In this paper we discuss a general framework for single component replacement models. This framework is based on the regenerative structure of these models and by using results from renewal theory a unified presentation of the discounted and average finite and infinite horizon cost models is given. Finally, some well-known replacement models are discussed, and making use of the previous results...

How adaptation appears and is later refined by natural selection has been the object of intense theoretical work. However, the testing of these theories is limited by our ability to estimate the strength of natural selection in nature. Using a long-term cline series, we estimate the selection coefficients acting on different alleles at the same locus to analyze the allele replacement observed i...

OBJECTIVES To determine the period prevalence, demographic characteristics, cost of treatment, and outcomes of patients admitted to the intensive care unit for continuous renal replacement therapy. DESIGN Descriptive case series. SETTING Intensive Care Unit in a Hong Kong tertiary referral, teaching hospital. PATIENTS All patients admitted to the Intensive Care Unit from January to Decemb...

OBJECTIVE Little is known about the nutritional adequacy and feasibility of breastmilk replacement options recommended by WHO/UNAIDS/UNICEF. The study aim was to explore suitability of the 2001 feeding recommendations for infants of HIV-infected mothers for a rural region in KwaZulu Natal, South Africa specifically with respect to adequacy of micronutrients and essential fatty acids, cost, and ...

In many situations, it may be more economical to use a used unit than to do a new one. This paper considers an age replacement policy and a periodic replacement policy with minimal repair at failure for a used unit of age x. We discuss optimum replacement policies which minimize the expected cost rates for a specified age x. Further, we obtain an upper bound of an optimum time for an age replac...

We apply fluid-replacement logging in arsenic-contaminated regions of Bangladesh using a low-cost, down-well fluid conductivity logging tool to detect leaks in the cased section of wells. The fluid-conductivity tool is designed for the developing world: it is lightweight and easily transportable, operable by one person, and can be built for minimal cost. The fluid-replacement test identifies le...

The main reason for calving replacement heifers early is economics. Economic assessments (2) have demonstrated that heifer rearing cost increases $50.00 to $60.00 each month calving is delayed. In addition, older calving ages result in the need for more heifers for herd replacement. These classic concepts are presented in Table 1. Conceptually, as calving age is reduced there is a linear reduct...

This paper proposes random age, periodic and block replacement policies which are made at random variable times, and optimal policies that minimize their expected cost rates are discussed analytically and computed numerically. We compare such random replacements with their standard policies that are made at constant times. Comparison results show that when costs for random and constant replacem...

This paper explores a family of augmented FIFO replacement policies for highly setassociative caches that are common in low-power embedded processors. In such processors, the implementation cost and complexity of the replacement policy is as important as the cache hit rate. By exploiting the cache hit way information between two replacements, the proposed replacement schemes reduce cache misses...