共查询到19条相似文献,搜索用时 437 毫秒
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《光子学报》2015,(10)
针对普通石英光纤质地较脆,应用在结构裂缝监测中易发生断裂的现象,本文运用塑料光纤代替普通石英光纤进行结构裂缝监测,并且考虑复合材料裂缝开裂方向的不确定性,对塑料光纤及其裂缝监测能力进行了研究.设计了一套塑料光纤传感装置,并通过裂缝模拟装置来研究塑料光纤分别与裂缝呈30°、45°、60°夹角时,光损耗与裂缝开度的关系.实验结果表明,随着裂缝的开展,光损耗逐渐增加;纤芯直径为0.5mm时最大光损耗幅值为78.76μW,而纤芯直径为0.25 mm时,最大光损耗幅值只有24.28μW,纤芯直径较大的光纤在微弯时易发生较大的光损耗.塑料光纤传感装置在结构裂缝监测中应用是可行性的,而且塑料光纤裂缝传感器的灵敏性随着方位角的增加而降低. 相似文献
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本文给出了刚玉中两类Fe~(3+)离子的自旋哈密顿矩阵的普遍形式,并着重研究了当两类Fe~(3+)离子不等价时,顺磁共振谱的特性。对于两类离子等价情况,计算了当磁场与晶轴的夹角α=0°,15°,30°,45°,54.7°,60°,75°,90°时Fe~(3+)离子的能级。对于两类离子最不等价情况,计算了当α=10°,20°,30°,40°,50°,54.7°,60°,70°,80°时Fe~(3+)离子的能级。并且给出了当α=0°和 90°时各能级的波函数和跃迁矩阵元公式。 在室温下,用ЭПР-2型波谱仪,在3厘米波段,做了蓝宝石的顺磁共振实验。利用使晶体绕两个相互垂直的方向转动的装置,精确地调整晶轴的方向。观察到了分别属于两类Fe~(3+)离子的两套顺磁共振谱线。给出了等价及最不等价情况的等频曲线。 相似文献
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本文给出了刚玉中两类Fe3+离子的自旋哈密顿矩阵的普遍形式,并着重研究了当两类Fe3+离子不等价时,顺磁共振谱的特性。对于两类离子等价情况,计算了当磁场与晶轴的夹角α=0°,15°,30°,45°,54.7°,60°,75°,90°时Fe3+离子的能级。对于两类离子最不等价情况,计算了当α=10°,20°,30°,40°,50°,54.7°,60°,70°,80°时Fe3+离子的能级。并且给出了当α=0°和90°时各能级的波函数和跃迁矩阵元公式。在室温下,用ЭПР-2型波谱仪,在3厘米波段,做了蓝宝石的顺磁共振实验。利用使晶体绕两个相互垂直的方向转动的装置,精确地调整晶轴的方向。观察到了分别属于两类Fe3+离子的两套顺磁共振谱线。给出了等价及最不等价情况的等频曲线。 相似文献
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充分利用光纤光栅传感网络的频域和时域资源,综合考虑了光栅传感环境特点、传感点铺设和维护等因素,提出了一种新型的基于粗时分复用的TDM/WDM光纤传感网络设计方案。先按时分复用方式将光纤传感环境划分成不同时延的传感域,再将域内传感点按波分复用方式进行波分复用,并结合网络拓扑结构分析了网络中的影响测量结果的主要因素。方案引入了传感域和时延容差概念,可以放宽对传感点精确位置的要求,可对传感网进行分域管理,便于替换死亡的传感器,更加方便、简洁地实现大容量光纤光栅传感系统,可依据器件具体情况灵活分配传感域内域外的传感器复用数,使每个传感单元的传感成本显著降低。 相似文献
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基于光纤光栅复用传感原理,结合F-P可调谐滤波技术,采用波分复用与空分复用相结合的方法构建光纤光栅复用传感网络,并对传感网络中的电源、可调谐滤波器、光电探测器、光开关及传感光纤光栅阵列的组成等进行分析和选择,提出了结构优化的分布式、大容量光纤光栅传感网络的组网方案。通过在光路中使用F-P标准具和参考光栅对波长值进行标定和校准,提高了传感系统的测量精度,为构建大容量、高精度、实时性强的光纤光栅传感系统提供了设计参考。分布式大容量光纤光栅传感网络在多点、多参量和大空间范围传感测量领域具有广阔的应用前景。 相似文献
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轴流压气机旋转失速的预示研究 总被引:1,自引:0,他引:1
大量的研究表明,旋转失速现象的发生不仅与压气机工作状态的气动参数有关,而且与压气机几何参数有直接关系。本文的目的是用实验的方法找出影响压气机旋转失速发生的主要因素,通过对实验数据分析研究获得判别失速发生的准则。文中首先对十个低速转子进行试验,其主要几何参数为稠度τ=1.5,轮毂比为0.815,安装角γ分別为45°和60°,弯角θ分别为0°,15°,34°,45°,60°。试验表明:具有各种不同几何参数(弯 相似文献
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高分辨率光纤应变传感系统是地球物理学中地壳微弱形变观测的有力工具.相比于传统的地壳应变观测技术,光纤应变传感器具有测量分辨率高、抗干扰能力强、尺寸小、可复用、易于安装布设等特性,在建立新型地壳形变监测网络中具有很大的应用潜力.本文围绕面向地壳形变观测的纳应变级分辨率光纤应变传感器技术,阐述了应变传感原理与实现超高测量分辨率的机理,并详细介绍了扫频探测、Pound-Drever-Hall解调技术、边带探测、双回路锁定传感、传感器时分复用等技术及相应的传感器系统实现方案,最后,给出了超高分辨率光纤传感器在现场观测的实验结果与分析. 相似文献
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Cuadrado-Laborde C 《Optics letters》2007,32(19):2867-2869
A lensless dual random phase encoding technique in the temporal domain is proposed and analyzed to evaluate its potential application for secure data transmission, mainly for short-haul fiber optic links. The different signal broadening effects produced by each stage of the encoding process in both time and frequency domains are analyzed by using the Wigner distribution function to take into account the fiber's multiplexing capabilities. Thus, quasi-white noise with a well-defined bandwidth is used in the encoding process to limit the bandwidth of the encrypted signal. Numerical simulations revealed good system performance, indicating that this multiplexing encryption method could be a good alternative to other well-established techniques. 相似文献
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This paper describes a fiber optic sensor suitable for remote sensing and multi-point detection of ultrasound. This ultrasound sensor is based on the surface-bonded fiber optic Sagnac interferometer with the output fringe visibility of 1; it consists of a laser source, an ordinary single mode fiber delay line, a fiber coupler, a phase modulator and polarization controllers. For the validation of the sensor, surface acoustic waves and Lamb waves are excited by illuminating a steel specimen with an array of Q-switched Nd:YAG laser-generated line sources and the measurement of laser-generated ultrasonic waves are performed on the specimen surface using the surface-mounting fiber optic Sagnac sensor. The surface-bonded fiber optic sensor developed in this study has a simple configuration for detection of ultrasonic waves. Effectiveness of surface-bonded fiber optic Sagnac sensors for remote sensing of ultrasound and in situ monitoring of structures is investigated. The capability of multi-point detection of ultrasound by this Sagnac sensor is also discussed. 相似文献
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光纤水听器的原理与应用 总被引:23,自引:0,他引:23
为适应水声学应用特别是水下反潜战的需要,在光纤技术不断发展的基础上,光纤水听器应运而生.光纤水听器是一种基于光纤、光电子技术上的新型水下声传感器,因其在军事、民用各领域应用广泛,目前光纤水听器在国内外发展迅速,已经到达实用状态.全光光纤水听器系统的湿端采用全光实现,信号传感与传输皆基于光纤技术.具有抗电磁干扰、重量轻和造价低等优点.文章简述了光纤水听器的发展历史、现状,论述了光纤水听器的原理及其应用前景. 相似文献
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Chang-Yong Yun Dipesh Dhital Jung-Ryul Lee Gyuhae Park Il-Bum Kwon 《Optics & Laser Technology》2012,44(1):269-280
To prevent possible threats to public safety and economic loss from chemical leakage accidents, novel chemical sensing techniques for regular monitoring and leakage detection have been developed for various fields. We propose a fiber optic liquid chemical sensor (FOCS) system using specialty optical fibers and an optical time domain reflectometer (OTDR), and is based on the leaky wave mode sensing principle. OTDR enables simple multiplexing where individual sensor nodes along the fiber length could be interrogated by a common OTDR. The sensor node in the optical fiber is prepared by removing the desired length of a protective layer using mechanical stripping and chemical etching techniques. A novel laser stripping technique with superior capability to fabricate quasi-distributed dense sensor nodes is devised as well. The FOCS system is further analyzed to characterize the sensor response behavior in relation to the sensor node length and possible environmental and chemical temperature effect. Under the condition satisfying the leaky wave mode principle and within the minimum acceptable refractive index (RI) range by the system, this FOCS system could monitor numerous liquid chemicals with variable refractive indices and has been tested with positive results. In addition, the system shows the possibility for multi-point detection and is further expanded into a hybrid technique capable of estimating the refractive index range of the detected chemical. 相似文献
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An experimental demonstration of fiber optic imaging inside a furnace at 1000°C is described, A low-resolution sapphire fiber optic video system was designed, fabricated, and tested for basic performance in a small tube furnace. The imaging fiber bundle was assembled using 100 high-quality sapphire fibers aligned and bonded at each end. Experiments to achieve a high-temperature cladding are described. Reference imaging experiments at room temperature were performed with the sapphire fiber bundle and a commercial glass fiber bundle of comparable sue. Imaging experiments at 1000°C are described and discussed. 相似文献
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甲烷是瓦斯的主要成分,是易燃易爆的气体。介绍了瓦斯的光谱特性以及光谱吸收法测量甲烷气体浓度的原理,给出了光谱吸收型光纤瓦斯气体传感器的主要进展和技术路径,包括差分吸收测量法和谐波吸收测量法。通过分析可看出,光谱吸收型光纤瓦斯传感器以其优良的特性得到了广泛关注,其中差分吸收法的抗干扰能力强,系统可靠性高,具有较强的工程应用价值。 相似文献