Nonlinear Quasi-zero stiffness (QZS) mechanisms were studied to overcome the weakness of linear isolators. This paper presents an integrated design of the QZS mechanism. First, various types of QZS vibration mechanisms are analyzed and a generalized model for QZS mechanisms is derived. The generalized model consists of two main parts: link and horizontal spring. The motion equation of the QZS mechanism is a Duffing equation with nonlinear stiffness. Based on the generalized model, the design problem of the QZS mechanism is converted into the kinematic design of a link element. For simplicity, the link is generalized with a cam-roller mechanism. The integrated design approach shows that the QZS mechanism can have desired QZS characteristics with properly designed cam geometry.
Large colorless single crystals of sodium zeolite X, stoichiometry |Na80|[Si112Al80O384]-FAU, with diameters up to 200 μm and Si/Al = 1.41 have been synthesized from gels with the composition of 2.40SiO2 : 2.00NaAlO2 : 7.52NaOH : 454H2O : 5.00TEA. One of these, a colorless octahedron about 200 μm in cross-section has been treated with aqueous 0.1 M KNO3 for the preparation of K + -exchanged zeolite X. The crystal structure of |K80|[Si112Al80O384]-FAU per unit cell, a = 24.838(4) Å, dehydrated at 673 K and 1 × 10 −6 Torr, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd at 294 K. The structure was refined using all intensities to the final error indices (using only the 707 reflections for which Fo > 4σ (Fo)) R1 = 0.075 (based on F) and R2 = 0.236 (based on
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