沙漠绿洲戈壁区域同化预报系统降水预报检验

基于沙漠绿洲戈壁区域同化预报系统(Desert Oasis Gobi Regional Assimilation and Forecast System,简称"DOGRAFS"),对2012年11月1日—2013年10月31日逐日四次预报的6h累积降水量和实况资料,利用TS、ETS和BS评分统计量,对该系统的降水预报能力进行客观检验评估,结果表明:总体而言,模式预报效果存在一定的季节差异,夏秋两季预报评分高于冬春两季;对于同一降水阈值,系统不同起报时间对降水的预报结果差别不大,但总体上12 UTC略优于其它三个时次;模式对降水的预报能力随着降水阈值的增大而逐渐降低,其中,对0.1 mm·(6 h)-1阈值的降水预报性能最稳定,对3.1 mm·(6 h)-1和6.1 mm·(6 h)-1两阈值次之但预报范围与实况比较吻合,对12.1 mm·(6 h)-1以上的大阈值降水过程,整体把握能力还有待提高。另外,针对2013年5月26—29日南疆一次极端强降水天气个例进行分析,不同起报时间对强降水时段的落区和量级的预报能力参差不齐,其中26日12UTC的预报结果最优;对其增量场分析表明,同化的资料对预报初始场中、低层的风场、温度场以及湿度场都有明显的调整作用,对预报结果有较好的正效应。     

近震震源深度测定精度的理论误差分析

震源深度是地震学中最难准确测定的参数之一,各种方法对于震源深度的估计都具相当程度的不确定性,影响着人们对震源过程的认识。各种因素对震源深度的影响是非线性的,本文从近震走时公式入手,分析了震中距、到时残差和速度模型(地壳模型)对震源深度的影响。当地震波传播速度一定时,震源深度的误差随着震中距或台站距离的增大和走时残差的增大而增大。走时残差一定时,震源深度误差随着震中距的增大和地震波速度的增大而增大。研究也表明,当速度已知,走时残差一定时,越浅的地震,定位误差可能越大。定位精度产生的水平误差随着震中距、走时误差和地震波速度的增大而增大,震源深度误差也将增大。另外,震源深度的误差会导致发震时刻的变化,随之而来的结果都会因此而改变。     

Profiles of the Hα and Hβ lines in the spectra of B and Be stars in the diffuse stellar cluster h/χ Persei

High dispersion CCD spectra are used to study the profiles of the Hα and Hβ lines of 48 stars in early spectral classes in the young diffuse binary cluster h/χ Per. In addition, moderate resolution spectra of 15 B and Be stars were taken over the interval 4400–4960 Å. One or, possibly, two new Be stars are discovered. The major parameters of the Hα line are measured for the observed B and Be stars. The spectra over 4400–4960 Å are used to estimate T_eff, logg, and υsin i. No traces of emission are detected in the Hα line profiles for 28 of the stars and emission is observed in the Hα line for 20. During our observations an absorption profile of the Hα line was observed for some of the stars, such as Oo146, Oo566, Oo922, and Oo1268, although they have previously been identified as Be stars. A significant long-term variability of the Hα line is discovered for the Be stars Oo1161 and Oo2242. Oo2371 manifests a variability in its faint emission spectrum which is typical of close binary systems that include a Be star. __________ Translated from Astrofizika, Vol. 51, No. 2, pp. 305–319 (May 2008).     

Simulation of the Askervein Flow. Part 1: Reynolds Averaged Navier–Stokes Equations (k ∈ Turbulence Model)

The neutrally stratified flow over the Askervein Hill was simulatedusing a terrain-following coordinatesystem and a two-equation(k - ) turbulence model. Calculations were performed on awide range of numerical grids to assess, among other things, theimportance of spatial discretization and the limitations of theturbulence model. Our results showed that a relatively coarse gridwas enough to resolve the flow in the upstream region of the hill;at the hilltop, 10 m above the ground, the speed-up was 10% lessthan the experimental value. The flow's most prominent feature wasa recirculating region in the lee of the hill, which determinedthe main characteristics of the whole downstream flow. This regionhad an intermittent nature and could be fully captured only in the caseof a time-dependent formulation and a third-order discretization ofthe advective terms. The reduction of the characteristic roughnessnear the top of the hill was also taken into account, showing theimportance of this parameter, particularly in the flow close to theground at the summit and in the downstream side of the hill.Calculations involving an enlarged area around the Askervein Hillshowed that the presence of the nearby topography affected the flowneither at the top nor downstream of the Askervein Hill.     

The gross features of the lithosphere-asthenosphere system in Europe from seismic surface waves and body waves

Long-period recordings of dispersive Rayleigh waves along numerous station lines, or profiles, in Europe have for the first time permitted a uniform inversion of these observations based on a new method of phase velocity regionalization.Regional dispersion relations obtained by this method have then been subjected to a complete inversion procedure commonly known as the hedgehog method. The results are presented in a map outlining the thickness of the lower lithosphere (lid) and the shear (S) velocities in both the lid and the asthenosphere channel.A comparison of these results with the minimum compressional (P) wave velocities in the asthenosphere and their corresponding depths provides an estimate of theV _p /V _s ratio for the asthenosphere in the European area.Contribution No. 314, Institute of Geophysics, ETH-Zürich, Switzerland.     

印尼Mw9.0地震的短临地电波(声波:潮汐力谐振共振波,HRT波)波动前兆——HRT波法进行短临地震准确预测可能性的探讨

新研制的抗干扰高精度PS100大地电测仪器系统,在中国川滇地区的台站上记录到印尼MW9.0海啸地震的地电前兆。本文将分析论证地电前兆的波动特性,特别是其传播规律。在印尼地震前约3个月开始出现周期等于潮汐力周期(如MSf、K1、M2等)、振幅异常增大的地电潮汐力谐振波(Harmonie waves driven by tidal frces,简称HT波);地震前2天(北京时2004年12月24日10时)出现地电潮汐力共振波(Resonancewaves driven by tidal frces,简称RT波)。RT波有纵波和横波,初步确定纵波速度Vl≈307 km/h;横波速度Vt≈126 km/h,是一种在地壳多孔岩石孔隙流体中传播的声波。其固有振动周期T0=4~5 h;其振幅很大达2.9%(超出观测标准偏差17倍),异常极为显著;峰值异常尖锐,Q≈8.3。与地震同时从震源发出的RT波为断层破裂所激发,故推断地震前2天所出现的RT波系MW9.0地震震源区断层前期破裂所致。在可预见的将来,根据震前RT波出现的时间,台站所记纵、横波的到时差及T0,对强震在震前1~3天定量预测其三要素(如果有一布设合理的PS100台网)是可能的。     

既有线200km／h提速客货共线直线段轨道的动力特性

既有线提速是高速铁路发展的重要方向之一。本文主要对轨道路基在列车荷载作用下的动力响应规律进行了研究。首先,建立轨道系统在移动荷载作用下的动力响应理论分析模型,该模型将轨道结构视为连续支承欧拉梁,对ANSYS软件进行二次开发,实现了模型的数值分析;然后,建立直线段轨道数值分析模型,利用该模型分析了荷载速度、载重、不平顺波长、不平顺波深对既有线路提速200km／h客货共线直线段钢轨、轨枕的竖向位移及竖向加速度的影响。可为制定新的铁路养护技术规范提供技术参考。     

基于随机森林算法的广州白云机场终端区雷暴潜势预报

利用2014—2015年夏季雷达资料获取雷暴发生有无数据,计算探空资料的对流指数与雷暴发生有无数据的灰色关联度,发现雷暴产生跟抬升凝结高度气压、850～700 hPa的温度和露点温度、风切变的关系最紧密。接着建立广州白云机场终端区内3类区域(离塔台中心8 km、50 km、100 km)的12小时随机森林分类模型,对不同区域的雷暴潜势进行预报和评估,发现终端区区域面积越大,雷暴发生样本比例越高,临界成功指数CSI、预报准确率AF、探测概率POD越来越高,虚假报警率FAR越来越低,表明预报出来的准确率越来越高。离塔台中心50 km和100 km区域的预报准确率AF和探测概率POD超过70%,对航空重要天气MDRS通报业务有指示作用。同时袋外错误率均低于1/3,随机森林算法的泛化性能好。     

HOW TO BUILT A QUANTITATIVE GEOLOGICAL MODEL FOR A FLUVIAL RESERVOIR: OUR PRACTICE IN GUDONG OILFIELD, SHANGDONG PROVINCE EAST CHINA

1. Introduction According to the reservoir characters and actual data of the 7th tract of Gudong oilfield, we have summarized for the first time the geological concept model and log response pattern of water-cut layer with geological data and well log information. Special structure of the reservoir is studied with the variogram parameters of the reservoir. The method of indicator simulation is proved to be suitable for building quantitative geological model of fluvial reservoir with the compar…     

矿物热膨胀的晶体化学研究综述

热膨胀是矿物材料的重要属性之一,对它的研究在矿物学及材料科学中具有重要意义。前人关于矿物的热膨胀系数和晶体化学参数之间关系的研究表明,矿物的 结构、成分、化学键及原子价态、配位数、外层电子结构等对热膨胀系数都有不同程度的影响。晶体化学方法是研究矿物热膨胀系数的有效方法,但由 于矿物的热膨胀系数和晶体化学参数之间的定量关系尚未完全弄清,目前仅仅能对简单结构矿物的热膨胀系数进行计算,结构、成分较复杂的矿物的热膨胀系数计算尚缺乏好的晶体化学模型。为达到精确计算矿物热膨胀系数的目的,必须对矿物按照晶体化学特性进行分类。 在分类的基础上,把晶体化学方法和理论计算方法有效地结合起来。矿物的热膨胀性可按照 受热时结构有无旋转划分为键膨胀型和结构旋转型,过渡金属阳离子所形成的化合物根据d电子层电子云的分布进行分类。通过以上的分类,在计算不同类型矿物热膨胀系数时 ,可按矿物类型处理。对键膨胀型的矿物只需估计键的膨胀情况,而对于结构旋转型除考虑 键的膨胀性以外还要考虑配位多面体旋转的情况。