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The extraction of current characteristics from the opening and closing coils is a crucial method for monitoring the state of high-voltage circuit breakers. Based on the waveform patterns of the opening and closing coil currents in high-voltage circuit breakers， the paper investigates a corner point extraction method of current waveform based on local thresholds of curvature scale space （CCS）. Subsequently， the characteristic curves of current at actual corner points are used to precisely monitor the mechanical state of high-voltage circuit breakers. Calculations based on the measured opening and closing coil currents from high-voltage circuit breakers in a specific substation indicate that the proposed local threshold method of the CCS can accurately identify the waveform features of the opening and closing coil currents. The mechanical state monitoring of high-voltage circuit breakers based on the characteristic curves of opening and closing coil currents shows excellent results. The research findings can provide crucial references for the mechanical state monitoring of high-voltage circuit breakers.

The present switching speed measurement devices for circuit breakers are mostly low in accuracy， severe on installation conditions， and cannot achieve real-time online monitoring. A new system for real-time switching speed measurement of circuit breakers based on a line array camera is proposed. First， the experimental technique is studied by building an experimental frame simulating the rotation of circuit breakers. A turntable is installed at the output of the motor to simulate the rotating shaft of the circuit breaker actuator， and a line array camera is placed on the turntable side to capture the black and white narrow strip images of the targets set on the turntable. Afterward， the appropriate resolution， exposure time and judgment threshold are chosen to analyze the changes of the images taken by the line array camera in real time to obtain the real-time motion travel of the target and the rotation speed of the turntable. The switching speed of the circuit breaker is obtained to verify the feasibility of the measurement scheme. Finally， it is applied to a pilot substation to monitor the motion travel of the switching of the circuit breaker in real time. Compared with the existing technology， this measurement system can process the images more quickly and measure the switching speed more precisely and stably.

In this work, the adsorption of SF6 decomposition products (SO2, SOF2, and SO2F2) on Ru–MoTe2 monolayer is investigated based on density‐functional theory (DFT) calculations. The doping structure, band structure, adsorption structure, adsorption energy, charge transfer, density of states (DOS), and molecular orbital are analyzed to better analyze the interaction mechanism between gas molecules and Ru–MoTe2 system. In the results, it is shown that the conductivity of MoTe2 monolayer can be greatly increased by doping Ru atom. Pristine MoTe2 shows a weak adsorption capacity for SO2, SOF2, and SO2F2 gases, which belongs to physical adsorption. When Ru atom is doped on MoTe2, the adsorption capacity of the doping system for these three gases is obviously improved. The adsorption capacity of Ru–MoTe2 monolayer to the gases is ranked as SO2F2 > SOF2 > SO2. Moreover, the strong interaction between gas molecules and Ru–MoTe2 surfaces leads to the rise of the conductivity of all adsorption systems to varying degrees, and the degree of the rise of conductivity influenced by gas molecules is ranked as SO2F2 > SO2 > SOF2. Herein, a theoretical basis for the preparation of gas sensors or adsorbers based on Ru–MoTe2 is provided for detecting and absorbing SF6 decomposition products. [ABSTRACT FROM AUTHOR]

Background: Chronic kidney disease (CKD) patients commonly report muscle weakness and fatigue. Losing muscle mass increases mortality. Accordingly, we aimed to determine the main factors associated with loss of muscle mass and muscle weakness. Methods: Anthropometric measurements were made in CKD patients attending a specialised clinic, along with hand grip strength (HGS), pinch strength (PS) and body composition (muscle mass and fat mass), using segmental bioimpedance assessment. Results: We reviewed the results of 161 CKD patients; 105 male (65.2%), mean (SD) age 70.3 (15) years, body mass index (BMI) 28.8 (6.7) kg m−2. In multivariable models, both HGS and PS were independently negatively associated with age [standardised β (St β) = 0.35; 95% confidence limits (CL) = −0.32 to −0.14; St β = 0.38; 95% CL = −0.65 to −0.02; P < 0.001, respectively] and positively with appendicular muscle in the arm tested [St β = 0.34; 95% CL = 2.5–6.3; St β = 0.24; 95% CL = 0.17–0.98; P < 0.001 and P = 0.006, respectively]. In addition, HGS was associated with male gender (St β = 0.19; 95% CL = 0.7–7.5; P = 0.019] and negatively with percentage body fat (St β = 0.22; 95% CL = −0.36 to −0.07; P = 0.003]. There were 47 (29.2%) Asian patients who had lower total skeletal muscle mass/height ratio and appendicular muscle mass/BMI ratio compared to other ethnicities [9.6 (1.8) versus 10.5 (1.6) kg m−2, P < 0.01; 0.73 (0.23) versus 0.83 (0.33) m2; P < 0.01). Conclusions: In CKD patients, we found that muscle weakness measured by HGS and PS was associated with increasing age and loss of appendicular muscle mass. HGS was also weaker with increasing fat mass and female gender, whereas PS was weaker in patients of Asian ethnicity. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were used to analyze the internal mechanism for the observed improvement in performance of nano-modified meta-aramid insulation paper from a microscopic point of view. The results showed that the k-polyphenylsilsesquioxane(PPSQ) modified meta-aramid insulation paper was superior to b-PPSQ modified meta-aramid insulation paper in terms of its thermal stability and mechanical and electrical properties. The analysis of microscopic parameters showed that the stiffness of k-PPSQ was less than that of b-PPSQ, and the hydroxyl groups on the open-loop system were more likely to enter the dispersed system, resulting in higher bonding strength, meta-aramid fiber chains between k-PPSQ molecules, and the formation of hydrogen bonds. Additionally, the nano-enhancement effects of k-PPSQ and b-PPSQ resulted in various improvements, including a reduction in pores between molecules in the blend model, an increase in the contact area, the formation of interfacial polarization, and a reduction in defects at the interface. [ABSTRACT FROM AUTHOR]