Ryan D. Winz’s research while affiliated with North Carolina State University and other places

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Publications (4)


Modeling and transportation planning for US noncombatant evacuation operations in South Korea
  • Preprint

November 2021

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33 Reads

John A Kearby

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Ryan D Winz

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[...]

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Purpose: The purpose of this paper is to investigate US noncombatant evacuation operations (NEO) in South Korea and devise planning and management procedures that improve the efficiency of those missions. Design/methodology/approach: It formulates a time-staged network model of the South Korean noncombatant evacuation system as a mixed integer linear program to determine an optimal flow configuration that minimizes the time required to complete an evacuation. This solution considers the capacity and resource constraints of multiple transportation modes and effectively allocates the limited assets across a time-staged network to create a feasible evacuation plan. That solution is post-processed and a vehicle routing procedure then produces a high resolution schedule for each individual asset throughout the entire duration of the NEO. Findings: This work makes a clear improvement in the decision-making and resource allocation methodology currently used in a NEO on the Korea peninsula. It immediately provides previously unidentifiable information regarding the scope and requirements of a particular evacuation scenario and then produces an executable schedule for assets to facilitate mission accomplishment. Originality/value: The significance of this work is not relegated only to evacuation operations on the Korean peninsula; there are numerous other NEO and natural disaster related scenarios that can benefit from this approach.


Performance tradeoffs for spare parts supply chains with additive manufacturing capability servicing intermittent demand

November 2021

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32 Reads

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1 Citation

Purpose - Investigate the impact of additive manufacturing (AM) on the performance of a spare parts supply chain with a particular focus on underlying spare part demand patterns. Design/Methodology/Approach - This work evaluates various AM-enabled supply chain configurations through Monte Carlo simulation. Historical demand simulation and intermittent demand forecasting are used in conjunction with a mixed integer linear program to determine optimal network nodal inventory policies. By varying demand characteristics and AM capacity this work assesses how to best employ AM capability within the network. Findings - This research assesses the preferred AM-enabled supply chain configuration for varying levels of intermittent demand patterns and AM production capacity. The research shows that variation in demand patterns alone directly affects the preferred network configuration. The relationship between the demand volume and relative AM production capacity affects the regions of superior network configuration performance. Research limitations/implications - This research makes several simplifying assumptions regarding AM technical capabilities. AM production time is assumed to be deterministic and does not consider build failure probability, build chamber capacity, part size, part complexity, and post-processing requirements. Originality/value - This research is the first study to link realistic spare part demand characterization to AM supply chain design using quantitative modeling.


Figure 3. (Color online) Conceptual overview of the approach
Figure 4. Forecasting technique for demand class
Figure 10. (Color online) The best performing network configuration, in terms of lowest average backorders, across all CV 2 and ADI value combinations. (Parameters: reactive inventory policy, AM capacity: 4, Average demand: 3, Demand realizations: 500, Products: 1.)
Figure 11. (Color online) Comparison of the amount of product produced via AM (in terms of percent of total demand) between network configurations
Figure 12. (Color online) Performance comparison of network configurations with CV 2 5 2.65 for all ADI values
Performance tradeoffs for spare parts supply chains with additive manufacturing capability servicing intermittent demand
  • Article
  • Full-text available

September 2021

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138 Reads

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9 Citations

Journal of Defense Analytics and Logistics

Purpose The study aims to investigate the impact of additive manufacturing (AM) on the performance of a spare parts supply chain with a particular focus on underlying spare part demand patterns. Design/methodology/approach This work evaluates various AM-enabled supply chain configurations through Monte Carlo simulation. Historical demand simulation and intermittent demand forecasting are used in conjunction with a mixed integer linear program to determine optimal network nodal inventory policies. By varying demand characteristics and AM capacity this work assesses how to best employ AM capability within the network. Findings This research assesses the preferred AM-enabled supply chain configuration for varying levels of intermittent demand patterns and AM production capacity. The research shows that variation in demand patterns alone directly affects the preferred network configuration. The relationship between the demand volume and relative AM production capacity affects the regions of superior network configuration performance. Research limitations/implications This research makes several simplifying assumptions regarding AM technical capabilities. AM production time is assumed to be deterministic and does not consider build failure probability, build chamber capacity, part size, part complexity and post-processing requirements. Originality/value This research is the first study to link realistic spare part demand characterization to AM supply chain design using quantitative modeling.

Download

Modeling and transportation planning for US noncombatant evacuation operations in South Korea

February 2020

·

455 Reads

·

6 Citations

Journal of Defense Analytics and Logistics

Purpose The purpose of this paper is to investigate US noncombatant evacuation operations (NEO) in South Korea and devise planning and management procedures that improve the efficiency of those missions. Design/methodology/approach It formulates a time-staged network model of the South Korean noncombatant evacuation system as a mixed integer linear program to determine an optimal flow configuration that minimizes the time required to complete an evacuation. This solution considers the capacity and resource constraints of multiple transportation modes and effectively allocates the limited assets across a time-staged network to create a feasible evacuation plan. That solution is post-processed and a vehicle routing procedure then produces a high resolution schedule for each individual asset throughout the entire duration of the NEO. Findings This work makes a clear improvement in the decision-making and resource allocation methodology currently used in a NEO on the Korea peninsula. It immediately provides previously unidentifiable information regarding the scope and requirements of a particular evacuation scenario and then produces an executable schedule for assets to facilitate mission accomplishment. Originality/value The significance of this work is not relegated only to evacuation operations on the Korean peninsula; there are numerous other NEO and natural disaster related scenarios that can benefit from this approach.

Citations (2)


... Faster processing times are expected to positively affect spare part supply, which can lead to better service levels and shorter lead times for customers [34]. Therefore, careful consideration of the technical capabilities and production constraints of on-demand manufacturing is required [35]. In addition, there is a lack of exploration of the hybrid warehouse option, in which physical and digital warehouses are considered. ...

Reference:

Green Spare Parts Evaluation for Hybrid Warehousing and On-Demand Manufacturing
Performance tradeoffs for spare parts supply chains with additive manufacturing capability servicing intermittent demand

Journal of Defense Analytics and Logistics

... Their objective also seeks to minimize helicopter fleet utilization as well as minimize the cost of helicopter routes. Unlike the DARP problem, many military applications prioritize other objectives over cost with approaches optimizing mission objectives, readiness, robustness, resilience and other factors (Kirby et al., 2020;Longhorn and Stobbs, 2021). ...

Modeling and transportation planning for US noncombatant evacuation operations in South Korea

Journal of Defense Analytics and Logistics