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<jats:p>Ionosphere delay is one of the main sources of noise affecting global navigation satellite systems, operation of radio detection and ranging systems and very-long-baseline-interferometry. One of the most important and common methods to reduce this phase delay is to establish accurate nowcasting and forecasting ionospheric total electron content models. For forecasting models, compared to mid-to-high latitudes, at low latitudes, an active ionosphere leads to extreme differences between long-term prediction models and the actual state of the ionosphere. To solve the problem of low accuracy for long-term prediction models at low latitudes, this article provides a low-latitude, long-term ionospheric prediction model based on a multi-input-multi-output, long-short-term memory neural network. To verify the feasibility of the model, we first made predictions of the vertical total electron content data 24 and 48 hours in advance for each day of July 2020 and then compared both the predictions corresponding to a given day, for all days. Furthermore, in the model modification part, we selected historical data from June 2020 for the validation set, determined a large offset from the results that were predicted to be active, and used the ratio of the mean absolute error of the detected results to that of the predicted results as a correction coefficient to modify our multi-input-multi-output long short-term memory model. The average root mean square error of the 24-hour-advance predictions of our modified model was 4.4 TECU, which was lower and better than 5.1 TECU of the multi-input-multi-output, long short-term memory model and 5.9 TECU of the IRI-2016 model.</jats:p>

<jats:p>Calculations on the spectroscopic constants and transition properties of the first three states (a<jats:sup>1</jats:sup>Δ, b<jats:sup>1</jats:sup>Σ<jats:sup>+</jats:sup>, and X<jats:sup>3</jats:sup>Σ<jats:sup>−</jats:sup>) of the SbH molecule were performed under the relativistic framework using the exact two-component Hamiltonian (X2C). The potential energy curves in the Franck–Condon region were computed and compared with the previous values. Furthermore, the transition dipole moments for the weak spin-forbidden transitions (b0<jats:sup>+</jats:sup>–X<jats:sub>1</jats:sub>0<jats:sup>+</jats:sup>, b0<jats:sup>+</jats:sup>–X<jats:sub>2</jats:sub>1, X<jats:sub>1</jats:sub>0<jats:sup>+</jats:sup>–X<jats:sub>2</jats:sub>1, and X<jats:sub>2</jats:sub>1–a2) were reported. The spontaneous radiative lifetime of the b<jats:sup>1</jats:sup>Σ<jats:sup>+</jats:sup> (<jats:italic>υ</jats:italic>′ = 0) state was calculated as 163.5±7.5 μ s, which is in reasonable agreement with the latest experimental value of 173±3 μ s. The spontaneous radiative lifetimes of the X<jats:sub>2</jats:sub>1 (<jats:italic>υ</jats:italic>′ = 0) state and the a2 (<jats:italic>υ</jats:italic>′ = 0) state were calculated to be 48.6 s and ∼ 8 ms, respectively. Our study is expected to be a benchmark transition property computation for comparison with other theoretical and experimental results. The datasets presented in this paper, including the transition dipole moments, are openly available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://dx.doi.org/10.11922/sciencedb.j00113.00018" xlink:type="simple">https://dx.doi.org/10.11922/sciencedb.j00113.00018</jats:ext-link>.</jats:p>

<jats:p>We present elastic electron scattering cross sections with holmethane molecules CH<jats:sub>2</jats:sub>Br<jats:sub>2</jats:sub> and CCl<jats:sub>2</jats:sub>Br<jats:sub>2</jats:sub> in the low-energy region ranging from 0.01 eV to 20 eV. The calculations are performed with the <jats:italic>R</jats:italic>-matrix method in static-exchange plus polarization (SEP) and close-coupling (CC) approximations. The integral, differential, and momentum transfer cross sections are calculated. The convergence of the obtained cross sections is checked at four different levels of SEP approximation. The predicted positions of the resonances agree well with available results. The precise resonance parameters are found to be sensitive to the treatment of polarization effects employed. We find that the polarization has a substantial effect on the cross sections, and this effect becomes even more important for lower impact energies.</jats:p>

<jats:p>Reusable reciprocal invisibility and phantom device is proposed and designed based on multi-folded transformation optics and equivalent components. In comparison with the reported reciprocal invisibility cloaks, the material parameters of the device presented here are homogeneous, and the hiding of the target object does not require any “anti-object” at all, which dramatically breaks through the limitations of the “anti-object” design in previous reciprocal cloak design. Perfectly illusion effect is also found by reasonably setting the material parameters of the restored medium of the device, which can be used to confuse detection radars while hiding target objects. Last but not least, the proposed device has an open structure, which enables the target object enclosed by the device to perform material exchange and simplex transfer of information with the outside world through open channels. In other words, the proposed device has a reusable function, enabling stealth or phantom of new target objects without changing any parameters of the device.</jats:p>

<jats:p>The optical injection locking of semiconductor lasers to dual-frequency lasers is studied by numerical simulations. The beat-note signals can be effectively transformed to optical frequency combs due to the effective four wave-mixing in the active semiconductor gain medium. The low-noise Gaussian-like pulse can be obtained by locking the relaxation oscillation and compensating the gain asymmetry. The simulations suggest that pulse trains of width below 30 ps and repetition rate in GHz frequency can be generated simply by the optical injection locking of semiconductor lasers. Since the optical injection locking can broaden the spectrum and amplify the optical power simultaneously, it can be a good initial stage for generating optical frequency combs from dual-frequency lasers by multi-stage of spectral broadening in nonlinear waveguides.</jats:p>

<jats:p>A novel high-energy picosecond optical parametric oscillator (OPO) was realized by placing an OPO in a second-harmonic (SH) cavity. In a proof-of-principle experiment, we demonstrated excellent burst energy of 45 μJ for the OPO signal at 900 nm that operates at a pulse repetition rate of 10 kHz and a pulse width of 46.8 ps. The beam quality was measured as <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{x}^{2}=1.44$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>M</mml:mi> <mml:mi>x</mml:mi> <mml:mn>2</mml:mn> </mml:msubsup> <mml:mo>=</mml:mo> <mml:mn>1.44</mml:mn> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_31_8_084206_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math> <?CDATA ${M}_{y}^{2}=1.40$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>M</mml:mi> <mml:mi>y</mml:mi> <mml:mn>2</mml:mn> </mml:msubsup> <mml:mo>=</mml:mo> <mml:mn>1.40</mml:mn> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_31_8_084206_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> in the orthogonal directions, corresponding to an average beam factor <jats:italic>M</jats:italic> <jats:sup>2</jats:sup> = 1.42. So far, this study is the first to investigate high-energy ps OPO synchronously pumped in a second-harmonic cavity.</jats:p>

<jats:p>A dynamically tunable multiband plasmon-induced transparency (PIT) effect in a series of rectangle cavities coupled with a graphene nanoribbon waveguide system is investigated theoretically and numerically by tuning the Fermi level of the graphene rectangle cavity. A single-PIT effect is realized using two different methods: one is the direct destructive interference between bright and dark modes, and the other is the indirect coupling through a graphene nanoribbon waveguide. Moreover, dual-PIT effect is obtained by three rectangle cavities side-coupled with a graphene nanoribbon waveguide. Results show that the magnitude of the dual-PIT window can be controlled between 0.21 and 0.74, and the corresponding group index is controlled between 143.2 and 108.6. Furthermore, the triple-PIT effect is achieved by the combination of bright–dark mode coupling and the cavities side-coupled with waveguide mechanism. Thus, sharp PIT windows can be formed, a high transmission is maintained between 0.51 and 0.74, and the corresponding group index is controlled between 161.4 and 115.8. Compared with previously proposed graphene-based PIT effects, the size of the introduced structure is less than 0.5 μm<jats:sup>2</jats:sup>. Particularly, the slow light effect is crucial in the current research. Therefore, a novel approach is introduced toward the realization of optical sensors, optical filters, and slow light and light storage devices with ultra-compact, multiband, and dynamic tunable.</jats:p>

<jats:p>Previous studies of drop impact mainly focus on homogeneous substrates while heterogeneous substrates remain largely unexplored. A convenient preparation strategy of stiff heterogeneous substrates is presented in this work, and the drop impact on such a stiffness-patterned substrate consisting of soft spirals surrounded by a rigid region is systematically investigated. The results show that the splash behavior of a drop on a stiffness-patterned substrate exhibits distinct characteristics from those on a homogeneous substrate. Prompt splash is more likely to occur on the substrate with the greater heterogeneity of stiffness, which is reflected in the lower critical impact velocity. Moreover, the splash velocity of emitted droplet is significantly larger on the heterogeneous substrate than that on a corresponding homogeneous substrate, especially at a higher impact velocity of the drop, indicating a stronger splash intensity on the heterogeneous substrate. The difference in drop splashing between homogeneous substrate and heterogeneous substrate is largely due to the stiffness heterogeneity, rather than the variation of overall stiffness of the substrate. The use of spiral shape provides a feasible solution for introducing stiffness heterogeneity of substrate. This study is conducive to the understanding of drop impact research beyond uniform substrates, reveals the potential of using stiffness-patterned substrates to control splash, and may find useful applications in industries related to drop impact and splash.</jats:p>

<jats:p>Hexagonal boron nitride (h-BN) films are synthesized by dual temperature zone low-pressure chemical vapor deposition (LPCVD) through using a single ammonia borane precursor on non-catalytic <jats:italic>c</jats:italic>-plane Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> substrates. The grown films are confirmed to be h-BN films by various characterization methods. Meanwhile, the growth rates and crystal quality of h-BN films at different positions in the dual temperature zone are studied. It is found that the growth rates and crystal quality of the h-BN films at different positions on the substrate are significantly different. The growth rates of the h-BN thin films show their decreasing trends with the rearward position, while the crystal quality is improved. This work provides an experimental basis for the preparation of large area wafer thick h-BN films by LPCVD.</jats:p>

<jats:p>We report computer simulations on the oscillatory of CuZr metallic glasses at zero temperature with different shear amplitudes. In small system a homogenous shear deformation is found, while in large system an inhomogeneous shear deformation is found with a shear band formed. Concomitantly, spatial correlation of irreversible displacement exhibits an isotropic and exponential decay in the case of homogeneous deformation, whereas a mixed power-law and exponential decay in the case of anisotropic and inhomogeneous deformation. By projecting the azimuthal-dependent correlation function onto the spherical harmonics, we found a strong polar symmetry that accounts for the emerged shear band, and a weaker quadrupolar symmetry that accounts for the elastic filed generated by Eshelby inclusions. By this, we conclude that the anisotropy and decaying formula of the plastic correlation are dominated by the homogeneity or inhomogeneity for the deformation in the metallic glasses.</jats:p>