Results Of Numerical Modeling Research Articles

Longitudinal and lateral circulation and tidal impacts in salt-plug estuaries

This study presents a comparison of forcings between density gradient and tides in idealized funnel-shaped salt-plug estuaries. Three-dimensional numerical model results also examine longitudinal and lateral circulations. In salt-plug estuaries, a positive longitudinal estuarine circulation is observed landward of a salinity maximum zone or salt plug. Seaward of the salt plug, the estuary shows an inverse circulation cell. The longitudinal flows show a fortnightly variability inside the salt plug. Also, the salt plug is saltier in spring tides than in neap tidal cycles mainly owing to higher landward salt transport by tidal advection during the spring tides. The lateral circulation and divergence dv/dy have the influence of Coriolis acceleration. In the absence of Earth’s rotation, the tidally averaged lateral circulations have nearly the same directions within the positive and inverse cells. Directions of lateral flow reverse in the salt-plug area. Inside this area, the lateral circulation also shows clear neap–spring variability, including downwelling cells during spring tides and upwelling in neap tides. The salinity maximum zone exhibits a vertically homogeneous condition particularly in meso-tidal salt-plug estuaries. Finally, this study introduces the threshold of “log(tidal Froude number)=3” (tidal forcing 3 orders of magnitude ≥ density gradients) for salt-plug estuaries as the condition under which the tidal forcing can overcome the density gradient, and consequently salinity inside the salt plug zone is reinforced by tides with a landward movement. This robust salinity maximum zone is also identified by a high Ekman number (log(Ekman number)>0.25).

COMPARISON OF RESULTS OF NUMERICAL ANALYSIS OF SIMULATION OF CYBERPHYSICAL BIOSENSOR SYSTEMS

The article compares the results of numerical modeling of mathematical models of cyber-physical biosensor systems using lattice difference equations with time delay on hexagonal and rectangular lattices. The main attention is paid to the mathematical description of the dynamics of a discrete population in combination with the dynamic logic of the studied models. Lattice difference equations with delay are proposed for modeling the antigen-antibody interaction in hexagonal and rectangular biopixels. Similar to the diffusion phenomenon, spatial operators are considered to model the interaction between biopixels. The paper compares the results of numerical modeling of processes occurring in biopixels of cyberphysical biosensor systems in the form of phase plane images and lattice images of the probability of antigen-antibody bonds. Based on the obtained experimental results, a comparative analysis of the stability of mathematical models was carried out using lattice difference equations on hexagonal and rectangular lattices for cyberphysical biosensors.

Modeling the Crack Interference in X80 Oil and Gas Pipeline Weld.

Based on the numerical simulation method of the virtual crack closure technique (VCCT), an interference model was established to investigate the physical problem of two interacting cracks of different sizes in the welding zone of oil and gas pipelines. The obtained results of the current interference problem were compared with those of single crack case. Various crack configurations, such as different crack spacing and different crack sizes, were analyzed. The characteristic quantity fluid pressure load P during the crack propagation process, the peak value of the von Mises stress distribution field of the crack growth path, as well as the difference ∆Bx between the peak value of the magnetic induction intensity component at the crack and the value of the magnetic induction intensity component at its symmetrical position were calculated. The crack interaction scale factors, including γP, γMises, and γΔBx, were compared and analyzed. The numerical modeling results show that when the unequal-length double cracks interfere with each other, the cracks are more likely to propagate toward each other. The tendency of the double-cracks to propagate toward each other gradually weakens as the distance between the crack tips increases and is finally the same as that of single-crack cases. It was also found that the effect of large-sized cracks on small-sized cracks is greater than that of small-sized ones on large-sized ones. The numerical modeling results could be applied for the prediction and analysis of multicrack damage in oil and gas pipeline welds.

The Seismic Vulnerability Assessment of Heritage Buildings: A Holistic Methodology for Masonry Churches

ABSTRACT The seismic vulnerability assessment of monumental buildings is a complex task. Several uncertainties mine the reliability of evaluations. Within historical buildings, churches appear as particularly vulnerable objects, prone to instabilities and collapse when undergoing seismic loads. Global and local collapse mechanisms related to in plane and out-of-plane response of walls, respectively, are commonly observed in existing masonry buildings subjected to a seismic event. The main cause is the lack of strong connections among orthogonal walls and between walls and floors, which does not allow a global box-type behaviour of the building. This paper shows an approach to evaluate the vulnerability of churches based on a three-step analysis with increasing detail. The first step is a large-scale analysis to be applied to sets of churches, based on a simplified form comparing 28 mechanisms that can be activated by seismic events. The second step is referred to the evaluation of single churches and related, based on a kinematic approach, to the possibility to have out-of-plane mechanisms. The third step is based on the results of numerical models. It is useful to evaluate the behaviour in detail of some macroelements and to validate the obtained results in the first two steps.

Influence of random parameter joint length on rock electrical conductivity

Rock joint hollowness coefficient is an important parameter when resolving practical mining problems. Geophysical methods used to resolve this problem are indirect. Thus the interpretation of their results may cause certain difficulties as a result of the uncertainty of the physical relationships between the parameters of joints and the measurement results. One of the ways to resolve this problem is to combine experimental research methods with analytical and numerical simulation. The studies were aimed at investigating the electrical conductivity of a two-dimensional medium in the presence of thin insulating (non-conducting) joints. This paper proposes an analytical method for assessing the dependence of the specific conductivity of a medium with inclusions in the form of elliptical joints on their half-length. This dependence is show to have the form of an exponent depending on the square of the length of the maximum semi-axis as an argument. The simulation method is based on the assumption of the elliptical shape of a joint when the length of the minor semi-axis of the ellipses tends to zero. A review of publications and their results presented in this paper showed that this method for determining the specific conductivity of the medium with thin joints is one of the best in terms of compliance with experimental data. Its predictions are close to those of the Effective Media Approximation (EMA). However, the proposed method is distinguished by the simplicity of the formulas and their physical visibility essential for the use in interpreting the data of a physical experiment. In two-dimensional formulation, numerical simulation of the specific electrical conductivity of a sample of a medium measuring 1×1 m with elliptical joints of conductivity less than that of the matrix was carried out in the COMSOL Multiphysics environment. A square sample of unit sizes with unit conductivity was considered in which 25 joints with uniform distribution along the length occurred. 40 models were built wherein the maximum length of the joints varied from 0.01 to 0.4 sample size in increments of 0.01 m. The satisfactory concordance of the results of numerical and analytical models, both visual and confirmed by statistical estimates, has been shown. It was noted that when the size of the joints changes to achieve the value of the maximum semi-axis α = 0.15 m, the influence of single joints that do not extend beyond the boundaries of the sample prevails. Above this value, at α > of 0.15 m, the influence of joint coalescence, as well as their extension to and beyond the sample boundaries begins to affect. Comparison of the proposed theoretical model of electrical conductivity, depending on the square of the length of the maximum semi-axis of a joint, with a similar model in the form of an exponent with a linear dependence showed a better concordance of the proposed model with observations at the stage of the lack of joint coalescence and their extension to the sample boundaries at α < 0.15 m. At α > 0.15 m. The proposed model has a lower coefficient of determination compared to the full range including both intervals, but higher than that of the model with a linear dependence in the exponent argument. This indicates the universal nature of the proposed model.

Studying the Plastic Deformation of Cu-Ti-C-B Composites in a Favorable Stress State.

Composites with a copper matrix attract the attention of researchers due to their ability to combine high ductility, heat conductivity, and electrical conductivity of the matrix with the high hardness and strength of the reinforcing phases. In this paper, we present the results of studying the effect of thermal deformation processing of a Сu-Ti-C-B composite produced by self-propagating high-temperature synthesis (SHS) on its ability to deform plastically without failure. The composite consists of a copper matrix and reinforced particles of titanium carbide TiC (sized up to 1.0 μm) and titanium diboride TiB2 (sized up to 3.0 μm). The composite hardness is 60 HRC. Under uniaxial compression, the composite starts to deform plastically at a temperature of 700 °C and a pressure of 100 MPa. Temperatures ranging between 765 and 800 °C and an initial pressure of 150 MPa prove to be the most effective condition for composite deformation. These conditions enabled a true strain of 0.36 to be obtained without composite failure. Under higher strain, surface cracks appeared on the specimen surface. The EBSD analysis shows that dynamic recrystallization prevails at a deformation temperature of at least 765 °C; therefore, the composite can plastically deform. To increase the deformability of the composite, it is proposed to perform deformation under conditions of a favorable stress state. Based on the results of numerical modeling by the finite element method, the critical diameter of the steel shell is determined, which is sufficient for deformation of the composite with the most uniform distribution of the stress coefficient k. Composite deformation in a steel shell under a pressure of 150 MPa, at 800 °C, is experimentally implemented until a true strain of 0.53 is reached.

Arsenic removal by highly efficient MnFe2O4/TiO2/g-C3N4 and MnFe2O4/TiO2/GO adsorbents from a groundwater sample, Bardsir, Iran

In this study, MnFe2O4/TiO2/GO and MnFe2O4/TiO2/g-C3N4 spinel ferrites nanoparticles were used, and synthesized via the co-precipitation method, for the removal of arsenic from groundwater in the Bardsir region, Iran. The magnetic adsorbents were characterized by XRD, VSM, BET, FE-SEM, EDS, RAMAN, and FTIR analyses. The effects of pH, adsorbent dosage, contact time, initial arsenic concentration, and temperature on the adsorption process were investigated. MnFe2O4/TiO2/GO and MnFe2O4/TiO2/g-C3N4 were utilized to minimize the concentration of arsenic. The arsenic concentration was reduced from the initial amount of 17.8 mg/l to 197 µg/l and 177 µg/l using MnFe2O4/TiO2/GO and MnFe2O4/TiO2/g-C3N4, which indicates the adsorption capacity of 331 (mg/g) and 332 (mg/g), and the removal efficiency of 98.89% and 99.01%, respectively. Moreover, the adsorption rate for MnFe2O4/TiO2/GO and MnFe2O4/TiO2/g-C3N4 was very fast and occurred in 5 (min) and 15 (min), respectively. The results of kinetics studies were well correlated with the pseudo-second-order model, with the coefficient of determination values of 1 for both adsorbents. These nanoparticles could remove arsenic by following the Freundlich isotherm model. The thermodynamics studies showed that arsenic adsorption was an exothermic and spontaneous process. This article also presents a numerical simulation containing the second-order kinetic expression using COMSOL Multiphysics software. The experimental data and the numerical modeling results were in solid agreement. Furthermore, after five adsorption–desorption cycles, the adsorption capacity of the adsorbents remained constant as in the first cycle. Overall, a simple synthesis method, high adsorption capacity, fast kinetics, easy magnetic separation, and reusability demonstrate that MnFe2O4/TiO2/GO and MnFe2O4/TiO2/g-C3N4 are high-performance adsorbents for arsenic removal from aqueous systems.

On the Springback and Load in Three-Point Air Bending of the AW-2024 Aluminium Alloy Sheet with AW-1050A Aluminium Cladding.

This article presents the results of an analysis of the bending load characteristics and the springback phenomenon occurring during three-point bending of 1.0 and 2.0 mm thick AW-2024 aluminium alloy sheets with rolled AW-1050A cladding. A new proprietary equation was proposed for determining the bending angle as a function of deflection, which takes into account the influence of the tool radius and the sheet thickness. The experimentally determined springback and bending load characteristics were compared with the results of numerical modelling using different models: Model I, a 2D model for a plane deformation state, disregarding the material properties of the clad layers; Model II, a 2D model for a plane deformation state, taking into account the material properties of the cladding layers; Model III, a 3D shell model with the Huber-von Mises isotropic plasticity condition; Model IV, a 3D shell model with the Hill anisotropic plasticity condition; and Model V, a 3D shell model with the Barlat anisotropic plasticity condition. The effectiveness of these five tested FEM models in predicting the bending load and springback characteristics was demonstrated. Model II was the most effective in predicting bending load, while Model III was the most effective in predicting the amount of springback after bending.

Important effects of polypropylene on migration of ciprofloxacin in groundwater

To investigate the effect of microplastics on the transport and retention of antibiotics in subsurface environment, polypropylene (PP) and ciprofloxacin (CIP) are selected as typical microplastic and antibiotic contaminant, respectively. The key factors and main control mechanisms are systematically investigated using a combination of adsorption experiments, column experiments and numerical model. The adsorption experiments indicate the largest adsorption capacity of CIP on PP is 1.03 mg·g−1. Simultaneously, the results of column experiments and numerical model suggest that PP can significantly affect the migration behavior and retention of CIP in porous media. CIP mobility is positively correlated to flow velocity, initial concentration of CIP and ionic strength (Na+, Ca2+ and Ba2+). Moreover, compared to monovalent cation (Na+), divalent cations (Ca2+, Ba2+) have a stronger enhancement effect on CIP mobility and a stronger inhibition effect on CIP retention in saturated porous media. The transport of CIP in saturated porous media containing PP is simulated by a single-point kinetic model, and the equations of the transport kinetic parameters of CIP are obtained through regression analysis. The research could help to gain insight into understanding the environmental behavior of antibiotic in the groundwater system, and provide scientific basis for the accurate prediction and assessment of environmental risk caused by microplastic and antibiotic in the groundwater system.

Ultrawideband Compact Lightweight Biconical Antenna With Capability of Various Polarizations Reception for Modern UAV Applications

This article presents the results of numerical modeling, optimization, fabrication and performance measurements of a new biconical antenna for modern unmanned aerial vehicle (UAV) applications. The developed antenna effectively combines a set of fundamental constructive and electromagnetic requirements, which include compact structure and small total dimensions, lightweight, and ultrawideband operating frequency range with the capability of receiving or transmitting both circular, horizontal, vertical, and one of slant linear polarizations. For the first time, an effect of multiple resonance reflections in the structure of biconical antenna with a polarizer and deterioration of antenna’s matching and gain characteristics at a series of frequencies was detected by measurements. Theoretical analysis of the observed resonances has been carried out in this article. Possible ways to exclude resonances are given. In the most part of operating frequency range 2–18 GHz, the developed antenna provides voltage standing wave ratio (VSWR) less than 2 and gain higher than 3 dBi for the -45° slant polarization, while the +45° slant polarization is discriminated by more than 15 dB.

High resolution acoustic tomography based on backpropagation of waves

A method of high-resolution acoustic tomography of scattering inhomogeneities based on the method of reverse time migration is proposed. An inhomogeneous background medium with a known distribution of refractive inhomogeneities is considered, where it is necessary to detect scattering inhomogeneities. Probing is carried out by broadband arbitrary waveforms. The method of reverse time migration is supplemented with linear filtering of the direct propagation field, which makes it possible to increase the resolution of reconstructed images. The results of numerical modeling and experiment are presented. Sounding was carried out in water at frequencies from 20 to 350 kHz using a signal with linear frequency modulation. The source of the ultrasonic signal was fixed and irradiated the objects under study in the water. The scattered signal was measured in a plane near the surface in water on a rectangular area with a step of less than 2 mm. Signal processing by the proposed method made it possible to reconstruct a three-dimensional image of scattering inhomogeneities with a resolution of about 7 mm. Comparison of the proposed method and the reverse time migration method showed that the proposed method allows obtaining a higher resolution.

Vortex Counting and Velocimetry for Slitted Superconducting Thin Strips

The maximal speed $v^\ast$ for magnetic flux quanta is determined by the energy relaxation of unpaired electrons and is thus essential for superconducting microstrip single-photon detectors (SMSPDs). However, the deduction of $v^\ast$ from the current-voltage ($I$-$V$) curves at zero magnetic field is hindered by the unknown number of vortices, $n_\mathrm{v}$, as a small number of fast-moving vortices can induce the same voltage as a large number of slow-moving ones. Here, we introduce an approach for the quantitative determination of $n_\mathrm{v}$ and $v^\ast$. The idea is based on the Aslamazov and Larkin prediction of kinks in the $I$-$V$ curves of wide and short superconducting constrictions when the number of fluxons crossing the constriction is increased by one. We realize such conditions in wide MoSi thin strips with slits milled by a focused ion beam and reveal quantum effects in a macroscopic system. By observing kinks in the $I$-$V$ curves with increase of the transport current, we evidence a crossover from a single- to multi-fluxon dynamics and deduce $v^\ast\simeq12\,$km/s. Our experimental observations are augmented with numerical modeling results which reveal a transition from a vortex chain over a vortex jet to a vortex river with increase of $n_\mathrm{v}$ and the vortex velocity. Our findings are essential for the development of 1D and 2D few-fluxon devices and provide a demanded approach for the deduction of $v^\ast$ at the SMSPD operation conditions.

Augmented digital twin for railway systems

The information that automated train control (ATO) systems use to improve safety and reduce power usage is limited by on-board and wayside monitoring applications and computing power. This paper presents an augmented digital twin for railway applications that enables real-time consideration of derailment risk in train operations. The augmented digital twin implements a surrogate model with the results of a massive multibody dynamics numerical program and machine learning models to predict the instantaneous wagon derailment risk. A case study for a heavy haul iron ore wagon with three-piece bogies was conducted to test the augmented digital twin. A multibody simulation numerical program comprising 2100 simulation cases was completed. The surrogate model was developed using linear, polynomial, decision tree and ensemble forest regression models on the results of the numerical program. A longitudinal train simulator was used to calculate the speed and lateral coupler force throughout a train trip. The surrogate model effectively predicted the derailment index for empty and loaded conditions accounting for lateral coupler forces, vehicle speeds and curve radius. The proposed augmented digital twin can be further developed to accomplish other train operational benefits such as the reduction of rail damage.

Determination of the rock mass displacement zone by numerical modeling method when exploiting the longwall at the Nui Beo Coal Mine, Vietnam

Purpose. It is important to conduct a study to identify the displacement zone caused by mining operations. By numerical modeling the process of mining the longwall 31104 in Seam 11 at the Nui Beo Coal Mine, Vietnam, the authors have deter-mined the total height of the rock mass displacement zone and the boundary of the affected area on the topographic surface. Methods. In this study, the authors use a numerical modeling method. The models are developed based on the UDEC (Universal Distinct Element Code) software. In addition, field survey methods and statistical analysis methods are used. Findings. Based on the analysis of the numerical modeling results, it has been determined that the total height of the displacement zone, when exploiting the longwall 31104 in Seam 11, is about 63 m. The analysis of the numerical modeling results also shows that the roof collapse angle is 52°, which determines the area of influence on the topographic surface in the range of 160 m. Originality. Based on the UDEC software, the authors have developed a simulation model for the mining process of the longwall 31104 in Seam 11. Analysis of the model results has shown the state of the displacement zone of the surrounding rock mass. In this study, the numerical modeling method is applied to simulate the longwall displacement zone, which is consistent with the actual production of the underground mine. Practical implications. Based on the analysis of the surrounding rock mass displacements zone, when exploiting the longwall 31104 in Seam 11 at the Nui Beo Coal Mine, the affected boundary on the topographic surface has been determined. At the same time, the height of the rock mass displacement zone has also been calculated. Thus, the research results can be used as a basis for implementation in actual production at the Nui Beo Coal Mine.

Prediction of shear strength for CFRP reinforced concrete beams without stirrups

Design guidelines in international codes show noticeable differences with regards to shear strength prediction of concrete beams reinforced with Fiber Reinforced Polymers, (FRP). These discrepancies in shear strength predictions are attributed to many factors affecting the shear behavior, such as shear span/depth ratio (a/d), beam size, rectangular and flanged cross-sectional shape (R-section and T-section), and concrete compressive strength. Shear resistance of beams longitudinally reinforced with carbon FRP, (CFRP), bars is not well defined in the literature compared to beams reinforced with steel bars. This is mainly attributed to the low modulus of elasticity of CFRP compared to traditional steel reinforcement resulting in relatively high strains generated in CFRP reinforcement and consequently wider cracks and lower contribution of the aggregate interlocking mechanism as well as dowel action in shear resistance. This paper numerically investigates the behavior of concrete beams reinforced in flexure with CFRP bars without transverse reinforcement to quantify concrete contribution in shear resistance. Specimens with R and T sections having different shear span-to-depth ratio, concrete compressive strength, and longitudinal CFRP reinforcement ratios are studied to determine the concrete contribution to shear resistance. The nonlinear program ATENA is used to simulate the actual behavior of concrete beams failing in shear and is verified against experimental results gathered from the literature to check the validity of the numerical model. The comparison shows good agreement between experimental and numerical results with a difference of 6% and then a parametric study is conducted to provide a better understanding of the effect of each parameter on the shear behavior of concrete beams reinforced with CFRP bars. The results of numerical models are compared to their counterparts predicted using different equations in codes and guidelines. It is found that the shear capacity of T-section is higher than R-section by about 15% to 25% mainly due to a change in cracking pattern due to the presence of the flange. Furthermore, the shear failure load increased by increasing the longitudinal reinforcement ratio as a result of decreasing strain and enhancement of dowel action. The effect of increasing concrete compressive strength was more pronounced on the shear capacity in arch action as opposed to diagonal tension regions. Finally, an equation is proposed to predict the shear capacity of concrete beams reinforced in flexure with CFRP bars. The shear capacity predicted by the proposed equation provided a good agreement with experimental results for 163 beams with a mean value of 1.01 and COV of 0.17.

Evaluation of welding-induced residual stress and distortion in A-TIG welding of duplex stainless steel

Applying non-uniform heat in welding causes residual stress and distortion, which affects the life of components. In the present study, the residual stress and distortion of Duplex 2205 stainless steel in A-TIG welding were investigated numerically and experimentally. The optimal welding parameters for highest penetration depth in welded samples were obtained experimentally. Uncoupled thermal-mechanical analysis using ABAQUS 2017 software has been done. Goldak's parameters were measured by empirical tests. The results include simulation diagrams of four samples consisting of the optimal sample without flux powder and three samples with the highest penetration depth. The simulation results show that the sample without flux has a higher maximum temperature and lower welding-induced distortions. The efficiency used in this research changes using and not using powder; it is concluded that, in similar conditions in A-TIG welding, fewer values of parameters are needed to achieve the appropriate result comparing conventional TIG. The efficiency of workpieces with flux should be considered about 20% lower to have similar results to the conventional TIG. The numerical modeling results showed a good agreement with experimental data both for temperature distribution and welding-induced residual stress and distortion. The distortion in the pieces with conventional TIG welding has increased to 11% at the farthest point from the welding line. The error obtained from comparing the results in residual stress is between 12 and 34%.

Pump Excited-State Absorption at 442 ± 1 nm for Efficient Visible Fluoride Fiber Lasers

In the well-known excited-state absorption (ESA) process, population inversion of the laser transition can be achieved by a strong pump ESA involving a lower laser level. The exploitation of pump ESA has expanded from the visible to the near-infrared spectral range, based on various laser sources. Extending the operating wavelength of the pump ESA is greatly significant for the development of rare-earth-doped fluoride fiber lasers. Herein, we report, presumably, the shortest operating wavelength of pump ESA at 442 ± 1 nm for an efficient continuous-wave visible fluoride fiber laser. A novel scheme for direct blue diode pumping was proposed and demonstrated in an Ho <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped fluoride fiber. Utilizing a 442 ± 1 nm blue laser diode, single-wavelength ground-state absorption (GSA) and ESA pumping mechanism were investigated not only for double populating of the upper laser level by GSA and ESA, but also to depopulate the lower laser level by ESA. We report a slope efficiency of 50.3% with respect to the launched pump power of 442 ± 1 nm and an output power of up to 327 mW for a 750 nm fiber laser. This result is an order of magnitude higher than that previously reported for a directly blue-diode-pumped deep-red Ho <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -doped fluoride fiber laser. Moreover, the numerical modeling results were in good agreement with the experimental results. Our approach represents a significant advancement for blue pump ESA in visible fluoride fiber lasers, which opens new capabilities for blue-diode pumping for a wide range of future applications.

A simplified pneumatic model for air brake of passenger trains

Braking system performance is relevant for both railway safety and network optimization. Most trains employ air brake systems; air brake systems of freight trains mostly cannot achieve a synchronous application of brake forces, which is usually customary for passenger trains. The paper generalizes a previous air brake pneumatic model to passenger trains and describes the needed modifications. Among them, the way the pressure reduces in the brake pipe is generalized. Moreover, this paper reports an analytical bi-dimensional function for calculating the nozzle diameter equivalent to the electro-pneumatic (EP) or the electronically controlled pneumatic (ECP) brake valve as a function of the wagon length and the time to vent the brake pipe locally. The numerical results of the new model are compared against several experimental tests of high-speed passenger trains of Trenitalia, namely ETR500 and ETR1000. The model is suitable to be integrated into the UIC software TrainDy, aiming to extend its computational field to passenger trains and to simulate the safety of trains during a recovery.

Numerical Analysis of the Mathematical Model of a Cluster V2X-System

The article analyzes the results of numerical modeling of information processes in vehicular ad-hoc networks (VANETs). The review of works devoted to clustering and data caching schemes in Vehicle-to-Everything (V2X) systems is given. L1-metric was chosen as a metric because of its active use in cities with modern layout. Two approaches to the description and evaluation of the efficiency of interaction of boundary devices in a traditional configuration and using a cluster scheme with a shared cache are considered. A mathematical model is constructed and an analysis of its effectiveness is carried out. It is shown that the introduction of new IEEE 802.11bd standards will increase the percentage of serviced devices, thereby minimize the overall delay of computing, which will improve the efficiency of the V2X-system. The results of the study can be used in the design and deployment of automated traffic control systems in cities.

Mathematical Model and Numerical Method of Calculating the Dynamics of High-Temperature Drying of Milled Peat for the Production of Fuel Briquettes

Milled peat must be dried for the production of peat fuel briquettes. The current trend in the creation of drying technologies is the intensification of the dehydration process while obtaining a high-quality final product. An increase in the temperature of the drying agent, above 300 °C, significantly accelerates the reaching of the final moisture content of the peat. In the final stage, it is also accompanied by partial thermal decomposition of the solid phase. Its first stage, which is the decomposition of hemicellulose, contributes to a decrease in weight and an increase in the caloric content of the dry residue. The development of high-temperature drying modes consists of determining the temperature and velocity of the drying agent, wherein the duration of the material reaching the equilibrium moisture content will be minimal and the temperature of the material will not rise above the second-stage decomposition temperature of cellulose. This problem can be solved by the mathematical modeling of the dynamics of peat particles drying in the flow. The article presents a mathematical model of heat and mass transfer, phase transitions, and shrinkage during the dehydration of milled peat particles. The equations of the mathematical model were built based on the differential equation of mass transfer in open deformable systems, which, in the absence of deformations, turns into the known equation of state. A numerical method for implementing a mathematical model has been developed. The adequacy of the mathematical model is confirmed by comparing the results of numerical modeling with known experimental data.