高亮度白光LED用外延片的新进展

文章首先介绍了发光二极管（LED）的内量子效率、外量子效率的基本概念和提高量子效率的基本方法，接着对LED外延的结构和方法做了简要介绍．文章的第三和第四部分则着重介绍了提高内、外量子效率的外延方法，这些方法包括外延结构的优化，侧向外延生长，SiC和GaN衬底的生长，AIInGaN四元系有源区生长，非极性面、半极性面的外延，表面粗化结构生长，图形化二次外延结构．图形化蓝宝石衬底上的外延，提高载流子注入效率的结构和组分设计．文章的第五部分则介绍了基于可靠性和成本考虑的其他新型外延结构，第六部分介绍了提高LED可靠性的外延方法．最后得出结论：采用非极性面的GaN衬底，生长优化的LED结构，并结合光子晶体技术，可望取得突破性进展．     

探针移动速度对等离子体射流热流密度测量结果的影响

采用自行研制的中心嵌有铜柱感应件的小尺寸杆状热流探针,在低扰动条件下,对射入大气环境的纯氩层流等热离子体射流传向铜探头表面的热流密度进行了动态测量.结果表明,在射流最高温度16500 K、最大轴向速度850 m/s、探针垂直于射流流动方向的移动速度130～260 mm/s的实验参数范围内,随着探针移动速度的提高,测得的热流密度值减小;射流温度和速度越高,探针移动速度对热流密度测量值的影响越大.     

层流与湍流等离子体冲击射流特性比较

本文采用数值模拟方法,对层流与湍流氩等离子体射流在空气环境中冲击平板时的流动与传热特性进行了对比研究.结果表明,在平板和射流进口间的距离较大时,平板的存在只对其附近的射流参数分布有较大影响,层流等离子体冲击射流的温度与轴向速度的轴向梯度明显小于湍流等离子体冲击射流情形;由于在平板表面形成的径向壁面射流对引射的附加贡献,层流和湍流等离子体冲击射流对环境空气的引射量明显增加.     

Phase-locking observed among high-order lateral modes of a broad-stripe diode array inside an external cavity

For a laser diode array (LDA) positioned in an external cavity of a certain length, a very strong inter-emitter coupling can be established between the off-axis lateral modes of the broad-stripe emitters. Under these circumstances, the phase-locked operation of the LDA due to couplings between off-axis modes of emitters has been observed, for the first time to our knowledge. The observations suggest that phase locking of a broad-stripe LDA can be achieved among different emitter lateral modes by selecting different cavity lengths.     

10－6—10－4m2/s黏度液体中靶受力学作用的测试与分析

通过自行研制的光纤传感器对不同黏度液体中材料靶后的力学作用进行研究，获得了液体黏度变化对等离子体烧蚀力、射流冲击力及空泡生存周期的影响. 实验结果表明：液体黏度相同时，靶材所受冲击力幅值随作用激光能量的增加单调上升；液体黏度增加时，靶材所受的冲击力减小，靶材的空化空蚀程度亦减小；受液体黏度增大的影响，空泡膨胀或收缩过程减缓，相应的生存周期也增大. 此外，对空泡溃灭周期公式进行修正, 结果表明修正后的理论估算值与实验值的一致性较好.     

Normal tracing deflectometry using a secondary light source

Scanning deflectometric profilers based on an f–gθ system are typical optical tools used to measure mirror profiles at many synchrotron facilities. Unlike these profilers, which are based on a pencil beam, here a secondary light source and a pinhole are used to construct a system that automatically selects a beam that will always pass through the pinhole and propagate along the normal direction of the measured area on the surface under test. By measuring the angle variation of the selected beam, slope variations of the surface under test can be measured. Systematic errors introduced by manufacturing defects or aberrations of an optical element, which greatly degrade the performance of traditional profilers, could be minimized by using the developed method. Simulation values of the proposed method and a conventional method are compared.     

关于电阻率测井中视电阻率概念的合理性

对视电阻率这一电阻率测井中常用的概念进行深入分析,通过理论上的考虑及有关数值算例,探讨视电阻率应该具有的性质及相应概念的合理性.     

Nonlinear analysis of the deformation and breakup of viscous microjets using the method of lines

We present a numerical model for predicting the instability and breakup of viscous microjets of Newtonian fluid. We adopt a one‐dimensional slender‐jet approximation and obtain the equations of motion in the form of a pair of coupled nonlinear partial differential equations (PDEs). We solve these equations using the method of lines, wherein the PDEs are transformed to a system of ordinary differential equations for the nodal values of the jet variables on a uniform staggered grid. We use the model to predict the instability and satellite formation in infinite microthreads of fluid and continuous microjets that emanate from an orifice. For the microthread analysis, we take into account arbitrary initial perturbations of the free‐surface and jet velocity, as well as Marangoni instability that is due to an arbitrary variation in the surface tension. For the continuous nozzle‐driven jet analysis, we take into account arbitrary time‐dependent perturbations of the free‐surface, velocity and/or surface tension as boundary conditions at the nozzle orifice. We validate the model using established computational data, as well as axisymmetric, volume of fluid (VOF) computational fluid dynamic (CFD) simulations. The key advantages of the model are its ease of implementation and speed of computation, which is several orders of magnitude faster than the VOF CFD simulations. The model enables rapid parametric analysis of jet breakup and satellite formation as a function of jet dimensions, modulation parameters, and fluid rheology. Copyright © 2010 John Wiley & Sons, Ltd.     

Jet impingement onto a tapered hole: Influence of jet velocity and hole wall velocities on heat transfer and skin friction

Jet impingement onto a hole with elevated wall temperature can be associated with the high‐temperature thermal drilling, where the gas jet is used for shielding the hole wall from the high‐temperature oxidation reactions as observed in the case of laser drilling. In laser processing, the molten flow from the hole wall occurs; and in the model study, the hole wall velocity resembling the molten flow should be accounted for. In the present study, gas jet impingement onto tapered hole with elevated temperature is considered and the heat transfer rates as well as skin friction at the hole wall surface are predicted. The velocity of molten flow from the hole wall determined from the previous study is adopted in the simulations and the effect of hole wall velocity on the heat transfer rates and skin friction is also examined. It is found that the Nusselt number and skin friction at the hole wall in the regions of hole inlet and exit attain high values. The influence of hole wall velocity on the Nusselt number and skin friction is found not to be very significant. Copyright © 2008 John Wiley & Sons, Ltd.     

Multiple Ligand and Cell-Dependent States of Lateral Mobility of Plasmalemmal G Protein-Coupled Cholecystokinin Receptors

Lateral movement of receptor molecules in the plane of the plasmalemma has important implications for signal transduction and receptor regulation, yet mechanisms affecting such movement are not well understood. We have studied the lateral mobility of the G protein-coupled cholecystokinin (CCK) receptor expressed in the natural milieu of the rat pancreatic acinar cell and in a model cell system, the CHO-CCKR cell, after occupation with fluorescent agonist and antagonist. Lateral diffusion characteristics were distinct in each type of cell and for receptors occupied by each type of ligand, fluorescent agonist, rhodamine-Gly-[(Nle^28,31)CCK-26-33], and fluorescent antagonist, rhodamine-Gly-[(D-Trp³⁰,Nle^28,31)CCK-26-32]-phenethyl ester. Multiple states of mobility were detected for CCK receptors. The slowest population of mobile receptors on the CHO-CCKR cells moved at similar rates when occupied by both antagonist and agonist, while the faster-moving populations moved at a faster rate when occupied with antagonist than with agonist. The fastest component of mobile receptors may reflect unconstrained interactions of the antagonist-occupied receptors with signaling or anchoring structures, while the slowest component may represent the fraction of ligand-occupied receptors that ultimately undergo internalization. The intermediate mobility states may reflect receptor interactions with signal transduction and regulatory machinery. While only a single population of mobile receptors was demonstrable on the acinar cells, increased ligand concentrations (agonist and antagonist) resulted in increased percentages of mobile receptors, suggesting a stoichiometric limitation of immobilizing molecular constraints. Inhibition of protein kinase C had no significant effect on the lateral mobility of agonist-occupied CCK receptors.