Paulo José de Freitas Filho

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Several studies have been conducted in order to understand the 'software aging' phenomenon. This paper presents the results of an experimental research work, which evaluated the software aging effects on a Web server as well as the performance of a rejuvenation agent. Its main contribution is the identification and analytical validation of the factors that(More)
In the past ten years, the software aging phenomenon has been systematically researched, and recognized by both academic, and industry communities as an important obstacle to achieving dependable software systems. One of its main effects is the depletion of operating system resources, causing system performance degradation or crash/hang failures in running(More)
In the last few years, the call center industry has considerably grown especially the outbound call center area, such as telemarketing. The productivity of the call centers has significantly increased, but they still require improvements especially because of the need to adapt their operations in some countries, like the UK and the USA, in which the silent(More)
This paper intends to show how two different methodologies, a Monte Carlo simulation method and a connectionist approach can be used to estimate the total time assessment in drilling and completion operations of oil wells in deep waters. The former approach performs a Monte Carlo simulation based on data from field operations. In the later one, correlations(More)
Call Centers are important channels of communication within the consumer relationship and a point of integration between suppliers and their customers. Correctly sizing the capacity of a given Call Center can bring benefits not only in terms of improved customer service (efficacy), but also in terms of reduced operating costs (efficiency). However,(More)
Nearly every well installation process nowadays relies on some sort of risk assessment study, given the high costs involved. Those studies focus mostly on estimating the total time required by the well drilling and completion operations, as a way to predict the final costs. Among the different techniques employed, the Monte Carlo simulation currently stands(More)
The call center industry has expanded greatly over recent years and it is constantly striving to increase business efficiency and customer service effectiveness. Incoming call volume forecasting algorithms are used in inbound call centers to predict the demand for services and, as a result, to plan resource allocation. However, a number of phenomena can(More)
It is well known that randomness is present in daily life and that often it is desirable to recognize inherent characteristics of this randomness. Probability theory describes a quantification of the uncertainty associated with this randomness. Based on probability theory, the present research describes an alternative methodology to the traditional(More)
In this work, we applied modeling and simulation to plan and evaluate the capacity of a real enterprise voice gateway system. We modeled the analyzed voice gateway and assessed it under different workload scenarios. We evaluated the actual setup under the real current workload demand, as well as future expected demands in terms of voice long-distance calls(More)