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Experimental testing is an important method for studying centrifugal compressors. However, test rigs with rotating impellers are costly in terms of construction and operating expenses. To address this issue, this study introduces a stationary component performance test rig for centrifugal compressors using an existing wind tunnel. The rig comprises a blower to supply compressed air, a wind tunnel, and a test section of stationary centrifugal compressor model stage. Specially designed stationary guide vanes substitute the impeller to simulate the impeller outlet flow field. Flow field parameters are measured at the inlet and outlet of each model-scale stationary component using a five-hole probe. Measured results can be used to evaluate the performance of each stationary component. Comparison between measured data and CFD results reveals that the measurement results are in good agreement with CFD results. This validates the reliability of the built test rig and measurement. Afterwards an improved diffuser and return channel of the same centrifugal compressor model stage is tested. The experimental results show a 4% reduction in total pressure loss coefficient and a 1% increase in static pressure recovery coefficient compared to the original structure. These results align with the findings obtained on a rotating test rig, indicating the feasibility of the proposed stationary component aerodynamic performance test rig.

High-pressure black water angle valves are essential equipment of black water flash treatment systems in the coal gasification process, and they usually suffer from a high risk of erosion wear failure. In this study, computational fluid dynamics (CFD), combined with the discrete particle method (DPM) and the volume of fluid (VOF) method, was used to study the flow characteristics and erosion wear phenomenon in high-pressure black water angle valves under different valve cavity radii and opening angles. In particular, a new parameter, the drift index, was introduced to analyze the bias flow phenomenon in the throttling zone. With the increase in valve cavity radius, the drift index first decreases and then increases, and the influence of the valve cavity radius gradually weakens with the increase in the valve opening. It was found that, with the increase in valve cavity radius, the average erosion wear rate of the valve body decreases first and then increases. When the valve cavity radius was 132 mm, the average erosion wear rate of the valve body was the smallest. Therefore, the optimization of the valve cavity radius selection value can reduce the erosion wear damage of the high-pressure black water angle valve and increase its operational dependability.

This study utilizes numerical simulations and dimensional analysis to investigate the impact of the two-phase outlet on flow field characteristics and separation efficiency of the separator. The study revealed a boundary layer separation at the water outlet, which was subsequently addressed to reduce energy losses in the separator. Dimensional analysis considered the influences of operational, structural, and physical parameters on the separator's performance. With other structural parameters held constant, separation efficiency is directly proportional to the ratio of inlet and oil-outlet diameter. Additionally, the separation efficiency is also associated with Re and the ratio of the inlet to the water-outlet diameter. When the diameter of the water outlet is constant, the axial vortex separator achieves optimal separation when the ratio of inlet and water-outlet diameter is 0.563, with a maximum separation efficiency of 97.00%. The optimal separation efficiency is reached at Re=22,908 under various operational conditions. Separation efficiency increases with water content, peaking at an inlet water content of 0.9 across different structural parameters. Separation efficiency shows an increase followed by a decrease with the rise in inlet flow rate(vi), achieving the best performance at vi=3m/s for the different separator structures studied.

The hydrodynamic coefficient of an underwater manipulator varies with changes in posture and flow field, presenting significant challenges for precise control and localization. This study, conducted numerical simulations to investigate the patterns of variation in flow field and hydrodynamic coefficients. Results showed that hydrodynamic performance remained consistent when the posture of the manipulator was either axisymmetric or origin-symmetric. Upon rotation, axial flow extended across the entire downstream surface, and the Karman vortex street entirely eliminated. Pressure coefficients on the back pressure surface of the manipulator increased with the Reynolds number within the range of 6×103 ≤ Re ≤ 3×104, while the pressure coefficient on the upstream surface remained unchanged. Within this range, drag coefficients for the upper and lower arms decreased by 27.4% and 23.9%, respectively. The hydrodynamic performance of the lower arm was independent of the upper arm's posture, with a maximum drag coefficient of 1.48 achieved at α = −90°. As the posture angle of the manipulator varied from 30° to 60°, the pressure coefficient on the upstream surface decreased from 0.75 to 0.25.

This paper aimed to investigate the radiation dosimetry and dose deposition to the surrounded organs at risk (OARs) with different radial and longitudinal margins based on the normal tissue complication probability (NTCP) and dose-volume histogram (DVH) methods.

Fifteen patients with histologically diagnosed esophageal cancer were retrospectively selected. From the clinical target volume (CTV), eight planning target volumes (PTV) were expanded for each patient, with one group of four radial margins (3mm, 5mm, 7mm, 10mm) and the other group of four longitudinal margins (3mm, 5mm, 7mm, 10mm). Then, eight plans with the prescription dose of 50.4Gy were designed in the tomotherapy system. Within each group, doses for the OARs and NTCP-based risk of pneumonitis and pericardial disease were compared.

Almost all the dose parameters in both groups, except for the Dmax (maximum dose) of the spinal cord in the longitudinal direction, showed significant linearly increasing trends with the expansion of margins. For same dose parameters, the increased slopes in the radial direction were larger than those in the longitudinal. Heart V30Gy (the percent volume of receiving 30Gy) grew fastest compared to other clinical constraint indexes in both groups, and the most significant difference in the risk of pneumonitis was observed in the radial group when the margin was expanded from 3 to 10mm.

In order to lower the likelihood of radiation-related toxicity, radial margin expansion should be more strictly controlled in the radiotherapy of esophageal cancer with tomotherapy.

The return-channel of a preceding stage in a multi-stage centrifugal compressor has a significant effect on the aerodynamic performance of the current and subsequent stages. However, due to the relatively complex nature of the return-channel configuration with many geometric parameters, no general design guidance is available in the literature. In this study, numerical methods are used to study the effects of different geometric parameters of a return-channel on the performance of a high-flow-coefficient centrifugal compressor. A multi-objective genetic algorithm is applied to optimize the return-channel. The effects of different geometric parameters on the performance are then studied using a sensitivity analysis method. Calculation results show that the residual vortex intensity at the outlet of the return-channel is affected by the geometric angles of the inlet and outlet of the return-channel blades. The flow uniformity at the stage outlet is primarily affected by the geometric angle of the blade outlet and the number of blades. The overall performance of the compressor stage is primarily affected by the geometric angle of the blade inlet and the lateral inclination angle of the cover plate. Calculation results for a two-stage compressor consisting of the optimized first stage and its following stage show that the outlet flow field of the first stage is more uniform than the original first stage. Additionally, at the design operating condition, the polytropic efficiency and pressure ratio of the entire unit increase by 1.07% and 4.07%, respectively. The polytropic efficiency and pressure ratio for the second stage increase by 2.34% and 3.51%, respectively. The impeller head coefficient increases by 7.33%. The theoretical analysis shows that for high-flow-coefficient centrifugal compressors, reducing the residual vortex intensity of the outlet flow field of the return-channel in a stage can significantly improve the off-design performance of the following stage.

A surface diversion groove with a specific geometry and position can influence the laminar flow characteristics of a projectile, which may affect the flight trajectory of an aircraft. The asymmetric flow field around the projectile can be induced by the diversion groove, which can produce an obvious aerodynamic force and moment at the projectile nose for trajectory correction. This study applied a diversion groove structure to the nose of tail-stabilized projectiles to investigate its impact on the aerodynamic characteristics of the projectile. The mathematical expressions for the aerodynamic force and aerodynamic coefficient were established theoretically. The change in the aerodynamic coefficient as a function of the phase angle of the diversion groove was determined. A parametric simulation was employed to investigate how the diversion groove affects the aerodynamic attributes of the projectile across various Mach numbers and angles of attack. The simulation results are consistent with the variation trends of aerodynamic forces and moments with respect to the phase angle of the diverter groove, as predicted by the static mathematical model. These findings demonstrate that the variation trends of the lift coefficient and pitching moment coefficient with respect to the angle β approximate a cosine function. Meanwhile, the variation trends of the yaw force coefficient and yaw moment coefficient with respect to the angle β approximate a sine function. The tail-stabilized projectile with asymmetrical diversion groove achieved a reduction of 1.2% in drag coefficient compared with that of the canard rudder corrective projectile, while the lift coefficient and pitch moment coefficient were increased by 6.4% and 16%, respectively, in the subsonic regime. The static margin of the projectile ranging from 13% to 16%. This study offers valuable insights for the design of corrective structures with diversion grooves and trajectory control.

For the purpose of automatic generation control (AGC), a portion of the propeller hydro-turbine units in China is adjusted to operate within a restricted range of 75%-85% load using computer-controlled AGC strategies. In engineering applications, it has been observed that when a propeller hydro-turbine unit operates under off-design conditions, a large-scale vortex rope would occur in the draft tube, leading to significant pressure fluctuations. Injecting air into the draft tube to reduce the amplitude of pressure fluctuations is a common practice, but its effectiveness has not been proven on propeller hydro-turbine units. In this study, a CFD model of a propeller hydro-turbine was established, and 15 cases with different guide vane openings (GVO, between 31° and 45°) under unsteady conditions were calculated and studied. Two air admission measures were introduced to suppress the vortex rope oscillation in the draft tube and to mitigate pressure fluctuations.  The reason for the additional energy loss due to air admission was then explained by the entropy production theory, and its value was quantified. This study points out that when injecting air, it is necessary to first consider whether the air will obstruct the flow in the draft tube. Finally, based on simulation and experimental data under various load conditions, pressure fluctuation analysis (based on fast Fourier transform, FFT) was conducted to assess the effectiveness of air admission measures. This study can provide an additional option for balancing unit efficiency and stability when scheduling units using an AGC strategy.

To explore the effectiveness of the mixed decoction of Inula cappa and Serissa japonica (IS) on acute liver injury model.

Sixty carbon tetrachloride (CCl4)-induced mice models were divided into bifendate group (0.2 g/kg) and IS (2, 1and 0.5 g/kg) groups, model group, and control group randomly. Liver function biomarkers aspartate aminotransferase (AST), alanine amiotransferase (ALT), and oxidative stress biomarkers superoxide dismutase (SOD), malonic dialdehyde (MDA) were measured in each group. Hematoxylin and eosin (HE) staining was used to detect the liver tissues.

The necrosis degree and scope, and the structural damage of hepatocyte were significantly ameliorated in the bifendate, IS (2 g/kg) and IS (1 g/kg), compare to model group. IS and bifendate could significantly inhibit the liver index, reduce liver function biomarkers levels and the content of MDA in the liver of acute liver injury mice, and improve the activity of SOD. The serum level of AST was 147.162 (Control), 736.023 (Model), 370.285 (Bifendate), 325.589 (High-dose IS), 407.205 (Middle-dose IS), and 438.631 U/L (Low-dose IS) while the level of ALT was 44.804 (Control), 474.825 (Model), 156.812 (Bifendate), 157.02 (High-dose IS), 217.399 (Middle-dose IS), and 255.649 U/L (Low-dose IS). The content of MDA increased in model and treatment groups compared to control, while the activity of SOD was 69.362 (Control), 53.208 (Model), 64.77 (Bifendate), 73.389 (High-dose IS), 65.173 (Middle-dose IS), and 61.755 (Low-dose IS). Compared to the model group, high-dose IS group exerted significant hepatoprotective effect (p<0.05).

The mixed decoction of Inula cappa and Serissa japonica was able to protect acute liver injury.

The pathogenesis of radiation-induced lung injury (RILI) remains elusive. In this study, we aimed to elucidate the mechanism underlying RILI progression by employing a comprehensive approach, integrating bioinformatics analysis and experimental validation.

Raw transcriptome sequencing data from two Gene Expression Omnibus (GEO) datasets, GSE202586 and GSE14431, were downloaded and overlapping genes were identified. Differential expressions of microRNAs (miRNAs) were analyzed using GEO2R software on the GSE202586 dataset. The miRDB database and miRWalk database were utilized to identify miRNA targets. Specific miRNA inhibitors or protein siRNA were administered to RILI mouse models for experimental confirmation.

Ten genes were consistently upregulated in the RILI groups across both datasets. A series of miRNAs were dysregulated in the RILI group, with miR-34a exhibiting the largest difference. By integrating target exploration and protein-protein interaction (PPI) analysis, we determined that the miR-34a/CDK6 axis may be the key regulator of RILI progression. Notably, miR-34a inhibitor treatment significantly alleviated alveolitis in RILI mice, and this effect was substantially reversed by CDK6 siRNA.

Targeting the miR-34a/CDK6 axis presents a potential therapeutic strategy for RILI.

As one of the most important means of transportation, high-speed trains have a large capacity for carrying passengers. However, their narrow carriages can easily exacerbate the spread of respiratory diseases. Just like personalized ventilation in an airplane, ventilation in seat armrests of high-speed trains may increase comfort for passengers, but also influence the diffusion characteristics of respiratory pollutants. In this study, the effect of personalized ventilation in seat armrests, on the diffusion characteristics of respiratory pollutants in train carriages, is studied by means of the tracer gas method. Taking the ceiling air supply as the original ventilation system, comfortable temperature and pollutant diffusion characteristics of the personalized ventilation system, with 4 different air supply angles, are investigated. The 4 angles are 0°, 30°, 45° and 60°.  When the personalized ventilation with the above 4 angles is adopted, the fluctuation amplitudes of pollutants in the passenger breathing zone are reduced by 15.84%, 19.27%, 19.76% and 19.68%, respectively, compared with the original ventilation system. It indicates that the sensible use of personalized ventilation can effectively reduce the passengers’ contaminant concentrations in the breathing zone, thereby reducing the possibility of cross-contamination between passengers. In addition, the use of the personalized ventilation system leads to a slight improvement in the thermal comfort and flow uniformity in the carriage. Based on the results, personalized air supply with an angle of 45° is advised for use in high-speed trains.

This study reconstructed the flow field of a symmetrical variable inlet guide vane in a centrifugal compressor through the passive control method of vane slots. Based on the high-fidelity numerical simulation model verified by experiments, the influence of different slot forms on the flow field was investigated, and the passive control mechanism was revealed. The results demonstrated that the vane slot method can effectively suppress the suction surface separation and broaden the range of low-loss incidence angles. Overall, the 50_30 slotted vane achieves the best flow field control, with a 65.6% reduction in the total pressure loss coefficient and a 2.3° reduction in the deviation angle, respectively, at a 25° incidence angle. The linear characteristics of the pre-swirl grade variation curve with variable inlet guide vane incidence angles are also improved. Furthermore, changing the slot outlet angle has the most significant influence on the aerodynamic performance as it changes the throat width of the location, thereby affecting the flow rate and momentum of the jet. Finally, the impact of the velocity varies in the first self-similarity region on the slotted vane. The results indicate that, in contrast to the baseline vane, the suppression effect of the slot jet on the flow separation improves with the inlet velocity, whereas the deviation angle of the slotted vane declines with the inlet velocity. Meanwhile, the higher the incoming flow velocity, the better the slotted jet can inhibition of flow separation.

Our study was to evaluate the value of contrast-enhanced ultrasonography (CEUS) and contrast-enhanced magnetic resonance imaging (CE-MRI) in analyzing the blood vessels associated with ovarian tumors.

A total of 100 patients with ovarian tumors underwent CEUS and CE-MRI before surgery. After surgery, the resected ovarian tissues were evaluated via immunohistochemistry to calculate the tumor microvessel density (MVD), and the correlation between the parameters of CEUS and CE-MRI and MVD in ovarian tumors was determined.

The MVD level between ovarian tumors was significantly different (p = 0.03); the peak intensity (PI) and area under the curve (AUC) of CEUS parameters in malignant tumors were significantly higher than those in benign tumors (p = 0.03, p = 0.03); and were significantly positively correlated with MVD (r = 0.57, p = 0.00; r = 0.50, p = 0.00). The Ktrans and Ve of CE-MRI parameters in malignant tumors were significantly higher than those in benign tumors (p = 0.01 and p = 0.04), and were also significantly positively correlated with MVD (r = 0.66, p = 0.00; r = 0.55, p = 0.00). Moreover, there was no significant difference between CEUS and CE-MRI in terms of sensitivity (Se), specificity (Sp), negative predictive value (NPV) and positive predictive value (PPV) in malignant ovarian tumors (p > 0.05).

Both CEUS and CE-MRI parameters can reflect the MVD level in ovarian tumors; therefore, CEUS is expected to become a viable alternative approach for evaluating ovarian tumors.

Considering the uncertainty of the natural state and the convenience of calculation, based on the third generation prospect theory (3-PT) and grey correlation analysis (GRA), we propose a method to solve the multi-attribute decision-making (MADM) problems where the attributes are described by the linguistic intuitionistic fuzzy numbers (LIFNs). Firstly, we transform the LIFNs into the belief structure that includes identity value and belief degree. Then, the evaluation information represented by belief structure is calculated by using the 3-PT, and the prospect matrix is gotten. The alternatives are ranked by the GRA. Finally, we use the proposed method to calculate an example and compare it with other methods to prove its effectiveness and superiority.

The stability and galloping characteristics of iced quad bundle conductor are studied in this paper. Firstly, the aerodynamic coefficients of iced quad bundle conductor and single conductor under four different working conditions are obtained by wind tunnel test. Secondly, the equivalent aerodynamic coefficients at the central axis of the quad bundle conductor are obtained, and the equivalent aerodynamic coefficients are compared with the aerodynamic coefficients of each sub-conductor of the quad bundle conductor. Then, based on the Den Hartog instability mechanism and Nigol instability mechanism, the stable and unstable range of the equivalent coefficients of the quad bundle conductor are analyzed. Finally, the galloping characteristics of the quad bundle conductor are studied by combining with the equivalent aerodynamic coefficients at the central axis of quad bundle conductor. The results of the wind tunnel test show that the aerodynamic coefficients increase with the decreasing of the wind speed. The stability analyses show that the higher the wind speed is, the smaller the Den Hartog coefficient is the easier the Den Hartog’ galloping would occur. Furthermore, the higher the wind speed is, the smaller the Nigol coefficient is, the easier the Nigol’ galloping would occur. The analysis of galloping characteristics shows that when the conductor is located at stable state, the displacement in the y-axis direction would be much greater than the displacement in the z-axis direction.

Physical and geochemical characteristics of shale play conclusive role in confirming operation measures during drilling and stimulation. The properties of shale samples from Jiyang depression were investigated through X-ray diffraction, scanning electron microscope, adsorption isothermal, high pressure mercury intrusion, methylene blue trihydrate, pressure pulse decay, tests of specific water wettability and shale stability index. Correlations, geological and engineering significances of them were discussed. Results show that shale reservoir in Jiyang depression has exploitation value corroborated by good characteristic parameters: 2.86% TOC, 69.9% brittle mineral, 26.14% clay mineral, high permeability of 0.011 × 10-3μm2, large Langmuir volume (5.82 cm3/g) and Langmuir specific area (0.91 m2/g), effective porosity (3.77%) and thickness (130.66m). Langmuir specific area is the key control on methane adsorption and storage verified by its moderate positive relativity with Langmuir volumes rather than TOC. High illite content (69.29%) may lead to instability of borehole and velocity sensitivity damage. Microfractures provide channels for filtration, invasion and loss of drilling fluid. Large specific water wettability (4.36 × 10-7g/m2) and smaller shale stability index (19.99 mm) dispalyed that shale formation were unstable once contacting with fresh water. Countermeasures must be adopted during drilling and fracturing to reduce reservoir damage and complex downhole conditions.

The aim of this study was to investigate the structure and ultrastructure of the digestive tract of Qinling lenok (Brachymystax tsinlingensis Li, 1966), a cold water Salmonidae fish, an endangered teleost species, with high potential for controlled rearing in Shaanxi Province of China, by light and electron microscopy. Morphological data of the digestive tract are important for understanding fish nutrition, pathological or physiological alterations. The histological structure of Qinling lenok consists of four layers: mucosa, submucosa, muscularis and serosa. Taste buds were found in lips and esophagus. The esophageal mucosa consists of undifferentiated mucous cells and surface epithelial cells. The U-shaped stomach was divided into cardiac, fundic and pyloric region. There are numerous gastric glands in the submucosa layer of the cardiac and fundic stomach, but none of them are present in the pyloric region. The convoluted tube-shape intestine is lined by simple columnar epithelial cells with microvilli at the apical surface, with an intestinal coefficient of 0.61. There are numerous goblet cells in the intestine. Finger-like pyloric caeca were found in the front of intestine tube, with number ranged from 42 to 88. In ultrastructural level, mucous and glandular cells in the stomach were found, the glandular cell with well-developed tubulovesicular system, a great amount of pepsinogen granules, mitochondria and Golgi apparatus. The enterocytes with abundant microvilli contained mitochondria and lysosome, and mucous granules of goblet cells were apparent in the intestine. High density of lipid droplets of pyloric caeca might be concerned with fat-absorption. The present study suggests that the digestive tract of Qinling lenok is similar to other carnivorous fishes, in relation to its feeding habits.

The Sturm-Liouville boundary value problem of the multi-order fractional differential equation    D α 0+ [p(t)D β 0+ u(t)] + q(t)f(t, u(t)) = 0, t ∈ (0, 1), a limt→0 t 1−βu(t) − b limt→0 t 1−α p(t)D β 0+ u(t) = 0, c limt→1 u(t) + d limt→1 p(t)D β 0+ u(t) = 0 is studied. Results on the existence of solutions are established. The analysis relies on a weighted function space and a fixed point theorem. An example is given to illustrate the efficiency of the main theorems. Keywords: multi-order fractional differential equation, SturmLiouville boundary value problems, fixed-point theorem.

The Sturm-Liouville boundary value problem of the multi-order fractional differential equation    D α 0+ [p(t)D β 0+ u(t)] + q(t)f(t, u(t)) = 0, t ∈ (0, 1), a limt→0 t 1−βu(t) − b limt→0 t 1−α p(t)D β 0+ u(t) = 0, c limt→1 u(t) + d limt→1 p(t)D β 0+ u(t) = 0 is studied. Results on the existence of solutions are established. The analysis relies on a weighted function space and a fixed point theorem. An example is given to illustrate the efficiency of the main theorems.