晶体电子在稳恒磁场中的能谱与有效质量近似的适用性

晶体电子在稳恒磁场中的能谱是具有无穷嵌套自相似结构的Ｈｏｆｓｔａｄｔｅｒ“蝴蝶”，在介绍该能谱的基础上对固体物理教材中采用有效质量近似分析回旋共振和德·哈斯－范·阿尔芬效应的适用性条件进行了分析。     

Mechanical behaviors and damage constitutive model of ceramics under shock compression

One-stage light gas gun was utilized to study the dynamic mechanical properties of AD90 alumina subjected to the shock loading. Manganin gauges were adopted to obtain the stress-time histories. The velocity interferometer system for any reflector （VISAR） was used to obtain the free surface velocity profile and determine the Hugoniot elastic limit. The Hugoniot curves were fitted with the experimental data. From Hugoniot curves the compressive behaviors of AD90 alumina were found to change typically from elastic to ＂plastic＂. The dynamic mechanical behaviors for alumina under impact loadings were analyzed by using the path line principle of Lagrange analysis, including the nonlinear characteristics, the strain rate dependence, the dispersion and declination of shock wave in the material. A damage model applicable to ceramics subjected to dynamic compressive loading has been developed. The model was based on the damage micromechanics and wing crack nucleation and growth. The effects of parameters of both the micro-cracks nucleation and the initial crack size on the dynamic fracture strength were discussed. The results of the dynamic damage evolution model were compared with the experimental results and a good agreement was found.     

Optoelectronic Butterfly Interconnection Implementation of an n-bit Parallel Full Addition and Subtraction

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Navier–Stokes computation of transonic vortices over a round leading edge delta wing

A 3D Navier–Stokes solver has been developed to simulate laminar compressible flow over quadrilateral wings. The finite volume technique is employed for spatial discretization with a novel variant for the viscous fluxes. An explicit three-stage Runge–Kutta scheme is used for time integration, taking local time steps according to the linear stability condition derived for application to the Navier–Stokes equations. The code is applied to compute primary and secondary separation vortices at transonic speeds over a 65° swept delta wing with round leading edges and cropped tips. The results are compared with experimental data and Euler solutions, and Reynolds number effects are investigated.     

Microstructures and Optical Properties of Scales of Butterfly Wings

This paper describes the mechanism generating the beautiful wing colors of various male butterflies and the relationship between the wing material and the color appearance. The microstructure of the scales covering the upper surface of the wings was analyzed with the aid of a scanning electron microscope. The basic mechanism of color generation of structurally colored scales is determined for the first time in accordance with the theory of optical interference in thin film layers using a model of wing scales. Optical properties were found in relation to the three-dimensional spectral reflectance of the samples, and differences were observed between the brightness perceived in subjective evaluations and calculated values based on the reflective spectra of the structurally colored wings. The results of this study suggest that the microroughness of the upper wing surface may influence the perceived gloss of structurally colored wings.     

Butterfly and chair clusters using N,O-chelating ligands: A combined crystallographic and mass spectrometric study

The organic ligand (1-methyl-1H-benzo[d]imidazol-2-yl)methanol (HL¹) was used to react with Cu(ClO₄)₂·6H₂O and triethylamine at 80°C to afford the complex [Cu₄(L¹)₆]·(ClO₄)₂·CH₃CN ( 1 ). Every four-coordinated Cu(II) ion is surrounded with NO₃ coordinated environment, and every five-coordinated Cu(II) ion is surrounded with N₂O₃ coordinated environment. Changing the metal salt to Zn(NO₃)₂·6H₂O, and after adding CH₃COONa, afforded the complex [Zn₄(L¹)₄(NO₃)₂(CH₃COO)₂] ( 2 ), in which every five-coordinated Zn(II) ion is surrounded with NO₄ coordinated environment. High-resolution electrospray ionization mass spectrometry results revealed that complex 1 broke into the most stable fragment [Cu₂(L¹)₃]⁺, and it also can assemble high nuclear peaks in solution. For complex 2 , it was found that the complex exhibited different component distribution in solution. Not only were there substitutions between coordinated anions, but the high nuclear peaks could also be detected.     

结构参数对串联微环谐振腔编解码器性能的影响

光码分多址系统中, 光编解码器是影响系统性能的关键因素之一.自相关峰值旁瓣比(P/W)、自互相关峰值比(P/C)是衡量编解码器性能的两个重要指标.以硅基SOI微环谐振腔为载体, 提出了一种串联三环阵列的二维相干OCDMA编解码器模型.详细研究了耦合系数、损耗系数、阵列间距以及通道间隔对微环谐振腔编解码器性能的影响.结果表明, 半径为50 μm的微环, 环与直波导间耦合系数在0.6–0.7之间, 环与环间耦合系数在0.1–0.2之间, 损耗系数 < 2 dB/cm, 阵列间距大于3 mm, 通道间隔在25–36 GHz间时, 编解码器能够获得良好的性能.     

CFD analysis of an oscillating wing at various reduced frequencies

The effect of various reduced frequencies has been examined for an oscillating aspect ratio 10 NACA 0015 wing. An unsteady, compressible three‐dimensional (3D) Navier–Stokes code based on Beam and Warming algorithm with the Baldwin–Lomax turbulence model has been used. The code is validated for the study against published experimental data. The 3D unsteady flow field is simulated for reduced frequency values of 0.1, 0.2 and 0.3 for a fixed mean angle of attack position and fixed amplitude. The type of motion is sinusoidal harmonic. The force coefficients, pressure distributions and flow visualization show that at the given conditions the flow remains attached to the wing surface even at high angles of attack with no clear separation or typical light‐to‐deep category of dynamic stall. Increased magnitude of hysteresis and higher gradients are seen at higher reduced frequencies. The 3D effects are even found at midspan locations. In addition, the rate of decrease in lift near the wing tips compared with the wing root is not much like in the static cases. Copyright © 2008 John Wiley & Sons, Ltd.     

Formation of a samarium alkoxide–aryloxide complex containing a novel butterfly framework: X-ray crystal structures of Sm4(μ3-O-i-Pr)3(μ2-O-i-Pr)4(O-i-Pr)2(O-2,6-i-Pr2C6H3)3(THF) and [Ti(O-i-Pr)2(O-2,6-i-Pr2C6H3) (μ-O-i-Pr)]2

Reaction of a 1:1 mixture of Sm[N(SiMe₃)₂]₃ and Ti(O-i-Pr)₄ with three equivalents of 2,6-di-iso-propylphenol, followed by crystallization from hexane/THF, leads to isolation of the tetranuclear samarium alkoxide Sm₄(₃-O-i-Pr)₃(₂-O-i-Pr)₄(O-i-Pr)₂(O-2,6-i-Pr₂C₆H₃)₃(THF) (1), in addition to the dimeric titanium alkoxide [Ti(O-i-Pr)₂(O-2,6-i-Pr₂C₆H₃)(-O-i-Pr)]₂ (2). 1 crystallizes in the space group while 2 crystallizes in space group P2₁/c. Cell parameters for 1: a = 15.928(6), b = 17.677(7), c = 18.99(1) Å, = 113.24(3), = 94.99(4), = 109.59(2)°, V = 4477(4) ų, D _calc = 1.350 Mg/m³, and Z = 2. Cell parameters for 2: a = 25.336(2), b = 12.082(1), c = 15.570(2) Å, = 96.510(8)°, V = 4735.4(8) ų, D _calc = 1.129 mg/m³, and Z = 4.