TY - JOUR TI - Topology control for load shed recovery AU - Escobedo, Adolfo R. AU - Moreno-Centeno, Erick AU - Hedman, Kory W. T2 - IEEE Transactions on Power Systems AB - This paper introduces load shed recovery actions for transmission networks by presenting the dc optimal load shed recovery with transmission switching model (DCOLSR-TS). The model seeks to reduce the amount of load shed, which may result due to transmission line and/or generator contingencies, by modifying the bulk power system topology. Since solving DCOLSR-TS is computationally difficult, the current work also develops a heuristic (MIP-H), which improves the system topology while specifying the required sequence of switching operations. Experimental results on a list of N-1 and N-2 critical contingencies of the IEEE 118-bus test case demonstrate the advantages of utilizing MIP-H for both online load shed recovery and recurring contingency-response analysis. This is reinforced by the introduction of a parallelized version of the heuristic (Par-MIP-H), which solves the list of critical contingencies close to 5x faster than MIP-H with 8 cores and up to 14x faster with increased computational resources. The current work also tests MIP-H on a real-life, large-scale network in order to measure the computational performance of this tool on a real-world implementation. DA - 2013/// PY - 2013/// DO - 10.1109/tpwrs.2013.2286009 VL - 29 IS - 2 SP - 908–916 ER - TY - JOUR TI - An Approach for Setting Inventory Norms for a Two-Echelon Supply Chain AU - Ramkumar, N. AU - Subramanian, P. AU - Narendran, T. T. AU - Ganesh, K. T2 - International Journal of Information Systems and Supply Chain Management AB - Managing inventories is crucial to the objective of minimizing supply chain costs. This paper presents an approach for setting inventory norms in context of a real-life case of an industry which practices Vendor Managed Inventory (VMI). The role of warehouses and the inventories held by them becomes significant in such an environment. This paper presents a two-phase approach to determine various components of inventory norms taking into account lead time and demand variability. Innovative strategic product classification has been done to decide upon stocking quantity at warehouses. DA - 2013/10/1/ PY - 2013/10/1/ DO - 10.4018/ijisscm.2013100106 VL - 6 IS - 4 SP - 102-119 LA - ng OP - SN - 1935-5726 1935-5734 UR - http://dx.doi.org/10.4018/ijisscm.2013100106 DB - Crossref ER - TY - JOUR TI - PRISM: PRIority based SiMulated annealing for a closed loop supply chain network design problem AU - Subramanian, P. AU - Ramkumar, N. AU - Narendran, T.T. AU - Ganesh, K. T2 - Applied Soft Computing AB - Concerns over environmental degradation, legislative requirements and growing needs of business have fueled the growth of Closed Loop Supply Chains (CLSC). We consider a CLSC and address the issues of designing the network and of optimizing the distribution. Four variants of the problem are considered. The problem is modeled as an Integer Linear Program (ILP). We develop a constructive heuristic based on Vogel's approximation method–total opportunity cost method to provide good initial solutions to a priority-based simulated annealing heuristic, to accelerate its convergence. Trials on a set of hypothetical datasets have yielded encouraging results. The methodology is also tested using a case study data of a company producing electronic products. Implications for sustainability are discussed. DA - 2013/2// PY - 2013/2// DO - 10.1016/j.asoc.2012.10.004 VL - 13 IS - 2 SP - 1121-1135 J2 - Applied Soft Computing LA - en OP - SN - 1568-4946 UR - http://dx.doi.org/10.1016/j.asoc.2012.10.004 DB - Crossref ER - TY - JOUR TI - A bi-objective network design model for multi-period, multi-product closed-loop supply chain AU - Pazhani, Subramanian AU - Ramkumar, N. AU - Narendran, T.T. AU - Ganesh, K. T2 - Journal of Industrial and Production Engineering AB - Concerns over environmental degradation legislative requirements and growing business needs have fueled the growth of closed-loop supply chains (CLSCs). This paper addresses a bi-objective network design problem for multi-period, multi-product CLSC to minimize the total supply chain costs and to maximize the service efficiency of the warehouses and hybrid facilities. We develop a bi-objective mixed integer linear programming model to assist decisions in (1) location/operating decisions for warehouses, hybrid facilities and manufacturing facilities and (2) production and distribution of products between stages in the supply chain. Goal programming models and compromise programming techniques are used to solve the problem. An application of the model is demonstrated using a case study from the literature. DA - 2013/6// PY - 2013/6// DO - 10.1080/21681015.2013.830648 VL - 30 IS - 4 SP - 264-280 J2 - Journal of Industrial and Production Engineering LA - en OP - SN - 2168-1015 2168-1023 UR - http://dx.doi.org/10.1080/21681015.2013.830648 DB - Crossref ER - TY - CONF TI - Optimizing Inventory Levels in a Serial Supply Chain considering Multiple Suppliers and Transportation Costs AU - Pazhani, Subramanian AU - Ventura, José A AU - Mendoza, Abraham. T2 - Institute of Industrial Engineers-Publisher C2 - 2013/// C3 - IIE Annual Conference DA - 2013/// SP - 3994-4002 ER - TY - CONF TI - Design of Closed Loop Supply Chain Networks AU - Pazhani, Subramanian AU - Ravindran, A. Ravi T2 - Institute of Industrial Engineers-Publisher C2 - 2013/// C3 - IIE Annual Conference. Proceedings DA - 2013/// ER - TY - CONF TI - Three Phase Heuristics for Inventory Routing Problem AU - Ramkumar, N. AU - Pazhani, S. AU - Narendran, T. T. AU - Ganesh, K. T2 - Institute of Industrial Engineers-Publisher C2 - 2013/// C3 - IIE Annual Conference. Proceedings DA - 2013/// SP - 4003 ER - TY - CONF TI - Machining depth regulation and friction reduction in AFM-based ultrasonic vibration assisted nanomachining AU - Zhang, L. AU - Dong, J. AU - Cohen, P.H. C2 - 2013/// C3 - Transactions of the North American Manufacturing Research Institution of SME DA - 2013/// VL - 41 SP - 482-488 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84892764978&partnerID=MN8TOARS ER - TY - CONF TI - Hybrid hierarchical fabrication of three-dimensional scaffolds AU - Wei, C. AU - Dong, J. C2 - 2013/// C3 - Transactions of the North American Manufacturing Research Institution of SME DA - 2013/// VL - 41 SP - 541-547 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84892703159&partnerID=MN8TOARS ER - TY - CONF TI - Production Planning using Nonlinear Clearing Functions: A Review of Recent Results AU - Kacar, N.B. AU - Moench, L. AU - Uzsoy, R. T2 - SIAM Conference on Computational Science and Engineering C2 - 2013/2// CY - Boston, MA DA - 2013/2// PY - 2013/2// ER - TY - CONF TI - Improving Shop Floor Level Performance in a Dynamic Lot Sizing Environment with Congestion AU - Albey, E. AU - Uzsoy, R. T2 - Industrial and Systems Engineering Research Conference C2 - 2013/5// CY - San Juan, PR DA - 2013/5// PY - 2013/5// ER - TY - CONF TI - Using Clearing Functions for Production Planning in Large-Scale Wafer Fabs AU - Kacar, N.B. AU - Monch, L. AU - Uzsoy, R. T2 - Industrial and Systems Engineering Research Conference C2 - 2013/5// CY - San Juan, PR DA - 2013/5// PY - 2013/5// ER - TY - CONF TI - Minimizing End Effects in Rolling Horizon Algorithms for Production Planning: An Experimental Study AU - Lin, P.C. AU - Uzsoy, R. T2 - Industrial and Systems Engineering Research Conference C2 - 2013/5// CY - San Juan, PR DA - 2013/5// PY - 2013/5// ER - TY - CONF TI - Production Planning with Load-Dependent Lead Times and Uncertain Demands AU - Norouzi, A. AU - Uzsoy, R. T2 - Industrial and Systems Engineering Research Conference C2 - 2013/5// CY - San Juan, PR DA - 2013/5// PY - 2013/5// ER - TY - CONF TI - Modeling for Equitable Food Distribution in North Carolina AU - Sengul, I. AU - Ivy, J.S. AU - Uzsoy, R. T2 - Industrial and Systems Engineering Research Conference C2 - 2013/5// CY - San Juan, PR DA - 2013/5// PY - 2013/5// ER - TY - ER - TY - ER - TY - JOUR TI - A Mixture Distribution of Spatial Attention AU - Feng, Jing AU - Spence, Ian T2 - Experimental Psychology AB - Although it may seem paradoxical, the unified-focus and multiple-foci theories of spatial selective attention are both well supported by experimental evidence. However, the apparent contradiction is illusory and the two competing views may be reconciled by a closer examination of the spatial mechanisms involved. We propose that the deployment of attention may be modeled as a mixture of individual distributions of attention and we tested this hypothesis in two experiments. Participants had to identify targets among distractors, with the targets presented at various distances from the cued locations. Experiment 1 confirmed that the distribution of attention may be described by a mixture of individual distributions, each centered at a cued location. Experiment 2 showed that cue separation is an important determinant of whether spatial attention is divided or not. DA - 2013/2// PY - 2013/2// DO - 10.1027/1618-3169/a000182 VL - 60 IS - 3 SP - 149-156 J2 - Experimental Psychology LA - en OP - SN - 1618-3169 2190-5142 UR - http://dx.doi.org/10.1027/1618-3169/a000182 DB - Crossref KW - spatial selective attention KW - divided attention KW - distributed attention ER - TY - JOUR TI - How Speech Modifies Visual Attention AU - Spence, Ian AU - Jia, Andrew AU - Feng, Jing AU - Elserafi, Jonny AU - Zhao, Ying T2 - Applied Cognitive Psychology AB - Summary Auditory distractions can have serious consequences in critical situations such as driving. Mobile phones, radios, media players, and information devices that interpret and produce speech are increasingly common in vehicles, but the threats to visual attention are not yet fully understood. In three experiments, we found that most speech tasks had relatively small adverse effects on the detection of a briefly presented target among distractors across a 60° subarea of the visual field. Although there was a little impact on detectability, moderately difficult speech tasks slowed responding relative to silence. Our most demanding condition—generating and speaking a word beginning with the last letter of another word—had the greatest effects on accuracy and latency, with responding slowed by about 900 ms. An impairment of this magnitude presents a significant threat to safe driving and calls into question the belief that hands‐free voice‐controlled devices are the answer to the problem of driver distraction. Copyright © 2013 John Wiley & Sons, Ltd. DA - 2013/9// PY - 2013/9// DO - 10.1002/ACP.2943 VL - 27 IS - 5 SP - 633-643 SN - 0888-4080 UR - http://dx.doi.org/10.1002/ACP.2943 ER - TY - JOUR TI - Optimal design of a new 3D haptic gripper for telemanipulation, featuring magnetorheological fluid brakes AU - Nguyen, Q H AU - Choi, S B AU - Lee, Y S AU - Han, M S T2 - Smart Materials and Structures AB - In this research work, a new configuration of a 3D haptic gripper for telemanipulation is proposed and optimally designed. The proposed haptic gripper, featuring three magnetorheological fluid brakes (MRBs), reflects the rolling torque, the grasping force and the approach force from the slave manipulator to the master operator. After describing the operational principle of the haptic gripper, an optimal design of the MRBs for the gripper is performed. The purpose of the optimization problem is to find the most compact MRB that can provide a required braking torque/force to the master operator while the off-state torque/force is kept as small as possible. In the optimal design, different types of MRBs and different MR fluids (MRFs) are considered. In order to obtain the optimal solution of the MRBs, an optimization approach based on finite element analysis (FEA) integrated with an optimization tool is used. The optimal solutions of the MRBs are then obtained and the optimized MRBs for the haptic gripper are identified. In addition, discussions on the optimal solutions and performance of the optimized MRBs are given. DA - 2013/// PY - 2013/// DO - 10.1088/0964-1726/22/1/015009 VL - 22 IS - 1 SP - 015009 SN - 0964-1726 1361-665X UR - http://dx.doi.org/10.1088/0964-1726/22/1/015009 ER - TY - BOOK TI - Linear Conic Optimization AU - Fang, Shu-Cherng AU - Xing, W. DA - 2013/// PY - 2013/// PB - Science Press SN - 97870381767 ER - TY - JOUR TI - ℓ1 Major Component Detection and Analysis (ℓ1 MCDA): Foundations in Two Dimensions AU - Tian, Ye AU - Jin, Qingwei AU - Lavery, John AU - Fang, Shu-Cherng T2 - Algorithms AB - Principal Component Analysis (PCA) is widely used for identifying the major components of statistically distributed point clouds. Robust versions of PCA, often based in part on the ℓ1 norm (rather than the ℓ2 norm), are increasingly used, especially for point clouds with many outliers. Neither standard PCA nor robust PCAs can provide, without additional assumptions, reliable information for outlier-rich point clouds and for distributions with several main directions (spokes). We carry out a fundamental and complete reformulation of the PCA approach in a framework based exclusively on the ℓ1 norm and heavy-tailed distributions. The ℓ1 Major Component Detection and Analysis (ℓ1 MCDA) that we propose can determine the main directions and the radial extent of 2D data from single or multiple superimposed Gaussian or heavy-tailed distributions without and with patterned artificial outliers (clutter). In nearly all cases in the computational results, 2D ℓ1 MCDA has accuracy superior to that of standard PCA and of two robust PCAs, namely, the projection-pursuit method of Croux and Ruiz-Gazen and the ℓ1 factorization method of Ke and Kanade. (Standard PCA is, of course, superior to ℓ1 MCDA for Gaussian-distributed point clouds.) The computing time of ℓ1 MCDA is competitive with the computing times of the two robust PCAs. DA - 2013/1/17/ PY - 2013/1/17/ DO - 10.3390/a6010012 VL - 6 IS - 1 SP - 12-28 J2 - Algorithms LA - en OP - SN - 1999-4893 UR - http://dx.doi.org/10.3390/a6010012 DB - Crossref KW - heavy-tailed distribution KW - l(1) KW - l(2) KW - major component KW - multivariate statistics KW - outliers KW - principal component analysis KW - 2D ER - TY - JOUR TI - A model for optimally dispatching ambulances to emergency calls with classification errors in patient priorities AU - McLay, Laura A. AU - Mayorga, Maria E. T2 - IIE Transactions AB - Abstract The decision of which servers to dispatch to which customers is an important aspect of service systems. Such decisions are complicated when servers have different operating characteristics, customers are prioritized, and there are errors in assessing customer priorities. This article formulates a model for determining how to optimally dispatch servers to prioritized customers given that dispatchers make classification errors in assessing the true customer priorities. These issues are examined through the lens of Emergency Medical Service (EMS) dispatch, for which a Markov Decision Process (MDP) model is developed that captures how to optimally dispatch ambulances (servers) to prioritized patients (customers). It is assumed that patients arrive sequentially, with the location and perceived priority of each patient becoming known upon arrival. The proposed model determines how to optimally dispatch ambulances to patients to maximize the long-run average utility of the system, defined as the expected coverage of true high-risk patients. The utilities and transition probabilities are location dependent, with respect to both the ambulance and patient locations. The analysis considers two cases for approaching the classification errors that correspond to over- and under-responding to perceived patient risk. A computational example is applied to an EMS system. The optimal policies under different classification strategies are compared to a myopic policy and the effect that classification errors have on the performance of these policies is examined. Simulations suggest that the policies remain effective when they are applied to more realistic situations. Keywords: Emergency medical dispatchMarkov decision processes DA - 2013/1// PY - 2013/1// DO - 10.1080/0740817x.2012.665200 VL - 45 IS - 1 SP - 1-24 J2 - IIE Transactions LA - en OP - SN - 0740-817X 1545-8830 UR - http://dx.doi.org/10.1080/0740817x.2012.665200 DB - Crossref KW - Emergency medical dispatch KW - Markov decision processes ER - TY - JOUR TI - Joint location and dispatching decisions for Emergency Medical Services AU - Toro-Díaz, Hector AU - Mayorga, Maria E. AU - Chanta, Sunarin AU - McLay, Laura A. T2 - Computers & Industrial Engineering AB - The main purpose of Emergency Medical Service systems is to save lives by providing quick response to emergencies. The performance of these systems is affected by the location of the ambulances and their allocation to the customers. Previous literature has suggested that simultaneously making location and dispatching decisions could potentially improve some performance measures, such as response times. We developed a mathematical formulation that combines an integer programming model representing location and dispatching decisions, with a hypercube model representing the queuing elements and congestion phenomena. Dispatching decisions are modeled as a fixed priority list for each customer. Due to the model’s complexity, we developed an optimization framework based on Genetic Algorithms. Our results show that minimization of response time and maximization of coverage can be achieved by the commonly used closest dispatching rule. In addition, solutions with minimum response time also yield good values of expected coverage. The optimization framework was able to consistently obtain the best solutions (compared to enumeration procedures), making it suitable to attempt the optimization of alternative optimization criteria. We illustrate the potential benefit of the joint approach by using a fairness performance indicator. We conclude that the joint approach can give insights of the implicit trade-offs between several conflicting optimization criteria. DA - 2013/4// PY - 2013/4// DO - 10.1016/j.cie.2013.01.002 VL - 64 IS - 4 SP - 917-928 J2 - Computers & Industrial Engineering LA - en OP - SN - 0360-8352 UR - http://dx.doi.org/10.1016/j.cie.2013.01.002 DB - Crossref KW - Location/allocation in healthcare KW - Hypercube model KW - Genetic algorithm ER - TY - JOUR TI - Districting and dispatching policies for emergency medical service systems to improve patient survival AU - Mayorga, Maria E. AU - Bandara, Damitha AU - McLay, Laura A. T2 - IIE Transactions on Healthcare Systems Engineering AB - The major focus of Emergency Medical Service (EMS) system is to save lives and to minimize the effects of emergency health incidents. Districting, or designing pre-determined response areas, allows an EMS system to reduce the response time of paramedic support to the incident. Furthermore, dispatching policies affect system performance. Thus, in this study we propose integrated dispatching and districting policies to improve the performance of EMS systems. We measure performance in terms of patient survival probability. We propose several policies for districting/dispatching, these are provided as inputs to a simulation model that compares the performance of different policies. Our response areas, or districts, are designed using a constructive heuristic which considers adjusted expected coverage. Intra-district and inter-district dispatching policies are developed considering the degree of the urgency of the call. Computational results show that integrated districting and dispatching policies are vital in increasing patient survivability. DA - 2013/1// PY - 2013/1// DO - 10.1080/19488300.2012.762437 VL - 3 IS - 1 SP - 39-56 J2 - IIE Transactions on Healthcare Systems Engineering LA - en OP - SN - 1948-8300 1948-8319 UR - http://dx.doi.org/10.1080/19488300.2012.762437 DB - Crossref ER - TY - CONF TI - Understanding the visualization strategies used by experts when reading mechanical part drawings using eye tracking AU - Nambiar, S. AU - Madathil, K.C. AU - Paul, M.D. AU - Zelaya, M. AU - Koikkara, R. AU - Gramopadhye, A.K. C2 - 2013/// C3 - IIE Annual Conference and Expo 2013 DA - 2013/// SP - 503-511 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84900300219&partnerID=MN8TOARS ER - TY - CHAP TI - Data and Information Fusion for Bio-Medical Design and Bio-Manufacturing Systems AU - Lee, Yuan-Shin AU - Qin, Xiaofeng AU - Prim, Peter AU - Cai, Yi T2 - Proceedings of the Institute of Industrial Engineers Asian Conference 2013 A2 - Lin, Y.K. A2 - Tsao, Y.C. A2 - Lin, S.W. PY - 2013/// DO - 10.1007/978-981-4451-98-7_177 SP - 1513–1520 PB - Springer SN - 9789814451970 9789814451987 UR - http://dx.doi.org/10.1007/978-981-4451-98-7_177 ER - TY - JOUR TI - Comparing traditional and fuzzy-set solutions to (Q, r) inventory systems with discrete lead-time distributions T2 - Journal of Intelligent and Fuzzy Systems AB - Using a previously published approach to computing Q, r policies for an inventory system with uncertain parameters described by fuzzy sets, we compare thee methods for specifying lead-time demand for four different empirically-specified, non-normal distributions of replenishment lead time. This general distribution of lead time results in a situation in which the distribution of demand over the lead time, or lead-time demand LTD, is not easily specified. We compare Q, r policies generated by using a traditional normal approximation to LTD, a fuzzy-set approximation, and the optimal policy computed via a simulation-optimization approach that utilizes the explicit LTD distribution. We show that, on average, the results from the fuzzy-set model are significantly more accurate than the traditional normal approximation, especially when the LTD distribution is highly skewed. DA - 2013/// PY - 2013/// DO - 10.3233/IFS-2012-0533 VL - 24 IS - 1 SP - 93-104 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84872357892&partnerID=MN8TOARS KW - Inventory KW - (Q, r) systems KW - fuzzy sets KW - optimization KW - simulation ER - TY - CONF TI - A newsvendor problem with replenishment AU - Buch, N. AU - King, R.E. AU - Vila-Parrish, A. AU - Warsing, D.P. C2 - 2013/// C3 - IIE Annual Conference and Expo 2013 DA - 2013/// SP - 3934-3943 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84900327424&partnerID=MN8TOARS ER - TY - JOUR TI - Integrated Planning of Supply Chain Networks and Multimodal Transportation Infrastructure Expansion: Model Development and Application to the Biofuel Industry AU - Hajibabai, L. AU - Ouyang, Y. T2 - Computer-Aided Civil and Infrastructure Engineering AB - Abstract: As the biofuel industry continues to expand, the construction of new biorefinery facilities induces a huge amount of biomass feedstock shipment from supply points to the refineries and biofuel shipment to the consumption locations, which increases traffic demand in the transportation network and contributes to additional congestion (especially in the neighborhood of the refineries). Hence, it is beneficial to form public‐private partnerships to simultaneously consider transportation network expansion and biofuel supply chain design to mitigate congestion. This article presents an integrated mathematical model for biofuel supply chain design where the near‐optimum number and location of biorefinery facilities, the near‐optimal routing of biomass and biofuel shipments, and possible highway/railroad capacity expansion are determined. The objective is to minimize the total cost for biorefinery construction, transportation infrastructure expansion, and transportation delay (for both biomass/biofuel shipment and public travel) under congestion. A genetic algorithm framework (with embedded Lagrangian relaxation and traffic assignment algorithms) is developed to solve the optimization model, and an empirical case study for the state of Illinois is conducted with realistic biofuel production data. The computational results show that the proposed solution approach is able to solve the problem efficiently. Various managerial insights are also drawn. It shall be noted that although this article focuses on the booming biofuel industry, the model and solution techniques are suitable for a number of application contexts that simultaneously involve network traffic equilibrium, infrastructure expansion, and facility location choices (which determine the origin/destination of multi‐commodity flow). DA - 2013/// PY - 2013/// DO - 10.1111/j.1467-8667.2012.00791.x VL - 28 IS - 4 SP - 247-259 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84874741231&partnerID=MN8TOARS ER - TY - CHAP TI - Behavioral Characteristics of Users with Visual Impairment in Haptically Enhanced Virtual Environments AU - Liu, Shijing AU - Bahn, Sangwoo AU - Choi, Heesun AU - Nam, Chang S. T2 - Human-Computer Interaction. Interaction Modalities and Techniques AB - This study investigated behavioral characteristics of users with visual impairments and tested effect of factors regarding the layout of virtual environments (VEs). Various three-dimensional (3D) VEs were simulated with two different factors: number of objects and layout type (random, symmetric). Using a Novint Falcon haptic device, users with visual impairments were required to complete an object recognition task in 3D VEs with different levels of number of object and layout. The characteristics of their movements (speed, applied force, location, direction, etc.) were recorded, and participants evaluated perceived difficulty after they completed each trial. We analyzed their recorded movements and their rating on perceived difficulty. Results showed that 1) number of objects in 3D VE had significant impact on visually impaired users’ behavior; 2) different layout had not showed significant influence on their movement; 3) increased number of objects in 3D VE made the task more difficult; 4) visualized results implied that different users had significant different behavior preference in the same 3D VE. It is expected that the results of this study can improve behavioral understanding of users with visual impairments and guidance for assistive technology development for users with visual impairments. PY - 2013/// DO - 10.1007/978-3-642-39330-3_67 SP - 618-625 OP - PB - Springer Berlin Heidelberg SN - 9783642393297 9783642393303 UR - http://dx.doi.org/10.1007/978-3-642-39330-3_67 DB - Crossref ER - TY - CHAP TI - Use of Reference Frame in Haptic Virtual Environments: Implications for Users with Visual Impairments AU - Lee, Ja Young AU - Bahn, Sangwoo AU - Nam, Chang S. T2 - Human-Computer Interaction. Interaction Modalities and Techniques AB - Reference frame is key in explaining the relationship between two objects. This paper focused on the orientation parameter of a reference frame in use of projective spatial terms, and its use by visually impaired participants using a haptic device to explore a haptic virtual environment. A total of nine visually impaired participants between 12 and 17 years of age participated in this study. After exploring the 3D virtual environment with a haptic device, participants answered questions about the frame they had utilized. Overall results indicated that the participants used relative frame of reference slightly more than the intrinsic frame of reference. This inclination was especially clear when both the target object and the reference object were on the horizontal plane. Only when objects were on horizontal plane but intrinsically vertical to the reference object, the intrinsic frame of reference was preferred. We also found evidence that participants used a reflective subtype of the relative frame, and vertically aligned objects were easy to be perceived with the relative reference frame. We concluded that the virtual environment and haptic input had influence on the result by separating the user from the computer, only allowing one point of contact. Thus it would be possible to apply the result of this study to the development and assessment of assistive technology for people with visual impairment, especially in regard to how spatial information between the systems and the user is communicated. PY - 2013/// DO - 10.1007/978-3-642-39330-3_66 SP - 610-617 OP - PB - Springer Berlin Heidelberg SN - 9783642393297 9783642393303 UR - http://dx.doi.org/10.1007/978-3-642-39330-3_66 DB - Crossref ER - TY - CHAP TI - Assessing the Effectiveness of Vibrotactile Feedback on a 2D Navigation Task AU - Jeon, Wooram AU - Li, Yueqing AU - Bahn, Sangwoo AU - Nam, Chang S. T2 - Human-Computer Interaction. Interaction Modalities and Techniques AB - The effect of vibrotactile parameters were investigated on a 2D navigation task. Participants performed a simple navigation task reproducing directional information presented by a series of vibrotactile stimuli consisting of different levels of amplitude and frequency. Task completion time and degree of annoyance were measured. The results demonstrated that both frequency and amplitude had a significant effect on the responses. In addition, interaction effects between the two parameters were found on the responses. It was concluded that user performance and comfort are significantly affected by frequency and amplitude. The results give some insight into designing navigating information presented by vibrotactile display for visually impaired people. More studies with people with visual impairment and manipulation of other vibrotactile parameters are recommended to be applicable to the potential research. PY - 2013/// DO - 10.1007/978-3-642-39330-3_64 SP - 594-600 OP - PB - Springer Berlin Heidelberg SN - 9783642393297 9783642393303 UR - http://dx.doi.org/10.1007/978-3-642-39330-3_64 DB - Crossref ER - TY - CHAP TI - Influence of Haptic Feedback on a Pointing Task in a Haptically Enhanced 3D Virtual Environment AU - Corbett, Brendan AU - Yamaguchi, Takehiko AU - Liu, Shijing AU - Huang, Lixiao AU - Bahn, Sangwoo AU - Nam, Chang S. T2 - Human-Computer Interaction. Interaction Modalities and Techniques AB - To gain a better view of the value of haptic feedback, human performance and preference in a pointing style task in a three-dimensional virtual environment was explored. Vibration and haptic attractive force were selected as two simple cases of feedback, each with two levels. These types of feedback were compared to a no-feedback condition to better understand how human performance changes under these conditions. The study included 8 undergraduate students. A Novint Falcon haptic controller was used in a simulated three-dimensional virtual environment. Analysis was conducted on how each type of feedback effects the movement time (MT) of users. The results showed that vibration was perceived negatively and had a slight negative impact on performance. The haptic attractive force significantly improved performance and was strongly preferred by subjects. PY - 2013/// DO - 10.1007/978-3-642-39330-3_60 SP - 561-567 OP - PB - Springer Berlin Heidelberg SN - 9783642393297 9783642393303 UR - http://dx.doi.org/10.1007/978-3-642-39330-3_60 DB - Crossref ER - TY - JOUR TI - Characterizing the impact of mental disorders on HIV patient length of stay and total charges AU - Zhang, Shengfan AU - Payton, Fay Cobb AU - Ivy, Julie Simmons T2 - IIE Transactions on Healthcare Systems Engineering AB - There are over one million people in the United States living with HIV/AIDS, 20% of whom are undiagnosed, increasing the risk of transmission and the burden on the healthcare system. Those with comorbid diseases may be particularly vulnerable. This paper studies the impact of comorbidities, with a particular focus on mental disorders, on HIV patient outcomes as measured by patient length of stay (LOS) and total charges. Generalized linear models (gamma models) allowing heteroscedasticity are developed to characterize the effects of selected comorbidities on HIV patient outcomes in the adult 2006 National Inpatient Sample. Comorbid HIV patients experience different LOS and total charges. In particular, having mental disorders resulted in a decrease in both LOS (19%) and total charges (15%) for HIV patients. To characterize the role of individual mental disorders, principal component and cluster analyses on ICD-9 codes are used to study the impact of mental disorder, and eight conditions are found to be most strongly associated with HIV. Gamma models with these identified mental disorders as independent variables are then developed. The results have shown different effects on LOS and charges for each condition, and special attention should be given to those mental disorders (e.g., drug dependence) that increased LOS and charges when present. DA - 2013/7// PY - 2013/7// DO - 10.1080/19488300.2013.820238 VL - 3 IS - 3 SP - 139-146 J2 - IIE Transactions on Healthcare Systems Engineering LA - en OP - SN - 1948-8300 1948-8319 UR - http://dx.doi.org/10.1080/19488300.2013.820238 DB - Crossref ER - TY - JOUR TI - Pricing policies for substitutable products in a supply chain with Internet and traditional channels AU - Chen, Yun Chu AU - Fang, Shu-Cherng AU - Wen, Ue-Pyng T2 - European Journal of Operational Research AB - This study considers pricing policies in a supply chain with one manufacturer, who sells a product to an independent retailer and directly to consumers through an Internet channel. In addition to the manufacturer’s product, the retailer sells a substitute product produced by another manufacturer. Given the wholesale prices of the two substitute products, the manufacturer decides the retail price of the Internet channel, and the retailer decides the retail prices of the two substitute products. Both the manufacturer and the retailer choose their own decision variables to maximize their respective profits. This work formulates the price competition, using the settings of Nash and Stackelberg games, and derives the corresponding existence and uniqueness conditions for equilibrium solutions. A sensitivity analysis of an equilibrium solution is then conducted for the model parameters, and the profits are compared for two game settings. The findings show that improving brand loyalty is profitable for both of the manufacturer and retailer, and that an increased service value may alleviate the threat of the Internet channel for the retailer and increase the manufacturer’s profit. The study also derives some conditions under which the manufacturer and the retailer mutually prefer the Stackelberg game. Based on these results, this study proposes an appropriate cooperation strategy for the manufacturer and retailer. DA - 2013/2// PY - 2013/2// DO - 10.1016/j.ejor.2012.09.003 VL - 224 IS - 3 SP - 542-551 J2 - European Journal of Operational Research LA - en OP - SN - 0377-2217 UR - http://dx.doi.org/10.1016/j.ejor.2012.09.003 DB - Crossref KW - Pricing KW - Game theory KW - Supply chain management KW - Channel competition ER - TY - JOUR TI - Exact Computable Representation of Some Second-Order Cone Constrained Quadratic Programming Problems AU - Jin, Qingwei AU - Tian, Ye AU - Deng, Zhibin AU - Fang, Shu-Cherng AU - Xing, Wenxun T2 - Journal of the Operations Research Society of China AB - Solving the quadratically constrained quadratic programming (QCQP) problem is in general NP-hard. Only a few subclasses of the QCQP problem are known to be polynomial-time solvable. Recently, the QCQP problem with a nonconvex quadratic objective function over one ball and two parallel linear constraints is proven to have an exact computable representation, which reformulates the original problem as a linear semidefinite program with additional linear and second-order cone constraints. In this paper, we provide exact computable representations for some more subclasses of the QCQP problem, in particular, the subclass with one second-order cone constraint and two special linear constraints. DA - 2013/3// PY - 2013/3// DO - 10.1007/S40305-013-0009-8 VL - 1 IS - 1 SP - 107-134 J2 - J. Oper. Res. Soc. China LA - en OP - SN - 2194-668X 2194-6698 UR - http://dx.doi.org/10.1007/S40305-013-0009-8 DB - Crossref KW - Linear conic program KW - Semidefinite program KW - Nonconvex quadratically constrained quadratic program KW - Second-order cone ER - TY - CHAP TI - Reallocation of Resources to Preserve Relative Efficiencies: Inverse CCR Model AU - Lertworasirikul, Saowanee AU - Fang, S. C. T2 - The 19th International Conference on Industrial Engineering and Engineering Management PY - 2013/// DO - 10.1007/978-3-642-37270-4_48 SP - 497-508 OP - PB - Springer Berlin Heidelberg SN - 9783642372698 9783642372704 UR - http://dx.doi.org/10.1007/978-3-642-37270-4_48 DB - Crossref ER - TY - JOUR TI - A Dispatching Model for Server-to-Customer Systems That Balances Efficiency and Equity AU - McLay, Laura A. AU - Mayorga, Maria E. T2 - Manufacturing & Service Operations Management AB - The decision about which servers to dispatch to which customers is an important aspect of service systems. This decision is complicated when servers must be equitably—as well as efficiently—dispatched to customers. In this paper, we formulate a model for determining how to optimally dispatch distinguishable servers to prioritized customers given a set of equity constraints. These issues are examined through the lens of emergency medical service (EMS) dispatch, for which a Markov decision process model is developed that captures how to dispatch ambulances (servers) to prioritized patients (customers). It is assumed that customers arrive sequentially, with the priority and location of each customer becoming known upon arrival. Four types of equity constraints are considered—two of which reflect customer equity and two of which reflect server equity—all of which draw upon the decision analytic and social science literature to compare the effects of different notions of equity on the resulting dispatching policies. The Markov decision processes are formulated as equity-constrained linear programming models. A computational example is applied to an EMS system to compare the different equity models. DA - 2013/5// PY - 2013/5// DO - 10.1287/msom.1120.0411 VL - 15 IS - 2 SP - 205-220 J2 - M&SOM LA - en OP - SN - 1523-4614 1526-5498 UR - http://dx.doi.org/10.1287/msom.1120.0411 DB - Crossref KW - emergency medical services KW - server-to-customer systems KW - public health KW - equity KW - Markov decision processes KW - linear programming ER - TY - JOUR TI - Elicitation of Haptic User Interface Needs of People with Low Vision AU - Kim, Hyung Nam AU - Smith-Jackson, Tonya L. AU - Nam, Chang S. T2 - International Journal of Human-Computer Interaction AB - Various assistive technologies such as haptic technology are used to help people with visual impairments comprehend complex information. Yet there is likely to be a misconception that users with the same disability category share the same user interface needs; furthermore, the majority of the literature has been oriented toward total blindness rather than low vision, possibly leading to dissatisfaction with assistive technologies and discontinuation of its use by those with low vision. The aim of this article is to advance the understanding of the needs of those with low vision especially in relation to haptic-incorporated multimodal user interfaces. A scenario-based, participatory design approach was used to explore their needs. A total of 19 user needs were systematically documented under three categories: audition (n = 5), touch (n = 11), and vision (n = 3). This article focuses on qualitatively exploring their needs and theoretically interpreting the needs in the light of previous studies. DA - 2013/7/3/ PY - 2013/7/3/ DO - 10.1080/10447318.2012.722465 VL - 29 IS - 7 SP - 488-500 J2 - International Journal of Human-Computer Interaction LA - en OP - SN - 1044-7318 1532-7590 UR - http://dx.doi.org/10.1080/10447318.2012.722465 DB - Crossref ER - TY - CONF TI - Combined DES/SD simulaton model of breast cancer screening for older women: An overview AU - Tejada, J.J. AU - Diehl, K. AU - Ivy, J.S. AU - Wilson, J.R. AU - King, R.E. AU - Ballan, M.J. AU - Kay, M.G. AU - Yankaskas, B.C. AB - We develop a simulation modeling framework for evaluating the effectiveness of breast cancer screening policies for US women of age 65+. We introduce a two-phase simulation approach to modeling the main components in the breast cancer screening process. The first phase is a natural-history model of the incidence and progression of untreated breast cancer in randomly sampled individuals from the designated population. Combining discrete event simulation (DES) and system dynamics (SD) submodels, the second phase is a screening-and-treatment model that uses information about the genesis of breast cancer in the sampled individuals as generated by the natural-history model to estimate the benefits of different policies for screening the designated population and treating the affected women. Based on extensive simulation-based comparisons of alternative screening policies, we concluded that annual screening from age 65 to age 80 is the best policy for minimizing breast cancer deaths or for maximizing quality-adjusted life-years saved. C2 - 2013/// C3 - Proceedings of the 2013 Winter Simulation Conference - Simulation: Making Decisions in a Complex World, WSC 2013 DA - 2013/// DO - 10.1109/WSC.2013.6721406 SP - 41-53 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84894200756&partnerID=MN8TOARS ER - TY - JOUR TI - Investigating interventions for increasing colorectal cancer screening: Insights from a simulation model AU - Hosking, Michael AU - Roberts, Stephen AU - Uzsoy, Reha AU - Joseph, Talisa M. T2 - Socio-Economic Planning Sciences AB - We develop a discrete-event-continuous simulation model of colorectal cancer screening in North Carolina to examine the impact of six different interventions on the fraction of eligible patients receiving the clinically recommended screening. We find that demand side interventions alone are less effective than using only supply side interventions or a combination of both; the single most effective intervention is implementing a patient reminder system to reduce the number of no-show patients; and that all interventions studied are subject to significant diminishing returns. DA - 2013/6// PY - 2013/6// DO - 10.1016/j.seps.2012.10.001 VL - 47 IS - 2 SP - 142-155 J2 - Socio-Economic Planning Sciences LA - en OP - SN - 0038-0121 UR - http://dx.doi.org/10.1016/j.seps.2012.10.001 DB - Crossref KW - Simulation KW - Systems dynamics KW - Colorectal cancer KW - Cancer screening KW - Screening barriers KW - Cancer prevention policy ER - TY - JOUR TI - Query optimization in information integration AU - Chen, Dongfeng AU - Chirkova, Rada AU - Sadri, Fereidoon AU - Salo, Tiia J. T2 - Acta Informatica DA - 2013/4/9/ PY - 2013/4/9/ DO - 10.1007/S00236-013-0179-1 VL - 50 IS - 4 SP - 257-287 J2 - Acta Informatica LA - en OP - SN - 0001-5903 1432-0525 UR - http://dx.doi.org/10.1007/S00236-013-0179-1 DB - Crossref ER - TY - CHAP TI - Comparison of Enhanced Visual and Haptic Features in a Virtual Reality-Based Haptic Simulation AU - Clamann, Michael AU - Ma, Wenqi AU - Kaber, David B. T2 - Human-Computer Interaction. Interaction Modalities and Techniques AB - An experiment was conducted to compare the learning effects following motor skill training using three types of virtual reality simulations. Training and testing were presented using virtual reality (VR) and standardized forms of existing psychomotor tests, respectively. The VR training simulations included haptic, visual and a combination of haptic and visual assistance designed to accelerate training. A comparison of performance test results prior to and following training revealed conditions providing haptic assistance to yield lower scores related to fine motor skill training than the visual-only aiding condition. Similarly, training in the visual condition resulted in comparatively lower cognitive skill scores. The present investigation incorporating healthy subjects was designed as part of an ongoing research effort to provide insight on the design of VR simulations for rehabilitation of motor skills in patients with a history of mTBI. PY - 2013/// DO - 10.1007/978-3-642-39330-3_59 SP - 551-560 OP - PB - Springer Berlin Heidelberg SN - 9783642393297 9783642393303 UR - http://dx.doi.org/10.1007/978-3-642-39330-3_59 DB - Crossref ER - TY - JOUR TI - An integer programming approach for the view and index selection problem AU - Asgharzadeh Talebi, Zohreh AU - Chirkova, Rada AU - Fathi, Yahya T2 - Data & Knowledge Engineering AB - The view- and index-selection problem is a combinatorial optimization problem that arises in the context of on-line analytical processing (OLAP) in database-management systems. We propose an integer programming (IP) model for this problem and study the properties of the views and indexes that appear in the optimal solution for this model. We then use these properties to remove a number of variables and constraints from the corresponding IP model and obtain a model that is significantly smaller, yet its optimal solution is guaranteed to be optimal for the original problem. This allows us to solve realistic-size instances of the problem in reasonable time using commercial IP solvers. Subsequently, we propose heuristic strategies to further reduce the size of this IP model and dramatically reduce its execution time, although we no longer guarantee that the reduced IP model offers a globally optimal solution for the original problem. Finally, we carry out an extensive computational study to evaluate the effectiveness of these IP models for solving the OLAP view- and index-selection problem. DA - 2013/1// PY - 2013/1// DO - 10.1016/j.datak.2012.11.001 VL - 83 SP - 111-125 J2 - Data & Knowledge Engineering LA - en OP - SN - 0169-023X UR - http://dx.doi.org/10.1016/j.datak.2012.11.001 DB - Crossref KW - Business intelligence KW - Data warehouse and repository KW - OLAP KW - Materialized views KW - View and index selection KW - Integer programming KW - Heuristics ER - TY - CHAP TI - Two-Stage Stochastic View Selection for Data-Analysis Queries AU - Huang, Rong AU - Chirkova, Rada AU - Fathi, Yahya T2 - Advances in Intelligent Systems and Computing AB - We consider the problem of selecting an optimal set of views to answer a given collection of queries at the present time (stage 1) as well as several collections of queries in the future (stage 2), with a given probability of occurrence associated with each collection, so as to minimize the expected value of the corresponding query response time, while keeping the total size of the views within a given limit. We formulate this problem as a two-stage stochastic programming problem. We show that this model is equivalent to an integer programming (IP) model that can be solved via various commercial IP solvers. We also study the relationship between the queries and the views in this context and use this relationship to reduce the size of the corresponding IP model, hence increase the scalability of our proposed approach. PY - 2013/// DO - 10.1007/978-3-642-32741-4_11 SP - 115-123 OP - PB - Springer Berlin Heidelberg SN - 9783642327407 9783642327414 UR - http://dx.doi.org/10.1007/978-3-642-32741-4_11 DB - Crossref ER - TY - JOUR TI - Allocating job-shop manpower to minimize : Optimality criteria, search heuristics, and probabilistic quality metrics AU - Lobo, Benjamin J. AU - Hodgson, Thom J. AU - King, Russell E. AU - Thoney, Kristin A. AU - Wilson, James R. T2 - Computers & Operations Research AB - We address questions raised by Lobo et al. in 2012 regarding the NP-hard problem of finding an optimal allocation of workers to machine groups in a job shop so as to minimize Lmax, the maximum job lateness. Lobo et al. formulated a lower bound on Lmax given a worker allocation, and an algorithm to find an allocation yielding the smallest such lower bound. In this article we establish optimality criteria to verify that a given allocation corresponds to a schedule that yields the minimum value of Lmax. For situations in which the optimality criteria are not satisfied, we present the Heuristic Search Procedure (HSP), which sequentially invokes three distinct search heuristics, the Local Neighborhood Search Strategy (LNSS), Queuing Time Search Strategy 1 (QSS1), and Queuing Time Search Strategy 2 (QSS2), before delivering the best allocation encountered by LNSS, QSS1, and QSS2. HSP is designed to find allocations allowing a heuristic scheduler to generate schedules with a smaller value of Lmax than that achieved via the allocation yielding the final lower bound of Lobo et al. Comprehensive experimentation indicated that HSP delivered significant reductions in Lmax. We also estimate a probability distribution for evaluating the quality (closeness to optimality) of an allocation delivered by a heuristic search procedure such as HSP. This distribution permits assessing the user's confidence that a given allocation will enable the heuristic scheduler to generate its best possible schedule—i.e., the schedule with the heuristic scheduler's smallest achievable Lmax value. DA - 2013/10// PY - 2013/10// DO - 10.1016/J.COR.2013.02.008 VL - 40 IS - 10 SP - 2569-2584 J2 - Computers & Operations Research LA - en OP - SN - 0305-0548 UR - http://dx.doi.org/10.1016/J.COR.2013.02.008 DB - Crossref KW - Job shop scheduling KW - Dual resource constrained systems KW - Maximum lateness KW - Worker allocation ER - TY - JOUR TI - Teaching a Multidisciplinary Nanotechnology Laboratory Course to Undergraduate Students AU - Zhu, Yong AU - Tracy, Joseph B. AU - Dong, Jingyan AU - Jiang, Xiaoning AU - Jones, M. Gail AU - Childers, Gina T2 - Journal of Nano Education AB - Here we report our efforts to teach the first multidisciplinary undergraduate nanotechnology laboratory course in the College of Engineering at North Carolina State University (NCSU). The course was designed to provide undergraduate students with hands-on experience in nanoscience and nanotechnology. The theme of this laboratory course is the integration of nanotechnology with microsystem technology, i.e., bottom-up synthesis meeting top-down fabrication. This course consists of seven carefully designed lab modules that bridge the major “pillars” of nanotechnology– nanomaterials, nanofabrication, nanoscale characterization, and nanodevices. Final projects provide students opportunities to conduct nanotechnology research through problem-based learning and to improve their communication and presentation skills for educating the public about nanotechnology. A pedagogical approach that features problem-based learning, group learning, visual/tactile assistance and interdisciplinary interaction was employed during the offering of this course. DA - 2013/6/1/ PY - 2013/6/1/ DO - 10.1166/jne.2013.1032 VL - 5 IS - 1 SP - 17-26 J2 - J Nano Educ LA - en OP - SN - 1936-7449 UR - http://dx.doi.org/10.1166/jne.2013.1032 DB - Crossref ER - TY - JOUR TI - Prioritization strategies for patient evacuations AU - Childers, Ashley Kay AU - Mayorga, Maria E. AU - Taaffe, Kevin M. T2 - Health Care Management Science DA - 2013/5/11/ PY - 2013/5/11/ DO - 10.1007/s10729-013-9236-0 VL - 17 IS - 1 SP - 77-87 J2 - Health Care Manag Sci LA - en OP - SN - 1386-9620 1572-9389 UR - http://dx.doi.org/10.1007/s10729-013-9236-0 DB - Crossref KW - Hospitals KW - Evacuation KW - Prioritization KW - Policy-making ER - TY - JOUR TI - A Simulation Optimization Approach to Epidemic Forecasting T2 - PLoS ONE AB - Reliable forecasts of influenza can aid in the control of both seasonal and pandemic outbreaks. We introduce a simulation optimization (SIMOP) approach for forecasting the influenza epidemic curve. This study represents the final step of a project aimed at using a combination of simulation, classification, statistical and optimization techniques to forecast the epidemic curve and infer underlying model parameters during an influenza outbreak. The SIMOP procedure combines an individual-based model and the Nelder-Mead simplex optimization method. The method is used to forecast epidemics simulated over synthetic social networks representing Montgomery County in Virginia, Miami, Seattle and surrounding metropolitan regions. The results are presented for the first four weeks. Depending on the synthetic network, the peak time could be predicted within a 95% CI as early as seven weeks before the actual peak. The peak infected and total infected were also accurately forecasted for Montgomery County in Virginia within the forecasting period. Forecasting of the epidemic curve for both seasonal and pandemic influenza outbreaks is a complex problem, however this is a preliminary step and the results suggest that more can be achieved in this area. DA - 2013/6/27/ PY - 2013/6/27/ DO - 10.1371/journal.pone.0067164 UR - http://dx.doi.org/10.1371/journal.pone.0067164 ER - TY - JOUR TI - Controlled release of metronidazole from composite poly-ε-caprolactone/alginate (PCL/alginate) rings for dental implants AU - Lan, Shih-Feng AU - Kehinde, Timilehin AU - Zhang, Xiangming AU - Khajotia, Sharukh AU - Schmidtke, David W. AU - Starly, Binil T2 - Dental Materials AB - Dental implants provide support for dental crowns and bridges by serving as abutments for the replacement of missing teeth. To prevent bacterial accumulation and growth at the site of implantation, solutions such as systemic antibiotics and localized delivery of bactericidal agents are often employed. The objective of this study was to demonstrate a novel method of controlled localized delivery of antibacterial agents to an implant site using a biodegradable custom fabricated ring. The study involved incorporating a model antibacterial agent (metronidazole) into custom designed poly-ε-caprolactone/alginate (PCL/alginate) composite rings to produce the intended controlled release profile. The rings can be designed to fit around the body of any root form dental implants of various diameters, shapes and sizes. In vitro release studies indicate that pure (100%) alginate rings exhibited an expected burst release of metronidazole in the first few hours, whereas Alginate/PCL composite rings produced a medium burst release followed by a sustained release for a period greater than 4 weeks. By varying the PCL/alginate weight ratios, we have shown that we can control the amount of antibacterial agents released to provide the minimal inhibitory concentration (MIC) needed for adequate protection. The fabricated composite rings have achieved a 50% antibacterial agent release profile over the first 48 h and the remaining amount slowly released over the remainder of the study period. The PCL/alginate agent release characteristic fits the Ritger–Peppas model indicating a diffusion-based mechanism during the 30-day study period. The developed system demonstrates a controllable drug release profile and the potential for the ring to inhibit bacterial biofilm growth for the prevention of diseases such as peri-implantitis resulting from bacterial infection at the implant site. DA - 2013/6// PY - 2013/6// DO - 10.1016/j.dental.2013.03.014 VL - 29 IS - 6 SP - 656-665 J2 - Dental Materials LA - en OP - SN - 0109-5641 UR - http://dx.doi.org/10.1016/j.dental.2013.03.014 DB - Crossref KW - Localized drug delivery KW - Dental implants KW - Poly-epsilon-caprolactone KW - Alginate KW - Solvent casting KW - Metronidazole ER - TY - JOUR TI - Regenerative medicine manufacturing AU - Shirwaiker, R.A. AU - Tan, Z. AU - Cohen, P.H. T2 - Industrial Engineer DA - 2013/// PY - 2013/// VL - 45 IS - 8 SP - 32-37 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84882976891&partnerID=MN8TOARS ER - TY - CONF TI - Determining optimal current intensity and duration for electrically activated silver-based prophylactic hip implant prototype design AU - Tan, Z. AU - Shirwaiker, Rohan AU - Orndoff, P.E. AB - Infections associated with medical prostheses result in notable morbidity, and traditional osteomyelitis treatments are often accompanied by high risk and cost. The probability of prosthetic joint infections is 1–2.5 % for primary hip or knee replacements and 2.1–5.8 % for revision surgeries, and the cost of treating such an infection is estimated to be over $50,000 per episode. [1] While the potential benefits of silver surfaces stimulated by low intensity direct current (LIDC) have been discussed in literature, we have recently utilized that concept in the actual design of prophylactic indwelling residual hardware prostheses for the very first time. [2–4] A modular titanium hip stem coated with silver at the anode (and titanium as the cathode) and activated by a watch battery encapsulated within the two electrode modules (Figure 1) will result in oligodynamic iontophoresis (OI) in the soft tissue surrounding the implant which is prone to infections. Preliminary in vitro and in vivo results have demonstrated the potency of silver-based OI as an effective local antibacterial therapy in osteomyelitis treatment with advantages over various antibiotics. However, the main challenge here is achieving the antibacterial potency while minimizing any potential toxic effects on local tissues. [4] C2 - 2013/// C3 - ASME 2013 Summer Bioengineering Conference, SBC 2013 DA - 2013/// DO - 10.1115/SBC2013-14141 VL - 1 B UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84894644307&partnerID=MN8TOARS ER - TY - JOUR TI - Disaster Response Planning in the Private Sector and the Role of Operations Research AU - Ergun, Özlem AU - Karakus, Gonca AU - Kerl, Paul AU - Keskinocak, Pinar AU - Swann, Julie L. AU - Villarreal, Monica AU - Drake, Matthew J. AB - Organizations in the private sector such as The Home Depot (THD), Lowe’s, Wal-Mart, and Waffle House have become actively involved in the disaster response operations in their communities. With the objective of becoming effective first responders, these companies have integrated a disaster response planning process to their business operations. We introduce the disaster response planning process implemented by THD after their experience with Hurricane Andrew. We describe in detail the components of this process, each of which requires different decisions to be made at different levels of the organization. We discuss how operations research methodologies could be used to assist decision makers in the disaster response setting, and we propose an optimization model for each of two of the decisions commonly found in a disaster response planning process: advance purchasing and inventory allocation. In addition to these exact methods, we suggest a scenario-based approach, which is more intuitive and allows to incorporate objectives that are harder to model, such as the relative value of the supplies. DA - 2013/// PY - 2013/// DO - 10.1007/978-1-4614-5278-2_9 SP - 197-217 ER - TY - JOUR TI - Improving Humanitarian Operations through Technology-enabled Collaboration AB - Humanitarian supply chains involve many different entities, such as government, military, private, and non‐governmental organizations and individuals. Well‐coordinated interactions between entities can lead to synergies and improved humanitarian outcomes. Information technology (IT) tools can help facilitate collaboration, but cost and other barriers have limited their use. We document the use of an IT tool to improve last‐mile supply distribution and data management in one of many camps for internally displaced persons after the January 2010 earthquake in Haiti, and we describe other current uses of technology in camp management. Motivated by these examples and the interest among humanitarian organizations in expanding the use of such tools to facilitate coordination, we introduce a cooperative game theory model and explore insights about the conditions under which multi‐agency coordination is feasible and desirable. We also outline an agenda for future research in the area of technology‐enabled collaboration in the humanitarian sector. DA - 2013/// PY - 2013/// DO - 10.1111/poms.12107 KW - humanitarian operations KW - coordination KW - cooperative game theory KW - cost-allocation mechanisms ER - TY - JOUR TI - Humanitarian Logistics: Advanced Purchasing and Pre-Positioning of Relief Items AB - Unfortunately, the world has experienced frequent disasters as well as mega-disasters in the last decade. The challenges faced during the relief efforts to those disasters called for improvements in the area of humanitarian logistics. In this chapter, first we present introductory knowledge on disaster management and humanitarian logistics. The complexities and inefficiencies in the current relief response practice are indicated. To improve the disaster response, we investigate the options of advance purchasing and pre-positioning of the relief items through applied projects performed for different humanitarian organizations. DA - 2013/// PY - 2013/// DO - 10.1007/978-1-4419-6132-7_18 ER - TY - JOUR TI - Allocating Scarce Healthcare Resources in Developing Countries: A Case for Malaria Prevention AU - Griffin, Jacqueline AU - Keskinocak, Pinar AU - Swann, Julie AB - Decisions regarding the best use of scarce health resources become increasingly complex in developing countries due to high disease incidence, poor healthcare system infrastructure, and other societal factors. We develop a resource allocation model for the design of an Indoor Residual Spraying (IRS) program for malaria prevention in developing countries. Due to the seasonal nature of malaria risk factors, the model addresses dynamic resource allocation based on the risk characteristics. Using the model as a framework, a decision support tool for IRS operations is constructed. With a small numerical example we demonstrate the value of the tool for evaluating complexities and tradeoffs in the allocation of limited resources for an IRS program and the impact of heuristic decision making. DA - 2013/// PY - 2013/// DO - 10.1007/978-1-4614-5885-2_20 SP - 511-532 ER - TY - JOUR TI - System factors to explain H1N1 state vaccination rates for adults in US emergency response to pandemic. AU - Davila-Payan, C. AU - Swann, J. AU - Wortley, P.M. AU - Vaccine AB - During the 2009-2010 H1N1 pandemic, vaccine in short supply was allocated to states pro rata by population, yet the vaccination rates of adults differed by state. States also differed in their campaign processes and decisions. Analyzing the campaign provides an opportunity to identify specific approaches that may result in higher vaccine uptake in a future event of this nature.To determine supply chain and system factors associated with higher state H1N1 vaccination coverage for adults in a system where vaccine was in short supply.Regression analysis of factors predicting state-specific H1N1 vaccination coverage in adults. Independent variables included state campaign information, demographics, preventive or health-seeking behavior, preparedness funding, providers, state characteristics, and H1N1-specific state data.The best model explained the variation in state-specific adult vaccination coverage with an adjusted R-squared of 0.76. We found that higher H1N1 coverage of adults is associated with program aspects including shorter lead-times (i.e., the number of days between when doses were allocated to a state and were shipped, including the time for states to order the doses) and less vaccine directed to specialist locations. Higher vaccination coverage is also positively associated with the maximum number of ship-to locations, past seasonal influenza vaccination coverage, the percentage of women with a Pap smear, the percentage of the population that is Hispanic, and negatively associated with a long duration of the epidemic peak.Long lead-times may be a function of system structure or of efficiency and may suggest monitoring or redesign of distribution processes. Sending vaccine to sites with broad access could be useful when covering a general population. Existing infrastructure may be reflected in the maximum number of ship-to locations, so strengthening routine influenza vaccination programs may help during emergency vaccinations also. Future research could continue to inform program decisions. DA - 2013/5// PY - 2013/5// DO - 10.1016/j.vaccine.2013.05.069 UR - http://europepmc.org/abstract/med/23727421 KW - Pandemic KW - Coverage KW - State-specific KW - Factors KW - Estimates KW - Adults ER - TY - JOUR TI - Evaluation of Telemedicine for Screening of Diabetic Retinopathy in the Veterans Health Administration. AU - Kirkizlar, E. AU - Serban, N. AU - Sisson, J.A. AU - Swann, J.L. AU - Barnes, C.S. AU - Williams, M.D. AU - Ophthalmology AB - Objective To explore the cost-effectiveness of telemedicine for the screening of diabetic retinopathy (DR) and identify changes within the demographics of a patient population after telemedicine implementation. Design A retrospective medical chart review (cohort study) was conducted. Participants A total of 900 type 1 and type 2 diabetic patients enrolled in a medical system with a telemedicine screening program for DR. Methods The cost-effectiveness of the DR telemedicine program was determined by using a finite-horizon, discrete time, discounted Markov decision process model populated by parameters and testing frequency obtained from patient records. The model estimated the progression of DR and determined average quality-adjusted life years (QALYs) saved and average additional cost incurred by the telemedicine screening program. Main Outcome Measures Diabetic retinopathy, macular edema, blindness, and associated QALYs. Results The results indicate that telemedicine screening is cost-effective for DR under most conditions. On average, it is cost-effective for patient populations of >3500, patients aged <80 years, and all racial groups. Observable trends were identified in the screening population since the implementation of telemedicine screening: the number of known DR cases has increased, the overall age of patients receiving screenings has decreased, the percentage of nonwhites receiving screenings has increased, the average number of miles traveled by a patient to receive a screening has decreased, and the teleretinal screening participation is increasing. Conclusions The current teleretinal screening program is effective in terms of being cost-effective and increasing population reach. Future screening policies should give consideration to the age of patients receiving screenings and the system's patient pool size because our results indicate it is not cost-effective to screen patients aged older than 80 years or in populations with <3500 patients. Financial Disclosure(s) The author(s) have no proprietary or commercial interest in any materials discussed in this article. To explore the cost-effectiveness of telemedicine for the screening of diabetic retinopathy (DR) and identify changes within the demographics of a patient population after telemedicine implementation. A retrospective medical chart review (cohort study) was conducted. A total of 900 type 1 and type 2 diabetic patients enrolled in a medical system with a telemedicine screening program for DR. The cost-effectiveness of the DR telemedicine program was determined by using a finite-horizon, discrete time, discounted Markov decision process model populated by parameters and testing frequency obtained from patient records. The model estimated the progression of DR and determined average quality-adjusted life years (QALYs) saved and average additional cost incurred by the telemedicine screening program. Diabetic retinopathy, macular edema, blindness, and associated QALYs. The results indicate that telemedicine screening is cost-effective for DR under most conditions. On average, it is cost-effective for patient populations of >3500, patients aged <80 years, and all racial groups. Observable trends were identified in the screening population since the implementation of telemedicine screening: the number of known DR cases has increased, the overall age of patients receiving screenings has decreased, the percentage of nonwhites receiving screenings has increased, the average number of miles traveled by a patient to receive a screening has decreased, and the teleretinal screening participation is increasing. The current teleretinal screening program is effective in terms of being cost-effective and increasing population reach. Future screening policies should give consideration to the age of patients receiving screenings and the system's patient pool size because our results indicate it is not cost-effective to screen patients aged older than 80 years or in populations with <3500 patients. DA - 2013/9// PY - 2013/9// DO - 10.1016/j.ophtha.2013.06.029 UR - http://europepmc.org/abstract/med/24084501 ER - TY - BOOK TI - Simulation Modeling with SIMIO: A Workbook AU - Joines, J.A. AU - Roberts, S.D. DA - 2013/// PY - 2013/// ET - 3rd PB - Simio LLC Sewickley, PA ER - TY - JOUR TI - Effect of aging on inter-joint synergies during machine-paced assembly tasks AU - Xu, Xu AU - Qin, Jin AU - Catena, Robert D. AU - Faber, Gert S. AU - Lin, Jia-Hua T2 - EXPERIMENTAL BRAIN RESEARCH DA - 2013/11// PY - 2013/11// DO - 10.1007/s00221-013-3688-9 VL - 231 IS - 2 SP - 249-256 SN - 1432-1106 KW - Upper extremity movement KW - Motor coordination KW - Uncontrolled manifold (UCM) KW - Redundancy ER - TY - JOUR TI - The error of L5/S1 joint moment calculation in a body-centered non-inertial reference frame when the fictitious force is ignored AU - Xu, Xu AU - Faber, Gert S. AU - Kingma, Idsart AU - Chang, Chien-Chi AU - Hsiang, Simon M. T2 - JOURNAL OF BIOMECHANICS AB - In ergonomics studies, linked segment models are commonly used for estimating dynamic L5/S1 joint moments during lifting tasks. The kinematics data input to these models are with respect to an arbitrary stationary reference frame. However, a body-centered reference frame, which is defined using the position and the orientation of human body segments, is sometimes used to conveniently identify the location of the load relative to the body. When a body-centered reference frame is moving with the body, it is a non-inertial reference frame and fictitious force exists. Directly applying a linked segment model to the kinematics data with respect to a body-centered non-inertial reference frame will ignore the effect of this fictitious force and introduce errors during L5/S1 moment estimation. In the current study, various lifting tasks were performed in the laboratory environment. The L5/S1 joint moments during the lifting tasks were calculated by a linked segment model with respect to a stationary reference frame and to a body-centered non-inertial reference frame. The results indicate that applying a linked segment model with respect to a body-centered non-inertial reference frame will result in overestimating the peak L5/S1 joint moments of the coronal plane, sagittal plane, and transverse plane during lifting tasks by 78%, 2%, and 59% on average, respectively. The instant when the peak moment occurred was delayed by 0.13, 0.03, and 0.09 s on average, correspondingly for the three planes. The root-mean-square errors of the L5/S1 joint moment for the three planes are 21 Nm, 19 Nm, and 9 Nm, correspondingly. DA - 2013/7/26/ PY - 2013/7/26/ DO - 10.1016/j.jbiomech.2013.05.012 VL - 46 IS - 11 SP - 1943-1947 SN - 0021-9290 KW - Lifting KW - Linked segment model KW - Centrifugal force KW - Coriolis force ER - TY - JOUR TI - Shoulder joint loading and posture during medicine cart pushing task AU - Xu, Xu AU - Lin, J. H. AU - Boyer, J. T2 - Journal of Occupational and Environmental Hygiene AB - Excessive physical loads and awkward shoulder postures during pushing and pulling are risk factors for shoulder pain. Pushing a medicine cart is a major component of a work shift for nurses and medical assistants in hospitals and other health care facilities. A laboratory experiment was conducted to examine the effects of common factors (e.g., lane congestion, cart load stability, floor surface friction) on shoulder joint moment and shoulder elevation angle of participants during cart pushing. Participants pushed a medicine cart on straight tracks and turning around right-angle corners. Peak shoulder joint moments reached 25.1 Nm, 20.3 Nm, and 26.8 Nm for initial, transition, and turning phases of the pushing tasks, indicating that shoulder joint loading while pushing a medical cart is comparable to levels previously reported from heavy manual activities encountered in industry (e.g., garbage collection). Also, except for user experience, all other main study factors, including congestion level, cart load stability, location of transition strip, shoulder tendency, surface friction, and handedness, significantly influenced shoulder joint moment and shoulder elevation angle. The findings provide a better understanding of shoulder exposures associated with medicine cart operations and may be helpful in designing and optimizing the physical environment where medicine carts are used. DA - 2013/// PY - 2013/// DO - 10.1080/15459624.2013.803417 VL - 10 IS - 8 SP - 446–454 ER - TY - CONF TI - Virtual exertions: Physical interactions in a virtual reality CAVE for simulating forceful tasks AU - Radwin R. G., Chen AU - K. B., Ponto AU - K., AU - Tredinnick, R. D. C2 - 2013/// C3 - International Annual Meeting of the Human Factors and Ergonomics Society DA - 2013/// ER - TY - JOUR TI - Touch screen performance by individuals with and without motor control disabilities AU - Chen, Karen B. AU - Savage, Anne B. AU - Chourasia, Amrish O. AU - Wiegmann, Douglas A. AU - Sesto, Mary E. T2 - APPLIED ERGONOMICS AB - Touch technology is becoming more prevalent as functionality improves and cost decreases. Therefore, it is important that this technology is accessible to users with diverse abilities. The objective of this study was to investigate the effects of button and gap size on performance by individuals with varied motor abilities. Participants with (n = 38) and without (n = 15) a motor control disability completed a digit entry task. Button size ranged from 10 to 30 mm and gap size was either 1 or 3 mm. Results indicated that as button size increased, there was a decrease in misses, errors, and time to complete tasks. Performance for the non-disabled group plateaued at button size 20 mm, with minimal, if any gains observed with larger button sizes. In comparison, the disabled group's performance continued to improve as button size increased. Gap size did not affect user performance. These results may help to improve accessibility of touch technology. DA - 2013/3// PY - 2013/3// DO - 10.1016/j.apergo.2012.08.004 VL - 44 IS - 2 SP - 297-302 SN - 1872-9126 KW - Touch screen KW - Performance KW - Disability ER - TY - JOUR TI - Effect of sitting orientation on touchscreen performance, touch characteristics, user preference, and workload AU - Chourasia, A. O. Wiegmann AU - A., Chen D. AU - K., B. AU - Sesto, M.E. T2 - IIE Transactions on Occupational Ergonomics and Human Factors AB - OCCUPATIONAL APPLICATIONS Sitting in a parallel orientation in front of a touch screen (requiring twisting of the torso) was found to cause a decrement in touchscreen performance (36%–48%). However, the adverse effect of sitting orientation on performance could be ameliorated by interface design, most notably by using button sizes greater than 20×20 mm. Larger button sizes also benefit individuals with upper extremity motor control disabilities, and this information could be used to incorporate universal design in touchscreen interfaces. Larger button sizes also help in reducing the force-time integral during button activation. Touchscreens are widely used in occupational settings, such as retail, restaurants, and health care. The touchscreen performance findings from this study are applicable to touchscreen interface design for users with and without upper extremity motor control disabilities, and the touch characteristics findings are useful for ergonomists quantifying forces involved in touchscreen operation. TECHNICAL ABSTRACT Background: Touchscreens can be used in stand-alone kiosks, embedded in larger structures, such as walls, or arranged in multi-display configurations (e.g., a control station). As a result, users may not always be positioned in front of the screen and may instead operate it in a variety of orientations. Previous touchscreen research has not considered the effect of user sitting orientation on touchscreen performance, such as in terms of the number of errors (incorrect button activation), misses (touch that does not result in button activation), task completion time, and touch characteristics (e.g., force, dwell time [the time the button was pressed], and force-time integral). Purpose: This study evaluates the effect of sitting orientation on performance and touch characteristics during a digit entry task among individuals with and without motor control disabilities, including wheelchair users and non-users. Methods: Participants with (n = 21) and without (n = 21) upper extremity motor control disabilities (+MCD and −MCD, respectively) completed a four-digit entry task on a touchscreen in both front and parallel orientations to the touchscreen. Button sizes of 10×10 to 30×30 mm (5-mm increments) and two button gaps (3 or 5 mm) were used. Results: Accuracy was adversely affected, with errors (36%) and misses (48%) greater in the parallel orientation. Dwell time (12%) and force-time integral (21%) were also greater in the parallel orientation than in the front orientation. Larger button sizes (≥20 mm) lowered misses, errors, force-time integrals, and dwell times for both orientations. The +MCD group had a greater percentage of trials with misses (150%) and longer dwell times (66%) than the −MCD group, but in general, similar trends in performance and touch characteristics were observed for both groups across button sizes, button gaps, and sitting orientation. Conclusions: Decrements in touchscreen performance occurred in the parallel orientation compared to the front orientation. In addition, greater forces were exerted and greater workload was reported in the parallel orientation than in the front orientation. However, performance may be improved by using larger button sizes (≥20×20 mm). This may be especially important in critical touchscreen activities. DA - 2013/// PY - 2013/// DO - 10.1080/21577323.2013.847873 VL - 1 IS - 4 SP - 235–245 ER - TY - JOUR TI - Effect of Sitting or Standing on Touch Screen Performance and Touch Characteristics AU - Chourasia, Amrish O. AU - Wiegmann, Douglas A. AU - Chen, Karen B. AU - Irwin, Curtis B. AU - Sesto, Mary E. T2 - HUMAN FACTORS AB - Objective: The aim of this study was to evaluate the effect of sitting and standing on performance and touch characteristics during a digit entry touch screen task in individuals with and without motor-control disabilities. Background: Previously, researchers of touch screen design have not considered the effect of posture (sitting vs. standing) on touch screen performance (accuracy and timing) and touch characteristics (force and impulse). Method: Participants with motor-control disabilities ( n = 15) and without ( n = 15) completed a four-digit touch screen number entry task in both sitting and standing postures. Button sizes varied from 10 mm to 30 mm (5-mm increments), and button gap was 3 mm or 5 mm. Results: Participants had more misses and took longer to complete the task during standing for smaller button sizes (<20 mm). At larger button sizes, performance was similar for both sitting and standing. In general, misses, time to complete task, and touch characteristics were increased for standing. Although disability affected performance (misses and timing), similar trends were observed for both groups across posture and button size. Conclusion: Standing affects performance at smaller button sizes (<20 mm). For participants with and without motor-control disabilities, standing led to greater exerted force and impulse. Application: Along with interface design considerations, environmental conditions should also be considered to improve touch screen accessibility and usability. DA - 2013/8// PY - 2013/8// DO - 10.1177/0018720812470843 VL - 55 IS - 4 SP - 789-802 SN - 1547-8181 KW - performance KW - workload KW - force KW - disability KW - touch screen ER - TY - CONF TI - Brain-computer interface supported collaborative work: Implications for rehabilitation AU - nam, AU - Lee, J. AU - Bahn, S. AB - Working together and collaborating in a group can provide greater benefits for people with severe motor disability. However, it is still not clear how collaboration should be supported by BCI systems. The present study explored BCI-supported collaborative work by investigating differences in performance and brain activity between when a pair of users performs a task jointly with each other and when they do alone only through means of their brain activity. We found differences in performance and brain activity between different work conditions. The results of this research should provide fundamental knowledge of BCI-supported cooperative work. C2 - 2013/// C3 - 2013 35th annual international conference of the ieee engineering in medicine and biology society (embc) DA - 2013/// DO - 10.1109/embc.2013.6609489 SP - 269–272 ER - TY - CONF TI - Real-time traffic congestion management and deadlock avoidance for vehicular ad hoc networks AU - Hussain, S. R. AU - Odeh, A. AU - Shivakumar, A. AU - Chauhan, S. AU - Harfoush, K. AB - Traffic congestion is common in heavily populated cities. In this paper, we introduce a novel protocol to guide vehicles to their destinations while managing congestion and avoiding deadlock situations in urban city grids. The protocol relies on vehicle-to-infrastructure (V2I) communication, infrastructure-to-infrastructure (I2I) communication as well as GPS information to disseminate congestion information to city grid intersections. Our proposal pro-actively aims at avoiding congestion scenarios and reacts to arising congestion in case it happens due to unpredictable events such as collisions. Simulation results reveal that vehicles enjoy reduced travel times even during rush hours and in the presence of collisions. C2 - 2013/// C3 - 2013 10th International Conference on High Capacity Optical Networks and Enabling Technologies (HONET-CNS) DA - 2013/// DO - 10.1109/honet.2013.6729791 SP - 223-227 ER - TY - JOUR TI - Mitigating Biases in Time-to-Contact Judgments with Cockpit Displays of Traffic Information AU - Pankok, Carl, Jr. AU - Kaber, David B. T2 - 2013 IEEE INTERNATIONAL CONFERENCE ON SYSTEMS, MAN, AND CYBERNETICS (SMC 2013) AB - A flight simulation experiment was conducted to assess cockpit automation for mitigating the effects of a distance bias in time-to-contact judgments on converging intruders. Six formats of a prototype cockpit display of traffic information were tested, including all combinations of intruder icon (perceptual cue) format (baseline/conventional, colored, blinking) and a data tag with velocity information (present, absent). Results revealed displays with colored or blinking cues produced greater accuracy in pilot selection of intruders posing the greatest risk and lower response times than for conventional displays not presenting such cues. The addition of the velocity data tag to icons had no effect on intruder selection accuracy but was associated with lower response times. It was concluded that both the perceptual cue format and velocity data tags support superior performance in time-to-contact judgments as compared with conventional displays. DA - 2013/// PY - 2013/// DO - 10.1109/smc.2013.721 SP - 4231-4236 SN - 1062-922X KW - cockpit automation KW - aircraft pilot performance KW - human factors in display design ER - TY - JOUR TI - Evaluation of a Virtual Reality and Haptic Simulation of a Block Design Test AU - Clamann, Michael AU - Ma, Wenqi AU - Kaber, David B. T2 - 2013 IEEE INTERNATIONAL CONFERENCE ON SYSTEMS, MAN, AND CYBERNETICS (SMC 2013) AB - The objective of this research was to develop a computer-based system for psychomotor skill assessment and training. The focus was on virtual reality (VR) simulation of an established pattern assembly task incorporating a haptic interface. A prototype VR and haptic-based system was developed to replicate established testing protocols, facilitate automated test scoring, and produce quantitative test output. The prototype was also compared to a native version of the test. Participants completed multiple training trials of the VR or native tests. Training effects were measured by comparing performance on objective baseline and post-tests administered before and after training, respectively. Results revealed training in either the VR or the native versions of the task to produce significant (p<;0.0001) performance increases from baseline, but neither version resulted in significant improvements over the other. The VR-haptic simulation was found to represent a viable psychomotor test and training method. DA - 2013/// PY - 2013/// DO - 10.1109/smc.2013.155 SP - 882-887 SN - 1062-922X KW - haptic interfaces KW - virtual reality KW - psychomotor test ER - TY - JOUR TI - Assessing Goal-Directed Three-Dimensional Movements in a Virtual Reality Block Design Task AU - Jeon, Wooram AU - Clamann, Michael AU - Kaber, David B. AU - Currie, Nancy J. T2 - 2013 IEEE INTERNATIONAL CONFERENCE ON SYSTEMS, MAN, AND CYBERNETICS (SMC 2013) AB - This study investigated three-dimensional (3D) goal-directed movements in a virtual reality (VR) simulation of a standardized psychomotor control task. Movement trajectories were collected from 22 subjects and parsed based on an existing two-phase model of motor control including ballistic and correction phases. Kinematic measures were also acquired to provide further insight into motor skill learning. Results revealed kinematic measures of total numbers of sub movements and numbers of sub movements in the correction phase to be significantly correlated with psychomotor task scores. A predictive model applied to the 3D movements revealed the correction phase movements to be more predictive of psychomotor performance than the ballistic phase. Findings indicate a greater degree of fine motor skill was required for performance of the psychomotor control task. This research supports the use of high resolution kinematic measures as reliable predictors of psychomotor task performance. DA - 2013/// PY - 2013/// DO - 10.1109/smc.2013.637 SP - 3739-3744 SN - 1062-922X KW - Virtual reality KW - submovement structure KW - cursor trajectory KW - block design task KW - motor learning ER - TY - JOUR TI - Locating Traffic Sensors on a Highway Network Models and Algorithms AU - Sayyady, Fatemeh AU - Fathi, Yahya AU - List, George F. AU - Stone, John R. T2 - TRANSPORTATION RESEARCH RECORD AB - This paper considers the problem of finding optimal sensor locations on a traffic network with the goal of characterizing system use overall. The problem is studied for two practical scenarios. In the first scenario, it is assumed that there is a given number of sensors (p) to be located on the highway network. In this context, the problem is to find a collection of p locations among a given collection of candidate locations. In the second scenario, it is assumed that there is a cost (c i ) associated with installing a sensor at each candidate location i and a total budget b. In this context, the problem is to find a collection of locations that provide the best possible characterization given the budget constraint. A metric is proposed for evaluating a potential solution, and then appropriate mathematical models are proposed for solving the problem for each scenario. It is shown that the budget-constrained problem is an extension of the well-known p-median problem. A new Lagrangian heuristic algorithm is presented for solving large instances of this problem when a budget constraint is imposed. A comprehensive computational experiment is used to demonstrate that the Lagrangian heuristic algorithm provides solutions for large-scale networks within reasonable execution times. Examples are based on locating weigh-in-motion sensors on a large-scale highway network. DA - 2013/// PY - 2013/// DO - 10.3141/2339-04 IS - 2339 SP - 30-38 SN - 2169-4052 ER - TY - JOUR TI - Testing and Validation of a Psychophysically Defined Metric of Display Clutter AU - Kaber, David AU - Kaufmann, Karl AU - Alexander, Amy L. AU - Kim, Sang-Hwan AU - Naylor, James T. AU - Prinzel, Lawrence J., III AU - Pankok, Carl, Jr. AU - Gil, Guk-Ho T2 - JOURNAL OF AEROSPACE INFORMATION SYSTEMS AB - Combinations of cockpit display features may lead to increased pilot perceptions of clutter. This research sought to capture pilot perceptions of display clutter associated with primary flight display features during a vertical takeoff and landing scenario and to validate a multidimensional measure of clutter previously developed for a fixed-wing environment. Sixteen active fixed-wing pilots were recruited for the study that used a simulator configured as a vertical takeoff and landing aircraft. A factor analysis was used to reduce the number of subdimensions of the clutter measure based on previous ratings data. The simplified measure revealed an increase in the number of active display features to cause an increase in perceived clutter. Displays including synthetic vision system features were perceived as significantly more cluttered than those without. Although a tunnel (highway in the sky) feature also contributed to clutter, pilots achieved higher navigation system failure detection rates when the feature was active. Significant positive correlations were found between perceived clutter and visual display properties but not between perceived clutter and performance. Although pilots rated some displays as being highly cluttered, the increased information aided navigation failure detection. Overall, the clutter measure was found to have validity and sensitivity for application across diverse flight domains. DA - 2013/8// PY - 2013/8// DO - 10.2514/1.i010048 VL - 10 IS - 8 SP - 359-368 SN - 2327-3097 ER - TY - JOUR TI - Measuring Situation Awareness in Virtual Environment-Based Training AU - Kaber, David B. AU - Riley, Jennifer M. AU - Endsley, Mica R. AU - Sheik-Nainar, Mohamed AU - Zhang, Tao AU - Lampton, Donald R. T2 - MILITARY PSYCHOLOGY AB - We evaluated the efficacy of a computer-based situation awareness (SA) measurement system for training dismounted infantry SA in an urban terrain virtual reality (VR) simulation. Based on past research, we hypothesized that the SA measures would be sensitive to individual (squad leader) differences, and that the frequency of specific probes would reveal differences in critical SA requirements among scenarios. Three infantry squads performed multiple trials across two different scenarios. A confederate platoon leader posed probes to squad leaders during trials and experts made ratings afterward. Results revealed squad leaders had similar responses to probes, despite differences in combat experience. Analysis of probe frequency revealed different high priority SA elements and decisions for each scenario. The SA behavior and communication ratings revealed differences among squads, which trended with experience. Measures of SA were also consistent across the test scenario as a result of similar mission types and task difficulties. We discuss the implication of our findings for future research and theory within this area. DA - 2013/// PY - 2013/// DO - 10.1037/h0095998 VL - 25 IS - 4 SP - 330-344 SN - 1532-7876 KW - situation awareness measurement KW - military operations KW - virtual reality KW - simulation and training ER - TY - JOUR TI - Influence of Flight Domain and Cockpit Display Dynamics on Pilot Perceived Clutter AU - Kaber, David B. AU - Naylor, James T. AU - Gil, Guk-Ho AU - Pankok, Carl AU - Kim, Sang-Hwan T2 - JOURNAL OF AEROSPACE INFORMATION SYSTEMS AB - Two analyses were conducted on three datasets from a series of aviation human factors experiments focused on the development and testing of measures of flight display clutter as well as the relation with flight task performance. The objectives of this study were to assess the effects of cockpit display dynamics and aircraft type on pilot perceptions of display clutter in simulated flight tasks through statistical analyses of the data gathered across the experimental studies. Comparisons were made on observations of pilots with comparable experience under similar headup or headdown display conditions. In general, this research demonstrated the clutter measures to be highly sensitive to aviation display and domain conditions. The findings also indicated that human information processing considerations in aviation display design coupled with attention to the visual characteristics of display features may provide an effective basis for mitigating potential effects of clutter on pilot performance. DA - 2013/12// PY - 2013/12// DO - 10.2514/1.i010036 VL - 10 IS - 12 SP - 550-559 SN - 2327-3097 ER - TY - JOUR TI - Estimating the cost of no-shows and evaluating the effects of mitigation strategies AU - Berg, B. P. AU - Murr, M. AU - Chermak, D. AU - Woodall, J. AU - Pignone, M. AU - Sandler, R. S. AU - Denton, B. T. T2 - Medical Decision Making DA - 2013/// PY - 2013/// VL - 33 IS - 8 SP - 976-985 ER - TY - JOUR TI - A Logarithmic Method for Reducing Binary Variables and Inequality Constraints in Solving Task Assignment Problems AU - Li, Han-Lin AU - Huang, Yao-Huei AU - Fang, Shu-Cherng T2 - INFORMS JOURNAL ON COMPUTING AB - This paper studies the classical task assignment problem (TAP) in which M unbreakable tasks are assigned to N agents with the objective to minimize the communication and process costs subject to each agent's capacity constraint. Because a large-size TAP involves many binary variables, most, if not all, traditional methods experience the difficulty in solving the problem within a reasonable time period. Recent works present a logarithmic approach to reduce the number of binary variables in problems with mixed-integer variables. This study proposes a new logarithmic method that significantly reduces the numbers of binary variables and inequality constraints in solving task assignment problems. Our numerical experiments demonstrate that the proposed method is superior to other known methods of this kind for solving large-size TAPs. DA - 2013/// PY - 2013/// DO - 10.1287/ijoc.1120.0527 VL - 25 IS - 4 SP - 643-653 SN - 1526-5528 KW - task assignment problem KW - binary variables KW - mixed-integer programming problem ER - TY - JOUR TI - Validation of a Haptic-Based Simulation to Test Complex Figure Reproduction Capability AU - Li, Yingjie AU - Clamann, Michael AU - Kaber, David B. T2 - IEEE TRANSACTIONS ON HUMAN-MACHINE SYSTEMS AB - The objective of this research was to develop a new computer-based system for psychomotor skill assessment. The focus was on the simulation of the Rey-Osterrieth Complex Figure (ROCF) reproduction test incorporating a haptic interface. Various system functions were created to support customized testing protocols that are based on specific user requirements, facilitate semiautomated scoring of tests, and produce quantitative test output. Advanced technologies of pattern recognition were reviewed and adapted for the system development. This approach yielded an application for recording freehand drawings and recognizing and normalizing drawing strokes for semiautomated scoring according to a standard. The new simulator system was validated by comparison with traditional paper-based tests in which participants were asked to use their nondominant hand to simulate a minor motor impairment. Results demonstrated the simulator to be sensitive to functional differences between dominant and nondominant hand use. The computerized scoring software also appeared to be valid for generating ROCF scores, which were consistent with manual scores determined by a trained rater for the same drawing stimuli. DA - 2013/11// PY - 2013/11// DO - 10.1109/tsmc.2013.2287341 VL - 43 IS - 6 SP - 547-557 SN - 2168-2305 KW - Computer simulation KW - haptic interfaces KW - neuropsychological assessment KW - Rey-Osterrieth complex figure ER - TY - JOUR TI - Assortment and inventory decisions with multiple quality levels AU - Mayorga, Maria E. AU - Ahn, Hyun-Soo AU - Aydin, Goker T2 - Annals of Operations Research DA - 2013/9/18/ PY - 2013/9/18/ DO - 10.1007/s10479-013-1456-7 VL - 211 IS - 1 SP - 301-331 J2 - Ann Oper Res LA - en OP - SN - 0254-5330 1572-9338 UR - http://dx.doi.org/10.1007/s10479-013-1456-7 DB - Crossref KW - Assortment planning KW - Inventory management KW - Consumer choice models ER - TY - JOUR TI - Optimal intervention strategies for an epidemic: A household view AU - Yarmand, Hamed AU - Ivy, Julie S. T2 - SIMULATION-TRANSACTIONS OF THE SOCIETY FOR MODELING AND SIMULATION INTERNATIONAL AB - In this research, we identify optimal intervention strategies at the household level in case of an epidemic. We consider an affected household (a household with one initial infective member) and model the effect of different intervention policies, which involve vaccination, antiviral prophylaxis, isolation, and treatment, on disease spread using a variation of Kermack–McKendrick (KM) models. Both full and partial adherence to interventions are considered. An implementation cost is assumed for each intervention policy. We refer to a collection of intervention policies as an intervention strategy. A reward is associated with susceptible members who remain uninfected. We define the effect of the implemented intervention strategy as the total reward earned by all members over the time horizon. We then identify the most cost-effective intervention strategies. In addition, we incorporate a budgetary constraint for the household and find the efficient frontier for the total reward over different upper bounds on the household budget. DA - 2013/12// PY - 2013/12// DO - 10.1177/0037549713505333 VL - 89 IS - 12 SP - 1505-1522 SN - 1741-3133 ER - TY - JOUR TI - Identifying optimal mitigation strategies for responding to a mild influenza epidemic AU - Yarmand, Hamed AU - Ivy, Julie S. AU - Roberts, Stephen D. T2 - SIMULATION-TRANSACTIONS OF THE SOCIETY FOR MODELING AND SIMULATION INTERNATIONAL AB - Mathematical models have been developed to simulate influenza epidemics to help public health officials evaluate different control policies. In these models, often severe influenza epidemics with a considerable mortality rate are considered. However, as was the case for the 2009 H1N1 pandemic, some of the influenza epidemics are mild with insignificant mortality rates. In the case of a mild epidemic, the cost of different control policies becomes an important decision factor in addition to disease-related outcomes such as the attack rate. We develop a continuous-time simulation model for the spread of a mild influenza epidemic based on the SEIR model (an epidemiological model with four classes: susceptible, exposed, infective, and recovered) which includes different interventions. To determine the epidemic mitigation policy with the minimum cost, we also develop an optimization model with two decision variables, vaccination and self-isolation fractions, and an upper-bound constraint for the attack rate. We use this model to evaluate the cost-effectiveness of different mitigation policies. Furthermore, we integrate the simulation and optimization models to identify the optimal mitigation policy. Finally, we conduct sensitivity analysis on the key input parameters to ensure robust results. The optimal policy depends on the target population and, as our results show, in general is a combination of vaccination and self-isolation. Further, for low (high) levels of intervention, vaccination (self-isolation) is incrementally more cost-effective. Therefore, public health officials should concentrate on vaccination at the beginning of the epidemic. However, if the epidemic continues to spread, they should promote self-isolation as a more effective intervention. DA - 2013/11// PY - 2013/11// DO - 10.1177/0037549713505334 VL - 89 IS - 11 SP - 1400-1415 SN - 1741-3133 KW - Simulation KW - mild epidemic KW - optimal control policy KW - cost-effectiveness analysis KW - vaccination KW - self-isolation ER - TY - JOUR TI - The Effects of Thoracic Manipulation Versus Mobilization for Chronic Neck Pain: a Randomized Controlled Trial Pilot Study AU - Suvarnnato, Thavatchai AU - Puntumetakul, Rungthip AU - Kaber, David AU - Boucaut, Rose AU - Boonphakob, Yodchai AU - Arayawichanon, Preeda AU - Chatchawan, Uraiwan T2 - JOURNAL OF PHYSICAL THERAPY SCIENCE AB - [Purpose] To investigate effects of thoracic manipulation versus mobilization on chronic neck pain. [Methods] Thirty-nine chronic neck pain subjects were randomly assigned to single level thoracic manipulation, single level thoracic mobilization, or a control group. The cervical range of motion (CROM) and pain ratings (using a visual analog scale: VAS) were measured before, immediately after and at a 24-hour follow-up. [Results] Thoracic manipulation significantly decreased VAS pain ratings and increased CROM in all directions in immediate and 24-hour follow-ups. The thoracic mobilization group significantly increased in CROM in most directions at immediate follow-up and right and left rotational directions at the 24-hour follow-up. Comparisons between groups revealed the CROM for the manipulation group to increase significantly more than for control subjects in most directions at immediate follow-up and flexion, left lateral flexion and left rotation at the 24-hour follow-up. The CROM for the thoracic mobilization group significantly increased in comparison to the control group in flexion at immediate follow-up and in flexion and left rotation at the 24-hour follow-up. [Conclusion] The study demonstrated reductions in VAS pain ratings and increases in CROM at immediate and 24-hour follow-ups from both single level thoracic spine manipulation and thoracic mobilization in chronic neck pain. DA - 2013/7// PY - 2013/7// DO - 10.1589/jpts.25.865 VL - 25 IS - 7 SP - 865-871 SN - 2187-5626 KW - Single level thoracic manipulation KW - Single level thoracic mobilization KW - Chronic neck pain ER - TY - JOUR TI - Simulated estimates of pre-pregnancy and gestational diabetes mellitus in the US: 1980 to 2008 AU - Mayorga, Maria AU - Reifsnider, O. S. AU - Neyens, D. M. AU - Gebregziabher, M. G. AU - Hunt, K. J. T2 - PLoS One AB - To simulate national estimates of prepregnancy and gestational diabetes mellitus (GDM) in non-Hispanic white (NHW) and non-Hispanic black (NHB) women.Prepregnancy diabetes and GDM were estimated as a function of age, race/ethnicity, and body mass index (BMI) using South Carolina live singleton births from 2004-2008. Diabetes risk was applied to a simulated population. Age, natality and BMI were assigned to women according to race- and age-specific US Census, Natality and National Health and Nutrition Examination Surveys (NHANES) data, respectively.From 1980-2008, estimated GDM prevalence increased from 4.11% to 6.80% [2.68% (95% CI 2.58%-2.78%)] and from 3.96% to 6.43% [2.47% (95% CI 2.39%-2.55%)] in NHW and NHB women, respectively. In NHW women prepregnancy diabetes prevalence increased 0.90% (95% CI 0.85%-0.95%) from 0.95% in 1980 to 1.85% in 2008. In NHB women from 1980 through 2008 estimated prepregnancy diabetes prevalence increased 1.51% (95% CI 1.44%-1.57%), from 1.66% to 3.16%.Racial disparities in diabetes prevalence during pregnancy appear to stem from a higher prevalence of prepregnancy diabetes, but not GDM, in NHB than NHW. DA - 2013/// PY - 2013/// DO - 10.1371/journal.pone.0073437 VL - 8 IS - 9 ER - TY - JOUR TI - Planning Wafer Starts using Nonlinear Clearing Functions: A Large-Scale Experiment AU - Kacar, Necip Baris AU - Moench, Lars AU - Uzsoy, Reha T2 - IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING AB - The nonlinear, circular dependency between workload and cycle times for production resources governed by queueing behavior has been a longstanding difficulty in the production planning domain. The issue is particularly important for semiconductor wafer fabrication facilities, which must operate at relatively high utilization to be profitable. Nonlinear clearing functions that relate the expected output of a resource in a planning period to the amount of work available to it have been proposed as an alternative approach. While computational tests on small systems have been promising, the question of whether the results remain valid for large-scale systems has remained open. In this paper we evaluate the performance of a clearing function based production planning model using a simulation of a large-scale wafer fab with two products and several hundred operations. Results indicate that, consistent with the results of previous experiments, the clearing function model yields substantial improvements in profit over conventional linear programming models. DA - 2013/11// PY - 2013/11// DO - 10.1109/tsm.2013.2283038 VL - 26 IS - 4 SP - 602-612 SN - 1558-2345 KW - Clearing functions KW - linear programming KW - production planning KW - release planning KW - simulation ER - TY - JOUR TI - Note on "Simulation optimization of PSA-threshold based prostate cancer screening policies" AU - Underwood, D. J. AU - Zhang, J. Y. AU - Denton, B. T. AU - Shah, N. D. AU - Inman, B. A. T2 - Health Care Management Science DA - 2013/// PY - 2013/// VL - 16 IS - 4 SP - 377-378 ER - TY - JOUR TI - Improving patient access to chemotherapy treatment at Duke Cancer Institute AU - Woodall, J. C. AU - Gosselin, T. AU - Boswell, A. AU - Murr, M. AU - Denton, B. T. T2 - Interfaces DA - 2013/// PY - 2013/// VL - 43 IS - 5 SP - 449-461 ER - TY - CONF TI - Comparison of an ℓ1-regression-based and a RANSAC-based planar segmentation procedure for urban terrain data with many outliers AU - Luo, Jian AU - Deng, Zhibin AU - Bulatov, Dimitri AU - Lavery, John E. AU - Fang, Shu-Cherng T2 - SPIE Remote Sensing A2 - Bruzzone, Lorenzo T3 - Proceedings of SPIE AB - For urban terrain data with many outliers, we compare an ℓ1-regression-based and a RANSAC-based planar segmentation procedure. The procedure consists of 1) calculating the normal at each of the points using ℓ1 regression or RANSAC, 2) clustering the normals thus generated using DBSCAN or fuzzy c-means, 3) within each cluster, identifying segments (roofs, walls, ground) by DBSCAN-based-subclustering of the 3D points that correspond to each cluster of normals and 4) fitting the subclusters by the same method as that used in Step 1 (ℓ1 regression or RANSAC). Domain decomposition is used to handle data sets that are too large for processing as a whole. Computational results for a point cloud of a building complex in Bonnland, Germany obtained from a depth map of seven UAV-images are presented. The ℓ1-regression-based procedure is slightly over 25% faster than the RANSAC-based procedure and produces better dominant roof segments. However, the roof polygonalizations and cutlines based on these dominant segments are roughly equal in accuracy for the two procedures. For a set of artificial data, ℓ1 regression is much more accurate and much faster than RANSAC. We outline the complete building reconstruction procedure into which the ℓ1-regression-based and RANSAC-based segmentation procedures will be integrated in the future. C2 - 2013/10/17/ C3 - Image and Signal Processing for Remote Sensing XIX CY - Dresden, Germany DA - 2013/10/17/ PY - 2013/9/23/ DO - 10.1117/12.2028627 VL - 8892 SP - 889209 PB - SPIE UR - http://dx.doi.org/10.1117/12.2028627 KW - DBSCAN KW - fuzzy c-means KW - l(1) regression KW - outlier-rich KW - planar KW - RANSAC KW - segmentation KW - urban terrain ER - TY - JOUR TI - A branch-and-cut approach to portfolio selection with marginal risk control in a linear conic programming framework AU - Deng, Zhibin AU - Bai, Yanqin AU - Fang, Shu-Cherng AU - Tian, Ye AU - Xing, Wenxun T2 - JOURNAL OF SYSTEMS SCIENCE AND SYSTEMS ENGINEERING DA - 2013/12// PY - 2013/12// DO - 10.1007/s11518-013-5234-5 VL - 22 IS - 4 SP - 385-400 SN - 1861-9576 KW - Portfolio selection KW - linear conic programming KW - branch-and-cut ER - TY - CONF TI - A biomechanical study of directional mechanical properties of porcine skin tissues AU - Huang, H.-Y. S. AU - Huang, S. AU - Gettys, T. A. AU - Harrysson, O. C2 - 2013/// C3 - ASME 2013 International Mechanical Engineering Congress & Exposition DA - 2013/// ER - TY - JOUR TI - Controlled Scalable Synthesis of Uniform, High-Quality Monolayer and Few-layer MoS2 Films AU - Yu, Yifei AU - Li, Chun AU - Liu, Yi AU - Su, Liqin AU - Zhang, Yong AU - Cao, Linyou T2 - SCIENTIFIC REPORTS AB - Two dimensional (2D) materials with a monolayer of atoms represent an ultimate control of material dimension in the vertical direction. Molybdenum sulfide (MoS2) monolayers, with a direct bandgap of 1.8 eV, offer an unprecedented prospect of miniaturizing semiconductor science and technology down to a truly atomic scale. Recent studies have indeed demonstrated the promise of 2D MoS2 in fields including field effect transistors, low power switches, optoelectronics, and spintronics. However, device development with 2D MoS2 has been delayed by the lack of capabilities to produce large-area, uniform, and high-quality MoS2 monolayers. Here we present a self-limiting approach that can grow high quality monolayer and few-layer MoS2 films over an area of centimeters with unprecedented uniformity and controllability. This approach is compatible with the standard fabrication process in semiconductor industry. It paves the way for the development of practical devices with 2D MoS2 and opens up new avenues for fundamental research. DA - 2013/5/21/ PY - 2013/5/21/ DO - 10.1038/srep01866 VL - 3 SP - SN - 2045-2322 ER - TY - JOUR TI - Analytic solution of the susceptible-infective epidemic model with state-dependent contact rates and different intervention policies AU - Yarmand, Hamed AU - Ivy, Julie S. T2 - SIMULATION-TRANSACTIONS OF THE SOCIETY FOR MODELING AND SIMULATION INTERNATIONAL AB - We consider the susceptible-infective (SI) epidemiological model, a variant of the Kermack–McKendrick models, and let the contact rate be a function of the number of infectives, an indicator of disease spread during the course of the epidemic. We represent the resultant model as a continuous-time Markov chain. The result is a pure death (or birth) process with state-dependent rates, for which we find the probability distribution of the associated Markov chain by solving the Kolmogorov forward equations. This model is used to find the analytic solution of the SI model as well as the distribution of the epidemic duration. We use the maximum likelihood method to estimate contact rates based on observations of inter-infection time intervals. We compare the stochastic model to the corresponding deterministic models through a numerical experiment within a typical household. We also incorporate different intervention policies for vaccination, antiviral prophylaxis, isolation, and treatment considering both full and partial adherence to interventions among individuals. DA - 2013/6// PY - 2013/6// DO - 10.1177/0037549713479052 VL - 89 IS - 6 SP - 703-721 SN - 1741-3133 KW - susceptible-infective model KW - epidemic duration KW - state-dependent contact rates KW - interventions ER - TY - JOUR TI - Fuzzy hypothesis testing with vague data using likelihood ratio test AU - Alizadeh, H. M. AU - Khamseh, A. R. A. AU - Ghomi, S. M. T. F. T2 - Soft Computing DA - 2013/// PY - 2013/// VL - 17 IS - 9 SP - 1629-1641 ER - TY - JOUR TI - Endoscopy Unit Efficiency: Quality Redefined AU - Gellad, Ziad F. AU - Thompson, Cole P. AU - Taheri, Javad T2 - Clinical Gastroenterology and Hepatology AB - This month’s contribution by Gellad et al concerns efficiency within an endoscopy unit. There are over 5400 Medicare certified ambulatory surgical centers (ASC) in the United States providing a distributed network of high quality, accessible centers for patients in need of outpatient endoscopic procedures. Most of these units are running efficiently with little room for waste (or they would not be able to survive in the current environment). Dr Gellad and colleagues have developed a process to analyze effi ciency by defining performance metrics based on standard Dona bedian analysis. Their article relates mostly to units performing a mix of procedures usually within a hospital unit. These units, unlike ASCs, deserve our scrutiny since many are operated at efficiency levels that provide “opportunities.” DA - 2013/9// PY - 2013/9// DO - 10.1016/J.CGH.2013.06.005 VL - 11 IS - 9 SP - 1046-1049.e1 J2 - Clinical Gastroenterology and Hepatology LA - en OP - SN - 1542-3565 UR - http://dx.doi.org/10.1016/J.CGH.2013.06.005 DB - Crossref ER - TY - JOUR TI - Computing optimal base-stock levels for an inventory system with imperfect supply AU - Warsing, Donald P., Jr. AU - Wangwatcharakul, Worawut AU - King, Russell E. T2 - Computers & Operations Research AB - We study a single-item, single-site, periodic-review inventory system with negligible fixed ordering costs. The supplier to this system is not entirely reliable, such that each order is a Bernoulli trial, meaning that, with a given probability, the supplier delivers the current order and any accumulated backorders at the end of the current period, resulting in a Geometric distribution for the actual resupply lead time. We develop a recursive expression for the steady-state probability vector of a discrete-time Markov process (DTMP) model of this imperfect-supply inventory system. We use this recursive expression to prove the convexity of the inventory system objective function, and also to prove the optimality of our computational procedure for finding the optimal base-stock level. We present a service-constrained version of the problem and show how the computation of the optimal base-stock level using our DTMP method, incorporating the explicit distribution of demand over the lead time plus review (LTR) period, compares to approaches in the literature that approximate this distribution. We also show that the version of the problem employing an explicit penalty cost can be solved in closed-form for the optimal base-stock level for two specific period demand distributions, and we explore the behavior of the optimal base-stock level and the corresponding optimal service level under various values of the problem parameters. DA - 2013/11// PY - 2013/11// DO - 10.1016/j.cor.2013.04.001 VL - 40 IS - 11 SP - 2786-2800 J2 - Computers & Operations Research LA - en OP - SN - 0305-0548 UR - http://dx.doi.org/10.1016/j.cor.2013.04.001 DB - Crossref KW - Inventory KW - Base-stock policy KW - Imperfect supply KW - Supply risk ER - TY - JOUR TI - The effect of handle design on upper extremity posture and muscle activity during a pouring task AU - Uy, C. AU - Chang, C. C. AU - Fallentin, N. AU - McGorry, R. W. AU - Hsiang, S. M. T2 - Ergonomics DA - 2013/// PY - 2013/// VL - 56 IS - 8 SP - 1326-1335 ER - TY - JOUR TI - ON CONSTRAINT QUALIFICATIONS: MOTIVATION, DESIGN AND INTER-RELATIONS AU - Wang, Ziteng AU - Fang, Shu-Cherng AU - Xing, Wenxun T2 - JOURNAL OF INDUSTRIAL AND MANAGEMENT OPTIMIZATION AB - Constraint qualification (CQ) is an important concept in nonlinear programming. This paper investigates the motivation of introducing constraint qualifications in developing KKT conditions for solving nonlinear programs and provides a geometric meaning of constraint qualifications. A unified framework of designing constraint qualifications by imposing conditions to equate the so-called ``locally constrained directions' to certain subsets of ``tangent directions' is proposed. Based on the inclusion relations of the cones of tangent directions, attainable directions, feasible directions and interior constrained directions, constraint qualifications are categorized into four levels by their relative strengths. This paper reviews most, if not all, of the commonly seen constraint qualifications in the literature, identifies the categories they belong to, and summarizes the inter-relationship among them. The proposed framework also helps design new constraint qualifications of readers' specific interests. DA - 2013/10// PY - 2013/10// DO - 10.3934/jimo.2013.9.983 VL - 9 IS - 4 SP - 983-1001 SN - 1547-5816 KW - Constraint qualification KW - nonlinear programming KW - optimality conditions KW - optimization KW - KKT conditions ER - TY - JOUR TI - Modeling and Analysis of Integrated Planning of Production and Engineering Process Improvement AU - Kim, Sukgon AU - Uzsoy, Reha T2 - IEEE Transactions on Semiconductor Manufacturing AB - A clearing function that can capture the nonlinear relationship between workloads and throughput and also reflect capacity improvement by engineering activities on a multioperation workcenter is developed. The clearing function is then used to formulate an integrated optimization model for planning both production and engineering process improvement. Marginal cost analysis using the Karush-Kuhn-Tucker optimality conditions provides useful insights into effective management of resources in a reentrant manufacturing system. DA - 2013/8// PY - 2013/8// DO - 10.1109/tsm.2013.2261099 VL - 26 IS - 3 SP - 414-422 J2 - IEEE Trans. Semicond. Manufact. OP - SN - 0894-6507 1558-2345 UR - http://dx.doi.org/10.1109/tsm.2013.2261099 DB - Crossref KW - Manufacturing planning KW - production management KW - semiconductor process modeling ER - TY - JOUR TI - Material-Insensitive Feature Depth Control and Machining Force Reduction by Ultrasonic Vibration in AFM-Based Nanomachining AU - Zhang, Li AU - Dong, Jingyan AU - Cohen, Paul H. T2 - IEEE TRANSACTIONS ON NANOTECHNOLOGY AB - This paper investigates the effect of ultrasonic tip-sample vibration in regulating the fabricated feature depth and reducing machining force in ultrasonic vibration-assisted nanomachining with an atomic force microscope (AFM). Nanopatterns on aluminum and polymethyl methacrylate (PMMA) substrates are fabricated by the ultrasonic vibration-assisted nanomachining approach. It is demonstrated that using a small set-point force and the same vibration amplitude for machining PMMA and aluminum, nearly the same feature depth is achieved. The fabrication depth is mainly controlled by the amplitude of the tip-sample z-vibration, and is insensitive to sample materials. A theoretical analysis of the sample contact stiffness and dynamic stiffness of the cantilever is used to explain the observed material-insensitive depth regulation by ultrasonic tip-sample vibration. The ultrasonic vibration also effectively reduces the normal force and friction during nanomachining. On both PMMA and aluminum samples, experimental results demonstrate significant reduction in set-point force and lateral friction force in ultrasonic vibration-assisted nanomachining compared with nanomachining without ultrasonic z-vibration. Smaller tip wear is observed in ultrasonic vibration-assisted nanomachining for the fabrication of PMMA samples. DA - 2013/9// PY - 2013/9// DO - 10.1109/tnano.2013.2273272 VL - 12 IS - 5 SP - 743-750 SN - 1941-0085 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84883779535&partnerID=MN8TOARS KW - Atomic force microscope (AFM) KW - nanomachining KW - tip-based nanofabrication KW - ultrasonic vibration ER - TY - JOUR TI - Effects of restrictive clothing on lumbar range of motion and trunk muscle activity in young adult worker manual material handling AU - Eungpinichpong, Wichai AU - Buttagat, Vitsarut AU - Areeudomwong, Pattanasin AU - Pramodhyakul, Noppol AU - Swangnetr, Manida AU - Kaber, David AU - Puntumetakul, Rungthip T2 - APPLIED ERGONOMICS AB - The objective of this study was to examine the effect of wearing restrictive trousers on lumbar spine movement, trunk muscle activity and low back discomfort (LBD) in simulations of manual material handling (MMH) tasks. Twenty-eight young adults participated in the study performing box lifting, liquid container handling while squatting, and forward reaching while sitting on a task chair when wearing tight pants (sizes too small for the wearer) vs. fit pants (correct size according to anthropometry). Each task was repeated three times and video recordings were used as a basis for measuring lumbar range of motion (LRoM). The response was normalized in terms on baseline hip mobility. Trunk muscle activity of rectus abdominis (RA) and erector spinae (ES) muscles were also measured in each trial and normalized. At the close of each trial, participants rated LBD using a visual analog scale. Results revealed significant effects of both pants and task types on the normalized LRoM, trunk muscle activity and subjective ratings of LBD. The LRoM was higher and trunk muscle (ES) activity was lower for participants when wearing tight pants, as compared to fit pants. Discomfort ratings were significantly higher for tight pants than fit. These results provide guidance for recommendations on work clothing fit in specific types of MMH activities in order to reduce the potential of low-back pain among younger workers in industrial companies. DA - 2013/11// PY - 2013/11// DO - 10.1016/j.apergo.2013.04.002 VL - 44 IS - 6 SP - 1024-1032 SN - 1872-9126 KW - Manual material handling KW - Lumbar range of motion KW - Trunk muscle activity ER - TY - JOUR TI - Using Common Random Numbers in Health Care Cost-Effectiveness Simulation Modeling AU - Murphy, Daniel R. AU - Klein, Robert W. AU - Smolen, Lee J. AU - Klein, Timothy M. AU - Roberts, Stephen D. T2 - HEALTH SERVICES RESEARCH AB - Objectives To identify the problem of separating statistical noise from treatment effects in health outcomes modeling and analysis. To demonstrate the implementation of one technique, common random numbers ( CRN s), and to illustrate the value of CRN s to assess costs and outcomes under uncertainty. Methods A microsimulation model was designed to evaluate osteoporosis treatment, estimating cost and utility measures for patient cohorts at high risk of osteoporosis‐related fractures. Incremental cost‐effectiveness ratios ( ICER s) were estimated using a full implementation of CRN s, a partial implementation of CRN s, and no CRN s. A modification to traditional probabilistic sensitivity analysis ( PSA ) was used to determine how variance reduction can impact a decision maker's view of treatment efficacy and costs. Results The full use of CRN s provided a 93.6 percent reduction in variance compared to simulations not using the technique. The use of partial CRN s provided a 5.6 percent reduction. The PSA results using full CRN s demonstrated a substantially tighter range of cost‐benefit outcomes for teriparatide usage than the cost‐benefits generated without the technique. Conclusions CRN s provide substantial variance reduction for cost‐effectiveness studies. By reducing variability not associated with the treatment being evaluated, CRN s provide a better understanding of treatment effects and risks. DA - 2013/8// PY - 2013/8// DO - 10.1111/1475-6773.12044 VL - 48 IS - 4 SP - 1508-1525 SN - 0017-9124 KW - Variance reduction KW - common random numbers KW - cost-effectiveness modeling KW - osteoporosis ER - TY - JOUR TI - Transport costs and China's exports: Some empirical evidences AU - Lizhi, Xu AU - Shu-Cherng, Fang AU - Xun, Zhang T2 - JOURNAL OF SYSTEMS SCIENCE & COMPLEXITY DA - 2013/6// PY - 2013/6// DO - 10.1007/s11424-013-1259-6 VL - 26 IS - 3 SP - 365-382 SN - 1559-7067 KW - Container throughput KW - port efficiency KW - the gravity model KW - transport costs ER - TY - JOUR TI - A Markov decision process-based policy characterization approach for a stochastic inventory control problem with unreliable sourcing AU - Ahiska, S. Sebnem AU - Appaji, Samyuktha R. AU - King, Russell E. AU - Warsing, Donald P., Jr. T2 - INTERNATIONAL JOURNAL OF PRODUCTION ECONOMICS AB - We consider a single-product periodic-review inventory system for a retailer who has adopted a dual sourcing strategy to cope with potential supply process interruptions. Orders are placed to a perfectly reliable supplier and/or to a less reliable supplier that offers a better price. The success of an order placed to the unreliable supplier depends on his supply status that has a Markovian nature. The inventory control problem for this unreliable supply chain is modeled as a discrete-time Markov decision process (MDP) in order to find the optimal ordering decisions. Through numerical experimentation, the structure of the optimal ordering policy under several cost scenarios and different supplier reliability levels is determined. Four basic policy structures are found and are referred as case 1: order only from the unreliable supplier; case 2: order simultaneously from both suppliers or only from the unreliable supplier depending on the inventory level; case 3: order from one or the other but not both suppliers simultaneously; and case 4: order only from the reliable supplier. For all cases, (s, S)-like policies characterize perfectly the optimal ordering decisions due to the existence of the fixed ordering cost. Further experimentation is done to study the effects of changes in several system parameters (cost parameters such as fixed ordering cost, unit purchasing cost, backorder cost as well as the supplier reliability level) on the ordering policy and cost of the system. DA - 2013/8// PY - 2013/8// DO - 10.1016/j.ijpe.2013.03.021 VL - 144 IS - 2 SP - 485-496 SN - 1873-7579 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84878827602&partnerID=MN8TOARS KW - Unreliable supply KW - Dual sourcing KW - Inventory policy characterization KW - Markov decision process ER - TY - JOUR TI - Dynamic Appointment Scheduling of a Stochastic Server with Uncertain Demand AU - Erdogan, S. Ayca AU - Denton, Brian T2 - INFORMS JOURNAL ON COMPUTING AB - We formulate and solve two new stochastic linear programming formulations of appointment scheduling problems that are motivated by the management of health services. We assume that service durations and the number of customers to be served on a particular day are uncertain. In the first model, customers may fail to show up for their appointments (“no-show”). This model is formulated as a two-stage stochastic linear program. In the second model, customers are scheduled dynamically, one at a time, as they request appointments. This model is formulated as a multistage stochastic linear program with stages defined by customer appointment requests. We analyze the structure of the models and adapt decomposition-based algorithms to solve the problems efficiently. We present numerical results that illustrate the impact of uncertainty on dynamic appointment scheduling, and we identify useful insights that can be applied in practice. We also present a case study based on real data for an outpatient procedure center. DA - 2013/// PY - 2013/// DO - 10.1287/ijoc.1110.0482 VL - 25 IS - 1 SP - 116-132 SN - 1526-5528 KW - appointment scheduling KW - stochastic programming KW - health care ER - TY - JOUR TI - Biocompatibility analysis of an electrically-activated silver-based antibacterial surface system for medical device applications AU - Samberg, Meghan E. AU - Tan, Zhuo AU - Monteiro-Riviere, Nancy A. AU - Orndorff, Paul E. AU - Shirwaiker, Rohan A. T2 - JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE DA - 2013/3// PY - 2013/3// DO - 10.1007/s10856-012-4838-5 VL - 24 IS - 3 SP - 755-760 SN - 1573-4838 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84876410058&partnerID=MN8TOARS ER - TY - JOUR TI - An empirical assessment of driver motivation and emotional states in perceived safety margins under varied driving conditions AU - Zhang, Yu AU - Kaber, David B. T2 - ERGONOMICS AB - Motivation models in driving behaviour postulate that driver motives and emotional states dictate risk tolerance under various traffic conditions. The present study used time and driver performance-based payment systems to manipulate motivation and risk-taking behaviour. Ten participants drove to a predefined location in a simulated driving environment. Traffic patterns (density and velocity) were manipulated to cause driver behaviour adjustments due to the need to conform with the social norms of the roadway. The driving environment complexity was investigated as a mediating factor in risk tolerance. Results revealed the performance-based payment system to closely relate to risk-taking behaviour as compared with the time-based payment system. Drivers conformed with social norms associated with specific traffic patterns. Higher roadway complexity led to a more conservative safety margins and speeds. This research contributes to the further development of motivational models of driver behaviour. Practitioner Summary: This study provides empirical justification for two motivation factors in driver risk-taking decisions, including compliance with social norm and emotions triggered by incentives. Environment complexity was identified as a mediating factor in motivational behaviour model. This study also recommended safety margin measures sensitive to changes in driver risk tolerance. DA - 2013/2/1/ PY - 2013/2/1/ DO - 10.1080/00140139.2012.739208 VL - 56 IS - 2 SP - 256-267 SN - 1366-5847 KW - driver motivation models KW - vehicle safety margins KW - traffic pattern KW - driver incentives KW - driving environment complexity ER - TY - JOUR TI - Acceptance of Assistive Technology by Special Education Teachers: A Structural Equation Model Approach AU - Nam, Chang S. AU - Bahn, Sangwoo AU - Lee, Raney T2 - INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION AB - To investigate the acceptance of assistive technology (AT) by special education teachers, the present study developed and tested hypothesized relationships among key determinants of AT acceptance such as the facilitating condition, perceived ease of use, computer self-efficacy, result demonstrability, perceived usefulness, and behavioral intention. Results from analysis of data collected from a number of special education teachers in schools for the visually and/or auditory impaired confirmed the effects hypothesized in our conceptual model of AT acceptance. In particular, perceived usefulness was a dominant factor affecting AT usage. Facilitating condition was strongly related to perceived ease of use, whereas perceived ease of use had a significant effect on computer self-efficacy. This study also found the importance of result demonstrability factor, which had significant effects on both computer self-efficacy and perceived usefulness. This study expanded and enriched a traditional technology acceptance model by further investigating determinants associated with the acceptance of AT by special education teachers for the blind and/or the deaf. In addition, the results of the present study should provide some insights into the understanding of AT acceptance and the decisions of AT utilization, as well as its distribution and training. DA - 2013/4/1/ PY - 2013/4/1/ DO - 10.1080/10447318.2012.711990 VL - 29 IS - 5 SP - 365-377 SN - 1532-7590 ER - TY - JOUR TI - Supporting medical device development: a standard product design process model AU - Medina, Lourdes A. AU - Kremer, Guel E. Okudan AU - Wysk, Richard A. T2 - JOURNAL OF ENGINEERING DESIGN AB - Abstract This article describes the complex nature of the medical device development (MDD) process and presents a product design process model to aid designers engaged in MDD. Basically, the model serves as a conceptual framework and provides a set of formalisms to define the development landscape for medical devices. Specifically, the model describes the phases of MDD and their relationships, including the testing and approval environment that impacts this process. The Food and Drug Administration (FDA) is an essential part of this environment, acting as the regulatory agency for medical devices in the USA. FDA approval is a significant milestone which industry developers must achieve before the actual release of their devices in the US market. In this article, the relevant literature addressing the regulations and the MDD process models are reviewed. The development and organisation of the model are discussed in detail with descriptions of the building process, concepts, granularity, utility and overall contribution. The model is the result of a documentation analysis and is supported by a content validation survey and a case study. The model is proposed as an aid for designers to proactively use in handling the complexities of MDD. Keywords: medical devicedevelopment processproduct designprocess modelregulation Notes DA - 2013/2/1/ PY - 2013/2/1/ DO - 10.1080/09544828.2012.676635 VL - 24 IS - 2 SP - 83-119 SN - 1466-1837 KW - medical device KW - development process KW - product design KW - process model KW - regulation ER - TY - JOUR TI - Optimum estimation of missing values in randomized complete block design by genetic algorithm AU - Azadeh, A. AU - Asadzadeh, S. M. AU - Jafari-Marandi, R. AU - Nazari-Shirkouhi, S. AU - Khoshkhou, G. B. AU - Talebi, S. AU - Naghavi, A. T2 - Knowledge-based Systems DA - 2013/// PY - 2013/// VL - 37 SP - 37-47 ER - TY - JOUR TI - Nanomaterials and synergistic low-intensity direct current (LIDC) stimulation technology for orthopedic implantable medical devices AU - Shirwaiker, Rohan A. AU - Samberg, Meghan E. AU - Cohen, Paul H. AU - Wysk, Richard A. AU - Monteiro-Riviere, Nancy A. T2 - WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY AB - Abstract Nanomaterials play a significant role in biomedical research and applications because of their unique biological, mechanical, and electrical properties. In recent years, they have been utilized to improve the functionality and reliability of a wide range of implantable medical devices ranging from well‐established orthopedic residual hardware devices (e.g., hip implants) that can repair defects in skeletal systems to emerging tissue engineering scaffolds that can repair or replace organ functions. This review summarizes the applications and efficacies of these nanomaterials that include synthetic or naturally occurring metals, polymers, ceramics, and composites in orthopedic implants, the largest market segment of implantable medical devices. The importance of synergistic engineering techniques that can augment or enhance the performance of nanomaterial applications in orthopedic implants is also discussed, the focus being on a low‐intensity direct electric current (LIDC) stimulation technology to promote the long‐term antibacterial efficacy of oligodynamic metal‐based surfaces by ionization, while potentially accelerating tissue growth and osseointegration. While many nanomaterials have clearly demonstrated their ability to provide more effective implantable medical surfaces, further decisive investigations are necessary before they can translate into medically safe and commercially viable clinical applications. The article concludes with a discussion about some of the critical impending issues with the application of nanomaterials‐based technologies in implantable medical devices, and potential directions to address these. WIREs Nanomed Nanobiotechnol 2013, 5:191–204. doi: 10.1002/wnan.1201 This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement DA - 2013/// PY - 2013/// DO - 10.1002/wnan.1201 VL - 5 IS - 3 SP - 191-204 SN - 1939-0041 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84876463086&partnerID=MN8TOARS ER - TY - JOUR TI - Driver distraction and performance effects of highway logo sign design AU - Zhang, Yu AU - Harris, Elizabeth AU - Rogers, Meghan AU - Kaber, David AU - Hummer, Joseph AU - Rasdorf, William AU - Hu, Jia T2 - APPLIED ERGONOMICS AB - Driver distraction and safety concerns have been identified for new highway logo sign configurations. This study assessed driver perception of logo signs and distraction under nine-panel, overflow-combination, or standard six-panel formats. A nine-panel sign has nine business panels within a single sign; a six-panel sign has six panels within a sign; an overflow-combination consists of a standard six-panel sign and a six-panel sign displaying two different services (e.g., food and gas). In this study, twenty-four participants searched for target food business logos while driving in a high-fidelity driving simulation under each signage condition. Gas and lodging signs were also displayed along the road in conventional six-panel formats. Dependent variables included signal detection, visual attention allocation, and vehicle control measures. Experiment results showed nine-panel signs drew greater visual attention and produced lower average speed than overflow-combination signs, and produced a lower speeding percentage compared to six-panel signs. However, there was no evidence the new configurations (nine-panel and overflow) caused substantive performance changes with safety implications. This study suggested the use of nine-panel and overflow-combination logo signs may be suitable for interchanges where there are more than six qualifying businesses in a category in terms of driver performance and safety. DA - 2013/5// PY - 2013/5// DO - 10.1016/j.apergo.2012.10.009 VL - 44 IS - 3 SP - 472-479 SN - 1872-9126 KW - Roadway logo signs KW - Driving simulation KW - Driver performance KW - Driver distraction KW - Highway safety ER - TY - JOUR TI - Agent-based simulation of affordance-based human behaviors in emergency evacuation AU - Joo, Jaekoo AU - Kim, Namhun AU - Wysk, Richard A. AU - Rothrock, Ling AU - Son, Young-Jun AU - Oh, Yeong-gwang AU - Lee, Seungho T2 - SIMULATION MODELLING PRACTICE AND THEORY AB - Complex cognitive processes corresponding to human control behaviors cannot be easily inferred using (1) a logical rule-based model, (2) a statistical model, or (3) an analytical predictive model. Predicting human behaviors in complex and uncertain environments like emergency evacuation is considered almost impossible (at least NP hard) in systems theory. In this paper, we explore simulating human behaviors using affordance-based finite state automata (FSA) modeling, based on the ecological concept of affordance theory. To this end, we introduce the conceptual and generic framework of affordance-based human behavior simulation developed through our previous work. Following the generic framework, formal simulation models of affordance-based human behaviors are developed, especially for emergency evacuation, to mimic perception-based dynamic human actions interacting with emergent environmental changes, such as fire. A “warehouse fire evacuation” case is used to demonstrate the applicability of the proposed framework. The human action planning algorithms in the simulation model are developed and implemented using the Adjusted Floor Field Indicators, which represent not only the evacuee’s prior knowledge of the floor layout but the perceivable information about dynamic environmental changes. The results of our simulation study verify that the proposed framework accurately simulates human fire evacuation behavior. The proposed framework is expected to capture the natural manner in which humans behave in emergency evacuation and enhance the simulation fidelity of analyses and predictions of perceptual human behaviors/responses in the systems by incorporating cognitive intent into human behavior simulations. DA - 2013/3// PY - 2013/3// DO - 10.1016/j.simpat.2012.12.007 VL - 32 SP - 99-115 SN - 1878-1462 KW - Human behavior KW - Emergency evacuation KW - Affordance theory KW - Finite state automata KW - Agent-based simulation ER - TY - BOOK TI - The Eighth Chinese Symposium on Mathematical Programming AU - Bai, Yanqin AU - Fang, Shu-Cherng AU - Fang, Weiwu AU - Han, Jiye AU - Xiu, Naihua A3 - Feng, Shu-Cherng A3 - Bai, Y. A3 - Fang, W. A3 - Han, J. A3 - Xiu, N. DA - 2013/// PY - 2013/// DO - 10.1080/02331934.2013.795052 VL - 62 SE - 429-430 ER - TY - JOUR TI - Direct fabrication of high-resolution three-dimensional polymeric scaffolds using electrohydrodynamic hot jet plotting AU - Wei, Chuang AU - Dong, Jingyan T2 - Journal of Micromechanics and Microengineering AB - This paper presents the direct three-dimensional (3D) fabrication of polymer scaffolds with sub-10 µm structures using electrohydrodynamic jet (EHD-jet) plotting of melted thermoplastic polymers. Traditional extrusion-based fabrication approaches of 3D periodic porous structures are very limited in their resolution, due to the excessive pressure requirement for extruding highly viscous thermoplastic polymers. EHD-jet printing has become a high-resolution alternative to other forms of nozzle deposition-based fabrication approaches by generating micro-scale liquid droplets or a fine jet through the application of a large electrical voltage between the nozzle and the substrate. In this study, we successfully apply EHD-jet plotting technology with melted biodegradable polymer (polycaprolactone, or PCL) for the fabrication of 2D patterns and 3D periodic porous scaffold structures in potential tissue engineering applications. Process conditions (e.g. electrical voltage, pressure, plotting speed) have been thoroughly investigated to achieve reliable jet printing of fine filaments. We have demonstrated for the first time that the EHD-jet plotting process is capable of the fabrication of 3D periodic structures with sub-10 µm resolution, which has great potential in advanced biomedical applications, such as cell alignment and guidance. DA - 2013/// PY - 2013/// DO - 10.1088/0960-1317/23/2/025017 VL - 23 IS - 2 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84878127942&partnerID=MN8TOARS ER - TY - JOUR TI - Computable representation of the cone of nonnegative quadratic forms over a general second-order cone and its application to completely positive programming AU - Tian, Ye AU - Fang, Shu-Cherng AU - Deng, Zhibin AU - Xing, Wenxun T2 - Journal of Industrial and Management Optimization AB - In this paper, we provide a computable representation of the cone of nonnegative quadratic forms over a general nontrivial second-order cone using linear matrix inequalities (LMI). By constructing a sequence of such computable cones over a union of second-order cones, an efficient algorithm is designed to find an approximate solution to a completely positive programming problem using semidefinite programming techniques. In order to accelerate the convergence of the approximation sequence, an adaptive scheme is adopted, and ``reformulation-linearization technique'' (RLT) constraints are added to further improve its efficiency. DA - 2013/4// PY - 2013/4// DO - 10.3934/jimo.2013.9.701 VL - 9 IS - 3 SP - 701-719 J2 - JIMO LA - en OP - SN - 1547-5816 UR - http://dx.doi.org/10.3934/jimo.2013.9.701 DB - Crossref ER - TY - JOUR TI - Associations among exercise duration, lameness severity, and hip joint range of motion in Labrador Retrievers with hip dysplasia AU - Greene, Laura M. AU - Marcellin-Little, Denis J. AU - Laselles, B. Duncan X. T2 - JAVMA-JOURNAL OF THE AMERICAN VETERINARY MEDICAL ASSOCIATION AB - To evaluate factors associated with lameness severity and hip joint range of motion in dogs with hip dysplasia and to assess the association between hip joint range of motion and degree of lameness.Prospective case series.60 client-owned Labrador Retrievers with hip dysplasia.Owners completed a questionnaire regarding their dogs' daily exercise duration and type (i.e., low impact vs high impact) and lifestyle. Range of motion of affected hip joints was measured with a transparent plastic goniometer. The presence of subluxation or luxation of hip joints as a consequence of hip dysplasia and the size of the largest osteophytes or enthesophytes of hip joints on ventrodorsal radiographic images of the pelvis were recorded. Multivariate analyses were performed to identify factors associated with lameness, loss of hip joint flexion, and loss of hip joint extension and to identify factors associated with the presence of large osteophytes.Exercise was associated with a decrease in the severity of lameness in dogs with hip dysplasia. The strength of this inverse relationship increased with longer exercise duration. Lameness was more severe in dogs with hip joint luxation than in dogs without luxation. Hip joint extension was 1° lower for each year of age, and osteophyte or enthesophyte size was 1 mm larger with each 3-year increase in age.Longer daily exercise duration was associated with lower lameness scores in dogs with hip dysplasia. Dogs with hip joint luxation secondary to hip dysplasia had higher lameness scores than did dogs without hip joint luxation. DA - 2013/6/1/ PY - 2013/6/1/ DO - 10.2460/javma.242.11.1528 VL - 242 IS - 11 SP - 1528-1533 SN - 1943-569X ER - TY - JOUR TI - Selecting optimal selling format of a product in B2C online auctions with boundedly rational customers AU - Jiang, Zhong-Zhong AU - Fang, Shu-Cherng AU - Fan, Zhi-Ping AU - Wang, Dingwei T2 - EUROPEAN JOURNAL OF OPERATIONAL RESEARCH AB - The advancement of Internet technology has enabled new formats for selling products in the B2C online auctions. At present, on the major online auction sites, there exist three popular selling formats, namely, the posted price, pure auction and buy-price auction formats. It is an important decision problem for a firm to select the most profitable format to sell its products through the Internet. The customer behavior is of course a crucial element of the decision process. To the best of our knowledge, most models available today assume that customers are perfectly rational. To better understand the decision process, in this paper, we incorporate the concept of bounded rationality into consideration. We first present a “behavior choice function” to characterize the behavior of the customers with bounded rationality. Then corresponding to each selling format, we construct a revenue model based on the bounded rationality for analysis. Finally, we conduct some elaborate computational experiments to investigate the performance of each revenue model for developing new managerial insights. Our computational results clearly demonstrate how the bounded rationality of customer behavior affects the choice of a preferable selling format for a B2C firm in an online auction. DA - 2013/4/1/ PY - 2013/4/1/ DO - 10.1016/j.ejor.2012.10.003 VL - 226 IS - 1 SP - 139-153 SN - 1872-6860 KW - E-commerce KW - Bounded rationality KW - Customer behavior KW - Online auctions KW - Revenue management ER - TY - JOUR TI - Evaluation of gait-related variables in lean and obese dogs at a trot AU - Brady, Robert B. AU - Sidiropoulos, Alexis N. AU - Bennett, Hunter J. AU - Rider, Patrick M. AU - Marcellin-Little, Denis J. AU - DeVita, Paul T2 - AMERICAN JOURNAL OF VETERINARY RESEARCH AB - Abstract Objective —To assess differences in sagittal plane joint kinematics and ground reaction forces between lean and obese adult dogs of similar sizes at 2 trotting velocities. Animals —16 adult dogs. Procedures —Dogs with body condition score (BCS) of 8 or 9 (obese dogs; n = 8) and dogs with BCS of 4 or 5 (lean dogs; 8) on a 9-point scale were evaluated. Sagittal plane joint kinematic and ground reaction force data were obtained from dogs trotting at 1.8 and 2.5 m/s with a 3-D motion capture system, a force platform, and 12 infrared markers placed on bony landmarks. Results —Mean stride lengths for forelimbs and hind limbs at both velocities were shorter in obese than in lean dogs. Stance phase range of motion (ROM) was greater in obese dogs than in lean dogs for shoulder (28.2° vs 20.6°), elbow (23.6° vs 16.4°), hip (27.2° vs 22.9°), and tarsal (38.9° vs 27.9°) joints at both velocities. Swing phase ROM was greater in obese dogs than in lean dogs for elbow (61.2° vs 53.7°) and hip (34.4° vs 29.8°) joints. Increased velocity was associated with increased stance ROM in elbow joints and increased stance and swing ROM in hip joints of obese dogs. Obese dogs exerted greater peak vertical and horizontal ground reaction forces than did lean dogs. Body mass and peak vertical ground reaction force were significantly correlated. Conclusions and Clinical Relevance —Greater ROM detected during the stance phase and greater ground reaction forces in the gait of obese dogs, compared with lean dogs, may cause greater compressive forces within joints and could influence the development of osteoarthritis. DA - 2013/5// PY - 2013/5// DO - 10.2460/ajvr.74.5.757 VL - 74 IS - 5 SP - 757-762 SN - 0002-9645 ER - TY - JOUR TI - Emotional State Classification in Patient-Robot Interaction Using Wavelet Analysis and Statistics-Based Feature Selection AU - Swangnetr, Manida AU - Kaber, David B. T2 - IEEE TRANSACTIONS ON HUMAN-MACHINE SYSTEMS AB - Due to a major shortage of nurses in the U.S., future healthcare service robots are expected to be used in tasks involving direct interaction with patients. Consequently, there is a need to design nursing robots with the capability to detect and respond to patient emotional states and to facilitate positive experiences in healthcare. The objective of this study was to develop a new computational algorithm for accurate patient emotional state classification in interaction with nursing robots during medical service. A simulated medicine delivery experiment was conducted at two nursing homes using a robot with different human-like features. Physiological signals, including heart rate (HR) and galvanic skin response (GSR), as well as subjective ratings of valence (happy-unhappy) and arousal (excited-bored) were collected on elderly residents. A three-stage emotional state classification algorithm was applied to these data, including: (1) physiological feature extraction; (2) statistical-based feature selection; and (3) a machine-learning model of emotional states. A pre-processed HR signal was used. GSR signals were nonstationary and noisy and were further processed using wavelet analysis. A set of wavelet coefficients, representing GSR features, was used as a basis for current emotional state classification. Arousal and valence were significantly explained by statistical features of the HR signal and GSR wavelet features. Wavelet-based de-noising of GSR signals led to an increase in the percentage of correct classifications of emotional states and clearer relationships among the physiological response and arousal and valence. The new algorithm may serve as an effective method for future service robot real-time detection of patient emotional states and behavior adaptation to promote positive healthcare experiences. DA - 2013/1// PY - 2013/1// DO - 10.1109/tsmca.2012.2210408 VL - 43 IS - 1 SP - 63-75 SN - 2168-2305 KW - Emotions KW - machine learning KW - physiological variables KW - regression analysis KW - service robots KW - wavelet analysis. ER - TY - JOUR TI - Detecting copositivity of a symmetric matrix by an adaptive ellipsoid-based approximation scheme AU - Deng, Zhibin AU - Fang, Shu-Cherng AU - Jin, Qingwei AU - Xing, Wenxun T2 - European Journal of Operational Research AB - It is co-NP-complete to decide whether a given matrix is copositive or not. In this paper, this decision problem is transformed into a quadratic programming problem, which can be approximated by solving a sequence of linear conic programming problems defined on the dual cone of the cone of nonnegative quadratic functions over the union of a collection of ellipsoids. Using linear matrix inequalities (LMI) representations, each corresponding problem in the sequence can be solved via semidefinite programming. In order to speed up the convergence of the approximation sequence and to relieve the computational effort of solving linear conic programming problems, an adaptive approximation scheme is adopted to refine the union of ellipsoids. The lower and upper bounds of the transformed quadratic programming problem are used to determine the copositivity of the given matrix. DA - 2013/8// PY - 2013/8// DO - 10.1016/j.ejor.2013.02.031 VL - 229 IS - 1 SP - 21-28 J2 - European Journal of Operational Research LA - en OP - SN - 0377-2217 UR - http://dx.doi.org/10.1016/j.ejor.2013.02.031 DB - Crossref KW - Conic programming KW - Copositive KW - Cone of nonnegative quadratic functions KW - Adaptive approximation scheme ER - TY - JOUR TI - DEVELOPMENT OF A CANINE STIFLE COMPUTER MODEL TO EVALUATE CRANIAL CRUCIATE LIGAMENT DEFICIENCY AU - Brown, Nathan P. AU - Bertocci, Gina E. AU - Marcellin-Little, Denis J. T2 - JOURNAL OF MECHANICS IN MEDICINE AND BIOLOGY AB - The objective of this study was to develop a three-dimensional (3D) quasi-static rigid body canine pelvic limb computer model simulating a cranial cruciate ligament (CrCL) intact and CrCL-deficient stifle during walking stance to describe stifle biomechanics. The model was based on a five-year-old neutered male Golden Retriever (33 kg) with no orthopedic or neurologic disease. Skeletal geometry and ligament anatomy determined from computed tomography (CT), optimized muscle forces, motion capture kinematics, and force platform ground reaction forces were used to develop the model. Ligament loads, tibial translation, tibial rotation, and femoromeniscal contact forces were compared across the intact and CrCL-deficient stifle. The CrCL was found to be the primary intact stifle load-bearing ligament, and the caudal cruciate ligament was the primary CrCL-deficient stifle load-bearing ligament. Normalized tibial translation and rotation were 0.61 mm/kg and 0.14 degrees/kg, respectively. Our model confirmed that the CrCL stabilizes the intact stifle and limits tibial translation and rotation. Model verification was confirmed through agreement with experimentally measured kinematics and previous in vivo, in vitro, and mathematical model studies. Parametric analysis indicated outcome measure sensitivity to ligament pre-strain. Computer modeling could be useful to further investigate stifle biomechanics associated with surgical stabilization techniques. DA - 2013/4// PY - 2013/4// DO - 10.1142/s0219519413500437 VL - 13 IS - 2 SP - SN - 1793-6810 KW - Canine stifle (knee) computer model KW - cranial cruciate ligament deficiency KW - biomechanics ER - TY - JOUR TI - A Cognitive Modeling Approach to Decision Support Tool Design for Anesthesia Provider Crisis Management AU - Segall, Noa AU - Kaber, David B. AU - Taekman, Jeffrey M. AU - Wright, Melanie C. T2 - INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION AB - Prior research has revealed existing operating room (OR) patient monitors to provide limited support for prompt and accurate decision making by anesthesia providers during crises. Decision support tools (DSTs) developed for this purpose typically alert the anesthesia provider to existence of a problem but do not recommend a treatment plan. There is a need for a human-centered approach to the design and development of a crisis management DST. A hierarchical task analysis was conducted to identify anesthesia provider procedures in detecting, diagnosing, and treating a critical incident and a cognitive task analysis to elicit goals, decisions, and information requirements. This information was coded in a computational cognitive model using GOMS (Goals, Operators, Methods, Selection rules) Language. An OR monitor interface was prototyped to present output from the cognitive model following ecological interface design principles. A preliminary assessment of the DST was performed with anesthesiology and usability experts. The anesthesiologists indicated they would use the tool in the perioperative environment and would recommend its use by junior anesthesia providers. Future research will focus on formal validation of the DST design approach and comparison of tool output to actual anesthesia provider decisions in real or simulated crises. DA - 2013/1/1/ PY - 2013/1/1/ DO - 10.1080/10447318.2012.681220 VL - 29 IS - 2 SP - 55-66 SN - 1532-7590 ER - TY - JOUR TI - Q-Tip Empirical Evaluation of Hand Hygiene Compliance AU - Venkitasubramanian, Akshay AU - Yannayon, Jamie AU - Kim, Bomin AU - Donahue, Devin AU - Koromia, George A. AU - Doshi, Niyati AU - Venkateswaran, Aravind AU - Arellano, Consuelo AU - Mazur, Lukasz M. T2 - AMERICAN JOURNAL OF MEDICAL QUALITY AB - The online version of this article can be found at:€DOI: 10.1177/1062860612464733American Journal of Medical Quality 2013 28: 81 originally published online 15 November 2012Venkateswaran, Consuelo Arellano and Lukasz M. MazurAkshay Venkitasubramanian, Jamie Yannayon, Bomin Kim, Devin Donahue, George A. Koromia, Niyati Doshi, Aravind DA - 2013/// PY - 2013/// DO - 10.1177/1062860612464733 VL - 28 IS - 1 SP - 81-81 SN - 1062-8606 ER - TY - JOUR TI - Modeling of uniaxial compression in a 3D periodic re-entrant lattice structure AU - Yang, Li AU - Harrysson, Ola AU - West, Harvey AU - Cormier, Denis T2 - JOURNAL OF MATERIALS SCIENCE DA - 2013/2// PY - 2013/2// DO - 10.1007/s10853-012-6892-2 VL - 48 IS - 4 SP - 1413-1422 SN - 0022-2461 ER - TY - JOUR TI - An entropy based central cutting plane algorithm for convex min-max semi-infinite programming problems AU - Zhang, LiPing AU - Fang, Shu-Cherng AU - Wu, Soon-Yi T2 - Science China Mathematics DA - 2013/1// PY - 2013/1// DO - 10.1007/s11425-012-4502-z VL - 56 IS - 1 SP - 201–211 SN - 1674-7283 1869-1862 UR - http://dx.doi.org/10.1007/s11425-012-4502-z KW - semi-infinite programming KW - min-max problem KW - central cutting plane KW - entropy ER - TY - CONF TI - Two-stage stochastic view selection for data-analysis queries AU - Huang, R. AU - Chirkova, R. AU - Fathi, Y. C2 - 2013/// C3 - Advances in databases and information systems DA - 2013/// VL - 186 SP - 115-123 ER - TY - JOUR TI - The impact of simultaneous continuous improvement in setup time and repair time on manufacturing cycle times under uncertain conditions AU - Godinho Filho, Moacir AU - Uzsoy, Reha T2 - INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH AB - We develop a system dynamics model to examine the cumulative effects of continuous improvement programmes for repair and setup times on the cycle time of a simple single-stage production system. The relationship between system performance and repair and setup times is captured using the Factory Physics approach. We find that modest rates of improvement in multiple areas in parallel yield cumulative benefits over time comparable with those obtained by a large reduction in a single parameter, especially when there is significant uncertainty in the degree of improvement that can be obtained, or in the degree to which improvements can be sustained over time. These results provide an insight into the success of the Toyota Production System and related lean manufacturing approaches where continuous improvement is an ongoing activity across the work environment. DA - 2013/// PY - 2013/// DO - 10.1080/00207543.2011.652261 VL - 51 IS - 2 SP - 447-464 SN - 1366-588X KW - continuous improvement KW - setup time KW - repair time KW - manufacturing KW - cycle times KW - system dynamics ER - TY - JOUR TI - The association of breast density with breast cancer mortality in African American and white women screened in community practice AU - Zhang, Shengfan AU - Ivy, Julie S. AU - Diehl, Kathleen M. AU - Yankaskas, Bonnie C. T2 - BREAST CANCER RESEARCH AND TREATMENT DA - 2013/1// PY - 2013/1// DO - 10.1007/s10549-012-2310-3 VL - 137 IS - 1 SP - 273-283 SN - 1573-7217 KW - Breast cancer KW - Mortality KW - Breast density KW - Mammography screening ER - TY - JOUR TI - Comparing traditional and fuzzy-set solutions to (Q, r) inventory systems with discrete lead-time distributions AU - Wu, X. M. AU - Warsing, D. P. T2 - Journal of Intelligent & Fuzzy Systems DA - 2013/// PY - 2013/// VL - 24 IS - 1 SP - 93-104 ER - TY - JOUR TI - An effective lower bound on L-max in a worker-constrained job shop AU - Lobo, Benjamin J. AU - Hodgson, Thom J. AU - King, Russell E. AU - Thoney, Kristin A. AU - Wilson, James R. T2 - COMPUTERS & OPERATIONS RESEARCH AB - A common industrial operation is a dual resource constrained job shop where: (a) the objective is to minimize L max , the maximum job lateness; (b) machines are organized into groups; and (c) each worker is assigned to a specific machine group. Because this problem is NP-hard, finding optimal solutions by enumeration is impractical. This paper details a procedure to compute a lower bound on L max that will be used in follow-up work to effectively evaluate the absolute performance of heuristic solutions. Given an allocation of workers to machine groups, a lower bound on L max is first computed for each machine group using a network-flow formulation. The lower bound on L max for the job shop is the largest of the lower bounds for the machine groups. A search algorithm then finds a worker allocation yielding the smallest such lower bound on L max for the job shop; and the latter quantity is our proposed lower bound on L max . Given a worker allocation, we use the Virtual Factory (a heuristic scheduler developed by Hodgson et al. in 1998) to generate a schedule. Experiments with a wide variety of job shops indicated that the proposed lower bound on L max could often be achieved by a Virtual Factory schedule based on the worker allocation yielding this lower bound. However, there were problem instances for which other worker allocations enabled the Virtual Factory to generate better schedules. Follow-up work provides optimality criteria, and heuristics to find improved allocations if these criteria are not satisfied. DA - 2013/1// PY - 2013/1// DO - 10.1016/j.cor.2012.07.003 VL - 40 IS - 1 SP - 328-343 SN - 1873-765X KW - Job shop scheduling KW - Dual resource constrained systems KW - Maximum lateness KW - Worker allocation ER -