产品研发过程中的技术创新及知识工程的建立和应用

本文提出了产品研发过程中的技术创新,并阐述了其重要性和相关理论,简述了基于创新的知识工程及其应用。     

颗粒气体的类气液相变

颗粒体系是远离平衡态的复杂耗散体系,在外力驱动下,能表现出类似于固体、液体或气体的特性.在稀疏的颗粒气体中,由于耗散,体系中常常会形成颗粒在局部的凝聚.这种凝聚行为具有自发对称性破缺的特征,使得颗粒气体中自动形成高密度区域和低密度区域共存的非均匀状态,类似于气体中液滴的形成.本文利用零重力条件下的三维颗粒气体理论模型进行计算和分析,揭示了颗粒气体这一相变行为的不稳定性根源及类气液相变本质,给出了颗粒气体中这种相分离发生的临界条件,并通过分子动力学模拟进行检验,结果从定性上和定量上都能够很好地吻合,为进一步的空间实验提供了理论依据和相关实验参数.     

实时嵌入式软件需求描述框架探索

描述软件需求,目前最大的挑战就是保证需求描述的完整性、准确性、一致性及规范性。本文分析了实时嵌入式软件的特点,找出实时嵌入式软件需求规格说明应当覆盖的内容,并针对各项内容,分析描述所采用的方法,形成实时嵌入式软件需求描述的框架。此框架对改善需求描述的完整性、规范性有很大帮助,对提高需求描述的准确性和一致性有积极作用。     

Space-to-space Radio Interferometry System from Medium Earth Orbits

This paper presents a new concept to perform space-to-space Very Long Baseline Interferometry which enables the imaging of cosmic sources at high-resolution and high-sensitivity with small antennas. Several individual apertures are embarked on separate identical satellites staggered in height into Polar or Equatorial Circular Medium Earth Orbits (PECMEO orbits). These orbits are stable and allow GNSS-based on-the-fly centimeter-level relative positioning. Coherent operation is possible by exchanging local oscillator components and measured signals through Inter-Satellite Links (ISL). On-board cross correlation is performed at each satellite over a delay window compatible with the accuracy of the on-the-fly relative positioning and the result sent to the ground. Image reconstruction is completed on the ground thanks to sub-millimeter baseline retrieval from accurate GNSS orbits, ISL ranging and spacecraft attitude information. The application of this concept to image the Super Massive Black Hole Sgr A* is hinted.      

基于自适应二阶终端滑模的SRM直接转矩控制

传统的直接转矩控制（DTC）可以在一定程度上减小开关磁阻电机（SRM）的转矩脉动,但是在换相区的转矩脉动抑制效果较差,并且传统的PI控制存在超调量大、鲁棒性差、抗负载扰动能力有限的缺点。因此,设计了基于负载转矩变化率自适应估计的二阶终端滑模转速控制器,在有限时间内使得系统状态迅速收敛到平衡点,实现无需已知扰动上界快速输出给定转矩。此外,对传统的扇区规则进行改进以优化电压矢量的选取,减少由于换相产生的转矩脉动。仿真和实验结果表明:改进后的DTC系统拥有良好的调速控制性能,抗干扰能力强,鲁棒性好,能进一步减少转矩脉动。      

聚乙二醇对聚偏氟乙烯/亲水性高聚物性能影响

文章以聚乙二醇为聚偏氟乙烯/亲水性高聚物共混体系的添加剂,研究了聚乙二醇含量对聚偏氟乙烯/亲水性高聚物共混膜的水通量、孔径、孔隙率和耐污染性的影响。结果表明当共混体系中聚乙二醇含量为7.5%,膜的最大水通量达到1050 L/m2.h,孔隙率为73.0%,平均孔径为0.19μm,聚乙二醇含量对PVDF/B共混膜的结构和性能变化起了重要的作用,可通过调节聚乙二醇的含量来控制膜的孔径和孔隙率。     

Microwave Brightness Temperature and Lunar Soil Dielectric Property Retrieve

Among many scientific objectives of lunar exploration, investigations on lunar soil become more and more attractive to the scientists duo to the existence of abundant 3He and ilmenite in the lunar soil and their possible utilization. Although the soil composition determination on the lunar surface is available by visible light spectrometer,γ/X-ray spectrometer etc, the evaluations on the total reserves of 3He and ilmenite in the lunar deep and on the thickness of the lunar soil are still impossible so far. In this paper, the authors first give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 Meter Telescope and Siberian Solar Radio Telescope; then introduce our researches on the microwave dielectric properties of lunar soil simulators; finally, discuss some basic relations between the microwave brightness temperature and lunar soil properties.     

矩形波导H—E面均匀弯头的多模等效网络表示法

矩形波导的均匀弯头是许多地面及空间微波子系统经常使用的器件。因此，需要利用它们精确，有产儿的全波特性来开发用以分析和设计复杂波导结构的现代ＣＡＤ工具。