The evolution of system reliability depends on its structure as well as on the evolution of its components reliability. The latter is a function of component age during a system’s operating life. Component aging is strongly affected by maintenance activities performed on the system. In this work, we consider two categories of maintenance activities: corrective maintenance (CM) and preventive ma...

In a distributed system, the actions of one component may lead to severe failures in the system as a whole. To govern such systems, constraints are placed on the behaviour of components to avoid such undesirable actions. Policies or norms are declarations of soft constraints regulating what is prohibited, permitted or obliged within a distributed system. These constraints provide systems-level ...

This document describes a model for failures in dependable systems. A general failure model is described in terms of a system consisting of interacting components. This model is then applied to an object-based interaction model. The model is based on events which occur with some value at some time. Components in the system observe events and have expectations which define regions in a value, ti...

thiopental sodium is an ultra short-acting barbiturate. due to its redistribution characteristic, its first injection has a short term effect. in order to elongate its anesthesia duration, more injections are needed. as these additional injections extend the recovery length , weaken respiration and causes other dangerous effects; its repeated use is considered unsafe. citicoline is a natural su...

gastric cancer is the most prevalent cancer among men and the third most prevalent cancer among women in iran. its most important reason for death is its belated diagnosis at the advanced stages of the disease. various factors can be effective on the survival of these patients after surgery, which are the major concern in this study.data from 330 patients with gastric cancer who had undergone s...

the sources of groundwater pollution such as, industrial effluents, sewage and extensive farming have lead to agrochemical pollution. mathematical modeling helps to analyze the existing situation, allows forecasting, and to evaluate the effects of changes in the surrounding water quality. the present research has been focused mainly towards understanding the various processes affecting the tran...