Thermal cyclotron radiation from hot coronal loops and peculiarities of the polarization structure of solar microwave emission sources: I. Brightness temperature     

E. Ya. Zlotnik  T. I. Kaltman  O. A. Sheiner 《Astronomy Letters》2007,33(3):168-181

We discuss the possible contribution of the thermal cyclotron radiation from hot coronal magnetic loops to the observed characteristics of the microwave emission from solar active regions. Based on the simplest three-dimensional model of a loop in the shape of a hot torus, we have calculated the expected peculiarities of the frequency and polarization structures of microwave emission sources associated with sunspots and containing coronal loops. Our model calculations of the two-dimensional brightness temperature distributions at various wavelengths for the ordinary and extraordinary modes and the wavelength dependences of the brightness temperatures are presented in the first part of the work. The loop size, the electron density, and the source position on the disk have been found to affect these characteristics. Our numerical calculations of the brightness temperature distributions and spectra have confirmed the well-known assumption that under certain conditions the spectrum of a hot filament can contain cyclotron lines and the sense of the polarization can change over the range. The results obtained here refer to the brightness temperature along the line of sight that crosses the photosphere at a point with given coordinates, i.e., these are the emission characteristics at a fixed point of the source. Integrated characteristics (the flux from the entire source and its polarization) and a discussion of the hot loop model will be given in the second part of the work.  相似文献   

钢管混凝土短柱隔震装置的试验与隔震结构仿真分析   总被引：3，自引：0，他引：3  

张永山  孙峰  王焕定 《地震工程与工程振动》2000,20(2):117-121

本文阐述了钢管混凝土短柱装置的工作原理,给出了装置的构造,对隔震装置的试验结果进行了详细分析,并对传统结构模型与隔震结构模型的对比实验作了仿真计算与分析．从计算结果可知,钢管混凝土基底隔震装置具有良好的隔震性能和推广使用价值。  相似文献   

MHD waves in coronal loops with a shell     

B. B. Mikhalyaev  A. A. Solov'ev 《Astronomy Letters》2004,30(4):268-275

We consider a model of a coronal loop in the form of a cord surrounded by a coaxial shell. Two slow magnetosonic waves longitudinally propagate within a thin flux tube on the m=0 cylindrical mode with velocities close to the tube velocities in the cord and the shell. One wave propagates inside the cord, while the other propagates inside the shell. A peculiar feature of the second wave is that the plasma in the cord and the shell oscillates with opposite phases. There are two fast magnetosonic waves on each of the cylindrical modes with m>0. If the plasma density in the shell is lower than that in the surrounding corona, then one of the waves is radiated into the corona, which causes the loop oscillations to be damped, while the other wave is trapped by the cord, but can also be radiated out under certain conditions. If the plasma density in the shell is higher than that in the cord, then one of the waves is trapped by the shell, while the other wave can also be trapped by the shell under certain conditions. In the wave trapped by the shell and the wave radiated by the tube, the plasma in the cord and the shell oscillates with opposite phases.  相似文献   

A new efficient Eulerian–Lagrangian localized adjoint method for solving the advection–dispersion equation on unstructured meshes     

A. Younes  P. AckererF. Lehmann 《Advances in water resources》2006

A new and high efficient scheme is developed for the Eulerian–Lagrangian Localized Adjoint Method (ELLAM) to solve the Advection–Dispersion transport Equation (ADE) on unstructured triangular meshes. To obtain accurate results, the new method requires a very limited number of integration points (usually 1 per element).  相似文献   

TEM中心回线法计算考虑关断时间的全区视电阻率   总被引：2，自引：0，他引：2  

杨生 《物探与化探》2008,32(6)

详细推导了TEM法中心回线装置发射电流为斜阶跃波形条件下全区视电阻率迭代反演计算方法。对正演过程中对关断时间的积分采用了解析表示。对反演过程中求导运算,通过变量变换,将对电阻率的求导变换为对时间的求导,从而也给出简单的解析关系。避开了数值积分运算和差分替代导数的近似,提高了计算精度和速度。为克服迭代反演过程中要多次计算概率积分的耗时问题,采用标准数据库的方法一劳永逸地加以解决,也大大提高了计算精度和速度。对实测资料进行了计算,并通过算例对一些问题进行了讨论。  相似文献   

C-波段测风一次雷达的跟踪特性及其应用前景          下载免费PDF全文

黄炳勋 《应用气象学报》1995,6(2):153-162

利用我国研制的第一部Ｃ－波段测风一次雷达样机在成都和郑州试验现场取得的大量测试和施放记录，对该雷达跟踪固定目标的静态特性和活动目标的动态特性作了进一步统计分析。结果表明，在跟踪固定目标时，该雷达有根高的跟踪精度；在跟踪实际活动反射靶时，跟踪数据的离散度比跟踪固定目标时大，并指出，采用适当的滑动平均措施减小原始数据的离散度，并选择合适的计算水平风的时间间隔，就可获得精度高（如１ｍ／ｓ）而层结精细度合适的高空风廓线。  相似文献   

利用地面测轨资料拟合GPS广播星历   总被引：5，自引：0，他引：5  

郝金明 《测绘学院学报》1990,(1)

本文对GPS广播星历进行了系统的分析,讨论了GPS广播星历的拟合计算方法,导出了其解算公式,通过实际数据验证了公式及方法的正确性;对于广播星历拟合过程中可能出现的问题,给出了解决方法。  相似文献   

南秦岭晚三叠世胭脂坝岩体岩石磁学及磁组构可靠性约束     

牛广智  陶威  梁文天  李阳  冉亚洲 《地质通报》2016,35(9):1522-1528

胭脂坝岩体是秦岭造山带内具典型代表性意义的晚三叠世花岗岩,已有的年代学和地球化学研究对该岩体的侵位机制有不同认识。对岩体的岩石磁学进行分析,结合其岩相学特征,探讨了用磁组构约束岩体内部组构这一方法的可靠性。研究表明,胭脂坝岩体样品的平均磁化率Km值和校正磁化率各向异性度PJ值总体较低,与顺磁性花岗岩类一致。磁滞回线分析表明,绝大部分样品的磁化率来自顺磁性矿物的贡献,少部分高磁化率样品含有铁磁性矿物的贡献,但其浓度极低。高磁化率值样品的等温剩磁曲线获得和反向退磁曲线及χ-T曲线分析表明,铁磁性矿物为磁铁矿,且为多畴颗粒。结合岩相学特征,认为胭脂坝岩体低场磁组构反映了顺磁性的云母类矿物的组构特征,磁组构特征真实地记录了样品的内部组构特征。  相似文献   

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陈涛  秦天亦  陈晓森  王华 《大地测量与地球动力学》2013,33(4):88-91

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模拟分析低低跟踪模式重力卫星反演地球重力场的精度          下载免费PDF全文

冉将军  钟敏  许厚泽  周泽兵  万晓云 《地球物理学报》2015,58(10):3487-3495

本文利用卫星重力反演与模拟软件ANGELS系统(ANalyst of Gravity Estimation with Low-orbit Satellites)对低低跟踪模式的重力卫星的关键载荷精度指标进行了深入分析.模拟结果表明:(1)对短弧长积分法而言,在低低跟踪模式的关键载荷精度指标中,重力场反演精度对星间距离变率精度最为敏感;(2)通过对目前在轨运行GRACE的载荷指标进行分析,发现轨道数据的误差主要影响重力场的低阶部分(约小于25阶),较高阶次部分(约大于26阶)主要受星间距离变率的误差限制;(3)如果下一代低低跟踪模式的重力卫星的目标之一是把重力异常反演精度较GRACE提高约10倍,则在保持轨道高度和GRACE相同的前提下,轨道、星间距离变率和星载加速度计等关键载荷指标需要达到的最低精度分别约为2cm、10nm·s-1和3.0×10-10 m·s-2;(4)轨道精度和混频误差将是影响下一代低低跟踪模式重力卫星重力场恢复能力进一步提高的主要制约因素,距离变率精度和加速度计精度存在盈余.  相似文献