Wyniki wyszukiwania - Biblioteka Nauki

1

Application of weighted myriad filters to suppress impulsive noise in biomedical signals

100%

Pander T.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2004

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tom Vol. 8, No 2

199-216

EN

Biomedical signals are commonly recorded with many kinds of noise. One of these is a waveform of the electrical activity of muscles. This "natural" distortion is usually modelled with a white Gaussian noise. In order to suppress such noise a weighted myriad filter is applied. The weighted myriad filter belongs to a class of non-linear filters and requires knowledge about noise impulsiveness. An impulsive noise can be described with alpha-stable distributions. One objective of this paper is to apply alpha-stable distribution as a model of real-life muscle noise in ECG signals. The other objective of the paper is to apply a weighted myriad filter to suppress impulsive noise in biomedical (ECG) signals. The reference filters have been the Savitzky-Golay smoothing filter and the median filter. The obtained results have shown that alpha-stable distributions can be applied to model muscle noise and that a weighted myriad filter with a Chebyshev weighted function can effectively suppress such noise.

2

Multilevel time series complexity

88%

Kozarzewski B.

Journal of Applied Computer Science

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2011

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tom Vol. 19, nr 2

61-71

EN

A simple and fast algorithm to quantify time series complexity which follows newly developed nonparametric complexity measure of symbolic sequences is proposed. In order to get complexity measure over many time scales I suggest using wavelets multilevel decomposition of time series instead of coarse-graining. As an example multilevel complexity of series generated by Henon map, as well as some data downloaded from PhysioBank database: synthetic series, gait dynamics, and interbeat heart rate is calculated.

3

Wybrane standardy archiwizowania i transferu sygnałów biomedycznych

75%

Chodorowicz H. , Małek W.

Prace Przemysłowego Instytutu Elektroniki

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2003

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tom nr 148

121--140

PL

W artykule przedstawiono zestawienie kilku typowych, niezależnych od sprzętu formatów zapisu informacji w wielokanałowych systemach akwizycji sygnałów biomedycznych. Standaryzacja akwizycji i transferu informacji w tym obszarze jest niezbędna ze względu na konieczność współpracy i wymiany doświadczeń pomiędzy poszczególnymi grupami badawczymi poprzez łatwą wymianę danych i narzędzi. Podejście takie umożliwia: uniezależnienie sposobu zapisu informacji od producentów sprzętu medycznego, rozwój sieciowych systemów archiwizacji i wymiany danych, stworzenie platformy do łączenia się z innymi systemami szpitalnymi (np. HL7), stworzenie globalnych baz diagnostycznych. W końcowej części artykułu dokonano próby analizy porównawczej kilku najbardziej typowych standardów: ASTM, EBS, EDF, SIGIF i SCP-ECG.

EN

In this paper the short description of the most typical, device- and manufacturer-independent formats for archiving, exchange and analysis of biomedical signals in the polygraphic devices is presented. The standardisation of this area makes it possible to exchange and compare data between groups of researches, specialists and medical centres. The article describes some advantages of this standardisation such as: creating manufacturer-independent platform for data interchange, the development of network systems for archiving and data exchange, creating the platform for connecting between different medical centres (system HL7), access to the global data bases for diagnosis and analysis and to the common and unified software tools for signal processing and analysis. The comparison between such standards as: ASTM, EBS, EDF, SIGIF and SCP-ECG is described in the paper.

4

The use of EMG signal in human-machine interface

63%

Winiarski D.

Automatyka / Automatics

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2015

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tom Vol. 19, no. 2

47--61

EN

In this paper, the analysis and processing algorithms of EMG signals have been presented. The main purpose of the research was to verify the usefulness of EMG signals in controlling a bionic prosthesis or exoskeleton. The physiological nature of the EMG signal has been introduced. An original measurement system has been presented. Analysis of the time and frequency domains of the signal has been conducted to extract vital information that the signal carries. Methods of using the EMG signal as a control signal for devices that operate in a human-machine interface have been proposed. The result shows that a processed EMG signal can be used as a basis for a simple control system.

PL

W artykule przedstawiono analizę oraz propozycję algorytmów przetwarzania sygnału EMG. Głównym celem badań było sprawdzenie przydatności tego sygnału dla sterowania bioniczną protezą lub egzoszkieletem. W pracy został przedstawiony fizjologiczny charakter sygnału EMG. Przedstawiono autorski system pomiarowy. Przeprowadzono analizę sygnału w dziedzinie czasu i częstotliwości, aby wyodrębnić informacje, które niesie sygnał EMG. Zaproponowano sposoby wykorzystania sygnału EMG jako sygnał sterujący dla urządzeń, które działają w interfejsie człowiek-maszyna. Wyniki pokazują, że przetworzony sygnał EMG mogą być wykorzystywane jako podstawa dla prostego układu sterowania.

5

A new concept of filters for biomedical data processing needs

63%

Piskorowski J.

Biocybernetics and Biomedical Engineering

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2011

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tom Vol. 31, no. 1

27-37

EN

This paper presents a new class of filters that can meet biomedical signal processing needs. The paper is written in a technical note style, therefore, the proposed filters are not discussed with respect to a specific problem appearing in processing of a particular biosignal. The class of filters presented in this note should be treated as a new effective tool which can be applied to many cases of biomedical signals, especially when the processing time is very important. Nevertheless, a simple example of biomedical signal filtering is presented. This paper presents a new concept of continuous-time Butterworth filters whose parameters are varied in time. Thanks to the variation of the filter parameters, the time-varying filter response is considerably faster in comparison with the traditional time-invariant filters. Therefore, we can measure and register a lot of details in the initial stage of signal duration, which is not possible in the case of traditional time-invariant filters due to their long-lasting transients. Results verifying the effectiveness of the proposed filters are presented and compared to the traditional time-invariant filter structures.

6

Metody wyznaczania obwiedni amplitudowej wybranych sygnałów biomedycznych

63%

Wilk B.

Zeszyty Naukowe Politechniki Rzeszowskiej. Elektrotechnika

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2003

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tom z. 25 [207]

361-365

PL

W pracy omówiono różne metody wyznaczania obwiedni amplitudowej sygnału, tj. tradycyjnie stosowane metody tzw. średniej amplitudy i średniej energii oraz metodę wykorzystującą transformatę Hilberta. Wspomniane metody zastosowano do określenia obwiedni wybranych sygnałów bioakustycznych (tj. tonów serca oraz tonów Korotkowa).

EN

In this paper various methods of the signal envelope estimation are described (i.e. traditionally using methods based on the average energy or average amplitude, and the method based on Hilbert transform). The mentioned methods have been applied to some acoustic biomedical signals (i.e. heart sounds, Korotkoffs sounds).

7

Comparison and evaluation of LMS-derived algorithms applied on ECG signals contaminated with motion artifact during physical activities

63%

Galdos J. , Lopez N. , Medina A. , Huarca J. , Rendulich J. , Sulla E.

Applied Computer Science

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2024

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tom Vol. 20, no 1

157--172

EN

The acquisition of ECG signals offers physicians and specialists a very important tool in the diagnosis of cardiovascular diseases. However, very often these signals are affected by noise from various sources, including noise generated by movement during physical activity. This type of noise is known as Motion Artifact (MA) which changes the waveform of the signal, leading to erroneous readings. The elimination of this noise is performed by different filtering techniques, where the adaptive filtering using the LMS (least mean squares) algorithm stands out. The objective of this article is to determine which algorithms best deal with motion artifacts, taking into account the use of instruments or wearable equipment, in different conditions of physical activity. A comparison between different algorithms derived from LMS (NLMS, PNLMS and IPNLM) used in adaptive filtering is carried out using indicators such as: Pearson's Correlation Coefficient, Signal to Noise Ratio (SNR) and Mean Squared Error (MSE) as metrics to evaluate them. For this purpose, the mHealth database was used, which contains ECG signals taken during moderate to medium intensity physical activities. The results show that filtering by IPNLMS as well as PNLMS offers an improvement both visually and in terms of SNR, Pearson, and MSE indicators.

8

Metody oceny dynamiki zmian aktywności bioelektrycznej mózgu w czasie stymulacji

51%

Zalewska E. , Kowalczyk L. , Miszczak J.

Biuletyn Wojskowej Akademii Technicznej

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2009

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tom Vol. 58, nr 1

361-369

PL

Badanie zmienności aktywności spontanicznej mózgu podczas stymulacji jest bardzo istotnym elementem oceny reaktywności ośrodkowego układu nerwowego. Porównywana była charakterystyka czynności bioelektrycznej mózgu przed bodźcem (500 ms) i po bodźcu (do 1500 ms). Opracowane zostały metody oceny dynamiki zmian aktywności bioelektrycznej mózgu podczas stymulacji, a ich przydatność zweryfikowano w badaniach anormalności sygnału EEG u osób zdrowych oraz w różnicowaniu postaci otępienia starczego.

EN

Examination of spontaneous brain activity during stimulation is an important element of central nervous system reactivity examination. In the study we compared characteristics of brain bioelectrical activity before event (500 ms) and after event (up to 1500 ms). The methods developed for the evaluation of EEG changes due to stimulation have been applied in examinations of EEG signal abnormality in healthy subjects and in studies of senile dementia.