Wang C.H.,Nan Jeon University of Science and Technology
Advanced Materials Research | Year: 2011
Extending the investigations on (Bi0.5Na0.5)TiO 3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Bi0.5Na 0.5)TiO3-(Bi0.5K0.5)TiO3 [BNT-BKT]. (Bi0.5Na0.5)TiO3 with 7∼30 mol% (Bi0.5K0.5)TiO3 ceramics have been prepared following the conventional mixed oxide process. A morphotropic phase boundary (MPB) between rhombohedral (R) and tetragonal (T) was found at the composition 0.82BNT-0.18BKT with correspondingly enhanced piezoelectric properties. The electromechanical planar coupling factor is higher for compositions near the MPB. The mechanical quality factor (Qm), planar coupling coefficient (kp) and thickness coupling coefficient (kt) of 0.82BNT-0.18BKT ceramics were 125, 28.8% and 47.4%, respectively. © (2011) Trans Tech Publications.
Wang C.-H.,Nan Jeon University of Science and Technology
Advanced Materials Research | Year: 2011
Extending the investigations on (Bi0.5Na0.5)TiO 3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Bi0.5Na 0.5)TiO3-Ba(Sn, Ti)O3. X-ray diffraction analysis revealed that, during sintering, all of the Ba(Sn, Ti)O3 diffuses into the lattice of (Bi0.5Na0.5)TiO3 to form a solid solution, in which a rhombohedral phase with a perovskite structure was found. It was found that the samples with a low content of Ba(Sn0.06Ti0.94)O3 exhibit relatively good physical and electric properties. For 0.98(Bi0.5Na 0.5)TiO3-0.02Ba(Sn0.06Ti0.94)O 3 ceramics, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.16 and 0.57, respectively, at the sintering of 1100oC for 3 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 3.56. For 0.98(Bi0.5Na0.5)TiO3-0.02Ba(Sn 0.06Ti0.94)O3 ceramics, the relative density and the thickness coupling coefficient kt reach 98.1% and 0.58, respectively, at the sintering of 1100°C for 5 h. With suitable Ba(Sn xTi1-x)O3 concentration and sintering condition, a dense microstructure and good electrical properties were obtained.
Huang Y.-K.,Nan Jeon University of Science and Technology |
Chen P.,National Tsing Hua University |
Kao Y.-J.,National Taiwan University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012
We apply the biorthonormal transfer-matrix renormalization group (BTMRG) to study low-temperature properties of quantum spin chains. Simulations on anisotropic Heisenberg spin-1/2 chains demonstrate that the BTMRG outperforms the conventional transfer-matrix renormalization group by successfully accessing far lower temperature than previously reported, while retaining the same level of accuracy. The power of the method is further illustrated by the calculation of the low-temperature specific heat for a frustrated spin chain. © 2012 American Physical Society.
Wang J.-B.,Nan Jeon University of Science and Technology |
Yau H.-T.,National Chung Cheng University
International Journal of Advanced Manufacturing Technology | Year: 2014
It is complex and divergent for the conventional motion controllers to process various G codes using different interpolation algorithms. This impairs programming efficiency and robustness of the controller. In this paper, we propose the universal non-uniform rational B-splines (NURBS)-based interpolator which can simplify the architecture of interpolation in spite of interpreting different kinds of inputs. Direct conversion of long G01 and G02/G03 numerical control (NC) segments to NURBS segment is first implemented. The fitting of multiple short segments into a continuous and smooth NURBS segment is then carried out. More importantly, the universal NURBS-based interpolator utilizes the Cox-de Boor algorithm which is highly efficient and can take advantage of the parallel computing scheme to accelerate the processing speed. Furthermore, due to the construction of real-time environment, the proposed algorithm enables interpretation, look-ahead functions, and motion control to work simultaneously. A 2D NC program possessing hundreds of short G01 segments and long segments (i.e., G02, G03, and long G01) is tested on an in-house developed XY-table with a PC-based motion controller. The results have shown the effectiveness and feasibility of the proposed real-time NURBS-based interpolator. © 2013 Springer-Verlag London.
Chen K.-H.,Nan Jeon University of Science and Technology |
Su C.-T.,National Yunlin University of Science and Technology
Expert Systems with Applications | Year: 2010
This paper proposes modified particle swarm optimization to solve the problem of activity assignment of fourth party logistics (4PL) with preemptive structure. In practice, decision makers must consider goals of different importance when they encounter 4PL decision problems. Previous studies have adopted weighted fuzzy goal programming to design optimization problems. However, it is difficult for decision makers to determine proper weights. This paper proposes a decision making method based on preemptive fuzzy goal programming and a modified PSO. The proposed method does not require weights, and prevents results without feasible solutions caused by improper resource setting. Furthermore, this paper proposes a modified PSO with mutation operator extension. Numerical analysis shows that proposed modified PSOs prevent algorithms from caving prematurely into local optimums. © 2009 Elsevier Ltd. All rights reserved.