# Chapter 15 Application of Computer Simulation and Modeling.

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Chapter 15 Application of Computer Simulation and Modeling

Objectives After reading the chapter and reviewing the materials presented the students will be able to: Understand the concept of simulation. Able to apply simulation to evaluate layout and material flow.

Introduction Simulation packages currently available perform real world and interactive simulations. They also require a relatively small investment of time on the part of the novice in order to develop a working knowledge of the simulation process. Many health care facilities are also turning to computer simulation to reduce cost and provide better service.

Defining Computer Simulation Simulation is defined as an experimental technique, usually performed on a computer, to analyze the behavior of any real world operating system. Simulation can be used to predict the behavior of a complex manufacturing or service system.

Advantages and Disadvantages of Simulation Advantage: Simulation allows us to observe the behavior of a system without actually disturbing the real individuals, layout, or equipment. Effects of changes on system can be observed and measured without actually changing the real work environment. Once a feasible solution is found, it can be implemented. Disadvantage: Development of some complex models may be expensive and time consuming.

Simulation in Facilities Planning Facility planners can use simulations to study various aspects of facilities design, capacity planning, inventory policies, office and parking lot layouts, quality and reliability systems, warehousing and logistics planning, and maintenance scheduling. By using simulations, the planner can compare various alternatives and study various scenarios before costly implementations and blunders.

How Simulation Works 1. Problem definition: What questions do I wish to find answers? 2. System definition: time, space, and financial constraints. 3. Conceptual model: Develop a graphical model to define system components, variables, and their interactions that constitute the system. 4. Preliminary design: What data need to be gathered from the model, in what form, and to what extent. 5. Input data preparation: Ascertain the integrity of data input. The output is only as reliable as the input data. 6. Model translation: Develop a working knowledge of the simulation package. 7. Verification and validation: Confirm that model represents system. 8. Experimentation: Learn how various changes can affect the output of the system. 9. Analysis and interpretation: Validity of output depends on validity of input data. 10. Implementation and documentation: Results can be recorded, documented, and implemented.

Reasons for Simulation 1. Evaluation: Determine and measure how well the system design performs when compared against set criteria. 2. Comparison: Compare alternative designs to carry out a specific function. 3. Prediction: Investigate performance of proposed system under specific conditions over a period of time. 4. Sensitivity analysis: Sensitivity analysis helps determine which of the many factors and variables have the greatest effect on the overall operation of the system. 5. Optimization: What factors or combination of factors produces the best overall system response. 6. Bottleneck analysis: Discover the nature and location of bottlenecks affecting the flow of the system.

Overview of Layout and Simulation Software The first classification consists of software packages that can aid in the planning and design of the layout. Software systems include STORM, FactoryCAD, FactoryPLAN, and SPIRAL. The second category includes simulation and performance analysis systems. Software systems include PROMODEL, FactoryFLOW, FACTOR/AIM, and ARENA.

Computer Aided Layout Design FactoryCAD is a powerful drawing tool that can be used for industrial and manufacturing layout. By customizing AutoCAD, FactoryCAD makes it easy to create, refine, improve, and edit either new or existing drawings FactoryPLAN is a tool for a tool for designing and analyzing layouts based on the desirability of closeness of different departments, work areas, offices, storage areas, or manufacturing cells. Whereas FactoryCAD can aid in the drawing of the plant layout FactoryPLAN is a planning tool that can be used to analyze and optimize the layout. FactoryOPT, working with FactoryPLAN determines the optimum locations of the activity centers, and hence the optimum plan layout.

Computer Assisted layout Performance Analysis FactoryFLOW is a layout analysis tool that integrates facilities drawings and material flow paths with production and material handling data. The planner can, in real time, easily make changes to the model, routings, production volumes, material handling equipment, and other system variables, in order to examine various alternatives. The analysis can help the designer to eliminate or reduce non value added steps, to reduce travel distances, to increase product throughput, to reduce work in process inventory, and to determine material handling requirements. ProModel is a user friendly simulation and analysis tool that is available to the facilities planner. The software can aid the planner to analyze an existing facility or to develop a new plant. By playing various what-if scenarios and running the simulation, one can determine whether the proposed changes have a positive effect on the manufacturing facility before implementing the changes on the factory floor.

Case Study – Simulation in Health Care A simulation study to assess and improve the operations of emergency department at Florida health care facilities: The purpose of the simulation was to examine the sequencing of triage and registration activities. The simulation showed that both triage and registration were shown to be activities on the critical path (the amount of time required for these activities significantly affected the overall turnaround time). The model showed that the location of these activities did not affect the overall performance of the system. The model showed that additional X ray facilities were not required regardless of general belief. The reduction in operating hours of two of the units did not affect the third unit – proper patient flow could still be maintained. The findings aided improved overall utilization of resources, and reduced overall length of stay for the patients.

Summary Simulation packages currently available perform real world and interactive simulations. Simulation is defined as an experimental technique, usually performed on a computer, to analyze the behavior of any real world operating system. Simulation can be used to predict the behavior of a complex manufacturing or service system. Advantage: Simulation allows us to observe the behavior of a system without actually disturbing the real individuals, layout, or equipment. Effects of changes on system can be observed and measured without actually changing the real work environment. Once a feasible solution is found, it can be implemented. The first classification consists of software packages that can aid in the planning and design of the layout. Software systems include STORM, FactoryCAD, FactoryPLAN, and SPIRAL. The second category includes simulation and performance analysis systems. Software systems include PROMODEL, FactoryFLOW, FACTOR/AIM, and ARENA. FactoryCAD can aid in the drawing of the plant layout FactoryPLAN is a planning tool that can be used to analyze and optimize the layout. FactoryOPT, working with FactoryPLAN determines the optimum locations of the activity centers, and hence the optimum plan layout. FactoryFLOW is a layout analysis tool that integrates facilities drawings and material flow paths with production and material handling data. ProModel is a user friendly simulation and analysis tool that is available to the facilities planner.

Home Work 1.What is simulation? 2.What is the advantage of simulation?