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ComputerAided_Design_Engineering_amp_Manufactur.pdf

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2a<br />

Reversible: Let M� � in , then<br />

where A is the incidence matrix and x a firing vector. Since is reversible, such that<br />

� 0 and<br />

equation is<br />

. Now add some tokens to some places in to result in . The relevant<br />

2a<br />

N 2a<br />

� a x 2a<br />

Ax 2a<br />

2a<br />

M� �<br />

2a<br />

M0 N 2a<br />

N b<br />

The above firing vector x also makes since � 0. Now choose the least positive<br />

integer u such that ; i.e., every component of x is nonnegative. We have<br />

2a<br />

b<br />

M� � M0 Ax 2a<br />

x ux 2a<br />

x b<br />

� � � 0<br />

N b<br />

Thus is reversible.<br />

N b<br />

R 2a<br />

N 2a<br />

b<br />

M� 2a<br />

M� Live: The proof of being live is exactly the same as that in Theorem 3.<br />

b<br />

M� The bounded property can also be proven by deriving the P-invariants 15 for the synthesized nets.<br />

Theorem 6: The class synthesized PN belongs to the class of synchronized-choice (SC) nets.<br />

2a<br />

M0 Ax 2a<br />

�<br />

Proof: A basic process is obviously an SC. Then assuming is an SC, we need to prove that is<br />

also an SC. Prove for the TT-rule first. The proofs for PP rules are similar. In order to satisfy the first<br />

(second) requirements, we need to show that for any pair of PT (TP) handles, there are two TP bridges<br />

across them. If all nodes and arcs of the two handles are in N , then by assumption they satisfy the two<br />

requirements. We need only consider the case where only part of the handles are in the new paths. Such<br />

handles are called mixed handles.<br />

1<br />

Consider the generations by TT-rules first. The case of PP-rules is similar. We need not consider the<br />

pure-TT generation, because the new path forms a PP-handle to N . For a generation by Rule TT.3,<br />

inside the new paths, there are only place joints formed by TP-path generations using Rule TT.3.1. But<br />

there are no pairs of TP-handles containing these TP-paths. This is because the TP-paths start from s<br />

and all of LEX1 are places.<br />

The only pairs of fixed PT-handles have their and �the of LEX1. One handle of the<br />

pair is in ; part of the other is in the new path. Two of the TP-paths generated using the Rule TT.3.1<br />

form the two bridges between the above two TP-handles, thus satisfying the first requirement.<br />

Note that an SC may not be synthesized; this happens when the SC is not well-behaved. For instance,<br />

when the PT-path (TP-path) generated using Rule TT.4.2 (PP.2.2) is not a virtual one, the is an SC<br />

but with deadlocks.<br />

1<br />

tg nps npe�t g nps pps N 1<br />

N 2<br />

8.4 Temporal Matrices for Petri Nets<br />

�<br />

�<br />

b<br />

b<br />

M0 Ax b<br />

�<br />

� Ax M0 A ux 2a<br />

� � ( ) � M0 The rules should be implemented as an interactive and visual-aid tools. The designer can view the PN<br />

model being designed on the screen and use a mouse to input paths according to the design specification.<br />

Each time a path is generated, the system should check the new path generation against the rules. If some<br />

b<br />

N 1<br />

b<br />

N 2

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