the main task of drilling the formation by the bit is done via scraping, crushing and grinding. discharging the fluid from the bit nozzles is done with high pressure which assists to break the rocks. different parameters affect the bit selection and design for each drilling formation, but the most important one is drillability that depends on hardness of the formation. in this paper, the design...

the qom formation, a series of shales, sandstones and carbonate deposits, is the last transgression of the sea in central iran sedimentary basin. foraminifera are one of the most important and numerous fossil groups present in the qom formation. in this study, the micropaleontology of the qom formation in three measured stratigraphic sections in south and west of tafresh (rakin, band-e-ali nagh...

The work is concerned with investigation of spatio-temporal phenomena on mutually coupled CNN array. Besides pattern formation and active wave propagation, we found that other interesting spatio-temporal phenomena such as phaseinversion-wave and classical waves can be also observed in the same network structure. In particular, we focus our discussion on the relations of spatio-temporal phenomen...

This study investigates economic and strategic inducements of R&D cooperation. We focus on industry and company factors that affect a firm’s rate of participation in R&D consortia. These factors are analyzed in a dynamic context using a sample of 312 Japanese firms in 74 industries between 1969 and 1992. We find a firm in an industry with weak competition and appropriability conditions has a hi...