Queues with retrial/self-generation of priorities /postponement of work and some related reliability problems

Application of Queueing theory in areas like Computer networking, ATM facilities, Telecommunications and to many other numerous situation made people study Queueing models extensively and it has become an ever expanding branch of applied probability. The thesis discusses Reliability of a ‘k-out-of-n system’ where the server also attends external customers when there are no failed components (main customers), under a retrial policy, which can be explained in detail. It explains the reliability of a ‘K-out-of-n-system’ where the server also attends external customers and studies a multi-server infinite capacity Queueing system where each customer arrives as ordinary but can generate into priority customer which waiting in the queue. The study gives details on a finite capacity multi-server queueing system with self-generation of priority customers and also on a single server infinite capacity retrial Queue where the customer in the orbit can generate into a priority customer and leaves the system if the server is already busy with a priority generated customer; else he is taken for service immediately. Arrival process is according to a MAP and service times follow MSP.

Patterns of alcohol use between genders: A cross-cultural evaluation

Introduction: Alcohol use by men and women is very much influenced by social habits and customs. Cultural peculiarities and biological differences between the sexes require more focused and standardized studies. The objective was to systematize information on patterns of alcohol use between the sexes.Method: A literary review (1972-2004) identified 96 publications (Lilacs, Scielo, Medline) and some related books.Results and conclusions: Men drank more and presented more problems (legal, family, social, clinical, traumas and mortality) associated with alcohol use; the consequences of alcohol use in developing countries with low death rates is even higher. Women can face more discrimination by using alcohol as well as worse health problems when they abuse drinking (liver, pancreas, and central and peripheral nervous system problems, psychiatric comorbidity, etc.); sexual abuse is more commonly associated with women than discussing the different responses to treatment. As for social roles/responsibilities exercised by women, there are indications that marriage, employment, and children have a good influence, discouraging alcohol use, while divorce, unemployment, and no children contribute to higher consumption. For both sexes, religion was a protective factor for alcohol use; acculturation was a strong influence in the pattern of alcohol use, and alcohol worsened the evolution of existing psychiatric disorders. (c) 2006 Elsevier B.V. All rights reserved.

Alcohol use and falls among the elderly in Metropolitan São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Problems related to the employment of thin uranium films as neutron dosimeters

Thin uranium films built on muscovite mica basis and obsidian samples having known ages were irradiated with thermal neutrons at the IPEN/CNEN reactor, São Paulo. Comparing thin film performance with the obsidian one, it was observed that the latter feel a greater neutron fluence. Nominal fluences at the used facility are in agreement with the results obtained analysing the obsidian samples. A probable hypothesis to explain this disagreement, namely, the uranium loss from the thin films, was ruled out. © 1995.

Vibration and oil analysis for monitoring problems related to water contamination in rolling

Trying to reduce particle contamination in lubrication systems, industries of the whole world spend millions of dollars each year on the improvement of filtration technology. In this context, by controlling fluid cleanliness, some companies are able to reduce failures rates up to 85 percent. However, in some industries and environments, water is a contaminant more frequently encountered than solid particles, and it is often seen as the primary cause of component failure. Only one percent of water in oil is enough to reduce life expectancy of a journal bearing by 80 percent. For rolling bearing elements, the situation is worse because water destroys the oil film and, under the extreme temperatures and pressures generated in the load zone of a rolling bearing element, free and emulsified water can result in instantaneous flash-vaporization giving origin to erosive wear. This work studies the effect of water as lubricant contaminant in ball bearings, which simulates a situation that could actually occur in real systems. In a designed bench test, three basic lubricants of different viscosities were contaminated with different contents of water. The results regarding oil and vibration analysis are presented for different bearing speeds.