Operations Research, Systems Engineering and Industrial Engineering Commons^™

A Multithreaded Scheduler For A High-Speed Simulator, Gene Saghi, Kirk Reinholtz, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

The Cassini spacecraft is on its journey to Saturn to perform a close-up study of the Saturnian system; its rings, moons, magneto-sphere, and the planet itself. Sequences of commands will be sent to the spacecraft by ground personnel to control every aspect of the mission. To validate and verify these command sequences, a bit-level, high-speed simulator (HSS) has been developed. To maximize performance, the HSS is implemented with multiple threads and runs on a multiprocessor system. A key component of the HSS is the scheduler, which controls the execution of the simulator. The general framework of the scheduler can be …

An Integrated Approach To Simulation And Activity-Based Costing For Evaluating Alternative Manufacturing Cell Designs, Robert Williams, Paul Savory, Rodney Rasmussen

Department of Industrial and Management Systems Engineering: Faculty Publications

One effective technique for improving manufacturing efficiency involves the application of group technology part families and manufacturing cells. Selection of the best or optimum configuration of the manufacturing cell relies on the experience and judgment of the cell designer. This paper describes how activity-based costing (ABC) concepts can be integrated into a discrete-event simulation model and be used to evaluate manufacturing cell configurations. The output of the combined ABC simulation model provides a detailed “Bill of Activity” which allows the cell designer to consider costs as a critical factor in the cell design problem. Alternative cell configurations studied in this …

Simulating Queue Scheduling Policies For A Spacecraft Simulator, Paul Savory, Gene Saghi

Department of Industrial and Management Systems Engineering: Faculty Publications

The mission of the Cassini spacecraft is a unique opportunity to gain insights into major scientific questions about Saturn, the creation of the solar system, and the conditions that led to life on Earth. In preparation for the launch, NASA's Jet Propulsion Laboratory developed a software simulator to emulate the hardware data-control system of the spacecraft. Its primary use is to validate and verify commands that will be transmitted to the spacecraft. To improve the performance of the simulator, we used the SIMAN simulation language to model numerous queue-scheduling policies. Implementation of the simulation results combined with a software-code redesign …

Selecting For Random Drug Testing At Union Pacific Railroad, Jennifer Meyer, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

Many industries have recently implemented programs to detect and deter the use of recreational drugs in the workplace. The transportation industry has received careful government attention, particularly where the safety of the public may be seriously affected by employees who use drugs. Following federal guidelines, Union Pacific Railroad first implemented a random drug-testing plan in 1990. Because the assigned jobs, shifts, and work locations of many railroad employees change frequently, defining the selection population was particularly challenging. In its continuing efforts to validate and improve this plan, Union Pacific Railroad sought an external evaluation to determine the fairness of its …

An Aggregation Procedure For Simulating Manufacturing Flow Line Models, Paul Savory, Gerald Mackulak

Department of Industrial and Management Systems Engineering: Faculty Publications

We develop a formal method for specifying an aggregate discrete-event simulation model of a production flow line manufacturing system. The methodology operates by aggregating production stations or resources of a flow line. Determining the specifications for representing the aggregated resources in a simulation model is the focus of our presentation. We test the methodology for a set of flow lines with exponentially distributed arrival and service times. Comparisons between analytical and simulation results indicate the aggregation approach is quite accurate for estimating average part cycle time.

Cycle Time Estimation For Simulating A Tandem Queueing Systems Using Aggregation Techniques, Paul Savory, Gerald Mackulak

Department of Industrial and Management Systems Engineering: Faculty Publications

One approach to simulating a single-server tandem queuing system is to explicitly model each of the production stages. In this paper, we apply queueing theory, a recursive algorithm, and composite random number sampling to develop an equivalent aggregate representation consisting of only a single production stage. Preliminary test results indicate that the aggregation works well for estimating the mean and variability of the total cycle time.

Using Mathematica To Aid Simulation Analysis, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

As computer power has increased, so has the capability of software developers to write programs that assist people with time-consuming tasks. Mathematica is such a program. The objective of this paper is to demonstrate how Mathematica, a symbolic programming environment, can be used to aid simulation analysis. In addition to a general discussion of Mathematica’s uses, advantages, and disadvantages, several examples will be presented. The examples include using Mathematica for distribution fitting, queueing analysis, random number generation, and creating a surface plot for optimization.

Issues In Developing An Undergraduate Simulation Course, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

Experience in developing an undergraduate simulation course is described. The course introduces the philosophies, principles, and methodologies for discrete-event simulation modeling. Strategy in choosing the course simulation software is discussed, plus important areas of teaching emphasis are highlighted.

Simulation Project Characteristics In Industrial Settings, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

In a survey of practitioners of discrete-event simulation from industry and research institutes who "build models for money," we asked about project goals, user backgrounds and training, organizational types and activities, software and hardware choices, modeling team composition, and effort allocation within a modeling project. We found that (1) only about half of the practitioners have three or more years experience, (2) many academics feel strongly affiliated with their industry clients rather than with their university employers, (3) shop-floor supervisors rarely lead simulation projects, even though their knowledge of the system may be unparalleled, (4)simulation models are generally described as …

The Science Of Simulation Modeling, Paul Savory, Gerald Mackulak

Department of Industrial and Management Systems Engineering: Faculty Publications

Many people refer to simulation model building as an “intuitive art”. This implies that modeling can only be done by a select group of highly trained creative people and thus isolates many from considering simulation as a usable tool. Model building is a science that is learned through education, training and experience. In this paper, we discuss the role of science in performing a simulation study. We illustrate the teaching of the science of simulation by discussing the simulation curriculum at Arizona State University.

Extending Simulation’S Advantages To Novice Model Builders: Intellisim Tutorial, Paul Savory, Gerald Mackulak, Jeff Cochran

Department of Industrial and Management Systems Engineering: Faculty Publications

The potential benefits that discrete-event simulation offers are impeded by the high level of expertise necessary to successfully conduct a sound simulation study. As a solution, this paper introduces IntelliSIM, an intelligent simulation environment. Using this environment makes simulation more accessible to users by reducing the need for extensive experience or training. One of IntelliSIM’s key features for accomplishing this is a tutorial and training module that quickly acquaints a novice simulation user with IntelliSIM’s features and the process of performing a simulation study. This paper discusses this tutorial by explaining how IntelliSIM develops a simulation model, thus illustrating how …

Ascertaining Important Features For Industrial Simulation Environments, Gerald Mackulak, Jeffery Cichran, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

Recent years have witnessed the development and commercial release of multiple simulation tools, environments, and intelligent simulators. Each release seems to contain additional advanced features designed to simplify simulation use and increase the productivity of model builders. But to date, no one has addressed feature definition from the viewpoint of a simulation practitioner. This paper discusses our efforts to identify and prioritize simulation features deemed most desirable from the practitioner viewpoint. A series of three questionnaires were developed and administered to a group of qualified simulation practitioners. With results that are of interest to simulation users, researchers, and simulation software …

A Robust Aggregation Approach To Simplification Of Manufacturing Flow Line Models, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

One of the more difficult tasks facing a modeler in developing a simulation model of a discrete part manufacturing system is deciding at what level of abstraction to represent the resources of the system. For example, questions about plant capacity can be modeled with a simple model, whereas questions regarding the efficiency of different part scheduling rules can only be answered with a more detailed model. In developing a simulation model, most of the actual features of the system under study must be ignored and an abstraction must be developed. If done correctly, this idealization provides a useful approximation of …

A Robust Aggregation Approach To Simplification Of Manufacturing Flow Line Models, Paul Savory

Industrial and Management Systems Engineering: Presentations

One of the more difficult tasks facing a modeler in developing a simulation model of a discrete part manufacturing system is deciding at what level of abstraction to represent the resources of the system. For example, questions about plant capacity can be modeled with a simple model, whereas questions regarding the efficiency of different part scheduling rules can only be answered with a more detailed model. In developing a simulation model, most of the actual features of the system under study must be ignored and an abstraction must be developed. If done correctly, this idealization provides a useful approximation of …

Introduction To Intellisim 2.0, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

IntelliSIM is a prototype for a new generation of knowledge-based simulation tool that has been developed by the Systems Simulation Laboratory at Arizona State University. This tool is a computer environment that allows non-simulation trained modelers to predict the performance of a manufacturing system for which the necessary data is available. The system provides predictive data on such items as throughput time, queue levels, equipment utilization, reactions to machine failures, etc. With IntelliSIM, the benefits of discrete-event simulation can be exploited without requiring the high level of expertise necessary to successfully conduct a sound simulation study. The approach offered with …

Introduction To Intellisim 1.0, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

IntelliSIM is a prototype for a new generation of knowledge-based simulation tool that has been developed by the Systems Simulation Laboratory at Arizona State University. This tool is a computer environment that allows non-simulation trained modelers to predict the performance of a manufacturing system for which the necessary data is available. The system provides predictive data on such items as throughput time, queue levels, equipment utilization, reactions to machine failures, etc. With IntelliSIM, the benefits of discrete-event simulation can be exploited without requiring the high level of expertise necessary to successfully conduct a sound simulation study. The approach offered with …

Material Handling In A Flexible Manufacturing Systems Processing Part Families, Paul Savory, Gerald Mackulak, Jeff Cochran

Department of Industrial and Management Systems Engineering: Faculty Publications

The objective of this simulation study is to analyze the system performance of a six machine flexible manufacturing system cell in which a material handling system is to be incorporated. The analysis focuses on determining the production potential of the cell by grouping common parts into "families". To accomplish this, computer simulation models are developed using the SIMAN simulation language.

Initially the manufacturing cell is modeled with no material handling system to get an upper bound estimate of production output. We next explore the impact that an automatic guided vehicle (AGV) has on system performance of the manufacturing system cell. …

Lpsolver: A Linear Program Solving Package For Educational And Instructional Modeling Applications, Paul Savory, Jeffrey Arthur

Department of Industrial and Management Systems Engineering: Faculty Publications

LPSOLVER is a computer program developed to be a learning tool for students studying linear programming. This technical paper contains and overview of what LPSOLVER is and how to use it. The program allows one to enter linear programs in three different formats which are discussed in Section IV. Described in Section VI are the two methods available for solving linear programs. Other features of LPSOLVER are discussed in Section VII. Appendix A describes all the various files that LPSOLVER uses/creates. A listing of error messages is given in Appendix B. Information about how the program was implement is contained …