地磁平静期间磁层高能粒子非垂直地磁截止刚度研究

地磁截止刚度是定量衡量地球磁场对高能粒子屏蔽效应的参数,描述了高能粒子穿越磁层到达指定观测点的带电粒子刚度阈值.人们一直研究垂直方向上的截止刚度,但对作为方向函数的截止刚度,缺少详细研究.我们使用单粒子方法,倒向追踪粒子的运动状态,计算了近地空间不同投掷角度的高能粒子地磁截止刚度,研究发现:(1)天顶方向或者垂直方向的...     

Models as multiple working hypotheses: hydrological simulation of tropical alpine wetlands

Tropical alpine grasslands, locally known as páramos, are the water towers of the northern Andes. They are an essential water source for drinking water, irrigation schemes and hydropower plants. But despite their high socio‐economic relevance, their hydrological processes are very poorly understood. Since environmental change, ranging from small scale land‐use changes to global climate change, is expected to have a strong impact on the hydrological behaviour, a better understanding and hydrological prediction are urgently needed. In this paper, we apply a set of nine hydrological models of different complexity to a small, well monitored upland catchment in the Ecuadorian Andes. The models represent different hypotheses on the hydrological functioning of the páramo ecosystem at catchment scale. Interpretation of the results of the model prediction and uncertainty analysis of the model parameters reveals important insights in the evapotranspiration, surface runoff generation and base flow in the páramo. However, problems with boundary conditions, particularly spatial variability of precipitation, pose serious constraints on the differentiation between model representations. Copyright © 2010 John Wiley & Sons, Ltd.     

隅撑支撑钢框架的抗震性能

隅撑支撑框架是一种新型的耗能支撑钢框架结构形式,在小震作用下,具有较大的抗侧移刚度,在大震作用下,具有较好的耗能性能。隅撑是隅撑支撑框架中的耗能构件,其设计参数对隅撑支撑框架的抗震性能有重大影响。本文主要通过非线性有限元分析,探讨了隅撑的设计参数对隅撑支撑钢框架抗震性能的影响。     

沿高变刚度设支撑高层大开间异型柱框架抗震性能试验研究

提出了沿异型住框架楼层变刚度设支撑的设计方法,进行了1／3结构模型试验研究,测试分析了弹性侧移刚度、结构的承载力、延性、滞回曲线、破坏机制及刚度衰减特性。计算所得的结构弹性侧移刚度与实测值符合较好．     

纤维增强混凝土异形柱框架抗震性能的试验研究

通过薄弱部位应用纤维增强的混凝土异形柱框架和同条件下无纤维异形柱框架的拟静力试验研究,对比了两榀框架的破坏特征、出铰顺序、承载能力和延性、滞回特性、耗能能力及刚度退化等抗震性能指标。研究表明：应用纤维增强的异形柱框架承载能力和整体刚度显著提高,薄弱部位破坏程度减轻,耗能能力有所增强,纤维可以改善异形柱框架薄弱部位的抗震性能,提高异形柱框架结构的整体抗震能力。     

Rigidity of the fault zones in the Earth’s crust estimated from seismic data

Nonlinear effects in seismic wave propagation are analyzed to determine the mechanical rigidity of different-order faults that thread the tectonic structures in the central part of the East European platform (Moscow syneclise and Voronezh Crystalline Massif) and the fault zones of the Balapan and Degelen mountain regions in Kazakhstan (the Degelen magmatic node in the Central Chingiz zone). The dependency of the rigidity of the fault zone on the fault’s length is obtained. The rigidity of the tectonic structures is found to experience well-expressed temporal variations with periods of 13–15 days, 27–32 days, and about one year. In the different-order fault zones, the amplitudes of both normal k _n and the shear k _s rigidity for semimonthly, monthly, and annual variations can span a factor of 1.3, 1.5, and 2.5, respectively.     

Cosmic ray geomagnetic cutoff rigidities in the magnetic field of two empirical models during a strong disturbance in November 2003: A comparison of models

Cosmic ray (CR) fluxes, which penetrate into the Earth??s magnetosphere and atmosphere from the interplanetary space, are an important factor of space weather. The geomagnetic field allows or forbids CR particles to enter into a given point in the magnetosphere depending on their energy. The geomagnetic cutoff rigidity regulates the distribution of CR fluxes in the magnetosphere. The geomagnetic cutoff rigidity (geomagnetic threshold) determination accuracy is closely related to the accuracy of the magnetospheric model used in calculations. Using a method for tracing of charged CR particle trajectories in the magnetic field of a model magnetosphere, we obtained geomagnetic thresholds for two magnetosphere empirical models (Ts01 and Ts04), constructed based on the same initial database. The Ts01 model describes the middle magnetosphere for certain conditions in the solar wind and interplanetary field. The Ts04 model pays the main attention to describing the large-scale evolution of magnetospheric currents during a storm. The theoretically obtained geomagnetic thresholds have been compared with experimental thresholds, calculated using the spectrographic global survey method based on data from the global network of CR stations. The study has been performed for the period of a strong geomagnetic storm that occurred in November 2003.     

Cosmic rays during great geomagnetic storms in cycle 23 of solar activity

Variations in the cosmic ray intensity (specifically, Forbush effects) and in the geomagnetic cutoff rigidity planetary system during powerful geomagnetic disturbances in cycle 23 were studied based on worldwide station network data by the global spectrographic survey method. The cosmic ray variation spectra during these periods and the spectral indices of these variations when the spectrum was approximated by the power function of the particle rigidity varying from 10 to 50 GV during different Forbush effect development phases are presented. It was indicated that the spectral indices of cosmic ray variations during spectrum approximation by the power function of the particle rigidity are larger during the maximal modulation phase than during the cosmic ray intensity decline and recovery phases. The fact that the amplitude of the second harmonic of the cosmic ray pitch angle anisotropy did not increase on November 20, 2003, confirms that the Earth fell into a Sun-independent spheromark magnetic cloud. The increased amplitudes of the second harmonic of the cosmic ray pitch angle anisotropy during other Forbush effects in July 2000, March–April 2001, October 2003, and November 2004 indicate that the Earth was in the coronal mass ejection region, in which the interplanetary magnetic field structure was loop-like during these periods.     

The rigidity spectrum of the harmonics of the 27-day variation of the galactic cosmic ray intensity in different epochs of solar activity: 1965–2002

We study temporal changes of the rigidity (R) spectrum of the harmonics of the 27-day variation of the galactic cosmic ray (GCR) intensity using neutron monitors (NM) data for the period 1965–2002. We show that the rigidity spectrum of the third harmonic (9 days) of the 27-day variation of the GCR intensity changes in a similar way as the spectra of the first and second harmonics, being hard in the maximum epochs and soft in the minimum epochs of solar activity. We ascribe this finding to the alternation of the sizes of the modulation regions of the 27-day variation of the GCR intensity in different epochs of solar activity. The average size of the vicinity of the corotating interaction regions, causing the 27-day variation of the GCR intensity, is less in the minimum epochs than in the maximum epochs of solar activity. A vicinity of the corotating interaction regions of larger size involves in modulation higher rigidity particles of GCR than the vicinity of smaller size; thus, this statement can be considered as one of the reasons leading to the hardening of the rigidity spectrum of the harmonics of the 27-day variation of the GCR intensity in maximum epochs compared with minimum epochs of solar activity.We also show that the temporal changes of the power rigidity spectrum of the third harmonic of the 27-day variation of the GCR intensity are negatively correlated with the rigidity spectrum of the 11-year variation of the galactic cosmic ray intensity.We found a recurrence in the temporal changes of the amplitudes of the first harmonic of the 27-day variation of the GCR intensity and in some parameters of solar activity and solar wind.     

Sensitivity of cosmic ray trajectory calculations to geomagnetic field model representations

Cosmic ray vertical cutoff rigidities at sea level have been calculated, using the trajectory-tracing method, for a number of different epochs. These calculations have been carried out for a world-wide grid of locations, and, in an effort to locate the cosmic ray equator, for a fine grid in the equatorial region. Comparison of the vertical cutoff rigidity values obtained using the International Geomagnetic Reference Field model for 1980.0 with those obtained from previous models shows systematic significant changes in the Atlantic Ocean region and over South America. The differences are greater than those predicted utilizing the older field models with their predicted secular change. The cutoff rigidity values calculated using the new IGRF 1980.0 field model appear to be in better agreement with data from cosmic ray latitude surveys in the Atlantic Ocean region. The changes in the cosmic ray equator are asymmetrical with essentially no changes in the equator position in the Asian and Pacific region, but with significant changes in the South American, Atlantic Ocean and West African regions. Calculations have also been undertaken for different directions of arrival for a satellite orbiting at 400 km altitude using the predicted 1980 field model and the interim 1980 field model adopted in 1981. Some differences have been found.     

The possibility of the propagation of Love type waves in an intermediate heterogeneous layer lying between two semi-infinite isotropic homogeneous elastic layers

Summary The conditions under which Love type ofSH waves can propagate in a non-homogeneous internal stratum of finite depth lying between two semi-infinite isotropic elastic media are considered in this paper. Two types of non-homogeneity have been studied, in one case the rigidity is supposed to vary exponentially with depth while the density remains constant and in the other both rigidity and density are assumed to vary linearly with depth.     

Solar proton event in December 2006

The variations in the rigidity spectrum and anisotropy of cosmic rays in December 2006 have been studied based on the surface measurements of the cosmic ray intensity at the global network of stations, using the method of global spectrographic survey. It has been indicated that the highest degree of anisotropy (to ～50%) with the maximal intensity of particles with a rigidity of 4 GV in the direction from the Sun (an asymptotic direction of about ?25° and 160°) was observed at 0400 UT on December 13. The parameters of the cosmic ray rigidity spectrum, which reflect the electromagnetic characteristics of the heliospheric fields during the studied period, have been determined when the surface and satellite measurements of protons in the energy range from several megaelectronvolts to several tens of gigaelectronvolts were jointly analyzed. The observed anisotropy and variations in cosmic rays in a wide energy range have been explained based on an analysis of the results.     

纬向正常密度假说与内波假说的比较

本文简要介绍了大陆漂移及板块运动动力问题研究的历史背景、以及我国地学工作者最新提出的“内波假说”和“纬向正常密度假说”在这一问题上的基本观点.针对地壳运动及板块运动的动力机制问题,对“内波假说”和“纬向正常密度假说”的基本观点进行了初步的比较.     

古震源实体初步研究

古震源区地震断裂成因的假玄武玻璃显微构造、基质成分及其与区域构造演化关系的研究表明.随地壳抬升和相应的温度降低,在大约10～15km的深度上,长石质岩石先于石英质岩石从韧性转变为脆性性状,是导致韧性剪切带中局部应变不稳定和地震发生的主要原因。对地震断层岩石的多样性和地震成因的二相变形理论模型进行了讨论     

On the effect of non-homogeneity

Summary Effects of non-homogeneity in respect of rigidity have been computed in the case of a gravitating sphere with a rigid core. For an isotropic spherical shell the effect of variation of rigidity has been calculated when the shell is under pressure or when the shell is subjected to some steady temperature on its internal surface.     

Nature of spatiotemporal variations in the rigidity of rock masses in seismically active zones of the San Andreas fault (Northern California)

The paper presents results of analysis of spatiotemporal variations in the rigidity of seismically active rock masses obtained from California Integrated Seismic Network data on first arrivals of P waves from local background (M < 5.0) earthquakes. The main goal was to determine sizes of zones of an anomalous response to the nucleation of strong earthquakes and to reveal specific features of dynamic manifestations of anomalies in crustal fault zones. As a result, conclusions are drawn on the nature of the variations, their implications for the development of strong earthquake sources, and their suitability for earthquake prediction.     

节点刚度对2008奥运羽毛球热身馆单层网壳稳定性影响研究

利用Matrix27单元，对节点半刚性问题进行了APDL二次开发。利用调整节点刚度程序，研究了节点刚度与特征值之间的曲线关系，并重点研究了节点刚度对单层网壳稳定性的影响。通过单层网壳中节点刚度的研究，得到了几点有益的结论，为该类结构的设计提供数据资料和依据。     

Phenomena of Hysteresis in the Cutoff Rigidity of Cosmic Rays during the Superstorm of November 7–8, 2004

Geomagnetism and Aeronomy - The ability of cosmic rays to penetrate the magnetosphere is characterized by the rigidity of the geomagnetic cutoff R, i.e., the stiffness below which the particle flux...     

On love wave dispersion in a homogeneous layer lying over a laterally heterogeneous half-space

A method is proposed for the determination of the dispersion equation of Love waves propagating in a homogeneous layer lying over a laterally inhomogeneous half-space. The proposed method can be made to work only when the lateral inhomogeneities in the lower half-space are finite in nature so that their Fourier transforms are available. As an illustration the dispersion equation of Love waves is obtained for one of such media in which the shear-wave velocity and the rigidity in the lower half-space either increases or decreases along the direction of propagation of waves according as the parameter of heterogeneity is positive or negative.     

Variations in the geomagnetic cutoff rigidity of cosmic rays at individual points of the Asian region during the extreme events of 2003

The variations in the geomagnetic cutoff rigidity in Irkutsk, Alma-Ata, and Beijing in October–November 2003 were calculated using ground-based measurements of cosmic ray intensity from the worldwide network of stations and GOES spacecraft. The calculated variations in geomagnetic cutoff rigidity are presented together with D _st variations of the geomagnetic field. The obtained results are compared to calculations performed using the Tsyganenko model of the magnetosphere.