In order to accurately determine the dielectric characteristics of a planar material slab, this paper presents a sophisticated algorithm with high precision, drawing inspiration from the advancements made in the Multi...
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ISBN:
(纸本)9798350381061
In order to accurately determine the dielectric characteristics of a planar material slab, this paper presents a sophisticated algorithm with high precision, drawing inspiration from the advancements made in the Multiple Signal Classification (MUSIC) algorithm. The transmission coefficients are acquired with a planar material sample placed in the middle of the two antennas. The reflection coefficients are determined with a metal-backed planar material sample using only one antenna. Through the application of measured transmission or reflection coefficients across known sample thicknesses via free-space transmission or reflection measurements, the effectiveness of the proposed algorithm is validated. The algorithm's validity is established through experiments involving varied thicknesses of Teflon-PTFE materials at the X-band. The outcomes of estimating the complex relative permittivity for the planar Teflon-PTFE slab using the presented algorithm showcase precision for both methods, particularly when the sample's minimum thickness equates to half of a wavelength.
We propose original data processing methods for the dielectric characterization of frequency-dependent reflection coefficients of construction materials considering a very wide frequency band. Two types of approaches ...
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We propose original data processing methods for the dielectric characterization of frequency-dependent reflection coefficients of construction materials considering a very wide frequency band. Two types of approaches have been developed to obtain, from spectral measurements, estimates of the equivalent complex permittivity versus frequency or reconstruction of the impulse response. In particular, highresolution (HR) algorithms based on the matrix pencil method have been used in an original way to identify wave multipath inside a sample. Both approaches have been used for the characterization of different types of building materials. A database of dielectric responses of materials is under construction in order to provide the deterministic propagation simulator with the characteristics of building materials. (C) 2004 Elsevier GmbH. All rights reserved.
Object localization using active sensor network exploiting the scattering of the emitted waves by a transmitter has been drawing a lot of research interest in the last years. For most applications, the environment lea...
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Object localization using active sensor network exploiting the scattering of the emitted waves by a transmitter has been drawing a lot of research interest in the last years. For most applications, the environment leads to the arrival of multiple signals corresponding to emitted signal, signals which are scattered by the objects, and noise. In practical systems, the signals impinging on an array are frequently correlated, and the object number rapidly exceeds the number of sensors, making unsuitable most high-resolution methods used in array processing. We propose a solution to overcome these two experimental constraints. Firstly, frequential smoothing is used to decorrelate the scattered signals, enabling the estimation of their time delays of arrival (TDOA), using subspace-based methods. Secondly, an efficient algorithm for source localization using the TDOA is proposed. The advantage of the developed method is its efficiency even if the number of sources is larger than the number of sensors, in the presence of correlated signals. The performances of the proposed method are assessed on simulated signals. The results on real-world data are also presented and analyzed.
A novel multiplexing technique for angular estimation that avoids the use of switches and multiple RF chains is presented. The principle of operation is as simple as connecting cables of different electrical lengths t...
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A novel multiplexing technique for angular estimation that avoids the use of switches and multiple RF chains is presented. The principle of operation is as simple as connecting cables of different electrical lengths to the antennas. The advantages are simplicity and fast measurements, which enables the study of time-variant channels. If the duration of the excitation signal is less than a certain limit (which depends on the delays introduced by cables and on the delay spread of the propagation channel), the technique performs a time-domain multiplexing. However, the technique is especially interesting in the case that the excitation signal duration exceeds this limit. In that case, it requires the frequency of the signal to increase or to decrease linearly in time, regardless if the variation is discrete or continuous in time. The post-processing of the receiver output used to separate the signals corresponding to each antenna is detailed in this study. Once separated, the signals can be processed with a high-resolution algorithm to estimate the direction of departure and the direction of arrival. To validate the capability of this method, simulation results and measurements in an anechoic chamber are presented.
In this paper, we propose to perform early fault diagnosis using high-resolution spectral analysis of the stator current to detect bearing faults in electrical induction machine. While most research works focus on mec...
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ISBN:
(纸本)9781424410613
In this paper, we propose to perform early fault diagnosis using high-resolution spectral analysis of the stator current to detect bearing faults in electrical induction machine. While most research works focus on mechanical vibration analysis, the originality of our work relies on the use of high-resolution methods to detect modulations in the stator current. We present the results obtained for real data to detect inner and outer raceway bearing defects made articially as well as bearing defects obtained through on-site ageing. The obtained results show that the proposed method yields better detection than classical spectum analysis.
In this paper, we focus on the stationarity of the scatterer contributions in highly time-variant wideband Car-to-Car (C2C) channels. To do so, these scatterer contributions were first extracted using a high-resolutio...
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