•Development of The Food bank Compliance problem extending a VRPTW.•New VRP model elements specific to food banks e.g., maximum wait time.•Creation of exact and heuristic methods to solve the new ...model.•Multi-criteria analysis to evaluate trade-offs between competing objectives for food banks.•Demonstrated significant improvements through collaborative, community-based OR.
According to the US Department of Agriculture, more than 49 million Americans do not have access to a sufficient quantity of affordable, nutritious food. To address the issue of food insecurity, non-profit food banks service a number of regional agencies that provide emergency food relief. To maintain regulatory compliance, each agency serviced by a food bank must receive an on-site audit once every 12–18 months. All audits are made by a member of the food bank’s staff. In collaboration with our community partner, we develop a multi-criteria capacitated vehicle routing with multiple time windows approach to improve the efficiency of the auditing schedule. Using real data from The Foodbank Inc., in Dayton, OH, we evaluate our model using both exact and heuristic methods and analyze the trade-offs between three competing objectives which correspond to our system’s three key stakeholders. Our computational results demonstrate an ability to quickly find solutions which improve upon the current operations at The Foodbank Inc. thereby benefiting all stakeholders and ultimately the community.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
AbstractThis paper introduces the new concept of restoration interdependencies that exist among infrastructures during their restoration efforts after an extreme event. Restoration interdependencies ...occur whenever a restoration task in one infrastructure is impacted by a restoration task, or lack thereof, in another infrastructure. This work identifies examples of observed restoration interdependencies during the restoration efforts after Hurricane Sandy as reported by major newspapers in the affected areas. A classification scheme for the observed restoration interdependencies is provided that includes five distinct classes: traditional precedence, effectiveness precedence, options precedence, time-sensitive options, and competition for resources. This work provides an overview of these different classes by providing the frequency they were observed, the infrastructures involved with the restoration interdependency, and a discussion of their potential impact on interdependent infrastructure restoration. The analysis is important because it provides a new understanding of how the restoration efforts of infrastructures are linked across systems and motivates the need for potential information-sharing in interdependent infrastructure restoration.
We present the Multi-Orbit Routing and Scheduling of Refuellable Space Robots for On-Orbit Servicing optimization problem which determines how to best route and schedule a fleet of highly ...maneuverable and refuellable space robot servicers to complete a set of tasks orbiting in space. We formulate this problem as a mixed-integer linear program and seek to maximize the weighted number of completed tasks subject to constraints related to the movements of the space robots, refueling depots, and tasks. We present and demonstrate algorithms for constructing the network and model using case studies with data based on satellites operating in the Low Earth, Mid Earth, and Geosynchronous Earth Orbits. Our results indicate the benefit of considering multiple orbits and policies related to the number and starting locations of robot servicers and refueling depots.
•A new MILP for multi-orbit on-orbit servicing with moving tasks and refueling depots.•Flexible algorithms to create model parameters: tasks, fuel depots, and the network.•A novel way to represent the movement of tasks and refueling depots.•Three case studies based on current space-based operational satellites.•Insights about robot servicers, task completion, and refueling depot usage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Many scheduling dispatching rules are intuitive processes used in every day life. For example, when faced with a variety of tasks due at different times one often implements the earliest due date ...scheduling rule: The next task worked on is the one with the earliest due date. Other common scheduling dispatching rules are easily understood, thereby enabling one to devise the rule when given the opportunity to experiment via trial and error. In this paper, we present an interactive Excel-based Gantt Chart Schedule builder that enables students to experiment with building schedules for different single and parallel machine problem examples. Instead of explicitly telling students these common scheduling rules, the schedule builder enables students to gain intuition about the rules on their own. Herein we describe the interactive schedule builder we created, explain how instructors and students can use this tool, perform a small preliminary assessment on the student perception metric, and provide supplemental teaching materials enabling use of the schedule builder in a variety of classroom environments.
In this paper, we discuss the impact of video tutorials on an undergraduate operations research (OR) course and analyze important aspects of student perception of their impact on the learning ...experience. Supplementary video tutorials offer additional examples of OR concepts; thus, class time can be more focused on letting students gain intuition about these concepts. We analyze students’ survey responses to help determine the perceived impact of the video tutorials on office hours and whether students’ familiarity with the creator of the tutorials impacted the tutorials’ effectiveness. Our results demonstrate that students saw significant advantages in using these supplementary video tutorials and that the creator of the tutorials did not impact the tutorials’ effectiveness as long as they were properly integrated into the course. Therefore, our results show that the overhead required to offer online video tutorials may be low (i.e., similar to selecting a course textbook) since their success relies more on proper integration into the course than having the professor of the course produce them. In addition, a preliminary assessment demonstrates that our blended learning environment has a positive impact on the learning experience.
Additive manufacturing (AM) has revolutionized the way industries manufacture and prototype products. A significant drawback that prevents 3D printing from being widely implemented in large-scale ...production is cycle time. This issue has been improved by allowing multiple collaborating printheads to print different parts of the same object simultaneously. However, little formal research has been done to support the aforementioned approach, and current implementations have room for improvement in terms of both makespan and mechanical properties. A new toolpath optimization methodology is proposed in this research to fill this need. The objectives are to create a collision-free infill toolpath for each printhead while maintaining the mechanical performance and geometric accuracy of the printed object. The methodology utilizes the combination of tabu search and novel collision detection and resolution algorithms, TS-CCR. The performance of the TS-CCR is analyzed and compared with the current industry standard.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper, we present, test, and compare two novel methods to solve the aircraft routing problem with aerial refueling with a multicriteria objective function. We present a mixed-integer linear ...program (MILP) that utilizes a combination of a network transformation and a formulation that creatively decouples refueling decisions from the nodes within the network. We also present a dynamic program (DP) that, when coupled with an alternative network transformation to account for the multiple criteria within the objective function, applies a node-labeling approach based on a modification of Dijkstra’s algorithm. We test and compare these alternative solution methods on a set of 264 synthetically-generated instances representing 66 combinations of network size and the frequency of aerial refueling point availability. Invoking CPLEX using the C++ callable library to solve the MILP and applying the DP in C++, we found that the application of the DP yields a 98.97 % reduction in the required computational effort, on average, relative to the MILP; the MILP fails to find an optimal solution within a 3,600-s time limit for selected instances of networks having at least 80 nodes and for all instances of networks having at least 350 nodes. In contrast, the DP is more robust than the MILP, as it only requires longer than 3,600 s to solve selected instances of networks having more than 3,000 nodes.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This paper presents a method for validating and transforming data for use in interdependent infrastructure network analysis. Critical infrastructure are interdependent on each other for delivery of ...services and execution of restoration activities. These interdependencies make infrastructure systems vulnerable to extreme events and highlights the needs for preparedness and response plans. Optimization models have been used to create effective plans using interdependent infrastructure networks. These models require accurate input data. However, many data sources have inconsistencies or errors which inhibit the ability to use such optimization models. This work identifies common errors in input network data and provides a method for processing and correcting these errors. We demonstrate the effectiveness of this method on data representing the transportation network in Juan Diaz town, in Panama. Keywords: Data processing, network, infrastructure, interdependence.
We consider the new class of integrated network design and scheduling (INDS) problems. These problems focus on selecting and scheduling operations that will change the characteristics of a network, ...while being specifically concerned with the performance of the network over time. Motivating applications of INDS problems include infrastructure restoration after an extreme event and building humanitarian distribution supply chains. While similar models have been proposed, no one has performed an extensive review of INDS problems from their complexity, network and scheduling characteristics, information, and solution methods. We examine INDS problems under a parallel identical machine scheduling environment where the performance of the network is evaluated by solving classic network optimization problems. We prove that all considered INDS problems are NP-Hard. We propose a novel heuristic dispatching rule algorithm that selects and schedules sets of arcs based on their interactions in the network. These interactions are measured by examining network optimality conditions. We present computational analysis based on case studies on realistic data sets representing the power, waste water, and emergency supply chain infrastructures of coastal New Hanover County, North Carolina, the power and telecommunications networks of lower Manhattan, New York, and the power network of a realistic artificial community CLARC County. These tests demonstrate the importance of a dispatching rule to arrive at near-optimal solutions during real-time decision making activities. We extend INDS problems to incorporate release dates which represent the earliest an operation can be performed on a network component. INDS problems with flexible release dates are then examined through the introduction of specialized machine(s) that can perform work to move the release date of a component earlier in time. An online optimization setting is explored with INDS problems, where the release date of a component is not known. We validate INDS problems as an appropriate model for many real life situations, including restoration of infrastructures after a large-scale disruptive event. We justify the use of a novel dispatching rule framework that can be easily customized to many types of complex INDS problems by demonstrating that it achieves near- optimal solutions rapidly.
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