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Records with Subject: Modelling and Simulations
Showing records 51 to 75 of 5392. [First] Page: 1 2 3 4 5 6 7 Last
Microparticles’ Lateral Oscillation Motion in Serpentine Micro-Channels without Inertial Lift Effects
Yang Liu, Xintao Hu, Jiayuan Ma, Feng Gao, Yanan Gao, Linbo Yan
September 21, 2023 (v1)
Keywords: dean drag, lateral motion, micro particles, serpentine microchannel
Micro-particle manipulation, based solely on the Dean drag force, has begun to be advocated for with the goal of lowering the pumping pressure and simplifying the complexity of the coupling effects of the inertial lift force and the Dean drag force, thus reducing the difficulty of theoretically predicting particle motion. We employed the CFD-DEM two-way coupling method in this work to quantitatively study the lateral (z in axis) motion of particles (7−10 μm), in square or half-circle segment serpentine microchannels, that was only reliant on Dean drag with the blockage ratio dDh= 0.04 (the inertial lift effects show at dDh>0.07). In the square-segment serpentine channel, under the conditions of single-side-wall sheath flow and sedimentation, we discovered that the particles exhibit a twist-type lateral trajectory around each turn, with the larger particles always twisting in the opposite direction of the smaller particles, as a result of the four-grid-pattern distribution of the latera... [more]
Optimization of Drilling Parameters in Influence Area of Gas−Solid Interaction during Parallel Drilling Hole
Fengyan Zhang, Haidong Wang
September 21, 2023 (v1)
Keywords: directional boreholes, drilling parameters, gas extraction, numerical simulation, permeability
Previous studies have established that the selection of gas extraction borehole parameters is crucial for the effectiveness of gas extraction. To more accurately determine the reasonable extraction radius of gas extraction boreholes in the coal seam, this study was based on the actual occurrence conditions of the coal body. A coal-seam gas-seepage model, considering dynamic changes in permeability under gas−solid coupling conditions, was constructed. It was combined with FLAC3D numerical simulations to develop a borehole extraction model closer to the field’s natural needs. The study revealed the influence of borehole diameter and spacing on gas extraction, obtained the radius of effect of borehole extraction, and optimized the gas extraction borehole parameters based on data simulation experiments. Multiple sets of experimental results indicated that the optimal parameters are a borehole diameter of φ = 113 mm and a borehole spacing of 5 m. Applying these parameters in on-site tests a... [more]
Mixing Characteristics and Parameter Effects on the Mixing Efficiency of High-Viscosity Solid−Liquid Mixtures under High-Intensity Acoustic Vibration
Xiaobin Zhan, Lei Yu, Yalong Jiang, Qiankun Jiang, Tielin Shi
September 21, 2023 (v1)
Keywords: acoustic vibration, Computational Fluid Dynamics, high viscosity, Mixing, multiphase flow
High-intensity acoustic vibration is a new technology for solving the problem of uniform dispersion of highly viscous materials. In this study, we investigate the mixing characteristics of high-viscosity solid−liquid phases under high-intensity acoustic vibration and explore the effect of vibration parameters on the mixing efficiency. A numerical simulation model of solid−liquid−gas multiphase flow, employing the volume of fluid (VOF) and discrete phase model (DPM), was developed and subsequently validated through experimental verification. The results show that the movement and deformation of the gas−liquid surface over the entire field are critical for achieving rapid and uniform mixing of the solid−liquid phases under acoustic vibration. Increasing the amplitude or frequency of vibration can intensify the movement and deformation of the free surface of gas and liquid, improve the mixing efficiency, and shorten the mixing time. Under the condition of constant acceleration, the mixing... [more]
Modified Model and Simulation Verification of Rock-Fatigue Damage Considering Repeated Discharge Impact
Jianchun Guo, Xinyang Li, Cong Lu, Xinlei Zhu, Kun Huang, Shiqian Xu
September 21, 2023 (v1)
Keywords: discharge shock wave, fatigue damage, micro-crack, modify the model, numerical simulation
The existing rock-fatigue-damage constitutive model fails to consider the influence of discharge energy and discharge times on the effect of rock damage under discharge impact. In this regard, the impact load test of sandstone was carried out. Based on the test results, the quantitative characterization formula of different discharge parameters on the weakening degree of rock compressive strength was established. Based on the TCK (Taylor−Chen−Kuszmaul) model, a constitutive model considering the mechanical properties of rock and the dynamic hange of micro-crack geometric size is established, and the cohesive model is proposed to calculate the crack size. The constitutive model includes the relationship between crack width, crack number, and rock compressive strength, and the change of damage factor D is used to consider the fatigue-damage effect of discharge shock on the rock. The results show that the modified model can quantitatively and accurately reflect the dynamic damage and fail... [more]
Numerical Simulation of Flashing Flows in a Converging−Diverging Nozzle with Interfacial Area Transport Equation
Jiadong Li, Yixiang Liao, Ping Zhou, Dirk Lucas, Liang Gong
September 21, 2023 (v1)
Keywords: flashing flow, interfacial area concentration, interfacial area transport equation (IATE), two-fluid model (TFM)
Flashing flows of initially sub-cooled water in a converging−diverging nozzle is investigated numerically in the framework of the two-fluid model (TFM). The thermal non-equilibrium effect of phase change is considered by an interfacial heat transfer model, while the pressure jump across the interface is ignored. The bubble size distribution induced by nucleation, bubble growth/shrinkage, coalescence, and breakup is described based on the interfacial area transport equation (IATE) and constant bubble number density model (CBND), respectively. The results are compared with the experimental data. Satisfactory prediction of the axial pressure distribution along the nozzle as well as the flashing inception, is achieved by the TFM-IATE coupling method. It was also found that the vapor production in the diverging section was overpredicted, and the radial gas volume fraction distribution deviated from the experiment. The radial diameter profiles exhibit opposite patterns at the nozzle throat a... [more]
Modelling the Effect of Water Removal by Reverse Osmosis on the Distillation of Mixtures of Short-Chain Organic Acids from Anaerobic Fermentation
Serena Simonetti, Davide Dionisi
September 21, 2023 (v1)
Keywords: anaerobic fermentation, Distillation, reverse osmosis, short-chain organic acids
Anaerobic fermentation (AF) to produce sustainable short-chain organic acids (SCOAs) has found no commercial application so far. This is due to several limitations, including the high energy consumption of the SCOAs’ separation from water by distillation. This study used AspenPlus simulations to investigate the benefits of reverse osmosis (RO) to remove water and concentrate the SCOAs from AF before their separation by distillation. The effect of RO on distillation reflux ratio, heat energy requirements, column diameter and equipment costs was simulated for the processing of model SCOA-containing streams, representing AF effluents. A total of 90 simulations were carried out, investigating three different SCOA compositions, corresponding to different ratios of lactic, acetic and propionic acids, three different concentrations of the total SCOAs (10, 50, 100 g/kg in the stream entering RO) and different extents of water removal by RO. RO brought a reduction in the distillation reboilers’... [more]
Green Techniques for Detecting Microplastics in Marine with Emphasis on FTIR and NIR Spectroscopy—Short Review
Vlatka Mikulec, Petra Adamović, Želimira Cvetković, Martina Ivešić, Jasenka Gajdoš Kljusurić
September 21, 2023 (v1)
Keywords: ecotoxicological testing, health impact, Machine Learning, marine pollution, microplastics, microplastics analysis, novel methods
The amount of microplastics (MPs) present in marine ecosystems are a growing concern, with potential impacts on human health because they are associated with an increase in the ecotoxicity of certain foods, such as fish. As a result, there has been a growing interest in developing effective methods for the analysis of MPs in marine waters. Traditional methods for MP analysis involve visual inspection and manual sorting, which can be time-consuming and subject to human error. However, novel methods have been developed that offer more efficient and accurate analyses. One such method is based on spectroscopy, such as Fourier transform infrared spectroscopy (FTIR). Another method involves the use of fluorescent dyes, which can selectively bind to microplastics and allow for their detection under UV light. Additionally, machine learning approaches have been developed to analyze large volumes of water samples for MP detection and classification. These methods involve the use of specialized a... [more]
The Numerical Investigations of Heat Transfer and Bubble Behaviors of R22 in Subcooled Flow Boiling in Casing Tubes
Xiaodie Hu, Jinfeng Wang, Jing Xie, Bingjun Wang, Fei Wang
September 21, 2023 (v1)
Keywords: gas–liquid flow, numerical simulation, subcooled flow boiling, volume of fluid
Amidst the background of “double carbon”, energy saving and emission reduction is a popular direction in the current refrigeration industry. Therefore, the research on the boiling heat transfer of gas−liquid two-phase flow is helpful to strengthen the heat transfer and design a more efficient heat exchanger. In this paper, a research method combining numerical simulation and experimental verification is adopted. Firstly, an experimental platform used for the subcooled flow boiling of refrigerant in casing tubes is introduced and experiments are carried out to obtain experimental data, which provides a theoretical basis for the development of numerical simulation and verifies the feasibility of numerical simulation. A numerical model of subcooled flow boiling in R22 was established and the grid independence test was carried out. Based on the simulation results, three factors affecting the boiling heat transfer of R22 are analyzed: First, the boiling heat transfer coefficient of R22 incr... [more]
The Industrial Digital Energy Twin as a Tool for the Comprehensive Optimization of Industrial Processes
Alejandro Rubio-Rico, Fernando Mengod-Bautista, Andrés Lluna-Arriaga, Belén Arroyo-Torres, Vicente Fuster-Roig
September 21, 2023 (v1)
Keywords: digital twin, Energy, Energy Efficiency, productive flexibility, smart manufacturing
Industrial manufacturing processes have evolved and improved since the disruption of the Industry 4.0 paradigm, while energy has progressively become a strategic resource required to maintain industrial competitiveness while maximizing quality and minimizing environmental impacts. In this context of global changes leading to social and economic impact in the short term and an unprecedented climate crisis, Digital Twins for Energy Efficiency in manufacturing processes provide companies with a tool to address this complex situation. Nevertheless, already existing Digital Twins applied for energy efficiency in a manufacturing process lack a flexible structure that easily replicates the real behavior of consuming machines while integrating it in complex upper-level environments. This paper presents a combined multi-paradigm approach to industrial process modeling developed and applied during the GENERTWIN project. The tool allows users to predict energy consumption and costs and, at the sa... [more]
Counting Abalone with High Precision Using YOLOv3 and DeepSORT
Duncan Kibet, Jong-Ho Shin
September 21, 2023 (v1)
Keywords: abalone, abalone counting, abalone detection, deep learning, Machine Learning
In this research work, an approach using You Only Look Once version three (YOLOv3)-TensorFlow for abalone detection and Deep Simple Online Real-time Tracking (DeepSORT) for abalone tracking in conveyor belt systems is proposed. The conveyor belt system works in coordination with the cameras used to detect abalones. Considering the computational effectiveness and improved detection algorithms, this proposal is promising compared to the previously proposed methods. Some of these methods have low effectiveness and accuracy, and they provide an incorrect counting rate because some of the abalones tend to entangle, resulting in counting two or more abalones as one. Conducting detection and tracking research is crucial to achieve modern solutions for small- and large-scale fishing industries that enable them to accomplish higher automation, non-invasiveness, and low cost. This study is based on the development and improvement of counting analysis tools for automation in the fishing industry.... [more]
Numerical Simulation of Natural-Gas-Hydrate Decomposition in Process of Heat-Injection Production
Qiannan Yu, Huimin Tang, Chenglong Li, Zhijing Chen, Kun Zhang, Yang Yu, Shuang Liang
September 20, 2023 (v1)
Keywords: decomposition characteristics, decomposition front, heat-injection production, natural-gas hydrate, saturation distribution, temperature distribution
Heat-injection production is a common technique for gas-hydrate development, and the mechanism needs further in-depth study, particularly of the decomposition characteristics of natural-gas hydrate, which are important fundamental issues. The natural gas-hydrate-reservoir model is based on a mathematical description of reservoir properties that considers the effects of hydrate decomposition and reservoir stress conditions. The aim of our investigation was to analyze the production and decomposition characteristics of natural-gas hydrates based on the results of numerical simulations of heat-injection production. The effects of different heat-injection temperatures and heat-injection rates on production were compared, and the decomposition characteristics of hydrates were evaluated qualitatively and characterized quantitatively by temperature distribution, saturation distribution, and the decomposition front in the process of heat-injection production of natural-gas hydrate. The results... [more]
Establishment and Verification of the Kinetics Model of Uranium Continuous Dissolution by Using Discrete Element Method
Tianchi Li, Fang Liu, Jia Zhou, Chen Zuo, Taihong Yan, Weifang Zheng
September 20, 2023 (v1)
Keywords: continuous dissolution, discrete element method, dissolution kinetics, uranium pellets
Continuous dissolution of spent fuel is indeed one of the key technologies that can significantly improve the efficiency and stability of spent fuel reprocessing. The China Institute of Atomic Energy designed a prototype rotary drum dissolver, and the dissolution behavior of UO2 pellets in the dissolver was calculated using the Discrete Element Method. A kinetic equation was established to model the dissolution behavior, considering variables such as temperature, nitric acid concentration, and stirring intensity. The calculations showed that complete pellet dissolution took about 10 h in the continuous reaction, compared to 6 h in the batch dissolution experiment due to the gradual decrease in nitric acid concentration. A 16 h continuous dissolution experiment confirmed the calculated results, with a deviation of 10.8% between the simulation and experiment in terms of the mass of dissolved pellets. It was also found that it takes approximately 30 h to reach equilibrium in the continuou... [more]
A Novel Thermal Lattice Boltzmann Method for Numerical Simulation of Natural Convection of Non-Newtonian Fluids
Xiaofei Ren, Feifei Liu, Zheng Xin
September 20, 2023 (v1)
Keywords: heat transfer, lattice Boltzmann method, natural convection, non-Newtonian fluids, power–law model
A modified thermal Bhatnagar−Gross−Krook Lattice Boltzmann (BGK-LB) model was developed to study the convection phenomenon of non-Newtonian fluids (NNFs). This model integrates the local shear rate into the equilibrium distribution function (EDF) of the flow field and keeps the relaxation time from varying with fluid viscosity by introducing an additional parameter. In addition, a modified temperature EDF was constructed for the evolution equation of the temperature field to ensure the precise recovery of the convection−diffusion equation. To validate the accuracy and effectiveness of the proposed model, numerical simulations of benchmark problems were performed. Subsequently, we investigated the natural convection of power−law (PL) fluids and examined the impact of the PL index (n = 0.7−1.3) and Rayleigh number (Ra = 103−5 × 105) on the flow and temperature fields while holding the Prandtl number (Pr = 7) constant. The obtained results indicate that, for a given value of n, the convec... [more]
An Overview of Flashing Phenomena in Pressure Hydrometallurgy
Junda Liu, Bin Liu, Ping Zhou, Di Wu, Caigui Wu
September 20, 2023 (v1)
Keywords: flash tank, flashing process, gas–liquid–solid flow, numerical simulation, pressure hydrometallurgy
Pressure hydrometallurgy has attracted much attention for its characteristics, such as the high adaptability of raw materials and environmental friendliness. Flashing (flash boiling or flash evaporation) refers to the phase change phenomenon from liquid to gas triggered by depressurization, which is an important connection between high-pressure processes and atmospheric ones in pressure hydrometallurgy. This paper takes the flashing process in zinc leaching and alumina Bayer processes as examples, describes the flashing process in pressure hydrometallurgy in detail for the first time, and shows the importance of the flashing process in energy recovery, solution concentration, and liquid balance, as well as increasing equipment life. According to solid holdup (the volume percentage of solid), this paper proposes to divide the flashing process into solution flashing (low solid holdup) and slurry flashing (high solid holdup). A further focus is put on reviewing the state of the art of rel... [more]
The Process of Developing Model Research for the Technology of Obtaining Energy Resources
Dawid Szurgacz, Beata Borska, Lukáš Pospíšil, Dagmar Dlouhá, Jiří Pokorný, Sergey Zhironkin
September 20, 2023 (v1)
Keywords: hydraulic prop, longwall mining, mathematical model of the prop, numerical simulation, powered roof support
The current problems associated with the maintenance of hard coal longwall mining depend on the application or use of extraction technologies. In order to make the best use of these technologies, a new approach based on simulation studies is necessary. This paper aims to develop a mathematical model for the powered roof support’s operation. The three groups of professionals involved in the testing of the roof support were involved in the work on changing the hydraulic system of the powered roof support stand. These professionals were powered roof support’s designers, researchers and users. The research subject was the development of a mathematical model as a starting point for conducting simulations. The model is based on d’Alembert’s principle and the equation of the balance of flow rates. Based on the developed model, it is possible to determine the pressure in the space under the piston of the hydraulic prop. The results obtained in the simulations are the basic assumptions for the... [more]
Evaluation and Prediction of the Effect of Fabric Wetting on Coolness
Zijiang Wu, Yunlong Shi, Xiaoming Qian, Haiyang Lei
September 20, 2023 (v1)
Keywords: coolness sensation, random forest regression model, sensory evaluation, thermal absorptivity, wet state
As an important parameter of garment comfort, the thermal sensation of fabrics changes with factors such as sweat-induced humidity, making it a crucial area of research. To explore the coolness sensation of fabrics under different humidities, we tested heat transfer between fabrics and skin for 20 different fabrics with varying thermal absorption rates using fuzzy comprehensive evaluation to objectively assess their coolness levels. Subjective evaluation was then obtained by having subjects touch the fabrics and provide feedback, resulting in a subjective evaluation of their coolness levels. We compared the objective and subjective evaluations and found them to be highly consistent (R2 = 0.909), indicating accurate objective classification of fabric coolness levels. Currently, random forest regression models are widely used in the textile industry for classification, identification, and performance predictions. These models enable the prediction of fabric coolness levels by simultaneou... [more]
An Interpretable Predictive Model for Health Aspects of Solvents via Rough Set Theory
Wey Ying Hoo, Jecksin Ooi, Nishanth Gopalakrishnan Chemmangattuvalappil, Jia Wen Chong, Chun Hsion Lim, Mario Richard Eden
September 20, 2023 (v1)
Keywords: health indices, Machine Learning, organic solvents, rough set theory, rough set-based machine learning
This paper presents a machine learning (ML) approach to predict the potential health issues of solvents by uncovering the hidden relationship between substances and toxicity. Solvent selection is a crucial step in industrial processes. However, prolonged exposure to solvents has been found to pose significant risks to human health. To mitigate these hazards, it is crucial to develop a predictive model for health performance by identifying the contributing factors to solvent toxicity. This research aims to develop a predictive model for health issues related to solvent toxicity. Among various algorithms in ML, Rough Set Machine Learning (RSML) was chosen for this work due to its interpretable nature of the generated models. The models have been developed through data collection on the toxicity of various organic solvents, the construction of predictive models with decision rules, and model verification. The results reveal correlations between solvent toxicity and the Balaban index, vale... [more]
Analysis of Heat Transfer of the Gas Head Cover of Diaphragm Compressors for Hydrogen Refueling Stations
Shengdong Ren, Xiaohan Jia, Jiatong Zhang, Dianbo Xin, Xueyuan Peng
September 20, 2023 (v1)
Keywords: diaphragm compressor, heat transfer enhancement, simulation model, temperature distribution
The inadequate ability to dissipate heat of the gas head cover of the diaphragm compressor will result in its excessive temperature, which will put the operation of the hydrogen filling station at risk for safety issues and raise operating costs. This paper analyzed the structure and the heat transfer characteristics of the gas head cover, along with the relevant heat transfer boundaries, based on which a finite element simulation model of the temperature distribution was established. A test rig for the temperature test of a 22 MPa diaphragm compressor was built to validate this simulation model. The results indicated that the simulated temperatures agree well with the measured values, and the deviation is within 9.1%. Further, this paper proposed two head cover structures for enhancing the heat transfer according to the temperature field distribution characteristics, and the simulation and experimental verification were carried out, respectively. The findings demonstrate that the meth... [more]
YOLOv7-Based Anomaly Detection Using Intensity and NG Types in Labeling in Cosmetic Manufacturing Processes
Seunghyo Beak, Yo-Han Han, Yeeun Moon, Jieun Lee, Jongpil Jeong
September 20, 2023 (v1)
Keywords: anomaly detection, deep learning, object detection, YOLOv7
The advent of the Fourth Industrial Revolution has revolutionized the manufacturing sector by integrating artificial intelligence into vision inspection systems to improve the efficiency and quality of products. Supervised-learning-based vision inspection systems have emerged as a powerful tool for automated quality control in various industries. During visual inspection or final inspection, a human operator physically inspects a product to determine its condition and categorize it based on their know-how. However, the know-how-based visual inspection process is limited in time and space and is affected by many factors. High accuracy in vision inspection is highly dependent on the quality and precision of the labeling process. Therefore, supervised learning methods of 1-STAGE DETECTION, such as You Only Look Once (YOLO), are utilized in automated inspection to improve accuracy. In this paper, we proposed a labeling method that achieves the highest inspection accuracy among labeling met... [more]
Optimized Operation of Fluidized Catalytic Cracking Considering CO2 Fixation and Carbon Pricing
Yusuke Mori, Daisuke Okazaki, Gento Mogi
September 20, 2023 (v1)
Keywords: CO2 emission, decarbonizing, economic value, FCC, fluidized catalytic cracking, liquefied petroleum gas, LPG, operation patterns, plant optimization, process simulation
Recently, Japan and the European Union have been experiencing declining petroleum demand owing to global initiatives aimed at reducing environmental impact by curtailing CO2 emissions. Consequently, alternative products and operational conditions should be developed to utilize the fluid catalytic cracking (FCC) unit. Using simulation software (Aspen Hysys), this study modeled a typical FCC unit and compared the simulation results with operational data to ensure reproducibility. Two new process models were developed to investigate two scenarios: (i) the slurry discharged from the FCC unit is utilized as a feedstock for the FCC process and (ii) the slurry and fraction obtained from the downstream absorber of the FCC unit are introduced into a delayed coker unit to facilitate carbon fixation. Within an optimum riser outlet temperature (ROT) of 520−530 °C, the yields of gasoline and liquefied petroleum gas increased up to 4%. For profit performance, although ROT of 535−545 °C yielded peak... [more]
Fast Assisted History Matching of Fractured Vertical Well in Coalbed Methane Reservoirs Using the Bayesian Adaptive Direct Searching Algorithm
Zhijun Li
September 20, 2023 (v1)
Keywords: assisted history matching, Bayesian adaptive direct searching (BADS), coalbed methane, fractured vertical well, numerical simulation
The proper understanding of reservoir properties is an important step prior to forecasting fluid productions and deploying development strategies of a coalbed methane (CBM) reservoir. The assisted history matching (AHM) technique is a powerful technique that can derive reservoir properties based on production data, which however is usually rather time-consuming because hundreds or even thousands of numerical simulation runs are required before reasonable results can be obtained. This paper proposed the use of a newly developed algorithm, namely the Bayesian adaptive direct searching (BADS) algorithm, for assisting history matching of fractured vertical CBM wells to derive reservoir property values. The proposed method was applied on representative fractured vertical wells in the low-permeable CBM reservoirs in the Qinshui Basin, China. Results showed that the proposed method is capable of deriving reasonable estimates of key reservoir properties within a number of 50 numerical simulati... [more]
A CFD-Based Methodology for Impact Assessment of Industrial Emissions and Evaluation of Mitigation Measures for Regulatory Purposes
Elena Antuña-Yudego, Víctor Manuel Fernández-Pacheco, Eduardo Álvarez-Álvarez, Juan Luis Carús-Candás, María José Suárez-López
August 3, 2023 (v1)
Keywords: complex terrain scenario, computational fluid dynamics (CFD), industrial emissions plume behaviour, pollutant dispersion
In a context where air quality has become a global concern, modelling techniques are becoming very popular for analysing pollutant dispersion conditions. While models based on empirical formulations are most widely used for industrial scenarios, singular cases involving complex terrain or large obstacles in the vicinity of emission sources require a more robust approach to evaluate the dispersion conditions. In this research, a computational fluid dynamics (CFD) model is developed to analyse the dispersion of pollutants from an industrial facility whose location and characteristics suggest the occurrence of complex flow features that affect the dispersion patterns. In addition, the variation of the gas exit temperatures of waste heat recovery systems is proposed as a measure to mitigate the impact of the plume. The simulation results show unexpected deviations in the plume path affecting vulnerable areas in a nearby mountainside, but increasing the gas exit temperature is useful to pre... [more]
Influence of Gas Inlet Slit Width on Gas-Assisted Plastic Micro-Tube Extrusion
Shuiquan Chen, Xingyuan Huang, Bin Liu, Xiaohui Zhang
August 3, 2023 (v1)
Keywords: extrusion deformation, gas-assisted extrusion, gas–liquid two-phase model, numerical simulation
In the process of the double-layer gas-assisted extrusion of plastic micro-tubes, the external size and surface quality of the micro-tubes are greatly affected by the size of the assisting gas inlet slit inside the mold. Therefore, in this experiment, a two-phase flow model was established based on a compressible gas and a non-compressible melt. The Polyflow finite element solution software module was used to solve the velocity field, temperature field, pressure field, and section size of the melt under the condition of double-layer gas-assisted extrusion in a mold under different gas inlet slit widths. The results show that, with an increase in the width of the gas inlet slit, the melt outlet velocity increases, the surface temperature increases, wall thickness shrinkage increases, and interior diameter expansion increases. In the process of gas-assisted extrusion, the thickness of the air cushion is affected by adjusting the size of the gas inlet slit, and, hence, changes the shape a... [more]
Microwave-Assisted Extraction of Condensed Tannins from Branches of Prunus spinosa L.: Response Surface Modeling and Optimization
Oana Teodora Ciuperca (Apreutesei), Elena Ionescu, Marius Sebastian Secula, Irina Volf
August 3, 2023 (v1)
Keywords: condensed tannins, microwave-assisted extraction, process optimization, Prunus spinosa, response surface modeling, two-level factorial design
The present study was conducted in order to investigate the parameters influencing the extraction of condensed tannins from branches of Prunus spinosa L. as a source of biomass, using a two-level factorial design. The extraction of condensed tannins was performed using microwave assisted-extraction (MAE)—a green technique to produce concentrated and pure extracts. Experimental tests were run to establish the effects of independent variables on the extraction of condensed tannins (expressed as catechin and epicatechin), which were quantified using high-performance thin-layer chromatography−densitometry. Four process variables were evaluated: ethanolic solvent concentration (% v/v) (30, 70), liquid-to-solid ratio (mL/g) (6:1, 10:1), extraction time (min) (2, 5) and microwave power (W) (400, 600). The significant influencing parameters were liquid-to-solid ratio and solvent concentration. The maximum content of condensed tannins (3.4 mg g−1 catechin and 3.45 mg g−1 epicatechin) was obtain... [more]
Research on Coupling Adsorption Experiments for Wall−Climbing Robots in Coal Mine Shafts
Ying Xu, Wenjun Fu
August 3, 2023 (v1)
Keywords: composite shaft lining, coupled adsorption, electromagnetic circuit, fan full pressure, numerical simulation, power increment, velocity component
Based on the composite shaft lining structure, the research on the electromagnetic and negative pressure coupling adsorption technology of wall−climbing robots is of great significance to improve the level of safety monitoring during the construction and service of coal mine shafts. On the basis of theoretical research and computational data, the numerical simulation and simulation experiments of the coupled adsorption system of a wall−climbing robot are conducted in this research. In the ANSA software environment, of experimental models and experimental environments of electromagnetic and negative pressure adsorption devices are constructed to investigate, parameters such as air flow and the law behavior of fan pressure under different system conditions, including negative pressure and varying fan speeds. The intensity distribution of the magnetic flux inside the electromagnetic circuit under different working conditions and the law of change in the direction of movement are explored.... [more]
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