One of the most efficient lighting technology is based on light-emitting diodes (LEDs). Common LED drivers with AC-input (50-60Hz) usually require a bulk electrolytic capacitor to decrease low-frequency ripple in the output. However, the critical element that limits the lifespan of the LED driver is the electrolytic capacitor. An isolated off-line LED driver is proposed in this paper, in which ...

critical discourse analysis has proved to be of great help in analyzing the form and meaning of literary works. certain scholars such as norman fairclough have greatly improved such studies. the present study deals with one of the political letters of mas'ud i of ghazni to arsalan khan written by his secretary abul-fazl bayhaqi. the complete version of the letter has been recorded in bayhaqi’s ...

Recent developments in gas-to-liquid conversion industry lead to reduction in initial investment, and it is expected by growth in demand for refined products in countries and the need to import these products in the countries. Implementing such projects can prevent currency outflow. In this article an integrated structure is developed for producing liquid fuels from natural gas through Fischer-...

in this paper a novel all-optical logic nand, nor and xor gate based on nonlinear directional coupler theory is demonstrated. we use the identical structure which contains three waveguides, for designing these gates; the only difference however, is the power of inputs light beam. in other words, while a beam with 4 w/μm in power considered as logical one, the output is nand gate and if a beam w...

This work studies the effects of dynamic threshold design techniques on the speed and power of digital circuits. A new dynamic threshold transistor structure has been proposed to improve performances of digital circuits. The proposed switched-capacitor dynamic threshold PMOS (SC-DTPMOS) scheme employs a capacitor along with an NMOS switch in order to effectively reduce the threshold voltage of ...

data envelopment analysis (dea) and balanced scorecard (bsc) are two well-known approaches for measuring performance of decision making units (dmus). bsc is especially applied with quality measures, whereas, when the quantity measures are used to evaluate, dea is more appropriate. in the real-world, dmus usually have complex structures such as network structures. one of the well-known network s...

in the last few decades, iran has experienced sharp fertility decline. studies indicate that women have a major role in childbearing; therefore, their empowerment and autonomy will lead to changes in their fertility behavior. this paper examines the relationship between family power structure and fertility behavior in the tehran city. the data is collected from around 400 women in tehran who ar...

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