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Articles 31 - 60 of 72

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

Decision Support For Vessel Traffic Service (Vts): User Needs For Dynamic Risk Management In The Vts, Gesa Praetorius Dec 2011

Decision Support For Vessel Traffic Service (Vts): User Needs For Dynamic Risk Management In The Vts, Gesa Praetorius

Gesa Praetorius

Vessel Traffic Service (VTS) is a shore-side service implemented by a “Competent Authority to improve the safety and efficiency of vessel traffic and to protect the environment”. It is a service that operates through VTS centers, from which VTS operators monitor traffic, assist in navigational matters and provide information to all ships in a designated area. As VTS is provided by operators located on shore, they usually make use of several decision support systems to be able to monitor the traffic and to provide information to the vessels. Although several new tools and approaches have been introduced in the VTS …


Inventory Planning And Coordination In Disaster Relief Efforts, Lauren Davis, Funda Samanlioglu, Xiuli Qu, Sarah Root Dec 2011

Inventory Planning And Coordination In Disaster Relief Efforts, Lauren Davis, Funda Samanlioglu, Xiuli Qu, Sarah Root

Dr. Lauren B Davis

This research proposes a stochastic programming model to determine how supplies should be positioned and distributed among a network of cooperative warehouses. The model incorporates constraints that enforce equity in service while also considering traffic congestion resulting from possible evacuation behavior and time constraints for providing effective response. We make use of short-term information (e.g., hurricane forecasts) to more effectively preposition supplies in preparation for their distribution at an operational level. Through an extensive computational study, we characterize the conditions under which prepositioning is beneficial, as well as discuss the relationship between inventory placement, capacity and coordination within the network.


A Hybrid Tabu Search And Constraint Programming Algorithm For The Dynamic Dial-A-Ride Problem, Gerardo Berbeglia Dec 2011

A Hybrid Tabu Search And Constraint Programming Algorithm For The Dynamic Dial-A-Ride Problem, Gerardo Berbeglia

Gerardo Berbeglia

No abstract provided.


Toward Unification Of Exact And Heuristic Optimization Methods, John Hooker Dec 2011

Toward Unification Of Exact And Heuristic Optimization Methods, John Hooker

John Hooker

No abstract provided.


Impact Of Batch Appointments On No-Show Rates: A Public Versus Private Clinic Perspective, Husniyah Abdus-Salaam, Lauren Davis Dec 2011

Impact Of Batch Appointments On No-Show Rates: A Public Versus Private Clinic Perspective, Husniyah Abdus-Salaam, Lauren Davis

Dr. Lauren B Davis

Much of the appointment scheduling literature has characterized the impact of no-show rates with respect to individual appointment requests. However, little is known about the impact of appointments that are grouped by household. This study is concerned with understanding the prevalence of these family group appointments and identifying the appointment characteristics that significantly influence no-show rates. Using historical data from a public and private pediatric clinic, Multiway Frequency Analysis is used to characterize the association between appointment characteristics and appointment size. A logistic regression model is also developed to identify the factors that contribute to no-show rates for both clinics. …


A Heuristic Approach For Allocation Of Data To Rfid Tags: A Data Allocation Knapsack Problem, Lauren Davis, Funda Samanlioglu, Xiaochun Jiang, Daniel Mota, Paul Stanfield Dec 2011

A Heuristic Approach For Allocation Of Data To Rfid Tags: A Data Allocation Knapsack Problem, Lauren Davis, Funda Samanlioglu, Xiaochun Jiang, Daniel Mota, Paul Stanfield

Dr. Lauren B Davis

Durable products and their components are increasingly being equipped with one of several forms of automatic identification technology such as radio frequency identification (RFID). This technology enables data collection, storage, and transmission of product information throughout its life cycle. Ideally all available relevant information could be stored on RFID tags with new information being added to the tags as it becomes available. However, because of the finite memory capacity of RFID tags along with the magnitude of potential lifecycle data, users need to be more selective in data allocation. In this research, the data allocation problem is modeled as a …


Evaluating The Impact Of Ehr On Clinical Reasoning Performance: A Ttf Perspective, Matthew Wills, Omar El-Gayar, Amit Deokar Dec 2011

Evaluating The Impact Of Ehr On Clinical Reasoning Performance: A Ttf Perspective, Matthew Wills, Omar El-Gayar, Amit Deokar

Amit Deokar

The proliferation of Electronic Health Records (EHR) as a backbone for healthcare delivery necessitates adequate tools for evaluating and improving the efficacy of such investments particularly as it relates to clinical reasoning performance. However, a thorough review of the literature indicates lack of a tested, validated instrument for evaluating and predicting the impact of EHR use on clinical reasoning performance. Despite successful application to a variety of other industries, TTF has not been adequately adapted to healthcare, EHR technology or the clinical reasoning task. Accordingly, the objectives of this research are to: 1) produce a valid instrument with diagnostic and …


Investigation Of Electrical Transport In Hydrogenated Multiwalled Carbon Nanotubes, Adam Friedman, Hyunkyung Chun, Don Heiman, Yung Jung, Latika Menon Jun 2011

Investigation Of Electrical Transport In Hydrogenated Multiwalled Carbon Nanotubes, Adam Friedman, Hyunkyung Chun, Don Heiman, Yung Jung, Latika Menon

Latika Menon

Highly disordered multiwalled carbon nanotubes of large outer diameter (~60 nm) fabricated by means of chemical vapor deposition process inside porous alumina templates exhibit ferromagnetism when annealed in a H2/Ar atmosphere. In the presence of an applied magnetic field, there is a transition from positive to negative magnetoresistance. The transition may be explained in terms of the Bright model for ordered and disordered carbon structures. Additionally, temperature dependent electrical transport experiments exhibit a zero-bias anomaly at low temperature.


Magnetic And Structural Investigation Of Heat Treated Ion Beam Sputtered Amorphous Co₇₄Fe₆B₁₅Si₅ Films, V. Harris, S. Oliver, W. Nowak, C. Vittoria, R. Culbertson, W. Elam, K. Kim Apr 2011

Magnetic And Structural Investigation Of Heat Treated Ion Beam Sputtered Amorphous Co₇₄Fe₆B₁₅Si₅ Films, V. Harris, S. Oliver, W. Nowak, C. Vittoria, R. Culbertson, W. Elam, K. Kim

Vincent G. Harris

As-deposited and annealed specimens of ion beam sputtered amorphous Co₇₄Fe₆B₁₅Si₅ thin films were examined to explore the correlation between changes in magnetic properties and atomic structure. Specimens were characterized magnetically, by traditional ac and dc techniques and structurally, via conversion-electron extended x-ray absorption fine structure analysis. Results show significant ordering of the higher order atomic shells around the transition metal ions well below the crystallization temperature. This ordering evolves into a body- centered-cubic configuration around both the Co and Fe ions. Increases in nearest neighbor peak positions in the EXAFS Fourier transforms were observed to correlate with increasing annealing temperatures. …


Information Sharing In Capacity Constrained Supply Chains, Lauren Davis, Russell King, Thom Hodgson, Wenbin Wei Dec 2010

Information Sharing In Capacity Constrained Supply Chains, Lauren Davis, Russell King, Thom Hodgson, Wenbin Wei

Dr. Lauren B Davis

We present a modelling approach for quantifying the value of information in supply chains using Markov decision processes (MDP). The case where information sharing occurs is modelled using a completely observable MDP. A restricted observation MDP is used to model the case where no information sharing occurs. We illustrate the use of this framework on a two-stage capacity-constrained supply chain consisting of a supplier and a retailer. We quantify the value of information sharing in this setting and construct several performance measures to identify the benefits to both the retailer and supplier as a result of the information sharing partnership.


Checking The Feasibility Of Dial-A-Ride Instances Using Constraint Programming, Gerardo Berbeglia, Gilles Pesant, Louis-Martin Rousseau Dec 2010

Checking The Feasibility Of Dial-A-Ride Instances Using Constraint Programming, Gerardo Berbeglia, Gilles Pesant, Louis-Martin Rousseau

Gerardo Berbeglia

No abstract provided.


Evaluating The Impact Of Patient Arrival Patterns In The Performance Of Appointment Scheduling Rules, Alcides Santander-Mercado, Jose Zayas-Castro, Laila Cure, Ali Yalcin Dec 2010

Evaluating The Impact Of Patient Arrival Patterns In The Performance Of Appointment Scheduling Rules, Alcides Santander-Mercado, Jose Zayas-Castro, Laila Cure, Ali Yalcin

Laila Cure

This paper evaluates the ability of commonly used Appointment Scheduling Rules (ASRs) in smoothing the effect of environmental factors in the performance of an outpatient scheduling system. ASRs have been widely implemented in outpatient clinics to improve performance measures such as staff idle time, patient waiting time, and facility congestion. However, the successful implementation of an ASR depends on its ability in dealing with the environmental factors affecting the system. Factors such as no-shows, variability of consultation times, patient unpunctuality, walk-in patient arrivals and the number of admitted patients per session affect the performance of the clinics in terms of …


Business Ethics As Rational Choice, John Hooker Dec 2010

Business Ethics As Rational Choice, John Hooker

John Hooker

No abstract provided.


Effects Of Boron Implantation In Films Of Iron-Nickel, J. Ryu, K. Castell, W. Nowak, C. Vittoria Dec 2010

Effects Of Boron Implantation In Films Of Iron-Nickel, J. Ryu, K. Castell, W. Nowak, C. Vittoria

Welville B. Nowak

We have implanted boron ions into films of Fe-Ni alloy composition. A homogeneous distribution of boron was determined from the sputter Auger analysis with a concentration of 18% and 34% for low- and high-dose implantation, respectively. The resistivity of film was increased by a factor of 2 and 4 as a result of low- and high-dose implantation, respectively. The magnetic properties of these films are studied as a function of annealing temperature by using FMR measurements. Both the uniaxial anisotropy field and FMR linewidth are dramatically decreased as a result of annealing at elevated temperatures. The changes of effective magnetization …


A Business-Mapping Approach To Multi-Criteria Group Selection Of Collection Centers And Recovery Facilities, Kishore Pochampally, Surendra Gupta Oct 2010

A Business-Mapping Approach To Multi-Criteria Group Selection Of Collection Centers And Recovery Facilities, Kishore Pochampally, Surendra Gupta

Surendra M. Gupta

For a prospective reverse supply chain to operate efficiently, the designing of that chain must involve selection of collection centers and recovery facilities that have sufficient success potentials. These success potentials depend heavily on the participation (in the reverse supply chain) of three important groups that have multiple, conflicting, and incommensurate goals. Therefore, the potentials must be evaluated based on the maximized consensus among the three groups, viz., (i) Consumers whose primary concern is convenience, (ii) Local government officials whose primary concern is environmental consciousness, and (iii) Supply chain company executives whose primary concern is profit. In this paper, we …


Design Of An Integrated Component Recovery System, Pitipong Veerakamolmal, Surendra Gupta Oct 2010

Design Of An Integrated Component Recovery System, Pitipong Veerakamolmal, Surendra Gupta

Surendra M. Gupta

This paper presents a two-stage disassembly and retrieval system that provides a unique solution for planning selective component recovery from products. The solution approach uses a process sequencing technique to schedule the operations in both stages to optimize the operational makespan.


A Combinatorial Cost-Benefit Analysis Methodology For Designing Modular Electronic Products For The Environment, Pitipong Veerakamolmal, Surendra Gupta Oct 2010

A Combinatorial Cost-Benefit Analysis Methodology For Designing Modular Electronic Products For The Environment, Pitipong Veerakamolmal, Surendra Gupta

Surendra M. Gupta

This paper presents a technique to analyze the efficiency of designing electronic products for the environment. The efficiency of each design is indicated using a Design for Disassembly Index (DfDI). DfDI uses a disassembly tree (DT) which relies on the product's bill of materials as its structural blueprint. DfDI can be used to compare the efficiency among alternative designs, identifying the best alternative for a product retirement plan. In addition, the index offers designers with an important measure to help improve future products.


A Multi-Phase Mathematical Programming Approach To Strategic Planning Of An Efficient Reverse Supply Chain Network, Kishore Pochampally, Surendra Gupta Oct 2010

A Multi-Phase Mathematical Programming Approach To Strategic Planning Of An Efficient Reverse Supply Chain Network, Kishore Pochampally, Surendra Gupta

Surendra M. Gupta

Strategic planning of a supply chain network is one of the most challenging aspects of reverse logistics. To effectively satisfy drivers such as profitability, environmental regulations and asset recovery, only the most economical used products must be reprocessed in only the recovery facilities that have the potential to efficiently reprocess them. Due to uncertainties in supply, quality and reprocessing times of used-products, the cost-benefit function in the literature that selects the most economical product to reprocess from a set of used-products is not appropriate for direct adoption. Moreover, due to the same uncertainties, any traditional forward supply chain approach to …


System Dynamics Approach In Inventory Management Of End-Of-Life Products In A Disassembly Line, Badr Johar, Surendra Gupta Sep 2010

System Dynamics Approach In Inventory Management Of End-Of-Life Products In A Disassembly Line, Badr Johar, Surendra Gupta

Surendra M. Gupta

A major challenge original equipment manufacturers (OEMs) currently face is how to implement an effective reverse supply chain network that is both cost effective and efficient. The rapid increase in the end-of-life (EOL) products returns from end customers back to origin for recovery or proper disposal can be said one of the main reasons behind this interest. Thus, the purpose of this paper is to examine the relationship between all elements of inventory management in the disassembly context using the system dynamic modeling approach to analyze the inventory of disassembled parts. Analysis of different market scenarios is conducted. The system …


Dynamic Programming For Solving Disassembly-To-Order System Under Stochastic Yields, Limited Supply, And Quantity Discount, Amre Massoud, Surendra Gupta Sep 2010

Dynamic Programming For Solving Disassembly-To-Order System Under Stochastic Yields, Limited Supply, And Quantity Discount, Amre Massoud, Surendra Gupta

Surendra M. Gupta

In this paper, we consider the disassembly-to-order (DTO) problem where a variety of returned end-of-life (EOL) products are disassembled in order to satisfy the demand for specified numbers of components. However, a lot of uncertainties exist in the disassembly process that further complicates the process. A DTO model has been developed that takes into consideration the different system uncertainties and variability. The DTO model was solved in multiple periods using dynamic programming (DP). The main objective was to determine optimal number of takeback EOL products in every period from each supplier to fulfill the demand of components while maximizing total …


An Evaluation Of The Effect Of Sensor Embedded Products In Product Disassembly With Precedence Relationships, Mehmet Ilgin, Surendra Gupta Sep 2010

An Evaluation Of The Effect Of Sensor Embedded Products In Product Disassembly With Precedence Relationships, Mehmet Ilgin, Surendra Gupta

Surendra M. Gupta

A promising solution approach to deal with the uncertainty associated with disassembly yield is sensor embedded products (SEPs) which involve sensors implanted during the production process. This study presents a quantitative assessment of the impact of SEPs on the various performance measures of a kanban-controlled air conditioner disassembly line. First, separate design of experiments studies based on orthogonal arrays are carried out for the cases with and without SEPs. Then, the results of paired-t tests comparing two cases based on different performance measures are presented.


Linear Physical Programming For Solving The Multi-Criteria Disassembly-To-Order Problem Under Stochastic Yields, Limited Supply, And Quantity Discount, Amre Massoud, Surendra Gupta Sep 2010

Linear Physical Programming For Solving The Multi-Criteria Disassembly-To-Order Problem Under Stochastic Yields, Limited Supply, And Quantity Discount, Amre Massoud, Surendra Gupta

Surendra M. Gupta

This paper focuses on the disassembly-to-order (DTO) problem. End-of-life (EOL) products are purchased from a number of suppliers in order to be disassembled into individual components to satisfy the demand for specified numbers of components. However, there are a lot of uncertainties that complicates the process. Previous work in the literature solved the DTO problem under multiple uncertainties and a single objective. Other models solved the multicriteria DTO problem with a single uncertainty. This paper develops a multi-criteria DTO model that takes into consideration multiple system uncertainties and solves it using Linear Physical Programming (LPP). The main objective was to …


An Optimization Framework For Advanced Disassembly/Repair-To-Order Systems With Remaining-Life Adjustment, Onder Ondemir, Surendra Gupta Sep 2010

An Optimization Framework For Advanced Disassembly/Repair-To-Order Systems With Remaining-Life Adjustment, Onder Ondemir, Surendra Gupta

Surendra M. Gupta

Due to environmental awareness and realization of cost savings, disassembly-to-order (DTO) concept has become popular. One of the main obstacles to making optimal DTO decisions is the uncertainty involved in end-of-life products (EOLPs). This uncertainty is due to the lack of information about the condition and the quantity of EOLPs returned. This uncertainty is removed by advanced disassembly/repair-to-order systems utilizing sensors to monitor the products in their life-cycle. Sensor technology enables remaining life estimation, thus allows advanced DTO models to deal with sophisticated component and product demands with remaining life adjustment. This paper presents an optimization framework for advanced disassembly/repair-to-order …


Cost-Benefit Analysis Of Sensor-Embedded Products Based Disassembly-To-Order System, Onder Ondemir, Surendra Gupta Sep 2010

Cost-Benefit Analysis Of Sensor-Embedded Products Based Disassembly-To-Order System, Onder Ondemir, Surendra Gupta

Surendra M. Gupta

Due to environmental awareness and realization of cost savings, disassembly-to-order (DTO) concept has become popular. One of the main obstacles to making optimal DTO decisions is the uncertainty involved in end-of-life products (EOLPs). This uncertainty is due to the lack of information about the condition and the quantity of EOLPs returned. This uncertainty can be removed by sensors monitoring the products in their life-cycle. However, DTO systems utilizing these sensors will be more costly to establish and maintain. This paper presents economic justification of establishing advanced disassembly-to-order (DTO) systems in which sensor-embedded end-of-life products are disassembled in order to fulfill …


Transportation Delays In Supply Networks: Stability Analysis & System Design, Rifat Sipahi, Stefan Lanmer, Silvia-Julian Niculescu, Dirk Helbing Sep 2010

Transportation Delays In Supply Networks: Stability Analysis & System Design, Rifat Sipahi, Stefan Lanmer, Silvia-Julian Niculescu, Dirk Helbing

Rifat Sipahi

No abstract provided.


Impact Of Demand Correlation And Information Sharing In A Capacitated Supply Chain With Multiple Retailers, Chanel Helper, Lauren Davis, Wenbin Wei Dec 2009

Impact Of Demand Correlation And Information Sharing In A Capacitated Supply Chain With Multiple Retailers, Chanel Helper, Lauren Davis, Wenbin Wei

Dr. Lauren B Davis

This paper considers a single product, two-echelon capacity constrainedsupplychain consisting of a supplier and two retailers facing correlated end-item demand. We use a decentralized Markov decision process with restricted observations to represent this system and conduct a numerical study to quantify the benefits of information sharing to the retailers under varying levels of supplier capacity and supply allocation mechanisms. Our results show an inverse relationship between capacity and information and indicate the retailers can achieve significant benefits as a result of the information sharing partnership.


Ontology-Based Information Extraction For Analyzing It Services, Amit Deokar, Sagnika Sen Dec 2009

Ontology-Based Information Extraction For Analyzing It Services, Amit Deokar, Sagnika Sen

Amit Deokar

Service Level Agreements (SLA) for multi-service Information Technology (IT) outsourcing contracts contain vast amounts of textual information. The SLAs provide details about a specific service, Key Performance Indicators (KPI) to measure its performance; as well as process elements, such as activities, events, and resources that are integral in achieving performance goals. However, KPIs and the process elements may be interrelated. The knowledge of such interrelationships is often tacitly present in the SLAs. The aim of our research is to extract this hidden information from IT service contracts and analyze them to empower customers of IT services to make better performance …


Dynamic Pickup And Delivery Problems, Gerardo Berbeglia Dec 2009

Dynamic Pickup And Delivery Problems, Gerardo Berbeglia

Gerardo Berbeglia

No abstract provided.


A Computationally Efficient Algorithm For Undiscounted Markov Decision Processes With Restricted Observations, Lauren Davis, Thom Hodgson, Russell King, Wenbin Wei Jan 2009

A Computationally Efficient Algorithm For Undiscounted Markov Decision Processes With Restricted Observations, Lauren Davis, Thom Hodgson, Russell King, Wenbin Wei

Dr. Lauren B Davis

We present a computationally efficient procedure to determine control policies for an infinite horizon Markov Decision process with restricted observations. The optimal policy for the system with restricted observations is a function of the observation process and not the unobservable states of the system. Thus, the policy is stationary with respect to the partitioned state space. The algorithm we propose addresses the undiscounted average cost case. The algorithm combines a local search with a modified version of Howard's (Dynamic programming and Markov processes, MIT Press, Cambridge, MA, 1960) policy iteration method. We demonstrate empirically that the algorithm finds the optimal …


Mac Pgp Encryption, Elizabeth Scheyder Dec 2008

Mac Pgp Encryption, Elizabeth Scheyder

Elizabeth C Scheyder

No abstract provided.