基于激光测距的机载光电成像系统目标定位

针对小型机载光电平台无法准确获取视轴指向问题，设计了一种基于激光测距的目标定位算法。利用机载光电侦察平台锁定跟踪目标的特性，对同一目标多次测量，采用激光测距装置获取目标与载机间的距离信息。根据WGS-84定义的地球椭球模型建立系统的测量方程。考虑到测量方程的非线性，利用扩展卡尔曼滤波对目标位置进行估计。该定位方法精度只受到GPS接收机定位精度和激光测距机测量精度的影响，目标定位误差与机载光电侦察设备视轴指向测量无关。采用蒙特卡洛法仿真分析载机位置测量误差及激光测距系统位置误差对目标定位的影响，结果显示该算法定位精度较高。采用飞行试验数据验证了该目标定位算法的有效性，在飞行高度8 000 m时，目标定位精度优于8 m。相比于传统定位算法，该方法可将定位精度明显提高。同时此定位方法易于部署，可操作性强，具有较大的应用价值。     

基于立体定向靶标的探针式多视场三维视觉测量系统

针对含有遮挡区域、深孔及凹槽等特征的多面体或回转体物体，设计了一套基于立体定向靶标的探针式多视场三维视觉测量系统，并阐述该套测量系统的结构组成和基本工作原理。首先，基于近景摄影测量技术建立立体定向靶标的6个单元模型，计算靶标各侧面角点在各自单元模型内的坐标，再通过单元模型的链接和光束平差，获取全部角点的精确全局坐标，并将其作为立体定向靶标的全局控制点。然后，设计了利用共面角点辅助定位的探针，仍基于近景摄影测量技术解算出角点和测头在探针坐标系中的精确坐标。最后，利用共面的棋盘格角点与其像平面之间的单应性矩阵，推导全局坐标系、探针坐标系各自与相机坐标系的位姿关系，进而求得探针测头的全局坐标。以量块（量棒）的标准长度作为评价指标，在2m×1.5m的视场范围内测量精度优于0.1mm。测量实验表明，多视场三维视觉测量系统用于具有回转体结构特征的水壶测量，能够获取水壶表面全部区域的点云数据。     

Enhancing nugget size and weldable current range of ultra-high-strength steel using multi-pulse resistance spot welding

ABSTRACT

This paper presents an innovative approach that uses a pulse-profile to improve the welding quality of CP1180 steel in resistance spot welding process. Three pulses with two cooling times were used in the developed multi-pulse welding (MPW) schedule. The experimental results show that the first pulse increases the contact area between the sheets to improve the current flow pattern. The second pulse was designed to extend the sheet-to-sheet contact area and corona bond for preventing rapid nugget growth. Using these designs, the nugget size was maximised through the third pulse. The maximum nugget size using the designed MPW schedule was 18.5% greater than that of the single-pulse welding schedule and the weldable current range was extended by 130%.     

基于正交试验的割缝筛管冲蚀磨损分析

为了探讨割缝筛管的冲蚀磨损情况,采用有限元法分析了生产压差、粒度水平、含砂水平及动力黏度等因素对割缝筛管冲蚀的影响程度,通过正交试验确定了各因素影响割缝筛管的主次顺序。分析结果表明:在一定的生产环境下,筛管缝道入口处流速最大,在入口处呈现一定半径圆弧的趋势增大,于缝隙处发生最大冲蚀率,正对来流方向的区域冲蚀严重;正交试验法确定的主次因素为含砂水平>粒度水平>动力黏度>生产压差,使割缝冲蚀最小的最佳组合方案为生产压差3 MPa,动力黏度0.05 Pa·s,粒度0.21 mm,含砂体积分数1%。所得结论可为筛管的结构设计与精度选择提供依据。     

一种Chirplet神经网络自动目标识别算法

针对飞机目标的自动识别问题,提出一种联合特征提取与分类的Chirplet神经网络方法,实现一维高分辨率距离像的识别。Chirplet神经网络将Chirplet原子变换用于多层前馈神经网络结构的输入层,替换传统的激励函数对距离像序列进行特征提取;网络的分类部分由隐层和输出层组成。在训练过程中调整神经网络权值的同时,完成对Chirplet原子时频参数的自动调整,协调优化特征参数和分类器参数,使Chirplet神经网络同时实现特征提取和目标分类。对4类飞机目标的仿真测试结果表明,相比时频变换和Gabor原子网络等方法,具有四特征参数的Chirplet神经网络方法具有较高的识别率和抗噪性能。     

Durable,Sensitive, and Wide‐Range Wearable Pressure Sensors Based on Wavy‐Structured Flexible Conductive Composite Film

Flexible pressure sensors have potential applications in human motion monitoring and electronic skins. To satisfy the practical applications, pressure sensors with a high sensitivity, a low detection limit, a broad response range, and an excellent stability are highly needed. Here, a piezoresistive pressure sensor based on wavy‐structured single‐walled carbon nanotube/graphite flake/thermoplastic polyurethane (SWCNT/GF/TPU) composite film is fabricated by a prestretching process. Due to the random wavy structure, high conductivity, and good flexibility, the prepared sensor displays a low detection limit of 2 Pa, a wide sensing range of 0–60 kPa, and a high sensitivity of 5.49 kPa^?1 for 0–50 Pa. Furthermore, the sensor shows a remarkable repeatability of over 1.1 × 10⁴, 9.0 × 10³, and 2.0 × 10³ pressure loading/unloading cycles at 50 Pa, 500 Pa, and 30 kPa, respectively, and a fast responsibility of 100–150 ms of loading response time and 400–600 ms of relaxation time. Therefore, the pressure sensor is successfully adopted to monitor both the large‐scale human activities (e.g., walk and jump) and the small‐scale signals (e.g., wrist pulse). Furthermore, a sensor array is assembled to map the weight and shape of an object, indicating its various potential applications including human–machine interactions, human health monitoring, and other wearable electronics.     

地表移动带范围内建构筑物安全可靠性分析

地表建构筑物位于在生产矿山地表开采移动范围内，如果按照一般圈定地表移动范围原则判断建构筑物的安全可靠性，结果是不安全或者预留保安矿柱可保证安全。为分析地表移动带范围内建构筑物安全可靠性，采用FLAC3D软件建立数值模拟模型，对矿区地表移动进行分析研究，并结合建构筑物的破坏等级评判标准，可以更加合理地判断地表移动范围内建构筑物的安全可靠性，对存在相似条件的矿山具有一定的借鉴意义。     

近距离上保护层开采下伏被保护层卸压效应研究

使用ZKBY-Ⅱ型顶板离层仪对戊_9-10煤层的变形膨胀进行观测，对近距离上保护层回采时下伏被保护层应力分布和膨胀变形规律进行了研究。结果表明，近距离上保护层开采后，在采空区下方的一定范围内被保护层产生卸压膨胀变形，煤体弹性潜能得以释放，透气性增大，消除或减小了被保护层煤与瓦斯突出危险性，研究取得了显著的经济技术效益。     

Effect of Solute Elements and Cooling Rate on Strain in Brittle Temperature Range of Continuously Cast Strand

A micro-segregation model of solute elements in mushy zone withδ/γtransformation during solidification was established based on the regular hexagon transverse cross section of dendrite shape proposed by finite difference method under the non-equilibrium solidification condition.The model was used to calculate the non-equilibrium pseudo binary Fe-C phase diagram and the strain of steels induced by variation of temperature in brittle temperature range.On the basis of the phase diagram and the strain,the strain curve in brittle temperature range as a function of carbon content for continuously cast strand was introduced and obtained.Solute elements change the position of the strain curve.And cooling rate changes the position and the shape of the strain curve.The comprehensive formula of the strain as functions of solute elements and cooling rate in brittle temperature range has been obtained by nonlinear fitting program.