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Manuel Alberto M. Ferreira

Publications and source records attributed to Manuel Alberto M. Ferreira.

At least 37 records · Page 2Linked to original sources
arXiv2021

Nanotechnology and Processes The NanoPhotovoltaic Panels

Nanotechnology may work as a powerful weapon to be used for creating competitive advantages in the energy market. Using the photovoltaic nano-panels, which may reduce considerably the production costs and meet simultaneously socio-environmental requirements demanded by law. It is a way to produce clean energy in innovative terms. Moreover, today the adoption of nanotechnology in energy production can make this kind of energy very interesting along the years. Nanotechnology may be responsible for considerable gains, both economically and the ones resulting from its contribution to protect the planet against pollution.

physics.soc-ph↗
arXiv2021

Infinite Servers Queue Systems Busy Period Time Length Distribution and Parameters Study through Computational Simulation

A FORTRAN program to simulate the operation of infinite servers queues is presented in this work. Poisson arrivals processes are considered but not only. For many parameters of interest in queuing systems study or application, either there are not theoretical results or, existing, they are mathematically intractable what makes their utility doubtful. In this case a possible issue is to use simulation methods in order to get more useful results. Indeed, using simulation, some experiences may be performed and the respective results used to conjecture about certain queue systems interesting quantities. In this paper this procedure is followed to learn something more about quantities of interest for those infinite servers queue systems, in particular about busy period parameters and probability distributions.

cs.PF↗
arXiv2021

Networks of Queues Models with Several Classes of Customers and Exponential Service Times

The main target of this paper is to present the Markov chain C that, not giving explicitly the queue lengths stationary probabilities, has the necessary information to its determination for open networks of queues with several classes of customers and exponential service times, allowing to overcome ingeniously this problem. The situation for closed networks, in the same conditions, much easier is also presented.

math.PR↗
arXiv2021

Studying Pensions Funds Through an Infinite Servers Nodes Network: A Theoretical Problem

This study intends to present a representation of a pensions fund through a stochastic network with two infinite servers nodes. With this representation it is allowed to deduce an equilibrium condition of the system with basis on the identity of the random rates expected values, for which the contributions arrive to the fund and the pensions are paid by the fund. In our study a stochastic network is constructed where traffic is represented. This network allows to study the equilibrium in the system and it is admissible to get a balance to a pensions fund. A specific case is studied. When the arrivals from outside at two nodes are according to Poisson processes, the system may be seen as a two nodes network where the first node is a MGinf queue and second a MtGinf queue. For this case in the long term the conditions of equilibrium are given by a very simple formula. In this formula it is established a relationship among the two nodes. Several examples are given in the study.

math.PR↗
arXiv2021

The Age or Excess of the MGinf Queue Busy Cycle Mean Value

In this work, approximate and exact results concerning a performance measure of the MGinf system, the age or the excess of the busy cycle, are presented. It will be seen that it is also a measure of the busy period performance. Service distributions for which it is given for a simple expression and others for which this does not happen are considered. For this last case, bounds are deduced. A special emphasis is given to the exponential distribution and to those related with it, useful in reliability theory.

math.PR↗
arXiv2021

Some notes on a semi-Markov matrix occurring in the MMinf queue parameters study

The main objective of this work is to present a process to compute the Markov renewal matrix for Markov renewal processes with countable infinite spaces, which semi-Markov matrixes are immigration and death type and assume a tridiagonal form. These processes occur often in practical applications. And the difficulty in obtaining friendly results for that matrix is a great obstacle to its application in practical cases modelling. It is considered the application to the MMinf queue particular case.

math.PR↗
arXiv2021

A Particular Collection of Service Time Distributions Parameters Study and Impact in some MGinf System Busy Period and Busy Cycle Parameters

The problems arising when the moments of service time distributions, for which the MGinf queue system busy period and busy cycle become very easy to study, are presented and it is shown how to overcome them. The busy cycle renewal function and the peakedness and the modified peakedness for the MGinf busy period and busy cycle in the case of those service time distributions are also computed.

math.PR↗
arXiv2021

A MGinf Queue Busy Period Distribution Characterizing Parameter

In this work it is proposed a parameter, η, to characterize the MGinf Queue Busy Period distribution that is a modification of the peakedness proposed in Whitt (1984). As this distribution moments centered at the origin are given, in general, by very complex expressions it is relevant to search for parameters simpler but with good descriptive properties.

math.PR↗
arXiv2021

Modelling and Differential Costs Evaluation of a Two Echelons Repair System through Infinite Servers Nodes Queuing Networks

After a short report of results on infinite servers queues systems, focusing on its busy period, using networks of queues with infinite servers nodes a model is constructed to study a two echelons repair system. These repair systems may be useful, for instance, in the operation of a fleet of aircraft, of shipping or of trucks. Additionally, it is shown how this model may be used in the evaluation of differential costs.

math.PR↗
arXiv2021

A Ratio to Evaluate Harvest Procedures Management in an Economic System where Resources Dynamics is ruled by an Ornstein- Uhlenbeck Process

The assessing resources dynamics problem, in the context of an economic system with Gaussian consumption and deterministic productivity, is considered in this paper. Basically it is presented a discrete time recursive equation that supports the recourse to the Ornstein-Uhlenbeck diffusion process. Some assumptions on the regeneration of the process are made, in order to observe the system equilibrium in what concerns the resources depreciation or accumulation. The objective of this work is to present a result on the sign of a ratio that can be used to evaluate harvest procedures in this context.

math.PR↗
arXiv2021

In the Search for the Infinite Servers Queue with Poisson Arrivals Busy Period Distribution Exponential Behavior

This paper purpose is to investigate exponential behavior conditions for the infinite servers queue with Poisson arrivals busy period length distribution. It is presented a general theoretical result that is the basis of this work. The complementary analysis rely on the infinite servers queue with Poisson arrivals busy period length distribution moments computation. In infinite servers queue with Poisson arrivals practical applications, in economic, management, and business areas, the management of the effective number of servers is essential since the physical presence of infinite servers is not viable and so it is necessary to create that condition through an adequate management of the number of servers during the busy period.

math.PR↗
arXiv2021

First Order Differential Equations Induced by the Infinite Servers Queue with Poisson Arrivals Transient Behavior Probability Distribution Parameters Study as Time Functions

The infinite servers queue with Poisson arrivals state transient probabilities, considering the time origin at the beginning of a busy period, mean and variance monotony as time functions is studied. These studies, for which results it is determinant the hazard rate function service time length, induce the consideration of two differential equations, one related with the mean monotony study and another with the variance monotony study, which solutions lead to some particular service time distributions, for which those parameters present specific behaviors as time functions.

math.PR↗
arXiv2021

Laplace Transform Effectiveness in the MGinf Queue Busy Period Probabilistic Study

The Laplace transform is a widely used tool in the study of probability distributions, often allowing for a probability density functions and distribution functions simpler determination and being a moments generating function. In this paper it is considered a situation not so simple, as it is the case of the MGinf queue busy period length distribution. Attention will also be given the respective tail Laplace transform. Then, in the context of an open queues network, which nodes behave as MGinf queues, the Laplace transform will be used to construct an algorithm to determine the Laplace transform of the global service time length of a customer during their stay on the network distribution.

math.PR↗
arXiv2021

Computing Customers Sojourn Times in Jackson Networks Distribution Functions and Moments

Jackson queuing networks have a lot of practical applications, mainly in services and technologic devices. For the first case, an example are the healthcare networks and, for the second, the computation and telecommunications networks. Evidently the time that a customer (a person, a job, a message) spends in this kind of systems, its sojourn time, is an important measure of its performance, among others. In this work, the practical statistical known results about the sojourn time of a customer, in a Jackson network, distribution are collected and presented. And an emphasis is set on the numerical methods applicable to compute the distribution function and the moments.

math.PR↗
arXiv2021

QUEUE, with Poisson arrivals, constant service time and infinite servers, BUSY PERIOD DISTRIBUTION

The queue system,with Poisson arrivals,constant service time and infinite servers, busy period distribution is intensively studied because, due to its probability density function quite easy interpretation, it may serve as a clue to interpret the queue systems, with Poisson arrivals, infinite servers, and other service time distributions, busy period distributions. In this work the queue system, with Poisson arrivals,constant service time and infinite servers, busy period distribution parameters are exactly computed and its probability density function is interpreted and explained. The only problem is how to compute the distribution function, for which an algorithm is presented and exemplified its application.

math.PR↗