四氢呋喃族燃料层流燃烧特性的实验研究

为探究高温高压条件下四氢呋喃族燃料的层流燃烧过程,利用高速摄影和纹影技术的定容燃烧弹实验,采用非线性外推方法,获得了四氢呋喃(THF)、2-甲基四氢呋喃(MTHF)、2,5-二甲基四氢呋喃(DMTHF)在初始压力为0.1～0.4MPa、初始温度为373～453K及当量比为0.7～1.6下的层流燃烧特性。结果表明:3种燃料的层流燃烧速率随初始温度升高而增大,随初始压力增大而减小,随当量比增加先增大后减小,峰值出现在当量比为1.1附近,三者层流燃烧速率的关系为S_u,THF>S_u,MTHF>S_u,DMTHF;三者速率的差异主要是由于绝热火焰温度关系为T_ad,THF>T_ad,MTHF>T_ad,DMTHF、热扩散率关系为D_th,THF≈D_th,MTHF>D_th,DMTHF所致。定量分析表明:层流燃烧速率与初始温度之间呈正指数幂函数关系,与初始压力呈负指数幂函数关系,三者中...     

考试数据统计与质量分析程序化研究

阐述了考试数据统计与质量分析应遵循的原则和方法，并编制了UCDOS3.1汉字系统下处理试卷的计算机程序，为正确评价各门课程的测试性能提供了科学依据。     

Characteristics of Nd:YGG Laser Operating at 4F3/2-4I9/2

The laser properties of the Nd：YGG crystal are investigated. The absorption spectrum from 500 to 90Onto and emission spectrum from 850 to 1400nm of Nd：YGG are measured. As much as 1.35 W output power of fundamental laser operating at 935 and 938nm with a slope efficiency of 15.7% and 105mW output power of frequency doubled blue laser are successfully obtained.     

大功率LD脉冲泵浦Nd:YAG蓝光激光器研究

采用大功率LD脉冲运转泵浦Nd：YAG,以消除连续运转时产生的热效应的影响,采用LBO腔内倍频获得高效蓝光输出。实验比较了不同脉冲占空比及不同脉宽时激光的输出特性,对脉冲泵浦减小热效应进行了研究。在未采取特殊致冷,泵光与腔模不匹配的情况下,在占空比为1：3,泵浦功率为7．2W时,获得239mW的473nm蓝光输出,光-光转换效率达到3.3％。     

汽车二维图像的分类识别研究

用自相关函数提取图像的特征,对三类小汽车模型的侧影进行了分类识别研究．给出了两种分类识别方法：加权ｋ－近邻分类法和ＢＰ网络分类法,并对两种分类方法的性能进行了分析．实验结果说明,识别效果较好     

高密度氙气的原子间相互作用与状态方程

从原子间相互作用出发,提出收缩因子的新概念,并利用它提出了适用于高密度气体的状态方程,系统地计算了氙气在临界区的等温压缩线.在缺乏实验数据的情况下,这些理论计算结果对实验有一定指导意义.     

Generation of 170-fs Laser Pulses at 1053nm by a Passively Mode-Locked Yb:YAG Laser

A novel method is developed to obtain 1.05μm laser operation with a Yb：YAG laser. By using a Yb：YAG crystal with proper length and doping concentration, a femtosecond Yb： YAG laser is realized at the central wavelength of 1053nm. The measured pulse duration and spectral bandwidth （FWHM） are 170fs and 7nm; the repetition rate is 80 MHz. Under a power pump of 2 W, an average mode-locking power of 180mW is achieved.     

A 12.1-W SESAM mode-locked Yb:YAG thin disk laser

Pumped by a 940 nm fiber-coupled diode laser, a passively mode-locked Yb:YAG thin disk oscillator was demonstrated with a semiconductor saturable absorber mirror(SESAM). 12.1 W mode-locked pulses were obtained with pulse duration of 698 fs at the repetition rate of 57.43 MHz. Measurement showed that the beam quality was close to the diffraction limit.