Environmental Engineering Reference
In-Depth Information
Figure 4. “Cube” of diversity-oriented decisions
Multi-version project (MVP) is a project, in
which the multi-version technology is applied
(version redundancy of processes is used) lead-
ing to creation of one- or multi-version system
(realization of version redundancy of products).
Strategy of diversity (MV) is a collection of general
criteria and rules defining principles of formation
and selection of version redundancy types and a
volume or/and choice of MVTs. Besides, impor-
tant elements of the multi-version computing are
concepts “multi-version life cycle,” “diversity
metric.” More detailed interpretation of these
concepts will be done below.
2.3.3-2.3.8, 3.3.3-3.3.8, 4.2.4-4.2.15; for example,
last combinations correspond to 12 = 4 (kinds of
EE diversity) х 3 (kinds of CASE-tool diversity))
couples.
Diversity Type Classification
Schemes
Different variants of diversity type classifica-
tions were described above. The analysis of the
considered classifications allows approving that:
they are presented by classifications of mixed
facet-hierarchical or matrix (network) types; the
NUREG-based classification presented in (Wood
et al., 2009) is the most detailed and systematic,
though the principle of attributes orthogonality
is not sustained in full in it; for example, subsets
of a design and software, a functional and signal
version redundancy are crossed and dependent; a
variety of a product (system, hardware and soft-
ware components) and of a process (technologies
of development, testing and maintenance) version
redundancy cause complexity of VR selection and
MVS development.
More general diversity type classification
scheme is so-called “cube” of diversity described
by a matrix MVR =|| vrijk|| in three-dimensional
space (Figure 4). The scheme has coordinates: a
stage of LC (i); a level of project decisions (PD,
j) and a type of VR (project decision). Example
of two-space matrix presented a cut of “cube” for
FPGA-based systems is shown on the Table 3.
Table 3 contains variants of a joint application
of one or two diversity types (items 1.4.2-1.4.4,
Models Multi-Version Systems
One-version W(1) and multi-version W(n) systems
are defined by 4 and 6 variables (Kharchenko et
al., 2010):
( ) {
Φ
W 1 = X, Y, Z.
,
(1)
( )
W n = X, Y, Z. , V,
{
Φ
Ψ
}
,
(2)
where X, Y, Z - sets of input signals, internal
conditions (states) and output signals correspond-
ingly; Ф = {φ
i
, i=1, ..., a} - a set of I&C functions
(for examples, actuation functions or algorithms
of reactor trip system); V = {v
j
, j=1, ..., n} - a
set of versions with output signals Z
1
,…, Z
n
(or
signals Z
id
, d = 1,…, n
i
; n
i
is a number of versions
for a function φ
i
; ∀φ
i
~ v
j
= { v
ij
, j =1,...,n
i
}); Ψ =
{ψ
s
, s=1, ..., в} - mapping Z
i
→Z.
If the function φ
i
is performed, local mapping
is true: ψ
s
:{z
i
(v
i1
),..., z
i
(
v
in
i
)}→
Z
i
( )
.Taking into
account Equations 1 and 2, multi-version system
and one-version system are connected by a rela-
tionship:
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