Background: A variety of viruses can cause acute respiratory infections (ARIs), resulting in a high disease burden worldwide. To explore the dominant viruses and their prevalence characteristics in children with ARIs, comprehensive surveillance was carried out in the Pudong New Area of Shanghai.Methods: Between January 2013 and December 2022, the basic and clinical information, and respiratory tract specimens of 0–14 years old children with ARIs were collected in five sentinel hospitals in Shanghai Pudong. Each specimen was tested for eight respiratory viruses, and the positive rates of different age groups, case types (inpatient or outpatient) were analyzed.Results: In our study, 30.67% (1294/4219) children with ARIs were positive for at least one virus. Influenza virus (IFV) was the most commonly detected respiratory virus (349/4219, 8.27%), followed by respiratory syncytial virus (RSV) (217/4219, 5.14%), para‐influenza virus (PIV) (215/4219, 5.10%), and human coronavirus (HCoV, including 229E, OC43, NL63, and HKU1) (184/4219, 4.36%). IFV was the leading respiratory virus in outpatients aged 5–14 years (201/1673, 12.01%); RSV was the most prevalent respiratory virus in both inpatients (61/238, 25.63%) and outpatients (4/50, 8.00%) for ARI patients aged <6 months old. For PIV, HMPV, HCoV, and HRV, the risk of infection usually was higher among young children. Co‐infection with more than two viruses was seen in 3.25% (137/4219).Conclusions: IFV and RSV played important roles in ARIs among children, but the risk populations were different. There are needs for targeted diagnosis and treatment and necessary immunization and non‐pharmaceutical interventions.

Alternating current rotating gliding arc discharge can produce large-scale, wide-range non-equilibrium plasma at atmospheric pressure. In order to investigate the gliding discharge mode, discharge characteristics and Spectral characteristics of AC rotating gliding arc discharge plasma, high speed camera, oscilloscope and spectrometer are used to collect discharge images and electrical signals of rotating gliding arc synchronously. Thus the dynamic behavior of arc and the characteristics of electric signal in the process of rotating gliding arc can be analyzed. The experimental results show that there are two different discharge modes in the rotating gliding arc discharge process, namely the breakdown gliding discharge mode (B-G mode) and the stable gliding discharge mode (A-G mode). The B-G mode is mainly characterized by high-frequency breakdown phenomenon (breakdown-extinguish-breakdown) during the arc gliding process, while the A-G mode is mainly characterized by stable continuous arc sliding. The paper also discusses the working mechanism in which the working parameters influence the gliding arc discharge characteristics. It is shown that the discharge mode and discharge characteristics of arc are the result of the combined action of excitation voltage and gas flow. When the gas flow is large and the excitation voltage is small, the gliding arc is an unstable discharge dominated by the B-G mode. Conversely, when the excitation voltage is large and the gas flow is small, the gliding arc is a stable gliding discharge dominated by the A-G mode. In addition, in B-G mode, the energy consumption is mainly concentrated in the breakdown moment, and the energy release is mainly pulsed. However, when the gliding arc discharge is in A-G mode, the energy dissipation is mainly used to maintain the continuous existence of the arc without extinguishing, and the energy release is stable and continuous. Affected by the gas flow rate and excitation voltage, the breakdown frequency of the B-G mode is greater than that of the A-G mode. Higher repeat breakdown frequency can cause multiple ionization in the process of gliding arc discharge, which produces more active particles. The research conclusions in this paper provide theoretical support for regulating the operating characteristics of the gliding arc discharge. In engineering application, the discharge mode, breakdown frequency and breakdown current of the gliding arc can be adjusted by changing the working parameters to obtain plasma sources with different characteristics.

Ar, N₂, O₂, and N₂-O₂ mixture under different O₂ components were separately used as the working medium gas of a plasma igniter to study the influence of working-medium-gas type and O₂ concentration on emission spectral and temperature characteristics of a direct-current arc plasma igniter. The emission spectra of the plasma jet were also analyzed using the optical emission spectroscopy method, and the influence rule of working medium gas and O₂ concentration on electron temperature and vibrational temperature of the plasma jet was calculated and analyzed. The experimental results show that the emission spectra of the plasma jet had significant differences when diverse working gases were used as the working medium of the igniter. With increasing O₂ concentration in the working medium gas, the spectral line intensity of oxygen-containing particles in emission spectra of the plasma jet was significantly enhanced, and the spectral intensities of nitrogen-containing particles, NO molecular bands, the second positive system of N2C3∏u−B3∏g, and the first negative system of N2+B2∑u+−X2∑u+ were also enhanced obviously. Both electron and vibrational temperature of the plasma jet increased gradually with increasing O₂ concentration in the working medium gas, and first increased and then decreased with increasing axial distance from the plasma jet.

Microwave plasma can improve the performance of ignition and combustion, as well as reduce pollutant emissions. By designing a novel microwave feeding device, the combustor can be used as a cavity resonator to generate microwave plasma and improve the performance of ignition and combustion. In order to feed the energy of microwave into the combustor as much as possible, and effectively adapt to the change in resonance frequency of combustor during ignition and combustion, the combustor was designed and manufactured by optimizing the size of slot antenna and setting the tuning screws, according to the simulation results of HFSS software (version: 2019 R 3). The relationship between the size, position of metal tip in the combustor and the discharge voltage was studied using HFSS software, as well as the interaction between ignition kernel, flame and microwave. The resonant characteristics of combustor and the discharge of microwave-assisted igniter were subsequently studied via experiments. The results show that the combustor as microwave cavity resonator has a wider resonance curve and can adapt to the change in resonance frequency during ignition and combustion. It is also indicated that microwave can enhance the discharge development of igniter and increase the discharge size. Based on this, the electric and magnetic field effects of microwave are decoupled.