in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...

due to the limiting workspace of parallel manipulator and regarding to finding the trajectory planning of singularity free at workspace is difficult, so finding a best solution that can develop a technique to determine the singularity-free zones in the workspace of parallel manipulators is highly important. in this thesis a simple and new technique are presented to determine the maximal singula...

during natural gas processing, water in natural gas may cause to hydrates formation in pipelines which may lead to serious damages to process equipments. given the problems raised by present of water in natural gas, glycol solvent uses to remove water.in contact of glycol with gas always an amount of btex and voc absorb along with water, which on glycol recovery process, these substances separa...

the purpose of this study was to examine the english language needs of medical students at tehran university of medical sciences . analysis of the needs took place for three groups: 320 undergraduate students, 30 postgraduate students and 20 university instructors. a triangulation approach to collect data was used in which a combination of the quantitative (using the questionnaires) and qualita...

the aim of this thesis is an approach for assessing insurer’s solvency for iranian insurance companies. we use of economic data with both time series and cross-sectional variation, thus by using the panel data model will survey the insurer solvency.

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...

this thesis is presented 10 ghz voltage controlled ring oscillator for high speed application. the voltage controlled ring oscillator was designed and fabricated in 0.13یm cmos technology. the oscillator is 7-stages ring oscillator with one inverter replaced by nand-gate for shutting down in the ring oscillator during idle mode. tri-state inverter was used to control of 126 bit vector in ri...

some new water-soluble schiff base complexes of na2[m(5-so3-1,2-salophen)].nh2o; (5-so3-1,2-salophen = n,n’-bis(5-sulphosalicyliden)-1,2-phenylendiamine); na2[m(5-so3-2,3-salpyr)(h2o)n].2h2o; (5-so3-2,3-salpyr = n,n’-bis(5-sulphosalicyliden)-2,3-diaminopyridine); and na2[m(5-so3-3,4-salbenz)(h2o)n].nh2o; (5-so3-3,4-salbenz = n,n’-bis(5-sulphosalicyliden)-3,4-diaminobenzophenon); where m = cu, n...

in this thesis, ‎‎using‎‎ ‎concept‎s‎ ‎of‎ ‎wavelet‎s‎ ‎theory ‎‎‎som‎e‎ ‎methods‎‎ ‎of‎ ‎th‎e ‎solving‎‎ ‎optimal‎‎ ‎‎con‎tr‎ol‎ problems ‎(ocps)‎‎. ‎g‎overned by time-delay systems is investigated. ‎th‎is‎ thesis contains ‎tw‎o parts. ‎‎first, the method of obtaining ‎o‎f ‎the‎ ‎‎ocps‎ in time delay systems by linear legendre multiwavelets is ‎ ‎presented‎.‎‎‎‎ the main advantage of the meth...

abstract although music possesses some kind of power and using it has been welcome by many students in language classrooms, it seems that they take a non-serious image of the lesson while listening to songs and they may think that it is a matter of fun. the main objective of the present study was to investigate whether learning a foreign language through musical texts (songs) can have an impac...