=Paper=
{{Paper
|id=Vol-2547/paper16
|storemode=property
|title=Methods of using mobile Internet devices in the formation of the general scientific component of bachelor in electromechanics competency in modeling of technical objects
|pdfUrl=https://ceur-ws.org/Vol-2547/paper16.pdf
|volume=Vol-2547
|authors=Yevhenii O. Modlo,Serhiy O. Semerikov,Stanislav L. Bondarevskyi,Stanislav T. Tolmachev,Oksana M. Markova,Pavlo P. Nechypurenko
|dblpUrl=https://dblp.org/rec/conf/aredu/ModloSBTMN19
}}
==Methods of using mobile Internet devices in the formation of the general scientific component of bachelor in electromechanics competency in modeling of technical objects==
217 Methods of using mobile Internet devices in the formation of the general scientific component of bachelor in electromechanics competency in modeling of technical objects Yevhenii O. Modlo1[0000-0003-2037-1557], Serhiy O. Semerikov2,3,4[0000-0003-0789-0272], Stanislav L. Bondarevskyi3[0000-0003-3493-0639], Stanislav T. Tolmachev3[0000-0002-5513-9099], Oksana M. Markova3[0000-0002-5236-6640] and Pavlo P. Nechypurenko2[0000-0001-5397-6523] 1 Kryvyi Rih Metallurgical Institute of the National Metallurgical Academy of Ukraine, 5, Stephana Tilhy Str., Kryvyi Rih, 50006, Ukraine eugenemodlo@gmail.com 2 Kryvyi Rih State Pedagogical University, 54, Gagarina Ave., Kryvyi Rih, 50086, Ukraine semerikov@gmail.com, acinonyxleo@gmail.com 3 Kryvyi Rih National University, 11, Vitaliy Matusevych Str., Kryvyi Rih, 50027, Ukraine parapet1979@gmail.com, stan.tolm@gmail.com, markova@mathinfo.ccjournals.eu 3 Institute of Information Technologies and Learning Tools of NAES of Ukraine, 9, M. Berlynskoho Str., Kyiv, 04060, Ukraine Abstract. An analysis of the experience of professional training bachelors of electromechanics in Ukraine and abroad made it possible to determine that one of the leading trends in its modernization is the synergistic integration of various engineering branches (mechanical, electrical, electronic engineering and automation) in mechatronics for the purpose of design, manufacture, operation and maintenance electromechanical equipment. Teaching mechatronics provides for the meaningful integration of various disciplines of professional and practical training bachelors of electromechanics based on the concept of modeling and technological integration of various organizational forms and teaching methods based on the concept of mobility. Within this approach, the leading learning tools of bachelors of electromechanics are mobile Internet devices (MID) – a multimedia mobile devices that provide wireless access to information and communication Internet services for collecting, organizing, storing, processing, transmitting, presenting all kinds of messages and data. The authors reveals the main possibilities of using MID in learning to ensure equal access to education, personalized learning, instant feedback and evaluating learning outcomes, mobile learning, productive use of time spent in classrooms, creating mobile learning communities, support situated learning, development of continuous seamless learning, ensuring the gap between formal and informal learning, minimize educational disruption in conflict and disaster areas, assist learners with disabilities, improve the quality of the communication and the management of institution, and maximize the cost-efficiency. ___________________ Copyright © 2020 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0). 218 Bachelor of electromechanics competency in modeling of technical objects is a personal and vocational ability, which includes a system of knowledge, skills, experience in learning and research activities on modeling mechatronic systems and a positive value attitude towards it; bachelor of electromechanics should be ready and able to use methods and software/hardware modeling tools for processes analyzes, systems synthesis, evaluating their reliability and effectiveness for solving practical problems in professional field. The competency structure of the bachelor of electromechanics in the modeling of technical objects is reflected in three groups of competencies: general scientific, general professional and specialized professional. The implementation of the technique of using MID in learning bachelors of electromechanics in modeling of technical objects is the appropriate methodic of using, the component of which is partial methods for using MID in the formation of the general scientific component of the bachelor of electromechanics competency in modeling of technical objects, are disclosed by example academic disciplines “Higher mathematics”, “Computers and programming”, “Engineering mechanics”, “Electrical machines”. The leading tools of formation of the general scientific component of bachelor in electromechanics competency in modeling of technical objects are augmented reality mobile tools (to visualize the objects’ structure and modeling results), mobile computer mathematical systems (universal tools used at all stages of modeling learning), cloud based spreadsheets (as modeling tools) and text editors (to make the program description of model), mobile computer-aided design systems (to create and view the physical properties of models of technical objects) and mobile communication tools (to organize a joint activity in modeling). Keywords: mobile Internet devices, bachelor of electromechanics competency in modeling of technical objects, a technique of using mobile Internet devices in learning bachelors of electromechanics. 1 Introduction In previous work [13] it has been established that despite the fact that mobile Internet devices (MID) are actively used by electrical engineers, the methods of using them in the process of bachelor in electromechanics training [4] is considered only in some domestic scientific studies. The article [13] highlights the components of the methods of using MID in the formation of the ICT component of the competence of the bachelor in electromechanics in modeling of technical objects [7; 8], providing for students to acquire basic knowledge in the field of Computer Science and modern ICT and skills to use programming systems, math packages, subroutine libraries, and the like. For processing tabular data, it was proposed to use various freely distributed tools that do not significantly differ in functionality, such as Google Sheets, Microsoft Excel, for processing text data – QuickEdit Text Editor, Google Docs, Microsoft Word. For 3D- modeling and viewing the design and technological documentation, the proposed comprehensive use of Autodesk tools in the training process. 219 According to the model of the use of mobile Internet devices in the formation of the competence of the bachelor in electromechanics in the modeling of technical objects [6], it is need to develop the methods of using mobile Internet devices in the formation of the general scientific component of the competence of the bachelor in electromechanics in the modeling of technical objects. To achieve this goal, the following tasks must be solved: 1. Identify the leading mobile software tools for the development of competence in applied mathematics and illustrate their use in the academic disciplines “Higher Mathematics” and “Computing Engineering and Programming”. 2. Identify the leading mobile software tools for the development of competences in fundamental sciences and illustrate their use in academic disciplines “Higher Mathematics”, “Theoretical Mechanics and Electrical Machines”. 2 Results of the research 2.1 Use of mobile Internet devices in the formation of competence in applied mathematics The formation of such a general scientific component of the competence of the bachelor in electromechanics in the modeling of technical objects, as the competence in applied mathematics, involves understanding students of the basic facts, concepts, principles of applied mathematics; mastering the methods of system analysis, construction and research of models of applied problems using the modern ICT tools, establishing their adequacy to real processes and phenomena; knowledge of numerical methods and algorithms for their implementation; determination of the correctness of the applied mathematics methods, the conditionality of the problems and the stability of the algorithms to the errors of the input data; selection and rational use of ready-made software (including computer mathematics systems) for computational experiments to verify hypothetical statements, etc. Formation of competence in applied mathematics occurs primarily in the study of such disciplines as “Higher Mathematics” and “Computer Science and Programming”. Thus, among the content modules of the “Higher Mathematics” one of the most important for the formation of competence in applied mathematics is module 1 “Elements of linear algebra”, which, in particular, considers the concepts of matrix, matrix types, actions on matrices and their properties, the notion and solution of a system of linear algebraic equations by the Gaussian and the matrix methods. In order to establish the interdisciplinary connections of the “Higher Mathematics” and “Computer Science and Programming”, it is expedient to consider similar models that are investigated by various means. Thus, before implementing the polynomial model of the approximation of the function of one variable by means of Visual Basic for Application in the third content module of the “Computer Engineering and Programming” it is expedient to consider it in practical lesson on the academic discipline “Higher Mathematics” in the matrix form, which students mastered in module 1 “Elements of linear algebra”. 220 Output data for constructing a model is a value from the table of the form: xexp yexp x1 y1 x2 y2 ... ... xi yi ... ... xn yn The polynomial expression should be written in the form y = apxp + ap–1xp–1 + ... + a2x2 + a1x + a0 Here n – is the number of pairs of values of the form (x; y) in the table, and p – is the order of the polynomial (p << n). After substituting each value from a table into a polynomial, we obtain a system of n linear algebraic equations with p+1 unknown: = + +⋯+ + + ⎧ ⎪ ⎪ = + +⋯+ + + ⋯ ⎨ = + +⋯+ + + ⎪ ⎪ ⋯ ⎩ = + +⋯+ + + The main matrices that characterize the system are: A – is a matrix column of unknown coefficients of the polynomial: ⎡ ⎤ ⎢ ⋯ ⎥ =⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎣ ⎦ X – the main matrix of the system: ⎡ ⋯ 1⎤ ⎢ ⋯ 1⎥ ⎢ ⋯⎥ = ⎢⋯ ⋯ ⋯ ⋯ ⋯ ⎥ ⎢ ⋯ 1⎥ ⎢⋯ ⋯ ⋯ ⋯ ⋯ ⋯⎥ ⎣ ⋯ 1⎦ 221 Y – is a matrix column of values: ⎡ ⎤ ⎢⋯⎥ = ⎢ ⎥ ⎢ ⎥ ⎢⋯⎥ ⎣ ⎦ A shortened system can be written as a matrix equation: Y = XA The direct solution of such system by methods considered in the first module is impossible due to the fact that the number of equations is greater than the number of unknowns. The same can be said about solving the matrix equation: finding a matrix inverse to the matrix X, is impossible because matrix X is not square. To get out of this dead end, we suggest students apply the property of a transposed matrix, namely: the product of a transposed matrix on the output is a square matrix, so we apply this property to both parts of the matrix equation: XTY = XTXA The resulting equation contains a new matrix – XT, which is a transposed matrix X. Using the associativity properties of multiplication of matrices, we obtain the following equivalent equation: (XTX)A = XTY It corresponds to the normal system of linear algebraic equations, for solving which one can use any of the mastered methods – Cramer’s rule, Gaussian elimination or matrix inversion. To use the latter, we make a left multiplication of both parts of the matrix equation on the matrix inversed to the product XTX: (XTX)–1(XTX)A = (XTX)–1XTY Get the next equivalent equation: IA = (XTX)–1XTY, where I – is an identity matrix of dimension (p+1, p+1): A = (XTX)–1XTY To find the solution, we first suggest using the traditional methods of “manual” solution in order to make sure that the time spent on such work is incommensurate with the time spent on the mathematical description of the model. It pushes for the use of ICT. For matrix models we are propose an electronic spreadsheets. Google Sheets provides to students and teachers the opportunity to put together experimental data and corresponding formulas. 222 To do this, make a spreadsheet accessible to all students in the academic group and invite each of them to fill in a line corresponding to the student number in the group’s journal with a pair “weight – height”. To select a polynomial order, we visualize the entered values and suggest justification of the choice. As a result of the discussion, we agree with the assumption that the line to be held at the smallest distance from all points can be a parabola, so our model will have the quadratic form y = a2x2 + a1x + a0. Accordingly, it is necessary to construct the matrix X from the elements of the column xexp in the second, first and zero degrees, and the matrix Y – from the elements of the column yexp. The XT matrix is constructed using the transpose function, giving it the parameter range of the values of the matrix X (E3:G32), and the products of XTX and XTY – by calling mmult(M3:AP5;E3:G32) and mmult(M3:AP5;I3:I32) respectively. We find the inverse to the XTX matrix with a minverse(M8:O10) call and make the left multiplication of it to the XTY matrix by calling mmult(M13:O15;Q8:Q10). As a result we obtain A, the matrix of polynomial coefficients (fig. 1). Fig. 1. Mobile Internet device while working with the model on higher mathematics classes In fig. 1 shows an updated graph of the ratio of weight and height of students, where the approximated growth values were added to the experimental points, calculated using the formula ycalc = -0,0148x2 + 2,3669x + 87,4835. The simulation results make it possible to draw an important conclusion that this model can be simplified to linear without losing adequacy. Since the factor of the second power x does not make a significant contribution to the calculated value of growth; therefore, the ratio of weight and height of students can be described not parabolic, but linear dependence. Such task can be offered for self-study. The considered algorithm of approximation can be illustrated also on the material of other modules. As shown in [12], the course of higher mathematics in technical universities traditionally ends with the Fourier transform and Fourier series as its partial 223 case. Considering the high practical significance of this topic for the further professional activity of future engineers-electromechanics, when studying the module 16 “Trigonometric series and their applications”, it is expedient for students to propose solution of the approximation problem by a fragment of a trigonometric series of sequence of points corresponding to the financial series. As a data source, we use the Google Finance online service, which provides the ability to export data to Google Sheets using the function =googlefinance("currency:usduah"; "close"; date(2013;1;9); date(2018;9;9)), the first parameter of which is the currency pair, “US dollar – Ukrainian hryvnia”, the second is the closing price of exchange rates of given currency pair, the third is start date and fourth is end date of the time interval l. The mathematical model of the renewal dependence is a cosine decomposition of an unknown function f(x) on an interval [0; l): ( )= , where n – is the harmonic number, N+1 – is the number of harmonics, an – is the Fourier coefficients. We put the measurement vector (value of the price) in the column matrix Y of the l×1 dimension. Due to find the column matrix A of the Fourier coefficients of by dimension (N+1)×1 we perform calculation A=(XTX)–1XTY, where X – is the matrix of the plan of the dimension l×(N+1), containing the cosine Fourier coefficients: Xxn = . As the value of the independent variable, apply the measurement number x = 0...l–1, and the harmonic number n =0...N. The call of the googlefinance function in cell A1 will provide two columns of values, the first of which will contain a date, and the second is the price. To determine the value of l we use the function of counting the number of column elements: count(A:A). We assign the number of harmonics manually: N = 30. To the first cell of the plan matrix X (N2) we enter the cos(pi()*N$1*$G2/$E$1) formula, which will be copied to all other cells of the X. The matrix column А are described by the formula – mmult(mmult(minverse(mmult(transpose(N2:AR1693);N2:AR1693));transpose(N2: AR1693));H2:H1693). To calculate the predicted values уcalc we use the scalar product of the line matrix to the column matrix A: mmult($N2:$AR2;$S$1696:$S$1726) to the J2 cell and distribute it to the entire range. To analyze the results we draw plots of currency values y obtained from Google Finance and approximated data ycalc (fig. 2). The function plot indicates that 30 harmonics in the general case is quite a satisfactory amount for the function estimation, but such amount is not enough to simulation of fast processes with a large amplitude of fluctuations. An example of such phenomena in the electromechanics are the modes of starting the engine, sharp loading of the load and short circuit. Discussion of this model in several classes provides an opportunity to evaluate its adequacy by forecasting future values of the currency pairs. So, it is advisable to compare the currency values for the dates that were not used when constructing the plan matrix, with the predicted values. To do this, we propose calculating at least three future values of the currency and compare them with the real ones. In fig. 3, the last three 224 values (1692-1694) were not used in constructing the plan matrix, but they reflect the tendency of the currency change. Fig. 2. Dynamics of currency pair “US dollar – Ukrainian hryvnia” and its approximation by Fourier series Fig. 3. Forecast of dynamics of currency pair “US dollar – Ukrainian hryvnia” for the period from September 10 till September 12, 2018 In studying the module 7 “Differential calculation of the function of several variables” it is expedient to consider the problem of finding the extremum of a convex function by a gradient descent method. To do this, you can return to the ratio of the two measured values x and y, considered in the first module of the model, but write down its solution using partial derivatives. The function of communication of these values (hypothesis) is written in the form h(x) = θ0 + θ1x, or ℎ( ) = ⃗ ⃗ = [ ] 1, 225 where ⃗ = – column matrix (vector-column) of unknown coefficients ⃗ , and 1 ⃗= – non-transposed element of the plan matrix. Let us construct a function of value, which depends on the parameters of the hypothesis: 1 ( , )= (ℎ( ) − ) . 2 The function plot has a single extremum (fig. 4). The gradient descent method is based on the fact that starting from a certain initial value of the vector ⃗ , we will take steps on the surface of the paraboloid in the direction of minimizing the function value, that is, the direction opposite to the gradient vector of the function: ∇ ( , ) = , . Fig. 4. Function plot (left) and its contour plot (right); the cross indicates the global minimum The partial derivatives of the function with the respect to the θ0 and θ1 are equal: 1 = (ℎ( ) − ), 1 = (ℎ( ) − ) , The algorithm of the gradient descent method will look: ⃗ = ⃗ − ∇ ( , ), where – descent speed. 226 The software implementation of this numerical method can be performed in mobile versions of Scilab [5], MATLAB or Octave. Thus, the function of the value of J can be realized through the scalar product of the defined vectors: function J = computeCostMulti(X, y, theta) m = length(y); J=1/(2*m)*(X*theta-y)'*(X*theta-y); end The number of iterations num_iters an additional parameter used when implementing the method: function [theta] = gradientDescentMulti(X, y, theta, alpha, num_iters) m = length(y); for iter = 1:num_iters temp=theta; n=size(X,2); s=zeros(n,1); for j=1:n for i =1:m s(j,1)=s(j,1)+(X(i,:)*theta-y(i))*X(i,j); end; end; temp=theta-alpha*(1/m)*s; theta=temp; end end As a result, we obtain the vector of the parameters ⃗ , and can visualize the results of the simulation (fig. 5). In the content module 9 “Definite and improper integrals” the competence in applied mathematics can be developed on example of the problem of building plot of electrical load. The corresponding code with teacher’s explanations can be offer in SageCell: #Output data data=[[1,6],[2,7],[3,7.5],[4,7.5],[5,7.5],[6,8],[7,8],[8,10],[9, 13],[10,15],[11,13.5],[12,13.5],[13,11],[14,12],[15,14],[16,11], [17,10], [18,12],[19,14],[20,14],[21,15],[22,13],[23,12],[24,7]] p=point((0,0)) S=vector([0,0,0]) # sums by the method of left and right rectangles, and the trapezoid method for i in range(len(data)-1): p += line([data[i], data[i+1]], color='red') 227 p += polygon([data[i], [data[i+1][0], data[i][1]], [data[i+1][0], 0], [data[i][0], 0], data[i]], color='lightblue') dt = data[i+1][0]-data[i][0] # integration step S += vector([data[i][1]*dt, data[i+1][1]*dt, (1/2)*(data[i][1]+data[i+1][1])*dt]) show(p, figsize=[4,5]) html("Daily electricity consumption calculated: