8 research outputs found

    Electrocardiogram modeling during paroxysmal atrial fibrillation : Application to the detection of brief episodes

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    Objective: A model for simulating multi-lead ECG signals during paroxysmal atrial fibrillation (AF) is proposed. Significance: The model is of particular significance when evaluating detection performance in the presence of brief AF episodes, especially since annotated databases with such episodes are lacking. Approach: The proposed model accounts for important characteristics such as switching between sinus rhythm and AF, varying P-wave morphology, repetition rate of f-waves, presence of atrial premature beats, and various types of noise. Main results: Two expert cardiologists assessed the realism of simulated signals relative to real ECG signals, both in sinus rhythm and AF. The cardiologists identified the correct rhythm in all cases, and considered two-thirds of the simulated signals as realistic. The proposed model was also investigated by evaluating the performance of two AF detectors which explored either rhythm only or both rhythm and morphology. The results show that detection performance is strongly dependent on AF episode duration, and, consequently, demonstrate that the model can play a significant role in the investigation of detector properties

    The influence of areal cartographer on layer information of georeferencial cadastral data in the updating process

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    Šiame leidinyje publikuojama tarptautinės mokslinės - metodinės konferencijos "Gamtotvarkos aktualijos - 2019“ pranešimų medžiagaKompiuterinės kartografinės programos suteikia galimybę erdvinius geografinius duomenis panaudoti praktiškai visose žmogaus veiklos srityse. Dėl šios priežasties erdvinių duomenų kaupimas ir atnaujinimas yra labai svarbi viso pasaulio visuomenes veiklos dalis, kadangi nuo šios veiklos priklauso tolimesnė visuomenės vystymosi pažanga, įvairūs projektavimo bei planavimo sprendimai. Viena svarbiausių kartografijos sričių yra georeferenciniai duomenys, nes jie tarnauja objektų erdvinei padėčiai nurodyti, pagrindu sudarant teminius duomenų rinkinius, o taip pat saugumo užtikrinimui, kadangi patikimi georeferenciniai duomenys būtini kariškiams. Dėl paminėtų priežasčių savalaikis duomenų atnaujinimas yra būtinas. Tyrimo objektas – georeferencinio kadastro vektoriniai bei atributiniai duomenys. Tyrimo tikslas – nustatyti kartografuotojo įtaką georeferencinio kadastro plotinių duomenų kaupimo procesui. Uždaviniai: Kiekvienam tyrėjui atnaujinti pateikti užstatytų teritorijų, medžiais ir krūmais apaugusių te-ritorijų, baseinų ir kūdrų vektorinius bei atributinius duomenis. Atlikti skirtingų kartografuotojų sukauptų duomenų palyginamąją analzę. Tyrimo objektas – Georeferencinių kadastro duomenų sluoksniai: užstatytos teritorijos (pu0), medžiais ir krūmais apaugusios teritorijos (ms0) bei kūdrų ir baseinų (hd4) sluoksniai, išsidėstę dalyje Marijampolės sav. Igliaukos kadastro vietovėje. Tyrimo objektu pasirinkta vietovė pagal žemės dangos tankumąComputer cartographic programs enable spatial geographic data to be used in prac-tically all areas of human activity. For this reason, collecting and updating of spatial data is a very important part of the activities of the entire world community, as it is a further development of society, various design and planning solutions. One of the most important domains of cartography is georeferenced data because it serves to indicate the spatial position of objects on the basis of thematic data sets, as well as to ensure security, as reliable georeferenced data is necessary for military personnel. For these reasons, timely updating of data is necessary. The object of the research is the vector and attribute data of georeferenced cadastre. The aim of the study is to determine the influence of the cartographer on the georeferenced cadastral data collection process. Each researcher had to update the vector and attribute data of the selected area (the dominant area for trees and bushes, pools and wetlands). They also had to do the comparative analysis of data which was collected by different cartographers. Object of the survey - Georeferential cadastral data layers: built-up areas (pu0), trees and bushy areas (ms0) and ponds and water pools (hd4) layers in Marijampole municipality cadastral site Igliauka. The site was chosen according to the density of the groundKauno miškų ir aplinkos inžinerijos kolegijaVytauto Didžiojo universitetasŽemės ūkio akademij

    Atrial fibrillation frequency tracking in ambulatory ECG signals : The significance of signal quality assessment

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    An approach to atrial fibrillation (AF) frequency tracking in long-term ambulatory ECG recordings is presented, comprising f-wave extraction, dominant atrial frequency (DAF) tracking, and signal quality assessment. Since poor signal quality is commonly encountered in ambulatory monitoring, a recently proposed index is employed to assess f-wave signal quality in a database containing 38 patients with permanent AF. The index ensures that DAF outliers, typically associated with poor-quality segments, are excluded from further analysis. 40% of all 5-s signal segments were excluded from the database due to poor quality. The exclusion of DAF outliers significantly reduces the standard deviation of the frequency estimates (p≤0.01), allowing more reliable evaluation of the difference between day- and night-time DAF. The results show that signal quality assessment plays a central role in DAF tracking, and therefore should be employed in ambulatory monitoring
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