山地降水垂直分布三参数高斯模式及其应用

针对蒋忠信山地降水高斯模式计算中的问题,提出三参数高斯模式及其非线性回归计算方法,将其应用于我国部分山地降水中,效果较好。     

三分量地震检波器的转换公式及误差分析

54.74°型三分量检波器在某种环境下按置常发生偏差,本文研究在偏差情况下的信号转换公式及误差分析。     

关于数字相位式测距仪的频率改正

本文在分析自动脉冲数字测相基本原理的基础之上，推出了不仅与测距频率有关，而且还与填充脉冲频率及低频测相频率有关的新的频率改正公式，并给出新的频率改正公式与传统频率改正公式之间等同的条件，即有锁相环路（或频率跟踪电路）的正常工作来保证。     

四种计算地震反应数值方法的比较研究

本文在简要总结了计算单自由度系统地震反应频域方法和时域方法的特点之后,按照统一的递归公式,系统地对计算单自由度体系的四种时域方法即中心差分方法、Newmark方法、Z变换方法、Duhamel逐步积分法进行了对比研究。通过递归系数b1和b2的不变性、传递函数的低频约束条件和相位特性以及数值分析等几个方面说明了上述方法各自的优缺点、相对精度和适用的范围。根据动力平衡方程的算子不变性,研究了上述方法的共性特征,揭示了相对位移、相对速度、相对加速度递归公式的内在联系,这表明只要知道相对位移的递归公式,相对速度、相对加速度的递归公式也就随之确定,在此基础上推荐了一套计算单自由度系统相对位移、相对速度、相对加速度地震反应的递归公式。     

The topographic bias by analytical continuation in physical geodesy

This study emphasizes that the harmonic downward continuation of an external representation of the Earth’s gravity potential to sea level through the topographic masses implies a topographic bias. It is shown that the bias is only dependent on the topographic density along the geocentric radius at the computation point. The bias corresponds to the combined topographic geoid effect, i.e., the sum of the direct and indirect topographic effects. For a laterally variable topographic density function, the combined geoid effect is proportional to terms of powers two and three of the topographic height, while all higher order terms vanish. The result is useful in geoid determination by analytical continuation, e.g., from an Earth gravity model, Stokes’s formula or a combination thereof.     

Comment and reply regarding Changyou Zhang (1995) A general formula and its inverse formula for gravimetric transformation by use of convolution and deconvolution techniques.

The incorrectness in the derivations of error formula (52) in Zhang's paper is pointed out and the correction is given. Table 3 [list of error formulae of Eqs (5)–(8)] in Zhang's paper is also corrected. Received: 25 February 1998 / Accepted: 30 June 1998     

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.     

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.     

测高数据在计算海平面时的取权

根据卫星测高数据分布所具有的低纬时稀疏、高纬时密集的特点,提出了计算平均海平面时非交叉点数据的解析定权公式和交叉点数据的解析定权公式。     

风沙运动中MAGNUS效应的数值研究

在风沙运动中,跃移沙粒一般都会伴随高速旋转,同时引起一种升力效应,即Magnus效应。采用数值模拟的方法计算了0.1Re400,转速ω为100~1000 rev.s-1范围时均匀来流中单个球形沙粒受到的Magnus力,并与Rubinow和Keller推导的Magnus力公式进行了比较。计算结果表明,在0.1Re200范围内,升力和沙粒的旋转速度成正比,随雷诺数的增大而减小。同时,Magnus效应和固定沙粒在均匀来流中的流动结构也有关系,即计算结果和Magnus力公式的升力系数比K在沙粒流动是附体的时随Re数增加逐渐减小,在Re=20~30时达到最小值,然后在沙粒流动是对称分离的时K随着Re数增加逐渐增大。当雷诺数继续增大到超过200时,沙粒本身流动状态非对称所引起的升力超过Magnus效应产生的升力,但Magnus效应的作用也不可以忽略。根据计算结果,对Magnus力公式进行了修正。另外,还发现流场速度梯度与Magnus效应并没有耦合作用,速度梯度对升力的影响可以和Magnus效应线性叠加。