Clearance joints can reduce motion accuracy and shorten service life for high-voltage circuit breakers, and they are a significant source of mechanical faults. For clearance joint fault diagnosis, the anti-interference ability is important. However, robustness is rarely analyzed in current studies of fault diagnosis of high-voltage circuit breakers. Most conventional diagnosis models are based on individual classifiers with poor robustness, and their performance highly depends on expert prior information. In this paper, a novel Dempster ̶ Shafer multiple echo state network (DS-MESN) is proposed to enhance the model accuracy and robustness of fault diagnosis. First, energy distributions in intrinsic mode functions by variational mode decomposition are considered as the inputting vector for diagnostic model training and testing. Then, multiple echo state network modules with different network parameters are adopted as subclassifiers, and their diagnostic outputs are fused by DS evidence theory. The DS-MESN can compromise the performance of multiple echo state network modules, making its performance more stable and objective. The superiority of the reported methodology is demonstrated by experimental data from a real ZN12 high-voltage circuit breaker.

In this work, the reduced iron powders were phosphated to form ferrous phosphate insulating layer on their surface. Then the iron based soft magnetic composites (SMCs) were prepared successfully by powder metallurgy and annealing process. The presence of insulating layer decreased the eddy current loss of iron powders. Furthermore, the effect of the annealing process on magnetic performance was investigated. The appropriate annealing temperature and holding time were carried out in this work. The samples were annealed in a N 2 atmosphere from 550 to 650 10 to 30 min. According to the results, the phosphated iron based SMCs that were annealed in a N 2 atmosphere at 600 15 min of holding time had the satisfying magnetic properties. It has a high resistivity () of 0.017 3 •cm, a high saturated magnetic flux density (B s) of 1.408 T, a high maximum permeability (m) of 263, a low coercivity (H c) of 197 A/ m and a low core loss (P s) of 119.70 W/kg at 1 000 Hz (B m =1 T).

Diesel engine combustion is dependent mainly on the fuel injection characteristics, particularly the injection pressure and rate, which directly affect the engine efficiency and emissions. Herein, an electrically controlled supercharger is added to a traditional high-pressure common rail system to form an ultrahigh-pressure common rail system. Then, the variations in the spray, combustion, and emission characteristics of a diesel engine with a variable fuel injection rate are analyzed. Moreover, a simulation model for a diesel engine combustion chamber is built and verified by experimental results for numerical analysis. The results reveal that the injection rate can be flexibly adjusted via regulation when the solenoid valves are opened on the electrically controlled supercharger. Specifically, (1) the boot-shaped injection rate has greater potential than the traditional rectangular injection rate in terms of combustion and emission; (2) the main injection advance angle at the boot-shaped injection rate can be properly increased to improve combustion; and (3) the pilot injection quantity and advance angle are strongly coupled with the boot-shaped injection rate, potentially enhancing the mixing efficiency of fuel and air in the cylinder to achieve favorable emission results. This paper provides good guidance for the reliable design and optimization of noble-metal-based diesel engines.

The dynamic characteristics of operating mechanisms are of great significance to the reliability of high-voltage circuit breakers (HVCBs). To achieve dynamic analysis and optimization design of HVCBs, this paper presents a reduced-order digital twin model for a 252 kV HVCB under the OpenModelica simulation platform. To validate the effectiveness of the model, simulated closing and opening stroke curves are compared with experimental results, demonstrating the high efficiency and accuracy of the reduced-order digital twin model. Furthermore, a simulation analysis is performed to examine the mechanical dynamics of the HVCB under potential fault conditions, such as abnormal spring driving force. The analysis reveals that a reduction in the preload of the closing spring slows the operating mechanism’s movement, increases closing time, and may even cause closing failure. Similarly, a decrease in the preload of the opening spring reduces the moving contact’s speed, prolongs the opening time, and may result in opening failure. The proposed digital twin modeling method offers designers a systematic method for quantifying the dynamic responses of HVCBs.

For underwater vehicles navigating in Arctic Sea ice-covered waters, fatigue damage is a crucial issue. Many scholars have conducted low-temperature fatigue analysis on low-temperature materials and substrate platforms for ships, and the results show that low temperature is beneficial for improving the mechanical properties of materials. However, they have mainly focused on low-temperature performance experiments and simulation analysis of standard components of materials, and there are very few fatigue life experimental studies on underwater vehicle mechanical structures. This paper conducts experimental investigations on a scaled model of an underwater vehicle rudder mechanism in a polar environment laboratory. Using a comparative analysis method involving simulations and experiments, the low-temperature fatigue test data of the scaled underwater vehicle rudder mechanism are analyzed, and the quantified analysis between fatigue and different low-temperature loading cycles, as well as the influence of icing on the fatigue life, is explored. It is indicated that the Arctic environment can decrease the fatigue life of the underwater vehicle rudder mechanism by deteriorating its material properties. The paper builds the foundation for the fatigue life of an underwater vehicle rudder mechanism in Arctic low-temperature environments.