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61.
Coronal mass ejections (CMEs) carry magnetic structure from the low corona into the heliosphere. The interplanetary CMEs (ICMEs)
that exhibit the topology of helical magnetic fluxropes are traditionally called magnetic clouds (MCs). MC fluxropes with
axis of low (high) inclination with respect to the ecliptic plane have been referred to as bipolar (unipolar) MCs. The poloidal
field of bipolar MCs has a solar cycle dependence. We report a cyclic reversal of the poloidal field of low inclination MC
fluxropes during 1976 to 2009. The MC poloidal field cyclic reversal on the same time scale of the solar magnetic cycle is
evident over three sunspot cycles. Approximately 48% of ICMEs are MCs, and 40% of IMCs are bipolar MCs during solar cycle 23.
The speed of the bipolar MCs has essentially the same distribution as all ICMEs, which implies that they are not from any
special type of CMEs in terms of the solar origin. Although CME fluxropes may undergo a number of complications during the
eruption and propagation, a significant group of MCs retains sufficient similarity to the source region magnetic field to
posses the same cyclic periodicity in polarity reversal. The poloidal field of bipolar MCs gives the out-of-ecliptic-plane
field or B
z
component in the IMF time series. MCs with southward B
z
field are particularly effective in causing geomagnetic disturbances. During the solar minima, the B
z
field IMF sequence within MCs at the leading portion of a bipolar MC is the same with the solar global dipole field. Our
finding shows that MCs preferentially remove the like polarity of the solar dipole field, and it supports the participation
of CMEs in the solar magnetic cycle. 相似文献
62.
This article summarizes recent developments and applications of digital photogrammetry in industrial measurement. Industrial photogrammetry covers a wide field of different practical challenges in terms of specified accuracy, measurement speed, automation, process integration, cost-performance ratio, sensor integration and analysis. On-line and off-line systems are available, offering general purpose systems on the one hand and specific turnkey systems for individual measurement tasks on the other. Verification of accuracy and traceability to standard units with respect to national and international standards is inevitable in industrial practice. System solutions can be divided into the measurement of discrete points, deformations and motions, 6DOF parameters, 3D contours and 3D surfaces. Recent and future developments concentrate on higher dynamic applications, integration of systems into production chains, multi-sensor solutions and still higher accuracy and lower costs. 相似文献