Hierarchical Magnetic Network Constructed by CoFe Nanoparticles Suspended Within “Tubes on Rods” Matrix Toward Enhanced Microwave Absorption

Hierarchical magnetic-dielectric composites are promising functional materials with prospective applications in microwave absorption(MA)field.Herein,a three-dimension hierarchical“nanotubes on microrods,”core–shell magnetic metal–carbon composite is rationally constructed for the first time via a fast metal–organic frameworksbased ligand exchange strategy followed by a carbonization treatment with melamine.Abundant magnetic CoFe nanoparticles are embedded within one-dimensional graphitized carbon/carbon nanotubes supported on micro-scale Mo2N rod(Mo2N@CoFe@C/CNT),constructing a special multi-dimension hierarchical MA material.Ligand exchange reaction is found to determine the formation of hierarchical magnetic-dielectric composite,which is assembled by dielectric Mo2N as core and spatially dispersed CoFe nanoparticles within C/CNTs as shell.Mo2N@CoFe@C/CNT composites exhibit superior MA performance with maximum reflection loss of−53.5 dB at 2 mm thickness and show a broad effective absorption bandwidth of 5.0 GHz.The Mo2N@CoFe@C/CNT composites hold the following advantages:(1)hierarchical core–shell structure offers plentiful of heterojunction interfaces and triggers interfacial polarization,(2)unique electronic migration/hop paths in the graphitized C/CNTs and Mo2N rod facilitate conductive loss,(3)highly dispersed magnetic CoFe nanoparticles within“tubes on rods”matrix build multi-scale magnetic coupling network and reinforce magnetic response capability,confirmed by the off-axis electron holography.     

城市再生水资源可利用量分析

本文主要以大连经济开发区污水处理二厂为实例,针对开发区地形地貌、水资源状况、用水、排水及经济社会发展等特点,在综合考虑各种影响因素的基础上,采用趋势分析法、定额分析法及折减系数法等多种方法,对污水处理二厂所在地区各水平年用水量、污水及再生水可利用量进行预测分析,为其它地区污水再生利用分析计算提供参考.     

饱和弹性半空间在低频谐和集中力下的积分形式解

本文采用解耦联合方程组，算子法解回代方程，推导饱和土低频Ｌａｍｅｂ积分形式解，并退化为一般弹性半空间的积分形式解，为饱和土动孔隙水压力和动力响应的计算提供了方法。算例证实本文推导的可靠性，其结论对工程有指导意义。     

青东凹陷油气资源潜力

青东凹陷是济阳坳陷的一个次级的构造单元,位于渤海浅水海域。该凹陷主力油源层埋藏浅,成熟度低,人们对其勘探潜力认识不足。文章对青东凹陷石油基础地质条件进行了综合分析,认为其深洼区烃源岩已经成熟;并提出凹陷构造运动微弱,保存条件较好,以及油气近距离成藏等新认识;经研究认为有利勘探区域为靠近生油中心的各类构造和地层 圈闭。     

加强对物探仪器装备的经济管理

物探仪器、特别是地震勘探仪器,作为大型特种装备,其管理上应包含三个方面的内容:设备管理、技术管理和经济管理。这个方面既有明显区别,又有紧密的内在联系。本文是根据仪器设备的一般经济管理模式来研究和探讨目前大型物探仪器装备的经济管理问题。     

应用水化硅酸盐纳米粉体制备块体材料

以磨细生石灰和硅质原料的混合物为前驱物,采用动态水热合成方法制备了水化硅酸盐纳米粉体.借助SEM、TEM及氮吸附等测试方法,分析了制得的水化硅酸盐粉体的形貌、粒径和比表面积.将制得的水化硅酸盐纳米粉体压制成块状固体.采用正交设计方法研究了成型压力、水泥掺量、纤维掺量、聚合物掺量等因素对块体材料力学性能的影响.结果表明:由该粉体压制成的块体材料立即具有强度和耐水性,且表观密度低;成型压力是影响其力学性能最显著的因素.     

声学-结构设计灵敏度分析

声学 -结构设计灵敏度分析揭示了结构振动引起的辐射声压与结构设计变量之间的关系。分别用有限元法和边界元法计算结构设计灵敏度和声学灵敏度。将两个灵敏度结合得到最终的声学 -结构设计灵敏度。在边界元计算中 ,采用退化元处理奇异积分问题 ,对特征频率不唯一问题采用CHIEF方法处理。以脉动球和箱体为例 ,验证了算法的可行性和精确性。     

Effect of particle size distribution on green properties during high velocity compaction

Iron powders with two different particle size distributions were compacted by high velocity compaction. The influences of particle size distribution and impact velocity on green properties, including green density, springback, tensile strength and bending strength etc., were studied with scanning electron microscopy (SEM) and a computer controlled universal testing machine. The results show that the particle size distribution and the impact velocity strongly affect its properties. Wider size distribution results in green compact with higher density and better strength. Furthermore, springback of compacts is lower produced by the powder with wider size distribution, especially for radial springback. As impact velocity increases, its green density and green strength gradually increases, but the increasing rate of density decreases gradually. No special relation is found between springback and impact velocity. In addition, the axial springback and the bending strength are higher than the radial springback and the tensile strength, respectively.     

Broad band focusing and demultiplexing of in-plane propagating surface plasmons

On the basis of a novel phase modulation method by in-plane diffraction processes, a well-designed nanoarray on metal surface is proposed to realize a broad band focusing (bandwidth ～100 nm) and a demultiplexing element (resolution ～12 nm) of surface plasmon polariton (SPP) waves. Moreover, sublattice arrays are developed to achieve an improved demultiplexer and confocal SPP beams. The proposed scheme with implemented functionalities is designed totally in planar dimension, which is free of the SPP coupling process and indicates more practical application in photonic integrations.