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31.
32.
It has been known that the axisymmetric Cauchy–Poisson problem for dispersive water waves is well posed in the sense of stability. Thereby time evolution solutions of wave propagation depend continuously on initial conditions. However, in this paper, it is demonstrated that the axisymmetric Cauchy–Poisson problem is ill posed in the sense of stability for a certain class of initial conditions, so that the propagating solutions do not depend continuously on the initial conditions. In order to overcome the difficulty of the discontinuity, Landweber–Fridman's regularization, famous and well known in applied mathematics, are introduced and investigated to learn whether it is applicable to the present axisymmetric wave propagation problem. From the numerical experiments, it is shown that stable and accurate solutions are realized by the regularization, so that it can be applicable to the determination of the ill-posed Cauchy–Poisson problem. 相似文献
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34.
A one-dimentional three-layer model for the thermal structure in the Huanghai Sea is presented in this study, me model consists of the upper mixed layer caused by heating and wind mixing, the lower mixed layer driven by tidal mixing, and the thermocline with certain thickness. The entrainment velocities of the upper and lower layers are obtained respectively. The results show that the model is capable of describing the development and decline processes of the seasonal thermocline in the Huanghai Sea, simulating successfully the Huanghai Sea Cold Water Mass, the nearshore front and surface cold water off North Jiangsu and explaining reasonably their formation mechanisms as well as the strong thermocline off Qingdao. It is suggested that the tidal mixing plays key role in the formation of the nearshore front off North Jiangsu and the strong thermocline off Qingdao. The wind mixing and the tidal mixing make the lower layer water with high nutrients go up to the upper layer. This physical process may be sig 相似文献
35.
Based on the recent research results on dry and wet deposition of nutrient elements and sulphate,we estimate the atmospheric flux of nutrient elements and sulphate to the southern Yellow Sea and the East China Sea in each season.The results suggest that the concentrations of nutrient elements and sulphate in aerosol and precipitation show an apparent seasonal cycle with the maximum values in winter and the minimum values in summer.Depositions of nitrate and sulphate are dominated by wet deposition,while the deposition for phosphate is mainly dry deposition.Moreover,compared with the riverine inputs,the atmospheric deposition may be the main source of dissolved inorganic nutrients in the southern Yellow Sea and the East China Sea. 相似文献
36.
Song H. Kuperman W.A. Hodgkiss W.S. Gerstoft P. Jea Soo Kim 《Oceanic Engineering, IEEE Journal of》2003,28(2):250-261
Adaptive-array beamforming achieves high resolution and sidelobe suppression by producing sharp s in the adaptive beampattern. Large-aperture sonar arrays with many elements have small resolution cells; interferers may move through many resolution cells in the time required for accumulating a full-rank sample covariance matrix. This leads to "snapshot-deficient" processing. In this paper, the -broadening technique originally developed for an ideal stationary problem is extended to the snapshot-deficient problem combined with white-noise constraint (WNC) adaptive processing. Null broadening allows the strong interferers to move through resolution cells and increases the number of degrees of freedom, thereby improving the detection of weak stationary signals. 相似文献
37.
平台在海上受风、浪、流、冰等水平载荷作用产生倾斜 ,而土壤粘接力、摩擦力和土抗力是平台的抗拔和抗倾力 ,桶基平台应满足抗拔、抗倾稳定的要求 ,以保证平台的整体稳定性。讨论了桶基平台受水平力作用时 ,桶形基础的破坏模式及其计算方法 ,阐述了抗倾稳定计算方法 相似文献
38.
为研究大尺度海洋环流和一些大尺度海洋物理过程,我们建立了一个无海底地形的三层斜压海洋环流数值模式。模式方程采用了静力近似和Boussinesq近似,在上边界采用了钢盖近似。同时,还做了两个数值试验:第一个模拟试验,海洋从静止状态开始,以4个季节的气候平均风应力和海表大气季节平均温度为强迫条件,积分区城选择45℃以北的太平洋,数值积分了5个模式年,这时海洋的上层环流和温度的年变化趋于平稳。计算结果再现了太平洋气候平均状态的海温分布和主要海流的大尺度特征以及它们的年变化特征。如西部强化流、赤道潜流等。第二个数值试验,在第一个数值模拟的基础上给定赤道西太平洋一个风应力异常区,数值积分了几个月。从计算结果中可看到类似E1 Ni■o的现象,并且初步地分析了赤道波动在E1 Ni■o形成过程中的作用。 相似文献
39.
40.
N. P. Romanov A. S. Drofa N. S. Kim A. V. Savchenko G. F. Yaskevich 《Izvestiya Atmospheric and Oceanic Physics》2006,42(1):74-83
From analysis of the relationships between the equilibrium state of condensation nuclei and the relative humidity, a conclusion
is made concerning the preferred use of poorly soluble substances for the generation of artificial condensation nuclei (ACN)
designed for modification of warm clouds and fogs with the purpose of their dissipation and precipitation formation. The advantage
of poorly soluble substances over commonly used soluble salts is that the finely dispersed part of the spectrum of the poorly
soluble ACN does not deliquesce and so is not involved in the formation of cloud droplets. For experimental testing of the
conclusions, preference was given to cement, whose main soluble substance is calcium oxide with a solubility of about 1 g/l.
The spectrum of dispersed cement particles was measured and compared with the spectra of pyrotechnic flares widely used for
modification at present. The process of formation of the cloud droplet spectra was simulated in the aerosol chamber of the
Institute of Experimental Meteorology by decreasing the preliminarily generated excess pressure. It was found in these experiments
that, compared to the spectra of particles formed on background condensation nuclei, the introduction of dispersed cement
leads to the broadening of spectra and to a decrease in the concentration of droplets. Even at the early stage of condensation,
droplets with radii of ∼20 μm appear. In this case, no “overseeding” phenomenon is observed, which, for soluble substances,
manifests itself in an increase in the concentration of cloud droplets with a large ACN concentration. These effects indicate
that, according to the existing concepts about the mechanism of warm-cloud modification with hygroscopic substances, the introduction
of poorly soluble ACN (in particular, dispersed cement) below the base of cumulus clouds should stimulate coagulation processes
and accelerate rain-formation processes. Considerations are given that the introduction of poorly soluble ACN into the already
existing cumulus or stratocumulus clouds or fogs should also result in the acceleration of precipitation-formation processes
or cloud dispersal. Comparison of cement powder with the well-known means of warm-cloud and fog modification is carried out.
Original Russian Text ? N.P. Romanov, A.S. Drofa, N.S. Kim, A.V. Savchenko, G.F. Yaskevich, 2006, published in Izvestiya AN.
Fizika Atmosfery i Okeana, 2006, Vol. 42, No. 1, pp. 80–91. 相似文献