Nonlinear cash flow optimization model

During construction, progress payments (cash inflow) are made periodically to contractors based on work performed. Contractors are required to pay the direct costs (cash outflow) during construction. The net difference between the cash inflow and outflow is the overdraft, which contractors must finance either from the bank or from their own resources. To increase profit margin, contractors consider methods to improve their cash flow, which will increase profit. These methods include front end loading (Stark 1974) and shifting of activities (Easa 1992). These two linear procedures could be done sequentially. However, this sequential linear formulation may not produce an optimized solution because of the nonlinear characteristics of the model. This note examines the combination of the two linear procedures into a single nonlinear formulation such that better profit margin can be achieved. © 2006 NRC Canada