Numerical analysis of unsteady cavitating turbulent flow and shedding horse-shoe vortex structure around a twisted hydrofoil

AbstractCavitating turbulent flow around hydrofoils was simulated using the Partially-Averaged Navier–Stokes (PANS) method and a mass transfer cavitation model with the maximum density ratio (ρl/ρv,clip) effect between the liquid and the vapor. The predicted cavity length and thickness of stable cavities as well as the pressure distribution along the suction surface of a NACA66(MOD) hydrofoil compare well with experimental data when using the actual maximum density ratio (ρl/ρv,clip=43391) at room temperature. The unsteady cavitation patterns and their evolution around a Delft twisted hydrofoil were then simulated. The numerical results indicate that the cavity volume fluctuates dramatically as the cavitating flow develops with cavity growth, destabilization, and collapse. The predicted three dimensional cavity structures due to the variation of attack angle in the span-wise direction and the shedding cycle as well as its frequency agree fairly well with experimental observations. The distinct side-lobes of the attached cavity and the shedding U-shaped horse-shoe vortex are well captured. Furthermore, it is shown that the shedding horse-shoe vortex includes a primary U-shaped vapor cloud and two secondary U-shaped vapor clouds originating from the primary shedding at the cavity center and the secondary shedding at both cavity sides. The primary shedding is related to the collision of a radially-diverging re-entrant jet and the attached cavity surface, while the secondary shedding is due to the collision of side-entrant jets and the radially-diverging re-entrant jet. The local flow fields show that the interaction between the circulating flow and the shedding vapor cloud may be the main mechanism producing the cavitating horse-shoe vortex. Two side views described by iso-surfaces of the vapor volume fraction for a 10% vapor volume, and a non-dimensional Q-criterion equal to 200 are used to illustrate the formation, roll-up and transport of the shedding horse-shoe vortex. The predicted height of the shedding horse-shoe vortex increases as the vortex moves downstream. It is shown that the shape of the horse-shoe vortex for the non-dimensional Q-criterion is more complicated than that of the 10% vapor fraction iso-surface and is more consistent with the experiments. Further, though the time-averaged lift coefficient predicted by the PANS calculation is about 12% lower than the experimental value, it is better than other predictions based on RANS solvers

Thermal Stability and Rheological Properties of Polyethylene (PE)/Polyvinylchloride (PVC)/Wood Composites

This paper investigated the thermorheological properties, thermal properties and flame retardant properties of wood-plastic composites (WPCs). With the addition of wood flour (WF), the rheological behavior became complexity. The critical frequency of shear-thinning phenomenon of the melt viscosity was shifted toward lower value. The temperature dependence of elastic modulus, loss modulus became more serious with the addition of WF. The Cole-Cole plot indicated the existence of complex multi-phase structure in the WPC melt. The CONE calorimetry results showed that ammonium polyphosphate (APP) had good flame retardancy through promoting the formation of the intumescent carbon layer. The present study will supply good insight into the optimization of WPC formulation

Efficacy of Ultrasound-guided Radiofrequency Ablation of Parathyroid Hyperplasia: Single Session vs. Two-Session for Effect on Hypocalcemia

To evaluate safety and efficacy of one- vs. two-session radiofrequency ablation (RFA) of parathyroid hyperplasia for patients with secondary hyperparathyroidism (SHPT) and to compare the outcome of both methods on hypocalcemia. Patients with secondary hyperparathyroidism underwent ultrasound guided RFA of parathyroid hyperplasia. Patients were alternately assigned to either group 1 (n = 28) with RFA of all 4 glands in one session or group 2 (n = 28) with RFA of 2 glands in a first session and other 2 glands in a second session. Serum parathyroid hormone (PTH), calcium, phosphorus and alkaline phosphatase (ALP) values were measured at a series of time points after RFA. RFA parameters, including operation duration and ablation time and hospitalization length and cost, were compared between the two groups. Mean PTH decreased in group 1 from 1865.18 ± 828.93 pg/ml to 145.72 ± 119.27 pg/ml at 1 day after RFA and in group 2 from 2256.64 ± 1021.72 pg/ml to 1388.13 ± 890.15 pg/ml at 1 day after first RFA and to 137.26 ± 107.12 pg/ml at 1 day after second RFA. Group 1\u27s calcium level decreased to 1.79 ± 0.31 mmol/L at day 1 after RFA and group 2 decreased to 1.89 ± 0.26 mmol/L at day 1 after second session RFA (P \u3c 0.05). Multivariate analysis showed that hypocalcemia was related to serum ALP. Patients with ALP ≥ 566 U/L had lower calcium compared to patients with ALP \u3c 566 U/L up to a month after RFA (P \u3c 0.05). Group 1\u27s RFA time and hospitalization were shorter and had lower cost compared with Group 2. US-guided RFA of parathyroid hyperplasia is a safe and effective method for treating secondary hyperparathyroidism. Single-session RFA was more cost-effective and resulted in a shorter hospital stay compared to two sessions. However, patients with two-session RFA had less hypocalcemia, especially those with high ALP

Identification and analysis of the germin-like gene family in soybean

In line 12 of page 1, replace "GmGER 9" with "GmGER 15"

Hierarchical Reinforcement Learning for Precise Soccer Shooting Skills using a Quadrupedal Robot

We address the problem of enabling quadrupedal robots to perform precise shooting skills in the real world using reinforcement learning. Developing algorithms to enable a legged robot to shoot a soccer ball to a given target is a challenging problem that combines robot motion control and planning into one task. To solve this problem, we need to consider the dynamics limitation and motion stability during the control of a dynamic legged robot. Moreover, we need to consider motion planning to shoot the hard-to-model deformable ball rolling on the ground with uncertain friction to a desired location. In this paper, we propose a hierarchical framework that leverages deep reinforcement learning to train (a) a robust motion control policy that can track arbitrary motions and (b) a planning policy to decide the desired kicking motion to shoot a soccer ball to a target. We deploy the proposed framework on an A1 quadrupedal robot and enable it to accurately shoot the ball to random targets in the real world.Comment: Accepted to 2022 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2022

Effect of retrograde intrarenal surgery on the inflammatory reaction, renal function indicators and clinical efficacy in male patients with kidney stones

To investigate the effect of retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotripsy on the inflammatory reaction, renal function indicators and clinical efficacy in male patients with kidney stones. 122 male patients with kidney stones were separated into the study group (n = 61) and the control group (n = 61) in terms of distinct clinical treatment regimens. The study group was treated with retrograde intrarenal surgery, while the control group was treated with percutaneous nephrolithotripsy. Inflammatory reaction indicators (Interleukin-6 (IL-6), Interleukin-10 (IL-10), serum tumor necrosis factor-α (TNF-α)), renal function indicators (blood urea nitrogen (BUN), serum creatinine (Scr), blood uric acid (BUA), serum β2 microglobulin (BMG)) and other clinical indicators (operative time, hospital stay, intraoperative blood loss, Visual analogue scale (VAS) pain score, complications) were observed and compared. Upon the treatment, significantly lowered inflammatory factors including IL-6, IL-10, TNF-α and renal function indicators including BUN, Scr, BUA, BMG were shown in study group. Notably shortened operative time and hospital stay were presented in study group with lowered intraoperative blood loss and pain score. The total incidence of complications in study group was 3.28%, significantly lower than 14.75% in control group. Compared with percutaneous nephrolithotripsy, retrograde intrarenal surgery for the treatment of male kidney stones with a diameter of less than 3 cm can improve the inflammatory reaction of male patients, maximize the preservation of renal function indicators, and eminently promote the clinical comprehensive efficacy

Host Phylogeny Is a Major Determinant of Fagaceae-Associated Ectomycorrhizal Fungal Community Assembly at a Regional Scale

Environmental filtering (niche process) and dispersal limitation (neutral process) are two of the primary forces driving community assembly in ecosystems, but how these processes affect the Fagaceae-associated ectomycorrhizal (EM) fungal community at regional scales is so far poorly documented. We examined the EM fungal communities of 61 plant species in six genera belonging to the Fagaceae distributed across Chinese forest ecosystems (geographic distance up to ∼3,757 km) using Illumina Miseq sequencing of ITS2 sequences. The relative effects of environmental filtering (e.g., host plant phylogeny, soil and climate) and dispersal limitation (e.g., spatial distance) on the EM fungal community were distinguished using multiple models. In total, 2,706 operational taxonomic units (OTUs) of EM fungi, corresponding to 54 fungal lineages, were recovered at a 97% sequence similarity level. The EM fungal OTU richness was significantly affected by soil pH and nutrients and by host phylogeny. The EM fungal community composition was significantly influenced by combinations of host phylogeny, spatial distance, soil and climate. Furthermore, host phylogeny had the greatest effect on EM fungal community. The study suggests that the assembly of the EM fungal community is governed by both environmental filtering and dispersal limitation, with host effect being the most important determinant at the regional scale

N′-(3,5-Dichloro-2-hydroxy­benzyl­idene)-3-methoxy­benzohydrazide methanol solvate

In the title compound, C15H12Cl2N2O3·CH3OH, the Schiff base mol­ecule is nearly planar, with a dihedral angle of 4.5 (2)° between the two benzene rings. An intra­molecular O—H⋯N hydrogen bond is observed. The methanol solvent mol­ecule is linked to the Schiff base mol­ecule through inter­molecular N—H⋯O and O—H⋯O hydrogen bonds