The modified hybrid element method (MHEM) is utilized to predict and analyze wave forces on arbitrarily shaped multiple bodies. This method can be applied to waves of all water depths, i. e. shallow, intermediate, and deep waters, on slowly varying seabed. The MHEM employs the ICCG method to save CPU and storage, thus the computation of wave forces for large multi-body systems can be carried out on microcomputers. Numerical results of the present method are compared with experimental data and other solutions. It is shown that the MHEM provides more accurate solutions of the wave forces than other numerical methods do. Therefore, the methodology presented herein can be used in the design of coastal and ocean structures. 相似文献
在植物组织内,类胡萝卜素除具有集光功能外,还具有其他的重要生物学功能,类胡萝卜素作为光保护剂可抵抗光、氧和光敏色素的有害作用,也可作为化学反应物抵抗细胞所产生的化学物质引起的氧化损伤,保护光合系统免受光动力敏化作用的破坏。类胡萝卜素光保护作用的主要机制如下:(1)类胡萝卜素对三重线态敏化剂的淬灭;(2)类胡萝卜素对1O2的淬灭;(3)类胡萝卜素对自由基反应的抑制,它的这种生物学活性在医学领域也具有重要的应用价值。胡萝卜素在生物系统中的保护作用包括失活由电激活的单线态氧(1O2),失活反应性的化学物质如过氧化物自由基和烷氧基,这些自由基产生于细胞内,并可能会引起有害的氧化作用。类胡萝卜素的保护功能与直接的抗氧化活性或与对细胞内抗氧化水平的调节有关(Krinsky,1990)。对于类胡萝卜素清除脂类过氧化物自由基的能力和作用机理已经进行了详细的研究(Burton et al.,1984; Burton, 1989; Terao,1989; Palozza et al.,1992b; Tsuchihashi et al.,1995),但对于类胡萝卜素清除超氧阴离子自由基的能力尚未见有详细研究报道。本文以邻苯三酚自氧化体系作为超氧自由基的发生体系,对海藻中分离纯化制备的类胡萝卜素清除该种自由基的能力进行了初步的探讨。 相似文献
-Based on the extended Morison Equation and model tests, the in-line forces on small square cylinders caused by waves (regular and irregular) and currents are analyzed in detail in this paper. The hydrodynamic coefficient CD and Cu related to KC number and the effect of direction of wave incidence are also given, which can be used in engineering practice. 相似文献
In this paper,the characteristics of density current under the action of waves are describedwith the help of flume experiment and theoretical analysis.The study shows that turbid water under the ac-tion of the waves can present three types of motion,i.e.significant stratification,fragile stratification andstrong mixing.The motion of turbid water presents significant stratification when(H/D)/△ρ/ρ~(1/2)≤4.5,generally this state is known as density current.The formulas of motionvelocity,thickness,and discharge of density current moving on horizontal bottom are derived by use of ba-sic equations such as momemtum equation,equation of energy conservation and continuity equation offluid.The time-average velocity and the thickness of density current under the action of waves have a rela-tionship with such parameters as relative density(△ρ/ρ),wave height(H),and water depth(D).Whenthese parameters are determined,the time-average thickness and motion velocity of density current are al-so determined.The relat 相似文献
At pesent,it is very popular to estimate pile bearing capacity by use of empirical formula andphysical indexes of soil provided in the design codes for civil construction in China.This paper attempts toapply mechanical indexes of soil and semi-empirical formulas,which are based on soil mechanical theoriesand were summarized and presented by Meyerhof in 1976,to calculate the axial pile bearing capacity.Lo-ading test results of 24 single piles in Tianjin area have been collected and compared with the proposed cal-ulation approach. 相似文献
This paper describes the model tests for determining the axial friction and the lateral resistance of sand to pipeline by using fine sand and prototype pipeline, and the calculation method based on limit analysis theory is verified. The effect of cyclic loading is considered in the test. 相似文献
- The shear failure of a rigid-plastic dented clamped tubular beam under the lateral impact of a mass is investigated. Both the denting and the impact point are in the middle span of the beam. It is assumed that denting does not spread during the shear sliding. Numerical results show that the axial force and lateral deflection of the beam are very small at the moment of the occurence of shear failure, which means that the finite deformation effect can be neglected in the shear failure analysis. Also, some aspects of the initial impact energy are investigated. 相似文献
Nineteen cheniers formed in the middle and late Holocene have been distinguished and studied.
In fair weather the wave action along the Yangtze Delta is weak, with a wave height of 0.5–1.0 m and average wave energy of 0.127 erg/s. However, in late summer and early autumn the coastal area is usually swept by typhoons, which sometimes are extremely violent. The development of cheniers is mainly controlled by these strong typhoons. As a result, a number of the sedimentary characteristics of the cheniers are related to the typhoon-generated high-energy environment.
Moreover, the study shows that the top elevation of a fully developed chenier indicates the spring high water level during a violent typhoon (11–12 on the Beaufort scale). 相似文献
- This paper, after briefly reviewing the experimental research on sediment transport on muddy beach since the 1950s, improves and perfects the method for forecasting siltation in navigation channels and harbour basins which was first put forward in China by the authors. In consideration of silty sediment and sand, some factors in forecasting methods have been changed and modified. Consequently, the modified methods can be used either to compute siltation in navigation channels and harbour basins on muddy beach or to compute siltation and scouring in navigation channels and harbour basins on both silty beach and sandy beach. The verification of field data from eleven large, medium and small natural harbours shows a good agreement between the forecasting by the modified method and the natural conditions. Finally, the paper deals with the rational utilization of water area after the construction of the West Dyke in Lianyungang, the maintenance of water depth of the navigation channel at the entrance, siltation distribution, siltation in the navigation channel and harbour basin for ships of 100 thousand tonnnage. Results once again prove that the prospect of constructing Lianyungang Harbour into a deepwater harbour is bright. 相似文献