Intelligent Health Monitoring of Machine Bearings Based on Feature Extraction

This document is the Accepted Manuscript of the following article: Mohammed Chalouli, Nasr-eddine Berrached, and Mouloud Denai, ‘Intelligent Health Monitoring of Machine Bearings Based on Feature Extraction’, Journal of Failure Analysis and Prevention, Vol. 17 (5): 1053-1066, October 2017. Under embargo. Embargo end date: 31 August 2018. The final publication is available at Springer via DOI: https://doi.org/10.1007/s11668-017-0343-y.Finding reliable condition monitoring solutions for large-scale complex systems is currently a major challenge in industrial research. Since fault diagnosis is directly related to the features of a system, there have been many research studies aimed to develop methods for the selection of the relevant features. Moreover, there are no universal features for a particular application domain such as machine diagnosis. For example, in machine bearing fault diagnosis, these features are often selected by an expert or based on previous experience. Thus, for each bearing machine type, the relevant features must be selected. This paper attempts to solve the problem of relevant features identification by building an automatic fault diagnosis process based on relevant feature selection using a data-driven approach. The proposed approach starts with the extraction of the time-domain features from the input signals. Then, a feature reduction algorithm based on cross-correlation filter is applied to reduce the time and cost of the processing. Unsupervised learning mechanism using K-means++ selects the relevant fault features based on the squared Euclidian distance between different health states. Finally, the selected features are used as inputs to a self-organizing map producing our health indicator. The proposed method is tested on roller bearing benchmark datasets.Peer reviewe

Impact of hygrothermal aging on rotational behavior of web-flange junctions of structural pultruded composite members for bridge applications

his paper presents the results of the second part of a multi-phase study focused on hygrothermal behavior of pultruded fiber reinforced polymer (PFRP) web-flange junction for bridge applications. The information reported herein focuses on hygrothermal effect on the rotational stiffness and strength of web/flange junctions (WFJs) of typical pultruded profiles commonly used in general construction applications and in bridge decks in particular. Experimental results extracted from a total of twenty-seven as-built (unexposed) and seventy-six pultruded WFJs specimens exposed to fresh water and artificial seawater environments at temperatures of 40℃, 60℃and 80℃. The study evaluated the rotational characteristics of six different web-flange junctions and hygrothermal aging effects on one of such junctions. The experimental results indicated that the moment capacity and associated rotational stiffness of J1 junction group specimens was the largest among the junction “J” groups evaluated in this study. In addition, it was concluded that the moment capacity of AJ2-M1 adhesively-bonded junctions was the largest; however, the rotational stiffness of specimens AJ3-M1 and AJ3-M2 were the highest among the “AJ#-M1” group and “AJ#-M2” group, respectively. A general conclusion was reached, based on the experimental results, that is both the WFJ moment capacity and associated rotational stiffness are proportional to the size of three elements: (i) web thickness, (ii) fillet radius, and (iii) flange thickness of the pultruded profile. Results also showed that: (1) the difference in ultimate moment capacity degradation due to hygrothermal effects for WFJs exposed to fresh water and artificial seawater environments at temperatures of 40℃ and 80℃ is relatively small, however, the ultimate moment capacity degradation of specimens exposed to artificial seawater was relatively higher as comparted to those exposed to fresh water environments at a temperature of 60℃; (2) in general, exposure to higher temperatures, results in a relatively higher strength degradation, except for the case of fresh water exposure at a temperature range between 40℃and 60℃

Impact of hygrothermal aging on rotational behavior of web-flange junctions of structural pultruded composite members for bridge applications

his paper presents the results of the second part of a multi-phase study focused on hygrothermal behavior of pultruded fiber reinforced polymer (PFRP) web-flange junction for bridge applications. The information reported herein focuses on hygrothermal effect on the rotational stiffness and strength of web/flange junctions (WFJs) of typical pultruded profiles commonly used in general construction applications and in bridge decks in particular. Experimental results extracted from a total of twenty-seven as-built (unexposed) and seventy-six pultruded WFJs specimens exposed to fresh water and artificial seawater environments at temperatures of 40℃, 60℃and 80℃. The study evaluated the rotational characteristics of six different web-flange junctions and hygrothermal aging effects on one of such junctions. The experimental results indicated that the moment capacity and associated rotational stiffness of J1 junction group specimens was the largest among the junction “J” groups evaluated in this study. In addition, it was concluded that the moment capacity of AJ2-M1 adhesively-bonded junctions was the largest; however, the rotational stiffness of specimens AJ3-M1 and AJ3-M2 were the highest among the “AJ#-M1” group and “AJ#-M2” group, respectively. A general conclusion was reached, based on the experimental results, that is both the WFJ moment capacity and associated rotational stiffness are proportional to the size of three elements: (i) web thickness, (ii) fillet radius, and (iii) flange thickness of the pultruded profile. Results also showed that: (1) the difference in ultimate moment capacity degradation due to hygrothermal effects for WFJs exposed to fresh water and artificial seawater environments at temperatures of 40℃ and 80℃ is relatively small, however, the ultimate moment capacity degradation of specimens exposed to artificial seawater was relatively higher as comparted to those exposed to fresh water environments at a temperature of 60℃; (2) in general, exposure to higher temperatures, results in a relatively higher strength degradation, except for the case of fresh water exposure at a temperature range between 40℃and 60℃

Mechanical characterization of a unidirectional pultruded composite lamina using micromechanics and numerical homogenization

In this paper, analytical and numerical homogenization methods are proposed to effectively simulate the macroscopic characteristics of a pultruded composite lamina. A continuum damage model was implemented via user material subroutine to model fiber failure, while the Mohr-Coulomb plastic criterion is employed to model matrix damage. In order to simulate the damage of the fiber-matrix interface, the relationship between traction and displacement is established. The proposed theoretical and numerical models were verified by tensile, compressive, and shear test results. The outcomes of this study indicated that both theoretical, numerical prediction values agree well with experimental verification results confirming the validity of the proposed methodology in providing a reliable reference for structural design of pultruded fiber reinforced polymeric (FRP) composite structures

Experimental and Numerical Characterization of PFRP Structural Elements with Stiffened Web-Flange Junctions

The research presented herein pertains to the experimental characterization and numerical simulation of the behavior of pultruded Glass Fiber-Reinforced Polymer (GFRP) structural elements, with specific attention devoted to enhancing ultimate capacity of the Web-Flange Junctions (WFJs). An experimental campaign, performed on as-manufactured I-beam specimens is conducted to serve as a baseline for comparing behavior of pultruded GFRP members with the proposed stiffening strategy. The specimens were produced through the addition of external elements, using bonded L-shaped profiles with variable lengths that were installed in the proximity of the WFJ zone of the I-beams. The experimental tests aimed at highlighting the inherent premature failure that potentially occurs at the WFJ as a result of lack of reinforcement continuity between the flanges and the web that are required to withstand localized radial stress concentration at these locations. To this end, the top flanges of the thin-walled GFRP I-beams were clamped while a localized concentrated load was applied on the bottom flange by means of a steel jaw. Two sets of tests were performed, namely Mid-Point (MP) and End-Point (EP), according to the location of the applied load that caused delamination, and eventually separation of the bottom flange from the web. Failure modes observed in the tests, together with experimental load–displacement curves, are used to investigate the influence of external stiffeners length on the ultimate strength and stiffness of the I-beams. In executing the tests, Digital Image Correlation (DIC) techniques were used to track the spatial distribution of the deformation in the elements. Based on the results of the experimental campaign, a numerical investigation was conducted, to characterize the influence of different stiffeners’ arrangements on the mechanical response of the GFRP elements. The computational model was validated by comparing the observed response, both in terms of measured force–displacement curves, and bi-dimensional displacement maps obtained by means of the DIC technique. Numerical results highlighted the importance and influence of an explicit representation of the mechanical response of the bonding agent (i.e., the epoxy resin used to attach the stiffeners to the I-beams) to correctly characterize the deformation behavior of the strengthened WFJs. © 2022 Elsevier Lt

Effect of phototherapy on eosinophils count in neonatal hyperbilirubinemia (cross-sectional study)

Abstract Background Neonatal jaundice is a common disorder in neonates. Phototherapy is associated with various side effects despite being safe. This research aimed to determine the impact of phototherapy (PT) on eosinophil levels in neonates treated for unconjugated hyperbilirubinemia. Methods In this cross-sectional prospective study, icteric neonates admitted to the Neonatal Intensive Care Unit (NICU) of Abo-Elreesh Child Hospital, Cairo University, from July 2020 to June 2021 were assessed. Laboratory data, including serum bilirubin and blood cell differentiation for eosinophils before and after phototherapy, were collected, and demographic data like age, gender, gestational age, and duration of phototherapy were taken. Results Two hundred neonates were included in this study. Hyperbilirubinemia was most frequently related to ABO group incompatibility (44.5%). After phototherapy, total serum bilirubin and neutrophil levels were significantly decreased, and platelet levels were significantly increased. Eosinophil count and percent were significantly increased (p < 0.001) following phototherapy. A statistically significant positive correlation was found between eosinophil count before and after PT (r = 0.583, p < 0.001) and between eosinophil percent before and after PT (r = 0.617, p < 0.001). Conclusion Serum eosinophils were increased after phototherapy in icteric neonates with hyperbilirubinemia

Engineered Nanomaterials as Potential Candidates for HIV Treatment: Between Opportunities and Challenges

Nanomaterials have received considerable attention due to their unique properties; they have high surface area compared to volume ratio, giving them superior chemical, optical and thermal characteristics. Nanomaterials have also both diagnostic and therapeutic applications. In this mini review, we are highlighting valuable data about human immunodeficiency virus (HIV), its relationship with cancer and its potential treatment with some nanomaterials such as silver nanoparticles (Ag NPs)