4～20GHz超宽带YIG调谐FET振荡器CAD计算和实验分析

简要介绍了采用双耦合ＹＩＧ谐振子的超宽带ＹＩＧ调谐ＦＥＴ振荡器的等效电路,并以阻抗圆图形式给出了ＣＡＤ优化设计的计算结果,稳定圆分析表明理论设计与实验结果一致。     

Segregation and intermixing in polydisperse liquid–solid fluidized beds: A multifluid model validation study

Multifluid model (MFM) simulations have been carried out on liquid–solid fluidized beds (LSFB) consisting of binary and higher-order polydisperse particle mixtures. The role of particle–particle interactions was found to be as crucial as the drag force under laminar and homogenous LSFB flow regimes. The commonly used particle–particle closure models are designed for turbulent and heterogeneous gas–solid flow regimes and thus exhibit limited to no success when implemented for LSFB operating under laminar and homogenous conditions. A need is perceived to carry out direct numerical simulations of liquid–solid flows and extract data from them to develop rational closure terms to account for the physics of LSFB. Finally, a recommendation flow regime map signifying the performance of the MFM has been proposed. This map will act as a potential guideline to identify whether or not the bed expansion characteristics of a given polydisperse LSFB can be correctly simulated using MFM closures tested.     

捷联系统四元数工具误差分离模型研究

惯性器件的误差会使导弹飞行参数计算产生偏差,直接影响导弹的命中精度,通过实验数据分离惯性器件工具误差系数并反馈给数学平台进行误差补偿是提高导弹命中精度的主要手段。在四元数的基础上建立了捷联惯导系统工具误差分离模型,并对该模型进行了工具误差系数分离。仿真实验结果验证了该工具误差模型的正确性,其系数分离结果要优于传统的欧拉角误差模型,该模型的建立为捷联惯导技术的工程实践提供了重要参考。     

能源土边界面模型的应力更新算法及算例分析

水合物的存在会显著影响能源土的刚度、峰值强度与剪胀性。针对已有能源土模型的不足,结合边界面模型的建模思想,构建一个新的能源土边界面模型,模型参数较少,能够恰当反映能源土的应力-应变关系。计算能源土变形问题的核心在于正确积分塑性本构方程,应用完全隐式回退Euler算法,建立模型应力及塑性内变量的更新公式,并给出显式的一致性切线模量表达式。基于ABAQUS软件提供的二次开发接口,编写模型的用户材料子程序,应用已有试验数据验证程序正确性。最后应用开发的子程序对能源土的平面应变试验进行模拟,分析水合物饱和度对剪切带倾角与孔隙比的影响。     

V带传动中轴向压力的研究

介绍了摩托车上常用的V型皮带式无级变速器的工作原理.通过对V型皮带式无级变速器主动轮和从动轮的力学分析,建立了皮带传动的力学关系,推导了这种传动的设计公式,并指出了现有公式的不足,在公式中引入了一个新的参数———摩擦力方向角,给出了计算V带传动当量摩擦系数的准确公式.     

Sufficient LMI stability conditions for Lur’e type systems governed by a control law designed on their Euler approximate model

In this paper, the stability issue of Lur’e systems governed by a control law stabilising their forward Euler approximate model is investigated. More specifically, the considered control law is obtained by exploiting the advantages of a new Lur’e type Lyapunov function with disconnected level sets. This Lyapunov function is adapted to discrete-time Lur’e systems and to the structure of the forward Euler approximate model. The main result consists of linear matrix inequality conditions allowing to guarantee that the continuous-time Lur’e system associated with the proposed digital control law is globally asymptotically stable. The relevance of this approach is illustrated using a numerical example.     

非结构网格多段翼型绕流Euler及N—S方程数值模拟

描述二维非结构无粘网格和粘性网格的生成方法,对二维翼型绕流进行了Euler及N－S方程数值模拟,运用推进面方法,生成无粘网格,进一步结合推进层方法,生成粘性网格,应用中心有限体积法,采用B－L代数湍流模型,完成了对多段翼型流场的Euler方程和N－S方程的数值模拟计算,计算与实验结果对比表明,所采用的网格生成技术及流场计算方法是正确、有效的。     

基于改进欧拉公式的变电站雷电过电压计算

为准确计算变电站雷电侵入波过电压,提出了基于改进欧拉公式的数值求解法。通过分别采用基于改进欧拉公式的数值求解法和基于贝杰龙法的EMTP仿真法对变电站的雷电过电压进行计算、对比,结果表明二者计算结果很接近,验证了基于改进欧拉公式的数值求解法是可行的。而与基于贝杰龙法的EMTP仿真法相比,基于改进欧拉公式的数值求解法的建模和计算过程更精确,更能准确模拟变电站遭受雷击后设备上过电压发展的实际过程。