CSNS铁氧体环性能初步测试

用于中国散裂中子源CSNS的环射频铁氧体同轴谐振腔,工作频率在1.02MHz至2.42MHz.论文对决定腔性能的铁氧体环材料进行了性能测试研究.通过改变铁氧体环的偏置磁场来改变铁氧体的磁导率,使腔的等效电感发生变化,从而使得LC并联谐振回路的谐振频率改变,进而获得铁氧体环在不同频率,不同高频磁场强度下的μrqf、品质因数和功率密度值.本文比较了几种不同铁氧体环的测量结果,选择适合于CSNS的环射频铁氧体谐振腔的材料为4M2.     

含左手材料的一维准周期光子晶体的透射特性研究

利用传输矩阵法,计算了含左手材料的一维准周期光子晶体的透射谱,并分析了其变化规律.结果表明:nR/ηL的比值对其透射谱影响较大,当比值为1时,透射率T恒为1,与N和△dR、△dL均无关;而当nR/ηL的比值在1.7～2.0之间、N=10时,透射谱的通带呈尖峰状,且通带中心在偶数倍频处有红移,通带峰值不变;而当nR/ηL的比值大于2.0时,在高频处的通带峰值变小,两介质的递增厚度△dR、△dL越大,nR越大,这种变化越明显,改变周期数N,对透射谱有较大的影响.     

金属泡沫内固-液相变数值模拟研究

本文利用多孔介质的体积平均模型,建立了金属泡沫内固-液相变的两方程数学物理模型,该模型考虑了熔化液态石蜡自然对流的影响、石蜡与泡沫局部非热平衡效应。模拟研究了熔化过程中不同泡沫孔隙率下液态石蜡内部的速度场、相界面位置随时间的变化规律,通过研究石蜡温度场和泡沫温度场的差异,证实了采用两方程模型的必要性。     

Complete Polarization Conversion Characteristics of Dielectric Grating Composed of Left-Handed Materials

The TE/TM polarization conversion characteristics of dielectric grating composed of left-handed materials for the case of plane wave oblique incidence are carefully investigated by a method which combines the multimode network theory with the rigorous mode matching method. It is indicated that complete polarization conversion between TE and TM modes can be realized using left-handed gratings. This can hardly achieve in the conventional right-handed gratings. Comparisons of polarization conversion properties between right-handed gratings and left-handed gratings are given with physical explanations. This unique merit of left-handed periodic structure is of important significance for accurate design of new millimeter wave TE/TM polarization converters.     

A Double-Beam Radiation Leaky Wave Antenna Based on Left-Handed Material Slab with Metallic Strips Periodically Loaded

A new leaky-wave antenna structure is carefully investigated in the paper, which is based on a grounded Left-Handed material (LHM) slab periodically loaded with metal strips. A rigorous formulation similar to the spectral domain method for planar circuits is deduced to analyze the radiation characteristics of the antenna. Theoretical analysis results reveal that at specific frequency region or with proper geometrical parameters chosen, the present structure supports simultaneously two leaky modes corresponding to the forward and backward radiations. The principle of the antenna is due to the peculiar propagation properties of the unperturbed LHM grounded slab waveguide, which is totally different from the phenomenon of double or even more space harmonic mode radiations in normal periodic structures. Extensive numerical results of the leakage characteristics are given to establish useful guidelines for the design of the new type leaky wave antenna.     

含各向异性左手材料一维光子晶体的传输特性分析

采用光学传输矩阵方法,研究了由各向异性左、右手材料交替排列构成的一维人工周期结构的带隙结构和传输特性,讨论了反射率随入射角度的变化关系。结果表明,含各向异性左手材料的光子晶体比传统的光子晶体有更宽的禁带;含各向异性左手材料的一维光予晶体具有更好的角度特性,可以用来实现对某一低频波段的全方位反射;通过适当选取左手材料的参数,禁带中会出现狭窄的透射峰。     

Electronic Spectrum and Optical Properties of Quantum Wires Made from Transition Metal Dichalcogenides

JETP Letters - The energy spectrum and optical absorption in a quantum wire of monolayer transition metal dichalcogenides in the shape of a straight strip are investigated theoretically. It is...     

Study of the Diffusion Coefficient in Thin Articles Made of Porous Materials

Technical Physics - A novel method of studying mass transfer processes in porous media has been considered. The method allows one to carry out operation monitoring of the diffusivity in thin...     

Simulation of Dampers Made of Viscoelastic Materials

Technical Physics - Taking damping into account in the problems of structural dynamics is an important and nontrivial problem. Its complexity is primarily determined by the required specification...     

左手介质矩形波导导模和表面模的场分布

从麦克斯韦方程组出发,结合电磁场的边界条件,推导出介质矩形波导导模的一般色散方程.对普通介质矩形波导和左手介质矩形波导的导模场分布分别进行了数值模拟.通过对比两种介质矩形波导的导模场分布的模拟结果,发现左手介质矩形波导Ex22模的场分布比普通介质波导Ex00模的场更集中在波导中部.同时,根据处理普通介质矩形波导的Marcatili方法.类比得到左手介质矩形波导表面模的色散方程,并数值模拟了低阶模的场分布,结果表明,能量主要集中在波导的四个角区以及波导的边缘.     

Invisible Spherical Objects Made of Isotropic Materials

Radiophysics and Quantum Electronics - It is demonstrated that Maxwell’s equations permit the existence of invisible spherical objects made of materials with isotropic electromagnetic...     

Numerical Simulations of Backward-to-Forward Leaky-Wave Antenna with Composite Right/Left-Handed Coplanar Waveguide

A composite right/left-handed （CRLH） coplanar waveguide （CPW） structure and its leaky-wave antenna （LWA） with continuous backward-to-forward scanning applications are proposed. The structure of the CRLH transmission line （TL） is composed of split-ring resonators （SRRs） for left-handed （LH） series capacitance and short-circuited stubs connected between the CPW central signal line and the ground for LH shunt inductance, while the unavoidable right-handed （RH） parasitic effects series inductance and shunt capacitance are generated by wave propagation through the host transmission line. The dispersion relations are calculated and compared with the equivalent circuit model method and 3D full-wave simulations, which can be used to determine the physical dimensions of the CRLH-CPW, such as in the balanced CRLH-TL case. As a main example, a CRLH-CPW-LWA operating from 1.67 GHz to 1.80 GHz with the dispersion characteristics of the balanced CRLH-TL case shows continuous leakage frequency band （fast wave region） from LH （phase constant β 〈0, .67〈f〈1.74 GHz） to RH （β〉0, 1.74〈f〈1.80 GHz） state through the transition frequency point （β=0, f=1.74 GHz）, whereas conventional LWAs operated in RH state only provide forward scanning capabilities （β〉0）.     

渔网电磁超介质左手通带的超常透射及其电场增强效应的数值研究

本文利用电磁场数值模拟方法研究了分布矩形孔阵列的"金属-电介质-金属"三明治渔网电磁超介质在其左手通带发生的超常透射现象和不同模式激发下的电场增强效应。结果证实左手通带紧邻的超常光学传输峰源于波导共振模式,利用超常传输效应可以有效降低电磁超介质的损耗,提高左手性能;波导共振模和左手通带对应的反对称磁模能够分别在孔洞和金属夹层区域激发超过11倍的增强电场,因此渔网电磁超介质结构在表面增强光谱和传感等方面也具有潜在应用价值。     

粉末压片法XRF分析锰锌铁氧体磁性材料的成分

试样经研磨、过筛,硼酸垫底,压成片样,用X射线荧光光谱法（XRF）测定锰锌铁氧体Mn3O4、ZnO、Fe2O3成分含量,同时自制一套参考标样作标样。方法快速、精确、稳定,可以满足生产及研发定量分析要求。     

金属材料中高能重离子辐照效应的理论描述

简要介绍了高能重离子在金属材料中引起辐照效应的主要理论,特别是与电子能损引起的缺陷产生与演化、离子潜径迹形成、辐照相变以及各向异性塑性形变等效应相应的理论描述.     

Electrodynamic Characteristics of Horn Microwave Antennas Made of Graphene-Containing Carbon-Composite Materials

Technical Physics - Electrodynamic characteristics of the L-and C-range horn antennas made of carbon-composite materials with graphene-containing binding substance are studied. The main attention...     

Analytical Method to Evaluate Hugoniot of Metallic Materials with Different Initial Temperatures

An analytical method is proposed to evaluate the Hugoniot parameters of preheated metallic materials by relating to its principal Hugoniot. Modelling calculations for 1100 Al, Cu and Ta show that the preheating lowers to a certain extent the shock impedance and the degree of lowering the shock impedance increases with increasing preheating temperature. The Hugoniots of 6061-T6 Al and TC4 preheated flyers at known preheating temperatures are evaluated, and are utilized to calculate the particle velocity and shock pressure using the impedance-match method based on the measured shock wave velocity and impact velocity reported in Z pinch-driven and three-stage gun-driven Hugoniot experiments. The presented method allows a reasonable evaluation for Hugoniot of the preheated metallic flyers.     

The Surface Layer States in Metallic Materials Subjected to Dry Sliding and Electric Current

Russian Physics Journal - The structure and properties of surface layers of metallic materials undergoing structural-phase changes as a result of their contact interactions in the form of dry...     

不同厚度衬底上矩形孔金属结构的太赫兹透射特性数值分析

利用时域有限差分法对不同材料和厚度衬底上矩形孔金属结构太赫兹（THz）波的透射特性进行了数值分析。研究表明：矩形孔金属阵列对THz光谱具有频率选择特性,这为太赫兹滤波功能器件的开发提供了基础。在实际应用中,这种金属微结构常常需要制备在某种衬底上,而衬底材料及厚度无疑会对其太赫兹透射特性带来影响。研究了不同衬底材料和衬底厚度的矩形孔金属结构太赫兹透射性质,通过数值模拟研究发现,对于同一种衬底材料,随着衬底厚度的增加,矩形孔金属结构的透射峰峰位向低频移动。比较高阻硅和聚四氟乙烯两种衬底材料发现,高介电常数的硅衬底引起的透射峰移动更为明显。