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Abstract:In order to solve the problem of dynamic gunnery problem solution under fire maneuver condition, this paper proposes a method of hitting the moving targets with rapid fire in the maneuver weapon. Based on the exterior ballistics model, objective model, the dynamic gunnery problem solution model is established. The improved particle swarm optimization (PSO) is adopted to calculate the ballistic data. In the process of realizing the algorithm, the angle of firing, azimuth and flight time of projectile are calculated iteratively synchronously, so as to improve the efficiency of the solution by eliminating the initial time assignment step. Considering the sustained rapid fire of maneuver weapon, the adjusting parameters of fire control elements for dynamic shooting are provided by solving the first and last firing ballistic data. The feasibility of the algorithm is verified by simulation experiment.

The aspect ratio has a significant effect on buckling instability. In this study, we used molecular dynamics (MD) simulation to investigate the buckling instability mechanism of NiCoCr medium-entropy alloy (MEA) nanotubes (NTs) under the compression process. Based on the compression results, we find that the buckling point and the critical buckling stress decrease with increasing aspect ratio. The critical buckling stress of the MD simulations resembles the Euler and Rayleigh–Ritz theories. The critical aspect ratio of 10 showed instability at NiCoCr NTs. In addition, we found that the compressive strength of single-crystalline specimens is much higher than that of polycrystalline specimens. Partial dislocations (PDs) dominated by stacking faults and twinning structures are mainly distributed on the grain boundaries of small grain specimens and decrease with increasing grain size. We also found that polycrystalline structures tend to induce buckling instability. The wall thickness specimen of the 7 nm has confirmed similar compressive strength as the nanowire. The compressive strength decreases as the wall thickness decreases. More stress concentration and PDs distributed in the specimen when the wall thickness is reduced to 1 nm, and it is easier to induce buckling instability at NiCoCr MEA NTs.

This paper presents a force/disturbance observer that compensates for the low-frequency response of a piezoelectric force sensor. Although the piezoelectric force sensor has many salient features, it is unable to measure dc and quasi-dc forces. The proposed observer compensates for this low-frequency deficiency, enabling the piezoelectric force sensor to be used in a servo system. Compared with previous studies, the proposed scheme requires redesigning neither the sensor structure nor sensing circuitry and can be easily integrated into an existing measurement system. As a by-product, the proposed observer also produces a disturbance estimate that can be used to enhance the robustness of a servo system. This paper reports experimental results of force control and position control for a linear motion platform equipped with a piezoelectric force sensor and a strain gauge-based load cell. The force control results indicate that the control system using the proposed observer can achieve a wider bandwidth than that using the load cell as a feedback-sensing device. In a comparative study, the position control results further demonstrate the proposed observer’s effectiveness in diminishing the piezoelectric sensor’s low-frequency deficiency. Moreover, the disturbance estimate produced by the proposed observer is experimentally introduced to the position control system, showing an enhanced tracking performance in terms of the root-mean-square error.

Significant decoherence of the plasmon-emitter (i.e., plexcitonic) strong coupling systems hinders the progress towards their applications in quantum technology due to the unavoidable lossy nature of the plasmons. Inspired by the concept of spectral-hole-burning (SHB) for frequency-selective bleaching of the emitter ensemble, we propose ‘cavity SHB’ by introducing cavity modes with moderate quality factors to the plexcitonic system to boost its coherence. We show that the detuning of the introduced cavity mode with respect to the original plexcitonic system, which defines the location of the cavity SHB, is the most critical parameter. Simultaneously introducing two cavity modes of opposite detunings, the excited-state population of the emitter can be enhanced by 4.5 orders of magnitude within 300 fs, and the attenuation of the emitter’s population can be slowed down by about 56 times. This theoretical proposal provides a new approach of cavity engineering to enhance the plasmon-emitter strong coupling systems’ coherence, which is important for realistic hybrid-cavity design for applications in quantum technology.

We report on the growth and characterization of a niobium titanium nitride (NbTiN) film on a Si substrate prepared by ultrahigh vacuum sputtering. We show that the superconducting transition temperature is lower than those of high-quality NbTiN films. Interestingly, even though the zero-temperature Ginzburg-Landau coherence length (=9.77 nm) is significantly shorter than the film thickness (=86 nm), we are still able to observe the Berezinskii-Kosterlitz-Thouless-like transition, indicating the two-dimensional (2D) signature of our three-dimensional (3D) sample. We propose that the mechanism of hidden 2D superconducting property is similar to the recently reported results of the disordered induced 3D to 2D superconductor transition. We suggest further theoretical work is required for studying our new experimental results.

The multifrequency resonance has been widely explored in some of the single-particle models, in which the modulating Rabi model has been most widely investigated. It has been found that with the diagonal periodic modulation, a steady dynamics can be realized in some well-defined discrete frequencies. These frequencies are independent of the off-diagonal couplings. In this work, we generalize this physics to the many-body seesaw realized using the tilted Bose-Hubbard model. We find that the wave function will recover to its initial condition when the modulation frequency is commensurate with the initial energy level spacing between the ground and the first excited levels. The period is determined by the driving frequency and commensurate ratio. In this case, the wave function will almost be restricted to the lowest two instantaneous energy levels. By projecting the wave function to these two relevant states, the dynamics is exactly the same as that for the spin precession dynamics and nutation dynamics around an oscillating axis. We map out the corresponding phase diagram and show that in the low-frequency regime the state is thermalized and in the strong modulation limit, the dynamics is determined by the effective Floquet Hamiltonian. The measurement of these dynamics from the mean position and mean momentum in phase space are also discussed. Our results provide a new thought about the multifrequency resonance in the many-body system., 7 pages, 6 figures

The in-plane magnetic hysteresis loops of Fe3O4/SrTiO3(STO) and Fe3O4/STO/Ba0.6Sr0.4TiO3(BSTO) heterostructures have been investigated at 200 K under various electric fields. The bottom BSTO layer of the STO/BSTO bilayer is used to improve the dielectric properties of the top STO layer. The polarization of the STO/BSTO bilayer is ∼78% larger than that of the STO layer at room temperature due to the improvement of surface topography and the contribution of electrostatic interlayer coupling. A significant enlargement (∼70%) in the magnetoelectric response of Fe3O4/STO/BSTO heterostructure has been achieved at 200 K and 300 kV cm-1 after introducing the BSTO layer, since the STO/BSTO bilayer with larger dielectric constant supplies more polarization charges at its interface to the Fe3O4 layer than the STO layer. It indicates that the dielectric bilayer improves the polarization and thus benefits the magnetoelectric coupling in the multiferroic heterostructure.

We report that an acoustic logic gate is realized by a three-port curved waveguide with four ultrathin curved metasurfaces immersed in air. By mechanically adjusting the angle positions of the curved metasurfaces, the transmission and phase of sound signals can be manipulated, and thus three basic logic functions OR, AND and NOT are realized in the same curved waveguide structure based on a linear interference mechanism. Moreover, the designed logic gate is also effective for two input signals with a certain phase difference, showing a high robustness in practical applications. Our designed logic gates have the advantages of constant structure configuration, passive phase modulation and high robustness, which have great potential applications in computing, information processing and integrated acoustics.

Since the Jost solutions of the derivative nonlinear Schrodinger equation do not tend to the free Jost solutions, when the spectral parameter tends to infinity(|λ| → ∞), the usual inverse scattering transform (IST) must be revised. If we take the parameter κ = λ−1 as the basic parameter, the Jost solutions in the limit of |κ| → ∞ do tend to the free Jost solutions, hence the usual procedure to construct the equations of IST in κ-plane remains effective. After we derive the equation of IST in terms of κ, we can obtain the equation of IST in λ-plane by the simple change of parameters λ = κ−1. The procedure to derive the equation of IST is reasonable, and attention is never paid to the function W(x) introduced by the revisions of Kaup and Newell. Therefore, the revision of Kaup and Newell can be avoided.

Since the Jost solutions of the DNLS equation does not tend to the free Jost solutioins as | | ! 1, the usual inverse scattering transform (IST) must be revised. Beside the Kaup and Newell's approach, we propose a simple revision in constructing the equations of IST, where the usual Zakharov-Shabat kern is revised by multiplying 2 or 1 . To justify the revision we show that the Jost solutions obtained do satisfy the pair of compatibility equations.

In this paper we study the influence of anisotropy on the usefulness of the entanglement in a two-qubit Heisenberg XY chain at thermal equilibrium in the presence of an external magnetic field, as a resource for quantum teleportation via the standard teleportation protocol. We show that the nonzero thermal entanglement produced by adjusting the external magnetic field beyond some critical strength is a useful resource. We also consider entanglement teleportation via two two-qubit Heisenberg XY chains.

In order to accurately predict the dynamic instability of helicopter ground resonance, a modeling and simulation method of helicopter ground resonance considering nonlinear dynamic characteristics of components (rotor lead-lag damper, landing gear wheel and absorber) is presented. The numerical integral method is used to calculate the transient responses of the body and rotor, simulating some disturbance. To obtain quantitative instabilities, Fast Fourier Transform (FFT) is conducted to estimate the modal frequencies, and the mobile rectangular window method is employed in the predictions of the modal damping in terms of the response time history. Simulation results show that ground resonance simulation test can exactly lead up the blade lead-lag regressing mode frequency, and the modal damping obtained according to attenuation curves are close to the test results. The simulation test results are in accordance with the actual accident situation, and prove the correctness of the simulation method. This analysis method used for ground resonance simulation test can give out the results according with real helicopter engineering tests.

Kaup and Newell's revised inverse scattering transform for the derivative nonlinear Schrodinger (DNLS) equation is investigated. We compared it with a more reasonable approach proposed recently, which is rigorously proven by the Liouville theorem. It is concluded that Kaup and Newell's revision is only suitable for giving single-soliton solution and can not be generalized to multi-soliton case.

Au nanoparticle-decorated TiO2 nanotube arrays are prepared by a simple method, which is a thermal annealing thin gold film deposited on anodic oxidized TiO2 nanotube arrays. These electron microscope images present that Au nanoparticles are well dispersed within the wall and on the surface of the TiO2 nanotubes. Meanwhile, the morphologies of Au nanoparticles can be controlled by changing the thickness of the deposited gold film. Associated with the excitation of localized surface plasmon resonances, the prepared Au nanoparticle-decorated TiO2 nanotube arrays could work as visible light responsive photocatalysts to produce a greatly enhanced photocurrent density. By varying the initial gold film thickness, such Au nanoparticle-decorated TiO2 nanotube arrays could be optimized to obtain the highest photocurrent generation efficiency in the visible and UV light regions.

A 3-dimensional chain-network anatase/TiO2 (B) was obtained via the basic hydrothermal treatment of a sandwich Ti/TiO2/Ti film on a glass substrate that was prepared from 16 nm anatase TiO2 nanoparticles. The Ti film was converted to the TiO2 (B) phase in a Teflon vessel containing a 10 M NaOH aqueous solution that was encapsulated in a stainless-steel autoclave and heated at 130 °C for 2 h. The TiO2 (B) then served as a binder layer that enabled the formation of pearl-necklace chains made of anatase TiO2 nanoparticles, and these chain-like structures thoroughly interpenetrated into the textured layer. Decomposition tests using methylene blue indicated that the chain-network anatase/TiO2 (B) mixed-phase film had a photocatalytic half-life that was 0.84 and 0.69 times shorter than those of as-prepared anatase TiO2 and P25, respectively. In addition, the intensity of the room temperature photoluminescence spectra of anatase TiO2 was 2.55-fold higher than that of the chain-network anatase/TiO2 (B). We thus conclude that the remarkable photocatalytic activity of the chain-network anatase/TiO2 (B) is attributed to the chain-network structural characteristics and a synergistic effect of the matching band gap potentials, which increases the transfer of photogenerated electrons and reduces electron-hole recombination.

The effects of using lattice-modulated AlInGaN as barriers in the active region were investigated in near-ultraviolet light-emitting diodes (LEDs). Both a stronger localization effect with wider barriers and a higher energy band gap existed in AlInGaN/InGaN LEDs, compared with GaN/InGaN LEDs. An increase in the carrier concentration in the active layer, a reduction in lattice mismatch that induced polarization mismatch in the active layer, and suppression of electron overflow can be found by numerical simulation. By 100 mA current injection, the AlInGaN/InGaN LED output power can be increased by 33.1%, compared with that of GaN/InGaN LED.

The effects of lattice-matched InAlGaN used as barriers in the active region were investigated in near ultraviolet light-emitting diodes (LEDs). By changing the thickness of InAlGaN barriers, it is observed that there exists an optimal thickness. Besides the better carrier confinement in the case of using thick barriers, the simulation results showed that hole distribution in the case of using wide barriers should also play a role in the improvement of optical performance. Hence, an excessive increment in the width of barriers will degrade the optical performance contrarily, owing to the accumulated stress and the difficulty in hole transport in the active region from thick barriers. In addition, the calculated energy bandgap of InAlGaN is higher than that of GaN, which is beneficial for increasing the capability of carrier confinement and simultaneously enhancing the radiative recombination. Under 100 mA, the light output power of the LED with 7.3-nm-thick In0.018Al0.09Ga0.892N barriers can be increased by 36% as compared with the LED with GaN barrier.

The effect of selective Si doping on the emission efficiency in ultraviolet (UV) light-emitting diodes (LEDs) is investigated both experimentally and theoretically. The results show that the light output power increases with the number of Si-doped barriers (QBs). Experimental results indicate that compared with an all-undoped-QB LED, a factor of 3.17 can be achieved for the output power of an all-doped-QB LED at 350 mA. Detailed analysis on this phenomenon shows that the Si-doped QB is beneficial to suppress the nonradiative recombination rate by excess electrons in doped barriers.

The work reports a theoretical and experimental study on the device performance of near ultraviolet light-emitting diodes (LEDs) with specific design on the electron blocking layer (EBL) by employing the band-engineering. The simulation results show the polarization-induced downward band bending is mitigated in the specific EBL design and, hence, the capability of hole transportation increases and the behavior of electron overflow decreases. The experimental results show the LEDs with specific EBL design exhibited a reduction of forward voltage from 4.40 to 4.07 V and a much enhancement of light output power from 30.6 to 51.9 mW, compared with conventional LED.

In this study, the effect of uniaxial tensile on the SiO2/Si interface of the 28 nm n-type metal–oxide–semiconductor field-effect transistors (nMOSFETs) has been investigated. nMOSFETs were fabricated with different thicknesses of the stress-memorization technique (SMT) films to further increase channel stress because the SMT films can provide a higher uniaxial tensile to the channel. Trap behaviors such as activation energy and depth were characterized on the basis of drain current random telegraph noise (RTN). By RTN analyses, we found that the trap energy level is closer to the channel conduction band as the tensile strain in the channel increases higher, resulting in the trap being located close to the SiO2/Si interface.

InGaN/AlGaN ultraviolet light-emitting diodes (UV LEDs) with AlGaN barriers having various Si doping concentrations are grown by metal–organic chemical vapor deposition. The light output power of UV LEDs was obviously improved as a result of Si doping of the AlGaN barriers. Detail analysis of this improvement by simulation modeling showed that the increase in Si doping concentration in AlGaN barrier is beneficial for increasing electron injection efficiency and simultaneously the radiative recombination distribution.

In this study, the impact of embedded tip-shaped SiGe in the source/drain (S/D) region on individual trap behavior such as activation energy and depth from the SiO2/Si interface of the 28 nm p-type metal–oxide–semiconductor field-effect transistors (pMOSFETs) has been investigated on the basis of drain current random telegraph noise (RTN). The purpose of implementing tip-shaped SiGe S/D is to further increase channel stress because it provides a closer proximity of embedded SiGe to the channel. By characterizing RTN, we found that the pMOSFETs underwent uniaxial compressive strain that was provided by tip-shaped SiGe S/D, and the trap energy level being close to the channel valence band resulted in the trap located close to the Si/SiO2 interface, as compared with the control device without embedded SiGe S/D.

The silicon dioxide (SiO2) on AlGaAs prepared by liquid phase deposition (LPD) at 40 °C has been explored. The LPD-SiO2 film deposition rate is about 67 nm h−1 for the first hour. The leakage current density is about 1.21 × 10−6 A cm−2 at 1 MV cm−1. The interface trap density (Dit) and the flat-band voltage shift (ΔVFB) are 1.28 × 1012 cm−2 eV−1 and 0.5 V, respectively. After rapid thermal annealing in the N2 ambient at 300 °C for 1 min, the leakage current density, Dit, and ΔVFB can be improved to 4.24 × 10−7 A cm−2 at 1 MV cm−1, 1.7 × 1011 cm−2 eV−1, and 0.2 V, respectively. Finally, this study demonstrates the application of the LPD-SiO2 film to the AlGaAs/InGaAs pseudomorphic high-electron-mobility transistor.

For InGaN/GaN based nanorod devices using a top-down etching process, the optical output power is affected by non-radiative recombination due to sidewall defects (which decrease light output efficiency) and the mitigated quantum confined Stark effect (QCSE) due to strain relaxation (which increases internal quantum efficiency). Therefore, the exploration of low-temperature optical behaviors of nanorod light emitting diodes (LEDs) will help identify the correlation between these two factors. In this work, low-temperature electroluminescent (EL) spectra of InGaN/GaN nanorod arrays were explored and compared with those of planar LEDs. The nanorod LED exhibits a much higher optical output percentage increase when the temperature decreases. The increase is mainly attributed to the increased carriers in the quantum wells for radiative recombination. Also, due to a better spatial overlap of electrons and holes in the quantum wells, the increased number of carriers can be more efficiently recombined in the nanorod device. Next, while the nanorod array shows nearly constant peak energy in the EL spectra at various injection currents at the temperature of 300 K, a blue shift has been observed at 190 K. The results suggest that with less non-radiative recombination and thus more carriers in the quantum wells, carrier screening and band filling still prevail in the partially strain relaxed nanorods. Moreover, when the temperature drops to 77 K, the blue shift of both nanorod and planar devices disappears and the optical output power decreases since there are fewer carriers in the quantum wells for radiative recombination.

Transverse mode competitions are compared between the large mode area (LMA) fiber lasers with and without flattened fundamental modes (FMs). Numerical simulations show that the flattened-FM fiber lasers can support single-mode (SM) operation without employing other mode selection methods. This property is useful for designing LMA fiber lasers with SM operation. For the flattened-FM fiber amplifiers, the photonic crystal fiber (PCF) with a flattened FM is proposed to shape the Gaussian beam into a flat-top one, which is coupled into the input end of the active fiber as a seed. The SM operation based on this approach can be obtained.