Showing papers by "National Cheng Kung University published in 1989"
TL;DR: The complete electrode model, which includes the effects of discretization of the current pattern, the shunt effect due to the highly conductive electrode material, and the effect of an effective contact impedance, allows calculation of the voltages due to any current pattern applied to a homogeneous resistivity field.
Abstract: A mathematical model for the physical properties of electrodes suitable for use in electric current computed tomography is discussed. The model includes the effects of discretization, shunt, and contact impedance. The complete model was validated by experiment. Bath resistivities of 284.0, 139.7, 62.3, and 29.5 Omega -cm were studied. Values of effective contact impedance used in the numerical approximations were 58.0, 35.0, 15.0, and 7.5 Omega -cm/sup 2/, respectively. Agreement between the calculated and experimentally measured values was excellent throughout the range of bath conductivities studied. It is desirable in electrical impedance imaging systems to model the observed voltages to the same precision as they are measured in order to be able to make the highest-resolution reconstructions of the internal conductivity that the measurement precision allows. The complete electrode model, which includes the effects of discretization of the current pattern, the shunt effect due to the highly conductive electrode material, and the effect of an effective contact impedance, allows calculation of the voltages due to any current pattern applied to a homogeneous resistivity field. >
591 citations
TL;DR: There are sexual and age differences in respiratory muscle strength and pulmonary function and that smoking or physical activity may affect respiratory muscle function.
Abstract: To investigate the effects of gender and age on respiratory muscle function, 160 healthy volunteers (80 males, 80 females) were divided into four age groups. Twenty-eight of the male subjects were smokers. After the subjects were familiarized with the experimental procedure, respiratory muscle strength, inspiratory muscle endurance, and spirometric function, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, tidal volume, breathing rate, and duty cycle, were measured. The respiratory muscle strength was indicated by the maximal static inspiratory and expiratory pressures (PImmax and PEmmax). Inspiratory muscle endurance was determined by the time the subject was able to sustain breathing against an inspiratory pressure load on a modified Nickerson-Keens device. The results showed that 1) except for inspiratory muscle endurance and FEV1/FVC, men had greater respiratory muscle and pulmonary functions than women, 2) respiratory muscle function and pulmonary function decreased with age, 3) smoking tended to lower duty cycle and FEV1/FVC and to enhance PE,mmax, and 4) inspiratory muscle endurance was greater in men who were physically active than in those who were sedentary. Therefore we conclude that there are sexual and age differences in respiratory muscle strength and pulmonary function and that smoking or physical activity may affect respiratory muscle function.
180 citations
TL;DR: It is concluded that inspiratory muscle endurance may deteriorate after a 30-h sleep loss, and the respiratory muscle strength, FEV1, and FVC were unaltered.
Abstract: Sleep loss is common in patients with respiratory disorders. To determine whether sleep loss affects respiratory muscle function, we compared respiratory muscle and pulmonary functions after normal sleep with those measured after a 30-h sleepless period in 30 normal male subjects. The respiratory muscle strength was estimated by the maximal static inspiratory and expiratory pressures. Inspiratory muscle endurance was determined by the product of pressure load and the sustained time, i.e., pressure-time index, while the subject breathed against an inspiratory pressure load on a modified Nickerson-Keens device. We found that inspiratory muscle endurance was decremented from 871 ± 61 to 638 ± 69 cm H2O·min after sleep deprivation. Twelve-second maximal voluntary ventilation was also significantly reduced after sleep loss. Nevertheless, the respiratory muscle strength, FEV1 and FVC were unaltered. We therefore conclude that inspiratory muscle endurance may deteriorate after a 30-h sleep loss.
132 citations
TL;DR: In this article, the authors derived generalized forms of capture area, acceleration, and homing time duration that are derived provide insight into the performance of the guidance laws being considered and lead to the discovery of new ones.
Abstract: The concept of a generalized guidance law is presented, and the closed-form solution for a homing missile pursuing a maneuvering target according to generalized guidance laws is given. It is shown that the guidance laws appearing in the literature are merely special cases of the one proposed by the authors. The derived generalized forms of capture area, missile acceleration, and homing time duration that are derived provide insight into the performance of the guidance laws being considered and lead to the discovery of new ones. The problem of finding a nonlinear optimal guidance law for a homing missile with controlled acceleration, applied so as to capture a maneuvering target with a predetermined trajectory while minimizing a weighted linear combination of time of capture and energy expenditures, is solved in closed form. The derived optimal control law is equal to the LOS (line of sight) rate multiplied by a trigonometric function of the aspect angle. Numerical simulation shows that the resulting guidance law appears to yield a significant advantage over true proportional navigation. >
99 citations
TL;DR: In this article, the authors presented a solution for the two-dimensional elliptic inclusion problem with general anisotropic elastic materials using the Stroh formalism and derived new identities which relate Stroh's complex eigenvalues and eigenvectors to real quantities obtainable directly from the elastic constants.
Abstract: The two-dimensional elliptic inclusion problems have been widely studied and many important results have been obtained. Solutions for which the inclusion as well as the matrix are of general anisotropic elastic materials are presented in this paper using the Stroh formalism. New identities which relate Stroh's complex eigenvalues and eigenvectors to real quantities obtainable directly from the elastic constants are derived, through which several solutions are expressed in real form. The special cases in which inclusion is rigid or a void are also studied
89 citations
TL;DR: In this article, an electron-gun evaporation and proper annealing in ambient oxygen gas was used to produce an SnO 2 thin film with fine particles and good structure, thus providing a sensor with high sensitivity and selectivity in detecting ethanol gas.
80 citations
TL;DR: In this paper, the degradation of thermal barrier coatings (TBCs) was investigated under different operating conditions within the temperature range 1000° to 1150°C and it was shown that oxidation of bond coatings is the dominant TBC degradation mechanism whereas the operationally induced stresses exert a conjugate effect.
Abstract: Duplex ZrO2–8 wt% Y2O3/Ni-22Cr-10Al-1Y thermal barrier coatings (TBCs) on Mar-M247 superalloy were tested under different operating conditions within the temperature range 1000° to 1150°C. Results of experiments in this study show that oxidation of bond coatings is the dominant TBC degradation mechanism whereas the operationally induced stresses exert a conjugate effect. The mechanisms of sintering and phase transformation of top coatings do not contribute to failure of TBCs within the temperature range studied. NiO and Ni(Cr,Al)2O4 grown on the surfaces of the bond coatings seem to accelerate spalling of the top coatings along a top coating/bond coating out-grown oxide interface. However, it is also concluded that the lifetime of TBCs is not directly related to a critical specific weight gain under thermal cycling conditions.
79 citations
TL;DR: In this article, the authors presented numerical solutions for steady laminar two-dimensional natural convection in concentric and eccentric horizontal cylindrical annuli with constant heat flux on the inner wall and a specified isothermal temperature on the outer wall.
69 citations
TL;DR: At an appropriately selected cutoff level, amylase can be effectively used as the first-line test and isoamylase or lipase as adjunct tests for acute abdominal conditions.
Abstract: We evaluated the diagnostic value of serum amylase, isoamylase, and lipase for the diagnosis of acute pancreatitis from sera of patients with acute abdominal pain. Comparison was first made in condition A between 32 patients with image-proven pancreatitis and 414 patients with nonpancreatic acute abdomen (the control group), then in condition B, between 62 pancreatitis patients with or without image proof and the control group. We found (a) that patients with image-proven pancreatitis suffer a more severe clinical course than those without; (b) that the sensitivity, positive predictive value, and accuracy in condition B are higher than in condition A at any cutoff level; (c) that none of the enzyme assays is specific at the upper reference limit, but their diagnostic yields are much improved by raising cutoff levels to about three or four times the upper limit; and (d) that at these selected cutoff levels, amylase had a diagnostic value similar to p-isoamylase or lipase in both conditions (sensitivity 84% and 92% for amylase in conditions A and B, respectively; specificity 98% and 98%; positive predictive value 75% and 90%; negative predictive value 99% and 99%; accuracy 91% and 97%). In conclusion, at an appropriately selected cutoff level, amylase can be effectively used as the first-line test and isoamylase or lipase as adjunct tests for acute abdominal conditions.
62 citations
TL;DR: In this paper, a twenty-node hexahedron element is employed in each layer for the displacement field, and the equilibrium equation is enforced by the variational principle, which is derived from the Hellinger-Reissner principle.
Abstract: The variational principle of this element can be derived from the Hellinger-Reissner principle through dividing six stress components into a flexural part (σ x , σ y , τ xy , σ z ) and a transverse shear part (τ xy , τ yz ). The element stiffness matrix can be formulated by assuming a stress field only for transverse shear stresses, while all the others are obtained from an assumed displacement field. A twenty-node hexahedron element is employed in each layer for the displacement field. The equilibrium equation is enforced by the variational principle
58 citations
TL;DR: In this article, the authors applied the finite element method to study the effect of moisture and temperature on the stability of a general orthotropic cylindrical composite shell panel subjected to axial or in-plane shear loading.
TL;DR: In this paper, the problem of transient free convection in a porous medium adjacent to a vertical semi-infinite flat plate with a simultaneous step change in wall temperature and wall concentration is investigated.
TL;DR: In this article, the authors conducted thermal cyclic tests of ZrO28.5Y duplex thermal barrier coatings (TBCs) from room temperature to 1000, 1025, 1050, 1075 and 1100°C. Failure analyses of all spalled specimens were carried out to elucidate the degradation mechanism of TBCs.
20 Aug 1989
TL;DR: A (1, m, n, T) dynamic threshold scheme based on the definition of cross- product in an N-dimensional linear space is proposed to illustrate the characterizations of the dynamic threshold schemes.
Abstract: This paper investigates the characterizations of threshold /ramp schemes which give rise to the time-dependent threshold schemes. These schemes are called the "dynamic threshold schemes" as compared to the conventional time-independent threshold scheme. In a (d, m, n, T) dynamic threshold scheme, there are n secret shadows and a public shadow, Pj, at time t=tj, l?tj?T. After knowing any m shadows, m?n, and the public shadow, pj, we can easily recover d master keys, K1j, K2j..., and Kdj. Furthermore, if the d master keys have to be changed to Kj+1/1 KJ+1/2..., and Kj+1/d for some security reasons, only the public shadow, pj, has to be changed to pj+1. All the n secret shadows issued initially remain unchanged. Compared to the conventional threshold/ramp schemes, at least one of the previous issued n shadows need to be changed whenever the master keys need to be updated for security reasons. A (1, m, n, T) dynamic threshold scheme based on the definition of cross- product in an N-dimensional linear space is proposed to illustrate the characterizations of the dynamic threshold schemes.
TL;DR: In this paper, new relaxation and gradient methods are proposed to handle this non-convex constraint, and the results of numerical experiments and error analysis are presented, which are used for the classification of stable defect structures and the description of the transitions that occur under the influence of electric and magnetic fields.
TL;DR: The inhibitory effect on thromboxane biosynthesis might explain the inhibitedory effect of procyanidins on platelet aggregation.
Abstract: The effects of procyanidins on platelet aggregation and arachidonate metabolism in platelets were studied Nine procyanidins were used in this investigation Procyanidins B-2-S, EEC and C-1 significantly induced the inhibition of platelet aggregation, and the potency of inhibition was comparable with aspirin Procyanidin B-2-S was used as a representative of procyanidins for further studies on the effect on arachidonate metabolism In arachidonate metabolism by fatty acid cyclooxygenase pathway, B-2-S inhibited TXB2 and HHT formation by intact platelets treated with exogenous arachidonic acid It also inhibited TXB2 formation measured by a specific radioimmunoassay when the cells were challenged with calcium ionophore A23187 In cell-free system, B-2-S inhibited both TXB2 and 12-HETE bioxynthesis in platelet microsome and cytosol, respectively The inhibitory effect on thromboxane biosynthesis might explain the inhibitory effect of procyanidins on platelet aggregation
TL;DR: In this article, the crystallization behavior of the electroless Ni-P deposit was investigated in detail with the aid of SEM, TEM, XRD, and electron diffraction techniques.
Abstract: The crystallization behavior of the electroless Ni‐P deposit was investigated in detail with the aid of SEM, TEM, XRD, and electron diffraction techniques. The as‐deposited film was shown to exhibit amorphous structure with XRD (x‐ray diffraction) and electron diffraction. The XRD and EDAX results show that heat‐treatment at temperatures above 300°C gives rise to Ni and phases. The fcc Ni and tetragonal grains of the film heated at 800°C are identified with electron diffraction. The occurrence of the maximum hardness achieved upon heating of the electroless Ni‐P plating is explained in terms of crystallization, grain coarsening, and defect change. The grain coarsening is also responsible for the random distribution of the phosphorus content across the deposit at temperatures above 600°C.
TL;DR: In this article, a study has been conducted to analyze the heat transfer characteristics of non-Newtonian power law fluids on the free convective flow over a vertical flat plate, including the inertia force in the momentum equation with a finite Prandtl number.
Abstract: A study has been conducted to analyze the heat transfer characteristics of non-Newtonian power law fluids on the free convective flow over a vertical flat plate. The analysis includes the inertia force in the momentum equation with a finite Prandtl number. In general, it has been found that the average heat transfer increases with increasing Prandtl number.
TL;DR: In this article, the i-phi hysteresis characteristic of a transformer is modeled and simulated by a curve-fitting technique, including a consuming function for representing hystresis loss.
Abstract: The i- phi hysteresis characteristic of a transformer is modeled and simulated by a curve-fitting technique, including a consuming function for representing hysteresis loss. The method is established on the basis of measured hysteresis data and allows direct calculation of hysteresis losses. The analytical expression also exhibits the property of increasing the loop area with increment of operating frequency. The simulation results are compared with experiments, and good agreement is shown. The approach can be adapted to determine an accurate transformer hysteresis characteristic by a simplified procedure. >
TL;DR: In this paper, differential thermal analysis and thermogravimetric analysis were employed to investigate the thermal decomposition, and an X-ray diffractometer and a transmission electron microscope were used to analyze the phases and crystalline states.
Abstract: Several experiments have been conducted to investigate the preparation of barium titanyl oxalate tetrahydrate (BTO). Differential thermal analysis and thermogravimetric analysis were employed to investigate the thermal decomposition, and an X-ray diffractometer and a transmission electron microscope were used to analyze the phases and crystalline states. It has been found that BTO is a nonstoichiometric compound, in which barium hydrogen oxalate hydrate was inserted by the titanium species. Moreover, it has been shown that a mixture would from rather than BTO, depending on pH, mixing order, and oxalate solution.
TL;DR: In this article, the operational characteristics, efficiency of treatment of landfill leachate, and recovery of energy in a laboratory scale hybrid bioreactor were investigated, which was a continuous upflow system combining a sludge bed and a filter and was operated at 35°C.
TL;DR: It is concluded that, for patients with severe wounds and evidence of V. vulnificus infection, an appropriate, powerful antibiotic, such as one of the third generation cephalosporins should be used as initial therapy unless the nature of the infection indicates other treatment.
Abstract: We report 3 cases of Vibrio vulnificus infections from Taiwan. Patient 1, who manifested symptoms of primary septicemia, died after 2 days. Patient 2, who had a wound infection and signs and symptoms of sepsis but negative blood cultures, responded to tobramycin and chloramphenicol plus surgical debridement, and recovered after 26 days of hospitalization. Patient 3 had secondary septicemia originating from a wound inflicted by a shrimp. Originally, the patient seemed to respond to ceftazidime and amikacin treatment along with surgical debridement, but subsequently died from adult respiratory distress syndrome (ARDS) induced by several episodes of aspiration which occurred after initial clinical improvements. We conclude that, for patients with severe wounds and evidence of V. vulnificus infection, an appropriate, powerful antibiotic, such as one of the third generation cephalosporins should be used as initial therapy unless the nature of the infection indicates other treatment.
TL;DR: In this paper, a methodology to generate six-bar planar linkage mechanisms with one degree of freedom in dead-center positions is presented, based on the concept of instant centers, which can also be applied to generate planar toggle linkage mechanisms.
Abstract: In dead-center positions, a mechanism loses its mobility and has zero mechanical advantage. Based on the concept of instant centers, we develop a methodology to generate planar linkage mechanisms in dead-center positions. This methodology also can be applied to generate planar toggle linkage mechanisms. All possible configurations of six-bar planar linkage mechanisms, with one degree of freedom, in dead-center positions are listed.
TL;DR: A generalized method is presented for analyzing the fringe patterns frequently encountered in experimental mechanics and a set of menu-driven software is developed for interactively implementing the fringe processing.
Abstract: A generalized method is presented for analyzing the fringe patterns frequently encountered in experimental mechanics By utilizing digital-image-processing and computer-graphics techniques, a set of menu-driven software is developed for interactively implementing the fringe processing Tests of this software on the images obtained experimentally by photoelasticity, holographic interferometry and speckle interferometry demonstrate its usefulness Good agreement between the experimental and theoretical results is established
TL;DR: In this article, the thermal postbuckling behavior of composite laminated plates subjected to a non-uniform temperature field is investigated by the finite element method, based on the principle of minimum potential energy, the nonlinear stiffness matrix and geometry matrix are derived.
TL;DR: In this paper, the thermal buckling behavior of laminated plates subjected to a nonuniform temperature field is investigated by the finite-element method, and the stiffness matrix, geometry matrix, and load vector are derived based on the principle of minimum potential energy.
Abstract: The thermal buckling behavior of laminated plates subjected to a nonuniform temperature field is investigated by the finite-element method. Being nonuniformly distributed over the plate, the thermal stresses should be determined before solving the buckling problem. The stiffness matrix, geometry matrix, and load vector are derived based on the principle of minimum potential energy. The assumed displacement state over the middle surface of the plate element is expressed as the products of one-dimensional, first-order Hermite polynomials. Numerical results show that the thermal buckling strength of a clamped plate is higher than that of a simply supported plate, and the influence of lamination angle, plate aspect ratio, and modulus ratio on thermal buckling are found to be significant for laminated plates.
TL;DR: The results showed that the inspiratory muscle endurance was greater in the midluteal phase than in the follicular phase, whereas the respiratory muscle strength and pulmonary function were unchanged.
Abstract: To investigate the effect of the menstrual cycle on respiratory muscle function, respiratory muscle and pulmonary functions were measured and compared in the midfollicular phase and in the midluteal phase of the menstrual cycle in 30 healthy adult women. Respiratory muscle strength was indicated by maximal static inspiratory and expiratory pressures. Inspiratory muscle endurance was determined by the product of pressure load and the sustained time, i.e., pressure-time index, while the subject breathed against an inspiratory pressure load on a modified Nickerson-Keens device. The results showed that the inspiratory muscle endurance was greater in the midluteal phase than in the follicular phase (815 +/- 43 versus 649 +/- 62 cmH2O.min, respectively), whereas the respiratory muscle strength and pulmonary function were unchanged. We conclude that inspiratory muscle endurance is affected by the menstrual cycle, i.e., higher in the midluteal phase and lower in the midfollicular phase.
TL;DR: In this paper, a real-time calculation method is presented to determine the optimal reactive power compensator for power systems, which is expressed as both the continuous control scheme and the discrete control scheme.
Abstract: A real-time calculation method is presented to determine the optimal reactive power compensator for power systems. The reactive power compensators are expressed as both the continuous control scheme and the discrete control scheme. The optimization problem is written in terms of the minimization of power line loss by minimizing the line currents. Three-phase current balancing is also considered in this problem. By an integerization method, suboptimal solutions are approached for utilizing the discrete-tap compensators. Theoretical derivations and computation procedures are formulated by including digital techniques for real-time data acquisition. Applications to radial-type systems are described and discussed. Examples of real-time simulations and experiments are discussed to show the performance of the method and to support the application capability. >
TL;DR: Etude experimentale en soufflerie. as mentioned in this paper Mesure des distributions de pression, des profils de couche limite and des proprietes aerodynamiques correspondantes pour divers angles d'attaque par anemometrie a fil chaud and visualisation au fil de fumee
Abstract: Etude experimentale en soufflerie. Mesure des distributions de pression, des profils de couche limite et des proprietes aerodynamiques correspondantes pour divers angles d'attaque par anemometrie a fil chaud et visualisation au fil de fumee
TL;DR: In this article, a theory of generalized functions is established on an arbitrary abstract Wiener space and it is shown that it provides a nice framework for reformulating white noise calculus initiated by T. Hida.