در این پایان نامه ابتدا شرط برد پایدار $ n $ را معرفی کرده، سپس حلقه های تبادلی را تعریف می کنیم و شرایط لازم و کافی برای این که حلقه تبادلی $ r $، در شرط برد پایدار $ n $ صدق کند را بیان می کنیم. نشان می دهیم که حلقه تبادلی $ r $، در شرط برد پایدار $ n $ صدق می کند اگر و تنها اگر برای هرعنصر منظم $ ain r ^{n} $، عنصر تک پیمانه ای مانند $ u in r ^{n} $ وجود داشته باشد به طوری که $ au in r $ یک ...

abstract: one of the most visited & important spaces in different countries by tourist are urban areas. the old tehran which major part is located in district 12 is historical showcase of the capital, but, its hiidden cultural attraction is not used as it should be. this thesis occasionally engage in studying the efficacy of correct installation of travel guide boards in welfare & easily acc...

in order to examine the ecological conditions and characteristics of fraxinus excelsior l. in the northern forests of iran 6 main areas as well as some miscellaneous ones , have been selected in the region respectively in : lomir2, shafaroud , park - e-noor , ahlam , alandan and noor.

data envelopment analysis (dea) is a powerful tool for measuring relative efficiency of organizational units referred to as decision making units (dmus). in most cases dmus have network structures with internal linking activities. traditional dea models, however, consider dmus as black boxes with no regard to their linking activities and therefore do not provide decision makers with the reasons...

ii abstract the legend of human being’s refulgence was distorted completely in the age of modernity. this new age, had some drastic negative effects, besides its positive qualities. one significant negative effect of it was the emergence of neurosis in human beings. aldous huxley’s brave new world was one of the novels of the 02 th century that contained the prophecy of criticizing ...

this thesis attempts to study the representations of the third-world intellectuals in three fictional works by the british-educated trinidadian nobel-winner v. s. naipaul: the mimic men, a bend in the river, and magic seeds. the first one recounts the story of ralph singh’s sense of alienation, his experiences as a colonial politician, and his struggle to give order to his disorderly world thro...

the application of e-learning systems - as one of the solutions to the issue of anywhere and anytime learning – is increasingly spreading in the area of education. content management - one of the most important parts of any e-learning system- is in the concern of tutors and teachers through which they can obtain means and paths to achieve the goals of the course and learning objectives. e-learn...

a major concern in the last few years has been the fact that the cultural centers are keeping distance with what they have been established for and instead of reproducing the hegemony, they have turned into a place for resistance and reproduction of resistance against hegemony. because the cultural centers, as urban public spaces in the last two decades, have been the subject of ideological dis...

efl/esl textbooks have been regarded as essential language teaching materials with which the learners spend about 70 up to 90 percent of their class time. the important role they play and their vast use make them not only influential in learning the language but also in shaping values and attitudes. put it another way, textbooks socialize learners using their contents (i.e. texts, illustrations...