any change in the refractive index of a laser active medium can lead to serious degradation of beam quality, laser beam modes, laser performance and variation in the intensity distribution. alteration in the refractive index of laser active medium is especially notable in high power lasers. it is clear that in the laser beam production, the pumping agent induces a great amount of heat which...

the concepts of similarity and dissimilarity have been the interest of many researchers. basically, in the studies the similarity between two objects or phenomena, has been discussed. in this thesis, we consider the case when the resemblance or similarity among three objects or phenomena of a set, 3-similarity in our terminology, is desired. later we will extend our definitions and propos...

Tabatabai’s theory about the meaning of life can be referred to as active objectivism, where a man plays an important role in achieving the meaningful life, rather than merely discovering the divine view about his existence. If the man chooses the divine purpose from a “real life” perspective as his meaning of life, God’s purpose and man’s purpose will converge in order to shape a meaningful li...

abstract in aggregate, active forms of reactive silica with mineral names are sometimes associated with sand and gravel in concrete mixture. alkali hydroxides originated from alkalis in the cement or other resources form an alkaline silica gel with this reactive silica which becomes swallowed and expanded during time causing damage to concrete. there have been growing researches on alkaline r...

     Reason is one of the sources of knowledge in human existence and human forces that distinguishes between good and evil or right and wrong. This has led many scientists and mystics to reflect on this issue among whom are Ibn Sina and Rumi. The purpose of this study is to study the nature of reason, its relationship with love and religion, factors and obstacles to reaching the perfection of ...