Showing papers by "National Cheng Kung University published in 1981"
TL;DR: In this paper, the Laguerre operational matrices for the integration and differentiation of a Laguero vector whose elements are Lagueria polynomials are generalized to fractional calculus for investigating distributed systems.
Abstract: The Laguerre operational matrices for the integration and differentiation of a Laguerre vector whose elements are Laguerre polynomials are generalized to fractional calculus for investigating distributed systems. The generalized operational matrices corresponding to 8, 1/8, 8/√(82+1) and exp (−8/(8+1)) are derived as examples. Comparison of the Laguerre series approximate inversions of irrational Laplace transforms with exact solutions is very satisfactory.
76 citations
TL;DR: In this article, ammonium uranyl carbonate (AUC) compounds were identified by chemical analysis, DTA/TGA analysis, and by single crystal X-ray diffraction.
44 citations
TL;DR: In this article, an instant-local similarity method is proposed to analyze the unsteady state Graetz problems, where only large Graetz numbers (small normalized axial distance) are concerned and the normalized time from transient up to steady state is of order 10 −1 ; therefore, the instant local similarity approach gives results of high accuracy.
31 citations
TL;DR: In this article, a new method for growing GaAs thin films is studied, where high quality GaAs layers can be grown by low pressure metalorganic vapor phase epitaxy (MOVPE) by using triethylgallium (TEG) as Ga source.
30 citations
TL;DR: In this paper, an improved linearization method was proposed for determining the monomer reactivity ratios of free-radical copolymerizations by fitting the data of cumulative copolymers compositions and overall weight fractional conversions, or cumulative Copolymer compositions and residual monomer compositions of the reaction mixture.
Abstract: An improved linearization method is proposed for determining the monomer reactivity ratios of free-radical copolymerizations by fitting the data of cumulative copolymer compositions and overall weight fractional conversions, or cumulative copolymer compositions and residual monomer compositions of the reaction mixture. The reactivity ratios of monomers for four different copolymerization reactions are determined. The results are very close to those of literature reports and account well for the experimental results.
20 citations
TL;DR: In this paper, a time-of-flight technique was proposed to analyze the decay of long-lived metastable autoionizing states which are frequently populated by a sequence of cascades that incorporates optical and Auger transitions.
Abstract: Little is known experimentally and theoretically about cascade induced repopulation of multiply excited states with high orbital, spin, and angular momentum quantum numbers. Such states are often created with surprisingly large cross sections by the beam-foil or beam-gas interaction. Recent progress in beam-foil and beam-gas1,2 electron spectroscopy offers the possibility to study excitation and deexcitation mechanisms for highly excited ionic projectile states via the Auger decay. This time-of-flight technique allows to analyze the decay of long-lived metastable autoionizing states which are frequently populated by a sequence of cascades that incorporates optical and Auger transitions.
19 citations
TL;DR: In this paper, the electrical characteristics of some polymer thick film (PTF) resistors have been studied, which include the sheet resistivity, current noise indices (CNI), temperature coefficient of resistance (TCR), and the percentage variations of resistance.
Abstract: The electrical characteristics of some polymer thick film (PTF) resistors have been studied. There are four different kinds of carbon blacks and two different kinds of polymer resin, i.e., epoxy resin and polyimide resin, selected in the preparations of the PTF resistors. In this paper, the electrical characteristics, which include the sheet resistivity, current noise indices (CNI), temperature coefficient of resistance (TCR) and the percentage variations of resistance ( \Delta R/R, %), are discussed. It will be shown that there exists a correlation between the "structure" of the carbon blacks and the electrical characteristics of the PTF resistors. The effects of the blended carbon blacks on the electrical characteristics of the PTF resistors are also discussed.
19 citations
TL;DR: In this paper, a new combined time and frequency domain method for the model reduction of discrete systems in z-transfer function is presented, which preserves both frequency domain and time domain characteristics of the original systems.
Abstract: A new combined time and frequency domain method for the model reduction of discrete systems in z-transfer function is presented. First, the z-transfer functions are transformed into the w-domain by the bilinear transformation, z = (1+w)/(1−w). Then, four model reduction methods—Routh approximation, Hurwitz polynomial approxima- tion, stability equation, and retaining dominant poles—are used respectively to reduce the order of the denominator polynomials in the w-domain. Least squares estimate is then used to find the optimal coefficients in the numerator polynomials of the reduced models so that the unit step response errors are reduced to a minimum. The advantages of the proposed method are that both frequency domain and time domain characteristics of the original systems can be preserved in the reduced models, and the reduced models are always stable provided the original models are stable.
18 citations
TL;DR: In this paper, the performances of spherical catalysts with both decreasing and increasing activity profiles toward the center were analyzed for various types of reactions and the performance of those catalysts experiencing deactivation was also investigated.
Abstract: The performances of spherical catalysts with both decreasing and increasing activity profiles toward the center are analyzed for various types of reactions. The concentration distribution of metal ions within a spherical support, which is resulted by incomplete impregnation or complete impregnation followed by backwashing, is converted to the activity profile of the catalyst by using the relation of activity and ion concentration. Under steady state isothermal operation, these catalysts of nonuniform activity are compared theoretically with those of uniform activity based on their reaction rates and selectivities. The performances of those catalysts experiencing deactivation are also investigated.
15 citations
TL;DR: In this paper, the separation efficiency of concentric-tube thermal diffusion columns with viscous heat generation has been investigated under consideration of the curvature effect, and the results were obtained graphically and were compared with those obtained by Yeh and Cheng in which they neglected the curvatures effect.
Abstract: The separation efficiency of concentric-tube thermal diffusion columns with viscous heat generation has been investigated under consideration of the curvature effect. The results were obtained graphically and were compared with those obtained by Yeh and Cheng in which they neglected the curvature effect. Considerable improvement in separation was obtained by employing a rotary column instead of a stationary one.
14 citations
TL;DR: The magnetic anisotropy, isomer shift, and hyperfine field for the amorphous series Fe 84 B 16− x C x (0 ⩽ x ¼ 10) and Fe 84B 16−x ¼ x Si x (1 ¼ 4) have been measured by the Mossbauer spectroscopy as discussed by the authors.
TL;DR: In this paper, the conduction mechanism is discussed on the basis that the sheet resistivity is dependent on the average gap distance between carbon black conducting particles or chains and the effect of the "structure" of carbon blacks has also been incorporated.
Abstract: Phenomenologicai explanations of the electrical characteristics of the polymer thick film resistors [1] are given. The conduction mechanism is discussed on the basis that the sheet resistivity is dependent on the average gap distance between carbon black conducting particles or chains. The effect of the "structure'! of carbon blacks has also been incorporated. The dependencies of sheet resistivity on both the content of carbon blacks and the structure of carbon blacks have been studied. The current noise indices (CNI) of the polymer thick film (PTF) resistors have been explained, qualitatively, by the same model. The relationships between sheet resistivity and the CNI, and the resistor geometries on the CNI have been examined with the aid of a model of noise generators. The temperature coefficient of resistance and the percentage variations of resistance was studied on the basis of the thermal motion (Brownian) of the Carbon black particles and the thermal expansion of the polymer resins. The improved electrical characteristics of the PTF resistors, prepared with the blended carbon blacks, were also studied.
TL;DR: In this paper, the surface tension of oleic acid and dioctyl sebacate surfaces was measured using a modified Du Nouy tensiometer, and the surface excess and the standard free energies, enthalpies and entropies of adsorption were derived from the surface tensor data.
TL;DR: In this article, a qualitative kinetic study was carried out to see how the rate and the yield of this reaction depend on the relative amounts of maleic acid, ceric ion, and bromide ion.
Abstract: The presence of small amounts of ceric and bromide ions in the aqueous sulfuric acid solution of maleic acid can catalyze the isomerization of maleic acid to fumaric acid rapidly and quantitatively at room temperature. A qualitative kinetic study was carried out to see how the rate and the yield of this reaction depend on the relative amounts of maleic acid, ceric ion, and bromide ion. In general, the rate increases asymptotically to a limiting value as the concentration of maleic acid, ceric or bromide ion increases. Sulfuric acid has both the chemical and physical effects on the rate of isomerization. If the relative amounts of the reactants is in the order of [maleic acid]≥[Br−]≥[Ce(IV)], a very high yield up to 98% can easily be obtained. Sulfuric acid does not have major effect on the yield. A mechanism was proposed to rationalize the experimental results.
TL;DR: In this article, the absolute rate constants for the propagation and termination of free-radical polymerization were determined by the convenient kinetic data without need for photo-illumination technique.
Abstract: The absolute rate constants for the propagation and termination of free-radical polymerization were determined by the convenient kinetic data without need for photo-illumination technique. The extent of recombination reaction occurring in the termination reactions can be obtained using the same experimental data. The homopolymerizations of styrene and methyl methacrylate are illustrated. The results obtained by this method are close to those in the literature.
TL;DR: In this paper, the existence and regularity of solutions for Cauchy problems associated with the following two equations were investigated: (1) ut(x, t) = (−1)k + 1Δku(x and t) on infinite dimensional spaces.
TL;DR: In this paper, a mathematical model has been proposed for an isotopic exchange reaction between insoluble salt and ions in a solution of finite volume, where the exchange rate is controlled by combined film diffusion and surface mass action.
TL;DR: In this article, the first synthesis of sydnone derivatives having a carbon-oxygen bond at the 4 position of the Sydnone ring has been reported, and 4-sydnonyl tosylate was successfully prepared by anodic substitution reaction.
Abstract: As the first synthesis of sydnone derivatives having a carbon-oxygen bond at the 4-position of sydnone ring, 4-sydnonyl tosylate were successfully prepared by anodic substitution reaction.
TL;DR: In this article, the buoyancy effects on the laminar boundary layer heat transfer from vertically moving flat plate and cylinder are studied by a coordinate perturbation method for the cases of prescribed surface temperature and prescribed wall heat flux.
Abstract: The buoyancy effects on the laminar boundary layer heat transfer from vertically moving flat plate and cylinder are studied by a coordinate perturbation method for the cases of prescribed surface temperature and prescribed wall heat flux. Universal expressions are given to show the temperature distributions and the increase of heat transfer rate with the increase of the buoyancy force parameter.
TL;DR: In this paper, a general method to find the rate constant and particle self-diffusion coefficient is suggested for a heterogeneous isotopic exchange reaction which is controlled by surface mass reaction or controlled by a combination of surface reaction and intraparticle diffusion.
Abstract: A general method to find the rate constant and particle self-diffusion coefficient is suggested for a heterogeneous isotopic exchange reaction which is controlled by surface mass reaction or controlled by a combination of surface mass reaction and intraparticle diffusion. The values of the kinetic parameter, ξ1 (ratio of the forward surface mass reaction rate to the intraparticle diffusion rate), particle self-diffusion coefficient D and rate constant k are obtained by the proposed method for the isotopic exchange reaction systems CaCO3(s)/Ca2+(aq) and CaC2O4(s)/Ca2+(aq).
TL;DR: An RAPD structure is proposed in which the direction of radiation incidence causes photogeneration to precede avalanche multiplication reducing the multiplication noise substantially, which should be useful in the design of RAPD laser detectors.
Abstract: Wavelength and temperature-dependent characteristics of silicon reach-through avalanche photodiodes (RAPD) are studied using the modified Baraff’s theory. The temperature and wavelength regions discussed are 100–500 K and 0.655–1.06 μm, respectively, for Si photodetectors. The effects of breakdown voltage, depletion region width, and efficiency on the avalanche region width are widely studied. Both n+ (front) side and p+ (back) side illumination are also considered. The noise equivalent power is significantly reduced with light incident on the p+ surface with little sacrifice of efficiency. An RAPD structure is proposed in which the direction of radiation incidence causes photogeneration to precede avalanche multiplication reducing the multiplication noise substantially. This result should be useful in the design of RAPD laser detectors.