Microwave permeability of single cobalt nanotube studied by micromagnetics simulations and generalized Snoek’s law

Microwave permeability spectra of single Co nanotube under equilibrium state have been studied by micromagnetics simulation.More than four obvious resonance peaks have been found(11.72,24.20,33.18 and 39.55 GHz).Such large resonance frequency cannot be found in other traditional magnetic materials.The configurations of magnetic moments along the nanotube have been simulated.The results show that the top end of nanotube has a"flow-out"pattern of magnetic moments configuration.The bottom end has a"flow-in"pattern of magnetic moments configuration.The magnetic moments within the main body of nanotube are aligned perfectly along the length of nanotube.The magnitude of natural resonance peak is strongly related to the volume fraction of a zone,which has the same orientation of magnetic moments.Large microwave permeability values have been found for single nanotube.The generalized Snoek’s law has been used to validate the micromagnetics simulations in this paper.     

Heterogeneous acid catalytic esterification by porous polyoxometalate-tantalum pentoxide nanocomposites

Polyoxometalates (POMs) are useful catalysts in both redox and acid catalysis reactions since its catalytic features can be controlled at a molecular level. We investigated POM (POM = H₃PW₁₂O₄₀) on tantalum pentoxide (Ta₂O₅) via hydrolysis of tantalum pentachloride (TaCl₅) in the presence of POM using the sol-gel method for acid catalytic reaction. All obtained amorphous materials have been characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transform infrared (FT-IR) spectra, Raman scattering spectroscopy, ³¹P magic-angle spinning (MAS) NMR, field emission scanning electron microscopy (FESEM), and nitrogen adsorption/desorption analysis, in order to confirm the structure integrity of the Keggin unit in as-prepared composites and investigate the morphology and surface textural property of the composites. Catalytic activity of the catalysts has been evaluated for esterification of acetic acid with ethanol as a model reaction with different catalytic reaction parameters such as POM loading, reaction time, catalyst dose, molar ratio of the reactants, etc. The conversion of ethanol reached 87.4 % and the turnover frequency (TOF) was 2.9×10³.Meanwhile, it is easy to separate and recover POM/Ta₂O₅ from the reaction system.     

基于计算机视觉的腾空飞脚错误动作识别模型

以南拳项目中腾空飞脚动作为例,依据2003版竞技武术套路竞赛规则,建立三维坐标系,将动作质量(A组)评分规则中的腾空飞脚动作的扣分规则进行形式化描述,以利于电子裁判对错误动作进行识别.针对每个动作建立错误函数和基于计算机视觉的腾空飞脚动作扣分模型,并举例说明.     

塑料瓶贴标用乳液胶的研究

本文分析了塑料瓶的表面结构特性及其对贴标胶的要求，简介乳液胶的合成过程，讨论了聚会温度、搅拌速度、增粘剂和改性剂对贴标胶的影响。     

活性石灰在冶金生产中的应用

介绍了活性石灰在炼钢、铁水预处理、精炼、烧结等冶金生产中的应用。     

The influence of publication delays on three ISI indicators

Summary Based on the transform function model of the observed citing process, the analytical expression of the age distribution of citations is deduced, and it is theoretically proved that the peak value of the citation distribution curve would fall and shift backward along with increasing the average publication delay and the peak age has a direct proportion relation with the pure delay and would be prolonged along with increasing the delay or decreasing the aging rate. The influence of the average publication delay on three ISI indicators impact factor, immediacy index and cited half-life are studied; in one subject discipline, the bigger the delay, the lower the three indicators of journals. Using the sensitivity theory, sensitivity formulae of the three indicators to publication delay parameters are deduced and it is found that responses of these indicators to changes of publication delays are different according to different time constant of the aging process; The faster the aging rate of a discipline literature is, the worse the influence of publication delays on the indicators of journals in the discipline.     

Piezoelectromagnetic waves guided by the surface of a ceramic cylinder

Summary The propagation of shear horizontal (SH) waves over the surface of a circular cylinder of polarized ceramics is studied from the three-dimensional equations of linear piezoelectromagnetism with full electromagnetic coupling. An exact solution is obtained.     

冲轧钼导杆的模具设计

设计了冲轧特种灯钼导杆的复合冲模.对冲模刀具材质和模块材料做了选择性实验,结果得出,刀具选用W18Cr4V效果最好,模块宜用45#钢.采用本设计的冲模能够成功地冲轧不同规格的高质量特种灯用钼导杆.     

An interpolation model to accelerate the frequency-domain response calculation of grounding systems using the method of moments

The transient characteristics of grounding systems are essential for their designs and related electromagnetic-compatibility problems in power systems. Although the method of moments (MoM) is a popular way to analyze the characteristics of grounding systems, it is time-consuming. In this paper, a two-stage method is presented to construct fitted models of the frequency-domain responses of grounding systems to accelerate the calculations of the MoM. In the first stage, the adaptive model-based parameter estimation is used to adaptively choose the most valuable frequency sampling points to construct the initial fitted functions, and then the fitted functions are adjusted in the second stage by comparing the fitted results with those computed by the first principle model at some points. The validation was achieved by a comparison of the numerical results and those obtained by inverse fast Fourier transformation.     

永磁式双转子电机的理论与实践

根据电机学的基本理论,分析了永磁式双转子电机的原理和结构特点,结合其特点,指出这类电机生产和使用中存在的关键问题,为进一步的工程应用做好准备。