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Distributed Supply Chain Simulation Across Enterprise
Boundaries
Boon Ping Gan, Li Liu, and Sanjay Jain (Gintic Institute
of Manufacturing Technology) and Stephen J. Turner, Wentong Cai, and Wen-Jing
Hsu (Nanyang Technological University)
Abstract:
The effective practice of supply chain management (SCM)
is crucial to improve corporations' competitive advantage. Many corporations
have built simulation models to facilitate the application of simulation in
designing, evaluating, and optimizing their supply chain. Traditionally, a
supply chain involves only a single enterprise with multiple facilities and
distribution centers. Hence, sharing of detailed simulation models is not a
problem in this scenario. But in recent years, the scope of SCM has evolved to
cross the enterprise boundaries. Applying simulation in designing, evaluating,
and optimizing the supply chain becomes more difficult since the participating
corporations might not be willing to share their simulation models with
partners. In this paper, distributed simulation techniques are presented as an
enabling technology that allows corporations to construct a cross enterprise
simulation while hiding model details within the enterprise. This can be
realized by either building the simulation on top of the Runtime
Infrastructure of the High Level Architecture or building the simulation on
top of a customized distributed discrete event simulation protocol. These
alternative approaches are compared in terms of their performance and
interoperability. The comparison of the performance is done through a
benchmarking test of a semiconductor supply chain model.
Optimal Production-Distribution Planning in Supply Chain
Management Using a Hybrid Simulation-Analytic Approach
Young Hae
Lee and Sook Han Kim (Hanyang University)
Abstract:
Production-distribution planning is the most important
part in supply chain management (SCM). To solve this planning problem, either
analytic or simulation approach has been developed. However these two
approaches have their own demerits in problem solving. In this paper, we
propose a hybrid approach which is a specific problem solving procedure
combining analytic and simulation method to solve production-distribution
problems in supply chain. The machine capacity and distribution capacity
constraints in the analytic model are considered as stochastic factors and
adjusted by the proposed specific process according to the results from
independently developed simulation model which includes general
production-distribution characteristics.
A Strategic Supply Chain Simulation
Model
James Ritchie-Dunham, Douglas J. Morrice, Judy Scott, and
Edward G. Anderson (The University of Texas at Austin)
Abstract:
In this paper, we describe a simulation game designed
to quantify the benefits of an enterprise resource planning system coupled
with the balanced scorecard framework in an extended enterprise. We present
three scenarios of the same enterprise: a base case scenario with a
non-integrated legacy system, a scenario with an integrated, enterprise
resource planning system, and a scenario with an enterprise resource planning
system using the balanced scorecard framework. Results from this game support
our research and teaching activities on the benefits of systems integration,
data and process standardization, visibility across the business enterprise,
improved decision support functionality, and operationalizing strategy.
A Methodology for Developing Robotic Workcell
Simulation Models
Frank S. Cheng (Central Michigan University)
Abstract:
Robotic workcell simulation is a modeling-based problem
solving approach developed for the design, analysis, and offline programming
of robotic workcells. Current industrial practices show that commercial
robotic simulation software packages are able to provide designers with an
interactive and virtual environment in which credible solutions for robotic
workcell designs can be obtained. However, conducting robotic workcell
simulation studies via robotic simulation packages require designers to carry
out complex processes of modeling, programming, and analysis, which often
results in technical challenges and difficulties. In this paper, a methodology
for developing robotic workcell simulation models via Deneb IGRIP technology
is introduced. The development of the method is based on successful
applications of Deneb's IGRIP robotic simulation software in designing real
robotic workcells.
Using Simulation to Support Implementation of
Flexible Manufacturing Cell
Kambiz Farahmand (Texas A&M
University)
Abstract:
A simulation model was developed and tested using
Taylor II to justify the implementation of a Flexible Manufacturing Cell
(FMC). The current production capacity at the existing Continuous Flow (CF)
assembly line must be increased and among other proposals, a FMC is highly
recommended. Simulation models are developed, tested, verified, and the model
sensitivity is evaluated. The simulation models provide valuable information
about performance parameters, critical elements, and bottlenecks that may
appear when the line capacities have been altered. Manufacturing line
evaluation and assessment of the improvements from one layout to the other is
accomplished by tracking performance parameters such as lead-time, throughput,
work-in process, and resource utilization. The simulation models resulted in a
more in-depth understanding of manufacturing parameters and clear
understanding of the improvements achieved by switching to FMC. The FMC model
showed a reduction in production lead-time, average WIP, the burn-in capacity,
and the number of operators required.
A Basic Study on Autonomous Characterization of Square
Array Machining Cells for Agile Manufacturing
Susumu Fujii, Hiroshi
Morita, and Takeshi Tanaka (Kobe University)
Abstract:
In this study, a manufacturing system locating
machining cells in a square array is considered as an agile manufacturing
system that can cope with a variety kinds production with varying volumes.
Each cell can process any work whose machining operations for each work are
divided into some operation groups common to all works. An auction-based
algorithm is proposed to select a cell to process a work after its processing
of one operation group. Five types of bid are considered and their effects on
the characterization of cells, i.e., concentration on the processing of
specific work kinds and operation groups, are investigated.
Dynamic Output Analysis for Simulations of
Manufacturing Environments
Peter Mullarkey and Srinagesh Gavirneni
(Maxager Technology, Inc.) and Douglas J. Morrice (Univeristy of Texas at
Austin)
Abstract:
We describe the design and implementation of a generic,
real-time, in-line output analysis procedure for controlling simulations of
discrete manufacturing environments. We implemented this capability in the
commercial simulation software Extend®. The main issues we faced were (1)
Specifying the products to evaluate, (2) Determining the batch sizes for
output analysis, and (3) Defining the stopping conditions based on the
confidence intervals. We implemented a significance test for correlation and
used this test to dynamically adjust the batch sizes used in confidence
interval estimation done using batch means. When the stability conditions have
been met, the simulation prompts the user to consider stopping the simulation.
On the other hand, if at the end of the run length selected by the user, the
statistical conditions were not satisfied, the tool notifies the user of that
fact. This capability enabled us to significantly reduce the simulation run
lengths, and ensures, with little additional computational effort, that the
results were reliable. We used this tool to control simulations of
electronics, steel, automotive, and metal processing industries. In general,
using this tool we realized a reduction of more than 40% in the time required
for simulation.
Ensuring the Successful Adoption of Discrete Event
Simulation in a Manufacturing Environment
J. Michael Knoll and
Joseph A. Heim (Genie Industries)
Abstract:
Discrete event simulation has long been recognized as a
valuable tool for manufacturers, but converting the recognition of value into
an embrace of the technology can be a challenge. Like most technologies, with
which an organization has little or no experience, timing and the manner in
which simulation is introduced can significantly influence whether its
adoption will succeed or fail. Without careful planning and adequate
foresight, simulation technology will not prove its benefits in the workplace
and will be viewed as an unnecessary expense. In this paper, we examine the
characteristics that signal the need for discrete event simulation, and we
discuss the strategies and methods we have found to ensure its successful
adoption.
Optimizing Production Work Flow Using
OpEMCSS
John R. Clymer (California State University Fullerton)
Abstract:
A graphical discrete event simulation library is
proposed for system simulation that is based on interacting concurrent
processes. This library works with EXTEND (Imagine That Inc), an inexpensive
yet capable and easy to use simulation software package, and it is called
Operational Evaluation Modeling for Context-Sensitive Systems (OpEMCSS).
Context-Sensitive Systems (CSS) is a systems theory, based on finite state
machines, that can assist a systems engineering manager, business operations
manager, or manufacturing production manager in understanding, evaluating, and
optimizing production work flow, represented as communicating concurrent
(parallel) processes. CSS theory can be expressed using the OpEM graphical
modeling language. Thus, OpEMCSS is a graphical simulation library that can
model systems based on CSS theory and the OpEM language. A simple part
production problem is discussed that is an example of applying the Classifier
Event Action block, which is a rule-based classifier contained in OpEMCSS, to
discover optimal rules to manage the workflow.
Using Simulation Techniques for Continuous Process
Verification in Industrial System Development
Par Klingstam and
Bengt-Goran Olsson (Volvo Car Corporation)
Abstract:
The purpose of this paper is to describe how discrete
event simulation should be used as a tool for continuous process verification
in industrial system development. Results include a specification of the
working procedures to be used in each life cycle phase of a development
project, as well as a definition of the areas where efforts are needed in the
future. The approach assures continuous verification of the processes, which
will lead to better decisions early on. Better decisions imply reduction in
time and costs as well as systems with high quality. In conclusion, using
simulation techniques for continuous process verification makes us more likely
to develop an optimal industrial solution.
Using Simulation for Manufacturing Process
Reengineering - A Practical Case Study
Lisete Silva, Ana Luisa
Ramos, and Pedro M. Vilarinho (Universidade de Aveiro)
Abstract:
This paper presents a simulation study carried out to
solve a problem of manufacturing process reengineering. The specific company
in which the study took place is a medium size manufacturer of chest freezers,
which required an in-depth analysis of its manufacturing operations in an
attempt to increase its throughput and overall productivity. A simulation
model of the current manufacturing system was developed to ascertain its
limitations and problems. The relevant operational performance measures were
analyzed in order to allow for the proposal of a set of changes to the actual
manufacturing operations. In order to support the decision process concerned
with the implementation of the suggested changes, these were included in the
simulation model. The outcome of the simulation study was taken into account
by the decision-makers and the recommendations are being implemented.
Confident Decision Making and Improved Throughput for
Cereal Manufacturing with Simulation
Travis A. Dahl (The Model
Builders) and Brian F. Jacob (Kellogg Company)
Abstract:
Kellogg Company faced a situation in 1999 were excess
cost had to be removed from manufacturing. A significant portion of production
had to be made relocated. Simulation played an important roll in two facets of
this project. First, it helped identify if the proposed engineering changes
would pick up the slack in production lost from relocations. Secondly,
simulation was used to develop line management set points for increasing the
output from the capacity installed.
Simulation Based Comparison of Semiconductor AMHS
Alternatives: Continuous Flow vs. Overhead Monorail
Igor Paprotny,
Jiun-Yan Shiau, Yo Huh, and Gerald T. Mackulak (Arizona State University)
Abstract:
Automation is an essential component in modern
semiconductor manufacturing. As factories migrate to 300mm technology,
automated handling becomes increasingly important for a variety of ergonomic,
safety, and yield considerations. Traditional semiconductor AMH systems such
as the Overhead Monorail Vehicle (OMV) or Overhead Hoist, can however be
prohibitively expensive. Cost projections for a 300mm inter/intrabay AMHS
installation are in the range of $50M - $100M. As an alternative, a lower cost
AMHS, called Continuous Flow Transport has been proposed. The CFT system is
similar in structure to what has historically been identified as a conveyor
based movement system. The CFT system provides cost savings at reduced
flexibility and longer average delivery time. This study compares the CFT to
Overhead Monorail transport to determine a cumulative delivery time
distribution. As expected, the CFT system requires a longer average delivery
time interval than OMV but may provide total savings through reduced transport
variability.
Simulation of an Evolutionary Tuned Fuzzy Dispatching
System for Automated Guided Vehicles
K. K. Tan and K. Z. Tang
(National University of Singapore)
Abstract:
This paper presents the development and simulation of a
novel Genetic Algorithm (GA) based methodology applied to optimal tuning of a
fuzzy dispatching system for a fleet of automated guided vehicles in a
flexible manufacturing environment. The dispatching rules are further
transformed into a continuously adaptive procedure to capitalize the on-line
information available from a shop floor at all times. The entire problem is
simulated using MATLAB/SIMULINK. The simulation results obtained show that GA
is an efficient and effective tool to achieve optimal performance for the
well-known NP-complete scheduling problem.
Automated Material Handling System Traffic Control by
Means of Node Balancing
Namdar Bahri and Robert J. Gaskins (PRI
Automation, Inc.)
Abstract:
This paper presents a logistic algorithm that improves
traffic conditions in a network-like automated material handling system
(AMHS). The algorithm uses a look-ahead procedure and series of nodal
parameters in order to balance the flow of traffic to and from load/unload
nodes. In doing so, it helps manage, distribute and allocate free AMHS
vehicles more efficiently. A simulation model of the algorithm, material
control system and the AMHS was developed and tested on various types of
semiconductor manufacturing facility layouts. The results of the simulated
algorithm demonstrate up to 30% improvement in the AMHS lot delivery time.
Simulating the Furniture Industry
Robert G.
Kyle, Jr. and Christopher R. Ludka (Sim X, Inc.)
Abstract:
The furniture industry is operating on tighter margins
and ever increasing competition. No longer are the days when one could develop
a product and market it for years, if not decades. With more competition and
ever changing consumer demands, manufacturers are frequently realizing the
necessity to reengineer their facility to satisfy the needs of many product
groups and styles. Designing facilities that recognize the need for
flexibility to reduce costs requires a clear understanding of the
interdependent relationships naturally occurring in complex cellular
manufacturing environments. However, engineers are often left to their own
inherent instincts during the design phase of a project without an analytical
tool to help them assess if their assumptions are correct or not. One of the
best tools available to provide correct evaluations of system
interdependencies is discrete event simulation. With the use of simulation,
manufacturers are able to quickly and accurately model future proposed
modifications to their facilities without making costly guesses. Furthermore,
if modeled correctly, the simulation model built to assess the significance of
a proposed layout change can be evolved into an operational planning tool that
can be utilized on a continued basis to evaluate issues such as scheduling
sequences or batch sizes.
Simulation of the Remote Unit Assembly and Test: A Case
Study
Jeff Fields, Dennis Davis, and Alfred Taylor (AT&T
Wireless Services)
Abstract:
This paper will present a case study on the use of
simulation to develop and implement an assembly line for the assembly and test
of customer located telephony equipment. The simulation model was used as a
tool to assist in development and integration of the assembly and test
processes with a focus on capacity, material flow optimization, and equipment
layout. The authors will discuss how the model affected the facilities layout,
equipment specifications, and material flow.
Reducing Gauging Lead Times and Optimizing Layout
Design at GM Powertrain with 3D Workcell Simulation
Rohit A.
Khanolkar (Applied Manufacturing Technologies, Inc.)
Abstract:
This paper describes an application of 3D-workcell
simulation for assessing feasibility of a concept Powertrain gauging process.
It provides a basic introduction to 3D-Workcell simulation and it’s associated
benefits. It describes the previous process, its limitations and problems, and
also the design reviews and iterations that were performed in simulation to
arrive at a new, optimized process. This new process minimizes operator
handling of product and also reduces the tasks involved in completing the
manual gauging operation. This paper describes how 3D-Workcell simulation was
instrumental in identifying design and layout flaws prior to equipment build
and install.
Scheduling Flow-Shops with Limited Buffer
Spaces
Michael X. Weng (University of South Florida)
Abstract:
The work described in this paper attempts to validate
the implicit assumption in traditional flow shop scheduling research that
there is a buffer of infinite capacity between any two adjacent machines. The
modified NEH (Nawaz, Encore and Ham) algorithm is used to generate an initial
permutation schedule which is then improved by tabu search. For any given
sequence, a limited equal buffer size is considered in computing job
completion times. The scheduling objective is to minimize mean job flowtime.
Computational results and analysis are presented. Through these simulation
experiments, it was found that the improvement by tabu search can be
significant and there is no need for more than 4 buffer spaces between any two
adjacent machines. Future research directions are also discussed.
Look-Ahead Strategies for Controlling Batch
Operations in Industry - Overview, Comparison and
Exploration
Durk-Jouke van der Zee (University of Groningen)
Abstract:
Batching jobs in a manufacturing system is a very
common policy in most industries. Main reasons for batching are avoidance of
set ups and/or facilitation of material handling. Good examples of batch wise
production systems are ovens found in aircraft industry and in semiconductor
manufacturing. Starting from the early nineties much research efforts have
been put in constructing strategies for the dynamic control of these systems
in order to reduce cycle times. Typically, these so-called "look-ahead
strategies" base their scheduling decision on the information on a few near
future product arrivals. In this paper we give a literature overview of the
developed strategies, evaluate their performance and explore their relevance
for practical situations by means of a simulation study.
An Analytical Model and an Optimal Scheduling Heuristics
for Collective Resource Management
Qiang Sun (Siebel Systems, Inc)
Abstract:
In the this paper, we study the problem of collective
resource management. We first introduce the problem through real-world
examples. Then we generalize the problem and build an analytical model using
queuing theory. Based on this model, we evaluate the expected average waiting
time of tasks. We present data from simulations, and compare the expected
average waiting time from theoretical calculations to that from our
experiments. We propose an optimal task scheduling heuristics. We conclude
with a brief discussion of our future research plans.
Simulation in Daily Factory Operation: 'Setting the Line
Bogey in Augusta'
Gordon D. Rehn (Deere & Company)
Abstract:
The John Deere Augusta Works uses discrete event
simulation in predicting assembly line output as a function of varying model
and option mix quantities in daily production schedules. The most unique
aspect of this application is not necessarily how it is used but who uses the
model. Prior to each production day, a Union representative executes the
model, and the simulation results establish the target production goal for the
day. Day-to-day wages are based on the actual production attained relative to
the simulated target. This paper describes the simulation tool structure
designed for Augusta, and discusses the circumstances surrounding this unique
simulation application. Included in the discussion are the benefits derived
from the application; the critical success factors enabling its use; lessons
learned in converting a simulation analysis into an operating tool; and future
improvements envisioned.
Product-Mix Analysis with Discrete Event
Simulation
Raid Al-Aomar (Classic Advanced Development Systems,
Inc.)
Abstract:
Discrete Event Simulation (DES) has been used as a
design and validation tool in various production and business applications.
DES can also be utilized for analyzing the product-mix for production planning
and scheduling. Product-mix decisions using analytical methods such as Linear
Programming (LP) are usually made so that the market demand is met and the
firm profit is maximized. However, the complexity and stochastic and dynamic
nature of real-world production and business systems may lead to production
levels that are different from those determined by analytical methods. Also,
coping with the dynamic changes in the product-mix usually requires enhancing
system parameters and/or process configuration. Therefore, its in some cases
essential to conduct the product-mix analysis using a DES model that accounts
for the complexity and stochastic and dynamic behavior of real-world systems.
Utilizing DES to measure the system response to potential changes in
product-mix is necessary to arrive at a flexible system configuration that is
adaptable to dynamic changes in the product-mix. Therefore, the primary goals
of this paper are to highlight the importance of analyzing the product-mix
with DES, present a methodology for performing the analysis, and provide a
case study to clarify the methodology.
Language Based Simulation Models as Management Tools
for Assembly Lines
Thomas Schulze (University of Magdeburg), Marco
Schumann (Fraunhofer IFF) and Gordon D. Rehn (Deere & Company)
Abstract:
This paper demonstrates that despite the trend to Point
& Click environments, the traditional approach of using general-purpose
simulation languages is still eligible. The authors share their experiences
gained from building a complex simulation using the language SLXTM. On the
basis of examples from the projects, the efficient modeling features of the
SLX languages are highlighted.
The Human Simulation: Resolving Manning Issues
Onboard DD21
Clyde R. Wetteland, Jeff L. Miller, and Jonathan
French (Micro Analysis & Design), Kelly O'Brien (Northrop Grumman
Corporation) and Daniel J. Spooner (Lockheed Martin GES)
Abstract:
The limitations that human operators impose on task
execution are rarely integrated into simulations of complex systems, resulting
in considerable loss of outcome fidelity. A discrete-event simulation tool,
Micro Saint, was used to stochastically model the impact of human interactions
in a comprehensive model of the next generation US Navy destroyer, DD21, to
support the Blue contract competitor team. Mission essential tasks performed
by a 3-operator and a 4-operator configurations were modeled during a
demanding 2.5 hour land attack scenario. Estimates of utilization rate for the
two configurations revealed that two of the operators were tasked more
frequently during the 3-operator configuration compared to a 4-operator
configuration. Workload estimates showed that Operator 2 was working with
significantly increased workload for the smaller watchteam configuration. The
workload for Operator 2 dropped 36% when Operator 4 was added to the mission.
This over tasking likely contributed to the finding that the smaller
configuration could not respond to a call for fire in support of ground forces
before 179 seconds whereas the 4 operator team responded within 61 seconds.
The DD21 model suggests that the small watchteam configuration might not be
acceptable, particularly during missions lasting over several days.
Using Simulation to Evaluate Cargo Ship Design on the
LPD17 Program
Joseph C. Hugan (Forward Vision Services)
Abstract:
As part of the design of the next generation Naval
Amphibious Transport Dock Ship (LPD17), simulation was used to evaluate the
arrangement and flow of cargo on the ship and to integrate material flow
concepts with the overall design requirements (see Figure 1). The simulation
model evaluated specific cargo load out scenarios to determine if the proposed
material handling systems would satisfy specific mission criteria. The
simulation was developed in 3D using a common database of CAD geometry to not
only evaluate the throughput and utilization of proposed systems but also to
verify that those systems could operate within the confined spaces of cargo
ships. The model considered factors such as cargo type and arrangement,
forklift speed, turning radius, elevator size, and elevator speed. The
placement of cargo was driven from external files and a rule set was developed
to allow for the automatic generation of an unload sequence. This paper will
focus on the construction of the model, its data file flexibility, and the
results of the missions evaluated during the project. It will also discuss the
role 3D simulation played in validating this model and communicating specific
simulation results.
Simulation Based Design for a Shipyard
Manufacturing Process
D. J. Medeiros, Mark Traband, April Tribble,
and Rebekah Lepro (Penn State University) and Kenneth Fast and Daniel Williams
(Electric Boat Corporation)
Abstract:
Discrete event simulation can be used for virtual
prototyping of new manufacturing facilities. Models built for this purpose
must be easy to use, flexible, and provide a realistic graphical view of the
proposed system. The DESTINY project has developed models of plate processing
operations to assist shipyards in modernizing their plate fabrication lines.
Configuration information for a proposed line is collected via a Web
interface, which then launches a program to build and execute a simulation of
the system. Graphics images and statistical reports are then returned to the
user via the Web interface. The approach allows rapid analysis of technology
improvements and a visualization of proposed system operation.