http://popups.lib.uliege.be/1373-5411/index.php?id=2188 Publications of Auteurs Uldis Rozevskis fr 0 http://popups.lib.uliege.be/1373-5411/index.php?id=3198 In this paper, a control theory is used for planning inspections in service of fatigue-sensitive aircraft structure components under crack propagation. One of the most important features of control theory is its great generality, enabling one to analyze diverse systems within one unified framework. A key idea, which has emerged from this study, is the necessity of viewing the process of planning in-service inspections as an adaptive control process. Adaptation means the ability of self-modification and self-adjustment in accordance with varying conditions of environment. The adaptive control of inspection planning process in service of fatigued aircraft structures differs from ordinary stochastic control of inspection planning process in that it attempts to reevaluate itself in the light of uncertainties in service of aircraft structures as they unfold and change. Thus, a catastrophic accident during flight can be avoided. Wed, 11 Sep 2024 17:02:22 +0200 Thu, 10 Oct 2024 16:27:31 +0200 http://popups.lib.uliege.be/1373-5411/index.php?id=3198 http://popups.lib.uliege.be/1373-5411/index.php?id=2479 System failures are usually observed during regular maintenance or inspection and this is especially the case for systems in standby or storage, which is common for safety critical systems. A periodic inspection policy is usually adopted. During the inspection, a lot of information is gained about the status of the system. Such information should be used in deciding upon the time for the next inspection. Hence sequential inspection is more appropriate, especially when the aging property of the system is unknown, and has to be estimated with the information from inspection. In this paper, a model is developed and sequential inspection strategies are studied in this situation. The focus is on the case when there are multiple systems inspected at the same, but discrete times. We also do not assume a known distribution of the system lifetime, and the estimation of that is incorporated into the analysis and decision-making. An availability criterion is considered and numerical example is provided to illustrate the procedure. Thu, 22 Aug 2024 15:52:11 +0200 Thu, 22 Aug 2024 15:52:17 +0200 http://popups.lib.uliege.be/1373-5411/index.php?id=2479 http://popups.lib.uliege.be/1373-5411/index.php?id=2184 A primary application of regression analysis is prediction. In this paper, we consider the definition of the domain of the model in which prediction is valid. This is important because prediction made outside the domain may be unacceptably different from the true responses. We provide a criterion that can be used to decide whether prediction is valid at a certain point. The criterion is based on the existence of an unbiased estimate of the distribution function associated to the "future" observation. In addition, in the context of regression analysis, the categorical control problem that is quite different from the numerical control problem in the setting of the target is considered. Categorical control may be compared to interval prediction, whereas numerical control is compared to point prediction. Our derivation is based on the Scheffé-type simultaneous tolerance interval at two distinct points. Tue, 30 Jul 2024 12:43:28 +0200 Tue, 30 Jul 2024 12:43:35 +0200 http://popups.lib.uliege.be/1373-5411/index.php?id=2184