r. li

Deep-sea slurry pump is a crucial component for achieving vertical transportation of ore particles in pump-pipe lifting deep-sea mining systems. However, traditional mining pump structures face challenges, such as insufficient particle flow capacity and blockage susceptibility, which affect the slurry pump's operational stability. This study introduces a novel deep-sea slurry pump design that incorporates the non-clogging structural characteristics of a screw mixed flow impeller combined with a diffuser. The pump flow capacity was evaluated using the CFD-DEM (Computational Fluid Dynamics - Discrete Element Method) coupling method for transporting 10 mm spherical particles at various flow rates. The motion patterns and non-uniform distribution characteristics of particles were analyzed qualitatively and quantitatively within the pump under different inflow conditions. The proposed pump demonstrated a robust coarse particle overflow capacity for varying particle transport states and unequal particle distribution among flow components. The particle quantity changed consistently throughout the transportation process and was divided into a growth phase and a stable phase. The main flow components exhibited a dynamic non-uniform particle flow with a more pronounced periodic nature in the impeller channel. The degree of non-uniform particle flow in the diffuser channel was inversely related to the flow rate， and was higher compared to the impeller channel.

Helical axial-flow multiphase (HAFM) pumps experience intermittent gas-blocking events, which negatively impact performance and threaten the stability of the overall pump and pipeline systems. This study applies jet flow field method to HAFM pumps. Active intervention in the gas-liquid separation process, utilizing external energy, results in the reorganization of the flow field within HAFM pumps. The effect of jet location on improving the efficiency of HAFM pumps is assessed, with a focus on the active flow control mechanism through jet influence. The study indicates that the region sensitive to jet site distribution affecting pump performance is 0.5Lc ≤ xr ≤ 0.7Lc, while the weakly sensitive region is 0.15Lc ≤ xr ≤ 0.5Lc. When xr ≤ 0.15Lc, the improvement in head and efficiency under high gas content conditions is reduced. Jet flow field control technology obviously decreases the gas phase accumulation in the downstream flow channel of the moving blade cascade. The optimal position for reducing gas phase agglomeration in the impeller channel is 0.3Lc. The jet site arrangement significantly affects the pressure structure near the cascade trailing edge. Appropriate jet hole positioning significantly improves the pressure structure at the cascade trailing edge, decreases reflux caused by separation vortices at the impeller outlet, and enhances the hydraulic performance in the multiphase pump.

Understanding the kinetic behavior at the scale of a single bubble is crucial for understanding cavitation flow properties. In this study, experiments and numerical analysis of shock waves resulting from the crumpling of a solitary adjacent wall vacuole have been conducted. Shock wave characteristics induced by near-wall bubble collapse were investigated using high-speed photography and shadowgraphy techniques. Numerical simulations were conducted of near-wall vacuole collapse-induced shock-wave dynamics using the OpenFOAM cavitatingFoam solver. (1) The shock wave displays an essentially symmetrical distribution. The pressure maxima diminished along the sagittal diameter. The intensity of the second shock wave generated near the wall was decreased by approximately 21.2% compared to the initial shock wave. The simulated wave speeds exhibit a high level of concordance with the experimental data, and the calculated errors are below 7.9%. (2) The pressure and velocity at which the shock wave propagates in water exhibit a power function and an exponential decay function, respectively, as they travel across distance. And the perturbation profile of the velocity aligned with the direction in which the shock wave propagated. This result indicates that the shock wave acts as a catalyst for the creation of disturbances in the velocity field. (3) Constructing a transformation relation for the wave energy of near-wall vacuole collapse. During its first collapse, the near-wall cavitation bubble lost an average of 85% of its energy. This allowed for the assessment of the erosive impact of cavitation-induced shock waves on rigid surfaces.

In order to investigate the influence of plasma actuation on cavitation in the flow field around a hydrofoil, the RNG k-ε turbulence model with density correction, the Schnerr–Sauer cavitation model, and the plasma phenomenological model were used to analyze the influence of forward and reverse plasma actuation on the cavitation characteristics of the NACA66(MOD) hydrofoil at an angle of attack of 8. The cavitation number of the incoming flow was 0.99. The results showed that under the positive excitation condition, the cavitation volume on the suction side of the hydrofoil was reduced by about 30%, and the time-averaged lift–drag ratio was reduced by about 5%, which had little influence on the re-entrant jet, vortex and shear flow. Therefore, the cavitation suppression effect on the hydrofoil flow field was weak. Under the condition of reverse actuation, the volume of cavitation on the suction side of the hydrofoil was reduced by about 87%, and the time-averaged lift–drag ratio was increased by about 21%, which effectively worsened the development conditions of cavitation. By greatly reducing the intensity of the re-entrant jet and eliminating the vortex and shear flow in the flow field, cavitation in the hydrofoil flow field was obviously suppressed. This shows that reasonable plasma actuation is an effective means to control hydrofoil cavitation.

The existence of correlates between radiation and plasma metabolites in rats might be affected by feeding conditions.

The rats were kept without food and water for a certain time before the blood was harvested on the seventh day after X-ray irradiation at doses of 0 and 8 Gy. The plasma metabolites were tested using Enzyme-Linked Immunosorbent Assay (ELISA).

Our results showed that abrosia for 2 h before blood harvesting could increase the level of detections of both interleukin-6 (IL-6) and glycine (Gly) in rats. Furthermore, abrosia and meanwhile water deprivation for 2-4 h increased better the level of detections of IL-6 and Gly in rats.

The level of detections of biomarkers in the blood may be more authentic and can better reflect the changes in the experimental animals after stress when they are treated by both abrosia and water deprivation for 2 h before blood harvesting.

The head shape of a high-speed maglev train was optimized in this study, based on the adjoint method, and the aerodynamic drag of four optimized train models were simulated and compared using different control point generation methods. The effectiveness of using the adjoint method to develop a compressible model for a maglev train was verified. The results show that the adjoint matrix optimization method can quickly and effectively capture the shape characteristics of the train head that are sensitive to aerodynamic resistance. When the design variables of the head are not defined separately, the grid control point set and surface control point set can be used to carry out the adjoint closed-loop optimization of the train head shape, and the exchange control point generation method can be used to perform closed-loop optimization. The results of a numerical simulation show that the optimized train model reduces aerodynamic resistance by approximately 4.8%.

Erosion wear of the centrifugal pump impeller are the key issues since its operating in sediment-laden flow. Experiment and numerical method are adopted in this study to investigate the erosion wear of the impeller in a double-suction pump in the Jingtai Yellow River Irrigation Project (JYRIP). Observation during operation combined with morphology study is carried out to verify erosion mechanisms at the different sections of the impeller blade. For numerical study, the Eulerian-Lagrangian approach combined with the Mclaury model is employed to predict the trajectories of the particles under different particle parameters. Also the effects of particle size and concentration on impeller erosion wear is studied. Numerical results are consistent with experimental data. The surface wear of the blade changes obviously from circular shape to strip shape in the direction from the Leading Edge (LE) to the Trailing Edge (TE), and the wear damage area increases correspondingly. Trajectories of larger particles are more uniform and tend to cause more severe erosion wear damage. The wear damage tends to be slow after the particle size increases to a certain extent under the same sediment concentration. Besides, erosion rate increases with an increase in sediment concentration, and the erosion rate of the suction side is greater than the pressure side at the same position of the blade surface. These results can offer a good reference for the design of wear resistance impeller of the double suction pump.

The aim of the study is to compare the effects of remifentanil/dexmedetomidine and remifentanil/midazolam combinations in monitored anesthesia care (MAC) during cystoscopies. Forty patients who received remifentanil infusion of 0.05 mg kg-1 min-1 for cytoscopy procedure were randomized into two groups: Either dexmedetomidine 1 mg kg-1 (Group D) or midazolam 0.2 mg kg-1 h-1 (Group M) was administered intravenously for the first 10 min. Subsequently, anesthesia was maintained by using the bispectral index as a continuous infusion of dexmedetomidine (0.2-0.7 mg kg-1 h-1) or midazolam (0.05-0.15 mg kg-1 h-1). Heart rate, mean arterial pressure, mini-mental state examination findings, levels of sedation andanalgesia, and the patient’s and surgeon’s satisfaction were recorded. Successful sedation and analgesia were achieved in all the patients. We were able to reach the target sedation level faster in Group D (P<0.0001). In Group D, the cognitive functions were less affected than in Group M (P<0.0001). Patient’s and surgeon’s satisfaction were significantly higher in Group D. The targeted sedation levels were achieved in a shorter period with dexmedetomidine-remifentanil compared to midazolam-remifentanil. The dexmedetomidine-remifentanil combination was observed to affect the cognitive functions less than midazolam-remifentanil did with shorter recovery times. Besides, patient’s and surgeon’s satisfaction rates were superior with dexmedetomidine-remifentanil. It was concluded that dexmedetomidine-remifentanil may be a combination of choice for monitored anesthesia care applications in outpatient surgical procedures of short duration.