基于数字相关匹配的光纤光栅非对称反射峰解调算法研究

光纤布拉格光栅(FBG)在封装时易出现非对称反射峰,传统拟合方式对此现象解调误差大.针对这一问题提出了一种基于数字相关匹配的光纤光栅解调新算法.采用Matlab仿真和水浴实验对此算法进行了检验,证明该算法的可行性及有效性.实验结果表明:在FBG存在非对称反射峰现象时,所提出的算法比传统高斯拟合算法误差减小约67％.基于数字相关匹配的光纤光栅解调算法扩大了解调算法的运用范围,提高了非对称峰时的解调精度,保持了光纤光栅的有效传感.     

基于差分演化算法的FBG参数重构技术

文章提出了一种基于差分演化算法的光纤布拉格光栅(FBG)参数重构技术.基于均匀FBG的目标反射谱,可利用差分演化算法寻找一组光栅参数,根据这组参数计算得到的反射谱与目标反射谱偏差最小,该组参数即为重构的光纤光栅参数.数值实例表明,差分演化算法计算效率高,结果精确,是一种实用的参数重构方法.     

基于语义的NGN融合业务合成算法研究

分析了当前两种基于语义的业务合成算法在应用于电信域和网络域业务融合时的不足,提出了一种新的基于语义的双向链自动业务合成算法,并对该算法的性能进行了详细分析,证明了其在业务的平均合成时间和合成成功率上明显优于已有的相关算法。最后给出了一个融合业务的合成实例,以验证算法的正确性。     

改进光纤光栅应变分布解调算法中优化目标函数的理论与方法

分析了光纤布拉格光栅(FBG)反射光谱的获取方式,根据反射光谱的特征,提出了利用相关系数改进FBG应变分布解调算法中优化目标函数的理论方法。结合差分进化算法,对改进算法与传统算法的性能进行了对比仿真。仿真结果表明,传统算法仅适用于能获知FBG真实反射率的情况,而改进算法还适用于无法获知FBG真实反射率的情况,所提方法提升了FBG应变分布解调算法的实际应用能力。     

SAR原始数据时频域幅相压缩算法

采用时频分析的方法,结合SAR原始数据非平稳的时频振荡特性,提出了一种基于Gabor变换的SAR原始数据时频域幅相压缩算法.该算法首先对分块原始数据进行幅度-相位转换、2D-RDGT变换以及在时频域内对各频率平面根据方差进行比特分配,然后采用分块自适应量化算法量化各频率平面.实验结果表明,该算法与传统的BAQ算法和已有的幅相算法相比无论在数据域还是在图像域的压缩性能都取得了明显的改善.     

同型机调度问题的混合ACO-SA优化算法研究

针对同型机调度问题,提出一种蚁群-模拟退火两阶段优化算法.构造了问题域蚁群模型,运用蚁群算法展开全局搜索,通过自适应调整闻值改善空间探索与局部开采的平衡;为提高搜索精度,引入模拟退火算法,将蚁群算法的最好解作为其初始解,在邻域内进行精细搜索,利用其概率突跳特性有效避免算法陷入局部最优.实验结果表明混合算法具有稳定而优良的寻优能力.     

基于二进小波变换自适应Kalman滤波反褶积

本文提出了基于二进小波变换自适应Kalman滤波反褶积(AKFD)新方法.它抛弃了传统预测反褶积对信号平稳性的假设,克服了提高分辨率反而明显降低信噪比的矛盾,其较好地压缩反射波形,但噪声并没有明显提高,所以具有很好的抗噪性能.在小波域进行的AKFD压制假反射比在时间域AKFD好,此外,该方法具有对信号分频进行AKFD的特性,增强了Kalman滤波的自适应性,所以在小波域下的分辨率明显比在时域内高.同时,该方法克服了在时域内进行的AKFD抬升低频成份的缺陷.经大量的模型及实际资料处理表明该方法具有明显的效果.     

利用数字压缩技术频域内积和方差的分形编码算法

文中定义了图像块的数字压缩技术(DCT)频域内积,并证明了该内积等于时域内积, 从而可根据频域内积大小来作为分形编码中最佳匹配块的判断,并推导出DCT域上恒等变换与其余7种对称变换的关系。本文将值域块分为平稳、中间和活跃三类,研究对于不同类型的值域块,求频域内积时,保留低频系数个数和解码图像质量之间的关系,并提出了基于DCT域内积和方差的分形图像编码算法。在实验中,将本文算法分别同文献[ 2 ]、[ 3 ]中方法进行了比较,结果表明,本文算法能在基本保证解码图像质量的同时,大大提高编码速度。     

基于REC技术的激光器阵列传感系统设计

分析并提出了基于重构等效啾啁（REC）技术激光器阵列的传感系统和解调算法。REC工艺满足激光器阵列的低成本大量生产,并具备小体积的优势,在未来传感领域中有较大的实用价值。提出了一种激光器扫描的高效算法用来测量光纤布拉格光栅（FBG）因外界应力而产生的位移量。系统的独特性在于阵列激光器通道仅需调谐0.4 nm采样数据,取代了扫描FBG主功率峰,并且算法在FBG的任意谱段均适用,可以用于多通道波峰复用的FBG传感网络中。在单通道和四通道的实验中对FBG反射谱的位移进行精确定位,初步实验证明了该系统和算法的有效性和可行性。算法得出单通道中心波长与实际中心波长误差均在5 pm以下,四通道可以到达在2 pm以下,应力与算法结果中心波长呈现很好的线性度。对今后多通道激光阵列传感具有一定参考价值。     

基于粒子群算法的FBG峰值波长检测技术

提出了一种新的光纤布拉格光栅(FBG)峰值波长检测技术,将改进粒子群算法(PSO)与峰值波长检测技术相结合,应用于在光纤光栅传感网络的波长检测,解决了传统波峰检测技术要求光纤光栅传感器带宽不能重叠和最小位移波形检测计算速度慢的问题.仿真计算结果证明,即使相邻两个FBG传感器的波峰相互叠加时,运用这种方法仍能取得较高的检测精度.     

基于人工蜂群优化算法的光谱形复用技术

光纤布喇光栅(FBG)在构成大型传感网络时,由于光源带宽有限会出现光谱重叠的问题.提出了一种人工蜂群(ABC)算法及改进ABC(IABC)算法的解调技术,结合谱形复用技术与IABC算法对光谱重叠中的各个光栅的波长进行识别,并对多个FBG传感系统进行实验仿真与分析.实验结果表明:IABC算法在多FBG传感复用系统中的解调...     

Formulation of time-domain algorithm for fiber Bragg grating simulation and reconstruction

A time-domain algorithm for fiber Bragg grating simulation is formulated. It provides a time-domain equivalent to the well-known spectral-domain transfer matrix algorithm for fiber Bragg grating simulation, and allows much more accurate impulse response to be simulated directly from a known fiber Bragg grating. Two different time-domain grating reconstruction algorithms are formulated, which are much more accurate and efficient than their spectral-domain equivalents due to their intrinsic infinite spectral representation and truly one-dimensional nature. Error studies are also conducted for the time-domain grating reconstruction algorithms. The high accuracy and efficiency of the new time-domain algorithms are well demonstrated with several simulation, reconstruction, and design examples.     

基于多子群竞争进化规划算法的光纤光栅设计

从光栅传输矩阵分析法出发,提出了一种基于多子群竞争进化规划算法的光纤Bragg光栅(FBG)设计方法,进而设计了用于滤波的均匀FBG和用于色散补偿的啁啾FBG(CFBG)的结构参数.结果表明,本文设计方法可直接确定FBG的结构参数,在不同的设计精度要求下所设计的FBG分析曲线与目标曲线吻合很好,所采用算法具有比传统的进化规划算法快几10倍的收敛速度和更好的稳定性.     

宽带FBG与自相关算法提高CCD解调精度的研究

为提高光纤光栅解调算法的精度,设计了3 dB带宽在1~3 nm之间的宽带布拉格光栅与自相关算法解调系统,使用线阵CCD检测光谱,进行波长寻峰分析与实验验证。线阵CCD离散像素点之间波长间距固定,宽带布拉格光栅可得到更多有效像素数据点;自相关算法只考虑传感测量时光谱的偏移程度,可抵消背景噪声,消除光栅刻写或封装过程中操作不当引起光谱异常的影响,从而提高光栅中心波长解调精度。温度测量结果表明,使用自相关算法解调啁啾光栅与宽带光栅,误差较高斯算法分别减少54.05%和40.87%,此算法可以使啁啾光栅达到正常光栅的解调精度。并且,使用宽带光栅的解调误差仅为啁啾光栅的50%。     

Analysis and optimization of uniform FBG structure for sensing and communication applications

A uniform fiber Bragg grating sensor is sketched and inspected by the finite-difference time-domain method in furtherance of obtaining ultimate transmission and reflection spectra by optimizing the FBG parameters like refractive index, grating height, grating width, wafer width, wafer length. The maximum transmission power spectrum is achieved as ??7 dB for the refractive index of 3.005, and the maximum reflection spectra are obtained as 6 dB for the grating height of 1 μm which is enhanced nine times than the precedent work. The proposed FBG is a simple, light-weight, low-cost uniform structure, and it offers high reflectivity and ease of handling. Therefore, it is highly useful in sensing and communication applications.

     

Reconstruction of chirped fiber Bragg grating parameters and phase spectrum using two thermally modulated intensity spectra and a genetic algorithm

This study presents a synthesis method for reconstructing the multiple parameters such as grating position, length, period profile, refractive index modulation, and phase response of a chirped fiber Bragg grating (FBG) and its phase spectrum using two thermally modulated reflection intensity spectra and a genetic algorithm. In the proposed approach, the FBG parameters are determined using the genetic algorithm and are then used to reconstruct the phase response. The advantages of the proposed method include its simplicity, low cost, and nondestructive nature. Furthermore, the proposed method does not require a prior knowledge of the sign of the chirp of the grating period distribution of FBGs.     

High-speed fibre Bragg grating sensor interrogation using dispersion compensation fibre

A novel high-speed fibre Bragg grating (FBG) sensor interrogator using dispersion-compensating fibre is proposed and demonstrated. The wavelength shift measurement of the FBG sensor is converted to time-domain measurement. The high-speed potential of this scheme was investigated experimentally, demonstrating an effective sampling speed of 2.44 megasamples per second.     

Highly Accurate Synthesis of Fiber and Waveguide Bragg Gratings by an Impedance Reconstruction Layer-Aggregation Method

We present a novel method for the synthesis of complex fiber Bragg gratings (FBGs) which is based on an impedance reconstruction layer aggregation technique. The method takes as a starting point the accurate approximation of the sinusoidal perturbation (uniform or nonuniform) of the refractive index by local step functions by means of an inverse Fourier series relationship. This reduces the otherwise continuous scattering to only two points per local period and thus, the maximum spatial resolution as limited by the Nyquist criterion is achieved and there is no need to lump various periods of the FBG into an equivalent mirror. The main advantage brought by the method is the possibility of synthesizing structures containing defects or discontinuities of the size of the local period, a feature which yields different results with priorly reported methods to which the one reported here can be considered as complementary. In addition, this enhanced spatial resolution allows the synthesis of very strong FBG devices providing convergent solutions. We illustrate this fact by demonstrating the synthesis of a flat-top filter with a maximum reflectivity of 99.999%. The method renders directly the refractive index profile n(z) as it does not rely on the coupled mode theory since the grating is reconstructed using a V-I matrix formulation. The method is simple and its complexity is equivalent to those previously reported in the literature. Examples are given which prove that perfect reconstruction is achieved in both simple and complex grating profiles. Although a layer aggregation is presented here, the layer peeling (i.e., moving time frame) version of this algorithm is straightforward.