We consider the maximal covering location-allocation problem with multiple servers. The objective is to maximize the population covered, subject to constraints on the number of service centers, total number of servers in all centers, and the average waiting time at each center. Each center operates as an M/M/k queuing system with variable number of servers. The total costs of establishing cen...

In this article, we consider the set covering problem with conflict constraints, i.e., from each conflicting pair of columns at most one column can appear in feasible solution. For problem, propose appropriate pre-processing techniques and several families Valid Inequalities (VIs) for corresponding integer programming model that result simultaneous presence constraints stable (conflict) constra...

 We introduce a dynamic and stochastic transportation problem consisting of two subproblems. For parcel transportation in hub-and-spoke networks, swap containers are used to carry out hub-to-hub shipments. This constitutes a pickup and delivery problem on the operational level. On the tactical level, empty swap containers are balanced over the hub-network in order to match the stochastic deman...

background: current who best infection control practices for injections do not address the use of hub cutters due to insufficient evidence on safety and efficacy. objective: to assess the impact of the use of hub cutters on 1) the frequency of needle-stick injuries (nsis) and other blood exposures among workers and 2) the volume of sharps waste in a mass vaccination campaign setting. methods: d...

The biggest challenges faced in big cities are greenhouse gas emission and growing energy needs. Efficient utilization of existing infrastructures has a prominent role in response to the challenges. Energy hub approach embraces performance of different energy networks. Energy hub is defined as a super node in electrical system receiving distinctive energy carriers such as gas and electricity in...