Ankita Gupta, Rakesh Ranjan and
Satyanshu K. Upadhyay
Classical and Bayes Analysis of A Competing Risk Model Based
on Two Weibull Distributions with Increasing and Decreasing
Hazards.
The paper considers a competing risk
model based on two Weibull distributions, one with
increasing and the other with decreasing hazard rate. It
then considers both classical and Bayesian analysis of the
model, the later development utilizes the informative but
weak priors for the parameters. The analysis is facilitated
by the fact that a competing risk model can be considered as
an incomplete data model even if the situation allows all
the observations on the test to be made available although
the results are extended for censored data cases as well.
The paper uses the expectation-maximization algorithm for
classical maximum likelihood estimation and Gibbs sampler
algorithm for posterior based inferences. It is shown that
the likelihood function offers unique and consistent maximum
likelihood estimates. The results are illustrated based on a
real data example. Finally, the compatibility of the model
is examined for the considered real data set using some
standard tools of Bayesian paradigm.
DOI:
https://doi.org/10.24411/1932-2321-2018-13001
Himanshu Pandey
Comparison of Usage
of Crowdsourcing in Traditional and Agile Software
Development Methodologies
on the Basis of Effectiveness
The authors here try to forecast the Effort in Person Months
for developing Agile and the traditional way of software
development including Prototyping. The comparison is made on
the basis of considering both Agile and traditional software
development methodologies in addition to the crowdsourcing
paradigm applied to both approaches. DNA Matcher (DNAM) has
been developed using both prototyping and Agile software
development with crowd sourcing. For Agile development,
first of all COCOMO II Model is applied on it utilizing the
crowdsourcing technique. The authors have determined that
Agile development proves to be considerably economical when
both techniques use crowdsourcing. The case study used here
is DNAM. First DNAM was developed using traditional
prototyping methods. During its analysis, costing is done.
This is done in accordance with the crowdsoursing used in
parallel to the Prototyping method. The time and effort in
Person Months (PM) was known. Then AGILE development
methodology is used in the development of DNAM. Agile is
used along with the crowdsourcing paradigm. As soon as the
analysis phase is completed, Simple Build-up Approach
forecasts the time and effort in terms of Number of
Iterations and Person Months and we compare the results of
Effort and Cost of both the techniques. The Agile method is
found to be both, less in cost and effort, thereby
increasing the Effectiveness and Efficiency of the
progression of Software development.
DOI:
https://doi.org/10.24411/1932-2321-2018-13002
Evsey Morozov, Gurami Tsitsiashvili
The Necessary
Stability Conditions of a Tandem System With Feedback
In this paper, we consider Markovian model of a two-station
tandem network with the following feedback admission control
policy: the first station rejects new arrivals when the
queue size in the second station exceeds a certain threshold
.
We provide necessary stability conditions of this model.
Each station operates as a multiserver queuieng system, and
thus work in part generalizes the results from the paper [1]
in which single-server stations have been considered. The
analysis is based on the Burke’s theorem and stochastic
monotonicity of the Birth-Death process describing the
number of customers in the second station.
DOI:
https://doi.org/10.24411/1932-2321-2018-13003
Ram Niwas
Reliability Analysis
of a Maintenance Scheduling Model Under Failure Free
Warranty Policy
This paper considers a maintenance
scheduling model by using the concepts of failure free
warranty policy. In this model, all the repairs during
warranty are cost-free to the users, provided failures are
not due to the negligence of the users. However, the users
will have to repair the failed unit at their own expenses
beyond warranty. During their formulation, the failure rate
of the system is considered to be negative exponential
distribution while the preventive maintenance (PM), repair
and replacement time distributions are taken to be arbitrary
with different probability density functions. Under these
assumptions, using the supplementary variable technique, the
various expressions which depict the behavior of the system
such as reliability of the system, Mean Time to System
Failure (MTSF), availability and profit function have been
derived. Further, steady-state behavior of the system has
also been derived. To substantiate the proposed approach,
the effect of the parameters of the system has been analyzed
through the system reliability and expected profit through
an illustrative example.
DOI:
https://doi.org/10.24411/1932-2321-2018-13006
Bavagosai Pratima, K. Muralidharan
A Pareto II Model
With Inliers at zERo and One Based on Type-II Censored
Samples
Inliers (instantaneous or early
failures) are natural occurrences of a life test, where some
of the items fail immediately or within a short time of the
life test due to mechanical failure, inferior quality or
faulty construction of items and components. The
inconsistency of such life data is modeled using a
nonstandard mixture of distributions; where degeneracy can
happen at discrete points at zero and one. In this paper,
the estimation of parameters based on Type-II censored
sample from a Pareto type II distribution with discrete mass
at zero and one is studied. The Maximum Likelihood
Estimators (MLE) are developed for estimating the unknown
parameters. The Fisher information matrix, as well as the
asymptotic variance-covariance matrix of the MLEs are
derived. Uniformly Minimum Variance Unbiased Estimate (UMVUE)
of model parameters as well as UMVUE of density function,
reliability function and some other parametric function are
obtained along with the standard error of estimators. The
model is implemented on various real data sets
DOI:
https://doi.org/10.24411/1932-2321-2018-13004
Vidhya G Nair, M. Manoharan
Reliability Analysis
of a Multi State System With Common Cause Failures Using
Markov Regenerative Process
In this paper the dynamic reliability
behaviour in terms of common cause failures is identified
and a state space model has been formed for the evaluation
of performance measures of multi state system. The concept
of renewal is employed in this paper. Markov Regenerative
Process has been used for assessment of availability of the
system and a system in which this technique is effectively
used is illustrated.
DOI:
https://doi.org/10.24411/1932-2321-2018-13005
