In project-oriented production systems where hundreds of thousands of operations are carried out each month subject to precedence and resource constraints, long-term scheduling is a challenging problem for any branch of operation research or artificial intelligence. In a dynamically changing environment, fixing a schedule for several months in advance would be pointless, and, furthermore, the s...

We address a novel integrated maintenance and production scheduling problem in a multi-machine and multi-period production system, considering maintenance as a long-term decision. Deterioration of machines over time decreases production capacity. Since maintenance activities improve machine conditions, increasing production capacity, but also take time that cannot be used for production, the ch...

This paper presents an interior point method for the long-term generation scheduling of large-scale hydrothermal systems. The problem is formulated as a nonlinear programming one due to the nonlinear representation of hydropower production and thermal fuel cost functions. Sparsity exploitation techniques and an heuristic procedure for computing the interior point method search directions have b...

background: this study aims to investigate the patterns of bioaccumulation and depuration of copper in the selected kidney and liver of capoeta fusca. methods: the fish were collected between september and november 2010 from a qanat in birjand. they were exposed to two types treatments with copper (0.25 and 0.75 mg/l) for a period of 41 days. the fish under study were exposed to the above-menti...

objective: successful bonding of a dental implant to bone, which was referred to as osseointegration by branemark has been well documented. however, long-term prognosis of an implant depends on adequate maintenance and long-term care. an effective maintenance program is required to preserve the health of peri-implant tissues. several techniques have been suggested for this purpose but it is not...