Much of the literature on message logging and checkpointing in the past decade has been based on a so-called optimistic approach 1] that places more emphasis on failure-free overhead than recovery ee-ciency. Our experience has shown that most telecommunications systems use a pessimistic approach because the main purpose of using message logging and checkpointing is to achieve fast and localized...

Uncertain data is an increasingly prevalent topic in database research, given the advance of instruments which inherently generate uncertainty in their data. In particular, the problem of indexing uncertain data for range queries has received considerable attention. To efficiently process range queries, existing approaches mainly focus on reducing the number of disk I/Os. However, due to the in...

in this research, interval efficiency of butchery units of zabol city using model of interval data envelopment analysis was measured, and factors of effective on it was studied. data for this research obtained via completing questionnaires and use of method of sampling randomized for 2010 years. the results showed that efficiency maximum of 50% of butcheries is less than 40% and efficiency mini...

In this paper, it is assumed that the “Decision Making Units“( ) are consist of positive and negative input and output. Firstly, the optimistic and pessimistic models have been suggested by using negative data and then units with most productive scale size are measured in optimistic and pessimistic models. These productive values are compared with double frontiers and Hurwicz’s Criterion to obt...