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Genetic algorithms in active vibration reduction problem

100%

Grochowina M. , Tyburski K.

Vibrations in Physical Systems

2022

tom Vol. 33, nr 2

art. no. 2022219

The design of active vibration reduction systems usually consists in selecting a control algorithm and determining the value of its settings. This article presents the results of research on the concept of using genetic algorithms to induce the settings of control systems. To test the concept, a simple pulse-excited flat bar model was selected. The vibrations were suppressed by the PID controller. Genetic algorithms with two types of crossover were tested - arithmetic and uniform. As a result, the settings for the PID controller were obtained, enabling effective reduction of vibrations in a short time.

Analysys of the impact of disturbance on the arteriovenous fistula state classification

100%

Grochowina M. , Leniowska L.

Annals of Computer Science and Information Systems

2017

tom Vol. 13

51--55

The quality of data sets used in the classification process has a significant impact on the outcome. The noise contained in the input data depending on the nature and intensity may have a different effect on the classification result. This paper presents the results of research on the quality and reliability of arterio-venous fistula classification based on the signal recorded under controlled disturbance conditions and in the model of artificial disturbations. Typical environmental noise that may occur when the acoustic signal produced by the fistula was recorded and it is used as a disturbance. Its influence on the features extraction process and on the result of the fistula assessment was determined. Finally, a relationship between the intensity of the disturbances and the degree of shifting of the classification result to the pathological state of the fistula was demonstrated

Vibration reduction assessment of layered acoustic metamaterial

80%

Świrk P. , Żyłka W. , Leniowska L. , Grochowina M.

Vibrations in Physical Systems

2022

tom Vol. 33, nr 2

art. no. 2022221

Acoustic meta-materials offer an approach to reducing the vibration and noise transmission through layered panels. In this paper, the investigation of constructed meta-material for reduction of low-frequency vibration and noise is a major concern. The key concept underlying this approach is to construct the metamaterial as a highly-distributed system of tuned point masses that introduce instead of low resonance frequency one or more bands of higher frequency. They can be then successfully damped with passive methods. Using the modes method, a metamaterial system with distributed point masses integrated into the honeycomb core was designed to be a representative layered panel. To determine the dynamic response of the global sandwich panel, the metamaterial system was tested for 70 Hz and 120 Hz excitation. The obtained results confirm the possibility of tuning the considered layered meta-material to the excitation frequency and shifting low frequencies towards higher frequencies.

Analysis of the possibility of mechanical devices supervision based on the measurement of the vibration level and SVM classifiers

80%

Schossler R. , Grochowina M. , Leniowska L.

Vibrations in Physical Systems

2022

tom Vol. 33, nr 3

art. no. 2022316

This paper presents the concept of diagnosing the technical condition of mechanical devices. The test is based on a non-invasive vibration analysis technique combined with the use of artificial intelligence method. The object of the research is an electric motor for which vibrations were recorded by a vibration sensor based on four 3-axis digital accelerometers and MPU-6050 gyroscopes. The effectiveness of classification methods using the two-class and one-class classification was compared. It has been shown that the use of an incomplete pattern of the vibration model and a single-class classifier allows for effective detection of anomalies in the operation of an induction motor. Satisfactory classification efficiency was achieved, despite the limitation of the teaching set only to the information obtained during the correct operation of the device. The described method is universal and can be used to diagnose the technical condition of many different types of technical devices.