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Application of grammatical evolution to coefficient identification problem in two-dimensional elastic problem

100%

Kuroda T. , Sugiura H. , Kita E.

Computer Assisted Methods in Engineering and Science

2013

tom Vol. 20, no. 1

3--13

Grammatical evolution (GE), which is a kind of evolutionary algorithms, is designed to find a function, an executable program or program fragment that will achieve a good fitness value for the given objective function to be minimized. In this study, GE is applied for the coefficient identification problem of the stiffness matrix in the two-dimensional elastic problem. Finite element analysis of the plate with a circular hole is performed for determining the set of the stress and the strain components. Grammatical evolution determines the coefficient matrix of the relationship between the stress and strain components. The coefficient matrix is compared with Hooke's law in order to confirm the validity of the algorithm. After that, three algorithms are shown for improving the convergence speed of the original GE algorithm.

Pressure Induced Phase Transitions and EOS Derived for Laves Phase Deuterides ErFe2Dx (x = 1.35, 1.9 and 3.4)

100%

Sugiura H. , Filipek S. M. , Paul-Boncour V. , Marchuk I.

2008

tom Vol. 82, nr 10

1959-1972

The energy dispersive X-ray diffraction patterns of ErFe2Dx deuterides [where x = 1.35 (alfa1 phase), x = 1.9 (alfa2 phase) and x = 3.4 (beta phase)] have been measured under pressure up to 31 GPa. Compression curves and equation of state (EOS) parameters were determined us ing ex per i men tal data. ErFe2D1.35 and ErFe2D1.9 de com posed into phases with low (alfa1 ,, alfa 2 ,) and high (alfa1 ,, alfa 2 ,,) deuterium concentrations around 8 GPa. As the pressure was raised above 8 GPa, the D con cen tra tion in the alfa1 ,, alfa 2 , phases re mained close to about x = 0.2 whereas in the alfa1 " alfa 2 ,, phases it in creased from x = 2.1 to a max i mum of x = 4.6 at about 20 GPa. This was accompanied with a progres sive distortion of the alfa1 ,, alfa 2 ,, phases from a cubic to wards an orthorhombic structure. This decomposi tion process occurs with a large hysteresis effect between loading and unloading cycles. A similar decomposition into beta , and beta ,, phases seem ingly oc curs also for ErFe2D3.4 at 11 GPa being accompanied with a change of initial rhombohedral (R3m) symmetry to another one. The D content in this new beta" phase (x ~4.6) be comes close to that of orthorhombic ErFe2H5. These processes have character of spinodal decomposition and are related to a lowering of its critical temperature upon applied pressure.

High pressures studies on hydrides of selected manganese alloys

75%

Sugiura H. , Filipek S. , Paul-Boncour V. , Marchuk I. , Liu R. , Pyun S.

2006

tom Vol. 51,suppl.1

73-77

Specific behavior found in hydrides formed in manganese, Mn-Ni and YMn2 under high pressure is presented and discussed. The synthesis of ferromagnetic fcc-manganese was proved. Parameters of the equations of state (EOS) derived from measurements in the diamond anvil cell (DAC) are summarized for manganese hydrides and for hydrides derived from YMn2 Laves phase. It was found that the compression behavior of recently discovered YMn2H6 is different from YMn2-based hydrides with lower hydrogen content.