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991.
992.
Dong-Hun Ryu 《International Journal of Computational Fluid Dynamics》2013,27(9):611-620
High heat capacity and constant operation temperature make a 2-phase heat remover tool promising for solving high heat dissipation problems in MEMS devices. However, microscale analysis of the flow with the conventional Navier–Stokes equation is inadequate, because the non-continuum effect is important when the characteristic dimension is comparable to the local mean free path. DSMC is a direct, particle-based numerical simulation method that uses no continuum assumption. In this paper, the gas–liquid boundary effects in microchannel flow are studied using this method. Modified DSMC code is used to simulate low-speed flow—under which viscous heating produces no significant temperature change—and MD results are incorporated into the DSMC boundary condition. Steady Couette flow simulation results show that the gas–liquid boundary affects the density distribution and the temperature dependence of the slip velocity. Unsteady simulation results show that mass transfer by diffusion is faster than momentum transfer by collision. 相似文献
993.
本文报导了采用氩离子激光器来泵浦Rr ̄(3+):YLF晶体,应用声光调制器实现了主动锁模;同时应用振动─高反射平面镜也实现了被动锁模,两种锁模均得到了ps光脉冲。据作者了解这是这种晶体材料的第一次锁模运转。 相似文献
994.
We establish optimal gradient estimates in Orlicz space for a nonhomogeneous elliptic equation of higher order with discontinuous coefficients on a nonsmooth domain. Our assumption is that for each point and for each sufficiently small scale the coefficients have small mean oscillation and the boundary of the domain is sufficiently close to a hyperplane. As a consequence we prove the classical Wm,p, m=1,2,…, 1<p<∞, estimates for such a higher order equation. Our results easily extend to higher order elliptic and parabolic systems. 相似文献
995.
We have synthesized an amphiphilic triblock coil-rod-coil molecule consisting of a rigid aromatic building block and poly(ethylene oxide). The coil-rod-coil molecule was observed to assemble into a cylindrical micelle structure in aqueous solution. Notably, addition of a small amount of a rod-coil-rod molecule into the cylindrical micellar solution can induce the anisotropic gelation due to dynamic interconnection of adjacent cylindrical micelles via hydrophobic and pi-pi interactions. Depending on the concentration of the rod-coil-rod molecule, the nematic gel can be reversibly switched into an isotropic solution of cylindrical micelles. 相似文献
996.
Ryu I Kreimerman S Araki F Nishitani S Oderaotoshi Y Minakata S Komatsu M 《Journal of the American Chemical Society》2002,124(15):3812-3813
Cascade reactions of 4-alkenyl iodides, involving a carbonylation-cyclization-carbonylation sequence, were accomplished by a hnu/Pd system. The stereochemical outcomes suggest that radical carbonylation and subsequent acyl radical cyclization may be involved in this reaction. 相似文献
997.
998.
Mee-Yi Ryu E KuokstisC.Q Chen J.W YangG Simin M Asif KhanG.G Sim P.W Yu 《Solid State Communications》2003,126(6):329-332
A comparative combined study of photoluminescence (PL), PL kinetics, stimulated emission (SE) and photoreflectance (PR) properties in InxGa1−xN epilayers is carried out in the composition range 0≤x≤0.19. In-incorporation up to 4% leads to the sufficient longer radiative recombination decay time due to the decrease in non-radiative recombination channels, which are peculiar to GaN, and band-to-band optical transitions predominate the spontaneous PL spectrum. Further In-incorporation (x>4%) leads to the localization of carriers and/or excitons at band-tails in the In-rich areas. Correlation between the position of dominant low-energy PR oscillation due to the main band gap and SE peak position shows that band-to-band transitions are responsible for lasing and dominate the PL spectrum in all highly pumped InxGa1−xN samples. 相似文献
999.
Both electrical and optical activation studies of Si-implanted Al0.18Ga0.82N have been made as a function of anneal time and anneal temperature to obtain maximum possible electrical activation efficiency. Silicon ions were implanted at 200 keV with doses of 5×1014 and 1×1015 cm−2, and the samples were annealed from 1100 to 1250 °C for 5-25 min with a 500 Å thick AlN cap in a nitrogen environment. The electrical activation efficiency and Hall mobility increase with anneal time and anneal temperature. Nearly 100 and 95% electrical activation efficiencies were obtained for Si-implanted Al0.18Ga0.82N with doses of 5×1014 and 1×1015 cm−2 and annealing at 1250 and 1200 °C for 25 min, respectively. The photoluminescence measurements show an excellent implantation damage recovery after annealing at these optimum anneal conditions, showing a strong near band emission. These optical results correlate well with the electrical results. 相似文献
1000.
Kimun Ryu 《Journal of Mathematical Analysis and Applications》2003,283(1):46-65
In this paper, we discuss the existence of positive solutions to certain nonlinear elliptic systems representing competitive interaction with self-cross diffusions between two species. The method employed is the fixed point index theory in a positive cone. Sufficient conditions for the existence of positive solutions are provided. 相似文献