Lecture 6: Modeling and Simulation PDF

Modeling and Simulation Simulation Software LECTURE 6 BY D R. S A M A H A. Z. H A SS A N Ch. 4 Simulation Software 1. Simulation with General Purpose Languages 2. Simulation with General Simulation Languages 3. Simulation with Special-purpose Simulation Packages  Ch. 4 Simulation Softwa...

Modeling and Simulation Simulation Software LECTURE 6 BY D R. S A M A H A. Z. H A SS A N Ch. 4 Simulation Software 1. Simulation with General Purpose Languages 2. Simulation with General Simulation Languages 3. Simulation with Special-purpose Simulation Packages  Ch. 4 Simulation Software General-purpose programming languages  Flexible and familiar.  Well suited for learning DES principles and techniques  e.g., C, C++, and Java.  Simulation programming language,  e.g., GPSS/HTM, SIMAN V ® and SLAM II ®.  Simulation environment  Good for building models quickly  Provide built-in features (e.g., queue structures)  Graphics and animation provided  E g : Arena Automod 2 E.g.: Arena, Automod, History of Simulation Software General Purpose Languages Advantages: ◦ Little or no additional software cost ◦ Universally available (portable) ◦ No additional training (Everybody knows…(language X) ! ) Disadvantages: ◦ Every model starts from scratch ◦ Very little reusable code ◦ Long development cycle for each model ◦ Difficult verification phase General Purpose Languages FORTRAN ◦ Probably more models than any other language. PASCAL ◦ Not as universal as FORTRAN MODULA ◦ Many improvements over PASCAL ADA ◦ Department of Defense attempt at standardization C++, Java ◦ Object-oriented programming language General Simulation Languages Advantages: ◦ Standardized features often needed in modeling ◦ Shorter development cycle for each model ◦ Much assistance in model verification ◦ Very readable code Disadvantages: ◦ Higher software cost (up-front) ◦ Additional training required ◦ Limited portability General Simulation Languages GPSS ◦ Block-structured Language ◦ Interpretive Execution ◦ FORTRAN-based SIMSCRIPT II.5 ◦ English-like Problem Description Language ◦ Compiled Programs ◦ Complete language (no other underlying language) Special-purpose Simulation Packages Advantages ◦ Very quick development of complex models ◦ Short learning cycle ◦ No programming--minimal errors in usage Disadvantages ◦ High cost of software ◦ Limited scope of applicability ◦ Limited flexibility (may not fit your specific application) NETWORK II.5 ◦ Simulator for computer systems OPNET ◦ Simulator for communication networks, including wireless networks COMNET III ◦ Simulator for communications networks SIMFACTORY ◦ Simulator for manufacturing operations Selection of Simulation Software Evaluating and selecting simulation software: ◦ Do not focus on a single issue such as ease of use. ◦ Consider the accuracy and level of detail obtainable, ease of learning, vendor support, and applicability to your problem. ◦ Execution speed is important. ◦ Do not think exclusively in terms of experimental runs that take place at night and over the weekend. ◦ Beware of advertising claims and demonstrations. ◦ Many advertisements exploit positive features of the software only. Selection of Simulation Software Evaluating and selecting simulation software: ◦ Ask the vendor to solve a small version of your problem. ◦ Beware of “checklists” with “yes” and “no” as the entries. ◦ For example, many packages claim to have a conveyor entity. However, implementations have considerable variation and level of fidelity. Implementation and capability are what is important. ◦ Simulation users ask if the simulation model can link to and use code or routines written in external languages such as C, C++, or FORTRAN. ◦ This is good feature, especially when the external routines already exist and are suitable for the purpose at hand. Selection of Simulation Software Evaluating and selecting simulation software: ◦ There may be a significant trade-off between the graphical model-building environments and ones based on a simulation language. ◦ Beware of “no programming required” unless either the package is a near-perfect fit to your problem domain, or programming (customized procedural logic) is possible with the supplied blocks, nodes, or process flow diagram, in which case “no programming required” refers to syntax only and not the development of procedural logic.  14 Any Questi ons