Storm‐event rainfall–runoff modelling approach for ungauged sites in Taiwan

This work develops a top‐down modelling approach for storm‐event rainfall–runoff model calibration at unmeasured sites in Taiwan. Twenty‐six storm events occurring in seven sub‐catchments in the Kao‐Ping River provided the analytical data set. Regional formulas for three important features of a streamflow hydrograph, i.e. time to peak, peak flow, and total runoff volume, were developed via the characteristics of storm event and catchment using multivariate regression analysis. Validation of the regional formulas demonstrates that they reasonably predict the three features of a streamflow hydrograph at ungauged sites. All of the sub‐catchments in the study area were then adopted as ungauged areas, and the three streamflow hydrograph features were calculated by the regional formulas and substituted into the fuzzy multi‐objective function for rainfall–runoff model calibration. Calibration results show that the proposed approach can effectively simulate the streamflow hydrographs at the ungauged sites. The simulated hydrographs more closely resemble observed hydrographs than hydrographs synthesized using the Soil Conservation Service (SCS) dimensionless unit hydrograph method, a conventional method for hydrograph estimation at ungauged sites in Taiwan. Copyright © 2008 John Wiley & Sons, Ltd.     

南极冰貌卫星影像条带噪声的剔除

本文在简要叙述条带噪声形成原因的基础上 ,针对南极地区的ASTER 1A的可见光影像中出现的条带噪声的现象 ,通过设计了基于切比雪夫窗、凯瑟窗的FIR滤波器和约束最小二乘FIR滤波器对其条带噪声进行剔除 ,这两种滤波器能够尽可能地剔除条带 ,同时使影像的灰度分布发生最小畸变。并通过与其他方法 (例如 :低通滤波 ,直方图匹配等 )比较 ,说明这两种滤波的方法优于其他的方法     

考虑卸荷效应钻孔灌注桩孔径时空变化规律研究

对上海地区某实际工程的钻孔灌注桩试成孔进行成孔测试,首先,统计分析测试所得孔径数据,得出了钻孔灌注桩考虑成孔卸荷效应的孔径随时间及空间的变化规律,孔径缩小量与时间呈正相关,且缩小幅度逐渐减小,最后趋于稳定;不同土层的孔径变化量不同,黏聚力c越小,内摩擦角φ越大,孔壁稳定性就越差,表现为该土层的孔径变化量越大。其次,采用科学合理的拟合公式对不同土层孔径变化进行拟合,拟合度较高,能够真实反映出孔径变化的特点和规律。最后,基于Kelvin模型,运用弹性理论,结合拟合公式,推导出更符合实际的孔径变化公式和反映孔壁稳定性的公式,并合理地解释了不同土层稳定性存在差异的原因。得出的结论对上海地区的成孔施工质量控制具有重要的价值。     

对数非线性指函数型暴雨公式的分析研究

对现有暴雨公式进行了分析,并根据暴雨公式应该具有的特性,利用雨深与历时的关系建立了三参数指数型对数非线性暴雨公式,该公式克服了现有公式的一些缺陷,能较好的反映暴雨历时强度的变化规律,精度有所提高。     

基于Peck公式的双线盾构引起的土体沉降预测

基于Peck公式,对双线水平平行盾构隧道施工中土体损失引起的三维土体沉降计算方法进行研究。考虑先行隧道施工对后行隧道的影响和两条隧道开挖面的不同位置,建立修正的三维Peck公式;通过分别计算先行盾构隧道和后行盾构隧道施工引起的土体沉降,叠加得到双线水平平行盾构施工引起的总的三维土体沉降。算例分析结果表明：预测值与实测值比较吻合;随着两条隧道开挖面前后距离的逼近,地面最大沉降量会逐渐增大;随着土体深度z的增大,沉降略增大、沉降槽宽度则略减小;当两条隧道轴线水平距离L较小时,地面沉降量较大,符合正态分布规律;随着L的增大,最大地面沉降量会逐渐减小,沉降曲线形状慢慢由V型转变成W型。     

迭代扩展卡尔曼滤波用于实时GPS数据处理

标准的卡尔曼滤波可以扩展到非线性模型,即将泰勒公式应用于状态方程和观测方程,得到扩展卡尔曼滤波公式。首先推导了计算公式,研究了迭代计算方法,并将其用于GPS数据的实时处理。     

南海神狐海域水合物三相混合层测井评价方法研究

天然气水合物降压试采过程中,水合物、游离气和水的三相混合层中的游离气首先被采出,从而提高降压效率,促进水合物分解;因此利用岩心刻度测井的方法开展南海神狐海域水合物三相混合层测井评价方法研究,对水合物矿体储量计算以及产业化开采具有重要意义.三相混合层与水合物层相比,其密度和中子孔隙度值均减小,纵波速度明显下降;与气层相比...     

On the character of distribution of chemical elements in nature

Distribution of chemical elements in nature is controlled by the general physical-chemical state of natural processes, a result of the effort to reach thermodynamic equilibrium. Natural processes, forming geologic objects (e.g., rocks, ores) usually do not reach total chemical equilibrium. This is reflected in distributions of chemical elements in nature. We recognize symmetric as well as asymmetric distributions. The question arises, what distribution in nature is most commonly followed? Evidently, this should be a distribution of chemical elements in thermodynamic equilibrium throughout the system, thus with maximum entropy. This paper notes that Gauss's normal distribution may be derived from statistic explanation of entropy as a function of contnt of chemical elements in a system with application of Einstein's formula.     

对于氟碳钡铈矿（Cordylite—Ce）成分与结构的质疑

本文讨论了氟碳钡铈矿的成分和结构问题。发现氟碳钡铈矿的成分、密度、折射率三者间的一致性参数很差,晶体结构与光性和空间群相矛盾,单个大阳离子的平均占有体积远大于同类矿物的平均占有体积,它的晶体结构与同类矿物不可类比。由于受当时条件的限制,在以往有关氟碳钡铈矿的成分和结构的资料中存在着一些明显的错误,有必要对其进行重新定义。其结构化学式应改为:(Na_(1-x),Ca_(0·5x))BaCe_2(CO_3)_4F。     

Estimation of the wave-related ripple characteristics and induced bed shear stress

A large data set on ripples was collected and examined. A set of new formulas for the prediction of the ripple characteristics is proposed with an emphasis on the disappearance of the ripples. The ripple wavelength was observed to be proportional to the bottom wave excursion but also to be a function of the grain-related Shields parameter and wave period parameter introduced by Mogridge et al. (1994). The ripple steepness was found to be nearly constant for orbital ripples, and with a sharp decrease for suborbital ripples. Two empirical functions are added including the effects of the critical Shields parameters (inception of transport and inception of sheet flow), i.e. giving the boundaries for the ripple existence's domain. The proposed formulas yield better prediction capabilities compared to the previously published formulas, especially when ripples are washed out. The effect of the ripple characteristics on the roughness height and the calculation of the bed shear stress is also discussed. It appeared that the bed shear stress calculation is more sensitive to the empirical coefficient a_r introduced in the estimation of the ripple-induced roughness height or to the limits of existence of the ripples than the ripple characteristics themselves.