ComputerAided_Design_Engineering_amp_Manufactur.pdf
ComputerAided_Design_Engineering_amp_Manufactur.pdf
ComputerAided_Design_Engineering_amp_Manufactur.pdf
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18<br />
1 EX SP SE SP SE EX EX EX EX EX EX EX EX EX EX EX SE<br />
2 EX EX SE EX SE SP SE SP SE SE SE SE SE SE SE SE SE<br />
3 SN EX SP CN CN EX EX EX EX EX EX EX EX EX SE EX SE<br />
4 SL SL SN CN CN SL EX SL EX SL SL SN SN CN SP EX SE<br />
5 SN EX CN CN SP EX EX EX EX EX EX EX EX EX SL EX SE<br />
6 SL SL CN CN CN SL EX SLL EX SL SL SL CN SN SP EX SE<br />
7 EX SN EX SE EX SE SP CN CN SP CN SE SE SE SE SE SE<br />
8 SE SL EX EX EX EX SN CN CN EX CN EX EX EX EX SP SE<br />
9 EX SN EX SE EX SL CN CN SP CN SP SP SE SE SE SE SE<br />
10 EX SL EX EX EX EX CN CN SN EX EX EX EX EX EX SP SE<br />
11 EX SL EX SE EX SE SN EX CN EX CN SP SE SE SE EX SE<br />
12 EX SL EX SE EX SE SL EX SN EX CN SP SE SE SE EX SE<br />
13 EX SL EX SP EX CN SL EX SL EX SN SN SP SP SE EX SE<br />
14 EX SL EX CN EX SP SL EX SL EX SL SL SN CN SE EX SE<br />
15 EX SL EX CN EX SP SL EX SL EX SL SL SN CN SE EX SE<br />
16 SL SL SL SN SL SN SL EX SL EX SL SL SL SL SL EX SE<br />
17 EX SL EX EX EX EX SL SN SL SN EX EX EX EX EX EX SP<br />
18 SL SL SL SL SL SL SL SL SL SL SL SL SL SL SL SN SN<br />
FIGURE 8.9(b) The new T-Matrix of the net in Figure 8.9(a). (From Reference 2a. With permission.)<br />
For factor 1, it takes O(1) time to consult the T-Matrix to find Agj . For factor 2, the complexity to<br />
update entries has been shown to be O(n) for PG and O n for each PSP generation during an IG.<br />
Thus each PSP generation takes O time complexity. Let be the number of PSPs prior to the ith<br />
generation. The time complexity for the ith generation is . After a PG, one PSP is deleted, while at<br />
most four new PSPs are created. Thus after the PG, the number of PSPs increases at most from to .<br />
For an IG of an NP between two PSPs, two PSPs are deleted and at most five new PSPs are created.<br />
Hence after the IG of a single PSP, there are at most PSPs. The time complexity for the next<br />
generation is bounded by .<br />
Let � be the total number of PSPs at the end of a design. If we add the above time complexity for all<br />
steps, the total time complexity would be . However, this is overly estimated by noting that every<br />
entry is updated at most twice because the entry can only be updated when it is “CN” or “EX.” In other<br />
words, it can be updated from “CN” or “EX” to “SQ,” but not vice versa. Since we have entries, the<br />
total time complexity is therefore .<br />
Note that the T-Matrix does not include any virtual PSPs as they have no internal nodes (i.e., neither<br />
nor ) to serve as an or an . Thus any PSP in the T-Matrix must contain at least one internal<br />
node and the total number of PSPs in the T-Matrix are less than the total number of nodes, �, in the<br />
PN. Therefore, the total time complexity is . When many PSPs contain a number of internal nodes,<br />
the number of nodes outnumbers that of PSPs. Operations on the T-Matrix should result in significantly<br />
more reduction in time for synthesis than if we consider each node individually.<br />
2<br />
( )<br />
n 2<br />
( ) ni 2<br />
O( ni) ni ni�3 ni � 3<br />
O [ ni�3] 2<br />
( )<br />
O � 3<br />
( )<br />
� 2<br />
O � 2<br />
( )<br />
ng nj ng nj O � 2<br />
( )<br />
8.6 X-Window Implementation<br />
We have implemented the above algorithm by incorporating it into a multi-function Petri net graphics<br />
tool based on X-Window (Motif version). This software package 4,11 is a user-friendly CAD tool for<br />
designing, verifying, simulating, querying (including cycle time, invariants, incidence matrix, inputs/<br />
outputs of neods, etc.), reducing, and synthesizing PN. The structure of this tool is shown in Figure 8.10.<br />
This tool can draw, erase, copy, move, pan, and zoom in/out objects such as places, transitions, states,<br />
rectangular and elliptical objects (filled and nonfilled), and texts (with a variety of fonts). The user can