The Dynamics of Multinational Capital Structure
and Macroeconomic Conditions
Samuel Frimpong Boateng (Global
Investments and Corporate Solutions (UK) Limited)
Abstract:
Using a panel data methodology on a sample of 712
multinational corporations, we model capital structure changes in a non-linear
fashion and compare the speed of capital structure adjustment with that of
aggregate macroeconomic issues by using three types of leverage – short-term
debt, long-term debt, and total debt. It is determined, macroeconomic factors
are more useful in the adjustment process of capital structure than in
deciding explicit debt values. A relationship between the speed of capital
structure adjustment and the rate of aggregate macroeconomic changes is found.
By using a non-linear approach in conjunction with the Monte Carlo simulation
model we unravel and correct the shortcomings inherent in the conventional
approach to linear static capital structure investigations. The results
support the hypothesis that MNCs use more short-term debt in their capital
structure and draws some allusions from the behavioral pattern of managers in
reacting to short-run contemporaneous macroeconomic changes.
Forecasting the Term Structure of Natural Gas
Constant Maturity Futures Using a Seasonal Principal Components-based
Post-Weighted Monte Carlo Simulation.
Elias A. Demetriades
(ILIA-Chicago) and Deborah Cernauskas (Stuart Graduate School of Business)
Abstract:
Given the increasing demand for natural gas, a number
of industry participants have attempted to value their storage contracts. Such
valuation involves both a forecasting of forward prices, as well as an
optimization of spreads and/or options. Leading industry firms have utilized
Principal Component Analysis and simulation to develop future values for
forward contracts, using a covariance matrix of forward returns generated by
historical data. We developed an improved procedure for applying the evolution
of the historical covariance matrix. Our methodology involves the
determination of a set of weights and the ensuing application of those weights
on the results of Monte Carlo simulations under a variable-period switching of
the VCV matrices. Out-of-sample results significantly improved the
approximation of actual values of forwards and spreads. Furthermore, its
deviations from market prices varied considerably less than those resulting
from current techniques, allowing future users to calibrate their models to
the market easier.
Assesssing Uncertainty in Software Reliability via
quasi-Monte Carlo Methods
Hongmei Chi and Edward Jones (Florida
A&M University)
Abstract:
The need of conducting uncertainty analysis in software
reliability for the large and complexity system is demanding. The Monte Carlo
method is used for reliability prediction and assessing uncertainty in
software reliability. An important improvement of the convergence rate (and
thus of speed) can be achieved by using quasi-Monte Carlo methods. These are
variants of ordinary Monte Carlo methods, but use quasi-random (highly
uniform) sequences instead of pseudorandom sequences. This enhanced uniformity
leads to higher rates of convergence. Analysis of a simple problem in software
reliability showed that quasi-Monte Carlo methods achieve the same or better
parameter estimates as standard Monte Carlo, but have the potential to
converge faster and so reduce the computational burden. The paper will explore
the use of quasi-Monte Carlo methods to assessing uncertainty in software
Reliability.
Los Alamos Communication Network
Simulation
Stephan Eidenbenz (Los Alamos National Laboratory)
Abstract:
We present a scalable end-to-end approach to
communication network simulation. We show that realistic network simulation
requires realistic input generation of the communication network and
communication sessions in addition to scalable protocol stack simulation. We
present the main building blocks of our simulation system: network generation,
session generation, network simulation, and simulation analysis. Our system
relies on light-weight agents that represent a human population and their
communication behavior. We support the case for our holistic end-to-end
approach through a few example simulations and results from our large-scale
studies of communication networks.
Automatic Generation of Simulation Program by
XML-Prolog
Ryo Fukuhara, Tomoharu Matsunaka, and Kazutaka Kitamori
(Hokkaido Institute of Technology)
Abstract:
We have developed an intelligent simulation development
environment and intelligent search engine using "XML-Prolog" for as a
framework for efficient and stable simulation development. This development
environment has a cycle that consists of three elements (modeling,
programming, and result generation) which are managed as XML documents. To
illustrate the framework, a Monte Carlo simulation and sampling of resultant
distributions are performed by logically merging knowledge concerning Monte
Carlo methods and sampling techniques retrieved by intellectual means.
Knowledge of how programs communicate is added the already merged knowledge
and the XML documents are generated. The programming process comprises of
simulation conditions and initial values programs which are generated by XML
documents. In this paper, we describe automatically generating programs for
Monte Carlo simulation with LPWS (Legendre polynomial weighted sampling) using
XML-Prolog.
Experiences From the Annual 24-hour Software
Engineering Competition at Univeristy of Skövde - How to use Simulation for
Detecting Good Software Engineers
Per M. Gustavsson and Anna
Persson (University of Skövde) and Tomas Planstedt, Christoffer Brax, and
Madeleine Norstedt Larsson (Ericsson)
Abstract:
In the presentation the five-year experiences from the
yearly 24 hours software engineering competition held at University of Skövde
is presented. The outline for the competition is briefed and architectural and
design issues are in focus. The competition is divided into two phases where
the first is to develop the software the second is too compete with it towards
each other in a distributed simulation. The systems that the students build
are C2 systems for, air traffic control, ambulance control, focused logistic.
Presented and elaborated together with the solutions. The work has evolved new
ideas in how simulation can be used to enhance the planning, learning and
combining game-engines architectures with military simulation architectures.
HLA versus CORBA versus OpenSIS as interoperability distribution mechanisms
are discussed.The application (Scenarios) is presented as well as the
presentation techniques in 2D and 3D to visualize the competition within the
competition for the audience.
Telerobotic Systems for Restoration Work in
Structured Hazardous Environments
Jimmy Huff and Silvanus J. Udoka
(North Carolina A & T State University)
Abstract:
A hazardous human environment is one in which harm
could potentially occur to any human or animal that enters into it. There is a
need for autonomous and/or semi-autonomous systems to replace humans on such
dangerous jobs. The operational reliability of the robot in the hazardous
environment is critical. This paper will address possible improvements in
mission success when variable controlled task programming is applied to task
planning in concert with virtual simulation. This is achieved through the use
of a telerobot in a structured environment to mimic its recreated structured
virtual environment. By programming more of the operators’ knowledge of the
task into the operational aspects of the robot, the robot is better able to
complete a task when and if contact is lost with its operator due to
environmental conditions and/or system malfunction.
Parallel VHDL Simulation
David
Kunzman, Terry L. Wilmarth, and Laxmikant V. Kale (University of Illinois)
Abstract:
VHDL simulation is a common tool for verifying a
circuit design. The complexity of modern computer components is growing at a
substantial rate. Consider modern processors and GPUs which contain 100 to 300
million transistors. In a variety of consumer markets ranging from scientific
computing to business servers to PC gaming, substantial effort is being made
to maximize performance while also trying to decrease the time to market to
stay competitive. This presents a problem for sequential VHDL simulators. In
this poster, we plan to present the preliminary results of a parallel VHDL
simulator based on the POSE discrete event simulation framework. By using
POSE, the simulator is able to utilize various features of the portable and
adaptive Charm++ runtime system. Parallel simulation will reduce the time to
verify new designs. Additionally, it will allow larger, more complex designs
to be simulated than would be possible with current sequential simulators.
Numerical Calculation of Electric Fields with
Charge Densities Expressed Using Spline Functions
Yohei Miyazaki,
Keiko Yukawa, and Kazutaka Kitamori (Hokkaido Institute of Technology)
Abstract:
In the simulation of plasma processes, minimizing the
error associated with the electric field calculation in the vicinity of the
sheath is an important consideration. The sheath length scale when compared to
the plasma size and fact that the electric fields must be solved for
self-consistently with equations describing the plasma chemistry make the
electric field solution particularly expensive. We describe an electric field
simulation with high speed and good accuracy enabled by the description of the
density of charged by spline functions. In our method, Legendre Polynomial
Weighted Sampling (LPWS) is used to determine charged particle density and
velocity distributions. The LPWS method has been developed for Monte Carlo
simulations as a means of obtaining more detailed distributions from smaller
(or coarser) sample sizes. The coefficient of the spline function is obtained
directly from LPWS rather than through macroparameters extracted from the
distributions.
Simulation-Optimization for Transportation
in a Unified Automated Material Handling Systems
Jairo Rafael
Montoya Torres (Ecole des Mines de Saint-Etienne / STMicroelectronics),
Stéphane Dauzere-Peres (Ecole des Mines de Saint-Etienne - CMP Georges
Charpak), Hélčne Marian (Ecole des Mines de Saint-Etienne - Centre G2I) and
Leon Vermarien (STMicroelectronics)
Abstract:
This paper focuses on the analysis of transport
strategies in Automated Material Handling Systems (AMHS) for the semiconductor
industry. A difference against previous work is that our approach takes into
account the unified nature of inter-bay and intra-bay load transport
operations. In a unified AMHS, vehicles can travel along the whole network
path to deliver loads directly from one machine to another without passing by
intermediate storage. In order to optimally satisfy transport requests during
the production horizon, intelligent strategies have to be implemented. The
problem is addressed by means of a hybrid simulation-optimization approach. A
detailed simulation model of the semiconductor factory is built in order to
analyze factory dynamics. Mathematical programming is used to determine the
optimal value of the parameters of the simulation model. The detailed
simulation model carried out for this research work showed some interesting
and unpredictable evidences.
Optimization of Airport Taxiways Using Fast Time
Simulation
John Podlena and Keith Joshi (Preston Aviation Solutions
Pty. Ltd.)
Abstract:
With an increasing demand for throughput experienced by
many large airports, airport authorities are frequently looking at ground
infrastructure changes to increase both airport capacity and safety while
reducing delays. One such infrastructure change involves the building of new
aircraft taxiways to alleviate existing or possible bottlenecks, or to open up
new paths for taxiing aircraft to ground destinations such as runways and
terminal gates. With a commonly limited budget for such infrastructure
changes, simulation provides a vital tool for the investigation of the
location of such taxiways on an airport layout and the resulting efficiency
gains to be expected. This paper details a proposed system for the automated
optimization of taxiway placement using a fast time simulator (the Total
Airspace and Airport Modeler).
Methodology for Hospital Evacuation
Planning
Desiree Steinmann, Matthew Johnson, Kevin M. Taaffe, and
Lindsay Becker (Clemson University)
Abstract:
Frequently, a hospital assumes the role of triage
center or sheltering facility when the surrounding community faces a natural
disaster or man-made threat. We consider the implications on the hospital
patients, staff, and general population when the hospital itself requires
evacuation. Using data from recent hospital evacuations due to hurricanes in
Florida and South Carolina, we use analytical tools including simulation
analysis, agent-based modeling, and decision analysis to evaluate and
formulate sample hurricane evacuation plans. The interaction of several
organizations, ongoing health care activities, uncertainties in plan
implementation, and severity of the disaster will all contribute to this
problem’s complexity. We devise a methodology for evacuation planning that
allows the facility risk and safety managers a more accurate assessment of
their individual plans. This research also generates insights into evacuation
procedures for other threats, for which there may be far less time to prepare
a planned response.
Importance Sampling with Skew-Normal
Distributions
Tim Swartz (Simon Fraser University)
Abstract:
This presentation considers integral approximation via
importance sampling where the importance sampler is chosen from the family of
skew-normal distributions. This is a wider class of distributions than is
typically considered in importance sampling applications. We describe variate
generation and propose adaptive methods for fitting a member of the
skew-normal family to a particular integral.
How to Leverage Computer Simulation in
Condition-Based Maintenance
Ernest Yat-Kwan Wong (United States
Military Academy)
Abstract:
Computer simulation creates not only the potential to
improve many functions within the U.S. Army aviation’s condition-based
maintenance paradigm, but it also holds the capability to help enhance the CBM
vision of achieving optimal operational readiness of the fleet. Therefore,
instead of focusing on answering whether computer simulation modeling can be
used to enhance CBM, it is perhaps more worthwhile to focus on how to best
introduce computer simulation modeling into the CBM process in the most
effective manner. This paper presents three alternatives for addressing how to
introduce computer simulation techniques into CBM: a) develop computer
simulation tools in-house that are tailored specifically to U.S. Army Aviation
and Missile Command engineering requirements; b) use existing commercial
simulation software tools, such as Crystal Ball and Palisades Decision Tools,
for analysis of existing data; and c) outsource the modeling functions to
external agencies that have demonstrated expertise in computer simulation.
The Computational Complexity of Component
Selection in Simulation Reuse
Robert G. Bartholet, David C. Brogan,
Paul F. Reynolds, and Jr. (University of Virginia)
Abstract:
Simulation composability has been much more difficult
to realize than some initially imagined. We believe that success lies in
explicit considerations for the adaptability of components. In this paper we
show that the complexity of optimal component selection for adaptable
components is NP-complete. However, our approach allows for the efficient
adaptation of components to construct a complex simulation in the most
flexible manner while allowing the greatest opportunity to meet all
requirements, all the while reducing time and costs. We demonstrate that
complexity can vary from polynomial, to NP, and even to exponential as a
function of seemingly simple decisions made about the nature of dependencies
among components. We generalize these results to show that regardless of the
types or reasons for dependencies in component selection, just their mere
existence makes this problem very difficult to solve optimally.
Teaming Discrete-event Simulation and Geographic
Information Systems to Solve a Temporal/Spatial Business
Problem
Richard G. Born (Northern Illinois University)
Abstract:
Although discrete-event simulation has pedagogically
been rooted in computer science, and the practicality of geographic
information systems in geography, the combined use of both in the business
world allows solving some very challenging temporal/spatial (time and space
dependent) business problems. The discrete-event simulation language WebGPSS,
an ideal simulation environment for the business person, is teamed with
Microsoft MapPoint, a GIS (geographic information system) designed to bring
powerful mapping and analysis techniques to corporate office desktops. The
result is the ability to solve innovative business strategy problems before
implementing them in the real world. This paper focuses on one such problem by
using WebGPSS to drive a simulation that provides geographic data for display
by MapPoint, and ultimately map animations showing spatial and temporal
business changes.
Simulation-specific Characteristics and Software
Reuse
Joseph C. Carnahan, Paul F. Reynolds, Jr., and David C.
Brogan (University of Virginia)
Abstract:
We argue that simulations possess interesting
characteristics that facilitate adaptation. Simplifying assumptions,
stochastic sampling, and event generation are common features which lend
themselves to adaptation for reuse. In this paper, we explore
simulation-specific characteristics amenable to adaptation and the ways they
can be exploited in support of reuse. Our work is of particular relevance to
research in component based simulations and dynamic data driven application
systems, where adaptability and reuse are essential.
Towards a Simulation and Visualization Portal to
Support Multi-Actor Decision Making in Mainports
Roy T.H. Chin,
Stijn-Pieter A. van Houten, and Alexander Verbraeck (Delft University of
Technology)
Abstract:
Decision makers in ports and airports are working in an
extremely complex environment. Decisions involve multiple actors, who all have
a different view on the system under investigation, and on the effectiveness
and desirability of possible outcomes of the decision making process.
Simulation and visualization are two core technologies to support these
complex decision making processes. One of the major challenges is to provide
the variety of involved actors with visualizations that fit their view on the
system. Two case studies showed that the visualizations should be able to
provide two views on decision making: a view on the system under investigation
and a view on the multi-actor decision making process itself. This paper
presents the re-quirements for a service-oriented and web-based simula-tion
and visualization portal, which integrates both views. In cooperation with the
Port of Rotterdam we are currently developing and testing a prototype
implementation of the portal.
Retrieving Process Analysis in a Parts Distribution
Center: A Case Study of Manual Trolley Fleet Substitution
Shih Y.
Chin, Heráclito L. J. Pontes, and Arthur J. V. Porto (University of Săo Paulo
)
Abstract:
This paper summarizes the results of a simulation study
for a Parts Distribution Center (PDC), which contains approximately 30000
items, modeling its retrieving process in simulation software ARENA® 5.0. The
collection of the parts is carried out manually by five employees, being
sup-ported by manual trolleys. The current problem of PDC is to decide if that
manual trolley fleet should be substituted, since the existent ones are
unbalanced in comparison with the same market competitors, considering the
retrieving process total time effectiveness. The Input data to the model about
the fleet is the decision factor. Those data are statistically organized in
two levels, according to the de-sign of experiments 2k and the results of each
test are ob-tained from two replications. With these results, managers will be
able to evaluate possibilities, compare to the current situation and conclude
how viable it is to change the fleet.
FreeSML: Delivering on the Open-source Simulation
Language Promise
John J. DiLeo (The George Washington University)
Abstract:
FreeSML is a Java-based simulation language, providing
support for process-oriented and event-oriented simulation, along with limited
support for continuous-variable simula-tion. The core simulation engine is
indirectly derived from that of Silk 1.3, and the language’s public interface
is based heavily on those of Silk and SSJ. Unlike earlier languages, FreeSML
was developed with the specific intent that it be released as an open-source
package, and has been released under the Free Software Foundation’s Lesser
General Public License (LGPL).
Recognition of Continuous Probability
Models
Marcelo Tenório, Silvia Nassar, and Paulo José Freitas
(Federal University of Santa Catarina) and Carlos Magno Jacinto (Petrobras)
Abstract:
It is well known that randomness is present in daily
life and that often it is desirable to recognize inherent characteris-tics of
this randomness. Probability theory describes a quantification of the
uncertainty associated with this ran-domness. Based on probability theory, the
present research describes an alternative methodology to the traditional
sta-tistical method of the recognition of the probabilistic mod-els that best
represent randomness. The main motivation of the methodology is to keep the
largest possible amount of information present in the data. This methodology
dif-fers from the traditional statistical method, mainly in as-pects related
to the division of the data into classes when the data are continuous.
The Road Towards Multi-Hypothesis Intention
Simulation Agents Architecture - Fractal Information Fusion
Modeling
Per M. Gustavsson (University of Skövde) and Tomas
Planstedt (Ericsson)
Abstract:
This paper presents the road towards Multi-Hypothesis
Intention Simulation Agents Architecture and specific the Fractal Information
Fusion model (FIF) that are formed to support a systems-thinking in an agent
architecture that aligns with the Global information Grid, NATO Net Enabled
Capabilities and Swedish Armed Force Enterprise Architecture initiatives. The
Joint Direc-tors of Laboratories information fusion model and the Observe,
Orient, Decide, Act loop by John Boyd is combined and used as the foundation
together with the Knowledge Model, Level of Conceptual Interoperability and
Previous, Present, Predict Information Fusion Model shaping the FIF-model. The
FIF-model’s effect in shaping of the Multi-Hypothesis Intention Simulation
Agents Architecture is presented.
Two New Subjective Validation Methods Using Data
Displays
Husam Hamad and Sami Al-Hamdan (Yarmouk University)
Abstract:
Three graphical data displays of histograms, box plots,
and behavior plots are used in existing literature for subjective model
validation. In this paper, we present two additional plots that can be used
for displaying graphs of data; these are the so-called circle plots and
ordinal plots. These plots are easy to generate using model data and system
data. Like the existing plot types, no statistical assumptions are made on the
data that are represented. However, more ex-peditious subjective
interpretations about model opera-tional validity are made using the methods
presented.
A Distributed Multi-Formalism Simulation to
Support Rail Infrastructure Control Design
Elisangela Mieko
Kanacilo and Alexander Verbraeck (Delft University of Technology)
Abstract:
In this study we use simulation as a method of inquiry
to support rail infrastructure control designers in making more effective
decisions during the design process. Limitations encountered in commercial
simulation tools when modeling rail system elements, are related to the choice
of just one formalism (discrete or continuous) to model the element behavior.
When supporting the design of rail system control, rail controllers and rail
control designers might be in different locations. Therefore distribution of
the simulation model is a required feature which is usually not possible in
current simulation environments. In order to more accurately represent rail
systems behavior and improve the effectiveness of control design, we propose a
simulation library where different formalisms can be integrated in one single
model and where simulation components are accessible by users in different
locations.
Study on Simulation Credibility Metrics
Fei
Liu, Ming Yang, and Zicai Wang (Harbin Institute of Technology)
Abstract:
Currently, there appears to be an over-preoccupation
with building simulation validity in simulation credibility evaluation.
However, today's simulation systems become more complex and larger, the only
validity metric can't represent simulation credibility, and there is a need
for other credibility metrics. Therefore, we should rethink the basic problem
in the simulation community: what are the metrics of simulation credibility.
In this paper, credibility metrics are deeply investigated and presented,
measurement methods for credibility metrics are discussed, a new approach to
synthesis of credibility metrics is presented, and a credibility metrics
driven VV&A process is discussed.
Does More Uniformly Distributed Sampling Generally
Lead to More Accurate Prediction in Computer Experiments?
Longjun
Liu (Gunderson Inc.) and Wayne Wakeland (Portland State University)
Abstract:
Sampling uniformity is one of the central issues for
com-puter experiments or metamodeling. Is it generally true that more
uniformly distributed sampling leads to more accu-rate prediction? A study was
conducted to compare four designs for computer experiments, based on
simulation tests and statistical analysis. Maximin Latin hypercube de-sign
(LHMm) nearly always generated more uniform sam-pling in two- and three-
dimensional cases than does ran-dom sampling (Rd), Latin hypercube design
(LHD), or Minimized centered L2 discrepancy Latin hypercube de-sign (LHCL2).
But often there was no significant differ-ence among the means of the
prediction errors by employ-ing LHMm versus the other designs. Occasionally,
even the opposite was seen. More uniform sampling did not generally lead to
more accurate prediction unless sampling included extremely nonuniform cases,
especially when the sample size was relatively small.
Optimized Concrete Delivery Scheduling Using Combined
Simulation and Genetic Algorithms
Ming Lu and Hoi-Ching Lam (Hong
Kong Polytechnic University)
Abstract:
The research presented is mainly focused on how to
simultaneously optimize concrete delivery scheduling and resource provisions
for ready mixed concrete (RMC) plants based on a valid simulation modeling
platform resulting from research, called HKCONSIM. Combined discrete-event
simulation and genetic algorithms (GA) are applied in HKCONSIM to model and
further optimize the one-plant-multisite RMC plant operations in Hong Kong.
Logistics planning practices of RMC businesses in Hong Kong are introduced,
and interfaces, features and functionalities of HKCONSIM described. The
potential industry impact of the research effort is demonstrated with a case
study based on one-day operations data obtained from a Hong Kong RMC plant. It
is concluded that the GA-integrated simulation platforms specifically designed
for RMC companies such as HKCONSIM will potentially assist managers in making
optimal decisions on concrete production and delivery scheduling, thus
enhancing productivity, resource utilization and concrete supply service in
day-by-day operations.
Railroad Infrastructure
Simulator
Marcelo Moretti Fioroni and Luiz Augusto G. Franzese
(Paragon Consulting Solutions) and Naguisa Yuri Hiramatsu Pereira and Marcelo
Neder Pereira (MRS Logistica S.A.)
Abstract:
The railroad is one of the best options for long
distance and high volume transportation. Many studies have been de-veloped to
determine the best way to use the available in-frastructure (tracks,
locomotives, etc.) or the best proce-dures to block trains or schedule its
departures. This study presents an experience made with a reusable simulation
tool specially designed to evaluate the impact of infrastruc-ture changes on
rail lines or load / unload terminals. Some aspects of this simulation tool
are presented, and an ex-periment made with a real rail network is described
Simulation-Based Scheduling for Photo-Reconnaissance
Satellite
Qiming Ruan, Yuejin Tan, Renjie He, and Yingwu Chen
(National University of Defense Technology)
Abstract:
A simulation-based scheduling mechanism for
photo-reconnaissance satellite is presented in this paper. The satellite
scheduling problem belongs to a class of single-machine scheduling problems
with time window constraint. It is NP-hard in computational complexity. Based
on simulation platform, a mixed integer programming model is used to formulate
the problem and an advanced tabu algorithm is adopted to solve the MIP.
Numerical results demonstrate that this approach is efficient in the
scheduling problems.
Agent-Based Simulation of Enterprise Communication
Network
Hideyuki Mizuta and Fusashi Nakamura (IBM Japan)
Abstract:
In this paper, we consider an agent-based simulation of
dynamic enterprise organization and communication networks. Along with recent
progress and popularization of Information Technology, social sciences have
been experiencing great advances in survey methodology. It has become possible
for researchers to utilize huge social data with computers. However, there
have been only conceptual studies in business school and few quantitative
studies about enterprise organizations. In a survey of an enterprise, we
evaluated strategic organization changes with graph/network analysis of the
communication network constructed from email transaction data. Moreover, there
is strong business needs to know how activities change according to an
organization transformation. Utilizing the agent-based approach, we have
constructed a dynamic model and simulation of communication over an
organization structure. The result of the simulation indicates the power
distribution for link degrees which is also observed in the real world as
universal characteristics of the scale-free network.
DSS to Manage ATM Cash Under Periodic Review with
Emergency Orders
Ana K. Miranda and David F. Muńoz (Instituto
Tecnológico Autónomo de México)
Abstract:
The cash management of an automated teller machine
(ATM) often combines a periodic review inventory policy with emergency orders,
the latter according to a continuous review inventory policy. We present a
simulation-based decision support system (DSS) that considers both regular
(periodic) and emergency (continuous review) orders. This DSS was developed to
assist an ATM’s manager in the se-lection of the appropriate (regular) order
and period sizes as well as the (emergency) reorder point under a given
ser-vice level. The DSS was developed using the software Arena and integrates
a Visual Basic for Applications (VBA) front-end that allows the user to
incorporate fixed and variable ordering costs as well as demand and arrival
rates updates.
Feature-Based Generators for Time Series
Data
Jorge R. Ramos and Vernon Rego (Purdue University)
Abstract:
A variety of interesting domains, such as financial
markets, weather systems, herding phenomena, etc., are characterized by highly
complex time series datasets which defy simple description and prediction. The
generation of input data for simulators operating in these domains is
challenging because process description usually involves high-dimensional
joint distributions that are either too complex or simply unavailable. In such
applications, a standard approach is to drive simulators with (historical)
trace-data, along with facilities for real-time interaction and
synchronization. But, limited input data, or conversely, abundant but
low-fidelity random data, limits the usefulness and quality of the results.
With a view to generating high-fidelity, random input for such applications,
we propose a methodology which uses the original data, as a template, to
generate candidate datasets, to finally accept only those datasets which
resemble the template, based upon parameterized features. We demonstrate the
methodology with some early experimental results.
Reducing Lead Time for Modeling in CAD Simulation
Softwares
Jai Thomas, Mitchel J. Keil, and Jorge Rodriguez (Western
Michigan University)
Abstract:
Flexible components, such as rubber hoses, are subject
to large elastic deformations during movement of the rigid components to which
they are attached. Currently, there is no inherent capability in any solid
modeling software to accurately depict the shape of the hose between any two
attachment points.Keil (2001) made the hose model in ADAMS/View simulation
software. Keil (2002) stated that it is a very time consuming and cumbersome
process to set up the model with the flexible beams and its associated joints
for modeling of a flexible body without any user errors.This paper presents a
method to automatically build a flexible element model using the principles of
spatial orientation and vector mathematics. These accurate mathematical
principles would maintain the precision in the flexible element model as
suggested by Keil while reducing the time for building a hose model to minutes
from hours.
Learning Simulation Through Team
Projects
Omer Tsimhoni and Changxu Wu (University of Michigan)
Abstract:
For several years, team projects have been an integral
part of the simulation course at the department of Industrial and Operations
Engineering at the University of Michigan. We believe that team projects are
an effective tool for learning how to perform simulation. In this paper, we
present a brief summary of research on cooperative learning from the field of
Education Research. Based on findings from that research, we present the
procedure we follow in assigning, running, and evaluating team projects during
an academic semester. We analyze students‘ responses to a survey on their
preference and perceived value of the team project as conducted in this
course. Two student papers, published in this conference, provide for examples
of completed team projects.
A Conceptual Model for the Creation of Supply Chain
Simulation Models
Guilherme E Vieira and Osmar César Junior
(Pontifical Catholic University of Parana)
Abstract:
This paper presents the development of conceptual
models that can be used in the creation of certain types of supply chain
simulation projects. The supply chain considered is composed of four elements:
suppliers, manufacturer, retail-ers, and the consumer market. The presented
ideas can be used in supply chain simulation projects, which objective can be,
for instance, to study the bullwhip effect or new collaboration practices.
ARENA simulation models using the conceptual models presented are currently
under development.
Reducing Service Time at a Busy Fast Food Restaurant
on Campus
Sara A. Curin, Jeremy S. Vosko, Eric W. Chan, and Omer
Tsimhoni (The University of Michigan)
Abstract:
As part of an undergraduate engineering class project,
a Tim Hortons restaurant on the University of Michigan campus was simulated to
improve its efficiency. Using the standard simulation study steps, several
service scenarios were modeled and evaluated based on customer system time. A
detailed analysis of the simulation revealed that, in the current setup, the
utilization of the cash registers is high (88%); consequently, several
scenarios that decrease the load on the cash registers were explored. To
reduce customer wait times and, therefore, serve more customers per hour, it
is recommended that Tim Hortons operate with five servers. A five-person setup
with three cashiers, a soup server, and a sandwich server could reduce
customer system time by over two minutes per customer. As an alternative,
transferring all food preparation to the secondary service location and adding
a dual-purpose server could reduce customer system time by over one half.
Comparing Skill-Based Routing Call Center
Simulations Using C Programming and Arena Models
Rodney B. Wallace
(IBM) and Robert M. Saltzman (San Francisco State University)
Abstract:
This paper describes the modeling of a skill-based
routing call center using two distinct simulation programming methods: the C
language and the Arena software package. After reviewing the features of this
type of call center, we describe the salient components of each method in
modeling the call center. The paper concludes with a comparison of the pros
and cons of using each simulation programming approach in this context.
Calibration of VISSIM for Shanghai Expressway Using
Genetic Algorithm
Wu Zhizhou, Sun Jian, and Yang Xiaoguang (Tongji
University)
Abstract:
This paper presents how an optimal optimization method,
Genetic Algorithm (GA), is applied for finding a suitable combination of
VISSIM parameters. The North-South (N-S) Expressway is investigated and
simulated in VISSIM platform using field data obtained from Traffic
Information Collecting System (TICS) in Shanghai. Numerous simulation tests
indicate that the following main parameters have affected simulation precision
most deeply, such as Desired Speed in Reduced Speed Area (DSRSA), Desired
Lane-Change Distance (DLCD), and Wiedemann99 car-following parameters, the
average desired distance between stopped cars (CC0), the headway time (in
second) that a driver wants to keep at a certain speed (CC1), and safety
distance a driver allows before he intentionally moves closer to the car in
front (CC2). The prepositional parameter combination of DSRSA, DLCD, CC0, CC1
and CC2 is 40,500, 1.5, 0.8 and 3.50 for peak time traffic.
Sharing Event Data in Optimistically Scheduled
Multicast Applications
Garrett Robert Yaun, David Bauerd, and
Christopher D. Carothers (Rensselaer Polytechnic Institute)
Abstract:
A major consideration when designing high performance
simulation models is state size. Keeping the model state sizes small enhances
performance by using less memory, thereby increasing cache utilization and
reducing model execution time. The only remaining area for reducing model size
is within the events they create. The event population is typically the most
memory intensive region within a simulation especially in the case of
multi/broadcast like applications which tend to schedule many events within
the atomic processing of a single event. This paper introduces the idea of
shared event data within an optimistic simulation system. Here, the
read-only data section is shared for a multicast event, which may then be
delivered to several LPs. From our performance study, we report a 22%
reduction in the data cache miss rate, a processor utilization in excess of
80% and a reduction in model memory consumption by a factor of 20.
Simulation Based Decision for Steelmaking
Operations Challenges
Marcelo Moretti Fioroni and Luiz Augusto G.
Franzese (Paragon Consulting Solutions) and Edson Luiz Harano, Juliana Souza
Lima, Joăo Bosco Mendes, Joeli Cuzzuol, Ricardo Baeta Santos, Robson Jacinto
Coelho, Benedito Pedro Costhek, and Adriano César Silva (Companhia Siderúrgica
de Tubarăo)
Abstract:
Companhia Siderúrgica de Tubarăo CST, is investing to
expand production level in 50%, adding new equipment and altering production
process. Simulation is widely used in CST, mainly in strategic phases prior to
capital invest-ment. A previous simulation model developed with ARENA was
enhanced to help CST achieve new goals: to analyze new process plan with
operational details, testing different production and operational scenarios,
evaluating new procedures and best practices. Two case studies are presented
here to show how CST uses this technology: the expansion of an steelmaking
plant and the expansion of the raw material handling conveyor system
Simulation Modelling for Performance Measurement in
Healthcare
Murat M. Gunal and Michael Pidd (Lancaster University)
Abstract:
Discrete event simulation is widely used to model
health-care systems with a view to their improvement. Most ap-plications focus
on discrete aspects of health care, such as accident and emergency rooms or
outpatient clinics. How-ever, despite this success with simulation at an
operational level, there are no reported uses of discrete event simulation for
the development and improvement of health policy. We describe the development
of such a policy-oriented model, aimed at improving performance assessment in
the UK National Health Service.
System-Centric Mission-Critical Simulation Model
for Mes Automation
Amit Jindal and Rajkumar Khandelwal (Intel
Corporation)
Abstract:
This paper describes the System centric simulation
meth-odology used for stress testing of Manufacturing Execution System (MES)
in Intel. System centric simulation involves testing such that the system
components (infrastructure stack and software) are characterized for the load
they would experience in production, irrespective of how that load is exerted.
A new manufacturing execution system software is introduced in Intel’s latest
fabrication facility. Validation of the product under stress is vital to
ensuring the mission critical capability will be able to comply with Intel’s
reliability, availability, performance, and scalability needs. The System
centric simulation model allows for ac-curate reproduction of real-world
scenarios while not re-quiring the expensive setup and execution of the
complete set of defined use cases.
Emergency Department Simulations: Medicine for
Building Effective Models
Carley J. Jurishica (Rockwell Automation)
Abstract:
This paper will discuss proven practices for developing
Emergency Department (ED) simulations based on recent project success. From
human decisions to political agen-das, an ED is filled with unpredictable
elements, making it a difficult environment to model. However, the key
deci-sion-making information that will be uncovered from a study is worth the
effort. This paper will thoroughly ana-lyze each step of a typical ED
simulation project, identify-ing key areas of focus and tips for success.
Defining the objective, process map, scenarios, outputs and animation
requirements are the first steps. A system for gathering the ED data will be
discussed, as well as advice for the verifi-cation and validation phases.
Finally, the presentation of the findings will be analyzed. No part an ED
simulation project should be discounted. This paper will stress de-pendency of
each phase on the successful outcome of the entire project.
Modeling Emergency Departments Using Discrete
Event Simulation Techniques
Alexander Komashie and Ali Mousavi
(Brunel University)
Abstract:
This paper discusses the application of Discrete Event
Simulation (DES) for modeling the operations of an Emergency Department (ED).
The model was developed to help the ED managers understand the behavior of the
system with regard to the hidden causes of excessive waiting times. It served
as a tool for assessing the impact of major departmental resources on Key
Performance Indicators, and was also used as a cost effective method for
testing various what-if scenarios for possible system improvement. The study
greatly enhanced managers’ understanding of the system and how patient flow is
influenced by process changes and resource availability. The results of this
work also helped managers to either reverse or modify some proposed changes to
the system that were previously being considered. The results also show a
possible reduc-tion of more than 20% in patients’ waiting times.
Simulation Optimization Using Tabu Search: An
Emprical Study
Abdullah Konak and Sadan Kulturel-Konak (Penn State
Berks)
Abstract:
This paper proposes alternative strategies to perform
simulation within a simulation optimization algorithm based on tabu search.
These strategies are tested empirically on a stochastic knapsack problem.
Results have shown that the way simulation is implemented and the number of
simulation replications have a profound effect on the performance of tabu
search.
Extend SRML Schema Based on DEVS: An Executable DEVS
Language
Chen Liu, Qun Li, Weiping Wang, and Yifan Zhu (National
University of Defense Technology)
Abstract:
This paper analyzes the significance of the
representation and reusability of SRML when being used in simulation models as
well as its drawbacks. The paper also discusses the ways to extend SRML schema
based on DEVS. The emphasis is placed on the elaboration of mapping DEVS onto
SRML schema to formulate SRML’s basic syntax and semantics for the structure
and behavior representation of atomic model and coupled model. The model
structure, such as property, input interface, output interface and sub-model
composition, are described by a group of XML marks. The model behavior, such
as external transition, internal transition, output and time-advance functions
are described by script language and a group of standard interface offered by
SRML simulator in Script marks. The paper then reviews the SRML element
architecture and finally gives a simulation demo of using SRML to build
differential equation model.
P-tree Structures and Event Horizon:
Efficient Event-Set Implementations
Katerina Asdre and Stavros D.
Nikolopoulos (University of Ioannina)
Abstract:
This paper describes efficient data structures, namely
the IP-tree, BP-tree, and IBP-tree, for maintaining
future events in a general purpose discrete event simulation system, and
studies the performance of their event set algorithms under the event horizon
principle. For comparison reasons, some well-known event set algorithms were
also selected and studied; that is, the Dynamic-heap and the P-tree
algorithms. To gain insight into the performance of the proposed event set
algorithms and allow comparisons with the other selected algorithms, they are
tested under a wide variety of conditions in an experimental way. The time
needed for the execution of the Hold operation is taken as the measure for
estimating the average time complexity of the algorithms. The experimental
results show that the BP-tree algorithm and the IBP-tree
algorithm behave very well with all the sizes of the event set and their
performance is almost independent from the stochastic distributions.
Importance Sampling Techniques for Estimating The
Bit Error Rate In Digital Communication Systems
Wheyming Song and
Wechi Chiu (National Tsing Hua University) and David Goldsman (Georgia
Institute of Technology)
Abstract:
We are interested in estimating the bit error rate
(BER) for signal transmission in digital communication systems. Since BERs
tend to be extremely small, it is difficult to obtain precise estimators based
on the use of crude Monte Carlo simulation techniques. In this paper, we
review, expand upon, and evaluate a number of importance sampling variance
reduction techniques for estimating the BER. We find that mixtures of certain
``tailed'' distributions with a uniform distribution produce estimators that
are at least competitive with those in the literature. Our comparisons are
based on analytical calculations and lay the groundwork for the evaluation of
more-general mixture distributions.
