The Effect of COVID-19 on the Efficiency of Intercity Bus Operation: The Case of Chungnam

This paper estimates the efficiency of operating intercity bus lines in Chungnam province over the period 2017–2020, and then empirically analyzes the determinants of the efficiency. In particular, it evaluates to what extent the efficiency in 2020 decreased due to COVID-19 and which characteristics of lines (length of a line, frequency of operation, whether a line operates via highways and includes the capital region or not) affected the efficiency during the pandemic through a tobit model. The empirical results show that the efficiency in the operation of intercity bus lines in Chungnam was higher in 2018 and 2019 compared to 2017, but dropped in 2020 by 15.8%. It appears that the efficiency is higher when a line operates more frequently and covers a longer distance, but the efficiency increases at a decreasing rate as the operating distance becomes longer. In addition, the difference in the efficiency according to operating distance due to COVID-19 seems to be statistically significant. Given that intercity bus lines are heavily dependent upon a (local) government’s financial support and the amount of this support needs to reflect the degree to which the efficiency has decreased due to COVID-19 as an external shock, it is important to precisely estimate the magnitude of the efficiency reduction from both a policy and academic standpoint.

Common-Mode Voltage Reduction in Capacitive Sensing of Biosignal Using Capacitive Grounding and DRL Electrode

A capacitive measurement of the biosignals is a very comfortable and unobtrusive way suitable for long-term and wearable monitoring of health conditions. This type of sensing is very susceptible to noise from the surroundings. One of the main noise sources is power-line noise, which acts as a common-mode voltage at the input terminals of the acquisition unit. The origin and methods of noise reduction are described on electric models. Two methods of noise removal are modeled and experimentally verified in the paper. The first method uses a passive capacitive grounding electrode, and the second uses an active capacitive Driven Right Leg (DRL) electrode. The effect of grounding electrode size on noise suppression is experimentally investigated. The increasing electrode area reduces power-line noise: the power of power-line frequency within the measured signal is 70.96 dB, 59.13 dB, and 43.44 dB for a grounding electrode area of 1650 cm2, 3300 cm2, and 4950 cm2, respectively. The capacitive DRL electrode shows better efficiency in common-mode noise rejection than the grounding electrode. When using an electrode area of 1650 cm2, the DRL achieved 46.3 dB better attenuation than the grounding electrode at power-line frequency. In contrast to the grounding electrode, the DRL electrode reduces a capacitive measurement system’s financial costs due to the smaller electrode area made of the costly conductive textile.

Dynamics of electric and magnetic fields in case of the urban environment

This paper studies the temporal dynamics of power-line frequency electric and magnetic fields in Saint-Petersburg and environs. It is found that electromagnetic fields generated by high-voltage transmission lines (HVTL) constantly change, depending on their loading and weather conditions. The dependence on weather conditions involves both the direct effect of air electrical conductivity as a function of its humidity, and indirect effects including the dependence of energy consumption on temperature and also the correlations between meteorological characteristics. An attempt has been made to evaluate the role of influencing factors.