多普勒雷达观测模式浅谈

根据五家渠多普勒雷达站的工作任务和目的，总结半年来的观测工作经验及有关雷达站的观测模式，结合新疆气候的特征，初步制定了多普勒雷达观测模式，使之能实时地准确地收集、分析雷达回波资料，以利于今后的工作。     

FTIR-derived characteristics of fossil-gymnosperm leaf remains of Cordaites principalis and Cordaites borassifolius (Pennsylvanian, Maritimes Canada and Czech Republic)

Cordaites principalis and Cordaites borassifolius, gymnosperm trees of the Carboniferous, are distinguished based on compression and cuticular morphology. A new distinction between them is suggested on the basis of differences in functional groups. Cuticular and compression spectra of C. borassifolius have lower CH₂/CH₃ ratios, suggesting more branched aliphatic chains in comparison with cuticles and compressions of C. principalis. Other differences are observed with Fourier transform infrared spectroscopy (FTIR) technique, but they vary from sample to sample of the two species to suggest other than chemotaxonomic-based sources of variations.     

Near-field horizontal and vertical earthquake ground motions

Strong-motion attenuation relationships are presented for peak ground acceleration, spectral acceleration, energy density, maximum absolute input energy for horizontal and vertical directions and for the ratio of vertical to horizontal of these ground motion parameters. These equations were derived using a worldwide dataset of 186 strong-motion records recorded with 15 km of the surface projection of earthquakes between M_s=5.8 and 7.8. The effect of local site conditions and focal mechanism is included in some of these equations.     

Deterministic and probabilistic floor response spectra

The paper presents a comparative study for computing floor response spectra (FRS) for complex structures. For the purpose of validation and evaluation of the methods for practical application, a systematic comparison of two concepts, classical deterministic and probabilistic, was carried out as an example of a nuclear power plants structure. The deterministic method utilizes time history analyses compatible with the prescribed design response spectrum. The probabilistic method uses an analysis of random vibrations for defining the probabilistic FRS influenced by random seismic soil movement. The seismic input is a power spectral density function (PSDF) compatible with the design response spectrum. The probabilistic approach based on PSDF provides satisfying FRS with far less effort and time consumption needed for calculation.     

Multifractal characteristics of general stress release（GSR）of earthquakes

Using multifractal spectrum estimating method based on the wavelet,the multifractal characteristics of GSR of earthquakes in China,Japan and New Zealand regions have been studied.It is shown that the multifractal spectra of GSR are obviously different in inter-and intra-plate regions.Moreover,though Japan and New ZeaIand are all located at the boundary of plates,West and East China are all characterized of continental tectonic structure,the multifractal spectra of GSR for both the two regions are also different.Further analysis shows that the natures of multifractal spectra of GSR are somehow related to the complexity of tectonics.     

高频地波雷达东海海洋表面矢量流探测试验

OSMAR2000高频地波雷达系统采用线性调频中断连续波体制，天线阵收发共用，应用多重信号分类法（MUSIC）和最小方差法（MVM）获得海面回波到达角. 2000年10月23～29日进行了OSMAR2000同传统海洋测量设备以及其他雷达系统的对比验证试验. 文中首先介绍雷达系统和提取海流信息所用的回波到达角估计算法，然后给出这次试验中海洋表面矢量流的有关对比测量结果. 结果表明了所研制雷达系统以及所采用信号处理方法在海洋表面流探测中的有效性.     

Attenuation modeling of recent earthquakes in Turkey

This paper deals with the derivation of a consistent set of empiricalattenuation relationships for predicting free-field horizontal components ofpeak ground acceleration (PGA) and 5 percent damped pseudoacceleration response spectra (PSA) from 47 strong ground motion recordsrecorded in Turkey. The relationships for Turkey were derived in similarform to those previously developed by Boore et al. (1997) for shallowearthquakes in western North America. The used database was compiledfor earthquakes in Turkey with moment magnitudes (M_w) = 5 thatoccurred between 1976–1999, and consisted of horizontal peak groundacceleration and 5 percent damped response spectra of accelerogramsrecorded on three different site conditions classified as rock, soil and softsoil. The empirical equations for predicting strong ground motion weretypically fit to the strong motion data set by applying nonlinear regressionanalysis according to both random horizontal components and maximumhorizontal components. Comparisons of the results show that groundmotion relations for earthquakes in one region cannot be simply modifiedfor use in engineering analyses in another region. Our results, patternedafter the Boore et al. expressions and dominated by the Kocaeli andDüzce events in 1999, appear to underestimate predictions based ontheir curves for up to about 15 km. For larger distances the reverse holds.     

Design energy input spectra for moderate‐seismicity regions

This paper proposes energy input spectra applicable to seismic design of structures located in low‐to‐moderate‐seismicity regions. These spectra represent the load effect, in terms of input energy, of the most severe earthquake that the construction might encounter during its lifetime. The spectra have been derived through dynamic response analyses of over 100 ground motion records obtained from 48 earthquakes that have occurred in Spain. An empirical equation for estimating the energy input contributable to damage from the total input energy is also suggested. This equation takes into account both the damping and the degree of plastification of the structure. Finally, the proposed design energy input spectra are compared with the provisions of the current Spanish Seismic Code and with the response spectra of recent earthquakes that have occurred in Turkey and Taiwan. Copyright © 2002 John Wiley & Sons, Ltd.     

A Ti L-edge X-ray absorption study of Ti-silicate glasses

 A series of titanium silicate glasses along the composition joins SiO₂–TiO₂, Na₂SiO₃–TiO₂, K₂SiO₃–TiO₂, and CaSiO₃–TiO₂ have been examined using titanium (Ti) L-edge X-ray absorption near-edge spectroscopy (XANES). XANES spectra were collected at the Canadian Synchrotron Radiation Facility (CSRF), University of Wisconsin, Madison, using the Spherical Grating Monochromator (SGM) beamline. Glass spectra were compared with spectra obtained from crystalline analogues with differing Ti coordination environments: β_rBa₂TiO₄ (^[4]Ti); fresnoite (^[5]Ti); and rutile and anatase (^[6]Ti). The Ti L-edge data indicate that for homogeneous TiO₂–SiO₂ glasses Ti coordination is ^[5]Ti at TiO₂ contents below 3.6 wt% but predominantly ^[4]Ti with some ^[5]Ti present above this content. There is no evidence for ^[6]Ti. For the Na₂ O-containing glasses the L-edge data indicate that Ti is ^[4]Ti with some ^[5]Ti at low TiO₂ contents, becomes a mix of ^[4]Ti and ^[5]Ti with increasing TiO₂ content, but is exclusively ^[5]Ti by 14.3 wt% TiO₂. The K₂O composition glasses exhibit similar behavior but contain a greater proportion of ^[4]Ti and less ^[5]Ti than the equivalent Na₂O-bearing glasses. These findings are consistent with previous Raman and XANES pre-edge studies. Alkaline-earth-containing glasses behave somewhat differently, with ^[5]Ti occurring in low TiO₂ content glasses, becoming a mix of ^[4]Ti and ^[5]Ti, and then gradually changing to predominantly ^[4]Ti at higher TiO₂ compositions. Finally, we have obtained data for a fresnoite composition (Ba₂TiSi₂O₈) glass. Previous pre-edge and Raman data had suggested that this composition glass contained ^[5]Ti; however, our Ti L-edge data indicate that Ti is almost exclusively ^[4]Ti, although some ^[5]Ti may also be present. Received: 20 December 2000 / Accepted: 10 July 2001     

An Analysis of a Meso-β System in a Mei-yu Front Using the Intensive Observation Data During CHeRES 2002

The conventional and intensive observational data of the China Heavy Rain Experiment and Study (CHeRES) are used to specially analyze the heavy rainfall process in the mei-yu front that occurred during 20-21 June 2002, focusing on the meso-β system. A mesoscale convective system (MCS) formed in the warm-moist southwesterly to the south of the shear line over the Dabie Mountains and over the gorge between the Dabie and Jiuhua Mountains. The mei-yu front and shear line provide a favorable synoptic condition for the development of convection. The GPS observation indicates that the precipitable water increased obviously about 2-3h earlier than the occurrence of rainfall and decreased after that. The abundant moisture transportation by southwesterly wind was favorable to the maintenance of convective instability and the accumulation of convective available potential energy (CAPE). Radar detection reveals that meso-β and -γ systems were very active in the MαCS. Several convection lines developed during the evolution of the MαCS, and these are associated with surface convergence lines. The boundary outflow of the convection line may have triggered another convection line. The convection line moved with the mesoscale surface convergence line, but the convective cells embedded in the convergence line propagated along the line. On the basis of the analyses of the intensive observation data, a multi-scale conceptual model of heavy rainfall in the mei-yu front for this particular case is proposed.