“…Some new applications have also been addressed in the recent literature. Dukkanci, Peker, and Kara (2019) introduce the green hub problem, Mirzapour-Kamanaj, Majidi, Zare, and Kazemzadeh (2020) address energy transmission hub networks, and bike-andride hub systems are addressed by Tavassoli and Tamannae (2020) . Hub systems for medical applications are important including in drone delivery networks ( Macias, Angeloudis, & Ochieng, 2020 ), to access medication treatment for opioid use disorders ( Miele et al, 2020;Reif, Brolin, Stewart, Fuchs, & Mazel, 2020 ), and in identifying structures in functional brain networks ( Esfahlani et al, 2020 ).…”