Calculation Scheme Research Articles

NUMERICAL SIMULATION IN CALCULATIONS OF TECHNOLOGICAL SYSTEMS OF ELECTROMAGNETIC PROCESSING. PART I: PROPAGATION OF THE ELECTROMAGNETIC FIELD

The article deals with the problem of numerical modeling when calculating electromagnetic field propagation in electromagnetic molding systems. From the analysis of open information sources, it follows that the problem of numerical modeling when creating new technological operations of electromagnetic molding or when improving existing ones is relevant in a scientific and practical sense. This is due to the need to perform adequate numerical modeling and computational analysis of technological systems and technological operations at the stage of creation and improvement. With regard to technological systems of electromagnetic processing, calculation schemes and models should make it possible to study the propagation of a non-stationary electromagnetic field and to study the processes of nonlinear deformation of technological elements, which is caused by the force interaction of the induced electromagnetic field with the field of the source. Adequate numerical modeling must be based on appropriate calculation procedures based on numerical methods. The article substantiates the need to use numerical methods for calculation analysis, which allow creating calculation schemes closer to reality to a greater extent compared to the case of using analytical approaches and methods. The most effective numerical method is the finite element method, which allows the analysis of the non-stationary electromagnetic field and deformation within the same calculation scheme. In this case, within the framework of the finite element method, iterative schemes can be created that allow taking into account nonlinear effects. Here, nonlinear effects can be caused by the dependence of the mechanical and electrophysical properties of the material on temperature, the plastic nature of the deformation, as well as the need to account for contact phenomena. The results of modeling the propagation of the electromagnetic field of a single-turn inductor are presented.

A modified artificial electric field algorithm and its application

Abstract As an efficient meta-heuristic technique, artificial electric field algorithm (AEFA) has been extensively applied to tackle various challenging tasks posed by practical scenarios. However, in the classical AEFA, the fitness function has a cumulative effect on the charge, resulting in limited search capability. To address this issue, a modified AEFA (MAEFA) is presented in this paper. More specifically, a novel charge calculation scheme is introduced to overcome the cumulative effect by gradually distinguishing the charges of particles during the evolutionary process. Further, an alternating search strategy is developed to calculate the total electrostatic force, thereby reinforcing the guiding effect of excellent individuals on the entire population. Subsequently, the performance of MAEFA is investigated using 42 well-benchmarked functions, two chaotic time series prediction problems, and two engineering design problems. Experimental results reveal that MAEFA is more competitive in comparison with several established AEFAs and 20 popular meta-heuristic techniques.

Deadline and Period Assignment for Guaranteeing Timely Response of the Cyber-Physical System

Cyber-physical systems (CPSs) need to respond to each change of each monitored object in time. The entire response process can be divided into two stages: the update stage and the control stage. Tasks in CPSs can thus be divided into two kinds: update tasks and control tasks. Assigning deadlines and periods for tasks to ensure a timely response to each change of each monitored object is an important problem in CPS research. Existing methods can ensure that all changes of all objects can receive timely responses if tasks are schedulable. However, these methods have not made efforts to ensure the schedulability of tasks. Therefore, some tasks that can actually receive services cannot be serviced under these methods. In this article, we study the problem of assigning deadlines and periods for tasks while ensuring timely responses and maximizing the schedulability of tasks. Specifically, we find that the delayed deadline assignment for update tasks is the main factor that causes the low scheduling capability of existing methods. A new deadline and period assignment method is proposed based on an optimized deadline calculation scheme and an advanced deadline determination mechanism. Theoretical analysis proves the correctness and superiority of the proposed method. Experimental results show that the new method can improve 30.02% acceptance ratio and save 98.48% runtime on average, as compared to the state-of-the-art deadline and period assignment method.

On the Optimal Distribution of Traction Forces in Cable Propulsors of Mobile Robots

The analysis of methods of distribution of traction forces in various propellers of mobile robotic complexes and transport vehicles is carried out. The problem of synthesizing a method for controlling the distribution of the total traction load between interconnected electric drives of mobile robot propellers, discretely interacting with the support surface, is considered. An underwater mobile robot is simulated with several "walking-like" anchor-cable propellers, which ensure the movement of the underwater mobile robot by pulling the body to the supports located on the bottom. A mathematical model of the rectilinear motion of a mobile robotic device with walking-type propellers has been compiled. A mathematical description of the electric drive of the propulsion of such a mobile robot is proposed, taking into account its kinetic transfer function. It is shown that the total traction effort realized by a mobile robot is the source of the moment of resistance in the electric drive of each mover. In this regard, coefficients characterizing the distribution of traction force have been introduced into the differential equation of electric drives. A feature of the functions of these coefficients is their dependence on the distance traveled, speed and strength of resistance to movement. To optimize the distribution of the total power load between the thrusters, a target functional has been compiled. It is shown that as such a target functional, a requirement for a minimum of total heat losses in an interconnected electric drive of propellers can be formulated. To find the minimum of the accepted functional, the Euler-Poisson equations are compiled. As an additional limitation, the condition of physical feasibility is introduced. The results of solving such an optimization problem are presented on the simplest calculation scheme of two DC electric drives, between which the load is distributed along the rectilinear movement of a solid. As a result of solving the formulated optimization problem, the dependences of control actions for electric drives (voltage for DC electric drives), graphs of changes in the target function providing optimal distribution of traction forces between them are obtained, and the optimality of such distribution is proven.

СОГЛАСОВАНИЕ ГЕОМЕТРИЧЕСКИХ ХАРАКТЕРИСТИК ФАКТИЧЕСКОГО ПОВОРОТА КОЛЁСНОЙ МАШИНЫ

Based on the above calculation scheme of controlled curvilinear motion of a wheeled vehicle, it was revealed that the steering trapezoid causes some discrepancy between the kinematics of real and correct rotation. It is established that when adjusting the track width of the machine, the kinematic mismatch between the optimal rolling conditions of the wheels increases, and, consequently, the calculated dependences of the parameters of the ideal turn will not give a satisfactory result when analyzing the actual turn. The minimum theoretical turning radius is taken as an estimated indicator of the turnability of a wheeled vehicle. The conclusion of a multifunctional analytical dependence for determining the theoretical minimum turning radius of a wheeled vehicle, the wheels of which are controlled by a steering trapezoid, is presented. The resulting formula includes the longitudinal base of the machine, the pin track, the angles of rotation of the inner and outer steerable wheels. A comparison of the calculation results according to the developed and known formulas is given, which confirmed the complete convergence. It was found that, for example, an increase in the pivot track of the machine by 0.2 m leads to an increase in the theoretical minimum radius of the actual turn by 16.5%, and the distance from the continuation of the rear axle to the instantaneous center of rotation by 45.07...98.02% when the angle of rotation of the inner steering wheel changes from 20° to 40°.

Numerical Analysis on the Excavation Damage Evolutions of Layered Tunnels: Investigations on the Influences of Confining Pressure and Layer Angles.

The bedding structure of layered tunnels has a significant impact on the evolution of excavation damage, yet research on the relevant evolution mechanisms is scarce. In view of this, this paper develops a mesh-free numerical method to simulate the progressive damage process of tunnel excavation and proposes a method for applying stress boundaries within the SPH framework. Through this method, simulations of tunnel excavation damage under different bedding dip angles and stress ratios are conducted. The results show that the following: in the simulation of excavation damage of a tunnel without bedding structures, specific areas around the tunnel exhibit characteristics of tensile-shear composite failure and shear failure, verifying the rationality of the algorithm; under different bedding dip angles, a damage zone is first generated around the tunnel, and shear cracks appear at the tangent of the bedding plane and the tunnel, with the damage degree being the largest when α = 30° and the smallest when α = 45°; and under different stress ratios, the damage starts around the tunnel, continuously evolves, and finally forms a failure zone inside the bedding plane joints tangent to the tunnel, and the damage degree increases with the increase in the stress ratio. This study discusses the damage mechanisms under different calculation schemes and provides a reference for understanding the excavation damage mechanisms of layered tunnels.

The stiffness of the joint connection of the translucent filling with the elements of the supporting frame of translucent facade systems

Problem statement. The study of the rigidity of nodes between elements is one of the directions of improving the calculation schemes of translucent facade structures. By analogy with other types of structures, the introduction of the rigidity of nodes obtained as a result of numerical and (or) experimental studies into the calculation scheme allows us to obtain a picture of the stress-strain state closer to the actual operation of the structure. As a result of it the prediction of the behavior of the structure under the action of various loads becomes more accurate. In addition, the study of the rigidity and behavior of nodes of translucent structures under static loads opens up space for moving on to the issue of the operation of facade systems under dynamic loads (pulsation component of wind load, seismic loads). The objectives of the study are: experimental studies of the rigidity of the connection node of the translucent filling with the elements of the supporting frame of the TFC, numerical studies of TFC fragments taking into account the obtained rigidities and analysis of the influence of the rigidity of the node on the operation of the SFC fragment. Results. The graphs of the dependence of displacements on forces reflecting the rigidity of the studied node were obtained, calculation schemes were created taking into account the obtained rigidities, the results were analyzed, further directions for the study of translucent facade structures were determined. Conclusions. The significance of the obtained results lies in identifying the influence of the rigidity of the glazing connection node with the pillar/beam and the inclusion of fragments of the glazing TFC in the calculation scheme as a whole on the spatial operation of translucent facade systems.

Determination of the particle size distribution of cube-shaped colloidal perovskite quantum dots from photoluminescence spectra: A combined theoretical-experimental approach.

A theoretical-experimental approach is proposed to convert the photoluminescence spectra of colloidal perovskite quantum dot ensembles into accurate estimates for their intrinsic particle size distribution functions. Two main problems were addressed and properly correlated: the size dependence of the first excitonic transition in a single cube-shaped quantum dot and the inhomogeneous broadening of the fluorescence line shape due to the size nonuniformity of the chemically prepared quantum dot suspension in addition to the single-dot homogeneous broadening. By applying the reported methodology to CsPbBr3 quantum dot samples belonging to the strong and intermediate confinement regimes, the calculated size distributions exhibited close agreement with those obtained from transmission electron microscopy, with precise estimates for the average particle size and standard deviation. Specifically for strongly confined ultrasmall CsPbBr3 quantum dots, the presented spectroscopic model for size distribution computation is based on a new analytical expression for the size-dependent bandgap, which was developed within the framework of the finite-depth square-well effective mass approximation accounting for band nonparabolicity effects. Such a quantum mechanical approach correctly predicts the expected transition to the intermediate confinement regime in sufficiently large quantum dots, which are traditionally described by the well-known bandgap equation in the infinite potential barrier limit with a spatially correlated electron-hole wavefunction and nonparabolic carrier effective masses. The proposed calculation scheme originates from general theoretical considerations so that it can be readily adapted to semiconductor quantum dots of many other systems, from all inorganic metal halides to hybrid perovskite materials, regardless of the adopted chemical synthesis route.

Real-time holographic 3D display using Split-Lohmann Fresnel computer-generated hologram (SL-FCGH).

Real-time generation of computer-generated hologram (CGH) from three-dimensional (3D) objects has been a long-standing problem in holographic display. In this paper we report a fast CGH generation algorithm, which can rapidly synthesize a 3D Fresnel hologram in only one-step backward propagation calculation in a Split-Lohmann lens-based diffraction model. In such a calculation scheme, we utilize an image padding and cropping strategy to remove image artifacts and improve the display quality in a large depth range. The generated hologram, which is called Split-Lohmann Fresnel CGH (SL-FCGH), can reproduce 3D images through free-space Fresnel diffraction optics. The computation time of the proposed method is independent of the quantized layer numbers and, therefore, can achieve real-time computation speed with a very dense depth sampling. Both simulation and experimental results of full-color holographic display prove the validation of the proposed method.

Развитие модели динамики снежного покрова Гидрометцентра России

Conceptual models of runoff formation used in the operational practice of hydrological forecasting by the Hydrometeorological Center of Russia include simplified parameterization of snow cover dynamics based on the use of snow cover melting coefficient, water-retaining capacity of snow and secondary freezing of meltwater in case of return of negative air temperatures. This schematization of the process is well established for the reliable calculation of the snow water equivalent for subsequent use in the calculation of meltwater inflow to the catchment surface and the calculation of streamflow characteristics. At the same time, the lack of calculation of snow density and snow height in the used schematization restricts the use of schemes for calculating of soil freezing depth in hydrological models, which seems to be extremely important for modelling runoff on mid-latitudes rivers, i.e. for the most Russian rivers. To overcome this disadvantage, the snow density and snow height parameterization was added to the calculation scheme of the model, which was verified using Roshydromet’s snow measurement routes data and shown a good and satisfactory quality of modeling of model characteristics.

Electromagnetic force calculation within finite volume framework

ABSTRACT In this research, the comparison of force calculation methods in magnetostatic simulations within a cell-centered finite volume framework is presented. Various procedures for postprocessing of the magnetic vector potential field are laid out to obtain the surface and volume integrals of Maxwell’s stress tensor and the Lorentz force density. Two different magnetostatic problems with multiple operating points were modeled with the AVL FIRETM M. The force results have been verified by comparing them to the Ansys Maxwell and were validated on a benchmark case from a Testing Electromagnetic Analysis Methods (TEAM) workshop. The interpolation of the magnetic flux density on a multi-material interface is presented, and it is used in conjunction with the surface integral of Maxwell’s stress tensor for an efficient global force computation. For all observed cases, the calculated results correspond well to the results found in the literature. It was found that the accuracy of the volume integral of Maxwell’s stress tensor is dependent on the mesh quality and gradient calculation scheme. Employing the semi-structured mesh with Gauss’s gradient scheme results in force discrepancies of less than 3% between the surface and volume integral of Maxwell’s stress tensor. The convergence of the iterative solver is observed to be slower in the case of the materials with permeability jump, where discontinuities between the tangential component of the magnetic flux density and the normal component of the magnetic field intensity occur.

A new tunnel drainage system using double-adhesive spray-applied membrane: key parameters and applicable scope

To address water leakage in tunnels with high water pressure, a new waterproof drainage system was proposed. The system uses a spray-applied material with double-adhesive properties as a waterproof layer, significantly reducing leakages, and incorporates a unique bottom drainage system to reduce water pressure. In order to check the effectiveness of the new drainage system and to analyze the effects of various structural measures on pressure reduction, a numerical seepage analysis was carried out under the conditions of a water head of 160 m and a surrounding rock permeability of 1 × 10−6 m/s. The results show that the maximum water pressure on the secondary lining is 0.6 MPa, which is about 60% reduction compared to a fully enclosed waterproof system and shows a significant pressure reduction. The spacing of the circumferential drainage pipe and the width of the drainage sheet significantly affect the drainage performance, while the arrangement of the drainage system and the size of the bottom drainage pipe have minimal impact. With full consideration of pressure reduction, cost efficiency and construction feasibility, it is recommended to use the following drainage scheme for iterative calculations during the design stage: “1” shaped arrangement, blind pipe diameter of 10 cm, width of drainage sheets of 0.8 m, and drainage spacing of 6 m. By combining the experimentally determined hydrostatic peel-off strength of 1.4 MPa for spray-applied membrane, the applicable scope of the new drainage system was acquired. The research results can provide valuable insights into the application of spray-applied waterproofing membrane in drainage tunnels with high water pressure.

Розрахунок несної здатності аркової дорожньої споруди з гофрованого металу аналітичним способом

Introduction. One of the possible options for a simple, practical design of an arched road structure (small bridge) made of corrugated metal is considered, which can be considered as one that is more accurate and labor-intensive for the design of such a structure under the road pressure, as the “structure – soil” system for finite element method. Problem Statement. Regular normative and methodological documents for the design and maintenance of road structures (culverts, small bridges, tunnels) made of corrugated metal provide a simple formula for the structure of the structure and deformation of the body for such structures round pipes. The world is constantly streaming a wider range of rational and fairly simple types of road structures. Purpose. To show one of the possible ways of calculating an arched road structure made of corrugated metal on the basis of generally accepted initial provisions and a simple, understandable calculation scheme is the goal and task of this work.

Pelatihan dan Sosialisasi Perhitungan PPH 21 Terbaru Dengan Tarif Efektif Rata-Rata Peraturan Pemerintah Nomor 58 Tahun 2024 Tentang Tarif Pemotongan PPH Pasal 21 Pribadi Pada UMKM Lingkungan Magetan

On January 1 2024, the government has changed the regulation og tax income, calculation scheme using Average Effective Rate (TER) through Government Regulation Number 58 of 2023 concerning Withholding Rates for PPh Article 21 on Income in Connection with Work, Services or Activities of Individual Taxpayers. This change in the PPh 21 deduction scheme is because the current calculation scheme can confuse taxpayers and tends to burden those who want to carry out their tax obligations properly. This challenge is also faced by MSME actors in Jonggrang Magetan Village. Seeing the diverse levels of business and promising MSMEs, MSME actors are also faced with difficulties in fulfilling their tax obligations, coupled with the new policy issued by the government regarding calculating PPH 21 using the calculation method. Therefore, in order to support MSMEs to understand and implement their tax obligations correctly, a systematic and structured training program is needed. Therefore, this proposal proposes holding Training and Socialization of the Latest PPh 21 Calculation with Average Effective Rates (TER) Government Regulation Number 58 of 2023 concerning Rates of Withholding of PPh Article 21 on Income in Connection with Work, Services or Activities of Individual Taxpayers in Magetan Environmental MSME Association.

Evaluation of the Spatial Variability of the Mechanical Properties of Rocks Using Non‐Iterative Green's Function Approach and the FOSM Method

ABSTRACTThe present work proposes a new version of the Green‐FOSM (first‐order second moment) method, which eliminates the iterative calculation process of the original version and, simultaneously, solves the convergence problems related to the mechanical properties of rocks that form the geological formation. In this calculation scheme, the iterative process is eliminated by using a matrix that correlates the nodal displacement vector with the strain vector. Considering the same computational resources, this non‐iterative version of the Green‐FOSM method is up to 200 times faster than the original iterative process. In addition, it allows analyzing problems with more than 10,000 random variables, value that in the original method is less than 3000. To demonstrate its validity, the proposed method is applied to two hypothetical models subjected to different fluid extraction processes. For all the different levels of correlation and spatial variability, the statistical results obtained by the proposed method agree well with the results obtained via Monte Carlo Simulation (MCS). The relationship between CPU times demonstrates that the proposed method is at least 50 times faster than MCS. In the end, the non‐iterative Green‐FOSM method is used to obtain the displacement, strain, and stress fields of a geological section constructed from a seismic image of Brazilian pre‐salt oil region. The results found show that, depending on the levels of spatial variability, the analyzed fields can assume values up to 30.6% higher or lower than the values obtained deterministically.

Implementation of the Zienkiewicz–Pande Model into a Four‐Dimensional Lattice Spring Model for Plasticity and Fracture

ABSTRACTPlasticity and fracture problems have always been hot topics in numerical methods. In this work, a universal implementation procedure for the elasto‐plastic constitutive model is developed in the four‐dimensional lattice spring model (4D‐LSM), in which the Jaumann stress rate is incorporated to exclude the influence of the rigid rotation in the particle stress, expanding the ability of 4D‐LSM to deal with large elastic deformation problems by its own to large plastic deformation problems. As an example, the Zienkiewicz–Pande (ZP) constitutive model is implemented. Several numerical examples are carried out to check the performance of the implemented model. Through a comparison with analytical solutions, available experimental data, and other numerical results, the stability of the developed plastic framework and the correctness of the stress calculation scheme are verified. Meanwhile, numerical results show that the developed code is capable of solving elasto‐plastic large deformation problems. With the advantage of 4D‐LSM in handling fracture problems, the ability of the embedded model to solve plastic fracture problems is verified with a simple maximum deformation failure criterion.

Optimization of Rafter and Frame structures

Objective. Trusses and frames are widely used in the design and construction of buildings and structures, since they have high load-bearing capacity and rigidity. At the same time, they have a significant mass. In order to reduce the mass and cost of rafter and frame structures, this article develops optimal design and calculation schemes using steels of different strengths. Method. The study is based on the theory and methods of design optimization. By studying the features of the frame and truss operation, the most loaded elements of the structures are determined. In accordance with this, steels of different strengths are selected, which ensures a decrease in the mass of the structure and its cost. Comparing various design and calculation schemes, the optimal distribution of steels of different strengths along the span of the structures is proposed. Result. The developed design and calculation schemes make it possible to reduce the mass and cost of frames and trusses by optimally distributing steels of different grades. Conclusion. The proposed solutions can find application in the practice of designing and constructing metal structures. Structural schemes of trusses and frames have been developed, where steels of different strengths are used, which in terms of weight and cost compare favorably with corresponding structures made of steels of the same strength (one grade).

Free vibrations of a Continuous-discrete multi-span Beam taking into account inertial Rotation Forces

Objective. The aim of the study is to estimate free vibrations of a continuousdiscrete multi-span beam taking into account the inertial forces of rotation. The goal is to determine the spectra of natural frequencies, damping coefficients and natural modes. Method. The study is based on the methods of linear mechanics of structures; numerical and numericalanalytical calculation methods. The solution to the problem is found using the method of separation of variables. Rotational movements of particles of continuous sections are taken into account according to one of the models of the Timoshenko beam. The D'Alembert principle and hypotheses on the smallness of displacements and angles of rotation of sections are used. Result. A system of equations in matrix-vector form is obtained. The mathematical model of transverse vibrations consists of three systems of differential equations. The equation includes transverse forces, external concentrated forces, d'Alembert inertial forcesi, and linear-viscous resistance forces. The inertial forces of rotation of concentrated masses are taken into account. The boundary and other additional conditions to the equations correspond to the calculation scheme. The left end of the beam is hinged. The conjugation conditions are met at the junction of the sections. Conclusions. This random process of disturbances is very close to the processes used in deterministic problems. The amplitudes and standard deviations of displacements in the deterministic and stochastic problems almost coincide, which confirms the reliability of the proposed calculation theory. Analysis of the curves shows that the standard deviations significantly depend on the degree of correlation of the components of the vector random process of disturbances. The use of modern computing computer systems such as Matlab allows us to successfully combine the advantages of both numerical and graphical methods.

Trustworthy fog: A reputation-based consensus method for IoT with blockchain and fog computing

This paper proposes Trustworthy Fog, a novel reputation-based consensus method for Internet of Things (IoT) systems that leverages blockchain and fog computing technologies. By integrating fog computing’s near-end data processing capabilities with blockchain’s immutability and transparency, the proposed method addresses challenges related to latency, device load, and the adaptability of traditional consensus algorithms to resource-constrained environments. A reputation management module evaluates device and node behaviors, facilitating rapid authentication and consensus processes. Distinct reputation calculation schemes for physical devices and fog nodes aim to prevent reputation centralization through periodic resets of reputation values. Based on these values, a lightweight consensus algorithm balances computational capacity and reputation to select leader nodes. Simulations demonstrate the method’s effectiveness in dynamically reflecting device trustworthiness and ensuring fair consensus participation. This research advances IoT blockchain technology, offering a robust solution for the scalability and security challenges inherent in IoT networks.

Research on optimization of flatness evaluation method for antenna array of a radar vehicle

Abstract Radar vehicles play an important role in providing radar services in the aviation field. The flatness of the antenna array is one of the key factors in ensuring the detection accuracy of radar vehicles for airborne targets. In this paper, the mechanical structure of a new type of radar antenna truck is designed, the stress analysis under various working conditions is carried out, the mechanical performance of the whole vehicle is checked, and the evaluation method of the flatness of the antenna array is discussed. Using ANSYS to carry out static finite element analysis and using the deformation results of each element node in ANSYS, the evaluation method based on the multiple regression function is applied to the calculation scheme of antenna array flatness. The final results show that the safety factor of the radar vehicle structure can reach more than 1.75 under extreme working conditions and more than 2.0 under other working conditions. It can work safely. Through the optimization of the shape evaluation method, the accuracy of the final shape calculation result is less than 10mm. The precision of shape error processing is improved.