This paper presents an overview of causes of sewer deterioration together with a discussion of control methods that can prevent or arrest this deterioration. In particular, the paper covers inlineand combined sewer overflow(CSO) storage-tank-flushing systems for removal of sediments and minimizing hydrogen sulfide production resulting in the reduction of associated pollution and sewerline corro...

We consider a class of problems, which we call “SFQ” problems, in which both stocks and ows can be controlled to promote the quality of a valued resource, such as environmental quality or public infrastructure. Under the optimal policy, periodic restoration of the stock of quality complements positive but variable abatement of the ow of damages. When deterioration is more rapid or highly vari...

Marine fisheries and the ecosystems that sustain them are increasingly beset by environmental deterioration, and the problem is particularly acute in coastal zones where human populations are increasing. In the best of circumstances, fishery managers are faced with the multiple, often conflicting, demands of resource users, politicians, and scientists when considering strategies for resource ma...

A condition based preventive and corrective maintenance policy is proposed for a continuously operating system. The condition of the system is assumed to deteriorate with time. The model incorporates both deterioration as well as random common cause failures. The deterioration stages are modeled as discrete state processes. The system is put to random inspection to know the condition. The mean ...

The debates over the future of human population and the earth’s environment, and similar large issues, usually take place without reference to explicit models. Debate would be clarified if such models were employed. We propose that the logistic equation and its extensions like the generalized logistic and the Lotka-Volterra equations, so familiar to ecologists, can easily be modified to model t...