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

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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

Design of control system for active vibration suppression of trapezoidal plate

100%

Mierzejewski K. , Leniowska L.

tom Vol. 30, nr 1

art. no. 2019132

An active vibration control system is proposed for suppressing the small amplitude plate vibration. The structure under study is a vibrating trapezoidal plate, having a constant thickness, to which MFC (Micro Fiber Composite) actuator is bonded. It was assumed, that the plate clamped at one edge is excited by a uniform periodic force generated by a loudspeaker. The control problem lies in using MFC actuator to reduce the plate vibrations. For the system under consideration the mathematical model obtained on the base of parametric identification method is constructed. This part of the research was done with the help of Polytec laser vibrometer. The apparatus is highly advanced tool that allows measurement of vibration of examined structure. With transfer function model obtained in identification process, using Matlabs Identification Toolbox, feedback control laws was created for changing response of the system in desired way. There are many ways to model controller having mathematical model of the object. In this article, authors propose approach to design an effective controller for vibration suppression of a trapezoidal plate with the use of the pole placement method in graphical SISOTool environment. This article describes concept, results of simulation tests and implementation for the designed controller.

Active vibration control of pipe-shaped robot arm

80%

Peter M. A. , Leniowska L. , Grochowina M.

tom Vol. 72, iss. 4

389--402

Robotic systems, because of their construction, are susceptible to vibrations that significantly affect their accuracy. Consequently, many efforts are made to eliminate vibrations and stabilize the structure as effectively as possible through the use of various solutions. This article presents the results of research on the use of piezoelectric elements- micro fiber composite (MFC) to reduce vibrations in a thin-walled tube, serving as a model of a lightweight robot arm. The aim of the research is to develop an effective method for vibration cancelation of considered arm model. In our approach, MFC elements were used to perform dual roles: as sensors and actuators. The object model was obtained based on measurements taken on a laboratory stand using an acquisition card and the xPC Target (Matlab) environment. Based on the obtained data, an ARX-type model was developed, and an optimal controller was selected for application in the designed active vibration reduction system. The article includes the results of tests carried out for several different vibration-inducing signals, confirming the effectiveness of the applied vibration-reduction method.

Vibration reduction assessment of layered acoustic metamaterial

80%

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

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.