Introduction to System Simulation (系統模擬介紹) By C. L. Hsieh Department of Industrial Management Aletheia University

What is Simulation? (什麼昰模擬) Simulation is the imitation of a dynamic system using a computer model in order to evaluate and improve system performance 模擬乃是使用電腦模型來模仿一個動態系統為了評估與改善系統之執行成效

What is Simulation? (什麼是模擬) [Schriber, 1987] Simulation is the modeling of a process or system in such a way that the model mimics the response of the actual system to events that take place over time 模擬乃是使用電腦模型來模仿真正系統建模之過程。此系統是會隨時間之改變而變化之系統(即動態系統)

Why Simulate? (為什麼要模擬) Simulation provides a way to validate the best decisions (模擬提供一種驗證最佳決策之方法) Simulation avoids expensive, time-consuming, and disruptive trial-and-error techniques (模擬避免昂貴，費時及破碎式的試誤法)

Characteristics of Simulation (模擬之特性) Capture system inter-dependencies (掌握系統間各元件之相依性) Account for variability in system (解釋系統中之變異性) Versatile enough to model any system (多方面的功能可以對任何系統建立模型) Shows behavior over time (解釋與顯示系統隨時間變化之行為)

Characteristics of Simulation (模擬之特性) Less costly, time, disruptive than experiment on the actual system (比起在真正系統上尋找答案，模擬負擔較少之成本，時間) Visually appealing (視覺之加分效果) Easy results (結果易分析) Run in compressed, real time (執行結果耗費較少時間即可獲得)

Doing Simulation (模擬之進行) Simulation provides a virtual way for doing system experimentation (see p.9, Fig 1.2) (模擬提供一種作系統實驗之實質方法) Simulation itself is not a solution tool but an evaluation tool (模擬本身不昰一種求解工具而是一種評估工具)

Doing Simulation (模擬之進行) Procedure for doing a simulation is an iterative (再三重複) one in which activities are refined and redefined with each iteration (模擬程序之進行乃是一種不斷反覆的程序，在每次反覆中所有當中之活動皆會被改善與重新定義) 參見 p.9, Fig 1.3 模擬實驗之程序流程圖

Procedures for Conducting a Simulation Q&A 1.模擬的目的為何? 2.顧客為誰? 3.模擬結果之重要性 4.顧客之期望是什麼? 5.預算有多少? 6.Deadline? Goals 系統功能分析 可行性研究 容量&製造能力分析 系統間功能比較 最優化系統 系統決策與反應分析 受限分析 系統溝通 資料收集與分析 界定所需資料 使用系統方法收集資料 使用適當資料來源 準備假設表列 將資料轉換為有用形式 資料文件化 界定模擬目標與限制 收集&分析系統資料 建立模式 引導模擬實驗 分析輸出結果 模擬成果報告

Use of Simulation (模擬普及化之原因) Increased awareness and understanding of simulation technology (對模擬技術了解越來越普遍) Increased availability, capability and ease of use simulation software (模擬軟體之發展越來越容易獲得與使用)

Use of Simulation (模擬普及化之原因) Increased computer memory & processing speeds, especially PCs (電腦記憶體與處理速度不斷進步) Decline hardware & software costs (電腦軟體與硬體成本之減少)

Applications of Simulation (模擬之應用) Manufacturing System (e.g. warehouse & distribution systems) Line Balancing (生產線平衡) Capacity Planning (生產計劃與容量) Cycle Time Reduction (減少生產時間) Staff & Resource Planning (人力資源計劃) Bottleneck Analysis (瓶頸分析) Quality Improvement (品質改善) Production Scheduling (生產排程)

Applications of Simulation (模擬之應用) Investment Analysis (投資分析) capital investments (資本投資分析) order processing (訂單處理) customer support (顧客支援) Communication & Visualization (visual animation) (通訊與視覺化) Interactive, Computer-Based Training (decision -making by interacting with the model) (互動式電腦之決策與訓練)

When Simulation is Appropriate? (何時適用模擬之應用) Operational (logical or quantitative) decision (作業型之決策:邏輯與定量型之問題) Well–defined & repetitive analytical process (完整定義與重複性分析過程) Not for Qualitative Problems (e.g. Machine Reliability, Motivate Workers (定性問題，如機器之可靠度，員工士氣之提昇等並不適用)

When Simulation is Appropriate? (何時適用模擬之應用) Activities & Events: inter-dependency & variability (系統中之活動與事件具有相依性與互動性) Cost of decision > cost of simulation (決策成本 > 模擬成本) Cost of experiment > cost of simulation (實驗成本 > 模擬成本) 注意: Don’t use a shot gun to kill a fly

Qualifications (使用模擬之資格) Project management (專案管理) Communication (溝通技巧) System Engineering (系統功能) Statistical analysis & design of experiments (統計分析與實驗設計)

Qualifications (使用模擬之資格) Modeling concepts (建模觀念) Basic Programming (基本程式設計) Training on simulation products (e.g. Promodel) (模擬軟體之使用與訓練) Familiarity with the system investigated (熟悉系統內部分析)

Qualifications (使用模擬之資格) Who are qualified? (誰有資格?) Good abstract thinkers (see the forest) (抽象思考者) Pay attention to detail (see the trees) (注意細節者) Quickly scope a project→gather pertinent data →get useful model →running without lets of starts & stops (掌握大方向→收集相關資料→建立有用模式→有效執行)

Economic Justification (成本分析與考量) Assess the risk of making poor design and operational decisions (例如：作錯決策之成本為何?) Provide justification (improvement) for management & operational goals (對於管理與作業目標提供改善依據) Allow making mistakes & working on errors on the model (允許在建模過程出錯， real savings)

Cost Changes of Subsequent Stages of System Development (系統發展過程之成本變化) Rule of Tens: Cost to correct a problem

Comparison of System Costs with & without Simulation (模擬與成本之關係)

Summary (結論) Simulation is powerful to improve system performance by providing a way to make better designs and decisions (模擬昰藉由較佳設計與決策來改善系統執行之有效方法)

Summary (結論) Simulation accounts for system inter-dependencies & variability (模擬解釋了系統之相依性與互動性) Simulation makes designing systems fun! (visualization makes realism) (模擬之視覺效果使系統之建立過程更有趣!)

How to Use This Book? (如何使用此本教科書) Part I : Basic Concepts : Science & Practice of Simulation (第一部分：模擬基本概念) Part II : Case Study Assignments (第二部分：實務探討) Part III : Promodel Lab Exercises Develop simulation skills (第三部分：Promodel上機練習)