用欧拉方程估算埋深和形状因数

本文论述了用欧拉方程估算埋深和形状因数的方法原理,并用模型计算加以验证,最后用湖南某地含原生金刚石的钾镁煌斑岩筒上的ΔＴ异常证实这种估算方法是值得推广的。     

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.     

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。     

重力场向下延拓Milne法

重力场向下延拓能够突出局部和浅部的异常信息,分离叠加的异常特征.但是向下延拓通常具有过程不稳定、下延深度小、结果不准确等问题.针对向下延拓所存在的不足,本文利用重力场及其垂向一阶导数,基于辛普森（Simpson）求积公式,推导出重力场向下延拓米尔尼（Milne）公式.将本文向下延拓方法应用于模型数据,向下延拓模型结果及误差曲线表明,相对于向下延拓快速傅里叶变换（FFT）法和积分迭代法,向下延拓Milne法的深度更大,相对误差更小;相对模型值,向下延拓Milne法能够获得稳定且准确的结果.对加拿大乃查科（Nechako）盆地地区实测航空重力数据进行本文方法向下延拓验证,处理结果表明,相对于实测异常,本文方法向下延拓结果能够很好还原实测数据,并且在进一步向下延拓中反映原始异常的趋势,增强局部和细小异常信息.

     

航空重力测量厄特弗斯改正公式注记

针对当前国内外机构和学者在使用航空重力测量厄特弗斯改正公式中存在的不一致性问题,详细分析了不同时期、不同形式改正计算公式的来源及其相互关系,并比较了它们在数值上的差异,指出我国作业部门目前使用近似公式存在的误用问题和统一使用严密公式的必要性。     

An empirical formula for friction coefficient of a perforated wall with vertical slits

The friction coefficient in the permeability parameter of a perforated wall has been estimated on the basis of a best fit between measured and predicted values of such hydrodynamic coefficients as reflection and transmission coefficients. In the present study, an empirical formula for the friction coefficient is proposed in terms of known variables, i.e., the porosity and thickness of the perforated wall and the water depth. This enables direct estimation of the friction coefficient without invoking a best fit procedure. To obtain the empirical formula, hydraulic experiments are carried out, the results of which are used along with other researchers' results. The proposed formula is used to predict the reflection and transmission coefficients of various types of structures including a perforated wall. The concurrence between the experimental data and calculated results is good, verifying the appropriateness of the proposed formula. It is also shown that the proposed formula can be used for irregular waves as well.     

变降深抽水附近地下水非稳定运动的积分方程解

根据完整井变流量抽水附近地下水运动的解析解,利用积分方程的方法,推导出了水井水位降深以任意一种函数关系随时间变化时含水层中地下水非稳定运动积分方程形式的解,并提出了该积分解相应的近似计算方法.最后通过一个实例验证了该方法的实用性.     

随机载荷下的疲劳损伤计算公式

本文推导了随机载荷下的疲劳损伤计算公式。数值计算结果表明：Ｐ．Ｈ．Ｗｉｒｓｃｈｉｎｇ给出的公式在宽带情况下与实际情况不符；Ｇ．Ｃｈａｕｄｈｕｒｙ给出的公式在窄带情况下与实际不符；本文绘出的公式不仅适合于窄带，也适合于具有各种不同带宽的宽带随机载荷。     

半圆型结构冰压力的物理模拟试验研究

利用DUT-1非冻结合成模型冰开展1:25冰对半圆型构件的物理模拟试验研究. 首先用简单的斜面构件的物理模拟试验检验了整体试验装置和技术设备的可靠性, 然后以同样比尺进行2种冰厚在5个不同水位条件的系列试验, 获得了模型冰排在半圆型构件前的破碎堆积现象和作用于构件上的水平和垂直作用力过程.结合实测模型冰物理和力学指标, 通过优化组合, 拟合出半圆型防波堤冰荷载的试验公式. 这些公式包含了冰对半圆型结构的弯曲破坏作用力、挤压破坏作用力及爬坡和堆积作用力.