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Influence of Coating Layer on Acoustic Wave Propagation in a Random Complex Medium with Resonant Scatterers 下载免费PDF全文
We investigate the influence of coating layer on acoustic wave propagation in a dispersed random medium consisting of coa.ted fibers.In the strong-scattering regime, the characteristics of wave scattering resonances are found to evolve regularly with the properties of the coating layer.By theoretical calculation,frequency gaps are found in acoustic excitation spectra in a random medium.The scattering cross section results present the evolution of scattering resonances with the properties of the coating layer,which offers a good explanation for the change of the frequency gaps.The velocity of the propagation quasi-mode is also shown to depend on the filling fraction of the coating layer.We use the generalized coherent potential-approximation approach to solve acoustic wave dispersion relations in a complicated random medium consisting of coating-structure scatterers.It is shown that our model reveals subtle changes in the behavior of the acoustic wave propagating quasi-modes. 相似文献
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一、前言 我厂生产的 Cr Mu Ti是齿轮用钢.它广泛用于汽车、拖拉机变速箱中的齿轮、内燃机上的凸轮、活塞等,它往往要求表面具有高的硬度和耐磨性.而心部则要求具有足够的强度和韧性,使零件既有耐磨的表面,又能承受大的冲击载荷,20Cr Mn Ti是能保证心部足够的韧性和强度的理想材质.齿轮损坏的主要原因是齿面磨损,齿面接触疲劳破坏等等.这些损坏主要是齿轮表面残余奥氏体量过多,硬度不足而造成,即关键是材质淬透性.众所周知;所谓淬透性系指淬硬层的深度.钢的化学成份和淬透性是否存在着相关关系,淬透性是否可以予测和控制也是当前炼钢生产… 相似文献
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晶体的铁电性及其实验判据周镇宏,吴福根(广东工学院,广州510090)1引言铁电体的发现可追溯到三百多年前.1655年,法国药剂师塞格涅特(P.deLa-Seignette)在罗息(LaRochelle)地方最早制造出了酒石酸钾钠(NaKC4H4O6... 相似文献
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自催化反应的临床界现象 总被引:4,自引:0,他引:4
提出一种自催化反应模式,证明在非平衡系统中存在类一组与类二级相变之间的转变点,它也代表一种连续相变,并类似于Landau在他的二级相变理论中所预见的“第二类相变的临界点”。同时指出与后者的区别,例如,两者的临界指数有不同的配置。 相似文献
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化学反应中的双稳性的临界现象及Landau相变理论 总被引:4,自引:0,他引:4
本文通过两个典型事例,即Langmuir形式的交换过程和Schlogle用以模拟一级相变的自催化反应,阐明化学反应系统的双稳性临界现象同样可以纳入Landau相变理论的模式。从而进一步揭示了双稳系统一级相变线临界点的二级(连续)相变特征,同时也揭示了作为远离平衡的化学反应双稳性临界现象的共性,以至于在更大范围内临界现象的共性。将相变的Landau理论,由原来的处于热平衡的凝聚物质推广到范围更宽广,表现更为丰富多彩的远离平衡系统的临界现象。 相似文献
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Effects of orientation and shape of holes on the band gaps in water waves over periodically drilled bottoms 下载免费PDF全文
The complete band gaps (CBGs) of shallow water waves propagating over bottoms with periodically drilled holes are investigated numerically by the plane wave expansion method. Four different patterns are considered, containing triangular, square, hexagonal and circular cross-sectioned holes arranged into triangular lattices. Results show that the width of CBGs can be changed by adjusting the orientation of noncircular holes and the effect of hole shape on the width of the maximal CBGs is discussed. 相似文献