Changjie Zhou

Two-dimensional (2D) WS2 films were deposited on SiO2 wafers, and the related interfacial properties were investigated by high-resolution x-ray photoelectron spectroscopy (XPS) and first-principles calculations. Using the direct (indirect) method, the valence band offset (VBO) at monolayer WS2/SiO2 interface was found to be 3.97 eV (3.86 eV), and the conduction band offset (CBO) was 2.70 eV (2.81 eV). Furthermore, the VBO (CBO) at bulk WS2/SiO2 interface is found to be about 0.48 eV (0.33 eV) larger due to the interlayer orbital coupling and splitting of valence and conduction band edges. Therefore, the WS2/SiO2 heterostructure has a Type I energy-band alignment. The band offsets obtained experimentally and theoretically are consistent except the narrower theoretical bandgap of SiO2. The theoretical calculations further reveal a binding energy of 75 meV per S atom and the totally separated partial density of states, indicating a weak interaction and negligible Fermi level pinning effect between WS2 monolayer and SiO2 surface. Our combined experimental and theoretical results provide proof of the sufficient VBOs and CBOs and weak interaction in 2D WS2/SiO2 heterostructures.

In case of wildfire, particles generated in combustion are in complex law of motion under the influence of flame temperature, airflow and lots of electrons and ions. They would distort the space electric field, and lead to gap discharge. This paper develops a multi-physics coupling calculation model of fluid, temperature, electric field and particle movement by combining the rod-plate gap experiment that simulates the wildfire condition. It analyzes the motion state of ash particles in flames, studies the charged particles of different polarity separately, and explores the impact of particle properties on the electric field of gap space by combining the distribution of particles. Results have shown that there are differences in the motion state of charged particles of different polarity, and the electrode will absorb some particles with different charges, while charged particles with the same polarity as the electrode will move away from the electrode in random motion. Particles of different properties (particle size, relative dielectric constant) have different impacts on the electric field of gap space, but they all promote the discharge propagation.

It is the inherent feature that high-voltage electrical equipment produces electric field around it. In this paper, a wearable intelligent warning system based on electric field measurement is proposed to prevent the staff from being electrocuted or entering the area with high field intensity. In order to meet the requirements of lightweight, stable, and anti-jitter for wearable measurement, the electric field sensor with double spherical shell structure is chosen to be the core of the warning system, and the subsequent signal processing system has been developed. Furthermore, the influence of human body on the electric field measurement has been studied by simulation, and the appropriate wearing position of measuring instrument has been determined considering factors such as accuracy, convenience, and safety of measurement. Then, some experiments have been conducted to test the performance of the developed measuring instrument. In the accuracy verification experiments, the measurement results of the developed instrument are close to those of the commercial measuring instrument for comparison, and the maximum relative error is within 6%. In the experiments under human body influence, the measurement results of the developed instrument are stable, but those of instrument for comparison fluctuate greatly. As the arm swings, the coefficient of variation of the measurement result does not exceed 6%, which proves that it is suitable for mobile measurement. The simulation and experiment results verify that the developed wearable electric field measuring instrument has satisfactory performances to be used in the safety warning system for approaching high-voltage electrical equipment.