TY - JOUR TI - Topology control for load shed recovery AU - Escobedo, A.R. AU - Moreno-Centeno, E. AU - Hedman, K.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 - 2014/// PY - 2014/// DO - 10.1109/TPWRS.2013.2286009 VL - 29 IS - 2 SP - 908-916 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897607427&partnerID=MN8TOARS ER - TY - CONF TI - Positioning automated guided vehicles in a general guide-path layout C2 - 2014/1/1/ C3 - IIE Annual Conference and Expo 2014 DA - 2014/1/1/ ER - TY - JOUR TI - Design of Closed Loop Supply Chain Networks AU - Pazhani, Subramanian AU - Ravindran, A. Ravi T2 - International Journal of Business Analytics AB - Given the importance of operating and managing forward and reverse supply chains in an integrated manner, this article considers an integrated four-stage supply chain network with forward and reverse product flows. We consider a closed loop supply chain (CLSC) network with primarily commercial returns, which could be potentially recovered by light repair operations or by refurbishing. The annual estimate of commercial returns in the United States is in excess of $100 billion. This paper discusses the optimal design of a CLSC network.A mixed integer linear programming (MILP) model is developed to determine the optimal locations of the facilities and the distribution of flows between facilities in the CLSC to maximize the total profit. The model is illustrated using a realistic example applicable to the electronics industries. Even though recycling and refurbishing add cost, the overall supply chain profit increases due to a reduction in the raw material cost. Sensitivity analysis is carried out to determine the effect of return percentage and varying demands of customers who are willing to buy refurbished products. The analysis show that the total supply chain profit increases with the increase in refurbishing activity. Finally, changes in the network design with respect to the uncertainty in these return parameters are also studied. The results show that the changes in return parameters lead to changes in optimal network design implying the need to explicitly consider the uncertainty in these return parameters. DA - 2014/1/1/ PY - 2014/1/1/ DO - 10.4018/ijban.2014010104 VL - 1 IS - 1 SP - 43-66 LA - ng OP - SN - 2334-4547 2334-4555 UR - http://dx.doi.org/10.4018/ijban.2014010104 DB - Crossref ER - TY - CONF TI - Positioning Automated Guided Vehicles in a General Guide-Path Layout, AU - Mendoza, A AU - Ventura, Jose AU - Subramanian, Pazhani C2 - 2014/// C3 - 13th International Material Handling Research Colloquium, Cincinnati, Ohio, USA DA - 2014/// ER - TY - CONF TI - Positioning Automated Guided Vehicles in a General Guide-Path Layout AU - Pazhani, Subramanian AU - Ventura, José A AU - Mendoza, Abraham T2 - Institute of Industrial Engineers-Publisher C2 - 2014/// C3 - IIE Annual Conference. Proceedings DA - 2014/// SP - 1723 ER - TY - THES TI - Technology for Improving the Quality of Life for Patients Suffering from Vascular Insufficiency AU - Livingston, F.J. DA - 2014/// PY - 2014/// M3 - Doctor of Philosophy PB - North Carolina State University ER - TY - CONF TI - Time-optimal feed-rate scheduling for nanopositioning systems with confined contouring error AU - Bharathi, A. AU - Dong, J. C2 - 2014/// C3 - Transactions of the North American Manufacturing Research Institution of SME DA - 2014/// VL - 42 SP - 372-380 M1 - January UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84938059294&partnerID=MN8TOARS ER - TY - JOUR TI - Super-resolution electrohydrodynamic (EHD) 3D printing of micro-structures using phase-change inks AU - Han, Y. AU - Wei, C. AU - Dong, J. T2 - Manufacturing Letters AB - This paper presents a super-resolution 3D printing process using electrohydrodynamic (EHD) printing technology for the direct fabrication of micro-scale structures with phase-change inks (i.e. wax). In this work, we successfully apply EHD printing process for phase-change ink (wax), which is widely used modeling and supporting material for additive manufacturing and 3D printing, to achieve micro-scale droplet dimension. Moreover, a Finite Element Analysis (FEA) model is developed to predict the droplet formation and droplet size of the EHD printing at different printing voltage. The EHD printing process is capable of producing high aspect-of-ratio 3D structures with sub-10 μm feature resolution. DA - 2014/// PY - 2014/// DO - 10.1016/j.mfglet.2014.07.005 VL - 2 IS - 4 SP - 96-99 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84908304909&partnerID=MN8TOARS ER - TY - CONF TI - Drop-on-demand E-Jet printing of continuous features with AC-pulse modulation on highly insulating substrates AU - Wei, C. AU - Qin, H. AU - Chiu, C.-P. AU - Lee, Y.-S. AU - Dong, J. C2 - 2014/// C3 - Transactions of the North American Manufacturing Research Institution of SME DA - 2014/// VL - 42 SP - 345-352 M1 - January UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84938054378&partnerID=MN8TOARS ER - TY - CONF TI - AC-pulse modulated electrohydrodynamic (EHD) direct printing of conductive micro silver tracks for micro-manufacturing AU - Qin, H. AU - Wei, C. AU - Dong, J. AU - Lee, Y.-S. C2 - 2014/// C3 - FAIM 2014 - Proceedings of the 24th International Conference on Flexible Automation and Intelligent Manufacturing: Capturing Competitive Advantage via Advanced Manufacturing and Enterprise Transformation DA - 2014/// SP - 763-770 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84960928060&partnerID=MN8TOARS ER - TY - CONF TI - Analysis of Release Changes with Fixed Lead Time and Capacity AU - Lin, P.C. AU - Uzsoy, R. T2 - Industrial and Systems Engineering Research Conference C2 - 2014/5// CY - Montreal, PQ, Canada DA - 2014/5// PY - 2014/5// ER - TY - JOUR TI - AGGREGATE PLANNING USING TRANSPORTATION METHOD: A CASE STUDY IN CABLE INDUSTRY T2 - International Journal of Managing Value and Supply Chains DA - 2014/9// PY - 2014/9// UR - https://airccse.org/journal/mvsc/vol5.html ER - TY - ER - TY - BOOK TI - Essays in Production, Project Planning and Scheduling T2 - International Series in Operations Research & Management Science A3 - Pulat, P. Simin A3 - Sarin, Subhash C. A3 - Uzsoy, Reha AB - From the Preface: This festschrift is devoted to recognize the career of a man who not only witnessed the growth of operations research from its inception, but also contributed significantly to this g DA - 2014/// PY - 2014/// DO - 10.1007/978-1-4614-9056-2 PB - Springer US SN - 9781461490555 9781461490562 UR - http://dx.doi.org/10.1007/978-1-4614-9056-2 ER - TY - CHAP TI - A Human Factors Study of Graphical Passwords Using Biometrics AU - Riggan, Benjamin S. AU - Snyder, Wesley E. AU - Wang, Xiaogang AU - Feng, Jing T2 - Pattern Recognition. GCPR 2014 A2 - Jiang, X. A2 - Hornegger, J. A2 - Koch, R. T3 - Lecture Notes in Computer Science AB - One mode of authentication used in modern computing systems is graphical passwords. Graphical passwords are becoming more popular because touch-sensitive and pen-sensitive technologies are becoming ubiquitous. In this paper, we construct the “BioSketch” database, which is a general database of sketch-based passwords (SkPWs) with pressure information used as a biometric property. The BioSketch database is created so that recognition approaches may be commensurable with the benchmark performances. Using this database, we are also able to study the human-computer interaction (HCI) process for SkPWs. In this paper, we compare a generalized SKS recognition algorithm with the Fréchet distance in terms of the intra/inter-class variations and performances. The results show that the SKS-based approach achieves as much as a 7 % and 17 % reduction in equal error rate (EER) for random and skilled forgeries respectively. PY - 2014/// DO - 10.1007/978-3-319-11752-2_38 SP - 464–475 PB - Springer International Publishing SN - 9783319117515 9783319117522 SV - 8753 UR - http://dx.doi.org/10.1007/978-3-319-11752-2_38 ER - TY - CHAP TI - Refined EM Method for Solving Linearly Constrained Global Optimization Problems AU - Yu, Lu AU - Fang, Shu-Cherng T2 - Essays in Production, Project Planning and Scheduling A2 - Pulat, P. A2 - Sarin, S. A2 - Uzsoy, R. T3 - International Series in Operations Research & Management Science AB - The Electromagnetism-like Mechanism (EM) has been widely used for solving global optimization problems with box-constrained variables. It is a population-based stochastic search method. Since the method uses function evaluations only at each step, it does not require any special information or structure of the objective function. In this article, we extend the original EM for solving optimization problems with linear constraints. The proposed method mimics the behavior of electrically charged particles that are restricted in the feasible region formed by the linear constraints. The underlying idea is to direct the sample points to some attractive regions of the feasible domain. In refined EM, the major steps of the original EM are redesigned to handle the explicit linear constraints in an efficient manner to find global optimal solutions. The proposed method is evaluated using many known test problems and is compared with some existing methods. Computational results show that without using the higher-order information, refined EM converges rapidly (in terms of the number of functions evaluations) to the global optimal solutions and produces better results than other known methods in solving problems of a varying degree of difficulty. PY - 2014/// DO - 10.1007/978-1-4614-9056-2_4 SP - 69–90 PB - Springer US SN - 9781461490555 9781461490562 SV - 200 UR - http://dx.doi.org/10.1007/978-1-4614-9056-2_4 ER - TY - JOUR TI - In celebration of Professor Min-yi Yue’s 95th birthday AU - Fang, S. AU - Bai, Y. AU - Fang, W. AU - Han, J. AU - Xiu, N. T2 - Optimization DA - 2014/5/13/ PY - 2014/5/13/ DO - 10.1080/02331934.2014.918768 VL - 63 IS - 6 SP - 827–828 SN - 0233-1934 1029-4945 UR - http://dx.doi.org/10.1080/02331934.2014.918768 ER - TY - JOUR TI - ℓ1 Major Component Detection and Analysis (ℓ1 MCDA) in Three and Higher Dimensional Spaces AU - Deng, Zhibin AU - Lavery, John AU - Fang, Shu-Cherng AU - Luo, Jian T2 - Algorithms AB - Based on the recent development of two dimensional ℓ1 major component detection and analysis (ℓ1 MCDA), we develop a scalable ℓ1 MCDA in the n-dimensional space to identify the major directions of star-shaped heavy-tailed statistical distributions with irregularly positioned “spokes” and “clutters”. In order to achieve robustness and efficiency, the proposed ℓ1 MCDA in n-dimensional space adopts a two-level median fit process in a local neighbor of a given direction in each iteration. Computational results indicate that in terms of accuracy ℓ1 MCDA is competitive with two well-known PCAs when there is only one major direction in the data, and ℓ1 MCDA can further determine multiple major directions of the n-dimensional data from superimposed Gaussians or heavy-tailed distributions without and with patterned artificial outliers. With the ability to recover complex spoke structures with heavy-tailed noise and clutter in the data, ℓ1 MCDA has potential to generate better semantics than other methods. DA - 2014/8/19/ PY - 2014/8/19/ DO - 10.3390/a7030429 VL - 7 IS - 3 SP - 429-443 J2 - Algorithms LA - en OP - SN - 1999-4893 UR - http://dx.doi.org/10.3390/a7030429 DB - Crossref KW - multidimensional heavy-tailed distribution KW - l(1)-norm KW - major component KW - n-dimensional KW - outlier KW - pattern recognition KW - robust principal component analysis ER - TY - JOUR TI - Improving emergency service in rural areas: a bi-objective covering location model for EMS systems AU - Chanta, Sunarin AU - Mayorga, Maria E. AU - McLay, Laura A. T2 - Annals of Operations Research DA - 2014/// PY - 2014/// DO - 10.1007/s10479-011-0972-6 VL - 221 IS - 1 SP - 133–159 SN - 0254-5330 1572-9338 UR - http://dx.doi.org/10.1007/s10479-011-0972-6 KW - Emergency medical service KW - Facility location KW - Bi-objective optimization KW - Discrete optimization ER - TY - JOUR TI - Predicting Liver Transplant Capacity Using Discrete Event Simulation AU - Toro-Díaz, Hector AU - Mayorga, Maria E. AU - Barritt, A. Sidney AU - Orman, Eric S. AU - Wheeler, Stephanie B. T2 - Medical Decision Making AB - The number of liver transplants (LTs) performed in the US increased until 2006 but has since declined despite an ongoing increase in demand. This decline may be due in part to decreased donor liver quality and increasing discard of poor-quality livers. We constructed a discrete event simulation (DES) model informed by current donor characteristics to predict future LT trends through the year 2030. The data source for our model is the United Network for Organ Sharing database, which contains patient-level information on all organ transplants performed in the US. Previous analysis showed that liver discard is increasing and that discarded organs are more often from donors who are older, are obese, have diabetes, and donated after cardiac death. Given that the prevalence of these factors is increasing, the DES model quantifies the reduction in the number of LTs performed through 2030. In addition, the model estimatesthe total number of future donors needed to maintain the current volume of LTs and the effect of a hypothetical scenario of improved reperfusion technology.We also forecast the number of patients on the waiting list and compare this with the estimated number of LTs to illustrate the impact that decreased LTs will have on patients needing transplants. By altering assumptions about the future donor pool, this model can be used to develop policy interventions to prevent a further decline in this lifesaving therapy. To our knowledge, there are no similar predictive models of future LT use based on epidemiological trends. DA - 2014/11/12/ PY - 2014/11/12/ DO - 10.1177/0272989x14559055 VL - 35 IS - 6 SP - 784-796 J2 - Med Decis Making LA - en OP - SN - 0272-989X 1552-681X UR - http://dx.doi.org/10.1177/0272989x14559055 DB - Crossref KW - liver transplantation KW - organ donors KW - forecast KW - simulation ER - TY - JOUR TI - Towards evaluating and enhancing the reach of online health forums for smoking cessation AU - Stearns, M. AU - Nambiar, S. AU - Nikolaev, A. AU - Semenov, A. AU - McIntos, S. T2 - Network Modeling Analysis in Health Informatics and Bioinformatics AB - Online pro-health social networks facilitating smoking cessation through web-assisted interventions have flourished in the past decade. In order to properly evaluate and increase the impact of this form of treatment on society, one needs to understand and be able to quantify its reach, as defined within the widely-adopted RE-AIM framework. In the online communication context, user engagement is an integral component of reach. This paper quantitatively studies the effect of engagement on the users of the Alt.Support.Stop-Smoking forum that served the needs of an online smoking cessation community for more than ten years. The paper then demonstrates how online service evaluation and planning by social network analysts can be applied towards strategic interventions targeting increased user engagement in online health forums. To this end, the challenges and opportunities are identified in the development of thread recommendation systems using core-users as a strategic resource for effective and efficient spread of healthy behaviors, in particular smoking cessation. DA - 2014/12// PY - 2014/12// DO - 10.1007/s13721-014-0069-7 VL - 3 IS - 1 UR - http://dx.doi.org/10.1007/s13721-014-0069-7 KW - Social network analysis KW - Smoking cessation KW - Online forum communication KW - RE-AIM framework KW - Reach KW - Engagement KW - Intervention modeling ER - TY - CHAP TI - How Similar Are Quasi-, Regular, and Delaunay Triangulations in ℝ3? AU - Kim, Donguk AU - Cho, Youngsong AU - Kim, Jae-Kwan AU - Lee, Yuan-Shin AU - Kim, Deok-Soo T2 - Computational Science and Its Applications – ICCSA 2014 A2 - Murgante, B. T3 - Lecture Notes in Computer Science AB - Voronoi diagrams and quasi-triangulations are powerful for solving spatial problems among spherical particles with different radii. However, a quasi-triangulation can be a non-simplicial complex due to anomaly conditions. While quasi-triangulation is straightforward to use when it is a simplicial complex, it may not seem so if it is not. In this paper, we report the experimental statistics of showing the phenomena related with two fundamental issues: i) How frequently anomalies occur in the quasi-triangulation of the arrangement of spherical atoms in ℝ3 and ii) how much similar or dissimilar the three related structures (i.e., the quasi-triangulation, the regular triangulation, and the Delaunay triangulation of an atomic arrangements) are. The observations from the experiments are as follows: i) Anomalies occur extremely rarely in molecular structures and occur very rarely even in random sphere sets, and ii) the three dual structures of a given set of spheres are not similar. PY - 2014/// DO - 10.1007/978-3-319-09129-7_29 SP - 381–393 PB - Springer International Publishing SN - 9783319091280 9783319091297 SV - 8580 UR - http://dx.doi.org/10.1007/978-3-319-09129-7_29 ER - TY - JOUR TI - Quadratic Optimization over a Second-Order Cone with Linear Equality Constraints AU - Guo, Xiao-ling AU - Deng, Zhi-bin AU - Fang, Shu-Cherng AU - Wang, Zhen-bo AU - Xing, Wen-xun T2 - Journal of the Operations Research Society of China AB - This paper studies the nonhomogeneous quadratic programming problem over a second-order cone with linear equality constraints. When the feasible region is bounded, we show that an optimal solution of the problem can be found in polynomial time. When the feasible region is unbounded, a semidefinite programming (SDP) reformulation is constructed to find the optimal objective value of the original problem in polynomial time. In addition, we provide two sufficient conditions, under which, if the optimal objective value is finite, we show the optimal solution of SDP reformulation can be decomposed into the original space to generate an optimal solution of the original problem in polynomial time. Otherwise, a recession direction can be identified in polynomial time. Numerical examples are included to illustrate the effectiveness of the proposed approach. DA - 2014/3// PY - 2014/3// DO - 10.1007/S40305-013-0035-6 VL - 2 IS - 1 SP - 17–38 SN - 2194-668X 2194-6698 UR - http://dx.doi.org/10.1007/S40305-013-0035-6 KW - Quadratic programming KW - Linear conic programming KW - Second-order cone KW - Cone of nonnegative quadratic functions ER - TY - JOUR TI - Approximation of Irregular Geometric Data by Locally Calculated Univariate Cubic L1 Spline Fits AU - Wang, Ziteng AU - Lavery, John AU - Fang, Shu-Cherng T2 - Annals of Data Science AB - $$L^1$$ splines have been under development for interpolation and approximation of irregular geometric data. We investigate the advantages in terms of shape preservation and computational efficiency of calculating univariate cubic $$L^1$$ spline fits using a steepest-descent algorithm to minimize a global data-fitting functional under a constraint implemented by a local analysis-based interpolating-spline algorithm on 5-node windows. Comparison of these locally calculated $$L^1$$ spline fits with globally calculated $$L^1$$ spline fits previously reported in the literature indicates that the locally calculated spline fits preserve shape on the average slightly better than the globally calculated spline fits and are computationally more efficient because the locally-calculated-spline-fit algorithm can be parallelized. DA - 2014/3// PY - 2014/3// DO - 10.1007/S40745-014-0002-Z VL - 1 IS - 1 SP - 5–14 SN - 2198-5804 2198-5812 UR - http://dx.doi.org/10.1007/S40745-014-0002-Z ER - TY - BOOK TI - Network routing of snowplow with resource replenishment and plowing priorities formulation. Algorithm, and application AU - Hajibabai, L. AU - Nourbakhsh, S.M. AU - Ouyang, Y. AU - Peng, F. AB - The routing of snowplow trucks in urban and regional areas encompasses a variety of complex decisions, especially for jurisdictions with heavy snowfall. The main activities involve dispatching a fleet of snowplow trucks from a central depot or satellite facility to clean and spread salt and chemicals on the network links (i.e., snow routes). In this paper, a mixed integer linear program model is proposed to minimize the total operation time of all snowplow trucks needed to complete a given set of snow routes with multiple plowing priorities and to reduce the longest individual truck operation time. Customized construction and local search solution algorithms are developed and used to design snow routes for an empirical application. The computational results show that the proposed solution approach is able to solve the problem effectively and the model result outperforms the current solution in practice. The proposed models and algorithms are also incorporated into the development of a state-of-the-art snowplow routing software that can help planners optimize snow routes and evaluate options for resource allocation. DA - 2014/// PY - 2014/// DO - 10.3141/2440-03 VL - 2440 SE - 16-25 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84938513511&partnerID=MN8TOARS ER - TY - JOUR TI - Joint optimization of freight facility location and pavement infrastructure rehabilitation under network traffic equilibrium AU - Hajibabai, L. AU - Bai, Y. AU - Ouyang, Y. T2 - Transportation Research Part B: Methodological AB - Establishment of industry facilities often induces heavy vehicle traffic that exacerbates congestion and pavement deterioration in the neighboring highway network. While planning facility locations and land use developments, it is important to take into account the routing of freight vehicles, the impact on public traffic, as well as the planning of pavement rehabilitation. This paper presents an integrated facility location model that simultaneously considers traffic routing under congestion and pavement rehabilitation under deterioration. The objective is to minimize the total cost due to facility investment, transportation cost including traffic delay, and pavement life-cycle costs. Building upon analytical results on optimal pavement rehabilitation, the problem is formulated into a bi-level mixed-integer non-linear program (MINLP), with facility location, freight shipment routing and pavement rehabilitation decisions in the upper level and traffic equilibrium in the lower level. This problem is then reformulated into an equivalent single-level MINLP based on Karush–Kuhn–Tucker (KKT) conditions and approximation by piece-wise linear functions. Numerical experiments on hypothetical and empirical network examples are conducted to show performance of the proposed algorithm and to draw managerial insights. DA - 2014/// PY - 2014/// DO - 10.1016/j.trb.2014.02.003 VL - 63 SP - 38-52 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897836858&partnerID=MN8TOARS KW - Facility location KW - Traffic equilibrium KW - Pavement rehabilitation KW - Bi-level KW - Optimization ER - TY - JOUR TI - System factors to explain 2009 pandemic H1N1 state vaccination rates for children and high-risk adults in US emergency response to pandemic AU - Davila-Payan, Carlo AU - Swann, Julie AU - Wortley, Pascale M. T2 - Vaccine AB - During the 2009–2010 H1N1 pandemic, children and high-risk adults had priority for vaccination. Vaccine in short supply was allocated to states pro-rata by population, but vaccination rates as of January 2010 varied among states from 21.3% to 84.7% for children and 10.4% to 47.2% for high-risk adults. States had different campaign processes and decisions. To determine program and system factors associated with higher state pandemic vaccination coverage for children and high-risk adults during an emergency response with short supply of vaccine. Regression analysis of factors predicting state-specific H1N1 vaccination coverage in children and high-risk adults, including state campaign information, demographics, preventive or health-seeking behavior, preparedness funding, providers, state characteristics, and surveillance data. Our modeling explained variation in state-specific vaccination coverage with an adjusted R-squared of 0.82 for children and 0.78 for high-risk adults. We found that coverage of children was positively associated with programs focusing on school clinics and with a larger proportion of doses administered in public sites; negatively with the proportion of children in the population, and the proportion not visiting a doctor because of cost. The coverage for high-risk adults was positively associated with shipments of vaccine to “general access” locations, including pharmacy and retail, with the percentage of women with a Pap smear within the past 3 years and with past seasonal influenza vaccination. It was negatively associated with the expansion of vaccination to the general public by December 4, 2009. For children and high-risk adults, coverage was positively associated with the maximum number of ship-to-sites and negatively associated with the proportion of medically underserved population. Findings suggest that distribution and system decisions such as vaccination venues and providers targeted can positively impact vaccination rates for children and high-risk adults. Additionally, existing health infrastructure, health-seeking behaviors, and access affected coverage. DA - 2014/1// PY - 2014/1// DO - 10.1016/J.VACCINE.2013.11.018 VL - 32 IS - 2 SP - 246-251 J2 - Vaccine LA - en OP - SN - 0264-410X UR - http://dx.doi.org/10.1016/J.VACCINE.2013.11.018 DB - Crossref KW - Pandemic KW - Coverage KW - State-specific KW - Factors KW - Estimates KW - Children and high-risk adults ER - TY - JOUR TI - Editorial AU - Nam, Chang S. AU - Hill, Jeremy T2 - Brain-Computer Interfaces DA - 2014/1/2/ PY - 2014/1/2/ DO - 10.1080/2326263X.2014.882101 VL - 1 IS - 1 SP - 1-1 J2 - Brain-Computer Interfaces LA - en OP - SN - 2326-263X 2326-2621 UR - http://dx.doi.org/10.1080/2326263X.2014.882101 DB - Crossref ER - TY - JOUR TI - Scheduling food bank collections and deliveries to ensure food safety and improve access AU - Davis, Lauren B. AU - Sengul, Irem AU - Ivy, Julie S. AU - Brock, Luther G., III AU - Miles, Lastella T2 - Socio-Economic Planning Sciences AB - Food banks are privately-owned non-profit organizations responsible for the receipt, processing, storage, and distribution of food items to charitable agencies. These charitable agencies in turn distribute food to individuals at risk of hunger. Food banks receive donated food from national and local sources, such as The Emergency Food Assistance Program (TEFAP) and supermarkets. Local sources with frequent high-volume donations justify the use of food bank vehicles for collection. Food bank vehicles are also used to deliver food to rural charitable agencies that are located beyond a distance safe for perishable food to travel without spoilage. Due to limited funds, food banks can only afford to sparingly use their capital on non-food items. This requires exploring more cost effective food delivery and collection strategies. The goal of this paper is to develop transportation schedules that enable the food bank to both (i) collect food donations from local sources and (ii) to deliver food to charitable agencies. We identify satellite locations, called food delivery points (FDPs), where agencies can receive food deliveries. A set covering model is developed to determine the assignment of agencies to an FDP. Both vehicle capacity and food spoilage constraints are considered during assignment. Using the optimal assignment of agencies to FDPs, we identify a weekly transportation schedule that addresses collection and distribution of donated food and incorporates constraints related to food safety, operator workday, collection frequency, and fleet capacity. DA - 2014/9// PY - 2014/9// DO - 10.1016/J.SEPS.2014.04.001 VL - 48 IS - 3 SP - 175-188 J2 - Socio-Economic Planning Sciences LA - en OP - SN - 0038-0121 UR - http://dx.doi.org/10.1016/J.SEPS.2014.04.001 DB - Crossref KW - Food distribution KW - Hunger relief KW - Humanitarian logistics KW - Set covering KW - Vehicle routing ER - TY - JOUR TI - Exact solution approach for a class of nonlinear bilevel knapsack problems AU - Beheshti, B. AU - Özalt?n, O.Y. AU - Zare, M.H. AU - Prokopyev, O.A. T2 - Journal of Global Optimization DA - 2014/// PY - 2014/// DO - 10.1007/s10898-014-0189-8 VL - 61 IS - 2 SP - 291-310 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84922834588&partnerID=MN8TOARS KW - Bilevel programming KW - Integer programming KW - Value functions KW - Knapsack problem ER - TY - CONF TI - Multi-objective optimization of 3D packing problem in additive manufacturing AU - Wu, S. AU - Kay, M. AU - King, R. AU - Vila-Parrish, A. AU - Warsing, D. C2 - 2014/// C3 - IIE Annual Conference and Expo 2014 DA - 2014/// SP - 1485-1494 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84910090427&partnerID=MN8TOARS ER - TY - JOUR TI - Flexural properties of Ti6Al4V rhombic dodecahedron open cellular structures fabricated with electron beam melting AU - Horn, Timothy J. AU - Harrysson, Ola L.A. AU - Marcellin-Little, Denis J. AU - West, Harvey A. AU - Lascelles, B. Duncan X. AU - Aman, Ronald T2 - Additive Manufacturing AB - Open cellular structures fabricated in Ti6Al4V using the electron beam melting (EBM) process have been proposed for tissue scaffolds and low stiffness implants that approximate the properties of bone. The properties of these structures, regardless of cell geometry, have often been determined through compressive testing, and very few of these studies have investigated the flexural properties. For certain types of implants that are designed to fill very large segmental defects in appendicular bones, such as those used in limb sparing, compression testing does not provide the necessary insight into the complex loading states typical of bending. In this study, EBM-fabricated Ti6Al4V prismatic bars, populated with rhombic dodecahedron unit cells of various sizes and relative densities, were subjected to four-point flexure tests. While the results generally follow the power scaling models of Gibson and Ashby, the use of these models as a design tool is limited by machine resolution, particularly when producing structures with small pore sizes required for bone ingrowth. DA - 2014/10// PY - 2014/10// DO - 10.1016/J.ADDMA.2014.05.001 VL - 1-4 SP - 2-11 J2 - Additive Manufacturing LA - en OP - SN - 2214-8604 UR - http://dx.doi.org/10.1016/J.ADDMA.2014.05.001 DB - Crossref ER - TY - JOUR TI - Reply AU - Gellad, Ziad F. AU - Taheri, Javad T2 - Clinical Gastroenterology and Hepatology AB - We thank Dr Kisloff for his comments on our recent article describing efficiency metrics for endoscopy.1Gellad Z.F. et al.Clin Gastroenterol Hepatol. 2013; 11: 1046-1049Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar We agree entirely with Dr Kisloff that an exploration of overuse in gastrointestinal endoscopy is important and would be a valuable contribution to the literature. Multiple studies have highlighted potential overuse in colonoscopy,2Schoen R.E. et al.Gastroenterology. 2010; 138: 73-81Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar, 3Goodwin J.S. et al.Arch Intern Med. 2011; 171: 1335-1343Crossref PubMed Scopus (157) Google Scholar and recent practice guidelines from the American College of Physicians have noted risks of overuse of upper endoscopy in evaluating reflux.4Shaheen N.J. et al.Ann Intern Med. 2012; 157: 808-816Crossref PubMed Scopus (130) Google Scholar Unraveling the reasons for overuse and mechanisms to curb overuse are much more complex undertakings, but promising work has begun. We would point to the recent editorial by Naik et al5Naik A.D. et al.Clin Gastroenterol Hepatol. 2013; 11: 753-755Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar in this journal as such an example. The importance of endoscopy utilization notwithstanding, we continue to believe that efficiency at the operational level remains an important and understudied area of health care quality. As Jim Kim, president of the World Bank, wrote in a recent editorial, the American health care system has an “inexplicably high tolerance for poor execution…that has compromised health care in the United States.”6Kim J.Y. Healthcare. 2013; 1: 3Crossref Scopus (2) Google Scholar Rather than being used for “fiscal legerdemain,” efficiency metrics should be used to support the delivery of high-value, patient-centered endoscopy services. As Dr Kisloff points out, however, we would be remiss if we did not also emphasize that efficiency metrics should not be used in isolation but rather in conjunction with similarly robust measures of quality such as post-discharge adverse outcomes. Finally, in regard to Dr Kisloff's frustration regarding the absence of detailed information on the Donabedian paradigm, we regret the difficulty in accessing referenced material. Donabedian is a classic conceptual model, and we chose to reference the original article. A more recent reprint is available.7Donabedian A. Milbank Quarterly. 2005; 83: 691-729Crossref PubMed Scopus (1276) Google Scholar We hope this provides easier access to additional information. Quality RedefinedClinical Gastroenterology and HepatologyVol. 12Issue 3PreviewIn perusing the contents of my September 2013 issue of Clinical Gastroenterology and Hepatology, I was immediately enticed by the prospect of learning about Donabedian analysis in your “Practice Management: The Road Ahead” section.1 One can only imagine my disappointment at discovering that I would need to go to a supplementary table in an almost half-century-old reference to familiarize myself with the intellectual underpinnings of this section. My frustration was further compounded when I learned from the article of “…the absence of measures that have been evaluated rigorously in the context of the AHRQ [Agency for Healthcare Research and Quality] criteria of scientific soundness…” Finally, as I read Table 1 of the section, I could not find any mention of post-discharge measures as regards “Endoscopy Unit Efficiency Measures.” The aforementioned table provides an ample roadmap to the expeditious dispatching of a patient, with seemingly no regard to possible post-discharge adverse outcomes. Full-Text PDF DA - 2014/3// PY - 2014/3// DO - 10.1016/J.CGH.2013.12.003 VL - 12 IS - 3 SP - 527 J2 - Clinical Gastroenterology and Hepatology LA - en OP - SN - 1542-3565 UR - http://dx.doi.org/10.1016/J.CGH.2013.12.003 DB - Crossref ER - TY - CHAP TI - Routing and Wavelength Assignment in Optical Networks from Maximum Edge-Disjoint Paths AU - Hsu, Chia-Chun AU - Cho, Hsun-Jung AU - Fang, Shu-Cherng T2 - Advances in Intelligent Systems and Computing AB - The routing and wavelength assignment (RWA) problem is NP-hard and also an important issue in wavelength-division multiplexing (WDM) optical networks. We propose an algorithm which is based on the maximum number of edge-disjoint paths (MEDP) to solve the RWA problem. The performance of the proposed method has been verified by experiments on several realistic network topologies. PY - 2014/// DO - 10.1007/978-3-319-01796-9_10 SP - 95-103 OP - PB - Springer International Publishing SN - 9783319017952 9783319017969 UR - http://dx.doi.org/10.1007/978-3-319-01796-9_10 DB - Crossref ER - TY - JOUR TI - A practical method for evaluating worker allocations in large-scale dual resource constrained job shops AU - Lobo, Benjamin J. AU - Wilson, James R. AU - Thoney, Kristin A. AU - Hodgson, Thom J. AU - King, Russell E. T2 - IIE Transactions AB - In two recent articles, Lobo et al. present algorithms for allocating workers to machine groups in a Dual Resource Constrained (DRC) job shop so as to minimize Lmax , the maximum job lateness. Procedure LBSA delivers an effective lower bound on Lmax , while the heuristic delivers an allocation whose associated schedule has a (usually) near-optimal Lmax value. To evaluate an HSP-based allocation’s quality in a given DRC job shop, the authors first compute the gap between HSP’s associated Lmax value and ’s lower bound. Next they refer this gap to the distribution of a “quasi-optimality” gap that is generated as follows: (i) independent simulation replications of the given job shop are obtained by randomly sampling each job’s characteristics; and (ii) for each replication, the associated quasi-optimality gap is computed by enumerating all feasible allocations. Because step (ii) is computationally intractable in large-scale problems, this follow-up article formulates a revised step (ii) wherein each simulation invokes , an improved version of , to yield an approximation to the quasi-optimality gap. Based on comprehensive experimentation, it is concluded that the -based distribution did not differ significantly from its enumeration-based counterpart; and the revised evaluation method was computationally tractable in practice. Two examples illustrate the use of the revised method. DA - 2014/7/28/ PY - 2014/7/28/ DO - 10.1080/0740817X.2014.892231 VL - 46 IS - 11 SP - 1209-1226 J2 - IIE Transactions LA - en OP - SN - 0740-817X 1545-8830 UR - http://dx.doi.org/10.1080/0740817X.2014.892231 DB - Crossref KW - Job shop scheduling KW - dual resource constrained system KW - worker allocation KW - maximum job lateness ER - TY - JOUR TI - The Influence of MgO Nanoparticles on the Osseointegration of Polycaprolactone - Sodium Alginate Hydrogel Interfaces AU - Khandaker, M. AU - Vaughan, M. AU - Starly, B. T2 - British Journal of Applied Science & Technology DA - 2014/1/10/ PY - 2014/1/10/ DO - 10.9734/bjast/2014/5404 VL - 4 IS - 1 SP - 79-88 SN - 2231-0843 UR - http://dx.doi.org/10.9734/bjast/2014/5404 ER - TY - CHAP TI - Research in Public Health for Efficient, Effective, and Equitable Outcomes AU - Ayer, Turgay AU - Keskinocak, Pinar AU - Swann, Julie T2 - Bridging Data and Decisions AB - Free AccessAboutSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked InEmail Go to SectionFree Access HomeINFORMS TutORials in Operations ResearchBridging Data and Decisions Research in Public Health for Efficient, Effective, and Equitable OutcomesTurgay Ayer, Pinar Keskinocak, Julie SwannTurgay Ayer, Pinar Keskinocak, Julie SwannPublished Online:27 Oct 2014https://doi.org/10.1287/educ.2014.0129Abstract Public health focuses on preventing disease, prolonging life, and promoting health in a population, and there are many ways in which operations research and management science (OR/MS) researchers can contribute to improved decision making in this area. In this tutorial, we discuss examples of work in several areas of public health, including access and equity, disease screening, chronic diseases, and infectious diseases. In each of these areas, we give a brief overview of challenging issues and related literature, give a specific example of a research topic, and point to potential future directions for research. We describe several trends that could impact future public health research including population ageing and an increased use of electronic records. The tutorial is intended to introduce OR/MS researchers to the many opportunities for having a positive impact on specific populations and society overall, through OR/MS research related to public health. This publication has no references to display. Your Access Options Login Options INFORMS Member Login Nonmember Login Purchase Options Save for later Item saved, go to cart Tutorials in OR, TutorialsNew $20.00 Add to cart Tutorials in OR, TutorialsNew Checkout Other Options Token Access Insert token number Claim access using a token Restore guest access Applies for purchases made as a guest Previous Back to Top Next FiguresReferencesRelatedInformationCited byA Review of the Healthcare-Management (Modeling) Literature Published in Manufacturing & Service Operations ManagementPinar Keskinocak, Nicos Savva17 December 2019 | Manufacturing & Service Operations Management, Vol. 22, No. 1 Bridging Data and DecisionsSeptember 2014 Article Information Metrics Information Published Online:October 27, 2014 Copyright © 2014, INFORMSCite asTurgay AyerPinar KeskinocakJulie Swann (2014) Research in Public Health for Efficient, Effective, and Equitable Outcomes. INFORMS TutORials in Operations Research null(null):216-239. https://doi.org/10.1287/educ.2014.0129 Keywordsoperations researchmanagement scienceanalyticspublic healthhealth systemsaccessequitychronic diseaseinfectious diseasescreeningPDF download PY - 2014/9// DO - 10.1287/educ.2014.0129 SP - 216-239 OP - PB - INFORMS SN - 9780984337859 UR - http://dx.doi.org/10.1287/educ.2014.0129 DB - Crossref ER - TY - JOUR TI - Scaling the house: optimal seating zones for entertainment venues when location of seats affects demand AU - Phumchusri, Naragain AU - Swann, Julie L. T2 - International Journal of Revenue Management AB - This paper studies the problem of 'Scaling the House', or how venue managers should optimally divide seats into sections with different prices. From previous study, it was found that distance from the stage and distance from the seating row's centre affect demand. We develop a two–dimensional zoning model for the optimal 'Scaling the House' decisions. When demand is not significantly sensitive to distance from the centre, we present an alternative one–dimensional zoning model and show that the optimal seating row (to be priced at a higher price before switching to the next lower price) is the row whose expected revenue when charging at a high price is equal to the expected revenue when charging at a low price. We provide key comparative statics on how model parameters impact the optimal decisions and discuss the important managerial insights on when it is most worthwhile to section seats into two dimensional zones. DA - 2014/// PY - 2014/// DO - 10.1504/ijrm.2014.067334 VL - 8 IS - 1 SP - 56 J2 - IJRM LA - en OP - SN - 1474-7332 1741-8186 UR - http://dx.doi.org/10.1504/ijrm.2014.067334 DB - Crossref ER - TY - JOUR TI - Spatial accessibility of pediatric primary healthcare: Measurement and inference AU - Nobles, Mallory AU - Serban, Nicoleta AU - Swann, Julie T2 - The Annals of Applied Statistics AB - Although improving financial access is in the spotlight of the current U.S. health policy agenda, this alone does not address universal and comprehensive healthcare. Affordability is one barrier to healthcare, but others such as availability and accessibility, together defined as spatial accessibility, are equally important. In this paper, we develop a measurement and modeling framework that can be used to infer the impact of policy changes on disparities in spatial accessibility within and across different population groups. The underlying model for measuring spatial accessibility is optimization-based and accounts for constraints in the healthcare delivery system. The measurement method is complemented by statistical modeling and inference on the impact of various potential contributing factors to disparities in spatial accessibility. The emphasis of this study is on children’s accessibility to primary care pediatricians, piloted for the state of Georgia. We focus on disparities in accessibility between and within two populations: children insured by Medicaid and other children. We find that disparities in spatial accessibility to pediatric primary care in Georgia are significant, and resistant to many policy interventions, suggesting the need for major changes to the structure of Georgia’s pediatric healthcare provider network. DA - 2014/12// PY - 2014/12// DO - 10.1214/14-aoas728 VL - 8 IS - 4 SP - 1922-1946 J2 - Ann. Appl. Stat. LA - en OP - SN - 1932-6157 UR - http://dx.doi.org/10.1214/14-aoas728 DB - Crossref KW - Healthcare access KW - optimization model KW - pediatric healthcare KW - spatial accessibility KW - spatial-varying coefficient model ER - TY - JOUR TI - Balancing investments in federally qualified health centers and Medicaid for improved access and coverage in Pennsylvania AU - Griffin, Paul M. AU - Lee, Hyunji AU - Scherrer, Christina AU - Swann, Julie L. T2 - Health Care Management Science DA - 2014/1/16/ PY - 2014/1/16/ DO - 10.1007/s10729-013-9265-8 VL - 17 IS - 4 SP - 348-364 J2 - Health Care Manag Sci LA - en OP - SN - 1386-9620 1572-9389 UR - http://dx.doi.org/10.1007/s10729-013-9265-8 DB - Crossref KW - Medicaid KW - Federally qualified health centers KW - Multi-criteria optimization KW - Utility ER - TY - JOUR TI - Modeling Influenza Pandemic and Planning Food Distribution AU - Ekici, Ali AU - Keskinocak, Pınar AU - Swann, Julie L. T2 - Manufacturing & Service Operations Management AB - Based on the recent incidents of H5N1, H1N1, and influenza pandemics in history (1918, 1957, and 1968) experts believe that a future influenza pandemic is inevitable and likely imminent. Although the severity of influenza pandemics vary, evidence suggests that an efficient and rapid response is crucial for mitigating morbidity, mortality, and costs to society. Hence, preparing for a potential influenza pandemic is a high priority of governments at all levels (local, state, federal), nongovernmental organizations (NGOs), and companies. In a severe pandemic, when a large number of people are ill, infected persons and their families may have difficulty purchasing and preparing meals. Various government agencies and NGOs plan to provide meals to these households. In this paper, in collaboration with the American Red Cross, we study food distribution planning during an influenza pandemic. We develop a disease spread model to estimate the spread pattern of the disease geographically and over time, combine it with a facility location and resource allocation network model for food distribution, and develop heuristics to find near-optimal solutions for large instances. We run our combined disease spread and facility location model for the state of Georgia and present the estimated number of infections and the number of meals needed in each census tract for a one-year period along with a design of the supply chain network. Moreover, we investigate the impact of voluntary quarantine on the food demand and the food distribution network and show that its effects on food distribution can be significant. Our results could help decision makers prepare for a pandemic, including how to allocate limited resources and respond dynamically. DA - 2014/2// PY - 2014/2// DO - 10.1287/msom.2013.0460 VL - 16 IS - 1 SP - 11-27 J2 - M&SOM LA - en OP - SN - 1523-4614 1526-5498 UR - http://dx.doi.org/10.1287/msom.2013.0460 DB - Crossref KW - influenza pandemic KW - food distribution planning KW - disease spread models KW - multiperiod facility location KW - dynamic update ER - TY - BOOK TI - Scaffolding hydrogels for rapid prototyping based tissue engineering AU - Shirwaiker, R.A. AU - Purser, M.F. AU - Wysk, R.A. AB - Scaffolding hydrogels provides the ability to pattern cell suspensions directly within 3D configurations of hydrated polymer networks to mimic the physical and biological characteristics of natural extracellular matrices. This chapter first reviews the developments, key characteristics, and applications of some commonly used and emerging hydrogel biomaterials. It then discusses the compatibility between hydrogels and rapid prototyping (RP) scaffolding processes, and highlights some of the recent emerging trends in scaffolding biomaterials research. DA - 2014/// PY - 2014/// DO - 10.1533/9780857097217.176 SE - 176-200 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84904083655&partnerID=MN8TOARS KW - hydrogels KW - biopaper KW - scaffolds KW - organ printing ER - TY - JOUR TI - Incorporating economies of scale into facility location problems in carpet recycling AU - Bucci, Michael J. AU - Woolard, Ryan AU - Joines, Jeffrey AU - Thoney, Kristin AU - King, Russell E. T2 - The Journal of The Textile Institute AB - The Carpet America Recovery Effort (CARE) set a goal to divert 40% of used carpet from landfills in the United States by 2012, but only achieved a 10% diversion rate. To achieve the 40% diversion rate, approximately 1.4 billion lbs would need to have been diverted. Diverting this significant quantity may require the design of a larger, more effective reverse logistics network to process the used materials. A new facility location heuristic originally developed for the forward distribution of products is applied to the reverse logistics system for carpet recycling. The objective is to locate an unknown number of carpet recycling facilities to minimize the total cost. The model includes transportation costs, as well as fixed facility and processing costs at the recycling plant, the latter exhibiting economies of scale (EOS) as the facility size increases. We evaluate the model using data from the CARE collection network in the continental United States and compare these findings to models that assume a significant increase in collection locations and rates to meet specific carpet diversion targets. We show the impact of EOS of the recycling facilities on the solution structure, as well as the impact that collection volumes have on the solution. DA - 2014/3/5/ PY - 2014/3/5/ DO - 10.1080/00405000.2014.890833 VL - 105 IS - 12 SP - 1300-1311 J2 - The Journal of The Textile Institute LA - en OP - SN - 0040-5000 1754-2340 UR - http://dx.doi.org/10.1080/00405000.2014.890833 DB - Crossref KW - reverse logistics KW - carpet recycling KW - facility location KW - economies of scale ER - TY - JOUR TI - Upper extremity kinematic and kinetic adaptations during a fatiguing repetitive task AU - Qin, Jin AU - Lin, Jia-Hua AU - Faber, Gert S. AU - Buchholz, Bryan AU - Xu, Xu T2 - JOURNAL OF ELECTROMYOGRAPHY AND KINESIOLOGY AB - Repetitive low-force contractions are common in the workplace and yet can lead to muscle fatigue and work-related musculoskeletal disorders. The current study aimed to investigate potential motion adaptations during a simulated repetitive light assembly work task designed to fatigue the shoulder region, focusing on changes over time and age-related group differences. Ten younger and ten older participants performed four 20-min task sessions separated by short breaks. Mean and variability of joint angles and scapular elevation, joint net moments for the shoulder, elbow, and wrist were calculated from upper extremity kinematics recorded by a motion tracking system. Results showed that joint angle and joint torque decreased across sessions and across multiple joints and segments. Increased kinematic variability over time was observed in the shoulder joint; however, decreased kinematic variability over time was seen in the more distal part of the upper limb. The changes of motion adaptations were sensitive to the task-break schedule. The results suggested that kinematic and kinetic adaptations occurred to reduce the biomechanical loading on the fatigued shoulder region. In addition, the kinematic and kinetic responses at the elbow and wrist joints also changed, possibly to compensate for the increased variability caused by the shoulder joint while still maintaining task requirements. These motion strategies in responses to muscle fatigue were similar between two age groups although the older group showed more effort in adaptation than the younger in terms of magnitude and affected body parts. DA - 2014/6// PY - 2014/6// DO - 10.1016/j.jelekin.2014.02.001 VL - 24 IS - 3 SP - 404-411 SN - 1873-5711 KW - Repetitive work KW - Kinematic variability KW - Age KW - Upper extremity ER - TY - JOUR TI - The effect of age on the hand movement time during machine paced assembly tasks for female workers AU - Xu, Xu AU - Qin, Jin AU - Zhang, Tao AU - Lin, Jia-Hua T2 - INTERNATIONAL JOURNAL OF INDUSTRIAL ERGONOMICS AB - The share of older adults in the workforce is increasing in many countries. In the manufacturing industry a high proportion of assembly tasks are machine paced. Previous studies have shown that older adults tend to have longer movement times than younger adults when working at a self-selected pace. However, it is unclear whether older adults can obtain the same hand movement time as a younger group when performing machine paced work at the assembly line. In the current study, 10 older and 10 younger female participants performed simulated light-duty assembly tasks during which the hand movement times were recorded. The results showed that the older participants were capable of working at the set pace and there was no significant difference between age groups in hand movement times (989.9 msec vs. 986.6 msec, p = 0.5647). A likely explanation to the results is that the older participant had to work closer to their physical limits or capacity in order to compensate for the age effect on movement time. This study provided some preliminary quantitative data describing the hand movement time for younger and older female adults during machine paced assembly work. The results showed that age did not have a significant effect on hand movement time. Such results may help in adapting workplaces and work tasks to accommodate the needs of an aging workforce. DA - 2014/1// PY - 2014/1// DO - 10.1016/j.ergon.2013.11.010 VL - 44 IS - 1 SP - 148-152 SN - 1872-8219 KW - Aging KW - Assembly tasks KW - Female workers KW - Movement time KW - Fitts' law ER - TY - JOUR TI - The accuracy of an external frame using ISB recommended rotation sequence to define shoulder joint angle AU - Xu, Xu AU - McGorry, Raymond W. AU - Lin, Jia-hua T2 - GAIT & POSTURE AB - When investigating shoulder kinematics, it may be necessary to limit shoulder joint angles at a specific level. Previous studies used external frames or external surfaces to assist the participant to reach the shoulder joint angles of interest. The accuracy of these methods, however, has not yet been investigated. In the current study, an external frame was designed to assist in maintaining specific shoulder postures in a wide range. The three degrees of freedom of rotation of the proposed frame were designed to be consistent with the description of shoulder joint angles recommended by the International Society of Biomechanics. Six participants used this frame to perform 118 different shoulder postures. The reference joint angles measured by a motion tracking system were compared with the frame-defined angles. The angle differences among all the participants ranged from 12.7° to 85.6°, with an average of 32.2° (SD 15.1°) across all postures. For the postures with elevation angles on or below horizontal, the average angle difference was 23.7° (SD 8.5°). Findings suggest that errors exist when using an external frame to assist in reaching specific shoulder postures. Error is minimized at elevation angles close to −30°, and the performance is poor for extreme shoulder postures. DA - 2014/1// PY - 2014/1// DO - 10.1016/j.gaitpost.2013.08.032 VL - 39 IS - 1 SP - 662-668 SN - 1879-2219 KW - Shoulder kinematics KW - Plane of elevation KW - Elevation angle KW - Axial rotation ER - TY - JOUR TI - Shoulder muscle fatigue development in young and older female adults during a repetitive manual task AU - Qin, Jin AU - Lin, Jia-Hua AU - Buchholz, Bryan AU - Xu, Xu T2 - ERGONOMICS AB - Age may modify the association between occupational physical demand and muscle loading, and ultimately increase the risk of musculoskeletal disorders. The goal of this study was to investigate age-related differences in shoulder muscle fatigue development during a repetitive manual task. Twenty participants in two age groups completed an 80-minute simulated low-intensity assembly task. Electromyographic (EMG) manifestation of muscle fatigue was observed in the upper trapezius, deltoid and infraspinatus muscles in both age groups, and coincided with an increase in the subjective ratings of perceived exertions. Compared with the younger group, older group showed a more monotonic decrease in EMG power frequency in the upper trapezius and deltoid muscles. However, the age-related difference in EMG amplitude was less consistent. Relative rest time of the upper trapezius muscle in the older group was less than the young group throughout the task. The observed patterns of EMG measures suggest that older participants may have disadvantages in fatigue resistance in the upper trapezius and posterior deltoid muscles during the simulated repetitive manual task. DA - 2014/8// PY - 2014/8// DO - 10.1080/00140139.2014.914576 VL - 57 IS - 8 SP - 1201-1212 SN - 1366-5847 KW - age KW - shoulder KW - muscle fatigue KW - electromyography KW - repetitive work ER - TY - JOUR TI - Joint Contribution to Fingertip Movement During a Number Entry Task: An Application of Jacobian Matrix AU - Qin, Jin AU - Trudeau, Matthieu AU - Buchholz, Bryan AU - Katz, Jeffrey N. AU - Xu, Xu AU - Dennerlein, Jack T. T2 - JOURNAL OF APPLIED BIOMECHANICS AB - Upper extremity kinematics during keyboard use is associated with musculoskeletal health among computer users; however, specific kinematics patterns are unclear. This study aimed to determine the dynamic roles of the shoulder, elbow, wrist and metacarpophalangeal (MCP) joints during a number entry task. Six subjects typed in phone numbers using their right index finger on a stand-alone numeric keypad. The contribution of each joint of the upper extremity to the fingertip movement during the task was calculated from the joint angle trajectory and the Jacobian matrix of a nine-degree-of-freedom kinematic representation of the finger, hand, forearm and upper arm. The results indicated that in the vertical direction where the greatest fingertip movement occurred, the MCP, wrist, elbow (including forearm) and shoulder joint contributed 10.2%, 55.6%, 27.7% and 6.5%, respectively, to the downward motion of the index finger averaged across subjects. The results demonstrated that the wrist and elbow contribute the most to the fingertip vertical movement, indicating that they play a major role in the keying motion and have a dynamic load beyond maintaining posture. DA - 2014/4// PY - 2014/4// DO - 10.1123/jab.2013-0093 VL - 30 IS - 2 SP - 338-342 SN - 1543-2688 KW - keying task KW - upper extremity KW - Jacobian matrix KW - kinematics ER - TY - JOUR TI - A regression-based 3-D shoulder rhythm AU - Xu, Xu AU - Lin, Jia-hua AU - McGorry, Raymond W. T2 - JOURNAL OF BIOMECHANICS AB - In biomechanical modeling of the shoulder, it is important to know the orientation of each bone in the shoulder girdle when estimating the loads on each musculoskeletal element. However, because of the soft tissue overlying the bones, it is difficult to accurately derive the orientation of the clavicle and scapula using surface markers during dynamic movement. The purpose of this study is to develop two regression models which predict the orientation of the clavicle and the scapula. The first regression model uses humerus orientation and individual factors such as age, gender, and anthropometry data as the predictors. The second regression model includes only the humerus orientation as the predictor. Thirty-eight participants performed 118 static postures covering the volume of the right hand reach. The orientation of the thorax, clavicle, scapula and humerus were measured with a motion tracking system. Regression analysis was performed on the Euler angles decomposed from the orientation of each bone from 26 randomly selected participants. The regression models were then validated with the remaining 12 participants. The results indicate that for the first model, the r(2) of the predicted orientation of the clavicle and the scapula ranged between 0.31 and 0.65, and the RMSE obtained from the validation dataset ranged from 6.92° to 10.39°. For the second model, the r(2) ranged between 0.19 and 0.57, and the RMSE obtained from the validation dataset ranged from 6.62° and 11.13°. The derived regression-based shoulder rhythm could be useful in future biomechanical modeling of the shoulder. DA - 2014/3/21/ PY - 2014/3/21/ DO - 10.1016/j.jbiomech.2014.01.043 VL - 47 IS - 5 SP - 1206-1210 SN - 1873-2380 KW - Humerus KW - Clavicle KW - Scapula KW - Kinematics KW - ISB recommendations ER - TY - JOUR TI - A regression model predicting isometric shoulder muscle activities from arm postures and shoulder joint moments AU - Xu, Xu AU - McGorry, Raymond W. AU - Lin, Jia-Hua T2 - JOURNAL OF ELECTROMYOGRAPHY AND KINESIOLOGY AB - Tissue overloading is a major contributor to shoulder musculoskeletal injuries. Previous studies attempted to use regression-based methods to predict muscle activities from shoulder kinematics and shoulder kinetics. While a regression-based method can address co-contraction of the antagonist muscles as opposed to the optimization method, most of these regression models were based on limited shoulder postures. The purpose of this study was to develop a set of regression equations to predict the 10th percentile, the median, and the 90th percentile of normalized electromyography (nEMG) activities from shoulder postures and net shoulder moments. Forty participants generated various 3-D shoulder moments at 96 static postures. The nEMG of 16 shoulder muscles was measured and the 3-D net shoulder moment was calculated using a static biomechanical model. A stepwise regression was used to derive the regression equations. The results indicated the measured range of the 3-D shoulder moment in this study was similar to those observed during work requiring light physical capacity. The r2 of all the regression equations ranged between 0.228 and 0.818. For the median of the nEMG, the average r2 among all 16 muscles was 0.645, and the five muscles with the greatest r2 were the three deltoids, supraspinatus, and infraspinatus. The results can be used by practitioners to estimate the range of the shoulder muscle activities given a specific arm posture and net shoulder moment. DA - 2014/6// PY - 2014/6// DO - 10.1016/j.jelekin.2014.02.004 VL - 24 IS - 3 SP - 419-429 SN - 1873-5711 KW - EMG KW - Muscle co-contraction KW - Kinematics KW - Biomechanical model ER - TY - JOUR TI - Manually Locating Physical and Virtual Reality Objects AU - Chen, Karen B. AU - Kimmel, Ryan A. AU - Bartholomew, Aaron AU - Ponto, Kevin AU - Gleicher, Michael L. AU - Radwin, Robert G. T2 - HUMAN FACTORS AB - In this study, we compared how users locate physical and equivalent three-dimensional images of virtual objects in a cave automatic virtual environment (CAVE) using the hand to examine how human performance (accuracy, time, and approach) is affected by object size, location, and distance.Virtual reality (VR) offers the promise to flexibly simulate arbitrary environments for studying human performance. Previously, VR researchers primarily considered differences between virtual and physical distance estimation rather than reaching for close-up objects.Fourteen participants completed manual targeting tasks that involved reaching for corners on equivalent physical and virtual boxes of three different sizes. Predicted errors were calculated from a geometric model based on user interpupillary distance, eye location, distance from the eyes to the projector screen, and object.Users were 1.64 times less accurate (p < .001) and spent 1.49 times more time (p = .01) targeting virtual versus physical box corners using the hands. Predicted virtual targeting errors were on average 1.53 times (p < .05) greater than the observed errors for farther virtual targets but not significantly different for close-up virtual targets.Target size, location, and distance, in addition to binocular disparity, affected virtual object targeting inaccuracy. Observed virtual box inaccuracy was less than predicted for farther locations, suggesting possible influence of cues other than binocular vision.Human physical interaction with objects in VR for simulation, training, and prototyping involving reaching and manually handling virtual objects in a CAVE are more accurate than predicted when locating farther objects. DA - 2014/9// PY - 2014/9// DO - 10.1177/0018720814523067 VL - 56 IS - 6 SP - 1163-1176 SN - 1547-8181 KW - virtual reality KW - physical interface KW - simulation KW - CAVE ER - TY - CONF TI - Influence of altered visual feedback on neck movement for a virtual reality rehabilitative system AU - Chen, Karen AU - Ponto, K. AU - Sesto, M. E. AU - Radwin, R. G. AB - This paper investigates altering visual feedback during neck movement through control-display (C-D) gain for a head-mounted display, for the purpose of determining the just noticeable difference (JND) for encouraging individuals with kinesiophobia (i.e. fear avoidance of movement due to chronic pain) to effectively perform therapeutic neck exercises. The JND was defined as .25 probability of detecting a difference from unity C-D gain (gain=1). A target-aiming task with two consecutive neck moves per trial was presented; one neck move had varying C-D gain and the other had unity gain. The VR system was able to influence neck moves without changing locations of the target. Participants indicated whether the two neck movements were the same or different. Logistic regression revealed that the JND gains were 0.903 (lower bound) and 1.159 (upper bound) as the participants could not discriminate a 55° turn, ranging from 49.7° to 63.7°. This preliminary study shows that immersive VR with altered visual feedback influenced movement. The feasibility for rehabilitation of individuals with kinesiophobia will next be assessed. C2 - 2014/// C3 - International Annual Meeting of the Human Factors and Ergonomics Society DA - 2014/// DO - 10.1177/1541931214581162 ER - TY - CONF TI - Assessing exertions: How an increased level of immersion unwittingly leads to more natural behavior AU - Ponto, K. AU - Chen, Karen AU - Radwin, R. G. AU - Tredinnick, R. AB - This paper utilizes muscle exertions as a means to affect and study the behavior of participants in a virtual environment. Participants performed a simple lifting task both physically using an actual weight and virtually. In the virtual environment participants were presented with two different types of virtual presentation methods, one in which the weights were shown as a 3D model in the Immersive Visuals scenario and one in which the weights were shown as a simple line in the bland scenario. In the virtual scenarios, the object is only lifted when the participant's muscle activity, measured by surface EMG, exceeds a calibrated minimum level as described in previous literature. We found that while participants were able to perceive the difference for various weights both physically and virtually, we found no significant differences in the perceived efforts between the presentation methods. However, while the participants subjectively indicated that their effort was the same for each of these presentation methods, we found significant differences in the muscle activity between the two virtual presentation methods. For all primary mover muscle groups and weights, the more immersive virtual presentation method led to exertions that were much more approximate to the exertions used for the physical weights. C2 - 2014/// C3 - IEEE VR DA - 2014/// DO - 10.1109/vr.2014.6802074 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, R. A. 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 - 2014/// C3 - Proceedings of the ASME Summer Bioengineering Conference - 2013, pt B DA - 2014/// DO - 10.1115/sbc2013-14141 ER - TY - JOUR TI - DIRECT FABRICATION OF HIGHLY CONDUCTIVE MICRO SILVER TRACKS USING ELECTROHYDRODYNAMIC JET PRINTING FOR SUB-20 mu M MICRO-MANUFACTURING AU - Qin, Hantang AU - Wei, Chuang AU - Dong, Jingyan AU - Lee, Yuan-Shin T2 - PROCEEDINGS OF THE ASME 9TH INTERNATIONAL MANUFACTURING SCIENCE AND ENGINEERING CONFERENCE, 2014, VOL 2 AB - This paper presents a direct fabrication method of highly conductive silver tracks with sub-20 μm microstructures on glass substrate by using electrohydrodynamic jet printing (EHDJP) with alternative current (AC) voltage. Traditional ink jet printing fabrication approaches are limited in the achievable resolution. EHDJP has been used in directly printing by generating a fine jet through a large electrical potential between nozzle and substrate. When charge accumulates on the ink meniscus at the nozzle, a fine jet down to nano scale can be generated. In the paper, we successfully applied EHDJP for fabrication of highly conductive silver tracks using AC voltage. It was the first time that sub-20 μm silver tracks were demonstrated and printed with resistivity about 3.16 times than bulk silver. The variables of fabrication process were investigated to achieve reliable jet printing of conductive silver tracks. The topography of printed tracks was characterized and verified in the study. The presented technique can be used for micro-manufacturing of three-dimensional microstructures and biomedical device fabrications. DA - 2014/// PY - 2014/// DO - 10.1115/msec2014-4163 VL - 2 SP - UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84908429027&partnerID=MN8TOARS KW - Electrohydrodynamic jet printing KW - Micro-manufacturing KW - Conductive silver tracks KW - Direct printing KW - Alternative current ER - TY - CONF TI - A biomechanical study of directional mechanical properties of porcine skin tissues AU - Huang, H. Y. S. AU - Huang, S. Y. AU - Gettys, T. AU - Prim, P. M. AU - Harrysson, O. L. C2 - 2014/// C3 - Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 9 DA - 2014/// ER - TY - CONF TI - Design for FDA: A predictive model for the FDA's decision time for medical devices AU - Medina, L. A. AU - Davila, S. AU - Kremer, G. E. O. AU - Wysk, R. A. AB - The concept of Design for FDA (DfFDA) has a strong basis on the Food and Drug Administration’s (FDA) regulation for medical devices in the Unites States. In fact; an analysis of the factors that impact the time it takes the FDA’s to provide market approval for medical devices, the product design process model, and Design for X (DfX) methods with overlapping FDA objectives lead to the development of DfFDA as a means to increase awareness about regulatory compliance and promote designers to consider the regulations throughout the development process of medical devices. For doing so, the main objective of DfFDA is to provide regulation-focused guidelines to producers of medical devices. An important part of these guidelines and this paper’s major contribution is the development of a prediction model for the FDA’s decision time. Overall, we want this model to become a tool that allows medical device companies to come up with an accurate estimate of a product’s time-to-market after accounting for the FDA’s decision time. In this work, we provide a comparison and discussion on the adequacy of linear regression models and other non-linear models such as parallel and serial tree-based ensembles for prediction the FDA’s decision time. C2 - 2014/// C3 - Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, 2013, vol 4 DA - 2014/// DO - 10.1115/detc2013-13606 ER - TY - CONF TI - A human factors study of graphical passwords using biometrics AU - Riggan, B. S. AU - Snyder, W. E. AU - Wang, X. G. AU - Feng, J. C2 - 2014/// C3 - Pattern recognition, gcpr 2014 DA - 2014/// VL - 8753 SP - 464-475 ER - TY - JOUR TI - Susceptibility to Driver Distraction Questionnaire Development and Relation to Relevant Self-Reported Measures AU - Fang, Jing AU - Marulanda, Susana AU - Donmez, Birsen T2 - TRANSPORTATION RESEARCH RECORD AB - Driver distraction significantly impairs performance and increases the likelihood of vehicle crashes. Understanding the underlying reasons for distraction engagement as well as individuals’ susceptibility to various types of distractions is a necessary step in developing effective solutions for mitigating distraction. This paper describes the development and initial evaluation of a questionnaire, the Susceptibility to Driver Distraction Questionnaire (SDDQ), which investigates distraction involvement by making a distinction between voluntary and involuntary engagement in secondary activities, or distractions, as referred to in this paper. The paper presents the theoretical underpinnings, the questionnaire itself, as well as the results of an online survey that examined the reliability and validity of the newly developed questionnaire. The analyses show moderate to high levels of internal consistency among the questionnaire items; this consistency provides support to the reliability of the SDDQ. The results also suggest that self-reported engagement in driver distraction is correlated with other self-reported, unsafe driving behaviors. As expected, personality is associated with attitudes and beliefs that motivate voluntary engagement in distraction, while susceptibility to involuntary distraction is related to cognitive limitations. These results indicate that the SDDQ can potentially be a useful tool to study driver distraction and the underlying reasons for distraction engagement. DA - 2014/// PY - 2014/// DO - 10.3141/2434-04 IS - 2434 SP - 26-34 SN - 2169-4052 ER - TY - JOUR TI - Hybrid hierarchical fabrication of three-dimensional scaffolds AU - Wei, Chuang AU - Dong, Jingyan T2 - JOURNAL OF MANUFACTURING PROCESSES AB - Three-dimensional (3D) porous structures facilitating cell attachment, growth, and proliferation is critical to tissue engineering applications. Traditional solid freeform fabrication (SFF) methods have limited capabilities in the fabrication of high resolution micro-scale features to implement advanced biomedical functions. In this work, we present a hybrid scaffold fabrication approach by integrating electrohydrodynamic (EHD) printing technology with extrusion deposition together to fabricate hierarchical 3D scaffolds with well controlled structures at both macro and micro scale. We developed a hybrid fabrication platform and a robust fabrication process to achieve 3D hierarchical structures. The melting extrusion by pneumatic pressure was used to fabricate 3D scaffolds with filaments dimension of hundreds of microns using thermoplastic biopolymer polycaprolactone (PCL). An electrohydrodynamic (EHD) melt jet plotting process was developed to fabricate micro-scale features on the scaffolds with sub-10 μm resolution, which has great potential in advanced biomedical applications, such as cell alignment and cell guidance. DA - 2014/4// PY - 2014/4// DO - 10.1016/j.jmapro.2013.10.003 VL - 16 IS - 2 SP - 257-263 SN - 2212-4616 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000349566600012&KeyUID=WOS:000349566600012 KW - Tissue engineering KW - Hierarchical scaffolds KW - Free-form fabrication KW - Electrohydrodynamic melt jet plotting ER - TY - JOUR TI - Canine stifle joint biomechanics associated with tibial plateau leveling osteotomy predicted by use of a computer model AU - Brown, Nathan P. AU - Bertocci, Gina E. AU - Marcellin-Little, Denis J. T2 - AMERICAN JOURNAL OF VETERINARY RESEARCH AB - Abstract Objective —To evaluate effects of tibial plateau leveling osteotomy (TPLO) on canine stifle joint biomechanics in a cranial cruciate ligament (CrCL)–deficient stifle joint by use of a 3-D computer model simulating the stance phase of gait and to compare biomechanics in TPLO-managed, CrCL-intact, and CrCL-deficient stifle joints. Sample —Computer simulations of the pelvic limb of a Golden Retriever. Procedures —A previously developed computer model of the canine pelvic limb was used to simulate TPLO stabilization to achieve a tibial plateau angle (TPA) of 5° (baseline value) in a CrCL-deficient stifle joint. Sensitivity analysis was conducted for tibial fragment rotation of 13° to −3°. Ligament loads, relative tibial translation, and relative tibial rotation were determined and compared with values for CrCL-intact and CrCL-deficient stifle joints. Results —TPLO with a 5° TPA converted cranial tibial translation to caudal tibial translation and increased loads placed on the remaining stifle joint ligaments, compared with results for a CrCL-intact stifle joint. Lateral collateral ligament load was similar, medial collateral ligament load increased, and caudal cruciate ligament load decreased after TPLO, compared with loads for a CrCL-deficient stifle joint. Relative tibial rotation after TPLO was similar to that of a CrCL-deficient stifle joint. Stifle joint biomechanics were affected by TPLO fragment rotation. Conclusions and Clinical Relevance —In the model, stifle joint biomechanics were partially improved after TPLO, compared with CrCL-deficient stifle joint biomechanics, but TPLO did not fully restore CrCL-intact stifle joint biomechanics. Overrotation of the tibial fragment negatively influenced stifle joint biomechanics by increasing caudal tibial translation. DA - 2014/7// PY - 2014/7// DO - 10.2460/ajvr.75.7.626 VL - 75 IS - 7 SP - 626-632 SN - 1943-5681 ER - TY - JOUR TI - Use of Reference Frame and Movement Pattern in Haptically Enhanced 3D Virtual Environment AU - Lee, Ja Young AU - Bahn, Sangwoo AU - Nam, Chang S. T2 - INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION AB - AbstractFor the present article a haptically enhanced 3D virtual environment was created, and this study investigates how visually impaired users perceive and explain the virtual space when haptic is the only input modality. The study investigates what factors affect the use of reference frame when the users verbally express a haptically constructed mental map and how such preference corresponds to their haptic movement in the virtual environment. In the study, gravity was the most influential cue in determining a vertical axis of a frame. When the users were asked to explain the relationship between themselves and the target object, they had the tendency to use the frame they initially chose to use. It was also noted that totally blind users were more responsive to various frames than users with lower vision and were faster in determining a term to explain spatial relationship. Furthermore, people who preferred relative frame were more likely to keep the haptic cursor closer to their body. Limited range of exploration caused lack of understanding of the space, whereas longer exploration time made them use more frames. Additional informationNotes on contributorsJa Young LeeJa Young Lee is currently a Ph.D. student at University of Wisconsin -- Madison, specializing in Human Factors and Ergonomics. She received an M.S. degree in Industrial and Systems Engineering at North Carolina State University, where she studied haptic user interface design and affective engineering. Her research interest is in analyzing and modeling human cognition.Sangwoo BahnSangwoo Bahn is an assistant professor of Industrial and Management Engineering at Myongji University, Korea. He received his Ph.D. degree in Industrial Engineering from Seoul National University, Korea, in 2010. His research interests include user interface design, affective engineering, and user modeling.Chang S. NamChang S. Nam is currently an associate professor of Industrial and Systems Engineering at North Carolina State University. He is also an associated faculty member in the UNC/NCSU Joint Department of Biomedical Engineering and Psychology Department. His primary research interests are brain–computer interface, neuroergonomics, rehabilitation engineering, and haptic user interfaces. DA - 2014/11/2/ PY - 2014/11/2/ DO - 10.1080/10447318.2014.941275 VL - 30 IS - 11 SP - 891-903 SN - 1532-7590 ER - TY - JOUR TI - The influence of rice plow handle design and whole-body posture on grip force and upper-extremity muscle activation AU - Swangnetr, M. AU - Kaber, D. AU - Phimphasak, C. AU - Namkorn, P. AU - Saenlee, K. AU - Zhu, B. AU - Puntumetakul, R. T2 - ERGONOMICS AB - A previous job screening study revealed ergonomics risk factors in rice field plowing. This work motivated the present experimental investigation of the influence of plow handle design and farmer whole-body posture on grip force and arm muscle activity. A total of 24 experienced farmers performed a simulated plowing task, including walking on even and uneven ground while rolling a tiller equipped with conventional horizontal and proposed vertical handles. Results revealed the proposed handles, designed to promote neutral wrist posture, to increase upper-arm muscle use between 47% and 70% across ground types, as compared with conventional handles. The ratio of grip force to forearm muscle activity (or efficiency in muscle use) increased from 1.85 when using conventional handles on uneven ground to 2.16 when using the proposed handles with symmetrical body posture on even ground. However, participants perceived higher discomfort when using the proposed handles, as they were accustomed to the conventional design. DA - 2014/// PY - 2014/// DO - 10.1080/00140139.2014.934301 VL - 57 IS - 10 SP - 1526-1535 SN - 1366-5847 KW - tool handle design KW - grip force KW - muscle activity KW - whole-body posture KW - body part discomfort ER - TY - JOUR TI - Statistical optimum estimation techniques for combinatorial optimization problems: a review and critique AU - Giddings, Angela P. AU - Rardin, Ronald L. AU - Uzsoy, Reha T2 - JOURNAL OF HEURISTICS DA - 2014/6// PY - 2014/6// DO - 10.1007/s10732-014-9243-4 VL - 20 IS - 3 SP - 329-358 SN - 1572-9397 KW - Statistical optimum estimation KW - Experimental analysis KW - Heuristic quality assessment ER - TY - JOUR TI - Scenario-Based Observation Approach for Eliciting User Requirements for Haptic User Interfaces AU - Bahn, Sangwoo AU - Corbett, Brendan AU - Nam, Chang S. T2 - INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION AB - As tactual information processing of visually impaired users has not been investigated sufficiently and there are few guidelines on the development of haptic user interfaces, development of haptic assistive system can pose many challenges. Despite the breadth and variety of tools available for elicitation of user requirements, no single tool adequately provides the needed information to develop such a specialized system for a unique user population where the understanding of user behaviors is limited. This article explores the state-of-art of requirements engineering, discusses the challenges in developing a haptic assistive system, and proposes a methodology of combining a controlled observation in a naturalistic setting with scenario-based design for effective and efficient user requirements elicitation. A case study of developing a haptically enhanced, collaborative learning-by-feeling science education system for visually impaired students was conducted to show validity and effectiveness of the proposed methodology. The case study showed that the methodology has a variety of benefits including the reduced uncertainty and a better fit to the natural behaviors of the user population. DA - 2014/11/2/ PY - 2014/11/2/ DO - 10.1080/10447318.2014.941271 VL - 30 IS - 11 SP - 842-854 SN - 1532-7590 ER - TY - JOUR TI - STABILIZING PERFORMANCE IN NETWORKS OF QUEUES WITH TIME-VARYING ARRIVAL RATES AU - Liu, Yunan AU - Whitt, Ward T2 - PROBABILITY IN THE ENGINEERING AND INFORMATIONAL SCIENCES AB - This paper investigates extensions to feed-forward queueing networks of an algorithm to set staffing levels (the number of servers) to stabilize performance % at Quality of Service (QoS) targets in an M t / GI / s t + GI multi-server queue with a time-varying arrival rate. The model has a non-homogeneous Poisson process (NHPP), customer abandonment, and non-exponential service and patience distributions. For a single queue, simulation experiments showed that the algorithm successfully stabilizes abandonment probabilities and expected delays over a wide range of Quality-of-Service (QoS) targets. A limit theorem showed that stable performance at fixed QoS targets is achieved asymptotically as the scale increases (by letting the arrival rate grow while holding the service and patience distributions fixed). Here we extend that limit theorem to a feed-forward queueing network. However, these fixed QoS targets provide low QoS as the scale increases. Hence, these limits primarily support the algorithm with a low QoS target. For a high QoS target, effectiveness depends on the NHPP property, but the departure process never is exactly an NHPP. Thus, we investigate when a departure process can be regarded as approximately an NHPP. We show that index of dispersion for counts is effective for determining when a departure process is approximately an NHPP in this setting. In the important common case when all queues have high QoS targets, we show that both: (i) the departure process is approximately an NHPP from this perspective and (ii) the algorithm is effective. DA - 2014/10// PY - 2014/10// DO - 10.1017/s0269964814000084 VL - 28 IS - 4 SP - 419-449 SN - 1469-8951 ER - TY - JOUR TI - Relationship Between Mechanical Thresholds and Limb Use in Dogs With Coxofemoral Joint OA-Associated Pain and the Modulating Effects of Pain Alleviation From Total Hip Replacement on Mechanical Thresholds AU - Tomas, Andrea AU - Marcellin-Little, Denis J. AU - Roe, Simon C. AU - Motsinger-Reif, Alison AU - Lascelles, B. Duncan X. T2 - VETERINARY SURGERY AB - Objectives To compare von Frey mechanical quantitative sensory thresholds (mQST vF ) between pelvic limbs in dogs before unilateral total hip replacement (THR) surgery; to correlate ground reaction forces (GRF) with mQST vF ; to assess changes in mQST vF after THR surgery. Study Design Prospective clinical study. Animals Dogs (n = 44). Methods mQST vF and GRF measured using a pressure sensitive walkway were evaluated before, and 3, 6, and 12 months after, unilateral THR. Measurements were recorded from the affected (operated) pelvic limb (APL) and the non‐operated pelvic limb (NPL). Random effects analysis and forwards stepwise linear regression models were used to evaluate the influence of time since surgery and patient factors on mQST vF thresholds. Results There were no significant correlations between mQST vF data and age, bodyweight or the GRF variables. Preoperative mQST vF measured at the APL and NPL did not differ ( P = .909). mQST vF thresholds increased significantly after 12 months in NPL ( P = .047) and APL ( P = .001). In addition to time, APL mQST vF values were significantly affected by sex (higher in males, P = .010) and body condition score (higher in leaner dogs, P = .035) and NPL mQST vF values by sex ( P = .038). Conclusion Successful unilateral THR results in decreased central sensitization after 12 months. DA - 2014/7// PY - 2014/7// DO - 10.1111/j.1532-950x.2014.12160.x VL - 43 IS - 5 SP - 542-548 SN - 1532-950X ER - TY - JOUR TI - Does Touch Matter?: The Effects of Haptic Visualization on Human Performance, Behavior and Perception AU - Nam, Chang S. AU - Richard, Paul AU - Yamaguchi, Takehiko AU - Bahn, Sangwoo T2 - INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION AB - Click to increase image sizeClick to decrease image size ACKNOWLEDGEMENTSThe guest editors thank all the authors in this special issue for contributing their high-quality papers. We also thank the reviewers who have generously given their invaluable time to critically evaluate the papers within tight timelines. Finally, we hope the readers find this special issue useful for their own work. DA - 2014/11/2/ PY - 2014/11/2/ DO - 10.1080/10447318.2014.941270 VL - 30 IS - 11 SP - 839-841 SN - 1532-7590 ER - TY - JOUR TI - Directional biomechanical properties of porcine skin tissue AU - Huang, H. Y. S. AU - Huang, S. Y. AU - Frazier, C. P. AU - Prim, P. M. AU - Harrysson, O. T2 - Journal of Mechanics in Medicine and Biology DA - 2014/// PY - 2014/// VL - 14 IS - 5 ER - TY - JOUR TI - Solving conic quadratically constrained quadratic programming problems AU - Jin, Q. W. AU - Fang, S. C. AU - Lu, C. AU - Xing, W. X. T2 - Pacific Journal of Optimization DA - 2014/// PY - 2014/// VL - 10 IS - 3 SP - 503-516 ER - TY - PCOMM TI - Second-line agents for glycemic control for type 2 diabetes: Are newer agents better? Diabetes care 2014;37:1338-1345 response AU - Zhang, Y. AU - McCoy, R. G. AU - Mason, J. E. AU - Smith, S. A. AU - Shah, N. D. AU - Denton, B. T. DA - 2014/// PY - 2014/// SP - E206-207 ER - TY - JOUR TI - Durations of Bone Consolidation and External Fixation After Distraction Osteogenesis in Dogs AU - Tuohy, Joanne L. AU - Marcellin-Little, Denis J. AU - Griffith, Emily H. T2 - VETERINARY SURGERY AB - Objective To evaluate the influence of epidemiologic, surgical, and mechanical factors on the durations of bone consolidation and external fixation after distraction osteogenesis in dogs. Study Design Retrospective cohort study. Sample Population Dogs (n = 115) that had corrective osteotomy with circular external fixation (CEF; n = 152) Methods Medical and radiographic records (1992–2012) of dogs that had corrective osteotomies were reviewed. Putative variables included age, weight, gender, and breed. Surgery date, delay before distraction, rate and duration of distraction, mechanical complications, and frame removal date were recorded. Radiographic data included bone operated, bone length, osteotomy site, bone and limb size at osteotomy site, distraction distance, and CEF frame size and stiffness. Results Mean ± SD bone consolidation period was 56 ± 33 days. Mean duration of external fixation was 77 ± 35 days. Twelve fixation failures occurred. Radii healed faster than tibiae ( P < .001). Failure of fixation ( P = .002) and stiff frames ( P = .033) increased duration of bone consolidation. For the tibia, durations of bone consolidation and external fixation decreased with larger bone size relative to limb size ( P = .004). For the radius, bone consolidation duration decreased as distraction amount increased ( P = .03). Conclusion Radii healed faster than tibiae. Wearing frames with low or moderate stiffness, the absence of mechanical complications, a larger distraction distance, and a larger bone size accelerated bone consolidation. Optimizing these factors should accelerate bone consolidation and reduce the duration of external fixation. DA - 2014/11// PY - 2014/11// DO - 10.1111/j.1532-950x.2014.12189.x VL - 43 IS - 8 SP - 903-911 SN - 1532-950X ER - TY - JOUR TI - Detection of a copositive matrix over a p-th order cone AU - Zhou, J. AU - Deng, Z. B. AU - Fang, S. C. AU - Xing, W. X. T2 - Pacific Journal of Optimization DA - 2014/// PY - 2014/// VL - 10 IS - 3 SP - 593-611 ER - TY - JOUR TI - Competing risks analysis in mortality estimation for breast cancer patients from independent risk groups AU - Zhang, Shengfan AU - Ivy, Julie S. AU - Wilson, James R. AU - Diehl, Kathleen M. AU - Yankaskas, Bonnie C. T2 - HEALTH CARE MANAGEMENT SCIENCE DA - 2014/9// PY - 2014/9// DO - 10.1007/s10729-013-9255-x VL - 17 IS - 3 SP - 259-269 SN - 1572-9389 KW - Breast cancer KW - Mortality estimation KW - Competing risks KW - Cumulative incidence KW - Risk factors KW - Log(-log) transformation ER - TY - JOUR TI - An exploratory study of disaggregated clearing functions for production systems with multiple products AU - Albey, Erinç AU - Bilge, Ümit AU - Uzsoy, Reha T2 - International Journal of Production Research AB - AbstractClearing functions (CFs) have shown considerable promise for representing production capacity in production planning models due to their ability to capture the non-linear relationships between throughput, order releases and lead times. Most CFs developed to date use the total work in progress of all products, in units of processing time, as the state variable. In this paper, we investigate CFs for multi-product systems where the overall throughput of the system is affected by the product mix. We show that the aggregate work in process (WIP) variable used in the previous CF literature may lead to inaccurate estimates of expected throughput for individual products. To address this issue, we explore the use of multi-dimensional CFs (MDCFs) that use an extended definition of resource state based on the disaggregated WIP levels for individual products. Several new functional forms for MDCFs are postulated for single machine multi-product systems and their ability to represent system behaviour is assessed using simulation experiments. Results reveal that MDCFs are better able to predict system performance in the presence of mix-dependent capacity losses. We also discuss the extension of the MDCF approach to multi-stage production systems.Keywords: capacity anticipationclearing functionsproduction planningsimulation FundingThe work reported in this paper is supported by Bogazici University Research Fund [grant number 09HA303D]; NSF-TUBITAK Bilateral Cooperation Programme [grant number 109M018]; NSF [grant number CMMI-0928573]. DA - 2014/4/7/ PY - 2014/4/7/ DO - 10.1080/00207543.2014.899442 VL - 52 IS - 18 SP - 5301-5322 J2 - International Journal of Production Research LA - en OP - SN - 0020-7543 1366-588X UR - http://dx.doi.org/10.1080/00207543.2014.899442 DB - Crossref KW - capacity anticipation KW - clearing functions KW - production planning KW - simulation ER - TY - JOUR TI - The minimum p-envy location problem with requirement on minimum survival rate AU - Chanta, Sunarin AU - Mayorga, Maria E. AU - McLay, Laura A. T2 - COMPUTERS & INDUSTRIAL ENGINEERING AB - In location problems for the public sector such as emergency medical service (EMS) systems, the issue of equity is an important factor for facility design. Several measures have been proposed to minimize inequity of a system. This paper considers an extension to the minimum p-envy location model by evaluating the objective of the model based on a survival function instead of on a distance function since survival probability is directly related to patient outcomes with a constraint on minimum survival rate. The model was tested on a real world data set from the EMS system at Hanover County, VA, and also compared to other location models. The results indicate that, not only does the enhanced p-envy model reduce inequity but we also find that more lives can be saved by using the survival function objective. A sensitivity analysis on different quality of service measures (survival probability and traveled distance) and different choices of priority assigned to serving facility is discussed. DA - 2014/8// PY - 2014/8// DO - 10.1016/j.cie.2014.06.001 VL - 74 SP - 228-239 SN - 1879-0550 KW - p-Envy KW - Location models KW - Survival function KW - Emergency medical service KW - Equity ER - TY - JOUR TI - Non-L-R Type Fuzzy Parameters in Mathematical Programming Problems AU - Hu, Cheng-Feng AU - Adivar, Murat AU - Fang, Shu-Cherng T2 - IEEE TRANSACTIONS ON FUZZY SYSTEMS AB - The triangular norm-based operations in fuzzy logic usually lead to non-L-R type fuzzy sets. This study considers mathematical programming problems with non-L-R type fuzzy parameters. It shows that the fuzzy solutions to such problems can be obtained by solving an optimization problem on a mixed domain. The necessary and sufficient conditions for solving the resulting optimization problems are investigated by employing the theory of convex optimization on mixed domains. This is the first attempt to solve the fuzzy optimization problem with non-L-R type membership functions in view of optimization problems on a mixed domain. DA - 2014/10// PY - 2014/10// DO - 10.1109/tfuzz.2013.2279691 VL - 22 IS - 5 SP - 1062-1073 SN - 1941-0034 KW - Fuzzy decision making KW - fuzzy optimization KW - fuzzy set theory KW - mathematical programming KW - membership function KW - triangular norms ER - TY - JOUR TI - In vitro dermal and epidermal cellular response to titanium alloy implants fabricated with electron beam melting AU - Springer, Jessica Collins AU - Harrysson, Ola L. A. AU - Marcellin-Little, Denis J. AU - Bernacki, Susan H. T2 - MEDICAL ENGINEERING & PHYSICS AB - Transdermal osseointegrated prostheses (TOPs) are emerging as an alternative to socket prostheses. Electron beam melting (EBM) is a promising additive manufacturing technology for manufacture of custom, freeform titanium alloy (Ti6Al4V) implants. Skin ongrowth for infection resistance and mechanical stability are critically important to the success of TOP, which can be influenced by material composition and surface characteristics. We assessed viability and proliferation of normal human epidermal keratinocytes (NHEK) and normal human dermal fibroblasts (NHDF) on several Ti6Al4V surfaces: solid polished commercial, solid polished EBM, solid unpolished EBM and porous unpolished EBM. Cell proliferation was evaluated at days 2 and 7 using alamarBlue(®) and cell viability was analyzed with a fluorescence-based live-dead assay after 1 week. NHDF and NHEK were viable and proliferated on all Ti6Al4V surfaces. NHDF proliferation was highest on commercial and EBM polished surfaces. NHEK was highest on commercial polished surfaces. All EBM Ti6Al4V discs exhibited an acceptable biocompatibility profile compared to solid Ti6Al4V discs from a commercial source for dermal and epidermal cells. EBM may be considered as an option for fabrication of custom transdermal implants. DA - 2014/10// PY - 2014/10// DO - 10.1016/j.medengphy.2014.07.004 VL - 36 IS - 10 SP - 1367-1372 SN - 1873-4030 KW - Keratinocyte KW - Fibroblast KW - Additive manufacturing KW - Electron beam melting KW - Titanium alloy KW - Biocompatibility ER - TY - JOUR TI - Development and Modeling of Melt Electrohydrodynamic-Jet Printing of Phase-Change Inks for High-Resolution Additive Manufacturing AU - Wei, Chuang AU - Dong, Jingyan T2 - Journal of Manufacturing Science and Engineering-Transactions of the Asme AB - This paper presents the development and modeling a high-resolution electrohydrodynamic-jet (EHD-jet) printing process using phase-change ink (i.e., wax), which is capable of producing sub-10 μm footprints (sub-10 fL in volume) for super-resolution additive manufacturing. In this study, we successfully apply EHD-jet printing for phase-change ink (wax), which is widely used as modeling and supporting material for additive manufacturing, to achieve micron-scale features. The resolution for single droplet on substrate is around 5 μm with the thickness in the range of 1–2 μm, which provides great potential in both high-resolution 3D printing and 2D drop-on-demand microfabrication. The droplet formation in EHD printing is modeled by finite element analysis (FEA). Two important forces in EHD printing, electrostatic force and surface tension force, are modeled separately by FEA. The droplet size is obtained by balancing the electrostatic force and surface tension of the pending droplets around meniscus apex. Furthermore, to predict the droplet dimension at different process conditions, a dimensionless scaling law is identified to describe the relationship between dimensionless droplet diameter and modified nondimensional electrical bond number. Finally, the droplets in-flight velocity and impact characteristics (e.g., Reynolds number and Weber number) are modeled using the results from FEA analysis. DA - 2014/// PY - 2014/// DO - 10.1115/1.4028483 VL - 136 IS - 6 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000344393000012&KeyUID=WOS:000344393000012 KW - electrohydrodynamic-jet printing KW - FEA modeling KW - phase-change ink KW - microscale additive manufacturing KW - 3D printing ER - TY - JOUR TI - Capability analysis of the variable measurement system with fuzzy data AU - Moheb-Alizadeh, H. T2 - Applied Mathematical Modelling DA - 2014/// PY - 2014/// VL - 38 IS - 19-20 SP - 4559-4573 ER - TY - JOUR TI - Systems Engineering Methods for Enhancing the Value Stream in Public Health Preparedness: The Role of Markov Models, Simulation, and Optimization AU - Yaylali, Emine AU - Ivy, Julie Simmons AU - Taheri, Javad T2 - PUBLIC HEALTH REPORTS AB - Large-scale incidents such as the 2009 H1N1 outbreak, the 2011 European Escherichia coli outbreak, and Hurricane Sandy demonstrate the need for continuous improvement in emergency preparation, alert, and response systems globally. As questions relating to emergency preparedness and response continue to rise to the forefront, the field of industrial and systems engineering (ISE) emerges, as it provides sophisticated techniques that have the ability to model the system, simulate, and optimize complex systems, even under uncertainty.We applied three ISE techniques--Markov modeling, operations research (OR) or optimization, and computer simulation--to public health emergency preparedness.We present three models developed through a four-year partnership with stakeholders from state and local public health for effectively, efficiently, and appropriately responding to potential public health threats: (1) an OR model for optimal alerting in response to a public health event, (2) simulation models developed to respond to communicable disease events from the perspective of public health, and (3) simulation models for implementing pandemic influenza vaccination clinics representative of clinics in operation for the 2009-2010 H1N1 vaccinations in North Carolina.The methods employed by the ISE discipline offer powerful new insights to understand and improve public health emergency preparedness and response systems. The models can be used by public health practitioners not only to inform their planning decisions but also to provide a quantitative argument to support public health decision making and investment. DA - 2014/// PY - 2014/// DO - 10.1177/00333549141296s419 VL - 129 SP - 145-153 SN - 0033-3549 ER - TY - JOUR TI - Spectrum management techniques for elastic optical networks: A survey AU - Talebi, Sahar AU - Alam, Furcian AU - Katib, Lyad AU - Khamis, Mohamed AU - Salama, Reda AU - Rouskas, George N. T2 - OPTICAL SWITCHING AND NETWORKING AB - In recent years, OFDM has been the focus of extensive research efforts in optical transmission and networking, initially as a means to overcome physical impairments in optical communications. However, unlike, say, in wireless LANs or xDSL systems where OFDM is deployed as a transmission technology in a single link, in optical networks it is being considered as the technology underlying the novel elastic network paradigm. Consequently, network-wide spectrum management arises as the key challenge to be addressed in network design and control. In this work, we review and classify a range of spectrum management techniques for elastic optical networks, including offline and online routing and spectrum assignment (RSA), distance-adaptive RSA, fragmentation-aware RSA, traffic grooming, and survivability. DA - 2014/7// PY - 2014/7// DO - 10.1016/j.osn.2014.02.003 VL - 13 SP - 34-48 SN - 1872-9770 KW - Elastic optical networks KW - Spectrum management KW - Routing and spectrum assignment ER - TY - JOUR TI - Effects of Laptop Touchpad Texturing on User Performance AU - Suresh, Sameerajan AU - Kaber, David AU - Clamann, Michael T2 - INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION AB - This research assessed user performance with different laptop touchpad textures. In specific, the study measured discrete movement task time and accuracy. It was hypothesized that texturing would increase task times but improve accuracy by providing users with tactile references. A variable representing the frictional potential of pads was introduced into an established model of discrete movement performance (Fitts’ Law) in an attempt to accurately model user performance under experimental task conditions. Results revealed touchpad texturing to degrade task performance. However, accuracy in pointing tasks was not significantly affected. Results also revealed that the expanded form of Fitts’ Law, including a parameter for representing the frictional potential of pad texturing, was more predictive of actual movement times than the original form of the Law. Results from the study increase understanding of the effects of touchpad texture on human motor control behavior and provide some guidance for future pad design. DA - 2014/6/3/ PY - 2014/6/3/ DO - 10.1080/10447318.2014.888502 VL - 30 IS - 6 SP - 470-479 SN - 1532-7590 ER - TY - JOUR TI - Priority dispatching strategies for EMS systems AU - Bandara, Damitha AU - Mayorga, Maria E. AU - McLay, Laura A. T2 - JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY AB - Emergency medical service (EMS) systems provide urgent medical care and transport. In this study we implement dispatching policies for EMS systems that incorporate the severity of the call in order to increase the survival probability of patients. A simulation model is developed to evaluate the performance of EMS systems. Performance is measured in terms of patients’ survival probability, since survival probability more directly mirrors patient outcomes. Different response strategies are evaluated utilizing several examples to study the nature of the optimal dispatching policy. The results show that dispatching the closest vehicle is not always optimal and dispatching vehicles considering priority of the call leads to an increase in the average survival probability of patients. A heuristic algorithm, that is easy to implement, is developed to dispatch ambulances for large-scale EMS systems. Computational examples show that the dispatching algorithm is valuable in increasing the patients’ survival probability. DA - 2014/4// PY - 2014/4// DO - 10.1057/jors.2013.95 VL - 65 IS - 4 SP - 572-587 SN - 1476-9360 KW - health service KW - dispatching KW - patient survivability KW - simulation KW - heuristics ER - TY - JOUR TI - High-resolution ac-pulse modulated electrohydrodynamic jet printing on highly insulating substrates AU - Wei, Chuang AU - Qin, Hantang AU - Ramirez-Iglesias, Nakaira A. AU - Chiu, Chia-Pin AU - Lee, Yuan-shin AU - Dong, Jingyan T2 - JOURNAL OF MICROMECHANICS AND MICROENGINEERING AB - This paper presents a new high-resolution ac-pulse modulated electrohydrodynamic (EHD)-jet printing technology on highly insulating substrates for drop-on-demand fabrication of electrical features and interconnects using silver nanoink. In traditional EHD-jet printing, the remained charge of the printed droplets changes the electrostatic field distribution and interrupts the follow-on printing behavior, especially for highly insulating substrates which have slow charge decay rates. The residue charge makes the control of EHD-jet printing very challenging for high-resolution continuous features. In this paper, by using modulated ac-pulsed voltage, the EHD-jet printing process switches the charge polarity of the consequent droplets to neutralize the charge on the substrate. The effect of the residue charge is minimized, which enables high-resolution printing of continuous patterns. Moreover, by modulating the pulse frequency, voltage, and duration, the EHD-jet printing behavior can be controlled with respect to printing speed/frequency and droplet size. Printing frequency is directly controlled by the pulse frequency, and the droplet dimension is controlled by the voltage and the duration of the pulse. We demonstrated that ac-pulse modulated EHD-jet printing can overcome the long-predicated charge accumulation problem on highly insulating substrates, and potentially be applied to many flexible electronics applications. DA - 2014/4// PY - 2014/4// DO - 10.1088/0960-1317/24/4/045010 VL - 24 IS - 4 SP - SN - 1361-6439 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84897548526&partnerID=MN8TOARS KW - AC-pulse modulation KW - drop-on-demand KW - electrohydrodynamic jet printing ER - TY - JOUR TI - Fabricating copper components with electron beam melting AU - Frigola, P. AU - Harrysson, O. A. AU - Horn, T. J. AU - West, H. A. AU - Aman, R. L. AU - Rigsbee, J. M. AU - Ramirez, D. A. AU - Murr, L. E. AU - Medina, F. AU - Wicker, R. B. AU - Rodriguez, E. T2 - Advanced Materials & Processes DA - 2014/// PY - 2014/// VL - 172 IS - 7 SP - 20-24 ER - TY - JOUR TI - Correction of Biapical Radial Deformities by Use of Bi-Level Hinged Circular External Fixation and Distraction Osteogenesis in 13 Dogs AU - Kwan, Toni W. AU - Marcellin-Little, Denis J. AU - Harrysson, Ola L. A. T2 - VETERINARY SURGERY AB - To describe clinical, radiographic, and computed tomographic (CT) assessment of biapical deformities of the radius in dogs and evaluate the effectiveness of their management by use of bilevel hinged circular external fixation frames.Prospective, non-randomized cohort study.Dogs (N = 26: 13 with 14 limbs operated, 13 controls).CT scans of the forelimbs were performed and CT-based polymer replicas prepared. Rotation within the elbow joint, varus of the proximal portion of the radius, radial torsion, valgus of the distal portion of the radius, procurvatum, and rotation within the carpal joint were measured on radiographs, on polymer replicas, and on CT scans. Bilevel hinged circular external fixation frames were assembled on polymer replicas and identical frames were placed on dogs. Torsion was corrected acutely and angulation was corrected progressively. Functional outcome was assessed subjectively.Buckling was present preoperatively in operated limbs. Mean (± SD) varus of the proximal portion of the radius was 36 ± 8°, valgus of the distal portion of the radius was 32 ± 5°, external radial torsion was 35 ± 6°, procurvatum was 41 ± 10°, and medial translation was 44 ± 11 mm. Treatment duration was 80 ± 24 days. Buckling was not observed after surgery. Lameness scores improved in all dogs (P < .001).The forelimbs of dogs with severe biapical radial deformities buckle and have increased radial head rotation and radial torsion. Biapical radial deformities can be managed with proximal and distal radial osteotomies and bilevel hinged circular external fixation. DA - 2014/3// PY - 2014/3// DO - 10.1111/j.1532-950x.2014.12114.x VL - 43 IS - 3 SP - 316-329 SN - 1532-950X ER - TY - JOUR TI - Comparison of two stretching methods and optimization of stretching protocol for the piriformis muscle AU - Gulledge, Brett M. AU - Marcellin-Little, Denis J. AU - Levine, David AU - Tillman, Larry AU - Harrysson, Ola L. A. AU - Osborne, Jason A. AU - Baxter, Blaise T2 - MEDICAL ENGINEERING & PHYSICS AB - Piriformis syndrome is an uncommon diagnosis for a non-discogenic form of sciatica whose treatment has traditionally focused on stretching the piriformis muscle (PiM). Conventional stretches include hip flexion, adduction, and external rotation. Using three-dimensional modeling, we quantified the amount of (PiM) elongation resulting from two conventional stretches and we investigated by use of a computational model alternate stretching protocols that would optimize PiM stretching. Seven subjects underwent three CT scans: one supine, one with hip flexion, adduction, then external rotation (ADD stretch), and one with hip flexion, external rotation, then adduction (ExR stretch). Three-dimensional bone models were constructed from the CT scans. PiM elongation during these stretches, femoral neck inclination, femoral head anteversion, and trochanteric anteversion were measured. A computer program was developed to map PiM length over a range of hip joint positions and was validated against the measured scans. ExR and ADD stretches elongated the PiM similarly by approximately 12%. Femoral head and greater trochanter anteversion influenced PiM elongation. Placing the hip joints in 115° of hip flexion, 40° of external rotation and 25° of adduction or 120° of hip flexion, 50° of external rotation and 30° of adduction increased PiM elongation by 30-40% compared to conventional stretches (15.1 and 15.3% increases in PiM muscle length, respectively). ExR and ADD stretches elongate the PiM similarly and therefore may have similar clinical effectiveness. The optimized stretches led to larger increases in PiM length and may be more easily performed by some patients due to increased hip flexion. DA - 2014/2// PY - 2014/2// DO - 10.1016/j.medengphy.2013.10.016 VL - 36 IS - 2 SP - 212-218 SN - 1873-4030 KW - Biomodeling KW - Computational modeling KW - Piriformis muscle KW - Stretching ER - TY - JOUR TI - Combined DES/SD model of breast cancer screening for older women, II: screening-and-treatment simulation AU - Tejada, Jeremy J. AU - Ivy, Julie S. AU - King, Russell E. AU - Wilson, James R. AU - Ballan, Matthew J. AU - Kay, Michael G. AU - Diehl, Kathleen M. AU - Yankaskas, Bonnie C. T2 - IIE Transactions AB - In the second article of a two-article sequence, the focus is on a simulation model for screening and treatment of breast cancer in U.S. women of age 65+. The first article details a natural-history simulation model of the incidence and progression of untreated breast cancer in a representative simulated population of older U.S. women, which ultimately generates a database of untreated breast cancer histories for individuals in the simulated population. Driven by the resulting database, the screening-and-treatment simulation model is composed of discrete-event simulation (DES) and system dynamics (SD) submodels. For each individual in the simulated population, the DES submodel simulates screening policies and treatment procedures to estimate the resulting survival rates and the costs of screening and treatment. The SD submodel represents the overall structure and operation of the U.S. system for detecting and treating breast cancer. The main results and conclusions are summarized, including a final recommendation for annual screening between ages 65 and 80. A discussion is also presented on how both the natural-history and screening-and-treatment simulations can be used for performance comparisons of proposed screening policies based on overall cost-effectiveness, the numbers of life-years and quality-adjusted life-years saved, and the main components of the total cost incurred by each policy. DA - 2014/3/28/ PY - 2014/3/28/ DO - 10.1080/0740817x.2013.851436 VL - 46 IS - 7 SP - 707-727 J2 - IIE Transactions LA - en OP - SN - 0740-817X 1545-8830 UR - http://dx.doi.org/10.1080/0740817X.2013.851436 DB - Crossref KW - discrete-event simulation KW - breast cancer KW - medical decision making KW - screening older U.S. women KW - Health care KW - system dynamics KW - combined discrete-continuous simulation ER - TY - JOUR TI - Branch and Bound Algorithms for Resource Constrained Project Scheduling Problem Subject to Nonrenewable Resources with Prescheduled Procurement AU - Chaleshtarti, A. Shirzadeh AU - Shadrokh, S. AU - Fathi, Y. T2 - MATHEMATICAL PROBLEMS IN ENGINEERING AB - A lot of projects in real life are subject to some kinds of nonrenewable resources that are not exactly similar to the type defined in the project scheduling literature. The difference stems from the fact that, in those projects, contrary to the common assumption in the project scheduling literature, nonrenewable resources are not available in full amount at the beginning of the project, but they are procured along the project horizon. In this paper, we study this different type of nonrenewable resources. To that end, we extend the resource constrained project scheduling problem (RCPSP) by this resource type (RCPSP-NR) and customize four basic branch and bound algorithms of RCPSP for it, including precedence tree, extension alternatives, minimal delaying alternatives, and minimal forbidden sets. Several bounding and fathoming rules are introduced to the algorithms to shorten the enumeration process. We perform comprehensive experimental analysis using the four customized algorithms and also CPLEX solver. DA - 2014/// PY - 2014/// DO - 10.1155/2014/634649 VL - 2014 SP - SN - 1563-5147 ER - TY - JOUR TI - Assessing the impact of alternative continuous improvement programmes in a flow shop using system dynamics AU - Godinho Filho, Moacir AU - Uzsoy, Reha T2 - INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH AB - AbstractWe use a system dynamics simulation model based on the Factory Physics perspective to study the cumulative effect of continuous improvement in arrival variability, process variability, defect rate, time to failure, repair time and set-up time on operating curves in a flow-shop environment. We find that small, simultaneous improvements at multiple locations in the line can provide reductions in cycle time comparable to, or sometimes superior to, those obtained by a major improvement at a single location. The reduction of process variability is often an excellent alternative to reducing the mean of a parameter, because process variability at a given station affects not only that station, but all downstream stations due to its impact on flow variability. Improvements at non-bottleneck stations also have significant benefits, again by reducing the variability of flow to the bottleneck station. These results suggest a broader interpretation of some aspects of the Theory of Constraints, and help explain the successful results of the Toyota Production System.Keywords: operating curvecontinuous improvementfactory physics DA - 2014/5/19/ PY - 2014/5/19/ DO - 10.1080/00207543.2013.860249 VL - 52 IS - 10 SP - 3014-3031 SN - 1366-588X KW - factory physics KW - continuous improvement KW - operating curve ER - TY - JOUR TI - A comparison of multiple linear regression approaches for fitting clearing functions to empirical data AU - Kacar, Necip Baris AU - Uzsoy, Reha T2 - INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH AB - We examine the problem of estimating clearing functions (CFs) that describe the expected output of a production resource as a function of its expected workload from empirical data. We use a simulation model of a scaled-down wafer fabrication facility to generate the data and evaluate the performance of the resulting CFs. We compare the performance of production plans generated using load based and product based CFs and find that using load based CFs yields better performance. DA - 2014/6/3/ PY - 2014/6/3/ DO - 10.1080/00207543.2013.864052 VL - 52 IS - 11 SP - 3164-3184 SN - 1366-588X KW - workload-dependent lead times KW - linear programming KW - simulation KW - production planning KW - clearing function ER - TY - JOUR TI - Upper visual field advantage in localizing a target among distractors AU - Feng, Jing AU - Spence, Ian T2 - I-PERCEPTION AB - Biases exist in many perceptual and cognitive functions. Since visual attention plays an important role in a wide range of perceptual and cognitive processes, any bias in the spatial distribution of attention is likely to be a significant source of perceptual and cognitive asymmetries. An attentional visual field task (AVF) requiring localization of a target among distractors was used to assess possible asymmetries in attentional processing in the vertical meridian. The results showed a bias favoring the upper visual field, suggesting a potentially important role of attention in perceptual and cognitive asymmetries. DA - 2014/// PY - 2014/// DO - 10.1068/i0625rep VL - 5 IS - 2 SP - 97-100 SN - 2041-6695 KW - spatial attention KW - distribution of attention KW - attentional bias KW - individual difference ER - TY - JOUR TI - The impact of lot-sizing in multiple product environments with congestion AU - Kang, Yongha AU - Albey, Erinc AU - Hwang, Sangwook AU - Uzsoy, Reha T2 - JOURNAL OF MANUFACTURING SYSTEMS AB - We present a production planning model for a multiple product single machine dynamic lot-sizing problem with congestion. Using queuing models, we develop a set of functions to capture the nonlinear relationship between the output, lot sizes and available work in process inventory levels of all products in the system. We then embed these functions in a nonlinear optimization model with continuous variables, and construct an approximate solution to the original problem by rounding the resulting fractional solution. Computational experiments show that our model with congestion provides significantly better flow time and inventory performance than a benchmark model that does not consider the effects of congestion. These advantages arise from the use of multiple smaller lots in a period instead of a single large lot as suggested by conventional fixed-charge models without congestion. DA - 2014/7// PY - 2014/7// DO - 10.1016/j.jmsy.2014.04.003 VL - 33 IS - 3 SP - 436-444 SN - 1878-6642 KW - Nonlinear programming KW - Dynamic lot sizing KW - Queueing KW - Congestion KW - Simulation KW - Rounding heuristics ER - TY - JOUR TI - The Effects of Visual and Cognitive Distractions on Operational and Tactical Driving Behaviors AU - Zhang, Yu AU - Kaber, David B. AU - Rogers, Meghan AU - Liang, Yulan AU - Gangakhedkar, Shruti T2 - HUMAN FACTORS AB - This study tested the effects of two fundamental forms of distraction, including visual-manual and cognitive-audio distraction, with comparison under both operational and tactical driving. Strategic control remains for future study.Driving is a complex control task involving operational, tactical, and strategic control. Although operational control, such as lead-car following, has been studied, the influence of in-vehicle distractions on higher levels of control, including tactical and strategic, remains unclear.Two secondary tasks were designed to independently represent visual-manual and cognitive-audio distractions, based on multiple resource theory. Drivers performed operational vehicle control maneuvers (lead-car following) or tactical control maneuvers (passing) along with the distraction tasks in a driving simulator. Response measures included driving performance and visual behavior.Results revealed drivers' ability to accommodate either visual or cognitive distractions in following tasks but not in passing. The simultaneous distraction condition led to the greatest decrement in performance.Findings support the need to assess the impacts of in-vehicle distraction on different levels of driving control. Future study should investigate driver distraction under strategic control. DA - 2014/5// PY - 2014/5// DO - 10.1177/0018720813495279 VL - 56 IS - 3 SP - 592-604 SN - 1547-8181 KW - tactical vehicle control KW - operational vehicle control KW - attention resource theory KW - eye tracking KW - driver distraction ER - TY - JOUR TI - TRF1 and TRF2 use different mechanisms to find telomeric DNA but share a novel mechanism to search for protein partners at telomeres AU - Lin, Jiangguo AU - Countryman, Preston AU - Buncher, Noah AU - Kaur, Parminder AU - Longjiang, E. AU - Zhang, Yiyun AU - Gibson, Greg AU - You, Changjiang AU - Watkins, Simon C. AU - Piehler, Jacob AU - Opresko, Patricia L. AU - Kad, Neil M. AU - Wang, Hong T2 - NUCLEIC ACIDS RESEARCH AB - Human telomeres are maintained by the shelterin protein complex in which TRF1 and TRF2 bind directly to duplex telomeric DNA. How these proteins find telomeric sequences among a genome of billions of base pairs and how they find protein partners to form the shelterin complex remains uncertain. Using single-molecule fluorescence imaging of quantum dot-labeled TRF1 and TRF2, we study how these proteins locate TTAGGG repeats on DNA tightropes. By virtue of its basic domain TRF2 performs an extensive 1D search on nontelomeric DNA, whereas TRF1's 1D search is limited. Unlike the stable and static associations observed for other proteins at specific binding sites, TRF proteins possess reduced binding stability marked by transient binding (∼ 9-17 s) and slow 1D diffusion on specific telomeric regions. These slow diffusion constants yield activation energy barriers to sliding ∼ 2.8-3.6 κ(B)T greater than those for nontelomeric DNA. We propose that the TRF proteins use 1D sliding to find protein partners and assemble the shelterin complex, which in turn stabilizes the interaction with specific telomeric DNA. This 'tag-team proofreading' represents a more general mechanism to ensure a specific set of proteins interact with each other on long repetitive specific DNA sequences without requiring external energy sources. DA - 2014/2// PY - 2014/2// DO - 10.1093/nar/gkt1132 VL - 42 IS - 4 SP - 2493-2504 SN - 1362-4962 ER - TY - JOUR TI - Second- line agents for glycemic control for type 2 diabetes: Are newer agents better? AU - Zhang, Y. H. AU - McCoy, R. G. AU - Mason, J. E. AU - Smith, S. A. AU - Shah, N. D. AU - Denton, B. T. T2 - Diabetes Care DA - 2014/// PY - 2014/// VL - 37 IS - 5 SP - 1338-1345 ER - TY - JOUR TI - Recommendations for dispatching emergency vehicles under multitiered response via simulation AU - Sudtachat, Kanchala AU - Mayorga, Maria E. AU - McLay, Laura A. T2 - INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH AB - Abstract Emergency medical service (EMS) systems provide medical care and transportation. While many real‐world systems use multiple vehicle types to attend different call priorities, few guidelines exist about which vehicles to allocate in multitiered responses where more than one vehicle is sent per call. This paper makes recommendations for multiple‐unit dispatch to multiple call priorities based on simulation optimization and heuristics. The objective is to maximize the overall expected survival probability of patients classified as “life‐threatening”. We assume two types of medical units and three call priorities; and that information may be updated when the medical unit arrives on‐scene. First, we study the optimal dispatching policies through several examples. Numerical results show that dispatching while considering call priorities, rather than dispatching the closest units, improves EMS system effectiveness. A heuristic algorithm is developed for large‐scale problems. A comparison between the heuristic and closest policy is demonstrated using real‐world data. DA - 2014/7// PY - 2014/7// DO - 10.1111/itor.12083 VL - 21 IS - 4 SP - 581-617 SN - 1475-3995 KW - emergency medical service KW - simulation KW - multiple-unit dispatch KW - call priorities ER - TY - JOUR TI - Examining the Effects of Conformal Terrain Features in Advanced Head-Up Displays on Flight Performance and Pilot Situation Awareness AU - Kim, Sang-Hwan AU - Kaber, David B. T2 - HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES AB - Abstract Synthetic vision systems (SVS) render terrain features for pilots through cockpit displays using a GPS database and three‐dimensional graphical models. Enhanced vision systems (EVS) present infrared imagery of terrain using a forward‐looking sensor in the nose of an aircraft. The ultimate goal of SVS and EVS technologies is to support pilots in achieving safety under low‐visibility and night conditions comparable to clear, day conditions. This study assessed pilot performance and situation awareness (SA) effects of SVS and EVS imagery in an advanced head‐up display (HUD) during a simulated landing approach under instrument meteorological conditions. Videos of the landing with various HUD configurations were presented to eight pilots with a superimposed tracking task. The independent variables included four HUD feature configurations (baseline [no terrain imagery], SVS, EVS, and a combination of SVS and EVS), two visibility conditions, and four legs of the flight. Results indicated that SVS increased overall SA but degraded flight path control performance because of visual confusion with other display features. EVS increased flight path control accuracy but decreased system (aircraft) awareness because of visual distractions. The combination of SVS and EVS generated offsetting effects. Display configurations did not affect pilot spatial awareness. Flight performance was not different among phases of the approach, but levels and types of pilot SA did vary from leg to leg. These results are applicable to development of adaptive HUD features to support pilot performance. They support the use of multidimensional measures of SA for insight on pilot information processing with advanced aviation displays. © 2012 Wiley Periodicals, Inc. DA - 2014/// PY - 2014/// DO - 10.1002/hfm.20501 VL - 24 IS - 4 SP - 386-402 SN - 1520-6564 KW - Head-up display (HUD) KW - Synthetic vision systems (SVS) KW - Enhanced vision systems (EVS) KW - Flight performance KW - Pilot SA ER - TY - JOUR TI - Biomechanical Evaluation of the Influence of an Intramedullary Pin on the Stability of a Feline Ilial Fracture Model Stabilized With a Bone Plate AU - Krebs, Renee C. AU - Roe, Simon C. AU - Lascelles, B. Duncan X. AU - Marcellin-Little, Denis J. AU - Trumpatori, Brian J. AU - Spodnick, Gary T2 - VETERINARY SURGERY AB - Objective To compare the mechanical properties of feline ilial fractures stabilized with either a plate (P), or a plate and IM pin (P + P). Study Design Mechanical study. Sample Population Cadaveric cat pelvii (n = 10). Methods Feline ilial fractures (n = 20) stabilized with either P or P + P were subjected to 100 nondestructive load cycles, then loaded to failure. Deformation after cycling, yield load and displacement, stiffness and load at 2 mm of displacement were compared between groups. Results There were no significant differences between groups for any of the parameters. Variability of data was much larger for the P + P group. Conclusions No biomechanical advantage was demonstrated. The P + P constructs were not significantly stronger than plates alone in this acutely loaded cadaveric model. DA - 2014/2// PY - 2014/2// DO - 10.1111/j.1532-950x.2013.12091.x VL - 43 IS - 2 SP - 114-119 SN - 1532-950X ER - TY - JOUR TI - The relevance of the "alphorn of uncertainty" to the financial management of projects under uncertainty AU - Zhang, J. W. AU - Elmaghraby, S. E. T2 - European Journal of Operational Research DA - 2014/// PY - 2014/// VL - 238 IS - 1 SP - 65-76 ER - TY - JOUR TI - Optimal two-phase vaccine allocation to geographically different regions under uncertainty AU - Yarmand, Hamed AU - Ivy, Julie S. AU - Denton, Brian AU - Lloyd, Alun L. T2 - EUROPEAN JOURNAL OF OPERATIONAL RESEARCH AB - In this article, we consider a decision process in which vaccination is performed in two phases to contain the outbreak of an infectious disease in a set of geographic regions. In the first phase, a limited number of vaccine doses are allocated to each region; in the second phase, additional doses may be allocated to regions in which the epidemic has not been contained. We develop a simulation model to capture the epidemic dynamics in each region for different vaccination levels. We formulate the vaccine allocation problem as a two-stage stochastic linear program (2-SLP) and use the special problem structure to reduce it to a linear program with a similar size to that of the first stage problem. We also present a Newsvendor model formulation of the problem which provides a closed form solution for the optimal allocation. We construct test cases motivated by vaccine planning for seasonal influenza in the state of North Carolina. Using the 2-SLP formulation, we estimate the value of the stochastic solution and the expected value of perfect information. We also propose and test an easy to implement heuristic for vaccine allocation. We show that our proposed two-phase vaccination policy potentially results in a lower attack rate and a considerable saving in vaccine production and administration cost. DA - 2014/2/16/ PY - 2014/2/16/ DO - 10.1016/j.ejor.2013.08.027 VL - 233 IS - 1 SP - 208-219 SN - 1872-6860 KW - OR in health services KW - Epidemic control KW - Two-phase vaccine allocation KW - Stochastic linear program KW - Newsvendor model KW - Value of stochastic solution ER - TY - JOUR TI - In celebration of Professor Min-yi Yue's 95th birthday AU - Bai, Y. Q. AU - Fang, S. C. AU - Han, J. Y. AU - Xiu, N. H. T2 - Optimization DA - 2014/// PY - 2014/// VL - 63 IS - 6 SP - 827-828 ER - TY - JOUR TI - Combined-Semantics Equivalence and Minimization of Conjunctive Queries AU - Chirkova, Rada T2 - COMPUTER JOURNAL DA - 2014/5// PY - 2014/5// DO - 10.1093/comjnl/bxt032 VL - 57 IS - 5 SP - 775-795 SN - 1460-2067 KW - combined semantics for query processing KW - query minimization KW - query equivalence ER - TY - JOUR TI - Cockpit Displays of Traffic Information and Pilot Bias in Time-to-Contact Judgments AU - Pankok, Carl, Jr. AU - Kaber, David B. T2 - AVIATION SPACE AND ENVIRONMENTAL MEDICINE AB - Pilots are susceptible to over-reliance on distance when making relative time-to-contact (TTC) judgments of surrounding intruders, referred to as "the distance bias." We tested the effect of adding perceptual cues and an information feature to cockpit displays of traffic information to mitigate this bias.There were 14 general aviation pilots who participated in a simulated flight scenario and were asked to make relative TTC judgments. Three levels of perceptual cue (blinking, color-change, and no-cue) were crossed with two levels of velocity data tag (present and absent) with identification of the highest risk intruder as a response.Perceptual cues were associated with more accurate high-risk intruder selection (color = 95.95% correct, blinking = 95.98%, no-cue = 87.89%), decreased response time (color = 3.68 s, blinking = 3.19 s, no-cue = 6.08 s), reduced visual attention demand (color = 57% of attention, blinking = 58%, no-cue = 62%), lower workload ratings (color = 28.38/100, blinking = 29.66/100, no-cue = 48.91/100), and higher performance confidence ratings (color = 83.92/100, blinking = 82.71/100, no-cue = 58.85/100) than the no-cue displays. There was no difference between blinking and color cue displays. The data tag was associated with lower response times (present = 4.13 s, absent = 4.50 s) and higher confidence ratings (present = 78.69/100, absent = 71.63/100) than displays without. Displays including the blinking cue, color-change cue, and data tag were preferred over displays that did not include these features (color = 8 pilots, blinking = 6, no-cue = 0).The added display features were effective in mitigating the effect of the distance bias on pilot performance measures and received favorable subjective ratings. DA - 2014/6// PY - 2014/6// DO - 10.3357/asem.3810.2014 VL - 85 IS - 6 SP - 597-604 SN - 1943-4448 KW - cockpit automation KW - traffic information displays KW - aircraft pilot performance KW - human factors in display design ER - TY - JOUR TI - Adaptive computable approximation to cones of nonnegative quadratic functions AU - Lu, Cheng AU - Jin, Qingwei AU - Fang, Shu-Cherng AU - Wang, Zhenbo AU - Xing, Wenxun T2 - OPTIMIZATION AB - Cones of nonnegative quadratic functions are keys to the understanding of quadratic optimization problems, since any quadratically constrained quadratic programming problem can be reformulated as a linear conic programming problem over such a cone. This paper proposes an adaptive computable approximation scheme to cones of nonnegative quadratic functions and uses it for solving linear conic programming problems over such a cone. We study some basic properties of cones of nonnegative quadratic functions and present a class of simple cones with computable linear matrix inequalities representations. Building on these simple cones, we design a computable approximation scheme for handling a general cone of nonnegative quadratic functions. When the scheme is applied for solving linear conic programming problems over a cone of nonnegative quadratic functions, we incorporate an adaptive approach to enhance the performance of the proposed computable approximation scheme. The computational performance and theoretic convergence proof of the proposed adaptive computable approximation scheme are shown for solving box-constrained quadratic programming problems. DA - 2014/6/3/ PY - 2014/6/3/ DO - 10.1080/02331934.2014.895899 VL - 63 IS - 6 SP - 955-980 SN - 1029-4945 KW - conic programming KW - quadratic programming KW - cones of nonnegative quadratic functions KW - conic approximation KW - lower bounds KW - 49N15 KW - 49M37 KW - 90C26 KW - 90C20 ER - TY - JOUR TI - QUADRATIC OPTIMIZATION OVER ONE FIRST-ORDER CONE AU - Guo, Xiaoling AU - Deng, Zhibin AU - Fang, Shu-Cherng AU - Xing, Wenxun T2 - JOURNAL OF INDUSTRIAL AND MANAGEMENT OPTIMIZATION AB - This paper studies the first-order cone constrained homogeneous quadratic programming problem. For efficient computation, the problem is reformulated as a linear conic programming problem. A union of second-order cones are designed to cover the first-order cone such that a sequence of linear conic programming problems can be constructed to approximate the conic reformulation. Since the cone of nonnegative quadratic forms over a union of second-order cones has a linear matrix inequalities representation, each linear conic programming problem in the sequence is polynomial-time solvable by applying semidefinite programming techniques. The convergence of the sequence is guaranteed when the union of second-order cones gets close enough to the first-order cone. In order to further improve the efficiency, an adaptive scheme is adopted. Numerical experiments are provided to illustrate the efficiency of the proposed approach. DA - 2014/7// PY - 2014/7// DO - 10.3934/jimo.2014.10.945 VL - 10 IS - 3 SP - 945-963 SN - 1553-166X KW - Quadratic programming KW - cone of nonnegative quadratic forms KW - first-order cone KW - linear conic programming KW - adaptive scheme ER - TY - JOUR TI - Modeling the evolution of dependency between demands, with application to inventory planning AU - Norouzi, Amirhosein AU - Uzsoy, Reha T2 - IIE TRANSACTIONS AB - This article shows that the progressive realization of uncertain demands across successive discrete time periods through additive or multiplicative forecast updates results in the evolution of the conditional covariance of demand in addition to its conditional mean. A dynamic inventory model with forecast updates is used to illustrate the application of the proposed method. It is shown that the optimal inventory policy depends on conditional covariances, and a model without information updates is used to quantify the benefit of using the available forecast information in the presence of additive forecast updates. The proposed approach yields significant reductions in system costs and is applicable to a wide range of production and inventory models. It is also shown that the proposed approach can be extended to the case of multiplicative forecast updates and directions for future work are suggested. DA - 2014/1/2/ PY - 2014/1/2/ DO - 10.1080/0740817x.2013.803637 VL - 46 IS - 1 SP - 55-66 SN - 1545-8830 KW - Forecast evolution KW - conditional covariance KW - base stock policy KW - inventory planning ER - TY - JOUR TI - Evaluation of varying morphological parameters on the biomechanics of a cranial cruciate ligament-deficient or intact canine stifle joint with a computer simulation model AU - Brown, Nathan P. AU - Bertocci, Gina E. AU - Marcellin-Little, Denis J. T2 - AMERICAN JOURNAL OF VETERINARY RESEARCH AB - To investigate the influence of varying morphological parameters on canine stifle joint biomechanics by use of a 3-D rigid-body canine pelvic limb computer model that simulated an intact and cranial cruciate ligament (CrCL)-deficient stifle joint across the stance phase of gait at a walk.Data from computer simulations.Computer model morphological parameters, including patellar ligament insertion location, tibial plateau angle (TPA), and femoral condyle diameter (FCD), were incrementally altered to determine their influence on outcome measures (ligament loads, relative tibial translation, and relative tibial rotation) during simulation of the stance phase of gait at a walk. Outcome measures were assessed for each scenario and compared between an intact and CrCL-deficient stifle joint with the sensitivity index (the percentage change in outcome measure divided by the percentage change in input parameter).In a CrCL-intact stifle joint, ligament loads were most sensitive to TPA. In a CrCL-deficient stifle joint, outcome measures were most sensitive to TPA with the exception of caudal cruciate ligament and lateral collateral ligament loads, which were sensitive to FCD and TPA. Relative tibial translation was sensitive to TPA and patellar ligament insertion location, whereas relative tibial rotation was most sensitive to TPA.The computer model sensitivity analyses predicted that individual parameters, particularly TPA and FCD, influence stifle joint biomechanics. Therefore, tibial and femoral morphological parameters may affect the likelihood, prevention, and management of CrCL deficiency. DA - 2014/1// PY - 2014/1// DO - 10.2460/ajvr.75.1.26 VL - 75 IS - 1 SP - 26-33 SN - 1943-5681 ER - TY - JOUR TI - Algorithms for Time-Varying Networks of Many-Server Fluid Queues AU - Liu, Yunan AU - Whitt, Ward T2 - INFORMS JOURNAL ON COMPUTING AB - Motivated by large-scale service systems with network structure, we introduced in a previous paper a time-varying open network of many-server fluid queues with customer abandonment from each queue and time-varying proportional routing among the queues, and showed how performance functions can be determined. The deterministic fluid model serves as an approximation for the corresponding non-Markovian stochastic network of many-server queues with Markovian routing, experiencing periods of overloading at the queues. In this paper we develop a new algorithm for the previous model and generalize the model to include non-exponential service-time distributions. In this paper we report results of implementing the algorithms and studying their computational complexity. We also conduct simulation experiments to confirm that the algorithms are effective in computing the performance functions and that these performance functions provide useful approximations for the corresponding stochastic models. DA - 2014/// PY - 2014/// DO - 10.1287/ijoc.1120.0547 VL - 26 IS - 1 SP - 59-73 SN - 1526-5528 KW - queues with time-varying arrival rates KW - nonstationary queues KW - queueing networks KW - many-server queues KW - deterministic fluid models KW - fluid approximation KW - nonstationary networks of fluid queues KW - customer abandonment KW - non-Markovian queues ER - TY - JOUR TI - Robust control of a MEMS probing device AU - Zhang, X. AU - Koo, B. AU - Salapaka, S.M. AU - Dong, Jingyan AU - Ferreira, P.M. T2 - Ieee-Asme Transactions on Mechatronics AB - In this paper, a systematic design based on the robust control theory is developed for a microelectromechanical systems nanopositioning/probing device. The device is fabricated on a silicon-on-insulator substrate, and provides decoupled XY motion by using a parallel kinematics mechanism design. Each axis of the device is actuated by linear comb-drives and the corresponding displacements are sensed by separate comb structures. To improve the sensing resolution, the sensing and driving combs are electrically isolated. The nonlinear dynamic model between the actuation voltage and the sensed displacement will increase the complexity of model identification and control design. We circumvent the nonlinear model by redefining the input and output (I/O) signals during the model definition and identification, which results in linear and time-invariant models. A dynamical model of the system is identified through experimental input-output frequency-domain identification. The implemented H control design achieves a significant improvement over the response speed, where the bandwidths from the closed-loop sensitivity and complementary sensitivity functions, respectively, are 68 and 74 Hz. When compared to open-loop characteristics, enhancement in reliability and repeatability (robustness to uncertainties) as well as noise attenuation (by over 12%) is demonstrated through this design. DA - 2014/// PY - 2014/// DO - 10.1109/TMECH.2012.2224122 VL - 19 IS - 1 SP - 100-108 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84895061380&partnerID=MN8TOARS KW - Electrostatic comb drive KW - H-infinity control KW - microelectromechanical systems (MEMSs) KW - nanopositioning KW - system identification ER - TY - JOUR TI - Optimizing the simultaneous management of blood pressure and cholesterol for type 2 diabetes patients AU - Mason, J. E. AU - Denton, B. T. AU - Shah, N. D. AU - Smith, S. A. T2 - EUROPEAN JOURNAL OF OPERATIONAL RESEARCH AB - We present a Markov decision process (MDP) model to determine the optimal timing of blood pressure and cholesterol medications. We study the use of our model for a high-risk population of patients with type 2 diabetes; however, the model and methods we present are applicable to the general population. We compare the optimal policies based on our MDP to published guidelines for initiation of blood pressure and cholesterol medications over the course of a patient’s lifetime. We also present a bicriteria analysis that illustrates the trade off between quality-adjusted life years and costs of treatment. DA - 2014/3/16/ PY - 2014/3/16/ DO - 10.1016/j.ejor.2013.09.018 VL - 233 IS - 3 SP - 727-738 SN - 1872-6860 KW - OR in medicine KW - Markov decision process KW - Type 2 diabetes KW - Blood pressure treatment KW - Cholesterol treatment ER - TY - JOUR TI - MANY-SERVER HEAVY-TRAFFIC LIMIT FOR QUEUES WITH TIME-VARYING PARAMETERS AU - Liu, Yunan AU - Whitt, Ward T2 - ANNALS OF APPLIED PROBABILITY AB - A many-server heavy-traffic FCLT is proved for the $G_{t}/M/s_{t}+\mathit{GI} $ queueing model, having time-varying arrival rate and staffing, a general arrival process satisfying a FCLT, exponential service times and customer abandonment according to a general probability distribution. The FCLT provides theoretical support for the approximating deterministic fluid model the authors analyzed in a previous paper and a refined Gaussian process approximation, using variance formulas given here. The model is assumed to alternate between underloaded and overloaded intervals, with critical loading only at the isolated switching points. The proof is based on a recursive analysis of the system over these successive intervals, drawing heavily on previous results for infinite-server models. The FCLT requires careful treatment of the initial conditions for each interval. DA - 2014/2// PY - 2014/2// DO - 10.1214/13-aap927 VL - 24 IS - 1 SP - 378-421 SN - 1050-5164 KW - Many-server queues KW - queues with time-varying arrivals KW - nonstationary queues KW - customer abandonment KW - nonexponential patience distribution KW - heavy traffic KW - functional central limit theorem KW - Gaussian approximation KW - deterministic fluid approximation ER - TY - JOUR TI - Life cycle implications of product modular architectures in closed-loop supply chains AU - Chung, Wu-Hsun AU - Kremer, Guel E. Okudan AU - Wysk, Richard A. T2 - INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY DA - 2014/2// PY - 2014/2// DO - 10.1007/s00170-013-5409-8 VL - 70 IS - 9-12 SP - 2013-2028 SN - 1433-3015 KW - Design for life cycle KW - Design for logistics KW - Modular design KW - Closed-loop supply chains ER - TY - JOUR TI - Interdigitated silver-polymer-based antibacterial surface system activated by oligodynamic iontophoresis - An empirical characterization study AU - Shirwaiker, Rohan A. AU - Wysk, Richard A. AU - Kariyawasam, Subhashinie AU - Voigt, Robert C. AU - Carrion, Hector AU - Nembhard, Harriet Black T2 - BIOMEDICAL MICRODEVICES DA - 2014/2// PY - 2014/2// DO - 10.1007/s10544-013-9800-x VL - 16 IS - 1 SP - 1-10 SN - 1572-8781 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-84894410919&partnerID=MN8TOARS KW - Silver KW - Ions KW - Low intensity direct electric current (LIDC) KW - Antibacterial surface ER - TY - JOUR TI - A Modular Design Approach to Improve Product Life Cycle Performance Based on the Optimization of a Closed-Loop Supply Chain AU - Chung, Wu-Hsun AU - Kremer, Guel E. Okudan AU - Wysk, Richard A. T2 - JOURNAL OF MECHANICAL DESIGN AB - As environmental concerns have grown in recent years, the interest in product design for the life cycle (DFLC) has exhibited a parallel surge. Modular design has the potential to bring life cycle considerations into the product architecture decision-making process, yet most current modular design methods lack the capability for assessing module life cycle consequences in a supply chain. This paper proposes a method for product designers, called the architecture and supply chain evaluation method (ASCEM), to find a product modular architecture with both low life cycle costs and low energy consumption at the early design stages. ASCEM expands the assessment scope from the product's architecture to its supply chain network. This work analyzes the life cycle costs (LCCs) and energy consumption (LCEC) of two products designated within the European Union's directive on waste of electric and electronic equipment (WEEE) within a closed-loop supply chain to identify the most beneficial modular structure. In addition, data on 27 theoretical cases representing various products are analyzed to show the broader applicability of the proposed methodology. Our analysis shows that ASCEM can efficiently identify a good-quality modular structure having low LCC and LCEC in a closed-loop supply chain for both the two tested products and the hypothetical cases. DA - 2014/2// PY - 2014/2// DO - 10.1115/1.4025022 VL - 136 IS - 2 SP - SN - 1050-0472 KW - design for life cycle KW - modular design KW - reverse logistics KW - closed-loop supply chains ER - TY - JOUR TI - Evaluation of an Augmented Virtual Reality and Haptic Control Interface for Psychomotor Training AU - Kaber, David AU - Tupler, Larry A. AU - Clamann, Michael AU - Gil, Guk-Ho AU - Zhu, Biwen AU - Swangnetr, Manida AU - Jeon, Wooram AU - Zhang, Yu AU - Qin, Xiaofeng AU - Ma, Wenqi AU - Lee, Yuan-Shin T2 - ASSISTIVE TECHNOLOGY AB - This study investigated the design of a virtual reality (VR) simulation integrating a haptic control interface for motor skill training. Twenty-four healthy participants were tested and trained in standardized psychomotor control tasks using native and VR forms with their nondominant hands in order to identify VR design features that might serve to accelerate motor learning. The study was also intended to make preliminary observations on the degree of specific motor skill development that can be achieved with a VR-based haptic simulation. Results revealed significant improvements in test performance following training for the VR with augmented haptic features with insignificant findings for the native task and VR with basic haptic features. Although performance during training was consistently better with the native task, a correspondence between the VR training and test task interfaces led to greater improvement in test performance as reported by a difference between baseline and post-test scores. These findings support use of VR-based haptic simulations of standardized psychomotor tests for motor skill training, including visual and haptic enhancements for effective pattern recognition and discrete movement of objects. The results may serve as an applicable guide for design of future haptic VR features. DA - 2014/// PY - 2014/// DO - 10.1080/10400435.2013.800923 VL - 26 IS - 1 SP - 51-60 SN - 1949-3614 KW - block design KW - haptic simulation KW - neuropsychological tests KW - Rey-Osterrieth complex figure KW - virtual reality ER - TY - JOUR TI - Effects of Luminosity Contrast and Stimulus Duration on User Performance and Preference in a P300-Based Brain-Computer Interface AU - Li, Yueqing AU - Bahn, Sangwoo AU - Nam, Chang S. AU - Lee, Jungnyun T2 - INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION AB - Brain–computer interfaces (BCI) have potential to provide a new channel of communication and control for people with severe motor disabilities. Although many empirical studies exist, few have specifically evaluated the impact of contributing factors on user performance and perception in BCI applications, especially for users with motor disabilities. This article reports the effects of luminosity contrast and stimulus duration on user performance and usage preference in a P300-based BCI application, P300 Speller. Ten participants with neuromuscular disabilities (amyotrophic lateral sclerosis and cerebral palsy) and 10 able-bodied participants were asked to spell six 10-character phrases in the P300 Speller. The overall accuracy was 76.5% for the able-bodied participants and 26.8% for participants with motor disabilities. The results showed that luminosity contrast and stimulus duration have significant effects on user performance. In addition, participants preferred high luminosity contrast with middle or short stimulus duration. However, these effects on user performance and preference varied for participants with and without motor disabilities. The results also indicated that although most participants with motor disabilities can establish BCI control, BCI illiteracy does exist. These results of the study should provide insights into the future research of the BCI systems, especially the real-world applicability of the BCI applications as a nonmuscular communication and control system for people with severe motor disabilities. DA - 2014/2/1/ PY - 2014/2/1/ DO - 10.1080/10447318.2013.839903 VL - 30 IS - 2 SP - 151-163 SN - 1532-7590 ER - TY - JOUR TI - Development of a patient-specific bone analog for the biomechanical evaluation of custom implants AU - Horn, Timothy J. AU - Harrysson, Ola L. A. AU - West, Harvey A., II AU - Little, Jeffrey P. AU - Marcellin-Little, Denis J. T2 - RAPID PROTOTYPING JOURNAL AB - Purpose – The aim of this study is to describe an improved experimental substrate for the mechanical testing of patient-specific implants fabricated using direct metal additive manufacturing processes. This method reduces variability and sample size requirements and addresses the importance of geometry at the bone/implant interface. Design/methodology/approach – Short-fiber glass/resin materials for cortical bone and polyurethane foam materials for cancellous bone were evaluated using standard tensile coupons. A method for fabricating bone analogs with patient-specific geometries using rapid tooling is presented. Bone analogs of a canine radius were fabricated and compared to cadaveric specimens in several biomechanical tests as validation. Findings – The analog materials exhibit a tensile modulus that falls within the range of expected values for cortical and cancellous bone. The tensile properties of the cortical bone analog vary with fiber loading. The canine radius models exhibited similar mechanical properties to the cadaveric specimens with a reduced variability. Research limitations/implications – Additional replications involving different bone geometries, types of bone and/or implants are required for a full validation. Further, the materials used here are only intended to mimic the mechanical properties of bone on a macro scale within a relatively narrow range. These analog models have not been shown to address the complex microscopic or viscoelastic behavior of bone in the present study. Originality/value – Scientific data on the formulation and fabrication of bone analogs are absent from the literature. The literature also lacks an experimental platform that matches patient-specific implant/bone geometries at the bone implant interface. DA - 2014/// PY - 2014/// DO - 10.1108/rpj-08-2012-0069 VL - 20 IS - 1 SP - 41-49 SN - 1758-7670 KW - Biomechanical testing KW - Rapid tooling KW - Bone analog KW - Custom implant KW - Mechanical properties of bone ER -