http://popups.lib.uliege.be/1373-5411/index.php?id=2460 Publications of Auteurs Gundars Bērziņš fr 0 http://popups.lib.uliege.be/1373-5411/index.php?id=2836 For important fatigue-sensitive structures of aircraft whose breakdowns cause serious accidents, it is required to keep their reliability extremely high. In this paper, we discuss inspection strategies for such important structures against fatigue failure. The focus is on the case when there are fatigue-cracks unexpectedly detected in a fleet of aircraft within a warranty period (prior to the first inspection). The paper examines this case and proposes stochastic models for prediction of fatigue-crack growth to determine appropriate inspections intervals. We also do not assume known parameters of the underlying distributions, and the estimation of that is incorporated into the analysis and decision-making. Numerical example is provided to illustrate the procedure. Tue, 03 Sep 2024 15:00:02 +0200 Thu, 10 Oct 2024 16:16:27 +0200 http://popups.lib.uliege.be/1373-5411/index.php?id=2836 http://popups.lib.uliege.be/1373-5411/index.php?id=2741 Based on a random sample from the Weibull distribution with unknown shape and scale parameters, lower and upper prediction limits on a set of m future observations from the same distribution are constructed. The procedures, which arise from considering the distribution of future observations given the observed value of an ancillary statistic, do not require the construction of any tables, and are applicable whether the data are complete or Type II censored. The results have direct application in reliability theory, where the time until the first failure in a group of m items in service provides a measure regarding the operation of the items, as well as in service of fatigue-sensitive aircraft structures to construct strategies of inspections of these structures ; examples of applications are given. Fri, 30 Aug 2024 15:11:10 +0200 Thu, 10 Oct 2024 16:28:03 +0200 http://popups.lib.uliege.be/1373-5411/index.php?id=2741 http://popups.lib.uliege.be/1373-5411/index.php?id=2459 Project portfolio investment is a crucial decision in many organizations, which must make informed decisions on investment, where the appropriate distribution of investment is complex, due to varying levels of risk, resource requirements, and interaction among the proposed projects. In this paper, we discuss an analytical optimal solution to the mean-variance formulation of the problem of optimization of multiperiod investment strategy for project portfolio. Specifically, analytical optimal multiperiod investment strategy for project portfolio is derived. An efficient algorithm is proposed in order to maximize the expected value of the terminal wealth under constraint that the variance of the terminal wealth is not greater than a preassigned risk level or to minimize the variance of the terminal wealth under constraint that the expected terminal wealth is not smaller than a preassigned level. A numerical example is given. Thu, 22 Aug 2024 10:03:16 +0200 Thu, 10 Oct 2024 09:46:52 +0200 http://popups.lib.uliege.be/1373-5411/index.php?id=2459