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1.
In the surface wind drift layer with constant momentum flux, two sets of the consistent surface eleva- tion expressions with breaking and occurrence conditions for breaking are deduced from the first in- tegrals of the energy and vortex variations and the kinetic and mathematic breaking criterions, then the expression of the surface elevation with wave breaking is established by using the Heaviside function. On the basis of the form of the sea surface elevation with wave breaking and the understanding of small slope sea waves, a triple composite function of real sea waves is presented including the func- tions for the breaking, weak-nonlinear and basic waves. The expression of the triple composite func- tion and the normal distribution of basic waves are the expected theoretical model for surface elevation statistics. 相似文献
2.
Song和Banner（2002,简称SB02）利用二维数值波浪水槽（Drimer和Agnon开发,并被Segre改进,简称DAS）研究了深水及中等水深下波群破碎,并依据波群内部能量调制和演变特性提出一个新的波浪破碎阈值.本文利用两个DAS改进模型对SB02的波浪破碎结果进行检验和比较,并研究底面斜坡坡度对SB02破碎判据的影响,其中第一个改进模型（简称MDAS1）修正了DAS中某些积分的计算错误,第二个改进模型（简称MDAS2）在自由表面上用三阶元取代原来的线性元.研究表明： MDAS1和DAS的结果非常一致;而MDAS2和MDAS1相比,波浪临界破碎时的造波板振幅、破碎时刻和局部能量极大值的最大平均变化率δmax都会发生变化,但MDAS2仍然符合SB02提出的破碎阈值.由MDAS1模拟中等水深下波群在坡度为1∶500、1∶300、1∶150和1∶100斜坡上的破碎结果表明：随着斜坡变陡,波群的局部能量极大值μ增大,δmax在临界非破碎情况下微弱变小,在临界破碎情况下急剧增大,SB02提出的破碎阈值在中等水深下坡度小于1∶100的斜坡上仍然有效. 相似文献
3.
一种被众多学者承认的论点是：孕震结构是彼此间即相互牵连又有共同成因的断裂构成的。我们知道，前震的地震活动征兆明显增加表明破裂的速率应遵从一种幂律关系。幂律关系的物理内涵是──大破裂是众多小破裂（看作众多子系统）之间的一种相互作用的结果（又称多体互作用）。深入讨论这种互作用是本文的核心。 相似文献
4.
地震强度分布不均匀性的摩擦时间依从CA模型 总被引：2，自引：1，他引：2
设计一个摩擦时间依从的地震活动性细胞自动机模型（CA），研究产生地震累积频度-震级关系曲线中，出现拐点的地震强度分布不均匀现象的物理原因。外界通过应力加载向模型输入能量，模型的细胞之间存在非线性的相互作用。对比分析规定单个细胞破裂与模型地震之间不同的决定规则时产生的地震序列的累积频度-震级关系，研究结果表明，地震的级联破裂方式是引起累积频度-震级关系在震级较低范围和震级较高范围之间不连续的因素之一。 相似文献
5.
本文将地震现象与材料的静力破坏特点、疲劳破坏特点相比较,确认产生地震的岩石断裂和错动属于疲劳破坏。根据作者70年代末研究受压容器、化工机械疲劳破坏规律的成果,将地球作为一个球形薄壁容器进行了认真计算,结果表明:地球无论在自转离心力的作用下,还是在太阳系内任一天体的万有引力作用下,35°N地带的疲劳破坏均最严重。从而揭示了35°N地带地震活动性高的原因。 相似文献
6.
孔隙性砂岩中变形带对揭示其相关地质作用过程和工程应用具有重要的意义,而其微观结构是其相关科学与工程研究的关键点。常规的岩石微观结构分析手段对于全面解析岩石内部的微观结构具有一定的局限性,而近年发展起来的三维X射线显微成像技术可以无损地获得岩石内部微米尺度的三维精细数字化图像,是建立岩石微观结构并对其进行解析的有效手段。通过三维X射线显微镜对孔隙性砂岩中变形带扫面,建立了高分辨率三维微观结构图像,利用高密度切片图像,对其微观结构特征进行解析。根据变形带微观产出状带和颗粒破碎过程的解析,建立颗粒破碎-破碎颗粒与残余破碎颗粒重新排列-局部颗粒破碎带-弱颗粒破碎变形带-强颗粒破碎变形带-强弱颗粒破碎变形带相间排列-簇状变形带的完整时间发育序列。 相似文献
7.
Statistics of breaking waves and its applications to estimation of air-sea fluxes (Ⅰ)——Theoretical models 总被引：1，自引：0，他引：1
ZHANG Shuwen & YUAN YeliKey Laboratory of Marine Science Numerical Modeling First Institute of Oceanography State Oceanic Administration Qingdao ChinaCorrespondence should be addressed to Zhang Shuwen 《中国科学D辑(英文版)》2004,(1)
Wave breaking statistics, such as the whitecap coverage and average volume of broken seawater, are evaluated in terms of wave parameters by use of wave breaking model (Yuan et al., 1988) taking the fifth order Stokes's wave as the analog of the original wave field. Based on the observed fact that breaking waves play an important role in the exchange of mass, momentum and energy between the atmosphere and the ocean, the influence of wave breaking on air-sea fluxes of heat and moisture is investigated. Theoretical expressions of bubble-volume flux and sea spray spectrum at the sea surface and models for bubble-induced and spray droplet-induced heat and moisture fluxes are established. This work can be taken as the basis for further understanding the mechanism of air-sea coupling and parameterization models. 相似文献
8.
Wave breaking statistics, such as the whitecap coverage and average volume of broken seawater, are evaluated in terms of wave parameters by use of wave breaking model (Yuan et al., 1988) taking the fifth order Stokes's wave as the analog of the original wave field. Based on the observed fact that breaking waves play an important role in the exchange of mass, momentum and energy between the atmosphere and the ocean, the influence of wave breaking on air-sea fluxes of heat and moisture is investigated. Theoretical expressions of bubble-volume flux and sea spray spectrum at the sea surface and models for bubble-induced and spray droplet-induced heat and moisture fluxes are established. This work can be taken as the basis for further understanding the mechanism of air-sea coupling and parameterization models. 相似文献
9.
Wave breaking statistics, such as the whitecap coverage and average volume of broken seawater, are evaluated in terms of wave
parameters by use of wave breaking model (Yuan et al., 1988) taking the fifth order Stokes’s wave as the analog of the original
wave field. Based on the observed fact that breaking waves play an important role in the exchange of mass, momentum and energy
between the atmosphere and the ocean, the influence of wave breaking on air-sea fluxes of heat and moisture is investigated.
Theoretical expressions of bubble-volume flux and sea spray spectrum at the sea surface and models for bubble-induced and
spray droplet-induced heat and moisture fluxes are established. This work can be taken as the basis for further understanding
the mechanism of air-sea coupling and parameterization models. 相似文献
10.
极盖等离子体云块是极区电离层常见特征之一,其形成演化过程是当前重要研究课题.光电离高密度等离子体在对流输送作用下从日侧穿过极隙,通过极盖到达夜侧,已成为共识.日侧磁场重联作用下的极区对流输运过程,在舌状等离子体结构（TOI）"断裂"形成极盖等离子体云块中发挥重要作用.利用极区全域GPS/TEC观测数据,结合SuperDARN雷达实测的对流速度,对等离子体云块形成过程进行案例研究,重点分析两种TOI断裂形成等离子体云块的发生机制.研究结果显示,等离子体对流输运过程在TOI断裂形成等离子体云块过程中发挥关键性作用,对流形态或局部对流速度矢量急剧变化都可能导致TOI结构不稳定,使TOI结构断裂形成等离子体云块. 相似文献
11.
极盖等离子体云块是极区空间天气重要现象之一,其形成过程是当前重要研究课题.观测表明,日侧磁场重联对应的极区电离层高速流可能对舌状等离子体(TOI)形成"切割"作用,最终形成极盖等离子体云块.伴随磁场重联,同时存在极光粒子沉降,会引起F层等离子体密度的增大,阻碍"切割"效应.本文利用耦合极区电离层模型,模拟研究电场和软电子沉降共同作用下F层等离子体密度的演化.结果表明,在局部电离层电场大于一定数值(80 mV)的情况下,"切割"效应能有效发生.并详细分析了"切割"效应发生时等离子体各参量的演化过程,对"切割"效应的内在物理过程进行了探讨. 相似文献
12.
Richard B. Rood 《Pure and Applied Geophysics》1985,123(5):733-755
The concept of planetary wave breaking (McIntyre andPalmer, 1983; 1984) is critically reviewed. It is concluded that the wave breaking signature is not unique to any particular dynamic event in the stratosphere. Therefore, the classification of stratospheric transport events, such as wave breaking, groups fundamentally different events together. Better qualification of the wave breaking signature and a more solid theoretical basis of planetary wave breaking must be presented if the concept is to be of significant utility in describing stratospheric tracer transport. 相似文献
13.
Oliver Miler Ismail Albayrak Vladimir Nikora Matthew O’Hare 《Aquatic Sciences - Research Across Boundaries》2012,74(1):31-44
We analysed the biomechanical properties of aquatic plant stems of four common submerged river macrophyte species with bending,
tension and cyclic loading/unloading tests and related these properties to the hydraulic habitats of the plants. The studied
species included Glyceria fluitans, Ranunculus penicillatus, Myriophyllum alterniflorum and Fontinalis antipyretica. Habitat assessment shows that these species occur in a range from low to high flow velocities, respectively. G. fluitans is a semi-aquatic species with stems of a high flexural rigidity and high breaking force and breaking stress that enable
them to carry their own weight and balance gravity when growing upright in slow flowing rivers. G. fluitans may also grow horizontally often producing emerged terrestrial stems. In contrast, F. antipyretica grows in fierce water flow. Its stems have the highest flexibility, a significantly higher ‘tension’ Young’s modulus, breaking
stress and work of fracture and a lower plastic deformation compared to M. alterniflorum and R. penicillatus. These traits enable F. antipyretica to survive even in swift flowing streams and constrict the growth of M. alterniflorum and R. penicillatus to the river reaches with moderate flow velocities. R. penicillatus has a weak bottom part with a low breaking force and breaking stress acting as a predetermined breaking point and enabling
seasonal regrowth from root parts. 相似文献
14.
Vertical mixing of oil droplets by breaking waves 总被引：2，自引：0，他引：2
Oil spilled on a sea surface can be dispersed by a variety of natural processes, of which the influence of breaking waves is dominant. Breaking waves are able to split the slick into small droplets, facilitating oil mixing in the water column. Vertical dynamics of the droplets plays a major role in the oil mass exchange between the slick and the water column. In this paper a mathematical model of oil droplet mixing by breaking waves is developed. The model uses a kinetic approach to describe the vertical exchange of the droplets at the interface between the slick and the water column. The majority of the coefficients and parameters are conveniently combined into a single "mixing factor". The model is verified using sensitivity analysis and empirical formulae of other authors. The model permits a rapid estimation of the amount of dispersed oil under the breaking waves. The ultimate goal of the research is to parameterise influence of breaking waves on vertical mixing of oil droplets to be used in a general 3-D oil spill model. 相似文献
15.
Dott. Ing. Agatino D'Arrigo 《Pure and Applied Geophysics》1952,21(1):86-95
Summary After a short reference made to the utility, having regard on maritime structures, and particularly on vertical wall breakwaters, of knowledge on the centurial observations on the storm wave height and the depth of water breaking wave or breaking hydrogeological on the bottom of Mediterranean Sea, because of the subaqueous source, are here shown the correlations among the waves characteristics and the morphological configuration of the continental-shelf, of the fetch, of the winds, of the sedimentation, of the stereophotogrammetry at the stormy sea surface. It is here likewise stated the analogical parallelism between the atomical disintegration and the transformation from potential energy of the oscillatory wave till kinetic energy of breaking waves. 相似文献
16.
采用二维全隐欧拉（FICE）格式对具有高斯分布的重力波波包在可压大气中传播时的饱和过程进行数值模拟和分析．数值计算结果表明,波振幅首先随高度增加而增加,但当波振幅接近于线性不稳定性给出的阈值时,不再增加,重力波波包达到饱和进而破碎．破碎出现的高度（86．50km）比线性理论预言的结果（84．59km）要高一些,并且一般都在波包的下游出现．波破碎过程能使波能量在空间重新分配,并对重力波能量有明显的耗散作用．并且波破碎会使波相关能量传输方向偏离线性射线理论的射线路径． 相似文献
17.
18.
Testing dispersant effectiveness under conditions similar to that of the open environment is required for improvements in operational procedures and the formulation of regulatory guidelines. To this end, a novel wave tank facility was fabricated to study the dispersion of crude oil under regular non-breaking and irregular breaking wave conditions. This wave tank facility was designed for operation in a flow-through mode to simulate both wave- and current-driven hydrodynamic conditions. We report here an evaluation of the effectiveness of chemical dispersants (Corexit® EC9500A and SPC 1000™) on two crude oils (Medium South American [MESA] and Alaska North Slope [ANS]) under two different wave conditions (regular non-breaking and plunging breaking waves) in this wave tank. The dispersant effectiveness was assessed by measuring the water column oil concentration and dispersed oil droplet size distribution. In the absence of dispersants, nearly 8-19% of the test crude oils were dispersed and diluted under regular wave and breaking wave conditions. In the presence of dispersants, about 21-36% of the crude oils were dispersed and diluted under regular waves, and 42-62% under breaking waves. Consistently, physical dispersion under regular waves produced large oil droplets (volumetric mean diameter or VMD ? 300 μm), whereas chemical dispersion under breaking waves created small droplets (VMD ? 50 μm). The data can provide useful information for developing better operational guidelines for dispersant use and improved predictive models on dispersant effectiveness in the field. 相似文献
19.
上海地震台针对测震台网参评台站电源故障发生后需快速修复、避免断记这一时效性需求特点,研发的台站电源系统具备可快速有效自修复的功能。该系统中的相关电路模块在台站应用中取得了较显著的效果,减少了断记时间,提高了运行率和运行质量。 相似文献
20.
新疆南天山东段地震平静相关问题探讨 总被引：1，自引：0，他引：1
分析了南天山东段地震平静相关问题。得到如下结论：①将平静现象分为震前平静、震后平静．场兆平静、无震平静可能更能客观地反映平静状态;②南天山东段4级地震平静6个月以上具有前兆意义;③5级地震发生前的打破平静现象分为两类,由4级地震打破平静的5级地震其发震位置与4级地震关系密切,由5级地震打破平静的地震一般发生在地震弱活动区或南天山东段5级地震成组活动时期,前兆现象较难捕捉;④南天山东段5级地震最长平静时间为57个月。 相似文献