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二硼化镁(MgB2)超导体在非铜氧化物陶瓷超导体中具有最高临界转变温度,给超导应用带来了新的契机.铁与镁不反应,且价格低廉,在需要热处理的超导成材工艺中,常常采用铁作MgB2的基底;然而,这种高磁导率的材料有可能增大基底的损耗.本文采用有限元分析软件ANSYS计算了工频下不同材料基底超导圆线传输交流的基底损耗,分析了基底损耗与电流大小、基底厚度之间的关系,对双层基底的损耗也进行了研究.本文的结果对于适当选取截面尺寸、基底材料和工作电流以期减小交流损耗,具有一定参考意义. 相似文献
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在结构设计解决周视光电观瞄设备的动态密封问题后,动密封所带来的摩擦力矩就成为周视光电稳定的重要制约因素。通过对3种典型应用动密封原理的周视光电观瞄设备分析研究,着重分析了动密封的摩擦力矩对结构、稳瞄精度的影响,并结合实际工程应用给出3种动密封形式所对应的摩擦力矩分析和估算方法,提供给稳瞄和结构设计人员,以期对后续稳瞄系统设计有所帮助。最后在同一周视转台上,对3种动密封进行了试验验证并进行分析计算,得出磁流体是解决周视光电设备动密封较好形式的结论。 相似文献
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本文采用MgB2/Fe/Cu单芯复合线材制作了一个小型实验线圈,并以此为基础,对用MgB2线、带材制成的线圈在承载较大电流情况下的交流损耗特性进行了仿真和实验研究,结果表明,为使MgB2/Fe/Cu复合线材适于电力应用,应设法大幅降低基体损耗. 相似文献
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Calibration-free wavelength modulation spectroscopy for gas concentration measurements under low-absorbance conditions 下载免费PDF全文
<正>We derive the expressions of the first and second harmonic signals on the basis of absorption spectral and lock-in theories,and determine the gas concentration according to the ratio of second and first harmonic signals.It is found that the X and Y components of the harmonic signals are influenced by the phase shift between the detection and reference signal,and the phase shift can be any value in a range from 0 to 2π,which is different from the results obtained previously.Meanwhile,an additional item caused by the residual amplitude modulation will make a great contribution to the second harmonic signal,and may not be neglected under low absorbance conditions.Theoretical analysis indicates that subtracting back-ground signal from the second harmonic signal can remove the influence of this item,and can improve the measurement accuracy of gas concentration.On this basis,we select the transition of CO2 at 6527.64 cm-1 to analyse the approximation errors during the derivation by numerical simulation and then measure the CO2 concentration under low absorbance conditions,with absorbance varying from l%o to 6‰. 相似文献