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81.
82.
Zicheng Zuo Yanbing Guo Yuliang Li Jing Lv Huibiao Liu Jialiang Xu Yongjun Li 《Macromolecular rapid communications》2009,30(22):1940-1944
Large scale of well‐ordered macroporous π‐conjugated polymer monoliths have been successfully prepared through a new approach using micrometer‐sized naphthalene crystals as templates. The macroporous monoliths of poly(p‐phenylenevinylene) (PPV) and poly(p‐phenyleneethynylene) (PPE) grew along the unidirectional freezing direction inside the template naphthalene crystals which lead to the formation of controlling morphologies and homogeneous diameters. The polymer monoliths show straight and lamella macroporous structures. The diameters of pores and the thickness of pore walls can be controlled by tuning the freezing temperature.
83.
Given the flexibility of choosing negative elastic parameters, we construct material structures that can induce two resonance phenomena, referred to as the elastodynamical resonances. They mimic the emerging plasmon/polariton resonance and anomalous localized resonance in optics for subwavelength particles. However, we study the peculiar resonance phenomena for linear elasticity beyond the subwavelength regime. It is shown that the resonance behaviors possess distinct characters, with some similar to the subwavelength resonances, but some sharply different due to the frequency effect. It is particularly noted that we construct a core–shell material structure that can induce anomalous localized resonance as well as cloaking phenomena beyond the quasistatic limit. The study is boiled down to analyzing the so-called elastic Neumann–Poincaré (N-P) operator in the frequency regime. We provide an in-depth analysis of the spectral properties of the N-P operator on a circular domain beyond the quasistatic approximation, and these results are of independent interest to the spectral theory of layer potential operators. 相似文献
84.
A. A. Smerdov 《Mechanics of Composite Materials》1999,35(3):223-226
The failure of unidirectional composite tubes in the Chinese lantern mode is analyzed in the case of a tube compressed by a weight type load, which retains its magnitude after splitting of the tube. Calculation formulas are derived for predicting the critical load. The main regularities of the solution obtained are illustrated with specific examples. It is shown that the nature of the acting load must be considered in the analysis of unidirectional composite tubular bars with axial reinforcement.Bauman Moscow State Technical University, Russia. Scientific Research Institute of Mechanical Engineering, Moscow, Russia. Translated from Mekhanika Komspozitnykh Materialov, Vol. 35, No. 3, pp. 319–324, May–June, 1999. 相似文献
85.
报道了非晶态铁基合金(Fe65.9Cr11.6Si7.5B15和Fe60Co5.9Cr11.6Si7.5B15)退火样品的回线偏移现象.研究了偏移回线与测量磁场Hm,温度T和时间t的关系.基于退火产生的硬磁颗粒与剩余非晶软磁母体之间的静磁相互作用机制,利用等效的单向各向异性模型可以很好地分
关键词:
铁基非晶合金
偏移回线
单向各向异性 相似文献
86.
对不同温度下的耐高温树脂基复合材料T300/BMP350的0°和90°单向层合板进行静载拉伸实验,得到材料在不同温度下的应力-应变响应,分析了温度对材料的力学性能影响。通过高温应变片采集到材料在高温环境下的热输出和破坏时的极限应变,分析了材料的热行为。通过分析材料的应力-应变曲线和失效模式,研究了材料的损伤和失效机理。研究结果表明:T300/BMP350树脂基复合材料具有很好的耐高温性能。高温下0°方向的拉伸强度和模量保持率达到80%以上,90°方向的拉伸强度和模量保持率可以达到50%以上。高温环境对材料的极限应变影响不大,材料破坏模式均为脆性破坏。基于实验结果,对材料的强度随温度的变化进行拟合,预测了该材料在350℃时0°和90°的拉伸强度。 相似文献
87.
The phenomenon of energy unidirectional transmission is numerically investigated by using a system of two coupled discrete nonlinear electrical transmission lines, each line of the network contains a finite number of cells and has different pass band structures, respectively. Using numerical simulations, we examine the frequency multiplication of the driving frequency and the lattice filtering effect in the line. These lead to the generation of energy unidirectional transmission. In the present work, energy is carried by the second harmonic wave in the pass band. In addition, we also study the dependence of the energy efficiency on the driving amplitude and other parameters of the model, such as the system size and the nonlinear coefficient, by calculation. Furthermore, after detailed numerical simulation, an experimental demonstration is realized. The experimental results agree with those in simulation qualitatively. 相似文献
88.
Preparation of macroporous hydrophobic materials filled with aligned porous hydrophilic domain via emulsion‐templated and unidirectional freezing technique 下载免费PDF全文
A new class of porous materials, having hydrophobic scaffold embedded with aligned porous hydrophilic domains, was in situ fabricated through combination of emulsion‐templated method and unidirectional freezing technique. A water‐in‐oil high internal phase emulsion (HIPE) was prepared with the mixture of styrene and divinylbenzene as continuous phase and a poly(vinyl alcohol) (PVA) aqueous solution as dispersed phase. After polymerization of the continuous phase and subsequently unidirectional freezing, the dispersed phase, a macroporous poly(styrene/divinylbenzene) embedded with an aligned PVA domain, was obtained. The effects of the polymerization temperature, PVA concentration, and freezing rate on these porous materials were investigated. It was found that the PVA domain size and the aligned channel size were dependent on the polymerization temperature, the PVA concentration, and freezing rate. The fabrication method in this work, combining of unidirectional freezing and emulsion template, not only allows to prepare hydrophobic–hydrophilic polyHIPEs having a sea island structure but also dramatically improves the stiffness and specific surface area of the resulting polyHIPEs. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
89.
Here, a two-dimensional (2D) hole-type square lattice photonic crystal is shown to achieve invisibility cloaking based on all-angle self-collimation. The proposed structure, which is composed of the high-refraction-index dielectric material PbTe (nPbTe ≈ 6), is applicable in the mid-infrared (mid-IR) frequency range. The cloaking region is capable of hiding any object of any shape and size since the incoming wave does not interact with the cloaked object. The optimization process and the functionality of the proposed structure are investigated by equal frequency contour analysis and the finite difference time domain (FDTD) method. 相似文献
90.