A simple model is developed that captures the main features of life reproduction, growth and maintenance. These features are determined by a single state variable, vitality. The resulting optimal life-history strategies are classified with respect to the course of their characteristic age-trajectory of mortality. It is shown that the range of optimal life histories is wide. The main factors tha...

Through their high degree of specialization, domain specific languages (DSLs) promise higher productivity and thus shorter development time and lower costs than general purpose programming languages. Since many domains are subject to continuous evolution, the associated DSLs inevitably have to evolve too, to retain their value. However, the continuous evolution of a DSL itself can be very expen...

The technical equipment developed and used in both installation and operation processes in refineries, oil and gas pipelines, and gas booster stations has always been expensive. Hence, managers at different organizational levels are keen to find methods to control and reduce these costs. Generally speaking, the operators in a gas booster station choose the operating devices without considering ...

A partial maintenance productivity goal is that the "rm should seek to maximize its maintenance productivity in economic terms, and should aim at producing any level of output which is decided upon at minimum maintenance cost with respect to the production system's state. The state of objects or production systems is such a property, i.e., a multidimensional property. In this paper we amalgamat...

in this paper, we focus on a continuously deteriorating critical equipment which its failure cannot be measured by cost criterion. for these types of systems like military systems, nuclear systems, etc it is extremely important to avoid failure during the actual operation of the system. in this paper we propose an approach which constrains failure probability to a pre-specified value. this valu...

We tested whether growth and maintenance costs of plant organs vary with environmental stress. Quercus ilex L. seedlings from acorns collected from natural populations in the northern Iberian Peninsula and in a lower elevation and putatively less stressful habitat in the southern Iberian Peninsula were grown in pots under the same conditions. Growth and maintenance respiration were measured by ...

'Ihe computing world is undergoing a transformation from centralized to distributed computer systems. At the same time, software maintenance has been identified repeatedly as the largest single system life cycle cost. This paper focuses on the issue of whether and to what extent distributed computer operating environments directly afrect software maintenance difficulty (and, by association, sof...

OBJECTIVES This study determined the cost-effectiveness of expanding methadone maintenance treatment for heroin addiction, particularly its effect on the HIV epidemic. METHODS We developed a dynamic epidemic model to study the effects of increased methadone maintenance capacity on health care costs and survival, measured as quality-adjusted life-years (QALYs). We considered communities with H...