Application of the Spectrum Peak Positioning Technology Based on BP Neural Network in Demodulation of Cavity Length of EFPI Fiber Optical Sensor

An Extrinsic Fabry-Perot Interferometric (EFPI) fiber optical sensor system is an online testing system for the gas density. The system achieves the measurement of gas density information mainly by demodulating the cavity length of EF- PI fiber optical sensor. There are many ways to achieve the demodulation of the cavity length. For shortcomings of the big intensity demodulation error and complex structure of phase demodulation, this paper proposes that BP neural net-work is used to locate the special peak points in normalized interference spectrum and combining the advantages of the unimodal and bimodal measurement achieves the demodulation of the cavity length. Through online simulation and actual measurement, the results show that the peak positioning technology based on BP neural network can not only achieve high-precision demodulation of the cavity length, but also achieve an absolute measurement of cavity length in large dynamic range.

Reflective Ladder Topology Network Based on White Light Fiber-Optic Mach-Zehnder Interferometer

In order to improve the multiplexing capability of the optical sensors based on the lower interferential optic fiber sensing technology and the white light fiber-optic Mach-Zehnder interferometer,reflective ladder topology network ( RLT) with tailored formula was proposed. The topology network consists of 6 rungs sensing elements linked by 5 couplers. Two cases with different choices of couplers were contrasted: one is equal coupling ratio,and the other is tailored coupling ratio. Through the simulation of these two cases,the detailed multiplexing capability was analyzed,and accordingly the experiments were also carried out. The simulation results showed that,the tailored formula enhances the multiplexing capability of the structure. In the first case, the maximum number of sensors which can be multiplexed is 8,and in the other case is 12 fiber optic sensors. The experimental results have a good agreement with numerical simulation results. Thus,it is considered expedient to incorporate RLT into large-scale building,grounds,bridges,dams,tunnels,highways and perimeter security.

Combined Transmission Interference Spectrum of No Core Fiber and BP Neural Network for Concentration Sensing Research

To investigate wavelength response of the no core fiber（NCF）interference spectrum to concentration,a three-layer back propagation（BP）neural network model was established to optimize the concentration sensing data.In this method,the measured wavelength and the corresponding concentration were trained by a BP neural network,so that the accuracy of the measurement system was optimized.The wavelength was used as the training set and got into the input layer of the three layer BP network model which is used as the input value of the network,and the corresponding actual concentration value was used as the output value of the network,and the optimal network structure was trained.This paper discovers a preferable correlation between the predicted value and the actual value,where the former is approximately equal to the latter.The correlation coefficients of the measured and predicted values for a sucrose concentration were 1.000 89 and 1.003 94;similarly,correlations of0.999 51 and 1.018 8 for a glucose concentration were observed.The results demonstrate that the BP neural network can improve the prediction accuracy of the nonlinear relationship between the interference spectral data and the concentration in NCF sensing systems.

Design and Implementation of MAC Layer in 155.520Mbps Broadband Fiber Optic MAN

The fiber optic technology has matured to the point where Metropolitan Area Networks(MAN)can be built to operate at speeds from 150Mbps to more than 1Gbps.This paper in-troduces an experimental fiber optic MAN.The topology of this MAN is an open looped dualbus,and the data rate at each bus is 155.520 Mbps.We apply ATM technique and modified802.6 DQDB MAC protocol,using universal packet switching.The cell format is completelycompatible with B-ISDN cell.Through gateway the MAN can be interconnected with theBroadband Data Microwave Network,VSAT,Satellite Broadcast TV System,and Ether-net.There are up to 254 nodes connecting to the network,and the distance between two ad-jacent nodes covers more than 5 kilometers.We use 1.3μm SMF as the transmission medi-um.This paper emphasizes on the design and implementation of the Medium Access Control(MAC)Protocol.

Structural Damage Assessment by an Embedded Fiberoptic Sensor Array and Its ANN Signal Processor

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Anycast Transmission in Routing Modulation Level Spectrum Assignment (RMLSA) Problem on Space Division Multiplexing (SDM) Elastic Optical Networks (EON)

With the rise of cloud computing in recent years, a large number of streaming media has yielded an exponential growth in network traffic. With the now present 5G and future 6G, the development of the Internet of Things (IoT), social networks, video on demand, and mobile multimedia platforms, the backbone network is bound to bear more traffic. The transmission capacity of Single Core Fiber (SCFs) may be limited in the future and Spatial Division Multiplexing (SDM) leveraging multi-core fibers promises to be one of the solutions for the future. Currently, Elastic optical networks (EONs) with multi-core fibers (MCFs) are a kind of SDM-enabled EONs (SDM-EON) used to enhance the capacity of transmission. The resource assignment in MCFs, however, will be subject to Inter-Core Crosstalk (IC-XT), hence, reducing the effectiveness of transmission. This research highlights the routing, modulation level, and spectrum assignment (RMLSA) problems with anycast traffic mode in SDM-EON. A multipath routing scheme is used to reduce the blocking rate of anycast traffic in SDM-EON with the limit of inter-core crosstalk. Hence, an integer linear programming (ILP) problem is formulated and a heuristic algorithm is proposed. Two core-assignment strategies: First-Fit (FF) and Random-Fit (RF) are used and their performance is evaluated through simulations. The simulation results show that the multipath routing method is better than the single-path routing method in terms of blocking ratio and spectrum utilization ratio. Moreover, the FF is better than the RF in low traffic load in terms of blocking ratio (BR), and the opposite in high traffic load. The FF is better than the RF in terms of a spectrum utilization ratio. In an anycast protection problem, the proposed algorithm has a lower BR than previous works.

Loading Localization by Small-Diameter Optical Fiber Sensors

Structural health monitoring(SHM)in service has attracted increasing attention for years.Load localization on a structure is studied hereby.Two algorithms,i.e.,support vector machine(SVM)method and back propagation neural network(BPNN)algorithm,are proposed to identify the loading positions individually.The feasibility of the suggested methods is evaluated through an experimental program on a carbon fiber reinforced plastic laminate.The experimental tests involve in application of four optical fiber-based sensors for strain measurement at discrete points.The sensors are specially designed fiber Bragg grating(FBG)in small diameter.The small-diameter FBG sensors are arrayed in 2-D on the laminate surface.The testing results indicate that the loading position could be detected by the proposed method.Using SVM method,the 2-D FBG sensors can approximate the loading location with maximum error less than 14 mm.However,the maximum localization error could be limited to about 1 mm by applying the BPNN algorithm.It is mainly because the convergence conditions(mean square error)can be set in advance,while SVM cannot.

A Novel Packet Switch Node Architecture for Contention Resolution in Synchronous Optical Packet Switched Networks

Packet contention is a key issue in optical packet switch (OPS) networks and finds a viable solution by including optical buffering techniques incorporating fiber delay lines (FDLs) in the switch architecture. The present paper proposes a novel switch architecture for packet contention resolution in synchronous OPS network employing the packet circulation in FDLs in a synchronized manner. A mathematical model for the proposed switch architecture is developed employing packet queuing control to estimate the blocking probability for the incoming traffic. The switch performance is analyzed with a suitable contention resolution al-gorithm through the computer simulation. The simulation results substantiate the proposed model for the switch architecture.

考虑信息泄露影响的光纤传感网络传输数据安全导入方法

为了提高对光纤传感网络传输数据安全传输能力,提出基于信息泄漏加密传输的光纤传感网络传输数据安全导入方法。采用离散混沌时间序列同步调制方法实现对光纤传感网络传输数据导入过程中调制编码处理,根据混沌随机编码特性实现对光纤传感网络传输数据过程中的同步输出稳定性调节和自主随机编码,构建光纤传感网络信息传输泄漏抑制的加密密钥,通过Logistics映射实现对光纤传感网络传输数据导入过程中的信息泄漏加密重传,根据光纤传感网络传输数据的混合敏感密钥表征和算术编码,实现信息泄漏控制和数据安全导入。实验结果表明,采用该方法进行光纤传感网络传输数据导入的加密性能较好,其光纤传感网络传输数据已加密比特序列的识别率为98%,误码率仅为2.7∗10-9%,抗泄漏能力达到了0.970,并且导入后的数据完整度达到了0.996,说明该方法具备了较强的加密效果、抗泄漏能力,实现数据的安全导入和加密传输。

物联网环境下复杂光纤通信传输网络节点调度

为了解决物联网环境下,光纤通信传输网络节点能耗高、调度效率低的问题,提出一种物联网环境下复杂光纤通信传输网络节点调度方法。在物联网环境下,分析光纤通信传输网络节点的分布情况,根据动态联盟理论,以最快调度速度和最小投资为目标,构建复杂光纤通信传输网络节点调度模型。通过蚁群和粒子群算法相结合的融合算法展开全部搜索,获取最佳调度方案,实现光纤通信传输网络节点调度。实验结果表明,所提方法的节点平均能耗在6.0 mJ以下,LBF值始终高于0.20,且节点调度耗时始终低于200 ms,具有良好的调度效果。

浅谈配网自动化光纤通信系统施工技术

为了保证配网自动化光纤通信系统的稳定运行和信号的可靠传输,论文简要介绍了配网自动化光纤通信系统,对配网自动化光纤通信技术在施工过程中的施工要求、关键要点和注意事项进行了探究。

Use Single－chip Computer to Realize Automatic Compensation for Optical Fiber Sensors

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Combined optical fiber interferometric sensors for the detection of acoustic emission

A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms,so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors,and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system,so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the frequency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the frequency characteristics.

基于非相干光频域反射的多芯光纤网络链路缺陷智能检测

为了保证通信安全稳定、数据传输完整,提出了一种基于非相干光频域反射的多芯光纤网络链路缺陷智能检测。先构建多芯光纤网络数学模型,约束光纤节点映射和频谱分配,使频谱数量最少的同时占用的频隙数最大。然后利用分簇检测建立数据传输链路模型,得出通信传输函数,根据相关匹配滤波器调整链路,通过波特间隔均衡完成链路数据采集。最后运用非相干光频域反射步进频率调制产生的瑞利散射光波,结合傅里叶逆变换获得网络健康状况空间分布位置,实现多芯光纤网络链路缺陷智能检测。实验结果表明,所提方法能够准确检测出链路缺陷,对链路阻塞缺陷检测、链路平均故障风险检测率、链路频谱利用率缺陷检测误差分别小于0.4%、0.2%和0.5,且检测时长控制在1.5 s以内,可帮助网络及时恢复运行。

基于光纤传感的铁路牵引网故障自动识别方法

由于现有的铁路牵引网故障识别方法在识别过程中易受到周围环境影响,故障识别准确率较低,因此,提出基于分布式光纤传感的铁路牵引网故障自动识别方法。构建三种牵引网故障自动识别规则,通过自动识别规则,使用分布式光纤传感对故障特征进行提取;使用变量分析对故障损伤数据进行处理,筛选符合传输的故障损伤数据进行传输,计算故障损伤数据,运用网络拓扑结构对故障特征信息进行传输;通过融合层次的诊断,进行数据的融合,得到诊断结果,实现基于分布式光纤传感的铁路牵引网故障自动识别。搭建仿真模拟模型进行实验,通过实验结果表明:在10种不同的故障类型条件下,本文设计方法在对牵引网故障损伤自动识别中,准确率最高可达到93.35%,故障识别效果较好,可满足对铁路牵引网故障自动准确识别的需求,具有一定的实际应用价值。

基于分布式光纤的蜂窝夹层结构脱粘损伤监测

航空航天蜂窝夹层结构服役环境恶劣,需要发展相应的结构健康监测技术以保证结构的安全运行。脱粘损伤因发生在内部胶层而难以监测,该文采用埋入胶层的分布式光纤传感器对蜂窝夹层结构脱粘损伤进行监测。在预埋损伤监测试验中采用高强光纤和边界浅槽的方式提高传感器存活效率,得到脱粘损伤应变特征。采用参数化建模方式对不同损伤位置进行大量有限元模拟,加入白噪声后得到含有脱粘损伤特征的13500组数据。将模拟数据代入卷积神经网络进行训练,训练后的网络对试验损伤数据的识别准确率达到98.84%。该方法能够识别20 mm^(2)脱粘损伤,同时定位平均误差小于4 mm。

深度学习在光纤通信系统损伤补偿中的应用

随着社会信息化程度的逐步提升,人们对光纤通信系统容量的需求持续增长。信道损伤一直是限制光纤通信容量提升的关键因素,信道损伤补偿作为光纤通信系统的基础性功能和关键技术也在不断改进。近年来,将深度学习应用到光纤通信信道损伤补偿中更是吸引了不少研究人员的关注。文章介绍了近年来应用于光纤通信中的常见深度学习模型,阐述了深度学习技术在光纤通信系统信号损伤补偿方面的发展情况。

远程光纤传感网中滤波降噪方法的优化

为实现远程光纤传感网络在噪声干扰条件下的高精度检测传输,提出一种优化差分(optimized difference,OD)的降噪方法。基于移动平均法构建新差分算法,并结合低通算法、中值算法预判边缘信息及预测信号数值;采用双重判别弥补边缘信息误判的缺陷,优化准确定位边缘信息的能力;融合加权平均法与卡尔曼滤波器(Kalman filter,KF),优化信号预测的精度。实验验证结果表明:采用该方法进行数据预处理将使系统能够正常检测数据,测量精度可达0.76%,提高检测系统的抗噪性能。与先进小波阈值降噪方法的对比实验结果表明:斜率优化方法在≥10 dB噪声干扰下,测量精度相对提高0.62倍以上。

持续性灾害下风险感知的光网络业务恢复算法

【目的】地震等自然灾害具有持续性和大范围的特性。灾害在发生过程中会持续性损伤光网络的链路资源,造成其链路风险不断变化。面对持续变化的链路风险,业务恢复规划不当可能导致恢复业务再次发生故障。从业务角度来看,重复故障将导致数据传输的多次中断,且随着灾害发生,后续的链路状态损伤加剧可能导致无法恢复此业务。从网络管控方面来看,重复恢复会造成算路资源浪费,占用其他业务的恢复资源。同时,由于业务传输的数据重要性不同,不同业务对传输可靠性的需求存在差异,在发生故障时,高重要度业务应优先恢复。因此,在大规模持续性灾害场景下,综合考虑灾害对链路风险的持续性影响以及不同业务对路径可靠性需求的差异性进行业务恢复是一个值得研究的问题。文章针对此问题提出了一种持续性灾害下基于链路风险感知的业务恢复算法——动态链路风险重路由算法(DLRRA)。【方法】首先,针对业务重要度和链路风险,文章建立了业务重要度与链路风险评估模型,并在此基础上提出了优化目标路由可靠度。DLRRA结合优化目标充分考虑了灾害对链路持续性影响造成的链路风险度变化,通过优先为高重要度的故障业务分配低风险的恢复资源,避免了在灾害持续发生过程中同一高重要度业务发生2次故障的风险。【结果】仿真结果表明,DLRRA恢复的首次业务较传统算法的2次故障概率降低了11%,且在高负载下的平均重要度提高了10%。【结论】因此,该算法有效避免了持续性故障造成的业务多次中断带来的损失,保证了重要业务在灾害环境中的持续稳定运行。