In this paper, we develop a generalized multi-state degraded system reliability model subject to multiple competing failure processes, including two degradation processes, and random shocks. The ...operating condition of the multi-state systems is characterized by a finite number of states. We also present a methodology to generate the system states when there are multi-failure processes. The model can be used not only to determine the reliability of the degraded systems in the context of multi-state functions, but also to obtain the states of the systems by calculating the system state probabilities. Several numerical examples are given to illustrate the concepts.
In some applications, the failure rate of the system depends not only on the time, but also upon the status of the system, such as vibration level, efficiency, number of random shocks on the system, ...etc., which causes degradation. In this paper, we develop a generalized condition-based maintenance model subject to multiple competing failure processes including two degradation processes, and random shocks. An average long-run maintenance cost rate function is derived based on the expressions for the degradation paths & cumulative shock damage, which are measurable. A geometric sequence is employed to develop the inter-inspection sequence. Upon inspection, one needs to decide whether to perform a maintenance, such as preventive or corrective, or to do nothing. The preventive maintenance thresholds for degradation processes & inspection sequences are the decision variables of the proposed model. We also present an algorithm based on the Nelder-Mead downhill simplex method to calculate the optimum policy that minimizes the average long-run maintenance cost rate. Numerical examples are given to illustrate the results using the optimization algorithm.
Flocculation has a great influence on the biogeochemical cycle by altering the particle size, density and settling velocity of suspended particulate matter (SPM) from coastal to shelf sea areas. ...However, the flocculation process in the shelf sea areas of China has not been systematically studied. In this study, the influencing mechanism of the North Yellow Sea cold water mass (NYSCWM) on the distribution and flocculation process of SPM is studied based on a comprehensive investigation during the summer of 2016. The results revealed that the mass concentration and turbidity of SPM showed a decreasing trend from coastal to offshore areas and an increasing trend from surface to near-benthic layers. Sediments from the Shandong subaqueous clinoform that were resuspended by the tidal mixing effect were the main source of inorganic SPM in the North Yellow Sea in summer. The existence of the bottom cold water mass enhanced the thermocline and pycnocline in the North Yellow Sea shelf area. The pycnocline obstructed the vertical diffusion of nutrients in the NYSCWM, resulting in a subsurface maximum chlorophyll a (chl a) layer, which further contributed to the maximum subsurface volume concentration of SPM. Flocculation was ubiquitous in the study area and was the main reason for the asynchronous variability in the mass concentration, turbidity and volume concentration of SPM. Three different kinds of flocculation mechanisms were identified, including the effects of biological activities in water masses above the NYSCWM, physicochemical effects in the near-benthic nepheloid layer within the NYSCWM, and their combined effects in shallow coastal areas. The flocculation of SPM enhanced the transport of particles from the surface to the bottom of the water column and made an important contribution to the formation of the North Yellow Sea mud deposit.
•The CWM changed the marine physical and biological environments, resulting in variations in SPM flocculation conditions.•Three flocculation mechanisms, dominated by biological activity, physicochemical effects and their coeffects are proposed.•The flocculation processes of SPM play important roles in the formation of mud deposits in the North Yellow Sea.
Respiratory syncytial virus (RSV) is the main cause of acute lower respiratory tract infection (ALRI) in children worldwide. Virus-host interactions affect the progression and prognosis of the ...infection. Autophagy plays important roles in virus-host interactions. Respiratory epithelial cells serve as the front line of host defense during RSV infection, However, it is still unclear how they interact with RSV. In this study, we found that RSV induced autophagy that favored RSV replication and exacerbated lung pathology
Mechanistically, RSV induced complete autophagy flux through reactive oxygen species (ROS) generation and activation of the AMP-activated protein kinase/mammalian target of rapamycin (AMPK-MTOR) signaling pathway in HEp-2 cells. Furthermore, we evaluated the functions of autophagy in RSV replication and found that RSV replication was increased in HEp-2 cells treated with rapamycin but decreased remarkably in cells treated with 3-methylademine (3-MA) or wortmannin. Knockdown key molecules in the autophagy pathway with short hairpinp RNA (shRNA) against autophagy-related gene 5 (
), autophagy-related gene 7 (
), or
or treatment with ROS scavenger N-acetyl-l-cysteine (NAC) and AMPK inhibitor (compound C) suppressed RSV replication. 3-MA or sh
significantly decreased cell viability and increased cell apoptosis at 48 hours postinfection (hpi). Blocking apoptosis with Z-VAD-FMK partially restored virus replication at 48 hpi. Those results provide strong evidence that autophagy may function as a proviral mechanism in a cell-intrinsic manner during RSV infection.
An understanding of the mechanisms that respiratory syncytial virus utilizes to interact with respiratory epithelial cells is critical to the development of novel antiviral strategies. In this study, we found that RSV induces autophagy through a ROS-AMPK signaling axis, which in turn promotes viral infection. Autophagy favors RSV replication through blocking cell apoptosis at 48 hpi. Mechanistically, RSV induces mitophagy, which maintains mitochondrial homeostasis and therefore decreases cytochrome
release and apoptosis induction. This study provides a novel insight into this virus-host interaction, which may help to exploit new antiviral treatments targeting autophagy processes.
This study aims to validate the efficacy of the conventional non-invasive score in predicting significant fibrosis in metabolic-associated fatty liver disease (MAFLD) and to develop a non-invasive ...prediction model for MAFLD.
This cross-sectional study was conducted among 7701 participants with MAFLD from August 2018 to December 2023. All participants were divided into a training cohort and a validation cohort. The study compared different subgroups' demographic, anthropometric, and laboratory examination indicators and conducted logistic regression analysis to assess the correlation between independent variables and liver fibrosis. Nomograms were created using the logistic regression model. The predictive values of noninvasive models and nomograms were evaluated using receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA).
Four nomograms were developed for the quantitative analysis of significant liver fibrosis risk based on the multivariate logistic regression analysis results. The nomogram's area under ROC curves (AUC) was 0.710, 0.714, 0.748, and 0.715 in overall MAFLD, OW-MAFLD, Lean-MAFLD, and T2DM-MAFLD, respectively. The nomogram had a higher AUC in all MAFLD participants and OW-MAFLD than the other non-invasive scores. The DCA curve showed that the net benefit of each nomogram was higher than that of APRI and FIB-4. In the validation cohort, the AUCs of the nomograms were 0.722, 0.750, 0.719, and 0.705, respectively.
APRI, FIB-4, and NFS performed poorly predicting significant fibrosis in patients with MAFLD. The new model demonstrated improved diagnostic accuracy and clinical applicability in identifying significant fibrosis in MAFLD.
With the advantages of being lightweight, flexible, and wearable, wire-shaped supercapacitors have received tremendous attention in wearable and portable power sources in recent years. Considering ...the demands for large-scale applications, it is necessary to explore a facile and convenient preparation approach for wire-shaped supercapacitors. Herein, we reported a simple approach to fabricate wire-shaped electrodes by a dipping method, which possessed a nitric acid-activated graphite fiber core and an activated carbon-coating layer structure. Parallel and symmetric all-solid-state wire-shaped supercapacitors (PWSCs) based on the electrodes were fabricated. The as-fabricated PWSC showed high energy density (6.60 W h/kg, 8.08 mW h/cm, and 1 mV/s) and power density (253 mW/kg, 0.31 mW/cm, and 100 mV/s) and excellent flexibility. Furthermore, this wire-shaped supercapacitor may bring broader application prospects for energy storage devices in future wearable electronic areas.
Acute coronary syndrome (ACS) is a serious cardiovascular disease. The ACS risk prediction model is of great significance during the hospitalisation of ACS patients. However, traditional machine ...learning methods are not effective in predicting risk events in the ACS treatment process because of sample imbalance and noise. In this letter, the multilayer perceptron (MLP) and ensemble method are combined and then ensemble‐MLPs are proposed, which has made two innovations: 1) increase the diversity of the base MLP classifier at the data level, structure level, and parameter level and 2) improve the ensemble performance by proposing a new ensemble method using f1‐score weighted average. Experiments have shown that the proposed method outperforms conventional ensemble MLP method and other traditional machine learning methods on the task of predicting risk events in the ACS treatment process.
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