Borel方向与亚纯函数的唯一性

设f是复平面上的亚纯函数,arg z=θ(0≤θ＜2π)是f的一条Borel方向.如果亚纯函数g和f在包含arg z=θ的角域内IM分担五个不同的值ai∈(C)(i=1,2,3,4,5),则f≡g.     

半导体激光泵浦Nd：YVO4激光器的1.34μm输出特性

报道了半导体激光泵浦Ｎｄ：ＹＶＯ４激光器在１．３４μｍ的输出特性，当入射的泵浦光功率为５１５ｍＷ时，最大１．３４μｍ激光输出功率达１５７ｍＷ，光－光转换效率为３０．５％，研究了激光器的纵模特性及弛豫噪声与泵浦功率的关系，发现不同的纵模具有各自不同的弛豫振荡频率。     

不同极性固定相上醇色谱保留指数的预测

采用拓扑指数(mQ)、定位基参数(SOX)及固定液极性值(CP)与脂肪醇在6种固定相上的气相色谱保留指数值(RI)进行了相关分析,发现RI与上述参数间存在良好的相关性,其关系可表示为:RI=158·384 57·7220Q-12·0491Q 5·720SOX 5·756CP R=0·9913继以留一法(Leave-one-out,LOO)进行交互检验,相关系数RCV=0·9909。说明所建定量结构-保留关系(QSRR)模型具有良好的稳定性和预测能力,较好地揭示了脂肪醇类物质在不同固定相上气相色谱保留指数的变化规律。     

Dynamics of triple-flames in ignition of turbulent dual fuel mixture: A direct numerical simulation study

Pilot-ignited dual fuel combustion involves a complex transition between the pilot fuel autoignition and the premixed-like phase of combustion, which is challenging for experimental measurement and numerical modelling, and not sufficiently explored. To further understand the fundamentals of the dual fuel ignition processes, the transient ignition and subsequent flame development in a turbulent dimethyl ether (DME)/methane-air mixing layer under diesel engine-relevant conditions are studied by direct numerical simulations (DNS). Results indicate that combustion is initiated by a two-stage autoignition that involves both low-temperature and high-temperature chemistry. The first stage autoignition is initiated at the stoichiometric mixture, and then the ignition front propagates against the mixture fraction gradient into rich mixtures and eventually forms a diffusively-supported cool flame. The second stage ignition kernels are spatially distributed around the most reactive mixture fraction with a low scalar dissipation rate. Multiple triple flames are established and propagate along the stoichiometric mixture, which is proven to play an essential role in the flame developing process. The edge flames gradually get close to each other with their branches eventually connected. It is the leading lean premixed branch that initiates the steady propagating methane-air flame. The time required for the initiation of steady flame is substantially shorter than the autoignition delay time of the methane-air mixture under the same thermochemical condition. Temporal evolution of the displacement speed at the flame front is also investigated to clarify the propagation characteristics of the combustion waves. Cool flame and propagation of triple flames are also identified in this study, which are novel features of the pilot-ignited dual fuel combustion.     

高功率端面抽运Nd:YVO4固体激光器模匹配的研究

研究了端面抽运Ｎｄ：ＹＶＯ４固体激光器激光晶体内基模半径与抽运光斑半径的匹配。晶体的Ｎｄ掺杂原子数分数分别为０．５％和２％,抽运功率分别为１０Ｗ和１４Ｗ。结果表明：ＴＥＭ００模输出功率对ｗ１／ｗｐａ在低于１的很大范围内的变化不敏感,不存在一个确定的最佳ｗ１／ｗｐａ值;在相对很小的ｗ１／ｗｐａ情形,仍可获得高效单一的ＴＥＭ００模输出,在这种情况下热透镜球差具有限模孔径的作用。     

Output Characteristics of High-Power Continuous Wave Raman Fiber Laser at 1484 nm Using Phosphosilicate Fiber

A continuous wave (CW) high-power Raman fiber laser (RFL) with maximum output power of 2.24 W and slope efficiency of 32.8% at 1484 nm is obtained using a CW 8.4 W/ 1064 nm Yb-doped double-clad fiber laser as a pump, 700 m phosphosilicate fiber, and cascaded cavities with two pairs of fiber Bragg grating mirrors for the first and the second Stokes orders. Theoretical simulation of the RFL using a very efficient and rapidly converging collocation method is done to understand and optimize the fiber length to obtain maximum second Stokes power. RFL performance for the 300, 700 and 1150 m phosphosilicate fiber lengths was experimentally investigated by observing maximum output power, slope efficiency, threshold power, and full-width at half maximum at the second Stokes wavelength.     

36-W diode-pumped continuous-wave 1319-nm Nd:YAG ceramic laser

Continuous-wave output at 1319 nm was obtained from a laser-diode-pumped 1% ceramic Nd:YAG laser. As much as 36.3-W output was obtained under pump power of 290 W, with an optical-to-optical conversion efficiency of 12.5%.