abstract nowadays, industries cannot play a crucial role in national and international competitions. the tourism industry is no exception. tourism industry development as the most important economic sector and income generation is one of the key challenges of economic development in the world. therefore, countries were successful that take advantage of the capabilities of tourism sector using ...

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...

nowadays, air pollution is a global problem that has had significant growth by technology development, population growth andindustrial development. industrial development brought natural resources deterioration, more manufacturing products, and more environmental pollutants. if pollutant won’t be controlled, human-being and wildlife will face the critical risks. significant release and critical...

in this research we have studied the effect of some transition-metals (cu, ag and au) substitutions on two-electron reduction potential of flavins by application of dft method. all geometries have been optimized at blyp level of theory and “6-31+g** + lanl2dz” mixed basis set. the frequency job at the same method and basis sets has been performed to obtain gibbs free energy of compounds. it h...

abstract global financial crisis has created too many problems in relations among governments. among these problems, the issue of global monetary management, more than every time in the past four decades, has been moved in the center of international economic attentions. a problem which is specially known with the monetary hostility between united states and public republic of china. where ar...

from 1950s onward, new theories and critical approaches burgeoned across humanities. these theories were context-oriented; as a result, the analysis of discursive practices gained significance. thus, social, political, historical and cultural discourses that have been hitherto marginalized and considered inferior to literary texts, were introduced as important texts to be analyzed by critics. o...

in this investigation the effect of external field on the electron density of nanostructures of cds, cdse, cdte, gaas and polymeric structure of three, four, five and six units of cds as a kind of nanosolar cells has been studied theoretically. as modeling this system in nanodimension, molecular structures has used. specific properties of molecular structures permit us to consider different sym...

abstract: mineral scaling in oil and gas production equipment is one of the most important problem that occurs while water injection and it has been recognized to be a major operational problem. the incompatibility between injected and formation waters may result in inorganic scale precipitation in the equipment and reservoir and then reduction of oil production rate and water injection rate. ...

in this thesis, structural, electronical, and optical properties of inverse pervskite(ca3pbo) in cubic phase have been investigated.the calculation have been done based on density functional theory and according to generalized gradiant approximate (gga) as correlating potential. in order to calculate the configurations, implementing in the wien2k code have been used from 2013 version. first of ...