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The authors analyze the effects of political freedom and personal freedom on the spread of COVID-19 in a cross-country study. The authors also investigate how income inequality, urbanization and previous experience with a similar respiratory epidemic/pandemic, such as SARS and MERS, affect the spread of COVID-19.

The authors employ data from 102 countries to examine the relationship of countries' economic and sociopolitical factors, such as political freedom and personal freedom and their COVID-19 infection cases per million population at 120 days, 150 days and 180 days after the reported 10th infection case. The authors also include the log term of real GDP per capita to control for counties' economic development and regional dummies to control for regional-specific effects.

Results of this study show that personal freedom, rather than democracy, has a significant positive effect on countries' COVID-19 infection cases. On the contrary, democracy has a negative impact on the infection rate. The authors also find that socioeconomic factors such as higher income inequality and urbanization rate adversely affect the COVID-19 infection cases. A larger older population is associated with fewer infection cases, holding everything else equal. Previous experiences with the coronavirus crisis affect countries only at the 120 days mark. Real GDP per capita has no significant effect.

The main contribution of this paper is to jointly explore personal freedom, which implies a social framework with more emphasis on self-value and self-realization and political freedom, that is, democracy. The authors show that it is personal freedom, rather than democracy, that contributes to higher COVID-19 infection cases. Democracy, on the other hand, reduces the number of infection cases.

The peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-12-2021-0769

The purpose of this paper is to combine triboelectric nanogeneration technology with ball bearing structure to achieve energy collection and fault monitoring.

In this paper, according to the rotation mode of ball bearings, the freestanding mode of triboelectric nanogeneration is selected to design and manufacture a novel triboelectric nanogeneration device Rolling Ball Triboelectric Nanogenerator (RB-TENG) which combines rotary energy collection with ball bearing fault self-sensing.

The 10,000s continuous operation experiment of the RB-TENG is carried out to verify its robustness. The accurate feedback relationship between the RB-TENG and rotation velocity can be demonstrated by the fitting comparison between the theoretical and experimental electrical signal periods at a certain time. By comparing the output electrical signals of the normal RB-TENG and the rotor spalling RB-TENG and polytetrafluoroethylene (PTFE) balls with different degrees of wear at 500 r/min, it can be concluded that the RB-TENG has an ideal monitoring effect on the radial clearance distance of bearings. The spalling fault test of the RB-TENG stator inner ring and rotor outer ring is carried out.

Through coupling experiments of rotor spalling fault of the RB-TENG and PTFE balls fault with different degrees of wear, it can be seen that when rotor spalling fault occurs, balls wear has a greater impact on the normal operation of the RB-TENG, and it is easier to identify. The fault self-sensing ability of the RB-TENG can be obtained, which is expected to provide an effective scheme for monitoring the radial wear clearance distance of ball bearings.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2024-0295/