具有镀铬层的铁磁材料和零件的裂纹检测

阐述了具有镀铬层铁磁性零件的裂纹漏磁检测机理,探讨了基于循环搜索逼近的裂纹定量检测的基本方法。实测结果证明漏磁法检测具有镀铬层工件的缺陷是可靠的。     

高雷诺数时筒形桅杆在均匀流场中的风载实验研究

在哈尔滨工程大学船模拖曳水池中,研究了雷诺数在3.19×104~1.15×106的范围内,表面倾斜且前后不对称的筒形桅杆攻角从0°~180°,以15°为间隔,在均匀流场中所受的风载。分析了桅杆所受的周向压力、轴向压力和St随雷诺数和攻角的变化趋势。结果表明,倾斜壁面和攻角改变对压力分布和St有较大影响。     

基于Monte-Carlo方法的火炮瞄准校验系统精度评定

基于双经纬仪的火炮瞄准校验系统需要给出其校验精度,但传统的测量不确定度传递公式需要大量微分运算,校验精度计算很复杂,为此,提出了基于Monte-Carlo方法的火炮瞄准校验系统测量不确定度的评定。以调炮精度校验为例分析了校验系统的原理,结合调炮精度校验过程设计了基于Monte-Carlo方法的测量不确定度评定过程,分析比较了计算量的大小,并将评定结果与传统评定方法的结果进行比较。结果表明:二者一致性良好,Monte-Carlo方法能够完成对瞄准校验系统各校验项目的校验精度评定,并且简化了计算,节省了时间。     

基于聚类分析的入侵检测算法?

聚类技术在入侵检测中被广泛研究，但是传统的K?means算法对初始值敏感，无法取得理想的效果；层次聚类算法时间复杂度高，性能较差。针对这些问题，设计了一种改进的K?means算法：算法优化孤立点和噪声处理能力，根据有效性指标获得最优K值，在此基础上，动态选取初始聚类中心进行聚类，可以取得较好的聚类效果。采用数据集KDD Cup99将改进的算法应用于入侵检测，进行仿真实验。实验结果表明，改进的算法有效地提高了检测率和降低了误检率，与现有算法相比具有一定的优势。     

潜艇攻击鱼雷最小射程圆内目标的方法

针对潜艇攻击鱼雷最小射程圆内目标的方法问题,首先,给出了不同自导方式下鱼雷最小射程的计算方法,并分析其对鱼雷攻击的影响;然后,依据鱼雷二次转角射击弹道过程,建立了鱼雷二次转角射击通式,并分析了鱼雷二次转角射击需满足的约束条件;在此基础上,深入研究了潜艇攻击鱼雷最小射程圆内目标的具体方法。最后通过实例验证了攻击方法的可行性和有效性。     

无线传感器网络中基于统计异常的入侵检测

无线传感器网络与传统网络存在较大差异,传统入侵检测技术不能有效地应用于无线传感器网络.结合无线传感器网络的特点,提出一种基于统计异常的入侵检测.入侵检测为传感器节点在正常工作状态下的某些系统特征建立行为模式,并通过统计观测值对正常行为模式的偏离程度来判断是否存在入侵.理论分析及仿真实验表明,提出的入侵检测技术可有效检测入侵,检测算法简洁高效,利于节能,适用于供能紧张的无线传感器网络.     

线膛炮内膛图像膛线识别研究

提出了一种线膛炮内膛表面图像识别的分层次识别方案,并研究了膛线识别的算法。对于特定情况下的图像识别有一定的借鉴作用。     

An infrared target intrusion detection method based on feature fusion and enhancement

Infrared target intrusion detection has significant applications in the fields of military defence and intelligent warning. In view of the characteristics of intrusion targets as well as inspection difficulties, an infrared target intrusion detection algorithm based on feature fusion and enhancement was proposed. This algorithm combines static target mode analysis and dynamic multi-frame correlation detection to extract infrared target features at different levels. Among them, LBP texture analysis can be used to effectively identify the posterior feature patterns which have been contained in the target library, while motion frame difference method can detect the moving regions of the image, improve the integrity of target regions such as camouflage, sheltering and deformation. In order to integrate the advantages of the two methods, the enhanced convolutional neural network was designed and the feature images obtained by the two methods were fused and enhanced. The enhancement module of the network strengthened and screened the targets, and realized the background suppression of infrared images. Based on the experiments, the effect of the proposed method and the comparison method on the background suppression and detection performance was evaluated, and the results showed that the SCRG and BSF values of the method in this paper had a better performance in multiple data sets, and it’s detection performance was far better than the comparison algorithm. The experiment results indicated that, compared with traditional infrared target detection methods, the proposed method could detect the infrared invasion target more accurately, and suppress the background noise more effectively.     

Influence of active constrained layer damping on the coupled vibration response of functionally graded magneto-electro-elastic plates with skewed edges

This article makes the first attempt in assessing the influence of active constrained layer damping (ACLD) treatment towards precise control of frequency responses of functionally graded skew-magneto-electro-elastic (FGSMEE) plates by employing finite element methods. The materials are functionally graded across the thickness of the plate in terms of modest power-law distributions. The principal equations of motion of FGSMEE are derived via Hamilton’s principle and solved using condensation technique. The effect of ACLD patches are modelled by following the complex modulus approach (CMA). Additionally, distinctive emphasis is laid to evaluate the influence of geometrical skewness on the attenuation capabilities of the plate. The accuracy of the current analysis is corroborated with comparison of previous researches of similar kind. Additionally, a complete parametric study is directed to understand the combined impacts of various factors like coupling fields, patch location, fiber orientation of piezoelectric patch in association with skew angle and power-law index.     

基于预报误差分布拟合的卫星历史机动检测方法

轨道机动会引起在轨卫星的轨道异常，是空间态势感知的重点关注对象之一。为此，提出一种从卫星的两行轨道要素编目数据中检测历史机动的方法。通过分析预报误差检测轨道参数的异常编目值，进而获得相应的历史机动信息。对卫星的两行轨道要素编目数据两两预报求差得到预报误差的样本数据后，利用期望最大化算法可以拟合得到以高斯混合模型表达的预报误差的概率分布模型；以此为基础，可以确定利用预报误差检测轨道参数异常编目值的门限；利用轨道机动与异常编目值之间的对应关系，最终实现机动检测。对典型活动卫星的机动检测结果表明，所提方法能够在准确检出历史机动事件的同时保持较低的误检率。