铟封稳频He－Ne激光器

稳频Ｈｅ－Ｎｅ激光器中布氏窗片的封接引起的各向异性损耗，是影响激光输出功率的主要因素。采用先进的铟封接技术，可以大大改善稳频管的窗口封接质量，从而减小了腔的损耗，明显地提高了稳频Ｈｅ－Ｎｅ激光器的输出功率。     

Computations of shear driven vortex flow in a cylindrical cavity using a modified k-ε turbulence model

In this paper, a new variant of the k-ε turbulence model (Saqr et al., CFD Letters, 1(2) pp. 87–94) is used to compute the shear driven vortex flow in an open cylindrical cavity. The results are compared with published LDA measurements for such flow configuration. The modified turbulence model demonstrated good agreement with experimental results, which further supports its validity in computing vortex dominated flows.     

Direct simulations of spherical particle motion in Bingham liquids

The present work deals with the development of a direct simulation strategy for solving the motion of spherical particles in a Bingham liquid. The simulating strategy is based on a lattice-Boltzmann flow solver and the dual-viscosity Bingham model. Validation of the strategy is first performed for single phase (lid-driven cavity flow) and then for two phase flows. Lid-driven cavity flow results illustrate the flow's response to an increase of the yield stress. We show how the settling velocity of a single sphere sedimenting in a Bingham liquid is influenced by the yield stress of the liquid. The hydrodynamic interactions between two spheres are studied at low and moderate Reynolds number. At low Reynolds number, two spheres settle with equal velocity. At moderate Reynolds number, the yield effects are softened and the trailing sphere approaches the leading sphere until collision occurs.     

Dental Chatter: Bacterial Cross-Talk in the Biofilm of the Oral Cavity

Dental biofilms are composed of hundreds of bacterial species. These biofilms are diverse biological structures due to the heterogeneity of the many different types of supports in the oral cavity. The bacteria immobilized in these biofilms are exposed to rapid environmental changes such as pH, temperature, nutrition and anti-plaque agents. One mode in which these bacteria adapt in the dental biofilm is by quorum sensing. This cell-cell communication regulates diverse sets of adhesion modes, physiological changes, virulence properties, allowing the bacteria to persist in the dental biofilm under rapid environmental changes. In this review, we will concentrate mostly on the cariogenic bacterium Streptococcus mutans as one of the pivotal microorganisms in the supra-gingival biofilm that plays a major role in dental caries.     

超短环形腔布里渊掺铒光纤激光器

提出了一种超短环形腔布里渊掺铒光纤激光器(BEFL),腔长仅为10m。该BEFL以4m长的普通掺铒光纤(EDF)为激光增益介质,腔外布里渊抽运光和980nm抽运光的注入在掺铒光纤中,分别引入非线性布里渊增益和线性掺铒光纤放大器(EDFA)增益。实验结果表明,BEFL工作在单纵模状态,输出信噪比高(>40dB),抽运阈值低(～20mW),输出功率大(>10mW),且布里渊抽运光不仅决定BEFL的输出波长,更对其抽运阈值和出光功率有重要影响。     

用于光通信的可调谐激光光源

随着高速大容量光通信系统的迅猛发展 ,可调谐激光光源在 DWDM中的应用将越来越重要。文中介绍了近年来应用于光通信领域的一些可调谐激光光源 ,对不同结构的可调谐激光器进行了初步的分析比较 ,并对国外已出现的一些比较成熟的可调谐激光器产品做了一些简要的介绍。     

迷宫密封中可压流体流场的数值模拟

应用Fluent软件计算迷宫密封间隙宽度和空腔深度以及直通式迷宫密封和错列式迷宫密封对迷宫密封流场和泄漏量的影响。计算结果与分析表明,间隙宽度对泄漏量的影响体现在通过改变空腔进出口面积来改变泄漏量。所以泄漏量随间隙宽度呈线性变化。在实际运用中,在保证安全的情况下尽量减小间隙宽度;在一定条件下,空腔深度越大,紊流程度下降,泄漏量越大;错列式迷宫密封的泄漏量要明显小于直通式迷宫密封。     

Correction of single‐beam sample absorption error in a hemispherical 45°/0° spectrophotometer measurement cavity

A mathematical model for quantifying single‐beam sample absorption error in a hemispherical 45°/0° measurement cavity is derived and tested by measuring diffuse reflectance standards with a prototype visible‐range spectrophotometer. A methodology is described for using this three‐parameter model to correct for sample absorption error in any single‐beam spectrophotometer. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 436–441, 2014     

基于CAE的注射模型腔尺寸补偿计算

提出了一种基于模拟的注射模型腔尺寸补偿计算方法。通过对塑件的结构进行功能分析,构造塑件的几何特征模型。并以Moldflow为CAE平台,对塑件进行收缩和翘曲模拟。依据采集的模拟数据进行分析,得出注射模的型腔尺寸补偿方案,用于指导型腔尺寸的修整。提高了塑件的尺寸精度和形位精度,改善了型腔几何模型与塑件设计模型之间的关系,提高了塑件的质量。     

Incompressible laminar flow over a three-dimensional rectangular cavity

IntroductionMany aerodynandc configurations include cavities asan integral part of design, manufactUre and performance.Examples of such configurations include landing-gearwells, bomb bays and junctions between surfaces, to namea few. Cavity phenomena can also be observed on a muchlarger scale, for example, around the channel gates orharbor entrances [l][2]. Flow past a cavity is oftencharacterized by unsteady velocity and density, andfurthermore by unsteady pressure fluctuation (oftenreferred…