高阻恒流LED产生亚泊松光的理论研究

本文研究高阻恒流源驱动的光发射二极管（ＬＥＤ）的输出光场的振幅噪声压缩与电，光量子效率，漏电流效应，泵浦残余噪声频率的关系，指出高阻恒流技术不仅使任意纵模产生振幅噪声压缩，而且由于仅在高阻恒流下各纵模间存在负量子相关，使得ＬＥＤ总输出光场的振幅噪声压缩加深。     

利用腔内量子电动力学效应改变钕玻璃微球荧光谱特性的研究

报道腔内量子电动力学效应对钕玻璃微球荧光谱的影响；分析了光谱中量子电动力学结构的相对强度，同时估算了自发辐射速率的量子电动力学增强。实验证实增强辐度超过１６倍。     

Global existence and analyticity of solution for the generalized Hall-magnetohydrodynamics system

We investigate the global existence and analyticity of mild solution to the three-dimensional generalized Hall-magnetohydrodynamics (MHD) system in this work. We prove the global existence and analyticity of solutions in the corresponding critical spaces. The work extends global existence and analyticity of solutions to Hall-MHD system in Duan and MHD system in Wang and Ye and Zhao, to the generalized Hall-MHD system with 1/2 ≤ α,β ≤ 1.     

Quantile regression for linear models with autoregressive errors using EM algorithm

In this paper, we consider the quantile linear regression models with autoregressive errors. By incorporating the expectation–maximization algorithm into the considered model, the iterative weighted least square estimators for quantile regression parameters and autoregressive parameters are derived. Finally, the proposed procedure is illustrated by simulations and a real data example.     

Joint modeling for mixed-effects quantile regression of longitudinal data with detection limits and covariates measured with error,with application to AIDS studies

It is very common in AIDS studies that response variable (e.g., HIV viral load) may be subject to censoring due to detection limits while covariates (e.g., CD4 cell count) may be measured with error. Failure to take censoring in response variable and measurement errors in covariates into account may introduce substantial bias in estimation and thus lead to unreliable inference. Moreover, with non-normal and/or heteroskedastic data, traditional mean regression models are not robust to tail reactions. In this case, one may find it attractive to estimate extreme causal relationship of covariates to a dependent variable, which can be suitably studied in quantile regression framework. In this paper, we consider joint inference of mixed-effects quantile regression model with right-censored responses and errors in covariates. The inverse censoring probability weighted method and the orthogonal regression method are combined to reduce the biases of estimation caused by censored data and measurement errors. Under some regularity conditions, the consistence and asymptotic normality of estimators are derived. Finally, some simulation studies are implemented and a HIV/AIDS clinical data set is analyzed to to illustrate the proposed procedure.     

Linear stability and Hopf bifurcation in a delayed two-coupled oscillator with excitatory-to-inhibitory connection

We consider the dynamical behavior of a delayed two-coupled oscillator with excitatory-to-inhibitory connection. Some parameter regions are given for linear stability, absolute synchronization, and Hopf bifurcations by using the theory of functional differential equations. Conditions ensuring the stability and direction of the Hopf bifurcation are determined by applying the normal form theory and the center manifold theorem. We also investigate the spatio-temporal patterns of bifurcating periodic oscillations by using the symmetric bifurcation theory of delay differential equations combined with representation theory of Lie groups. Finally, numerical simulations are given to illustrate the results obtained.     

A porous medium equation with nonlocal boundary condition and a localized source

This article studies the blow-up properties of solutions to a porous medium equation with nonlocal boundary condition and a general localized source. Conditions for the existence of global or blow-up solutions are obtained. Moreover, it is proved that the unique solution has global blow-up property whenever blow-up occurs. Blow-up rate estimates are also obtained for some special cases.     

Preparation of TiO2-carbon surface composites with high photoactivity by supercritical pretreatment and sol-gel processing

TiO₂-carbon surface (TCS) composites were prepared by pretreatment of a sealing substrate in supercritical carbon dioxide using paraffin as a plugging agent, and sol-gel processing using tetrabutyl orthotitanate as a precursor. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectrum (XPS), optical absorption spectroscopy and nitrogen absorption. The photoactivity of TCS was checked by monitoring the decomposition of methylene blue (MB) in aqueous solution under UV irradiation. The results indicated that compared with TC prepared only by the sol-gel method, the small nanosize TiO₂ particles are well dispersed on carbon surface with large amount of micropores and high Eg values, meanwhile TCS have high Ti³⁺ concentration due to supercritical pretreatment providing a amount of carbon on the composite surface with interfacial energy effects, which controls the growth of TiO₂ nanoparticles, baffles the agglomeration of TiO₂ nanoparticles and easily produces Ti³⁺ ions. These are reasons why TCS has a higher efficiency of decomposing MB than TiO₂-carbon (TC) composites and pure TiO₂. Additional, it is also attributed to the fact that TCS produce a high concentration of organic compounds near TiO₂ in comparison with TC and pure TiO₂, because their surface area are greater than that of TC and pure TiO₂.     

间二甲苯分子在不同外电场下结构和解离特性研究

间二甲苯是挥发性有机物(VOCs, Volatile Organic Compounds)的关键活性成分,研究其在外电场下的性质十分重要.采用密度泛函理论(DFT),在B3LYP/6-311G++基组水平上对间二甲苯分子进行优化,从分子结构研究了不同外电场(-0.025 a.u.～0.025 a.u.)作用下,间二甲苯分子的总能量,键长,电偶极矩,前线轨道,红外光谱和解离势能面.计算结果表明,沿两甲基中C原子连线方向的电场(-0.025 a.u.～0.025 a.u.)增加时,分子总能量和能隙先增大后减小,电偶极矩先减小后增加.通过计算发现外电场对间二甲苯分子不同键长和不同振动模式的红外光谱的影响均有所不同.间二甲苯分子的解离特性表现为:沿两甲基中C原子连线方向施加强度超过0.047 a. u.的电场时,位于电场增加方向的甲基与苯环之间起连接作用的C-C键断裂.以上计算结果可为利用电场降解间二甲苯提供重要理论参考.     

Significant evaluation of three factors affecting the pre-curing behavior of urea formaldehyde resin: temperature,solid content,and pH

Journal of Thermal Analysis and Calorimetry - In order to evaluate the significant effects of curing temperature, solid content, and pH on the pre-curing behavior of the UF resin, the isothermal...