The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform
Patrick S K Chua - One of the best experts on this subject based on the ideXlab platform.
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Adaptive wavelet transform for Vibration signal modelling and application in fault diagnosis of water hydraulic motor
Mechanical Systems and Signal Processing, 2006Co-Authors: H X Chen, Patrick S K ChuaAbstract:Abstract There has been an increasing application of water hydraulics in industries due to growing concern on the environmental, health and safety issues. The fault diagnosis of water hydraulic motor is important for improving water hydraulic system reliability and performance. In this paper, fault diagnosis of water hydraulic motor in water hydraulic system is investigated based on adaptive wavelet analysis. A novel method for modelling the Vibration signal based on the adaptive wavelet transform (AWT) is proposed. The linear combination of wavelets is introduced as wavelet itself and adapted for the particular Vibration signal, which goes beyond adapting parameters of a fixed-shape wavelet. The AWT procedure based on the parametric optimisation by genetic algorithm (GA) is developed. The model-based method by AWT is applied to extract the features in the fault diagnosis of the water hydraulic motor. This technique for de-noising the corrupted simulation signal shows that it can improve the signal-to-noise ratio of the Vibration signal. The results of the experimental signal demonstrate the Characteristic Vibration signal details in fine resolution. The magnitude plots of the continuous wavelet transform (CWT) show the Characteristic signal's energy in time and frequency domain which can be used as feature values for fault diagnosis of water hydraulic motor.
H X Chen - One of the best experts on this subject based on the ideXlab platform.
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Adaptive wavelet transform for Vibration signal modelling and application in fault diagnosis of water hydraulic motor
Mechanical Systems and Signal Processing, 2006Co-Authors: H X Chen, Patrick S K ChuaAbstract:Abstract There has been an increasing application of water hydraulics in industries due to growing concern on the environmental, health and safety issues. The fault diagnosis of water hydraulic motor is important for improving water hydraulic system reliability and performance. In this paper, fault diagnosis of water hydraulic motor in water hydraulic system is investigated based on adaptive wavelet analysis. A novel method for modelling the Vibration signal based on the adaptive wavelet transform (AWT) is proposed. The linear combination of wavelets is introduced as wavelet itself and adapted for the particular Vibration signal, which goes beyond adapting parameters of a fixed-shape wavelet. The AWT procedure based on the parametric optimisation by genetic algorithm (GA) is developed. The model-based method by AWT is applied to extract the features in the fault diagnosis of the water hydraulic motor. This technique for de-noising the corrupted simulation signal shows that it can improve the signal-to-noise ratio of the Vibration signal. The results of the experimental signal demonstrate the Characteristic Vibration signal details in fine resolution. The magnitude plots of the continuous wavelet transform (CWT) show the Characteristic signal's energy in time and frequency domain which can be used as feature values for fault diagnosis of water hydraulic motor.
Chung-han Chung - One of the best experts on this subject based on the ideXlab platform.
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Effect of different halide types on HMF synthesis from kudzu extract in ionic liquid
Journal of Cleaner Production, 2013Co-Authors: Jinwoo Lee, Chung-han ChungAbstract:Abstract An eco-beneficial strategy for the production of hydroxymethylfurfural (HMF) was developed using kudzu root extract as a sustainable biomass material and the physicochemical properties of the extract characterized using FESEM, XRD, and FT-IR. The visual image of the kudzu extract and the XRD analysis revealed that the molecular structure of the extract is amorphous and its major composition would be starch. The FT-IR analysis showed 6 Characteristic Vibration modes contributing to starch and other sugars. The halide ligands of different types significantly affected the synthesis of HMF. The exceptional promotion effect on HMF synthesis was achieved by fluorine ligand of the chromium-based metal catalyst. The most effective stoichiometry ratio of catalyst-to-feed biomass for the synthesis of HMF from kudzu root extract was found at its ratio value of 0.2. The most optimal extraction condition for HMF synthesis from the kudzu extract occurred at 0.3 M HCl. The highest HMF production (34.8 ± 4.8 dwt%) was obtained in the reaction mixture containing 40% (w/v) ionic liquid, 10% (v/v) ethyl acetate, 1% (w/v) halide catalyst, and 50% (v/v) of 0.3 M HCl extract by undergoing the reaction at 130 °C for 12 h.
Wissam A. Saidi - One of the best experts on this subject based on the ideXlab platform.
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Effects of topological defects and diatom vacancies on Characteristic Vibration modes and Raman intensities of zigzag single-walled carbon nanotubes.
The journal of physical chemistry. A, 2013Co-Authors: Wissam A. SaidiAbstract:Defects are ubiquitous in carbon nanotubes (CNTs), despite their large formation energies, and have astounding effects on their physicochemical properties. In this study, we employ density-functional theory (DFT) calculations to study systematically the atomic structure, stability, and Characteristic Vibrations of pristine and defected zigzag CNTs, where the defects are of the form of Stone-Wales (SW) and diatom vacancies (DV). The DFT optimized structures and the phonon modes are subsequently used in conjunction with a semiempirical bond-polarization model to study the nonresonant Raman spectra. For each defect type, we find two CNT structures with defects parallel or oblique to the tube axis. For the SW defects, the two structures have similar formation energies, whereas for the DV defect, only defects parallel to the tube axis are likely to exist. The results show that the defects induce a blue shift in the radial breathing mode (RBM) of metallic CNTs, whereas this mode is not shifted for semiconducting CNTs. However, the RBM shift or its Raman profile is not sensitive to the defect type. The G-band showed more sensitivity to the defects in the form of a red/blue shift in the frequency, or a partial/complete defragmentation of the G bands.
P K Mitra - One of the best experts on this subject based on the ideXlab platform.
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thermal decomposition of precipitated low bulk density basic aluminium sulfate
Materials Chemistry and Physics, 2004Co-Authors: I N Bhattacharya, P K Gochhayat, P. S. Mukherjee, S Paul, P K MitraAbstract:Abstract Hydrated basic aluminium sulfates (BAS) are of great importance as precursor material for the preparation of activated and high pure calcined aluminas. Low bulk density category BAS powders have superior quality over higher bulk density varieties in terms of higher surface area, more active sites for adsorption, etc. A brief description on the processing route of low bulk density BAS powders utilizing aluminium sulfate and ammonia as hydrolyzing precipitant has been presented. Low Al 3+ concentration and pH of around 7–7.2 were found to be crucial for formation of such material. Characterization of this low bulk density material and its different calcined products was also carried out. The characterization was performed through XRD, FTIR and DTA studies. The XRD analysis indicated precipitated powder to be an amorphous material. Interestingly, this amorphous structure is retained till 800 °C. At 900 °C, η-Al 2 O 3 phase appears to be the only transitional phase during its transformation to α-Al 2 O 3 at 1100–1200 °C. FTIR study showed Characteristic Vibration modes related to molecular water, co-ordinated sulfate and AlO bonds.