Passively Q-switched single-frequency output from a diffusion-bonded monolithic Nd:YAG non-planar ring oscillator

A compact monolithic Nd:YAG non-planar ring laser with diffusion-bonded Cr4+:YAG is demonstrated,and high stable pulsed single-frequency laser at 1.06 μm is realized.Theoretical analysis and simulation results of pulsed laser parameters are illustrated.14.96-kW maximum peak power,pulse-width of 4.8 ns is achieved for single-frequency operation.     

Global holomorphic 2-forms and pluricanonical systems on threefolds

The change of zero locus of a global holomorphic 2-form on a threefold under birational transformations is investigated. It is proved that existence of 2-forms with certain conditions on their zero loci on a threefold of nonnegative Kodaira dimension limits types of terminal singularities appearing on its minimal models. As a result of the restriction on the types of terminal singularities and Reid's Riemann-Roch formula, a universal bound N is found such that the linear system NK defines a birational map from a threefold of general type admitting those 2-forms, where K is the canonical bundle of the threefold. Received March 10, 2000 / Published online October 11, 2000     

Reactive blue 19 adsorption behaviors of magnesium hydroxide modified biochar derived from the traditional Chinese medical residual

This study examined the reactive blue 19 (RB-19) adsorption behaviors of magnesium hydroxide modified biochar (MBC) derived from the traditional Chinese medical residual. The obtained MBC was characterized using Scanning Electron Microscope (SEM), Fourier Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). The static adsorption experiment was carried out to investigate the adsorption properties. The results indicated that pH 4 was best for the adsorption removal of RB-19 in the pH range of 4–9. Compared with the pseudo-first-order model and Elovich model, the pseudo-second-order equation was best to describe the adsorption process (R² > 0.995). The Langmuir model was better than the Freundlich model to fit the experimental data (R² > 0.990). The intra-particle diffusion model showed that film diffusion and intra-particle diffusion were involved in the adsorption process. Thermodynamic parameters showed that the RB-19 adsorption by MBC was spontaneous and endothermic. The adsorption mechanism might include electrostatic interaction, pore filling, and hydrogen bond, and the MBC was a promising adsorbent.     

基于法布里-珀罗干涉仪的瑞利散射测速技术研究

基于法布里-珀罗干涉仪的干涉瑞利散射测速技术原理,结合种子注入Nd∶YAG脉冲激光器、ICCD相机和高光谱分辨法布里-珀罗干涉仪,建立了一套干涉瑞利散射速度测量系统,系统的速度测量准确度为10m/s.对拉瓦尔喷管产生的超声速自由射流开展干涉瑞利散射速度测量,得到气流的流动速度为366m/s.在不需要外加任何示踪粒子的条件下,利用流场气体分子本身的瑞利散射,实现了对超声速流场速度的非接触测量.     

宝石能谱CT对胃癌区域淋巴结转移的诊断价值

目的 研究宝石能谱CT（gemstone spectral CT,GSCT）对胃癌区域淋巴结转移的诊断价值。方法 回顾分析52例胃镜下组织学活检证实为胃癌并行GSCT（GSCT 组,24 例）或双源CT（dual source CT,DSCT）（DSCT 组,28 例）的患者,两组除常规CT增强检查外,GSCT在动脉期应用能谱成像GSI（gemstone spectral imaging）软件,获得区域转移淋巴结与胃癌病变的能谱衰减曲线,对比分析两组CT结果与术后病理结果符合率及GSCT 对转移淋巴结评估的准确性。结果 通过计算淋巴结大小、CT 值差值及短长径比值的方法,GSCT 组评估淋巴结转移与病理符合率高于DSCT 组（P＜0.05）;胃癌及转移淋巴结能谱分析结果无统计学差异（P≥0.05）。结论 GSCT 检查胃癌区域淋巴结转移与病理结果的一致性高于DSCT;GSCT可对胃癌术前转移淋巴结进行详细判断,并对术前评估提供了理论依据和技术支持,具有重要的临床应用价值。     

Freestanding midinfrared negative-index metamaterials with sandwich configuration perforated with square arrays of holes

Metamaterials with large-scale freestanding Ag-SU-8-Ag sandwich configuration, perforated with a square periodic array of circular holes, are fabricated. The transmittance spectra of both experiment and simulation have shown the existence of two transmittance peaks in the middle-infrared region. Numerical simulations based on the effective media method and the effective parameter retrieval procedure verify that the low-frequency transmittance peak results from the electric and the magnetic resonance associated with the negative refractive index. The influence of dielectric loss of the interlayer on transmission and negative refractive response is discussed. Numerical simulations indicate that the transmission within the negative refractive index region decreases, while the dielectric loss of interlayer increase, mainly due to the enhanced reflection. Moreover, the electric resonance mode further increases the absorption resulted from the dielectric loss of interlayer.     

O (3P) + H2 → OH+H反应的立体动力学研究

用BMS1势能面[Brandão 等, J.Chem.Phys. 121, 8861 (2004)],选取碰撞能为34.6kcal/mol,用准经典轨线方法研究了O ( ) + 反应的立体动力学性质。计算并讨论了k与j'的夹角的分布关系P ( )以及描述k-k'- j'三者关系的二面角分布。（k为反应物速度方向,k'为产物的速度方向,j'为产物的角动量方向） 的峰值在90°附近并且关于90°呈对称性分布,这表明产物角动量的方向与初速度的方向垂直。二面角分布P( )关于散射平面呈反对称性分布,这一结果表明产物的角动量具有强烈的极化效应。另外,我们还研究了振动激发对产物角动量的影响,结果表明产物的矢量性质对反应物的初始振动态非常敏感。     

Laguerre calculus and Paneitz operator on the Heisenberg group

Laguerre calculus is a powerful tool for harmonic analysis on the Heisenberg group. Many sub-elliptic partial differential operators can be inverted by Laguerre calculus. In this article, we use Laguerre calculus to find explicit kernels of the fundamental solution for the Paneitz operator and its heat equation. The Paneitz operator which plays an important role in CR geometry can be written as follows:

具有性能约束的三维布局优化模型的主要性质

本文研究了简化的旋转卫星舱内的三维布局优化问题,建立了一个具有性能约束的三维布局优化模型,给出了其主要性质,并证明了性能目标函数为局部Lipschitz连续函数,且其局部最优解即为全局最优解.