To overcome the invalid phase and phase jump phenomenon generated during the phase unwrapping, a phase error correction method based on the Gaussian filtering algorithm and intensity variance is proposed in this paper. First, a threshold of fringe intensity variance is set to identify and clear the phase in the invalid region. Then, the Gaussian filtering algorithm is employed to correct the phase order at the fringe junction, and then the absolute phase is corrected. Finally, the phase correction experiments of different geometric objects are carried out to verify the feasibility and accuracy of the proposed method. The method proposed in this paper can be extended to the correction of absolute phase error obtained by any coding method.

To achieve the real-time detecting and localization of hypervelocity impact events, a monitoring and localization system was designed based on fiber Bragg grating (FBG) sensor network. First, the simulation model was built to study the damage evolution and wave propagation process. Subsequently, based on the response mechanism of FBG to strain, the corresponding high frequency demodulation system was designed. Furthermore, a hypervelocity impact experiment was performed to verify the effectiveness of the designed system. Finally, combined with the diamond sensor array localization algorithm, the accurate position of hypervelocity impact source can be achieved.

In this paper, to reduce the non-linear phase error caused by gamma effect of the digital projector, a novel phase difference extraction method is proposed. First, through multi-layer discrete wavelet decomposition (DWT), the components of the original phase difference at different frequencies are extracted. Subsequently, the effective components are taken by the orthogonal matching pursuit (OMP) algorithm, and the phase difference is reconstructed. According to the upper and lower envelopes of the original phase difference extracted by cubic spline interpolation, the residual threshold of OMP is set. According to the results of three-dimensional (3-D) reconstruction experiment on a standard sphere, the proposed method is capable of reducing the errors in the original phase difference and achieving a better imaging result.

近红外光谱检测已被应用于水泥生料成分的快速检测, 但现场环境中的湿度等因素会对光谱产生干扰, 从而降低检测精度。 为了提高检测精度, 在实验分析湿度对水泥生料近红外光谱检测影响的基础上研究了补偿方法。 在水泥厂选取了24份水泥生料样本, 其中18份作为校正集, 6份作为验证集; 水泥生料中的有效成分为SiO2, Al2O3, Fe2O3和CaCO3, 各成分含量的标准值由X射线荧光光谱分析测出。 首先, 将校正集的18份样本每份重复装样测5次光谱, 用得到的90个光谱建立模型Ⅰ; 再每份样品制作5个湿度梯度样本, 其获得过程为, 先将样本放置在电加热平台上, 用玻璃棒将样本摊平, 180 ℃下加热30 min, 再将样本放置在散热片上进行降温, 待样品恢复室温后取出进行第一次光谱扫描, 得到1个光谱, 将测量后的样本放入搅拌器, 使用装有去离子水的喷雾器对其喷雾两次, 然后搅拌30 s混合均匀, 测量混合后的样本得到下一个光谱, 重复该过程, 得到具有湿度梯度的5个光谱。 所有样本均采用烘干法进行湿度测量, 样本湿度变化区间在0.6%～2%以内。 对每个湿度梯度的样本测量1次, 用得到的这90个光谱建立模型Ⅱ。 然后, 将验证集的6份样本每份制作5个湿度梯度, 获取方式与校正集相同, 对每个湿度梯度的样本测量1次, 得到30个光谱。 所有光谱均采用多元散射校正预处理, 拟合波段选择4 000～5 000 cm-1, 建模方法采用偏最小二乘法。 比较同一份样本的5个湿度梯度, 可以看到在5 200 cm-1处光谱差异最大, 在其他位置也有肉眼可见的明显差异, 因此, 湿度变化对全波段光谱有明显的影响。 最后, 将这30个光谱输入模型Ⅰ与模型Ⅱ进行验证, 并对比模型Ⅰ与模型Ⅱ的预测均方根误差RMSEP。 模型Ⅱ中SiO2, Al2O3, Fe2O3和CaCO3的预测均方根误差RMSEP比模型Ⅰ分别减小了25%, 31.3%, 33.3%和25%。 实验结果表明, 水泥生料样本湿度对近红外光谱模型的预测结果具有一定的影响, 采用具有湿度梯度的样本进行建模可有效降低湿度对预测结果的影响。

为解析脉冲激光对靶材的破坏效果与激光各参数之间的关系, 提出了一种基于数值计算方法的仿真模拟方案, 开发了一套脉冲激光辐照靶材的热-力效应数值仿真软件。采用对照法, 分别对激光功率、激光能量、激光光斑大小、脉冲宽度和间歇时间等五个参量进行控制, 对比不同参数条件下激光破坏靶材的效果, 讨论并得出了优化脉冲激光破坏靶材的方法。仿真结果表明, 激光能量和功率密度与破坏效果之间是非线性关系, 随着二者的增加, 对破坏效果的边际加强效果减弱; 随着间歇时间的增加, 破坏效果先增大后减小。对于确定的靶体目标, 通过增加脉冲激光的输出能量和功率密度, 减小光斑半径, 调整脉冲间歇时间, 可以使得脉冲激光辐照靶材的破坏效果达到最佳。

脉冲激光辐照靶材作用机理的研究在激光加工等领域具有重要的科学意义和应用潜力。为了直观体现脉冲制式强激光对靶材的破坏优势，考虑靶材本身、入射激光因素对激光辐照靶材的破坏作用的影响，利用有限容积法对激光辐照靶材的作用过程进行模拟，重点研究了脉冲激光与靶材相互作用的机理，建立了数学模型，得到了三种不同形式的脉冲激光辐照靶材的温度场及作用过程。实验结果表明，脉冲激光辐照靶材可分为升温、熔孔和熔孔深径比增加三个阶段，且重复频率脉冲激光对靶材的破坏效果大于间歇脉冲激光。

Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipment. In this paper, four fiber Bragg grating (FBG) sensors are used to establish the sensor array to locate the acoustic emission source. Firstly, the nonlinear locating equations are established based on the principle of acoustic emission, and the solution of these equations is transformed into an optimization problem. Secondly, time difference extraction algorithm based on the phase transform (PHAT) weighted generalized cross correlation provides the necessary conditions for the accurate localization. Finally, the genetic algorithm (GA) is used to solve the optimization model. In this paper, twenty points are tested in the marble plate surface, and the results show that the absolute locating error is within the range of 10 mm, which proves the accuracy of this locating method.

基于GMM(超磁致伸缩材料)的FBG(光纤布拉格光栅)电流传感器具有光学电流传感器的优点。利用自行配制的环氧树脂胶将FBG与GMM封装为一体作为传感器探头, 通过增加偏置磁场改变传感器的静态工作点, 采用高频性能良好的铁氧体材料作为导磁回路, 约束交变电流产生的磁场并引导进入传感器探头, 进而将电流的变化转变成为FBG的波长变化, 通过FBG解调系统实现电流测量。通过实验对该传感器的静态和动态响应进行测试, 取得了良好的实验结果。

基于光纤光栅(FBG)传感器网络构建了声发射检测系统, 并提出了最小方差无失真响应(MVDR)的声发射源定位方法。构建的系统由7个FBG传感器组成传感器线阵列, 采用未经平坦的放大自发辐射(ASE)光源边缘滤波实现信号解调。利用Shannon小波变换从频散复杂的声发射信号中提取窄带信号, 并基于MVDR算法扫描整个监测区域获取空间谱。根据空间谱函数计算输出值, 并将计算的输出值作为像素值。最后, 通过提取空间谱中的最大值的坐标确定声发射源的位置。在LY12铝合金板上进行了实验验证。结果表明, 该方法在400 mm ×400 mm的区域内, 声发射定位的最大误差为9.4 mm, 平均误差为7.2 mm, 耗时小于3 s。该系统具有较高的实时性和定位精度, 是一种声发射源定位的新方法。

在电流回路中, 当通过导线的电流过高时, 会导致线路高温, 严重时可能引起火灾。因此实时监测电流线路的温度, 对预防线路过载以及火灾的发生具有重要的意义。在理论分析光纤光栅温度传感机理的基础上, 设计了用于导线负载检测的传感系统。在0~5 A范围内, 实验研究了光纤光栅温度传感器中心波长变化与导线负载之间的关系, 验证了导线负载检测的可行性, 为导线负载的实时监测, 以及断路、短路故障的判断提供了一种新的方法。