High-Temperature Stability of 650-nm Resonant-Cavity Light-Emitting Diodes Fabricated Using Wafer-Bonding Technique on Silicon Substrates

AlGalnP-based visible 650-nm GalnP-AlGalnP resonant-cavity light-emitting diodes (RCLEDs) with high-temperature stability were fabricated by wafer-bonding techniques on Si substrates. In this study, the metal-bonding RCLEDs (MBRCLEDs) devices were designed with 84-mum apertures for light output. The MBRCLEDs with a maximum wall-plug efficiency of 13.7% were demonstrated at an injection current of 2.5 mA. In addition, the improved heat sinking of MBRCLEDs led to lower junction temperature, and resulted in a very low power decay of 0.31 dB from room temperature to 100degC at an injection current of 20 mA.     

A Micromirror With Large Static Rotation and Vertical Actuation

A micromirror with large rotation angle and vertical displacement is proposed and developed. The proposed micromirror is actuated by newly developed prestress comb drive actuators, which exhibit no pull-in, no hysteresis, and large vertical displacement range characteristics. The micromirror was fabricated using commercially available PolyMUMPs. Experimental results indicated that the maximum rotation angle and vertical displacement of the device are 26 and 45 mum, respectively     

Stability bound of discrete multiple time-delay singularly perturbed systems

In this paper, the exact stability bound for discrete multiple time-delay singularly perturbed systems is examined. The obtained results, based on state space approach for the critical stability criterion of discrete systems, are sufficient conditions for the original system and its reduced subsystems about stability problems. Besides, we show that the subsystems are, indeed, zero-order approximations to the original systems. An example is given to illustrate the proposed schemes.     

基于OpenGL的新型水雷三维仿真训练系统

为克服我国新型水雷开展训练面临的困难,介绍了采用Visual C++及OpenGL构建某型水雷三维仿真训练系统的方法和过程.重点阐述了如何在OpenGL开发环境中实现对三维模型的交互控制.训练系统的建立证明了方法的可行性.     

Improved three-point formulas considering the interface conditionsin the finite-difference analysis of step-index optical devices

A general relation, considering the interface conditions, between a sampled point and its nearby points is derived. Making use of the derived relation and the generalized Douglas scheme, the three point formulas in the finite-difference modeling of step-index optical devices are extended to fourth order accuracy irrespective of the existence of the step-index interfaces. With numerical analysis and numerical assessment, several frequently used formulas are investigated     

Effect of algal extracellular polymer substances on UF membrane fouling

Low-pressure membrane processes, such as ultrafiltration (UF), are effective for treating algae-laden eutrophic source waters. However, fouling caused by algae excreted organics can be a major obstacle to the smooth operation of membrane processes. In this study, three algae species, with a similar cell size and shape, but a different amount of extracellular polymeric substances (EPS), were selected. The characteristics of the bound EPS, including its amount and constituents, mainly polysaccharide and protein, were analyzed. Cell suspensions were filtered through a dead-end stirred cell with a regenerated cellulose UF membrane. Based on the observations of permeate flux decline at higher transmembrane pressure (TMP) and critical flux values, it can be concluded that algae cell EPS do affect membrane fouling, and the constituents of EPS may also play a role.     

The preparation of PLZT ceramics from a sol-gel process

Sol-gel process is employed to prepare PLZT ceramic with the composition 9/56/44 (La/Zr/Ti). Complete crystallization of the sol-gel derived powders is achieved after 600°, 1 hr. calcination. The sintered density of the PLZT pellet decreases as the sintering time increases. A ninety-nine percent theoretical density is obtained for samples sintered at 1250° for one hour. The dielectric properties and optical transmission of the sol-gel derived samples are measured and compared with those of the hot-pressed PLZT ceramics reported in the literature. Sol-gel derived powders, when properly sintered, possess sufficient optical transparency for optoelectrical device applications.     

Thermal and electrical stability of ZnO varistors with glass additives

Glasses in the PbO-B₂O₃-Al₂O₃-BaO-CaO-SiO₂ system were employed as the dopant to ZnO varistors. The thermal stability of the varistor is enhanced with glass additives. The temperature coefficient of threshold field for the sample doped with 1 w/o glass (65 w/o PbO - 23 w/o B₂O₃ - 12 w/o SiO₂) is 1 × 10^-4/K as compared to 3.3 × 10^-3/K for that of the undoped sample. The change in the temperature dependence of the field-current density characteristics is more related to the barrier height change than the refractory behavior of the glass employed. Heat treatment is very effective in recovering the degraded samples by providing the activation energy for the diffusion of Zn interstitials. The experimental results can be explained with a Schottky barrier model.