Behaviors of photovoltaic cells illuminated by a laser of different operation modes.

The ultimate capability of light-electricity conversion of a laser with different operation modes in a typical photovoltaic (PV) cell was investigated for the technologic concept of laser power transmission (LPT). The quasi-linear correlation between the maximum allowable laser power density and the pulsed laser power percentage (PPP) of the combined dual lasers was found experimentally on a tri-junction GaAs PV cell. At the same time, the patterns of thermomechanical damage in the PV cells were characterized. The physical mechanism on the difference in the light-electricity conversion ability for a multi-pulse (MP) laser and a continuous wave (CW) laser was revealed by the coupled model on thermal diffusion and the carrier transport.

Invariant in variants.

The coronavirus Covid-19 mutates quickly in the pandemic, leaves people struggling to verify and improve the effectiveness of the vaccine based on biochemistry. Is there any physical invariant in the variants of such kind of pathogen that could be taken advantage to ease the tensions? To this point, extensive numerical experiments based on continuity mechanics have been accomplished to discover the consistent vibration modes and the range of natural frequency of coronavirus Covid-19. Such invariant could help us in developing some flexible technique to deactivate the coronavirus, like as resonantly breaking the viral spike by ultrasound wave. The fundamental mechanisms governing such process are demonstrated via solving the coupled acoustic wave and elastic dynamic equations, after which the practical strategies are proposed to efficiently realize the technique concept.

Microstructure Dependence of Effective Thermal Conductivity of EB-PVD TBCs.

Microstructure dependence of effective thermal conductivity of the coating was investigated to optimize the thermal insulation of columnar structure electron beam physical vapor deposition (EB-PVD coating), considering constraints by mechanical stress. First, a three-dimensional finite element model of multiple columnar structure was established to involve thermal contact resistance across the interfaces between the adjacent columnar structures. Then, the mathematical formula of each structural parameter was derived to demonstrate the numerical outcome and predict the effective thermal conductivity. After that, the heat conduction characteristics of the columnar structured coating was analyzed to reveal the dependence of the effective thermal conductivity of the thermal barrier coatings (TBCs) on its microstructure characteristics, including the column diameter, the thickness of coating, the ratio of the height of fine column to coarse column and the inclination angle of columns. Finally, the influence of each microstructural parameter on the mechanical stress of the TBCs was studied by a mathematic model, and the optimization of the inclination angle was proposed, considering the thermal insulation and mechanical stress of the coating.