Search

In the field of ultrafast magnetism, i.e., subpicosecond or femtosecond time scales, the dynamics of magnetization can be described by the inertial Landau-Lifhitz-Gilbert equation. In terms of this equation, the intrinsic characteristics is investigated in detail for the theoretical limit of the magnetization reversal field. We can find that there is a critical value for the inertia parameter τc , which is affected by the damping and anisotropy parameter of the system. When the inertial parameter factor τ < τc , the limit value of the magnetization reversal field under the ultrafast magnetic mechanism is less than that of the fast magnetic mechanism. When τ > τc , the limit value of the magnetization reversal field will be greater than the limit value under the fast magnetic mechanism. Moreover, it is important to point out that the limit value of the magnetization reversal field under the ultrafast magnetic mechanism decreases with the increasing inertial factor, as τ < τc /2, while increases with inertial factor τ as τ > τc /2. Finally, with the joint action of damping and anisotropy, compared with fast magnetism, we find that the limit value of the magnetization reversal field has rich variation characteristics, i.e., there is not only a linear and proportional relationship, but also an inverse relationship, which is very significant for the study of ultrafast magnetism.

Optical fiber Bragg sensors (FBGs) have great potential in the field of flexible wearable devices for tracking human gestures. Due to different human sizes, different wearable tensions inevitably cause errors when tracking arm joint movements. We have designed a flexible wearable smart sleeve with four heads of FBG and spandex polyurethane fibers (SPFs). SPFs sewn with flexible fabric sleeves convert elbow yawing and wrist pitching and roll into an axial strain of FBG. The measuring system has been developed to deduce personalized sensitivity using a dynamic calibration method. For males and females, dynamic calibration, verification and tracking tests were carried out. From the male’s experimental data, the relative errors between the verification sensitivity and the personalized sensitivity are 1.93%, 5.85% and 7.16%, and the average relative errors between the tracking sensitivity and the personalized sensitivity are 7.09%, 5.58% and 2.52%, respectively. And from the data of the female’s experiment, the relative errors between the verification sensitivity and the personalized sensitivity are 0.25%, 5.0% and 6.75%, and the average relative errors between the tracking sensitivity and the personalized sensitivity are 0.99%, 5.56% and 6.95%, respectively. The experimental data have shown that this wearable smart sleeve and the measuring system work well. The research results can be used to develop FBG sensing systems for monitoring joint movements for different human sizes on-line.

We investigate the spin-related currents and tunnel magnetoresistance through a quantum dot, which is side-coupled with a Majorana fermion zero mode and two thermal-driven ferromagnetic electrodes. It is found that the interplay of Majorana fermion and electrodes’ spin polarization can induce a nonlinear thermal-bias spin current. This interplay also decreases the total magnitude of spin or charge current, in either parallel or antiparallel configuration. In addition, a thermal-driven negative tunnel magnetoresistance is found, which is an unique feature to characterize Majorana fermion. With large temperature difference, a step phenomenon is observed in gate tuned spin-up current. When the coupling between quantum dot and topological superconductor is strong enough, this step will evolve into a linear relation, revealing Majorana fermion’s robustness.

The numerical model of the series isolation structure was established by using the finite element software to simulate the dynamic behavior of the series isolation structure after explosions occurred at different positions, and study the dynamic response and failure mode of the series isolation structure under explosion load. The results show that the vertical displacement and speed of the beams on each floor show a certain regularity with the passage of time. When columns at different positions encounter explosive loads, they will cause local collapse and damage of the structure, and the damage is mainly distributed in the longitudinal and transverse ranges where the columns are located. Compared with the inner column, the structural damage caused by the explosion load on the corner column and side column is more serious.

This paper examined the deformation and the distribution of von-mises stress on the fixed and orbiting scroll. The stress and deformation of the scroll plate has been achieved under thermal load, structural load and thermo-static load. The full process of compression is achieved by the meshing operation of the moving and fixed scroll during the compression process of the scroll compressor. In this process, the teeth of the scrolls are mainly subjected to the combined effect of temperature and gas force resulting in stress and deformation. The performance of the scroll compressor can be affected by the high stress and deformation of the scroll, so it is important to research the scrolls under different field conditions. In this paper we presented the scrolls specification and deformation of oil-free scroll compressor. This study will enable the researcher and designers to improve the workability of the scroll compressor, resulting in a good performance prototype.

The seismic response of a high-pier long-span continuous rigid frame bridge under the action of far-field long-period ground motions is studied. A numerical calculation model of a high-pier long-span continuous rigid frame bridge whose span layout is (95+170+95)m is established by using finite element software. According to the established wave selection criteria, 10 long-period far-field seismic records and 10 ordinary seismic records are selected from the strong earthquake record database. Using the dynamic time history analysis method, the seismic response of the bridge structure under the far-field long-period seismic record and the ordinary seismic record was obtained through calculation, and a comparative analysis was carried out. The results show that the seismic response of a high-pier long-span continuous rigid frame bridge under far-field long-period ground motions is significantly greater than that of ordinary ground motions, the effect of ground motion spectrum characteristics should be considered in seismic design of such Bridges.

Based on the uniform, helical and spiral domain-wall magnetic configurations, the excited spin waves are studied with emphasis on the role of damping. We find that the damping closes the gap of dispersion, and greatly influences the dispersion in the long-wave region for the spin waves of spiral wall and helical structure. For the uniform configuration, the Dzyaloshinskii–Moriya interaction determines the modification of dispersion by the damping. Furthermore, we investigate the interaction between spin waves and a moving spiral domain wall. In the presence of damping, the amplitude of spin wave can increase after running across the wall for small wave numbers. Driving by the spin waves, the wall propagates towards the spin-wave source with an increasing velocity. Unlike the case without damping, the relation between the wall velocity and the spin-wave frequency depends on the position of wall.

Electroluminescence devices based all-inorganic halide perovskite material with the excellent luminescence performance have been studied extensively in recent years . However, the important role for the electrodes of electroluminescence devices is payed few attention by theoretical and experimental studies. Appropriate electrodes can reduce the Schottky barrier height to decrease the energy loss, and prevent the metal impurities from diffusing into the perovskite material to generate deep impurity levels, which improves the luminous efficiency and lifetime of devices. In this paper, not only the interface effects between CsPbBr3 and common metal electrode (Ag, Au, Ni, Cu and Pt) are studied by first-principle calculations, but also the diffusion effects of metal electrode atom into the CsPbBr3 layer are also explored by nudged elastic band calculations. The calculated results show the metal Ag is more suitable for the cathode for CsPbBr3 electroluminescence devices, while the metal Pt is more applicable for the anode. Based on the overall consideration about the interface effects and diffusion effects of the CsPbBr3-metal electrode junctions, the essential principle is analyzed. The work provides theoretical guidance for how to select the right electrode for the electroluminescence performance of all-inorganic halide perovskite. The critical factor of Schottky barrier height between the electrode and the light-emitting semiconductor, and transition level generated by metal impurities also provide a valuable reference how to select the suitable electrodes for other electroluminescence devices.