An analytical model for reverse automotive production planning and pricing

Automotive shredders need a reverse production planning strategy that includes determining at what price to purchase vehicle hulks from different sources. In this paper, we formulate the automotive reverse production planning and pricing problem in a nonlinear programming model, develop an approximate supply function for hulks when adjacent shredders price independently, and compare two hulk pricing strategies in three trends for ferrous metal and hulk prices: constant, increasing and decreasing. The case study results indicate that adjusting purchase price based on hulk composition in coordination with planning for purchasing, storing and processing can increase net revenue by 7–15%.Journal Articl

Viable plastics recycling from end-of-life electronics

Millions of end-of-life (EOL) electronic products represent more than one million tons of engineering thermoplastics. The economically and environmentally sound recovery of engineering thermoplastics from EOL electronics is a challenge to the sustainability of electronics manufacturing. In this paper, we review the technologies to separate and identify pure post-consumer plastics from EOL electronics, which are followed by the comparison of electronic plastics recycling processes and the network models for plastics recycling processes. We also review successful plastics recycling practices for electronics. In addition, further research directions for recycling plastics from EOL electronics are discussed.Journal Articl

Single versus hybrid time horizons for open access scheduling

Difficulty in scheduling short-notice appointments due to schedules booked with routine check-ups are prevalent in outpatient clinics, especially in primary care clinics, which lead to more patient no-shows, lower patient satisfaction, and higher healthcare costs. Open access scheduling was introduced to overcome these problems by reserving enough appointment slots for short-notice scheduling. The appointments scheduled in the slots reserved for short-notice are called open appointments. Typically, the current open access scheduling policy has a single time horizon for open appointments. In this paper, we propose a hybrid open access policy adopting two time horizons for open appointments, and we investigate when more than one time horizon for open appointments is justified. Our analytical results show that the optimized hybrid open access policy is never worse than the optimized current single time horizon open access policy in terms of the expectation and the variance of the number of patients consulted. In nearly 75% of the representative scenarios motivated by primary care clinics, the hybrid open access policy slightly improves the performance of open access scheduling. Moreover, for a clinic with strong positive correlation between demands for fixed and open appointments, the proposed hybrid open access policy can considerably reduce the variance of the number of patients consulted.Journal Articl

A mean–variance model to optimize the fixed versus open appointment percentages in open access scheduling systems

Although healthcare quality may improve with short-notice scheduling and subsequently higher patient show-up rates, the variability in patient flow may negatively impact the service design. This study demonstrates how to select the percentage for short-notice or open appointments in an open access scheduling system subject to two quality performance metrics. Specifically, we develop a mean–variance model and an efficient solution procedure to help clinic administrators determine the open appointment percentage subject to increasing the average number of patients seen while also reducing the variability. Our numerical results indicate that for cases with high patient demand and high patient no-show rates for fixed appointments, one or more Pareto optimal percentages of open appointments significantly decrease the variability in the number of patients seen with only a negligible decrease in the expected number of patients seen. While our method provides a useful tool for clinic administrators, it also presents a modeling foundation for open access scheduling with quality management objectives to smooth patient flow and improve capacity utilization.Journal Articl

Matching daily healthcare provider capacity to demand in advanced access scheduling systems

Advanced access scheduling, introduced in the early 1990s, is reported to significantly improve the performance of outpatient clinics. The successful implementation of advanced access scheduling requires the match of daily healthcare provider capacity with patient demand. In this paper, for the first time a closed-form approach is presented to determine the optimal percentage of open-access appointments to match daily provider capacity to demand. This paper introduces the conditions for the optimal percentage of open-access appointments and the procedure to find the optimal percentage. Furthermore, the sensitivity of the optimal percentage of open-access appointments to provider capacity, no-show rates, and demand distribution is investigated. Our results demonstrate that the optimal percentage of open-access appointments mainly depends on the ratio of the average demand for open-access appointments to provider capacity and the ratio of the show-up rates for prescheduled and open-access appointments.Journal Articl

Model-based analysis of capacity and service fees for electronics recyclers

By 2010, billions of discarded electronics will require recycling due to concerns over data destruction and electronics recycling legislation. Unlike manufacturing planning that seeks to meet finished goods demand, recycling planning must meet recycling service demand to accept end-of-life electronic products. Motivated by actual electronics recycling problems that were observed, a short-term bulk recycling planning model was developed to determine what products to accept, process, and reprocess. Using data collected from electronics recyclers, an experiment was run including eight scenarios on the analytical recycling planning model that vary the processing capacity, service fee, and storage capacity. Although the results demonstrate that recyclers may improve their material revenues with reprocessing and selection of key product groups, the material revenues do not cover the total costs. Products with higher service fee-toweight ratios and material output revenues are more attractive for recyclers to accept. Service fee revenues are necessary to cover overhead costs such as capital equipment purchases, administrative costs, and logistics costs. The modeling scenarios also indicate that recyclers could benefit from greater processing and staging space capacity to accept more products that generate service fee revenues and, upon processing, generate material revenues.Journal Articl