WSC 2001 Final Abstracts

Transportation, Logistics, and Distribution Track

Monday 10:30:00 AM 12:00:00 PM
Distribution and Material Movement Applications

Chair: Kevin Gue (Naval Postgraduate School)

Efficiently Modeling Warehouse Systems
David Burnett (Ryder Ingegrated Logistics) and Todd LeBaron (Brooks AutoMation, Autosimulations Business Unit)

The proliferation of e-business has demanded that supply-chains include increasing performance on distribution and order fulfillment operations. Simulation has aided in meeting this demand from both engineering solution design and business development perspectives. Ryder System, Inc. has created a model to be used as an engineering tool to validated an automated design, predict resource requirements, and determine operational throughput capacities for its E-channel operations. The model’s flexible demand generation and operating parameters allow potential clients to quickly witness “what-if scenarios“ of their operations. Resources, volumes, and wave creation strategies can be varied in each scenario. Many common attributes can be found in the different warehouse systems in operation today. The data parameterization of common system attributes, and specific applications of the model will be presented. Finally, the benefits and limitations of template modeling will be discussed.

An Object-Oriented Paradigm for Simulating Postal Distribution Centers
K. Preston White, Jr. (University of Virginia), Brian Barney, Scott Keller, Robert Schwieters, and Jacqueline Villasenor (none) and William S. Terry, Richard G. Fairbrother, and Richard D. Saxton (Distribution Technologies)

Discrete-event simulation is an established tool for the design and management of large-scale mail sortation and distribution systems. Because the design of distribution facilities integrates many of the same or functionally similar components, adopting an object-oriented approach to simulation promises significant economies. Instead of coding and verifying models de novo for each facility, component subsystem, or individual process, object orientation allows engineers to reuse validated code stored in an objects library. In this paper, we illustrate how the procedural language AutoMod--a leading commercial simulation package widely accepted in the industry--can be adapted for use within a hierarchical, object-oriented paradigm. A principal contribution is the design of a configuration management plan, which defines a structured process to control and account for the development and maintenance of procedural code and graphics stored in the objects library.

Using Simulation to Evaluate Site Traffic at an Automobile Truck Plant
Joseph C. Hugan (Forward Vision Services)

Recent trends in automotive manufacturing have increased the focus on the Just-In-Time (JIT) delivery of automotive components. By requiring smaller batches of parts delivered more frequently, automobile assembly plants now need methods for handling and understanding how the increased traffic will effect the safety and operation of their overall site. This paper focuses on the use of discrete event simulation to address the many traffic related considerations brought on by this more aggressive inventory method. The model considered factors such as plant schedule, gate staffing, vehicle production, truck size, travel time, vehicle speed, loading time, and marshalling requirements. This paper will focus on the construction of the model, its data file flexibility, and the results of the experiments evaluated during the project.

Monday 1:30:00 PM 3:00:00 PM
Airline and Airport Applications

Chair: Joe Drelling (Northwest Airlines)

Simulation Optimization of Airline Delay with Constraints
David W. Hutchison (The Johns Hopkins University) and Stacy D. Hill (Johns Hopkins University Applied Physics Laboratory)

Air traffic delay is a growing and expensive problem. We investigated ways to reduce the cost and magnitude of such delays by trading gate delays against more expensive air delays. Air management and planning at this level can be facilitated by simulation, especially for strategies that alter controls on the system. We used the SIMMOD air traffic simulation to model the system. The objective was to determine a set of control measures that achieve the best system performance subject to restrictions on the decision parameters and selected system output measurements. Because observed system performance is “noisy,” the problem is a constrained stochastic optimization problem with nonlinear objective function and nonlinear, stochastic constraints, which requires efficient stochastic optimization methods for its solution. Our approach used the simultaneous perturbation stochastic approximation (SPSA) algorithm with a penalty function to handle the difficult constraints.

Simulation of Check-In at Airports
Paul E. Joustra and Nico M. Van Dijk (Incontrol Enterprise Dynamics)

The purpose of this paper is to describe: Why simulation is necessary to evaluate check-in. · A simulation toolbox for check-in counters. · Two case studies for Amsterdam Airport Schiphol. First, it is discussed why queuing theory results are too limited but nevertheless useful to predict queuing times for check-in counters at airports. Next the necessity of simulation is emphasized and a special purpose simulation tool-box is presented. The toolbox is suited for several purposes; (1) analyzing operational check-in rules (e.g. common instead of dedicated check-in, (2) overflow for economy class passengers to business class counters), performing capacity studies, (3) evaluating the operational planning of check-in counters and (4) improving personnel planning. Finally two simulation studies are outlined that are conducted with the toolbox for Schiphol: one to evaluate operational check-in rules and one to determine the growth capacity of Schiphol with the current check-in facilities.

Hybrid Agent-Based Simulation for Analyzing the National Airspace System
Seungman Lee, Amy Pritchett, and David Goldsman (Georgia Tech)

Hybrid agent-based simulation is required to provide a mechanism for analyzing large-scale complex systems, such as the National Airspace System (NAS). The dynamic behavior of many complex systems is, in general, hybrid in nature and can be best described by a combination of discrete-event and continuous-time models, and their interactions. Correspondingly, hybrid agent-based simulation capable of incorporating different types of models provides an accurate means of evaluating the reliability and performance of complex systems. However, in order to serve as a design and analysis tool, a number of issues must be addressed. This paper outlines issues in the development of hybrid agent-based simulation architectures capable of providing a scaleable mechanism for simulating the NAS. In particular, an object-oriented approach is described. In addition, methods of improving computational efficiency of updating the simulation are described and compared.

Monday 3:30:00 PM 5:00:00 PM
Railroad Applications

Chair: Mani Manivannan (Emery Worldwide)

The Use of Simulation to Calculate the Labor Requirements in an Intermodal Rail Terminal
Beth C. Kulick and James T. Sawyer (Automation Associates, Inc.)

An intermodal rail terminal is a facility where the transfer of cargo occurs between truck and rail. The operations within these terminals involve many resources and operating rules. The ability of a terminal to respond to activity peaks that occur as a result of train arrivals and departures is critical. In order to explore how operations can be improved given the dynamics of resource and demand interactions, a simulation model was developed to assist in understanding and exploring areas where throughput can be improved. The model was constructed such that capacity issues could be explored incrementally. The first focus was for understanding if efficient deployment of labor resources could provide desired throughput.

Simone: Large Scale Train Network Simulations
Dick Middelkoop (Railned) and Michiel Bouwman (Incontrol Enterprise Dynamics)

This paper describes the architecture and potentials of Simone. Simone is a simulation environment to generate, simulate and analyze complex and large scale train networks. The purpose of Simone is to * Assess the robustness of timetables * Determine the stability of the network * Analyze causes and effects of delays * Improve timetables, by determining the relations between design standards and robustness of the timetable * Detect and quantify bottlenecks in a train network * Quantify delays for different layouts of railway infrastructures. A strong feature of Simone is the ability to automatically generate ready-to-use network simulation models from databases. First, the concepts are described, then two case studies are presented. Last, the paper ends with a short evaluation of the use up till now and forthcoming developments for Simone.

Simulation Modeling at Union Pacific Railroad
Malay A. Dalal and Lawrence P. Jensen (Union Pacific Railroad)

Despite the potential, the use of simulation technology at US railroads appears to be lagging behind that in manufacturing and other transportation industries. This paper describes three recent experiences of applying simulation at Union Pacific Railroad: validation of yard-queuing data used in a railroad operations planning and control system, evaluation of work-rest patterns for scheduling train crews, and evaluation of strategic transportation plan. Collectively they demonstrate the wide spectrum of possible applications in terms of domain, development effort, planning horizon, etc. We conclude with thoughts on how to promote the use of simulation in the railroad environment.

Tuesday 8:30:00 AM 10:00:00 AM
Roadways, Vehicle, and Traffic Applications

Chair: Ed Williams (Ford Motor Company)

Defining Models of Urban Traffic Using the TSC Tool
Mariana Lo Tártaro and César Torres (Universidad de Buenos Aires) and Gabriel Wainer (Carleton University)

ATLAS is a specification language defined to outline city sections as cell spaces. A static view of the city section to be analyzed can be defined, and a modeler is able to define complex traffic models in a simple fashion. A compiler for this specification language (called TSC) was built. The language implements the ATLAS constructions as Cell-DEVS models. The rule generation for describing the traffic behavior is based on macro templates, entitling changes in the model implementation in a flexible way. The formal specification avoids a high number of errors in the developed application, and the problem solving time is highly reduced.

An SLX-Based Micro-Simulation Model for a Two-Lane Road Section
Marco Lemessi (University of Rome)

A car-following and lane-changing micro-simulation model of a two-lane road section has been written in SLX (Simulation Language with eXtensibility) as part of an extensive research project by the University of Rome Transport Department to qualify and quantify the environmental impact of traffic. The micro-simulation model is part of a three-step approach, involving a traditional transport macroscopic model, the microscopic model, and an ultra-micro model. The micro-simulation model’s car-following and lane-changing rules are presented and described in detail, and model outputs are commented. The paper includes a short description of the Microsoft Visual Basic user-interface developed by the author and the animation performed by means of Proof Animation.

Simulation of a Night Taxi-Bus Service for the Historical Center of Rome
Thomas Schulze (Otto-von-Guericke University Magdeburg,FIN-WI) and Marco Lemessi and Francesco Filippi (University of Rome )

The Municipality of Rome plans to introduce a taxi-bus system as a night service. A micro-simulation model was developed to estimate the needed information. Two major topics regarding this model are presented. First, the iteration process for input parameters is described. The number of potential customers is determined by means of an external modal split model. Two input parameters (frequency of trips and travel times) for the external model are estimated by the micro-simulation model. An iteration process was used. The second topic is the integration of an optimization model into the micro-simulation model. Both simulation and optimization components were implemented in the simulation system SLX®.

Tuesday 10:30:00 AM 12:00:00 PM
Transport Applications

Chair: Joe Hugan (Forward Vision)

Architecture Using Jini Technology for Simulation of an Agent-Based Transportation System
Lisa A. Schaefer (The MITRE Corporation)

This paper describes an architecture for the simulation of a transportation system that uses agent technology to deliver people and goods from their origins to their destinations. The intent of the architecture is to analyze incremental changes to the existing transportation paradigm to determine what type of system we could plan for in the future. Each entity within the system that has computational power is simulated as an agent. This architecture is useful for experimenting with many different algorithms and strategies for improving transportation systems.

A Preliminary Study of Tramming Speeds in Multiple Tele-Operated Load-Haul-Dump Scenarios Using QUEST®
Neil Runciman (INCO Limited )

Tele-operated Load Haul Dump (LHDs) machines are becoming a common tramming solution throughout many mines at INCO Limited in Copper Cliff, Ontario, Canada. To reach maximum productivity from multiple teleoperated LHDs, the system must achive a proper balance of LHD speed in the haulage network and haulage layout geometry. A study was inititated to determine if multiple LHDs, tramming in second gear under automatic guidance, would influence the total throughput of a production process. A simulation model was used to evaluate the haulage system throughtput with the LHDs tramming in second gear while under automatic guidance. The study indicated that allowing LHDs to operate in second gear for the specificed haulage layout configuration, may not provide an increase in the system capacity. The paper concludes that further investigation of key tramming system variables should be carried out to optimize LHD speed with the haulage layout geometry.

Modeling Risk in the Dynamic Environment of Maritime Transportation
Jason R. W. Merrick (Virginia Commonwealth University) and J. René van Dorp, Thomas A. Mazzuchi, and John R. Harrald (The George Washington University)

The Washington State Ferries are one of the largest ferry systems in the world. Accidents involving Washington State Ferries are rare events. However, low probability, high consequence events lead to difficulties in the risk assessment process. Due to the infrequent occurrence of such accidents, large accident databases are not available for a standard statistical analysis of the contribution of perceived risk factors to accident risk. In the WSF Risk Assessment, a modeling approach that combined system simulation, expert judgement and available data was used to estimate the contribution of risk factors to accident risk. Simulation is necessary to capture the dynamic environment of changing risk factors, such as traffic interactions, visibility or wind conditions, and to evaluate future scenario's that are designed to alter this dynamic behavior for the purposes of risk reduction or improved passenger service. This paper describes the simulation component of the model used in the Washington State Ferries Risk Assessment.

Tuesday 1:30:00 PM 3:00:00 PM
Material Flow and Inventory Control Applications

Chair: Voratas Kachitvichyanukul (Asian Institute of Technology)

Modeling Continuous Flow with Discrete-Event Simulation
S. Stephen Kuo (BASF) and E. Jack Chen, Paul L. Selikson, and Young M. Lee (BASF Corporation)

This paper describes the application of discrete event simulation to study continuous material flow. Logistics is an integrated part of most manufacturing companies. The purpose of this study is to determine the required logistics opertions to allow continuous operations of a chemical manufacturing plant. The application has been used to provide critical decision support.

Staging Queues in Material Handling and Transportation Systems
Kevin R. Gue and Keebom Kang (Naval Postgraduate School)

In most physical queueing applications, customers join a queue and move forward after each service, leaving room for others to join behind them. Some queues found in material handling and transportation systems do not operate like this because the queued entities (pallets or unoccupied cars, for example) are incapable of moving forward autonomously. We develop a model for the resulting staging queue, and give simulation results for several configurations.

Simulation and Analysis of Dealers' Returns Distribution Strategy
Hui Zhao (Purdue University)

Due to high demand uncertainty, excess inventory has been a key issue in inventory control. Caterpillar developed the dealers' parts inventory sharing (DPIS) and returns programs to help dealers cope with excess inventory. However, historical data show that the current returns policy has been very costly to Caterpillar due to the distribution strategy. In this project, we develop alternative returns policies and propose to use simulation to analyze the cost structure of the alternative policies, develop cost sharing schemes, and compare performance with the current policy under different scenarios. It is shown that the simulation tool we developed provides industry managers with a test ground for new returns strategies and the output analysis presents guidelines to set parameters when using the new strategies to manage returns distribution.

Tuesday 3:30:00 PM 5:00:00 PM
Supply Chain Applications I

Chair: Sanjay Jain (Accenture)

Designing the Support Logistics for the FAA ACE-IDS System
Ricki G. Ingalls and John W. Nazemetz (Oklahoma State University)

The Federal Aviation Administration (FAA) is beginning to field the Automated Surface Observing System Controller Equipment – Information Display System (ACE-IDS) and required a study on the service logistics for the system. The ACE-IDS is a combination of commercial-off-the shelf (COTS) and custom built hardware and software components interfaced with existing FAA and National Weather Service (NWS) systems. The ACE-IDS includes a set of networked workstations capable of displaying selected subsets of data from 10,000 predefined screens and extends the capability of the current Automated Surface Observing System (ASOS). These screen displays are populated in real time using data from a variety of FAA and NWS systems such as the ASOS, the Automation of Field Operations and Service (AFOS), and the Flight Data Input/Output (FDIO) systems. This paper outlines a simulation study that was used to develop spares and inventory strategies for the deployment of ACE-IDS.

Analyzing the Supply Chain for a Large Logistics Operation Using Simulation
Sanjay Jain, Eric C. Ervin, Andrew P. Lathrop, Russell W. Workman, and Lisa M. Collins (Accenture)

This paper presents a case study of using simulation for analyzing the impact of proposed changes in the supply chain processes for a large logistics operation. The major changes explored include business process changes, and use of new supply chain software. The results of the analysis indicate that the changes in forecast accuracy provide much larger savings compared to process automation changes. A number of insights are drawn from the results of the analyses.

Wednesday 8:30:00 AM 10:00:00 AM
Supply Chain Applications II

Chair: Steven Brown (Arizona State University)

Development of a High-Level Supply Chain Simulation Model
Sanjay Jain, Russell W. Workman, Lisa M. Collins, Eric C. Ervin, and Andrew P. Lathrop (Accenture)

This paper describes an effort that involved development of a simulation model for evaluating the business processes and inventory control parameters of a logistics and distribution supply chain. A generic simulation tool, rather than a supply chain simulator, was developed for meeting customized needs of the effort. The paper describes the approaches used to model at the selected level of abstraction, the development of interfaces for data and experimentation and the development and delivery of animation for communicating the approach and results to the client.

Distributed Simulation with Incorporated APS Procedures for High-Fidelity Supply Chain Optimization
Peter Lendermann and Boon Ping Gan (Gintic Institute of Manufacturing Technology) and Leon F. McGinnis (Georgia Institute of Technology)

Tactical and operational planning for manufacturing enterprises are more important today than ever before as their supply chains span the globe. Two state-of-the-art technologies that are critical to success are Discrete Event Simulation and Advanced Planning and Scheduling. They are commonly applied in designing and executing operations at each site within the supply chain. However, as supply chains become leaner and more responsive, operational constraints and stochastic influences within the manufacturing sites and the logistics network require a combination of both technologies applied to the entire supply chain. This paper describes a novel framework for advanced distributed simulation with integrated APS procedures for collaborative supply chain optimization. The framework can be used for fast optimization of both planning procedures and execution policies and also provides a base for easy implementation of simulation results. A prototype of a distributed semiconductor supply chain simulation has been developed and is currently being refined.

Supply Chain Process Design Toolkit (SCPDT)
Perakath Benjamin (Knowledge Based Systems, Inc.) and Mike Graul, Richard Mayer, Michael Painter, and Charles Marshall (none)

A prominent characteristic that will distinguish successful manufacturing enterprises of the next millennium will be agility, the ability to respond quickly, proactively, and aggressively to unpredictable change. The use of extended virtual enterprise Supply Chains (SC) to achieve agility is becoming increasingly prevalent. A key problem in the construction of effective SCs is the lack of methods and tools to support the integration of processes and systems from several organizations into shared SC processes and systems. This paper describes the architecture and concept of operation of the Supply Chain Process Design Toolkit (SCPDT), an integrated software system that addresses the challenge of seamless and efficient integration. The SCPDT enables the analysis and design of Supply Chain (SC) processes. SCPDT facilitates key SC process engineering tasks including 1) AS-IS process base-lining and assessment, 2) collaborative TO-BE process requirements definition, 3) SC process integration and harmonization, and 4) TO-BE process planning and implementation.

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