数控展成电解磨削整体叶轮叶片的过切误差分析及解决方案

分析了平行直纹展成电解磨削整体叶轮叶片的过切误差,得到了过切误差计算公式,提出了用圆锥磨轮和组合式五轴联动数控方案来消除过切误差的方法。     

Modelling of the electromagnetic field in the interplanetary space and in the Earth's magnetosphere

A magnetohydrodynamic model of the solar wind flow is constructed using a kinematic approach. It is shown that a phenomenological conductivity of the solar wind plasma plays a key role in the forming of the interplanetary magnetic field (IMF) component normal to the ecliptic plane. This component is mostly important for the magnetospheric dynamics which is controlled by the solar wind electric field. A simple analytical solution for the problem of the solar wind flow past the magnetosphere is presented. In this approach the magnetopause and the Earth's bow shock are approximated by the paraboloids of revolution. Superposition of the effects of the bulk solar wind plasma motion and the magnetic field diffusion results in an incomplete screening of the IMF by the magnetopause. It is shown that the normal to the magnetopause component of the solar wind magnetic field and the tangential component of the electric field penetrated into the magnetosphere are determined by the quarter square of the magnetic Reynolds number. In final, a dynamic model of the magnetospheric magnetic field is constructed. This model can describe the magnetosphere in the course of the severe magnetic storm. The conditions under which the magnetospheric magnetic flux structure is unstable and can drive the magnetospheric substorm are discussed. The model calculations are compared with the observational data for September 24–26, 1998 magnetic storm (Dst _min=−205 nT) and substorm occurred at 02:30 UT on January 10, 1997. This revised version was published online in August 2006 with corrections to the Cover Date.     

Relationship Between Substorm Auroras and Processes in the Near-Earth Magnetotail

Although the auroral substorm has been long regarded as a manifestation of the magnetospheric substorm, a direct relation of active auroras to certain magnetospheric processes is still debatable. To investigate the relationship, we combine the data of the UV imager onboard the Polar satellite with plasma and magnetic field measurements by the Geotail spacecraft. The poleward edge of the auroral bulge, as determined from the images obtained at the LHBL passband, is found to be conjugated with the region where the oppositely directed fast plasma flows observed in the near-Earth plasma sheet during substorms are generated. We conclude that the auroras forming the bulge are due to the near-Earth reconnection process. This implies that the magnetic flux through the auroral bulge is equal to the flux dissipated in the magnetotail during the substorm. Comparison of the magnetic flux through the auroral bulge with the magnetic flux accumulated in the tail lobe during the growth phase shows that these parameters have the comparable values. This is a clear evidence of the loading–unloading scheme of substorm development. It is shown that the area of the auroral bulge developing during substorm is proportional to the total (magnetic plus plasma) pressure decrease in the magnetotail. These findings stress the importance of auroral bulge observations for monitoring of substorm intensity in terms of the magnetic flux and energy dissipation.     

应用于磁悬挂系统的200V─6OA晶体管斩波器

在大功率磁悬挂系统中，电磁铁电流必须采用开关频率较高的大功率斩波器来调节。本文介绍一个用于磁悬挂系统的大功率晶体管斩波器，它的工作电源电压为２００Ｖ，输出电流为６０Ａ，斩波频率为２ｋＨｚ，试验负载从阻性到感性，电感量达２．５Ｈ。该斩波器在一个单自由度大功率磁悬浮试验装置中完成了磁悬挂控制试验。该斩波器由不对称半桥、开关辅助网络、最优基极驱动电路ＵＡＡ４００２、一次脉冲源ＭＣ３４０６０及电流反馈环等部分构成，具有多种保护功能和良好的传输特性线性度。     

五自由度磁悬磨头电控系统研究

研究的高速磨床电磁悬浮磨头电控系统尽量采用最新技术，在保证系统 性能的前提下降低了系统造价。在该系统中采用TMS320F240 DSP芯片作为控制核心，同时控制磁悬浮轴承的悬浮和变频电机调速，采用运行效率很高的汇编语言编写控制软件，其中磁悬浮轴承是PID控制算法，电机调速为SPWM方式。磁悬浮轴承PWM功率放大器中采用能简化驱动的新型半桥电路，电机调速主电路中采用智能功率模块（IPM）。动态刚度测试和高速运转实验表明，该电控系统满足高速磨床电磁悬浮磨头的控制要求。     

STUDIES ON MAGNETIC ABRASIVE MACHINING

磁性磨料磁力研磨是近年发展起来的一种高效率、高质量的抛光方法，能够加工复杂外形工件和各种内壁、内腔表面，具有加工装置易于控制、工作环境清洁、加工成本低等优点，具有广阔的应用前景。本文设计、制造了加工装置并进行了一系列的试验，在研磨过程各主要参数对研磨的影响作了研究。试验结果表明，研磨初期加工效率较高，但随着研磨时间的延长，研磨效率降低，研磨质量提高不多；工件转速越高，研磨效率越高，而对研磨质量则没有影响；研磨存在最佳的加工间隙与电流强度值，在此条件下，研磨效率高，研磨质量也较好。本文最后对加工机理作了理论分析，认为磁极的设计与制造研磨能力好、磁性强的磁性磨料是非常重要的。     

面内强磁场下铁磁板壳的自由振动

本文研究了面内强磁场环境下铁磁板壳的自由振动问题。基于Eringen-Maugin的关于磁弹性作用的理性力学模型,从理论上推导了一般壳体在磁场中的运动方程,进而求解了面内强磁场作用下的小磁化率悬臂铁磁薄板自由振动频率。数值计算结果表明,本文模型和已有的实验结果吻合很好。     

一种小功率组合式航空发电机

先进的飞行控制系统和机载电子系统设备对轻型飞机电源系统的要求越来越高，电源系统的可靠性将直接影响到轻型飞机的安全性。本文提出了一种适用于轻型飞机的小功率组合式航空发电机方案。这种新型的“永磁─—内封闭导磁体”组合发电机既有永磁发电机的体积小、重量轻、无电刷等优点，又有内封闭导磁体发电机电压可调的优点。在发电机体积重量增加不多的情况下，免除了复杂的直流变换器，使电源系统体积最小、重量最轻，并且提高了系统的可靠性。同时采用晶体管脉宽调制激磁控制方式，使电源系统的稳压性得到提高。     

The characteristics of sharp (small-scale) boundaries of solar wind plasma and magnetic field structures

We investigate properties of large (>20%) and sharp (<10 min) solar wind ion flux changes using INTERBALL-1 and WIND plasma and magnetic field measurements from 1996 to 1999. These ion flux changes are the boundaries of small-scale and middle-scale solar wind structures. We describe the behavior of the solar wind velocity, temperature and interplanetary magnetic field (IMF) during these sudden flux changes. Many of the largest ion flux changes occur during periods when the solar wind velocity is nearly constant, so these are mainly plasma density changes. The IMF magnitude and direction changes at these events can be either large or small. For about 55% of the ion flux changes, the sum of the thermal and magnetic pressure are in balance across the boundary. In many of the other cases, the thermal pressure change is significantly more than the magnetic pressure change. We also attempted to classify the types of discontinuities observed.     

惯性器件精密零件微小毛刺去除技术研究

针对惯性器件中的外形复杂类零件、通孔交叉孔类零件、特殊材料类零件等微小毛刺去除需求,分析了现有控制工艺方法不足.通过开展高效率、高质量的零件毛刺去除试验,研究了磨粒流去毛刺、磁力研磨去毛刺、强力超声波去毛刺等精密去毛刺新方法对产品质量的影响,分析了先进去毛刺工艺方法的适用性,探索了惯性器件零件去毛刺技术发展方向.