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891.
Well-adhered alumina washcoats on FeCrAl metallic supports were prepared using boehmite sols and alumina slurries. The microstructure and the surface performance of the washcoat/support were investigated by SEM, XRD, and ultrasonic vibration. The effects of the main preparative parameters on the coating adherence were studied. The optimal coating conditions are presented as follows: pre-oxidation of the metallic supports was performed at 900 °C for 10 h, the sol layer loadings were 2.0-6.6 wt.%, and the slurry layer loadings were less than 25.3 wt.%. The sol layer drying was performed at 30 °C for 1 h and that for the slurry layer the drying was performed at 120 °C for 2 h, and the coating calcining was performed at 900 °C for 2 h. The SEM photographs of coated samples show that alumina washcoats were well deposited on the metallic supports. 相似文献
892.
In this Letter, a hyperchaotic Lorenz system is constructed via state feedback control. Abundant dynamics of the hyperchaotic system is studied using the Lyapunov exponents, Poincaré section and bifurcation diagram. Furthermore, effective linear feedback controllers are designed for stabilizing hyperchaos to unstable equilibrium, periodic orbits and quasi-periodic orbit. Numerical simulations are given to illustrate and verify the results. 相似文献
893.
894.
The wettability of calcite cubes was tuned by varying the sizes of the polystyrene nanoparticles attached to their surfaces via a dispersion polymerization. The products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersion spectrum (EDS) and Fourier transformation infrared spectrum (FTIR). The results showed that the hydrophobicity of the calcite cubes was enhanced with the increase of the size of the polystyrene nanoparticles attached. Using polystyrene nanoparticle-attached calcite cubes (PNACC) as emulsifiers, stable water-in-tricaprylin Pickering emulsions were produced. By gelling the water droplets of the Pickering emulsions, the hierarchical structures of polystyrene nanoparticle-attached calcite cube-armored microspheres were obtained. The polystyrene nanoparticle-attached calcite cubes were expected to have novel surface properties similar neither to traditional Pickering particles, nor to macroscopically asymmetrical Janus particles. 相似文献
895.
The influence of fiber dispersion on the code form of the optical mm-wave signal generated by single sideband intensity-modulation 总被引:2,自引:0,他引:2
We have theoretically investigated the transmission performance of the optical mm-wave generation by using an external modulator based on single sideband (SSB) intensity modulation. Though the SSB millimeter (mm)-wave can immune the fading effect, the baseband signals with a high bit rate are degraded greatly after transmission along fiber. The main reason is that the fiber dispersion causes the time shift of the code edges; therefore the maximum transmission distance of the baseband signals is limited. The experimental and simulation results agree well with our theoretical analysis. We also propose a novel scheme to extend the transmission distance. In this novel scheme, the data signals are modulated only onto one of the two optical carriers; hence the shift of the code edges in the down-converted signals after transmission is eliminated. 相似文献
896.
In this paper, we consider the nonlinear Schrödinger equation with variable coefficients, and by using direct transformation of variables and functions, the explicit chirped gray one- and two-soliton solutions are presented. Based on the exact solutions, we in detail analyze the propagation characteristics of the chirped gray soliton, including the stability against either the deviation from integrable condition or the initial perturbation, and interaction between the chirped gray solitons. The results show that the gray soliton can be compressed by choosing the appropriate initial chirp, and the chirped gray pulses can stably propagate along optical fibers remaining the character of solitons. 相似文献
897.
Jian-Feng Jia 《Applied Surface Science》2007,253(10):4485-4489
Ab initio molecular orbital theory was used to examine the hydrogenation of a B12N12 molecule. The 1,2 addition of the 4,6 bond is an energetically favorable adsorption site in one-hydrogen-molecule adsorption. We found that the averaged bind energy of hydrogen molecule is maximized in B12N12H12. The largest energy gaps of B12N12H12 and B12N12H24 suggest they have special stability. Moreover, calculation of the Gibbs free energy of the B12N12 + 12H2 → B12N12H24 reaction showed that this reaction becomes endothermic above 320 K. 相似文献
898.
The dynamic single-mode and modulation performance of λ/4 phase-shifted distributed feedback laser diode with chirped grating (QWS-CG-DFB) are analyzed theoretically. The numerical simulation shows that, in contrast to purely QWS-DFB laser, the enhanced dynamic single-mode suppression ratio (SMSR) can be reached by QWS-CG-DFB laser. Under the smaller biasing current, the modulation band-width in presence of chirped grating is narrower, this difference shrinks for larger biasing current. For large signal modulation, the chirped grating is helpful to increase the output extinction ratio, but worsens the frequency chirping. The good dynamic characteristic can be obtained by selecting system parameters reasonably. 相似文献
899.
Tianqing Jia Motoyoshi Baba Fuli Zhao Xiaojun Wu Masayuki Suzuki Zhizhan Xu 《Solid State Communications》2007,141(11):635-638
We present a simple route for ZnSe nanowire growth in the ablation crater on a ZnSe crystal surface. The crystal wafer, which was horizontally dipped in pure water, was irradiated by femtosecond laser pulses. No furnace, vacuum chamber or any metal catalyst were used in this experiment. The size of the nanowires is about 1-3 μm long and 50-150 nm in diameter. The growth rate is 1-3 μm/s, which is much higher than that achieved with molecular-beam epitaxy and chemical vapor deposition methods. Our discovery reveals a rapid and simple way to grow nanowires on designed micro-patterns, which may have potential applications in microscopic optoelectronics. 相似文献
900.
Linxiang He Jun Yu Weiming Yang Jia Li Bin Yang Yunbo Wang 《Solid State Communications》2007,142(8):472-476
Ferroelectric Pb0.84La0.16Ti0.96O3/Pb0.96La0.04(Zr0.52Ti0.48)0.99O3/Pb0.84La0.16Ti0.96O3 (PLT/PLZT/PLT) structures were fabricated on platinum-coated silicon wafers by RF magnetron sputtering. A Pb0.84La0.16Ti0.96O3 layer was used as a seed layer to improve the crystallization and enhance the ferroelectric properties of the PLZT film. With the PLT seed layers, the films showed excellent ferroelectric properties in terms of large remnant polarization (2Pr) of 52.7 μC/cm2, lower coercive field (2Ec) of 130 kV/cm for an applied field of 500 kV/cm. Moreover, the PLT/PLZT/PLT structures exhibited good fatigue endurance after 1010 switching cycles, which was attributed to the double-sided PLT layers. They improved the electrical fatigue by eliminating the pyrochlore phase, reduced the strong (111) orientation, and assimilated the oxygen vacancies from the PLZT layer. 相似文献