侦察-攻击作战航空综合体效能模型分析

对侦察-攻击作战航空综合体的基本概念、组成和功能进行全面系统地阐述;并根据侦察-攻击作战航空综合体作战过程的特点,阐述了评估侦察-攻击作战航空综合体效能的数学模型,为进一步研究该类型作战航空综合体作战效能提供了一些帮助。     

数据库开放对象的数学模型

本文根据系统论提出了开放对象的概念,认为客观世界是由开放对象构成的。它本身是一个递归定义的层次结构,同时具有目的性和适应环境、改造环境的能力即具有自我进化的能力。每个开放对象与其外界的通讯只能通过信息来完成,而且允许它们对同一个消息具有完全不同的理解。开放对象实质是面向对象+人工智能+数据库的一个模型。同时本文还给出它的形式定义。     

再入飞行器和模型转换雷诺数计算

本文采用近似的激波关系、球锥体压力分布、平衡气体状态方程、边界层厚度计算公式及转捩准则等,按照流管法计算了4种再入飞行器的外流转捩雷诺数和转捩距离,并给出了高硅氧、碳石英、碳碳球锥模型的转捩雷诺数范围,对再入飞行器和模型的计算结果作了分析和比较。     

无刷双馈电机静止坐标系数学模型的研究

由于没有电刷和滑环,提高了运行的可靠性,降低了维护成本,因此无刷双馈电机(BDFM)在变速恒频发电领域有着广阔的应用前景。由于特殊的结构和工作原理,BDFM数学模型十分复杂。从BDFM多回路空间矢量数学模型出发,推导出了两个静止坐标系之间的坐标变换关系以及功率绕组静止坐标系数学模型和控制绕组静止坐标系数学模型,推导过程简洁明了。所得结果为BDFM理论分析和不同控制策略的研究提供了理论基础。MATLAB/Simulink环境下的仿真结果验证了数学模型及坐标变换关系的正确性。     

移15°双十二相隐极同步整流发电机数学模型的研究

分别在abc坐标系和dq0坐标系下建立了移15°双十二相隐极同步整流发电机的基本数学方程,推导了电机电压、磁链、输出功率、电磁转矩和转子运动方程。在MATLAB/Simulink中建立了移15°双十二相隐极同步整流发电机的仿真模型。对两路输出进行了不平衡负载仿真和试验。仿真与试验结果相比基本一致,验证了移15°双十二相隐极同步整流发电机数学模型的正确性。这为双十二相同步整流发电机运行性能和励磁控制系统的研究奠定了基础。     

Mechanism of error propagation from the subdaily Universal Time model into the celestial pole offsets estimated by VLBI

Within the analysis of space geodetic observations, errors of the applied subdaily Earth rotation model can induce systematic effects in different estimated parameters. In this paper, we focus on the impact of the subdaily Universal Time (UT1) model on the celestial pole offsets (CPO) estimated from very long baseline interferometry (VLBI) observations. We provide a mechanism that describes the error propagation from the subdaily UT1 into the daily CPO.In typical 24-h VLBI sessions the observed quasars are well distributed over the sky. But the observations, if looked at from the Earth-fixed frame, are not homogeneously distributed. The amount of observations performed in different terrestrial directions shows an irregularity which can be roughly compared to the case where the observations are collected in only one Earth-fixed direction. This peculiarity leads to artefacts in VLBI solutions, producing a correlation between the subdaily variations in UT1 and the position of the celestial pole. As a result errors in diurnal terms of the subdaily UT1 model are partly compensated by the estimated CPO. We compute for each 24-h VLBI session from 1990 until 2011 the theoretical response of the CPO to an error in the subdaily UT1 by setting up a least-squares adjustment model and using as input the coordinates of the observed quasars and observation epochs. Then real observed response of the estimated CPO derived from the VLBI session solutions is compared to the predicted one. A very good agreement between the CPO values estimated from VLBI and the predicted values was achieved. The presented model of error propagation from the subdaily UT1 into the daily CPO allows to predict and explain the behaviour of CPO estimates of VLBI solutions computed with different subdaily Earth rotation models, what can be helpful for testing the accuracy of different subdaily tidal models.     

基于多并联支路的双余度永磁同步电机伺服系统分析

为了提高永磁同步电机(PMSM)伺服系统的可靠性,提出了一种基于多并联支路的双余度PMSM伺服系统。阐述了其基本的冗余设计原理和控制驱动原理。依据电机的具体结构和控制驱动方式,建立了基于多并联支路的双余度PMSM的数学模型及其控制系统模型,包括磁链平衡方程、电压平衡方程、转矩方程、机械运动方程和电流控制系统框图及其稳定性分析。并依据建立的模型,基于MATLAB/Simulink仿真其发生故障时的工作状态,得到整个伺服系统的响应数据,从理论上验证了该伺服系统的容错性能。     

Design and optimization of a novel electrically controlled high pressure fuel injection system for heavy fuel aircraft piston engine

The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenges is to precisely control the injected fuel quantity and flow rate in the presence of pressure fluctuation. This challenge is even more serious for heavy fuel. An original design for electrically controlled high pressure fuel injection system called Multi-Pumppressure-reservoirs fuel injection System(MPS) was demonstrated to reduce the pressure fluctuation and help keep injection stable. MPS was compared with an ordinary high pressure Common Rail fuel injection System(CRS). This work established one-dimensional AMESim and mathematical models for both CRS and MPS to study the effect of different structures and geometric parameters on the pressure fluctuations. The calculations show that the average fuel pressure fluctuation of MPS can be reduced by 57% for the crankshaft speed of 1900 r/min, and the pressure fluctuation before injection reduced by 100%. It is concluded that the pressure performance of MPS is less sensitive to pressure reservoir volume than that of CRS, and there is an opportunity for further volume reduction.     

基于FMI的飞行器分系统多源异构模型一体化仿真

针对飞行器设计领域各个分系统独立建模设计,产生的多源异构模型难以进行联合数学仿真的问题,提出了采用FMI构建多源异构模型的通用通信接口,从FMU模型封装与联合仿真两方面,给出了一种一体化仿真平台解决方案。以实际项目为背景,验证了平台的兼容性和扩展性。为控制专业的设计工作提供了新的平台,解决了各分系统研发单位之间模型级交流的困难与障碍。同时使控制专业设计人员仅需要了解分系统原理,而无需完全细致了解模型内部结构甚至自行建模,就可以进行设计验证工作,缩短了产品研制周期。     

压力传感器动态特性参数不确定度评定

压力传感器动态特性参数的不确定度是表征其动态测量性能的重要指标。提出了一种压力传感器动态特性参数的不确定度评定方法。首先,使用激波管动态校准系统产生阶跃压力信号激励压力传感器,得到传感器的输出信号;其次,采用基于经验模态分解（EMD）的传感器输出信号预处理方法,减小动态校准过程中噪声的影响;然后,根据传感器的输入输出信号,采用自适应最小二乘法建立压力传感器的数学模型,进而得到其时频域动态特性参数;最后,针对重复校准实验得到的动态特性参数序列的小样本特点,采用自助法计算参数的扩展不确定度和相对不确定度。采用激波管系统对压力传感器进行多次重复动态校准实验,计算时频域动态特性参数的不确定度,并与现有方法进行对比。实验结果表明:本文方法可以弥补贝塞尔法在处理小样本量数据中的不足,且与蒙特卡罗法的不确定度评定结果相对误差小于10%,说明本文方法可以有效地评定压力传感器动态特性参数的不确定度。分析时频域动态特性参数的相对不确定度得到传感器的工作频带和超调量受噪声的影响较大,为动态校准实验条件的改善提供了重要依据。