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Simulation-based Evaluation of Frequency Response Analysis as a Diagnostic Tool for Deformations of Windings in Power Transformers
Ivan Papa, 2020, master's thesis

Abstract: In this master’s thesis, we have established a model of a transformer winding. This model is based on the multi transmission line theory that allows us to model each turn of the winding separately. By using that approach, it was possible to calculate the frequency response of a winding in the required frequency range from 20 Hz to 2 MHz. The purpose of this simulation was to evaluate the frequency response analysis as a diagnostic tool for deformations of windings in power transformers. An evaluation was performed using sensitivity analysis of several parameters that indicate winding deformations. Finally, axial bending deformation was simulated and successfully diagnosed by applying the frequency response analysis.
Keywords: Power transformer, Frequency response analysis, Diagnostics, MTL model
Published: 03.11.2020; Views: 62; Downloads: 19
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Evaluation of the influence of the macro-environment on the social innovation activity of enterprises
Liliya Satalkina, Nestor Shpak, 2018, original scientific article

Abstract: Background: Nowadays the emphasis on social components in the general mainstream of innovation activity is one of the strongest grounds for the successful functioning and development of enterprises. In several countries, social innovation activity is becoming a product of business in general, with associated expectations regarding profit. Objectives: The goal of the article is to develop a toolkit for the evaluation of the influence of the macro-environment on the social innovation activity (SIA) of enterprises. Method: The methodology includes elements of theoretical and empirical research with the implementation of methods such as a literature review, all types of analysis, and methods of aggregation and integration. Questionnaires were used as a means of data collection. Results: The general methodological framework of diagnostics of the SIA macro-environment is distinguished. Based on a theoretical analysis of the SIA ecosystem and the experience of operating enterprises, the main factors of SIA macro-environment are determined. The general integrated index and its five-level interpretational model are proposed as a measure for the evaluation of the SIA macro-environment. Conclusion: The results presented provide data necessary for the argumentation of SIA strategy and tactics, as well as investment policy in this sphere.
Keywords: enterprise, social innovation activity, diagnostics, macro-environment, factors
Published: 07.05.2018; Views: 621; Downloads: 230
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Automated diagnostics of damage to an aluminum alloy under the conditions of high-cycle fatigue
P. O. Maruščak, Igor Konovalenko, Mykhailo Karuskevich, Vladimir Gliha, Tomaž Vuherer, 2013, original scientific article

Abstract: An identification and quantitative analysis of the deformation relief of the aluminium alloy for an aircraft construction based on a digital-image processing has been performed. The behaviour of defects has been assessed on the basis of diagnostics results for individual stages of the deformation process. It has been established that the individual stages of the damage-accumulation process are characterised by the values of integral-image parameters. Based on the consecutive processing of the data on the surface cyclic deformation, the main regularities of the propagation of defects have been found. Theoretical preconditions have been substantiated and experimental results obtained.
Keywords: fatigue, surface, digital image, diagnostics, accumulated damage, defect propagation, evaluation
Published: 10.07.2015; Views: 800; Downloads: 69
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Using of acoustic models in mechanical diagnostics
Mateja Ploj Virtič, Boris Aberšek, Uroš Župerl, 2008, original scientific article

Abstract: This paper presents an acoustical model for control and diagnostics of single stage gear wheels. The model is based on various methods and procedures that as a result provide information about the generatorćs condition, the gear in particular. The acoustical model is part of a complex system that units' different models to meet diagnostics of single stage gear wheels as precise as possible. Using the adaptive FIR filter, acoustical model enables the calculation of impulse response for different notch lengths between 0 and ac. The acoustical model consists of digital FIR filter, modified by LMS algorithm, used to calculate impulse responses in non-linear systems, the model for the calculation of any impulse response and the frequency analysis with the use of FFT for the simulation of frequency spectrums. Frequency spectrum of the simulated sound signal enables an analysis of the error that can be used for calculating the remaining service life and/or determining the control cycle of maintenance.
Keywords: mechanical fault diagnostics, acoustic models, impulse response, adaptive algorithm
Published: 31.05.2012; Views: 1080; Downloads: 25
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Crack identification in gear tooth root using adaptive analysis
Aleš Belšak, Jože Flašker, 2007, original scientific article

Abstract: Problems concerning gear unit operation can result from various typical damages and faults. A crack in the tooth root, which often leads to failure in gear unit operation, is the most undesirable damage caused to gear units. This article deals with fault analyses of gear units with real damages. A laboratory test plant has been prepared. It has been possible to identify certain damages by monitoring vibrations. In concern to a fatigue crack in the tooth root significant changes in tooth stiffness are more expressed. When other faults are present, other dynamic parameters prevail. Signal analysis has been performed also in concern to a non-stationary signal, using the adaptive transformation to signal analysis.
Keywords: machine elements, gears, fatigue crack, fault detection, vibrations, adaptive signal analysis, engineering diagnostics
Published: 31.05.2012; Views: 1469; Downloads: 60
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