射电运动Ⅳ型爆发和日冕物质抛射     

陈晓娟 《天文研究与技术》1999,(2):62

射电Ⅳ型运动爆发同日冕物质抛射（ＣＭＥｓ）关系极为密切。本文基于对Ⅳ型运动爆发的研究以及ＣＭＥｓ开放场的物理条件,探讨了ＣＭＥｓ形成及抛射的物理条件。由于磁通量突然喷发,能量大量释放,在ＣＭＥ闭合场中的等离子体被加速,导致高能质子和高能电子被大磁环捕获。随着磁环内的热压Ｐ和磁压Ｐｍ的升高,当β＞βＴ时磁环将炸裂,从而产生ＣＭＥｓ。抛射出的未离化的等离子体团将产生等离子体基波与谐波辐射。随着等离子体的不断离化,高能相对论电子绕开放磁场线作螺旋飞行,这时等离体辐射降到次要地位,回旋同步加速辐射上升到主导地位,这就是射电Ⅳ型运动爆发。如果离化的早,则在微波波段也能看到Ⅳ型运动爆发。这就是微波Ⅳ型爆发,也是微波Ⅳ型爆发罕见的原因。射电运动Ⅳ型爆发源就是日冕抛射的物质。  相似文献   

基于物联网的城市管理统一业务受理平台设计与应用     

郭磊  马俊瑞  刘旭 《北京测绘》2020,(5):614-618

物联网技术在智慧城市发展中得到深化研究与应用,综合监控与处置物联网监测报警,对最终意义上实现城市管理可持续发展具有重要应用价值。本文结合项目实践应用阐述平台的研究设计思路,介绍数据实时统一分类监管,移动终端闭环处置流程,数据动态跟踪更新表达等内容,对SignalR实时通信、Vue动态更新、移动端相关服务等关键技术应用进行说明。该平台在安徽宿州智能管网PPP项目中应用成效显著。  相似文献   

MEMS IMU辅助的高性能GPS接收机设计     

唐康华  吴美平  胡小平 《测绘学报》2008,37(1):128-134

高性能稳健性的GPS卫星接收机仍然是当前研究和发展的热点。在高动态条件下,GNSS接收机设计总是涉及到跟踪动态性能所要求的环路带宽和噪声所要求的环路带宽一对矛盾体。以微惯性测量单元(MIMU)辅助的GPS接收机为实例,设计了MIMU辅助的GPS接收机搜索算法和跟踪算法,同时为减少GPS接收机对惯性器件的性能的依赖,设计了基于MIMU辅助的最优GPS接收机的环路带宽。通过仿真和车载试验对所设计的方法进行验证,仿真和试验结果表明,MIMU辅助的GPS接收机动态性能取决于MIMU的性能指标和环路的带宽,而抗干扰性能至少有13 dB的提高;跑车试验中,商用GPS接收机和研制的GPS接收机精度大体相当。同时系统还能够提供姿态角信息。  相似文献   

Acceleration Phase of Coronal Mass Ejections: I. Temporal and Spatial Scales     

Bojan Vršnak  Darije Maričić  Andrew L. Stanger  Astrid M. Veronig  Manuela Temmer  Dragan Roša 《Solar physics》2007,241(1):85-98

We study kinematics of 22 coronal mass ejections (CMEs) whose motion was traced from the gradual pre-acceleration phase up to the post-acceleration stage. The peak accelerations in the studied sample range from 40, up to 7000 m s⁻², and are inversely proportional to the acceleration phase duration and the height range involved. Accelerations and velocities are, on average, larger in CMEs launched from a compact source region. The acceleration phase duration is proportional to the source region dimensions; i.e., compact CMEs are accelerated more impulsively. Such behavior is interpreted as a consequence of stronger Lorentz force and shorter Alfvén time scales involved in compact CMEs (with stronger magnetic field and larger Alfvén speed being involved at lower heights). CMEs with larger accelerations and velocities are on average wider, whereas the widths are not related to the source region dimensions. Such behavior is explained in terms of the field pile-up ahead of the erupting structure, which is more effective in the case of a strongly accelerated structure.  相似文献   

Observation and Research on the Twisting Characteristics of Flare Loop System     

Li Rufeng  Bi Shaolan  Dun Jinping 《天文研究与技术》1999,(Z1)

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｍａｇｎｅｔｉｃｆｉｅｌｄａｎｄｍａｔｅｒｉａｌｍｏｔｉｏｎｈａｖｅａｌｗａｙｓｂｅｅｎｔｈｅｐｏｉｎｔｓｔｏｗｈｉｃｈｃｌｏｓｅａｔｔｅｎｅｉｏｎｉｓｐａｉｄｉｎｔｈｅｓｔｕｄｙｏｆｓｏｌａｒｆｌａｒｅｐｒｏｃｅｓｓ.Ｅｓｐｅｃｉａｌｌｙｔｈｅｔｗｉｓｔｉｎｇｅｎｅｒｇｙｓｔｏｒｇｅｐｒｏｃｅｓｓｉｓａｐｒｏｂ ｌｅｍｔｈａｔａｕｔｈｏｒｓｏｆｍａｎｙｆｌａｒｅｔｈｅｏｒｉｅｓａｎｄｍｏｄｅｌｓｈｏｐｅｔｏｒｅｓｏｌｖｅ .Ｇｏｌｄ＆Ｈｏｌｙｅ ( 1 96 0 ) ｐｒｅｓ…  相似文献   

第23太阳活动周期太阳风参数及地磁指数的统计分析   总被引：2，自引：1，他引：1       下载免费PDF全文

沈晓飞  倪彬彬  顾旭东  周晨  刘勇  项正  赵正予 《地球物理学报》2015,58(2):362-370

日冕物质抛射(Coronal Mass Ejection,简称CME)和共转相互作用区(Corotating Interaction Region,简称CIR)是造成日地空间行星际扰动和地磁扰动的两个主要原因,提供了地球磁暴的主要驱动力,进而显著影响地球空间环境.为深入研究太阳风活动及受其主导影响的地磁活动的时间分布特征,本文对大量太阳风参数及地磁活动指数的数据进行了详细分析.首先,采用由NASA OMNIWeb提供的太阳风参数及地磁活动指数的公开数据,通过自主编写matlab程序对第23太阳活动周期(1996-01-01—2008-12-31)的数据包括行星际磁场Bz分量、太阳风速度、太阳风质子密度、太阳风动压等重要太阳风参数及Dst指数、AE指数、Kp指数等主要的地磁指数进行统计分析,建立了包括269个CME事件和456个CIR事件列表的数据库.采用事例分析法和时间序列叠加法分别对两类太阳活动的四个重要太阳风参数(IMF Bz、太阳风速度、太阳风质子密度、太阳风动压)和三个主要地磁指数(Dst、AE、Kp)进行统计分析,并研究了其统计特征.其次,根据Dst指数最小值确定了第23太阳活动周期内的355个孤立地磁暴事件,并以Dst指数最小值为标准将这些磁暴进一步分类为145个弱磁暴、123个中等磁暴、70个强磁暴、12个剧烈磁暴和5个巨大磁暴.最后,采用时间序列叠加法对不同强度磁暴的太阳风参数和地磁指数进行统计分析.统计分析表明,对于CME事件,Nsw/Pdyn(Nsw表示太阳风质子密度,Pdyn表示太阳风动压)线性拟合斜率一般为正;对于CIR事件,Nsw/Pdyn线性拟合斜率一般为负,这可作为辨别CME和CIR事件的一种有效方法.从平均意义上讲,相较于CIR事件,CME事件有更大的南向IMF Bz分量、太阳风动压Pdyn、AE指数、Kp指数以及更小的Dstmin.一般情况下,CME事件有更大的可能性驱动极强地磁暴.总体而言,对于不同强度的地磁暴,Dst指数的变化呈现出一定的相似性,但随着地磁暴强度的增强,Dst指数衰减的速度变快.CME和CIR事件以及其各自驱动的地磁暴事件有着很多不同,因此,需要将CME事件驱动的磁暴及CIR事件驱动的磁暴分开研究.建立CME、CIR事件及地磁暴的数据库以及获取的统计分析结果,将为深入研究地球磁层等离子体片、辐射带及环电流对太阳活动的响应特征提供有利的帮助.  相似文献   

秦岭造山带晚三叠世糜署岭岩体的岩石磁学及磁组构可靠性约束   总被引：2，自引：0，他引：2       下载免费PDF全文

梁文天  靳春胜  Prayath Nantasin  张国伟 《地球物理学报》2015,58(3):953-970

近年来,针对秦岭造山带晚三叠世花岗岩体侵位机制的巨大争议,一些研究采用磁组构方法分析了岩体的内部组构特征及其与区域构造的关系,提出了具有重要意义的新认识.然而,目前这些研究均缺乏对岩体磁组构本质意义的分析,利用该方法约束岩体内部组构的可靠性并不十分清晰.针对这一问题,本文以秦岭造山带内具典型代表性意义的晚三叠世糜署岭花岗岩体为例,开展了该岩体的磁组构、岩石磁学、矿物形态组构和显微构造的综合研究.结果表明,糜署岭岩体的磁化率总体较低,属钛铁矿系列花岗岩.绝大部分样品的磁化率受控于顺磁性的黑云母等铁镁硅酸盐矿物,部分高磁化率样品包含了少量多畴磁铁矿等铁磁性组分的贡献,且随磁化率增大,铁磁性组分的贡献更为明显.样品的磁组构也主要是黑云母组构或由黑云母与磁铁矿的亚组构复合而成.由于样品中磁铁矿含量较低且与黑云母密切共生,磁组构与黑云母形态组构基本一致,因此,黑云母与磁铁矿的亚组构基本共轴.糜署岭岩体的磁组构本质上等同于黑云母组构,反映了黑云母等页硅酸盐矿物在岩体中的分布,可以有效的指示岩体的内部构造特征.宏观和显微构造观察还显示,糜署岭岩体的内部组构形成于岩浆侵位的晚期阶段,叠加了同岩浆期区域构造的关键信息,是从岩体构造角度开展区域构造演化的良好载体.  相似文献   

Expected in Situ Velocities from a Hierarchical Model for Expanding Interplanetary Coronal Mass Ejections     

P. Démoulin  M. S. Nakwacki  S. Dasso  C. H. Mandrini 《Solar physics》2008,250(2):347-374

In situ data provide only a one-dimensional sample of the plasma velocity along the spacecraft trajectory crossing an interplanetary coronal mass ejection (ICME). Then, to understand the dynamics of ICMEs it is necessary to consider some models to describe it. We derive a series of equations in a hierarchical order, from more general to more specific cases, to provide a general theoretical basis for the interpretation of in situ observations, extending and generalizing previous studies. The main hypothesis is a self-similar expansion, but with the freedom of possible different expansion rates in three orthogonal directions. The most detailed application of the equations is though for a subset of ICMEs, magnetic clouds (MCs), where a magnetic flux rope can be identified. The main conclusions are the following ones. First, we obtain theoretical expressions showing that the observed velocity gradient within an ICME is not a direct characteristic of its expansion, but that it depends also on other physical quantities such as its global velocity and acceleration. The derived equations quantify these dependencies for the three components of the velocity. Second, using three different types of data we show that the global acceleration of ICMEs has, at most, a small contribution to the in situ measurements of the velocity. This eliminates practically one contribution to the observed velocity gradient within ICMEs. Third, we provide a method to quantify the expansion rate from velocity data. We apply it to a set of 26 MCs observed by Wind or ACE spacecrafts. They are typical MCs, and their main physical parameters cover the typical range observed in MCs in previous statistical studies. Though the velocity difference between their front and back includes a broad range of values, we find a narrow range for the determined dimensionless expansion rate. This implies that MCs are expanding at a comparable rate, independently of their size or field strength, despite very different magnitudes in their velocity profiles. Furthermore, the equations derived provide a base to further analyze the dynamics of MCs/ICMEs.  相似文献   

The Recovery of CME-Related Dimmings and the ICME’s Enduring Magnetic Connection to the Sun   总被引：1，自引：1，他引：0  

G. D. R. Attrill  L. van Driel-Gesztelyi  P. Démoulin  A. N. Zhukov  K. Steed  L. K. Harra  C. H. Mandrini  J. Linker 《Solar physics》2008,252(2):349-372

It is generally accepted that transient coronal holes (TCHs, dimmings) correspond to the magnetic footpoints of CMEs that remain rooted in the Sun as the CME expands out into the interplanetary space. However, the observation that the average intensity of the 12 May 1997 dimmings recover to their pre-eruption intensity in SOHO/EIT data within 48 hours, whilst suprathermal unidirectional electron heat fluxes are observed at 1 AU in the related ICME more than 70 hours after the eruption, leads us to question why and how the dimmings disappear whilst the magnetic connectivity is maintained. We also examine two other CME-related dimming events: 13 May 2005 and 6 July 2006. We study the morphology of the dimmings and how they recover. We find that, far from exhibiting a uniform intensity, dimmings observed in SOHO/EIT data have a deep central core and a more shallow extended dimming area. The dimmings recover not only by shrinking of their outer boundaries but also by internal brightenings. We quantitatively demonstrate that the model developed by Fisk and Schwadron (Astrophys. J. 560, 425, 2001) of interchange reconnections between “open” magnetic field and small coronal loops is a strong candidate for the mechanism facilitating the recovery of the dimmings. This process disperses the concentration of  “open” magnetic field (forming the dimming) out into the surrounding quiet Sun, thus recovering the intensity of the dimmings whilst still maintaining the magnetic connectivity to the Sun. Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.  相似文献   

Recycling of Cathode Ray Tubes (CRTs) in Electronic Waste     

Sunil Herat 《洁净——土壤、空气、水》2008,36(1):19-24

The management of used electrical and electronic equipment (EEE) or e‐waste is a significant problem worldwide due to rapid uptake of the technology and early obsolescence of EEE. Cathode ray tubes (CRTs) from used televisions and computer monitors represent a major e‐waste problem as they consist of glass with different compositions. The front panel is a lead‐free barium‐strontium glass whereas parts such as the funnel hidden inside are composed of glass with lead oxides. Regulations require the glass from waste CRTs to be recycled or re‐utilized. Closed‐loop recycling and open‐loop recycling are two principal ways of recycling CRT glass. The aim of this paper is to examine the technical characteristics and composition of the CRTs, its generation, environmental impacts and related regulatory requirements and to review the current technologies and their limitations for recycling CRT glass and its end use.  相似文献