Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>In this paper, a perfect bidirectional broadband visible light absorber composed of Titanium nitride and Tungsten nanodisk arrays is proposed. The average absorption of the absorber exceeds 89% at 400-800 nm when light is normally incident on the front-sided. Illumination from the opposite direction (back-sided) results in absorption of more than 75%. Through the theoretical analysis of the electric and magnetic fields, the physical mechanism of the broadband perfect absorption is attributed to the synergy of localized surface plasmons, propagating surface plasmons, and plasmonic resonant cavity modes. Furthermore, the absorber also exhibits excellent polarization-independence performance and a high angular tolerance of ~30° for both front- and back-sided incidence. The designed bidirectional broadband visible light absorber here has wide application prospects in the fields of solar cells and ink-free printing.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigated the angle-dependent spin wave spectra of Permalloy ring arrays with the fixed outer diameter and various inner diameters by ferromagnetic resonance spectroscopy and micromagnetic simulation. When the field is obliquely applied to the ring, local resonance mode can be observed in different parts of the rings. And the resonance mode will change to perpendicular spin standing waves if the magnetic field is applied along the perpendicular direction. The simulation results demonstrated this evolution and implied more resonance modes that maybe exist. And the mathematical fitting results based on the Kittel equation further proved the existence of local resonance mode.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>A method to measure the detailed performance of polycapillary X-ray optics by a pinhole and charge coupled device (CCD) detector was proposed in this study. The pinhole was located between the X-ray source and the polycapillary X-ray optics to determine the illuminating region of the incident X-ray beam on the input side of the optics. The CCD detector placed downstream of the polycapillary X-ray optics ensured that the incident X-ray beam controlled by the pinhole irradiated a specific region of the input surface of the optics. The intensity of the output beam of the polycapillary X-ray optics was obtained from the far-field image of the output beam of the optics captured by CCD detector. As an application example, the focal spot size, gain in power density, transmission efficiency, and beam divergence of different parts of a polycapillary focusing X-ray lenses (PFXRL) were measured by a pinhole and CCD detector. Three pinholes with diameters of 500, 1000, and 2000 μm were used to adjust the diameter of the incident X-ray beam illuminating the PFXRL from 500 μm to the entire surface of the input side of the PFXRL. The focal spot size of the PFXRL, gain in power density, transmission efficiency, and beam divergence ranged from 27.1 to 34.6 μm, 400 to 3460, 26.70% to 5.38%, and 16.8 to 84.86 mrad, respectively.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study the wave-particle duality in a general Mach-Zehnder interferometer with an asymmetric beam splitter from the viewpoint of quantum information theory. The correlations(including the classical correlation and the quantum correlation) between the particle and the which-path detector are derived when they are in pure state or mixed state at the output of Mach-Zehnder interferometer. It is found that the fringe visibility and the correlations are effected by the asymmetric beam splitter and the input state of the particle. The complementary relations between the fringe visibility and the correlations are also presented.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>This paper provides an adaptive closed-loop strategy for suppressing the pathological oscillations of the basal ganglia based on a variable universe fuzzy algorithm. The pathological basal ganglia oscillations in the theta (4-9Hz) and beta (12-35Hz) frequency bands have been demonstrated to be associated with the tremor and rigidity/bradykinesia symptoms in Parkinson's disease (PD). Although the clinical application of open-loop deep brain stimulation (DBS) is effective, the stimulation waveform with the fixed parameters cannot be self-adjusted as the disease progresses, and thus the stimulation effects go poor. To deal with this difficult problem, a variable universe fuzzy closed-loop strategy is proposed to modulate different PD states. This paper establishes a cortico-basal ganglia-thalamocortical network model to simulate pathological oscillations and test the control effect. The results suggest that the proposed closed-loop control strategy can accommodate the variation of brain states and symptoms, which may become an alternative method to administrate the symptoms in PD.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Combining hyperchaotic map, cross-plane operation and gene theory, a color image encryption scheme is devised. First, the hyperchaotic map used in the encryption scheme is analyzed and studied. On the basis of the dynamics of hyperchaotic map, a color image encryption scheme is designed. At the end of the encryption process, a DNA mutation operation is used to increase the encoding images’ randomness and improve the encryption algorithm’s security. Finally, simulation experiments, performance analysis, and attack tests are performed to prove its effectiveness and security of the designed algorithm. The research work in this paper offers the possibility of applying chaos theory and gene theory in image encryption.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In order to reduce the external magnetic field and improve the conversion efficiency of high-power microwave generation devices with low external magnetic field, a novel diode with embedded soft magnetic and shielding structure is proposed. The soft magnetic material is designed to enhance the local magnetic field in the diode region. Besides, the diode applies a shielding structure which can reduce the radial electric field. From simulation research, it is found that the emission and transmission quality of the electron beam with low magnetic field is greatly improved when loading this diode. Through simulation research, it is verified that the diode can increase the conversion efficiency of the TTO from 30% to 36.7%. In our experimental study, under the conditions of a diode voltage of 540kV and a current of 10.5kA, the output microwave power is 1.51GW when loading the novel diode and the microwave frequency is 4.27GHz when an external guiding magnetic field of 0.3T is applied. The corresponding conversion efficiency is improved from 20.0% to 26.6%, which is 6.6% higher than the device loaded with a conventional diode. Our experiments have verified that this novel diode can effectively improve the conversion efficiency of high-power microwave sources operating with low magnetic field, and contribute to the miniaturization and compactness of high-power microwaves.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Polyyne, a sp<jats:sup>1</jats:sup>-hybridized linear allotrope of carbon, has a tunable quasiparticle energy gap, which depends on the terminated chemical ending groups as well as the chain length. Previously, nitrogen doping was utilized to tailor the properties of different kinds of allotrope of carbon. However, how the nitrogen doping tailors the properties of the polyyne remains unexplored. Here, we applied the GW method to study the quasiparticle energy gaps of the N-doped polyynes with different lengths. When a C atom is substituted by a N atom in a polyyne, the quasiparticle energy gap varies with the substituted position in the polyyne. The modification is particularly pronounced when the second-nearest-neighboring carbon atom of a hydrogen atom is substituted. In addition, the nitrogen doping makes the Fermi level closer to the lowest unoccupied molecular orbital, resulting in a n-type semiconductor. Our results suggest another route to tailor the electronic properties of polyyne in addition to the length of polyyne and the terminated chemical ending groups.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have studied structural and atomic transport properties for liquid <jats:italic>f</jats:italic>-shell ytterbium in a temperature range 1123–1473 K. Pair interactions among atoms are derived using a local pseudopotential. The potential parameters are fitted to the phonon dispersion curve at room temperature. The local pseudopotential used in the present study is computationally more efficient with only three parameters, and it is found to be transferable to the liquid phase without changing the parameters. Since computed various properties agree with reported theoretical and experimental findings; the adopted fitting scheme is justified. As a significant outcome of the study, we find that (i) the melting in Yb is governed by the Lindemann’s law, (ii) the mass transport mechanism obeys the Arrhenius law, (iii) the role of three particle correlation function for deriving the velocity autocorrelation function is little, (iv) the mean-square atomic displacement is more sensitive to the choice of interaction potential than the other bulk properties, and (v) the liquid Yb does not show liquid-liquid phase transition within the studied temperature range. Further, due to a good description of the structural and mass transport properties, we propose that Yb remains divalent at reduced density.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We simulate the dynamic response of $\mathrm{H}_{2}^{+}$ in a linearly polarized laser field by numerically solving the time-dependent Schrödinger equation (TDSE). The elliptically polarized high-order harmonics generated by $\mathrm{H}_{2}^{+}$ irradiated by the linearly polarized laser field is systematically investigated. It is found that the amplitude and rotation of the ellipticity of harmonics are affected by the alignment angle and internuclear distance of molecule, and by analyzing the change of the forces acted on the ionized electrons and the trajectories of the electrons, the phenomena are resulted from the change in the direction of the total coulomb forces from the two nuclear felt by the re-collided ionized electrons in the direction perpendicular to laser polarization direction. According to the influence law, we can select the harmonics with specific frequency band under different alignment angles, then synthesize the isolated attosecond pulses with different rotation, which can be continuously converted from right-handed circular polarization, linear polarization and left-handed circular polarization with the change of the alignment angle. It provides a new possible approach to the real-time detection of molecular states by attosecond pulses and obtaining more optimized harmonics by molecular properties.</jats:p>