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Mathematical methods of signal analysis applied in medical diagnostic

Ciecierski Konrad A.

International Journal of Applied Mathematics and Computer Science

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2020

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Vol. 30, no. 3

449--462

EN

Digital signal processing, such as filtering, information extraction, and fusion of various results, is currently an integral part of advanced medical therapies. It is especially important in neurosurgery during deep-brain stimulation procedures. In such procedures, the surgical target is accessed using special electrodes while not being directly visible. This requires very precise identification of brain structures in 3D space throughout the surgery. In the case of deep-brain stimulation surgery for Parkinson’s disease (PD), the target area—the subthalamic nucleus (STN)—is located deep within the brain. It is also very small (just a few millimetres across), which makes this procedure even more difficult. For this reason, various signals are acquired, filtered, and finally fused, to provide the neurosurgeon with the exact location of the target. These signals come from preoperative medical imaging (such as MRI and CT), and from recordings of brain activity carried out during surgery using special brain-implanted electrodes. Using the method described in this paper, it is possible to construct a decision-support system that, during surgery, analyses signals recorded within the patient’s brain and classifies them as recorded within the STN or not. The constructed classifier discriminates signals with a sensitivity of 0.97 and a specificity of 0.96. The described algorithm is currently used for deep-brain stimulation surgeries among PD patients.

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Using of continuous wavelet transform for de-noising signals accompanying electrical treeing in epoxy resins

Dobrzycki A., Mikulski S.

Przegląd Elektrotechniczny

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2016

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R. 92, nr 4

26--29

EN

The following paper presents application of methods of noise reduction in acoustic emission signals, accompanying phenomenon electrical treeing of solid dielectric such as epoxy resin, based on time-frequency signal analysis. For signal estimation was applied method of soft and hard thresholding described by Donoho and Johnson. All calculations ware obtained with use of Matlab software, especially Wavelet Toolbox.

PL

W artykule zaprezentowanie zastosowanie metod redukcji szumu w sygnałach emisji akustycznej towarzyszących zjawisku drzewienia dielektryków stałych, w szczególności żywic epoksydowych, opartych na falkowej analizie sygnałow. Opisany został algorytm usuwania szumów z sygnału m. in. algorytm miękkiego oraz twardego progowania stworzonych przez Donoho i Johnsona. Wszystkie obliczenia wykonano w Matlabie z wykorzystaniem dodatku Wavelet Toolbox.

3

Vibrations on driver position of agricultural tractor during meadow mowing using high efficient disc mowers

Ignasiak Ł., Spadło M., Kromulski J., Pawłowski T.

Journal of Research and Applications in Agricultural Engineering

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2015

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Vol. 60, nr 3

114--118

EN

The paper concerns the subject of vibrations influence on driver body, generated by high efficient disc mowers while mowing and during transport on public roads and dirt roads. Information about accelerations of the head and the seat of machine operator were collected. Then these data were converted to the characteristics, which were compared with the limit values specified in ISO 2631. Allowable exposure times of the human body to the vibrations were defined and assessment of the risk of loss of control over the machine by vibration was performed.

PL

W artykule podjęto tematykę wpływu wibracji na organizm kierowcy, generowanych przez wysokowydajne kosiarki dyskowe, podczas realizacji procesu technologicznego koszenia oraz podczas przejazdów transportowych po drogach publicznych i polnych. Zgromadzono informacje o przebiegach przyspieszeń głowy oraz siedziska operatora agregatu. Dane te poddano następnie przekształceniom i uzyskano charakterystyki, które skonfrontowano z wartośćiami dopuszczalnymi określonymi w normie ISO 2631. Zdefiniowano dopuszczalne czasy ekspozycji na drgania dla organizmu człowieka i dokonano oceny narażenia na niebezpieczeństwo utraty kontroli nad prowadzonym zespołem w wyniku wibracji.

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Separation of groups of free radicals from noised EPR spectrum using genetic algorithm and gradient method

Bernas M., Ramos P.

Journal of Medical Informatics & Technologies

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2013

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Vol. 22

117--123

EN

Different groups of free radicals exist in biological material like animal tissues or plants parts. The processes like heating or cooling creates additional types of free radicals groups in this organic matter, due to changes in chemical bonds. The paper proposes a method to determine types and concentrations of different groups of free radicals in the matter processed in various temperatures. The method extracts the spectrum of free radicals using electron paramagnetic resonance with the microwave power of 2.2 mW. Then an automatic method to find a best possible fit using limited number of theoretical mathematical functions is proposed. The match is found using spectrum filtration, and a genetic algorithm implementation supported by a Gradient Method. The obtained results were compared against the samples prepared by an expert. Finally, some remarks were given and new possibilities for future research were proposed.

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Novel S-transform information fusion for filtering ultrasonic pulse-echo signals

Kubinyi M., Kreibich O., Neuzil J., Smid R.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 1

290-295

EN

Direct evaluation of ultrasonic signals requires data analyses with an acceptable level of noise. Ultrasonic signals represent a specific category of time domain signals to be analyzed. In order to increase a difference between the level of noise and the amplitude of the ultrasonic pulse a suitable method for signal filtering has to be used. Within this article we discuss and evaluate a novel signal denoising method. The S-transform for signal analysis and processing was used. This transformation has been recently introduced for ultrasonic echo analyses. Proposed transformation represents an intermediate stage between the Fourier transform analysis and the wavelet transform analysis. In order to filter ultrasonic signals from the Electromagnetic Acoustic Transducer (EMAT) with a high level of noise, new, different approach in signal filtering was developed based on an information fusion. Suggested method is able to process the pulse-echo signal in its full complexity. Proposed method offers good results in studied ultrasonic signals in comparison to digital filter or wavelet denoising.

PL

Bezpośrednia ocean sygnału ultradźwiękowego wymaga analizy danych obciążonych szumami. W celu zwiększenia różnicy między amplitudą sygnału a szumami użyto specjalnej metody filtrowania. Zastosowano transformatę S do analizy ultradźwiękowego sygnału echa. Tego typu transformata jest metodą pośrednia między transformatą Fouriera a transformatą falkową. Użyto nowej metody bazującej na fuzji informacji. Testy potwierdziły że nowa metoda może być skuteczniejsza niż filtrowanie cyfrowe czy odszumianie falkowe.