Basis Of Simulations Research Articles

SuFEx‐based Transparent Polysulfates and their Applications in Tunable Resistant Electrical Memory Materials

AbstractVisibly transparent electron devices are current research highlights, which are found at the “neotype” stage of technical development for the usage in the next generation “see‐through” electronic devices. However, less attention is paid to transparent semiconductor memory devices, and hence, achieving such “see‐through” electronic devices are still partially limited by lacking the easily achievable and cost‐effective transparent memory materials. Herein, three visible light transparent polysulfate‐based memory devices are reported, e.g. ITO/P‐BPS/Al, ITO/P‐TPA/Al, and ITO/P‐TPABPS/Al, that displayed DRAM, WORM, and FLASH effects, respectively. The mechanisms of the observed memory behavior of each memory material are proposed on the basis of computational simulation. Remarkably, these polysulfates‐based memory materials are obtained by simply using different main‐chain repeating units, suggesting a wide application potential of polysulfate as functionalized materials.

Constructing the soliton wave structure to the nonlinear fractional Kairat-X dynamical equation under computational approach

In this paper, the nonlinear fractional Kairat-X equation is investigated on the basis of computational simulation. The nonlinear fractional Kairat-X equation is an integrable equation and is used to explain the differential geometry of curves and equivalence aspects. Several kinds of solitary wave structures of the nonlinear fractional Kairat-X equation are established successfully via the implantation of the extended simple equation method. Here, we explore the interesting, novel and general solutions in trigonometric, exponential, and rational types, which represent periodic wave solitons, mixed solitons in the shape of bright–dark solutions, kink wave solitons, peakon bright and dark solitons, anti-kink wave solutions, bright solitons, dark solitons, and solitary wave structure. The physical structures of secured results, aided by numerical simulation, have numerous applications in applied sciences such as optical fiber, geophysics, laser optics, mathematical physics, nonlinear optics, nonlinear dynamics, communication system, and engineering. This study explores the physical behavior of models through the visualization of solutions in contour, 2D and 3D plots by revealing that these solutions yield profitable results in the field of mathematical physics. The study demonstrates that the proposed technique is more reliable, efficient, and powerful in analyzing nonlinear evolution equations in various domains of science.

Evolution of cross-sectional shapes of liquid inclusions enclosed in a crystal: Computer simulation and its application for studying interface kinetics

The previously developed model of the cross-sectional stationary shape of a liquid inclusion migrating through a non-uniformly heated crystal has been extended to the case of transient processes caused by changes in the temperature gradient value and/or temperature oscillations. On the basis of computer simulations, the evolution of the cross-sectional shapes of the inclusions with 4 facets in their cross sections has been analyzed for the cases of different mechanisms of interfacial processes. A technique for estimating kinetic coefficients from the geometry of the inclusion shapes established after imposing and removing the temperature gradient has been proposed. The possibility of controlling the velocity and shape of the 4-faceted inclusions by means of temperature oscillations has been demonstrated and discussed.

Modeling of poly-β-hydroxybutyrate production by Bacillus subtilis and its use for feed-forward bioreactor studies.

Successful scale-up of Bacillus subtilis culture for poly-β-hydroxybutyrate (PHB) production was performed in 5-l stirred-tank reactor using batch, fed-batch, and two-stage culture strategies. The kinetics of biomass production, substrate consumption, and PHB production were established in the stirred tank bioreactor in all the studies. A mathematical model was developed to investigate the role of limiting substrate on overall culture metabolism. A fed-batch strategy was predicted on the basis of computer simulations, for maximum PHB production. This was performed by extrapolation of batch model for predicting the feeding rate and suitable time of feeding. Substrate inhibition was studied and the substrate inhibition terms were incorporated in the model. The maximum cell biomass concentration in batch culture (24h) and fed-batch culture (30h) was 1.79 ± 0.03g/l on dry cell weight (DCW) basis and 1.66 ± 0.050g/l on DCW basis and the corresponding PHB content was 68.71% and 85.54% of DCW, respectively. Glucose was found to be the major limiting nutrient during the bioreactor culture. A two-stage culture, where cells were first grown in stage I in LBG media containing excess carbon and thereafter in stage II in OM media, showed biomass production of 1.95 ± 0.045g/l at 4h and PHB production of 93.33% of DCW at 16h. A 9% increase in growth and 25% increase in PHB yield were obtained using two-stage culture with computer-simulated feeding strategy in the 5l reactor. Oxygen limitation was overcome in modified two-stage culture to obtain a PHB production of 98% at 30h. KEY POINTS: • Polyhydroxybutyrate production was studied in a 5-l stirred-tank bioreactor using HPLC • Mathematical model-assisted fed-batch strategy was implemented in bioreactor • Two-stage fed-batch cultivation was implemented and PHB production was 93% of dry weight in Gram-positive bacteria.

Numerical and Physical Study on New Simple Design of Subflux Flow Controller for One-Strand Tundish.

Tundish metallurgy is essential for continuous steel casting technology. In this study, the subflux flow controller (SFC) installed in the tundish pouring zone was tested, demonstrating the possibility of simultaneously reducing the dimensions of the flow control device (FCD) and effectively influencing the structure of the liquid steel flow. On the basis of computer simulations and water model trials, results were obtained describing the hydrodynamic structure in considered variants of the one strand slab tundish. Considering the influence of the SFC on the steel flow structure in the tundish, and the gradient of the wall shear stress and total pressure on the SFC surface/tundish walls, the most optimal SFC variant for a single-strand wedge-type tundish is SFC No. 2C.

Computer simulation of the reliability of the heat exchange surface of the steam turbine condenser

The aim of the article is to demonstrate the relationship between the adaptive regulation of the heat exchange surface to specific operating conditions of a steam turbine condenser and the reliability and availability of this surface in a specific period of time. The article exemplifies the relationship between the settings of the condenser heat exchange surface and the resulting changes in the reliability structures of this surface. The method of creating a mathematical model of reliability estimation, which is characterized by the variability of the reliability structures of the heat exchange surface in relation to specific operating conditions in a specific period of time, was indicated. Then, exemplary simulations of the adaptation of reliability structures of specific pipe systems constituting the condenser’s heat exchange surface to specific processes of operation of this condenser are presented. The simulations refer to the time-varying thermal loads of the condenser, the time-varying mean thickness of the sediments, and changes in the temperature of the cooling water at the point of its intake over time. The adaptation of certain reliability structures consists in the adaptation of specific systems of pipes through which the cooling water flows to the currently existing operating conditions of the condenser in order to maintain the desired reliability of the heat exchange surface for a specified time. This is done by enabling or disabling the flow of cooling water through a given number of pipes in specific systems under given operating conditions. On the basis of computer simulations, the reliability functions, and the availability functions of the subsystem under consideration were estimated.

Impact of simulation training for teamwork and communication intervention on patient safety in the emergency department

Background: The emergency department (ED) is the hospital division that is most vulnerable to poor communication and teamwork-based medical errors that affect patient safety. One approach to prevent medical errors is by training and assessing healthcare workers using simulation-based (SB) teamwork and communication training. This study aimed to explore the extent to which SB training could improve teamwork and communication and reduce preventable medical errors in the ED. Method: The study was conducted at the Ministry of National Guard Health Affairs, a tertiary care center with a 39-bed ED, in Saudi Arabia. A total of 123 ED healthcare staff participated in the study. This study adopted a single-subject experimental design with the intervention of simulation training in ED cases. The methodology focused on three domains: 1) patient safety in the ED, 2) inter-professional and multidisciplinary simulation team training, and 3) team dynamic enhancement use. Staff perceptions regarding teamwork and communication pre-and post-intervention and the relationship between changes in their perception of performance in the ED and patient outcomes. The chi-square test was used for univariate analysis, and a generalized linear regression model was adjusted for demographics in multivariate analysis. Results: Staff perceptions were collected from all multidisciplinary team members before and after simulation training. The data revealed a significant improvement in overall staff perceptions toward teamwork and communication (8% to 34%, p-value = 0.001). Conclusion: SB communication and teamwork training in the ED resulted in a sustained and measurable improvement in ED staff perceptions toward teamwork and communication. The results suggest that simulation sessions may improve staff perceptions and multidisciplinary team communication during critical situations in the ED.

Влияние высоты пластинчатых турбулизаторов потока на характеристики течения в микрофакельных горелочных устройствах

The use of flow turbulators in microflame burners is intended to intensify heat and mass transfer processes in the active combustion zone and, in general, to improve the energy and environmental performance of burners of this type. The available studies of various methods of intensifying combustion processes do not cover many issues related to the regularities of the influence of various factors on the characteristics of the working processes of microflame burners in the case of using one or another method of intensifying combustion. It is important to establish the dependence of these characteristics on various design parameters of the flow turbulators. The purpose of this study is to establish the patterns of influence on the flow characteristics of the height of the turbulizing plates located on the side surfaces of the flame stabilizers. The research was carried out on the basis of computer simulation using the FLUENT code. The results of the studies performed showed that with an increase in the height of the turbulizing plate from 0.005 to 0.01 m, there is a significant change in the flow pattern, which manifests itself in the lengthening of the circulation flow zones behind the flame stabilizer, in an increase in the maximum absolute value of the velocity in these zones, an increase in the level of velocity pulsations. and the size of the subregions in which these pulsations are significant, etc. Prospects for further research are related to the study of the considered situations in the conditions of reacting flows.

Complex use of smart grid technology in railway traction networks

The goal is to develop a methodology for modeling electric power supply systems for railways equipped with a complex of devices implemented using smart grid technologies. The results obtained showed that a reliable and high-quality electric power supply for traction of trains and non-traction consumers could be implemented on the basis of the integrated use of Smart Grid active elements, such as a phase converter, an active harmonic conditioner, a controlled reactive power source and a distributed generation plant. On the basis of computer simulation, it has been established that in the absence of reactive power sources, noticeable voltage fluctuations are observed on the 10 kV buses of a non-traction consumer. The asymmetry approaches the limit of normally permissible values; turning off the active filter leads to an increase in the total voltage harmonic distortion up to 16%; in the presence of the whole complex of active devices, high quality of electricity is achieved. The phase number converter is robust and has low sensitivity to parameter setting errors; voltage deviations caused by a limited range of changes in reactive power in its source are short-term and do not exceed values acceptable for practice. Thus, on the basis of Smart Grid technologies, it is possible to implement the connection of distributed generation plants directly to the traction network using a device for transducing the number of phases, formed according to the inverted Steinmetz’s circuit. Elimination of harmonic distortions created by rectifier electric locomotives is carried out by means of an active conditioner of higher harmonics. A controlled reactive power source can be used to maintain voltage levels.

DEVELOPMENT OF ENERGY EFFICIENT LIGHTING PROJECTS

The article is devoted to the development of an energy efficient lighting project for an administrative building, taking into account the new requirements for the energy efficiency of lighting installations. The project was developed on the basis of computer simulation using modern LED lamps. The analysis of the impact of current regulatory requirements in the field of energy efficiency of lighting in public premises on the change in the range of manufactured lighting devices based on LEDs in Russia is carried out.

Comprehensive study of the process of cutting screw grooves on the inner surface of a cylindrical steel sleeve with rotary cutting mandrels

The paper presents the results of a comprehensive study of the process of cutting helical internal grooves on the basis of computer simulation in order to establish the influence of technological parameters of cutting on the forming force. Researches of cutting of screw grooves on thinwalled steel sleeves by a cutting mandrel with various cutting speeds have been carried out. The method of processing internal screw grooves on machines with simple kinematics is presented. The dependences of the influence of cutting rates on implementation of the hidden kinematical connection are established. Graphs reflecting the dependence of the cutting rate on the angle of inclination of the cut helical groove are constructed, and a regression equation is obtained describing the dependence of the studied factors on the axial force. Ranges of cutting rates are established, allowing to provide the maximum productivity at various angles of the spiral inclination. The results of processing the experimental data of the study of the influence of tool geometrical parameters on the forming force when cutting helical grooves on the inner surface of the cylindrical shell are shown. Levels of change of factors, variance of experiment results on each of experiments are defined. The regression coefficients are calculated, the regression equation is compiled, the variance of model adequacy is estimated and adequacy of the regression equation is checked, the nature of infl uence of interaction of cutting rate parameters, front angle and the allowable allowance on the forming force is determined. Based on the results of modeling using the Maple program, a regression equation was obtained that reflects dependence of influence of factors on the axial force per tool tooth, dependence of the influence of the studied factors on the change in temperature in a cutting zone, and also constructed a temperature field reflecting the heat distribution in the processing zone on the example of one experiment. The study was performed with the financial support of the Russian Foundation for Basic Research within the research project No. 19-38-90057.

ДИНАМІЧНА РЕАКЦІЯ ТА СТІЙКІСТЬ ПОШКОДЖЕНОЇ КОНСТРУКЦІЇ ТРАНСПОРТНОГО ЛІТАКА

In the process of designing and operating the aircraft, it is important to determine the ultimate state of the structure, taking into account the dynamic load of the structure and its stability. The ultimate state of the structure is characterized by damage, in which the structure still retains the ability to withstand without catastrophic destruction of the maximum operating load. The main method of studying the stability of the structure is the dynamic method. It allows us to investigate the perturbed motion of a structure as a nonconservative system for some initial perturbation. The monotonic departure of the system from the equilibrium position or its oscillations with increasing amplitudes indicate the instability of the structure. The paper analyzes the effect of damage to the aircraft structure on its dynamic stability based on the determination of the dynamic response of the aircraft to some non-stationary perturbation, for example, on the action of a turbulent atmosphere. The method of computational analysis is used to study the dynamic stability of the structure. The basis of this method is mathematical modeling (MM) of the operation of the aircraft in the form of a system of equations of motion and deformation of the structure. The problem of dynamic aeroelasticity is considered - the behavior of the elastic damaged structure of the aircraft in the air flow to the initial perturbation. On the basis of computer simulation, the dynamic stability of the elastic structure, its oscillating or quasi-static (aperiodic) deformation motion within the flight range of the aircraft is estimated. On the basis of parametric researches the limits of instability of a design at the set damages for typical operating conditions are estimated. The relevance of the direction focused on the creation and advanced operation of MM aircraft - their mathematical backups in the process of design and operation of aircraft due to the complexity and limited capabilities of ground experimental installations and flight experiment. It is noted that the condition for the application of this method is the formed MM operation of the aircraft and the availability of information on the mass-inertial, stiffness and aerodynamic characteristics of the aircraft.

Calculated studies for the braking efficiency of freight trains under the rules of gost 34434-2018 with the application of universal formulas (four-axle gondola cars, covered railraod cars, platforms, dump cars)

Absence of normative values of the actual coefficients in new rules of GOST 34434-2018 does not allow implementing and determining the optimal characteristics of the brake according to the previously adopted conditions of braking efficiency (braking distance), which causes uncertainty in solving this problem. The uncertainty lies in the fact that the choice of the characteristics of the brake system of a freight car has to be carried out by enumerating a large number of variations. In this respect, the article provides tools for determining the actual coefficient of the press force of composite brake blocks on  wheels, satisfying the given braking efficiency of the freight train. Universal formulas are used as tools in the form of power dependence between the actual coefficient of press force of brake blocks and the braking distance of a freight train. The coefficients of universal formulas are obtained on the basis of computer simulation. Numerous examples show that the error in the use of universal formulas in calculation studies does not exceed 0.5% compared to the calculated ones according to GOST 34434-2018 methodology. Values of actual coefficients are given depending on the axial load of the car and speed at which the braking distances of the freight train correspond to the standard minimum permissible values. It is shown that performance of the calculation studies using universal formulas in the EXCEL environment allows automate the calculation process in full. A technique is proposed for determining the gear ratio of the brake lever mechanism of a freight car, at which a given braking efficiency is performed. The proposed technique allows you to perform multivariate studies on the selection of optimal parameters of the brake system of freight cars that meet the specified requirements for braking efficiency, and greatly facilitates the calculation studies.

Analysis of the bioethanol production process control

The article presents the analysis of the automatic control of the bioethanol production process intended for biofuel. It presents the formulated general concept of the system and the method of designing a closed control system based on the iterative prototyping procedure. The modeling and the simulation were carried out in the Matlab®-Simulink environment. The simulation model of the object was developed based on the experimentally registered characteristics. It has been adjusted, i.e. the compatibility of its behavior with the object it reproduces has been confirmed. Based on the tuned model of the object, a control system model was created, which was the basis for computer simulation which enabled the control algorithm parameters to be established. The final verification of the correct operation of the system was performed with the use of hardware simulation. It was based on entering a negative feedback loop of the virtual control system of the real object elements into the loop. The results of the simulation confirmed the correctness of the adopted design.

Simulation of a gas-condensate mixture passing through a porous medium in depletion mode

One of important tasks in a development of gas-condensate fields is to minimize hydrocarbons loss arising from the gas condensation in pores of the gas-bearing layer. The search for the optimal gas production regime is carried out both on the basis of laboratory experiments and on the base of computer simulation. In this regard, the relevant is the verification of the constructed mathematical models by means of comparison of numerical results with experimental data obtained on the laboratory models of a hydrocarbon reservoirs. Within the classical approach on the basis of the Darcy law and the law continuity for flows, the model is formulated that describes the passing a multicomponent gas-condensate mixture through a porous medium in the depletion mode. The numerical solution of the corresponding system of nonlinear partial differential equations is implemented on the basis of the combined use of the C++ programming language and the Maple software. Shown that the approach used provides an agreement of results of numerical simulations with experimental data on the dynamics of hydrocarbon recoverability depending on the pressure obtained at VNIIGAZ, Ukhta.

Simulation of a gas-condensate mixture passing through a porous medium in depletion mode

One of important tasks in a development of gas-condensate fields is to minimize hydrocarbons loss arising from the gas condensation in pores of the gas-bearing layer. The search for the optimal gas production regime is carried out both on the basis of laboratory experiments and on the base of computer simulation. In this regard, the relevant is the verification of the constructed mathematical models by means of comparison of numerical results with experimental data obtained on the laboratory models of a hydrocarbon reservoirs. Within the classical approach on the basis of the Darcy law and the law continuity for flows, the model is formulated that describes the passing a multicomponent gas-condensate mixture through a porous medium in the depletion mode. The numerical solution of the corresponding system of nonlinear partial differential equations is implemented on the basis of the combined use of the C++ programming language and the Maple software. Shown that the approach used provides an agreement of results of numerical simulations with experimental data on the dynamics of hydrocarbon recoverability depending on the pressure obtained at VNIIGAZ, Ukhta.

Simulation of a gas-condensate mixture passing through a porous medium in depletion mode

One of important tasks in a development of gas-condensate fields is to minimize hydrocarbons loss arising from the gas condensation in pores of the gas-bearing layer. The search for the optimal gas production regime is carried out both on the basis of laboratory experiments and on the base of computer simulation. In this regard, the relevant is the verification of the constructed mathematical models by means of comparison of numerical results with experimental data obtained on the laboratory models of a hydrocarbon reservoirs. Within the classical approach on the basis of the Darcy law and the law continuity for flows, the model is formulated that describes the passing a multicomponent gas-condensate mixture through a porous medium in the depletion mode. The numerical solution of the corresponding system of nonlinear partial differential equations is implemented on the basis of the combined use of the C++ programming language and the Maple software. Shown that the approach used provides an agreement of results of numerical simulations with experimental data on the dynamics of hydrocarbon recoverability depending on the pressure obtained at VNIIGAZ, Ukhta.

Simulation of a gas-condensate mixture passing through a porous medium in depletion mode

One of important tasks in a development of gas-condensate fields is to minimize hydrocarbons loss arising from the gas condensation in pores of the gas-bearing layer. The search for the optimal gas production regime is carried out both on the basis of laboratory experiments and on the base of computer simulation. In this regard, the relevant is the verification of the constructed mathematical models by means of comparison of numerical results with experimental data obtained on the laboratory models of a hydrocarbon reservoirs. Within the classical approach on the basis of the Darcy law and the law continuity for flows, the model is formulated that describes the passing a multicomponent gas-condensate mixture through a porous medium in the depletion mode. The numerical solution of the corresponding system of nonlinear partial differential equations is implemented on the basis of the combined use of the C++ programming language and the Maple software. Shown that the approach used provides an agreement of results of numerical simulations with experimental data on the dynamics of hydrocarbon recoverability depending on the pressure obtained at VNIIGAZ, Ukhta.

Simulation of a gas-condensate mixture passing through a porous medium in depletion mode

One of important tasks in a development of gas-condensate fields is to minimize hydrocarbons loss arising from the gas condensation in pores of the gas-bearing layer. The search for the optimal gas production regime is carried out both on the basis of laboratory experiments and on the base of computer simulation. In this regard, the relevant is the verification of the constructed mathematical models by means of comparison of numerical results with experimental data obtained on the laboratory models of a hydrocarbon reservoirs. Within the classical approach on the basis of the Darcy law and the law continuity for flows, the model is formulated that describes the passing a multicomponent gas-condensate mixture through a porous medium in the depletion mode. The numerical solution of the corresponding system of nonlinear partial differential equations is implemented on the basis of the combined use of the C++ programming language and the Maple software. Shown that the approach used provides an agreement of results of numerical simulations with experimental data on the dynamics of hydrocarbon recoverability depending on the pressure obtained at VNIIGAZ, Ukhta.

Finite element modelling of the stress-strain state in specimens from dissimilar Ni-based alloys during pressure welding with displacement

ABSTRACT In this paper, the possibility of producing a bimetallic disc-shaft-type part for a gas turbine engine made from dissimilar heat-resistant nickel-based superalloys by means of pressure welding in the presence of shear deformation is considered on the basis of computer simulation. It is shown that the quality of a solid-phase joint of the part depends on the scheme of shaft insertion into the disk, the angle of the shaft taper and the degree of surface treatment.