THE SYMMETRY CONSTRAINT AND LEVY EVOLUTION EQUATION HIERARCHY

1IntroductionThesymmetryconstraintgivestheinterrelationbetweenhigher-dimensionalintegrablesystemsandlower-dimensionalintegrablesystemsandprovidesadirectmethodtoconstructsolutionsofhigher-dimensionalintegrablesystemsbysolvinglower-dimensionalintegrablesyst…     

Remarks on the structural evidence of high reactivity of arsonium ylides bearing with an electron-withdrawing substituent

The crystal structures of benzoylmethylene triphenyl-arsorane, -phosphorane and triphenylarsine oxide have been studied so as to well account for the high reactivity of the title compounds.     

电光双折射扫描滤波法提高啁啾脉冲对比度

提出了一种通过扫描滤波来提高啁啾脉冲对比度的方法,并分析了该方法的原理。与传统的非线性滤波技术不同,扫描滤波方法消除预脉冲时,选通原理是基于光的频率而不是强度。以电光双折射扫描滤波器为例,说明了扫描滤波法的具体应用。通过数值模拟及实验研究,发现电光双折射扫描滤波法可以有效地消除主脉冲以前几百ps的预脉冲,并且主脉冲同时还能保证较高的透过率。     

Studies on Timing Jitter in WDM Dispersion-Managed System by Variational Method

The variational method is employed to describe the basic properties of soliton parameters and to evaluate the timing jitter by considering multi-perturbations in wavelength-division-multiplexing (WDM) dispersion-managed soliton (DMS) system. The bit error rates (BER) of different dispersion managed systems, which induced by the timing jitter are given and compared. From that, there exist optimizations for the design of high-speed and long-distance practical WDM soliton system.     

Chemical degradation of TGDDM/DDS epoxy resin in supercritical 1-propanol: Promotion effect of hydrogenation on thermolysis

Chemical decomposition of an epoxy system made of tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) and 4,4′-diaminodiphenylsulfone (DDS) in supercritical 1-propanol was investigated under different reaction temperature and time. The GC–MS results suggested that the epoxy system was decomposed to the products including aniline, N-propylbenzenamine, and 4,4′-diaminodiphenylsulfone. The change of the products' yield with time was measured by GC. In addition, the formed chars were characterized by SEM, elemental analysis, Raman and XRD. The results implied the presence of some graphite microcrystals and disordered structure in the solid residue. Upon the addition of KOH, the Guerbet reaction of 1-propanol was promoted to generate more hydrogen. A possible free-radical reaction mechanism was proposed for the depolymerization of TGDDM/DDS epoxy resin. Hydrogenation of radicals had a promotion effect on thermolysis of TGDDM/DDS epoxy resin.     

Small-angle X-ray scattering study on the microstructure evolution of zirconia nanoparticles during calcination

Zirconia nanoparticles have been synthesized from zirconium hydroxide precipitates followed by a supercritical CO₂ extraction. The microstructure evolution of these zirconia nanoparticles during the calcination at the moderate temperature has been investigated. Assisted by the analyses of TEM and XRD, small-angle X-ray scattering (SAXS) study offers possibilities to a comprehensive and quantitative characterization of the structural evolution on the nanometer scales. The as-synthesized zirconia sample exhibits a mass fractal structure constructed by the surface fractal particles. Such a structure can be preserved up to 300 °C. After calcination at 400 °C, considerable structural rearrangement occurs. In the interior of nanoparticles zirconia nanocrystallites emerge. It is the scattering from such zirconia nanoparticles that give rise to the broadened crossover in the ln[J(q)] vs. ln q plot and the scattering peak in the ln[q³J(q)] vs. q² plot. With a further increase in the calcination temperature, the power-law region at large-q in ln J(q) vs. ln q plot expands, and the peak in ln[q³J(q)] vs. q² plot shifts towards lower q values, indicating size increases in both the nanocrystallites and nanoparticles. Besides, the mass fractal structure constructed by zirconia nanoparticles can be largely preserved during the moderate temperature calcination.     

Synthesis of high-density nanocavities inside TiO2-B nanoribbons and their enhanced electrochemical lithium storage properties

Single crystalline TiO2-B nanoribbons with high-density nanocavities were successfully synthesized via a simple hydrothermal route. The as-prepared TiO2-B nanoribbons exhibited a large Brunauer, Emmett, and Teller (BET) surface area of about 305 m(2)/g because of the high-density nanocavities inside the thin nanoribbons. Electrochemical measurements indicated that the TiO2-B nanoribbons with dense nanocavities showed discharge specific capacity higher than those of TiO2-B nanotubes and nanowires. It was found that the dense nanocavities have an important influence on the electrochemical lithium intercalation properties.     

Numerical study of radial temperature distribution in the AlN sublimation growth system

A large radial temperature gradient in the AlN sublimation growth system would lead to non‐uniform growth rate along the radial direction and introduce thermal stress in the as grown crystal. In this paper, we have numerically studied the radial thermal uniformity in the crucible of a AlN sublimation growth system. The temperature difference on the source top surface is insignificant while the radial temperature gradient on the lid surface is too large to be neglected. The simulation results showed that the crucible material with a large thermal conductivity is beneficial to obtain a uniform temperature distribution on the lid surface. Moreover, it was found that the temperature gradient on the lid surface decreases with increased lid thickness and decreased top window size.     

带空洞损伤的古典压力容器问题

本文根据微弹性结构线性理论研究了带空洞损伤的压力容器问题．解答是准静态的，其应力场为古典弹性力学关于球体对称压力容流问题应力解答，位移场和损伤场具有由于考虑损伤而表现出体积粘弹性特点．     

最高阶元个数是4p的有限群

本文证明了如果有限群G恰有4p个最高阶元,p为素数,则群G为可解群,除非G同构于S5.