This paper addresses the staged capacity expansion of multiproduct batch plants operating in single product campaign (SPC) mode and in the presence of product demand uncertainty. This extends previous work by the authors on the design problem. Staged capacity expansions are modeled as additions of extra units of equal size at each stage at the end of each time period. The normality assumption i...

Projects may be evaluated and compared according to the Net Present Value (NPV) of their cash flow. The NPV is the discounted expected revenues minus the costs over the lifetime of the project. Traditional NPV calculations do not take into account the uncertainty in the variables that influence the revenues and costs. We present a simulation approach to incorporate uncertainty in the NPV calcul...

Existing methods of pushback (phase) design are reviewed in the context of “gap” problems, a term used to describe inconsistent sizes between successive pushbacks. Such gap problems lead to suboptimal open pit mining designs in terms of maximizing net present value. Methods such as the Lerchs– Grossman algorithm, network flow techniques, the fundamental tree algorithm, and Seymour’s parameteriz...

One of the most difficult problems in mining operation is how to determine optimum cut-off grades of ores at different periods over the lifespan of the mine that will maximize the net present value (NPV) of the mine. Maximizing the NPV of a mining operation, subject to different constraints is a nonlinear programming problem. Cut-off grade optimization is used to arrive at an operating strategy...

The optimal development planning of offshore oil and gas fields has received significant attention in recent years. In this paper, we present an efficient investment and operational planning model for this problem which is fairly generic, and is extended to include fiscal considerations. With the objective of maximizing total NPV for long-term planning horizon, the proposed non-convex multiperi...

Geological uncertainty is of significant concern in petroleum reservoir modeling with the goal of maximizing oil production. Stochastic simulation allows generating multiple reservoir models that can be used to characterize this uncertainty. However, the large computation time needed for flow simulation (e.g., for use in production forecasting) impedes the evaluation of flow on all reservoir mo...

AIMS To determine whether the use of negative pressure ventilation (NPV) was associated with a lower rate of endotracheal intubation in infants with recurrent apnoea secondary to acute bronchiolitis. METHODS Retrospective review of two paediatric intensive care units (PICU) databases and case notes; one PICU offered NPV. RESULTS Fifty two infants with bronchiolitis related apnoea were admit...

Photosynthetic vegetation (PV) and non-photosynthetic vegetation (NPV) are important ground cover types for desertification monitoring and land management. Hyperspectral remote sensing has been proven effective for separating NPV from bare soil, but few studies determined fractional cover of PV (f pv) and NPV (f npv) using multispectral information. The purpose of this study is to evaluate seve...