Primjenljivost transportnih parametara Townsendovog izboja u simulacijama RF i DBD izboja u modelu tekućine

The fluid model has recently been used in several domains like the simulation of the discharges that use the sinusoidal electric field as in the RF and DBD discharges. In this work, the validity of using the transport parameters of the Townsend discharge in the simulation of the ac discharges by the fluid model method is studied. Generally in the ac discharges, the drift velocity of the dc discharge is taken multiplied by sin(ωt), and the reaction rates and the diffusion coefficient are taken constant. These suppositions are well tested. It is confirmed that the drift velocity of the dc electric field can be used multiplied by sin(ωt) in the simulation of the ac discharges by the fluid model if the first non-equilibrium and the difference on the negative side are neglected. The ionization frequency of the dc field multiplied by sin(ωt) should be used with caution in the simulation of the ac discharges and attention should be paid to two main factors: the phase shift and the amplitude. The ionization coefficient of the dc field multiplied by sin(ωt) can’t be used for several reasons. It is not realistic to take constant reaction rates in the simulation of the ac discharges by the fluid model. The diffusion coefficients of the dc field can be used in the simulation of the ac discharges by the fluid model as constant values only in special conditions.Model tekućine se u posljednje vrijeme rabi u više područja za simulaciju izboja sa sinusoidalnim električnim poljem, poput RF i DBD izboja. U ovom se radu proučava primjenljivost transportnih parametara Townsendovog izboja u simulaciji izboja izmjeničnom strujom (AC) u modelu tekućine. Općenito se u AC izbojima uzima posmična brzina u izboju stalnom strujom (DC) pomnožena sa sin(ωt) a brzine reakcija i difuzijski koeficijent uzimaju se stalnima. Te se pretpostavke pažljivo ispituju. Potvrđuje se da je ispravno uzeti posmičnu brzinu DC polja pomnoženu sa sin(ωt) u simulacijama AC izboja u modelu tekućine ako se zanemare prvo neravnotežno stanje i razlike na negativnoj strani. Frekvencija ionizacije DC polja pomnožena sa sin(ωt) može se rabiti u simulacijama AC izboja ali s oprezom pazeći na dva faktora: pomak faze i amplitudu. Ionizacijski koeficijent DC izboja pomnožen sa sin(ωt) ne može se rabiti u simulacijama AC izboja zbog više razloga. Nije realno pretpostaviti stalne brzine reakcija u simulacijama AC izboja u modelu tekućina. Vrijednosti difuzijskih koeficijenata DC izboja mogu se rabiti kao stalne vrijednosti u AC izbojima u modelu tekućine samo u posebnim uvjetima

A numerical study of pressure changes in dead-end pores

Dead-end pores are usually present in natural porous media especially in consolidated sandstone and limestone rocks. However, the presence of the dead-end pores is usually ignored. Then, the influences of the dead end pores to the flow system are also neglected. In this paper, pressure changes for the periods of transient and steady state of the dead-end pores are studied using lattice gas automata model. A simulation result is compared with the past works. They show that the model is viable to perform simulation of dead-end pore pressure. Some parameters such as pressure distribution and size of neck and body of the dead-end pores are varied to examine their effects. We found that the parameters affect the rate of pressure change during transient period. In addition, the parameters also affect the pressure fluctuation during steady state period. The dead-end pores have function either as source or sink in the transient period depend on initial and injection pressures. During steady state period, the dead-end pores behave both as source and sink since the pressure in the pores fluctuates around an equilibrium pressure between the pressure of dead-end pore and that of main channel at the neck position of dead-end pore

New complexes of manganese (II) and copper (II) derived from the two new furopyran-3, 4-dione ligands: Synthesis, spectral characterization, ESR, DFT studies and evaluation of antimicrobial activity

A total of four new metal complex derivatives of two new ligands 2-(hydroxy(phenyl)-6-methyl-2H-furo [3,2-c]pyran-3,4-dione (L1) and 2-(hydroxyl (2-hydroxyphenyl) -6-methyl-2H-furo [3,2-c]pyran-3,4-dione (L2) with the metal ions Mn(II) and Cu(II) have been successfully prepared in alcoholic medium. The complexes obtained are investigated by spectral studies with the use of FT-IR and UV–vis techniques, ESR and magnetic measurements. The IR spectra suggest that the oxygen atoms of the two ligands are engaged in the bond with the central metal. The electronic spectra of the complexes and their magnetic moments provide information about geometries. The molar conductance measurements showed that the complexes are non-electrolytes. Theoretical calculations invoking geometry optimization and molecular orbital description HOMO and LUMO are done using DFT density functional theory. The experimental results and the calculated structural parameters, bond distances and angles, revealed a distorted octahedral geometries around the manganese and copper center through the oxygen of the furan ring for the synthesized complexes ([M(L)2(H2O)2]nH2O; M: metal; L: ligand). The antimicrobial activity of the ligands and their complexes was evaluated in vitro against different bacteria and fungi using agar diffusion method. The ligands and their complexes of manganese (II) and copper (II) exhibited a strong antifungal activity. Copper and manganese complexes have different antibacterial properties against bacteria. The ligand L1 and there complexes were found to be more active against Gram-positive than Gram-negative bacteria.publishe