808 nm 抽运的Ho3+，Tm3+及Er3+掺杂的氟磷酸盐 玻璃的2.0 μm 光谱性质研究

2.0 μm spectroscopic properties of Er³⁺/Tm³⁺/Ho³⁺ triply-doped fluorophosphate glasses pumped by 808 nm and the energy transfer mechanisms between the three rare earth ions were investigated. J-O theory was used to calculate the parameters of Ho³⁺ in fluorophosphate glasses. Absorption and emission cross-sections and the gain coefficients were calculated. The obtained lifetime r and spontaneous transition probability Ar of Ho³⁺:⁵I7 level were 10.64 ms and 93.95 s^-1 respectively. The calculated maximum emission cross-section of 2.0 μm was 9.26×10^-21 cm². The energy transfer analysis indicated that the cross-relaxation of Tm³⁺ was important and the resonent energy transfer in Er³⁺&rarrHo³⁺, Tm³⁺&rarrHo³⁺, Er³⁺&rarrTm³⁺&rarrHo³⁺ process was the main channel. The study revealed that the Er³⁺/Tm³⁺/Ho³⁺ triply-doped fluorophosphate glass would be a potential material for 2.0 μm emission because of the efficient sensitization of Er³⁺ and Tm³⁺ to Ho³⁺.

S-808为浮选剂的磷矿尾矿水对鱼类的亚致死效应的研究

<正> 磷矿浮选剂S-808是我国新开发的一种浮选剂.对此作者曾进行了鱼类和胚胎的毒性试验.鉴定结果表明该浮选剂的毒性为“毒级”.鱼的胚胎毒性试验发现,即使在较低的浓度情况下,仍发现有致畸现象.但经浮选工艺流程操作后排出的废水,其毒性有明显的降低.那么长期作用于水生生物,

磷矿浮选剂S-808及其尾矿水对鱼类和胚胎的毒性

<正> S-808是我国选矿科技工作者研制的一种新型磷矿浮选剂。湖北省荆襄磷矿矿务局王集矿,在选矿过程中采用S-808作为抑制剂直接浮选中低品位钙质磷块岩,获得特殊的选矿效果。为此化工部矿山局委托我们开展磷矿浮选剂S-808对鱼类的毒性和毒理学的研究。

808 nm high-power laser grown by MBE through the control of Be diffusion and use of superlattice

808 nm high-power laser diodes are gown by MBE. In the laser structure, the combination of Si-doped GRIN (graded-index) region adjacent to n-AlGaAs cladding layer with reduced Be doping concentration near the active region has been used to diminish Be diffusion and oxygen incorporation. As compared with the laser structure which has undoped GRIN region and uniform doping concentration for Si and Be, respectively, in the cladding layers, the slope efficiency has increased by about 8%. Typical threshold current density of 300 A/cm(2) and the minimum threshold current density of 220 A/cm(2) for lasers with 500 mu m cavity length are obtained. A high slope efficiency of 1.3 W/A for coated lasers with 1000 mu m cavity length is also demonstrated, Recorded CW output power at room temperature has reached 2.3 W.

808-nm fiber coupled module with a CW output power up to 130 W

A fiber coupled module is fabricated with integrating the emitting light from four laser diode bars into multimode fiber bundle. The continuous wave (CW) output power of the module is about 130 W with a coupling efficiency of around 80%. The output power is very stable after the temperature cycling and vibration test. No apparent power decrease has been observed as the device working continuously for 500 h.

准连续17 kW 808 nm GaAs/AlGaAs叠层激光二极管列阵

高功率激光二极管列阵广泛应用于抽运固体激光器.报道了17 kW GaAs/AlGaAs叠层激光二极管列阵的设计、制作过程和测试结果.为了提高器件的输出功率,一方面采用宽波导量子阱外延结构,降低腔面光功率密度,提高单个激光条的输出功率,通过金属有机物化学气相沉积(MOCVD)方法进行材料生长,经过光刻、金属化、镀膜等工艺制备1 cm激光条,填充密度为80%,单个激光条输出功率达100 W以上;另一方面器件采用高密度叠层封装结构,提高器件的总输出功率,实现了160个激光条叠层封装,条间距0.5 mm.经测试,器件输出功率达17kW,峰值波长为807.6 nm,谱线宽度为4.9 nm.

贺兰山过去196年降水的树轮宽度重建及降水变率

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氧等离子体硫化法制作可变形聚二甲基硅氧烷薄膜培养基底

发展了氧等离子体硫化法制作可变形聚二甲基硅氧烷薄膜培养基底的技术。与传统的加热硫化法相比，该法制作的基底表面具有亲水性，细胞的粘附、铺展以及基底皱褶变形的发展均非常迅速。此外，观察了细胞松弛素D处理过程中基底皱褶的变化，结果表明这种技术具有较高的时间分辨率。

Numerical Investigation On Detonation Cell Evolution In A Channel With Area-Changing Cross Section

The two-dimensional cellular detonation propagating in a channel with area-changing cross section was numerically simulated with the dispersion-controlled dissipative scheme and a detailed chemical reaction model. Effects of the flow expansion and compression on the cellular detonation cell were investigated to illustrate the mechanism of the transverse wave development and the cellular detonation cell evolution. By examining gas composition variations behind the leading shock, the chemical reaction rate, the reaction zone length, and thermodynamic parameters, two kinds of the abnormal detonation waves were identified. To explore their development mechanism, chemical reactions, reflected shocks and rarefaction waves were discussed, which interact with each other and affect the cellular detonation in different ways.

The Head-On Colliding Process Of Binary Liquid Droplets At Low Velocity: High-Speed Photography Experiments And Modeling

The experimental and theoretical studies are reported in this paper for the head-on collisions of a liquid droplet with another of the same fluid resting on a solid substrate. The droplet on the hydrophobic polydimethylsiloxane (PDMS) substrate remains in a shape of an approximately spherical segment and is isometric to an incoming droplet. The colliding process of the binary droplets was recorded with high-speed photography. Head-on collisions saw four different types of response in our experiments: complete rebound, coalescence, partial rebound With conglutination, and coalescence accompanied by conglutination. For a complete rebound, both droplets exhibited remarkable elasticity and the contact time of the two colliding droplets was found to be in the range of 10-20 ms. With both droplets approximately considered as elastic bodies, Hertz contact theory was introduced to estimate the contact time for the complete rebound case. The estimated result Was found to be on the same order of magnitude as the experimental data, which indicates that the present model is reasonable. (C) 2008 Elsevier Inc. All rights reserved.

Scaling Functions In Conical Indentation Of Elastic-Plastic Solids

The finite element method was used to simulate the conical indentation of elastic-plastic solids with work hardening. The ratio of the initial yield strength to the Young's modulus Y/E ranged from 0 to 0.02. Based on the calculation results, two sets of scaling functions for non-dimensional hardness H/K and indenter penetration h are presented in the paper, which have closed simple mathematical form and can be used easily for engineering application. Using the present scaling functions, indentation hardness and indentation loading curves can be easily obtained for a given set of material properties. Meanwhile one can use these scaling functions to obtain material parameters by an instrumented indentation load-displacement curve for loading and unloading if Young's modulus E and Poisson's ratio nu are known.

含圆形弹性夹杂的反平面问题

运用复变函数技术,求出了无限弹性平面含不同弹性材料的圆形夹杂,在反平面剪切和反平面集中力作用下,应力和位移场的封闭形式解,并由此得出相应的界面应力公式。

蜂蜡球锥的驻点烧蚀研究

<正> 1.引言 飞行器再入大气层时受热情况严重,表面要发生严重的烧蚀,外形要发生显著的变化,驻点的烧蚀更为严重。这一烧蚀过程能否由蜂蜡这种低温液态层材料在高超音速风洞中再现,能否通过对蜂蜡球锥的驻点烧蚀研究为液态层材料的烧蚀图象形成机理和发展规律提供依据,为两相流问题的理论研究提供实验资料,这便是我们进行蜂蜡球锥驻点烧蚀研究的目的。