Modern Physics Letters B

In this paper, electron acceleration by relativistic pondermotive force has been studied in the interaction of intense laser pulse with an axially inhomogeneous underdense plasma. The results show that the relativistic ponderomotive nonlinearity causes obvious beam self-focusing and a highly energetic electron can be achieved in the plasma, moreover, the high-energy electron would be automatically ejected by the ponderomotive force without adding any additional extractor. In addition, it is found that the real part and imaginary part of Lorentz factor can directly affect the amplitude and change the trend of electron acceleration, and electrons acceleration can be strengthened when we can elect properly the laser intensity with higher momentum and smaller beam width, but nonuniformity of plasmas can slightly decrease the electron acceleration. The results can provide useful physical support for novel design of table accelerator and the optimized parameters of electron acceleration in the plasma.

The global equivalence ratio (ER1) will change drastically when scramjets carry out the mission of condition transition. The blowout characteristics of partially premixed flame in a fuel-rich condition are investigated experimentally in a cavity-stabilized scramjet combustor. The total pressure, total temperature and Mach number at the combustor entrance are 1.6 MPa, 1486 K and 2.52, which can simulate the flight condition of Mach 5.5 at 25 km altitude. When the final ER1 is relatively small, the range and light intensity of flame increase first and then almost keep constant. The cavity-stabilized flame can be switched from cavity shear layer to jet-wake. Once the final ER1 exceeds a critical value, the rich flame blowout phenomena will appear suddenly. During the blowout process, the flame in the cavity is blown out first and then the flame downstream extinguishes completely along the rear-wall. The intensity of combustion at the flame front is more vigorous with a higher ER1 at the initial combustion state, which is conductive to burn more fuel mixed in the incoming flow. When the initial flowfields are more vigorous, the stabilized flame can be shifted to a stronger combustion state under a higher ER1.

HIGHLIGHTS

• •Effectiveness of vice blades flow control method.
• •Improvement mechanism of flow control method on centrifugal pump.
• •Energy redistribution of multi-scale turbulence by flow control method.
• •Design strategy for high-performance centrifugal pump.

The demand for the high-performance centrifugal pumps has grown considerably in order to address various working conditions and application scenarios. Here, a high-performance centrifugal pump capable of great hydraulic and anti-cavitation performance, and low-pressure pulsation and vibration, is realized by adding drainage vice blade to the conventional blade type. The multi-scale turbulence in centrifugal pumps is characterized by the Hybrid RANS/LES method, then the energy distributions are obtained by the proper orthogonal decomposition (POD) method. The experimental methods are employed to study the pressure pulsation and vibration characteristics. The new-type of blades can reconstruct the energy of multi-scale turbulence in centrifugal pump by concentrating the energy on low-frequency large-scale flow structures, while reducing the energy of high-frequency small-scale flow structures. A higher energy of large-scale flow structures can enhance the energy transportation and hydraulic performance in centrifugal pump. The small-scale flow structures with lower energy can suppress high-frequency excitation in flow to avoid the hydraulic resonance, which is essential to improve the dynamic characteristics of the centrifugal pumps. We propose a flow control method that can reconstruct the energy distribution of multi-scale turbulence which can greatly improve its overall performance, suggesting a broad range of promising applications.

A bubble equation of motion close to the solid plane is obtained by using the perturbation method. This bubble equation can explain the phenomena of the reentrant microjet penetrating the bubble produced by the external disturbances if the distance between the bubble center to the solid boundary is small enough as well as the external pressure is large enough. Furthermore, two critical points are found. One critical point is the distance between the bubble center to the solid boundary. The other is external pressure. The critical boundary at which the reentrant microjet can just be produced is given. The critical boundary depends on both the distance between the bubble center to the solid boundary and the ratio of external pressure to the initial pressure of the liquid.

In this paper, the binary Darboux transformation for a defocusing coupled complex modified Korteweg-de Vries (dccmKdV) equation was investigated. With nonzero plane wave initial conditions, we further derived its dark–dark solitons, breather solutions, different types of rogue waves and some new interaction structures among them. These novel results can be applied in the areas of fluid, plasma mechanics, etc.

The Schamel–Korteweg-de Vries (S-KdV) model is used to predict the influence of surface for deep water in the presence of solitary waves. The aim of the study is to study the governing model analytically by employing the extended modified auxiliary equation mapping approach and the extended FAN sub-equation method. The 3D, 2D and contour plots are drawn to demonstrate the physical nature of the nonlinear model for a set of parameters. As a result, dark solitons, light solitons, solitary waves, periodic solitary waves, rational functions, and elliptic function solutions are established. Furthermore, the the developed results are verified with the aid of latest computing tool such as Mathematica or Maple. The applied strategy appears to be a more powerful and efficient scheme for achieving exact solutions to a number of diversified contemporary models of recent eras.

In this paper, two three-party cyclic teleportation schemes for real arbitrary quantum states of a single particle and two particles are proposed for the first time. In the first ($1\sim 2\sim 1$) scheme, Alice sends any single particle state to Bob, Bob sends any two-particle states to Charlie, and meanwhile Charlie sends any single particle state to Alice. In the second ($2\sim 2\sim 1$) scheme, with the help of the controller David, Alice sends any two-particle states to Bob, Bob sends any two-particle states to Charlie, and Charlie sends any single particle state to Alice simultaneously. Based on the maximum entangled quantum channel shared in advance, the communication participants carry out some Bell state measurement (BSM) measurements and carry out corresponding unitary transformation according to the results published by each other. After that, the cyclic teleportation of predetermined quantum information can be successfully realized. The success probability of teleportation of both schemes can reach 100%. Finally, this paper briefly analyzes the security of the two schemes and compares them with some previously published schemes from the perspective of inherent efficiency. The results show that the two schemes proposed in this paper are safe and have high inherent efficiency. Different from the previous symmetric cyclic quantum teleportation methods, the asymmetric cyclic quantum teleportation schemes proposed in this paper are more universal.

The noise attenuation ability of a single material or structure, especially for low-frequency noise, is limited by its thickness. Aiming to achieve high-efficiency noise attenuation at low frequencies, this paper proposes the methods of porous material filling and micro-perforated plate (MPP) embedding to design a perfect sound absorber at different frequencies using the under-loss Helmholtz resonator (HR). Based on the transfer matrix method, the theoretical calculation models of the sound absorption coefficients of the HR, Helmholtz resonator with porous material (HRP), and Helmholtz resonator with micro-perforated plates (HRM) are constructed. Based on the theoretical models, the under-loss absorber HR1 with the peak absorption at 243 Hz, and the HRP and HRM with perfect absorption at 212 Hz and 157 Hz are designed, respectively. The impedance analysis and complex frequency plane method are used to analyze the sound absorption mechanisms of the HR1, HRP, and HRM. The accuracy of the theoretical model is verified by the finite element method. Finally, the three acoustic absorbers are manufactured using 3D printing technology, and the absorption coefficients are evaluated experimentally. The experimental results show that the HR1 has a high working frequency at 245 Hz and a narrow bandwidth of high-efficiency sound absorption ($\alpha >0.8$), which is only 12 Hz. The working frequency of the HRP is 214 Hz, and its high-efficiency sound absorption bandwidth is 54 Hz. The HRP has the lowest working frequency at 157 Hz and the widest high-efficiency sound absorption bandwidth of 58 Hz among the three absorbers. The research results presented in this paper provide a reference for the realization of low-frequency broadband noise attenuation designs and have certain application potential in noise control.

In this paper, we discuss the challenges and limitations of current free-space optical (FSO) networks toward scaling beyond the 100 Gbps switch capacity era while achieving low-latency and high-reliability. Owing to the slowdown of Moore’s law, to avoid electronically-induced bottlenecks, we construct an FSO switch network and experimentally evaluate the feasibility of ultrafast optical packet switch architecture based on polarization-independent plomb lanthanum zirconate titanate (PLZT) switch without buffering. The bit error ratio of 160 Gbps ($16\lambda \times 10$) data was validated based on measurements while still preserving the sub-us latency metrics ($<400$ ns). The experimental results may offer a significant reference for FSO communication and network.

In this paper, higher-order localized waves for a coupled fourth-order nonlinear Schrödinger equation are investigated via a generalized Darboux transformation. The $N$th-order localized wave solutions of this equation are derived via Lax pair and Darboux matrix. Evolution plots are made and dynamical characteristics of the obtained higher-order localized waves are analyzed through numerical simulation. It is observed that rogue waves coexist with dark–bright solitons and breathers. The presented results also show that different values of the involved parameters have diverse effects on the higher-order localized waves.

In this paper, we propose a novel efficient surface reconstruction method from unorganized point cloud data in three-dimensional Euclidean space. The proposed method is based on the Allen–Cahn partial differential equation, with an edge indicating function to restrict the evolution. We applied the explicit Euler’s method to solve the discrete equation, and use the operator splitting technique to split the governing equation. Furthermore, we also modify the double well form to a periodic potential. Then we find that the proposed model can reconstruct the surface well even in the case of insufficient data. After selecting the appropriate parameters, we carried out various numerical experiments to demonstrate the robustness and accuracy of the proposed method. We adopt the proposed method to reconstruct the surfaces on simple, irregular and complex models, respectively, and can obtain smooth three-dimensional surfaces and visual effects. In addition, we also perform comparison tests to show the superiority of the proposed model. Statistic metrics such as the $\sigma$, $d_{max}$, $d_{\mathrm{\text{mean}}}$, CPU time, and vertex numbers are evaluated. Results show that our model performs better than the other methods in statistical metrics even use far less point cloud data, and with the faster CPU computing speed.

In this paper, we study the resonant collisions among different types of localized solitary waves in the (2+1)-dimensional Hirota–Satsuma–Ito equation, which are described by N-soliton solutions constructed using bilinear method. Through the asymptotic analysis and limit treatment of the phase shift of these localized waves, the elastic collisions among different localized waves can be transformed into resonant collisions. Hereby, we study the resonant collision between a breather/ lump and a bright line soliton and find two collision situations: (i) the breather is semi-localized in space and the shape of the breather is not localized during the propagation and (ii) the lump wave generates from the bright line wave. At the same time, we investigate the resonant collision between a breather/lump and two bright line solitons. In these evolution processes, we also gain two dynamical behaviors: (iii) the breather is always localized in space and the shape of the breather is not localized during the propagation, and (iv) the lump wave appears from a bright line soliton and then disappears into the other bright line soliton. Localized wave and interaction solutions of the nonlinear wave models have a great impact on oceanography and physics. The results may be useful in researching the physical phenomena in shallow water waves and nonlinear optics.