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Erbil, Iraq

Qadir R.W.,University of Malaya | Qadir R.W.,Physics Laboratory | Ahmad Z.,University of Malaya | Sulaiman K.,University of Malaya
Journal of Modern Optics | Year: 2014

We theoretically investigate the enhancement of optical absorption in organic thin films by embedding the periodic metallic nanostructures (NSs) inside the thin films. For the case study, one of the organic solar cell materials copper phthalocyanine (CuPc) has been used. Finite Different Time Domain technique has been used to illustrate the role of the several different shapes of the metallic NSs. It has been found that the NSs can result in broadband optical absorption enhancement. A study on the position of the metallic particles in the organic thin film and the effect of particle dimension on absorption has also been performed. A significant enhancement in the absorption in the wavelength range 350-550 nm has been observed. Furthermore, the investigation has been performed on the effect of the light source incident angle and polarization direction on the absorption in the organic thin films. The best incident angle is found at 75°. © 2014 Taylor & Francis.

Abry P.,CNRS Physics Laboratory | Roux S.G.,Physics Laboratory | Wendt H.,French National Center for Scientific Research | Messier P.,Western Washington University | And 7 more authors.
IEEE Signal Processing Magazine | Year: 2015

Texture characterization of photographic prints can provide scholars with valuable information regarding photographers? aesthetic intentions and working practices. Currently, texture assessment is strictly based on the visual acuity of a range of scholars associated with collecting institutions, such as museum curators and conservators. Natural interindividual discrepancies, intraindividual variability, and the large size of collections present a pressing need for computerized and automated solutions for the texture characterization and classification of photographic prints. In the this article, this challenging image processing task is addressed using an anisotropic multiscale representation of texture, the hyperbolic wavelet transform (HWT), from which robust multiscale features are constructed. Cepstral distances aimed at ensuring balanced multiscale contributions are computed between pairs of images. The resulting large-size affinity matrix is then clustered using spectral clustering, followed by a Ward linkage procedure. For proof of concept, these procedures are first applied to a reference data set of historic photographic papers that combine several levels of similarity and second to a large data set of culturally valuable photographic prints held by the Museum of Modern Art in New York. The characterization and clustering results are interpreted in collaboration with art scholars with an aim toward developing new modes of art historical research and humanities-based collaboration. © 1991-2012 IEEE.

Du X.,Soochow University of China | Du X.,Yanshan University | Tian H.,Physics Laboratory | Yao S.,Soochow University of China | And 3 more authors.
Physica B: Condensed Matter | Year: 2015

In this study, Cr3+-doped MgAl2O4 nanophosphors have been prepared via a facile high-temperature calcination route. The structure and morphology of the products were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques, which confirmed the typical spinel MgAl2O4 phase and sphere-like shape with particle size distribution of 50-80 nm. It was found that the Cr3+-doped MgAl2O4 can be efficiently excited by visible light and exhibits intense red emission peaking at 695 nm, corresponding to the 2Eg→4A2g transition of Cr3+ ions. The evolution of the luminescent properties on the Cr-doping concentration (0, 0.5, 1, 2, 3, 4 and 6 mol%) was then investigated and the optimal concentration was 3.0 mol%. It is believed that active intermediates and gases created in the calcining process play important roles not only on the formation of the monodispersed nanoparticles, but also on the homogeneous doping of Cr3+ at high concentration. © 2015 Elsevier B.V. All rights reserved.

Yu G.,China University of Mining and Technology | Cheng H.,China University of Mining and Technology | Li R.,China University of Mining and Technology | Chen H.,China University of Mining and Technology | And 2 more authors.
10th International Power and Energy Conference, IPEC 2012 | Year: 2012

Switched reluctance machine combines the electrical machine theories with power electronics technique and the microprocessor control technique, measurement technique. It has a lot of advantages, such as simple structure, strong structure, high efficiency, wide speed adjusting range, multivariable control. The paper introduces the theory and features of SRM, the composing of SRM drive system and research survey. The paper proves that fuzzy controller has the best effect. Finally, we tested and compared the different strategies on the hardware experiment system, and got the experimental waveforms. It validates that the control strategy is correct. And the SRM drive system has a good static and dynamic performance. © 2012 IEEE.

Zou J.,China University of Mining and Technology | Chen H.,China University of Mining and Technology | Huo Y.,Physics Laboratory
10th International Power and Energy Conference, IPEC 2012 | Year: 2012

This paper introduces the design mode of switched reluctance motor (SRM) control system. Using TMS320F28335 as the core chip, the control system board for DSP controlled SRM is designed. And based on the system board, the experiment system was established with a three-phase 12/8 structure low power SRM prototype as action element. Finally, the experimental results were given. © 2012 IEEE.

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