The effects of the solar magnetic polarity and the solar wind velocity on Bz-component of the interplanetary magnetic field

We have studied the effect of both solar magnetic polarity and the solar wind velocity on the Bz-component of the interplanetary magnetic field, IMFBz, for the minimum activity of the solar cycles 21, 22, 23 and 24. We made a statistical study of IMFBz in the first section which is considered as an extension of Lyatsky et al. (2003). They made a statistical study of IMFBz for two periods of minimum solar activity 22 and 23 related to 1985–1987 and 1995–1997 when the solar magnetic field had opposite polarity. Our results seem to be consistent with the results obtained by Lyatsky et al. (2003). We found that there is a dependence of IMFBz on the IMFBx and the solar magnetic polarity for the minimum periods of the selected four solar cycles. In addition, we found that there is a dependence of IMFBz on the solar wind velocity.     

一个简单有效的磁记录纠错系统

介绍一种简单有效的纠错编码方法 ,用于资源卫星高密度数字磁记录器 ,使误码率由 10 -6降低到 10 -11,同时介绍它的基本工作原理、实现方案及试验结果。     

Response of Hainan GPS ionospheric scintillations to the different strong magnetic storm conditions

Using the GPS ionospheric scintillation data at Hainan station (19.5°N, 109.1°E) in the eastern Asia equatorial regions and relevant ionospheric and geomagnetic data from July 2003 to June 2005, we investigate the response of L-band ionospheric scintillation activity over this region to different strong magnetic storm conditions (Dst < −100 nT) during the descending phase of the solar cycle. These strong storms and corresponding scintillations mainly took place in winter and summer seasons. When the main phase developed rapidly and reached the maximum near 20–21 LT (LT = UT + 8) after sunset, scintillations might occur in the following recovery phase. When the main phase maximum occurred shortly after midnight near 01–02 LT, following the strong scintillations in the pre-midnight main phase, scintillations might also occur in the post-midnight recovery phase. When the main phase maximum took place after 03 LT to the early morning hours no any scintillation could be observed in the latter of the night. Moreover, when the main phase maximum occurred during the daytime hours, scintillations could also hardly be observed in the following nighttime recovery phase, which might last until the end of recovery phase. Occasionally, scintillations also took place in the initial phase of the storm. During those scintillations associated with the nighttime magnetic storms, the height of F layer base (h’F) was evidently increased. However, the increase of F layer base height does not always cause the occurrence of scintillations, which indicates the complex interaction of various disturbance processes in ionosphere and thermosphere systems during the storms.     

潜在电路分析中的拓扑模式图形生成算法研究

在电路网络树拓扑模式被识别出来的基础上 ,推导出网络树的基本拓扑模式图形生成算法 ,以便于分析设计人员使用拓扑模式图形的方式对电路系统进行具体的潜在电路分析     

相位检测误差对核磁共振陀螺输出频率的影响

针对核磁共振陀螺中采用相位检测方案时可能引起额外频率误差的问题,提出了通过控制电子顺磁共振失谐量及静磁场扰动来抑制额外频率误差的方案。基于Bloch方程,推导了惰性气体原子系综输出频率的表达式,并将相位检测的过程包含在内。建立了考虑相位检测误差的核磁共振陀螺频率误差方程,给出了相位检测引入的额外频率误差表达式并进行了数值仿真。仿真结果表明,通过设定合适的共振失谐量,其额外频率误差至少可以抑制1个数量级,而通过精确地抑制静磁场的一阶及二阶扰动,可以进一步抑制1～3个数量级,将额外频率误差降低到nHz量级。     

超声电机温度-转速特性及补偿方法研究

针对超声电机转速随温度升高而明显降低的问题,基于电机等效电路模型,分析了电机温升对LC谐振电路电压增益和压电陶瓷片机械谐振点的影响。通过实验数据拟合计算,提出了一种针对温度变化对控制信号频率进行补偿的方法,并通过实验验证了该温补算法的有效性。     

"TC-1/2"卫星镍氢电池磁性控制方法研究

文章就"TC-1"卫星镍氢电池的磁性控制进行了细致的研究,同时对国内使用含金属镍的卫星部件,例如镉镍电池、姿控发动机等的磁性控制提出了控制方案.     

电容式微机械陀螺温度特性研究及温度补偿

电容式MEMS角速率传感器零位的全温稳定性是其实用化的最重要的技术指标之一。分析了陀螺工作原理,从传感器敏感表头的空气阻尼、谐振频率等方面分析了机械结构的温度特性,得出了在全温区内驱动力与传感器零位输出的相关性。根据对陀螺表头和接口电路的温度特性分析,设计了恒定跨导高线性度的运算放大器,实现了全温低相位偏移、低幅值偏移的接口ASIC,并在高压N阱COMS工艺下流片。通过驱动力信号对零位进行温度补偿,包含了机械结构刚度和空气热阻尼等因素的影响,理论上比单独的谐振频率补偿更准确,而且驱动力信号可直接由接口电路给出,避免复杂的采样。在-40℃60℃的温度范围内进行零位温度循环测试,驱动力幅值对零位输出进行三阶拟合补偿,补偿后全温零位温度漂移小于26.7(°)/h(1σ)。     

高转矩密度磁力齿轮的拓扑结构设计与性能比较

永磁行星齿轮和同轴永磁齿轮是两类具有不同拓扑结构和运行原理的磁力齿轮,采用定量设计比较法设计了具有相同有效体积和永磁体用量的上述两类磁齿轮,并通过有限元分析法对二者的转矩传递性能进行比较研究。研究结果表明,永磁行星齿轮较同轴永磁齿轮有更高的转矩密度和更低的转矩脉动。此外,由于永磁行星齿轮具有更加灵活的运行模式,并且能实现功率分流,使其在混合动力汽车领域有很好的应用前景。加工了一台永磁行星齿轮样机,并搭建试验平台进行了相关的试验,结果表明了该拓扑结构的有效性。     

示波器输入电容对上限截止频率测量的影响

单管放大电路是模拟电路中的一个经典实验。通过这个实验,学生可以更好地掌握静态工作点的调整和测试方法,并通过测量放大电路的主要性能指标,体会静态工作点对动态特性的影响。实验电路的上限截止频率仿真值和实测值存在较大差异,本文针对这个问题进行了详细的分析,指出示波器的输入电容是引起差异的主要原因,并进一步讨论了可有的改进测试方法。