301,262 research outputs found
On Extended Quadratic Hazard Rate Distribution: Development, Properties, Characterizations and Applications
In this paper, we propose a flexible extended quadratic hazard rate (EQHR) distribution with increasing, decreasing, bathtub and upside-down bathtub hazard rate function. The EQHR density is arc, right-skewed and symmetrical shaped. This distribution is also obtained from compounding mixture distributions. Stochastic orderings, descriptive measures on the basis of quantiles, order statistics and reliability measures are theoretically established. Characterizations of the EQHR distribution are studied via different techniques. Parameters of the EQHR distribution are estimated using the maximum likelihood method. Goodness of fit of this distribution through different methods is studied
Degradation Analysis of Probabilistic Parallel Choice Systems
Degradation analysis is used to analyze the useful lifetimes of systems,
their failure rates, and various other system parameters like mean time to
failure (MTTF), mean time between failures (MTBF), and the system failure rate
(SFR). In many systems, certain possible parallel paths of execution that have
greater chances of success are preferred over others. Thus we introduce here
the concept of probabilistic parallel choice. We use binary and -ary
probabilistic choice operators in describing the selections of parallel paths.
These binary and -ary probabilistic choice operators are considered so as to
represent the complete system (described as a series-parallel system) in terms
of the probabilities of selection of parallel paths and their relevant
parameters. Our approach allows us to derive new and generalized formulae for
system parameters like MTTF, MTBF, and SFR. We use a generalized exponential
distribution, allowing distinct installation times for individual components,
and use this model to derive expressions for such system parameters
Screening and metamodeling of computer experiments with functional outputs. Application to thermal-hydraulic computations
To perform uncertainty, sensitivity or optimization analysis on scalar
variables calculated by a cpu time expensive computer code, a widely accepted
methodology consists in first identifying the most influential uncertain inputs
(by screening techniques), and then in replacing the cpu time expensive model
by a cpu inexpensive mathematical function, called a metamodel. This paper
extends this methodology to the functional output case, for instance when the
model output variables are curves. The screening approach is based on the
analysis of variance and principal component analysis of output curves. The
functional metamodeling consists in a curve classification step, a dimension
reduction step, then a classical metamodeling step. An industrial nuclear
reactor application (dealing with uncertainties in the pressurized thermal
shock analysis) illustrates all these steps
An a posteriori verification method for generalized real-symmetric eigenvalue problems in large-scale electronic state calculations
An a posteriori verification method is proposed for the generalized
real-symmetric eigenvalue problem and is applied to densely clustered
eigenvalue problems in large-scale electronic state calculations. The proposed
method is realized by a two-stage process in which the approximate solution is
computed by existing numerical libraries and is then verified in a moderate
computational time. The procedure returns intervals containing one exact
eigenvalue in each interval. Test calculations were carried out for organic
device materials, and the verification method confirms that all exact
eigenvalues are well separated in the obtained intervals. This verification
method will be integrated into EigenKernel (https://github.com/eigenkernel/),
which is middleware for various parallel solvers for the generalized eigenvalue
problem. Such an a posteriori verification method will be important in future
computational science.Comment: 15 pages, 7 figure
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