| |
RT&A
2012,
# 4(27) Vol.7
I.B. Shubinsky, Dr. Hendrik Schäbe
ON THE DEFINITION OF
FUNCTIONAL RELIABILITY
The
theory of reliability has been developed in order to
ensure operability of technical objects (components and
systems). However, no thorough explanation of the term
“functional reliability” is given by now, although it is
used with increasing frequency. We deduce a definition
based on the terms property, quality and function.. In
this connection, we draw attention on the principal
differences between functional and structural
reliability. We explain similarities between functional
safety and functional reliability and show how they
smoothly change one into the other.
Swajeeth Pilot Panchangam, V. N. A. Naikan
APPLICATION OF
RELIABILITY GROWTH MODELS TO SENSOR SYSTEMS
This
paper presents the three reliability growth models
namely Duane, AMSAA, and ERG II models briefly. The
paper compares the three models for both time and
failure terminated tests. Comparisons are carried out by
simulating and conducting the statistical hypothesis
t-test on twenty sets of failure data. An inference made
from statistical hypothesis t-test is that AMSAA model
is better choice for time terminated reliability growth
test. Duane model is better choice for failure
terminated reliability growth test. This is based on
comparison with ERG II model which is expected to give
best results. Case study on reliability growth tests of
strain gauge of pressure sensor used in propulsion
systems of satellites is also presented.
Dmitry A. Maevsky
FUNDAMENTALS OF
SOFTWARE STABILITY THEORY
The
theoretical fundamentals of software stability were
elaborated on the basis of software dynamic theory. The
concepts of internal and external equilibrium have been
introduced and the condition of reliability has been
proved. The law of defect flow equilibrium has been
formulated. The existence of unknown before mutual
dependences among the defect flows in software has been
revealed.
S. Zarrin, M. Kamal, S. Saxena
ESTIMATION IN
CONSTANT STRESS PARTIALLY ACCELERATED LIFE TESTS
FOR
RAYLEIGH DISTRIBUTION USING TYPE-I CENSORING
Partially Accelerated life tests are used when the data
obtained from Accelerated life tests cannot be
extrapolated to use conditions. This study deals with
simple Constant Stress Partially Accelerated life tests
using type-I censoring. The lifetime distribution of the
test item is assumed to follow Rayleigh distribution.
The maximum likelihood estimates are obtained for the
distribution parameter and acceleration factor. In
addition, asymptotic variance and covariance matrix of
the estimators are given. Interval estimation that
generates narrow intervals to the parameters of the
distribution with high probability is obtained.
Simulation procedure is used to illustrate the
statistical properties of the parameters and the
confidence bounds.
Farhadzade E.M., Muradaliev A.Z., Farzaliev Y.Z.
QUANTITATIVE
ESTIMATION OF INDIVIDUAL RELIABILITY OF THE EQUIPMENT
AND
DEVICES OF THE POWER SUPPLY SYSTEM
The
basic stages of a design procedure of parameters of
individual reliability the equipment and devices of
electro power systems are considered. The recommended
method illustrated on an example of parameters of
reliability calculated as average arithmetic random
variables. The method based on imitating modeling of
random variables and the theory of check of statistical
hypotheses.
Kumar Pardeep
CARDINALITY BASED
APPROACH FOR RELIABILITY REDUNDANCY OPTIMIZATION OF FLOW
NETWORKS
In flow
networks, a reliability model representing
telecommunications networks is independent of
topological information, but depends on traffic path
attributes like delay, reliability and capacity etc..
The performance of such networks from quality of service
point of view is the measure of its flow capacity which
can satisfy the customers demand. To design a flow
network which can meet the desired performance goal, a
cardinality based approach for reliability redundancy
optimization using composite performance measure
integrating reliability and capacity has been proposed.
The method utilizes cardinality based criteria to
optimize main flow paths and backup paths on priority
basis. The algorithm is reasonably efficient due to
reduced computation work even for large
telecommunication networks.
Medvedev Arkadiy M.
PRINTED-CIRCUIT
BOARDS. RELIABILITY OF INTERCONNECTIONS
Stability of metallization of holes to thermomechanical
pressure is provided with durability and plasticity of
galvanic besieged copper. Distinctions in factors of
thermal expansion of copper and the dielectric bases of
printed-circuit boards create powerful thermomechanical
factors of rupture of metallization of apertures,
destructions of internal interconnections in
multilayered structures of printed-circuit boards.
Standard norms of requirements to a thickness of
metallization of apertures, its durability and
plasticity of copper were established in the course of
manufacture of ordinary printed-circuit boards with
reference to use of traditional technologies of the
soldering by tin-lead solders. Return to consideration
of a problem of plasticity of copper is caused first of
all by transition on the Lead-free solders, initiated by
the all-European Directive RoHS, rations different by a
heat. More heats create the big deformations of
metallization of holes those forces to reconsider
requirements to plasticity of copper. At the same time,
the tendency to reduction of diameter of the metallized
holes, so also to reduction of the area of cross-section
section of metallization is everywhere observed. Smaller
sections have smaller resistance to rupture. Therefore,
along with good plasticity, metallization of holes of
printed-circuit boards should provide and higher
breaking strength. In this connection deformation of
metallization of holes at heating to soldering
temperatures has been investigated. The purpose of
researches - revision of norms on plasticity of copper
in holes of printed-circuit boards. It is shown that
plasticity copper deposition in holes of modern
printed-circuit boards should not be less than 6 %.
Modern cupper electrolytes allow to receive plasticity
of copper of 12-18%.
Swajeeth Pilot Panchangam, V. N. A. Naikan
OPTIMAL SENSOR
NETWORKS SYSTEM RELIABILITY ALLOCATION USING IMPROVED AGREE
METHOD
Reliability of sensor networks system plays an important
role in monitoring the operational health conditions of
any critical engineering system. In this paper, a
methodology is proposed to improve an initial optimal
allocation of sensor system by considering fault
acceptance degree (FAD), fault influence degree (FID),
importance factor (α),
and the actual operational data of the critical system
with initial allocated sensors for a small initial
period. The paper has also proposed a method for
estimation of expected life of the sensor network based
on the above factors. A hypothetical case of the sensor
system of an electric motor is presented to illustrate
the proposed approach.
Artyukhova M., Polesskiy S.
DEVELOPMENT OF THE
METHOD OF PREDICTION PARAMETER
OF RELIABILITY CHEMICAL
CURRENT SOURCES OPERATING IN A “SESSION” MODE
The
paper describes the calculation method of reliability
and conservability products class of chemical current
sources (CCS) in the design to the specific conditions
in the electronic means. The technical specification for
the indicators of CCS reliability are for specific
operation modes and their use in the calculation gives a
large error. In the U.S. (MIL-HDBK-217F, Telcordia (Bellcore)
SR 332), French (CNET RDF-2000), English (British
Telecom HRD5) and Chinese (GJB/z 299B) references to
the reliability of electronic devices there is no
information for the calculation of reliability and
conservability CCS, no calculation models. The
cumulative accounting model of physical factors
affecting the calculated capacity of the chemical
current sources, which is the main factor affecting the
reliability is shown
|
