SB6键合机工艺腔净化过程的软件改进(英文)

分子泵是高真空系统的核心部件,通过对SB6键合机真空系统和分子泵特性的分析,总结讨论了3个可能导致分子泵损坏的键合工艺过程,最后,提出对工艺腔净化过程的一个软件改进办法,这个改进的思路对从事半导体设备维修的专业人员而言是有一定帮助的。

ARX-NNPLS Model Based Optimization Strategy and Its Application in Polymer Grade Transition Process

Since it is often difficult to build differential algebraic equations (DAEs) for chemical processes, a new data-based modeling approach is proposed using ARX (AutoRegressive with eXogenous inputs) combined with neural network under partial least squares framework (ARX-NNPLS), in which less specific knowledge of the process is required but the input and output data. To represent the dynamic and nonlinear behavior of the process, the ARX combined with neural network is used in the partial least squares (PLS) inner model between input and output latent variables. In the proposed dynamic optimization strategy based on the ARX-NNPLS model, neither parameterization nor iterative solving process for DAEs is needed as the ARX-NNPLS model gives a proper representation for the dynamic behavior of the process, and the computing time is greatly reduced compared to conventional control vector parameterization method. To demonstrate the ARX-NNPLS model based optimization strategy, the polyethylene grade transition in gas phase fluidized-bed reactor is taken into account. The optimization results show that the final optimal trajectory of quality index determined by the new approach moves faster to the target values and the computing time is much less.

Direct Numerical Simulation of Particle Dispersion in Gas-Solid Compressible Turbulent Jets

A numerical method was developed to directly simulate the compressible, particle-laden turbulent jets.The fourth order compact finite difference schemes were used to discretize the space derivatives. The Lagrangian method was adopted to simulate the particle motion based on one-way coupling. It is found that the turbulent intensity profiles attain self-similar status in the jet downstream regions. At the Stokes number of 1, particles are concentrated largely in the outer boundaries of the large-scale vortex structures with the most uneven distribution and the widest dispersion in the lateral direction. Particles at the much smaller Stokes numbers are distributed evenly in the flow field, and the lateral dispersion is also considerable. Distribution of particles at much larger Stokes numbers is more uniform and the lateral dispersion becomes small. In addition, the inflow conditions have different effects on the particle dispersion. The direct numerical simulation (DNS) results accord with the previous experiments and numerical studies.

Growth of Semi-Insulating GaN Using N2 as Nucleation Layer Carrier Gas Combining with an Optimized Annealing Time

Semi-insulating （SI） GaN is grown using N2 as the nucleation layer （NL） carrier gas combined with an optimized annealing time by metalorganic chemical vapour deposition. Influence of using 1-12 and N2 as the NL carrier gas is investigated in our experiment. It is found that the sheet resistance of unintentionally doped GaN can be increased from 10^4 Ω/sq to 10^10 Ω/sq by changing the NL carrier gas from 1-12 to N2 while keeping the other growth parameters to be constant, however crystal quality and roughness of the tilm are degraded unambiguously. This situation can be improved by optimizing the NL annealing time. The high resistance of GaN grown on NL using N2 as the carrier gas is due to higher density of threading dislocations caused by the higher density of nucleation islands and small statistic diameter grain compared to the one using 1-12 as carrier gas. Annealing the NL for an optimized annealing time can decrease the density of threading dislocation and improve the tilm roughness and interface of AlGaN/GaN without degrading the sheet resistance of as-grown GaN signiticantly. High-quality SI GaN is grown after optimizing the annealing time, and AlGaN/GaN high electron mobility transistors are also prepared.

Combustion characteristics of Methanol-base fuel （MBF） made by coal

Profound experimental research was made on Methanol-base fuel （MBF） mainly consisting of methanol, and the results were compared with that of diesel oil. Their respective combustion characteristics of caloric value, combustion efficiency and components of smoke were synthetically analyzed by employing the electronic weighing devices, the rotor flow-meter, intelligent flue gas analyzer, advanced bomb calorimeter, etc., referring to the feasibility of taking it as a fuel for general use. Experiment results show that Methanol-base fuel not only has superiorities on combustion characteristics but also bears energy saving and environmental protection advantages.

Prediction of Thermophoretic Deposition Efficiency of Particles in a Laminar Gas Flow along a Concentric Annulus： A Comparison of Developing and Fully Developed Flows

Thermophoresis is an important mechanism of micro-particle transport due to temperature gradients in the surrounding medium.It has numerous applications,especially in the field of aerosol technology.This study has numerically investigated the thermophoretic deposition efficiency of particles in a laminar gas flow in a concentric annulus using the critical trajectory method.The governing equations are the momentum and energy equations for the gas and the particle equations of motion.The effects of the annulus size,particle diameter,the ratio of inner to outer radius of tube and wall temperature on the deposition efficiency were studied for both developing and fully-developed flows.Simulation results suggest that thermophoretic deposition increases by increasing thermal gradient,deposition distance,and the ratio of inner to outer radius,but decreases with increasing particle size.It has been found that by taking into account the effect of developing flow at the entrance region,higher deposition efficiency was obtained,than fully developed flow.

Invasive house geckos （hemidactylus spp.）： their current, potential and future distribution

In this study, we identified the current distribution of five globally distributed invasive Hemidactylus species and predicted their potential and future distribution using species distribution models based on climate and elevation data. These species included H. brookii, H. frenatus, H. garnotii, FI. mabouia, and H. turcicus. We show that many regions with tropical and Mediterranean climates are suitable for most of these species. However, their current and potential distributions sug- gest that climate is not the only limiting factor. We hypothesize that climatic conditions may affect competition and other interactions resulting in a segregated distribution of the studied Hemidactylus species. As an effect of global climate change it is likely that H. brookiiwill expand its range to areas that are currently colonized by H. mabouia and/or H. frenatus, while H. turcicus is likely to expand its range to areas that are not yet invaded by any Hemidactylus species. The role of species interactions in the range expansion of these five Hemidactylus species still remains poorly understood, but could be of major importance in understanding and managing these invasive species.