9,942 research outputs found

    Are We Insane? The Quest for Proportionality in the Discovery Rules of the Federal Rules of Civil Procedure

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    Atrial fibrillation is a common heart arrhythmia which is characterized by a missing or irregular contraction of the atria. The disease is a risk factor for other more serious diseases and the total medical costs in society are extensive. Therefore it would be beneficial to improve and optimize the prevention and detection of the disease.   Pulse palpation and heart auscultation can facilitate the detection of atrial fibrillation clinically, but the diagnosis is generally confirmed by an ECG examination. Today there are several algorithms that detect atrial fibrillation by analysing an ECG. A common method is to study the heart rate variability (HRV) and by different types of statistical calculations find episodes of atrial fibrillation which deviates from normal sinus rhythm.   Two algorithms for detection of atrial fibrillation have been evaluated in Matlab. One is based on the coefficient of variation and the other uses a logistic regression model. Training and testing of the algorithms were done with data from the Physionet MIT database. Several steps of signal processing were used to remove different types of noise and artefacts before the data could be used.   When testing the algorithms, the CV algorithm performed with a sensitivity of 91,38%, a specificity of 93,93% and accuracy of 92,92%, and the results of the logistic regression algorithm was a sensitivity of 97,23%, specificity of 93,79% and accuracy of 95,39%. The logistic regression algorithm performed better and was chosen for implementation in Java, where it achieved a sensitivity of 97,31%, specificity of 93,47% and accuracy of 95,25%.Förmaksflimmer Àr en vanlig hjÀrtrytmrubbning som kÀnnetecknas av en avsaknad eller oregelbunden kontraktion av förmaken. Sjukdomen Àr en riskfaktor för andra allvarligare sjukdomar och de totala kostnaderna för samhÀllet Àr betydande. Det skulle dÀrför vara fördelaktigt att effektivisera och förbÀttra prevention samt diagnostisering av förmaksflimmer.   Kliniskt diagnostiseras förmaksflimmer med hjÀlp av till exempel pulspalpation och auskultation av hjÀrtat, men diagnosen brukar faststÀllas med en EKG-undersökning. Det finns idag flertalet algoritmer för att detektera arytmin genom att analysera ett EKG. En av de vanligaste metoderna Àr att undersöka variabiliteten av hjÀrtrytmen (HRV) och utföra olika sorters statistiska berÀkningar som kan upptÀcka episoder av förmaksflimmer som avviker frÄn en normal sinusrytm.   I detta projekt har tvÄ metoder för att detektera förmaksflimmer utvÀrderats i Matlab, en baseras pÄ berÀkningar av variationskoefficienten och den andra anvÀnder sig av logistisk regression. EKG som kommer frÄn databasen Physionet MIT anvÀnds för att trÀna och testa modeller av algoritmerna. Innan EKG-signalen kan anvÀndas mÄste den behandlas för att ta bort olika typer av brus och artefakter.   Vid test av algoritmen med variationskoefficienten blev resultatet en sensitivitet pÄ 91,38%, en specificitet pÄ 93,93% och en noggrannhet pÄ 92,92%. För logistisk regression blev sensitiviteten 97,23%, specificiteten 93,79% och noggrannheten 95,39%. Algoritmen med logistisk regression presterade bÀttre och valdes dÀrför för att implementeras i Java, dÀr uppnÄddes en sensitivitet pÄ 91,31%, en specificitet pÄ 93,47% och en noggrannhet pÄ 95,25%

    Advancing Human Rights Through the United Nations

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    Today's high oil prices and more stringent environmental requirements have led to that manufacturers of mobile construction equipment try to make their products more energy efficient. With this in mind a project about hybridization of hydraulic systems has been formed. The purpose of this project was to analyze the savings that can be achieved by hybridization of hydraulic systems. A reach stacker truck (Kalmar DRD450-80S4XS) were simulated in some load cases with conventional hydraulic systems and with three types of hybridized hydraulic systems. Different parts of the hydraulic systems were also analyzed separately. The analysis has shown that significant energy savings can be achieved by hybridizing hydraulic systems. The analysis showed that between 9-30% energy savings could be achieved by hybridizing the truck's various subsystems.Med dagens höga oljepriser och samhÀllets allt strÀngare miljökrav, stÀvar tillverkare av mobila entreprenadmaskiner efter att energieffektivisera sina produkter. Med detta i tanke formades ett projekt om att regenerera hydraulisk energi pÄ entreprenadmaskiner. Syftet med detta projekt var att analysera vilka besparingar som kan Ästakommas genom att hydraulsystemet pÄ entrprenadmaskiner hybridiseras. En reachstacker truck (Kalmar DRD450-80S4XS) simulerades i nÄgra lastfall med konventionellt hydraulsystem samt med tre typer av hybridiserade hydraulsystem. Olika delar av de hydrauliska systemen analyserades Àven var för sig. Analysen har visat att stora energibesparingar kan Ästakommas genom att hybridisera hydraulsystem. Den genomförda analysen visade pÄ att mellan 9-30% energibesparing kunde uppnÄs genom att hybridisera truckens olika delsystem

    Control of MTDC Transmission Systems under Local Information

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    High-voltage direct current (HVDC) is a commonly used technology for long-distance electric power transmission, mainly due to its low resistive losses. In this paper a distributed controller for multi-terminal high-voltage direct current (MTDC) transmission systems is considered. Sufficient conditions for when the proposed controller renders the closed-loop system asymptotically stable are provided. Provided that the closed loop system is asymptotically stable, it is shown that in steady-state a weighted average of the deviations from the nominal voltages is zero. Furthermore, a quadratic cost of the current injections is minimized asymptotically

    Distributed PI-Control with Applications to Power Systems Frequency Control

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    This paper considers a distributed PI-controller for networked dynamical systems. Sufficient conditions for when the controller is able to stabilize a general linear system and eliminate static control errors are presented. The proposed controller is applied to frequency control of power transmission systems. Sufficient stability criteria are derived, and it is shown that the controller parameters can always be chosen so that the frequencies in the closed loop converge to nominal operational frequency. We show that the load sharing property of the generators is maintained, i.e., the input power of the generators is proportional to a controller parameter. The controller is evaluated by simulation on the IEEE 30 bus test network, where its effectiveness is demonstrated

    Thermal properties of charge noise sources

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    Measurements of the temperature and bias dependence of Single Electron Transistors (SETs) in a dilution refrigerator show that charge noise increases linearly with refrigerator temperature above a voltage-dependent threshold temperature, and that its low temperature saturation is due to SET self-heating. We show further that the two-level fluctuators responsible for charge noise are in strong thermal contact with the electrons in the SET, which can be at a much higher temperature than the substrate. We suggest that the noise is caused by electrons tunneling between the SET metal and nearby potential wells
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