对相控阵雷达自适应旁瓣对消的多点源压制干扰

分析了相控阵雷达自适应旁瓣对消的工作原理及方法.然后提出了用多台干扰设备协同工作的相参干扰.每台干扰设备在雷达处理间隔内发射能覆盖真实目标并且持续时间较短的干扰信号,多台设备协同工作在目标附近形成压制干扰.该方法影响雷达样本选择,从而降低自适应旁瓣对消的效果.仿真结果和外场试验表明了该方法的有效性.     

基于HOG和SVM算法的磨粒图像在线监测技术

为了解决发动机润滑油液磨粒图像监测只适用于微流且易受气泡干扰等问题,设计了一种可适用于相对大流量工作环境的油液磨粒光学图像在线监测系统,区分气泡和磨粒。通过该监测系统,批量采集了一系列磨损颗粒和气泡图片,用于后续图像分类算法的训练与测试。采用了一种基于背景差分和大津法的运动物体提取算法提取出大量磨粒及气泡图像样本,运用基于方向梯度直方图（Histogram of oriented gradients,HOG）进行特征提取和支持向量机（Support vector machine,SVM）分类算法对气泡和磨粒进行识别。实验结果表明,该监测系统能有效采集磨粒及气泡图像并进行自动识别。与基于形态学特征提取算法以及K最近邻（K-nearest neighbor,KNN）等传统分类算法相比,HOG-SVM算法分类精度更高,识别准确率可达83 8%。     

储氢合金的性质及发展趋势

本文介绍了储氢合金的性质，Ｎｉ－ＭＨ电池原理，以及储氢合金对Ｎｉ－ＭＨ电池所产生的影响，根据目前科学技术的发展以及市场的需求，提出了未来储氢合金及Ｎｉ－ＭＨ电池的发展趋势。     

Solar flare forecasting model supported with artificial neural network techniques

Nowadays operational models for solar activity forecasting are still based on the statistical relationship between solar activity and solar magnetic field evolution. In order to set up this relationship, many parameters have been proposed to be the measures. Conventional measures are based on the sunspot group classification which provides limited information from sunspots. For this reason, new measures based on solar magnetic field observations are proposed and a solar flare forecasting model supported with an artificial neural network is introduced. This model is equivalent to a person with a long period of solar flare forecasting experience.     

一种基于RS码的宽间隔跳频序列生成方法

针对目前基于RS码生成的非重复跳频序列周期较短、序列复杂度较低、工程实用性不强等缺点,提出一种改进的RS码宽间隔跳频序列生成方法。使用长周期的RS码,采用非线性转移矩阵法将其转换为跳频序列,再用对偶频带法对其进行宽间隔处理。性能仿真结果表明,与以往的方法相比,改进的跳频序列在增加了序列复杂度的情况下,仍具有良好的均匀性、随机性和汉明相关性,且实现较简单,工程实用性较强。     

某锅炉钢结构角钢对扣箱型结构的焊接

某锅炉钢结构项目电梯井立柱采用了角钢对扣的箱型结构,此种箱形结构截面小,焊缝布置不对称,且焊缝长度较大,坡口切割变形、焊接变形难以控制,我们通过自制工装改进制作工艺解决了此类问题,满足该项目的验收要求。     

Neoplastic transformation of hamster embryo cells by heavy ions

We have studied the induction of morphological transformation of Syrian hamster embryo cells by low doses of heavy ions with different linear energy transfer (LET), ranging from 13 to 400 keV/μm. Exponentially growing cells were irradiated with ¹²C or ²⁸Si ion beams generated by the Heavy Ion Medical Accelerator in Chiba (HIMAC), inoculated to culture dishes, and transformed colonies were identified when the cells were densely stacked and showed a crisscross pattern. Over the LET range examined, the frequency of transformation induced by the heavy ions increased sharply at very low doses no greater than 5 cGy. The relative biological effectiveness (RBE) of the heavy ions relative to 250 kVp X-rays showed an initial increase with LET, reaching a maximum value of about 7 at 100 keV/μm, and then decreased with the further increase in LET. Thus, we confirmed that high LET heavy ions are significantly more effective than X-rays for the induction of in vitro cell transformation.     

高转速风扇叶片外物撞击损伤的定量评价方法

外物撞击是造成航空发动机风扇叶片变形、损伤甚至断裂的主要因素。针对外物撞击持续时间短、瞬间载荷大、损伤影 响因素多，难以进行定量损伤评价的问题，提出基于叶片损伤参数α的叶片损伤定量评价方法。以发动机风扇叶片受冰撞为例， 采用非接触叶尖计时测量方法，对叶片撞击产生的叶尖位移进行监测分析，验证了该方法的可行性。采用瞬态动力学分析方法对 叶片经受撞击过程进行全流程仿真模拟，并采用正交试验法定量研究了外物撞击过程中的撞击速度、叶片转速、撞击位置3种因 素对叶片损伤参数α的影响，拟合回归方程并绘制了这3种因素的3D响应曲面图，得到各因素的影响权重。结果表明：冰块速度 与撞击位置同时下降时，叶片损伤弱化效果显著。该方法可为大型风扇叶片抗外物打击性能设计和在役健康监测提供理论支撑。     

Flow separation control on swept wing with nanosecond pulse driven DBD plasma actuators

A 15° swept wing with dielectric barrier discharge plasma actuator is designed.Experimental study of flow separation control with nanosecond pulsed plasma actuation is performed at flow velocity up to 40 m/s. The effects of the actuation frequency and voltage on the aerodynamic performance of the swept wing are evaluated by the balanced force and pressure measurements in the wind tunnel. At last, the performances on separation flow control of the three types of actuators with plane and saw-toothed exposed electrodes are compared. The optimal actuation frequency for the flow separation control on the swept wing is detected, namely the reduced frequency is 0.775, which is different from 2-D airfoil separation control. There exists a threshold voltage for the low swept wing flow control. Before the threshold voltage, as the actuation voltage increases, the control effects become better. The maximum lift is increased by 23.1% with the drag decreased by 22.4% at 14°, compared with the base line. However, the best effects are obtained on actuator with plane exposed electrode in the low-speed experiment and the abilities of saw-toothed actuators are expected to be verified under high-speed conditions.     

火箭返回制导动力着陆段的自适应启动方法

针对重复使用火箭垂直返回着陆问题,提出了一种燃料最优的动力着陆段自适应启动方法。首先,将燃料最优启动点对应的动力着陆轨迹的推力剖面和攻角剖面描述为解析的形式,该解析形式中攻角剖面由状态量唯一确定,推力剖面仅含一个待定参数。随后,通过预测具有上述解析剖面形式的轨迹判断是否启动动力着陆。计算中引入松弛终端位置约束的策略求解推力剖面待定参数,由终端位置约束判断是否满足燃料最优启动条件。上述策略将燃料最优启动条件的判断问题简化为单一变量求解问题,实现了该问题的快速求解。仿真结果表明,该方法得到的启动点与数值优化方法得到的燃料最优启动点接近,且求解过程稳定、计算效率高。