Showing papers by "Dalian University of Technology published in 2001"
TL;DR: Based upon the Riccati equation, a new generalized transformation is presented and applied to solve Whitham-Broer-Kaup (WBK) equation in shallow water as mentioned in this paper.
335 citations
TL;DR: In this article, a more powerful method to seek exact travelling wave solutions of nonlinear partial differential equations is presented, which uses the good ideas of the extended-tanh function method and our previous method.
284 citations
TL;DR: In this paper, a robust iterative learning controller for batch injection molding control is presented, where a sufficient and necessary condition to ensure BIBO stability is derived for the optimal ILC when tracking arbitrary bounded output reference.
174 citations
TL;DR: The anti-obesity effects of teasaponin in high-fat diet-treated mice may be partly mediated through delaying the intestinal absorption of dietary fat by inhibiting pancreatic lipase activity.
Abstract: OBJECTIVE: Based on the inhibitory effects of teasaponin on pancreatic lipase activity in vitro, this study was performed to clarify whether teasaponin prevented obesity induced in mice by a high-fat diet for 11 weeks DESIGN: For in vitro experiments, assay for the inhibitory effects of teasaponin on pancreatic lipase activity was performed by measuring the rate of release of oleic acid from triolein in an assay system using triolein emulsified with lecithin, gum arabic, Triton X-100 or 4-methylumbelliferyloleate For in vivo experiments, female ICR mice were fed a high-fat diet with or without 05% teasaponin for 11 weeks RESULTS: Teasaponin competitively inhibited the hydrolysis of triolein emulsified with lecithin, gum arabic, Triton X-100 or 4-methylumbelliferyloleate Teasaponin inhibited the elevations of plasma triacylglycerol levels 3, 4 and 5 h after oral administration of lipid emulsion containing corn oil Teasaponin suppressed the increases in body, parametrial adipose tissue weights and diameter in adipose cell size induced by a high-fat diet Furthermore, feeding a high-fat diet plus teasaponin had no effect on stool frequency and content, but significantly increased triacylglycerol contents in feces as compared to feeding a high-fat diet CONCLUSIONS: The anti-obesity effects of teasaponin in high-fat diet-treated mice may be partly mediated through delaying the intestinal absorption of dietary fat by inhibiting pancreatic lipase activity
158 citations
TL;DR: A unified theoretical treatment is given of longitudinal (or compressional) and transverse modes in Yukawa crystals, including the effects of damping, and Dispersion relations are obtained for hexagonal lattices in two dimensions and bcc and fcc lattice in three dimensions.
Abstract: A unified theoretical treatment is given of longitudinal (or compressional) and transverse modes in Yukawa crystals, including the effects of damping. Dispersion relations are obtained for hexagonal lattices in two dimensions and bcc and fcc lattices in three dimensions. Theoretical predictions are compared with two recent experiments.
156 citations
TL;DR: In this paper, three isomer chlorophenols, o -, m -, p -chlorophenol, were dechlorinated by palladium/iron powder in water through catalytic reduction.
140 citations
TL;DR: It is shown that under a natural hypothesis - called the uniform separation condition - the Ritz pairs (N,X) converge to the eigenpair (L,X), and certain refined Ritz vectors whose convergence is guaranteed, even when the uniformseparation condition is not satisfied.
Abstract: This paper concerns the Rayleigh- Ritz method for computing an approximation to an eigenspace X of a general matrix A from a subspace W that contains an approximation to X. The method produces a pair (N,X) that purports to approximate a pair (L,X), where X is a basis for X and AX = XL. In this paper we consider the convergence of (N,X) as the sine e of the angle between X and W approaches zero. It is shown that under a natural hypothesis - called the uniform separation condition - the Ritz pairs (N,X) converge to the eigenpair (L,X). When one is concerned with eigenvalues and eigenvectors, one can compute certain refined Ritz vectors whose convergence is guaranteed, even when the uniform separation condition is not satisfied. An attractive feature of the analysis is that it does not assume that A has distinct eigenvalues or is diagonalizable.
130 citations
15 Aug 2001
TL;DR: The calcium carbonate scale inhibition by two inhibitors, polyacrylic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid, has been studied in two heat transfer systems and it is found that PBTCA has a better inhibition effect than PAA under identical conditions.
Abstract: The calcium carbonate scale inhibition by two inhibitors, polyacrylic acid (PAA) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), has been studied in two heat transfer systems: recirculating cooling water and pool boiling systems. It is found that PBTCA has a better inhibition effect than PAA under identical conditions. The inhibition effect increases with increasing fluid velocity for the cooling water system, whereas in the presence of inhibitors, the fluid velocity has less effect on the scaling behavior. When the initial surface temperature increases, the inhibition efficiency decreases. In the presence of inhibitors, the scaling behavior is insensitive to the change of surface temperature. The relationship between the inhibition effect and the fractal dimension has also been investigated. The results show that the fractal dimension is higher in the presence of inhibitors. The better the inhibition effect, the higher the fractal dimension. XRD and FTIR analyses demonstrate that for the CaCO3 formed in the pool boiling system, the content of vaterite increases with the increase of inhibition effects. The metastable crystal forms of vaterite and aragonite are stabilized kinetically in the presence of inhibitors. The step morphology has been observed by atomic force microscopy. It is shown that the step space on the CaCO3 surface increases in the presence of inhibitors. Moreover, with the increase in inhibition effect, both the step space and the fractal dimension increase. Step bunching is also found and discussed in this paper. C ∞ 2001 Academic Press
124 citations
TL;DR: An accurate and highly efficient algorithm series for structural stationary/non-stationary random response analysis, pseudo excitation method (PEM) is presented in this paper, where the cross-correlation quadratic terms between the participant modes and between the excitations have both been included.
124 citations
TL;DR: In this paper, four pairs solutions of Whitham-Broer-Kaup (WBK) equations, which contain blow-up solutions and periodic solutions, are obtained by using of hyperbolic function method, Mathematica and Wu elimination method.
123 citations
TL;DR: The scaling of the reconnection electric field in a collisionless plasma is determined analytically for a model of forced reconnection and its dependence on the ion skin depth and the boundary conditions is calculated explicitly.
Abstract: The scaling of the reconnection electric field in a collisionless plasma is determined analytically for a model of forced reconnection. In particular, the dependence of the length of the reconnection layer on the ion skin depth and the boundary conditions is calculated explicitly. Analytical results are tested by Hall magnetohydrodynamics simulations.
TL;DR: In this article, a new band occurring at 874 cm −1 in IR spectra after 400°C is associated with the IR-active vibration states of graphitic structure.
TL;DR: In this article, a new approach for the solution of singular problems caused by stress and local buckling constraints is proposed, where a second order smooth-extended technique is used to make the disjoint feasible domains connect, then the so-called e-relaxed method is applied to eliminate the singular optima from problem formulation.
Abstract: The present paper investigates problems of truss topology optimization under local buckling constraints. A new approach for the solution of singular problems caused by stress and local buckling constraints is proposed. At first, a second order smooth-extended technique is used to make the disjoint feasible domains connect, then the so-called e-relaxed method is applied to eliminate the singular optima from problem formulation. By means of this approach, the singular optimum of the original problem caused by stress and local buckling constraints can be searched approximately by employing the algorithms developed for sizing optimization problems with high accuracy. Therefore, the numerical problem resulting from stress and local buckling constraints can be solved in an elegant way. The applications of the proposed approach and its effectiveness are illustrated with several numerical examples.
TL;DR: In this article, the authors present a rich class of exact solutions that contain radiation-dominated and matter-dominated models for the early and late universe, which are compatible with extensions of general relativity to string and membrane theory.
Abstract: We present a rich class of exact solutions that contains radiation-dominated and matter-dominated models for the early and late universe. They include a variable cosmological "constant" that is derived from a higher dimension and manifests itself in spacetime as an energy density for the vacuum. This is in agreement with observational data and is compatible with extensions of general relativity to string and membrane theory. Our solutions are also typified by a nonsingular "big bounce" (as opposed to a singular big bang), where matter is created as in inflationary cosmology.
TL;DR: The corrosion resistance of the gammaN-phase layer was studied by the electrochemical cyclic polarization measurement in Ringer's solutions buffered to pH from 3.5 to 7.5, and the corroded surface morphologies of the GammaN- phase layers observed by scanning electron microscopy are consistent with the results of the Electrochemical polarization measurement.
TL;DR: In this paper, the preparation, electrical and surface characterization of Cu doped tin dioxide thin-films for highly selective integrated gas sensor devices was reported, and a highly selective sensor device for CO and H 2 gas was fabricated.
Abstract: This paper reports on the preparation, electrical and surface characterization of Cu doped tin dioxide thin-films for highly selective integrated gas sensor devices. The 3000 A thin-film of 0.16 wt.% copper doped tin dioxide was deposited by reactive R.F. sputtering at room temperature and followed by 10 A Pt on top of Cu doped tin dioxide thin-film (SnO 2 –Cu/Pt). In another batch, the 100 A SiO 2 thin-film was deposited on top of the SnO 2 –Cu/Pt thin-film structure (SnO 2 –Cu/Pt/SiO 2 ). The electrical response of these thin-films was investigated for CO and H 2 gases at different temperatures and gas concentrations. The device with the SnO 2 –Cu/Pt thin-film, showed excellent electrical response towards CO gas and device with SnO 2 –Cu/Pt/SiO 2 thin-film showed response towards hydrogen only. The SiO 2 thin-film prevents the diffusion of CO gas and only hydrogen gas diffuse through silicon dioxide layer. Using thin-films structure SnO 2 –Cu/Pt and SnO 2 –Cu/Pt/SiO 2 , a highly selective sensor device for CO and H 2 gas was fabricated. The surface characterization of these thin-films was performed using scanning electron microscopy (SEM) and X-ray photoemission spectroscopy (XPS) techniques. The SEM picture showed that surface structure of the SnO 2 thin-film improved by copper doping.
TL;DR: In this article, a fuzzy iteration methodology is presented to give the objective weight and the relative membership degree of alternatives at the same time, since the weight and relative membership degrees are directly acquired from the recommended alternatives provided by decision makers.
Abstract: Reservoir flood control is operated in real time so finding the optimal solution is unnecessary since it may not be practical. The key to reservoir flood control operation is quickly generating some feasible and effective alternatives and then selecting one among them. A fuzzy iteration methodology, which gives the objective weight and the relative membership degree of alternatives at the same time, is presented. Since the weight and relative membership degree are directly acquired from the recommended alternatives provided by decision makers, the results are more reasonable and realistic. Besides, the difficulty in giving weights is also avoided. With the aid of a robust and flexible decision support system, the effectiveness of decision making can be improved.
TL;DR: Fourteen new 2,5-disubstituted-1,3,4-oxadiazoles were synthesized and evaluated for their insect growth regulatory activity against second-instar larvae of armyworm (Pseudaletia separata Walker).
Abstract: Fourteen new 2,5-disubstituted-1,3,4-oxadiazoles, namely (i) six 2-[2,2-dimethyl-3-(2,2-dichlorovinyl)-cyclopropyl]-5-substituted-1,3,4-oxadiazoles and (ii) eight 2-substituted-phenoxymethyl-5-substituted-aryl-1,3,4-oxadiazoles, were synthesized and evaluated for their insect growth regulatory activity against second-instar larvae of armyworm (Pseudaletia separata Walker). Two of these compounds (7 and 8) showed good insecticidal activities, with LC(50) values of 14.33 and 15.85 microg/mL, respectively. Steric parameters (e.g., the molecular length d and the ratio of the nonpolar surface area and polar surface area V(1)/V(2)) and semiempirical quantum parameters (e.g., the molecular total energy E(t) and the lowest unoccupied molecular orbital energy E(LUMO) and so on) of these compounds, as well as those of six other 2,5-disubstituted-1,3,4-oxadiazoles reported, were acquired by the molecular modeling method and the PM3-SCF-MO method, respectively. With the help of the synthons' activity contribution method based on the Free-Wilson approach in its Fujita-Ban variant, quantitative structure-activity relationships were studied by regressing half-lethal concentrations against the above parameters.
TL;DR: Based on the Mindlin/Reissner plate theory, two refined triangular thin/thick plate elements, the conforming displacement element DKTM with one point quadrature for the part of shear strain and the element RDKTM with the re-constitution of the shear force, are proposed in this paper.
Abstract: Based on the Mindlin/Reissner plate theory, two refined triangular thin/thick plate elements, the conforming displacement element DKTM with one point quadrature for the part of shear strain and the element RDKTM with the re-constitution of the shear strain, are proposed. In the formulations the exact displacement function of the Timoshenko's beam is used to derive the element displacements of the refined elements. Numerical examples are presented to show that the present models indeed possess properties of high accuracy for thin and thick plates, is capable of passing the patch test required for Kirchhoff thin plate elements, and does not exhibits extra zero energy modes. The element RDKTM is free of locking for very thin plate analysis and its convergence can be ensured theoretically. However, the element DKTM is not free of shear locking when the thickness/span ratios less than 10−2. Copyright © 2001 John Wiley & Sons, Ltd.
TL;DR: In this paper, a review of the theory and simulation of nonlinear collisionless reconnection holds the promise for providing solutions to some outstanding problems in laboratory and astrophysical plasma physics, including sawtooth oscillations in tokamaks, magnetotail substorms, and impulsive solar and stellar flares.
Abstract: Recent developments in the theory and simulation of nonlinear collisionless reconnection hold the promise for providing solutions to some outstanding problems in laboratory and astrophysical plasma physics. Examples of such problems are sawtooth oscillations in tokamaks, magnetotail substorms, and impulsive solar and stellar flares. In each of these problems, a key issue is the identification of fast reconnection rates that are insensitive to the mechanism that breaks field lines (resistivity and/or electron inertia). The classical models of Sweet-Parker and Petschek sought to resolve this issue in the realm of resistive magnetohydrodynamics (MHD). However, the plasmas mentioned above are weakly collisional, and hence obey a generalized Ohm’s law in which the Hall current and electron pressure gradient terms play a crucial role. Recent theoretical models and simulations on impulsive (or triggered) as well as quasi-steady reconnection governed by a generalized Ohm’s law are reviewed. In the impulsive reconnection problem, not only is the growth rate fast but the time-derivative of the growth rate changes rapidly. In the steady-state reconnection problem, explicit analytical expressions are obtained for the geometric characteristics (that is, length and width) of the reconnection layer and the reconnection rate. Analytical results are tested by Hall MHD simulations. While some of the geometric features of the reconnection layer and the weak dependence of the reconnection rate on resistivity are reminiscent of Petschek’s classical model, the underlying wave and particle dynamics mediating the reconnection dynamics in the presence of the Hall current and electron pressure gradient are qualitatively different. Quantitative comparisons are made between theory and observations. Open and unresolved issues are identified.
TL;DR: In this paper, the authors present a rich class of exact solutions which contain radiation-dominated and matter-dominated models for the early and late universe, including a variable cosmological constant which is derived from a higher dimension and manifests itself in spacetime as an energy density for the vacuum.
Abstract: We present a rich class of exact solutions which contains radiation-dominated and matter-dominated models for the early and late universe. They include a variable cosmological ``constant'' which is derived from a higher dimension and manifests itself in spacetime as an energy density for the vacuum. This is in agreement with observational data and is compatible with extensions of general relativity to string and membrane theory. Our solutions are also typified by a non-singular ``big bounce'' (as opposed to a singular big bang), where matter is created as in inflationary cosmology.
TL;DR: The amorphous boron-carbon-nitrogen (BCN) films were deposited by RF magnetron sputtering from a mixed target composed of h-BN and graphite as discussed by the authors.
TL;DR: A solution strategy for such a problem is proposed and corresponding heuristic algorithms are presented, known as NP-hard problem of the simplified vessel of satellite which moves spirally.
TL;DR: In this article, sulfonated poly(phthalazinone ether sulfone ketone)s (SPPESKs) were fabricated into ultrafiltration (UF) and nanofiltration (NF) asymmetric membranes.
TL;DR: It was concluded from the model that the main factors affecting photolysis half-lives of PAHs under irradiation of sunlight are PAH absolute hardness and electronegativity, which are related to the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital.
TL;DR: The ginsenoside-β-glucosidase that hydrolyzes the β-(1→2)- glucoside of the gINSenoside Rg3 sugar moiety to ginseneside Rh2 was isolated from the ginseng root, and the enzyme was purified and characterized.
Abstract: The ginsenoside-beta-glucosidase that hydrolyzes the beta-(1-->2)-glucoside of the ginsenoside Rg3 sugar moiety to ginsenoside Rh2 was isolated from the ginseng root, and the enzyme was purified and characterized. The enzyme was purified to one spot in SDS polyacrylamide gel electrophoresis, and its molecular weight was about 59 kDa. The optimum temperature of the ginsenoside-beta-glucosidase was 60 degrees C, and the optimum pH was 5.0. Ca2+ ion had positive effect on ginsenoside-beta-glucosidase, while Cu2+ had negative effect on it. The ginsenoside-beta-glucosidase may be a special beta-glucosidase that is different from the original exocellulase such as beta-glucosidase (EC 3.2.1.21).
TL;DR: In this paper, a linear stability analysis of ion-acoustic and dustacoustic waves is carried out using a multifluid model in the presence of ionization, ion drag, and collisions of ions and dust with the background neutral gas.
Abstract: A linear stability analysis of ion-acoustic and dust-acoustic waves is carried out using a multifluid model in the presence of ionization, ion drag, and collisions of ions and dust with the background neutral gas. It is found that an unstable dust-acoustic mode of nonzero real frequency can be generated via a resonance phenomenon. This resonance develops as the frequency of the dust-ion-acoustic mode is reduced sufficiently in the long-wavelength regime that it couples strongly to the dust-acoustic mode. As the charge on dust particles exceeds a threshold, multiple low-frequency modes with large growth rates are excited suddenly. Predictions of the theory are compared with experimental results [D. Samsonov and J. Goree, Phys. Rev. E 59, 1047 (1999)].
TL;DR: In this article, a modification of poly(phthalazinone ether sulfone ketone) (PPESK) by sulfonation with concentrated or fuming sulfuric acid was carried out to prepare membrane materials with increased hydrophilicity and potentially increased fouling resistance.
Abstract: Modification of poly(phthalazinone ether sulfone ketone) (PPESK) by sulfonation with concentrated or fuming sulfuric acid as sulfonation agents was carried out to prepare membrane materials with increased hydrophilicity and potentially increased fouling resistance. Sulfonated PPESK (SPPESK) copolymers, with a degree of sulfonation ranging from 10–300%, were prepared and characterized. Factors affecting the sulfonation reaction were studied, and reaction conditions for the preparation of SPPESK with different degrees of sulfonation were determined. Compared with the properties of PPESK, the hydrophilicity of SPPESK was increased, as shown by a reduced contact angle with water. The glass transition temperature was increased from 278°C (PPESK) to a maximum of 323°C for the highly sulfonated derivative, due to the strong polarity of SO3H and hydrogen bonding. Ultrafiltration membranes prepared with PPESK and SPPESK were compared. For a SPPESK asymmetric membrane, the PEG12000 rejection was 98% and the water flux was 876 kg · m−2 · h−1. SPPESK/PPESK composite nanofiltration membranes were also prepared and were shown to have short-term operational stability up to 120°C. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1685–1692, 2001
TL;DR: In this paper, the authors studied the nonlinear evolution of a dust ellipsoid embedded in a flat Friedmann background universe, in order to determine the evolution of the density of the ellipssoid as the perturbation associated with it detaches from the general expansion and begins to collapse.
Abstract: We study the nonlinear evolution of a dust ellipsoid embedded in a flat Friedmann background universe, in order to determine the evolution of the density of the ellipsoid as the perturbation associated with it detaches from the general expansion and begins to collapse. We show that while the growth rate of the density contrast of a mass element is enhanced by shear, in agreement with Hoffman's 1986 result, the angular momentum acquired by the ellipsoid has the right magnitude to counterbalance the effect of the shear. This result confirms the previrialization conjecture by showing that initial asphericities and tidal interactions begin to slow the collapse after the system has broken away from the general expansion.
TL;DR: In this paper, a new algorithm is proposed to convert nonhomogeneous dynamic systems into homogeneous dynamic systems by means of the dimensional expanding method, which is not required in the precise time-integration method.
Abstract: The precise time-integration method proposed for a linear time-invariant dynamic system can give precise numerical results approaching the exact solution at the integration points. However, dife culties arise when the algorithm is used for nonhomogeneous dynamic systems due to the inverse matrix calculation required. A new algorithm isproposedto convertnonhomogeneousdynamicequationsinto homogeneousequationsbymeansofthe dimensional expanding method. With this conversion, the inverse matrix calculation is not required in the precise time-integration method. The new algorithm has enhanced the precise time-integration method by benee ting the programming implementation and the numerical stability; it has improved the computational efe ciency as well. Numerical examples are given to demonstrate the validity and efe ciency of the algorithm. Nomenclature Ai = coefe cient of the solution of Fourier series ai = coefe cient vector Bi = coefe cient of the solution of Fourier series bi = coefe cient vector C = magnitude of the load on the nodes of the structure D = coefe cient matrix of ordinary differential equations satise ed by the nonhomogeneous vector d = number of terms of one series f = load vector G = damping matrix H = coefe cient matrix of structural dynamic system H ¤ = coefe cient matrix of expanding structural dynamic system I = identity matrix K = number of time steps K = stiffness matrix k = order of time step l = number of dynamic modes M = mass matrix m = number of 2 N N = algorithm parameter of precise time integration n = dimension of the structural dynamic system p = transformed system state variable q = displacement vector r = nonhomogeneous vector of structural dynamic system Ta = small part of the matrix exponential Tc = part of matrix exponential according to matrix C Td = part of matrix exponential according to matrix D t = time v = state variable of structure dynamic system v ¤ = state variable vector of expanding structural