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Composite materials with interpenetrating network structures usually exhibit unexpected merit due to the cooperative interaction. Locally resonant phononic crystals (LRPC) exhibit excellent sound attenuation performance based on a periodical arrangement of sound wave scatters. Inspired by the interpenetrating network structure and the LRPC concept, we develop a locally network anechoic coating (LNAC) that can achieve a wide band of underwater strong acoustic absorption. The experimental results show that the LNAC possesses an excellent underwater acoustic absorbing capacity in a wide frequency range. Moreover, in order to investigate the impact of the interpenetrating network structure, we fabricate a faultage structure sample and the network is disconnected by hard polyurethane (PU). The experimental comparison between the LNAC and the fanltage structure sample shows that the interpenetrating network structure of the LNAC plays an important role in achieving a wide band strong acoustic absorption. 相似文献
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Improving nucleation in the fabrication of high-quality 3D macro-porous copper film through the surface-modification of a polystyrene colloid-assembled template
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A new approach is developed to the fabrication of high-quality
three-dimensional macro-porous copper films. A highly-ordered
macroporous copper film is successfully produced on a
polystyrene sphere (PS) template that has been modified by
sodium dodecyl sulfate (SDS). It is shown that this procedure
can change a hydrophobic surface of PS template into a
hydrophilic surface. The present study is devoted to the
influence of the electrolyte solution transport on the
nucleation process. It is demonstrated that the permeability of
the electrolyte solution in the nanochannels of the PS template
plays an important role in the chemical electrodeposition of
high-quality macroporous copper film. The permeability is
drastically enhanced in our experiment through the surface
modification of the PS templates. The method could be used to
homogeneously produce a large number of nucleations on a
substrate, which is a key factor for the fabrication of the
high-quality macroporous copper film. 相似文献
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为探索重力瞬变引起的约束液滴自激振荡机理, 本文利用落塔装置模拟短时微重力环境并借助高速CCD记录圆形限位基片上液滴整个过程的运动情况. 自激振荡是微重力下液滴形态的重整恢复过程, 边界的限位作用使得液滴在整个运动过程接触线钉扎不变, 具体可分为两个阶段: 首先是振荡的高低点位置高度渐进上升的液滴形态变化阶段, 与重力环境渐进变化有关; 而后是平衡位置附近的阻尼衰减振荡阶段, 此时振荡的频率恒定, 振幅衰减类似孤立黏性液滴的指数衰减过程. 对于第二阶段, 在高低点等位置处存在高度不变过程, 高度起伏变化时液滴振荡模式类似自由液滴二阶振荡, 高度不变时振荡模式类似自由液滴三阶振荡. 此外, 对于本实验体系的恒定接触面积的钉扎约束, 液滴的体积量不同时, 内驱振荡的阶段和模式不变, 但具体的振荡过程有所不同. 对于大体积液滴, 会在初始振荡的中间位置出现高度不变现象, 并且随振荡逐渐消失; 而小液滴中间位置则不存在此现象, 波形较一致; 第二阶段小体积液滴振幅衰减的阻尼率更大, 无量纲频率也更高. 相似文献
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Marangoni效应是一种液体在界面张力梯度作用下的自发流动行为.液体界面上液体的Marangoni效应在工程技术领域具有重要作用.本文使用硅油作为驱动液体,正十六烷作为被驱动液体,十二烷基硫酸钠溶液作为液体基底,通过高速相机捕捉正十六烷受驱动铺展的整个过程,研究了三相液体系统中液滴的Marangoni效应.实验发现,正十六烷在硅油的驱动下从内向外铺展,形成液体圆环.本文根据正十六烷圆环内、外边界铺展行为,分析了正十六烷内边界和外边界的铺展原理,并研究了滴入硅油体积对于铺展过程的影响.研究发现,正十六烷内边界铺展与单一液滴的铺展规律相同,正十六烷内边界前期铺展由重力主导,内边界铺展标度律在R~t1/4到R~t1/2范围.随后铺展由界面张力梯度主导,内边界铺展标度律为R~t3/4.因内边界铺展受重力影响,内边界的铺展速度与硅油体积成正相关.而正十六烷外边界在硅油驱动下,因接触角改变而产生界面张力梯度,在界面张力梯度作用下外边界铺展标度律为R~t3/4. 相似文献
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The monodisperse polystyrene spheres are assembled into the colloidal crystal on the glass substrate by vertical deposition method, which is aimed at the so-called photonic crystal applications. The structural information of the bulk colloidal crystal is crucial for understanding the crystal growth mechanism and devel- oping the various applications of colloidal crystal. Small-angle X-ray scattering (SAXS) technique was used to obtain the bulk structure of the colloidal crystal at Beamline lW2A of BSRF. It is found that the SAXS pattern is sensitive to the relative orientation between the colloidal sample and the incident X-ray direction. The crystal lattice was well distinguished and determined by the SAXS data. 相似文献
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Wide-band underwater acoustic absorption based on locally resonant unit and interpenetrating network structure 总被引:1,自引:0,他引:1
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The interpenetrating network structure provides an interesting avenue to novel materials. Locally resonant phononic
crystal (LRPC) exhibits excellent sound attenuation performance based on the periodical arrangement of sound wave scatters.
Combining the LRPC concept and interpenetrating network glassy structure, this paper has developed a new material which can achieve a wide band underwater strong acoustic absorption. Underwater absorption coefficients of different samples were measured by the pulse tube. Measurement results show that the new material possesses excellent underwater acoustic effects in a wide frequency range.Moreover, in order to investigate impacts of locally resonant units,some defects are introduced into the sample. The experimental result and the theoretical calculation both show that locally resonant units being connected to a network structure play an important role in achieving a wide band strong acoustic absorption. 相似文献