A New Weighted Time Window-based Method to Detect B-point in ICG

Background: A simple, adaptive, and efficient method to detect the beginning of the left ventricular ejection in Impedance Cardiogram (ICG) or the so-called B-point is presented. From implementation perspective this method is designed in time domain and could be exploited for real-time implementation. Method: The core of the new method is transformation by weighted time window of an ICG segment preceding the maximal ICG peak (the C-point) aiming at the B-point enhancement. The resulting Modified B-point (MB-point) is then easily delineated. To evaluate the proposed workflow for B-point detection based solely on ICG signal, the dataset comprising 20 healthy participants and 21065 B-points are manually annotated and openly shared with the software code. To the best of our knowledge, this is the largest reported and shared ICG dataset for delineation. Detector performance was evaluated on two recorded segments with less and more distinct noises, as well as on an available dataset from the internet comprising ICG recorded in another set of 24 healthy subjects. Results: The results showed that the method was superior when the tolerance for B-point detection was set to +/-150 ms in all cases and for both datasets (>99.4%). Conclusions: In conclusion, proposed approach based on the weighted time windows presents a promising technique for reliable ICG delineation and even for further customization for labeling of other biomedical signals such as electrocardiogram and photopletismogram.Comment: 13 pages, 3 figures, 3 table

The numerical method of inverse Laplace transform for calculation of overvoltages in power transformers and test results

A methodology for calculation of overvoltages in transformer windings, based on a numerical method of inverse Laplace transform, is presented. Mathematical model of transformer windings is described by partial differential equations corresponding to distributed parameters electrical circuits. The procedure of calculating overvoltages is applied to windings having either isolated neutral point, or grounded neutral point, or neutral point grounded through impedance. A comparative analysis of the calculation results obtained by the proposed numerical method and by analytical method of calculation of overvoltages in transformer windings is presented. The results computed by the proposed method and measured voltage distributions, when a voltage surge is applied to a three-phase 30 kVA power transformer, are compared. [Projekat Ministartsva nauke Republike Srbije, br. TR-33037 i br. TR-33020

An Efficient Method for Approximation of Non Rational Transfer Functions

A method for rational approximation of linear fractional order systems (LFOS) is presented in the present paper. The method is computationally efficient, flexible and effective, as is illustrated by numerous examples. The proposed approach can also be used as an intermediate stage in designing indirect discrete rational approximations

A novel method for in-situ extracting bio-impedance model parameters optimized for embedded hardware

Abstract A novel method for embedded hardware-based parameter estimation of the Cole model of bioimpedance is developed and presented. The model parameters R ∞, R 1 and C are estimated using the derived set of equations based on measured values of real (R) and imaginary part (X) of bioimpedance, as well as the numerical approximation of the first derivative of quotient R/X with respect to angular frequency. The optimal value for parameter α is estimated using a brute force method. The estimation accuracy of the proposed method is very similar with the relevant work from the existing literature. Moreover, performance evaluation was performed using the MATLAB software installed on a laptop, as well as on the three embedded-hardware platforms (Arduino Mega2560, Raspberry Pi Pico and XIAO SAMD21). Obtained results showed that the used platforms can perform reliable bioimpedance processing with the same accuracy, while Raspberry Pi Pico is the fastest solution with the smallest energy consumption

Mera fleksije trupa za ocenu bola u leđima / Trunk flexion measurement for the assessment of low back pain / Измерение подвижности туловища при оценке боли в спине

Low Back Pain (LBP) is one of the most common incidences all over the world. For the assessment of LBP, descriptive medical scores are widely used. Nevertheless, there is a need for the quantitative assessment of LBP by appropriate physiological and kinematic measurements. Quantitative assessment methods are of interest since they might provide reliable and repeatable measures related to low back pain in both everyday clinical practice and at home or work. In this paper, we proposed simple measurements of the trunk angle and the activity of back muscles during simple flexion/relaxation task for an improved assessment of LBP (Low Back Pain). The application of the proposed instrumentation and signal processing is evaluated in three healthy subjects and in two individuals with LBP.The presented data analysis indicates that angle velocity might be a promising parameter in a combination with electromyography profiles for differentiation between healthy subjects and in individuals with LBP for improved medical diagnostics and assessment. / Bol u leđima je jedan od najčešćih zdravstvenih problema ljudi u celom svetu. Za ocenu oporavka pacijenata sa bolom u leđima i dijagnostiku u upotrebi su deskriptivne medicinske skale. Međutim, kako bi se kvantitativno ocenio oporavak pacijenata neophodno je definisati odgovarajuće fiziološke i kinematičke mere. One su značajne kako bi se obezbedila neophodna ponovljivost i pouzdanost ocene za njihovu primenu u kliničkoj praksi i u kućnim uslovima. U ovom radu predloženo je jednostavno merenje elektromiografskih (EMG) signala mišića leđa i merenje ugla trupa tokom fleksije/ekstenzije trupa. Primena predložene instrumentacije i rutina za procesiranje signala testirani su merenjima na tri zdrava ispitanika i na dva ispitanika sa bolom u leđima. Predložena analiza izmerenih signala pokazala je da bi se za kvantitativnu ocenu pacijenata i zdravih ispitanika mogla koristiti brzina fleksije/esktenzije trupa u kombinaciji sa profilima aktivacije mišića trupa. Rezultati testiranja pokazali su da je analizom trajektorija ugla u trupu, brzine trupa i mišićnih profila moguće razlikovati zdrave i bolne profile fleksije trupa, što bi značajno unapredilo današnju medicinsku dijagnostiku. / Боли в спине одна из самых распространенных заболеваний во всем мире. Для установления диагноза и прогноза реабилитации пациентов применяется описательные шкалы. Но для достоверной количественной оценки реабилитации пациентов необходимо определить подходящие физиологические и кинематические меры. Такие меры важны для обеспечения точности оценки, и могут применяться как в клинических, так и в домашних условиях. В статье рассматривается обыкновенное электромиографическое исследование (ЭМГ) сигналов мышц спины и измерение угла туловища при сгибании/разгибании позвоночника. Был проведен эксперимент по предложенным процедурам измерения сигнала на трех здоровых людях и 2-х пациентах с болями в спине. Проведенный эксперимент измерения сигнала показал, что на точность количественной оценки больных и здоровых обследуемых влияет скорость сгибания/разгибания позвоночника, и свойства активированных мышц туловища. Результаты исследования показали, что при анализе траектории угла туловища, скорости сгибания/разгибания, и профиля мышц, возможно различить здоровые профили сгибания туловища от больных. Применение данных результатов могло бы значительно улучшить эффективность современной медицинской диагностики