Coronal loop detection from solar images

In this paper, we make an overview of a methodology for the automatic retrieval of images with coronal loops from the solar image data captured by the extreme-ultraviolet imaging telescope (EIT) onboard the spacecraft SOHO (Solar and Heliospheric Observatory). Our image retrieval system provides relevant data to astrophysicists who need such data to study the coronal heating problem. As part of building this system, we investigated various image preprocessing techniques, image based features, and classifiers to automatically detect coronal loops and to indicate their locations on the images. Despite many challenges related to the coronal loop characteristic, we obtained promising results, namely, 78% precision and 80% recall in loop retrieval.     

Preparation and characterization of zeolite beta–polyurethane composite membranes

Incorporation of zeolite into polyurethane (PU) membranes was investigated by using as‐synthesized and calcined zeolite beta particles at two different loading contents (0.1 and 1 wt %). The chemical interaction between the zeolite beta crystals and PU was observed by ATR‐FTIR spectroscopy. The SEM results suggested that the calcined zeolite beta crystals were more homogeneously dispersed in the composite membranes than the as‐synthesized zeolite beta crystals. DMA results demonstrated that all composite membranes had higher storage modulus in the rubbery state and higher stability towards thermal and mechanical degradation with respect to the control groups. Tensile testing results also showed increased tensile strength and elongation at break for all composite membranes. This study suggests that incorporating zeolite beta in its as‐synthesized or calcined forms and at different amounts can be applied as an alternative method for tailoring the mechanical properties of PU membranes without changing its structural characteristics. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Preparation and characterization of sulfonated polysulfone/titanium dioxide composite membranes for proton exchange membrane fuel cells

In the present study, sulfonated polysulfone (sPS)/titanium dioxide (TiO₂) composite membranes for use in proton exchange membrane fuel cells (PEMFCs) were investigated. Polysulfone (PS) was sulfonated with trimethylsilyl chlorosulfonate in 1,2 dichloroethane at ambient temperatures. It was shown that the degree of sulfonation is increased with the molar ratio of the sulfonating agent to PS repeat unit. The degree of sulfonation was determined by elemental analysis and ¹H NMR was performed to verify the sulfonation reaction on the PS. Sulfonation levels from 15 to 40% were easily achieved by varying the content of the sulfonating agent. Composite membranes were prepared by blending TiO₂ with sPS solution in DMAC (5 wt.%) by the solution casting procedure. The membranes have been characterized by thermal analysis, water uptake, proton conductivity measurements and single cell performance. The addition of TiO₂ increased the thermal stability but high filler concentrations decreased the miscibility of the composite component, and resulted in brittle membranes. The conductivity values in the range of 10⁻³–10⁻² S/cm were obtained for composite membranes. The conductivities of the membranes show similar increasing trend as a function of operating temperature. The membranes were tested in a single cell operating at 60–85 °C in humidified H₂/O₂. Single fuel cell tests performed at different operating temperatures indicated that sPS/TiO₂ composite membrane is more hydrodynamically stable and also performed better than sPS membranes. The highest performance of 300 mA/cm² was obtained for sPS/TiO₂ membrane at 0.6 V for an H₂–O₂/PEMFC working at 1 atm and 85 °C. The results show that sPS/TiO₂ is a promising membrane material for possible use in proton exchange membrane fuel cells.     

Conducting polymer composites: Polypyrrole and poly(vinyl chloride-vinyl acetate) copolymer

Composites of a polypyrrole (PPy) and poly(vinyl chloride-vinyl acetate) copolymer (PVC-PVA) were prepared both chemically and electrochemically. An insulating polymer was retained in the blend and the thermal stability of the polymer was enhanced by polymerizing pyrrole into the host matrix in both cases. The composites prepared electrochemically gave the best results in terms of conductivity and air stability. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 667–671, 1997     

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