Coupling Method Research Articles

Influence of solid particles in liquid tank on sloshing behaviour based on CFD-DEM coupling method

This paper employs multiphase flow theory to investigate the influence of different solid particle densities on the sloshing characteristics within a liquid tank. A numerical model of gas-liquid-solid multiphase flow sloshing motion within the tank was established using the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) coupling method, simulating the interactive coupling between the two-phase fluid and solid particles. In this context, the gas-liquid two-phase fluid is treated as a continuous phase, described under the Eulerian framework, with the Volume of Fluid (VOF) method applied to capture the gas-liquid interface. Conversely, the solid particles are treated as a discrete phase, described under the Lagrangian framework. The effects of different solid particle densities on the tank sloshing characteristics were analyzed utilizing the STAR-CCM + software platform. Initially, the validity of the CFD-DEM method was confirmed by simulating classical scenarios such as a single spherical particle falling from air into water and the flow dynamics of a gas-liquid-solid three-phase dam break. Subsequently, a numerical simulation of sloshing in a pure water tank was conducted and compared with published experimental results, thereby verifying the feasibility of the numerical method for gas-liquid two-phase sloshing. Following this, a series of simulations were conducted on a pure water tank to validate the effectiveness of the numerical method for gas-liquid two-phase fluid sloshing. Subsequently, solid particles were introduced to the model, and the effect of solid particle densities on sloshing load and response under forced motion was studied. Finally, by comparing and analyzing the sloshing-induced pressure on the tank walls and the amplitude of the free surface motion across different solid particle densities and as well as different excitation frequencies, the sloshing characteristics of the solid-liquid mixed two-phase flow were investigated. The computational results indicate that an increase in solid particle density corresponds to an increase in liquid surface wave amplitude. This suggests that lighter solid particles have a greater damping effect on tank sloshing. It can be inferred that when the density of solid particles is maintained at a constant level, the closer the external excitation frequency is to the natural frequency, the more effective the sloshing suppression effect. This is attributed to the fact that, as sloshing intensifies, fluid velocity increases, resulting in greater damping due to viscosity effects, thereby enhancing the sloshing suppression.

Assessing pre-season workload variation in professional rugby union players by comparing three acute:Chronic workload ratio models based on playing positions

Quantifying the pre-season workload of professional Rugby Union players, in relation to their respective positions not only provides crucial insights into their physical demands and training needs but also underscores the significance of the acute:chronic workload ratio (ACWR) in assessing workload. However, given the diversity in ACWR calculation methods, their applicability requires further exploration. As a result, this study aims to analyze the workload depending on the player's positions and to compare three ACWR calculation methods. Fifty-seven players were categorized into five groups based on their playing positions: tight five (T5), third-row (3R), number nine (N9), center, and third line defense (3L). The coupled and uncoupled rolling averages (RA), as well as the exponentially weighted moving average ACWR method, were employed to compute measures derived from GPS data. Changes throughout the pre-season were assessed using the one-way and two-way analysis of variance. The results revealed that N9 covered significantly greater distances and exhibited higher player load compared to T5 and 3L [p < 0.05, effect size (ES) = 0.16–0.68]. Additionally, 3L players displayed the highest workload across various measures, including counts of accelerations and decelerations (>2.5 m s−2), accelerations (>2.5 m s−2), acceleration distance (>2 m s−2), high-speed running (>15 km h−1), very high-speed running (>21 km h−1, VSHR), sprint running (>25 km h−1, SR) distance. When using coupled RA ACWR method, centers exposed significantly greater values to T5 (p < 0.05, ES = 0.8) and 3R (p < 0.05, ES = 0.83). Moreover, centers exhibited greater (p < 0.05, ES = 0.67–0.91) uncoupled RA ACWR values for VHSR and SR than T5 and 3R. When comparing the three ACWR methods, although significant differences emerged in some specific cases, the ES were all small (0–0.56). In light of these findings, training should be customized to the characteristics of players in different playing positions and the three ACWR calculation methods can be considered as equally effective approaches.

Research on Multiphyics bidirectional coupling for small-diameter high-speed submersible permanent magnet synchronous motor

The small-diameter high-speed submersible permanent magnet synchronous motor (SHS-PMSM) is essential equipment for rodless oil and gas extraction in slimhole wells and high-water content oil wells. The SHS-PMSM typically operates for extended periods of time underground in high temperatures. Because of its compact size, the heat is difficult to dissipate, which increases the risk of motor overheating and damage. In order to accurately predict temperature, the method of magnetic-heat-flow multiphysics bidirectional coupling is studied in this paper. A SHS-PMSM with an outer diameter of ø89mm is taken as the object, and its copper loss, friction loss and convective heat transfer coefficient are studied by analytical derivation. The relationship between them and temperature are expressed by functions which can be compiled into User-Defined Functions (UDFs) as variable during the calculation process of finite volume method. Both coupling calculations and experiments are conducted. The temperature calculated by magnetic-heat-flow bidirectional connection is higher than that produced by the conventional method and more in line with experimental results after the results of both simulations and experiments are carried out and compared. The accuracy of the magnetic-heat-flow bidirectional coupling method is verified and the design basis of temperature for SHS-PMSM can be provided.

Electrothermal coupling analysis of submarine cables

ABSTRACT With offshore wind power transmission engineering development, submarine cable laying plays an important role in energy supply. Deep-water heavy-current composite submarine cables generate heat during power transmission, which raises their temperature and impacts energy efficiency and mechanical properties. To address the issue of heat release affecting structural sections during cable operation, a structural temperature field calculation theory is introduced, establishing a method for calculating the temperature field of submarine cables.The IEC standard's equivalent thermal circuit method and COMSOL Multiphysics' electromagnetic, thermal coupling method were employed to assess the current carrying capacity at the insulation temperature. The finite element model's accuracy was confirmed by comparing manufacturer-provided parameters. Additionally, a 3D finite-element model of the cable was created to determine its tensile, bending, and torsional stiffness with and without the electric-heat-force field coupling.

Theoretical approaches to study degradation in Li-ion battery cathodes: Crucial role of exchange and correlation

Abstract Li-ion batteries have become essential in energy storage, with demand rising steadily. Cathodes, crucial for determining capacity and voltage, face challenges like degradation in the form of thermal runaway and battery failure. Understanding these degradation phenomena is vital for developing mitigation strategies. Experimental techniques such as XAS, XPS, PES, UV–Vis, RIXS, NMR, and OEMS are commonly used, but theoretical modelling, particularly atomistic modelling with density-functional theory (DFT), provides key insights into the microscopic electronic behaviours causing degradation. While DFT offers a precise formulation, its approximations in the exchange-correlation functional and its ground-state, 0K limitations necessitate additional methods like ab initio molecular dynamics. Recently, many-body electronic structure methods have been used alongside DFT to better explain electron–electron interactions and temperature effects. This review emphasizes material-specific methods and the importance of electron–electron interactions, highlighting the role of many-body methods in addressing key issues in cathode degradation and future development in electron–phonon coupling methods. Graphical abstract

Leakage detection method based on transient pressure behaviors during pigging process in pipelines

Pipelines are the most common way to transport oil and gas due to its convenience. They are facing many threatens such as leakage, which may cause serious pipeline accidents. This paper proposes a leakage detection method coupled with the transient pressure characteristics to recognize leaks in pipeline. A coupled dynamic mesh method was used to achieve the movement of pigging device. The explicit and implicit coupling method has been developed to simulate transient pressures and leak behaviors. Cases has been conducted through the established experimental pipeline system to validate the proposed leakage detection method. The reasonable agreement between the results from these two methods verify that the proposed leakage detection method is accurate enough to simulate transient pressure behaviors in pipelines during the pigging process. Leak volume and location identification methods have been presented and the calculation accuracy is verified in a reasonable range. The proposed leakage detection method in this paper is a supplement to the field of subsea pipeline detection.

Insights into the scale effects on ship motions and wave loads considering hydroelasticity

To investigate the scale effects on ship seakeeping and wave loads, ship motions and wave loads considering hydroelasticity responses of a 310-m-long ship are calculated in four different scales, i.e., model scale 1:100, 1:50, 1:25 and full-scale 1:1 by using a partitioned CFD-FEM two-way coupled method. The simulation results of the 1:50 scaled model are also compared with tank experimental data of a segmented model with a same scale and configuration for validation. Then the hydrodynamic coefficients, incident waves, heave and pitch motions, vertical bending moment, vertical shearing force and whipping loads obtained by different scaled simulations are compared and the associated scale effects are systematically analyzed. This paper also investigates the influence of segment scheme and backbone configuration on ship modal characteristics, which sheds some light on the design of segmented models with backbone for hydroelasticity experiments.

Fatigue life prediction of cracked cross beam of mining linear vibrating screen under cyclic load

The cross beam of a mining linear vibrating screen is prone to cracking under long-term cyclic load. In order to accurately predict the fatigue life of the cracked cross beam, a coupled analysis method of vibration and crack propagation is proposed. A 2D dynamic model of the vibrating screen is established based on the finite element method, which is verified by the vibration test platform. The cracked Euler beam element is used to model the cracked cross beam. The effects of crack depth, amplitude of excitation force, frequency of excitation force, and crack location on the crack-tip stress intensity factor of the cracked cross beam are investigated in detail. In addition, an iterative method is proposed on the basis of the Paris model. The residual service life of the beam under different frequencies of excitation force, amplitudes of excitation force, spring stiffness, crack positions, and degrees of stiffness imbalance are discussed. The results demonstrate that the fatigue life of the beam increases as the frequency of excitation force and spring stiffness increase. The increase of the amplitude of excitation force and spring permanent deformation reduces the fatigue life. The conclusion obtained provide some theoretical guidance for the design and routine maintenance of mining linear vibrating screens.

The preparation of immunomagnetic beads based on oriented Ab and its application for AFB1 enrichment

The escalating issue of Aflatoxin B1 (AFB1) contamination has posed an alarming concern worldwide. Enrichment efficiency is crucial to accurately detecting trace amounts of AFB1. Immunomagnetic beads (IMBs) enrichment is beneficial for reducing operation time and labor intensity. In this work, oriented MBs@PG@mAbs was prepared as novel IMBs while MBs@SA@mAbs and MBs@mAbs were prepared as traditional IMBs. At equivalent antibody coupling amounts, the normalized Fab orientation of MBs@PG@mAbs, MBs@SA@mAbs, and MBs@mAbs were 100, 70.7, and 68.0%, respectively. The MBs@PG@mAbs exhibit good AFB1 enrichment, with a maximum capture efficiency of 96.2%, and the capture efficiencies of MBs@SA@mAbs, and MBs@mAbs were 95.8 and 94.9%, respectively. The reliability and practicability of the proposed MBs@PG@mAbs for AFB1 enrichment were further evaluated using AFB1-spiked maize samples. The recoveries of MBs@PG@mAbs were 97.6, 95.0 and 94.2% when 2, 5 and 10 ng/g AFB1 were spiked in samples. The quantitative analysis results of the AFB1 in actual maize samples by MBs@PG@mAbs−ELISA and LC-MS/MS were consistent. Thus, the PG-mediated coupling method led to the most efficient enrichment performance and had the potential for further applications.

Photocatalytic Formamide Synthesis via Coupling of Electrophilic and Nucleophilic Radicals over Atomically Dispersed Bi Sites.

Formamide (HCONH2) plays a pivotal role in the manufacture of a diverse array of chemicals, fertilizers, and pharmaceuticals. Photocatalysis holds great promise for green fabrication of carbon-nitrogen (C-N) compounds owing to its environmental friendliness and mild redox capability. However, the selective formation of the C-N bond presents a significant challenge in the photocatalytic synthesis of C-N compounds. This work developed a photocatalytic radical coupling method for the formamide synthesis from co-oxidation of ammonia (NH3) and methanol (CH3OH). An exceptional formamide yield rate of 5.47±0.03 mmol ⋅ gcat -1 ⋅ h-1 (911.87±5 mmol ⋅ gBi -1 ⋅ h-1) was achieved over atomically dispersed Bi sites (BiSAs) on TiO2. An accumulation of 45.68 mmol ⋅ gcat -1 (2.0 g ⋅ gcat -1) of formamide was achieved after long-term illumination, representing the highest level of photocatalytic C-N compounds synthesis. The critical C-N coupling for formamide formation originated from the "σ-σ" interaction between electrophilic ⋅CH2OH with nucleophilic ⋅NH2 radical. The BiSAs sites facilitated the electron transfer between reactants and photocatalysts and enhanced the nucleophilic attack of ⋅NH2 radical on the ⋅CH2OH radical, thereby advancing the selective C-N bond formation. This work deepens the understanding of the C-N coupling mechanism and offers an intriguing photocatalytic approach for the efficient and sustainable production of C-N compounds.

Numerical investigation of thermal soak within engine bay using lattice Boltzmann method

A large amount of heat accumulates in the engine bay for a short time after the engine runs at high load and shuts down, that will lead to thermal damage and thermal fatigue caused by the temperature rise of some heat sensitive components. This paper uses an aero-thermal coupling approach to study the heat transfer problem in the engine bay of an SUV model under thermal soak conditions. Due to the transient characteristics of the heat transfer process, the natural transient CFD software developed based on the LBM method is used to study the engine bay heat transfer during the 400 s key-off soak process. The analysis reveals that convection and radiation are the main heat transfer modes in the early stage of hot immersion (0–120 s), and conduction only makes a significant contribution in contact with high temperature sources. The radiation and convection are the key contributors to heat transfer processes of engine bay during soak, but the efficiency of radiation heat transfer decreases with the increase of time, whereas the efficiency of convection heat transfer is not always reduced, it will increase and then decrease with the increase of time. The coupling method established can predict the thermal state in the engine bay well, and is in good agreement with the experimental results. The results show that the error in the engine coolant temperature is less than 1 °C, and the error in the temperature of the heat-sensitive components is less than 5 °C. Finally, the potential risks of thermal damage and thermal fatigue states were assessed, providing an important reference for the control design of cooling fan running time after key-off.

Strength and Vibration Analysis of Axial Flow Compressor Blades Based on the CFD-CSD Coupling Method

During the operational process of an axial-flow compressor, the blade structure is simultaneously subjected to both aerodynamic loads and centrifugal loads, posing significant challenges to the safe and reliable operation of the blades. Considering both centrifugal loads and aerodynamic loads comprehensively, a bidirectional CFD-CSD coupling analysis method for blade structure was established. The Navier–Stokes governing equations were utilized to solve the internal flow field of the axial-flow compressor. The conservative interpolation method was utilized to couple and solve the blade’s static equilibrium equation, and the deformation, stress distribution, and prestress modal behavior of compressor blades were mainly analyzed. The research results indicate that the maximum deformation of the blades occurred at the lead edge tip, while stress predominantly concentrated approximately 33% upward from the blade root, exhibiting a radial distribution that gradually decreased. As the rotational speed increased, the maximum deformation of the blades continuously increased. Furthermore, at a constant rotational speed, the maximum deformation of the blade exhibited a trend of first increasing and then decreasing with the increase in mass flow. In contrast, the maximum stress showed a trend of first increasing, then decreasing, and finally increasing again as the rotational speed continuously increased. Centrifugal loads are the primary factor influencing blade stress and natural frequency. During operation, the blades exhibited two resonance points, approximately occurring at 62% and 98% of the design rotational speed.

Photocatalytic Formamide Synthesis via Coupling of Electrophilic and Nucleophilic Radicals over Atomically Dispersed Bi Sites

AbstractFormamide (HCONH2) plays a pivotal role in the manufacture of a diverse array of chemicals, fertilizers, and pharmaceuticals. Photocatalysis holds great promise for green fabrication of carbon‐nitrogen (C−N) compounds owing to its environmental friendliness and mild redox capability. However, the selective formation of the C−N bond presents a significant challenge in the photocatalytic synthesis of C−N compounds. This work developed a photocatalytic radical coupling method for the formamide synthesis from co‐oxidation of ammonia (NH3) and methanol (CH3OH). An exceptional formamide yield rate of 5.47±0.03 mmol ⋅ gcat−1 ⋅ h−1 (911.87±5 mmol ⋅ gBi−1 ⋅ h−1) was achieved over atomically dispersed Bi sites (BiSAs) on TiO2. An accumulation of 45.68 mmol ⋅ gcat−1 (2.0 g ⋅ gcat−1) of formamide was achieved after long‐term illumination, representing the highest level of photocatalytic C−N compounds synthesis. The critical C−N coupling for formamide formation originated from the “σ–σ” interaction between electrophilic ⋅CH2OH with nucleophilic ⋅NH2 radical. The BiSAs sites facilitated the electron transfer between reactants and photocatalysts and enhanced the nucleophilic attack of ⋅NH2 radical on the ⋅CH2OH radical, thereby advancing the selective C−N bond formation. This work deepens the understanding of the C−N coupling mechanism and offers an intriguing photocatalytic approach for the efficient and sustainable production of C−N compounds.

Vibroacoustic Analysis of Laminated Composite L-shaped Acoustic Cavity using Multi-domain Coupled BE-FE Method

Vibroacoustic Analysis of Laminated Composite L-shaped Acoustic Cavity using Multi-domain Coupled BE-FE Method

Numerical Determination of Anisotropic Permeability for Unconsolidated Hydrate Reservoir: A DEM–CFD Coupling Method

Numerical Determination of Anisotropic Permeability for Unconsolidated Hydrate Reservoir: A DEM–CFD Coupling Method

Mechanical properties and ductility improvement mechanisms of fiber-reinforced biomimetic mineralized composites using sea sand

Biomimetic mineralized composites (BMC) is an emerging green cementing material. However, the application of BMC is limited by brittle failure. This study proposes novel fiber-reinforced biomimetic mineralized composites (FRBMC) with excellent ductility based on the coupling method of fiber reinforcement and biomimetic chemically induced calcium carbonate precipitation (BCICP). Three typical fibers, including polymer fibers (polypropylene fiber, PF), mineral fibers (basalt fiber, BF), and plant fibers (coir fiber, CF), were used to explore the feasibility of application in FRBMC. Accordingly, mechanical properties, pore structures, and microscopic characteristics were assessed through unconfined compressive strength (UCS) test, mercury intrusion porosimetry (MIP) tests, and scanning electron microscopy (SEM). The results show that fiber induces a transition from brittle to ductile failure modes in BMC. PF exhibits the most notable enhancement in residual strength and peak strain, while BF leads to the highest compressive strength. CF can effectively enhance energy absorption after reaching peak stress. Moreover, FRBMC with CF contains a higher quantity of minute pores, while BF can reduce the porosity of FRBMC. The calcium carbonate crystals effectively cement fibers and sand particles, enhancing the ductility of FRBMC through forming various cementing structures. This study investigates the synergistic effect of BCICP and fiber reinforcement, providing valuable guidance for potential practical applications of FRBMC.

Interior-point policy optimization based multi-agent deep reinforcement learning method for secure home energy management under various uncertainties

Improving the efficiency of home energy management (HEM) is of great significance in reducing resource waste and prompting renewable energy consumption. With the development of advanced HEM systems and internet-of-things technology, more residents are willing to participate in the electricity market through a demand response mechanism, which can not only reduce the electricity bill but also stabilize the operation of the main grid through peak shaving and valley filling. However, the uncertainties from household appliance parameters, user behaviors, penetrated renewable energy, and electricity prices render the HEM problem a non-trivial task. Although previous deep reinforcement learning (DRL) methods have no requirement for system dynamics due to their model-free and data-driven merits, the unrestricted action space may violate the physical constraints of various devices, and few works have concentrated on this area before. To solve the above challenges, this paper proposes a novel interior-point policy optimization-based multi-agent DRL algorithm to optimize the home energy scheduling procedure while guaranteeing safety during its operation. Besides, a time-series prediction model based on a non-stationary Transformer neural network is proposed to predict the future trend of solar generation and electricity price, which can provide the agents with abundant information to make better decisions. The superior performance of our proposed predictive-control coupled method is demonstrated through extensive numerical experiments, which achieves more precise prediction results, near-zero constraint violations, and better trade-offs between cost and safety than several benchmark methods.

Non-uniform variation characteristics of temperature field and corresponding thermal effect of longitudinal continuous slab ballastless track structure

The longitudinal continuous slab ballastless track structure (LCSBTS) easily suffers from interface and joint damage when subjected to extremely high-temperature loads, significantly affecting the running smoothness and safety of high-speed trains. This paper establishes a numerical model of the LCSBTS using the heat transfer principle and real-time shadow technology to replicate the time-varying evolution and spatial distribution of the temperature field. The corresponding thermal effect is obtained based on the sequential thermal-mechanical coupling method. The results show that the temperature variation and the corresponding thermal effect exhibit strong temporal-spatial non-uniformity on the horizontal and vertical planes of the LCSBTS. Solar radiation and heat convection are the dominant factors for the temperature field of the LCSBTS in the daytime and night, respectively, resulting in a higher temperature and greater thermal deformation on the sunny side than on the shady one. The temperature and vertical thermal deformation along the longitudinal direction vary periodically with a specific wavelength between the two adjacent rail support concrete blocks. The thermal deformation increments under the studied non-uniform temperature loads cause an interface damage increment. Finally, the consideration of a non-uniform temperature load produces remarkably different thermal effects from those given by the design temperature load.

2‐DPC Mediated Effective Synthesis of Peptide Conjugates, their Antifungal and Antibacterial Properties

AbstractThe present work demonstrates the effective synthesis of amide derivatives of Nα‐protected amino acids and aryl/heteroaryl amines using di‐2‐pyridyl carbonate (2‐DPC) and cat. DMAP mediated coupling reaction. Several coupling methods were employed for the screening of the amides using EDC, HATU, mixed anhydride, T3P, CDI, COMU, DPTC, and 2‐DPC, where 2‐DPC/cat. DMAP method furnished amides with better yields and purity in shorter durations. Seventeen amide derivatives (3 a–3 q) were successfully synthesized using the present protocol and were characterized by NMR, mass and IR spectroscopy. Further, we performed the in‐silico and in‐vitro studies on the synthesized molecules on antifungal and antibacterial activity. Molecular docking studies reveal the binding affinity of protein‐ligand interactions ranging from −6.2 to −11.0 kcal/mol (Aspergillus Niger Esta), −5.9 to −9.9 kcal/mol (DNA gyrase subunit B) and −6.4 to −13.4 kcal/mol (CYP51B). Compounds like 3 d, 3 e, 3 h, 3 i, 3 j and 3 l exhibit the highest antibacterial and antifungal activity when compared to the standards delafloxacin, ketoconazole, and bifonazole in in‐silico studies. Whereas the in‐vitro studies also unveiled good antimicrobial activity with peptide conjugates. The results of antimicrobial activity exhibits in antifungal species show the good activity concentrations in compounds 3 j is 11.2±3.54 μg/mL and 3 l is 10.3±2.76 μg/mL. The anti‐bacterial species exhibit the compound 3 g showing good activity in different concentrations 12±3.08 μg/mL, 12.2±3.04 μg/mL, 12.6±2.78 μg/mL and 12.5±2.98 μg/mL.

Silica-Polymer Heterogeneous Hybrid Integrated Mach-Zehnder Interferometer Optical Waveguide Temperature Sensor.

In this paper, a temperature sensor based on a polymer-silica heterogeneous integrated Mach-Zehnder interferometer (MZI) structure is proposed. The MZI structure consists of a polymer waveguide arm and a doped silica waveguide arm. Due to the opposite thermal optical coefficients of polymers and silica, the hybrid integrated MZI structure enhances the temperature sensing characteristics. The direct coupling method and side coupling method are introduced to reduce the coupling loss of the device. The simulation results show that the side coupling structure has lower coupling loss and greater manufacturing tolerance compared to the direct coupling structure. The side coupling loss for PMMA material-based devices, NOA material-based devices, and SU-8 material-based devices is 0.104 dB, 0.294 dB, and 0.618 dB, respectively. The sensitivity (S) values of the three hybrid devices are -6.85 nm/K, -6.48 nm/K, and -2.30 nm/K, which are an order of magnitude higher than those of an all-polymer waveguide temperature sensor. We calculated the temperature responsivity (RT) (FSR→∞) of the three devices as 13.16 × 10-5 K, 32.20 × 10-5 K, and 20.20 × 10-5 K, suggesting that high thermo-optic coefficient polymer materials and the hybrid integration method have a promising application in the field of on-chip temperature sensing.