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Abstract

The objective of the article is to examine the approximative and adjustive uses of the verb dire, which is mostly regarded as an assertive and eventful verb; hence nonapproximative. Meanwhile, in many expressions, in an impersonal use, in negation when the subjunctive mode is used, in the conditional forms, its evidence value is weakened and the verb dire can express approximation. The study is situated in light of the enunciation theory, notably it refers to a notion of modalisation. The corpus was established on the basis of dictionaries, which are representative for normative uses, but we will refer as well to press texts, particularly interviews, where the verb say is frequently used as a marker of the position of the speaker.

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Authors and Affiliations

Katarzyna Kwapisz-Osadnik
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Abstract

This study discusses the cross-cultural re-conceptualization of the slogan ‘I’m lovin’ it’, popularized in Poland by a global fast-food restaurant chain, which occurs in the inter-linguistic transfer between English and Polish. The analytical framework for the study is provided by Cultural Linguistics and the Re-conceptualization and Approximation Theory. The analysis is based on proposals submitted by 45 translators asked to come up with a Polish equivalent of the slogan. The results indicate that because the semantic networks for the meaning of love do not overlap between English and Polish perfectly, attempts at the cross-cultural transfer of the slogan can be approached only as more or less accurate approximations of the original meaning constructed according to culture-specific norms, expectations, and attitudes.

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Authors and Affiliations

Jacek Tadeusz Waliński
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Abstract

The positive asymptotically stable continuous-time linear systems are approximated by corresponding asymptotically stable discrete-time linear systems. Two methods of the approximation are presented and the comparison of the methods is addressed. The considerations are illustrated by three numerical examples and an example of positive electrical circuit.

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Authors and Affiliations

Tadeusz Kaczorek
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Abstract

The main aim of the study was to determine the goodness of fit between the relaxation function described with a rheological model and the real (experimental) relaxation curves obtained for digital materials fabricated with a Connex 350 printer using the PolyJet additive manufacturing technology. The study involved estimating the uncertainty of approximation of the parameters of the theoretical relaxation curve. The knowledge of digital materials is not yet sufficient; their properties are not so well-known as those of metallic alloys or plastics used as structural materials. Intensive research is thus required to find out more about their behavior in various conditions. From the calculation results, i.e. the uncertainty of approximation of the relaxation function parameters, it is evident that the experimental curves coincide with the curves obtained by means of the solid model when the approximation uncertainty is taken into account. This suggests that the assumed solid model is well-suited to describe a real material.

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Authors and Affiliations

Stanisław Adamczak
Jerzy Bochnia
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Abstract

Wavelet transform becomes a more and more common method of processing 3D signals. It is widely used to analyze data in various branches of science and technology (medicine, seismology, engineering, etc.). In the field of mechanical engineering wavelet transform is usually used to investigate surface micro- and nanotopography. Wavelet transform is commonly regarded as a very good tool to analyze non-stationary signals. However, to analyze periodical signals, most researchers prefer to use well-known methods such as Fourier analysis. In this paper authors make an attempt to prove that wavelet transform can be a useful method to analyze 3D signals that are approximately periodical. As an example of such signal, measurement data of cylindrical workpieces are investigated. The calculations were performed in the MATLAB environment using the Wavelet Toolbox.

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Authors and Affiliations

Krzysztof Stępień
Włodzimierz Makieła
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Abstract

Size-dependent dynamic instability of cylindrical nanowires incorporating the effects of Casimir attraction and surface energy is presented in this research work. To develop the attractive intermolecular force between the nanowire and its substrate, the proximity force approximation (PFA) for small separations, and the Dirichlet asymptotic approximation for large separations with a cylinder-plate geometry are employed. A nonlinear governing equation of motion for free-standing nanowires – based on the Gurtin-Murdoch model – and a strain gradient elasticity theory are derived. To overcome the complexity of the nonlinear problem in hand, a Garlerkin-based projection procedure for construction of a reduced-order model is implemented as a way of discretization of the governing differential equation. The effects of length-scale parameter, surface energy and vacuum fluctuations on the dynamic instability threshold and adhesion of nanowires are examined. It is demonstrated that in the absence of any actuation, a nanowire might behave unstably, due to the Casimir induction force.

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Authors and Affiliations

Hamid M. Sedighi
Hassen M. Ouakad
Moosa Khooran
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Abstract

The basic objective of the research is to construct a difference model of the melt motion. The existence of a solution to the problem is proven in the paper. It is also proven the convergence of the difference problem solution to the original problem solution of the melt motion. The Rothe method is implemented to study the Navier–Stokes equations, which provides the study of the boundary value problems correctness for a viscous incompressible flow both numerically and analytically.
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Bibliography

[1] R. Lakshminarayana, K. Dadzie, R. Ocone, M. Borg, and J. Reese: Recasting Navier–Stokes equations. Journal of Physics Communications, 3(10), (2019), 13–18, DOI: 10.1088/2399-6528/ab4b86.
[2] S.Sh. Kazhikenova, S.N. Shaltaqov, D. Belomestny, and G.S. Shai- hova: Finite difference method implementation for Numerical integration hydrodynamic equations melts. Eurasian Physical Technical Journal, 17(33), (2020), 50–56.
[3] C. Bardos: A basic example of non linear equations: The Navier– Stokes equations. Mathematics: Concepts and Foundations, III (2002), http://www.eolss.net/sample-chapters/c02/e6-01-06-02.pdf.
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[11] N. Merazga and A. Bouziani: Rothe time-discretization method for a nonlocal problem arising in thermoelasticity. Journal of Applied Mathematics and Stochastic Analysis, 2005(1), (2005), 13–28, DOI: 10.1080/00036818908839869.
[12] T.A. Barannyk, A.F. Barannyk, and I.I. Yuryk: Exact solutions of the nonliear equation. Ukrains’kyi Matematychnyi Zhurnal, 69(9), (2017), 1180–1186, http://umj.imath.[K]iev.ua/index.php/umj/article/view/1768.
[13] N.B. Iskakova, A.T. Assanova, and E.A. Bakirova: Numerical method for the solution of linear boundary-value problem for integrodifferential equations based on spline approximations. Ukrains’kyi Matematychnyi Zhurnal, 71(9), (2019), 1176–91, http://umj.imath.[K]iev.ua/index.php/ umj/article/view/1508.
[14] S.L. Skorokhodov and N.P. Kuzmina: Analytical-numerical method for solving an Orr-Sommerfeld type problem for analysis of instability of ocean currents. Zh. Vychisl. Mat. Mat. Fiz., 58(6), (2018), 1022–1039, DOI: 10.7868/S0044466918060133.
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Authors and Affiliations

Saule Sh. Kazhikenova
1
ORCID: ORCID
Sagyndyk N. Shaltakov
1
ORCID: ORCID
Bekbolat R. Nussupbekov
2
ORCID: ORCID

  1. Karaganda Technical University, Kazakhstan
  2. Karaganda University E.A. Buketov, Kazakhstan
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Abstract

The article presents "-approximation of hydrodynamics equations’ stationary model along with the proof of a theorem about existence of a hydrodynamics equations’ strongly generalized solution. It was proved by a theorem on the existence of uniqueness of the hydrodynamics equations’ temperature model’s solution, taking into account energy dissipation. There was implemented the Galerkin method to study the Navier–Stokes equations, which provides the study of the boundary value problems correctness for an incompressible viscous flow both numerically and analytically. Approximations of stationary and non-stationary models of the hydrodynamics equations were constructed by a system of Cauchy–Kovalevsky equations with a small parameter ". There was developed an algorithm for numerical modelling of the Navier– Stokes equations by the finite difference method.
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Bibliography

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[3] P.M. Gresho: Incompressible fluid dynamics: some fundamental formulation issues. Annu. Rev. Fluid Mech., 23, Palo Alto, Calif., (1991), 413-453.
[4] R. Lakshminarayana, K. Dadzie, R. Ocone, M. Borg, and J. Reese: Recasting Navier–Stokes equations. J. Phys. Commun., 3(10), (2019), 13– 18, DOI: 10.1088/2399-6528/ab4b86.
[5] S.Sh. Kazhikenova, S.N. Shaltakov, D. Belomestny, and G.S. Shai- hova: Finite difference method implementation for numerical integration hydrodynamic equations melts. Eurasian Physical Technical Journal, 17(1), (2020), 50–56.
[6] O.A. Ladijenskaya: Boundary Value Problems of Mathematical Physics. Nauka, Moscow, 1973.
[7] Z.R. Safarova: On a finding the coefficient of one nonlinear wave equation in the mixed problem. Archives of Control Sciences, 30(2), (2020), 199–212, DOI: 10.24425/acs.2020.133497.
[8] A. Abramov and L.F. Yukhno: Solving some problems for systems of linear ordinary differential equations with redundant conditions. Comput. Math. and Math. Phys., 57 (2017), 1285–1293, DOI: 10.7868/ S0044466917080026.
[9] K. Yasumasa and T. Takahico: Finite-element method for three-dimensional incompressible viscous flow using simultaneous relaxation of velocity and Bernoulli function. 1st report flow in a lid-driven cubic cavity at Re = 5000. Trans. Jap. Soc. Mech. Eng., 57(540), (1991), 2640–2647.
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[12] T.A. Barannyk, A.F. Barannyk, and I.I. Yuryk: Exact Solutions of the nonliear equation. Ukrains’kyi Matematychnyi Zhurnal, 69(9), (2017), 1180–1186, http://umj.imath.kiev.ua/index.php/umj/article/view/1768.
[13] S. Tleugabulov, D. Ryzhonkov, N. Aytbayev, G. Koishina, and G. Sul- tamurat: The reduction smelting of metal-containing industrial wastes. News of the Academy of Sciences of the Republic of Kazakhstan, 1(433), (2019), 32–37, DOI: 10.32014/2019.2518-170X.3.
[14] S.L. Skorokhodov and N.P. Kuzmina: Analytical-numerical method for solving an Orr–Sommerfeld-type problem for analysis of instability of ocean currents. Zh. Vychisl. Mat. Mat. Fiz., 58(6), (2018), 1022–1039, DOI: 10.7868/S0044466918060133.
[15] N.B. Iskakova, A.T. Assanova, and E.A. Bakirova: Numerical method for the solution of linear boundary-value problem for integrodifferential equations based on spline approximations. Ukrains’kyi Matematychnyi Zhurnal, 71(9), (2019), 1176–1191, http://umj.imath.kiev.ua/index.php/ umj/article/view/1508.
[16] S.Sh. Kazhikenova, M.I. Ramazanov, and A.A. Khairkulova: epsilon- Approximation of the temperatures model of inhomogeneous melts with allowance for energy dissipation. Bulletin of the Karaganda University- Mathematics, 90(2), (2018), 93–100, DOI: 10.31489/2018M2/93-100.
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[22] M. Rosenfeld and M. Israeli: Numerical solution of incompressible flows by a marching multigrid nonlinear method. AIAA 7th Comput. Fluid Dyn. Conf.: Collect. Techn. Pap., New-York, (1985), 108–116.92.


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Authors and Affiliations

Saule Sh. Kazhikenova
1
ORCID: ORCID

  1. Head of the Department of Higher Mathematics, Karaganda Technical University, Kazakhstan
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Abstract

The overall acoustic echo of a submarine is greatly dependent on the conning tower. For enhancing the acoustic stealth performance of a submarine, it is necessary to research an innovative design scheme of the conning tower to reduce its target strength (TS). The aim of this work is to reduce the TS of a conning tower by varying its geometry and streamlining. The accuracy in modelling the acoustic scattering of a conning tower using the Kirchhoff approximation (KA) was validated, compared with finite element analysis (FEA). Several angular conning tower geometries were designed to analyze the effect of streamlining and the number of lateral facets on TS using the KA method. In consideration of the actual situation, the acoustic effect of backing medium was analyzed by compared water-filled elastic hulls with rigid hulls. From the observed TS calculation results, it is shown that the non-streamlined four lateral-facet conning tower geometries are optimal for acoustic stealth performance during the range of incidence angles from −10X to 10X, whereas the streamlined versions have better performance at incidence angles beyond this range. Furthermore, elastic hulls and rigid hulls provide similar spatial distribution regularities in monostatic configuration with the rigidity affecting the magnitude of the TS.
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Authors and Affiliations

Lin-Jiang Han
1
Hao Song
2
Chang-Xiong Chen
1
Xi-Rui Peng
3
Zi-Long Peng
1

  1. Jiangsu University of Science and Technology, Zhenjiang 212100, China
  2. Systems Engineering Research Institute, Beijing 100036, China
  3. China Ship Development and Design Center, Wuhan 430064, China
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Abstract

In this study, a new chemically modified cellulose polymer-capped ZnO nanopowder prepared by hydrothermal method using chemically modified cellulose polymer as capping agent was successfully reported. The structural characteristics of CMC-capped ZnO nanopowder was reported by FTIR, XRD, SEM and EDX studies. XRD results revealed crystallographic properties like crystal composition, phase purity and crystallite size of the prepared CMC-capped ZnO nanopowder and average size calculated by Debye Scherrer formula as 14.66 nm. EDX studies revealed that the presence of elemental compositions of capping agent in the nanopowder samples. The optical characterization of the CMC-capped ZnO nanopowder was studied using UV absorption (λmax = 303 nm) and PL spectroscopy (λex = 295 nm). The average crystal diameter and grain size were calculated by effective mass approximation formula and compared with XRD findings that agreed well and verified CMC capped ZnO with particle size of 193 nm. Thus, the promising optical characteristics shown by the synthesized CMC capped ZnO nanopowders exposes its potential usage in bio-medical fields.
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Bibliography

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Authors and Affiliations

R. Jagadeeswari
1
P. Selvakumar
2
ORCID: ORCID
V. Jeevanantham
2
ORCID: ORCID
R. Saravanan
1

  1. Department of Chemistry, KPR Institute of Engineering And Technology, Coimbatore-641407, Tamilnadu, India
  2. Department of Chemistry, Vivekanandha College of Arts And Sciences for Women, Tiruchengode-637205, Tamilnadu, India
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Abstract

In the paper a novel mathematical model of electromechanical actuator is presented. It is based on application of Hamiltonian equations in the description of electromechanical energy conversion. It results in employment of flux linkages as state variables in the state space equations. For simplicity only a 3-phase wye connected stator winding without a neutral wire is considered in detail. The procedure can be generalised to any number of phases. Topology-based approach is used in the model implementation. Procedures for evaluation of all quantities (currents, energy/coenergy, electromagnetic torque) present in model equations are described. Eddy currents and hysteresis phenolmenon are neglected in formulation of the model to enable application of state-space description.

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Authors and Affiliations

Wojciech Burlikowski
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Abstract

The paper presents an algorithm for the construction of an approximation of a highly nonlinear current-flux characteristic of a synchronous reluctance machine. Such an approximation is required in a Hamiltonian model of an electric machine and the constructed approximation is suited to be used in such a model. It employs a simplicial approximation based on irregular points sets in the spaces of currents and fluxes. The sets are constructed by the iterative insertion of new points. Initially the sets contain an arbitrarily small number of elements. The insertion is based on an approximation error calculation. Based on the sets containing possibly small number of elements, the proposed procedure leads to smooth and precise approximation. Due to the nonlinearity of the approximated characteristics, ambiguities can occur. A method for the triangulation refinement of the sets of currents and fluxes that eliminates them is also presented. In the paper, a reluctance machine model using the constructed approximation is described and compared with a model using the approximation based on regular sets.

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Authors and Affiliations

Wojciech Burlikowski
Zygmunt Kowalik
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Abstract

The article discusses the development of an approximation model of selected plastic and mechanical properties obtained from compression tests of model materials used in physical modeling. The use of physical modeling with the use of soft model materials such as a synthetic wax branch with various modifiers is a popular tool used as an alternative or verification of numerical modeling of bulk metal forming processes. In order to develop an algorithm to facilitate the choice of material model to simulate the behavior of real-metallic materials used in industrial production processes the induction of decision trees was used. First of all, the Statistica program was used for data mining, which made it possible to determine / find the relationship between the percentage of particular constituents of the model material (base material and modifiers) and yield strength, critical and maximum strain, and provide the opportunity to indicate the most important variables determining the shape of the stress – strain curve. Next, using the induction of decision trees, an approximation model was developed, which allowed to create an algorithm facilitating the selection of individual modifying components. The last stage of the research was verification of the correctness of the developed algorithm. The obtained research results indicate the possibility of using decision tree induction to approximate selected properties of modeling materials simulating the behavior of real materials, thus eliminating the need for costly and time-consuming experiments carried out on metallic material.

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Authors and Affiliations

M. Hawryluk
D. Wilk-Kołodziejczyk
K. Regulski
M. Głowacki
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Abstract

This paper presents a universal approximation of the unit circle by a polygon that can be used in signal processing algorithms. Optimal choice of the values of three parameters of this approximation allows one to obtain a high accuracy of approximation. The approximation described in the paper has a universal character and can be used in many signal processing algorithms, such as DFT, that use the mathematical form of the unit circle. One of the applications of the described approximation is the DFT linear interpolation method (LIDFT). Applying the results of the presented paper to improve the LIDFT method allows one to significantly decrease the errors in estimating the amplitudes and frequencies of multifrequency signal components. The paper presents the derived formulas, an analysis of the approximation accuracy and the region of best values for the approximation parameters.

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Authors and Affiliations

Józef Borkowski
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Abstract

The paper presents a new method of surface topology reconstruction from a white light interferogram. The method is based on interferogram modelling by complex exponents (Prony method). The compatibility of white light interferogram and Prony models has already been proven. Effectiveness of the method was tested by modelling and examining reconstruction of tilted and spherical surfaces, and by estimating the reconstruction accuracy.
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Authors and Affiliations

Anna Khoma
Jarosław Zygarlicki
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Abstract

BC (Black Carbon), which can be found in the atmosphere, is characterized by a large value of the imaginary part of the complex refractive index and, therefore, might have an impact on the global warming effect. To study the interaction of BC with light often computer simulations are used. One of the methods, which are capable of performing light scattering simulations by any shape, is DDA (Discrete Dipole Approximation). In this work its accuracy was estimated in respect to BC structures using the latest stable version of the ADDA (vr. 1.2) algorithm. As the reference algorithm the GMM (Generalized Multiparticle Mie-Solution) code was used. The study shows that the number of volume elements (dipoles) is the main parameter that defines the quality of results. However, they can be improved by a proper polarizability expression. The most accurate, and least time consuming, simulations were observed for IGT_SO. When an aggregate consists of particles composed of ca. 750 volume elements (dipoles), the averaged relative extinction error should not exceed ca. 4.5%.
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Authors and Affiliations

Krzysztof Skorupski
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Abstract

The paper presents the modelling measurement results of the load-displacement relation for scaffold stands and bracings. In the case of stands, there are two sections of curves, i.e. a straight-line and curvilinear section, and in the case of bracings, two straight line sections as well as one curvilinear section are distinguished. As a result of analyses, it is concluded that the sections which can be approximated by means of linear functions should be distinguished in graphs, if possible. On the one hand, this results from the evaluation methods of scaffold components. Nevertheless, the determination of elastic-linear scope of components’ operation is useful in engineering practice during computer calculations. Moreover, the method of determining an intersection point between functions, approximating tests results, along with analysis of the impact of polynomial degree, approximating the research results, on the time and effectiveness of the process of approximating functions selection, are all demonstrated in this article. The proposed method can prove useful in all science fields where curves obtained from any research (laboratory test, in situ test, numerical analysis) require approximation or replacement with a simpler description.

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Authors and Affiliations

E. Błazik-Borowa
J. Szer
A. Borowa
A. Robak
M. Pieńko
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Abstract

Seasonality is a function of a time series in which the data experiences regular and predictable

changes that repeat each calendar year. Two-stage stochastic programming model

for real industrial systems at the case of a seasonal demand is presented. Sampling average

approximation (SAA) method was applied to solve a stochastic model which gave a productive

structure for distinguishing and statistically testing a different production plan. Lingo

tool is developed to obtain the optimal solution for the proposed model which is validated

by Math works Matlab. The actual data of the industrial system; from the General Manufacturing

Company, was applied to examine the proposed model. Seasonal future demand

is then estimated using the multiplicative seasonal method, the effect of seasonality was

presented and discussed. One might say that the proposed model is viewed as a moderately

accurate tool for industrial systems in case of seasonal demand. The current research may

be considered a significant tool in case of seasonal demand. To illustrate the applicability of

the proposed model a numerical example is solved using the proposed technique. ANOVA

analysis is applied using MINITAB 17 statistical software to validate the obtained results.

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Authors and Affiliations

Asmaa A. Mahmoud
Mohamed F. Aly
Ahmed M. Mohib
Islam H. Afefy
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Abstract

The article proposes a model in which Diffusion Approximation is used to analyse the TCP/AQM transmission mechanism in a multinode computer network. In order to prevent traffic congestion, routers implement AQM (Active Queue Management) algorithms. We investigate the influence of using RED-based AQM mechanisms and the fractional controller PIγ on the transport layer. Additionally, we examine the cases in which the TCP and the UDP flows occur and analyse their mutual influence. Both transport protocols used are independent and work simultaneously. We compare our solution with the Fluid Flow approximation, demonstrating the advantages of Diffusion Approximation.
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Authors and Affiliations

Dariusz Marek
1
ORCID: ORCID
Adam Domański
1
ORCID: ORCID
Joanna Domańska
2
ORCID: ORCID
Jakub Szyguła
1
ORCID: ORCID
Tadeusz Czachórski
2
ORCID: ORCID
Jerzy Klamka
2
ORCID: ORCID
Katarzyna Filus
2
ORCID: ORCID

  1. Faculty of Automatic Control, Electronics and Computer Science, Department of Distributed Systems and Informatic Devices, Silesian University of Technology, Akademicka 16, 44-100 Gliwice, Poland
  2. Institute of Theoretical and Applied Informatics, Polish Academy of Sciences, Bałtycka 5, 44-100 Gliwice, Poland
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Abstract

In recent, modeling practical systems as interval systems is gaining more attention of control researchers due to various advantages of interval systems. This research work presents a new approach for reducing the high-order continuous interval system (HOCIS) utilizing improved Gamma approximation. The denominator polynomial of reduced-order continuous interval model (ROCIM) is obtained using modified Routh table, while the numerator polynomial is derived using Gamma parameters. The distinctive features of this approach are: (i) It always generates a stable model for stable HOCIS in contrast to other recent existing techniques; (ii) It always produces interval models for interval systems in contrast to other relevant methods, and, (iii) The proposed technique can be applied to any system in opposite to some existing techniques which are applicable to second-order and third-order systems only. The accuracy and effectiveness of the proposed method are demonstrated by considering test cases of single-inputsingle- output (SISO) and multi-input-multi-output (MIMO) continuous interval systems. The robust stability analysis for ROCIM is also presented to support the effectiveness of proposed technique.
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Authors and Affiliations

Jagadish Kumar Bokam
1
Vinay Pratap Singh
2
Ramesh Devarapalli
3
ORCID: ORCID
Fausto Pedro García Márquez
4
ORCID: ORCID

  1. Department of Electrical Electronics and Communication Engineering, Gandhi Institute of Technology and Management (Deemed to be University), Visakhapatnam, 530045, Andhra Pradesh, India
  2. Department of Electrical Engineering, Malaviya National Institute of Technology Jaipur, India
  3. Department of Electrical Engineering, BITSindri, Dhanbad, Jharkhand
  4. Ingenium Research Group, University of Castilla-La Mancha, Spain
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Abstract

In the paper approximate controllability of second order infinite dimensional system with damping is considered. Applying linear operators in Hilbert spaces general mathematical model of second order dynamical systems with damping is presented. Next, using functional analysis methods and concepts, specially spectral methods and theory of unbounded linear operators, necessary and sufficient conditions for approximate controllability are formulated and proved. General result may be used in approximate controllability verification of second order dynamical system using known conditions for approximate controllability of first order system. As illustrative example using Green function approach approximate controllability of distributed dynamical system is also discussed.
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Authors and Affiliations

Jerzy Klamka
1
ORCID: ORCID
Asatur Zh. Khurshudyan
2

  1. Department of Measurements and Control Systems, Silesian University of Technology, Gliwice, Poland
  2. Institute of Mechanics, NAS of Armenia
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Abstract

Bilevel programming problem is a non-convex two stage decision making process in which the constraint region of upper level is determined by the lower level problem. In this paper, a multi-objective indefinite quadratic bilevel programming problem (MOIQBP) is presented. The defined problem (MOIQBP) has multi-objective functions at both the levels. The followers are independent at the lower level. A fuzzy goal programming methodology is employed which minimizes the sum of the negative deviational variables of both the levels to obtain highest membership value of each of the fuzzy goal. The membership function for the objective functions at each level is defined. As these membership functions are quadratic they are linearized by Taylor series approximation. The membership function for the decision variables at both levels is also determined. The individual optimal solution of objective functions at each level is used for formulating an integrated pay-off matrix. The aspiration levels for the decision makers are ascertained from this matrix. An algorithm is developed to obtain a compromise optimal solution for (MOIQBP). A numerical example is exhibited to evince the algorithm. The computing software LINGO 17.0 has been used for solving this problem.

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Authors and Affiliations

Ritu Arora
Kavita Gupta
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Abstract

The study aimed to examine the use of Geomagnetic Anomaly Detection (GAD) to locate the buried ferromagnetic pipeline defects without exposing them. However, the accuracy of GAD is limited by the background noise. In the present work, we propose an approximate entropy noise suppression (AENS) method based on Variational Mode Decomposition (VMD) for detection of pipeline defects. The proposed method is capable of reconstructing the magnetic field signals and extracting weak anomaly signals that are submerged in the background noise, which was employed to construct an effective detector of anomalous signals. The internal parameters of VMD were optimized by the Scale–Space algorithm, and their anti-noise performance was compared. The results show that the proposed method can remove the background noise in high-noise background geomagnetic field environments. Experiments were carried out in our laboratory and evaluation results of inspection data were analysed; the feasibility of GAD is validated when used in the application to detection of buried pipeline defects.

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Authors and Affiliations

Haiyang Ju
Xinhua Wang
Tao Zhang
Yizhen Zhao
Zia Ullah
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Abstract

Shaft-stator rub and cracks on rotors, which have devastating effects on the industrial equipment, cause nonlinear and in some cases chaotic lateral vibrations. On the other hand, vibrations caused by machinery faults can be torsional in cases such as rub. Therefore, a combined analysis of lateral and torsional vibrations and extraction of chaotic features from these vibrations is an effective approach for rotor vibration monitoring. In this study, lateral and torsional vibrations of rotors have been examined for detecting cracks and rub. For this purpose, by preparing a laboratory model, the lateral vibrations of a system with crack and rub have been acquired. After that, a practical method for measuring the torsional vibrations of the system is introduced. By designing and installing this measurement system, practical test data were acquired on the laboratory setup. Then, the method of phase space reconstruction was used to examine the effect of faults on the chaotic behaviour of the system. In order to diagnose the faults based on the chaotic behaviour of the system, largest Lyapunov exponent (LLE), approximate entropy (ApEn) and correlation dimension were calculated for a healthy system and also for a system with rub and a crack. Finally, by applying these parameters, the chaotic feature space is introduced in order to diagnose the intentionally created faults. The results show that in this space, the distinction between the various defects in the system can be clearly identified, which enables to use this method in fault diagnosis of rotating machinery.

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Authors and Affiliations

Ali Hajnayeb
Kourosh Heidari Shirazi
Reza Aghaamiri

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