Sufficient Calculation Accuracy Research Articles

Mathematical modeling of minimization of electricity consumption by industrial enterprises with continuous production

Relevance. Determined by the importance of minimizing electrical power consumption in industrial enterprises with continuous production, considering the specific characteristics of their technological processes and the requirements to maintain the output volume of their products. Aim. To solve the task of minimizing electrical power consumption based on a mathematical model and gradient method under optimal planning of the production volume of the industrial enterprises with continuous production; to develop a mathematical model for optimal distribution of production over a time cycle (month, quarter, year) across departments, taking into account both simple and functional constraints, derived from the condition of ensuring minimal electrical power consumption in industrial enterprises with continuous production. Methods. When developing the mathematical model for ensuring minimal electrical power consumption while preserving the production volume, classic Lagrange optimization methods were used. To ensure sufficient calculation accuracy, iterative methods were also applied. For the task under consideration, a calculation error margin of ε=0,1 was assumed and established. It is known that the choice of calculation error margin depends on the specifics of the problem at hand and the decision-maker. To verify the adequacy of the developed model, the method of finding the relative extremum of a function of several variables was used. Results. The use of the mathematical model, which takes into account the nature of the technological process and boundary conditions in both simple and integral forms, demonstrated the feasibility of optimal planning of electrical power consumption by the enterprise. The effectiveness of the developed approaches was verified using a metallurgical enterprise as an example of an industrial enterprise with continuous production, in solving the task of minimizing electrical power consumption for products produced during the reporting period. The use of the proposed model allowed for a reduction in annual electrical power consumption by 2.5% while maintaining the same production volume. One of the classic optimization methods – the method of finding the relative extremum of functions of several variables – showed almost identical results upon verification. This serves as further evidence of the adequacy of the proposed model.

Investigation of greenhouse emission inventory from transport system functioning in large and medium cities

The object of the research of the article is transport system of a city. The paper reviews the necessity to assess the greenhouse emissions in the city and proposes the methods for greenhouse emissions inventory of the urban transport system. The proposed approach is aligned with guidelines for the development of Sustainable Energy and Climate Action Plan (SECAP) of Mayor Covenants of European Union (EU). The methodologies outlined in the paper allow to estimate annual greenhouse emissions from transport sector. The SECAP defines transport sectors based on ownership and functioning as following: municipal transport fleet, public transport, and private and commercial transport. The paper proposes the methodology to estimate direct and indirect emissions in each of the described sector based on the information that is typicaly available to municipalities in Ukraine. The assessment is conducted on disaggregated level for different fuel types (diesel, petroleum, natural gas, biofuel, electricity, etc.) and separately for each fleet type (buses, trucks, passenger vehicles, specialized machinery). Total CO2 emissions are then estimated by multiplying the amount of fuel consumed by the emission factor for each fuel type and vehicle type. Information of fuel consumption is estimated based on annual milage and estimated based on available data and number of assumptions proposed in the paper. The proposed methodology for greenhouse emissions inventory for the transport sector allows to analyze available data, recommendations for data collection and a methodology for determining CO2 emissions from the operation of the transport system with sufficient accuracy of calculations. Based on these results, it is possible to forecast changes in energy consumption and emissions in the transport sector as a result of various interventions. For example, in Zhytomyr city the results of inventory were used to develop a set of measures, which include updating the rolling stock of electric transport; increasing the energy efficiency of the power grids of the transport system, developing cycling infrastructure.

Экспериментальная оценка адекватности численного моделирования межслоевой трещиностойкости слоистого стеклоэпоксикомпозита при комбинированной моде нагружения I/II

The reliability of numerical simulation of crack growth in a laminate glass-epoxy composite under mixed-mode loading by opening (mode I) and shear (mode II) of an interlayer crack is verified. According to the experimentally determined standard (DCB and ENF) and nonstandard (SLB and OLB) methods, the values of the parameters of interlayer crack resistance under individual and mixed-mode loading modes I and II calculated the exponent in the Benzeggagh-Kenane equation as a material constant of the laminate epoxy glass composite. Using this parameter and the ANSYS software package, within the framework of linear elastic fracture mechanics and the method of virtual crack closure, numerical finite element modeling of the growth of interlayer cracks in samples of a laminate glass-epoxy composite of the SLB and OLB types was carried out under a mixed-mode loading with a different fraction of modes. With the optimal number of elements in the finite element mesh per given length of the crack growth trajectory, numerical simulation provides sufficient accuracy of calculations of the limit load of the beginning of crack growth with a minimum amount of calculations and good agreement between the experimentally determined and calculated crack resistance parameters.

ГИДРОДИНАМИКА ДВУХФАЗНОГО ПОТОКА В ЦЕНТРОБЕЖНЫХ АППАРАТАХ С ПРОФИЛИРОВАННОЙ КОНТАКТНОЙ ЗОНОЙ

Interest in detailed study and modelling of processes occurring in heat and mass exchange equipment is determined by the variety of designs and types of apparatuses, as well as the number of different ways to intensify the processes occurring in the equipment. The study of hydrodynamics of technological media and interaction of phases (components) on contact devices allows to optimise the geometry of designed equipment in order to increase the efficiency of heat and mass exchange processes. For modelling and analysis of the processes occurring in the technological equipment, the software complexes of computational fluid dynamics based on the methods of finite element analysis are often used, which allow to obtain contours of velocity, concentrations, temperature and pressure distribution only for single-phase media. However, modelling of technological processes implies description of hydrodynamics of multiphase media, which today in conditions of influence of centrifugal field and Coriolis acceleration on the nature of interaction of flows is a rather complicated task requiring significant computational resources, machine time and human resources. In connection with the above mentioned, it is of interest to develop an approach to modelling, combining simplicity of analytical dependencies and providing sufficient accuracy for calculation, determined by satisfactory agreement of the obtained results with literature data and results of numerical studies in software complexes of computational fluid dynamics. In this paper we propose a mathematical description of the solution of the hydrodynamic problem associated with the determination of the flow velocity of a two-phase flow in a profiled nozzle of a centrifugal apparatus. The basic differential equations and boundary conditions describing the flow of interacting phases in the profiled nozzle are given in the text.

О МОДЕЛИРОВАНИИ ПРОЦЕССА ТЕЧЕНИЯ РЕЗИНОВЫХ СМЕСЕЙ В КАНАЛАХ СОЭКСТРУЗИОННОЙ ГОЛОВКИ С УСИЛЕННОЙ ЗОНОЙ КОНТАКТА МАТЕРИАЛОВ

Currently, in the chemical and related industries, the process of obtaining polymeric, two-layer products with a reinforced contact zone of materials is common. These products include: caterpillar tracks, liners for tram tracks, etc. Particular attention is paid to the quality of products obtained by coextrusion. The article presents ways to solve problems of obtaining a strong connection between the layers of materials and an unstable shape of the extrudate at the outlet of the co-extrusion head. The authors propose to use a co-extrusion head with a reinforced material contact zone. In order to save time and computing resources, it is necessary to identify a rational design zone, in which sufficient calculation accuracy will be ensured. To identify the rational design zone, numerical experiments were carried out in the ANSYS software and computer system. The Maxwell model was chosen as the rheological model. Velocity and pressure distribution patterns were obtained, which can be used to solve various applied problems. It was revealed that the maximum speed is achieved in the center of the head section, while its minimum values are located along the periphery. As a result, dependences of the velocity inhomogeneity coefficient in the outlet section on the relative tooth height were drawn. The resulting regression curves are similar for the cases of the full and partial simulation zones. That is why it is sufficient to simulate the process only in the part of the extrusion head. With such a scheme, the number of finite elements will be less, which, with a given accuracy, will reduce the calculation time. The results obtained can be used in the design of co-extrusion heads for tire and rubber industries in order to replace foreign equipment with domestic developments.

Study on a Rapid Aerodynamic Optimization Method of Flying Wing Aircraft for Conceptual Design

Searching for a design scheme satisfying the requirements in aircraft conceptual design can be a time-consuming work because of the multipeak and nonlinearity of the design space. This paper proposed a rapid aerodynamic optimization method for flying wing aircraft conceptual design. This method is aimed at reducing the induced drag at the design point by adjusting the camber and twist angle of spanwise airfoil. Firstly, the mean camber surface of the flying wing aircraft was parameterized. Secondly, the surrogate model was constructed based on the points selected by the optimization Latin square method. Thirdly, the surrogate model combined with a multi-island genetic algorithm was used for the preliminary solution of global optimum, and then, the Nonlinear Programming by Quadratic Lagrangian method combined with a vortex lattice method was used for searching the nearest exact best point from the initial best point. Finally, connecting with manual selection, the optimized flying wing layout scheme was obtained. The optimized results show that the induced drag coefficient is reduced by 10%, the pitching moment coefficient is reduced by an order of magnitude, and the lift drag ratio is increased from 26.3 to 27.3. The proposed optimization method decreases the time cost in aircraft conceptual design while achieving sufficient calculation accuracy. By using this method, the design space can be explored rapidly to search for the best design scheme satisfying the constraints.

Vibration analysis of aero parallel-pipeline systems based on a novel reduced order modeling method

The modeling of parallel-pipeline is a difficult work in engineer field duo to long distance complex pipelines. Vibration analysis of pipeline can become prohibitive due to high computational time associated with large number of degrees of freedom. Thus, the efficient model reduction technique to analyze the vibration characteristics of pipeline system is challenging for designers. The objective of this paper is to propose a reduced order modeling method of parallel-pipeline with multi-supports. Considering the constraint interface stiffness at the elastic support and the coupled fluid-structure pipeline system, a novel reduced order model is obtained by assembling the reduced substructure element. Modal analysis is performed for parallel-pipeline system, and the calculation results for reduced order model are compared with the full finite element model. The obtained results indicate that the natural frequencies and mode shapes of the reduced order model are consistent with full finite element model. Moreover, an interesting phenomenon is obtained that the fluid velocity in one of parallel-pipeline can decrease the natural frequencies of another pipeline. The proposed model can obtain sufficient calculation accuracy and higher calculation efficiency, which can provide insight and guidance for engineers in aircraft.

Constitutive model for thin-walled H-sections bent about weak-axis considering local buckling

Since earthquakes occur in random directions, the seismic behavior of thin-walled structures about the weak-axis cannot be ignored, thus the corresponding constitutive model is necessarily needed. To achieve sufficient calculation accuracy and efficiency, the constitutive model of thin-walled steel H-sections, based on moment-curvature curves in the sectional level, is proposed in this paper. Firstly, the validated FEA models were utilized to conduct the parametric studies, where the effects of strain hardening rate and loading protocol on the constitutive model were fully discussed. Based on a large number of moment-curvature curves derived from the FEA models results, the undetermined parameters of the constitutive model were identified. The constitutive model provided precise predictions on hysteretic responses of H-sections, with the unfavorable coupling effects of plate interaction and local buckling fully considered. According to the different buckling mechanisms of H-sections based on the experimental and numerical results, the model was divided into two categories, including the post-buckling stage with decreased-reloading-stiffness (DRS) and increased-reloading-stiffness (IRS). Correspondingly, the proposed constitutive model contains one backbone curve and four types of hysteretic rules. Finally, comparisons of the proposed constitutive models with experimental and numerical results are conducted for further adjustments, which shows the model achieved high accuracy in a variety of loading scenarios.

Simulation Technique of Kinematic Processes in the Vehicle Steering Linkage

The results of the investigation of the turning kinematics of the steerable wheels of the KrAZ-7634NE off-road vehicle with a wheel formula 8x8 and two front steer axles are given. The theoretical relations between the steer angles of the steerable wheels on the basis of the scheme of double-axle steering turning of the vehicle are shown. The mathematical model of flat four-bar vehicle steering linkage is developed, it determines the relation between the steering linkage left and right steering arms turning angles at any turning radius of the vehicle. KrAZ-7634HE steering three-dimensional model was created and simulation technique of its work was carried out using Creo software. It has been shown that the flat steering linkage model provides sufficient accuracy of calculations in analysis of turning kinematics. The design data can be used for any vehicles that have a similar steering linkage, they allow to analyze the impact of the vehicle design parameters on the turning kinematics and optimize them. Further study of the impact of the kingpin inclinations on the steering linkage kinematic and power characteristics are required.

Application of different curve interpolation and fitting methods in water distribution calculation of mobile sprinkler machine

In the calculation of water application in mobile sprinkler machines, various interpolation and fitting methods have been applied to describe the radial water distribution pattern of sprinklers. However, few studies have been carried out related to the accuracy and applicability of these methods. In this study, the radial water distribution curves were obtained by adopting cubic spline interpolation, Lagrange interpolation, least-squares polynomial fitting, and simplified geometric curves, respectively. The mobile spraying water distribution and spray uniformity coefficients were calculated based on these radial water distribution curves. The results indicated that the cubic spline curve and the least-squares polynomial fitting reflected the water distribution characteristics accurately, with the maximum deviation between the calculated values and the measured values being less than 10%. The existence of Runge's phenomenon in the Lagrange interpolation method led to sharp oscillations at both ends of the radial water distribution curve, resulting in large inconsistencies between the calculated value and the measured value of irrigation depth. The curves of the simplified geometric method were too simple to accurately characterise water application. Although the cubic spline interpolation showed high calculation accuracy, the large number of interpolation polynomial coefficients hinder its practical application. The least-squares based polynomial fitting curve showed both sufficient calculation accuracy and simple expression form, while the number of polynomial coefficients is only one more than the degree of polynomial. The recommended degree of polynomial fitting was six in this study.

Influence of geometric errors of guide rails and table on motion errors of hydrostatic guideways under quasi-static condition

Abstract Motion errors of hydrostatic guideways are mainly influenced by the geometric errors of guide rails and table which can be decomposed into harmonic waves of different frequencies based on Fourier transform. In this paper, a new approximate model is established to study the influence of geometric errors of guide rails and table on the motion errors of hydrostatic guideways using the equivalent third power of oil film thickness. It is found that, the motion errors are mainly affected by the geometric errors of guide rails rather than the geometric errors of table. The harmonic waves with wave numbers 0.5, 1.5, 2.5, 3.5, …, on the guide rails have no influence on the center displacement of table, and the harmonic waves with wave numbers 1, 2, 3, 4, …, have no influence on the yaw angle of table. The increment of land width and decrement of distance of two adjacent pads will result in enhancement of comprehensive averaging effect in consideration of center displacement and yaw angle. The approximate formulas have sufficient calculation accuracy compared with FEM when the ratio between amplitude of harmonic wave and initial film thickness is small. Using a deformed guide rail with wave numbers 0.5 and 1, the results of experiments agree well with the results calculated by approximate formulas and FEM. In the experiments, a novel method is proposed to manufacture the single harmonic wave of guide rail in the scale of micron meters, through which the amplitude and wavelength of the harmonic wave on guide rail can be controlled.

Regression equations for circular CFST columns carrying capacity evaluation

Within the last decades, a considerable amount of experimental studies have been carried out by numerous researchers across the world with the purpose to study the carrying capacity of concrete-filled steel tubular (CFST) columns and evaluation of their stressed-strained state. The array of the obtained results have allowed designing a mathematical model to determine the maximum carrying capacity value of such constructions using the methods of mathematical statistics. The authors obtained three types of regression equations for short and long circular CFST columns with different geometrical and physical properties under axial compression. Statistical quality of the obtained models was verified by both regression equation quality in general and statistical significance of the equation parameters. The comparison of the obtained carrying capacity values with the results calculated by Eurocode 4 and AIJ methodologies allows making a conclusion on the sufficient calculation accuracy of the designed mathematical models.

ラジアル型セルフベアリングモータにおける受動安定性の簡易推定式の検討

An implantable ventricular assist device requires that to have a high durability and efficiency, to flow blood without non-sliding, and miniaturizing the device. Therefore, we have developed a ventricular assist device using a radial type self-bearing motor. In the self-bearing motor, the radial position of the rotor is controlled actively, and the axial position of the rotor is passively stable within the thin rotor structure. In this paper, the estimating equation of the restoring force corresponding to the self-bearing motor's the passive stability in the axial direction was developed in order to reduce the designing time and elucidate the magnetic suspension characteristic. The estimating equation has the sufficient calculation accuracy that can be used for the prior design of the magnetic field analysis. The estimating equation has elucidated the interaction of the permanent magnet field and the magnetic field of rotation.

An improved solution for beam on elastic foundation using quintic displacement functions

The theory of beam on elastic foundation is a simple and popular analytic approach for computing the response of laterally loaded piles. For a laterally loaded pile with constant subgrade reaction coefficient, an analytical solution can be easily deduced based on the theory of beam on elastic foundation when the load distribution and boundary condition are simple. However, when the subgrade reaction coefficient increases linearly with the depth or when the constraint condition is complex, an approximate solution can only be obtained by numerical method. At present, the node-spring simulation method and the modifying stiffness matrix method are two main solution methods for beam on elastic foundation with a nonuniform distribution of subgrade reaction coefficient, but a large number of elements are necessary for obtaining a sufficient calculation accuracy. Based on the Winkler elastic foundation model, an improved Finite Element (FE) method for the laterally loaded pile on an elastic foundation with a linearly distributed modulus of the subgrade reaction is proposed. A quintic displacement function is proposed as an approximate solution, and the weighted residual method is used for solving differential equations. The corresponding element stiffness matrix and nodal force vector are derived, and a more accurate nodal displacement, element internal force and displacement distribution can then be obtained by employing fewer elements. Three beams on elastic foundations under different boundaries and loading conditions are taken as typical examples to compare the difference of the calculation accuracy between the improved method and the node-spring simulation method. A laterally loaded pile is analyzed by the improved method, and the numerical results show that two elements for one soil layer can provide a sufficient calculation accuracy.

A modified two-stage pulse tube cryocooler utilizing double-inlet and multi-mesh regenerator

In this paper a thermally coupled Stirling-type two-stage pulse tube cryocoolers (TSPTC) is studied using a one-dimensional (1-D) CFD code. After validating the results of the simulations, effects of synchronous utilization of multi-mesh regenerator and double-inlet on the performance of the TSPTC are investigated. Results of simulations show that non-oscillating friction factors do not possess sufficient accuracy for calculation of oscillating friction losses in non-porous media. Whereas, using oscillating friction factor of non-porous media leads to sufficient accurate results. According to the results, using multi-mesh regenerator and double-inlet increases the COP and decreases the minimum attainable temperature of the system. It is observed that a minimum temperature of 18.2K is attainable using optimum multi-mesh regenerator and double-inlet; whereas, for a simple TSPTC with a uniform mesh regenerator, a minimum temperature of 26.4K is concluded.

船の操縦性に及ぼす横揺連成影響について

Roll-coupling effect on ship maneuvering motions is not negligible for high speed vessels, large container ships, passenger ships and so on. To perceive the roll-coupling effect on the ship maneuverability, in this paper, approximate formulas for course stability criterion, steady turning index and the response time until reaching to steady turning (time constant) in the framework of the linear motion theory were derived on the assumption where the depthwise acting point of lateral force with respect to roll moment is constant even in any modes such as oblique moving, turning, rolling and steered conditions. Using the hydrodynamic derivatives measured in tank tests for 3 ship models, the roll-coupling effect on the ship maneuverability is discussed. The course stability becomes worse with increase of Froude number of the ship and/or decrease of metercentric height in general, and the turning performance is improved and the time constant becomes long. The approximate formulas have sufficient calculation accuracy and the formulas are useful for conventionally checking the ship maneuverability.

G0501-5-2 翼列計算のための格子構成と計算精度の検討(CFD)

H-type of single-block grids is commonly used for blade cascades, because the grids can be simply generated However, the mt important iegion around a leading edge has large grid distoffion including a singular point Therefore, it is considered that sufficient calculation accuracy cannot be thtained. In this study the grids are arranged by a multi-block grid and an overset grid which are made of O-grid around a blade and H-grid between blades, because the distortion of H-grid is improved by using an O-grid arotmdablade. The three type topologies are compared ith the experimental results, and the differences of the characteristics are investigated The results of computational fluid dynamics are well in agreement with experimental results for three grid topologies, and even H-grid it became clear that the accuracy is practically sufficient

寄生的離散ウェーブレット変換およびその異常信号検出への応用(機械力学,計測,自動制御)

In this study, in order to improve effectiveness of the abnormal signal detection, we first developed a novel parasitic discrete wavelet transform (P-DWT) to perform fast wavelet instantaneous correlation (F-WIC) and then proposed a new design method of the parasitic filters for the P-DWT. Furthermore, we showed a judgment standard for assessing the credibility of the abnormal signal detection by using the P-DWT. Finally, we applied the F-WIC to car rattle noise source identification and showed that our method can improve computation efficiency and obtain sufficient calculation accuracy at the same time.

On the formation and development of tropical cyclones

A method of diagnostic calculation of the maximal wind speed in the tropical cyclone, its radius, and central pressure is proposed taking into account large-scale air motions in a low-gradient baric field between subtropical anticyclones. The results of such calculations are considered. A conclusion is made about sufficient accuracy of calculations of the parameters within the tropical zone using only dynamic factors.

Efficient and robust algorithms for Monte Carlo and e-beam lithography simulation

A traditional method of e-beam lithography simulation uses the convolution of beam point spread function (a.k.a. “proximity function”) with the electron dose image to calculate density of energy deposited in resist. The proximity function is calculated by the Monte Carlo (MC) technique and a large number of simulated electrons are required to provide sufficient calculation accuracy. The purpose of this work is to describe effective algorithmic improvements that increase the performance of MC simulations while maintaining high accuracy of the calculated proximity function. We also consider the issue of robust integration when convolving the proximity function with electron dose image.