Shape memory polymers (SMPs) and shape memory polymer composites have drawn considerable attention in recent years for their shape memory effects. A unified modeling approach is proposed to describe thermomechanical behaviors and shape memory effects of thermally activated amorphous SMPs and SMP-based syntactic foam by using the generalized finite deformation multiple relaxation viscoelastic theory coupled with time-temperature superposition property. In this paper, the thermoviscoelastic parameters are determined from a single dynamic mechanical analysis temperature sweep at a constant frequency. The relaxation time strongly depends on the temperature and the variation follows the time-temperature superposition principle. The horizontal shift factor can be obtained by the Williams-Landel-Ferry equation at temperatures above or close to the reference temperature (T r ), and by the Arrhenius equation at temperatures below T r . As the Arruda-Boyce eight-chain model captures the hyperelastic behavior of the material up to large deformation, it is used here to describe partial material behaviors. The thermal expansion coefficient of the material is regarded as temperature dependent. Comparisons between the model results and the thermomechanical experiments presented in the literature show an acceptable agreement.

The essence of logical stochastic resonance is the dynamic manipulation of potential wells. The effect of time delay on the depth of potential wells and the width of a bistable region can be inferred by logic operations in the bistable system with time delay. In a time-delayed synthetic gene network, time delay in the synthesis process can increase the depth of the potential wells, while that in the degradation process, it can reduce the depth of the potential wells, which will result in a decrease in the width of the bistable region (the reason for time delay to induce logic operations without external driving force) and the instability of the system (oscillation). These two opposite effects imply stretching and folding, leading to complex dynamical behaviors of the system, including period, chaos, bubble, chaotic bubble, forward and reverse period doubling bifurcation, intermittency, and coexisting attractors.

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In this study, it is proposed to utilize the advantages of Zn and Ga alloying to achieve improved performance Sn-0.7Cu solder alloys. As dual addition of Ga and Zn into Sn-0.7Cu alloy, wetting force increased while wetting time was reduced simultaneously. Zn promoted the nucleation of b-Sn and lead to the increase of nucleation temperatures. Meanwhile Ga reduced the melting temperature of Sn-0.7Cu. Zn addition introduced another Cu-Zn-Sn intermetallic formation, refined the microstructure. Vickers hardness of Sn-0.7Cu solder alloy and also impact shear strength of Sn-0.7Cu/Ni-Au/Cu solder joints have been obviously improved. The improvements can be attributed to Cu-Zn intermetallic acting as participation phases and solid solution strengthening brought by Ga in b-Sn matrix.