Frequency band selection (FBS) in rotating machinery fault diagnosis aims to recognize frequency band location including a fault transient out of a full band spectrum, and thus fault diagnosis can suppress noise influence from other frequency components. Impulsiveness and cyclostationarity have been recently recognized as two distinctive signatures of a transient. Thus, many studies have focused on developing quantification metrics of the two signatures and using them as indicators to guide FBS. However, most previous studies almost ignore another aspect of FBS, i.e. health reference, which significantly affect FBS performance. To address this issue, this paper investigates importance of a health reference and recognize it as the third critical aspect in FBS. With help of the health reference, the frequency band where the fault transient exists could be located. A novel approach based on classification is proposed to integrate all three aspects (impulsiveness, cyclostationarity, and health reference) for FBS. Classification accuracy is developed as a novel indicator to select the most sensitive frequency band for rotating machinery fault diagnosis. The proposed method (coined by accugram) has been validated on benchmark and experiment datasets. Comparison results show its effectiveness and robustness over conventional envelope analysis, the kurtogram, and the infogram.
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Sci Rep
January 2025
School of Advanced Technologies, Iran University of Science and Technology, Tehran, 1684613114, Iran.
This study presents a very thin wideband linear polarization converter in transmission mode with near-unity conversion efficiency. The suggested converter consists of a periodic array on a single-layer substrate, two metallic layers and six vias. Metallic vias connect the upper and lower layers of the construction.
View Article and Find Full Text PDFACS Nano
January 2025
Department of Chemistry, University of California Berkeley, Berkeley, California 94720, United States.
Understanding charge transport in semiconductor quantum dot (QD) assemblies is important for developing the next generation of solar cells and light-harvesting devices based on QD technology. One of the key factors that governs the transport in such systems is related to the hybridization between the QDs. Recent experiments have successfully synthesized QD molecules, arrays, and assemblies by directly fusing the QDs, with enhanced hybridization leading to high carrier mobilities and coherent band-like electronic transport.
View Article and Find Full Text PDFInt J Audiol
January 2025
Department of Audiology, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran.
Objective: Tinnitus and its pathophysiological mechanisms need more investigation because tinnitus may change the typical processing of sounds in the auditory system. Poor temporal resolution, which is not assessed with conventional subjective tinnitus evaluations, has been reported in some tinnitus sufferers.
Design: This study used a gap-in-noise paradigm to assess temporal resolution in tinnitus sufferers using both behavioural and electrophysiologic methods.
Phys Rev Lett
December 2024
University of Connecticut, University of Connecticut, School of Mechanical, Aerospace, and Manufacturing Engineering, Storrs, Connecticut 06269, USA and Institute of Materials Science, Storrs, Connecticut 06269, USA.
Flat lines within a band structure represent constant frequency bands for all momentum values (i.e., they maintain zero group velocity for all wave numbers).
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
Shaanxi Key Laboratory of Artificially Structured Functional Materials and Devices, Airforce Engineering University, Xi'an, Shaanxi, 710051, China.
The integrated modulation of radiation and scattering provides an unprecedented opportunity to reduce the number of electromagnetic (EM) apertures in the platform while simultaneously enhancing communication and stealth performance. Nevertheless, achieving full-polarization, arbitrary amplitude, and phase modulation of radiation scattering remains a challenge. In this paper, a strategy that realizes space-time coding of radiation scattering within the same frequency band, which enables the simultaneous and independent modulation of amplitude and phase, is proposed.
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