用假想磁荷模型计算三维静磁场的解耦问题

本文提出了用假想磁荷模型计算三维静磁场的解耦概念和实施方法,较好地解决了假想磁荷模型中的磁位跃变边界问题。通过实例计算,证明了该概念和方法的正确性。     

ENTROPY CHARACTERISTICS OF MAGNETIC REFRIGERANTS

ＥＮＴＲＯＰＹＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＭＡＧＮＥＴＩＣＲＥＦＲＩＧＥＲＡＮＴＳ￥ＹｏｕＬｉｘｉｎ；ＧｕｏＸｉａｎｍｉｎｇ；ＸｕＳｈｅｆａ（ＤｅｎａｒｔｍｅｎｔｏｆＡｉｒｃｒａｆｔＥｎｇｉｎｅｅｒｉｎｇ．ＮＵＡＡ，２９ＹｕｄａｏＳｔｒｅｅｔ．...     

磁悬挂天平系统的磁场分析与计算(60mm×60mm 磁悬挂天平技术研究之一)

磁悬挂天平系统的磁场设计好坏是磁悬挂天平系统结构设计成败的关键。而磁悬挂天平系统的磁场结构比较复杂,用简单的磁路设计方法已经不能满足更高的设计要求。本文介绍了一种求解电磁场的方法——二维电磁场有限元法,建立了相应的磁悬挂天平系统的数学模型,并应用此法,对磁悬挂天平的均匀磁场和梯度磁场分布进行了分析计算;提出了一种用于求解磁场开域问题的方法。文章中还介绍了根据磁场的计算结果来确定线圈间间距和铁芯厚度的方法。在此基础上,提出了一个60mm×60mm 的磁悬挂天平系统的设计方案,并给出了此设计方案的理论计算与实验结果的对比表。     

矩形栅格波导阵列单元的阵中特性

根据等效原理,用矩量法(MOM)导出求解仅激励中心单元条件下矩形栅格开口波导阵列各单元口面等效磁流的模型,在此基础上给出了激励单元的内部场、耦合场、反射系数、驻波系数,激励波导与阵中其他波导的耦合系数,以及远区场等阵中特性的计算公式。在不同工作频率下计算了一7单元×7单元开口波导矩形栅格阵中激励单元的等效磁流和阵中方向图,以及激励单元与阵中其他单元的耦合系数。研究表明:互耦对单元的阵中特性影响明显,阵中驻波系数明显大于孤立单元,单元间的耦合随工作频率增大而减弱。     

“Oblique” Bernstein modes in solar preflare plasma: Generation of second harmonics

Process of second harmonics generation due to development of corresponding instability has been investigated for pure electron weakly oblique Bernstein mode. This mode was supposed to be modified by taking into account the influence of pair Coulomb collisions and weak large-scale electric field in flare loop. Investigated area was located near the loop foot-point in the “lower–middle” chromosphere of active region. It has been shown, that for the Fontenla–Avrett–Loeser model of solar atmosphere the investigated process of second harmonics generation starts at the extremely low threshold values of subdreicer electric field, well before the beginning of “preheating” phase of flare process.     

磁带控制机软硬件开发

磁带记录设备是航空电子仿真系统的重要组成部分，盒式磁带机是通常采用的一种记录设备，磁带控制机实现对盒式磁带机的控制。本文介绍了磁带控制机的原理及软硬件的开发与实现，并提出和分析了开发中的一些关键问题。     

Influences of preload on the friction and wear properties of high-speed instrument angular contact ball bearings

For starved-oil or solid lubrication of high-speed instrument angular contact ball bearings, friction heating and wear are the main reasons of bearing failures. This paper presents a dynamic wear simulation model to investigate the impacts of different preload methods and the changes of preload caused by wear on bearing wear life. The integral value QV of stress and sliding velocity in the contact ellipses between a ball and the inner and outer races determines friction heating and wear. The changes of QV with the friction coefficient and the wear volume under constant-force preload and fixed-position preload are analyzed. Results show that under the same initial preload, the QV decreases with an increase of the friction coefficient for both preload methods, and the latter is slightly larger. The wear of the ball and the race is equivalent to the ball diameter reduction. The QV of constant-force preload is almost not changed with a decrease of the ball diameter, but for fixed-position preload, the value decreases firstly and then increases substantially due to insufficient preload, and slipping occurs, the ball diameter is reduced by 0.025%, while the preload is reduced by 60.33%. An estimation of the bearing wear life under different preload methods requires a consideration of the changes in the wear rate of bearing parts.     

Substorm activity during the main phase of magnetic storms induced by the CIR and ICME events

In this work, the relation of high-latitude indices of geomagnetic activity (AE, Kp) with the rate of storm development and a solar wind electric field during the main phase of magnetic storm induced by the CIR and ICME events is investigated. 72 magnetic storms induced by CIR and ICME events have been selected. It is shown that for the CIR and ICME events the increase of average value of the Kp index (Kp_aver) is observed with the growth of rate of storm development. The value of Kp_aver index correlates with the magnitude of minimum value of Dst index (|Dst_min|) only for the ICME events. The analysis of average values of AE and Kp indices during the main phase of magnetic storm depending on the SW electric field has shown that for the CIR events, unlike the ICME events, the value of AE_aver increases with the growth of average value of the electric field (Esw_aver). The value of Kp_aver correlates with the Esw_aver only for the ICME events. The relation between geomagnetic indices and the maximum value of SW electric field (Esw_max) is weak. However, for the ICME events Kp_aver correlates with Esw_max.     

The relationship between inductive electric field and flares

We observationally deduce the inductive electric field in the photosphere for the first time from the horizontal velocities computed by local correlation tracking (LCT) technique and the vector magnetic fields derived from vector magnetograms. We study the relationship between E and powerful flares (X-class) of four active regions (ARs): NOAA 10720, 10486, 9077 and 8100. It is found that the kernels of flares are roughly located near the inversion lines where maxima of E are observed. Our results show that E relates to the accumulation of non-potentiality in the photosphere and the transportation of non-potentiality from the photosphere to the corona.     

动静压轴承在 MG1432 型磨床主轴系统中的应用

通过生产实践，用ＷＭＢ液体动静压混合轴承代替一般滑动轴承来改造ＭＧ１４３２型磨床，取得了理想效果。