introduction: the frequency of floods is one of the characteristics of river flow statistics so thatanalyzing it has an important role to assess the hydrological and economical water resources projects. for determining flood frequency, the estimation of accurate skewness coefficient of annual peak discharges is required. estimation of population skew for different regions will be improved when ...

in the islamic era, mausoleums were considered as the most important after mosques. constructing these buildings dates from the fourth century after hijrah, coinciding with the establishment of the earlier post -islamic dynasties in east and north east of iran. this tradition continued in later islamic periods in two basic rectangular and tomb tower types. the significant point about these buil...

the europeans consider roger bacon as the inventor of spectacles, and the 13th century, as the beginning of using lenses as spectacles. it can truly be said that the lenses had not been born all of a sudden then. it may be concluded that the lenses had been available long before that time.   we are all familiar with quartz, a transparent volcanic stone that begins its journey in the rivers afte...

introduction the study area is a small part of the urumieh-dokhtar structural zone in the markazi province, located in the northeastern part of the farmahin, north of arak (hajian, 1970). the volcanic rocks studied from the area include andesite, dacite, rhyodacite, ignimbrite and tuff of middle to late eocene age (middle lutetian to upper lutetian) (ameri et al., 2009). it seems that folding a...