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Articles 601 - 630 of 671

Full-Text Articles in Operations Research, Systems Engineering and Industrial Engineering

Investigating Sorbent Geometry Response Surfaces From Sorption Rate Data, H. Michael Harrison Mar 1998

Investigating Sorbent Geometry Response Surfaces From Sorption Rate Data, H. Michael Harrison

Theses and Dissertations

Sorption and desorption of hydrophobic organic compounds (HOCs) into soil particles occurs at Air Force contamination sites. Long-term desorption extends clean up time, costing billions. Accurately modeling desorption will reduce costs and improve clean up designs. State of the art models depict soil as uniform spherical particles which lose the effect of longer sorption path lengths. An alternate approach, the multiple sites in series (MSS) model, describes the sorption capacity of a mixture of soil particle sizes and shapes using a composite particle defined by a two parameter statistical distribution. When the MSS model uses a general radial geometry function …

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Generating Bomber Routes For The Delivery Of Gravity Weapons, Gregory J. Ehlers Mar 1998

Generating Bomber Routes For The Delivery Of Gravity Weapons, Gregory J. Ehlers

Theses and Dissertations

United States Strategic Command (USSTRATCOM) is updating the Arsenal Exchange Model (AEM) that it uses for allocating strategic weapons to targets. AEM does not model the range constraints on bomber routes. These routes are used to deliver gravity munitions. In order to include these constraints in the new method, the Weapons Allocation Model (WAM), a pool of routes that satisfy the range constraints needs to be created. The number of possible routes to consider is extremely large and it is not possible to enumerate them all. Therefore, the method to form the pool of routes needs to reduce the number …

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A Multithreaded Scheduler For A High-Speed Simulator, Gene Saghi, Kirk Reinholtz, Paul Savory Jan 1998

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

Department of Industrial and Management Systems Engineering: Faculty Publications

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

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An Analysis Of Early Software Reliability Improvement Techniques, John G. Leonard, Ric K. Nordgren Dec 1997

An Analysis Of Early Software Reliability Improvement Techniques, John G. Leonard, Ric K. Nordgren

Theses and Dissertations

This research explores early life cycle software reliability prediction models or techniques to predict the reliability of software prior to writing code, and a method for increasing or improving the reliability of software products early in the development life cycle. Five prediction models and two development techniques are examined. Each model is statically analyzed in terms of availability of data early in the life cycle, ease of data collection, and whether data is currently collected. One model and the two techniques satisfied those requirements and are further analyzed for their ability to predict or improve software reliability. While the researchers …

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Modeling And Comparison Of Wormhole Routed Mesh And Torus Networks, Ronald I. Greenberg, Lee Guan Oct 1997

Modeling And Comparison Of Wormhole Routed Mesh And Torus Networks, Ronald I. Greenberg, Lee Guan

Computer Science: Faculty Publications and Other Works

2D-mesh and torus networks have often been proposed as the interconnection pattern for parallel computers. In addition, wormhole routing has increasingly been advocated as a method of reducing latency. Most analysis of wormhole routed networks, however, has focused on the torus and the broader class of k-ary n-cubes to which it belongs. This paper presents a performance model for the wormhole routed mesh, and it compares the performance of the mesh and torus based on theoretical and empirical analyses.

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Foreign Military Sales Supply Support: Is There A Better Way?, Eric G. Ellmyer, Won Joon Jang Sep 1997

Foreign Military Sales Supply Support: Is There A Better Way?, Eric G. Ellmyer, Won Joon Jang

Theses and Dissertations

In today's world of declining defense budgets, there is an increasing need for South Korea to ensure they obtain the best dollar value when procuring defense articles. With the increasing financial situation, the purpose of this thesis is to research a surrogate third party firm and determine to what degree South Korea and other foreign military sales customers obtain the best value for their money for follow-on support item procurements. South Korea has participated in the Parts and Repair Ordering System program since its inception. However, South Korea has received little, if any, feedback regarding lead time and cost performance …

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A Comparison Of The Military's Organic Movement And Commercial Express Carriers, Travis E. Condon, Kirk A. Patterson Sep 1997

A Comparison Of The Military's Organic Movement And Commercial Express Carriers, Travis E. Condon, Kirk A. Patterson

Theses and Dissertations

The DoD has begun outsourcing airlift in order to expedite high priority cargo movement. However, are commercial express carriers more expedient in the cargo delivery than the Air Force organic transportation system? Although anecdotal evidence suggests commercial carriers are faster, little empirical research has been conducted on this subject. This study compares the military's organic transportation system with Federal Express in the delivery of high priority cargo to Spangdahlem Air Base, Germany. The Large Sample Test of Hypothesis was used to determine if there was a significant difference between the cargo transit times of the two. The mean delivery time …

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Applying Cross-Decking And Activity-Based Costing To Military Distribution Centers: A Proposed Framework, Jonathan P. Elliott, Dwight H. Hintz Jr. Sep 1997

Applying Cross-Decking And Activity-Based Costing To Military Distribution Centers: A Proposed Framework, Jonathan P. Elliott, Dwight H. Hintz Jr.

Theses and Dissertations

Current events and fiscal constraints have focused DoD planners' attention on reducing logistics costs and improving efficiency while maintaining effective combat operations support. Military leaders are seeking private industry best practices that may help the DoD achieve these goals. Two commercially successful business practices that may help the DoD achieve its goals are cross-docking and Activity-Based Costing (ABC). Cross-docking is a commercially proven approach to material distribution through a distribution center that can help reduce inventories, speed material flows, and cut related logistics activity costs. However, the DoD is faced with the challenge of costing current and potential logistics processes …

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An Improved Analytical Model For Wormhole Routed Networks With Application To Butterfly Fat-Trees, Ronald I. Greenberg, Lee Guan Aug 1997

An Improved Analytical Model For Wormhole Routed Networks With Application To Butterfly Fat-Trees, Ronald I. Greenberg, Lee Guan

Computer Science: Faculty Publications and Other Works

A performance model for wormhole routed interconnection networks is presented and applied to the butterfly fat-tree network. Experimental results agree very closely over a wide range of load rate. Novel aspects of the model, leading to accurate and simple performance predictions, include (1) use of multiple-server queues, and (2) a general method of correcting queuing results based on Poisson arrivals to apply to wormhole routing. These ideas can also be applied to other networks.

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A Value Function Approach To Information Operations Moe's: A Preliminary Study, Michael P. Doyle, Richard F. Deckro, Jack M. Kloeber Jr., Jack A. Jackson Jr., Center For Modeling, Simulation, And Analysis, Air Force Institute Of Technology Jul 1997

A Value Function Approach To Information Operations Moe's: A Preliminary Study, Michael P. Doyle, Richard F. Deckro, Jack M. Kloeber Jr., Jack A. Jackson Jr., Center For Modeling, Simulation, And Analysis, Air Force Institute Of Technology

AFIT Documents

A value focused thinking approach is applied to information operations. A preliminary value hierarchy for information operations is constructed by extracting the values of senior military leadership from existing doctrine. To identify these key values for information operations, applicable existing doctrine was reviewed and summarized. Additionally, hierarchical representations of the values represented within each reviewed doctrine are developed. A value hierarchy requires that supporting objectives be mutually exclusive and collectively exhaustive. Within this analysis, these requirements are enforced, in part, by developed definitions which serve as tests to maintain mutual exclusivity. An exhaustive set of supporting values is also guaranteed …

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An Object Oriented Simulation Of The C-17 Wingtip Vortices In The Airdrop Environment, Hans J. Petry Mar 1997

An Object Oriented Simulation Of The C-17 Wingtip Vortices In The Airdrop Environment, Hans J. Petry

Theses and Dissertations

This thesis effort focuses on the development of an object-oriented simulation of C-17 personnel airdrop operations and provides a tool for risk assessment of jumper and wingtip vortex interaction. Using the initial modeling efforts of the Wright Laboratory, this model expands those efforts to include random aircraft, wind and jumper movement within the simulation using MODSIM III as its language. Once the model was built, verified, and calibrated, it helped perform a preliminary analysis of jumper risk with varying element spacing and no crosswind. The results of the simulation provided 15 data points with which linear and logistic regression provided …

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System Comparison Procedures For Automatic Target Recognition Systems, Anne E. Catlin Mar 1997

System Comparison Procedures For Automatic Target Recognition Systems, Anne E. Catlin

Theses and Dissertations

Estimating the performance of an automatic target recognition (ATR) system in terms of probability of successful target identification involves extensive image collection and processing, which can be very time-consuming and expensive. We investigate the Wald sequential test for the difference in two proportions as a sample size-reducing alternative to ranking and selection and the classical method of comparing binomial confidence intervals. The test is modified for the multiple pairwise comparison of four systems, and is applied to actual data to compare different configurations of the Moving and Stationary Target Acquisition and Recognition (MSTAR) System.

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Optimizing Airborne Area Surveillance Asset Placement, Douglas E. Fuller Feb 1997

Optimizing Airborne Area Surveillance Asset Placement, Douglas E. Fuller

Theses and Dissertations

Currently there is no automated planning tool for the optimum positioning of USAF area surveillance assets for a theater level campaign. This research seeks to find the optimum or near optimum placement of the limited USAF airborne surveillance assets against a theater level target set. The problem of finding the optimum orbit points can be modeled as a classic maximal covering location problem (MCLP). Operational constraints on the placement of surveillance aircraft can be handled by preprocessing the potential orbit points to eliminate infeasible orbit points. Heavy emphasis is placed on preprocessing the data to reduce problem size and hence …

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An Aggregation Procedure For Simulating Manufacturing Flow Line Models, Paul Savory, Gerald Mackulak Jan 1997

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

Department of Industrial and Management Systems Engineering: Faculty Publications

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

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An Integrated Approach To Simulation And Activity-Based Costing For Evaluating Alternative Manufacturing Cell Designs, Robert Williams, Paul Savory, Rodney Rasmussen Jan 1997

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

Department of Industrial and Management Systems Engineering: Faculty Publications

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

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Selecting For Random Drug Testing At Union Pacific Railroad, Jennifer Meyer, Paul Savory Jan 1997

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

Department of Industrial and Management Systems Engineering: Faculty Publications

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

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Simulating Queue Scheduling Policies For A Spacecraft Simulator, Paul Savory, Gene Saghi Jan 1997

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

Department of Industrial and Management Systems Engineering: Faculty Publications

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

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Modeling Space In The Air Force Command Exercise System (Aces), Robert Payne Jr. Mar 1996

Modeling Space In The Air Force Command Exercise System (Aces), Robert Payne Jr.

Theses and Dissertations

In response to the increased influence of space forces on today's battlefield, several theater level models were analyzed for the presentation of space forces. These models were the Extended Air Defense Simulation (EADSIM), the Joint Theater Level Simulation (JTLS), the Integrated Theater Engagement Model (ITEM), the Tactical Warfare Model (TACWAR), Thunder, Janus, and the Aggregate Level Simulation Protocol (ALSP). While ALSP is not a model but a simulation protocol connecting various models, it was studied because it appears to be the future of modeling. The consensus of the analysis was that space forces are virtually ignored by most of the …

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International Space Station Traffic Modeling And Simulation, Jillene B. Rylaarsdam Mar 1996

International Space Station Traffic Modeling And Simulation, Jillene B. Rylaarsdam

Theses and Dissertations

In an effort to provide NASA with an alternative perspective and some insights to the operational planning of the International Space Station (ISS), this research developed a simulation environment for the ISS and devised a method to evaluate various altitude strategies. The simulation environment allowed us to incorporate the natural random behaviors which affect the lifetime of objects in low earth orbit. We created prototype models of the operational planning process to analyze current altitude strategy approaches and acquire new strategies from insights observed. In addition, by extrapolating random future solar activity values from the interpolation of historical data, we …

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Cycle Time Estimation For Simulating A Tandem Queueing Systems Using Aggregation Techniques, Paul Savory, Gerald Mackulak Jan 1996

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

Department of Industrial and Management Systems Engineering: Faculty Publications

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

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A Methodology To Assess Post-Launch Efforts To Counter Mobile Tactical Ballistic Missile Launchers, Wayne H. Hayes Dec 1995

A Methodology To Assess Post-Launch Efforts To Counter Mobile Tactical Ballistic Missile Launchers, Wayne H. Hayes

Theses and Dissertations

The Department of Defense has a requirement to quantify the force enhancement effects from various configurations of an envisioned multilayered Theater Missile Defense (TMD) system. TMD research accomplished to date has focused primarily on the pre-launch and in-flight tactical ballistic missile (TBM) operational phases while ignoring the post-launch phase during which mobile transporter-erector-launchers (TELs) are vulnerable to attack. No methodology currently exists to measure the effectiveness of various post-launch counter-TEL system configurations or their potential contribution to the overall TMD mission. This research uses the decision analysis technique of influence diagrams to model the post-launch counter-TEL process using notional variable …

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Exmis: An Expert System For The Autonomous Onboard Command System (Aocs), Kevin D. Benedict Dec 1995

Exmis: An Expert System For The Autonomous Onboard Command System (Aocs), Kevin D. Benedict

Theses and Dissertations

The primary objective of this study is the creation of a prototype expert system called EXMIS (EXpert MIssile System) that performs the flight termination logic sequence of the Autonomous Onboard Command System (AOCS). The AOCS is a proposed system that would take the "man-in-the-loop" out of the self-destruct decision making process and place the entire decision on the launch vehicle. Through the use of a six degree of freedom trajectory program called BOOST, simulated flight data for four different flight scenarios is obtained. The launch vehicle selected for the simulations is the Peacekeeper ICBM. EXMIS is developed using an expert …

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Using Mathematica To Aid Simulation Analysis, Paul Savory Dec 1995

Using Mathematica To Aid Simulation Analysis, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

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

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An Evaluation Of Cost Metrics Used Within Aeronautical Systems Center, Kevin M. Byrne Sep 1995

An Evaluation Of Cost Metrics Used Within Aeronautical Systems Center, Kevin M. Byrne

Theses and Dissertations

Aeronautical Systems Center (ASC) system program offices rely on cost metrics to acquire information on program effectiveness and organizational improvement. This study was an attempt to determine the effectiveness of ASC’s cost metrics. The effectiveness of the metrics were determined by the desirability of the behaviors which are exhibited when individuals utilize the specific metrics. Using an expert panel to evaluate the metrics, data was collected using the Group Research Laboratory for Logistics located in Armstrong Laboratory at Wright Patterson AFB, OH. Metric diagnostic charts were utilized to arrange the data into a format which would provide effectiveness information. The …

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Aggregating Organizational Performance Metrics Using The Analytic Hierarchy Process, Bret L. Indermill Sep 1995

Aggregating Organizational Performance Metrics Using The Analytic Hierarchy Process, Bret L. Indermill

Theses and Dissertations

Measurement provides factual information which is necessary for effective control of business processes. Implementing a Total Quality Management (TQM) philosophy is a common process in many organizations today. The United States Air Force is using the Malcolm Baldrige National Quality Award criteria to measure organizational performance in implementing the Quality Air Force (QAF) initiative. Unfortunately, the Baldrige-based unit self-assessment (USA) process is an inconsistent measure due to its subjectivity, and is also time consuming to use. This study determined that a new USA method based on the analytic hierarchy process (AHP) was not a significant improvement over the existing QAF-USA …

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An Empirical Investigation Of The Integrated Weapon System Management Concept Of Seamless Processes, Timothy H. Surabian Sep 1995

An Empirical Investigation Of The Integrated Weapon System Management Concept Of Seamless Processes, Timothy H. Surabian

Theses and Dissertations

This research investigated the way four Air Force Materiel Command (AFMC) single manager organizations operationalized the Integrated Weapon System Management (IWSM) concept of "seamless processes." In this thesis, the IWSM concept of "seamless processes" refers to the degree of integration between acquisition and sustainment organizations. Four SPO organizations were involved in six case studies. This research focused on the way "seamless processes" affect the shifting of the organizational "center of gravity" within or between single manager organizations. An interview questionnaire was administered to 13 Product Center managers and 6 Logistics Center managers. The interview questions focused on IWSM in general, …

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A Model For Forecasting Pollution Prevention Life Cycle Costs For Air Force Major Weapon Systems, Mark E. Garner, Jennifer S. Kirchoffer Sep 1995

A Model For Forecasting Pollution Prevention Life Cycle Costs For Air Force Major Weapon Systems, Mark E. Garner, Jennifer S. Kirchoffer

Theses and Dissertations

This research effort developed a modification to the HAZMAT program so that the program could provide the user with the capability to generate an estimate during the concept exploration and design phases for the total costs associated with hazardous materials usage in a major weapon system. Using the HAZMAT database, a spreadsheet was developed which projects a cost for a weapon system based on its total surface area and the number of aircraft to be produced by performing an analogy with a similar weapon system. The modification uses algorithm which are based on the hazardous material substances rather than processes …

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Response Surface Methodology As A Sensitivity Tool In Decision Analysis, David A. Meyers Mar 1995

Response Surface Methodology As A Sensitivity Tool In Decision Analysis, David A. Meyers

Theses and Dissertations

The purpose of this study is to evaluate response surface methodology as a sensitivity analysis tool in the area of decision analysis. The advent of low-cost personal computer software, such as DPLTM, has created an accessible tool with the ability to frame and solve influence diagrams for decision problems. This study provides a comparison of current sensitivity analysis techniques vs those made possible through response surface methodology (RSM). Sensitivity analysis alternatives are demonstrated on a decision problem concerning the evaluation of force structure options for the Department of Defense. Sensitivity analysis is performed on both one-way and two-way perturbations of …

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Modeling Corps Artillery In A Theater Level Combat Model, Richard F. Bowyer Mar 1995

Modeling Corps Artillery In A Theater Level Combat Model, Richard F. Bowyer

Theses and Dissertations

This thesis describes the development of a methodology to explicitly model corps artillery assets in the Joint Staff's Joint Stochastic Analysis Research (J-STOCHWAR) and to quantify Army doctrine that guides organization of artillery for combat. The methodology incorporates corps artillery into the J-STOCHWAR by using the five fundamentals for organizing for combat, which reflect Army doctrine, and combines them with basic concepts already used in existing theater-level models. Other aspects of the problem include determining the appropriate level of detail, identifying techniques to solve the problem, and verifying the results. The proposed decision analysis solution technique provides a feasible method …

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Issues In Developing An Undergraduate Simulation Course, Paul Savory Jan 1995

Issues In Developing An Undergraduate Simulation Course, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

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

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