a novel acrylic acid-functionalized fe3o4 magnetic nanoparticle with a core-shell structure was developed for utilization as a heterogeneous organosuperacid in chemical transformations. the structural, surface, and magnetic characteristics of the nanosized catalyst were investigated by various techniques such as transmission electron microscopy (tem), thermogravimetric analysis (tga), and ft-ir...

there are many approaches for solving variety combinatorial optimization problems (np-compelete) that devided to exact solutions and approximate solutions. exact methods can only be used for very small size instances due to their expontional search space. for real-world problems, we have to employ approximate methods such as evolutionary algorithms (eas) that find a near-optimal solution in a r...

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...

power transformers are important equipments in power systems. thus there is a large number of researches devoted of power transformers. however, there is still a demand for future investigations, especially in the field of diagnosis of transformer failures. in order to fulfill the demand, the first part reports a study case in which four main types of failures on the active part are investigate...

a significant problem in multicarrier communication systems is the necessity to reduce the value of papr (peak-to-average power ratio) of transmitting signal. in this thesis we study the effect of the system parameters such as coding and modulation types on papr and ultimate ber in a mc-cdma system. in this study we consider fading channel as well as the nonlinearity of transmitter’s amplifier ...

wireless sensor networks (wsns) are one of the most interesting consequences of innovations in different areas of technology including wireless and mobile communications, networking, and sensor design. these networks are considered as a class of wireless networks which are constructed by a set of sensors. a large number of applications have been proposed for wsns. besides having numerous applic...

determination of uranium in natural water and complex solutions using ion exchange chromatography: a combined procedure using ion exchange chromatography and uv-vis spectrophotometry techniques has been developed to measure uranum in natural water and complex solutions. after conditicing , one hundred milli liters of sample solutions have been passed through an ion exchange column,pachked with ...

one of the most important number sequences in mathematics is fibonacci sequence. fibonacci sequence except for mathematics is applied to other branches of science such as physics and arts. in fact, between anesthetics and this sequence there exists a wonderful relation. fibonacci sequence has an importance characteristic which is the golden number. in this thesis, the golden number is observed ...