AUTOTEM - Automated geometry meshing and heat conduction calculation

Temperature distribution for an arbitrary irregular body is calculated by AUTOTEM, which generates required input data automatically by computer. Temperature distribution is calculated for a two-dimensional plane section in /x,y/ coordinates or for an axisymmetric irregular body in /r,z/ coordinates

Design of photonic crystal optical waveguides with single-mode propagation in the photonic bandgap

The authors present a systematic method for designing dielectric-core photonic crystal optical waveguides that support only one mode in the photonic bandgap (PBG). It is shown that by changing the sizes of thc air columns (without perturbing the positions of the centres of the air column) in the two rows that are adjacent to the middle slab, the higher order mode(s) can be pushed out of the photonic bandgap, resulting in single-mode wave propagation in the bandgap

Development of EHD Ion-Drag Micropump for Microscale Electronics Cooling Systems

In this investigation, the numerical simulation of electrohydrodynamic (EHD) ion-drag micropumps with micropillar electrode geometries have been performed. The effect of micropillar height and electrode spacing on the performance of the micropumps was investigated. The performance of the EHD micropump improved with increased applied voltage and decreased electrode spacing. The optimum micropillar height for the micropump with electrode spacing of 40$\mu$m and channel height of 100$\mu$m at 200V was 40$\mu$m, where a maximum mass flow rate of 0.18g/min was predicted. Compared to that of planar electrodes, the 3D micropillar electrode geometry enhanced the overall performance of the EHD micropumps.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Unstable topography of biphasic surfactant monolayers

We study the conformation of a heterogeneous surfactant monolayer at a fluid-fluid interface, near a boundary between two lateral regions of differing elastic properties. The monolayer attains a conformation of shallow, steep `mesas' with a height difference of up to 10 nm. If the monolayer is progressively compressed (e.g. in a Langmuir trough), the profile develops overhangs and finally becomes unstable at a surface tension of about K(delta c_0)^2, where (delta c_0) is the difference in spontaneous curvature and K a bending stiffness. We discuss the relevance of this instability to recently observed folding behavior in lung surfactant monolayers, and to the absence of domain structures in films separating oil and water in emulsions.Comment: 7 pages, 7 figures, LaTex using epl.cls, accepted for Europhys Let

Manufacturing Of Robust Natural Fiber Preforms Utilizing Bacterial Cellulose as Binder

We present a novel method of manufacturing rigid and robust short natural fiber preforms using a papermaking process. Bacterial cellulose acts simultaneously as the binder for the loose fibers and provides rigidity to the fiber preforms. These preforms can be infused with a resin to produce truly green hierarchical composites

pH-triggered phase inversion and separation of hydrophobised bacterial cellulose stabilised Pickering emulsions

The pH-triggered transitional phase behaviour of Pickering emulsions stabilised by hydrophobised bacterial cellulose (BC) is reported in this work. Neat BC was esterified with acetic (C2–), hexanoic (C6–) and dodecanoic (C12–) acids, respectively. We observed that C6– and C12–BC stabilised emulsions exhibited a pH-triggered reversible transitional phase separation. Water-in-toluene emulsions containing of 60 vol.% dispersed phase stabilised by C6– and C12–BC were produced at pH 5. Lowering the pH of the aqueous phase to 1 did not affect the emulsion type. Increasing the pH to 14, however, caused the emulsions to phase separate. This phase separation was caused by electrostatic repulsion between modified BC due to dissociable acidic surface groups at high pH, which lowered the surface coverage of the water droplets by modified BC. When the pH was re-adjusted to 1 again, w/o emulsions re-formed for C6– and C12–BC stabilised emulsions. C2–BC stabilised emulsions, on the other hand, underwent an irreversible pH-triggered transitional phase separation and inversion. This difference in phase behaviour between C2–BC and C6–/C12–BC was attributed to the hydrolysis of the ester bonds of C2–BC at high pH. This hypothesis is in good agreement with the measured degree of surface substitution (DSS) of modified BC after the pH-triggered experiments. The DSS of C2–BC decreased by 20% whilst the DSS remained constant for C6– and C12–BC