Papers by Keyword: Optical

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Authors: Dong Hwan Kim, Yong Ri Piao, Sung Jin Cho, Seok Tae Kim
Abstract: A new 3D image encryption method using integral imaging technology and maximum length cellular automata (MLCA) is proposed in this paper. First, an elemental image (EI) is generated by the integral imaging pickup process. The Wolfram rule is then selected and the state transition matrix, T, is created by MLCA. A random number matrix (RNM) is generated according to the MLCA rule. The generated EI and RNM are compared and pixel values are transitioned. Finally, a basis image is generated by another MLCA rule. The basis image is applied by performing a logic bit exclusive-OR (XOR) operation on the final encrypted image. This method changes the basic image information. Using pixel values to visualize image data gives better encryption results than the previous method. The robustness of the encryption method for lost data, including added noise or cropping attacks, was analyzed and the results of encryption method safety test experiments are presented using histograms.
Authors: J. Valentin, M.A. Weber, R. Brodmann, A. Sharp
Abstract: The measurement and evaluation of sheet metal surface characteristics is of increasing importance, due to the significant functional impact on finishing processes like forming and varnishing. For a comprehensive and useful description of textured topographies including nonstatistical characteristics, a simple profile evaluation based on 2D roughness parameters is no longer sufficient. The introduction of area-imaging white light confocal microscopy offers, in contrast to tactile profiling methods of comparable accuracy, the clear advantage of contact-free and extremely fast 3D data capture. The capabilities and benefits of this technology in interaction with sophisticated 3D area analysis methods are demonstrated by measurement examples of sheet metal and roller surfaces. A newly-developed mobile confocal measurement system for direct roller measurements is introduced.
Authors: Ying Jian Chen
Abstract: In this paper,we first discuss the main distinct advantages of MEMS as well as the important differences between MEMS and IC,then some latest research progresses on biomedical, optical and automotive applications of MEMS are briefly reviewed. Finally,possible future developments of MEMS are prospected.
Authors: Yu Long Zhang, Xian Peng Zhang, Rui Qin Tan, Ye Yang, Jun Hua Zhao, Wei Yan Wang, Ping Cui, Wei Jie Song
Abstract: Pristine and Al-doped zinc oxide nanopowders were synthesized via a surfactant-assisted complex sol-gel method, possessing a pure ZnO phase structure and controllable grain size which was characterized by X-ray diffraction and scanning electron microscopy. Using these nanopowders, the pristine and Al-doped ZnO magnetron sputtering targets were prepared following a mold-press, cold isostatical-press and schedule sintering temperature procedure. The relative density of these as-prepared targets was tested by Archimedes’ method on densitometer. All of the results were above 95 theory density percents, and the resistivity was tested on four-probe system at a magnitude of 10-2 Ω cm. Related pristine ZnO thin films and Al-doped ZnO thin films were fabricated by magnetron sputtering method, respectively. The pristine and Al-doped ZnO films deposited on the quartz glass by dc sputtering owned a (002) orientation with a thickness of 350 nm at a deposition power of 100 W for two hours under an argon plasma. A good optical transparency above 80% and low resistivity of 1.60×10-3 Ω cm were obtained with a deposition temperature of 573 K. The optical energy bandgap could be tailored by Al doping at 4 at.% Al.
Authors: P. Popper
Authors: T. Gurunathan
Abstract: Stainless steels are regularly used as one of the preferred material of construction in the pressure vessels and heat exchangers manufactured by welding for process plants and energy sector at BHEL, Tiruchirappalli. They are considered mainly because of their corrosion resistance and high temperature suitability. But the practising welding engineers have to face innumerable challenges with stainless steel with regard to defects minimization, distortion control and dimensional stability on large and complex assemblies. Use of Nickel based filler wires or development of welding procedures simulating the true configuration of the product and by conducting specific tests and NDE are followed for weld defects control. Sequence welding, development of special fixtures, etc have come as handy options for welding distortion control of SS. Innovative inspection techniques for the certification of dimensions including geometrical tolerances especially on large constructions using SS welding and evolution of special Helium leak testing procedures for certain in-process checks in critical products are inevitable in the SS fabrication industry as a part of Quality Assurance programme. As a pioneer in SS fabrication, some of our challenging experiences pertaining to these three areas are discussed in this paper.
Authors: Yotsakit Ruangtaweep, Nattapon Srisittipokakun, Kitipun Boonin, Patarawagee Yasaka, Jakrapong Kaewkhao
Abstract: The recycling of rice straw fly ash (RSA) obtained from the biomass power plants has been studied. RSA was calcined at 400, 600, 800 and 1,000 °C for 3 h and investigated their compositions and structures by X-rays fluorescence spectrometer (XRF) and X-rays diffractometer (XRD) respectively. The results show that, the major compositions of RSA are SiO2 and CaO, MgO, K2O and P2O5. The XRD patterns exhibited the peak of sylvite potassium chloride phase (KCl) up to 600 °C. Since 800 °C tridymite phase SiO2 was obtained and the KCl phase was disappeared. The glasses from RSA (RSA-glass) were prepared by melt-quenched technique and investigated their optical and physical properties, compared with the glass prepared from high purity SiO2 (SiO2-glass) using the same glass formula and preparation conditions. The density and refractive index of the RSA-glass were higher than SiO2-glasses. Similar optical absorption spectra of both glasses were obtained. In addition the shoulder peak were appeared at 450 nm due to Fe3+ ion from contamination in RSA.
Authors: C.M. Mahajan, A.G. Godbole, S.P. Gumfekar, S.H. Sonawane, M.G. Takwale
Abstract: Nanocrystalline undoped and Al doped ZnO thin films were synthesized by the chemical spray pyrolysis of Zinc acetate and Aluminium chloride solution. The optoelectronic properties of undoped and Al:ZnO films were investigated. The XRD patterns of films were preferably oriented along c-axis [0 0 2] plane with the hexagonal wurtzite structure. The Al-doping caused no additional X-ray diffraction peaks when compared with XRD of undoped film, indicating Al2O3 content was below the detection limit. The crystallite size of undoped and Al doped film was 48 nm and 51nm respectively, as measured from X-ray diffractogram. The films are of high optical transmittance (≥ 90%). The resistivity of the film was found to decrease because of Al doping. The dark resistivity measurement for Al:ZnO film was of the order of 10-3 Ω-1cm-1. The band gap energy of the film was found to vary from 3.25 to 3.32eV indicating the Moss Burstein shift. Al:ZnO films can be used as transparent conducting oxide layers for photovoltaic applications.
Authors: Guang Xing Liang, Ping Fan, Zhuang Hao Zheng, Jing Ting Luo, Dong Ping Zhang, Jing Rong Chi, Chao Ming Chen, Jun Zhao
Abstract: Cu (In, Ga)Se2 (CIGS) thin film was prepared by ion beam sputtering Cu, In, Se and evaporating Ga elements continuously on BK7 glass substrate and the 4-layer film was then annealed at 400 oC for 1h in the same vacuum chamber. The CIGS thin film is single-phase with chalcopyrite structure and has a preferential (112) orientation. Its elemental composition approaches the stochiometric composition ratio of 1:0.7:0.3:2 and it consists of densely packed grain clusters. An energy band gap of about 1.30 eV and an absorption coefficient of 105 cm-1 are obtained. Thus, an optimization of the fabrication for CIGS thin films was achieved.
Authors: S. Gopinath, S. Barathan, R. Rajasekaran
Abstract: Abstract: The thiourea is an interesting inorganic matrix modifier. Recently, researchers are focusing on growing metal complexes of thiourea crystals. Some of the examples are bis thiourea zinc chloride (BTZC) , tetrakis thiourea potassium iodide (TTPI) , tetra thiourea potassium iodide (TTPI) , tetra thiourea cobalt chloride (TTCoC) , bis thiourea cadmium chloride (BTCC) etc., G.Anand et al , S.Gopinath et al and M.Mariappan et al have reported the growth and characterization of metal complexes of urea thiourea. This paper aims to compare the optical , mechanical and thermal properties of these crystals.
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