[en] A new kind of SILO (sealed interface local oxidation of silicon) processing for VLSI isolation has been explored. In this SILO process, an LPCVD Si₃N₄ film (about 50 nm) is deposited directly onto the silicon surface. Then N₂⁺ ions are implanted into the Si₃N₄ film. This N₂⁺ ion implantation can not only effectively reduce the tensile stress of the Si₃N₄ film, but also mix the native SiO₂ between silicon and the Si₃N₄ film. SEM results show that the birds' beak is greatly reduced by choosing proper implanting energy. The stress of the Si₃N₄ film is studied by the flatness measurement using Canon 500 laser scanning flatness measuring equipment and the Si/Si₃N₄ interface properties are analysed by AES.MOSFETs using the SILO process have also been fabricated. (author)

[en] Hydrogen bonding interaction between alcohols and water molecules is an important characteristic in the aqueous solutions of alcohols. In this paper, a series of molecular dynamics simulations have been performed to investigate the aqueous solutions of low molecular weight alcohols (methanol, ethylene glycol and glycerol) at the concentrations covering a broad range from 1 to 90 mol %. The work focuses on studying the effect of the alcohols molecules on the hydrogen bonding of water molecules in binary mixtures. By analyzing the hydrogen bonding ability of the hydroxyl (-OH) groups for the three alcohols, it is found that the hydroxyl group of methanol prefers to form more hydrogen bonds than that of ethylene glycol and glycerol due to the intra-and intermolecular effects. It is also shown that concentration has significant effect on the ability of alcohol molecule to hydrogen bond water molecules. Understanding the hydrogen bonding characteristics of the aqueous solutions is helpful to reveal the cryoprotective mechanisms of methanol, ethylene glycol and glycerol in aqueous solutions

[en] Highlights: • The bubble departure diameter is proportional to g^−0.425 in quiescent fluid. • The bubble release frequency is proportional to g^0.678 in quiescent fluid. • The simulation result supports the transient micro-convection model. • The bubble departure diameter has exponential relation with inlet velocity. • The bubble release frequency has linear relation with inlet velocity. -- Abstract: Nucleate boiling flows on a horizontal plate are studied in this paper by a hybrid lattice Boltzmann method, where both quiescent and slowly flowing ambient are concerned. The process of a single bubble growth on and departure from the superheated wall is simulated. The simulation result supports the transient micro-convection model. The bubble departure diameter and the release frequency are investigated from the simulation result. It is found that the bubble departure diameter and the release frequency are proportional to g^−0.425 and g^0.678 in quiescent fluid, respectively, where g is the gravitational acceleration. Nucleate boiling in slowly flowing ambient is also calculated in consideration of forced convection. It is presented that the bubble departure diameter and the release frequency have exponential relationship and linear relationship with inlet velocity in slowly flowing fluid, respectively

[en] Highlights: • A thermal LBM-LES model in body-fitted coordinate system is established. • Heat transfer around a circular cylinder is modeled in a wide Reynolds number range. • The effects of Reynolds number and Prandtl number on heat transfer are revealed. -- Abstract: In order to apply the lattice Boltzmann method (LBM) for modeling passive heat transfer at high Reynolds numbers, a number of models were proposed by introducing the large eddy simulation (LES) into the LBM framework to improve numerical stability. Our study finds that the generalized form of interpolation-supplemented LBM (GILBM), likewise, can locally modify the dimensionless relaxation time, thus enhancing the numerical stability at high Reynolds numbers. Given additional advantages of the GILBM in dealing with complicated geometries and improving computing accuracy, a thermal LBM-LES model in body-fitted coordinates is established in this paper. Numerical validation is performed by investigating the flow and heat transfer around a circular cylinder over a wide range of Reynolds numbers. The obtained results agree well with both experimental and numerical data in the previous work. Meanwhile, the effects of Reynolds number and Prandtl number on thermodynamic features of flow past a circular cylinder are revealed. It is found out that when the Reynolds number exceeds the critical value, the local Nusselt number fluctuates rapidly in a specific region of the rear cylinder surface affected by the Prandtl number. In the near-wake region, the temperature field exhibits significant dependence on the Prandtl number at moderate Reynolds numbers, while such effects turn to be slight at high Reynolds numbers.

[en] Highlights: • The wetting boundary condition is derived and validated for the phase transition LBM model used in present work. • The dynamic behavior and phase transition process during droplet impacting upon the inclined surface has been simulated. • Three influence factors, including droplet impacting angle, surface wettability and Weber number, are analyzed to explore their effects on the thermodynamic and hydrodynamic behavior of droplet. - Abstract: In the current work, the impacting process of a saturated fuel droplet on an inclined blade surface in superheated gas is simulated by the lattice Boltzmann method (LBM). Firstly, wetting boundary condition is derived for the phase transition LBM model, and then it is validated by calculating static contact angle of a droplet on partial wetting solid wall. Next, the dynamic behavior and phase transition of the droplet during its impacting process are analyzed on the basis of impacting angle, surface wettability, and Weber number. The results indicate that both deformation and evaporation of the droplet are enhanced by these three factors. Furthermore, the influence of impacting angle on droplet velocity is more obvious than that of other factors.

[en] In order to investigate the effect of different mixing forms and pressure variations on the spray characteristics of the air-blast atomizer, in terms of two air-blast atomizers with different mixing forms, a series of experiments was conducted by using the laser induced fluorescence (LIF) and particle image velocimetry (PIV) system. The effects of liquid pressure and air pressure on the spray angle and velocity field were studied and analysed, respectively. The fluids used in the experiments were air and aviation kerosene. The results indicate that the spray angle and particles velocity are not sensitive to the liquid pressure for both atomizers, but significantly affected by the air pressure. Specifically, the spray angle of the atomizer A increases firstly and then decreases with the increase of the air pressure. For the atomizer B, at the initial stage, the spray angle increases continuously and finally it maintains a stable value. Under a constant liquid pressure, the velocity of the particles of the atomizer A increases obviously with the air pressure. For the atomizer B, as air pressure increases, the particles velocity increases and some vortices have been formed. The research demonstrates that under the same condition, the mixing mode of the atomizer B can make the mixture of air and liquid more uniformly with better spray characteristics

[en] Highlights: • The characteristic of hydrate decomposition at 274 K was numerical analyzed. • Ice generation during hydrate decomposition was investigated. • The effect of ice generation and initial hydrate saturation on pressure, temperature, permeability was obtained. • The influence factors and features of the cumulative gas production and the instantaneous gas generation rate are analyzed. As a potential new source of energy, gas hydrate has been the focus of research around the world. In this study, based on a summary of existing models, a one-dimensional mathematical model containing four phases (water, gas, hydrate, and ice phases) and three constituents (water, gas, hydrate) based on the finite difference method (FDM) was established for analysing methane hydrate decomposition at a relatively low temperature condition (approximately 274 K) by depressurization in porous media. This model can be used to investigate gas hydrate exploitation under a wider range of temperatures (e.g., deep seabed or permafrost conditions). When the initial temperature of the hydrate reservoir is approximately 274 K, ice generation occurs during exploitation. This investigation focused on the characteristics of hydrate decomposition, ice generation and ice distribution by changing the parameters of relevant settings. The analysis addressed the effects of ice generation on pressure, temperature, permeability, and cumulative gas production; the influence of other relevant parameters on each other; the influential factors and features of cumulative gas production and the instantaneous gas generation rate. The results showed that ice generation gradually increases during the hydrate decomposition process and occurs early and near the production well due to a large pressure gradient. As an unfavourable factor, ice generation causes the absolute permeability, instantaneous gas generation rate and local pressure to decline. The production well pressure is the determinant of ice generation. Moreover, the final cumulative gas production is determined by the hydrate characteristics, which include the hydrate saturation, reservoir porosity and permeability. Ice generation reduces the gas generation rate, but this does not affect the final cumulative gas production.