Influence of wave-current interactions on fluid force     

Chi Chao Tung  Norden E. Huang 《Ocean Engineering》1973,2(5):207-218

Influence of wave-current interactions on fluid force on a single cylinder and on two cylinders in tandem is examined. Quantities obtained are spectra of fluid force on elements, total fluid force and its statical moment. Comparisons are made of the cases in which wave-current interactions are considered and ignored. It is shown that interactions affect spectra of element force and statical moment more than do total force spectrum. For two cylinders in tandem, for cylinder spacings, current conditions and frequency range of practical interest, the effect of interactions is slightly reduced.  相似文献   

Improvement of a drainage system for flood management with assessment of the potential effects of climate change     

Hsiang-Kuan Chang  Yih-Chi Tan  Tsung-Yi Pan  Tzu-Ming Liu  Ching-Pin Tung 《水文科学杂志》2013,58(8):1581-1597

Abstract

Runoff discharge in the Tuku lowlands, Taiwan, has increased with land development. Frequent floods caused by extreme weather conditions have resulted in considerable economic and social losses in recent years. Currently, numerous infrastructures have been built in the lowland areas that are prone to inundation; the measures and solutions for flood mitigation focus mainly on engineering aspects. Public participation in the development of principles for future flood management has helped both stakeholders and engineers. An integrated drainage–inundation model, combining a drainage flow model with a two-dimensional overland-flow inundation model is used to evaluate the flood management approaches with damage loss estimation. The proposed approaches include increasing drainage capacity, using fishponds as retention ponds, constructing pumping stations, and building flood diversion culverts. To assess the effects on the drainage system of projected increase of rainfall due to climate change, for each approach simulations were performed to obtain potential inundation extent and depth in terms of damage losses. The results demonstrate the importance of assessing the impacts of climate change for implementing appropriate flood management approaches.

Editor Z.W. Kundzewicz

Citation Chang, H.-K., Tan, Y.-C., Lai, J.-S., Pan, T.-Y., Liu, T.-M., and Tung, C.-P., 2013. Improvement of a drainage system for flood management with assessment of the potential effects of climate change. Hydrological Sciences Journal, 58 (8), 1581–1597.  相似文献   

Criteria for initiation of motion of rigid bodies to base excitation     

C. C. Tung 《地震工程与结构动力学》2005,34(10):1343-1350

It is known that when an unanchored rigid body is placed on a horizontal base which oscillates horizontally, it may undergo one of four modes of motion: rest, slide, slide–rock and rock. Initiation of a rigid body into these modes depends on the slenderness ratio of the body, the coefficient of friction between the body and the base and the acceleration of the base. In this study, the coefficient of friction and the base acceleration are considered random. For specific probability distributions of the coefficient of friction and the peak base acceleration, and for various values of the mean and standard deviation of the two random variables, the probabilities of occurrence of these modes of motion are obtained for a body of given slenderness ratio. It is shown that randomness of the coefficient of friction and base peak acceleration should not be ignored. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

利用地方震出格记录尾波测定宁夏北部及邻区Q值   总被引：2，自引：0，他引：2       下载免费PDF全文

杨明芝  董卫国 《地震工程学报》1985,7(2):23-30

基于安艺的尾波理论,本文提出了一种使用单台记录的出格地震图尾波资料测定地壳上层介质Q值的新方法。利用该方法,对宁夏北部地区(38°—41.5°,104°—107°)测定了其Q值的分布。结果指出,宁夏吴忠到石咀山之间的银川地堑的Q值(100—200)明显偏低于与其接邻的内蒙阿拉善左旗和磴口一带的Q值(200—300),在个别局部区城存在Q值异常区。最后简要讨论了所得结果。  相似文献   

极大熵准则在降雨强度-历时-频率模型参数估计中的应用     

陆宝宏  陆晓明  汤有光 《水文》2002,22(1):17-19,57

根据频率与重现期的关系推导出三类常用降雨强度-历时-频率模型的无条件及条件概率分布(概率密度)函数及与模型相对应的约束。极大熵与极大似然准则产生一致估计,本文尝试基于极大熵准则建立降雨强度-历时-频率模型参数估计的优化模型,应用模拟退火算法求解该优化模型。根据比较发现,极大熵估计有时比常用的极大似然估计和最小二乘估计更精确。  相似文献   

Initiation of motion of a free‐standing body to base excitation     

C. C. Tung 《地震工程与结构动力学》2007,36(10):1431-1439

This study is concerned with the conditions for the initiation of various modes of response of a free‐standing rigid body, initially at rest, placed on a frictional horizontal base which undergoes earthquake‐like accelerations in both the horizontal and vertical directions. These conditions are derived using equations of motion appropriate for each mode of motion. The analysis shows that an equivalent horizontal base acceleration may be constructed by dividing the time history of horizontal base acceleration by the sum of gravitational acceleration and the time history of vertical base acceleration. The criteria governing each mode of response of a body of given aspect ratio are then presented graphically with the magnitude of the equivalent base acceleration as abscissa and the coefficient of friction between the body and the base as ordinate. The study shows that a body is more stable while the vertical base acceleration is upwards than when it is absent as expected. When the vertical base acceleration is downwards, although the body is very likely to be lifted off the base, it is nevertheless possible to rock, and slide and rock simultaneously provided the value of coefficient of friction is sufficiently high and the downward vertical base acceleration is not too different from gravitational acceleration. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

On estimating the earthquake-induced changes in hydrogeological properties of the Choshuishi Alluvial Fan, Taiwan     

Kuo-Chin Hsu  Chih-Chiu Tung 《Hydrogeology Journal》2005,13(3):467-480

The hydrological response of the Choshuishi alluvial fan to the 1999 Chi-Chi earthquake shows that the earthquake did impact the aquifer. The possible earthquake-induced changes in hydrogeological properties were investigated in this study. First, contour maps of the hydrologic anomaly, seismic factors, and vertical ground-surface displacement were compared qualitatively. Bulls eye patterns were found on the contour maps of hydraulic conductivity, coseismic groundwater-level change and vertical ground-surface displacement but did not occur with other seismic factors. The more permeable zones of the aquifer were found to coincide with the locations of greater vertical ground-surface displacement and coseismic groundwater-level change in the 1999 Chi-Chi earthquake. This indicates that the change of the hydrogeologic properties of Choshuishi alluvial fan due to the 1999 Chi-Chi earthquake may have mainly occurred in the highly permeable zones. Fractal, cross semivariogram and cross correlogram analyses were performed to quantitatively measure the persistency, variability and similarity, respectively, of spatial hydrologic response, seismic factors and hydraulic conductivity. The groundwater-level change, earthquake intensity, and vertical ground-surface displacement were found to show antipersistent tendencies while other factors showed the opposite. Higher correlations were found between hydraulic conductivity and groundwater-level change in aquifers 2–1 and 2–2, and between hydraulic conductivity and vertical ground-surface displacement in aquifer 3. Changes in porosities and hydraulic conductivity were evaluated in the main aquifers of the Choshuishi alluvial fan based on the data of hydrologic anomaly and the vertical ground-surface displacement. While both approaches show that the 1999 Chi-Chi earthquake has impacted the Choshuishi alluvial fan by reducing its porosity and hydraulic conductivity, these changes were not significant relative to natural variation in hydraulic conductivity.This revised version was published in May 2005 with correction to the rubric.  相似文献   

丁村旧石器遗址群的黄土地层研究   总被引：5，自引：0，他引：5       下载免费PDF全文

吴文祥  刘东生 《地震地质》2002,24(2):241-248

通过测量黄土的磁化率 ,并结合传统的黄土地层学研究方法 ,对丁村旧石器文化遗址群中两个典型的剖面 ,即代表丁村旧石器中期文化的 10 0地点和代表丁村旧石器早期文化的 79:0 2地点文化层上部的黄土 -古土壤序列进行划分 ,并将其结果与位于丁村附近黄土塬上的敬村黄土剖面和典型洛川黄土剖面的地层和磁化率曲线进行对比。结果表明 ,丁村 10 0地点地层上部黄土 -古土壤序列为S0 ,L1,S1;而 79:0 2地点上部的黄土 -古土壤序列则包括S0 ,L1,S1,L2 ,S2 。因此 ,丁村 10 0地点文化层的年代大于S1的形成年代即 0 13MaB .P .,79:0 2地点文化层的年代大于S2 的轨道调谐年龄 ,即 0 2 4 7MaB .P  相似文献   

Dating palaeo‐seismic faulting in the Taiwan Mountain Belt          下载免费PDF全文

Chih‐Tung Chen  Chieh‐Yu Wu  Ching‐Hua Lo  Hao‐Tsu Chu  Tzen‐Fu Yui 《地学学报》2018,30(2):146-151

In‐situ ⁴⁰Ar/³⁹Ar laser microprobe dating was carried out on the Hoping pseudotachylite from a mylonite‐fault zone in the metamorphosed basement complex of the active Taiwan Mountain Belt to determine the timing of the responsible earthquake(s). The dating results, distributed from 3.2 to 1.6 Ma with errors ranging from 0.2 to 1.1 Ma, were derived from a combination of two Ar isotopic system end‐members with inverse isochron ages of 1.55 ± 0.05 and 2.87 ± 0.07 Ma, respectively. Petrographical observations reveal fault melt containing ultracataclasites, therefore the older inverse isochron end‐member may be attributed to the relic wall rock Ar isotopic system contained in micro‐breccia. Without significant Ar loss expected, the ~1.6 Ma for the young end‐member defines the exact time of the pseudotachylite formation. Seismic faulting therefore occurred during basement rock exhumation in the Taiwanese hinterland.  相似文献   

Nappe structure revealed by thermal constraints in the Taiwan metamorphic belt     

Chih‐Tung Chen  Yu‐Chang Chan  Chia‐Yu Lu  Martine Simoes  Olivier Beyssac 《地学学报》2011,23(2):85-91

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