the main objective in sampling is to select a sample from a population in order to estimate some unknown population parameter, usually a total or a mean of some interesting variable. a simple way to take a sample of size n is to let all the possible samples have the same probability of being selected. this is called simple random sampling and then all units have the same probability of being ch...

deployable scissor type structures are composed of the so-called scissor-like elements (sles), which are connected to each other at an intermediate point through a pivotal connection and allow them to be folded into a compact bundle for storage or transport. several sles are connected to each other in order to form units with regular polygonal plan views. the sides and radii of the polygons are...

1.0 overview it seems that grammar plays a crucial role in the area of second and foreign language learning and widely has been acknowledged in grammar research. in other words, teaching grammar is an issue which has attracted much attention to itself, and a lot of teachers argue about the existence of grammar in language teaching and learning. this issue will remind us a famous sentence f...

to teach english adequately, qualified teachers are needed. unfortunately, there are still teachers who are teaching english without an academic degree in tefl. it is necessary for teachers to have a major in english to have subject knowledge, but it is not sufficient. teachers need to have an understanding of the social, cultural, moral, ethical, and pedagogical issues of education and practic...

abstract nowadaysphotovoltaic solar cells (pvs) areacknowledged the fastest growing energy technology in the word, however, they only account for only fraction of current global renewable energy capacity. it isrecognized that this incomplete market penetration has been largely a result of the technology’sexcessive cost. so researchers are trying to find innovative, economic way with theaim of ...

a one dimensional dynamic model for a riser reactor in a fluidized bed catalytic cracking unit (fccu) for gasoil feed has been developed in two distinct conditions, one for industrial fccu and another for fccu using various frequencies of microwave energy spaced at the height of the riser reactor (fccu-mw). in addition, in order to increase the accuracy of component and bulk diffusion, instanta...

from its emergence till present time marxist principles has undergone great changes since their promulgation by marx. many theorists and thinkers set at rectifying marxist tenets and introducing those of their own while others advocated its main concepts and attempted at improving them. among marxist philosophers who had an intensive study of marxs ideology, is louis althusser whose reflections...

?it is of utmost priority for an experienced teacher to train the mind of the students, and enable them to think critically and correctly. the most important question here is that how to develop such a crucial ability? this study examines a new way to the development of critical thinking utilizing critical discourse analytical tools. to attain this goal, two classes of senior english la...

according to webster and wind (1972) and anderson et al (1987), “organizational buying is a complex process and involves many people from different functional areas, multiple goals and potentially conflicting decision criteria. moreover, the customers of today are also more knowledgeable and selective when making their purchasing decisions. since a key to organizational survival is the retentio...

today the image of a permanent skeletal space of cities affected by some forces or mechanisms is put in time with social-economic development and while imposes a new face and perspective to physical anatomy of cities, and prepares field to changes in content and social- economic structures of cities too. simultaneously with quitting villages in order to settle in cities by villagers, the phen...