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981.
982.
983.
介质层厚对含负折射率介质Bragg微腔的影响 总被引:1,自引:0,他引:1
研究了介质层厚对含负折射率介质一维光子晶体Bragg微腔的缺陷模和双稳态的影响.在中心频率附近将传输矩阵各矩阵元采用泰勒级数展开并取一级近似,得到了缺陷模频率与介质层厚的关系式及品质因子公式.研究结果表明:一级近似法能很好地解释中心频率附近介质层厚对缺陷模频率的影响.理想Bragg微腔结构的缺陷模品质因子最大;递增正折射率介质层厚和增大缺陷层介质层厚、递减负折射率介质层厚及同时等量递减正和负折射率介质层厚,均可使缺陷模红移,双稳态阈值降低. 相似文献
984.
To determine the time-independent constitutive modeling for porous and multiphase nanocrystalline materials and understand the effects of grain size and porosity on their mechanical behavior, each phase was treated as a mixture of grain interior and grain boundary, and pores were taken as a single phase, then Budiansky's self-consistent method was used to calculate the Young's modulus of porous, possible multi-phase, nanocrystalline materials, the prediction being in good agreement with the results in the literature. Further, the established method is extended tosimulate the constitutive relations of porous and possible multi-phase nanocrystalline materials with small plastic deformation in conjunction with the secant-moduli approach and iso-strain assumption. Comparisons between the experimental grain size and porosity dependent mechanical data and the corresponding predictions using the established model show that it appears to be capable of describing the time-independent mechanical behaviors for porous and multi-phase nanocrystalline materials in a small plastic strain range. Further discussion on the modification factor, the advantages and limitations of the model developed were present. 相似文献
985.
EFFECTIVE ELASTIC MODULUS OF BONE-LIKE HIERARCHICAL MATERIALS 总被引:1,自引:0,他引:1
Zuo Shuchun Wei Yueguang 《Acta Mechanica Solida Sinica》2007,20(3):198-205
A shear-lag model is used to study the mechanical properties of bone-like hierarchical materials.The relationship between the overall effective modulus and the number of hierarchy level is obtained.The result is compared with that based on the tension-shear chain model and finite element simulation,respectively.It is shown that all three models can be used to describe the mechanical behavior of the hierarchical material when the number of hierarchy levels is small.By increasing the number of hierarchy level,the shear-lag result is consistent with the finite element result.However the tension-shear chain model leads to an opposite trend.The transition point position depends on the fraction of hard phase,aspect ratio and modulus ratio of hard phase to soft phase.Further discussion is performed on the flaw tolerance size and strength of hierarchical materials based on the shear-lag analysis. 相似文献
986.
Dan Zhao Shuang Yu Wen-Jie Jiang Zhi-Hao Cai Dan-Li Li Ya-Lan Liu Zhi-Zhou Chen 《Molecules (Basel, Switzerland)》2022,27(7)
Population growth and industrial development have exacerbated environmental pollution of both land and aquatic environments with toxic and harmful materials. Luminescence-based chemical sensors crafted for specific hazardous substances operate on host-guest interactions, leading to the detection of target molecules down to the nanomolar range. Particularly, the luminescence-based sensors constructed on the basis of metal-organic frameworks (MOFs) are of increasing interest, as they can not only compensate for the shortcomings of traditional detection techniques, but also can provide more sensitive detection for analytes. Recent years have seen MOFs-based fluorescent sensors show outstanding advantages in the field of hazardous substance identification and detection. Here, we critically discuss the application of MOFs for the detection of a broad scope of hazardous substances, including hazardous gases, heavy metal ions, radioactive ions, antibiotics, pesticides, nitro-explosives, and some harmful solvents as well as luminous and sensing mechanisms of MOF-based fluorescent sensors. The outlook and several crucial issues of this area are also discussed, with the expectation that it may help arouse widespread attention on exploring fluorescent MOFs (LMOFs) in potential sensing applications. 相似文献
987.
988.
研究了温度场中非保守功能梯度材料(FGM)圆板的非线性力学行为.基于经典板理论,推导了受非保守力作用的FGM圆板在温度场中的控制微分方程.采用打靶法分析了由陶瓷二氧化锆和金属钛合金两相材料组成的非保守FGM圆板在均匀和非均匀升温场中的非线性力学行为.给出了不同均匀升温和非均匀升温场下,FGM圆板在非保守载荷作用下的平衡... 相似文献
989.
990.
MXenes是一类新型的二维过渡金属碳/氮化物或碳氮化物,是由Mn+1AXn相物质(MAX相)通过剥离而得到的单层或薄层纳米片。独特的二维层状结构、较大的比表面积以及出色的导电性、机械稳定性和磁性等性能,使MXenes迅速成为研究热点,并已广泛应用于储能、催化、吸附等众多领域。本文总结介绍了二维材料MXenes的制备方法,并重点综述其近年来在环境领域的应用研究进展,如吸附重金属、吸附放射性金属、吸附有机物、二氧化碳的选择性吸附、光催化、电催化、膜分离、传感器、生物活性、电磁吸收与屏蔽等进行了总结与回顾,最后对现阶段存在的问题和未来发展进行了分析。 相似文献