Modeling&Simulation_Ch01_part 3.pptx
- 1. Classification of Systems ClassificationAccording to the Complexity of the System: ©AhmedHagag Modelin g and Simulati on 1
- 2. Classification of Systems Modeling and Simulation 2 Physical systems: • Physical systems can be defined as systems whose variables can be measured with physical devices that are quantitative such as electrical systems, mechanical systems, computer systems, hydraulic systems, thermal systems, or a combination of these systems. • Physical system is a collection of components, in which each component has its own behavior, used for some purpose. These systems are relatively less complex.
- 3. Classification of Systems 3 Conceptual systems: • Conceptual systems are those systems in which all the measurements are conceptual or imaginary and in qualitative form as in psychological systems, social systems, health care systems, and economic systems. These are complex systems. Transportation system
- 4. Classification of Systems Modeling and Simulation 4 Esoteric systems: • Esoteric systems are the measurements are not systems in which the possible with physical measuring devices. The complexity of these systems is of highest order.
- 5. Classification of Systems Modeling and Simulation 5 • Systems will be divided into three classes according to the degree of interconnection of events. • Independent • Cascaded • Coupled
- 6. Classification of Systems Modeling and Simulation 6 Independent system: • If the events have no effect upon one another, then the system is classified as independent.
- 7. Classification of Systems Modeling and Simulation 7 Cascaded system: • If the effects of the events are unilateral (that is, part A affects part B, B affects C, C affects D, and not vice versa), the system is classified as cascaded.
- 8. Classification of Systems Modeling and Simulation 8 Coupled system: • If the events mutually affect each other, the system is classified as coupled.
- 9. Classification of Systems Modeling and Simulation 9 • Systems can be classified according to the Nature and Type of Components. • Static or dynamic components • Linear or nonlinear components • Deterministic or stochastic components • Continuous-time and discrete-time systems • Others…
- 10. Classification of Systems (14/15) Modeling and Simulation ©Ahmed Hagag 10 Static or dynamic components • A static simulation model, sometimes called a Monte Carlo simulation, represents a system at a particular point in time. • Dynamic simulation models represent systems as they change over time. The simulation of a bank from 9:00A.M. to 4:00P.M. is an example of a dynamic simulation.
- 11. Classification of Systems Modeling and Simulation 11 Deterministic or stochastic components • Simulation models that contain no random variables are classified as deterministic. No probabilistic component in the system. • A stochastic simulation model has one or more random variables as inputs. Some components of the system has a probabilistic behavior (Random variable, event probability). Example: Queuing systems.
- 12. Steps in a Simulation Study Modeling and Simulation 12 1. Problem formulation 2. Setting of objectives and overall project plan 3. Model conceptualization 4. Data collection 5. Model translation 6. Verified? 7. Validated? 8. Experimental design 9. Production runs and analysis 10. More runs? 11. Documentation and reporting 12. Implementation
- 13. 76 ©AhmedHagag Modelingand Simulation Steps in a Simulation Study
- 14. 1. Problem formulation Every study should begin with a statement of the problem. If the statement is provided by the policymakers or those that have the problem, the analyst must ensure that the problem being described is clearly understood. If a problem statement is being developed by the analyst, it is important that the policymakers understand and agree with the formulation. Steps in a Simulation Study Modeling and Simulation 14
- 15. 2. Setting of objectives and overall project plan The objectives indicate the questions to be answered by simulation. At this point, a determination should be made Steps in a Simulation Study Modeling and Simulation 15 simulation is the appropriate concerning whether methodology for the problem as formulated and the objectives as stated.
- 16. 3. Model conceptualization It is best to start with a simple model and build toward greater complexity. However, the model complexity need not exceed that required to accomplish the purposes for which the model is intended. It is advisable to involve the model user in model conceptualization. Involving the model user will both enhance the quality of the resulting model and increase the confidence of the model user in the application of the model. Steps in a Simulation Study Modeling and Simulation 16
- 17. 4. Data collection There is a constant interplay between the construction of the model and the collection of the needed input data. As the complexity of the model changes, the required data elements can also change. Also, since data collection takes such a large portion of the total time required to perform a simulation, it is necessary to begin as early as possible, usually together with the early stages of model building. Steps in a Simulation Study Modeling and Simulation 17
- 18. 5. Model translation Most real-world systems result in models that require a great deal of information storage and computation, so the model must be entered into a computer-recognizable format. We use the term program even though it is possible, in many instances, to accomplish the desired result with little or no actual coding. The modeler must decide whether to program the model in a simulation language or to use special-purpose simulation software. Steps in a Simulation Study Modeling and Simulation 18
- 19. 6. Verified? Did we build the model right? Verification pertains to the computer program that has been prepared for the simulation model. Is the computer program performing properly? With complex models, it is difficult, if not impossible, to translate a model successfully in its entirety without a good deal of debugging; if the input parameters and logical structure of the model are correctly represented in the computer, verification has been completed. Steps in a Simulation Study Modeling and Simulation 19
- 20. 7. Validated? Did we build the right model? Validation usually is achieved through the calibration of the model, an iterative process of comparing the model against actual system behavior and using the conflict between the two, and the insights gained, to improve the model. This process is repeated until model accuracy is judged acceptable. Steps in a Simulation Study Modeling and Simulation 20
- 21. 8. Experimental design The alternatives that Steps in a Simulation Study Modeling and Simulation 21 are to be simulated must be determined. Often, the decision concerning which alternatives to simulate will be a function of runs that have been completed and analyzed. For each system design that is simulated, decisions need to be made concerning the length of the initialization period, the length of simulation runs, and the number of replications to be made of each run.
- 22. 9. Production runs and analysis Production runs and their subsequent analysis, are used to estimate measures of performance for the system designs that are being simulated. Steps in a Simulation Study Modeling and Simulation 22
- 23. 10. More runs? Given the analysis of runs that have been completed, the analyst determines whether additional runs are needed and what design those additional experiments should follow. Steps in a Simulation Study Modeling and Simulation 23
- 24. 11. Documentation and reporting There are two types of documentation: progress. Steps in a Simulation Study Modeling and Simulation 24 program and Program documentation is necessary for numerous reasons. If the program is going to be used again by the same or different analysts, it could be necessary to understand how the program operates. Also, if the program is to be modified by the same or a different analyst.
- 25. 11. Documentation and reporting Progress reports provide the important, written history of a simulation project. Project reports give a chronology of work done and decisions made. Steps in a Simulation Study Modeling and Simulation 25
- 26. 11. Documentation and reporting “it is better to work with many intermediate milestones than with one absolute deadline.” Possibilities prior to the final report include a model Steps in a Simulation Study Modeling and Simulation 26 training results, intermediate analyses, specification, prototype demonstrations, animations, program documentation, progress reports, and presentations.
- 27. Steps in a Simulation Study Modeling and Simulation 27 12. Implementation The success of the implementation phase depends on how well the previous eleven steps have been performed.