A new manufacturing process has been developed that involves drawing circular sheets of thin metal through a conical die to create square cups. This technique produces deep square cups with a height-to-punch-side length ratio of approximately 2, as well as high dimensional accuracy and a nearly uniform height. The study investigated how various factors, including the sheet material properties and process geometric parameters, affect the limiting drawing ratio (LDR). The researchers used finite element analysis to determine the optimal die design for achieving a high LDR and found that the proposed technique is advantageous for producing long square cups with high dimensional accuracy.

During the development of condensate gas reservoirs, the phenomenon of retrograde condensation seriously affects the production of gas wells. The skin factor caused by retrograde condensation pollution is the key to measuring the consequent decrease in production. In this study, a multiphase flow model and a calculation model of retrograde condensate damage are first constructed through a dynamic simulation of the phase behavior characteristics in condensate gas reservoirs using the skin coefficient, and these models are then creatively coupled to quantitatively evaluate retrograde condensation pollution. The coupled model is solved using a numerical method, which is followed by an analysis of the effects of the selected formation and engineering parameters on the condensate saturation distribution and pollution skin coefficient. The model is verified using actual test data. The results of the curves show that gas−liquid two-phase permeability has an obvious effect on well production.... [more]

Precision seeding technology is an important component of agricultural mechanization production. The precise regulation of seed movement behavior is the core of precision sowing technology and the key to improving the quality of single seed precision sowing. To accurately obtain the interaction law between seeds and soil after touching the soil, it is necessary to conduct comprehensive physical experiments to determine the simulation parameters of the seed and soil. This article takes coated cotton seeds as the research object, and the basic physical parameters of coated cotton seeds are measured through biological experiments. Based on the Hertz−Mindlin with bonding V2 contact model, a simulation model of compression between coated cotton seeds and soil is established. Using peak compression force as the response value, a combination of physical experiments and simulation simulations was used to calibrate the simulation parameters of the simulation mode of coated cotton seeds and soil... [more]

The flow field structure and pressure pulsation characteristics in two series of trailing edges of a centrifugal pump are investigated using the SST k-w turbulence model. Series 1 involves varying the impeller exit angle, and Series 2 involves varying the impeller exit shape. The entropy generation rate analysis method is used to evaluate the numerical simulation results. Vortex cores within the flow field are identified by applying the Ω criterion. The influence of different trailing edge configurations on the energy loss characteristics of the pumps is explored. The dynamic mode decomposition (DMD) method is used to analyze pressure pulsations at the volute considering unsteady flows in centrifugal pumps with different trailing edge shapes. The findings suggest that different trailing edge shapes can be used to adjust the energy loss proportions in various components of the pump. In Series 1, the efficiency remains nearly constant with changes in the outlet angle on both sides of the... [more]

The production of high-quality castings without foundry defects at minimal production costs is a constant priority for foundries. Innovation and optimization of production processes are key to achieving this goal. Computer simulation of foundry processes offers a modern alternative to expensive and time-consuming experiments in real foundries and provides a reliable representation and analysis of casting and solidification processes. A detailed analysis of the casting and solidification simulation results allows the prediction of various risks that can cause defects in cast castings, thereby reducing their quality and, last but not least, the cost of their production. This paper deals with the analysis of a computer simulation of the casting of a brake disc in a Slovak foundry. This brake disc has had shrinkages and micro shrinkages that reduce the internal quality of the casting. These defects occurred in the ribs in the upper part of the casting under the feeders. A computer simulati... [more]

Thermal deformation of the rotor is a critical factor leading to radial air leakage in rotary air preheaters. However, previous studies have not comprehensively established the correlation between rotor thermal deformation during thermal operation and radial air leakage. This study addresses this gap by introducing a novel model for calculating radial air leakage, incorporating the thermal deformation of the rotor. To achieve this, we selected a three-section rotary air preheater from a 330 MW coal-fired unit boiler for investigation. This research begins by constructing a heat transfer−structure coupled numerical simulation model using Fluent and ANSYS Workbench. This model is employed to analyze the thermal deformation of the rotor under varying unit power generation loads. This paper meticulously examines the thermal deformation patterns of the rotor in diverse circumstances, explores their impact on air leakages, and provides a comprehensive analysis of air leakage fluctuations in... [more]

In the development of the Qianshao (QS) gas condensate reservoir, it is crucial to consider the phenomenon of retrograde condensation. Understanding the condensate saturation distribution with respect to time and space within the reservoir is essential for planning and implementing effective strategies for the future development of the QS gas condensate reservoir. In this paper, various PVT experiments (including reservoir oil recombination, flash separation, constant composition expansion, and constant volume depletion) were conducted to study the PVT properties and phase behavior of QS gas condensate fluid. Based on experimental data, our in-house PVT computation package was used to determine the appropriate EOS model parameters for the QS gas condensate. A four-step reservoir fluid characterization procedure and workflow for gas condensate reservoirs was developed. Furthermore, by analyzing the pressure-temperature phase envelope, the maximum possible condensate saturation in the QS... [more]

Temperature is a key factor affecting the insulation performance and operation safety of cable joints. Accurate acquisition of hot spot temperatures of cable joints is a difficult issue in cable operation and maintenance. Three-core cables may have unbalanced three-phase loads in actual operation. This paper takes a 10 kV three-core cable joint as the research object; based on the temperature field numerical simulation method, it analyzes the diffusion path of the main heat flow inside the joint and establishes an inversion model that fits the hot spot temperature of the joint through the surface temperature of the cable body. At the same time, considering the special situation of the unbalanced three-phase load of a three-core cable, the joint hot spot temperature inversion model of a three-core cable under an unbalanced three-phase load is further established. This paper further uses the cable joint multi-step unbalanced load temperature rise test to verify the accuracy of the cable... [more]

Channelrhodopsin-2 (ChR2) is an important tool for optogenetics, and some of its mutants are Ca2+-selective channels. However, the mechanism for Ca2+-selective permeation is still unclear. In this study, molecular dynamic (MD) simulations for the Ca2+ permeation of the CatCh mutant were carried out to investigate the fundamental features of the selectivity of Ca2+. Research on the conformational changes in the key residues near the central gate (CG) of the channel suggested that E83, E90, and D253 play an important role in Ca2+ conductivity. The clustering analysis indicates that the above “EED triad” acts as a filter, and Ca2+ can only pass through if the EED is in a certain conformation. It was also found that hydrated Ca2+ can be coordinated with carboxyl groups, resulting in the loss of part of the water molecules in the hydrated shell and a reduction in ionic radius, which helps Ca2+ enter the channel.

Considering a class of complex nonlinear systems whose dynamics are mostly governed by statistical regulations, the pattern-moving theory was developed to characterise such systems and successfully estimate the outputs or states. However, since the pattern class variable is not computable directly, this study establishes a clustered generalized cell mapping (C-GCM) to reveal system characteristics. C-GCM is a two-stage approach consisting of a pattern-moving-based description and analysis method. First, a density algorithm, named density-based spatial clustering of applications with noise (DBSCAN), is designed to obtain cell space Ω and the corresponding classification guidelines; this algorithm is initiated after the initial pre-image cells, and the total number of entity cells amounts to Ns. Then, the GCM provides several image cells based on a cell mapping function that refers to the multivariate ARMAX model. The global dynamic analysis employing both searching and storing algorithm... [more]

Aiming at the low efficiency of heavy-oil thermal recovery, a downhole multi-thermal fluid generator (DMTFG) can improve the viscosity reduction effect by reducing the heat loss of multi-thermal fluid in the process of wellbore transportation. The steam generated by the MDTFG causes damage to the packer and casing, owing to the return upwards along the annular space passage of the oil casing. To mitigate this damage, a heat transfer model for multi-channel coiled tubing wells and a prediction model for the upward return of the steam temperature field in the annulus were established with the basic laws of thermodynamics. Models were further verified by ANSYS. The results indicate the following four conclusions. First of all, when the surface pressure is constant, the deeper the located DMTFG, the shorter the distance for the steam to return would be. It is easier to liquefy the steam. Second, the higher the temperature of the steam produced by the downhole polythermal fluid generator, t... [more]

The heat-integrated distillation column (HIDiC) has more energy-saving potential than conventional distillation columns. However, its nonlinearity and coupling effects pose significant challenges for the online operation of the HIDiC. To overcome these challenges, it becomes necessary to utilize accurate nonlinear models for design optimization or control schemes. Traditional modeling methods require extensive tray information, implying the impractical use of numerous sensors in real-world applications. This paper proposes a modeling approach for the HIDiC based on a limited number of measurements. It only requires the measurement of a finite amount of tray information to construct a global model of the HIDiC. This method serves as an online observer, providing real-time information about the entire column, and also enables the prediction of tray concentration changes. The proposed model forms the basis for developing model-based online monitoring and control schemes. Experimental simu... [more]

With increasing computational capacities and advances in numerical methods, a simulation-based process and product design approach for spray dried products has become the focus of many researchers. In this context, a novel unresolved CFD-DEM simulation approach for single suspension droplets is presented, which models the drying and solidification process in a hot gas environment. The solidification process is described by the formation of bonds between the primary particles in the suspension droplet, showing a plausible solidification behavior, which starts when a critical solid concentration is reached at the droplet surface. The drying conditions for the single-droplet simulations are determined from a large-scale spray dryer simulation for different droplet size classes. The resulting solid particles from the CFD-DEM simulation show a higher tendency to form hollow particles at high drying rates when the locking point is reached at earlier stages of the drying process. Using these... [more]

A new idea to deal with the backmixing problem in a scaled-up multi-inlet vortex mixer is proposed in this paper. Firstly, a Reynolds-averaged Navier−Stokes−large-eddy simulation hybrid model was used to simulate the flow field in a vortex mixer, and the numerical simulation results were compared with those from a particle image velocimetry experiment in order to validate the shielded detached eddy simulation model in the rotating shear flow. Then, by adding a series of columns in the mixing chamber, the formation of wake vortexes was promoted. The flow field in the vortex mixer with different column arrangements were simulated, and the residence time distribution curves of the fluid were obtained. Meanwhile, the degree of backmixing in the vortex mixer was evaluated by means of a tanks-in-series model. In the total ten cases related with four groups of variables, it was found that increasing the diameter of the column was the most efficient for weakening the backmixing in the vortex m... [more]

Assessing oxidation−reduction potential (ORP) is of paramount importance in the efficient management of wastewater within both chemical and biological treatment processes. However, despite its critical role, insufficient information exists about how reactive chemical species generated by cold plasma (CP) in chemical treatment are associated with ORP and air flow rate. Therefore, we aim to identify the correlation between ORP and the removal of organic pollutants when using CP treatment. Additionally, we introduce a machine-learning-based operation to predict removal efficiency in the CP process. Results reveal a significant correlation of over 0.9 between real-time ORP and total organic carbon (TOC), which underscores the efficacy of ORP as a key parameter. This approach made it possible to control OH radical generation by regulating the air flow rate of the CP. This study posits that smart management facilitated by machine learning has the potential to enhance the economic viability o... [more]

In order to indirectly calculate the core temperature of a cable joint, an equivalent transient thermal circuit model of single-core cable joint by considering axial heat dissipation is proposed. Firstly, the temperature field of the middle joint of a 110 kV single-core cable is calculated by finite element method. Based on the heat dissipation path of the core, an improved equivalent thermal circuit model is proposed. The axial heat dissipation of the cable joint core is simplified to a thermal resistance and the temperature rise of the cable body core, the temperature calculation of the cable joint transient process is realized. Compared with the results of finite element simulation, the steady-state temperature errors of the thermal circuit model are within 1 °C, while the maximum temperature errors of the transient process shall not exceed 3 °C, which proves the validity of the model. This method can provide reference for temperature inversion and the dynamic current-carrying capac... [more]

In recent years, deep learning models have led to improved accuracy in industrial defect detection, often using variants of YOLO (You Only Look Once), due to its high performance at a low cost. However, the generalizability, fairness and bias of their outcomes have not been examined, which may lead to overconfident predictions. Additionally, the complexity added by co-occurring defects, single and multi-class defects, and the effect on training, is not taken into consideration. This study addresses these critical gaps by introducing new methodologies for analyzing dataset complexity and evaluating model fairness. It introduces the novel approach of co-occurrence impact analysis, examining how the co-occurrence of defects in sample images affects performance, and introducing new dimensions to dataset preparation and training. Its aim is to increase model robustness in the face of real-world scenarios where multiple defects often appear together. Our study also innovates in the evaluatio... [more]

The exploration of coal wettability is not only of paramount significance in the mitigation of coal dust and the development of coalbed methane, but it also provides crucial technical support for realizing the geological storage of CO2 within the ‘dual-carbon’ background. Molecular simulation serves as an effective means by which to investigate coal wettability at the microscopic level. This study employed a molecular dynamics simulation to investigate the wettability of coal across 13 distinct coal ranks. Through the analysis of trajectory files, and the incorporation of experimental data during the modeling process, the mechanisms governing the evolution of wettability were revealed. The results demonstrated that the contact angle on the surface of coal increases with the elevation of coal rank. The molecule relative concentration analysis revealed that, with increasing coal rank, the overlap range between water droplets and the coal slab decreases, the height increases, and the diff... [more]

An analysis of entropy generation and exergy efficiency can effectively explore the energy-saving potential of reheating furnaces. This paper simulated the combustion, flow, and heat transfer in a walking beam reheating furnace by establishing a half-furnace model. The entropy generation rate distribution of different thermal processes was numerically calculated. The effect of slab residence time and fuel distribution in the furnace was studied to optimize exergy efficiency. The results indicated that combustion and radiative heat transfer are the primary sources of entropy generation. Irreversible losses accounted for 26.39% of the total input exergy, in which the combustion process accounted for 16.43%, and radiative heat transfer accounted for 8.47%. Reducing the residence time by 60 min decreased irreversible exergy loss by about 2.5% but increased heat dissipation and exhaust exergy loss by 5.8%. Energy saving can only be achieved when the heat exchanger’s exergy recovery efficien... [more]

A pantograph is a key component on the tops of trains that allows them to efficiently tap electricity from power lines and propel them. This study investigates the possibility of using metal matrix composites (MMCs), specifically aluminum MMCs, as a material for making pantograph parts regarding the dynamics of the train’s movement and external meteorological conditions. In this study, a computer-aided design (CAD) model is created using PTC Creo design software and moves to detailed finite element analysis (FEA) simulations executed by the ANSYS software suite. These simulations are important in examining how the dynamic performance of pantographs can vary. The incorporation of Al MMC materials into the structure of the pantograph resulted in significant improvements in structural robustness, with equal stress reduced by up to 0.18%. Similarly, aluminum MMC materials reduced the strain energy by 0.063 millijoules. The outcomes not only give a new perspective to the implementation of m... [more]

The constitutive model refers to the mapping relationship between the stress and deformation conditions (such as strain, strain rate, and temperature) after being loaded. In this work, the hot deformation behavior of a Ni-Cr-Mo steel was investigated by conducting isothermal compression tests using a Gleeble-3800 thermal simulator with deformation temperatures ranging from 800 °C to 1200 °C, strain rates ranging from 0.01 s−1 to 10 s−1, and deformations of 55%. To analyze the constitutive relation of the Ni-Cr-Mo steel at high temperatures, five machine learning algorithms were employed to predict the flow stress, namely, back-propagation artificial neural network (BP-ANN), Random Committee, Bagging, k-nearest neighbor (k-NN), and a library for support vector machines (libSVM). A comparative study between the experimental and the predicted results was performed. The results show that correlation coefficient (R), root mean square error (RMSE), mean absolute value error (MAE), mean squar... [more]

In order to assess the stable operating duration of an ultrasonic vibration system, a reliability-based analysis method for the stability of the ultrasonic vibration system is proposed. Firstly, the failure mechanisms of the ultrasonic vibration system are analyzed, and the resonant frequency and amplitude are selected as two degradation features of the system. Subsequently, accelerated degradation experiments under different force loads were conducted, and the degradation model of the ultrasonic vibration system was established by comparing experimental data with degradation, distribution, and acceleration models. Finally, Copula functions were introduced to connect the two degradation features, resonant frequency, and amplitude, and lifetime curves were plotted under the influence of univariate and bivariate degradation factors. Through the analysis of the lifetime curves, the conclusion is drawn that the decay of amplitude is the primary indicator of system lifetime, and it is predi... [more]

Acid fracturing is an effective stimulation technology that is widely applied in carbonate reservoirs. An integrated model for acid fracturing without prepad treatment has been established. Compared with the previous models which use prepad for generating hydraulic fractures, this model can simultaneously simulate the fracture propagation and the acid etching of fracture surfaces, as well as the wormhole growth during acid fracturing. The influences of some essential factors have been studied through a series of numerical simulations, and the main conclusions are as follows. First, increasing the injected acid volume can expand the size of the formed hydraulic fractures and extend the propagation distance of the wormhole. Increasing the injected acid volume can also expand the etched width and extend the effective distance of the injected acid. Second, a high injection rate impels more acid to flow into the depth of a fracture before infiltration and reaction, resulting in the augmenta... [more]

Humanity is facing the challenge of reducing its environmental impact. For this reason, many specialists worldwide have been studying the processes of production and efficient use of energy. In this way, developing cleaner and more efficient energy systems is fundamental for sustainable development. The present work analyzed the technical feasibility of a solar-driven power-cooling system operating in a particular location in Mexico. The theoretical system integrates organic Rankine and single-stage absorption cooling cycles. A parabolic trough collector and a storage system integrated the solar system. Its performance was modeled for a typical meteorological year using the SAM software by NREL. The analyzed working fluids for the organic cycle include benzene, cyclohexane, toluene, and R123, while the working fluid of the absorption system is the ammonia-water mixture. The cycle’s first and second-law performances are determined in a wide range of operating conditions. Parameters such... [more]

To characterize the failure of rock mass surrounding underground tunnels, biaxial compression tests were conducted on a real sandstone model with a straight-walled arched hole. The acoustic emission (AE) system and digital image correlation (DIC) optical inspection equipment were used to investigate the crack evolution process and failure precursors of the tunnel. A two-dimensional particle flow code (PFC2D) was used to conduct numerical simulations on the sample, so as to investigate the mesoscopic failure mechanism of rock mass. The results show that the failure of the single tunnel constructed in sandstone occurs mainly in the walls on both sides (between the spandrels and arch feet), showing slabbing failure characteristics and a certain abruptness. The crack initiation in sandstone in early stage is not obvious, and the crack propagation in rock mass is rapid when acoustic emissions are enhanced. The small increments in the AE count and amplitude and the continuous reduction in th... [more]