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With the increasing level in the intensification of agricultural production in China, continuous cropping obstacles have become a problem that needs to be solved. The use of vertical rotary tillage technology and soil disinfection technology is an effective solution. In this paper, a vertical rotary soil-tilling variable disinfection combine was developed and an on-board control system with STM32 as the control core was designed to realize the real-time acquisition of powder monopoly torque information and the variable application of soil disinfection chemicals. Based on the obtained experimental soil parameters, a discrete element soil particle model was established, and orthogonal experiments were conducted to analyze the single-blade roller tillage process, and the optimal operating parameters were finally selected as 500 mm powder monopoly depth, 320 r/min knife roller speed, and 0.26 m/s forward speed, respectively. The field experiment found that the average tillage depth of the implement was 489 mm, the stability coefficient of tillage depth was 94.50%, the uniformity coefficient of soil disinfection was 85.57%, and the applied amount and the speed ratio coefficient of the given flow were linearly related, respectively. This research provides a technical reference for the deep tillage and soil disinfection of the powder monopoly. [ABSTRACT FROM AUTHOR]

The paper presents the results of simulation studies of fluid flow through a standard orifice and two slotted orifices. The research that has been carried out concerns the analysis of the effect of the orifice geometry on the velocity profiles, turbulence kinetic energy and turbulence energy dispersion. The profile studies were conducted at different distances behind the orifice so that the results could be compared with each other. The studied flow included an airflow whose inlet velocity was 15 m/s. The turbulence model k-ε was used for numerical calculations. The tested orifices were characterized by an orifice constriction equal to β = 0.5. The calculations involved flow through a pipeline with a diameter of 160 mm. The results show that for a standard orifice, the maximum velocity of the flow is about 95 m/s and this is recorded at a distance of about 10–20 cm behind the orifice, and then it decreases, and at a distance of about 60 cm, the flow velocity is about 27 m/s. In the case of slotted holes, the maximum velocity is about 30% lower compared to the flow rate through a standard orifice design. The maximum velocity behind slotted orifices occurs directly behind the orifice, and in the cases of slotted orifice 1 and slotted orifice 2, was about 70 m/s and 67 m/s, respectively. For slotted orifice 1, at a distance of 20 cm behind the orifice, the flow assumed a velocity of about 19 m/s, whereas for slotted orifice 2, the flow reached a speed of about 18 m/s, at a distance of about 30 cm behind the orifice. The values of the maximum kinetic energy of turbulence for the tested orifices are about 420 m2/s2 for the standard orifice, and about 250 m2/s2 and 220 m2/s2 for slotted orifices 1 and 2, respectively. The obtained simulation results demonstrated that slotted orifices lead to faster stream homogenization and do not disturb the flow as much as a standard orifice. Slotted orifices exhibit a higher flow coefficient. [ABSTRACT FROM AUTHOR]

Siberian apricot (Prunus sibirica L.) is a woody tree species of ecological, economic, and social importance. To evaluate the genetic diversity, differentiation, and structure of P. sibirica, we analyzed 176 individuals from 10 natural populations using 14 microsatellite markers. These markers generated 194 alleles in total. The mean number of alleles (13.8571) was higher than the mean number of effective alleles (6.4822). The average expected heterozygosity (0.8292) was higher than the average observed heterozygosity (0.3178). Shannon information index and polymorphism information content were separately 2.0610 and 0.8093, demonstrating the rich genetic diversity of P. sibirica. Analysis of molecular variance revealed that 85% of the genetic variation occurred within populations, with only 15% among them. The genetic differentiation coefficient and gene flow were separately 0.151 and 1.401, indicating a high degree of genetic differentiation. Clustering results showed that a genetic distance coefficient of 0.6 divided the 10 natural populations into two subgroups (subgroups A and B). STRUCTURE and principal coordinate analysis divided the 176 individuals into two subgroups (clusters 1 and 2). Mantel tests revealed that genetic distance was correlated with geographical distance and elevation differences. These findings can contribute to the effective conservation and management of P. sibirica resources. [ABSTRACT FROM AUTHOR]

Near-wall flow simulation remains a central challenge in aerodynamics modelling: Reynolds-averaged Navier-Stokes predictions of separated flows are often inaccurate, and large-eddy simulation (LES) can require prohibitively small near-wall mesh sizes. A deep learning (DL) closure model for LES is developed by introducing untrained neural networks into the governing equations and training in situ for incompressible flows around rectangular prisms at moderate Reynolds numbers. The DL-LES models are trained using adjoint partial differential equation (PDE) optimization methods to match, as closely as possible, direct numerical simulation (DNS) data. They are then evaluated out-of-sample - for aspect ratios, Reynolds numbers and bluff-body geometries not included in the training data - and compared with standard LES models. The DL-LES models outperform these models and are able to achieve accurate LES predictions on a relatively coarse mesh (downsampled from the DNS mesh by factors of four or eight in each Cartesian direction). We study the accuracy of the DL-LES model for predicting the drag coefficient, near-wall and far-field mean flow, and resolved Reynolds stress. A crucial challenge is that the LES quantities of interest are the steady-state flow statistics; for example, a time-averaged velocity component ⟨ui⟩(x)=limt→∞(1/t)∫0tui(s,x)ds. Calculating the steady-state flow statistics therefore requires simulating the DL-LES equations over a large number of flow times through the domain. It is a non-trivial question whether an unsteady PDE model with a functional form defined by a deep neural network can remain stable and accurate on t∈[0,∞), especially when trained over comparatively short time intervals. Our results demonstrate that the DL-LES models are accurate and stable over long time horizons, which enables the estimation of the steady-state mean velocity, fluctuations and drag coefficient of turbulent flows around bluff bodies relevant to aerodynamics applications. [ABSTRACT FROM AUTHOR]

In hydrology and water resources engineering, predicting the flow coefficient is a crucial task that helps estimate the precipitation resulting in a surface flow. Accurate flow coefficient prediction is essential for efficient water management, flood control strategy development, and water resource planning. This investigation calculated the flow coefficient using models based on Simple Membership functions and fuzzy Rules Generation Technique (SMRGT) and an Adaptive Neuro-Fuzzy Inference System (ANFIS) model. The fuzzy logic methods are used to model the intricate connections between the inputs and the output. Statistical parameters such as the coefficient of determination (R2), the root mean square error (RMSE), the mean absolute error (MAE), and the mean absolute percentage error (MAPE) were used to evaluate the performance of models. The statistical tests outcome for the SMRGT model was (RMSE:0.056, MAE:1.92, MAPE:6.88, R2:0.996), and for the ANFIS was (RMSE:0.96, MAE:2.703, MAPE:19.97, R2:0.8038). According to the findings, the SMRGT, a physics-based model, exhibited superior accuracy and reliability in predicting the flow coefficient compared to ANFIS. This is attributed to the SMRGT's ability to integrate expert knowledge and domain-specific information, rendering it a viable solution for diverse issues. [ABSTRACT FROM AUTHOR]

Focusing on cavitation phenomena caused by high-speed submerged water jets, this paper presents an improved cavitation model for a compressible fluid mixture based on a concise estimation of fluid compressibility that considers phase change effects. The homogeneous two-phase flow assumption is adopted, and the gas phase is assumed to consist of vapor and non-condensable components. Equations of state for a pure liquid and an ideal gas are employed to evaluate the compressibility of the liquid and non-condensable components, and the compressibility of the vapor is treated semi-empirically as a constant. The model is embedded in an unsteady Reynolds-averaged Navier–Stokes solver, with the realizable k-ε model employed to evaluate the eddy viscosity. The turbulent cavitating flow caused by an impulsively started submerged water jet is treated. The pattern of periodic cavitation cloud shedding is acceptably captured, and the mass flow rate coefficient and its fluctuation frequency evaluated by simulations agree with the experimental results well. The validity of the proposed method is confirmed. The results reveal that cavitation occurs when p i n / P in reaches 0.65 and fluid flow begins to pulsate. In the well-developed stage, the leading cavitation cloud and a subsequent cloud are successively shed downstream, and this process is repeated. The subsequent cloud catches the leading cloud, and they coalesce in the range x / d ≈ 2–3. The pressure fluctuations concentrate in the range of x / d ≈ 2 – 5 corresponding to the periodic shedding of cavitation clouds. The mass flow rate coefficient pulsates from 0.59 – 0.66 under the effect of cavitation. [ABSTRACT FROM AUTHOR]

The current study is a new method for liquid–liquid extraction of copper (II) and zinc that was carried out using an efficient solvent called trifluoroacetylacetone in a hollow fiber membrane contactor (HFMC). To analyze the extraction process and understand its underlying mechanisms, computational fluid dynamics (CFD) was employed. The extraction was performed in three domains by coupling the mass and momentum equation to express the solute transport from the tube side to the shell side through the membrane in a hollow fiber membrane contactor. The finite element approach simulates the governing equation and validates the results. This work aims to obtain the distribution of copper (II) and zinc by performing a simulation. The effect of some crucial parameters was investigated. The results illustrate that the extraction efficiency increases by increasing the partition coefficient and decreasing the flow rate on the tube side. Also, the temperature significantly affects extraction, and by enhancing the temperature from 298 to 313 K, the efficiency increases by 12% for copper (II) and 6.6% for zinc. Furthermore, the membrane porosity was found to be another influential parameter. By increasing the membrane porosity of 25% to 90%, the efficiency increases to 95% for copper (II) and 98% for zinc. [ABSTRACT FROM AUTHOR]

Consideration has been given to the distinctive features of multistep concentration of all the molybdenum isotopes in a cascade with a varying type of stages as far as the number of gas centrifuges is concerned. A computational experiment on separation of molybdenum hexafluoride was conducted. A procedure of calculation from the cuts of partial flows of the stages was used which takes account of the dependence of the separation factors of gas centrifuges on their feed flow and the flow-division coefficient. It has been shown that the high efficiency of separation processes is attained with a large number of stages and gas centrifuges and small feed flows of the cascade. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The comparative numerical analysis of the butterfly valve is performed to simulate the fluid flow inside the pipe. In this study, the performance of the single-disc butterfly valve flow is investigated in the opening process. The flow separation for the turbulent case is also examined to observe the velocity and pressure distributions since the unsteady flow can be understood well with an examination of the velocity and pressure changes. The formations of the vortexes are considered. In addition, an optimization study is done to decrease the operational coefficient values. In the result of the study, the characteristic parameters of the conventional and optimized valves are compared including, flow coefficient; drag coefficients, and dynamic torque. The changes of the characteristic parameters at different opening angles are demonstrated as tables and graphs to evaluate the performance of the valves. [ABSTRACT FROM AUTHOR]

In aero-engines, a secondary air system is used to cool the rotor discs and seal cavities between rotor and stator parts. The pressure loss caused by bleed air can be effectively reduced by setting the finned vortex reducer. Thus, the bleed system design can be optimized by researching the flow structure and pressure loss of each section in the cavity with a finned vortex reducer. In this study, the influence of different installation positions of a finned vortex reducer on the pressure loss characteristics was investigated through experimental and numerical simulation methods, focusing on the radial inflow of the secondary air system. The results indicate that the inlet and outlet positions of the fins affect the flow structure in the cavity. The aerodynamic parameters (rotational Reynolds number ReΦ and mass flow rate coefficient Cw), together with the inlet and outlet radii of the fins, influence the pressure loss in the cavity. Considering the swirl ratio β constrained by the fins, a pressure loss model was established, which showed good agreement with the experimentally measured pressure loss. This model reflects the impact of the inlet and outlet positions of the fins on the pressure loss characteristics. [ABSTRACT FROM AUTHOR]

The subject of this paper is the effect of changing the roughness of the inflow surface of an orifice on its characteristics. A sloping segmental orifice was chosen as the reducer and its surface roughness was changed by lining its inflow surface with sandpaper of different roughness parameters. In such a system, the dependence of the flow stream on the differential pressure at the orifice was measured on a test stand in the range of Reynolds numbers 4110-17000, the flow coefficient C was calculated and flow characteristics were prepared. The study was carried out for a selected segmental orifice with flow coefficient C = 0.723 installed in a pipeline with diameter Dw = 50.35 mm. The roughness of the inflow surface was changed by sticking sandpaper with a gradation of P120 ÷ P1200 to its surface. The roughness parameter Ra was in the range Ra = 5.69-25.85 µm and Rz = 43.84-164.83 µm. The dependence of the variation of the coefficient C on the roughness parameter Ra is then presented and the relative errors of the flow stream measurements were calculated. The paper also presents distributions of the differential pressure measured at the orifice for different flow streams depending on the roughness parameter. [ABSTRACT FROM AUTHOR]

This study involves an experimental and numerical analysis of the Hunter turbine, a vertical axis turbine utilized for tidal energy. A laboratory model of the Hunter turbine, featuring an aspect ratio of 1.2, was designed and tested. Numerical equations, including the Reynolds-averaged Navier–Stokes (RANS) constant, were analyzed through computational fluid dynamics (CFD) software using the k-ω turbulence model to forecast turbine performance and other related flow specifications, such as pressure lines, stream velocity, and pressure. This simulation was conducted on the surface of the turbine blade, and the results were obtained accordingly. The experimental data were utilized to verify the numerical results, and the difference between the two was reasonably acceptable. The turbine was studied in six different flow coefficients and four different vertical positions. The results indicated that the power coefficient increased as the submerged depth from a water-free surface increased, and after a specific depth, the output power remained constant. It was also observed that the minimum depth from a water-free surface for maximum power coefficient was three times the diameter of the turbine drum (3D). [ABSTRACT FROM AUTHOR]

The effect of the elliptic ratio on the hydraulic performance of the LOPAC gate has been investigated using experimental and Computational Fluid Dynamics CFD simulations (Flow- 3 D Hydro). Experiments and simulations were carried out at three different flow discharges, three different submerged ratios, and five different elliptic ratios. In this context, the CFD model was first calibrated and verified using the measured data, and then CFD simulation was performed. The ratio of upstream/downstream flow depth, the flow discharge coefficient, and the energy dissipation through the gate have been calculated and analyzed, and the three-dimensional features of the flow have been described. Based on the results, the elliptical LOPAC gates with circular weirs determine extreme values of the controlled flow parameters. Asymmetric recirculation downstream of the gate is sometimes observed in the model predictions. The use of Coriolis coefficients relevant to the entire cross-section, here deployed just for the circular and the traditional rectangular Lopac gates, has allowed a concise way to report and compare complex flows for any experimental condition. [ABSTRACT FROM AUTHOR]

Copyright of China Population Resources & Environment is the property of Shandong Normal University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The determination of the total aerodynamic load which negatively influences the movement of artillery projectiles is inevitable and indispensable in order to be able to increase or control their ranges. The main part of this aerodynamic load that has the most influence on projectile movement is the drag force, which acts in the opposite direction to the velocity vector and therefore opposes its movement. From this, in this present work, the total drag coefficient of the 155mm M107 axisymmetric projectile under axisymmetric flow, at zero yaw, was predicted by semi-empirical and computational fluid dynamics (CFD) approaches in the three flow regimes, also the influence of its components on the total drag was analysed. The average deviation of the total drag coefficient in the three flow regimes, compared to the reference experimental results, is 5.7% for the semi-empirical results and 1.7% for the computational results. Analysis of the influence of the total drag components, such as pressure drag, friction drag and base drag, permitted to calculate their influence rates on the total drag as a function of Mach number and flow regime. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The flow boiling heat transfer performance of R22 and R407c, in a microfin tube with a helix angle of 22° and an apex angle of 48°, was evaluated in a study. The study is aimed at investigating the impact of heat flux, mass flux, saturation temperature, and vapor quality on the heat transfer coefficient during flow boiling. Two different saturation temperatures, 293.15 K and 313.15 K, were used in the experiments, with heat fluxes ranging from 25 to 85 kW.m-2 and mass fluxes ranging from 150 to 350 kg.m-2.s-1. To validate the experimental data, the results were compared with existing correlations for microfin tubes. The calculated error margin among all correlations with the experimental dataset, which ±15% and ±30%, was also matched by 85% and 95% of the datasets, respectively. Findings reveal that at lower saturation temperatures, the average heat transfer coefficients augmented with increasing mass flux. The study also found that R22 has a higher heat transfer coefficient than R407c at low saturation temperatures due to its stronger thermal conductivity and lower viscosity. [ABSTRACT FROM AUTHOR]

This paper proposes a pollution diffusion model that accurately assesses changes in instantaneous river pollution in vegetation open channels. The model is established based on cellular automata and lattice Boltzmann method (LBM-CA). Flow influence coefficients are incorporated into cellular automata (CA) to represent the effect of vegetation on pollutant diffusion, while the lattice Boltzmann method (LBM) is utilized to simulate flow in vegetation open channels and obtain the flow influence coefficients for each cellular. The results show that the LBM-CA model has high accuracy and that pollutants tend to accumulate in vegetation areas, thereby extending the residence time of pollutants. The model incorporates pollution limits, allowing the prediction of basin pollution levels at specific times. The LBM-CA model provides a method for simulating pollutant diffusion in natural rivers. [ABSTRACT FROM AUTHOR]

Simple analytical models can be employed to estimate the leakage mass flow rate from labyrinth seals, resulting in a quick procedure, well suited for the early design process. Different formulas were proposed by many authors during the past decades and most of them employ a carry-over factor and a flow coefficient to predict the mass flow rate across the clearance area. The present work aims to compare the analytical prediction with the results of an experimental campaign. The experimental results were retrieved from a dedicated test rig for both a straight-through and a stepped labyrinth seal. Hence, for each seal, the effect of the clearance size, the Reynolds number and the pressure ratio has been investigated. Starting from the experimental required inputs, six different correlations are considered, with both direct and indirect methods. The results are shown as a function of pressure ratio and clearance gap. Despite some differences in the comparison, and most of the used correlation underestimate the measured mass flow rate, some general trends and guidelines can be highlighted. [ABSTRACT FROM AUTHOR]

The shoal area of the lower Yellow River in China is not flooded with water during the dry season, so various plants can grow. When floods overflow the plains in the flood season, the complexity of water resistance is increased due to the resistance to water flow by vegetation, which directly affects flood discharge in the beach area. The drag force coefficient (CD), Manning's roughness coefficient (n), and Darcy-Weisbach resistance coefficient (f) are commonly used to characterize vegetation drag force. Such studies are commonly conducted in clear water, but flood water in the lower Yellow River is generally muddy. In order to study the effect of the same sediment content and different sedimentation thicknesses on the resistance of muddy waters containing vegetation, this study conducted experiments in a flume (length = 28 m, width = 0.5 m, and height = 0.5 m) under different deposition thicknesses. The results showed that the vegetation drag force coefficient (CD), vegetation roughness (nb), and Darcy-Weisbach drag coefficient (f) all decreased logarithmically with increasing Reynolds number (Re) and Froude number (Fr). When Re > 30,000, under the conditions of different siltation thicknesses of vegetation, the vegetation roughness tended to stabilize near its minimum value. When the Reynolds number of the water flow is large (Re > 20,000), the variation of the Darcy-Weisbach drag coefficient f slows down with the Reynolds number Re. Logarithmic functions were established for the above resistance coefficients and flow coefficients, and the corresponding correlation coefficients were high, indicating that the conclusions were reliable. [ABSTRACT FROM AUTHOR]

A new type of assembly composite damping self‐centering brace is proposed to simplify the configuration, reduce the manufacturing cost, and improve its energy dissipation capacity, which is assembled by several modules in parallel with different functions. A brace specimen with a total length of 1.843 m was designed and numerically analyzed. The brace exhibits stable and full flag‐shaped hysteretic responses, and dissipates adequate energy during cyclic motion, with a high bearing capacity. When the brace is unloaded, the viscous damping force disappears, and the residual displacement can be basically eliminated. The hysteretic envelope area increases with the increase in loading frequency. When the frequency is 0.5 Hz and the target displacement is 30 mm, the activation force, ultimate bearing capacity, residual displacement, energy dissipation during one cycle, and equivalent viscous damping ratio are 622.5 kN, 1018.7 kN, 9.11 mm, 41.10 kJ, and 0.214, respectively. Under random loading, the damping force provided by the viscous module ensures a fuller hysteretic loop than the existing displacement‐type energy dissipation self‐centering brace. The influences of design parameters on the hysteretic performances of the brace were studied. When the disc spring stiffness increases from 3.27 to 9.80 kN/mm, the ultimate bearing capacity, residual displacement, and equivalent viscous damping ratio change by 18%, −24%, and −15%, respectively. The viscous damping coefficient and flow index of the viscous module should be increased, and the prepressed force and stiffness of disc springs in recentering module should also be appropriately increased. [ABSTRACT FROM AUTHOR]

For the development of gas exchange for large diesel engines, a compromise has to be found between efficient valve-flow and the time between overhauls. On the one hand, large effective flow areas, especially during valve-overlap, are demanded. On the other hand, there are limitations of cylinder bore regarding the maximum diameter of inlet and outlet valves and the minimum distance (dead space) between valves and piston, as well as wear-related smaller seat angles. For large medium-speed diesel engines, a valve-seat angle of β = 30° for inlet and outlet valves is a standard application. For engine-operation with clean fuels, a valve-seat lubrication (gasoil) or smaller seat angles (natural gas) need to be applied. With this presentation, the basic influence of different valve-seat angles on the operation values and emissions will be considered for the example of the single-cylinder research engine FM16/24. Using a self-developed testbed, experimental investigations into effective flow areas as a function of valve-lift at inlet and outlet valves have to be executed. With this input, different cycle calculations including T/C have to be carried out to determine deviances in specific fuel-oil consumption, exhaust-gas temperatures, NOx emissions and air/fuel ratio. The results will be discussed critically. [ABSTRACT FROM AUTHOR]

Discrete tip injection (DTI) shows great promise for improving the operating stability of transonic axial flow compressor (AFC) rotors. However, the design optimization of DTI remains a challenging task because of both the reliance on computationally expensive unsteady simulations to calculate its effects and the lack of a flow physics-based index for assessing operating stability. The present study introduces a nonlinear harmonic method for the rapid simulation of the dominant unsteady effects caused by a DTI device, and it proposes the unsteady shroud endwall blockage attenuation as an operating stability optimization index for DTI design based on analyzing the stall flow mechanism in transonic AFCs. On this basis, an efficient optimization method for DTI design is proposed in combination with an adaptive kriging-based optimization technique. This design optimization method is validated by the Coandă injector design for the transonic rotor National Aeronautics and Space Administration Rotor 37, with improved operating range and reduced injection mass flow pursued simultaneously by a comprehensive objective function. The optimal DTI design significantly reduces the stalling flow coefficient of the compressor by 4.46% at a small injection mass flow (0.72% of the compressor stalling mass flow), with a slight increase in the aerodynamic performance of the compressor. Detailed unsteady flow-field analysis shows that the main reason for the improved operating stability of the transonic AFC is a significant attenuation and delayed recovery of shroud endwall blockage, and the underlying flow mechanism is elucidated well. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the development of combined cycle engines, it is urgent to estimate more quickly and accurately the flow capture capacity and starting performance of variable geometry inlets over a wide Mach number range. Based on the flow field and parameter fitting, two prediction methods for the curved axisymmetric inlet with lip translation scheme have been proposed. The method based on the flow field of the reference inlet is more efficient than the parameters-based prediction method, as it can accurately predict the lip translation distance and the corresponding flow coefficient over the entire working range of the inlet without additional numerical calculations. Moreover, the starting Mach number is accurately predicted by the fitting method based on the throat Mach number of the reference inlet, with a relative error of only 0.95% compared to the numerical simulation. The flow coefficient-based method is simple and accurate for predicting lip translation distances with a known starting Mach number, with a relative error of only 1.65% compared to numerical simulations. The prediction approaches can overcome the drawbacks of the standard iterative algorithms and significantly enhance computational accuracy and efficiency. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reduction of energy expenditures required for various technological processes is a pressing issue in today's economy. One of the ways to solve this issue in regard to liquefied natural gas (LNG) storage is the recovery of its vapours from LNG tanks using an ejector system. In that respect, studies on the outflow of the real gas through the nozzle, the main element of the ejector, and identifying differences from the ideal gas outflow, are of high relevance. Particularly, this concerns the determination of the discharge coefficient µ as the ratio of the actual flowrate to the ideal one, taking into account the energy losses at gas outflow through the nozzle. The discharge coefficient values determined to date for various nozzle geometries are, as a rule, evaluated empirically and contradictory in some cases. The authors suggest determining the discharge coefficient by means of an experiment. This paper includes µ values determined using this method for the critical outflow of air to atmosphere through constrictor nozzles with different outlet diameters (0.003 m; 0.004 m; 0.005 m) in the pressure range at the nozzle inlet of 0.5–0.9 MPa. The obtained results may be used for the design of an ejector system for the recovery of the boil-off gas from LNG tanks, as well as in other fields of industry, for the design of technical and experimental devices with nozzles for various applications. [ABSTRACT FROM AUTHOR]

Anisotropic flow, typically defined as the azimuthal correlations of the produced particles with respect to the common symmetry plane over a large kinematic, has been a popular approach in the last three decades to explore the properties of hot and dense QCD matter in high-energy heavy-ion collisions. These flow studies are usually based on the multi-particle correlations method, assuming that multi-particle correlations can be factorized into the product of flow coefficients. However, recent LHC measurements, based on new four-particle correlation observables, show evidence of flow angle decorrelation and flow magnitude decorrelation. These decorrelations break the assumption of the common symmetry plane and factorization. In this paper, we perform systematic studies to investigate the decorrelation with A Multi-Phase Transport (AMPT) model. We examine different tunings of the initial conditions, partonic cross sections, and hadronic interactions, revealing that the decorrelations are mainly driven by the initial geometry fluctuations while weakly influenced by the system's dynamic evolution. Comparison to experimental data and the AMPT calculations presented in this paper promotes a new possibility to further constraints on the initial conditions of the heavy-ion collisions. [ABSTRACT FROM AUTHOR]

The current investigation focuses on the thermal characteristics and heat and mass transfer in the context of their applications. There has been a lot of interest in the utilization of non‐Newtonian liquids in various engineering and biological fields. Having such considerable attention on non‐Newtonian liquids, the goal is to investigate the flow nature of viscoelastic nanoliquid flow driven by a permeable stretchable surface considering the Buongiorno nanofluid model with suction or injection and mixed convection. This model includes Brownian diffusion, thermophoresis, and radiation effects. The thermal boundary layer theories established the constitutive flow equations, that is, the momentum, diffusion balance, and energy expressions. The established partial differential equations are diminished to dimensionless coupled ordinary differential equations by taking the assistance of proper transformations of nonlinearities. An efficient and validated numerical algorithm is implemented as a computational technique where Mathematica 11.0 environment, a programming tool, is developed for fluid dynamics. The convergence standard had also been recognized for the precision of the relevant parameters by using boundary postulates. The impact of embedded physical quantities of practical interest is examined and offered via the plotted graphs. In addition, the impression of system parameters on drag force, heat, and mass flow coefficient with three‐dimensional graphs is also debated. [ABSTRACT FROM AUTHOR]

This research introduces a hybrid deep learning approach to perform real-time forecasting of passenger traffic flow for the metro railway system (MRS). By integrating long short-term memory (LSTM) and the graph convolutional network (GCN), a hybrid deep learning neural network named the graph convolutional memory network (GCMN) was constructed and trained for accurate real-time prediction of passenger traffic flow for the MRS. Data collected of the traffic flow in Delhi's metro rail network system in the period from October 2012 to May 2017 were utilized to demonstrate the effectiveness of the developed model. The results indicate that (1) the developed method provides accurate predictions of the traffic flow with an average coefficient of determination (R2) of 0.920, RMSE of 368.364, and MAE of 549.527, and (2) the GCMN model outperforms state-of-the-art methods, including LSTM and the light gradient boosting machine (LightGBM). This study contributes to the state of practice in proposing a novel framework that provides reliable estimations of passenger traffic flow. The developed model can also be used as a benchmark for planning and upgrading works of the MRS by metro owners and architects. [ABSTRACT FROM AUTHOR]

This paper presents ocean wave energy control using the Aquila optimization (AO) technique. An oscillating water column (OWC)-type wave energy converter has been considered that is fitted with a Wells turbine and doubly fed induction generator (DFIG). To achieve maximum power point tracking (MPPT), the rotor speed of the DFIG must be controlled as per the MPPT law. The MPPT law is designed in such a way that the Wells turbine flow coefficient remains within the threshold limit. It avoids the turbine from stalling which generates the maximum power. The MPPT law provides the reference rotor speed which is followed by the actual rotor speed. For this, a backstepping controller (BSC)-based rotational speed control strategy has been designed using the Lyapunov stability theory. The BSC has unknown control parameters which should be selected such that tracking errors are minimum. Hence, the objective of this work is to find the unknown control parameters using an optimization approach. The optimization approach of selecting BSC control parameters for an OWC plant has not been explored yet. To achieve this, an integral square error (ISE)-type fitness function has been defined and minimized using the AO technique. The results achieved using the AO technique have been compared with particle swarm optimization (PSO) and a genetic algorithm (GA), validating its superior performance. The rotor speed error maximum peak overshoot is least for AO-BSC as compared to PSO-BSC and GA-BSC. The fitness function value for AO comes out to be least among all the optimization methods applied. However, all tested methods provide satisfactory results in terms of turbine flow coefficient, rotor speed and output power. The approach paves the way for future research on ocean wave energy control. [ABSTRACT FROM AUTHOR]

The safety of the offshore net cage and the survival environment of cultured fish are closely related to the net system. Since the damage caused by predators or biological fouling significantly threatens the longevity of the net system, this paper aims to understand the hydrodynamic characteristics of the biological fouling net in the open ocean. First, the equivalent model of the biofouling net is proposed, and the drag force coefficient and flow field variations are studied using large-eddy simulation (LES). The results highlight that the cross-sections contacted with fluid lead to a smaller drag force coefficient for 2 × 2 cruciform circular cylinder. Then, the fitted formula of the drag force coefficient under different biological fouling levels is established. Moreover, the length of recirculation flow is irrelevant with the number of net twines, but it is greatly affected by the biological fouling level. Wake vortices behind the fouling net is more disordered as the biological fouling level increases. Finally, the influence between the net aperture and the net twines on the wake are also accessed in this paper. [ABSTRACT FROM AUTHOR]

Generalizability theory provides a comprehensive framework for determining how multiple sources of measurement error affect scores from psychological assessments and using that information to improve those assessments. Although generalizability theory designs have traditionally been analyzed using analyses of variance (ANOVA) procedures, the same analyses can be replicated and extended using structural equation models. We collected multi-occasion data from inventories measuring numerous dimensions of personality, self-concept, and socially desirable responding to compare variance components, generalizability coefficients, dependability coefficients, and proportions of universe score and measurement error variance using structural equation modeling versus ANOVA techniques. We further applied structural equation modeling techniques to continuous latent response variable metrics and derived Monte Carlo-based confidence intervals for those indices on both observed score and continuous latent response variable metrics. Results for observed scores estimated using structural equation modeling and ANOVA procedures seldom varied. Differences in reliability between raw score and continuous latent response variable metrics were much greater for scales with dichotomous responses, thereby highlighting the value of doing analyses on both metrics to evaluate gains that might be achieved by increasing response options. We provide detailed guidelines for applying the demonstrated techniques using structural equation modeling and ANOVA-based statistical software. [ABSTRACT FROM AUTHOR]

Simple Summary: High-quality seedlings are a prerequisite for healthy aquatic animal breeding. As the scale of Procambarus clarkii farming continues to expand, the model of "breeding and catching large and keeping small" has led to serious degradation of the fry. This has restricted the development of the P. clarkii industry. Therefore, the selection and breeding of optimal breeds of P. clarkii are very important. Investigating intraspecific patterns of genetic diversity may help unravel the species' genetic structure, evaluate the quality of the fry, and design measures for breeding and conservation. In this study, the genetic diversity of P. clarkii from three regions of China was analysed using microsatellite markers. Populations of P. clarkii showed high genetic diversity and extensive gene flow. The Xuancheng population could be used as a selective breeding population because it possesses the highest diversity. The results of this study provide a scientific basis for the conservation of germplasm resources and the genetic selection and breeding of P. clarkii. With the increasing scale of crayfish breeding, the self-propagation and "catch large and keep small" breeding patterns have led to serious degradation of the fry, so the selection and breeding of high-quality fry is very important. Selecting a population with a high genetic diversity as the base population for breeding can greatly improve the breeding efficiency. Fifteen microsatellite loci were used to understand the genetic structure and diversity of three Procambarus clarkii populations in Chongming, Shanghai; Gaoyou, Jiangsu; and Xuancheng, Anhui. The results indicated that the three populations were diverse and the number of alleles, observed heterozygosity, expected heterozygosity, Shannon information index, and polymorphic information content ranged from 4.8 to 6.2, 0.5567 to 0.6257, 0.6166 to 0.7086, 1.1292 to 1.3987, and 0.5446 to 0.6452, respectively. The Xuancheng population had the highest genetic diversity. The genetic differentiation coefficient and gene flow of the three populations were between 0.0553 and 0.1068 and 2.0908 and 4.2708, respectively, and there was extensive genetic exchange between the Chongming and Xuancheng populations. Analyses of molecular variance indicated that the genetic variation was mainly within the population (91.51%) and inter-population genetic variation accounted for 8.49%. The unweighted pair group method with an arithmetic mean clustering map was utilised based on the genetic distance between groups, and the results showed that the Gaoyou group was grouped alone, while the Chongming and Xuancheng groups were clustered together. The structural results indicated that the Chongming and Xuancheng groups had the same origin, although the Xuancheng group possessed a more complex genetic structure. This study indicated that all three populations had a high genetic diversity, with the Xuancheng population exhibiting the highest diversity. The results of the study provide a reference for the selection of base populations in breeding programs and confirm that the Xuancheng population in Anhui has a better genetic background. The selection of the Xuancheng population as one of the base populations for genetic breeding will be more efficient to accumulate superior traits. [ABSTRACT FROM AUTHOR]

Telescopic water intake structures allow for the selective intake of water from the top layers of a reservoir. A telescopic water intake has a high degree of mobility, and a wide field of application; at the same time, it is very simple and convenient to operate. Despite these advantages, an exact calculation method for a telescopic water intake is lacking (Lipin, 2020; Lipin, 2022). Therefore, the purpose of this research is to develop an exact calculation method for a telescopic water intake. In order to perform this task, all the structural elements of a telescopic water intake were analyzed separately by means of existing hydraulic principles. The impact of the critical submergence depth of the water intake funnel on the operability of a telescopic water intake was studied, and an equation for the critical submergence depth calculation was proposed. The optimal range of the flow rate coefficient (μ =0.30 - 0.45) was proposed for calculating the funnel flow rate, and the correlation between the flow rate and funnel inlet diameter was defined. The optimal curvature radius of the elbow was proposed. In order to verify the above mentioned parameters and correlations, analytical and numerical calculations of specific examples were performed. The results of the numerical modelling demonstrated that the critical submergence depth and shape of the water intake funnel, as defined by the analytical calculations, ensured its effective operation free of cavitation and vortexes. The analytically calculated dimensions of the telescopic column, following the numerical modelling results, provided normal hydraulic conditions without active cavitation. According to the numerical modelling, the proposed curvature radius of the elbow was sufficient to avoid significant cavitation and vortex formation in the elbow structure. This research can provide guidance for the design of telescopic water intake structures. [ABSTRACT FROM AUTHOR]

For diesel engines equipped with a combined spiral/tangential inlet, the main object of the valve structure and valve lift dissimilitude strategies is the valve, the changes of both will alter the motion state of the in-cylinder airflow, which has an important impact on the formation and combustion of the mixture. In order to investigate the flow performance of valve structure and valve lift dissimilitude, this paper used computational fluid dynamics (CFD) numerical simulation and multi-parameter regression methods to optimize the dual intake valve structure and obtained three valve structures with better intake performance first. Then, the optimized intake valve structure models were combined with the valve lift dissimilitude schemes to conduct steady-flow tests for the intake port. Through the reasonable combining of the two, the intake performance of the original engine was further improved. The results show that the valve structure has a relatively small influence on the intake mass, while it has a greater effect on the formation of the swirl in the cylinder, increasing the swirl ratio by 8.0%. The optimized valve structure model was combined with the valve lift dissimilitude scheme. It was found that the valve structure with optimal intake mass combined with the dissimilitude scheme of the largest valve lift of the spiral inlet could increase the flow coefficient by a maximum of 1.9%. The valve structure of the optimal swirl ratio combined with the dissimilitude scheme of the largest valve lift of the tangential inlet could increase the swirl ratio by a maximum of 9.7%. This study can guide diesel engines with combined intakes to increase the intake mass and improve the intake performance. [ABSTRACT FROM AUTHOR]

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Utilization of satellite precipitation products (SPPs) for reliable flood modeling has become a necessity due to the scarcity of conventional gauging systems. Three high-resolution SPPs, i.e., Integrated Multi-satellite Retrieval for GPM (IMERG), Global Satellite Mapping of Precipitation (GSMaP), and Climate Hazards Group InfraRed Precipitation with Station (CHIRPS), data were assessed statistically and hydrologically in the sparsely gauged Chenab River basin of Pakistan. The consistency of rain gauge data was assessed by the double mass curve (DMC). The statistical metrics applied were probability of detection (POD), critical success index (CSI), false alarm ratio (FAR), correlation coefficient (CC), root mean square error (RMSE), and bias (B). The hydrologic evaluation was conducted with calibration and validation scenarios for the monsoon flooding season using the Integrated Flood Analysis System (IFAS) and flow duration curve (FDC). Sensitivity analysis was conducted using ±20% calibrating parameters. The rain gauge data have been found to be consistent with the higher coefficient of determination (R2). The mean skill scores of GSMaP were superior to those of CHIRPS and IMERG. More bias was observed during the monsoon than during western disturbances. The most sensitive parameter was the base flow coefficient (AGD), with a high mean absolute sensitivity index value. During model calibration, good values of performance indicators, i.e., R2, Nash−Sutcliffe efficiency (NSE), and percentage bias (PBIAS), were found for the used SPPs. For validation, GSMaP performed better with comparatively higher values of R2 and NSE and a lower value of PBIAS. The FDC exhibited SPPs' excellent performance during 20% to 40% exceedance time. [ABSTRACT FROM AUTHOR]

We propose in this paper a new multiphase Cahn–Hilliard model with doubly degenerate mobilities. We prove by a formal asymptotic analysis that it approximates with second order accuracy the multiphase surface diffusion flow with mobility coefficients and surface tensions. To illustrate that it lends itself well to numerical approximation, we propose a simple and effective numerical scheme together with a very compact Matlab implementation. We provide the results of various numerical experiments to show the influence of mobility and surface tension coefficients. Thanks to its second order accuracy and its good suitability for numerical implementation, our model is very handy for tackling notably difficult surface diffusion problems. In particular, we show that it can be used very effectively to simulate numerically the dewetting of thin liquid tubes on arbitrary solid supports without requiring nonlinear boundary conditions. [ABSTRACT FROM AUTHOR]

A variable geometry auxiliary inlet for a wide-body aircraft environmental control system with moveable deflectors operating in a large mass flow rate range is studied through numerical simulation and wind tunnel tests, which yields a design method for the variable geometry auxiliary inlet with high performance. The characteristics of the flow field are studied by numerical simulation. The results show that the favorable pressure gradient and the roll-up vortices are the major impetus that inhales the incoming flow into the inlet. The law of regulation and the performance variation under different conditions are obtained by wind tunnel test. The flow coefficient increases first but then decreases with the increase in the inlet opening, and the pressure rise ratio and total pressure recovery coefficient increase first and then decrease with the increase in the mass flow rate. In general, under the condition of a high Mach number (Ma > 0.4), the inlet opening of this test configuration should not exceed 50%. The deflectors can maintain the normal work of the environmental control system by moving properly to control the mass flow rate of the auxiliary inlet. [ABSTRACT FROM AUTHOR]

A method has been developed for simultaneous concentration of molybdenum isotopes with intermediate atomic mass in two additional products of a multi-flow cascade with a given number of centrifuges in stages. The method takes into account the dependence of the separation factors of the cascade stages on the feed flow of gas centrifuges and the flow division coefficient, which makes it possible to calculate the most efficient operating modes. On its basis, a computational experiment on the separation of molybdenum hexafluoride was carried out. The influence of factors related to the cascade feed flow and to the number of stages and gas centrifuges is investigated. It is shown that the feed flows and the separation factors of the stages of gas centrifuge cascades differ significantly from rectangular and rectangular-partitioned cascades. [ABSTRACT FROM AUTHOR]

The length of long marshalling freight train and the non-streamline shape of wagon lead to more difficulties in simulating the aerodynamic performances. To simplify the simulation process of long freight trains and conserve computational resources, periodic boundary conditions and the improved delayed detached eddy simulation based on the shear-stress transport k-ω turbulence model were employed in this study. To better analyze the aerodynamic coefficients of full-scale, nine-boxcar, and periodic-boundary simulations, the pressure and viscous drag were analyzed separately. Aerodynamic coefficients and surrounding flows of freight trains obtained from periodic-boundary, full-scale, and nine-boxcar simulation methods are compared in detail to investigate the feasibility of the periodic-boundary condition for numerical simulations of long freight trains. The dependence of the computational mesh was verified in the STAR-CCM + software. Simulation results show that the deviations of drag coefficient under the periodic-boundary and full-scale conditions is 7.6 %, and that of the nine-boxcar and full-scale conditions is 5.7 %. Based on the simulated flow fields, the variations of pressure and velocity fields around the test wagon are similar in these three simulations. Besides, the distribution of detached vortices around the test wagon are similar in simulations. Moreover, locomotive has no significant influence on aerodynamic performances of the fifth wagon in the simulation of one locomotive with nine boxcars. In this study, the computing time of full-scale condition is 58 hours, and that of periodic-boundary condition is one-tenth of full-scale condition. Consequently, it can be concluded that the periodic boundary is a potential choice in aerodynamic simulations of a long freight train, better balancing the simulation accuracy and efficiency. [ABSTRACT FROM AUTHOR]

The CFD (Computational Fluid Dynamics) method can be used in various areas that concern almost every field of technology, including water bodies, air spaces, as well as technical devices and machines. A finite difference algorithm determines the velocity and pressure of the oil film, while the pressure coefficient of the flow field is calculated to predict the cavitation initial position at different texture distribution densities. As part of the preliminary CFD tests, the pressure and speed distributions of the flow control valve were obtained, and the nozzle flow coefficients were determined as a function of the valve spool position. [Extracted from the article]