[en] In order to investigate the influence of baffles on the mixing effect of particles during ceramic dry granulation process.Air-particles interaction was analyzed by euler gas-solid two phases flow model, the granulation area was simplified.The three dimensional physical model of particles mixing process was constructed, granulation room rotary motion was simulated by sliding grid method and multiple reference frame method, turbulent motion was analyzed by modified RNG discrete model. The influence of different baffles on particles mixing was investigated according to the volume fraction distribution and velocity field, changed the position of the baffle can increase the blending effect by about 22%.The results showed: when there were no baffles, wall baffles and middle baffles in the granulation room, the average volume fraction of powder was about 0.22, 0.18 and 0.26 respectively. The average speed of powder was about 0.6m/s, 0.9m/s and 0.4m/s respectively. The wall baffle made the powder have significant axial movement, the experimental data showed: when granulation room had wall baffles, the content of active particles accounted for about 73%. It is helpful to improve the understanding of gas-solid two phase flow field in ceramic drying granulation room and provide some theoretical guidance for the design and optimization of the baffle. (paper)

[en] We investigate the effects of slight Dy/Mn off-stoichiometry on the multiferroic behaviors of DyMnO₃ (Dy_1−xMn_1+xO₃). It is revealed that the distorted lattice structure and ferroelectric property exhibit higher stability against the Mn deficiency than the Dy deficiency. Since the electric polarization includes the contributions from the Mn-Mn and Dy-Mn interactions, the measured polarization exhibits different dependence on the Mn deficiency from that on the Dy deficiency. The present work suggests that the Dy/Mn off-stoichiometry is detrimental to the ferroelectricity, owing to the modulated spin interactions and reshuffled spin frustration

[en] The multiferroic RMn₂O₅ family, where R is rare-earth ion or Y, exhibits rich physics of multiferroicity which has not yet well understood. DyMn₂O₅ is a representative member of this family. The ferroelectric polarization of DyMn₂O₅ is claimed to be magnetically relevant and have more than one component. Therefore, the polarization reversal upon the sequent magnetic transitions is expected. We investigate the evolution of the ferroelectric polarization upon a partial substitution of Mn³⁺ by nonmagnetic Al³⁺ in order to tailor the Mn³⁺-Mn⁴⁺ interactions and then to modulate the polarization in DyMn_2−x/2Al_x/2O₅. It is revealed that the polarization can be successfully reversed by Al-substitution via substantially suppressing the Mn³⁺-Mn⁴⁺ interactions, while the Dy³⁺-Mn⁴⁺ interactions can sustain against the substitution until a level as high as x = 0.2. In addition, the independent Dy spin ordering is shifted remarkably down to an extremely low temperature due to the Al³⁺ substitution. The present work unveils the possibility of tailoring the Mn³⁺-Mn⁴⁺ and Dy³⁺-Mn⁴⁺ interactions independently, and thus reversing the ferroelectric polarization

[en] We propose a theoretical scheme to implement non-leaky population transfer in a transmon-regime artificial atom. Due to the weak level anharmonicity of the transmon system, resonant driving leads to considerable quantum leakage. Facilitated by the level-transition rule, we develop a Λ-type interaction between the first three levels and the driving fields. Under two-photon resonance with large detuning, a reduced two-level system is obtained, with which we perform non-leaky population transfer by adjusting the microwave driving. With the accessible parameters, we further analyse the flexible reversibility and high robustness of the protocol. The present scheme provides a potential approach to optimizing population transfer with transmon artificial atoms. (letter)

[en] Since the discovery of FRB 200428 associated with the Galactic SGR 1935+2154, magnetars have been considered to power fast radio bursts (FRBs). It is widely believed that magnetars could form by core-collapse (CC) explosions and compact binary mergers, such as binary neutron stars (BNSs), binary white dwarfs (BWDs), and neutron star–white dwarf (NSWD) mergers. Therefore, it is important to distinguish the various progenitors. The expansion of the merger ejecta produces a time-evolving dispersion measure (DM) and rotation measure (RM) that can probe the local environments of FRBs. In this paper, we derive the scaling laws for the DM and RM from ejecta with different dynamical structures (the mass and energy distribution) in the uniform ambient medium (merger scenario) and wind environment (CC scenario). We find that the DM and RM will increase in the early phase, while DM will continue to grow slowly but RM will decrease in the later phase in the merger scenario. We fit the DM and RM evolution of FRB 121102 simultaneously for the first time in the BNS merger scenario and find that the source age is ∼9–10 yr when it was first detected in 2012, and the ambient medium density is ∼2.5–3.1 cm⁻³. The large offsets of some FRBs are consistent with the BNS/NSWD channel. The population synthesis method is used to estimate the rate of compact binary mergers. The rate of BWD mergers is close to the observed FRB rate. Therefore, the progenitors of FRBs may not be unique.

[en] Based on the theory of quantum particle swarm optimization, the calculation method of coal characteristics is integrated. The calculation analysis model and theoretical method are put forward to determine the distribution characteristics of lignite blended coal parameters. The CFB furnace heat transfer model with partitioned section calculation and the overall algorithm of boiler thermal calculation with sequential module iteration are applied to carry out thermal calculation of mixed coal with different proportions of lignite coal and variable conditions. The influence rule of the parameters is analyzed, and the range of reasonable mixing ratio is 50 ∼ 70%. Based on the theory of combustion air dynamics and clean combustion theory, the performance of a large CFB boiler with high proportion of lignite burning is optimized, and the thermal efficiency of the boiler is increased to 90.845%. The power consumption of the integrated plant is reduced to 10.59 - 11.23% (paper)

[en] DyMn_2O_5 is an extraordinary example in the family of multiferroic manganites and it accommodates both the 4f and 3d magnetic ions with strong Dy-Mn (4f-3d) coupling. The electric polarization origin is believed to arise not only from the Mn spin interactions but also from the Dy-Mn coupling. Starting from proposed scenario on ferrielectricity in DyMn_2O_5 where the exchange-strictions associated with the Mn"3"+-Mn"4"+-Mn"3"+ blocks and Dy"3"+-Mn"4"+-Dy"3"+ blocks generate the two ferroelectric sublattices, we perform a set of characterizations on the structure, magnetism, and electric polarization of Dy_1_-_xY_xMn_2O_5 in order to investigate the roles of Dy-Mn coupling in manipulating the ferrielectricity. It is revealed that the non-magnetic Y substitution of Dy suppresses gradually the Dy"3"+ spin ordering and the Dy-Mn coupling. Consequently, the ferroelectric sublattice generated by the exchange striction associated with the Dy"3"+-Mn"4"+-Dy"3"+ blocks is destabilized, but the ferroelectric sublattice generated by the exchange striction associated with the Mn"3"+-Mn"4"+-Mn"3"+ blocks remains less perturbed, enabling the ferrielectricity-ferroelectricity transitions with the Y substitution. A phenomenological ferrielectric domain model is suggested to explain the polarization reversal induced by the Y substitution. The present work presents a possible scenario of the multiferroic mechanism in not only DyMn_2O_5 but probably also other RMn_2O_5 members with strong 4f-3d coupling

[en] Laser-induced forward transfer is a versatile method for the fabrication of surface microstructures. In this paper, the material ejection from copper films induced by nanosecond laser pulses was studied. Two reversely oriented ejections were induced simultaneously by a single laser shot. The opposite ejected droplets were significantly smaller than the direct ejected ones, and were separated from the remnant donor material clearly, which might be utilized to fabricate microstructures on the donor substrates. Three distinct ejection regimes: no ejection, stable ejection and sputtering were characterized with respect to the laser intensity. The thermal field and the phase transition within the donor film were analyzed with a finite element model. Correlations between the phase transitions and the ejection regimes were noticed, suggesting that the material ejection was mainly caused by the cavitation effect. The dynamics of the laser-induced cavitation bump and the formation of the jets were simulated with a vapor–liquid lattice Boltzmann model. The formation of the bump and the material ejections were clearly demonstrated. It was concluded that the jets were mainly induced by the collision of the cumulating flows, which were generated within the bump shell by the asymmetrical cavitation of the bump. The dynamics of the vapor also plays an important role in the development of the jets. The simulation results agree well with the present experimental observations. (paper)

[en] We experimentally compare the probe transmission, four-wave mixing (FWM) and fluorescence signals under dressing effects for the first time. Especially, the interplay between two ladder subsystems is investigated in the Y-type atomic system. Moreover, the two-photon fluorescence signal with ultra-narrow linewidth is obtained, which is much narrower than the Doppler-free electromagnetically induced transparency window. Such fluorescence with very high coherence and monochromaticity can be potentially applied in metrology and quantum correlation

[en] Ion induced electron emission (IIEE) from solid surfaces is one of the fundamental processes with ion beam applications. The different IIEE yields from different surfaces such as Si, SiO₂, metals and photoresist (PR) may cause charging and damage the gate oxide in ion implantation. IIEE yields with B⁺ and Si⁺ beams were measured for several kinds of PR materials, bare and oxide wafers. Although the target chamber pressure was always in or below the low 10^-7 Torr range, the IIEE yield from PR surfaces was found to be a function of implant dose with the most dramatic change in the beginning of implantation. For other materials such as Si and SiO2, the IIEE yield is independent of implant dose after the initial variation due to surface contamination