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Studies have shown that the valveless piezoelectric pump with streamline flow tubes (VPPSFTs) can increase the flow rate while reducing the vortex, which has a broad application prospect and conforms to the huge potential demand in the fields of medical treatment, sanitation, and health care. The flow runner of the VPPSFT was designed as two segments with a smooth transition between the hyperbola segment and the arc segment. However, the effect of the radius of the arc segment on pump performance is not clear. Therefore, three groups of VPPSFT with arc segments of different curvature radii were designed in this study, and the influence of curvature radius of arc segment on the pump performance was explored. On the basis of the theoretical analysis of fluid continuity and conservation of energy, the structure of VPPSFT was designed, the experimental test was carried out, and the finite element simulation software was used for numerical analysis. The results show that the output performance increases with the increase in the radius of the arc segment, and the maximum flow rate was 116.78 mL/min. The amplitude and the flow rate are almost the same trend as the frequency. This study improves the performance of the valveless piezoelectric pump and provides reference for the structure design of VPPSFT.

Single-track Gray codes (STGCs) is a type of absolute position coding method for novel angular sensors, because it has single-track property over traditional Gray codes and mono-difference over linear feedback shift register codes. However, given that the coding theory of STGCs is incomplete, STGC construction is still a challenging task even though it has been defined for more than 20 years. Published coding theories and results on STGCs are about two types of STGC, namely, necklace and self-dual necklace ordering, which are collectively called as k-spaced head STGCs. To find a new code, three constraints on generating sequences are proposed to accelerate the searching algorithm, and the complete searching result of length-6 STGCs is initially obtained. Among the entire 132 length-6 STGCs, two novel types of STGCs with non-k-spaced heads are found, and the basic structures of these codes with the general length n are proposed and defined as twin-necklace and triplet-necklace ordering STGCs. Furthermore, d-plet-necklace ordering STGC, which unifies all the known STGCs by changing the value of d, is also defined. Finally, a single-track absolute encoder prototype is designed to prove that STGCs are as convenient as the traditional position coding methods.

Compared with amorphous shape memory polymers (SMPs), semicrystalline SMPs have more diverse shape memory effects (SMEs) which promotes their application in smart structures. To reveal the driving mechanism of the triple SMEs of semicrystalline SMPs, our study focuses on developing the constitutive model under the condition of finite deformation. In the paper, a thermo-mechanical constitutive model under consideration of the second law of thermodynamics is developed based on the theory of thermodynamics with internal state variables. The model can be used to describe the nonequilibrium response of the amorphous and semicrystalline components in the vicinity of the glass transition, melting, and crystallization. To verify the validity of model, numerical simulation is carried out for a thermo-mechanical shape memory cycle which can be divided into a two-step programing process and a two-step recovery process. The comparison between the model results and the test data shows good agreement.