l. zheng

Computational particle fluid dynamics method is utilized to study the influence of polydisperse and monodisperse particle size distribution, fuel addition, and biomass mixing ratio on the gas-solid flow behavior in a pilot-scale circulating fluidized bed (CFB). Numerical results show that a polydisperse system with different particle sizes can enhance the fluidization quality and the uniformity of the particle volume fraction in comparison with a monodisperse system with uniform particle sizes. When fuel is present in the CFB, the disturbance at the circulation inlet is eliminated and the particle aggregation effect at the wall is reduced. Furthermore, the particle volume fraction, pressure, and particle velocity distributions change only slightly as the biomass increased from 0% to 20% or from 50% to 100% of the total fuel mass. However, as the biomass ratio increases from 20% to 50%, the pressure drop in the riser decreases and the back-mixing degree at the riser wall weakens.

To explore the effect of kilovolt (kV) selection based on body mass index (BMI) on reducing the radiation dose of radiofrequency ablation (RFA) in liver tumours under computed tomography (CT) guidance.

This study retrospectively reviewed CT-guided RFA of liver tumours performed between 1 January 2019 and 31 December 2019. The radiation dose received by the patients was recorded after the planning, execution and surgery. The RFA protocol for liver tumours was subsequently modified according to the patients’ BMI. Changes in tube voltage and tube current were recorded for the RFA protocol based on BMI. The image quality and overall operator satisfaction were recorded for each case based on the BMI-modified protocol. The radiation dose received by the patients was also recorded, and the degree of dose reduction adjusted based on BMI was calculated.

The results showed that the mean (± SD) overall CT dose index (CTDI) of CT-guided RFA was 12.83 ± 3.78 mGy. Following protocol modification, the mean CTDI decreased to 3.84 ± 2.24 mGy, a 70.07% reduction overall. The image quality was slightly lower compared with before the modification, but the image quality in both stages met the needs of CT-guided RFA for liver tumours. Electrode needle display and operator confidence satisfaction showed no significant difference between the groups (P > 0.05).

Modification of the BMI-based kV protocol could significantly reduce the radiation dose received by patients during CT-guided ablation of liver tumours. Furthermore, the image quality was not significantly compromised.

The purpose of this work isto investigate transient aerodynamic characteristics of the coach under the crosswind in straight-line situations with different uniform speeds and uniform accelerations. The transient aerodynamics caused by different speed changes are analyzed using the real-time interaction between aerodynamic simulation and dynamic simulation. The target model is a simplified coach on a full scale. The SST (Menter) K-Omega Improved Delayed Detached Eddy Simulation and overset mesh technique are used to predict the transient aerodynamic loads. The accuracy of the turbulence model is verified by a wind tunnel experiment of the 1/7th scaled coach model. The present results show that the transient aerodynamic loads have different locations of maximum side force and the holding duration of yaw moment for different constant speeds. The speed becomes larger, and the position where the side force is maximum becomes farther away. The holding duration of the top yaw moment is larger simultaneously. Moreover, proper acceleration for low initial driving speed and crosswind of small influence range could build up stability. High speed driving in gust wind is not suggested for unskilled drivers.