Formation Response of High Frequency Electromagnetic Waves

Core samples from rock formations respond to electromagnetic radiation based on an effective permittivity, which depends on the conductivity and permittivity of the constituent components of the rock, as well as the geometric structure of these constituents and the frequency of the radiation. This study analyzes the effect, for radiation of 1 to 100 Mhz, of discrete inclusions having a different permittivity from the surrounding medium. The focus is on the effect of certain geometric features, namely, the individual size of the inclusions, their overall volume fraction, the presence of sharp edges, and their aspect ratio. It is found that the volume fraction has the strongest impact on the effective permittivity, linear at first but higher order at higher volume fractions. The aspect ratio of the inclusions has a moderate effect, which is exaggerated in the extreme case of needle-like inclusions, and which can also be seen in a stronger nonlinearity. There is also a possibility that some features in the shape of the inclusion boundaries may influence the frequency dependence of the effective permittivity. Inclusion size and sharp edges have negligible effect

Reverse roll coating with a deformable roll operating at negative gaps

YesReverse roll coating is probably the most widely used coating operation, yet its full potential has not been exploited as it is shown in this paper which considers operation with a negative gap. We demonstrate through a wide range of experimental data that such operation can yield very thin and stable films with no ribbing or cascade instabilities when low viscosity fluids are used. Typically, stable film thickness less than 5μm can be obtained at speeds up to 150 m/min when a rubber roller is used at -100 μm gap with fluids of viscosity in the range 10-200 mPa.s. These film thicknesses can be made to decrease further down to 1 or 2 microns with a judicious choice of speed ratios (applicator to metering roller) and rubber hardness. Such new findings make this simple coating method an attractive roll to roll technique for application in the newer coating technologies, such as in the production of solar cells and plastic electronics. The data obtained in this study have been underpinned by a model based on the classical lubrication theory, well developed for such flow situations. Essentially it is shown that the film thickness non dimensionalised with respect to the set negative gap is controlled through a single parameter, the elasticity number Ne which combines all the operating parameters. Of course, this flow problem has complexities, particularly at high speed ratios and at zero gap so the data obtained here can serve as a basis for more comprehensive modelling of this classical fluid mechanic problem.Films R&D Centre of Toyobo Co. Ltd., Otsu, Japan and the Thin Films Research Group of the University of Bradford, UK

Analysis Techniques of Polymeric Encapsulant Materials for Photovoltaic Modules: Situation and Perspectives

AbstractThe properties of the encapsulant are critical to the long-term performance of photovoltaic (PV) modules under the influence of sunlight including UV, elevated temperature, humidity and diffusion of oxygen. Encapsulation process represents about 40% of the whole PV module cost. The introduction of new non-EVA encapsulant material type ″Low-Cost, High-Performance″ should provide a solution to outdoor yellowing degradation problems. The emerging encapsulant materials exhibit a good compatibility with emerging PV solar cells for long term durability. This new generation of encapsulant materials has the advantage to improve the PV module performances and long term durability for specific climate like desert regions. This scientific contribution presents an overview of the different encapsulant materials currently on the market, the general requirements of the emerging encapsulant materials and characterizations techniques for degradation, diagnostic and reliability lifetime estimation in the framework of Algerian renewable energy strategy

The effect of continuous pore stratification on the acoustic absorption in open cell foams

This work reports new data on the acoustical properties of open cell foam with pore stratification. The pore size distribution as a function of the sample depth is determined in the laboratory using methods of optical image analysis. It is shown that the pore size distribution in this class of materials changes gradually with the depth. It is also shown that the observed pore size distribution gradient is responsible for the air flow resistivity stratification, which is measured acoustically and non-acoustically. The acoustical absorption coefficient of the developed porous sample is measured using a standard laboratory method. A suitable theoretical model for the acoustical properties of porous media with pore size distribution is adopted. The measured data for open porosity, tortuosity, and standard deviation data are used together with this model to predict the observed acoustic absorption behavior of the developed material sample. The transfer matrix approach is used in the modeling process to account for the pore size stratification. This work suggests that it is possible to design and manufacture porous media with continuous pore size stratification, which can provide an improvement to conventional porous media with uniform pore size distribution in terms of the attained acoustic absorption coefficient

Sesquiterpenes from aerial parts of Ferula vesceritensis

From the dichloromethane extract of aerial parts of Ferula vesceritensis (Apiaceae), 11 sesquiterpene derivatives were isolated. Among them five were compounds designated as 10-hydroxylancerodiol-6-anisate, 2,10-diacetyl-8-hydroxyferutriol-6-anisate, 10-hydroxylancerodiol-6-benzoate, vesceritenone and epoxy-vesceritenol. The six known compounds were identified as feselol, farnesiferol A, lapidol, 2-acetyl-jaeschkeanadiol-6-anisate, lasidiol-10-anisate and 10-oxo-jaesckeanadiol-6-anisate. All the structures were determined by extensive spectroscopic studies including 1D and 2D NMR experiments and mass spectroscopy analysis. Two of the compounds, the sesquiterpene coumarins farnesiferol A and feselol, bound to the model recombinant nucleotide-binding site of an MDR-like efflux pump from the enteropathogenic protozoan Cryptosporidium parvum

Ozone generation in a wire-to-cylinder corona discharge ozonizer fed with mixtures of O2 and N2

The generation of ozone in a coaxial wire-cylinder corona discharge reactor has been experimentally investigated using variable proportions (5% to 90%) of oxygen in nitrogen. The experiments have been carried out under negative polarity and using different gas flow rates (50 cm3/min to 200 cm3/min). The obtained results show that the corona current exhibits a certain dependence with the percentage of oxygen in the gas mixture, which may influence the rate of ozone production. Moreover, the evaluation of the ozone yield has revealed a non-linear dependence of this magnitude with the concentration of oxygen. The maximum ozone yield was obtained when the percentage of oxygen in the gas mixture was about 70%