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Comparison between two geometrical nonlinear methods for truss analyses
M. Greco,R.C.G. Menin,I.P. Ferreira,F.B. Barros 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.6
This paper presents a comparison between two different procedures to deal with the geometric nonlinear analysis of space trusses, considering its structural stability aspects. The first nonlinear formulation, called positional, uses nodal positions rather than nodal displacements to describe the finite elements kinematics. The strains are computed directly from the proposed position concept, using a Cartesian coordinate system fixed in space. The second formulation, called corotational, is based on the explicit separation between rigid body motion and deformed motion. The numerical examples demonstrate the performances and the convergence of the responses for both analyzed formulations. Two numerical examples were compared, including a lattice beam with postcritical behavior. Despite the two completely different approaches to deal with the geometrical nonlinear problem, the results present good agreement.
Comparison between two geometrical nonlinear methods for truss analyses
Greco, M.,Menin, R.C.G.,Ferreira, I.P.,Barros, F.B. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.6
This paper presents a comparison between two different procedures to deal with the geometric nonlinear analysis of space trusses, considering its structural stability aspects. The first nonlinear formulation, called positional, uses nodal positions rather than nodal displacements to describe the finite elements kinematics. The strains are computed directly from the proposed position concept, using a Cartesian coordinate system fixed in space. The second formulation, called corotational, is based on the explicit separation between rigid body motion and deformed motion. The numerical examples demonstrate the performances and the convergence of the responses for both analyzed formulations. Two numerical examples were compared, including a lattice beam with postcritical behavior. Despite the two completely different approaches to deal with the geometrical nonlinear problem, the results present good agreement.
Spera, M.,Corso, D.,Di Franco, S.,Greco, G.,Severino, A.,Fiorenza, P.,Giannazzo, F.,Roccaforte, F. Elsevier 2019 Materials science in semiconductor processing Vol.93 No.-
<P><B>Abstract</B></P> <P>This work reports on the effect of high temperature annealing on the electrical properties of p-type implanted 4H-SiC. Ion implantations of Aluminum (Al) at different energies (30–200 keV) were carried out to achieve 300 nm thick acceptor box profiles with a concentration of about 10<SUP>20</SUP> at/cm<SUP>3</SUP>. The implanted samples were annealed at high temperatures (1675–1825 °C). Morphological analyses of the annealed samples revealed only a slight increase of the surface roughness RMS up to 1775 °C, while this increase becomes more significant at 1825 °C (RMS = 1.2 nm). Room temperature Hall measurements resulted in a hole concentration in the range 0.65–1.34 × 10<SUP>18</SUP>/cm<SUP>3</SUP> and mobility values in the order of 21–27 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>. The temperature dependent electrical measurements allowed to estimate an activation energy of the Al-implanted specie of about 110 meV (for the post-implantation annealing at 1675 °C) and a fraction of active p-type Al-dopant ranging between 39% and 56%. The results give useful indications for the fabrication of 4H-SiC JBS and MOSFETs.</P>
Ippen, C.,Greco, T.,Kim, Y.,Kim, J.,Oh, M.S.,Han, C.J.,Wedel, A. Elsevier Science 2014 ORGANIC ELECTRONICS Vol.15 No.1
Quantum dots are a highly attractive class of materials for the use in light-emitting devices, since they allow high color purity, facile tunability and solution-processing methods. Here, zinc selenide QDs are investigated for their suitability as emissive material in cadmium-free blue QD-LEDs. By adjusting the stoichiometry in the synthesis the emission wavelength can be tuned in the range of 390-435nm. For the assembly of the QD-LED, the device setup was adjusted to the low-lying ZnSe valence band energy by choosing a suitable hole-transport material. A first promising QD-LED result is achieved showing the characteristic narrow QD emission peak with a luminance of 25cd/m<SUP>2</SUP>.