Simulation Modeling with SIMIO: A Workbook - Preface

This edition of this workbook maintains the successful “participatory” style introduced in the first edition. You don’t sit and read the book without a computer loaded with SIMIO (the book was created using version 7.124 of SIMIO™).  We expect your active participation in using SIMIO as you turn the pages.  We try to carry on a conversation with you.  Our belief is that simulation is not a spectator sport.  You have to practice to gain skill with it and you develop that skill through modeling practice.  This book encourages you to practice and use your skill, and feedback from earlier editions appear to validate the approach. This book retains its focus on simulation modeling with SIMIO and most of the simulation statistical analysis and analytical issues are more thoroughly covered in other books.  We strongly suggest that if you are teaching/learning simulation that you also have one of these non-language books available.

We have deliberately tried to keep the price of the book low (i.e., the E-book or the paper copy).  A relatively new simulation language like SIMIO is constantly.  In fact, the SIMIO developers have a history of new releases (called “sprints”) about every three months.  Any book that describes SIMIO will go out of date quickly, so we have tried to track new features and update this book fairly often.  If the book price is low, maybe you will want to re-buy this book from time to time, so you have the latest information. Also, we feel when learning and teaching, the paper copy allows the learner to write directly in the book.

Part 1: Organization of this Edition

This edition of the workbook has an evolved structure based on use and experience.  More emphasis is placed on “why” modeling choices are made, to supplement the “how” in using SIMIO in simulation.   In Chapter 1, we present fundamental simulation concepts, independent of SIMIO which can be skipped for those who already understand these fundamentals.   In Chapters 2 through 6, concentrates of the use of the Standard Library Objects in SIMIO. You can do a lot of simulation modeling without resorting to more complex concepts.  A key part of those chapters is learning to identify/separate the data in a model from the model structure.  Chapter 7 introduces the fundamental topic of “processes,” which we frequently employ in the following chapters.  Chapters 8 and 9 concentrate on the important topics of flow and capacity.  Chapter 10 introduces optimization in the context of supply chain modeling.  Chapter 11 presents the influence of bias and variability on terminating and steady-state simulation. Chapter 12 introduces SIMIO materials handling features.  Chapter 13 extends the use of resources while Chapters 14 and 15 describes the use of workers including the detailed services provided by task sequences and their animation.  Chapter 16 details the simulation of call centers with reneging, balking, and cost optimization.  Chapters 17 through 20 presents object-oriented simulation capabilities in SIMIO.  Chapter 17 builds a model out of an existing model (we call it sub-modeling).  Chapter 18 describes the anatomy of an existing SIMIO and in Chapter 19 we build a new object by “sub-classing” an existing object.  In Chapter 20 a new object is designed and built from a base SIMIO object and its creation is contrasted with standard SIMIO object.  Chapter 21 presents some of the continuous modeling features in SIMIO.  Chapters 22 and 23 demonstrates the power of object-oriented simulation in the modeling supply chains and process planning respectively.  We include an appendix on input modeling, although SIMIO does not provide software.

The book is designed to be read from chapter to chapter, although it is possible to pick out certain concepts and topics.  Some redundancy is helpful in learning.  By the time you have finished this book you should be well-prepared to build models in SIMIO and to understand the virtues of different modeling approaches.
Like SIMIO itself, this workbook has been designed for a variety of student, teacher, and practitioner audiences.  For example, if you are interested in manufacturing, you will want to be sure to study data-based modeling in Chapter 5, assemply and packaging in Chapter 6, the workstation in Chapter 9, and material handling in Chapter 12.  If you are interested in logistics, don’t miss modeling of distances in Chapter 3, flow and capacity in Chapter 8, inventories and supply chains in Chapter 10, and free space travel in Chapter12.  If you are interested in healthcare, be sure to review scheduled arrivals in Chapter 8, resource decision making in Chapter 13, mobile workers in Chapter 14, and animated people and task sequences in Chapter 15.  If object-oreinted simulation is your interest, make sure to study Chapters 17 through 20, which describes how SIMIO provides composition and inheritance to create objects.  Manufacting examples and examples from the service sector are used throughout.  Also we pay some attention to input modeling (including input sensitivity) and output analysis (including confidence intervals and optimization).  This workbook provides comprehensive and in-depth discussion of simulation modeling with SIMIO.

At the end of most chapters, we offer commentary on topics presented.  We will emphasize the strengths and weaknesses of the modeling approach and the language (we have no financial stake in SIMIO).   To help insure that everyone participates in this active learning process, we sprinkled questions throughout the chapters.  They have short answers and require the student pay some attention to what is going on. You can use these in class.  Accordingly, even though you don’t officially take attendance, you can give credit to students who turn in their in-class assignment each day.  These practices help develop a reputation as a class you need to attend. We can provide you with answers to the questions, lecture notes, homework, and tests through a shared Dropbox™ if you contact us.

Part 2: Specific Changes in the Fourth Edition

  • In any type of software book, it is not until the book is actually used do mistakes crop up. This edition corrects several mistakes and typos that occurred in the third edition. 
  • Since the third edition, SIMIO has gone through many changes and upgrades. The second edition and to some extent the third edition just added the new features to existing chapters or added another chapter later with the same case to highlight those new features (e.g., the original Chapter 7 which introduced related tables based on the Chapter 4 case). In the new book we have combined those two chapters which is now Chapter 5. We feel related data tables are an extremely important modeling concept and needs to be introduced earlier in the development of the simulation model.
  • Also, we moved all the material handling to a standalone chapter (i.e., Chapter 12).  For those who would like to have material handling sooner, Chapter 12 can be introduced any time after the Chapter 7 which introduces processes. 
  • As mentioned earlier, a new Chapter 1 which introduces simulation fundamentals which caused the original Chapters 1 - 3 to shift to Chapters 2 – 4. Chapter 3 introduces the concept of Input Sensitivity which is further explored in the new Chapter 11 devoted to Simulation Output Analysis. We do a more thorough job of using confidence intervals to examine output.
  • Chapter 6 is now the original Chapter 5 which introduced combiners for the memory chip problem. However, the chapter is now followed directly by the processes chapter (i.e. Chapter 7) based on the same memory chip problem rather than waiting several chapters as was done before.
  • The new concept of Tokenized processes which allows one to create a generic process that can be passed input parameters to specialize the process are an important concept. No longer do you have to have almost identical processes. Tokenized processes are utilized in Chapters 7, 9, and 15.
  • In the first three editions, the original Chapter 9 and 10 utilized a simple clinic to introduce concepts of flow and capacity where chapter 9 was a little obsolete by the third edition. These two chapters were combined into the new Chapter 8 improving the flow along with a different case (i.e., the DMV).
  • Some chapters were just refreshed and updated to the new versions but have moved within the book. For example, Chapter 9 and 10 are just refreshed versions of Chapter 8 and 11 from the third edition.  However, Chapter 9 does utilize Tokenized processes when producing the materials in the JIT section.
  • Chapters 13 and 14 were combined into one chapter (Chapter 13) improving the flow. Another example was added to the earlier editions when new features were added.
  • Chapter 15 was updated to use the new Reserve option for acquiring resources. Also, SIMIO has introduced more process capability beyond simple processing times by using the task sequences. Chapter 15 explores the various features related to tasks utilizing the bank problem.
  • Chapter 20 is now the new object chapter and was updated to include states and different animation pictures along with capacity.
  • Consistent with the third edition, the continuous chapter, Chapter 21 is located after the discussion of objects. However, a new section was added that utilizes the new container entity, filler, and emptier objects.
  • The more advanced Chapters 22 (Shirt Folding Line), 25 (Lean Systems), and 26 (Multiple product) were not included in this version for several reasons. Many of the new features of SIMIO have made some of the tricks used since the first edition obsolete.  Also we needed to limit the length of the book. If anyone would like access to these chapters, we can provide you with the pdf and models of these chapters not included.

Part 3: Styles Used in this Book

Certain styles have been used in this book to illustrate objects, names and parameters and to make it easier to distinguish these types of parameters. Standard SIMIO objects will be set in small caps using a Courier New font (e.g., Server) while objects that are created by the modeler will be also bolded (e.g., DelayObject). Properties associated with these objects will be italicized (e.g., Processing Time).  Process names will be italicized and placed in quotes, as “OnEnteredProcessing”, while Add-on process triggers (e.g., Exited) will be will be only italicized since they are properties.   Process steps like Assign will be set in italicized in Courier New font.  SIMIO uses lots of expressions.  These are set in Courier New font (e.g., SrvOffice.Contents >0).  Names of all objects specified by the modeler will be bolded (e.g., Insert a Server named SrvOffice). Values associated with properties will be set in a fashion similar to expressions or in quotes for strings (e.g., “True”).

Part 4: Acknowledgements

We wish to thank our students, who have added much to our understanding and who let us often display our ignorance. Also we thank the many colleagues and friends (new and old) who have read, commented as well as used the book in their classes – hopefully they know who they are. In our writing this book, we appreciated the response of SIMIO developers and SIMIO Support to our endless stream of questions and doubts, especially Dave Sturrock and Dennis Pegden.  Finally we thank our families for understanding and patience as we often spend more time talking with each other than with them.

Please let us know how we can improve this workbook and how it can better meet your needs.

Jeff Joines (JeffJoines@ncsu.edu)

Steve Roberts (roberts@ncsu.edu)

North Carolina State University

Raleigh, North Carolina