波传播

The basic properties of elastic wave propagation in quadratic inhomogeneous damage materials are discussed by examples.

介质中的波的传播理论在国内外已得到广泛的研究[4-6]，但以往的文献大多研究的是均匀介质或分层均匀介质中的波的传播问题[7]。

SH guided wave dispersion characteristics and wave structure for free surface isotropic elastic pipe circumferential waveguide were calculated and analyzed to guide pipeline inspection,and these characteristics were compared with those of the plate SH guided wave.

为指导基于超声导波的管道无损检测，计算并分析水平切变（shear horizontal，SH）导波在具有自由内表面、外表面的弹性各向同性管道周向波导中传播的频散和波结构特性，将这些特性与平板SH导波的对应特性进行对比分析。

Research on development methods and application of CAD system of prac tical sheet metal expansion ;2. A frame expansion method of operator is used to the phase shift operator of split-step Fourier propagator.

针对裂步Fourier传播算子在速度强横向变化介质中的不足，将算子的框架展开方法应用于Fourier传播算子中的相移算子，提出了一种波场传播的局部裂步Fourier传播算子，并把它应用于波动方程叠前深度偏移成像。

The evolution of the half-peak width of the relative density increment pulse with respect to slow wave also demonstrates the close relation to Δp. Its minimum w〓 decreases with the increase of Δp, which means, slow wave will steepen with the enhancement of Δp and may evolve into slow shock eventually. Numerical results also indicate that the propagation velocity of fast and slow wave increase when Δp increases.

对强扰动情形(Δp＝5)，通过考察相关物理量的径向分布，并借助于对物理量沿波动阵面法向分布的讨论，可以初步判断出由强扰动所造成的慢模磁声波在传播过程中逐渐陡变而演化为慢激波，慢激波在进入日冕前已在色球层中形成，并在此后的传播过程中始终保持这一性质。

The main characteristics include: the quiet Sun corona has a rapid response to the flare heating, within 2 second the corona temperature increases nearly one order of magnitude, but later such increase becomes very slowly; the downward velocity at early stage of impulsive phase is too small to be negnected; chromospheric evaporation made by conduction shows some intensely, the maximum evaporated velocity may be as large as 1000 km/s; the chromospheric condensation appears just when the chromospheric evaporation takes place and its place always coincide with that of transition region in the early stage; the maximum of chromospheric condensation occurs also in the early stage of impulsive phase, at which the density in condensation may be larger two order of magnitude than that of surround and the downward velocity may be as large as 100 km/s; after the maximum of chromospheric condensation, its strongth decreases gradually but its width becomes greater with time and have a tendency to transport into deep chromosphere; the front of chromospheric condensation heats atmosphere obviously and the temperature in the chromospheric condensation is higher than the original case; the downware velocity of transition region may be greater than 100 km/s at the early stage; when the evaporated material collide at the top of loop, the densityand the presure there increase rapidly, which result in the formation of a shock wave; and so on.

在改善色球辐射损失和精确分辨过渡区的基础上，通过联立求解连续性方程、动量方程和能量方程，构造了一维磁限制性耀斑环在热沉积作用下的大气动力学模型，获得了耀斑热模型下脉冲相早期较为细致的大气演化理论图象，其主要特征是：耀斑对宁静日冕的加热相当迅速，仅2秒钟日冕温度增加即达一个量级，之后日冕温度增加缓慢；脉冲相早期日冕向下速度很小，几乎可以忽略，热传导驱动色球蒸发，其过程较为激烈，蒸发极大速度可达到1000km/s；色球压缩区与色球蒸发几乎同时形成，且在早期其位置总是与过渡区位置重合；色球压缩极大发生在脉冲相早期，其时密度可高于周围约2个量级，向下速度可超过100km/s；色球压缩极大后，其强度逐渐减弱，但宽度明显增大，且渐渐脱离过渡区往色球传播；压缩区内物质温度要高于原先的大气温度；过渡区下降在脉冲相早期相当迅速，可超过100km/s；当蒸发物质在环顶高速相碰时，环顶的密度、压力迅速增大，且温度也有所增加，导致形成激波，其波面以每秒上百公里的速度自环顶向下传播；在脉冲相前期，日冕软x辐射对色球的加热作用可以忽略；等。

Feb. 1988, quasi-biennial and quasi-3-to-4-year oscillation are invenstigated. It is found that the two oscillations are propagating from west to east at all levels, being out of paase for the tropics but in phase for the mid-latitudes; for the latter oscillations in West Pacific, it travels equatorially from both mid-latitudes at low-levels while from south to north through a well-defined channel at...

结果发现：纬向风准两年、准3─4年振荡在热带地区上、下层均一致自西向东传播，但位相相反；在中纬度地区，纬向风准两年、准3─4年振荡上、下层均盛行自西向东传播，且位相一致；西太平洋地区低层纬向风准3─4年振荡均为从南、北半球中纬度地区向赤道传播；高层纬向风准3─4年振荡在175─140°W附近存在一明显的通道，且为自南向北传播，而且在经向上呈1波特征。

The findings: with the apparent dominant frequency of the Ricker wavelet rising, the detection SNR will get worse gradually, it is obvious that the variety of the SNR is slower during the portion of high frequency than during the portion of low frequency; in the usual range of seismic prospecting frequency, the SNR of the chaotic oscillator detection system could partially make up the amplitude attenuation aroused by the transmit of the seismic wave; the results could provide help for detecting the event constituted by aberrant wavelets.

本文以Ricker子波模拟地震子波，研究Ricker子波视主频变化的相应检测效果。研究结果：随着Ricker子波视主频的升高，检测SNR逐渐变差，在高频部分SNR的变化明显比低频部分缓慢；在通常地震勘探频率范围内，混沌振子系统检测SNR有可能部分补偿由于地震波传播引起的幅度降低；为检测由畸变子波构成的同相轴提供一定的可能。

Therelationship between the turbulent kinetic energy and its dissipation rate,whichis widely used to parameterize the dissipation rate in turbulence closure models,is found to hold well for both reversing and rotating flows,but with differentcoefficients.Microstructure profiling measurements at two comparative stations (a deepercentral basin and a local shelf break) in the stratified Yellow Sea are analyzed,with emphasis on tidal and internal-wave induced turbulence near the bottomand in the pyenocline.The water column has a distinct three-layer thermohaline structure,consisting of weakly stratified surface and bottom boundary layers anda narrow sharp pycnocline.Turbulence in the surface layer is controlled by thediurnal cycle of buoyancy flux and wind forcing at the sea surface.while thebottom stress induced by barotropic tidal eurrents dominates turbulence in thebottom boundary layer.The maximum level at which the tidally enhanced mixingcan affect generally depends on the magnitude of the tidal current,and it canbe up to 10-15 m in the Yellow Sea.This suggests that,in the deeper regionsof the shelf seas,turbulent dissipation and mixing are very weak at the levelsbetween the near-bottom tidally enhanced layer and the pycnocline.Therefore,these levels provide a significant bottle neck for the vertical exchanges.In theshallow regions,however,the tidally-induced turbulence can occupy the wholewater colum below the pycnocline.A quarter-diurnal periodicities of the turbulentdissipation rate and eddy diffusivity are found at different heights with evidenttime lag.In the relatively flat central basin,the pycnocline is essentially non-turbulent and internal-wave activity is very weak.Therefore,vertical fluxes acrossthe pycnocline decreased to molecular levels.In contrast,internal waves of variousperiods can be always found near the local shelf break.

对强层化季节黄海两对比性站位(分别位于中央海盆区与局地陆坡区)处层化、内波以及湍流混合特征的研究结果表明：1、强层化季节的陆架海水体一般呈现显著的三层热盐结构，在水体近乎混合均匀的上混合层与潮流底边界层之间为强跃层；2、近表层水体的湍流混合强度主要由海表浮力通量的日变化与海表风强迫控制，而在潮流底边界层内，潮混合是水体热量、物质、动量与能量垂直交换的主要机制；3、潮混合影响的深度由潮流大小决定，在黄海，一般可达10-15 m，因此，在水深较深的区域，在跃层与潮混合所至深度范围的上界之间存在湍流混合非常弱的区域，这显著抑制水体内物质的垂直通量，为物质垂直交换的瓶颈，而在水深较浅的区域，潮混合影响范围可至跃层底部，因此物质在跃层以下整个水体中混合非常均匀，当跃层内间歇性强混合发生时，可以产生显著的跨跃层物质输运；4、近底潮致强湍流耗散缓慢地向上传播，底上不同深度处垂直湍扩散系数也具有显著的位相差异，且二者均随时间呈现四分之一周日周期的变化；5、在地形较为平坦的中央海盆区，内波活动非常微弱，因此跃层内湍流混合非常弱，垂直扩散系数为分子扩散水平，跨跃层物质通量受到显著抑制，而在地形变化较为显著的局地陆坡区，内波活动非常活跃，除内潮的影响外，高频内波与内孤立波的影响也很显著，因此跃层内存在很强的间歇性强混合，内孤立波存在的区域，水体湍流混合显著增强。

The results show that, influenced by the rarefaction waves from the left sharp corner, the reaction zone is separated from the leading shock. Then, the detonation is degenerated into the deflagration. The winkled reaction front can be clearly identified in numerical schlieren and temperature contours.

结果表明：气相爆轰波在分叉管中传播，分叉口左尖点的稀疏波导致诱导激波后压力、温度急剧下降，诱导激波和化学反应区分离，爆轰波衰减为爆燃波。

Two coherent waves which have the same amplitude,frequency and wave speed propagate in opposite direction along a line.So they overlap is a special interference phenomenon.

驻波是由振幅、频率和传播速度都相同的两列相干波，在同一直线上沿相反方向传播时叠加而成的一种特殊形式的干涉现象。

I am accused of being overreligious," she said in her quiet, frank manner,"but that does not prevent me thinking the children very cruel who obstinately commit such suicide.""

客人们在卡罗利娜·埃凯家里，举止就文雅一些，因为卡罗利娜的母亲治家很严厉。

Designed by French fashion house Herm è s, this elegant uniform was manufactured in our home, Hong Kong, and was the first without a hat.

由著名品牌 Herm è s 设计，这件高贵的制服是香港本土制造，是我们第一套不配帽子的制服。