Author Affiliations
Abstract
Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, P. R. China
With the rapid development of modern industries, the high-temperature piezoelectric sensors that can work in extreme environments are in great demand. In this work, langasite (La3Ga5SiO, LGS), as a high-temperature piezoelectric crystal with stable electro-elastic performance, is used as core element, and air and porous Al2O3 are selected as backing layers respectively to prepare two kinds of high-temperature acoustic emission (AE) sensors. The detection sensitivities at 25–500∘C are analyzed by the ball falling test and Hsu–Nielsen experiment. Under the condition of 25–500∘C, the received amplitude signals by both sensors are maintained above 90dB stimulated by the ZrO2 ceramic ball dropping. In the Hsu–Nielsen experiment, as the temperature rising from 25∘C to 500∘C, the signal amplitude of sensor with air backing layer decays from 447mV to 365mV, while the signal amplitude varies from 270mV to 203mV for the sensor with porous Al2O3 backing layer. Significantly, compared with the bandwidth of the air-backing sensor (37–183kHz), the sensor with porous Al2O3 backing layer broadens bandwidth to 28–273kHz. These results show that both these AE sensors have strong and stable response ability to AE signals at high-temperature of 500∘C. Therefore, piezoelectric AE sensor based on LGS has great potential application in the field of high-temperature structural health monitoring.
La3Ga5SiO14 acoustic emission sensor sensitivity structural health monitoring Journal of Advanced Dielectrics
2024, 14(1): 2342001
1 中国航空工业集团公司洛阳电光设备研究所,河南 洛阳 471009
2 空基信息感知与融合全国重点实验室,河南 洛阳 471009
针对离轴光学系统装调过程中自由度高且互相耦合的问题,提出一种新的离轴自由曲面反射式光学系统装调方法,采用计算全息图(CGH)实现多镜共基准定姿定态,解耦合系统各镜片的装调自由度,显著降低系统装调复杂度;分析CGH用于定姿定态时的定位精度,提高系统装调精度和效率,适应不同构型的离轴光学系统。利用上述方法,完成口径为、视场为的近红外长波红外双波段离轴反射式光学系统装调,全视场波像差RMS小于(),达到设计预期,装配周期短,成像质量优良。
光学设计 计算全息图 离轴三反 自由曲面
1 河北科技大学材料科学与工程学院, 石家庄 050018
2 河北省柔性功能材料重点实验室, 石家庄 050018
3 河北环瑞化工有限公司, 石家庄 050035
研制高性能隔热材料对发展航空、建筑、运输等领域具有重要意义。二氧化硅(SiO2)纤维具有低密度、低热导、抗氧化的优点, 是一种极具发展潜力的隔热材料。然而, SiO2纤维的热导率有待进一步降低, 如何进一步提升其隔热性能是一个重要课题。本文从SiO2纤维的隔热机理出发, 首先分析了不同形貌(实心、中空、多孔)SiO2纤维的制备方法及研究现状, 并总结了SiO2纤维与有机材料、无机材料等复合的研究进展。同时, 简述了隔热材料目前的主要应用领域, 最后展望了SiO2纤维基隔热材料在未来的发展方向。
二氧化硅 纤维 隔热 复合材料 silica fiber thermal insulation composite
1 苏州大学应用技术学院,江苏 苏州215325
2 同济大学 航空航天与力学学院,上海 200092
近年来,为了使加工技术更加精准、无误差,各国研究者投入到了微加工领域的研究。而飞秒激光以其极高的峰值、较小的损伤阈值、高的聚焦力,使其成为国内外在微加工领域的热点研究对象。总结了近年来飞秒激光在微加工领域的研究进展,并从微加工金属材料、集成光学、生物医疗、纳米加工领域进行综述,最后指出飞秒激光发展到现在所存在的问题及对未来的期想。
微加工 飞秒激光 损伤阈值 集成光学 micromachining femtosecond laser damage threshold integrated optics
Author Affiliations
Abstract
1 School of Physics, University of Science and Technology of China, Hefei 230026, China
2 Southwestern Institute of Physics, Chengdu 610041, China
System validation and density fluctuation calibration of phase contrast imaging (PCI) on an HL-2A tokamak are presented. Signals from different channels show not only a pronounced modulation of an incident laser beam induced by a sound wave, but also an excellent magnification and low image distortion of optics. The frequency-wavenumber spectrum is achieved by using two-dimensional Fourier transform of time series signals. The conversion coefficient between detected signal amplitude and chord integral plasma density fluctuation is 2.35 × 1013 m 2/mV, which promises a suitable signal level at the order of volts of the PCI in typical HL-2A discharges.
120.5050 Phase measurement 150.1488 Calibration 350.5400 Plasmas 120.5060 Phase modulation Chinese Optics Letters
2018, 16(12): 121201