Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>GaN films grown on (111) Si substrate with different lattice parameter of AlN buffer layer by metal organic chemical vapor deposition (MOCVD) have been studied. Stress state obtained by different test methods were compared and it is found that the lattice parameter of AlN buffer layer may have a remarkable effect on stress state in the initial stage of subsequent GaN film growth. A larger compressive stress is beneficial to improve surface morphology and the crystal quality of GaN film. The result of further orthogonal experiment shows that an important factor affecting lattice pa-rameter is the growth rate of AlN buffer layer. This work may be promising for realizing simple structure of GaN-on-Si and thus reducing the cost of growth processes.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>P2-type layered oxides have been considered as promising cathode materials for Na-ion batteries, but the capacity decay resulting from the Na<jats:sup>+</jats:sup>/vacancy ordering and phase transformation limits their future large-scale applications. Herein, the impact of Li-doping in different layers on the structure and electrochemical performance of P2-type Na<jats:sub>0.7</jats:sub>Ni<jats:sub>0.35</jats:sub>Mn<jats:sub>0.65</jats:sub>O<jats:sub>2</jats:sub> is investigated. It can be found that Li ions successfully enter both the Na and transition metal layers. The strategy of Li-doping can improve the cycling stability and rate capability of P2-type layered oxides, which promotes the development of high-performance Na-ion batteries.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Microstructure evolution and hardening effect of pure tungsten and W-1.5%ZrO<jats:sub>2</jats:sub> alloy under carbon ion irradiation were investigated using transmission electron microscopy and nano-indentation. Carbon ion irradiation was performed at 700 °C with irradiation damages ranging from 1.0 dpa to 8.0 dpa. The results showed that the irradiation defect clusters were mainly in the forms of dislocation loops. The size and density of dislocation loops increased with increasing irradiation damages. W-1.5%ZrO<jats:sub>2</jats:sub> alloy had smaller dislocation loop size in comparison to that of pure tungsten. It was proposed that the phase boundaries had the ability to absorb and annihilate defects and the addition of ZrO<jats:sub>2</jats:sub> phase improves the sink strength for irradiation defects. It is confirmed that the W-1.5%ZrO<jats:sub>2</jats:sub> alloy shows a smaller change in hardness than that of pure tungsten after irradiation. From the above results, we conclude that the addition of ZrO<jats:sub>2</jats:sub> in tungsten can significantly reduce the accumulation of irradiated defects and improve the irradiation resistance behavior of the tungsten materials.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have proved that the chemical reaction induced by femtosecond laser filament in the atmosphere produces CO, HCN and NO, and the production CO and HCN were observed for the first time. The concentrations of the products were measured by mid-infrared tunable laser absorption spectroscopy. In reduced pressure air, the decomposition of CO<jats:sub>2</jats:sub> was enhanced by vibration excitation induced by laser filament, resulting in enhanced production of CO and HCN. At the same time, the generated CO and HCN from the atmosphere suffered rotation excitation induced by laser filament, enhancing their absorption spectra. We found NO, CO, and HCN accumulating to 134 ppm, 80 ppm, and 1.6 ppm in sealed air after sufficient reaction time. The atmospheric chemical reaction induced by laser filament opens up a way to change the air composition while maintaining environmental benefits.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Atmospheric effects have significant influence on the performance of a free-space optical continuous variable quantum key distribution (CVQKD) system. In this paper, we investigate how the transmittance, excess noise and interruption probability caused by atmospheric effects affect the secret-key rate (SKR) of the CVQKD. Three signal wavelengths, two weather conditions, two detection schemes, and two types of attack are considered in our investigation. An expression aims at calculating the interruption probability is proposed based on the Kolmogorov spectrum model. The results show that a signal using long working wavelength can propagate much further than that of using short wavelength. Moreover, as the wavelength increases, the influence of interruption probability on the SKR becomes more significant, especially within a certain transmission distance. Therefore, interruption probability must be considered for CVQKD using long-signal wavelengths. Furthermore, different detection schemes used by the receiver will result in different transmission distances when subjected to individual attacks and collective attacks, respectively.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Radial basis function network (RBF) has excellent generalization ability and approximation accuracy when parameters set properly.However, relying only on traditional methods,it is tough to obtain optimal network's parameters and construct a stabile model as well.In view of this,RBF-MLP neural network is proposed in this article.In the form of connecting two networks to work cooperatively,the RBF's parameter can be adjusted adaptively by the structure of multi-layer perceptron (MLP) so as to realize the effect of backpropagation updating error. Furthermore, genetic algorithm is used to optimize the network's hidden layer so as to confirm the optimal neurons (basis function) number automatically. In addition, a memristive circuit model is proposed to realize the neural network's operation mentioned above based on the character of spin memristors. It is verified that the network can adaptively construct a network model with outstanding robustness and stably achieve 98.33% accuracy in processing the MNIST dataset classification task. The experimental results show that the method mention above has application value.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Since air leakage is inevitable when earmuffs are worn improperly or together with safety glasses in factory or military, it is required to be considered to accurately predict earmuff attenuation. Besides unwanted air leakage, under controlled air leakage is introduced to earmuff to achieve adjustable attenuation in different signal to noise ratio (SNR) and balance between attenuation and speech intelligibility. This work aimed to develop an improved lumped parameter model (LPM) to predict earmuff attenuation considering of air leakage. Air leakage paths were introduced into conventional LPM without air leakage, and air leakage path impedance was analytically described by Maa’s microperforated tube impedance. Earmuff passive attenuation behavior can be analytically described and analyzed with improved LPM. Finally, the validity of improved LPM was verified by experiments. Results indicated that the improved LPM can predict earmuff attenuation with air leakage, and air leakage deteriorates earmuff attenuation and shifts resonance frequency higher.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigated the collective plasma oscillations theoretically in multilayer 8-<jats:italic>Pmmn</jats:italic> borophene structures where the tilted Dirac electrons in spatially separated layers are coupled via the Coulomb interaction. We calculated the energy dispersions and Landau dampings of the multilayer plasmon excitations as a function of the total number of layers, the interlayer separation, and the different orientations. Like multilayer graphene, the plasmon spectrum in multilayer borophene consists of one in-phase optical mode and <jats:italic>N</jats:italic>-1 out-of-phase acoustical modes. We show that the plasmon modes possess kinks at the boundary of the interband single-particle continuum and the apparent anisotropic behavior. All the plasmon modes approach the same dispersion at a sufficiently large interlayer spacing in the short-wavelength limit. Especially along specific orientations, the optical mode could touch an energy maximum in the nondamping region, which shows non-monotonous behavior. Our work provides an understanding of the multilayer borophene plasmon and may pave the way for multilayer borophene-based plasmonic devices.</jats:p>

<jats:p>A nonlocal Boussinesq equation is deduced from the local one by using consistent correlated bang method. To study various exact solutions of the nonlocal Boussinesq equation, it is converted into two local equations which contain the local Boussinesq equation. From the <jats:italic>N</jats:italic>-soliton solutions of the local Boussinesq equation, the <jats:italic>N</jats:italic>-soliton solutions of the nonlocal Boussinesq equation are obtained, among which the (<jats:italic>N</jats:italic> = 2,3,4)-soliton solutions are analyzed with graphs. Some periodic and traveling solutions of the nonlocal Boussinesq equation are derived directly from the known solutions of the local Boussinesq equation. Symmetry reduction solutions of the nonlocal Boussinesq equation are also obtained by using the classical Lie symmetry method.</jats:p>

<jats:p>The finite temperature Lanczos method (FTLM), which is an exact diagonalization method intensively used in quantum many-body calculations, is formulated in the framework of orthogonal polynomials and Gauss quadrature. The main idea is to reduce finite temperature static and dynamic quantities into weighted summations related to one- and two-dimensional Gauss quadratures. Then lower order Gauss quadrature, which is generated from Lanczos iteration, can be applied to approximate the initial weighted summation. This framework fills the conceptual gap between FTLM and kernel polynomial method, and makes it easy to apply orthogonal polynomial techniques in the FTLM calculation.</jats:p>