Browsing by Author "Luo, WC"

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NMR study of hetero-association accompanying self-association of 2-hydroxyl-4-methyl-pyridine and 2-pyrrolidone in acetonitrile
(2000-12-01)
Luo, WC
;
Lin, CC
;
Lin, JA
;
Kao, DY
;
Chen, JS
This work investigated not only the equilibrium of self-association of 2-pyrrolidone (A) and that of 2-hydroxyl-4-methyl-pyridine (B), but also the hetero-association between A and B in [H-2(3)]acetonitrile through hydrogen bonding using high-resolution nuclear magnetic resonance spectroscopy. Dilution shift data for the protons of the NW group of A and OH group of B were measured over a wide range of temperatures and concentrations. In addition, the monomer shifts, dimer shifts and dimerization constants of self-association and hetero-association were evaluated using a graphic method operating on the dilution chemical shift data. The enthalpy and entropy of dimerization of self-association and hetero-association were also obtained from the van't Hoff plot.
NMR study of hydrogen bonding association of 2-isopropylphenol in carbon tetrachloride, acetone, dimethyl sulphoxide and acetonitrile
(2001)
Luo, WC
;
Lay, JL
;
Chen, JS
;
應用化學系
;
Department of Applied Chemistry
This study investigates the association of 2-isopropylphenol through hydrogen bonding in carbon tetrachloride, [H-2(6)]acetone, [H-2(3)]acetonitrile and [H-2(6)]dimethyl sulphoxide by using high resolution nuclear magnetic resonance spectroscopy. Chemical shifts of the hydroxyl proton were measured over a wide range of temperature and concentration. The chemical shift data were treated by a graphical method to determine the monomer shift, dimer shift and dimerization constant. The enthalpy and entropy of dimerization were determined via a van't Hoff plot from the temperature variation of the dimerization constant.
NMR study of hydrogen bonding association of some sterically hindered alcohols in carbon tetrachloride, chloroform and cyclohexane
(2002)
Luo, WC
;
Lay, JL
;
Chen, JS
;
應用化學系
;
Department of Applied Chemistry
The self-association (dimerization) due to hydrogen bonding for some alcohols with bulky side chains was investigated by nuclear magnetic resonance spectroscopy. The systems studied include 2,4-dimethyl-3-pentanol or 3-methyl-3-pentanol in [H-2(12)]cyclohexane, carbon tetrachloride or [H-2(1)]chloroform, and 2,3,4-trimethyl-3-pentanol in carbon tetrachloride. The dilution shift data of hydroxyl proton were measured and employed to deduce the monomer shift, dimer shift and dimerization constant with the help of a graphic method. Use of van't Hoff plot for dimerization constants thus obtained at different temperature gave the enthalpy and entropy of dimerization. Also discussed herein is the effect of substituent hindrance and dielectric constant of solvent on the self-association.
NMR study of self-association of acetanilide in chloroform, acetone, acetonitrile and dimethyl sulphoxide
(2001)
Luo, WC
;
Chen, JS
;
應用化學系
;
Department of Applied Chemistry
The self-association of acetanilide through hydrogen bonding between N-H and O=C in the solvents [H-2(1)]chloroform, [H-2(6)]acetone, [H-2(3)]acetonitrile and [H-2(6)]dimethyl sulphoxide is investigated by high resolution nuclear magnetic resonance spectroscopy. Dilution shift data for the protons of the N-H group were measured over a wide range of temperature and concentration. The monomer shift, dimer shift and dimerization constant were determined by a graphical method operating on the dilution chemical shift data. The enthalpy and entropy of dimerization were also obtained from the van't Hoff plot.
Selection of optimal learning rates in CMAC based control schemes
(2002)
Luo, WC
;
Song, KT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
CMAC based control schemes have been studied by many researchers. It is well recognized that properly designed CMAC controllers provide useful and practical tools for precision control of non-linear systems. For complex trajectories, however, the convergence speed of CMAC can be slow because the CMAC module takes much time in learning the inverse dynamics of the plant. Therefore, one practical difficulty of CMAC based controller design is the selection of appropriate learning rate. In this paper, we present a method for selection of optimal CMAC learning rate. Furthermore, we demonstrate that the proposed GA-based approach to parameter selection can provide a global optimal solution. Computer simulation results confirm the effectiveness of the proposed method.