PTS装置工作模式及波形调节

为了对即将建成的PTS装置的实验能力进行分析,对装置的工作模式及波形调节能力进行了分析。装置具有三种工作模式:短脉冲模式、长脉冲模式和波形调节模式。在不同的工作模式下,装置可以进行不同负载的实验研究。在基本工作模式下,在15 nH负载上输出前沿90 ns、幅值8~10 MA脉冲电流。通过电路模拟,对装置在三种工作模式下预计的负载电流输出进行了分析,短脉冲模式下装置负载电流的上升时间约90 ns,长脉冲模式时约200 ns,波形调节模式时可以达到400 ns。模拟结果表明,通过调节激光触发气体开关的触发方式和脉冲输出开关及装置其他参数,PTS装置可以输出脉冲前沿100~400 ns、波形形状在一定范围可调的强电流脉冲。     

Analysis of cardiac tissue by gold cluster ion bombardment

Specific molecules in cardiac tissue of spontaneously hypertensive rats are studied by using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The investigation determines phospholipids, cholesterol, fatty acids and their fragments in the cardiac tissue, with special focus on cardiolipin. Cardiolipin is a unique phospholipid typical for cardiomyocyte mitochondrial membrane and its decrease is involved in pathologic conditions. In the positive polarity, the fragments of phosphatydilcholine are observed in the mass region of 700-850 u. Peaks over mass 1400 u correspond to intact and cationized molecules of cardiolipin. In animal tissue, cardiolipin contains of almost exclusively 18 carbon fatty acids, mostly linoleic acid. Linoleic acid at 279 u, other fatty acids, and phosphatidylglycerol fragments, as precursors of cardiolipin synthesis, are identified in the negative polarity. These data demonstrate that SIMS technique along with Au₃⁺ cluster primary ion beam is a good tool for detection of higher mass biomolecules providing approximately 10 times higher yield in comparison with Au⁺.     

柴油机轴系扭振系统的强非线性主共振

研究柴油机轴系扭振系统强非线性问题.根据拉格朗日方程建立柴油机轴系扭振系统的动力学模型,通过参数变换,应用Modified Lindstedt-Poincaré方法得到柴油机轴系扭振系统强非线性主共振的幅频响应方程,分析系统不同参数对主共振幅频响应的影响.结果表明,系统的幅频响应曲线存在跳跃,随着简谐力矩的减小和阻尼的增大,系统的非线性跳跃减弱,系统的振幅减小,系统主共振的区域也随之减小;随着调谐参数的变化,系统的主共振力幅响应曲线存在两种拓扑结构.MLP方法得出的近似解析解与龙格库塔法得出的数值解吻合.     

根据新课标要求改进原电池实验

按照新课程标准的要求,针对高中物理粤版选修教材中存在的不足,在制作原电池方面做了相应的改进.用重铬酸钾做电解质溶液中的氧化剂,用蓬松棉做盐桥,并用碳棒做电池正极.同时将该方法制做的原电池引入探究原电池内电压和外电压的关系和电池内电阻的大小2个实验中.     

Color Conversion Method for Multiprimary Display Using Matrix Switching

The range of reproducible color, i.e., color gamut, of conventional three-primary display devices is sometimes insufficient for reproducing the natural color of an object through color imaging systems. A multiprimary display is being developed for the purpose of reproducing an expanded color gamut using more than three primary colors. In this paper, a color conversion method is proposed to reproduce the natural color by additive mixture of multiprimary colors. The multiprimary color signal in this conversion method is calculated from the three-dimensional color coordinates CIE-XYZ, considering the dynamic range of each primary color. Divided into some linear elements from the polyhedral color solid of the multiprimary display, the conversion considering the constraint of the dynamic range can be performed by simple calculation without iterative calculation or a huge three-dimensional look up table. A fast computation method with a two-dimensional look-up-table is also presented. Using the proposed method, the result of the color reproduction is experimentally demonstrated by a six-primary projection display.     

Deformations of 2k-Einstein structures

It is shown that the space of infinitesimal deformations of 2k-Einstein structures is finite dimensional on compact non-flat space forms. Moreover, spherical space forms are shown to be rigid in the sense that they are isolated in the corresponding moduli space.     

Gravitational interpretation of the Hitchin equations

By referring to theorems of Donaldson and Hitchin, we exhibit a rigorous AdS/CFT-type correspondence between classical 2+1-dimensional vacuum general relativity theory on Σ×R$\Sigma \times \mathbb{R}$ and SO(3) Hitchin theory (regarded as a classical conformal field theory) on the spacelike past boundary Σ$\Sigma$, a compact, oriented Riemann surface of genus greater than 1. Within this framework we can interpret the 2+1-dimensional vacuum Einstein equation as a decoupled “dual” version of the two-dimensional SO(3) Hitchin equations.     

Muckenhoupt weights and Lindelöf theorem for harmonic mappings

We extend the result of Lavrentiev which asserts that the harmonic measure and the arc-length measure are _A∞$A_{\infty }$ equivalent in a chord-arc Jordan domain. By using this result we extend the classical result of Lindelöf to the class of quasiconformal (q.c.) harmonic mappings by proving the following assertion. Assume that f is a quasiconformal harmonic mapping of the unit disk U onto a Jordan domain. Then the function A(z)=arg?(_∂φ(f(z))/z)$A(z)=\arg ?({\partial }_{\phi }(f(z))/z)$ where z=re^iφ$z=r{e}^{i\phi }$, is well-defined and smooth in U^?={z:0<|z|<1}${\mathbf{U}}^{?}=\{z:0<|z|<1\}$ and has a continuous extension to the boundary of the unit disk if and only if the image domain has C¹$C^1$ boundary.     

Profiles of Essential Oils and Correlations with Phenolic Acids and Primary Metabolites in Flower Buds of Magnolia heptapeta and Magnolia denudata var. purpurascens

Magnolia flower buds are a source of herbal medicines with various active compounds. In this study, differences in the distribution and abundance of major essential oils, phenolic acids, and primary metabolites between white flower buds of Magnolia heptapeta and violet flower buds of Magnolia denudata var. purpurascens were characterised. A multivariate analysis revealed clear separation between the white and violet flower buds with respect to primary and secondary metabolites closely related to metabolic systems. White flower buds contained large amounts of monoterpene hydrocarbons (MH), phenolic acids, aromatic amino acids, and monosaccharides, related to the production of isoprenes, as MH precursors, and the activity of MH synthase. However, concentrations of β-myrcene, a major MH compound, were higher in violet flower buds than in white flower buds, possibly due to higher threonine levels and low acidic conditions induced by comparatively low levels of some organic acids. Moreover, levels of stress-related metabolites, such as oxygenated monoterpenes, proline, and glutamic acid, were higher in violet flower buds than in white flower buds. Our results support the feasibility of metabolic profiling for the identification of phytochemical differences and improve our understanding of the correlated biological pathways for primary and secondary metabolites.