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1.
为了定量地预测规划河道特别是规划河堰附近的河床冲淤情况,做好拦河堰与河道的规划工作,建立了一个能考虑各泥沙粒径组的级配、流线曲率与流路曲率的差异以及能同时对推移质与悬移质泥沙进行计算的正交曲线坐标系准三维全沙数学模型.用正规划重建倒伏式拦河堰的某河的现有河道实测资料对该模型进行了验证.验证结果表明,冲淤计算结果与实测结果基本一致.以该河规划重建的倒伏式拦河堰为讨论对象,取其上下游一定的规划河道区间为计算河段,对设计洪水时的冲淤情况进行了模拟预测.预测结果表明:该模型的水位计算结果与一维非均匀流模型的计算结果基本一致并更符合河道的地形特征,河道冲淤趋势符合河道及水流的特征;规划堰上下游附近的河床冲刷量最大为3.0 m,整个计算河段的冲淤量也在-3.0~3.0 m范围内.可见,规划河道具有较好的稳定性,规划堰的选址是比较合适的.  相似文献   

2.
GIS在海岸工程规划设计中的应用   总被引:6,自引:1,他引:5  
分析了海岸工程规划中传统的水下地形冲淤计算方法的不足,介绍了地理信息系统(GIS)的基本组成及其在不下地形冲淤计算中的应用实例。在浙江舟山渔港港域地形冲淤变化分析中,利用GIS工具软件ARC/INFO分别建立了该水域1962年、1987年和1996年三个不同时期的数字高程模型(DEM),计算了1962 ̄1987年和1987 ̄1996年两个时段的冲淤深度与相应的冲淤面积产冲淤量,为建港环境条件分析提  相似文献   

3.
统计相关水深遥感模式的建立   总被引:6,自引:1,他引:5  
利用卫星遥感图像影像光谱值和实际水深的同步资料进行统计相关分析,建立初步的水深遥感模式,应用于水下地形的反演,使用幂函数形式的非线性修正项对初步模式进行修正,弥补用局部样本点的回归方程代替整体时局部水域产生的水深数值偏差的不足,得到应用于整个研究水域的水深遥感模式,使遥感水深值的平均相对误差从修正前的37%下降到修正后的17%,精度明显提高。  相似文献   

4.
利用海浪波峰和波谷位置的遥感影像信息差异,可以基于快速傅里叶变换(FFT)方法反演波长,进而反演近岸水深.本文采用理想波面数据和数值模拟波面数据代替遥感资料进行仿真研究,讨论资料分辨率和子图长度对海浪波长及水深反演的影响.研究结果表明:低分辨率资料反演波长和水深的效果差,但是当资料分辨率达到一定要求时,再提高资料分辨率对波长和水深反演结果没有影响.当波长不存在空间变化时,子图越大,波长反演误差越小.在非均匀变化的地形上,子图长度为4~8倍波长、并且小于或等于地形变化尺度时,波长和水深反演误差小,子图太大或太小时,波长和水深反演误差都增大.  相似文献   

5.
河道数字地形信息系统与长江镇扬河段GIS研制   总被引:8,自引:1,他引:7  
采用GIS及系统集成技术,使长江镇扬河段GIS实现了河道地形测量制图自动化,地形信息时空管理与三维地形表达和任意时期,任意空间的可道冲淤分析,形成了专业处理与分析的河道地形信息系统,解决了长期困水利部门河道地形信息管理与地形分析手段落后的难题,在此研究基础上,提出了河道数字地形信息系统新概念,目的是推进河床演变,河道整治等应用数字技术研究。  相似文献   

6.
论三峡水库下游的河床冲淤变化   总被引:10,自引:0,他引:10  
回顾和分析了三峡建库前后坝下游汉口以上河段的冲淤情况,通过分析丹江口、三门峡等水库下游实测资料表明,在水库下游河床冲刷、沙量恢复过程中,各粒径组输沙量均不会超出建库前水平,这是与河床边界、河型等因素无关的一般性规律,目前三峡水库下游冲淤计算成果与其他水库下游的冲淤规律存在矛盾之处,汉口以上河段冲淤情况以及对防洪的影响值得商榷。  相似文献   

7.
河口推移质水道冲淤计算公式   总被引:1,自引:0,他引:1       下载免费PDF全文
在珠江三角洲横门出海水道的整治工程研究中,引进了一种计算以推移质造床为主的水道冲刷深度的方法,针对推移质造床的水流、泥沙特点,将推移质看作接近床面运动的浓度较高的悬移质来处理,并引进一综合参数来校正将推移质作为悬移质近似处理时造成的与实际情况的差异,通过物理模型实验的实测值得率定该参数。研究结果表明,该计算方法较好地反映了推移质引起的冲淤情况,较为准确地计算和模拟了推移质河床的冲淤数量与冲淤过程。  相似文献   

8.
基于MIKE21 Flow Model建立双龙河口潮流、泥沙输运及河床演变数学模型,采用实测资料对数学模型进行了验证.通过对不同冲刷方式、开闸流量以及闸门调控过程的调度方案的模拟计算,研究闸门调度方案对闸下河道冲刷效果的影响,分析河道冲淤分布、河道冲刷总量和冲刷效率变化规律.研究结果表明:河道的冲刷总量与开闸流量成正相关,但受河道地形的控导作用,河道各段冲淤分布不均.采用大流量径流冲淤时,连续开闸方式可使河道冲刷效率更高;但采用小流量径流冲淤或纳潮冲淤时,非连续开闸方式可显著提高河道冲刷效率.  相似文献   

9.
提出以河床表面分形维数从整体上量化河床形态,并依据表面积—尺度法原理,在对现有面分维计算方法的表面积估算、边界处理及无标度区判断等方面进行改进的基础上,给出了适用于具有不规则边界的表面分形维数计算方法,该方法对河床表面分维计算具有较好的适用性.将典型河段的年内冲淤变化、局部河势、河型与河床表面分形维数变化结合起来,说明了河床表面形态具有一定的分形特征,河床表面分形维数可随着河床的冲淤变化而改变,河床形态冲淤起伏愈剧烈,则河床表面分形维数愈大,其能定量反映河床形态的复杂程度,可用于河势量化分析、河型判别以及河道形态阻力计算等相关问题研究.  相似文献   

10.
王献朝  邱华强  许岩 《科技信息》2012,(7):131-131,110
本文对用矩形、抛物线型、三角形、梯形、天然河道五种类型河床包括宽浅、窄深式分别计算水力半径的精算值和三种简算值及相对误差数分别计算,分析得出不同类型河床糙率的误差及应采用的方法。水文站断面形状各异,计算糙率时水力半径最好采用精算法,宽浅式断面可用平均水深代替水力半径;窄深式用断面面积除以水面宽加平均水深计算R值,当平均水深小于5米时采用平均水深代替水力半径,其误差小于5%,计算糙率误差小于3.2%。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

14.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

15.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

16.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

17.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

20.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

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