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1

Comparison of Methods for Measuring Reverberation Time

Melnyk M., Kernytskyy A., Lobur M.

Machine Dynamics Research

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2018

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Vol. 42, No. 2

27--34

EN

The article presents the results of an experimental evaluation of the reverberation time of the lecture auditorium in the Lviv Polytechnic National University. For their further analysis, a sub-system of batch processing of audio ﬁles with a registered response of the room for excited impulse noise has been developed. To determine the bypass signal, Schroeder method was used, and the least squares method was improved by pre-processing of the signal using the MM method. The inﬂuence of the number of neighboring points of the MM method on the accuracy of the reverberation time by the least squares method is investigated. A comparison of the Schroeder method and the least squares method is made, which makes it possible to establish that Schroeder method is more precise. The average error of this method for 6 experiments against the Dirac system was 0.02 sec, whereas for the least squares method it was 0.06 seconds. The developed subsystem of the batch analysis of the registered response of the premises for pulsed noise makes it possible to increase the speed and efﬁciency of processing the results of experiments.

2

Development of СAD Structure for Design of Aerostatic Complex

Melnyk M., Kernytskyy A., Stefanskyy A.

Machine Dynamics Research

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2013

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Vol. 37, No. 3

61-65

EN

To solve the problem of AC aerodynamically shaped envelope design the integrated system of design was developed that allows minimizing human involvement in routine operations of modeling and calculation of design parameters.

3

Formalization of Location and Spacing Tasks Modern Methods of Design

Chura I., Kernytskyy A.

Machine Dynamics Problems

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2007

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Vol. 31, No. 3

15-24

EN

Tasks of optimal location and spacing of geometric objects arising during material cutting, animation, design of PCBs, design of plans of both habitual and industrial areas, location of equipments and loads and design of economic processes belongs to the class of the abovementioned problems. Therefore, the problem of ES development for the location and spacing problems solution is vital. Interest to the location and spacing tasks solution is determined by the wide spectrum of practical applications from the one side and by the complication and no triviality of the development of mathematical models vital for their adequate description. Regardless the variety of such problems, all of them include the formulation: it is necessary to locate the geometric objects in the given region taking into account terms and limitations so that achieved value of an efficiency function are the nearest ones to the optimum. The tasks of location and spacing of flat objects depending on their application domain are classified in the paper. On the basis of the conducted analysis of practical problems mathematical formalization is presented. As a result of analysis of the known practical problems of location and spacing their similarity by input an output data is distinguished. All formalized problems are joined by main properties: a) there is questions about location of geometric objects of arbitrary form in the regions of arbitrary geometric form, b) each of problems is formalized, at least verbally, as the problem of mathematical programming. In other words, a problem appears as some terms that are limitations on the parameters of placing of objects at implementation of which it is necessary to achieve put objective. Under achievement of purpose the receipt of the best quality or optimum quantity is understood, that are expressed by correlations and relied on the parameters of placing of objects. It is known, that such correlations in the mathematical programming are named functions or functions of quality having a special purpose.

4

Educational System for Studying Numerical Methods Application in Engineering Courses

Karkulyovskyy V., Kernytskyy A., Motyka I., Karkulyovskyy B.

Machine Dynamics Problems

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2007

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Vol. 31, No. 3

44-50

EN

Development of society rises before specialists in the field of organization of education and teachers at Universities new tasks. One of main reasons of change of paradigm of education consists in penetration of IT in all spheres of human activity. The increase of efficiency of educational process can be achieved by introduction of computer methods of teaching. There is the necessity of application of numeral methods for the decision of the concrete applied problems studying a row of different engineering disciplines. Therefore it is necessary to know the features of realization and application of these methods. The developed educational automated system is created for this purpose. Realization of new pedagogical technologies is impossible without the effective use of computer from auxiliary tools to basic at distant learning. The permanent increase of volume of information which must be independently mastered by student requires the intensive and rational use of electronic educational methods. Students which systematically and independently work with a computer, study to select and systematize information, draw conclusions, adapt themselves quickly under new conditions. The automated subsystem for conducting of laboratory sessions in the frame of "Numerical methods" course is developed. The purpose of the subsystem is to deep the knowledge of methods. The system has user friendly interface, allows estimating level of students knowledge and conduct laboratory sessions of different kinds.