Papers by Keyword: Spectroscopy

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Authors: Yu Liu, Zhen Tao Wang, Zhen Dong Tan, Hong Xiang Tian
Abstract: The faults of the machines appeared suddenly usually cause to huge losing. So it’s important to monitor and analyze the condition of the machines. Now, more and more methods have been applied to condition monitoring and fault diagnoses. The spectral analysis technique has been widely used to detect the contents of abrasive metal in the lubricating oil. To mine the spectral data better, a method was put forward, which can be used to build the healthy record and reveal the important information about the operated conditions of the equipment. In the method, the similar information of the principal component in oil was obtained in the stable abrasion of the different friction pairs of equipment. The composition of mechanical and electrical equipment was also gained. The healthy record was created preliminarily according to all the information. In the malfunction detection of the equipment, cooperated with the data of the threshold of oil, the analysis results of spectra can be compared with the healthy record. So, the abnormal abrasion can be judged accurately.
Authors: Ghulam Shabbir, Asghari Maqsood, Izhar-ul-Haq
Abstract: Micro-Brillouin light scattering experiments were performed on flux grown D-type (monoclinic, P21/c) Ho2Si2O7 single crystal from room temperature to 850 K. Both the hypersonic velocity (VLA) and related elastic constant (c33) of the longitudinal acoustic phonons propagating along 001-direction showed a small dispersion at T565 K whereas the same could not be observed clearly in attenuation/damping. The overall temperature dependent behavior of elastic constant and hypersonic velocity was attributed to the lattice anharmonicity of the crystal in the investigated temperature range.
Authors: Yoshiaki Kiyanagi, Takashi Kamiyama, Toshiyuki Nagata, F. Hiraga
Abstract: Neutron imaging using a pulsed neutron time-of-flight method can give an energy dependent transmission image, namely, spectroscopic image. This image includes the structure information if the sample is coherent scatterer. Here, two examples are introduced. First, we obtained the transmission image of a welded sample of SS304 and 308. Change of the crystal structure depending on the position was observed. Furthermore, we measured spatial dependent transmission of SS samples treated in different ways, surface treatment and whole body treatment. There were almost no spatial dependent change, but the cross section change was found between surface and whole body treatment samples. It was suggested that this might be due to the difference of a grain size. These results demonstrated that the spectroscopic imaging using a pulsed neutron source is a useful tool for material characterization.
Authors: Ying Lan Jiang, Ruo Yu Zhang, Jie Yu, Wan Chao Hu, Zhang Tao Yin
Abstract: Agricultural products quality which included intrinsic attribute and extrinsic characteristic, closely related to the health of consumer and the exported cost. Now, imaging (machine vision) and spectrum are two main nondestructive inspection technologies to be applied. Hyperspectral imaging, a new emerging technology developed for detecting quality of the food and agricultural products in recent years, combined techniques of conventional imaging and spectroscopy to obtain both spatial and spectral information from an objective simultaneously. This paper compared the advantage and disadvantage of imaging, spectrum and hyperspectral imaging technique, and provided a description to basic principle, feature of hyperspectral imaging system and calibration of hyperspectral reflectance images. In addition, the recent advances for the application of hyperspectral imaging to agricultural products quality inspection were reviewed in other countries and China.
Authors: Vikram Srinivas, Vasanthakumari Raju
Abstract: Magnetite nanoparticle with average size 7-10 nm was embedded with biocompatible polyvinyl alcohol nanofiber and the average diameter of nanofiber is 115 nm. The nanofiber was further assembled over polymeric mesh to analyse the release mechanism of nanoparticles from polymer nanofiber. A hydrodynamics setup was constructed to study this system. Prior to hydrodynamics the nanofiber was allowed to react with water in static mode and observed that the magnetite nanoparticles were released from the nanofiber with increase in time. UV-Visible Spectrophotometer is used for analysis of absorbance and transmittance of polyvinyl alcohol-magnetite nanoparticles solution, nanofiber and films. High-resolution scanning electron microscopy is used to analyze the dimension of nanofiber; High-resolution transmission electron microscopy is used to find the size of magnetite nanoparticles. Here, an online spectroscopic technique was used to study the release mechanism of nanoparticles from nanofibers samples of different layers during hydrodynamics. The results reveal that the quantity of magnetite nanoparticles can be controlled by embedding into nanofibers during hydrodynamics. Also, the spectroscopic results indicate the quantity of nanoparticles released from nanofiber. This mechanism can be utilized to control the required quantity of nanoparticles to release at particular location through a polymer mesh assembly.
Authors: Masanobu Yoshikawa, Masataka Murakami, Takaya Fujita, K. Inoue, K. Matsuda, H. Ishida, Hiroshi Harima
Abstract: We have measured cathodoluminescence (CL) spectra in the vicinity of V-defects in InGaN single-quantum-well(SQW) films at nanometer level, using newly developed CL apparatus (SE-SEM-CL). From spectroscopic CL measurement, it has been found that the spectra change dramatically in the vicinity of V-defects in the region of £50nm. The SE-SEM-CL has a potential to detect the CL spectral variation at spatial resolution with £50nm.
Authors: Peter B.S. Bailey, S.A. Hayes, R.J. Hand, B. Zhang
Abstract: The results of an initial investigation into the monitoring of water absorption and chemical degradation in epoxy matrix composites using evanescent wave spectroscopy are presented. While conventional silica glasses have too low a refractive index and too short an IR transmission window to be useful as unclad sensing elements in most resin systems, chalcogenide glasses offer suitable refractive indices and infrared transmission windows. Arsenic selenide compositions with gallium or tellurium additions were initially investigated as they have been successfully demonstrated in other fibre sensing applications. However their glass transition point lies near or below the curing temperature for many commercial epoxy resins and thus germanium-antimony-lead sulphide glasses were also investigated as they display higher glass transition temperatures. The fibres were embedded in a representative matrix resin by casting samples of epoxy resin around sections of fibre. The end faces were prepared to allow an infrared beam to be passed along the fibre and the samples were subjected to hygrothermal aging. Changes in the transmitted spectra were observed, and photoelasticity was used to monitor the occurrence of fibre fragmentation. Both the arsenic selenide based compositions and the germanium-antimony-lead sulphide compositions displayed minimal bonding with the epoxy resin, so a simple silane treatment was used to improve adhesion.
Authors: M. Bojinov, G. Fabricius, J. Ihonen, T. Laitinen, J. Piippo, Kimmo Saarinen, G. Sundholm
Authors: Li Hong Zhao, Hong Jun Sun
Abstract: The physico-chemical characterization of two types of alkali lignin from different origin, namely L1 and L2, were studied by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectrometry (1H NMR) and gel permeation chromatography (GPC) analysis. FT-IR spectra show that they have the characteristics of absorption peaks of syringyl and guaiacyl. 1H NMR spectra indicate that acetylated L1 exhibits higher content of aromatic protons than L2, as the former is mainly composed by G units. L2 presents high quantities of methoxyl groups. GPC results show that L1 has much higher weight average than L2. They had similar functional groups, however, there were differences in the relative contents of functional groups.
Authors: Jun Juan Zhao, Xian Hui Li, Wei Zhang, Zhan Zhao
Abstract: This paper presents method and performance of the Helmholtz photoacoustic resonant cell and its remodified one which both were designed and tested respectively based on the measurement of the CO2 contribution of the photoacoustic signal in experiments. The average optical power at the laser operating point was 800mW for the10.653um laser (CO2 detection). On-line and real time measurement CO2/N2 mixtures (CO2 300ppm) were then performed. The Helmholtz photoacoustic resonant cell and its remodified one test of the carbodioxide conducted at their respective resonant frequency demonstrated signals about 43mV and 67mV, signal-to-noise (S/N) values about 47dB and 51dB respectively. According to test results, the remodified one also has a better quality factor. All this demonstrate the remodified Helmholtz cell can preferably improve excitation of acoustical signal.
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