<s>
RAMP	B-Algorithm
Simulation	I-Algorithm
Software	I-Algorithm
for	I-Algorithm
Modelling	I-Algorithm
Reliability	I-Algorithm
,	I-Algorithm
Availability	I-Algorithm
and	I-Algorithm
Maintainability	I-Algorithm
(	O
RAM	O
)	O
is	O
a	O
computer	O
software	O
application	O
developed	O
by	O
WS	O
Atkins	O
specifically	O
for	O
the	O
assessment	O
of	O
the	O
reliability	O
,	O
availability	O
,	O
maintainability	O
and	O
productivity	O
characteristics	O
of	O
complex	O
systems	O
that	O
would	O
otherwise	O
prove	O
too	O
difficult	O
,	O
cost	O
too	O
much	O
or	O
take	O
too	O
long	O
to	O
study	O
analytically	O
.	O
</s>
<s>
A	O
front-end	O
interactive	O
graphical	B-Application
user	I-Application
interface	I-Application
(	O
GUI	B-Application
)	O
.	O
</s>
<s>
A	O
back-end	O
discrete-event	B-General_Concept
simulation	I-General_Concept
that	O
employs	O
the	O
Monte	B-Algorithm
Carlo	I-Algorithm
method	I-Algorithm
.	O
</s>
<s>
The	O
RAMP	O
Model	O
Builder	O
enables	O
the	O
user	O
to	O
create	O
a	O
block	B-Application
diagram	I-Application
describing	O
the	O
dependency	O
of	O
the	O
process	O
being	O
modelled	O
on	O
the	O
state	O
of	O
individual	O
elements	O
in	O
the	O
system	O
.	O
</s>
<s>
Groups	O
can	O
be	O
further	O
combined	O
(	O
to	O
any	O
depth	O
)	O
to	O
produce	O
a	O
Process	O
Dependency	O
Diagram	O
(	O
PDD	O
)	O
of	O
the	O
system	O
,	O
which	O
is	O
similar	O
to	O
a	O
normal	O
reliability	O
block	B-Application
diagram	I-Application
(	O
RBD	O
)	O
commonly	O
used	O
in	O
reliability	O
engineering	O
,	O
but	O
also	O
allows	O
complex	O
logical	O
relationships	O
between	O
groups	O
and	O
elements	O
to	O
permit	O
a	O
more	O
accurate	O
representation	O
of	O
the	O
process	O
being	O
modelled	O
.	O
</s>
<s>
The	O
PDD	O
should	O
not	O
be	O
confused	O
with	O
a	O
flow	B-Application
diagram	I-Application
since	O
it	O
describes	O
dependency	O
,	O
not	O
flow	O
.	O
</s>
<s>
The	O
RAMP	O
Model	O
Processor	O
mimics	O
the	O
system	O
operating	O
over	O
the	O
time	O
period	O
of	O
interest	O
-	O
known	O
in	O
RAMP	O
as	O
a	O
mission	O
-	O
by	O
sampling	O
failure	O
and	O
repair	O
times	O
from	O
probability	O
distributions	O
(	O
with	O
probabilities	O
drawn	O
from	O
a	O
pseudo-random	B-Algorithm
number	I-Algorithm
generator	I-Algorithm
)	O
and	O
combining	O
with	O
other	O
data	O
defined	O
in	O
the	O
RAMP	O
Model	O
Builder	O
to	O
determine	O
state	O
transition	O
events	O
for	O
each	O
element	O
in	O
the	O
model	O
.	O
</s>
<s>
By	O
running	O
enough	O
missions	O
over	O
the	O
same	O
time	O
period	O
of	O
interest	O
(	O
different	O
possible	O
histories	O
from	O
the	O
same	O
starting	O
point	O
)	O
,	O
RAMP	O
can	O
be	O
used	O
to	O
generate	O
statistically	B-General_Concept
significant	I-General_Concept
results	O
that	O
establish	O
the	O
likely	O
distribution	O
of	O
the	O
user-defined	O
parameters	O
of	O
interest	O
and	O
thus	O
objectively	O
assess	O
the	O
system	O
,	O
with	O
the	O
confidence	O
bands	O
on	O
the	O
results	O
dependent	O
on	O
the	O
number	O
of	O
missions	O
simulated	O
.	O
</s>
<s>
Extensive	O
redevelopment	O
by	O
Atkins	O
of	O
the	O
original	O
RAMP	O
application	O
for	O
DOS	B-Device
has	O
produced	O
a	O
series	O
of	O
RAMP	O
applications	O
for	O
the	O
Microsoft	B-Application
Windows	I-Application
platform	O
,	O
with	O
the	O
RAMP	O
Model	O
Builder	O
written	O
in	O
Visual	B-Language
Basic	I-Language
and	O
the	O
RAMP	O
Model	O
Processor	O
written	O
in	O
FORTRAN	B-Application
.	O
</s>
