TMPA 卫星降水数据的评估与校正

卫星遥感降水由于时空分辨率的优势在现代水文模拟中正起着越来越大的作用。本研究对黄河源区的两套卫星降水产品(TMPA准实时3B42RT和研究数据3B42V6)进行了详细评估,结果表明,3B42RT与3B42V6相比会明显高估地面降水,而两者对降水事件的反演能力基本一致。通过引入"降水重心"的概念,两套卫星降水产品均可以基本反映降水的空间分布及长期演变过程。在两者尤其是3B42RT数据的校正中,首先将卫星数据与地面站点月降水对比,再等比例降尺度回日降水,然后尝试逐步订正和最优插值两种残差处理方法,从而使降水量和降水分布的精度进一步提高。最后用校正后的卫星降水驱动分布式水文模型,利用输出径流间接验证校正的效果。     

结合mean-shift与MST的K-means聚类算法

针对初始点选择不当导致K—means陷入局部最小值问题,提出一种结合自适应mean-shift与最小生成树（MST）的K—means聚类算法。将数据对象投影到主成分分析（PCA）子空间,给出自适应mean．shift算法,并在PCA子空间内将数据向密度大的区域聚集,再利用MST与图连通分量算法,找出数据的类别数和类标签,据此计算原始空间的密度峰值,并将其作为K．means聚类的初始中心点。对K—means的目标函数、聚类精度和运行时间进行比较,结果表明,该算法在较短的运行时间内能给出较优的全局解。     

Experimental study of weld position detection based on keyhole infrared image during high power fiber laser welding

Keyhole is one of the important phenomena in high-power laser welding process. By studying the keyhole characteristic and detecting the seam offset during high-power fiber laser welding, an infrared sensitive high-speed camera arranged off-axis orientation of laser beam was applied to capture the dynamic thermal images of a molten pool. The 304 austenitic stainless steel plate butt joint welding experiment with laser power 10 kW was carried out. Through analyzing the keyhole infrared image, the weld position was calculated. Least squares method was used to determine the actual weld position. Image filtering technique was used to process the keyhole image, and the keyhole centroid coordinate were calculated. Also, least squares method was used to fit the keyhole centroid curve equation and establish a nonlinear continuous model which described the deviation between keyhole centroid and weld seam. The heat accumulation effect affected by the infrared radiation was analyzed to determine whether the laser beam focus spot deviated from the desired welding seam. Experimental results showed that the keyhole centroid has related to the seam offset, and can reflect the welding quality.     

基于ZigBee的钨矿井下矿车定位监测系统研究与设计

针对现有的钨矿井下矿车定位系统的布线困难、信息化和可视化水平低等问题,为了更加合理、高效地调度矿车,设计了一种基于Zig Bee的无线网络系统,实现对井下矿车定位及安全监测。首先探讨了井下环境无线信号传输的RSSI测距模型,并采用高斯滤波对RSSI测距参数进行修正后,结合极大似然估计定位方法实现矿车定位,针对此定位算法存在的较大误差,提出了加权质心定位算法来提高矿车定位的准确性。然后通过上位机将井下采集的矿车速度和定位信息实时显示在井上监控主机和大屏幕中。通过实验仿真,结果证明,改进的加权质心定位算法有效地降低了定位误差,上位机对速度数据信息可实现调用、存储、实时显示、查询并预警等功能,系统具有实时性强、精度高、鲁棒性好等特点,可以有效提升钨矿井下开采生产的安全性。     

舰船箔条质心干扰建模与仿真

箔条质心干扰是舰船在受到反舰导弹攻击时重要的防御方式之一。介绍了舰船箔条质心干扰原理,然后构建了作战环境、舰船、箔条云、弹载雷达目标检测等模型,进行了仿真计算,对仿真数据进行了分析,给出了不同情况下箔条云最佳的布放距离和角度,使箔条干扰在对抗反舰导弹时能发挥最大效果。     

舰艇质心干扰效果的模型及仿真

建立了质心干扰形成后干扰效果的数学模型，利用计算机仿真技术对干扰过程和效果进行仿真和评估，对实施质心干扰的舰艇机动具有一定的指导意义。     

一种低复杂度光伏系统太阳光斑位置检测算法

日光跟踪技术能明显提高光伏系统的效率,传统的光电检测日光跟踪技术的跟踪精度低,基于图像处理的日光检测跟踪技术精度虽高但算法复杂,系统成本高。通过图像处理进行太阳光斑检测跟踪的一般方法,包括太阳光斑图像的二值化、形心提取、差量计算等算法的分析,提出了一种简化的形心提取方法,通过与传统形心提取算法比较,误差很小并不足以对跟踪精度造成实质性的影响,最后用ARM-CortexM3内核的芯片作为载体实现了对太阳光斑图像的检测跟踪算法。     

A robust condition monitoring methodology for grinding wheel wear identification using Hilbert Huang transform

Grinding is a finishing operation performed to obtain the desired finish on the component. Wheel wear is one of the primary constraints in achieving the desired productivity in grinding. A new methodology is proposed for accurate and timely identification of wheel wear in cylindrical grinding using Hilbert Huang transform and support vector machine. During the grinding of EN31 carbon steel, the condition of the wheel and its wear was monitored with an accelerometer and power cell. Both vibration and power signals captured were used to identify the condition of the wheel and its wear. An exhaustive feature set is generated in the frequency and the time-frequency domain. Hilbert Huang transform, an adaptive time-frequency analysis technique, was used to extract the features of tool wear in the time-frequency domain. The first three IMF constituents were further chosen for feature extraction of statistical parameters based on their mean energy. Random forests algorithm was used to identify the relevant features. The methodology was validated with several grinding experiments and, is found to give an accuracy of 100% with both low and high cutting depths. The results indicated the robust and reliable wheel wear detection in cylindrical grinding with the use of relatively cheap sensors like accelerometers. The proposed method can be widely used in many applications in the industry where grinding is predominantly used as the finishing operation.     

面源红外干扰弹质心干扰反舰导弹的决策方法

面源红外诱饵已经发展成为对抗红外成像制导导弹的一种有效手段。以面源红外干扰弹质心干扰反舰导弹为例,设计了相关的仿真模型,包括导弹模型、舰艇模型、面源干扰弹模型、干扰弹发射决策模型和发射机动决策对干扰效果影响的评估模型等,并依据质心干扰仿真计算流程,对干扰弹发射和舰艇机动决策方案进行了寻优仿真,提出了实施面源红外干扰时优选的干扰弹发射和舰艇规避机动决策原则与方法。     

基于距离平方模板的快速质心搜索算法

智能识别领域,严格要求系统能快速准确地搜索跟踪目标质心,一个基于欧式模板的快速质心搜索算法得到了广泛应用。但该方法仅能求得近似解,难以求取目标质心的精确坐标。提出一种基于距离平方模板的快速质心搜索算法,并将该算法从二值图像推广到灰度图像的质心搜索。两种算法对同一图像质心搜索结果进行对比,欧式模板算法误差在2%～6%范围内,而距离平方模板算法精度为100%。结果表明:在精确度要求较高的场合,特别是小目标追踪识别时,必须使用距离平方模板进行目标质心的计算。