Orthogonal arrays are of great importance in mathematical sciences. This paper analyses a certain practical advantage of quasi-difference matrices over difference matrices to obtain orthogonal arrays with given parameters. We also study the existence of quasi-difference matrices over cyclic...

In distribution systems such as airlines and express package delivery, the use of hub-and-spoke networks is common, and flow consolidation at hub facilities is essential for cost reduction. While a constant discount factor is typically used to model cost reduction in interhub links, this paper...

Public health agencies and medical organizations have increased their relentless efforts to control the outbreaks of mosquitoes causing West Nile disease epidemics with the re-emergence of deadly disease in the United States. Such measures include a large-scale spray operation of insecticides...