射频控制器1805B直流替代原理及校准

四线法是精确测量小电阻时最常用的一种方法。射频控制器1805B作为微波功率计自动校准装置中（系统ⅡA）的重要组成部分，它的直流替代电路是由三个臂的惠斯通电桥组成，其每四个臂可以用两个100Q的标准电阻等效代替。通过对标准电阻两端直流电压的准确测量，就可判断1805B在各档的直流替代功率是否满足要求，本文最后给出了直流替代功率所对应的直流电压范围。     

清梳联应用梳针的剖析

就清梳联系统应用梳针的情况进行了剖析，从分梳、纤维损伤等方面指出了梳针的优越性，说明梳针将是未来发展的方向。     

非晶丝微磁化线圈磁电阻抗效应研究

本文研究了铁基及钴基非晶态合金丝在由微磁经线圈所产生的轴向交变磁场的作用下所呈现的磁电阻抗效应，经出了一些测试结果，结果表明，微磁化线圈两端的电压信号峰－峰值随轴向外磁场Ｈｅ的增加而单调减少，钴基非晶丝可呈现巨磁电阻抗效应，利用该效应可制成新型磁敏元件及器件。     

汽车用线缆的新发展

本文介绍随着汽车工业的现代化而对汽车内所用的电线电缆的改进。这些改进主要是用双金属线(铜包钢和铜包铝)来替代传统的铜导线;用新型的可交联聚酯弹性体来替代传统的绝缘材料。其主要目的在于减小线缆的尺寸和重量,增加了线缆的柔软性、耐热水性和耐热性等机械物理性能。文章描述了这些新产品的开发、性能试验和应用。     

基于小波变换的钢丝绳检测信号分析

介绍了小波变换的基本概念,利用小波变换的变焦特性和局部化性质对漏磁法钢丝绳检测信号进行了多分辨率分析。结果表明,该方法在奇异信号检测和局部化分析方面具有优异特性,小波变换可以聚焦到信号的细节,适合突变信号的时频分析处理。     

旁路带电作业在架空配电线路检修上的应用分析

文章通过引入旁路带电作业的概念,介绍了旁路带电作业在架空配电线路上的具体应用(包括应用范围,特制工器具和具体的应用检修项目),并重点分析了旁路带电作业在带电更换架空线路导线和带电更换配电变压器上的应用。     

Determination of corrosion rate of orthodontic wires based on nickel‐titanium alloy in artificial saliva

The goal of this study was to determine corrosion behavior of three orthodontic wires based on nickel‐titanium alloy (NiTi) in artificial saliva at temperature of 37 °C as function of immersion time. Following orthodontic wires were used: uncoated (NiTi), rhodium coated (Rh NiTi) and nitrified (N NiTi) orthodontic wires. Corrosion of investigated orthodontic wires were monitored by measuring of Ni²⁺ and Ti⁴⁺ ions released in artificial saliva by inductively coupled plasma‐optical emission spectroscopy (ICP‐OES) after 3, 7, 14, 21 and 28 days of immersion. Obtained results indicate that corrosion reaction of the NiTi wires in artificial saliva follows the parabolic rate law. According to the obtained values of parabolic corrosion rate constants, corrosion susceptibility of orthodontic wires decreases in the following order: Rh NiTi wire (K_p = 2.48 μg²/cm⁴ h) > NiTi wire (K_p = 1.6 × 10^–3 μg²/cm⁴ h) > N NiTi wire (K_p = 6.0 × 10^–4 μg²/cm⁴ h). These results indicate that in comparison with uncoated NiTi wire, rhodium coating significantly increases corrosion susceptibility, while nitrification effectively suppresses the release of Ni²⁺ and Ti⁴⁺ ions.     

Thermally stabilized MgB2 composite wires with different barriers

Glidcop sheathed in situ MgB₂ wires with Nb and Ti barriers and Cu and Al inner cores have been made and tested. It was found that the inner aluminium stabilization is not appropriate, due to a reaction with Nb during the heat treatment at 630 °C. Using Ti barriers, much higher J_c values were obtained when compared to Nb barriers. The enhancement by 1.5 to 2.1 times is explained by the absorption of impurities from MgB₂ filaments by titanium. On the other hand, Ti reacts with copper and reduces the conductivity of metallic sheath (RRR ratio), which affects the thermal stabilization of the MgB₂ wire.     

对流换热对覆冰导线高频融冰温度分布的影响

根据流体力学的基本原理,应用有限元分析软件ANSYS建立覆冰导线高频融冰时的外流场模型,得到覆冰导线高频融冰时的周围空气流场、压力场分布规律及覆冰导线表面对流换热差异性。分析了高频融冰过程中的热量损失和对流换热的影响因素,通过电磁与热分析,揭示了高频激励融冰过程呈不均匀非对称融冰规律,覆冰导线迎风侧压力大、温度低,背风侧压力小、温度高,表明不均匀对流换热使覆冰导线背风侧先融化,迎风侧后融化。在环境温度和覆冰厚度一定的条件下,覆冰导线外表面温度随对流换热系数的增大而降低。