Digital Commons Network^™

The George-Anne, Georgia Southern University

The George-Anne

• GSU Equestrians Tie with COC for 2nd Place
• News
• Views
• Campus Recreation & Intramurals
• Campus Services
• Features
• Classifieds
• Sports

The George-Anne, Georgia Southern University

The George-Anne

• Provost Search Continues
• News
• Views
• Weekend Wrap
• Reviews
• Features
• Classifieds
• Sports

Comparison Of Bacteroides Human Markers For Pollution Diagnostics In Recreational Waters, Asli Aslan, Joan B. Rose

Environmental Health Sciences: Faculty Presentations (2010-2017)

This presentation was given during the Great Lakes Beach Association Annual Conference.

The George-Anne, Georgia Southern University

The George-Anne

• Barrel Full of Cash
• GSA Hosts First Gay Prom
• Police Beat
• Candidates Chosen for Provost, Vice President Position
• A 'Fantastical, Mystical, Classical' Representation Of the Dartts
• USG Chancellor Retires
• Get off Facebook, Increase Happiness
• Shores Of Jersey With Muscles, Tans, Hair Gel and Low IQs
• An Unqualified Disgrace
• On Polls and Cellphones
• Does Facebook Make You Depressed?
• OxFam Hunger Banquet Tonight
• Homemade Bowls, Chili at Rotunda
• Campus Recreation & Intramurals
• Career Services
• The Importance of Experience
• Reliving Prom the Right Way
• A Walk In the Shoes Of the Homeless
• Classifieds
• Strength Of the Southern Conference
• Mocs Drop Eagles
• Women's Lacrosse …

A Maximum Pseudo-Likelihood Approach For Estimating Species Trees Under The Coalescent Model, Liang Liu, Lili Yu, Scott V. Edwards

Biostatistics: Faculty Publications

Background

Several phylogenetic approaches have been developed to estimate species trees from collections of gene trees. However, maximum likelihood approaches for estimating species trees under the coalescent model are limited. Although the likelihood of a species tree under the multispecies coalescent model has already been derived by Rannala and Yang, it can be shown that the maximum likelihood estimate (MLE) of the species tree (topology, branch lengths, and population sizes) from gene trees under this formula does not exist. In this paper, we develop a pseudo-likelihood function of the species tree to obtain maximum pseudo-likelihood estimates (MPE) of species trees, …

The Inkwell, Armstrong Atlantic State University

The Inkwell

No abstract provided.

Vlt Observations Of Ngc 1097'S “Dog-Leg” Tidal Stream: Dwarf Spheroidals And Tidal Streams, P. Galianni, F. Patat, James L. Higdon, S. Mieske, P. Kroupa

Physics & Astronomy: Faculty Publications

Aims. We investigate the structure and stellar population of two large stellar condensations (knots A & B) along one of the faint optical “jet-like” tidal streams associated with the spiral NGC 1097, with the goal of establishing their physical association with the galaxy and their origin.

Methods. We use the VLT/FORS2 to get deep V-band imaging and low-resolution optical spectra of two knots along NGC 1097's northeast “dog-leg” tidal stream. With this data, we explore their morphology and stellar populations.

Results. Spectra were obtained for eleven sources in the field surrounding the tidal stream. The great …

The Energetics Of Molecular Gas In Ngc 891 From H2 And Far-Infrared Spectroscopy, G. J. Stacey, Vassilis Charmandaris, F. Boulanger, Yanling Wu, F. Combes, S. J. U. Higdon, J. D. T. Smith, T. Nikola

Physics & Astronomy: Faculty Publications

We have studied the molecular hydrogen energetics of the edge-on spiral galaxy NGC?891, using a 34 position map in the lowest three pure rotational H2 lines observed with the Spitzer Infrared Spectrograph. The S(0), S(1), and S(2) lines are bright with an extinction-corrected total luminosity of ~2.8 × 107 L ?, or 0.09% of the total-infrared luminosity of NGC?891. The H2 line ratios are nearly constant along the plane of the galaxy?we do not observe the previously reported strong drop-off in the S(1)/S(0) line intensity ratio in the outer regions of the galaxy, so …

The George-Anne, Georgia Southern University

The George-Anne

• Virtual Food Court Comes to the Boro
• News
• Views
• Campus Recreation & Intramurals
• Features
• Classifieds
• Sports

Database Trials And Evaluations, Georgia Southern University, Zach S. Henderson Library

Library Publications (1999-2023)

• Database trials and evaluations

The Inkwell, Armstrong Atlantic State University

The Inkwell

No abstract provided.

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 …

A Flowshop Scheduling Problem With Transportation Times And Capacity Constraints, Abraham Mendoza, Jose A. Ventura, Kwei Long Huang

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

Although there are numerous methodologies and research studies on machine scheduling, most of the literature assumes that there is an unlimited number of transporters to deliver jobs from one machine to another for further processing and that transportation times can be neglected. These two assumptions are not applicable if one intends to generate an accurate schedule for the shop floor. In this research, a flowshop scheduling problem with two machines, denoted as M1 and M2, and a single transporter with capacity c is considered. The main focus is on the development of a dynamic programming algorithm to generate a schedule …

Optimization Of Costs And Service Level By Choosing The Best Customer Order Decoupling Point, Michael Schmidt, Detlef Spee

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

The customer order decoupling point (CODP) as the link in the supply chain between processes based on uncertain information, such as sales forecasts, and certain information in the form of customer orders is crucial for production efficiency, storage costs, and the quality of logistics. This paper focuses on developing an approach for identifying a CODP that provides the highest potential for achieving business objectives. Within the context of the above-mentioned topics, this paper focuses on the interrelations and the tradeoffs that have to be made when positioning the COPD. The goal of the paper is to present an effective and …

Distribution Planning Considering Warehousing Decisions, Pratik J. Parikh, Xinhui Zhang, Bhanuteja Sainathuni

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

Modern supply chains heavily depend on warehouses for rapidly fulfilling customer demands through retail, web-based, and catalogue channels. The traditional approach that considers warehouses as cost-centers has affected the profitability of numerous supply chains. A lack of synchronization between procurement and allocation decisions causes warehouses to scramble for resources during peak times and be faced with under-utilized resources during drought times. Warehouses, however, have emerged as service-centers and it is imperative that warehousing decisions be an integral part of supply chain decisions. In this paper we propose a mixed-integer programming model to integrate warehousing decisions with those of inventory and …

Using Data Envelopment Analysis To Evaluate The Performance Of Third Party Distribution Centers, Ching-Jung Ting, Hsueh-Lin Fang

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

There has been considerable interest worldwide in last few years in the growth of third party logistics (3PL) providers. 3PL distribution center (DC) enables firms to achieve reduced operating costs, increased revenues, and to focus on their core competence. This research aims to find the key performance indicators through a survey of a set of DCs and then evaluate their efficiency over the period 2005-2007 using data envelopment analysis (DEA) models based on selected performance indicators as inputs and outputs. Three inputs and two outputs for all DCs from the surveyed performance indicators were selected in this study. DEA is …

Freight Sequencing To Improve Hub Operations In The Less-Than-Truckload Freight Transportation Industry, Xiangshang Tong, Kimberly Ellis, Amy Brown Greer

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

In less-than-truckload freight transportation, hub operations affect the service levels that carriers are able to provide their customers. This paper focuses on improving the efficiency of hub operations by reducing freight handling time and cost. Specifically, the freight sequencing problem (FSP) is investigated to determine the freight unloading and loading sequence that minimizes the time for dock workers to transfer shipments from origin trailers to destination trailers. The FSP is modeled as a Rural Postman Problem (RPP) and three algorithms are compared: trailer-at-atime, nearest neighbor, and balance-and-connect. Using five industrial data sets, the results demonstrate the effectiveness, advantages, and disadvantages …

Multiple-Grooved Magnetic Traction Sheaves, Thorsten Schmidt, Thomas Leonhardt, Martin Anders

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

This paper discusses a new and innovative form of traction sheaves, which can be used in many hoisting applications that are driven with wire ropes in material handling systems. By use of high performance permanent magnets, integrated in the periphery of traction sheaves, a significant increase of driving capacity is achieved. In this special case it concerns high energy magnets consisting of rare earth materials known as NdFeB magnets. These magnets provide a 20 times higher force than conventional magnets. The results of the research show that the driving capacity of traction sheaves with a round groove design can be …

Design Of Cross-Chain Internet Order Fulfillment Centres, Kees Jan Roodbergen, Iris F. A. Vis, Jaap Boter

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

Many consumers have embraced the option of ordering via the Internet, which has resulted in an enormous increase in direct orders compared to the times when direct ordering was done by catalogue and phone. The fulfillment process in the supply chain is an important factor for these consumers impacting how long they must wait between ordering and delivery. This fact has significantly increased the importance of the back-end fulfillment process. We present a novel supply chain design to enable cross-chain coordination of order fulfillment operations for internet sales. Shared warehousing facilities are used more and more to achieve competitive advantage. …

Class-Based Storage With A Finite Number Of Items, Yugang Yu, René B.M. De Koster

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

ABC class-based storage is widely studied in literature and applied practice. It divides all stored items into a limited number of classes according to their demand rates (turnover per unit time). Classes of items with higher turnovers are stored in a region closer to the warehouse depot. In literature, it is commonly shown that the use of more storage classes leads to shorter travel time for storing and retrieving items. A basic assumption in this literature commonly is that the required storage space of items equals their average inventory levels, which is right if an infinite number of items are …

Designing Automated Warehouses By Minimising Investment Cost Using Genetic Algorithms, Tone Lerher, Iztok Potrc, Matjaz Sraml

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

The successful performance of the automated storage and retrieval systems is dependent upon the appropriate design and optimization process. In the present work a comprehensive model of designing automated storage and retrieval system for the single- and multi-aisle systems is presented. Because of the required conditions that the automated storage and retrieval systems should be technically highly efficient and that it should be designed on reasonable expenses, the objective function represents minimum total cost. The objective function combines elements of layout, time-dependent part, the initial investment and the operational costs. Due to the nonlinear, multi-variable and discrete shape of the …

Monitoring Inventory Accuracy With Statistical Process Control, Kyle Huschka, John R. English, Todd Easton, Andrew Huschka

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

Inventory accuracy is critical in most industrial environments such as distribution, warehousing, and retail. Many companies use a technique called cycle counting and have realized outstanding results in monitoring and improving inventory accuracy. The time and resources to complete cycle counting are sometimes limited or not available. In this work, we promote statistical process control (SPC) to monitor inventory accuracy. Specifically, we model the complex underlying environments with mixture distributions to demonstrate sampling from a mixed but stationary process. For our particular application, we concern ourselves with data that result from inventory adjustments at the stock keeping unit (SKU) level …

A Real-Time Picking And Sorting System In E-Commerce Distribution Centers, Yeming Gong, Erik M. M. Winands, Rene B. M. De Koster

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

Order fulfillment is the most expensive and critical operation for companies engaged in e-commerce. E-commerce distribution centers must rapidly organize the picking and sorting processes during and after the transaction has taken place, with the ongoing need to create greater responsiveness to customers. Sorting brings a relatively large setup time, which cannot be well admitted by existing polling models. We build a new stochastic polling model to describe and analyze such systems, and provide approximate explicit expressions for the complete distribution of order line waiting time for polling-based order picking systems and test their accuracy. These expressions lend themselves for …

Investigating Possible Synergies In Intermodal Operations With Truck And Rail, G. Don Taylor, Mia K. Burns, Gary L. Whicker

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

As the trucking industry continues to examine ways to provide better service at lower cost, many companies are more heavily utilizing intermodal (IM) strategies between truck and rail, especially for those loads that are relatively non-critical in terms of delivery time requirements and that have longer lengths of haul. As IM business grows, supporting dray infrastructure naturally develops around IM rail yards. What is unknown is whether it is best to have a dedicated set of drivers performing dray operations or if efficiency and cost savings can result when utilizing a joint driving fleet to concurrently support IM and traditionally …