内部演化网络分析

分析了Barabasi-Albert(BA)无标度网络内部演化加边对网络结构的影响,考虑了线性和非线性择优连接．基于扩展的率方程方法,考虑引入新节点和内部加边引起的网络中已有节点的度的变化率,得到了度分布的精确表达式．当择优连接为线性时,度分布服从幂律;对于亚线性择优连接,度分布呈拉伸的指数分布形式．对于超线性择优连接,边的两端都择优连接会出现几乎与网络中其他所有节点都相连的“凝胶”节点．     

Tm,Ho声光调Q激光系统理论与实验研究

利用激光速率方程理论,对Tm,Ho激光系统计算预测得出最佳耦合输出透过率和调Q激光脉冲宽度.实验采用Tm, Ho:LuLF为增益介质,三向侧面泵浦,环形腔声光调Q.选用透过率20%和30%的输出镜作对比.在透过率20%耦合输出时,得到调Q激光脉冲能量最大为58.0 mJ,对应光光转换效率为1.45%;在透过率30%耦合输出时,得到调Q激光脉冲能量最大为62.9 mJ,对应光光转换效率1.57%,并且获得了最大动静比48.7%.激光脉冲宽度在注入能量3.25 J时为417.2 ns.与理论计算结果较为一致.     

矿物均相酸催化剂催化甲醇和乙酸酯化反应动力学(英文)

In this work, esterification of acetic acid and methanol to synthesize methyl acetate in a batch stirred reactor is studied in the temperature range of 305.15–333.15 K. Sulfuric acid is used as the homogeneous catalyst with concentrations ranging from 0.0633 mol·L?1 to 0.3268 mol·L?1. The feed molar ratio of acetic acid to methanol is varied from 1:1 to 1:4. The influences of temperature, catalyst concentration and reactant concentration on the reaction rate are investigated. A second order kinetic rate equation is used to correlate the experimental data. The forward and backward reaction rate constants and activation energies are determined from the Arrhenius plot. The developed kinetic model is compared with the models in literature. The developed kinetic equation is useful for the simulation of reactive distillation column for the synthesis of methyl acetate.     

放大自发辐射对全固态激光器调Q性能的影响

为定量分析放大自发辐射(ASE)对调Q激光器性能的影响,在调Q激光速率方程中引入放大自发辐射项,并在合理的近似下求解,给出了激光二极管(LD)端面抽运电光调Q运转的固体激光器反转粒子数的建立过程,分析了放大自发辐射对激光上能级储能效率的影响及考虑放大自发辐射时调Q激光器输出脉冲宽度和脉冲能量随抽运功率的变化关系。结果表明,由于放大自发辐射的存在,上能级储能效率降低,且在一定的抽运功率下,调Q输出脉冲宽度变宽,脉冲能量下降。用LGS(La3Ga5SiO14)晶体作电光调Q元件,在激光二极管抽运的Nd∶YVO4激光器上进行了实验,实验结果与理论分析结果基本吻合。     

Anomalous luminescence efficiency enhancement of short-term aged GaN-based blue light-emitting diodes

The origin of anomalous luminescence efficiency enhancement of short-term aged GaN-based blue light-emitting diodes was studied. We found that the intensity of the electroluminescence and photoluminescence spectra were both increased in the very beginning period of aging. With the help of a rate-equation model, we concluded that this kind of luminescence efficiency enhancement is a joint effect of the defect reduction in active layers and the changes out of active layers, for example the Mg acceptor annealing.     

Kinetics of esterification of methanol and acetic acid with mineral homogeneous acid catalyst

In this work, esterification of acetic acid and methanol to synthesize methyl acetate in a batch stirred reactor is studied in the temperature range of 305.15–333.15 K. Sulfuric acid is used as the hom...     

LD泵浦Nd:YAG 946nm与1319nm双波长运转理论分析

本文由准三能级和四能级的阈值条件出发,分析了抑制1064nm激光起振的最低镀膜要求,并且利用速率方程理论和两激光的输出特性曲线对泵浦功率为10W时946nm和1319nm双波长的条件进行数值分析和计算,分析表明在泵浦功率为10W、946nm激光的透过率为3%时,为了使两谱线腔内光子数密度相等,对于1319nm激光的透过率应为8%左右,这时两激光的输出功率分别为0.35W和0.6W。本文为等光子数双波长运转提供了一种相应的分析方法,并且提出了RGB激光器的设计方案。     

垂直腔面发射激光器的特性分析

主要用数值方法分析了垂直腔面发射半导体激光器的基本特性.利用贝塞尔函数和傅里叶展开,把描述半导体激光器光子数与载流子浓度变化与空间位置有关的速率方程转化为与空间位置无关的方程,进而利用龙库塔法求解方程,确定激光器在不同电流注入下的光输出特性以及温度,电极尺寸对输出特性的影响.     

一种带温度参量的半导体激光器速率方程及仿真求解

研究并求解了热效应条件下的半导体激光器的速率方程。在经典速率方程的基础上,通过引入热效应特性,得到了带温度参量修正的速率方程组,然后利用Simulink软件工具,对该非线性微分方程进行仿真求解,最后以某分布反馈激光器的参量为例,得到了不同偏置点、不同调制信号及不同温度条件下速率方程的瞬态解,并据此分析了弛豫振荡、频率啁啾等特性。仿真求解结果符合该型激光器的瞬态特性,为该型激光器设计制造和应用选型提供了一定的参考。