Papers

The constraint mechanical systems with quasi coordinates are more universal than generalized coordinates, in this paper, we study the Noether symmetries and conserved quantities of nonconservative singular systems in phase space. Firstly, the internal constraints induced by singularity are equivalent considered as extrinsic nonholonomic constraints, the canonical equations of constrained Hamilton systems with quasi coordinates are obtained by using transform to the Euler-Lagrange equations. Secondly, the infinitesimal transformations of time, quasi coordinates and generalized momentum are introduced, the definition, criterion and Noether theorem are obtained according to the regular action quantity keep generalized quasi invariance under the transformation, meanwhile, the inverse problem of the Noehter symmetry is also studied. Finally, an example is given to illustrate the application of the content. The results found that the rational use of quasi coordinates will make the constraints caused by the singularity of the system do not affect the standard form of the regular equations and avoid the emergence of constrained multipliers, the conservation is more concise.

A frequent approach to synthesize a series of 3-(4,6-dichloro-1,3,5-triazin-2-yl)-2- phenylthiazolidin- 4-one was developed by applying an efficient multi-component reaction. Also, the synthesized compounds were tested for their antimicrobial activity. The most admirable results were observed with the substituted phenyl thiazolidin-4-one triazine analogs and it could be a potential starting point to develop innovative lead compounds fight against a panel of some human disease-causing pathogens bacteria and fungi. All synthesized compounds were characterized by IR, 1H NMR, mass and elemental analysis.

The presented paper deals with the effect of UV radiation and change in rate of recombination on the operation of metal oxide gas sensors. The performance of a simple metal oxide sensor is simulated first and the relation between absorbed gas concentration and resistance is monitored in absence of UV radiation. Later, the same performance is monitored in the presence of UV radiation on the sensor with the occurrence of surface recombination phenomenon. The performances are simulated on MATLAB. The Grain boundary resistance (Rgb), neck resistance (Rn) and total resistance (R) were obtained by simulating standard equation on MATLAB software. The effect of the surface recombination on absorption of gas concentration and change in resistance is also taken into account. It has been observed that the resistance of the sensors depends on the grain size (L), flux density, absorbed gas concentration (Nr), depletion width (W).