An extended probabilistic method for reliability analysis under mixed aleatory and epistemic uncertainties with flexible intervals

The reliability analysis approach based on combined probability and evidence theory is studied in this paper to address the reliability analysis problem involving both aleatory uncertainties and epistemic uncertainties with flexible intervals (the interval bounds are either fixed or variable as functions of other independent variables). In the standard mathematical formulation of reliability analysis under mixed uncertainties with combined probability and evidence theory, the key is to calculate the failure probability of the upper and lower limits of the system response function as the epistemic uncertainties vary in each focal element. Based on measure theory, in this paper it is proved that the aforementioned upper and lower limits of the system response function are measurable under certain circumstances (the system response function is continuous and the flexible interval bounds satisfy certain conditions), which accordingly can be treated as random variables. Thus the reliability analysis of the system response under mixed uncertainties can be directly treated as probability calculation problems and solved by existing well-developed and efficient probabilistic methods. In this paper the popular probabilistic reliability analysis method FORM (First Order Reliability Method) is taken as an example to illustrate how to extend it to solve the reliability analysis problem in the mixed uncertainty situation. The efficacy of the proposed method is demonstrated with two numerical examples and one practical satellite conceptual design problem.Aerodynamics, Wind Energy & Propulsio

Edge computing assisted autonomous flight for UAV: Synergies between vision and communications

Autonomous flight for UAVs relies on visual information for avoiding obstacles and ensuring safe collision-free flight. In addition to visual clues, safe UAVs often need connectivity with the ground station. In this article, we study the synergies between vision and communications for edge-computing-enabled UAV flight. By proposing a framework of edge computing assisted autonomous flight (ECAAF), we illustrate that vision and communications can interact with and assist each other with the aid of edge computing and offloading, and further speed up UAV mission completion. ECAAF consists of three functionalities that are discussed in detail: edge computing for 3D map acquisition, radio map construction from the 3D map, and online trajectory planning. During ECAAF, the interactions of communication capacity, video offloading, 3D map quality, and channel state of the trajectory form a positive feedback loop. Simulation results verify that the proposed method can improve mission performance by enhancing connectivity. Finally, we conclude with some future research directions.Accepted Author ManuscriptLearning & Autonomous Contro

Repression of hypoxia-inducible factor alpha signaling by Set7-mediated methylation

Hypoxia-inducible factor (HIF)-1 alpha and HIF-2 alpha are the main regulators of cellular responses to hypoxia. Post-translational modifications of HIF-1 alpha and 2 alpha are necessary to modulate their functions. The methylation of non-histone proteins by Set7, an SET domain-containing lysine methyltransferase, is a novel regulatory mechanism to control cell protein function in response to various cellular stresses. In this study, we show that Set7 methylates HIF-1 alpha at lysine 32 and HIF-2 alpha at lysine K29; this methylation inhibits the expression of HIF-1 alpha/2 alpha targets by impairing the occupancy of HIF-alpha on hypoxia response element of HIF target gene promoter. Set7-null fibroblasts and the cells with shRNA-knocked down Set7 exhibit upregulated HIF target genes. Set7 inhibitor blocks HIF-1 alpha/2 alpha methylation to enhance HIF target gene expression. Set7-null fibroblasts and the cells with shRNA-knocked down Set7 or inhibition of Set7 by the inhibitor subjected to hypoxia display an increased glucose uptake and intracellular adenosine triphosphate levels. These findings define a novel modification of HIF-1 alpha/2 alpha and demonstrate that Set7-medited lysine methylation negatively regulates HIF-alpha transcriptional activity and HIF-1 alpha-mediated glucose homeostasis