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Regeneration of sand waves after dredging 总被引:2,自引:0,他引:2
Sand waves are large bed waves on the seabed, being a few metres high and lying hundreds of metres apart. In some cases, these sand waves occur in navigation channels. If these sand waves reduce the water depth to an unacceptable level and hinder navigation, they need to be dredged. It has been observed in the Bisanseto Channel in Japan that the sand waves tend to regain their shape after dredging. In this paper, we address modelling of this regeneration of sand waves, aiming to predict this process. For this purpose, we combine a very simple, yet effective, amplitude-evolution model based on the Landau equation, with measurements in the Bisanseto Channel. The model parameters are tuned to the measured data using a genetic algorithm, a stochastic optimization routine. The results are good. The tuned model accurately reproduces the measured growth of the sand waves. The differences between the measured weave heights and the model results are smaller than the measurement noise. Furthermore, the resulting parameters are surprisingly consistent, given the large variations in the sediment characteristics, the water depth and the flow field. This approach was tested on its predictive capacity using a synthetic test case. The model was tuned based on constructed predredging data and the amplitude evolution as measured for over 2 years. After tuning, the predictions were accurate for about 10 years. Thus, it is shown that the approach could be a useful tool in the optimization of dredging strategies in case of dredging of sand waves. 相似文献
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Somenath Chakrabarty 《Astrophysics and Space Science》2007,310(3-4):195-199
It is shown that in strongly magnetized neutron stars, there exist upper limits of magnetic field strength, beyond which the
self energies for both neutron and proton components of neutron star matter become complex in nature. As a consequence they
decay within the strong interaction time scale. However, in the ultra-strong magnetic field case, when the zeroth Landau level
is only occupied by protons, the system again becomes stable against strong decay.
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利用多重尺度摄动法,对低纬大气Kelvin波和Rossby波的波包演变进行了分析,得到两波的非线性相互作用方程为耦合的非线性复系数Landau方程组。数值计算表明两波相遇将使波振幅变化,波宽变窄;两波非线性相互作用可能是低纬强烈天气突然爆发的原因之一。 相似文献
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The α–β transition in quartz is investigated by molecular dynamics simulations in the constant stress ensemble. Based on a frequently used two-body interaction potential for silica, it is found that anomalies in the elastic constants are at least in semiquantitative agreement with experiment despite the fact that no anomaly in the c/a ratio is observed in the simulations. A finite-size scaling analysis shows that first-order Landau theory is applicable to the employed model potential surface. This statement also applies to the susceptibility below the transition temperature T tr, which has not yet been measured experimentally. Examination of the local order near T tr reveals that the deformation of SiO4 tetrahedral units is equally large in the β phase as in the α phase. However, large hysteresis effects can be observed in the local structure for distances r > 4 Å. The results are in agreement with the picture of a first-order displacive phase transformation which is driven by the motion of deformed tetrahedral SiO4 units. Yet, the fast oscillations of oxygen atoms are around (time-dependent) positions that do not correspond to the ideal oxygen positions in β-quartz. The averaged configurations resemble the ideal structure only if averaged over at least a few nanoseconds. 相似文献
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Somenath Chakrabarty 《Journal of Astrophysics and Astronomy》1995,16(3-4):399-405
The effect of intense magnetic field on the cosmic quark-hadron phase transition and also on the baryon number inhomogeneity
has been investigated using phenomenological MIT bag model for the quark sector. For the sake of simplicity an ideal gas equation
of state has been considered for the hadronic phase. 相似文献
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兰道班江铁矿成矿地质特征及矿床成因 总被引:2,自引:0,他引:2
通过对马来西亚吉兰丹州兰道班江铁矿地质特征的研究,认为成矿热液来源于中酸性花岗闪长岩体,地层为碳酸盐类,二者发生接触交代作用形成矽卡岩型铁及多金属矿床。 相似文献
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