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The study describes the recoverable strain in Ti-24Nb-4Zr-8Sn (wt.%) alloy with cellular structure having rhombic dodecahedron and topology-optimised unit cell fabricated by electron beam melting. At a certain cyclic strain, the recoverable strain in rhombic dodecahedron structure was greater in comparison to topology-optimised structure because of different stress distribution on struts. The cellular structure of Ti-24Nb-4Zr-8Sn alloy with rhombic dodecahedron unit cell had larger recoverable strain in comparison to Ti-6Al-4V cellular structure. This behaviour is attributed to higher strength to modulus ratio (σ/E) and superelasticity of Ti-24Nb-4Zr-8Sn alloy. [ABSTRACT FROM AUTHOR]

The two main objectives of this article are (1) to determine the bifurcating periodic responses accurately and to study the effects of time delay and feedback gain on the steady state response in autonomous oscillators by means of the residue harmonic balance method; and (2) to study the dynamics of both the autonomous and non-autonomous Duffing-van der Pol oscillators with delayed position feedback as examples. The results of the steady state response to frequency and amplitude excitation versus the time delay, positive and negative feedback gains are studied. Both saddle-node and subcritical Hopf bifurcations are found and discussed. The obtained second-order solutions are in excellent agreement with numerical integration results. By combining both harmonic balance and polynomial homotopy continuation techniques, the superharmonic resonance responses of the non-autonomous oscillator are investigated in order to obtain all possible steady state solutions. The effects of the feedback gains and time delay on the steady state response are found analytically. It is shown that the fundamental and superharmonic amplitudes decrease with increasing feedback gain. Furthermore, the multiple symmetric solutions of the response amplitudes versus those of external excitation are detected when time delay becomes smaller. [ABSTRACT FROM AUTHOR]

Abstract: Structural and physical properties of Na x CoO2 and superconducting Na x CoO2·yH2O hydrates have been systematically investigated. Raman scattering measurements reveal that the five active phonons in Na x CoO2·yH2O system change systematically with the H2O intercalation and modification of superconductivity, in particular the A 1g and E 1g modes in correlation with oxygen movements. Incoherent inelastic neutron scattering (IINS) study on the local structure of H2O-layers in Na x CoO2·yH2O (0≤y≤1.8) suggests the presence of three types of clusters, H3O+, H5O+ and ice-Ih like weakly bonded water, among CoO2 sheets. Electron energy loss (EEL) analysis on Na0.33CoO2·yH2O (0≤y≤1.3) indicates certain notable changes in the electronic structure during hydration. Microstructure and structural phase transitions accompanied with local atomic ordering in the charge-ordered phase Na0.5CoO2 have been investigated along with the hexagonal–orthorhombic phase transition. [Copyright &y& Elsevier]