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Nakhon Ratchasima, Thailand

Patton R.,University of Hull | Chen L.,University of Hull | Klinkhieo S.,Synchrotron Light Research Institute SLRI
International Journal of Applied Mathematics and Computer Science | Year: 2012

The concept of combining robust fault estimation within a controller system to achieve active Fault Tolerant Control (FTC) has been the subject of considerable interest in the recent literature. The current study is motivated by the need to develop model-based FTC schemes for systems that have no unique equilibria and are therefore difficult to linearise. Linear Parameter Varying (LPV) strategies are well suited to model-based control and fault estimation for such systems. This contribution involves pole-placement within suitable LMI regions, guaranteeing both stability and performance of a multi-fault LPV estimator employed within an FTC structure. The proposed design strategy is illustrated using a nonlinear two-link manipulator system with friction forces acting simultaneously at each joint. The friction forces, regarded as a special case of actuator faults, are estimated and their effect is compensated within a polytope controller system, yielding a robust form of active FTC that is easy to apply to real robot systems. Source

Wongpanya P.,Suranaree University of Technology | Wongpinij T.,Synchrotron Light Research Institute SLRI | Photongkam P.,Synchrotron Light Research Institute SLRI | Euaruksakul C.,Synchrotron Light Research Institute SLRI | Witit-Anun N.,Burapha University
Materialpruefung/Materials Testing | Year: 2015

TiAlN films with thicknesses of 250, 500 and 750 nm were deposited on 4140 steel using the reactive direct current co-unbalanced magnetron sputtering method. The effects of the film thickness on the microstructure were revealed using a field emission scanning electron microscope, an image analyzer and X-ray diffraction. The results showed that grain size apparently increased when the film was at greater thicknesses whereas porosity, lattice strain and dislocation density decreased. Meanwhile, the results of anodic polarization tests in air-saturated 3.5 wt.-% NaCl solution at pH levels of 2, 7 and 10 and at 25°C showed lower corrosion potential in thicker film, attributed to a lower ratio of grain boundary area to individual grain area. However, a more stable passive film with higher pitting potential was formed. By analyzing using X-ray absorption spectromicroscopy, oxidation of Ti into TiO2 was found on the corroded surface of TiAlN film. © Carl Hanser Verlag, München. Source

Kempet W.,Suranaree University of Technology | Kempet W.,Synchrotron Light Research Institute SLRI | Marungsri B.,Suranaree University of Technology | Yimnirun R.,Suranaree University of Technology | And 6 more authors.
Ferroelectrics | Year: 2016

Lead zirconate titanate (PZT) ceramics have been extensively used for electronic applications due to their ability to couple mechanical and electrical energy, a so-called piezoelectric effect. This effect is caused by the shift of Ti4+ or Zr4+ ion relative to neighbouring atoms. The movement of the ions due to an external load causes reorientation of the ferroelectric polarization. Microscopically, the detail of the shift of Ti ion, reflecting polarization switching behaviour, can be analyzed by X-ray absorption near-edge structure (XANES) technique. The aim of this project is to investigate the shift of Ti4+ ion in PZT under the application of electric field by in-situ X-ray absorption technique. For this project, the special custom-built high voltage sample chamber installed at synchrotron XANES beam line at Synchrotron Light Research Institute, Thailand, was employed to conduct the experiment. XANES spectrum of bulk PZT was collected under the different amplitudes of an applied electric field. Ti K-edge X-ray absorption spectra were analyzed by IFEFFIT software package. The results showed that the pattern of XANES changed with the alternation of the applied field amplitude. The change of XANES spectrum was caused by the movement of Ti4+ ion reflecting the change of ferroelectric polarization. From the analysis, it was found that this technique could be used to investigate the Ti4+ ion shifting of PZT bulk ceramics. © 2016 Taylor & Francis Group, LLC. Source

Galbraith S.C.,Suranaree University of Technology | Flood A.E.,Suranaree University of Technology | Flood A.E.,Vidyasirimedhi Institute of Science and Technology | Rugmai S.,Synchrotron Light Research Institute SLRI | Chirawatkul P.,Synchrotron Light Research Institute SLRI
Chemical Engineering and Technology | Year: 2016

Potential mechanisms affecting growth rate dispersion (GRD) are investigated. Previous studies have identified surface roughness and internal lattice perfection as key mechanisms which are both evaluated with respect to GRD. Crystal growth of potassium dihydrogen phosphate was studied in two solvent mixtures, water and water-ethanol. The surface roughness was analyzed by atomic force microscopy and the internal crystal perfection by X-ray diffraction using a synchrotron source. The crystals grown at higher supersaturation have more pronounced and more frequent surface irregularities, supporting previous findings on a feedback mechanism between surface roughness and growth rate. No significant relationship was found between internal crystal perfection and growth rate, however, this is likely due to the size of the crystals analyzed herein and not the absence of any such mechanism in small crystals. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Tangcharoen T.,King Mongkuts University of Technology Thonburi | Tangcharoen T.,Synchrotron Light Research Institute SLRI | Ruangphanit A.,Thai Microelectronics Center | Klysubun W.,Synchrotron Light Research Institute SLRI | Pecharapa W.,King Mongkuts University of Technology Thonburi
Ferroelectrics | Year: 2013

In this work, nanocrystalline lead-free multiferroic composites of nickel zinc ferrite (Ni0.5Zn0.5Fe2O4) - potassium sodium niobate (K0.5Na0.5NbO3) were synthesized by a sol-gel combustion method. The influence of Ni 0.5Zn0.5Fe2O4 content, on the crystal structure, chemical bonding, morphologies, dielectric properties and magnetic behavior of K0.5Na0.5NbO3 was investigated using X-ray diffraction measurement, Raman spectroscopy, scanning electron microscope, LCR meter and vibrating sample magnetometer, respectively. The overall characterization results indicate that the various contents of ferrite and ferroelectric materials in those composites have a significant influence on their multiferroic properties. In addition, this method is proven as one of an ordinary, fast and efficacious way to synthesize functional multiferroic materials with simple availability implements. © 2013 Copyright Taylor and Francis Group, LLC. Source

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