Location and parameters of a microwave millisecond spike event

A typical microwave millisecond spike event on November 2, 1997 was observed by the radio spectrograph of National Astronomical Observatories (NAOs) at 2.6–3.8 GHz with high time and frequency resolution. This event was also recorded by Nobeyama Radio Polarimeters (NoRP) at 1–35 GHz and Radio Heliograph (NoRH) at 17 GHz. The source at 17 GHz is located in one foot-point of a small bright coronal loop of YOHKOH SXT and SOHO EIT images with strong photospheric magnetic field in SOHO MDI magnetograph. It is assumed that the electron cyclotron maser instability and gyro-resonance absorption dominate, respectively, the rising and decay phase of the spike event. For different harmonic number of gyro-frequency or magnetic field strength, a fitting program with free plasma parameters is used to minimize the difference between the observational and theoretical values of the exponential growth and decay rates for a given spike. The plasma parameters at third harmonic number are more comparable to their typical values in solar corona. Hence, it is able to provide a diagnosis for the source parameters (magnetic field, density, and temperature), the properties of radiations (wave vector and propagation angle), and the properties of non-thermal electrons (density, pitch angle, and energy). The results are also comparable with the diagnosis of the gyro-synchrotron radiation model, the frequency drift rates and a dipole magnetic field model, as well as the YOHKOH SXT and SOHO MDI data. This study is supported by the NFSC project nos. 10333030 and 10273025, and “973” program with no. G2000078403.     

水准网闭合差自动解算的新方法

介绍一种在水准测量中独立闭合环或附合路线自动搜索及闭合差自动解算的新方法。该方法将间接平差函数模型转化为条件平差函数模型,利用条件方程式的所有信息,搜索出独立闭合环或附合路线并快速解算出闭合差,与给定的限差进行比较,较好地检验并剔除粗差。最后经过编程实现该方法,用实例验证了该方法的正确性和用之进行观测值质量检核的有效性。     

低频检波器频谱补偿算法建模及仿真

采用数值仿真的方法建立了动圈式检波器的仿真模型,推导检波器传递函数,通过对实际动圈式检波器频率特性的测试,验证了动圈式检波器数值仿真模型的正确性,分析动圈检波器频率响应特性,分别对动圈式检波器的自然频率、灵敏度、阻尼比进行仿真,对不同自然频率、灵敏度、阻尼比对检波器输出频率特性的影响进行了分析,使用二阶二次型反馈补偿方法,设计检波器低频补偿结构,结果表明:数值仿真模型与实际检波器的频率响应一致,补偿结构使检波器自然频率由2 Hz降低至0.2 Hz.     

地表数据驱动的与层相关的层间多次波消除方法及应用

基于反馈模型的地表相关多次波消除方法SRME(Surface-Related Multiple Elimination)近年来已得到了广泛的应用.利用共聚焦点CFP(Common Focus Point)道集代替炮集,可以将该方法扩展至层间多次波的消除.地表数据驱动的层间多次波消除方法直接利用地表观测数据进行层间多次波预测,避免了构建CFP道集所需的聚焦运算,特别是与层相关的层间多次波消除方法有效提高了多次波预测的计算效率.但地表数据驱动的与层相关的层间多次波消除方法并没有从理论上被严格地推导证明,其与CFP方法之间的关系亦未被讨论.本文在CFP方法的理论基础上推导了地表数据驱动的与层相关的层间多次波消除方法,阐明了CFP方法与地表数据驱动方法之间的内在联系.并将该方法应用于模型数据和野外实际数据,应用实例表明了所提方法的有效性.     

Feedback Mechanisms For The Atmosphere And Ocean Surface

Two kinds of feedback mechanisms in the coupling process between the atmosphere and ocean surface are identified in this paper. One is a negative feedback mechanism, which is effective in the dynamic interaction processes through momentum flux exchange. In this mechanism,the ocean extracts momentum from the atmosphere as a forcing field to generate waves, which decelerates atmospheric motions, lessening the intensity of synoptic systems. The second is a positive feedback mechanism, which is effective in the thermal interaction processes through heat flux exchange. This is a mechanism that is effective in the transport of sensible and latent heat fluxes to the atmosphere from the underlyingocean surface. As a result, the atmosphere obtains energy from the ocean, which intensifies atmospheric motions. For storm conditions typical of North Atlantic mid-latitudes, we consider these thermal and dynamical nteractions, the dominance of one over the other, and related implications for storm intensification.     

我国东北地区某些荒芜土地的景观生态建设

我国东北地区荒芜土地的主要问题是:①土地自然生产力得不到充分发挥;②土地退化。本文根据景观生态学关于人与自然共同创造的思想及生物控制共生与自然界等级组织理论,主张在东北区域的沙地上建立林、草、田复合生态系统,在沙垅间长洼地上节节修筑沙坝,控制7—8月暴雨径流,再按不同生境种植水稻、芦苇及红麻,既适应环境,又提高生产力。     

垂直地壳运动的均衡失稳条件探讨

根据Lyapunov稳定理论和耗散结构理论,分析了在均衡力作用下,地壳的均衡调整运动和地壳的反均衡运动的稳定性;推导了判断均衡地壳垂直运动失稳时的熵产生判据和条件;讨论了非线性运动过程中均衡地壳运动系统的反馈性质。作为均衡地壳非稳定性运动的两个实际例子,对青海门源6.4级地震前的重力水准资料和甘肃礼县5.0级地震前的重力水准资料进行了计算,得出了与理论基本一致的结果。     

陆地生态系统与气候相互作用的研究进展

陆地生态系统与气候系统通过地面与大气之间能量平衡、水汽交换和生物地球化学循环相互作用,影响大气中温室气体浓度和气溶胶,继而影响气候变化。较系统分析总结了当代国际上陆地生态系统与气候相互作用的最新研究进展。首先介绍了陆地生态系统与气候相互作用的机制与过程,总结了陆地生态系统与气候相互作用研究的三个发展阶段,以及当代相互作用的过程模拟研究中三类主要的全球生态系统模型,即生物物理模型、生物地理模型和生物地球化学模型。并介绍了气候对生态系统变化的响应,即两种主要的反馈机制。最后,对未来的研究方向和重点作了分析。