In this paper we extend the recently developed models that predict the magnetic field produced by thermoelectric currents in anisotropic homogeneous metal media to laminated composite metals. The premise is that thermoelectric anisotropy produced by the layering could be more pronounced and tailored to the specific needs as contrasted with the relatively small inherent crystallographic anisotropy in conventional metals. The effective anisotropic properties of the layered composite are first obtained for both directions along and normal to the layering using mixture theories. The magnetic field produced by directional heating of the composite panel is then calculated using the approach developed in A.H. Nayfeh et al. (J. Appl. Phys. 91, 225 (2002)).

We report measurements of photoluminescence from corrugated thin films of a light-emitting polymer. We find that emission into guided modes that would otherwise be trapped in the polymer may Bragg scatter off the corrugation to produce useful, far-field radiation. Analysis of the angle dependence of this far-field emission together with theoretical modeling enables us to establish the nature of the optical modes guided by the structure. We show that the dispersion of the modes supported by corrugated polymer films depends on the depth of modulation of the corrugation and find that if the periodic corrugation is strong enough photonic band gap effects may be induced. We also address the question of whether Bragg-scattering of the guided modes, including surface plasmon polariton modes, may increase the efficiency of the emission. We measure and compare the efficiency with which radiation is produced by planar and corrugated structures, finding the corrugated structures to be up to a factor of 2.6 more efficient. We indicate how our results may be used in the search for ways to improve the efficiency of devices based on light emitting thin films.

A new mixed acid sulphate K0.9Rb0.1HSO4 was synthesized at room temperature. It has been firstly characterised by X-ray diffraction (XRD) and vibrational spectroscopy investigations. Then, in order to detect phase transitions and watch changes in the conductivity behaviour, investigations by differential scanning calorimetry (DSC), (XRD), electrical conductivity measurements, and impedance spectroscopy were carried out. The XRD results on single crystals showed that at room temperature, K0.9Rb0.1HSO4 has an orthorhombic symmetry with space group Pbca. The unit cell parameters are: a = 8.39(6) Å; b = 9.79(8) Å and c = 18.98(5) Å. The Raman and infrared spectra at room temperature were also investigated. The structural similarity with KHSO${_4}$ has been confirmed. The thermal studies showed that K0.9Rb0.1HSO4 undergoes two structural phase transitions at about 400 K and 435 K. A partial substitution of K+ by Rb+ increases the conductivity even at room temperature. The transition at 435 K leads to a super-ionic conductor state at high temperatures related with rotational motions of HSO4− ions.

The crystallization processes of Zr70Cu20Rh10 and Zr70Cu27.5Rh2.5 metallic glasses were studied. The initial precipitates are the mixture of an icosahedral quasicrystalline phase (I phase) and a face centered cubic Zr2Rh phase (fcc-Zr2Rh) for Zr70Cu20Rh10 alloy and that for the Zr70Cu27.5Rh2.5 alloy is a single I phase. Under optimum annealing conditions, the largest I phase particle size is 40 nm and 80 nm for Zr70Cu20Rh10 and Zr70Cu27.5Rh2.5, respectively. To explain these results, it is assumed that icosahedral atomic cluster exists in the metallic glasses, which serves as the seeds for the precipitation of metastable I and FCC-Zr2Rh phases. Further, it is suggested that the number density of icosahedral atomic cluster and the ease of fcc-Zr2Rh phase formation depend on the Rh concentration, which explain the above-mentioned dependence of the I phase particle size on Rh concentration.

Silicon technology has become a good alternative to copper for the elaboration of efficient cooling devices required in power electronics domain. Owing to its high degree of miniaturization, it is expected to provide suitable microchannels and other inlets holes that were not achievable by copper micromachining. Besides, the use of silicon technology provides a variety of bare materials (silicon dioxide, silicon nitride, silicide, etc.) which may be either insulator or conductive, with a good or bad thermal conductivity. This large choice makes it possible to built up rather complex multilayer devices with mechanical properties good enough in comparison with hybrid copper technology heat sinks. Nevertheless, the use of silicon technology, where the microchannel width may reach few tens of microns, raises fundamental features concerning the fluid displacement within such small sections. More precisely, fundamental fluid mechanics studies have to be conducted out in order to get an accurate description of the fluid boundary layers and to provide basic data on the exchange mechanisms occurring at these surfaces. In this paper, we review the operation principles of both single- and double-phase heat exchange devices elaborated in silicon technology. Forced-convection heat sinks as well as integrated micro heat pipes are analyzed. An analytical approach is adopted to evaluate their total thermal resistances as a function of several geometrical parameters. Numerical simulations are then used in order to assess the accuracy of the analytical approach and to evaluate the impact of the fluidic aspects on the whole performance. The optimum devices are then conceived thanks to an appropriate optimization procedure taken into account the several experimental constraints. Reference values of similar copper devices are reminded and the advantages of the silicon integrated approach are highlighted.

The functions of the plasma flow such as electrical conductivity, thermal conduction and chemical reaction can be enhanced by seeding vaporized alkali metal with low ionization potential. In the present study, numerical simulation is conducted for the radio frequency inductively coupled plasma of which functions are enhanced by seeding a small amount of vaporized alkali metal. The effects of seeding, injection flow rate and applied coil frequency on the plasma characteristics are clarified by relating to the flow structure and electromagnetic effect.

This paper is devoted to polystyrene thin film treatment under DC pulsed discharges in nitrogen, oxygen and oxygen-argon mixtures. XPS analysis is used in order to investigate the new chemical bonds generated by the reactive particles colliding the surface from the plasma. The experimental conditions are close to the best running conditions deduced from [16,75,86]. Correlations between microscopic analyses obtained by XPS through the knowledge of the surface chemical composition and macroscopic ones realized by studies of water drop deposited on the films (contact angle measurements) are presented. It is pointed out that the wettability is highly improved when the percentage of oxygen atoms incorporated in polystyrene surface reaches a high value. C − O, C = O and O − C = O are the main chemical bonds and it is found that the oxygen uptake happens during a very short time (about one second for the treatment duration time, i.e. about 10 ms on account of the duty factor value). A high oxygen rate is observed, correlated to the formation of a maximum $\Delta \theta/\theta_i$ plateau value (wettability). Reaction processes in the plasma bulk and on the polystyrene surface are proposed, taking into account the bond energies of polystyrene. As a consequence, the polystyrene treatment is interpreted assuming two steps for the reaction processes: in a first step, chemical bonds are broken by energy transfer from reactive particles to the surface and in a second step, new chemical bonds are generated. In this spirit, the main reactive plasma particles are described and surface reactions are proposed on the polystyrene surface.