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Iowa State University

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Articles 271 - 291 of 291

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

Development Programs For One-Shot Systems Using Multiple-State Design Reliability Models, Suntichai Shevasuthisilp, Stephen B. Vardeman Jan 2004

Development Programs For One-Shot Systems Using Multiple-State Design Reliability Models, Suntichai Shevasuthisilp, Stephen B. Vardeman

Industrial and Manufacturing Systems Engineering Publications

Design reliability at the beginning of a product development program is typically low, and development costs can account for a large proportion of total product cost. We consider how to conduct development programs (series of tests and redesigns) for one-shot systems (which are destroyed at first use or during testing). In rough terms, our aim is to both achieve high final design reliability and spend as little of a fixed budget as possible on development. We employ multiple-state reliability models. Dynamic programming is used to identify a best test-and-redesign strategy and is shown to be presently computationally feasible for at ...


Determining Multi-Criteria Priorities In The Planning Of Electric Power Generation: The Development Of An Analytic Hierarchy Process For Using The Opinions Of Experts, Sung Chul Kim, Kyung J. Min Jan 2004

Determining Multi-Criteria Priorities In The Planning Of Electric Power Generation: The Development Of An Analytic Hierarchy Process For Using The Opinions Of Experts, Sung Chul Kim, Kyung J. Min

Industrial and Manufacturing Systems Engineering Publications

The electric power industry in the United States is undergoing substantial changes in power gene ration business as well as in environmental regulation. Under these changes, it is highly desirable for the electric power industry to objectively and quantitatively examine generation planning, which often involves a multiple number of different experts with multi-criteria for decision making. In this paper, we consider these two key aspects in generation planning (multi-experts/multi-criteria), and integrate an analytic hierarchy process for multi-criteria decision making and a Bayesian approach for combining experts' opinions. Our efforts lead to a comprehensive numerical example that illustrates multi-experts/multi-criteria ...


The Effect Of Technological Improvement On Capacity Expansion For Uncertain Exponential Demand With Lead Times, Dohyun Pak, Nattapol Pornsalnuwat, Sarah M. Ryan Jan 2004

The Effect Of Technological Improvement On Capacity Expansion For Uncertain Exponential Demand With Lead Times, Dohyun Pak, Nattapol Pornsalnuwat, Sarah M. Ryan

Industrial and Manufacturing Systems Engineering Publications

We formulate a model of capacity expansion that is relevant to a service provider for whom the cost of capacity shortages would be considerable but difficult to quantify exactly. Due to demand uncertainty and a lead time for adding capacity, not all shortages are avoidable. In addition, technological innovations will reduce the cost of adding capacity but may not be completely predictable. Analytical expressions for the infinite horizon expansion cost and shortages are optimized numerically. Sensitivity analyses allow us to determine the impact of technological change on the optimal timing and sizes of capacity expansions to account for economies of ...


The Engineering Learning Portal For Problem Solving: Experience In A Large Engineering Economy Class, Sarah M. Ryan, John K. Jackman, Frank E. Peters, Sigurdur Olafsson, Mary Huba Jan 2004

The Engineering Learning Portal For Problem Solving: Experience In A Large Engineering Economy Class, Sarah M. Ryan, John K. Jackman, Frank E. Peters, Sigurdur Olafsson, Mary Huba

Industrial and Manufacturing Systems Engineering Publications

In an effort to improve students' problem solving skills with information technology across the industrial engineering curriculum, we created an Internet based problem-solving environment. The module implemented for engineering economy presents a realistic problem that establishes connections with other courses. The design of the learning environment promotes metacognitive skill development by requiring students to explain each major problem solving action taken and to evaluate their own progress toward a solution. Experience in two successive semesters of a large introductory course indicates that information technology can be used effectively to create opportunities for students to collaboratively solve realistic engineering problems, thereby ...


An Active Learning Environment In An Integrated Industrial Engineering Curriculum, Frank Peters, John K. Jackman, Sarah M. Ryan, Sigurdur Olafsson Oct 2003

An Active Learning Environment In An Integrated Industrial Engineering Curriculum, Frank Peters, John K. Jackman, Sarah M. Ryan, Sigurdur Olafsson

Industrial and Manufacturing Systems Engineering Conference Proceedings and Posters

We are developing a new learning environment that supports a suite of interrelated modules based on real-world scenarios. The primary goals of the project are to integrate industrial engineering courses, improve students’ information technology skills, and enhance students’ problem solving skills. In particular, metacognitive abilities will be strengthened as students apply domain knowledge, data, methods and software tools while monitoring their own solution processes. This paper presents the design of two modules that have been developed.


Discrete Event Simulation Implemented In A Virtual Environment, Jason Kelsick, Lori Buhr, Cheryl Moller, Judy M. Vance Sep 2003

Discrete Event Simulation Implemented In A Virtual Environment, Jason Kelsick, Lori Buhr, Cheryl Moller, Judy M. Vance

Mechanical Engineering Publications

Virtual reality (VR) technology provides a human-computer interface that allows participants to interact naturally with digital objects which are represented as three-dimensional images that occupy positions in a three-dimensional world. Related to problems of engineering design and manufacturing, this new technology offers engineers the ability to work with computer models in a three-dimensional, immersive environment. This paper describes a virtual reality application where the results of a discrete event simulation of a manufacturing cell are integrated with a virtual model of the cell to produce a virtual environment. The program described in this paper, the VRFactory, combines results from a ...


Information Technology Based Active Learning: A Pilot Study For Engineering Economy, Sigurdur Olafsson, Mary Huba, John K. Jackman, Frank E. Peters, Sarah M. Ryan Jan 2003

Information Technology Based Active Learning: A Pilot Study For Engineering Economy, Sigurdur Olafsson, Mary Huba, John K. Jackman, Frank E. Peters, Sarah M. Ryan

Industrial and Manufacturing Systems Engineering Conference Proceedings and Posters

We have recently designed a learning environment to add practical problem solving, increased information technology content, and active learning to industrial engineering courses. In particular, we have successfully implemented and tested a computer-based module for an undergraduate engineering economy course. In this module, students are required to formulate the problem, devise a plan of action, and derive a final solution using the domain knowledge acquired in class. In addition to improving understanding of the course material, the module is also designed to improve more general cognitive skills and specifically to enhance the metacognitive ability of the participating students. A prototype ...


Total Wip And Wip Mix For A Conwip Controlled Job Shop, Sarah M. Ryan, F. Fred Choobineh Jan 2003

Total Wip And Wip Mix For A Conwip Controlled Job Shop, Sarah M. Ryan, F. Fred Choobineh

Industrial and Manufacturing Systems Engineering Publications

A planning procedure to set the constant level of Work-In-Process (WIP) for each product type in a job shop operated under CONWIP control is developed. We model the job shop as a single chain multiple class closed queuing network. Given a specified product mix and a total WIP, a nonlinear program bounds the throughput of the network and optimizes the WIP mix. We identify the minimum total WIP that is guaranteed to yield throughput near the maximum possible for the specified product mix and set individual WIP levels by multiplying the optimal WIP mix proportions by the minimum total WIP ...


Capacity Expansion With Lead Times And Autocorrelated Random Demand, Sarah M. Ryan Jan 2003

Capacity Expansion With Lead Times And Autocorrelated Random Demand, Sarah M. Ryan

Industrial and Manufacturing Systems Engineering Publications

The combination of uncertain demand and lead times for installing capacity creates the risk of shortage during the lead time, which may have serious consequences for a service provider. This paper analyzes a model of capacity expansion with autocorrelated random demand and a fixed lead time for adding capacity. To provide a specified level of service, a discrete time expansion timing policy uses a forecast error-adjusted minimum threshold level of excess capacity position to trigger an expansion. Under this timing policy, the expansion cost can be minimized by solving a deterministic dynamic program. We study the effects of demand characteristics ...


Capacity Expansion For A Loss System With Exponential Demand Growth, Alexander Simampo, Sarah M. Ryan Jan 2003

Capacity Expansion For A Loss System With Exponential Demand Growth, Alexander Simampo, Sarah M. Ryan

Industrial and Manufacturing Systems Engineering Publications

We study a loss system to forecast the demand for capacity based on the forecast demand for service and a specified service level. A little-used property of the Erlang loss formula allows the linear transformation of demand for service into demand for capacity. Next, given the forecast demand for capacity, we approximate a long-run optimal capacity expansion policy by optimizing over successively longer finite time horizons. Analytical formulas together with regression analysis show the significance of the number of potential customers, frequency and duration of their requests for service, and the specified service level on the demand for capacity. Numerical ...


A New Analytical Evaluation Model For Kanban Controlled Systems With Fork/Join Synchronization Stations, Heedong Kim, Sarah M. Ryan Jan 2002

A New Analytical Evaluation Model For Kanban Controlled Systems With Fork/Join Synchronization Stations, Heedong Kim, Sarah M. Ryan

Industrial and Manufacturing Systems Engineering Conference Proceedings and Posters

A nonlinear programming model is developed for analyzing the queuing model of a kanban controlled system with fork/join synchronization stations. The model finds the minimum number of kanbans for a given throughput requirement or the maximum throughput for a given number of kanbans, where servers have different exponential service times. Furthermore, it aids understanding of kanban systems.


The Impact Of Surface Errors On The Location And Orientation Of A Cylindrical Workpiece In A Fixture, Supapan Sangnui, Frank E. Peters May 2001

The Impact Of Surface Errors On The Location And Orientation Of A Cylindrical Workpiece In A Fixture, Supapan Sangnui, Frank E. Peters

Industrial and Manufacturing Systems Engineering Publications

Surface error at the contact region is one factor that contributes to the displacement of the workpiece in a fixture. This work employs the Newton-Raphson technique to develop a mathematical model that predicts the impact of surface errors on the location and orientation of a cylindrical workpiece. Model validation and measurement analysis were conducted to verify the proposed mathematical model. An experimental fixture and workpiece were developed to simulate the effect of surface errors on the placement of a workpiece. The study showed that the numerical model is reliable in predicting the behavior of the workpiece.


Form Error Estimation Using Spatial Statistics, Tai-Hung Yang, John K. Jackman Jan 2000

Form Error Estimation Using Spatial Statistics, Tai-Hung Yang, John K. Jackman

Industrial and Manufacturing Systems Engineering Publications

Form error estimation is an essential step in the assessment of product geometry created through one or more manufacturing processes. We present a new method using spatial statistics to estimate form error. Using large sets of uniform sample points measured from five common machined surfaces, we compare the form error estimates using individual points and fitted surfaces obtained through spatial statistical methods. The results show that spatial statistics can provide more accurate estimates of form error under certain conditions.


A Simplified Procedure For Estimating Labor-Hour Requirements Of Discrete Assemblies, Deepak Srinivas, Kyung J. Min Jan 2000

A Simplified Procedure For Estimating Labor-Hour Requirements Of Discrete Assemblies, Deepak Srinivas, Kyung J. Min

Industrial and Manufacturing Systems Engineering Publications

Estimating the labor-hour requirements of discrete assemblies is often critical to numerous manufacturers because of its usefulness in determining the production cycle time, the costs of products, the performance of employees, and the price quotes to customers. The traditional method does not necessarily provide a fast and realistic estimation because of the time and complexity necessary to develop and estimate pre-specified times and allowances. In this paper. we propose a new procedure that is simpler and/aster. First, we present the data requirements and the regression-based procedure to estimate the Labor-hour requirements. Next, we show how specific linear and nonlinear ...


Determining Inventory Levels In A Conwip Controlled Job Shop, Sarah M. Ryan, Bruno Baynat, F. Fred Choobineh Jan 2000

Determining Inventory Levels In A Conwip Controlled Job Shop, Sarah M. Ryan, Bruno Baynat, F. Fred Choobineh

Industrial and Manufacturing Systems Engineering Publications

We extend the concept of CONWIP control to a job shop setting, in which multiple products with distinct routings compete for the same set of resources. The problem is to determine the fixed overall WIP level and its allocation to product types (WIP mix) to meet a uniformly high customer service requirement for each product type. We formulate an optimization problem for an open queuing network model in which customer orders pull completed products from the system. Then, assuming heavy demand, we derive a throughput target for each product type in a closed queuing network and provide a simple heuristic ...


Dimensional Variability Of Aluminum Castings, W.C. Faustine, R.C. Voigt, Frank Peters Jan 1999

Dimensional Variability Of Aluminum Castings, W.C. Faustine, R.C. Voigt, Frank Peters

Industrial and Manufacturing Systems Engineering Publications

The dimensional capabilities of production aluminum castings are described. More than 480 production casting features have been evaluated for jobbing shop aluminum castings made in green sand and permanent molds. A comprehensive database of casting, feature and process descriptors has also been developed, so that the influence of these factors on casting dimensional variability can be evaluated.

Measurement system analysis techniques have been used to ensure that the dimensional variability measured was not influenced by excessive measurement system errors. The dimensional variability of both green sand and permanent-mold castings is less than is suggested by International Standards Organization (ISO) casting ...


Dimensional Variability Of Production Iron Castings, E.S. Nazareth, R.C. Voigt, Frank Peters Jan 1998

Dimensional Variability Of Production Iron Castings, E.S. Nazareth, R.C. Voigt, Frank Peters

Industrial and Manufacturing Systems Engineering Publications

The dimensional variability of casting features from production gray and ductile iron castings has been characterized. Dimensional data from castings and patterns has been collected from castings produced at several jobbing foundries. The variability of over 300 casting features from castings produced in green sand molds using jolt squeeze, high-pressure horizontal parting line and vertical parting line molding processes have been evaluated


Effect Of Casting Form Variability On Machining Fixturing Error, Frank Peters, E.J. Salisbury Jan 1998

Effect Of Casting Form Variability On Machining Fixturing Error, Frank Peters, E.J. Salisbury

Industrial and Manufacturing Systems Engineering Publications

Many castings are eventually machined to create additional /ea/I/res or tighter tolerances that are beyond the capabilities of the casting process. To accomplish this machining, the castings must be /neared in a fix/ti re. Surface errors on the casting will cause the position and orientation of the casting to be offset from the nominal. This could result in problems, since the cutting roof is often programmed with respect to the fixture.


A Probabilistic View Of Problems In Form Error Estimation, Tai-Hung Yang, John K. Jackman Jan 1997

A Probabilistic View Of Problems In Form Error Estimation, Tai-Hung Yang, John K. Jackman

Industrial and Manufacturing Systems Engineering Publications

Form error estimation techniques based on discrete point measurements can lead to significant errors in form tolerance evaluation. By modeling surface profiles as random variables, we show how sample size and fitting techniques affect form error estimation. Depending on the surface characteristics, typical sampling techniques can result in estimation errors of as much as 50 percent. Another issue raised in the fitting approach is the metric p selection for the fitting objective. We show that for p = 2 and p = ∞, the selection does not appear to significantly affect the estimation of form errors


Haccp As A Regulatory Innovation To Improve Food Safety In The Meat Industry, Laurian J. Unnevehr, Helen H. Jensen Feb 1996

Haccp As A Regulatory Innovation To Improve Food Safety In The Meat Industry, Laurian J. Unnevehr, Helen H. Jensen

CARD Working Papers

Industrial engineers in the food-processing industry have developed the Halyard Analysis Critical Control Point (HACCP) system as a preventive approach to ensuring the safety of meat and poultry products. This paper discusses both the origins of HACCP as an engineering concept and the economics of HACCP as a regulatory tool. The authors contend that the economics literature has not adequately explored the benefits from prevention, particularly when the costs of hazard detection are high and the exact benefits of a particular standard are uncertain but potentially large.


Ice Skate Blade Alignment Mechanism, Leon E. Girard, Patrick E. Patterson Aug 1992

Ice Skate Blade Alignment Mechanism, Leon E. Girard, Patrick E. Patterson

Iowa State University Patents

A blade alignment mechanism for an ice skate including a clamp for releasably securing the blade assembly to a skating boot in a trial position. The clamp includes a first member secured to the boot at a point remote from the screw apertures in the front or rear flanges, and a second member attached to the first member and disposed to contact one of the flanges to hold it in a trial position. The second member includes an enlarged adjustment opening that allows side-to-side and fore-and-aft adjustment of the second member with respect to the first member. The first and ...