- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Statistical classification of contamination in glass insulators by reading its spectrum
摘要： This paper proposes to use a statistical approach for classifying the contamination level of insulators used in high voltage transmission lines. This studied case considers the voltage applied on glass insulators used in a chain of six elements of a 69 kV power line. When submitted to high voltage, the insulators radiate radio frequency signals up to frequencies of some GHz. In this frequency range the signal can be detected using portable antennas, and then be applied to post processing. These received spectra are analyzed by statistical methods, mean and standard deviation, and the cross relation between them is used to classify the pollution level in insulators. To reduce complexity and cost a simple data processing using the mean and the standard deviation are used. Two types of glass insulators are considered: clean or polluted, and to cover the entire frequency range from 30 MHz to 1 GHz two types of antennas were needed. The results obtained with the mean and the standard deviation show that the first 100 MHz bandwidth can be used for statistical of the insulator pollution level.
关键词： radio frequency spectrum,mean value,High voltage transmission lines insulators,statistical classification methods,standard deviation
更新于2025-09-23 15:22:29
-
[IEEE 2019 XXIVth International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Lviv, Ukraine (2019.9.12-2019.9.14)] 2019 XXIVth International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Waveguide Millimeter Wave Measurement Cell with Minimum Reflection Coefficient for Complex Permittivity Determination of Bioactive Liquids
摘要： An original waveguide millimeter wave measurement cell for complex permittivity determination of bioactive high-loss liquids was studied numerically and experimentally. This measurement cell consisted of round metal waveguide, Teflon inserted and glass capillary with liquid under test inside. The main features of the measurement cell are as follows. Waveguide connections (matching elements) to input and output waveguides have minimum reflection coefficient. The capillary with the high loss liquids under test located not in the electromagnetic field maximum as usual, but at an angle to the wave propagation along the waveguide cell. The advantages of such capillary location were discussed in the paper. This waveguide millimeter wave measurement cell was compared with the symmetrical waveguide millimeter wave measurement cell for complex permittivity determination.
关键词： millimeter waves,reflection coefficient,Microwave resonator,complex permittivity,bioactive liquids,frequency spectrum,waveguide
更新于2025-09-16 10:30:52
-
Design of a frequency spectrum-based versatile two-dimensional arbitrary shape filter bank: application to contact lens detection
摘要： A filter bank (FB) is an integral part of any image processing system. The designing of a FB generally involves modifying an existing FB or focusing on a particular property of the filter bank. Such FBs limit their use to a particular image. Through our work, we have devised a unique and novel approach for designing a two-dimensional arbitrary shape filter bank (2-D ASFB). This FB is inherently 2-D and eliminates the need for transforming a one-dimensional FB into 2-D. Its arbitrary nature expands its application to any image as compared to regular-shaped FBs currently in use. The novelty of the design lies in the fact that the designed FB can match the frequency spectrum of any image by reducing the error function between the frequency spectrum and the desired filter response of the FB. The error function has been minimized using the eigenfilter approach. After designing the low-pass analysis filter, perfect reconstruction constraint has been used to get a low-pass synthesis filter. In this paper, we have demonstrated the use of the 2-D ASFB specifically for contact lens detection (CLD). The proposed CLD system focuses on feature extraction using the 2-D ASFB. The support vector machine classifier is the same as in the existing systems. The results show improved correct classification rate as compared to the existing systems for IIITD and ND2013 contact lens database. This 2-D ASFB overcomes limitations posed by the existing filter banks with respect to separability, directionality, orthogonality, and shape. This FB can be effectively applied to any feature extraction application such as pattern recognition, biometrics, medical image processing.
关键词： Eigenfilter,Contact lens detection,Feature extraction,Filter bank,Frequency spectrum
更新于2025-09-09 09:28:46
-
Retrieval of Polarimetric Azimuthal Angular Characteristics via the Application of Target Decomposition to Spectral Domain Circular SAR Images
摘要： In this paper, we discuss the application of polarimetric target decomposition (TD) theorems to circular synthetic aperture radar (CSAR) images to retrieve the polarimetric azimuthal angular characteristics of the targets. In CSAR systems, radar-carrying aircraft moves along a circular path. The antenna beam is pointed toward the center of the circular path during the data acquisition to irradiate the spotlighted area from various azimuthal or aspect angles. Therefore, the resultant polarimetric CSAR images contain information about the polarimetric scattering mechanisms of the targets at each aspect angles. To recover this information, we propose the use of spectral decomposition of CSAR images in combination with several TD algorithms. The spectral domain CSAR images can be viewed as the azimuthal angular spectrum images. Thus, the application of TD algorithms to the spectral domain images is expected to be able to obtain the angular dependence and polarimetric scattering properties of the targets simultaneously. We carried out a simple numerical simulation and an indoor laboratory experiment to validate the proposed TD scheme.
关键词： Circular SAR (CSAR),target decomposition (TD),polarimetric radar,spatial frequency spectrum
更新于2025-09-09 09:28:46
-
[ACM Press the 2018 ACM International Joint Conference and 2018 International Symposium - Singapore, Singapore (2018.10.08-2018.10.12)] Proceedings of the 2018 ACM International Joint Conference and 2018 International Symposium on Pervasive and Ubiquitous Computing and Wearable Computers - UbiComp '18 - PPG-based Heart Rate Estimation with Time-Frequency Spectra
摘要： PPG-based continuous heart rate estimation is challenging due to the effects of physical activity. Recently, methods based on time-frequency spectra emerged to compensate motion artefacts. However, existing approaches are highly parametrised and optimised for specific scenarios. In this paper, we first argue that cross-validation schemes should be adapted to this topic, and show that the generalisation capabilities of current approaches are limited. We then introduce deep learning, specifically CNN-models, to this domain. We investigate different CNN-architectures (e.g. the number of convolutional layers, applying batch normalisation, or ensemble prediction), and report insights based on our systematic evaluation on two publicly available datasets. Finally, we show that our CNN-based approach performs comparably to classical methods.
关键词： Heart rate,CNN,Evaluation methods,Deep learning,PPG,Time-frequency spectrum
更新于2025-09-09 09:28:46