高效相变蓄热装置结构设计及试验研究

文章针对某飞行器舱内大功率设备控温需求,提出了相变蓄热技术解决方案,建立了平板式肋片强化相变蓄热装置物理模型,根据大功率伺服舵机控制器热耗及工作模式等参数条件,采用十八烷为相变吸热材料,设计了一台高效平板式肋片相变蓄热装置,并通过地面试验研究,验证了该装置的控温性能、稳定性及等温性。试验结果表明:所设计的肋片式高效相变蓄热装置,在120 W热源功率下,可以将设备温度控制在50℃以下超过3000 s;榫槽形式的封装结构具有良好的密封性能,相变蓄热装置在多次相变循环后无泄漏;在3000 s测试时间内相变装置内部最大温差为3℃,具有很好的等温性。     

用于故障穿越的飞轮储能双三相异步电机驱动控制研究

随着海上风电场的发展和高压直流输电技术的应用,风电场系统存在交流侧故障穿越的问题。针对这个问题,提出了一种用于故障穿越的基于模块化多电平变频器和双三相异步电机的飞轮储能系统,并设计了其驱动控制方案。飞轮储能系统采用了模块化多电平技术能方便地构建大功率高压变频器,并具备扩容能力。为了提高飞轮储能系统的可靠性,采用了双三相异步电机驱动,从而提高了冗余性。接着设计了能均衡各个模块电容电压的双三相异步电机驱动控制算法。最后,基于MATLAB/Simulink仿真平台建立了风电场和飞轮储能系统的仿真模型,进行了仿真计算。仿真结果验证了飞轮储能系统的功能和驱动控制策略的性能。     

缺陷对高温合金蜂窝板弯曲力学性能的影响

采用预埋缺陷的方法,制备含有面芯脱焊缺陷的高温合金蜂窝板,进行了三点弯曲试验,研究了缺陷形状、大小、位置和蜂窝芯取向对蜂窝板三点弯曲损伤模式和承载能力的影响.研究发现,含面芯脱焊缺陷的蜂窝板在缺陷受压部位产生反向鼓包,并沿着宽度方向扩展为完全破坏;随着缺陷尺寸的增大,蜂窝板承载能力逐渐降低;当缺陷位于三点弯曲受拉面时,蜂窝板具有更高的三点弯曲极限载荷,且矩形缺陷试样的弯曲极限载荷要高于相同缺陷面积的圆形试样.最后,利用LS-DYNA对含圆形缺陷高温合金蜂窝板的三点弯曲性能进行了数值模拟分析,得到其三点弯曲过程中的应力分布状态.     

应用GPS载波确定载体姿态

本文简述了利用GPS载波相位技术进行载体姿态确定的原理，比较了目前已有的多种整周模糊度求解算法，选用最小二乘法进行了载体定姿实践，减少了备选整周模糊度的组合数，并采用多种约束信息来剔除不正确的模糊度组合，结合实验，指出了载体姿态变化和整周模糊度搜索速度的关系，提出了一种模糊度确定的辅助方法，并给出了应用算例。     

二维三角晶格的Peierls相变前后的声子色散曲面的研究

利用晶格动力学理论计算了二维三角晶格的Peierls相变前后的声子能谱。并且在第一布里渊区绘制了声子色散曲面。通过对Peierls相变前后的声子能谱比较可知，随其对称性降低，声子能谱的简并度被破缺。二维三角晶格的Peierls相变前只有两支声频支声子能谱，Peierls相变后有两支声频支声子能谱与两支光频支声子能谱，并且声频支声子能谱与光频支声子能谱不相交，两支光频支声子沿ky轴平缓地变化。     

运动单站干涉仪相位差直接定位方法

针对传统干涉仪测向定位在低信噪比(SNR)下性能降低、多频段系统复杂等缺点,本文直接利用运动单站干涉仪模糊相位差(PD)实现对地面静止辐射源定位.为解决该定位问题,结合干涉仪相位差的几何特性,提出了一种多角度距离参数化高斯和滤波(MB-RP-GMF)定位解算方法,利用相位差误差检测获得多个初始方位角,通过距离参数化得到一组滤波初始值,采用扩展卡尔曼滤波(EKF)进行定位计算.仿真结果表明,该定位方法在低信噪比下优于仅测向(BO)定位,且仅采用一组干涉仪便可对多个频段辐射源进行定位.     

Dynamics of a spacecraft and normalization around Lagrangian points in the Neptune–Triton system

The problem of a spacecraft orbiting the Neptune–Triton system is presented. The new ingredients in this restricted three body problem are the Neptune oblateness and the high inclined and retrograde motion of Triton. First we present some interesting simulations showing the role played by the oblateness on a Neptune’s satellite, disturbed by Triton. We also give an extensive numerical exploration in the case when the spacecraft orbits Triton, considering Sun, Neptune and its planetary oblateness as disturbers. In the plane a × I (a = semi-major axis, I = inclination), we give a plot of the stable regions where the massless body can survive for thousand of years. Retrograde and direct orbits were considered and as usual, the region of stability is much more significant for the case of direct orbit of the spacecraft (Triton’s orbit is retrograde). Next we explore the dynamics in a vicinity of the Lagrangian points. The Birkhoff normalization is constructed around L₂, followed by its reduction to the center manifold. In this reduced dynamics, a convenient Poincaré section shows the interplay of the Lyapunov and halo periodic orbits, Lissajous and quasi-halo tori as well as the stable and unstable manifolds of the planar Lyapunov orbit. To show the effect of the oblateness, the planar Lyapunov family emanating from the Lagrangian points and three-dimensional halo orbits are obtained by the numerical continuation method.     

不同频率及相转移催化剂条件下的安息香缩合反应

本文介绍了在不同频率超声波及不同相转移催化剂条件下对安息香缩合反应的影响,实验发现,超声波的频率对安息香的收率有一定程度的影响,收率随着超声波频率的增加而增加。在选择的三种相转移催化剂中,采用苄基三乙基溴化铵效果最好,安息香的收率最高。     

导引头量测故障下的增量式三维制导律设计

考虑导引头量测故障下拦截机动目标的末制导问题,以提高制导系统的鲁棒性、降低制导增益、减小系统残差、避免视线角速率剧烈振荡/发散为目的,基于增量式控制方法设计了一种具有鲁棒增强特性的三维末制导律。首先,将末制导问题转化为零化视线角速率的控制问题。其次,通过弹目相对距离及视线角速率定义辅助变量,给出传统的滑模制导律作为设计参考。然后,基于增量式非线性动态逆滑模控制方法,充分挖掘视线角加速度估计信息及上一采样时刻的制导指令,得到增量式三维鲁棒制导律。最后,在目标机动及导引头量测故障下,分析并比较了两种制导律所产生的系统残差。理论分析及多工况仿真结果表明,增量式制导律不仅对目标机动及大范围失效的导引头量测故障具有强鲁棒性,而且所需制导增益也较小,同时避免了末端视线角速率严重发散的问题     

A closed-form solution for moving source localization using LBI changing rate of phase difference only

Due to the deficiencies in the conventional multiple-receiver localization systems based on direction of arrival(DOA) such as system complexity of interferometer or array and amplitude/phase unbalance between multiple receiving channels and constraint on antenna configuration,a new radiated source localization method using the changing rate of phase difference(CRPD)measured by a long baseline interferometer(LBI) only is studied. To solve the strictly nonlinear problem, a two-stage closed-form solution is proposed. In the first stage, the DOA and its changing rate are estimated from the CRPD of each observer by the pseudolinear least square(PLS) method,and then in the second stage, the source position and velocity are found by another PLS minimization. The bias of the algorithm caused by the correlation between the measurement matrix and the noise in the second stage is analyzed. To reduce this bias, an instrumental variable(IV) method is derived. A weighted IV estimator is given in order to reduce the estimation variance. The proposed method does not need any initial guess and the computation is small. The Cramer–Rao lower bound(CRLB) and mean square error(MSE) are also analyzed. Simulation results show that the proposed method can be close to the CRLB with moderate Gaussian measurement noise.