The air-retaining property of the hydrophobic surface can be widely employed in many applications. This study is carried out to enhance this property by biomimicking the structure of Salvinia molesta floating leaves, which features hydrophilic patches on a superhydrophobic structure. Different from the existing lotus structure, in this study, the theoretical models and equations governing the contact and sliding angles, and contact line density of the salvinia structure were developed. The Marangoni effect was re-examined and modified to consider the characteristic of the salvinia structure. In addition, a novel process was proposed to fabricate the salvinia and lotus structures, which were designed using mathematical models and numerical simulation results. Both structures were tested to verify the theoretical models and derived governing equations. The results indicate that the air-retaining property was greatly enhanced using the salvinia structure compared with the lotus one.
In this paper, we successfully demonstrate multifunctional surfaces based on scaffolding biomimetic structures, namely, hybrid salvinia leaves with moth-eye structures (HSMSs). The novel fabrication process employs scalable polystyrene nanosphere lithography and a lift-off process. Systematic characterizations show the biomimetic HSMS exhibiting superhydrophobic, self-cleaning, antiadhesive, and antireflective properties. Furthermore, the resulting surface tension gradient (known as the Marangoni effect) leads to a superior air retention characteristic in the HSMS under water droplet impact, compared with the traditional hybrid lotus leaf with a moth-eye structure (HLMS). Such results and learnings pave the way towards the attainment and mass deployment of dielectric surfaces with multiple functionalities for versatile biological and optoelectronic applications.
This paper proposes the design of a self-sensing compensating restrictor/pad module for hydrostatic bearings. The module consists of a bearing pad and the associated restrictor featuring the characteristics of self-sensing compensation and easy installation. The paper first introduces the configuration of the proposed module. Then, the lumped parameter model was used to derive the equation for the relationship between the pocket pressure and the bearing gap. Furthermore, equations governing the stiffness and load-carrying capacity of the bearing were also obtained. Influences of the design parameters, such as the land length and pressure ratio, on bearing performance and the feasibility of the new design were studied both analytically and experimentally. Results of the theoretical analysis were compared with that of the experiment. Superior performances on the aspects of stiffness and load-carrying capacity, as well as time delay due to the distance between restrictor and bearing pad to the traditional restrictors such as capillary and orifice were achieved. In addition, the proposed restrictor possesses the advantages of simplicity for both manufacturing and assembly in comparison with the membrane-type restrictors.
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