Optimal maintenance strategies for systems with partial repair options and without assuming bounded costs

We study a repairable system with Markovian deterioration and partial repair options, carried out at fixed times $n=1,2,\ldots$ and look for optimal strategies under certain conditions. Two optimality criteria are considered: expected discounted cost and long-run average cost. Douer and Yechiali found conditions under which a policy in the class of generalized control limit policies is optimal. In this paper conditions are found under which an optimal policy is a control-limit policy. We explicitly explain how to derive this optimal policy; numerical examples are given, too

A discounted model for a repairable system with continuous state space

We examine repairable systems with a continous state space and partial repair options, carried out at fixed times $n=1,2,...$. Every time interval $[n,n+1)$ there is a manufacturing cost and a repair cost. These cost functions are not restricted to the class of bounded functions in this study. Conditions are found under which a control-limit replacement policy minimizes the discounted cost. Hence these conditions guarantee that there is an optimal policy under the discounted cost criterion which does not use partial repairs. We explicitly explain how to derive this optimal policy

Mental health issues and adults with learning disabilities

Full text of this book chapter is not available in the UHRA.Introduction – What is a mental health condition? How does this differ from a learning disability? Prevalence and aetiology of mental illness in people with learning disabilities – Why is their high numbers of people with learning disabilities and associated mental health problems? Assessment and Diagnosis – How are people with learning disabilities assessed for mental illness? Problems of assessing people with LD. Service Provision – A look at how people with learning disabilities and mental health needs have in the past and are presently being cared for. Therapeutic Interventions – Medication and non-physical interventions aimed at addressing the needs

Sedimentology of the Triassic–Jurassic boundary beds in Pinhay Bay (Devon, SW England)

Sedimentology of the Triassic–Jurassic boundary beds in Pinhay Bay(Devon, SW England). Proceedings of the Geologists’ Association, 112. 349–360. New exposures in Pinhay Bay (SE Devon) of the White Lias (Langport Member of the Lilstock Formation)and basal Blue Lias reveal rapidly changing palaeoenvironments during the Triassic–Jurassic(T–J) boundary interval. During deposition of the topmost White Lias a soft seafloor of micritic mudstone was lithified and bored. The resultant hardground was locally eroded, probably in a shallow marine setting, to form a spectacular intraformational conglomerate that was itself lithified. Brief subaerial emergence then followed and produced a fissured and pitted top surface to the White Lias. The regression was short lived and rapid transgression at the base of the Blue Lias established organic-rich shale deposition with a small framboidal pyrite population and low Th/U ratios indicative of a stable, sulphidic lower water column (euxinic conditions). The White Lias/Blue Lias contact thus records a short duration, high amplitude relative sea-level change. This sea-level oscillation has also been postulated for other T–J boundary sections in Europe, although the failure to identify it in regional-scale sequence stratigraphic studies is probably due to its brief duration. Deposition of the basal beds of the Blue Lias was marked by a discrete phase of syn-sedimentary folding and small growth fault activity that may record a regional pulse of extensional tectonic activity

Getting Infrastructure Priorities Right in Post-Conflict Reconstruction

infrastructure, conflict, reconstruction, water

Millennium Development Goal 7: An Assessment of Progress With Respect to Water and Sanitation: Legacy, Synergy, Complacency or Policy?

MDGs, water, sanitation, access

European Union environmental regulations and their potential impact on market access for Africa's exports

international trade;impact assessment;European Union;Africa;access to markets;environmental protection;exports;international agreements;environmental standards

Consumer Preferences for Water Supply? An Application of Choice Models to Urban India

Water supply, Consumer preferences, Discrete choice, Lexicographic preferences