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  • MDPI AG  (3)
  • 1
    In: Bioengineering, MDPI AG, Vol. 10, No. 5 ( 2023-05-18), p. 607-
    Abstract: Most of the existing multi-lead electrocardiogram (ECG) detection methods are based on all 12 leads, which undoubtedly results in a large amount of calculation and is not suitable for the application in portable ECG detection systems. Moreover, the influence of different lead and heartbeat segment lengths on the detection is not clear. In this paper, a novel Genetic Algorithm-based ECG Leads and Segment Length Optimization (GA-LSLO) framework is proposed, aiming to automatically select the appropriate leads and input ECG length to achieve optimized cardiovascular disease detection. GA-LSLO extracts the features of each lead under different heartbeat segment lengths through the convolutional neural network and uses the genetic algorithm to automatically select the optimal combination of ECG leads and segment length. In addition, the lead attention module (LAM) is proposed to weight the features of the selected leads, which improves the accuracy of cardiac disease detection. The algorithm is validated on the ECG data from the Huangpu Branch of Shanghai Ninth People’s Hospital (defined as the SH database) and the open-source Physikalisch-Technische Bundesanstalt diagnostic ECG database (PTB database). The accuracy for detection of arrhythmia and myocardial infarction under the inter-patient paradigm is 99.65% (95% confidence interval: 99.20–99.76%) and 97.62% (95% confidence interval: 96.80–98.16%), respectively. In addition, ECG detection devices are designed using Raspberry Pi, which verifies the convenience of hardware implementation of the algorithm. In conclusion, the proposed method achieves good cardiovascular disease detection performance. It selects the ECG leads and heartbeat segment length with the lowest algorithm complexity while ensuring classification accuracy, which is suitable for portable ECG detection devices.
    Type of Medium: Online Resource
    ISSN: 2306-5354
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2746191-9
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  • 2
    Online Resource
    Online Resource
    MDPI AG ; 2023
    In:  Remote Sensing Vol. 15, No. 11 ( 2023-05-23), p. 2710-
    In: Remote Sensing, MDPI AG, Vol. 15, No. 11 ( 2023-05-23), p. 2710-
    Abstract: Due to the long synthetic aperture time, the large squint angle, and the large imaging width of medium Earth orbit (MEO) and high Earth orbit (HEO) SAR satellites, it is difficult to simulate the geometric positioning accuracy of MEO- and HEO-SAR satellites through the SAR image simulation methods. In this paper, one non-zero Doppler simulation method of geometric positioning accuracy was proposed without simulating SAR images. In order to simulate the geometric positioning accuracy under different errors and imaging observation conditions, the virtual simulation geometric model was constructed by the simulated satellite ephemeris and the coordinates of ground control points (GCPs). On this basis, one geometric accuracy simulation method based on mean value compensation was proposed to simulate the geometric positioning accuracy with GCPs. The experimental results showed that the impact of Doppler center frequency error and velocity error of MEO- and HEO-SAR satellites on geometric positioning accuracy is significant compared with the LEO-SAR satellites, and the maximum error they affect can reach about 1597 m. In addition, the geometric positioning accuracies of MEO- and HEO-SAR satellites with GCPs can be achieved to 1~10 m and 7~29 m, respectively.
    Type of Medium: Online Resource
    ISSN: 2072-4292
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2513863-7
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  • 3
    Online Resource
    Online Resource
    MDPI AG ; 2022
    In:  Applied Sciences Vol. 12, No. 12 ( 2022-06-10), p. 5947-
    In: Applied Sciences, MDPI AG, Vol. 12, No. 12 ( 2022-06-10), p. 5947-
    Abstract: To improve the measurement accuracy of unmanned aerial vehicles (UAVs), in this study, we proposed a method for measuring the attitude angle of a UAV by the combination of a magnetometer and satellite positioning system. Based on the measurement principle, we established a combined measurement error model, analyzed the root cause of the measurement error, and calibrated the magnetometer using the least-squares algorithm. For handling external or system interference effects, we designed a compensation algorithm that does not depend on environmental information. For handling measurement errors, a “current” statistical model was established, and the continuous-discrete Kalman filter algorithm was used to eliminate measurement errors. The test results showed that after using the compensation algorithm, the measurement error was reduced from 17.80% to 6.86% compared to the average absolute error of the local magnetic field intensity, and the absolute measurement error was reduced by 61.49%. The absolute measurement error was compared after using the compensation + filtering algorithm, and the error after compensation was further reduced by 42.36%. Hence, we proved the feasibility and effectiveness of our method.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704225-X
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