Strengthening and improving ideological and political work in the new era requires educators to take building morality and cultivating people as the fundamental task, sticking to innovation. Based on China's aerospace, this paper designs the ideological curriculum of college physics from a new perspective under the background of the No.1 school of China's aerospace-HIT. From the perspective of China aerospace, the ideological and political design of college physics in HIT is mainly generated from the “three lines” proposed by this paper. Centering on the teaching mode of “X + engineering line”, this paper presents two practical cases of ideological and political practice in the courses of gas, electromagnetism and quantum mechanics, which leads to a broader path for the design of ideological and political courses of college physics.
- Article type
- Year
- Co-author
In the genre of aerospace, the transition of the boundary layer always seems to be a problem that limits the aerodynamic performance of a wing. Thus, an increasing number of experiments and researches are working on optimizing the airfoil to dilute the turbulence. Based on the NACA4412 airfoil, in this paper, a new type of airfoil, sunken trailing edge airfoil, is proposed and tested by means of the Flow Simulation unit of SOLIDWORKS. And it has been verified that the new airfoil has the superior aerodynamic performance compared to the original airfoil by a large number of simulation experiments. The lift drag ratio gain of the sunken trailing edge airfoil is systematically discussed with different shapes, wind speeds, and angles of attack. The research data show that when the sunk depth is around naught and the length is about one third of the chord, sunken trailing airfoil produces the greatest lift-drag ratio increase, which can be up to 60% more than the prototype's in mid-speed flow field. Thus, this study brings a new way to design an airfoil of medium and low speed aircraft, increasing load while improving energy utilization.
The barium ferrite BaTixFe12-xO19 (x = 0.2, 0.4, 0.6, 0.8) (BFTO-x) ceramics doped by Ti4+ were synthesized by a modified sol-gel method. The crystal structure and magnetic structure of the samples were determined by neutron diffraction, and confirm that the BFTO-x ceramics were high quality single phase with sheet microstructure. With x increasing from 0.2 to 0.8, the saturation magnetization (Ms) decreases gradually but the change trend of coercivity (Hc) is complex under the synergy of the changed grain size and the magnetic crystal anisotropy field. Relying on the high valence of Ti4+, double resonance peaks are obtained in the curves of the imaginary part of magnetic conductivity (μ′′) and the resonance peaks could move toward the low frequency with the increase of x, which facilitate the samples perform an excellent wideband modulation microwave absorption property. In the x = 0.2 sample, the maximum reflection loss (RL) can reach -44.9 dB at the thickness of only 1.8 mm, and the bandwidth could reach 5.28 GHz at 2 mm when RL is less than -10 dB. All the BFTO-x ceramics show excellent frequency modulation ability varying from 18 (x = 0.8) to 4 GHz (x = 0.4), which covers 81% of the investigated frequency in microwave absorption field. This work not only implements the tunable of electromagnetic parameters but also broadens the application of high-performance microwave absorption devices.
Multiferroic BiFeO3-based ceramics were synthesized using the rapid liquid-phase sintering method. The rare-earth ion (Sm3+, Gd3+, Y3+) doping causes structural distortion without changing the intrinsic rhombohedral perovskite structure. Raman analysis shows that the effect of doping on E modes is greater than A1 modes, and the microstructure of FeO6 octahedron can be regulated by ion doping. A-site trivalent ion doped ceramics exhibit improved magnetism compared with pure BiFeO3 ceramic, which originated from the suppressed spiral spin structure of Fe ions. The tilt of FeO6 octahedron as a typical structure instability causes the anomalous change of the imaginary part of permittivity at high frequency, and doped ceramics exhibit natural resonance around 16-17 GHz.
Bismuth ferrite (BiFeO3)-based materials are multiferroic materials widely studied. This study reports that strong ferroelectricity and enhanced magnetic performance are simultaneously obtained in the quenched (1-x)BiFeO3-xBaTiO3 (BFBT100x, x = 0.2 and 0.3) ceramics. Quenching treatment can reduce the amount of defects and Fe2+ ions and make the defect dipole in a random state, which is conducive to improving the ferroelectricity and magnetism. Compared with the conventional sintered samples, the quenched ceramics have higher remnant and saturation polarization. As for magnetism, the coercive field (Hc) of the quenched ceramics is smaller and the quenching treatment can increase the maximum magnetization by up to 15%.