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A model-based prognostics method for fatigue crack growth in fuselage panels

Chinese Journal of Aeronautics 2019年第2期32卷 396-408页

作者： Yiwei WANG christian GOGU Nicolas BINAUD christian bes Jian FU School of Mechanical Engineering and Automation Beihang University Institut Clément Ader (UMR CNRS 5312) INSA/UPS/ISAE/Mines Albi Université de Toulouse

This paper proposes a model-based prognostics method that couples the Extended Kalman Filter(EKF) and a new developed linearization method. The proposed prognostics method is developed in the context of fatigue crack propagation in fuselage panels where the model parameters are unknown and the crack propagation is affected by different types of uncertainties. The coupled method is composed of two steps. The first step employs EKF to estimate the unknown model parameters and the current damage state. In the second step, the proposed efficient linearization method is applied to compute analytically the statistical distribution of the damage evolution path in some future time. A numerical case study is implemented to evaluate the performance of the proposed method. The results show that the coupled EKF-linearization method provides satisfactory results: the EKF algorithm well identifies the model parameters, and the linearization method gives comparable prediction results to Monte Carlo(MC) method while leading to very significant computational cost saving. The proposed prognostics method for fatigue crack growth can be used for developing predictive maintenance strategy for an aircraft fleet, in which case, the computational cost saving is significantly meaningful.

关键词： Aircraft fuselage panels Extended Kalman filter Fatigue crack propagation Linearization method Model-based prognostics

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A cost driven predictive maintenance policy for structural airframe maintenance

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Chinese Journal of Aeronautics 2017年第3期30卷 1242-1257页

作者： Yiwei WANG christian GOGU Nicolas BINAUD christian bes Raphael T.HAFTKA Nam H.KIM Universite de Toulouse INSA/UPS/ISAE/Mines Albi ICA UMR CNRS 5312 Toulouse 31400 Frallce Department of Mechanical & Aerospace Engineering University of Florida Gainesville 32611 USA

Airframe maintenance is traditionally performed at scheduled maintenance *** decision to repair a fuselage panel is based on a fixed crack size threshold,which allows to ensure the aircraft safety until the next scheduled maintenance *** progress in sensor technology and data processing techniques,structural health monitoring（SHM） systems are increasingly being considered in the aviation *** systems track the aircraft health state continuously,leading to the possibility of planning maintenance based on an actual state of aircraft rather than on a fixed *** paper builds upon a model-based prognostics framework that the authors developed in their previous work,which couples the Extended Kalman filter（EKF） with a firstorder perturbation（FOP） *** using the information given by this prognostics method,a novel cost driven predictive maintenance（CDPM） policy is proposed,which ensures the aircraft safety while minimizing the maintenance *** proposed policy is formally derived based on the trade-off between probabilities of occurrence of scheduled and unscheduled maintenance.A numerical case study simulating the maintenance process of an entire fleet of aircrafts is *** the condition of assuring the same safety level,the CDPM is compared in terms of cost with two other maintenance policies：scheduled maintenance and threshold based SHM *** comparison results show CDPM could lead to significant cost savings.

关键词： Extended Kalman filter First-order perturbation method Model-based prognostic Predictive maintenance Structural airframe maintenance

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Potassium Bromate-induced Changes in the Adult Mouse Cerebellum Are Ameliorated by Vanillin

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Biomedical and Environmental Sciences 2018年第2期31卷 115-125页

作者： Hajer Ben Saad Dorra Driss Imen Jaballi Hanen Ghozzi Ons Boudawara Michael Droguet christian Magne Monsef Nasri Khaled Mounir Zeghal Ahmed Hakim Ibtissem Ben Amara Laboratory of Pharmacology University of SfaxFaculty of Medicine3029 SfaxTunisia Laboratory of Enzyme engineering and Microbiology National Engineering School in SfaxUniversity of SfaxB.P.11733038 SfaxTunisia Centre of Biotechnology of Sfax P.O.Box 11773018 SfaxTunisia Anatomopathology Laboratory University of SfaxHabib Bourguiba Hospital3029 SfaxTunisia EA 4324 ORPHY Faculty of MedicineUniversity of Brest29238 Brest CedexFrance EA 2219 Geoarchitecture University of BrestUFR Sciences&Techniques29238 Brest Cedex 3France

Objective The current study aimed to elucidate the effect of vanillin on behavioral changes, oxidative stress, and histopathological changes induced by potassium bromate （KBrO3）, an environmental pollutant, in the cerebellum of adult *** The animals were divided into four groups： group 1 served as a control, group 2 received KBrO3, group 3 received KBrO3 and vanillin, and group 4 received only vanillin. We then measured behavioral changes, oxidative stress, and molecular and histological changes in the *** We observed significant behavioral changes in KBrO3-exposed mice. When investigating redox homeostasis in the cerebellum, we found that mice treated with KBrO3 had increased lipid peroxidation and protein oxidation in the cerebellum. These effects were accompanied by decreased Na＋-K＋ and Mg2＋ ATPase activity and antioxidant enzyme gene expression when compared to the control group. Additionally, there was a significant increase in cytokine gene expression in KBrO3-treated mice. Microscopy revealed that KBrO3 intoxication resulted in numerous degenerative changes in the cerebellum that were substantially ameliorated by vanillin supplementation. Co-administration of vanillin blocked the biochemical and molecular anomalies induced by *** Our results demonstrate that vanillin is a potential therapeutic agent for oxidative stress associated with neurodegenerative diseases.

关键词： Cerebellum Behavior Potassium bromate Vanillin ATPases Genes expression

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Performance characteristics of retrograde single-balloon endoscopy: A single center experience

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World Journal of Gastrointestinal Endoscopy 2016年第15期8卷 501-507页

作者： Kaci E christian Karan Kapoor Eric M Goldberg Department of Medicine Division of Gastroenterology University of Maryland Medical Center

AIM: To evaluate the technical success, diagnostic yield(DY) and therapeutic potential of retrograde single balloon enteroscopy(rS BE). METHODS: A retrospective review of 136 rS BE procedures performed at a tertiary academic referral center from January 2006 and September 2013 was completed. Patient characteristics including age, gender and inpatient status were collected. The indication for the procedure was categorized into one of three groups: Obscure gastrointestinal bleeding(GIB), evaluation for Crohn's disease and abnormal imaging. Procedural characteristics including insertion depth(ID), procedure time, concordance with pre-procedural imaging and complications were also recorded. Lastly, DY, defined as the percentage of cases producing either a definitive diagnosis or findings that could explain clinical symptoms and therapeutic yield(TY), defined as the percentage of cases in which a definitive intervention was performed, were determined. Mucosal tattooing and biopsy alone were not included in the TY. RESULTS: A total of 136 rS BE procedures were identified. Mean patient age was 57.5(± 16.2) years, 67(49.2%) were male, and 110(80.9%) procedures were performed on an outpatient basis. Indications for rS BE included GIB in 55(40.4%), evaluation of inflammatory bowel disease(IBD) in 29(21.3%), and imaging suggestive of pathology other than GIB or IBD in 43(31.6%). Nine(6.6%) rS bes were performed for other indications. Mean ID was 68.3(± 39.3) cm proximal to the ileocecal valve and mean time to completion was 41.7(± 15.5) min. Overall, 73(53.7%) cases were diagnostic and 25(18.4%) cases were therapeutic in which interventions(argon plasma coagulation, stricture dilatation, polypectomy, etc.) were performed. Pre-procedural imaging was performed in 88(64.7%) patients. Endoscopic concordance of positive imaging findings was seen in 31(35.2%) cases. Follow up data was available in 93(68.4%) patients; 2(2.2%) reported post-procedural abdominal pain within 30 d follow

关键词： Retrograde Single-balloon Enteroscopy Endoscopy

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