the hierarchical hub location problem is encountered three-level network that is applied in production-distribution system, education system, emergency medical services, telecommunication network, etc. this paper addresses the hierarchical hub covering problem with single assignment accounting for mandatory dispersion of central hubs restriction as a special case. this formulation with incorpor...

Energy-consuming countries are affected by obstructions in supplies or conflicts that may occur along the energy transit path. Hence, presence of a global logistics hub for acting as connecting bridge between energy-supplying and energy-consuming can overcome such troubles, support sustainable flow energy, achieve overall operational efficiency supply chain. However, establishing is complicated...