Poly(ethylene terephthalate) (PET) has a low glass transition temperature. Therefore it has significant applications in fields where low bonding temperature is needed. But PET microfluidic chip production using a hot embossing/bonding method has rarely been reported. In this study, hot embossing was conducted for a micro-feature's fabrication on a PET substrate, and a special temperature-pressure profile was used to achieve high replication accuracy without a vacuum; plasma surface treatment was used to improve the bonding capability of PET material, a cover plate was bonded with a substrate at a low temperature of around 63 • C, and VB2 was used as a separation solvent to test the capability of the PET microfluidic chip. The results show that high replication accuracy can be achieved using the new hot embossing process without a vacuum. Plasma surface treatment has increased the surface energy of the PET substrate and hot bonding can be achieved in low temperature. Plasma treatment has also changed the hydrophobic property of PET material; electrophoresis has been conducted successfully.
Hyperfine structure (HFS) of La I are reported using Doppler-free intermodulated fluorescence, Doppler-limited laser-induced fluorescence and optogalvanic spectroscopy in a homemade hollow-cathode discharge tube. The A and B constants for the levels at 20197.34, 21447.86 cm-1 and A constants for the levels at 19379.40, 18156.97, 24910.38 and 24409.68 cm-1 are, to the authors' knowledge, reported for the first time. A linewidth less than 40 MHz and the different resolutions of fluorescence and optogalvanic spectroscopy are observed.
In this paper, a study of a three-dimensional (3D) self-propelled bionic flying bird in a viscous flow is carried out. This bionic bird is propelled and lifted through flapping and rotating wings, and better flying can be achieved by adjusting the flapping and rotation motion of wings. In this study, we found that the bird can fly faster forward and upward with appropriate center of rotation and oscillation without more energy consumption and have perfect flight performance at a certain angle of attack by adjusting the center of oscillation. The study utilizes a 3D computational fluid dynamics package which constitutes combined immersed boundary method and the volume of fluid method. In addition, it includes adaptive multigrid finite volume method and control strategy of swimming and flying. self-propelled, bird flying, numerical simulation, three-dimensional PACS number(s): 47.11.Df, 47.32.C-, 47.63.MCitation: Zhu L L, Guan H, Wu C J. A study of a three-dimensional self-propelled flying bird with flapping wings. In nature, many animals have perfect flight performance which has fascinated humans for many centuries. Most of the time, they are propelled and lifted through unique flapping motion which can control the turbulent flow and is more complicated and efficient than the flight with fixed wings such as man-made aerial vehicles. The unsteady aerodynamics of flapping flyers is determined not only by surface deformation but also by some important features of the aerodynamics of biological flapping flyers as a result of large flapping wing displacement and rotation, small size, and low flight speeds as reviewed by Shyy et al. [1,2].Many studies have shown that vortex structures, unsteady separation and reattachment are produced and developed around the flapping wings in the flow fields [3][4][5][6][7][8]. All these 3D effects have a tremendous impact on the flight performance. Studying the dynamic interaction between the fluid and the bionic bird and analizing these 3D effects may lead to understanding the cause of lift force and a better micro air vehicles (MAV) design [1], which has the potential to develop our sensing and information gathering capabilities. The aerodynamics of flapping flyers has attracted global attention in the past few decades. Pennycuic [9] has collected wingbeat frequencies of 15 species of birds cruising flight and found that the lift force is proportional to the flapping frequency. Ansari et al.[10] studied the effects of wing kinematics on the aerodynamic performances of insect-like flapping wings in hover based on non-linear unsteady aerodynamic models and found that the lift force and the thrust force increased with increasing flapping frequency, flapping angle, and advanced wing rotation, but such increases were limited by practical conditions. Additionally, much experimental and computational work have been done
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