In this article the corrosion rate of the austenitic stainless steel type 304, under the synergistic effect of environmental factors has been assessed via potentiodynamic polarization scan.Salinity, velocity, pH and t...In this article the corrosion rate of the austenitic stainless steel type 304, under the synergistic effect of environmental factors has been assessed via potentiodynamic polarization scan.Salinity, velocity, pH and temperature are the factors which induce effects on the corrosion rate of the considered metal.Quantitative analysis is applied using the full two-level factorial experimental design method, which results in the contribution value of each parameter in changing the quantity of average corrosion rate in both individual and synergistic cases.Besides this quantitative analysis, qualitative analysis has been used to predict the variation direction.These two analyses show the important role of the synergistic action, which changes the variation direction of corrosion rate and the contribution percentage of each parameter in varying the value of corrosion rate.Applying both these analyses can show the magnitude and quality of each parameter＇s effect, which is remarkably valuable in marine applications.展开更多
We present a comparative study of electronic structure and magnetic properties of Gd5Si4 and Gd5Ge4compounds using first principles full potential linearized augmented plane wave(FP-LAPW) method based on density funct...We present a comparative study of electronic structure and magnetic properties of Gd5Si4 and Gd5Ge4compounds using first principles full potential linearized augmented plane wave(FP-LAPW) method based on density functional theory(DFT) using the WIEN2 k code. The local-spin density approximation with correlation energy(LSDA+U) method has been used as the exchange-correlation potential. The optimized lattice constants are in good agreement with the experimental data. The total and partial density of states(DOS) of Gd5Si4 and Gd5Ge4show the difference in Si 3p-Gd 5d and Ge 4p-Gd 5d hybridization, which have an effective role in indirect exchange interaction.In addition, the magnetic moments of Gd, Si, and Ge atoms and the compounds are calculated to clarify the differences in the magnetic properties of these compounds.展开更多
We study the energy distribution of a noncommutative Reissner–Nordström black hole.We consider both Ein-stein and Møller prescriptions,and compare our results with the corresponding results obtained recentl...We study the energy distribution of a noncommutative Reissner–Nordström black hole.We consider both Ein-stein and Møller prescriptions,and compare our results with the corresponding results obtained recently for a Schwarzschild black hole.展开更多
This paper presents a technique for deriving least-squares-based polynomial bubble functions to enrich the standard linear finite elements,employed in the formulation of Galerkin weighted-residual statements.The eleme...This paper presents a technique for deriving least-squares-based polynomial bubble functions to enrich the standard linear finite elements,employed in the formulation of Galerkin weighted-residual statements.The element-level linear shape functions are enhanced using supplementary polynomial bubble functions with undetermined coefficients.The enhanced shape functions are inserted into the model equation and the residual functional is constructed and minimized by using the method of the least squares,resulting in an algebraic system of equations which can be solved to determine the unknown polynomial coefficients in terms of element-level nodal values.The stiffness matrices are subsequently formed with the standard finite elements assembly procedures followed by using these enriched elements which require no additional nodes to be introduced and no extra degree of freedom incurred.Furthermore,the proposed technique is tested on a number of benchmark linear transport equations where the quadratic and cubic bubble functions are derived and the numerical results are compared against the exact and standard linear element solutions.It is demonstrated that low order bubble enriched elements provide more accurate approximations for the exact analytical solutions than the standard linear elements at no extra computational cost in spite of using relatively crude meshes.On the other hand,it is observed that a satisfactory solution of the strongly convection-dominated transport problems may require element enrichment by using significantly higher order polynomial bubble functions in addition to the use of extremely fine computational meshes.展开更多
文摘In this article the corrosion rate of the austenitic stainless steel type 304, under the synergistic effect of environmental factors has been assessed via potentiodynamic polarization scan.Salinity, velocity, pH and temperature are the factors which induce effects on the corrosion rate of the considered metal.Quantitative analysis is applied using the full two-level factorial experimental design method, which results in the contribution value of each parameter in changing the quantity of average corrosion rate in both individual and synergistic cases.Besides this quantitative analysis, qualitative analysis has been used to predict the variation direction.These two analyses show the important role of the synergistic action, which changes the variation direction of corrosion rate and the contribution percentage of each parameter in varying the value of corrosion rate.Applying both these analyses can show the magnitude and quality of each parameter＇s effect, which is remarkably valuable in marine applications.
文摘We present a comparative study of electronic structure and magnetic properties of Gd5Si4 and Gd5Ge4compounds using first principles full potential linearized augmented plane wave(FP-LAPW) method based on density functional theory(DFT) using the WIEN2 k code. The local-spin density approximation with correlation energy(LSDA+U) method has been used as the exchange-correlation potential. The optimized lattice constants are in good agreement with the experimental data. The total and partial density of states(DOS) of Gd5Si4 and Gd5Ge4show the difference in Si 3p-Gd 5d and Ge 4p-Gd 5d hybridization, which have an effective role in indirect exchange interaction.In addition, the magnetic moments of Gd, Si, and Ge atoms and the compounds are calculated to clarify the differences in the magnetic properties of these compounds.
基金Supported by the Center for Excellence in Astronomy and Astrophysics(CEAAI-RIAAM),Maragha,Iran.
文摘We study the energy distribution of a noncommutative Reissner–Nordström black hole.We consider both Ein-stein and Møller prescriptions,and compare our results with the corresponding results obtained recently for a Schwarzschild black hole.
基金study grant provided by the Department of Chemical Engineering,Loughborough University。
文摘This paper presents a technique for deriving least-squares-based polynomial bubble functions to enrich the standard linear finite elements,employed in the formulation of Galerkin weighted-residual statements.The element-level linear shape functions are enhanced using supplementary polynomial bubble functions with undetermined coefficients.The enhanced shape functions are inserted into the model equation and the residual functional is constructed and minimized by using the method of the least squares,resulting in an algebraic system of equations which can be solved to determine the unknown polynomial coefficients in terms of element-level nodal values.The stiffness matrices are subsequently formed with the standard finite elements assembly procedures followed by using these enriched elements which require no additional nodes to be introduced and no extra degree of freedom incurred.Furthermore,the proposed technique is tested on a number of benchmark linear transport equations where the quadratic and cubic bubble functions are derived and the numerical results are compared against the exact and standard linear element solutions.It is demonstrated that low order bubble enriched elements provide more accurate approximations for the exact analytical solutions than the standard linear elements at no extra computational cost in spite of using relatively crude meshes.On the other hand,it is observed that a satisfactory solution of the strongly convection-dominated transport problems may require element enrichment by using significantly higher order polynomial bubble functions in addition to the use of extremely fine computational meshes.
