Pills of Mefenamic acid were  employed as effective catalysts in the three component reaction of aromatic  aldehydes,  malononitrile,  as  well  as  4-hydroxycoumarin  or  barbituric  acid  in  aqueous solution,  using  reflux  conditions  in  order  to  synthesize  derivatives  of  dihydropyrano[2,3-c]chromene and pyrano[2,3-d]pyrimidine, correspondingly. Among the benefits of this technique, ...

This paper presents numerical methods for the simulation of combustion processes in porous media. The equations governing the ow in the porous medium are discretized by the mixed nite element method on Raviart{Thomas elements of lowest order. Hybridization is applied to transform the resulting equations into a form more convenient for the solution by multigrid methods. Special emphasis is put o...

The reaction of fly ash with a KOH solution was used to synthesize Linde F(K) zeolite, following which Fourier transform infrared spectroscopy were used to characterize the crystalline material. The competitive adsorption of Cu, Ni, Pb, and Cd onto this zeolite was subsequently studied in quaternary solution systems. The results show that the metal removal rates gradually increase with incr...

The combustion in future engines will work with a very high amount of recirculated exhaust gas in part load conditions to enable a low peak combustion temperature. This combustion suffers from instabilities of the process and a highly nonlinear behaviour. The paper presents the use of neural nets for observing the engine. A nonlinear model without feedback of measurements is linearised online a...

In this study nano-crystalline ZnO particles were synthesized by microwave-assisted solution combustion method. Zinc nitrate and urea were used as oxidizer and fuel, respectively. The effect of fuel to oxidizer (F/O) ratio on ZnO powder properties was investigated by using different urea/nitrate ratios. X-ray diffractometer, scanning electron microscopy and fourier transform infra-red were used...

Designing pulverized coal combustion simulation and visualization systems is still a complex task. The current solutions, such as the commercial CFD packages are focused on the precision of the computation. Our solution is suited to the education and computer graphics area, where the precision does not take the first, but also not the last place. The main factor in our solution utilizes the int...