模擬平台之設計與實作

Design and Implementation of a Simulation System

蒲泰宏(Tai-Hong Pu)

指導教授 ： 俞旭昇

國立暨南國際大學/管理學院/資訊管理學系/碩士(2008年)

https://doi.org/10.6837/NCNU.2008.00271

摘要

由於現實生活中存在著許多事物侷限於時間、金錢或無法實際實驗，因此必須借助模擬來研究。模擬乃為藉由電腦模仿真實系統的運作過程，透過模擬的結果，不僅節省了許多不必要的成本，也可以作為研究參考之依據。但目前的模擬軟體大多數存在著無法處理複雜的模擬環境，且僅適用於單一領域的問題。因此，本研究希望建立一套具有易用性、有用性及泛用性的模擬平台。
　　在模型選擇的策略上，微分方程(ODEs)最主要的困難點在於模擬大型網路時，任意增減節點時必須重新撰寫整個模型，而且不具有圖形化也不易學習，因此，本研究選擇了具有圖形化與可以驗證模型正確性的Petri Nets。Petri Nets主要由Transition、Place、Arc與Token所組成，雖然容易使用，但是僅具有一種運作機制，塑模方式無法由使用者自由延伸，即使是改良過的High level Petri Nets能無法避開其缺陷，因此對於許多真實現象皆無法確切的表達與模擬。
　　有鑑於此，本研究將Java的繼承概念，引進了Transition，使其語意(semantic)能夠改變，因此使用者可以依據需求而實做不同的sub Transition；不論何種Petri Nets，皆必須事先定義Arc的方向性才能模擬，本研究提出了動態Arc與資料庫的配合，產生整個模擬環境，而且Arc不需具有方向性；對於Token也可用連續型別處理，別於傳統只能傳遞離散型別的Token；最後透過支援多核心硬體，將可縮短模擬時間。

關鍵字

模擬 ； Petri Nets ； 物件導向 ； Java ； 繼承

並列摘要

A computer simulation is an attempt to model a real-life or hypothetical situation on a
computer so that it can be studied to see how the system works. By changing variables,
predictions may be made about the behavior of the system.
In the thesis, we propose the simulation software and it is based on Petri Nets. The
proposed method is extending Petri Nets' semantic of transition by Object Oriented.
Compared with original Petri Nets, the proposed method can not only execute the original
transition but also can execute other different transitions that can be implemented via Java'
inheritance. In addition, user can define fire rule in transition and change the original Petri
Nets' execution semantic. Petri Nets' direction of arc is dynamic when a transition finished
and determined the arc's direction. In other words, the relationship between transition and
place is undirected, arc's direction is computing dynamic by transition. For example, in a
chemical equation, the reaction is forward or reverses according to equilibrium constant,
and the equilibrium constant is computed in a transition.
Furthermore, we propose a new way to generate simulation model quickly and
automatically by combined dynamic arc with database, so user do not necessary generate
model step by step. Lastly, the software can support with multicore processors and it can
improve the simulation performance significantly.

並列關鍵字

Simulation ； Petri Nets ； Object Oriented ； Java ； Inheritance

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