基于微处理器的PWM波形发生器及其应用

全数字式PWM波形发生芯片SA828,在微处理器控制下可以生成高精度的三相脉宽调制波形,其精度和温度稳定性是传统模拟式不可比拟的。在介绍其原理与控制方法的同时,并给出了在变频调速中应用的硬、软件设计实例。     

桅杆首阶固有频率控制与构形设计

基于Timoshenko梁理论,提出筒形桅杆首阶固有频率控制设计原理。依据该原理,采用Transfer matrix算法,研究了直壁式、外凸式及双曲式三种构形的桅杆首阶固有频率的变化规律,发现在桅杆高度、质量、顶部及底部截面边长相同的情况下,外凸式构形具有最大的首阶固有频率值。     

A higher order coupled frequency characteristics study of smartmagneto-electro-elastic composite plates with cut-outs using finite element methods

This article deals with investigating the effect of cut-outs on the natural frequencies of magneto-electro-elastic (MEE) plates incorporating finite element methods based on higher order shear deformation theory (HSDT). In order to consider the influence of cut-out, the energy of the cut-out domain is sub-tracted from the total energy of the entire plate. The governing equations of motions are derived through incorporating Hamilton's principle and the solution is obtained using condensation technique. The proposed numerical formulation is verified with the results of previously published literature as well as the numerical software. In addition, this research focuses on evaluating the effect of geometrical skewness and boundary conditions on the frequency response. The influence of cut-outs on the degree of coupling between magnetic, electric and elasticfields is also investigated.     

Fuzzy recognition of missile borne multi-line array infrared detection based on size calculating

In order to improve the infrared detection and discrimination ability of the smart munition to the dy-namic armor target under the complex background, the multi-line array infrared detection system is established based on the combination of the single unit infrared detector. The surface dimension features of ground armored targets are identified by size calculating solution algorithm. The signal response value and the value of size calculating are identified by the method of fuzzy recognition to make the fuzzy classification judgment for armored target. According to the characteristics of the target signal, a custom threshold de-noising function is proposed to solve the problem of signal preprocessing. The multi-line array infrared detection can complete the scanning detection in a large area in a short time with the characteristics of smart munition in the steady-state scanning stage. The method solves the disadvan-tages of wide scanning interval and low detection probability of single unit infrared detection. By reducing the scanning interval, the number of random rendezvous in the infrared feature area of the upper surface is increased, the accuracy of the size calculating is guaranteed. The experiments results show that in the fuzzy recognition method, the size calculating is introduced as the feature operator, which can improve the recognition ability of the ground armor target with different shape size.     

线阵CCD在弹丸飞行姿态测量中的应用

提出应用线阵CCD技术测量飞行弹丸攻角 ,建立了测量飞行弹丸攻角的计算方法。实际测量结果表明应用单个线阵CCD可以测量飞行弹丸的一个攻角分量。对测量误差进行了分析 ,发现线阵CCD的采样频率对测量误差的影响较大     

区域防入侵中振动目标威胁评估研究

在分析地振动目标信号特征的基础上,提出了振动目标的威胁属性参数;建立了目标威胁隶属度函数和威胁等级判决模型;运用层次分析法确定了各目标威胁参数的权值,构建了振动目标的威胁评估函数,并通过实例验证了评估结果的合理性和实用性。     

基于随机拟合的悬浮式深弹弹阵特征建模＊

通过分析悬浮式深弹发射后在空中的弹道特性,建立了深弹弹着点坐标的计算模型。采取蒙特卡洛方法,分别对舰艇六自由度状态下,单管和六联装火箭深弹的弹着点坐标进行了仿真计算,对弹着点的分布规律进行了研究,并得出弹着点的联合密度函数。结果表明,在发射参数存在正态扰动时,弹着点散布区域均呈椭圆形分布,弹着点坐标均仍服从正态分布。     

声表面波对汽油胶质含量响应特性的理论与实验研究

从理论上分析了沉积于压电基片表面的汽油胶质对声表面波（SAW）传播特性的影响,在此基础上参照国家标准规定的汽油胶质含量测定试验条件,基于自制的SAW传感器,实验研究了SAW对不同汽油胶质含量的响应特性.结果表明SAW传感器的中心频率及幅度随SAW传播路径上沉积胶质的含量变化表现出敏感且单调的变化规律,这一结果可为车用汽油胶质含量的快速检测提供参考.