RT&A
2015,
# 4(39) Vol.10
H. Schäbe, I. Shubinsky
Bounds for the reliability of different redundant systems
In many cases, reliability can be
improved by using redundant components. This is an approach
that is applied especially in information networks. In this
paper we study redundant systems with imperfect switches. We
show that there exists a limit as the number of redundant
components tends to infinity. This limit is computed for
components with exponential life time distributions, which
is the typical distribution for digital equipment used in
information systems. For components with distributions
belonging to the NBUE or HNBUE classes, bound are derived.
A. Fries (Panel Chair), W.P. Cherry,
R.G. Easterling, E.A. Elsayed, A.V. Huzurbazar, S.V. Wiel,
P.A. Jacobs, W.Q. Meeker, Jr., N.
Nagappan, M. Pecht, A. Sen, C. Citro, M.L. Cohen, M.J. Siri
Summary of the
National Research Council Report on “Reliability Growth:
Enhancing Defense System Reliability"
This paper, extracted from National
Research Council (2015), summarizes the findings and
recommendations from a recent report from the Panel on
Reliability Growth Methods for Defense Systems,
operating under the auspices of the Committee on
National Statistics (CNSTAT) within the National
Research Council (NRC). The report offers
recommendations to improve defense system reliability
throughout the sequence of stages that comprise U.S.
Department of Defense (DoD) acquisition processes –
beginning with the articulation of requirements for new
systems and ending with feedback mechanisms that
document the reliability experience of deployed systems.
A number of these recommendations are partially or fully
embraced by current DoD directives and practice,
particularly with the advent of recent DoD initiatives
that elevate the importance of design for reliability
techniques, reliability growth testing, and formal
reliability growth modeling. The report supports the
many recent steps taken by DoD, building on these while
addressing associated engineering and statistical
issues. The report provides a self-contained rendition
of reliability enhancement proposals, recognizing that
current DoD guides and directives have not been fully
absorbed or consistently applied and are subject to
change.
Ŕ.
Breznická,
A. Chovanec
Mathematic and
simulation modeling for analysis prediction of risk
Specification of requirements for
reliability of a transport means is first of all an issue of
looking for an acceptable compromise between a requested
level of reliability and a level of costs, which will be
needed for its achievement. Provision of reliability in a
stage of application is however dependent on allocated
sources for a provision of maintenance.
Pustylnik P.N.
THE
EVALUATION OF RISK OF THE DEVELOPMENT OF SOCIO-PRODUCTIVE
STRUCTURE WITH USE OF THE PROGRAM COMPLEX OF ASM 2001
How to manage socio-productive
structure in modern economic conditions? On the basis of
systematic analysis is formulated the concept "dangerous
state of socio-productive structures". Described are three
possible scenarios of failure of development of
socio-productive structure. Proposed is LP-model of
development of socio-productive structure. The calculations
are made with using the software complex ASM 2001. The
results obtained are help in making strategic solution on
basing the assessment of the risks of unsuccessful
development of socio-productive structure.
Farhadzadeh E.M., Muradaliyev A.Z.,
Farzaliyev Y.Z.
TRANSITION FROM QUALITATIVE TO THE QUANTITATIVE APPROACH OF
FORMATION OF DECISIONS ON INCREASE OF RELIABILITY OF OBJECTS OF
ELECTRO POWER SYSTEMS
The decision of problems of maintenance
service arising at the organization and repair of the
equipment and devices of electro power systems is resulted.
To them concern: an estimation of the importance of a
version of the attributes describing reliability and
profitability of work; an estimation of parameters of
individual reliability; an estimation of parameters of
reliability of homogeneous groups (clusters). Methods,
algorithms and programs of calculation of these estimations
are developed. As the initial information statistical data
of operation serve. These data are represented not as
sample, of which general population, and as final population
of multivariate data. The expediency of classification of
these data on the set versions of attributes has or under
condition of not casual character of a divergence of
statistical functions of distribution of the initial data
Fs(x) constructed on all
population and sample
Fv(X). As
criterion of estimation it is accepted non-exceedance to an
estimation of a parameter of reliability calculated on
experimental data of sample
Pe(X), and
critical value of this parameter
Pk for
the set significance value (Errors I type). It is shown,
that: decrease in number of versions of attributes has basic
value for decrease in time of calculations; it is necessary
to analyze not only character of a divergence of the average
parameter of reliability and , but also various combinations of versions of an
attribute; it would be erroneous to represent, that
estimations of parameters of individual reliability are
considered on statistical data of operation of the concrete
equipment. It is simply not enough of them or not.
Individuality is set by significant versions of attributes
for this reason exist more than one unit of equipment and
devices, parameters of which individual reliability are
equal. These groups form cluster; Parameters of reliability
clusters differ from parameters of individual reliability
forming cluster the equipment and devices. Distinction is
caused by that parameters of individual reliability are
calculated on the set versions of attributes. At calculation
parameters of reliability clusters are considered only
versions of attributes for which not casually differ not only from
but
also from all others.
M. A. El-Damcese, N. H. El-Sodany
RELIABILITY AND
SENSITIVITY ANALYSIS OF THE K-OUT-OF-N:G WARM
STANDBY PARALLEL REPAIRABLE SYSTEM WITH REPLACEMENT
AT COMMON-CAUSE FAILURE USING MARKOV MODEL
Standby redundancy is a technique that
has been widely applied for improving system reliability and
availability in system design. In this paper, probabilistic
model for a redundant system with replacement at each
common-cause failure has been developed to analyze the
reliability measures using Markov models. We investigate the
reliability and sensitivity analysis of k-out-of-n:G warm
standby parallel repairable system. All failure and repair
times of the system are exponentially distributed and when
one of the operating primary units fails then it is
instantaneously replaced by a warm standby unit if one is
available. Comparative analysis of reliability measures
between two dissimilar configurations has been developed.
Configuration Ι is a 2-out-of-4:G warm standby parallel
repairable system, while Configuration ΙΙ is a 2-out-of-5:G
warm standby parallel repairable system. We get a
closed-form solution of the reliability measures of the
system for the two configurations. Comparisons are performed
for specific values of system parameter. Sensitivity
analysis is also carried out to depict the effect of various
parameters on the reliability function and mean time to
failure of the system. Numerical example is given to
illustrate the results obtained.
V.V. Rykov, V.YU. Itkin
ON
SENSITIVITY OF RELIABILITY SYSTEMS OPERATING IN RANDOM
ENVIRONMENT TO SHAPE OF THEIR INPUT DISTRIBUTIONS
Removable double redundant
reliability system operating in Markov environment is
considered. The problem of the system steady state
probabilities insensitivity to shape of its elements
life and repair time distributions is studied.
