abstract the present study deals with a comparison between reactive and pre-emptive focus-on-form in terms of application and efficiency. it was conducted in an intermediate english class in shahroud. 15 male learners participated in this research and their age ranged from 18 to 25. a course book, new interchange 3, and a complementary book were used. every session the learners gave lectures o...

Introduction: In the present experimental investigation, the thermal and electrical performances of a photovoltaic/thermal system equipped with a sheet-and-grooved serpentine tube collector are investigated. The water-magnetite nanofluid is used as the heat transfer fluid. The effect of nanoparticle volume concentration (0-1%), nanofluid mass flow rate (10-40 kg/h) and groove pitch (0, 0.54 an...

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...

Utilization of combined heat and power (CHP) systems that simultaneously fulfill the electrical and heating energy needs is considered as an effective strategy for management of energy demand and consumption. Overall operational efficiency in excess of 70% is made possible, when these systems are utilized, and it is expected that needs for both the demand and supply sides are met even under ...

The aging of insulating materials can be estimated by an electrical breakdown occurring in electrical components so that the relationship between lifetime, failure probability and reliability of electrical components may be studied using the life models in high voltage cables networks. In last decades with attention to higher features as electrical, thermal, mechanical characteristic, widely cr...

The solar radiation energy is one of the clean, essential and renewable resources for future. Iran, having 300 annual sunny days, has such intrinsic potential and thermosyphon solar-electrical water heaters (TSEWH) are the simplest solar-thermal convertors. Despite their unique merits, they can not supply hot water for domestic applications during cold period, so, an auxiliary backup system suc...

on- the-job training on of the most effective tools for managers to cope with the changing organizational environment. it grantess suitable services to customers, particularly in public service enterprises. if such training os goal oriented, planned systematically, and tailored to the employees, job content, then not only it could increase employees and organizational performance, but also it c...

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...