The high reliability of modern engineering systems is achieved by performing predictive maintenance. Mathematical models based on stochastic timed colored Petri nets are an effective tool for developing complex production processes Industry 4.0. This article discusses the maintainability evaluation used in hierarchical net models. simulation model was built using nets, and constructed with four...

Stochastic comparison results for replacement policies are shown in this paper using formalism of point processes theory. At each failure moment a repair is allowed performed with a random degree of repair including as special cases perfect, minimal, imperfect repair models. Results for such repairable systems with schemes of planned replacements are also shown. The results are obtained by coup...

background a gunshot wound to the lower extremity with combined skeletal and vascular injuries can be difficult to manage. in clinical practice, it is not always possible to assemble a multispecialty team to work seamlessly to attain this goal, and the end result may be unnecessary prolonged ischemic time. a covered endovascular stent (evs) can be used initially to restore perfusion without nee...

this paper analyzes a controllable discrete-time machine repair problem withl operating machines and two repairmen. the number of working servers can be adjusteddepending on the number of failed machines in the system one at a time at machine's failure orat service completion epochs. analytical closed-form solutions of the stationary probabilities ofthe number of failed machines in the sys...

background: considering that complications and outcome of each method of pediatric inguinal hernia repair are one of the determinants for pediatric surgeons for selection of the appropriate surgical technique, we compared the early and late complications of two inguinal repair techniques, with and without opening the external oblique muscle fascia. materials and methods: in this double-blind cl...

The present paper deals with the reliability and fault analysis of a stochastic model for two non-identical units, in which first unit is kept as operative other sub-standard one. may be repaired or replaced by another on its failure, depending cost repairing/replacement. Failure repair times are considered correlated using bivariate point exponential distribution. Analysis system done to find ...

  Background: The standard method for repair of an injured peripheal nerve is epineural repair with separate sutures. Herein we describe a method in which the nerve is sutured with continous sutures. In fact this method has not been utilized for nerve repair previously and our purpose was to compare it to the standard method. If it proved to be successful it would replace the standard method in...

The emergence of corona virus (COVID-19) has create a great public concern as the outbreak is still ongoing and government are taking actions such as holiday extension, travel restriction, temporary closure of public work place, borders, schools, quarantine/isolation, social distancing and so on. To mitigate the spread, we proposed and analyzed a stochastic model for the continue spread of coro...