Implantable microfluidic and electronic systems for insect flight manipulation

Insect micro air vehicles represent a promising alternative to traditional small scale aircraft because they combine the enhanced energy storage and maneuverability of living insects with the controllability offered by microelectromechanical systems. These systems have been previously demonstrated, usually using either electrical (with implanted electrodes) or chemical (with implanted microfluidics) control schemes, but to date little work has been done on the creation of hybrid systems that use both these methods simultaneously. In this paper, we develop an integrated microsystem that uses both chemical and electrical methods to modulate the flight activity of Manduca sexta moths. The integration of two control schemes is essential because it could increase the number of achievable flight routines and duration. The electrical component of the system initiates and maintains flight by applying electrical pulses to an antenna lobe and an implanted drug delivery component modulates flight output power by administering a neurotransmitter dose to the central nervous system. Flight duration results acquired with this system are compared with those obtained from direct mechanical stimulation. We demonstrate that the electrical stimulation provides as much as 35-fold enhancement in flight duration with respect to mechanical agitation and that a 50% mean flight power output reduction can be achieved with the proper neurotransmitter dose.     

Synergistic electro-co-deposition and molecular mixing for reinforcement of multi-walled carbon nanotube in copper

Carbon nanotube-reinforced copper composite powder was prepared by a modified electro-co-deposition method that was carried out on small diameter (3 mm) tip of the cathode. The deposition was done at room temperature and atmospheric pressure. Samples were prepared under constant stirring by a magnetic stirrer. Transmission and scanning electron microscopy confirms the dispersion of multiwalled carbon nanotubes (MWCNT) in the copper matrix. Dispersion of MWCNTs in copper matrix by this method is very easy and the set up can be easily scaled up for the bulk production of MWCNT reinforced copper powder. The method for the fabrication of MWCNT reinforced copper powder; microstructure and morphology of the powder formed are reported.     

Two-way coupled SPH and particle level set fluid simulation

Grid-based methods have difficulty resolving features on or below the scale of the underlying grid. Although adaptive methods (e.g. RLE, octrees) can alleviate this to some degree, separate techniques are still required for simulating small-scale phenomena such as spray and foam, especially since these more diffuse materials typically behave quite differently than their denser counterparts. In this paper, we propose a two-way coupled simulation framework that uses the particle level set method to efficiently model dense liquid volumes and a smoothed particle hydrodynamics (SPH) method to simulate diffuse regions such as sprays. Our novel SPH method allows us to simulate both dense and diffuse water volumes, fully incorporates the particles that are automatically generated by the particle level set method in under-resolved regions, and allows for two way mixing between dense SPH volumes and grid-based liquid representations.     

Investigation of flow boiling in horizontal tubes: Part II—Development of a new heat transfer model for stratified-wavy, dryout and mist flow regimes

The new version of the flow pattern map presented in Part I of this paper has been used to modify the dry angle in the heat transfer model of Kattan-Thome-Favrat [J. Heat Transfer, 120 (1) (1998) 156]. This significantly improves the heat transfer prediction in stratified-wavy flow. Moreover, a new heat transfer prediction method has been developed for the dryout and mist flow regimes, which extends the applicability of the heat transfer model to these flow regimes. An extensive flow boiling heat transfer database has been acquired for R-22 and R-410A to develop and validate the new heat transfer prediction methods. The new model also shows good agreement with the independent heat transfer data of Lallemand et al. [M. Lallemand, C. Branescu, P. Haberschill, Local heat transfer coefficients during boiling of R-22 and R-407C in horizontal smooth and microfin tubes, Int. J. Refrigeration, 24 (2001) 57-72].