An estimation of discharge using mean velocity derived through Chiu’s velocity equation   总被引：1，自引：1，他引：0  

Tai Ho Choo  Hyeon Cheol Yoon  Sang Jin Lee 《Environmental Earth Sciences》2013,69(1):247-256

To estimate discharge through the year (dry season and flood season), a stage–discharge curve derived through monitoring discharge in about 20 rivers or channels every year has been generally used. As revealed in many studies, however, the stage–discharge curve is inevitably affected by their hydraulic characteristics. This suggests that the use of a stage–discharge curve derived without considering hydraulic characteristics unique to a river or channel may produce significant errors in estimating discharge at not only low stage (during dry seasons) but also high stage (during flood seasons). In this study, the authors proposed a method to calculate the mean velocity and to estimate the discharge considering the hydraulic characteristics of a river or channel (e.g. the bed slope, wetted perimeter, width, kinematic viscosity, etc.); the method was developed using Chiu’s velocity equation. With the proposed method, it is possible to calculate a maximum velocity that is difficult to measure in an open channel, derive an entropy function representing the equilibrium of the channel, and thereby, estimate reliable discharge even in a flood season. To comparatively verify the utility of the proposed method, relations between the results of analysis using Manning’s and Chezy’s mean velocity equations and the values of measured discharge were addressed together. The results of analysis using lab data sets and measured data sets revealed that the proposed method was significantly more accurate in estimating discharge, even in flood seasons, when compared with the conventional method.  相似文献   

An alternative depth-integrated formulation for granular avalanches over temporally varying topography with small curvature     

Yih-Chin Tai  Chih-Yu Kuo  Wai-How Hui 《地球物理与天体物理流体动力学》2013,107(6):596-629

An alternative formulation is proposed for deriving depth-integrated equations for gravity-driven granular avalanches over a non-trivial topography with small curvature. The coordinate system of Bouchut and Westdickenberg (2004 Bouchut, F and Westdickenberg, M. 2004. Gravity driven shallow water models for arbitrary topography. Commun. Math. Sci., 2: 359–389. [Crossref] , [Google Scholar]) is combined with the unified coordinate (UC) method, so that it can evolve in accordance with the entrainment–deposition processes at the basal surface. The resultant mass and momentum equations are formulated as a conservation system of the Cartesian components of the conservative physical variables. The motion of the flows is driven by the basal topography-induced pressure, pressure gradient, and resisted by the basal friction. The best benefit of this formulation is that it greatly simplifies the computation of the varying coordinate orientations. The features and advantages of this formulation are illustrated by the sliding-mass examples where we simulate the motion of a finite mass of granular material sliding down an inclined chute, running through a transition zone, and being deposited onto a horizontal plane.  相似文献   

水泥土搅拌桩在垃圾填埋场地基处理中的应用     

刘刚  台运好  华伟 《岩土工程技术》2012,26(2):106-108,F0003

水泥土搅拌桩作为加固软土地基的一种成熟方法,适用于多种成因的饱和软粘土与粉土等地基。通过工程实例,介绍了水泥土搅拌桩在用于垃圾填埋场复合地基中,提高地基承载力与减少地基沉降量,保证垃圾堆体及地基整体稳定的作用,供类似工程参考。  相似文献   

High-pressure and high-temperature Raman spectroscopic study of hydrous wadsleyite (β-Mg2SiO4)     

Xiaozhi Yang  Leonid Dubrovinsky  M. A. G. M. Manthilake  Qingguo Wei 《Physics and Chemistry of Minerals》2012,39(1):57-64

In situ Raman spectra of hydrous wadsleyite (β-Mg₂SiO₄) with ~1.5 wt% H₂O, synthesized at 18 GPa and 1,400°C, have been measured in an externally heated diamond anvil cell up to 15.5 GPa and 673 K. With increasing pressure (at room temperature), the three most intense bands at ~549, 720 and 917 cm⁻¹ shift continuously to higher frequencies, while with increasing temperature at 14.5 GPa, these bands generally shift to lower frequencies. The temperature-induced frequency shifts at 14.5 GPa are significantly different from those at ambient pressure. Moreover, two new bands at ~714 and ~550 cm⁻¹ become progressively significant above 333 and 553 K, respectively, and disappear upon cooling to room temperature. No corresponding Raman modes of these two new bands were reported for wadsleyite at ambient conditions, and they are thus probably related to thermally activated processes (vibration modes) at high-pressure and temperature conditions.  相似文献   

Acclimation-dependent expression of heat shock protein 70 in Pacific abalone (Haliotis discus hannai Ino) and its acute response to thermal exposure     

李加琦  何庆国  孙辉  刘晓 《中国海洋湖沼学报》2012,30(1):146-151

Heat shock protein 70 (Hsp70) is one important member of heat shock protein (Hsp) family that is responsible for various stresses, especially thermal stress. Here we examined the response of Hsp70 gene to both chronic and acute thermal exposure in Pacific abalone (Haliotis discus hannai Ino). For the chronic exposure, abalones were maintained at 8, 12, 20, and 30°C for four months and their mRNA levels were measured. The highest mRNA level of Hsp70 gene relative to actin gene was detected in the 30°C-acclimated group, followed by the 8°C-acclimated group and then the 12°C- and 20°C-acclimated groups. After the long-term acclimation, gills from each of the above acclimation groups were dissected and exposed to different temperatures between 8°C and 38°C for 30 min. Hsp70 expression in gills acclimated to different temperatures responded differentially to the same temperature exposure. The incubation temperature that induced maximum Hsp70 mRNA expression was higher in the higher temperature acclimation groups than lower temperature groups. Pacific abalones could alter the expression pattern of Hsp70 gene according to environmental thermal conditions, through which they deal with the stress of thermal variations.  相似文献   

Correlating mass physical properties with ALOS reflectance spectra for intertidal sediments from the Ba Lat Estuary (northern Vietnam): an exploratory laboratory study     

Nguyen Thi Ngoc  Katsuaki Koike  Nguyen Tai Tue 《Geo-Marine Letters》2013,33(4):273-284

Characterization of the sediment composition of tidal flats and monitoring of their spatiotemporal changes has become an important part of the sustainable management of coastal environments. To accurately classify sediments through remote sensing, a comprehensive understanding of sediment reflectance spectra is indispensable. The present laboratory-based study explores the performance of the high spatial resolution (10?×?10 m) Advanced Land Observing Satellite (ALOS) launched in 2006. Relationships between reflectance spectra (bands 1 to 4) and four typical mass physical properties were investigated under wet and dry experimental conditions for intertidal sediments sampled near the Ba Lat Estuary in northern Vietnam. Reflectance in the near-infrared region corresponding to ALOS band 4 (0.76–0.89 μm) was found (1) to have a strong negative correlation with sand content (dry wt%) under both wet and dry conditions (linear correlation coefficient r?=?–0.7859 and –0.8094, respectively), (2) to increase with decreasing relative water content (%) in a given sediment type (r?=?–0.7748 to –0.9367 for mud, sandy mud, muddy sand, and sand), (3) to have a positive correlation with organic matter content (r?=?0.7610 and 0.6460 under wet and dry conditions for contents >0.20 dry wt%), and (4) to be insignificantly correlated with mineral composition assessed in terms of contents (wt%) of quartz, clay minerals, and mica group minerals. Positive relationships between reflectance and water content for the pooled data of all sediment types (r?=?0.6395) or organic matter content contrast with previous findings, and can be attributed to close interrelationships between these properties and the predominance of sand content as controlling factor of reflectance. This study clarifies that ALOS band 4 provides the most useful imagery for intertidal monitoring because its reflectance, as simulated using the laboratory data, shows the strongest correlation with sand content. In a next step, these experimental findings should be verified by identifying the reflectance relationships at satellite image scales, and also considering the effects of other tidal flat features on reflectance, such as microtopography and biological surface characteristics.  相似文献   

喀斯特生态环境敏感性评价指标分级方法研究——以都匀市土地利用类型为例   总被引：4，自引：2，他引：2  

李荣彪  洪汉烈  强泰  杨广斌  安裕伦  李阳兵 《中国岩溶》2009,28(1):87-93

应用数学、统计学等方法建立"比较矩阵"分析模型,对喀斯特地区生态环境敏感性评价指标的分级方法进行研究.与此同时,以都匀市土地利用类型为例,从生物多样性、系统承载力、环境容量、气候调节、物质循环与能量流动、水土保持与流失、环境污染、土地退化等11个指标来对13种土地利用类型分别做比较分析与敏感性量化,然后进行敏感性排序和有序聚类分级,并借助GIS软件绘成都匀市土地利用类型生态敏感等级分布图.研究结果认为,Ⅰ级敏感的土地利用类型包括灌木林地、有林地,Ⅰ级敏感包括天然草地、稻田、园地、水域,Ⅲ级敏感包括旱地、陵墓地,Ⅳ级敏感包括城镇、公路、农村居民点,Ⅴ级敏感包括独立工矿用地、未利用地.   相似文献   

三峡库区第三期地质灾害治理项目即将启动     

董泰 《国际地震动态》2005,(4):47-47

经我国13位地质专家分析确定的长江三峡库区195m处前缘高程、156m水位线以下的地质灾害治理项目即将启动。这批地质灾害治理项目是三峡库区地质灾害治理的第3期,总投资达65亿元人民币,主要是为了确保库区地质灾害不影响三峡工程如期蓄水至156m,保护移民安全,避免蓄水后水下工程难以施工或增大投资。  相似文献   

用于结构计算仿真的神经网络样本点选择方法研究     

费庆国  张令弥  王彤 《地震工程与工程振动》2005,25(1):21-25

本文对影响结构计算仿真神经网络精度的训练样本选择方法进行了分析。以卫星天线模型(ANTENNA)和飞机模型(GARTEUR)为对象,以样本数量和网络模型的均方误差为指标,对多种样本选择方法进行了比较。结果表明,均匀设计方法可以用较少的训练样本,保证神经网络模型较高的精度,是结构计算仿真中神经网络训练样本的最优选取方法。  相似文献   

上海抗震能力Ⅶ度,重要建筑都装有强震记录仪器     

董泰 《国际地震动态》2005,(4):47-47

经我国13位地质专家分析确定的长江三峡库区195m处前缘高程、156m水位线以下的地质灾害治理项目即将启动。这批地质灾害治理项目是三峡库区地质灾害治理的第3期,总投资达65亿元人民币,主要是为了确保库区地质灾害不影响三峡工程如期蓄水至156m,保护移民安全,避免蓄水后水下工程难以施工或增大投资。  相似文献