Miner累积损伤理论的试验验证和统计分析

本文通过对LY12-CZ铝合金板材光滑试件和中心孔试件的常幅加载和变幅加载疲劳试验,对Miner累积损伤理论进行了试验验证,并对累积周比的分散性作了统计分析,发现累积周比的分散性服从Weibull分布,因此本文提出以最小累积周比值或以与一定存活率相应的累积周比值进行安全寿命估计的观点。

表面曲率对边界层的影响与边界层外缘附近的连结问题

利用一种严格的边界層外缘条件重新计算了不可压縮非粘性流体繞二維曲面的运动,求出曲度对表面剪力与速度剖面的影响。墨菲曾首次研究此題,其结果与本文的結果比較,在質与量上均有出入,因此說明如何准确連結边界層与势流对此类問題的重要性。 結果还表明凸面曲度使表面剪应力較平面的剪应力小,也使边界層內的速度比平面的小。反之,凹面曲度使表面剪应力較平面的大,也使边界層的速度比平面的大。又曲度对表面剪应力的影响小,对速度剖面影响大。

矿场评价注水井伤害程度的试井方法

注水井试井是评价注水层伤害程度的有效手段。通过压力落差试井，可以测得注水井停注后压力随时间的变化，所得压力与时间关系的资料通过应用注水井不稳定试井解释方法，可以求得注水井的表皮因子，并通过表皮因子分析判断注水井伤害的主要原因。建立了试井评价模型，确定了压力落差试井表皮因子，现场应用后可以指出注水井伤害的程度和主要原因。

岩石破裂滑动过程及其声发射数值模拟

运用岩石破裂与失稳过程分析RFPA2D系统 ,对滑动形成过程进行了数值模拟研究。滑动岩体似为非均匀弹 -脆岩石材料 ,模拟结果再现了滑动形成从变形到破坏直至失稳的全过程及其声发射规律。结果表明 ,剪断面是滑动形成的主要形式 ,并首先在试样一端出现 ,然后再形成由一端及里的剪断面扩展直至另一端最后产生剪断面破坏贯通 ,形成统一的滑动面

Absolute phase control of spectra effects in a two-level medium driven by two-color ultrashort laser pulses

Using a omega-3 omega combination scenario, we investigate the absolute phase control of the spectra effects for ultrashort laser pulses propagating in a two-level medium. It is found that the higher spectral components can be controlled by the absolute phases. In particular, different absolute phase combinations can lead to the buildup or split of the even harmonics. (c) 2006 Elsevier B.V. All rights reserved.

双掺杂LiNbO3：Fe：Mn晶体局域光折变体全息光栅形成及衍射特性

将带输运模型与二维耦合波理论相结合，研究了双掺杂LiNbO3：Fe：Mn晶体中由两束有限宽度平面波干涉产生的局域光折变体全息的动力学机制及其衍射特性。采用三步法联立求解了双中心带输运物质波方程和二维耦合波方程。数值计算结果表明，局域光折变体全息光栅的空间电荷场在空间上呈不均匀分布。当光栅区域较小时空间电荷场较强，随着光栅区域的增大，空间电荷场急剧下降，并降低一个数量级。此外，在接近光束入射边界的区域，空间电荷场时空变化规律与一维无限大光折变体全息光栅的结果相似，随着光栅区域的扩大，边界效应对空间电荷场的影

Simulation of an apodizer's effect for high-density optical storage

The effect of an apodizer with two parallel taper refractive surfaces is theoretically investigated for high-density optical storage. The apodizer may modulate an incident Gaussian beam into an annular beam. Simulation shows that with the increasing inner radius of the modulated beam, the focal spot shrinks obviously. The depolarization effect gets strong simultaneously, which induces the circular symmetry loss of the focal spot. In this process, pattern density of the orthogonal and longitudinal diffractive fields increases remarkably.

Structural and upconversion fluorescence properties of Er3+/Yb3+-codoped oxychloride lead-germanium-bismuth glass

Structural and infrared-to-visible upconversion fluorescence properties of Er3+/Yb3+-codoped oxychloride lead-germanium-bismuth glass have been studied. The Raman spectrum investigation indicates that PbCl2 plays an important role in the formation of glass network, and has an important influence on the upconversion luminescence owing to lower phonon energy. Intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions H-2(11/2)-->I-4(15/2,) I-4(3/2)-->I-4(15/2), and F-4(9/2)-->I-4(15/2), respectively, were observed at room temperature. The quadratic dependence of the 525, 546, and 657 nm emissions on excitation power indicates that a two-photon absorption process occurs under 975 nm excitation. (C) 2004 Elsevier Ltd. All rights reserved.