排序方式: 共有16条查询结果,搜索用时 15 毫秒
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提出了激励和接收均使用电容式叉指换能器(Capacitive Interdigital Transducers,CIDT)的集成化的电容式Lamb波器件。利用电容式叉指换能器直接激励和接收Lamb波非对称模式的方式,解决了机电耦合效率的问题。在分析各种电容检测电路的基础上,针对Lamb波电容式检测的特殊性,选择了直流电路法来进行接收电容变化规律的测量。为说明直流电路法的适用性,设计了波动检测验证实验。实验结果表明:用直流电路法测量得到的声波信号与其理论计算值之间误差仅为2.4%,证明了直流电路法的适用性,解决了目前Lamb波器件的功能材料层的制作工艺均与传统集成电路工艺不兼容的问题。 相似文献
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为了解决飞秒激光高脉冲能量冲击打孔中时存在微裂纹等问题,提出了飞秒激光旋切加工方法。本文利用脉宽为120 fs的飞秒激光,选择0.5 mm厚度的304不锈钢进行旋切打孔实验。实验研究了激光旋切加工中离焦量和光楔的相对偏转角对孔直径的影响,以及激光离焦量对微孔锥度的影响。结果表明,随着离焦量的增大,孔径增大,同时锥度会减小后增加,当离焦量为0时,锥度最小为3.5°;微孔直径随之双光楔相对转角的增大而增大。此外实验发现冲击打孔孔壁出现微裂纹而旋切微孔的孔壁出现了纳米周期性条纹。 相似文献
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介绍了采用金属银作阳极的特殊结构有机电致发光技术,阐述了利用表面处理和增加缓冲层方法提高阳极空穴注入的原珲,分析了各种技术的优缺点,并提出了利用蒸镀有机薄膜改善载流子注入的方法. 相似文献
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改进型飞秒写制长周期光纤光栅及其高温特性 总被引:5,自引:5,他引:0
基于双CCD对光纤夹持运动系统进行五维初步定 位,通过计算机控制运动平台和飞秒 激光,采用改进型的逐点扫描 方法在未经载氢的SMF-28光纤纤芯区域进行矩形区域扫描,降低了逐点刻写法对聚焦光点 与纤芯对准的敏感性,成功刻写出 在1250~1400nm波段主谐振峰值达-19dB的长 周期光纤光栅(LPFG),光栅长为16.5mm。对写制的LPFG进行高温 特性分析,实验获得其在300~800℃范围主谐振峰的温 度响应灵敏度达到139.27pm/℃,线性度为0.993。研究表明:改 进型的飞秒激光逐点扫描方法稳定可靠,刻写的光栅尺寸小,并且光栅在高温范围有很高 的响应灵敏度,特别适用于高温检测。 相似文献
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恒弹性合金的加工对表面质量和加工精度的要求越来越高,为了实现对恒弹合金的精密定量去除,本文探索了采用飞秒激光烧蚀的加工新方法。首先,分析计算了在高强度飞秒激光辐照加工下,恒弹性合金材料的烧蚀阈值;其次,实验研究了飞秒激光脉冲能量和脉冲个数对该材料上烧蚀加工微坑的直径和深度的影响,结果表明:恒弹性合金的飞秒激光烧蚀阈值为0.167 J/cm2;可以通过增大脉冲能量来增大烧蚀坑直径,通过增大脉冲数来增大烧蚀坑深度。脉冲烧蚀坑直径上限为150.64 μm,运用飞秒激光旋切加工方法,可获得直径为500 μm的微孔,提高了飞秒激光烧蚀加工的能力。 相似文献
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ZnAlLa-CO 3 layered double hydroxides (LDHs) with different Zn/Al/La molar ratios were prepared by the constant pH coprecipitation method. The synthetic materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer-Emmett-Teller method (BET) and particle analysis. The results showed that the hydrotalcite-like materials had a layered structure. The ZnAlLa-CO 3 -LDHs as stabilizers were mixed with PVC resin. The tests of thermal aging, mass loss test and Congo red for the PVC composites were carried out at 180±1 oC, respectively. The results showed that ZnAlLa-CO 3 LDHs used as single thermal stabilizers could enhance both the long-term thermal stability and initial thermal stability of PVC, and 2.4 phr (parts per hundred PVC resin) ZnAlLa-CO 3 -LDHs with Zn/Al/La (molar ratio)=20/8/2 had a better stabilizing effect on PVC than others. Compared with single thermal stabilizers, the composite thermal stabilizers including 0.3 phr calcium stearate (CaSt 2 ), 0.4 phr β-diketone and 2.4 phr ZnAlLa-CO 3 -LDHs significantly enhanced the thermal stability of PVC sample. And rare earth ion could optimize the conformation of PVC and refrain the initiation of the thermal stability and the thermal stable time was over 220 min. The main reason could be concluded to the special structure of rare earth ion, which had longer atom radius and more coordination numbers. So the rare earth ion (RE δ+ ) could react with the labile chlorine atoms (Cl r- ) to form a stable coordinate complex. 相似文献