数转换器检测次声信号的能力.本系统利用可编程增益仪表放大器的特点,结合过采样技术,使系统实现了高分辨率、宽动态范围的数据采集.实验表明本系统较传统次声信号数据采集系统对信号的还原度更高.     

基于双树复小波包和AR谱的滚动轴承复合故障诊断方法

针对滚动轴承复合故障信号中故障特征难以分离的问题,提出了基于双树复小波包和自回归(autoregressive,AR)谱的故障诊断方法.首先,利用双树复小波包变换将复杂的、非平稳的复合故障振动信号分解为若干个不同频带的分量;然后,对包含故障特征的分量进行希尔伯特包络;最后,对包络信号求其AR功率谱,由此实现对复合故障特征信息的分离和故障识别.实验结果表明:该方法可有效地分离轴承复合故障的特征频率,验证了该方法的可行性和有效性.