In this research, we investigate the influence of a load-balancing strategy and parametrization on the speed-up of discrete element method simulations using Lethe-DEM. Lethe-DEM is an open-source DEM code which uses a cell-based load-balancing strategy. We compare the computational performance of different cell-weighing strategies based on the number of particles per cell (linear and quadratic). We observe two minimums for particle to cell weights (at 3, 40 for quadratic, and 15, 50 for linear) in both linear and quadratic strategies. The first and second minimums are attributed to the suitable distribution of cell-based and particle-based functions, respectively. We use four benchmark simulations (packing, rotating drum, silo, and V blender) to investigate the computational performances of different load-balancing schemes (namely, single-step, frequent and dynamic). These benchmarks are chosen to demonstrate different scenarios that may occur in a DEM simulation. In a large-scale rota... [more]

Molecular dynamics simulations were used to analyze the internal mechanism for the observed improvement in performance of nano-modified meta-aramid insulation paper from a microscopic point of view. The results showed that the k-polyphenylsilsesquioxane(PPSQ) modified meta-aramid insulation paper was superior to b-PPSQ modified meta-aramid insulation paper in terms of its thermal stability and mechanical and electrical properties. The analysis of microscopic parameters showed that the stiffness of k-PPSQ was less than that of b-PPSQ, and the hydroxyl groups on the open-loop system were more likely to enter the dispersed system, resulting in higher bonding strength, meta-aramid fiber chains between k-PPSQ molecules, and the formation of hydrogen bonds. Additionally, the nano-enhancement effects of k-PPSQ and b-PPSQ resulted in various improvements, including a reduction in pores between molecules in the blend model, an increase in the contact area, the formation of interfacial polarizat... [more]

This paper presents computational fluid dynamics (CFD) simulations of the flow around a horizontal axis hydrokinetic turbine (HAHT) found in the literature. The volume of fluid (VOF) model implemented in a commercial CFD package (ANSYS-Fluent) is used to track the air-water interface. The URANS SST k-ω and the four-equation Transition SST turbulence models are employed to compute the unsteady three-dimensional flow field. The sliding mesh technique is used to rotate the subdomain that includes the turbine rotor. The effect of grid resolution, time-step size, and turbulence model on the computed performance coefficients is analyzed in detail, and the results are compared against experimental data at various tip speed ratios (TSRs). Simulation results at the analyzed rotor immersions confirm that the power and thrust coefficients decrease when the rotor is closer to the free surface. The combined effect of rotor and support structure on the free surface evolution and downstream velocitie... [more]

Computational fluid dynamics (CFD) was utilized to investigate the deposition process and printability of rice paste. The rheological and preliminary printing studies showed that paste formed from rice to water ratio (100:80) is suitable for 3D printing (3DP). Controlling the ambient temperature at 47±5 °C also contributed to improving the printed sample’s structural stability. The viscoelastic simulation indicated that the nozzle diameter influenced the flow properties of the printed material. As the nozzle diameter decreased (1.2 mm to 0.8 mm), the die swell ratio increased (13.7 to 15.15%). The rise in the swell ratio was a result of the increasing pressure gradient at the nozzle exit (5.48×106 Pa to 1.53×107 Pa). The additive simulation showed that the nozzle diameter affected both the residual stress and overall deformation of the sample. CFD analysis, therefore, demonstrates a significant advantage in optimizing the operating conditions for printing rice paste... [more]

Uranium resource distribution and accurate reserve evaluation are important references for mineral investment and production. Eight kinds of interpolation methods in the Groundwater Modeling System (GMS), including ordinary kriging (OK), are used in this study to predict the spatial distribution of reserve-related parameters, such as uranium grade, ore thickness and uranium content per square meter. The present study draws the following conclusions: (1) Cross-validation found that the uranium grade value using the spherical method is the closest to the actual value. The spherical method has the best interpolation effect. (2) The relative error, which is +3.62%, between the uranium reserves that is calculated by the spherical interpolation method and that by the traditional calculation value is the smallest. (3) The setting of the number of interpolation grids is related to the actual number of boreholes. The ratio between the two will affect the accuracy of reserve estimation, and diff... [more]

At present, most of the incoming liquids from the oilfield combined stations are not pre-separated for natural gas, which makes the subsequent process of oil-water separation less effective. Therefore, it is necessary to carry out gas-liquid separation. A new type of axial flow gas-liquid separator was proposed in this paper. The numerical simulation was carried out by CFD FLUENT software, and the changes of concentration field, velocity field and pressure field in the axial flow gas-liquid separator were analyzed. It was found that there were gas-liquid separation developments and stabilization segments in the inner cylinder of the separator. The axial velocity will form a zero-speed envelope in the inner cylinder, and the direction of the velocity in front of and behind the zero-speed envelope was opposite. The tangential velocity showed a “W” shape distribution in the radial position of the inner cylinder. The pressure on the left wall of the guide vane was higher than that on the r... [more]

The conveyor electric pump for deep-sea mining is a key piece of equipment in deep-sea mineral transportation systems, as its flow capacity and wear resistance affect the reliability of the entire system. In this study, aimed at solving problems such as mining pumps being prone to clogging and wear, which could lead to performance degradation, a mining pump with wide flow paths and high performance was designed, and hydraulic performance tests were conducted on the new pump. The test results obtained were in good agreement with the numerical simulation results. Based on the reliability of the performance test results, using computational fluid dynamics (CFD) methods, and taking the wear model into consideration, a wear analysis was conducted on the internal through-passage components of the pump under different solid-phase particle parameters and operating conditions, and the average wear rate on the surface of the predominant through-passage components was calculated. The results show... [more]

Contamination of toxic and odorous gases emitted from stacks in buildings located in an urban environment are potential health hazards to citizens. A simulation using the computational fluid dynamic technique may provide detailed data on the flammable region and spatial dispersion of released gases. Concentrations or emissions associated with garage sources and garage-to-house migration rates are needed to estimate potential exposures and risk levels. Therefore, the aim of the study was to use an original mathematical model to predict the most accurate locations for LPG sensors in an underground garage for vehicles powered with LPG. First, the three-dimensional geometry of an underground garage under a multi-family building was reconstructed. Next, two types of ventilation, jet and duct, were considered, and different sources of LPG leakage were assumed. Then, the Ansys Fluent software was applied as a solver, and the same initial value of released LPG (5 kg) was assumed. As a simplifi... [more]

The process of aeolian sand transport is an important mechanism leading to the formation and evolution of local landforms in coastal areas and desert lakes. For a long time, the role of surface moisture in incipient motion of sand grains by wind stress has been extensively studied but, in fact, sand-bed collision is the main mechanism in steady aeolian sand flow. At present, the lack of understanding of surface moisture content on sand-bed collision limits the application of aeolian sand transport models in wet coastal areas. In this paper, we adopt numerical simulations to discuss and analyze the effect of cohesive forces formed by surface moisture content on the sand-bed collision process based on discrete element method. High density contact forces appear with the surface moisture increasing, and form a closed structure around the edge of crater to resist the avulsion in horizontal direction. Under high moisture condition, even though the ejected sand grains saltate away from the su... [more]

This paper concerns the dynamical modeling of the microbiological processes that occur in the biofilms that are formed on fine inert particles. Such biofilm forms e.g. in fluidized-bed bio-reactors, expanded bed biofilm reactors and biofilm air-lift suspension reactors. An approximate model that is based on the Laplace−Carson transform and a family of approximate models that are based on the concept of the pseudo-stationary substrate concentration profile in the biofilm were proposed. The applicability of the models to the microbiological processes was evaluated following Monod or Haldane kinetics in the conditions of dynamical biofilm growth. The use of approximate models significantly simplifies the computations compared to the exact one. Moreover, the stiffness that was present in the exact model, which was solved numerically by the method of lines, was eliminated. Good accuracy was obtained even for large internal mass transfer resistances in the biofilm. It was shown that signific... [more]

This article presents the most valuable and applicable open-source tools and communication technologies that may be employed to create models of production processes by applying the concept of Digital Twins. In recent years, many open-source technologies, including tools and protocols, have been developed to create virtual models of production systems. The authors present the evolution and role of the Digital Twin concept as one of the key technologies for implementing the Industry 4.0 paradigm in automation and control. Based on the presented structured review of valuable open-source software dedicated to various phases and tasks that should be realised while creating the whole Digital Twin system, it was demonstrated that the available solutions cover all aspects. However, the dispersion, specialisation, and lack of integration cause this software to usually not be the first choice to implement DT. Therefore, to successfully create full-fledged models of Digital Twins by proceeding w... [more]

Chromium (Cr) and the emission of its compounds into the environment have caused long-term environmental contamination. In this study, the modes of occurrence of Cr in low-rank coal and their thermal stability in pyrolysis were investigated by sequential chemical extraction (SCE), single-component samples (SCS) pyrolysis, and thermochemical equilibrium simulation. The results showed that organic matter, aluminosilicate, and carbonate were the dominant modes of occurrence of Cr in low-rank coal. The modes of occurrence and chlorine (Cl) content affected the volatilization of Cr in coal. The characteristic release temperature range of Cr bounded to aluminosilicate was >600 °C and 400−600 °C for Cr bounded to a disulfide. Cr bounded to organic matter almost released completely before 600 °C. Cl enhanced the volatility of Cr and reduced its release temperature in Cr bounded to aluminosilicate. The simulation showed the content of gas products was very low, mainly chlorides. While the conte... [more]

Today, companies need to continuously improve their production processes, which is a complex task. Lean manufacturing is one of the methodologies for production improvement, and one of the basic goals of any lean implementation is to reduce work-in-process (WIP) and shorten the production lead time. One of the basic lean principles for achieving these goals is pull principle. The adoption of this principle is quite challenging, as it requires a long-term commitment in the application and adoption of various lean techniques and tools that are prerequisites for the successful introduction of the pull principle. Kanban is the most well-known pull production control mechanism, and the first one developed within Toyota production system, but later, other pull control mechanisms were developed. Some of them include Conwip, Hybrid Kanban/Conwip, and Drum Buffer Rope (DBR), and those three, together with Kanban, were the research topic of this study. These four mechanisms were not explored and... [more]

Automated storage and retrieval systems (AS/RS) play a key role in improving the performance of automated manufacturing systems, warehouses, and distribution centers. In the modern manufacturing industry, the term (AS/RS) refers to various methods under computer control for storing and retrieving loads automatically from defined storage locations. Using an (AS/RS) is not considered a value-added activity. Therefore, the longer (AS/RS) travels, the more expensive the warehousing process becomes. This paper presents an algorithm for minimizing total travel distance/time between input/output (I/O) stations. The proposed algorithm is used to manage the storage and retrieval orders on warehouse shelves in class-based storage on the storage racks. It contains two steps: the first step is to evacuate some storage compartments (locations) near the I/O station; in the second step, some tote bins are reallocated to compartments closer to the I/O station. Among the features of this algorithm are... [more]

Cyclone is often used in the Industry due to its low maintenance costs, simple design, and ease of operation. This work presents both experimental and simulation evaluation on the effect of inlet velocity and mass flow rate on the performance of a wheat conveying cyclone. According to the great importance of the pressure drop and separation efficiency on the separation phenomenon in the cyclone, a comprehensive study has been conducted in this regard. A computational fluid dynamics (CFD) simulation was realized using a Reynolds stress turbulence model, and particle-air interactions were modeled using a discrete phase model. The result showed a good agreement between the measured value and CFD simulation on the pressure drop and tangential velocity with a maximum deviation of 6.8%. It was found that the separation efficiency increased with inlet velocity up to 16 m s−1 but decreased slightly at a velocity of 20 m s−1. The pressure drop increased proportionally with inlet velocity. Howev... [more]

Knowing the effect of electromagnetic force on fluid flow and solidification within the molds of large-size round blooms is of paramount importance to minimize internal and external defects. In this regard, a three-dimensional coupling model is established, containing magnetohydrodynamics, fluid flow, and heat transfer within the mold, and a new approach for the uniformity of the initial shell is presented. Meanwhile, the effect of stirring parameters on fluid flow and solidification is discussed. The results show that M-EMS can significantly change the temperature and velocity distribution within the mold. These changes can stabilize the level fluctuations and make the initial shell uniform. The maximum industrial height fluctuation was reduced from 1.9 mm to 1.3 mm when the stirring intensity was 375 A/3 Hz. The stirring intensity of M-EMS is relatively ideal.

Supercritical water desalination (SCWD) shows great potential in the treatment of high-salt wastewater with zero liquid discharge. To investigate the salt precipitation behavior and mechanism in supercritical water, experiments and molecular dynamics simulations (MDs) were used to study the salting-out process of different salts in supercritical water. The equilibrium concentrations of NaCl, KCl, CaCl2, Na2SO4, and Na2CO3 in supercritical water were experimentally measured. When the temperature exceeded 693 K, the salt equilibrium concentration measured in the experiment was less than 130 mg/L. The solubility decreased in the order of KCl > NaCl > CaCl2 > Na2SO4 > Na2CO3. To elucidate the effects of different cations and anions in supercritical water on salt dissolution and precipitation behavior, the potential energy, radial distribution function (RDF) and coordination number in the system were obtained via molecular dynamics simulation. Experimental and MD results showed that salt so... [more]

This study evaluates low-temperature district heating (LTDH) networks with different geothermal heat sources under thermo-economic criteria. In particular, the heat and cold supply of modern neighbourhoods are taken into account in a dynamic simulation model built on the modelling language Modelica. Both horizontal and vertical ground heat exchangers (GHE) were investigated in respect to the load profiles of the consumers, depending on dimension as well as location. The selected base case represents a LTDH network near Stuttgart (Germany). The corresponding results of an annual simulation show that a horizontal GHE is suitable for pure heat supply and can reduce costs by up to 12% compared to a vertical system. This economic advantage remains when the cooling demand is considered. Subsequently, a variation of the system location was carried out. It is shown that horizontal GHEs operate more economically in northern regions, whereas vertical ones are more advantageous in regions with in... [more]

This research investigated the ability of two materials, which are waste generated during water treatment and wastewater treatment, to remove phosphates from water. The selected materials were quartz sand used in drinking water treatment plants (OQS) and incinerated (600 °C) sewage sludge (ISS). The materials were chosen for their composition: both contain aluminium, iron, and calcium. The experiments were carried out in the laboratory (in batch and in columns stand). Modelling of the sorption processes was performed on the basis of results from experiments in batches. The maximum adsorption capacity of the OQS was 1.14 mg/g obtained using the linearized Langmuir model and the maximum adsorption capacity of the ISS was 0.86 mg/g for the linearized Langmuir model (in batch). A pseudo-first-order model obtained using a nonlinear fit can accurately explain phosphate adsorption kinetics using both adsorbents: OQS and ISS. During the column filtration experiment, a higher sorption capacity... [more]

In this study, entropy generation theory based on computational fluid dynamics (CFD) is used to study the influence of a pumping chamber type (guide vane and volute scheme) on the spatial distribution of hydraulic loss in a mixed-flow pump. The CFD data of the mixed-flow pump with a volute is validated by external characteristic test data under Q = 561.4−1598.6 m3/h. The results show that the efficiency and the head of the guide vanes scheme are lower under Q = 800−1200 m3/h, which resulted from a higher total entropy production (TEP) in the pumping chamber and outlet pipe. The high total entropy production rate (TEPR) inside the guide vanes can be found near the leading edge of the hub side and trailing edge of the rim side due to flow separation, which reduces the recovery efficiency of kinetic energy of the guide vanes. The high TEPR inside outlet pipe can be seen near the inlet, caused by back flow. However, the efficiency and head of the volute scheme are lower, under Q = 1200−160... [more]

Deterministic lateral displacement (DLD) microsystems are suitable for the size fractionation of particle suspensions in the size range of 0.1 to 10 µm. To be able to fractionate real particles beyond a laboratory scale, these systems have to be designed for higher throughputs. High flow resistances and increasing the clogging of the systems impose substantial challenges for industrial operation. Simulative parameter studies are suitable for improving the design of the systems; for example, the position and shape of the posts. A high-resolution, two-way coupled 6-DOF CFD-DEM approach was used to study the flow and particle behavior of different post shapes (circular and triangular) and post sizes at different Reynolds numbers. The results were compared with the classical first streamline width theory. It was shown that the streamline theory does not account for all effects responsible for the separation. Furthermore, a shift in the critical particle diameter to smaller values could be... [more]

Smart production systems conforming the Industry 4.0 vision are based on subsystems that are integrated in a way that supports high flexibility and re-configurability. Specific components and devices, such as industrial and mobile robots or transport systems, now pose full-blown systems, and the entire Industry 4.0 production system constitutes a system-of-systems. Testing, fine-tuning, and production planning are important tasks in the entire engineering production system life-cycle. All these steps can be significantly supported and improved by digital twins, which are digitalized replicas of physical systems that are synchronized with the real systems at runtime. However, the design and implementation of digital twins for such integrated, yet partly stand-alone, industrial sub-systems can represent challenging and significantly time-consuming engineering tasks. In this article, the problem of the digital twin design for discrete-event production systems is addressed. The article als... [more]

A screw reactor is a promising apparatus for decontaminating radioactive graphite waste by uniform gasification under ambient air. However, developing the design equation for a screw reactor is difficult due to the reactor’s fundamentally intricate gas and solid interactions. In this study, we performed three-dimensional computational fluid dynamics simulations to predict and characterize the graphite particles that flow through the screw reactor and are thermally gasified. This was done using the Eulerian single-fluid approach coupled with the experimentally established kinetic model for graphite gasification. The numerical results show that the counter-rotating flow, generated along the rotating screw of the reactor by the relative motion of the reactor wall to the rotating screw, mixes particles spatially and reduces their axial velocity. The diameter of the feed graphite particles can be reduced by as much as 28% depending on the screw rotating velocity and the temperature of the r... [more]

Person tracking in hazardous goods factories can provide a significant improvement in security and safety. This article proposes a face verification model which can be used to record travel paths for staff or related persons in the factory. As face images are captured from the dynamic crowd at entrance−exit gates of workshops, face verification is challenged by polymorphic faces, poor illumination and changing of a person’s pose. To adapt to this situation, a new face verification model is proposed, which is composed of two advanced deep learning neural network models. Firstly, MTCNN (Multi-Task Cascaded Convolutional Neural Network) is used to construct a face detector. Based on the SphereFace-20 network model, we have reconstructed a convolutional network architecture with the embedded Batch Normalization elements and the optimized network parameters. The new model, which is called the MDCNN, is used to extract efficient face features. A set of specific processing algorithms is used... [more]

Recently, global energy consumption has increased due to industrial development, resulting in increasing demand for various energy sources. Aside from the increased demand for renewable energy resources, the demand for fossil fuels is also on the rise. Accordingly, the demand for resource development in the deep sea is also increasing. Various systems are required to efficiently develop resources in the deep sea. A study on an in-line type oil−water separator is needed to compensate for the disadvantages of a gravity separator that separates traditional water and oil. In this paper, the separation performance of the axial-flow oil−water separator for five design variables (conical diameter, conical length, number of vanes, angle of vane, and thickness of vane) was analyzed. Numerical calculations for multiphase fluid were performed using the mixture model, one of the Euler−Euler approaches. Additionally, the Reynolds stress model was used to describe the swirling flow. As a result, it... [more]