the energy of a graph is equal to the sum of the absolute values of its eigenvalues. two graphs of the same order are said to be equienergetic if their energies are equal. we point out the following two open problems for equienergetic graphs. (1) although it is known that there are numerous pairs of equienergetic, non-cospectral trees, it is not known how to systematically construct any such pa...

One of the difficulties with PWM switching converters is high switching loss and electromagnetic interference due to switching at non-zero voltage and current, which limits the operating frequency. In order to reduce the converter volume and weight (by increasing the frequency) and reducing switching losses, zero voltage and current switching methods are recommended. In this paper, four main ze...

One of the difficulties with PWM switching converters is high switching loss and electromagnetic interference due to switching at non-zero voltage and current, which limits the operating frequency. In order to reduce the converter volume and weight (by increasing the frequency) and reducing switching losses, zero voltage and current switching methods are recommended. In this paper, four main ze...

 First principle calculations of nanolayered ZnO polymorphs (Wurzite–, Zincblende–, Rocksalt–structures) in the scheme of density functional theory were performedwith the help of full potential linear augmented plane wave (FP-LAPW) method. Theexchange - correlation potential is described by generalized gradient approximation asproposed by Perdew–Burke–Ernzrhof (GGA–PBE) and modified Becke–Johns...

Water splitting for hydrogen production under sunlight using TiO2 as photo catalyst provides a better route for solar energy and attracts the attention of many researchers. The photo catalytic activity of TiO2 under sunlight irradiation depends on the band gap energy. The transition metal doped TiO2 shows an edge over TiO2 in optical absorbance and photo catalytic activity. Thin film of Cr dope...

in internal combustion engines, only about a third of the total fuel input energy is converted into useful work. if the energy rejected into the cooling system and the exhaust gases could be recovered instead and put into useful work, fuel economy would have been substantially improved. the main aim of this research paper was to evaluate the effects of the hybrid nano-catalyst containing cerium...

The important characteristic of sea waves is their high energy density, which is the highest among renewable energy sources. Having up to 2700 km. of shoreline, Iran has a great potential in construction of offshore wave buoys (hereafter called OWB). In this article a OWB model with the possibility of assembling different buoy configurations is introduced. The system is exposed to regular and i...

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