Information Technology Reference
In-Depth Information
Here, G(t
0
) is the value of the gravitational constant at the
first cosmic quantum-
interval of time t
0
. This varying G(t) is used to compute total force F
i
exerted on
agent i from direction d in the space. Due to this force agents are accelerated
towards each other. Acceleration of any agent i having mass Mi
i
at time t in direction
d is computed with the equation presented below:
F
i
ð
Þ
t
a
i
ð
t
Þ
¼
ð
6
Þ
M
i
ð
t
Þ
The position velocity of each agent is updated with laws of motion as follows:
v
i
ð
t
þ
Þ
¼R
v
i
ð
t
Þþ
a
i
ð
t
Þ
1
ð
7
Þ
x
i
ð
x
i
ð
v
i
ð
t
þ
1
Þ
¼
t
Þþ
t
þ
1
Þ
ð
8
Þ
Here, x
i
ð
and v
i
ð
t
þ
1
Þ
t
þ
1
Þ
are the position and velocity of agent i in direction
d at time t
þ
1. R is an uniformly distributed random variable within range
ð
0
;
1
.
This strategy can be
fitted into generalized framework of SI by considering pop-
ulation as set of searching agents.
3.5 Intelligent Water Drop
Intelligent Water Drops (IWD) algorithm was introduced by Shah-Hosseini (
2008
).
IWD simulates
flow of river water. It seems that natural river often follows
favorable paths among lots of possible different paths on the ways from the source
to destination. Paths through which water
fl
flows in rivers may have several twists
and turns, but always chose best possible path. Intelligence behind those twists and
turns are the key inspiration of the IWD algorithm. Those approximate best paths
are resulted by the actions and reactions, which occur among the water drops and
the water drops with the soil. Considering these aspects IWDs are created with two
properties soil and velocity. Solution space is represented with a graph. IWDs are
distributed over the graph and starts moving through edges. An IWD
fl
flows from a
source to a destination. Initially IWDs have velocity but zero soil. During move-
ment from one node to another, removes soil from the path and gain speed.
Increment in velocity of an IWD is non-linearly and inversely proportional to the
soil present in the path. Therefore, the IWD become faster in a path with less soil.
Three things happening during movement of IWDs in graphically represented
solution space. Firstly, IWDs gain velocity and gather soil from the path they
moved through. Secondly, proportionate amount of soil is removed from the path of
the graph through which they move. Time factor is used during removal and
addition of soil. Less the time to pass IWD through a path can remove larger
amount of soil. The time is proportional to the velocity of the IWD and inversely
fl
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