Operational Research Commons^™

Performance Trade-Offs In Layouts For Relief Centers, Ananth Krishnamurthy, Sanket Bhat, Debjit Roy

12th IMHRC Proceedings (Gardanne, France – 2012)

At a disaster affected region, relief centers distribute critical supplies and aid to the affected victims. Unlike traditional distribution centers, relief centers experience significant ‘crowd effects’ due to the sudden influx of victims in a confined space. Using knowledge from studies on pedestrian traffic flow, specialized state dependent queuing models are developed to model the flow of victims along the walkways setup at a relief center. The underlying queuing network model is analyzed to derive expressions for the average times that victims experience before they receive the service at the relief center. The research shows that crowd density effects lead …

A Multi-Objective Optimization Approach For Designing Automated Warehouses, Tone Lerher, Matej Borovinšek, Iztok Potrč, Matjaž Šraml

12th IMHRC Proceedings (Gardanne, France – 2012)

A multi objective optimization of automated warehouses is discussed and evaluated in present paper. Since most of researchers in material handling community had performed optimization of decision variables with single objective function only (usually named with minimum travel time, maximum throughput capacity, minimum cost, etc.), the multi objective optimization (travel time – cost – quality) will be presented. For the optimization of decision variables in objective functions, the method with genetic algorithms is used. To find the Pareto optimal solutions, the NSGA II genetic algorithm was used. The main objective of our contribution is to determine the performance of the …

A Mathematical Model For Driver Balance In Truckload Relay Networks, Sarah Root, Hector A. Vergara

12th IMHRC Proceedings (Gardanne, France – 2012)

Driver retention has been cited as one of the primary motivating factors for the implementation of relay networks for full truckload transportation. The strategic design of such networks considering important operational factors such as limitations on load circuity and equipment balance has been previously studied in the literature, however driver scheduling has not been explicitly considered in routing decisions. We present a prescriptive modeling approach that uses mathematical programming in conjunction with a decomposition-based algorithm to select feasible duties that consider current hours-of-service regulations and assign them to drivers domiciled at relay points in the network to cover truckload demands …

Collaborative Freight Transportation To Improve Efficiency And Sustainability, Kimberly P. Ellis, Steven Roesch, Russell D. Meller

12th IMHRC Proceedings (Gardanne, France – 2012)

Collaborative distribution offers the potential for substantial improvements in freight transportation. As collaboration increases, more loads are available for sharing among transportation service providers, leading to more fully loaded trailers that travel fewer miles and reduce the cost per load on average. In this study, we develop approaches to analyze improvements in key performance measures as collaboration increases in freight transportation. For the data sets analyzed, improvements include a 34% increase in trailer fullness, a 29% reduction in average costs per load, and a 25% decrease in average miles per load. Based on this analysis, collaboration provides substantial improvements for …

Functional Design Of Physical Internet Facilities: A Road-Based Crossdocking Hub, Russell D. Meller, Benoit Montreuil, Collin Thivierge, Zachary Montreuil

12th IMHRC Proceedings (Gardanne, France – 2012)

As part of the 2010 IMHRC, Montreuil, Meller and Ballot proposed a set of facility types that would be necessary to operate a Physical Internet (PI, π), which they termed nodes. This paper is part of a three-paper series for the 2012 IMHRC where the authors provide functional designs of three PI facilities. This paper covers a unimodal road-based crossdocking hub designed specifically to exploit the characteristics of Physical Internet modular containers so as to enable the efficient and sustainable transhipment of each of them from its inbound truck to its outbound truck. The objective of the paper is to …

Dynamic Slotting Optimization Based On Skus Correlations In A Zone-Based Wave-Picking System, Li Yingde, Jeffery S. Smith

12th IMHRC Proceedings (Gardanne, France – 2012)

Many exiting slotting methods ignore the picking correlations between Stock Keeping Units (SKUs). In a previous paper, a mix integer program model for dynamic slotting to minimize the pick-wave makespan among all zones under some load balancing constraints was developed. In this paper, we develop an ant colony optimization with slot-exchange policy (ACO-SE) based on SKU correlation to assign the correlated SKUs to the adjacent slots in the same zone. The ACO-SE deposits pheromones between SKUs, uses local and global pheromone trail updates, and controls pheromone accumulation using the Max-Min rule. The main heuristic information is set to the correlation …

An Extended Double Row Layout Problem, Chase C. Murray, Xingquan Zuo, Alice E. Smith

12th IMHRC Proceedings (Gardanne, France – 2012)

The double row layout problem (DRLP) seeks to determine optimal machine locations on either side of an aisle, where the objective has been defined as the minimization of material ow cost among ma- chines while meeting machine clearance constraints. In this paper, we extend existing DRLP formulations in two respects. First, we consider the minimization of layout area besides the usual material ow cost objective. Second, we present a mixed integer linear programming formulation that permits non-zero aisle widths. This new formulation also includes new constraints that eliminate layout \mirroring," thus reducing the solution space significantly and thus solution times. …

Robust Material Handling System Design Based On The Risk Versus Cost Tradeoff, Marc Goetschalckx, Edward Huang, Pratik Mital

12th IMHRC Proceedings (Gardanne, France – 2012)

The design and planning of major material handling systems belongs to the class of systems design problems under uncertainty. The overall structure of the system is decided during the current design stage, while the values of the future conditions and the future planning decisions are not known with certainty. Typically the future uncertainty is modeled through a number of scenarios and each scenario has an individual timediscounted total system cost. The overall performance of the material handling system is characterized by the distribution of these scenario costs. The central tendency of the cost distribution is almost always computed as the …

Toward Sustainability, High Density And Short Response Time By Live-Cube Storage Systems, Nima Zaerpour, Yugang Yu, René De Koster

12th IMHRC Proceedings (Gardanne, France – 2012)

This paper studies random storage in a live-cube storage system where loads are stored multi-deep. Although such storage systems are still rare, they are increasingly used, for example in automated car parking systems. Each load is accessible individually and can be moved to a lift on every level of the system in x- and y-directions by a shuttle as long as an open slot is available next to it, comparable to Sam Loyd’s sliding puzzles. A lift moves the loads across different levels in z-direction. We derive the expected travel time of a random load from its storage location to …

Process Analysis For Material Flow Systems, Thorsten Schmidt, David Wustmann, Robert Schmaler

12th IMHRC Proceedings (Gardanne, France – 2012)

This paper describes a generic approach for analysis of internal behavior of logistic systems based on event logs. The approach is demonstrated by an example of event data from the simulation model of an automated material handling system (MHS) in a manufacturing company. The purpose of the analysis is the identification of design and operation problems and their causes, prospectively. As a result, the simulation model developer obtains the condensed and ranked information on events. These events describe the internal system behavior with anomalies pointing at either possible problems or capacity reserves.

A Study On Storage Allocation In An Automated Semiconductor Manufacturing Facility, St´Ephane Dauz`Ere-P´Er`Es, Claude Yugma, Ahmed Ben Chaabane, Ahmed Ben Chaabane, Lionel Rulli`Ere, Gilles Lamiable

12th IMHRC Proceedings (Gardanne, France – 2012)

This paper deals with the allocation of storage capacity in the automated material handling environment of a semiconductor wafer manufacturing facility. The impact of the allocation of stokers to machines in semiconductor fabrication facilities (fabs) is very little studied, although it significantly impacts the efficiency of the Automated Material Handling System (AMHS). After motivating and describing the problem of allocating unitary stokers to machines, a first local approach is discussed. We then propose a Mixed Integer linear Programming model to solve the global problem with two objectives: Minimizing the total maximum travel distance of vehicles and balancing the utilization of …

Design & Modeling Of A Single Machine Flow Rack As/Rs, Zaki Sari, Nadir Hakim Bessenouci

12th IMHRC Proceedings (Gardanne, France – 2012)

In this paper, we aim to introduce a new variation of the flow rack automated storage and retrieval system (AS/RS) using a single machine for storage and retrieval operations instead of two machines. Also, analytical expressions are derived for expected single and dual cycle times of the storage and retrieval machine. For that, randomized storage assignment, and Tchebychev travel are assumed. Two dwell point positions are investigated and compared to determine the best one. Finally an experimental validation using simulation is conducted to verify the quality of the developed.

An Mip Approach To The U-Line Balancing Problem With Proportional Worker Throughput, Reyhan Erin, Andres L. Carrano, Moises Sudit

12th IMHRC Proceedings (Gardanne, France – 2012)

One of the major challenges faced by manufacturing companies is to remain competitive in dynamic environments, where fluctuations in customer demand and production rates require systems capable of adapting in a practical and economical way. A U-shaped production cell is considered one of the most flexible designs for adapting the workforce level to varying conditions. However, re-balancing efforts are time consuming and often require a new work allocation and line design. In this paper, a two-stage MIP model to determine the best cell design under varying workforce levels is proposed. The model seeks to maintain proportionality between throughput and the …

A Yard Crane Scheduling Problem With Practical Constraints, Amin Hossein Gharehgozli, Yugang Yu, Rene De Koster, Gilbert Laporte

12th IMHRC Proceedings (Gardanne, France – 2012)

The problem considered in this paper is to locate storage containers while a set of container storage and retrieval requests are sequenced. Two automated cranes stack and retrieve containers in a single block of a yard. The cranes cannot pass each other and must be separated by a safety distance. Storage containers are initially located at the seaside and land side input/output (I/O) points of the block. Each must be stacked in a specific location of the block, selected from a set of open locations suitable for stacking the storage container. Retrieval containers are initially located in the block and …

Modeling The Inventory Requirement And Throughput Performance Of Picking Machine Order-Fulfillment Technology, Jennifer A. Pazour, Russell D. Meller

12th IMHRC Proceedings (Gardanne, France – 2012)

Picking machines, also known as remote-order-picking systems, are an example of a stock-to-picker piece-level order-fulfillment technology that consists of two or more pick stations and a common storage area. An integrated closed-loop conveyor decouples the pick stations from the storage area by transporting the needed totes to and from the storage area and the pick stations. We develop a probabilistic model capable of quantifying the inventory differences between order-fulfillment technologies that pool inventory with technologies that do not pool inventory. To determine the throughput of a picking machine, we develop a methodology that incorporates existing analytical models for the picking …

An Integrated Framework For Configurable Product Assortment Planning, Seyed Ali Taghavi Behbahani

Wayne State University Dissertations

A manufacturer's assortment is the set of products or product configurations that the company builds and offers to its customers. While the literature on assortment planning is growing in recent years, it is primarily aimed at non-durable retail and grocery products. In this study, we develop an integrated framework for strategic assortment planning of configurable products, with a focus on the highly complex automotive industry. The facts that automobiles are highly configurable (with the number of buildable configurations running into thousands, tens of thousands, and even millions) with relatively low sales volumes and the stock-out rates at individual dealerships (even …

An Unstable Balance: Exploration, Exploitation, And Innovation Decline During Development, Craig Randall

2012

he ability to innovate is considered central to firm performance and the consensus is that firms should balance exploration and exploitation innovation to succeed. Studies using an exploration/exploitation perspective have gained increasing interest, and have generally concluded that exploration innovation rates are too low. Researchers have concentrated on the early aspects of the innovation planning process: the Search, Portfolio Selection, and Design Phase, and have also studied the benefits of pursuing a serial or parallel pursuit of exploration and exploitation. Largely missing from exploration/exploitation innovation literature, however, is the development phase—which is among the longest and resource intensive phases of …

A System Dynamics Model For Simulating Ambulatory Health Care Demands, Rafael Diaz, Joshua G. Behr, Mandar Tulpule

VMASC Publications

Introduction: This article demonstrates the utility of the system dynamics approach to model and simulate US demand for ambulatory health care service both for the general population and for specific cohort subpopulations over the 5-year period, from 2003 to 2008. A system dynamics approach that is shown to meaningfully project demand for services has implications for health resource planning and for generating knowledge that is critical to assessing interventions.

Methods: The study uses a cohort-component method in combination with structural modeling to simulate ambulatory health care utilization. Data are drawn from the National Ambulatory Medical Care Survey and the National …

Epistemic Uncertainty Analysis: An Approach Using Expert Judgment And Evidential Credibility, Patrick Hester

Engineering Management & Systems Engineering Faculty Publications

When dealing with complex systems, all decision making occurs under some level of uncertainty. This is due to the physical attributes of the system being analyzed, the environment in which the system operates, and the individuals which operate the system. Techniques for decision making that rely on traditional probability theory have been extensively pursued to incorporate these inherent aleatory uncertainties. However, complex problems also typically include epistemic uncertainties that result from lack of knowledge. These problems are fundamentally different and cannot be addressed in the same fashion. In these instances, decision makers typically use subject matter expert judgment to assist …

Designing Optimal Aviation Baggage Screening Strategies Using The Monkey Search Algorithm, Edgar Ivan Jimenez

Open Access Theses & Dissertations

This thesis addresses the aviation baggage screening design problem considering several baggage screening devices which may be used for system implementation, the devices have different false clear and false alarm rates, throughput and purchase costs. In the present research, a comprehensive cost function which not only includes the cost associated with purchase and operation of baggage security devices, but also includes the indirect costs associated with device errors is used. A new monkey search based evolutionary algorithm is presented to determine the best selection of baggage screening security devices in order to minimize the expected annual total cost. The final …