Algorithms for interpreting (decoding) of interferograms plotted by the finite-element method are considered. Three directional field-building methods are used in them: the (i) complex averaging method, (ii) the proje...
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Algorithms for interpreting (decoding) of interferograms plotted by the finite-element method are considered. Three directional field-building methods are used in them: the (i) complex averaging method, (ii) the projection-dispersion method, and (iii) the spectral method. The efficiency of the algorithms is checked on simulated and real interferograms.
The purpose of this paper is to specify the main components of the stray load loss of induction motors from both results of measurement and analysis. The IEEE standard 112 method B is applied to the cage induction mot...
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The purpose of this paper is to specify the main components of the stray load loss of induction motors from both results of measurement and analysis. The IEEE standard 112 method B is applied to the cage induction motor for the measurement of the stray load loss. On the other hand, the losses generated at the stator core, the rotor core, and the rotor cage are calculated directly by the finite-element method considering the magnetic saturation and the harmonic fields, which vary due to the load condition. The measured and the calculated torque, losses, and efficiency agree well. It is clarified that the main parts of the stray load loss in the case of the analyzed motor are the increase of harmonic losses due to load, which are the harmonic Joule losses of the rotor cage and the harmonic core losses of the stator and the rotor. The relationships between the losses separated by the measurement and the losses calculated directly by the finite-element method are also clarified.
This paper presents an adaptive refinement algorithm of a B-spline based finite-element approximation of the streamfunction formulation for the large scale wind-driven ocean currents. In particular, we focus on a post...
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This paper presents an adaptive refinement algorithm of a B-spline based finite-element approximation of the streamfunction formulation for the large scale wind-driven ocean currents. In particular, we focus on a posteriori error analysis of the simplified linear model of the stationary quasi-geostrophic equations, namely the Stommel-Munk model, which is the fourth-order partial differential equation. The analysis provides a posteriori error estimator for the local refinement of the Nitsche-type finite-element formulation. Numerical experiments with several benchmark examples are performed to test the capability of the posteriori error indicator on rectangular and L-shape geometries. (C) 2017 Elsevier B.V. All rights reserved.
The discretization inherent in the vector finite-element method results in the numerical dispersion of a propagating wave. The numerical dispersion of a time-harmonic plane wave propagating through an infinite, three-...
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The discretization inherent in the vector finite-element method results in the numerical dispersion of a propagating wave. The numerical dispersion of a time-harmonic plane wave propagating through an infinite, three-dimensional, finite-element mesh composed of hexahedral and tetrahedral edge elements is investigated in this work. The effects on the numerical dispersion of the propagation direction of the the wave and the electrical size of the elements are investigated. The numerical dispersion of the tetrahedral edge elements is Sound to be dependent upon the polarization of the plane wave propagating through the mesh. In addition, the dispersion of the tetrahedral elements is significantly smaller than the dispersion of the hexahedral edge elements. Both elements are found to have a phase error that converges nt the rate of O[(h/lambda)(2)]. (C) 1998 John Wiley & Sons, Inc.
To obtain the mechanical parameters for a microcapsule, such as the Young's modulus, yield stress, and hardening coefficients using different mechanical constitutive models, parameter identification must be implem...
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To obtain the mechanical parameters for a microcapsule, such as the Young's modulus, yield stress, and hardening coefficients using different mechanical constitutive models, parameter identification must be implemented using inverse analysis. In the present study, a new approach combining the finite-element method and an optimisation procedure is proposed for determining the constitutive parameters of urea-formaldehyde micro capsules, in which three types of elastic-plastic constitutive models are considered: the power-law hardening model, the elastic-perfectly plastic model, and the elastic-perfectly plastic model with linear hardening. A nonlinear optimisation procedure is applied to determine the minimum of the multivariable objective function, which is defined as the norm of the difference between the numerical and experimental results. The efficiency and robustness of the proposed method are verified with different initial values and numbers of elements. The force-displacement curves from a numerical simulation show good agreement with the experimental data, indicating that the proposed approach and the mechanical parameters determined are reliable.
A general linear superposition theory for finite-element formulation is proposed for airfoil pitching, heaving, and control surface oscillations. It divides the solution into time-independent and the first-harmonic su...
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A general linear superposition theory for finite-element formulation is proposed for airfoil pitching, heaving, and control surface oscillations. It divides the solution into time-independent and the first-harmonic subsolutions. The crucial part of the formulation is the finite-element treatment of the wake behind the trailing edge, which is modelled through velocity potential difference rather than the conventional tangential velocity difference. The proper numerical form of the unsteady Kutta condition is discussed in detail. To avoid any numerical blockage effect, a parametric study of finite-element mesh sizes is also conducted. finally, the unsteady aerodynamic forces obtained are employed to calculate flutter speed with a new iteration scheme. Both the unsteady aerodynamic forces and the flutter speed are compared with either numerical or know theoretical solutions. The agreement is good.
The paper presents a new iterative finite-element model for the analysis of the thermal interference between a three-phase system of high voltage cables and heat pipelines buried in close proximity. A triangular forma...
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The paper presents a new iterative finite-element model for the analysis of the thermal interference between a three-phase system of high voltage cables and heat pipelines buried in close proximity. A triangular formation of 110 kV cables and a pair of polyurethane insulated steel heat pipes are considered as a characteristic real-life example in authors' country. The maximum allowable load magnitudes for cables in winter weekdays have been determined for various distances between cables and pipes. The proposed mathematical model takes into account the effects of conduction, and the heat exchange by convection and radiation on the pavement surface. In order to adequately model the convective heat transfer from the water in motion an iterative approach is elaborated based upon the properties of the Nusselt number. It was shown that the maximum allowable magnitudes of load current of cables should be decreased for app. 6% if the distance between the cables and the adjacent pipe is 3 m, which is the minimum distance usually tolerated in practice in authors' country.
In this paper, we will give an h-version finite-element method for a two-dimensional nonlinear elasto-plasticity problem. A family of admissible constitutive laws based on the so-called gauge-function method is introd...
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In this paper, we will give an h-version finite-element method for a two-dimensional nonlinear elasto-plasticity problem. A family of admissible constitutive laws based on the so-called gauge-function method is introduced first, and then a high-order h-version semidiscretization scheme is presented. The existence and uniqueness of the solution for the semidiscrete problem are guaranteed by using some special properties of the constitutive law, and finally we will show that as the maximum element size h --> 0, the solution of the semidiscrete problem will converge to the solution of the continuous problem. The high-order h-version discretization scheme introduced here is unusual. If the partition of the spatial space only has rectangles or parallelograms involved, then there would not be any limit on the element degree. However, if the partition of the spatial space has some triangular elements, then only certain combinations of finite-element spaces for displacement and stress functions can be used. The discretization scheme also provides a useful idea for applications of hp-version or high-order h-version finite-element methods for two-dimensional problems where the elasto-plastic body is not a polygon, such as a disk or an annulus.
We propose a new approach to the investigation of the thermomechanical states in layered plastically deformed heat-sensitive bodies of any geometric shape with arbitrary orientation of the interfaces between the layer...
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We propose a new approach to the investigation of the thermomechanical states in layered plastically deformed heat-sensitive bodies of any geometric shape with arbitrary orientation of the interfaces between the layers. The proposed approach is based on the formulation of the nonstationary problem of heat conduction, problem of the theory of plastic nonisothermal flow, computational schemes of the finite-element method, and the corresponding software. We also study the thermomechanical behavior of a two-layer sphere under the conditions of rapid cooling from its initial uniform temperature.
One of the most prolific areas of fluid mechanics applications in general and nanofluid applications in particular, is boundary layer flows. In the recent past, a great many of these applications, have been limited to...
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One of the most prolific areas of fluid mechanics applications in general and nanofluid applications in particular, is boundary layer flows. In the recent past, a great many of these applications, have been limited to one-term similarity approximations. This work however, was concerned with numerically approximating nonsimilar fluid boundary layer transfer. Nonsimilar fluid boundary layer problems are more generally valid and are more prevalent industrially. In this research, the objective was to establish and advance numerically the first application of the finite-element method (FEM) to the solution of a set of nonsimilar boundary layer-derived infinite series ordinary differential equations (ODEs). Thus, this work emphasizes an FEM technique devised and used for a class of nonsimilar boundary layer-derived ODEs. The motivation is to improve and complement the numerical heat transfer literature regarding an FEM technique that may be applied to solve a coupled system of nonsimilar boundary layer-derived infinite series ODEs. The analysis obtained results that correlate very well with highly accurate benchmarked results for heat transfer and universal velocity functions. An examination of the convergence of the FEM is also shown and discussed. The results indicate that the FEM is a very robust technique for nonsimilar boundary layer infinite series differential equations. (C) 2020 Elsevier Ltd. All rights reserved.
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