Operations Research, Systems Engineering and Industrial Engineering Commons^™

Open Location Management In Automated Warehousing Systems, Yugang Yu, René De Koster

12th IMHRC Proceedings (Gardanne, France – 2012)

A warehouse needs to have sufficient open locations to be able to deal with the change of item inventory levels, but due to ongoing storage and retrieval processes, open locations usually spread over storage areas. Unfavorable positions of open locations negatively impact the average load retrieval times. This paper presents a new method to manage these open locations such that the average system travel time for processing a block of storage and retrieval jobs in an automated warehousing system is minimized. We introduce the effective storage area (ESA), a well-defined part of the locations closest to the depot; where only …

Analysis Of Parameters Influencing In-Plant Milk Run Design For Production Supply, Eva Klenk, Stefan Galka, Willibald A. Günthner

12th IMHRC Proceedings (Gardanne, France – 2012)

In-plant milk-run systems are a transport concept for in-plant material delivery which is becoming more and more applicable especially in the automotive industry. This is due to the system characteristic of providing materials in small lot sizes and with high frequency. As there is a number of different milk run concepts applied and there are several parameters influencing the efficiency and stability of these systems, this paper aims at presenting an overview of common concepts and their properties together with key figures based on an empirical study. The concepts are further analyzed and evaluated with respect to resulting lead times …

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 …

Identification And Implementation Of Patterns Towards A Model Of Environmental Sustainability, S. Jimmy Gandhi, Santiago Perez, Danial Rushton, Robert Cloutier, Ipek Bozkurt, C. Ariel Pinto

Engineering Management & Systems Engineering Faculty Publications

Much like the Quality Revolution did in the 1980's, corporate sustainability has the potential to drive significant changes in the processes and structure of various organizations in the coming decade. With a rapidly growing global population and an ever increasing global demand for resources (Population-Resource-Center, 2012). Sustainability has emerged as one of the primary challenges that organizations will have to deal with in the 21st century. An increasing realization among business executives that profitability by itself is not enough as a measure of success is also driving the increased adoption of sustainable practices in the corporate world (Lowitt and Grimsley, …

Dock Assignment And Truck Scheduling Problems At Cross-Docking Terminals, Ching-Jung Ting, Amanda G. Rodríguez López

12th IMHRC Proceedings (Gardanne, France – 2012)

In this paper, we consider the integration of dock assignment and truck scheduling problem at cross-docking terminals. The problem is first formulated as a 0-1 integer programming model. Since both dock assignment and truck scheduling problems are NP-hard, its integration is more difficult to solve. Thus we propose reduced variable neighborhood search (RVNS) algorithms to solve the problem. Computational experiments are carried out on four set of instances. The results show that RVNS is capable of finding good solutions in a much shorter computation time when it is compared with optimization solver Gurobi’s solutions.

Multi-Party Multi-Period Supply Chain Coordination, Thin Yin Leong, Michelle Lee Fong Cheong

Research Collection School Of Computing and Information Systems

We apply combinatorial auction as a coordination mechanism to smooth demands placed on suppliers' limited production capacities, allowing several manufacturers to share common suppliers effectively. Products are bidders bidding for parts from suppliers, consuming their capacities in different time periods. The fourth party logistic (4PL) provider acts as the auctioneer to coordinate bids and perform price iterations. We leverage on the strong links between the Lagrangian relaxation method and combinatorial auction, where the Lagrange multipliers serve as the supply capacity reserve prices, to balance the demand and supply of capacities. To prevent cyclic behaviour and to increase convergence speed, we …

An Empirical Investigation Of Supply Chain Excellence In Healthcare, Brian Keith Smith

Graduate Theses and Dissertations

This research is motivated by opportunities to improve the cost and quality of healthcare delivery through improved supply chain processes. This research assesses the quality of the healthcare supply chain and identifies factors that are driving supply chain excellence among organizations in the healthcare industry. The first objective of this research is to assess the state of quality measurement in the healthcare supply chain. The achievement of this first objective is presented in Chapter 3 of this dissertation in the form of a manuscript accepted for publication in The Quality Management Journal. The second research objective is to develop …

Perspectives On Quality Coordination And Assurance In Global Supply Chains, Ling Li, John N. Warfield

Information Technology & Decision Sciences Faculty Publications

The 2007 recall of Berko Electric Toe-Space Heaters made in the US, the recall of backpack blowers made in Japan, the recalls of toys and pet food produced in China have exposed the potential of global supply chain disruptions. This product recall storm leads to the issue of quality assurance in global supply chain management. Product recalls indicate that manufacturing companies are particularly vulnerable to ensure quality when they source via a global supply chain with poor visibility. Obviously, a supply chain cannot afford this kind of sourcing and supply structure that threatens the supply-chain integrity. This special issue on …

Spiral Facility Layout Generation And Improvement Algorithm, Hatice E. Sanli, Fahrettin Eldemir

11th IMHRC Proceedings (Milwaukee, Wisconsin. USA – 2010)

This study is concerned with construction and improvement of a facility layout heuristic called Spiral Facility Layout Generation and Improvement Algorithm (SFLA). The algorithm starts with positioning departments from center point and continues like a hologram from center to outside. The aim of any facility layout algorithm is to better allocate the departments within facility. SFLA is compared with the existing space filling curve methods, MCRAFT and MULTIPLE, that are available in the literature. To form an initial spiral curve, a block system is used, like the bands for MCRAFT. The width and length of the blocks are given by …

Empirically-Based Warehouse Design: Can Academics Accept Such An Approach?, James M. Apple Jr., Russell D. Meller, John A. White Jr.

11th IMHRC Proceedings (Milwaukee, Wisconsin. USA – 2010)

It is our opinion that existing research is not sufficient to support the design of a warehouse. As a result, facility designers that work in practice are left to face the design process with their own methods. These methods are in stark contrast to the analytical models developed in academia in that they are highly based on empirical observations. Supported by a collection of empirical observations, facility designers who work in practice employ an ad hoc design process. We present a design process based on empirical observations and then formalize it so that it can be taught and used. We …

Dispatching Vehicles Considering Uncertain Handling Times At Port Container Terminals, Vu Duc Nguyen, Kap Hwan Kim

11th IMHRC Proceedings (Milwaukee, Wisconsin. USA – 2010)

This paper considers the problem of vehicle dispatching at port container terminals in a dynamic environment. The problem deals with the assignment of delivery orders of containers to vehicles while taking into consideration the uncertainty in the travel times of the vehicles. Thus, a real-time vehicle dispatching algorithm is proposed for adaptation to the dynamic changes in the states of the container terminals. To evaluate the performance of the proposed algorithm, a simulation study was conducted by considering various values of decision parameters under the uncertainty in travel times. Further, the performance of the proposed algorithm was compared with those …

Blocking Effects On Performance Of Warehouse Systems With Automonous Vehicles, Ananth Krishnamurthy, Sunderesh Heragu, Charles Malmborg

11th IMHRC Proceedings (Milwaukee, Wisconsin. USA – 2010)

Distribution centers are under increasing pressure to adopt material handling systems that offer greater flexibility to improve cycle time and throughput capacity in the transfer of unit loads in their high density storage areas. Autonomous Vehicles-based Storage and Retrieval Systems (AVS/RS), have been shown to hold significant promise in this context. In these systems, loads are transferred by autonomous vehicles. Vehicles support horizontal load movement along aisles and cross-aisles within a tier, and lifts support vertical movement between tiers. Existing research in AVS/RS, do not explicitly account for the potential blocking of vehicles and lifts while they are processing transactions. …

Merge Problems With High Speed Sorters, Dirk Jodin, Andreas Wolfschluckner

11th IMHRC Proceedings (Milwaukee, Wisconsin. USA – 2010)

To meet customer demands on distribution the necessity of sorting systems for unit loads in regard to quantity and capacity is growing up constantly.

Due to that, manufactures offer powerful sorting machines with a capacity up to 15.000 pieces per hour. Those machines are for instance Crossbelt or Tilt-Tray sorters. The output of these sorters is calculated by the equation of throughput.

The point of interest is the merge, referring to the overall efficiency of the single sorter. The motion sequence during merging has to be absolutely quick and precise to achieve exact positioning using minimized distances of the single …

The Future Of Modeling In Material Handling Systems, Leon F. Mcginnis

11th IMHRC Proceedings (Milwaukee, Wisconsin. USA – 2010)

Today, when we talk about “modeling” in the context of material handling systems, invariably we are referring to a mathematical or computational model for analyzing some aspect of the system, such as its throughput rate, response time, cost of ownership, required storage capacity, etc. Creating these kinds of models requires considerable knowledge in at least two domains the material handling system domain, and the analysis methodology domain—and considerable skill in the “art of modeling” in order to express the former in the terms of the latter. The results can be somewhat ad hoc—e.g., two different modelers are likely to create …

Optimizing Distribution Center Configuration: A Practical View Of A Multi-Objective Problem, Russell D. Meller, Lisa M. Thomas

11th IMHRC Proceedings (Milwaukee, Wisconsin. USA – 2010)

The shape of a distribution center, as well as whether dock locations are on one side or two sides of the facility, impacts measures like travel distances and the number of dock locations that may be utilized. Thus, for a required number of pallet locations, there are multiple combinations of distribution center shape and dock configurations that should be evaluated against multiple measures. We have developed a practical model for making such evaluations and illustrate the model with data reflective of a partner in the Center for Engineering Logistics and Distribution.

The Effect Of Interaction Between The Production System (Ps) And A Looped Conveyor-Based Material Handling System (Lcmhs) In A Manufacturing Facility, Vernet Lasrado, Dima Nazzal

11th IMHRC Proceedings (Milwaukee, Wisconsin. USA – 2010)

In this paper, we provide empirical evidence that shows the effect of the interaction between the production system (PS) and a looped conveyor-based material handling system (LCMHS) in a manufacturing facility. A rudimentary simulation model captures the interaction between the two systems. Varying several key factors, we test for a statistically significant difference in the work in process (WIP) of the production system with and without the LCMHS to find if the squared coefficient of variation (SCV) of the interarrival time distribution to the PS is affected. The results suggest the need to model the interaction between the two systems …