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排序方式: 共有767条查询结果,搜索用时 31 毫秒
511.
通过多年生产性试验及测量对虾体长和对虾投饵量的记录,整理出不同体长每万尾对虾投饵量的计算式:Q=1/a+be~(-l)=1/0.6245+42.2379e~(-l) 相似文献
512.
An apparent wave is a part of the sea record observed between two successive upcrossings of the still water level. Integral formulas are given for intensities of encountered waves that overtake a ship sailing in directional sea with constant velocity. The formulas can be evaluated exactly in the case when the directional spectrum is known and the sea is assumed to be Gaussian, i.e. is a sum of noninteracting sinusoidal waves. 相似文献
513.
1 .Introduction The Wells turbine ,consisting of several symmetric aerofoil blades ,fixedto a hub,can rotate inthe same direction without anyrectifyingflap valves .It has been consideredto bethe most prospectivewave energy conversion deviceforits simple s… 相似文献
514.
515.
One of the major rehabilitation projects in Kuwait during the 1990s was improvement of the wastewater treatment plant at Jahra,
a town 30 km north of Kuwait City. The project incorporates construction of a pumping station to collect the sewage via a
network of sewer lines throughout the city. Groundwater occurs 4 m below the ground surface and construction specifications
required lowering the groundwater table by 16 m to the foundation grade, 20 m below the ground surface. Open excavation with
four stage well point system of dewatering was selected to ensure dry foundation conditions; but the system failed to lower
the groundwater table down to the desired depth. Review of site investigation records and recalculation of field hydraulic
conductivity resulted in design changes, augmenting the well point system with a number of deep wells and sumps to lower the
water table down to the foundation grade. The paper discusses subsurface conditions and presents an analysis of the cause
of failure of the well point system. The actual hydraulic conductivity proved to be several folds higher than the calculated
one that was determined using Hazen’s formula. It was found that use of Hazen’s formula led to serious underestimation of
field hydraulic conductivity. It is advised not to use such formulas without thorough investigation and proper interpretation
of borehole data. 相似文献
516.
城市暴雨强度公式的准确性直接影响着城市排水管网的规范设计.合肥市原有暴雨强度公式亟需重新修订。对合肥市董铺站1965~2012年共48年的全部暴雨资料进行分析,用年最大值法取样,采用皮尔逊-Ⅲ型分布,指数分布和耿贝尔分布曲线进行拟合,对频率分析后的数据分别采用了麦夸尔特法,高斯-牛顿法,遗传算法,拟牛顿法,模拟退火法,粒子群算法共6种优化算法进行公式参数推求,最终确定以指数分布配合麦夸尔特法确定的公式精度最好,公式精度大大优于合肥市原有的暴雨强度公式,所推求出的暴雨强度公式可用于洪水灾害的危险性分析、城市给水排水设计等供水灾害管理中,对合肥市的防涝、排涝、排水设施规划和工程设计具有重大意义。 相似文献
517.
518.
逐步缩小搜索范围的遗传算法 总被引:16,自引:3,他引:16
本文介绍在遗传算法的运行过程中如何逐步缩小搜索范围,使搜索速度与计算精度同时得到提高的方法。文中提出了真值邻域的概念,利用这个概念得到了缩小搜索范围的压缩公式。只要合理选择初始搜索范围(这一点并不难做到),上述压缩公式能确保问题的解始终保留在压缩后的搜索范围内。通过理论模型的检验及与原有遗传算法结果的比较,证实了方法的有效性。 相似文献
519.
花岗岩裂隙水推荐配方稳定性模拟研究 总被引:1,自引:0,他引:1
在核废物深部地质处理科学过程中,提供一种长期稳定的模拟花岗岩裂隙,用以模拟试验是非常有必要的。本文主要依照中国辐射防护研究院推荐的模拟花岗岩裂隙水修正配方,引用地球化学模式程序对其溶液的稳定性进行模拟计算,探讨配方中所存在的问题。 相似文献
520.
M. A. Khan 《Natural Hazards》1992,5(2):125-132
The distinctive nature of the structure of the Earth's gravity field over high seismicity areas, as observed in some limited scale studies, indicates that it is possible to use these associative patterns to outline areas of high seismicity or high earthquake hazard potential from a knowledge of the finer structure of the Earth's gravity field. The global scale investigation of such relationships as a function of the geophysical characteristics of various tectonic provinces, and the parameterisation of such relationships by hypocentral depth and earthquake intensity/energy data, become even more attractive because of the availability of (1) satellite-determined gravity models which provide global information on the long wavelength components of the gravity field, (2) satellite altimetry data which provide oceanwide information on the detailed geoidal structure, (3) surface gravity data which provide information on the short wavelength components in the areas of surface gravity coverage, and (4) bathymetric and topographic data which, though still somewhat limited in spite of their recent extensions of coverage, are available in more and more areas and provide information on the tectonic and morphological environments of an area to enable its gravity data conversion to some standard environments for direct comparisons of underlying structures. Additionally, the rapidly mounting geological and geophysical evidence of considerable intraplate tectonic activity, not so fashionable until recently, makes the study of these correlative patterns even more attractive and productive from a scientific viewpoint. This paper presents the major elements of the theoretical formulation for conducting such investigations. 相似文献