Showing papers by "Shanghai University published in 2002"
TL;DR: In this paper, a modified Lindstedt-Poincare method is proposed to avoid the occurrence of secular terms in the perturbation series solution, which is suitable not only for weakly nonlinear systems, but also for strongly non-linear systems.
Abstract: In this paper, a modified Lindstedt–Poincare method is proposed In this technique, a constant, rather than the non-linear frequency, is expanded in powers of the expanding parameter to avoid the occurrence of secular terms in the perturbation series solution Some examples are given here to illustrate its effectiveness and convenience The results show that the obtained approximate solutions are uniformly valid on the whole solution domain, and they are suitable not only for weakly non-linear systems, but also for strongly non-linear systems
283 citations
TL;DR: These error estimators are shown to be useful in adaptive finite element approximation for the optimal control problems and are implemented in the adaptive approach.
Abstract: In this paper, sharp a posteriori error estimators are derived for a class of distributed elliptic optimal control problems. These error estimators are shown to be useful in adaptive finite element approximation for the optimal control problems and are implemented in the adaptive approach. Our numerical results indicate that the sharp error estimators work satisfactorily in guiding the mesh adjustments and can save substantial computational work.
247 citations
TL;DR: In this article, a modified Lindstedt-Poincare method is proposed to avoid the occurrence of secular terms in the perturbation series solution, which is suitable not only for weakly nonlinear systems, but also for strongly non-linear systems.
Abstract: In this paper, a modified Lindstedt–Poincare method is proposed. In this technique, we introduce a new transformation of the independent variable. This transformation will also allow us to avoid the occurrence of secular terms in the perturbation series solution. Some examples are given here to illustrate its effectiveness and convenience. The results show that the obtained approximate solutions are uniformly valid on the whole solution domain, and they are suitable not only for weakly non-linear systems, but also for strongly non-linear systems.
182 citations
10 Dec 2002
TL;DR: In this paper, a new axial flux surface mounted permanent magnet (PM) field controlled TORUS type (FCT) machine is presented, and a linear model and sizing analysis using generalized sizing equations are introduced.
Abstract: This paper presents a new axial flux surface mounted permanent magnet (PM) field controlled TORUS type (FCT) machine. Machine structure and principles are explored and the field weakening feature of the topology as well as the advantages of the machine are presented in the first part. The second section introduces the linear model and sizing analysis using generalized sizing equations. Optimization of the machine pole number and power density maximization for the optimum pole number is also achieved. In the third section, 3D finite element analyses (FEA) of the topology are illustrated for different field currents in order to accomplish the machine design and to determine the sizing of the optimum field winding. Furthermore, torque analysis of the FCT machine using 3D finite element analysis is also carried out and illustrated in the paper.
128 citations
TL;DR: In this article, a weighted orthogonal system on the half-line based on the Chebyshev rational functions is introduced, and the error estimates for both the rational spectral and pseudospectral methods are considered both theoretically and numerically.
Abstract: A weighted orthogonal system on the half-line based on the Chebyshev rational functions is introduced. Basic results on Chebyshev rational approximations of several orthogonal projections and interpolations are established. To illustrate the potential of the Chebyshev rational spectral method, a model problem is considered both theoretically and numerically: error estimates for the Chebyshev rational spectral and pseudospectral methods are established; preliminary numerical results agree well with the theoretical estimates and demonstrate the effectiveness of this approach.
118 citations
TL;DR: In this paper, a distance transformation for the accurate evaluation of near singular boundary integrals with various kernels for both the two-and three-dimensional problems incorporated with the distance functions defined in the local intrinsic coordinate systems is proposed.
Abstract: The accurate numerical solution of near singular boundary integrals was an issue of major concern in most of the boundary element analysis next to the singular boundary integrals. The problem was solved in this paper by a kind of non-linear transformation, namely, the distance transformation for the accurate evaluation of near singular boundary integrals with various kernels for both the two- and three-dimensional problems incorporated with the distance functions defined in the local intrinsic coordinate systems. It is considered that two effects play the role in the transformation. They are the damping out of the near singularity and the rational redistribution of integration points. The actual numerical computation can be performed by standard Gaussian quadrature formulae and can be easily included in the existing computer code, along with its insensitivity to the kind of the boundary elements. Numerical results of potential problem were presented, showing the effectiveness and the generality of the algorithm, which makes it possible, for the first time, to observe the behaviors of various boundary integral values with numerical means, when the source point is moving across the boundary with fine steps.
118 citations
TL;DR: SA-B could effectively reverse liver fibrosis in chronic hepatitis B and was better than IFN-gamma in reduction of serum HA content, overall decrease of 4 serum fibrotic markers, and decrease of ultrasound imaging score.
Abstract: AIM: To evaluate the clinical efficacy of salvianolic acid B (SA-B) on liver fibrosis in chronic hepatitis B.
METHODS: Sixty patients with definite diagnosis of liver fibrosis with hepatitis B were included in the trial. Interferon-γ (IFN-γ) was used as control drug. The patients took orally SA-B tablets or received muscular injection of IFN-γ in the double blind randomized test. The complete course lasted 6 mo. The histological changes of liver biopsy specimen before and after the treatment were the main evidence in evaluation, in combination with the results of contents of serum HA, LN, IV-C, P-III-P, liver ultrasound imaging, and symptoms and signs.
RESULTS: Reverse rate of fibrotic stage was 36.67% in SA-B group and 30.0% in IFN-γ group. Inflammatory alleviating rate was 40.0% in SA-B group and 36.67% in IFN-γ group. The average content of HA and IV-C was significantly lower than that before treatment. The abnormal rate also decreased remarkably. Overall analysis of 4 serological fibrotic markers showed significant improvement in SA-B group as compared with the IFN-γ group. Score of liver ultrasound imaging was lower in SA-B group than in IFN-γ group (HA 36.7% vs 80%, IV-C 3.3% vs 23.2%). Before the treatment, ALT AST activity and total bilirubin content of patients who had regression of fibrosis after oral administration of SA-B, were significantly lower than those of patients who had aggravation of fibrosis after oral administration of SA-B. IFN-γ showed certain side effects (fever and transient decrease of leukocytes, occurrence rates were 50% and 3.23%), but SA-B showed no side effects.
CONCLUSION: SA-B could effectively reverse liver fibrosis in chronic hepatitis B. SA-B was better than IFN-γ in reduction of serum HA content, overall decrease of 4 serum fibrotic markers, and decrease of ultrasound imaging score. Liver fibrosis in chronic hepatitis B with slight liver injury was more suitable to SA-B in anti-fibrotic treatment. SA-B showed no obvious side effects.
106 citations
TL;DR: In this article, a systematic approach to constructing an infinite number of conservation laws for discrete soliton systems is proposed, and three examples are given; see Section 2.2.1.
Abstract: A systematic approach to constructing an infinite number of conservation laws for discrete soliton systems is proposed, and three examples are given.
104 citations
TL;DR: In this article, the Hamiltonian structures of the lattice isospectral evolution equations associated with a general discrete spectral problem were investigated and the existence of the recursion operator L, which is a strong and hereditary symmetry of the flows, was shown.
Abstract: We describe an approach for investigating the Hamiltonian structures of the lattice isospectral evolution equations associated with a general discrete spectral problem. By using the so-called implicit representations of the isospectral flows, we demonstrate the existence of the recursion operator L, which is a strong and hereditary symmetry of the flows. It is then proven that every equation in the isospectral hierarchy possesses the Hamiltonian structure if L has a skew-symmetric factorization and the first equation (ut = K(0)) in the hierarchy satisfies some simple condition. We obtain related properties, such as the implectic-symplectic factorization of L, the Liouville complete integrability and the multi-Hamiltonian structures of the isospectral hierarchy. Four examples are given.
101 citations
TL;DR: The N -soliton solutions for the modified KdV equation with self-consistent sources are obtained through Hirota's method and Wronskian technique respectively.
Abstract: The N -soliton solutions for the modified KdV equation with self-consistent sources are obtained through Hirota's method and Wronskian technique respectively. Some novel determinantal identities are presented to treat the nonlinear term in the time evolution and finish the Wronskian verifications. The uniformity of these two kinds of N -soliton solutions is proved.
99 citations
TL;DR: An improved Knoevenagel condensation reaction of aldehydes and malononitrile can be achieved by grinding at room temperature in the absence of solvents and catalysts as mentioned in this paper.
TL;DR: In this paper, a general algorithm of the distance transformation type is presented for the accurate numerical evaluation of nearly singular boundary integrals encountered in elasticity, which, next to the singular ones, has long been an issue of major concern in computational mechanics with boundary element methods.
Abstract: A general algorithm of the distance transformation type is presented in this paper for the accurate numerical evaluation of nearly singular boundary integrals encountered in elasticity, which, next to the singular ones, has long been an issue of major concern in computational mechanics with boundary element methods. The distance transformation is realized by making use of the distance functions, defined in the local intrinsic coordinate systems, which plays the role of damping-out the near singularity of integrands resulting from the very small distance between the source and the integration points. By taking advantage of the divergence-free property of the integrals with the nearly hypersingular kernels in the 3D case, a technique of geometric conversion over the auxiliary cone surfaces of the boundary element is designed, which is suitable also for the numerical evaluation of the hypersingular boundary integrals. The effects of the distance transformations are studied and compared numerically for different orders in the 2D case and in the different local systems in the 3D case using quadratic boundary elements. It is shown that the proposed algorithm works very well, by using standard Gaussian quadrature formulae, for both the 2D and 3D elastic problems.
06 May 2002
TL;DR: The results of the experiments show that the proposed SNNB algorithm is efficient and it outperforms Naive Bayes, and state-of-the-art classification methods NBTree, CBA, and C4.5 in terms of accuracy.
Abstract: Naive Bayes is a probability-based classification method which is based on the assumption that attributes are conditionally mutually independent given the class label. Much research has been focused on improving the accuracy of Naive Bayes via eager learning. In this paper, we propose a novel lazy learning algorithm, Selective Neighbourhood based Naive Bayes (SNNB). SNNB computes different distance neighborhoods of the input new object, lazily learns multiple Naive Bayes classifiers, and uses the classifier with the highest estimated accuracy to make decision. The results of our experiments on 26 datasets show that our proposed SNNB algorithm is efficient and it outperforms Naive Bayes, and state-of-the-art classification methods NBTree, CBA, and C4.5 in terms of accuracy.
TL;DR: In this article, the existence and approximation of the global attractor for second order damped lattice dynamical systems was studied. But the approximation was not considered for the case where the lattice lattice is not convex.
TL;DR: In this paper, the formation mechanism of ZnS nanowires has been studied, and it was shown that the formation process probably was via the process of the directional aggregation and orientated growth of the nanoparticles.
TL;DR: In this paper, a new route of Knoevenagel condensation of aromatic aldehydes with Meldrum's acid, barbituric acid and dimedone in the presence of cetyltrimethyl ammonium bromide at room temperature in water is described.
TL;DR: In this article, a new outer-rotor permanent magnet (PM) brushless DC drive is designed and analyzed to enable this drive to be applied to electric vehicles, its transient performances at both normal and flux-weakening operations are particularly focused.
Abstract: In this paper, a new outer-rotor permanent magnet (PM) brushless DC drive is designed and analyzed. To enable this drive to be applied to electric vehicles, its transient performances at both normal and flux-weakening operations are particularly focused. The distinct feature in design is due to the new motor configuration including the outer-rotor topology, the multipole magnetic circuit and the full slot-pitch coil span arrangement. The distinct feature in analysis is due to the development of the circuit-field-torque coupled time-stepping finite-element method. The proposed PM brushless DC drive is prototyped. The analysis results are verified by experimental measurement.
TL;DR: In this article, the development of Si-based micro-machined micro-heater array with extremely low power consumption, lowvoltage operation, and CMOS compatibility, and low voltage and low power CMOS drive circuitry for the microheaters that can provide large drive current and voltage swing, and heater temperature is continuously adjustable in the full temperature range.
Abstract: Low-voltage and low-power design is the key issue for the portable electronics applications and has become the major concern for the system design. Integrated gas sensor array allows the monolithic realization of multi-species gas sensing systems. This paper reports the developments of Si-based micro-machined micro-heater array with extremely low-power consumption, low-voltage operation, and CMOS compatibility, and low-voltage and low-power CMOS drive circuitry for the micro-heaters that can provide large drive current and voltage swing, and heater temperature is continuously adjustable in the full temperature range.
TL;DR: An approach to fillet polyhedral model is investigated and a simple way to detect detailed boundary elements is developed, which can be applied in efficient modeling for CAE from CAD models.
Abstract: A methodology for abstracting features from a 3D solid model based on a new detail-level metric method is proposed. Filleting the whole boundary of an object with constant fillet radius has the effect of low-pass filtering. Taking advantage of the effect, detail-level of boundary entities can be rated. This paper investigates an approach to fillet polyhedral model and then develops a simple way to detect detailed boundary elements. Taking detailed entities as the indicators, detail features are recognized and extracted. In the detailed entities detection and decomposition cycle of the corresponding detail features, detail features are decomposed from the model one by one in terms of their locality. Detail feature decomposition directly results in geometric simplification of a 3D object. The method proposed in this paper can be applied in efficient modeling for CAE from CAD models.
TL;DR: In this paper, a dual-polarized corner-fed microstrip antenna element and arrays with thin single-layer structure are investigated by the proposed extended multiport network method (EMNM).
Abstract: A systematic study on the dual-polarized corner-fed microstrip antenna element and arrays with thin single-layer structure is presented. The impedance matrices and S-parameters of the element and arrays are investigated by the proposed extended multiport network method (EMNM). The co- and cross-polarization patterns are also analyzed. It is shown that this kind of antenna element has an isolation about 10 dB higher than that of a conventional edge-fed square patch. A series of new dual-polarized arrays of corner-fed patches have been designed and analyzed based on the EMNM. The experimental results of five arrays indicate that these arrays achieve an isolation of 27/spl sim/38 dB with a maximum of higher than 28/spl sim/58 dB and cross-polarization level of lower than -23/spl sim/ -30 at boresight, which are substantially better than those of similar dual-polarized arrays of edge-fed patches. All theoretical results are in good agreement with experimental ones.
TL;DR: In this article, an alternative choice of f ð1Þ of our interest is f 1Þ 1 �4 XN, which is essentially the same as (9).
Abstract: !j 1⁄4 B kj Ak j ; e Ajl 1⁄4 ðkj klÞ ðkj þ klÞ ; ð9bÞ and the sum over 1⁄4 0; 1 refers to each of the j; j 1⁄4 1; 2; ;N. Obviously, the solution of SG equation and MKdV equation can be found from (2) and (9). In addition, the solution of this equation possesses an another representation, the Wronskian form, which is essentially the same as (9). In this paper, an alternative choice of f ð1Þ of our interest is f ð1Þ 1⁄4 XN
TL;DR: The typical morphologies of Cu-doped ZnS nanocrystals in a polyvinyl alcohol (PVA) film by an ion complex transformation method observed by transmission electron microscope show that the particles were rather evenly distributed throughout the PVA film, and the dimension was estimated to be about 5.7 µm in diameter as mentioned in this paper.
TL;DR: In this paper, the buckling behavior of purlin-sheeting systems under wind uplift loading is analyzed using finite strip methods in which the pre-buckling stress is calculated based on the same model used for the buckle analysis rather than taken as the pure bending stress.
Abstract: This paper presents a study on the buckling behaviour of purlin-sheeting systems under wind uplift loading. The restraint provided by the sheeting to the purlin is modeled by using two springs representing the translational and rotational restraints. The analysis is performed using finite strip methods in which the pre-buckling stress is calculated based on the same model used for the buckling analysis rather than taken as the ‘pure bending’ stress. The results obtained from this study show that, for both local and distortional buckling, the restraints have significant influence on the critical loads through their influence on the pre-buckling stress rather than directly on the buckling modes. While for lateral-torsional buckling, the influence of the restraints on the critical loads is mainly due to their influence on the buckling modes rather than the pre-buckling stress.
TL;DR: This paper studies the chaotification problem of driving a continuous-time system to a chaotic state by using an impulsive control input and proves it to be not only possible but also implementable near a stable limit cycle of the given system.
Abstract: This paper studies the chaotification problem of driving a continuous-time system to a chaotic state by using an impulsive control input. The controller is designed to ensure the controlled orbit be bounded and, meanwhile, have positive Lyapunov exponents. This is proved to be not only possible but also implementable near a stable limit cycle of the given system. Two numerical examples are given to illustrate the effectiveness of the proposed chaotification method.
TL;DR: In this article, a red luminescent material N,N-bis{4]-2-(4-dicyanomethylene)-4H-pyran electron acceptor moieties and a triphenylamine electron-donor moiety for application in organic light-emitting diodes (OLEDs) was synthesized.
Abstract: A novel red luminescent material N,N-bis{4-[2-(4-dicyanomethylene-6-methyl-4H-pyran-2-yl)ethylene]phenyl}aniline (BDCM) with two (4-dicyanomethylene)-4H-pyran electron-acceptor moieties and a triphenylamine electron-donor moiety for application in organic light-emitting diodes (OLEDs) was synthesized. The resultant compound has a sterically well-hindered structure and a high fluorescence yield. The photoluminescence (PL) of this compound in solution and solid film and the electroluminescence (EL) have been studied. Based on its intense sterically hindered structure, the pure BDCM film prepared shows a bright red PL emission. The three-layered EL device with the structure ITO/CuPc/DPPhP/BDCM/Mg:Ag has a turn-on voltage of less than 4 V, which suggests that BDCM has an excellent electron injection property. A bright luminance of 582 cd m−2
is obtained for the device at 19 V.
01 Feb 2002-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, a mathematical model for the argon-oxygen decarburization (AOD) stainless steel making process has been proposed and developed based on the assumption that the blown oxygen oxidizes C, Cr, Si, and Mn in the steel and Fe as a matrix.
Abstract: Some available mathematical models for the argon-oxygen decarburization (AOD) stainless steelmaking process have been reviewed. The actual situations of the AOD process, including the competitive oxidation of the elements dissolved in the molten steel and the changes in the bath composition, as well as the nonisothermal nature of the process, have been analyzed. A new mathematical model for the AOD refining process of stainless steel has been proposed and developed. The model is based on the assumption that the blown oxygen oxidizes C, Cr, Si, and Mn in the steel and Fe as a matrix, but the FeO formed is also an oxidant of C, Cr, Si, and Mn in the steel. All the possible oxidation-reduction reactions take place simultaneously and reach a combined equilibrium in competition at the liquid/bubble interfaces. It is also assumed that at high carbon levels, the oxidation rates of elements are primarily related to the supplied oxygen rate, and at low carbon levels, the rate of decarburization is mainly determined by the mass transfer of carbon from the molten steel bulk to the reaction interfaces. It is further assumed that the nonreacting oxygen blown into the bath does not accumulate in the liquid steel and will escape from the bath into the exhaust gas. The model performs the rate calculations of the refining process and the mass and heat balances of the system. Also, the effects of the operating factors, including adding the slag materials, crop ends, and scrap, and alloy agents; the nonisothermal conditions; the changes in the amounts of metal and slag during the refining; and other factors have all been taken into account.
TL;DR: The inhibition of gastric cancer cell growth in vivo by Chinese Jianpi herbs and SRRS is related to induction of the cell apoptosis which may be involved in aberrant expression of p53 and bcl-2 genes.
Abstract: AIM: To explore the mechanism of the Sijunzi decoction and another Chinese herbal recipe (SRRS) based mainly on the Sijunzi decoction in treatment of gastric cancer
METHODS: A human gastric adenocarcinoma cell line SGC-7901 grafted onto nude mouse was used as the animal model The mice were divided into 3 groups, one control and the two representative experimental conditions Animals in the two experimental groups received either Sijunzi decoction or SRRS over a 40-day period starting at 1st day after grafting Control animals received saline on an identical schedule Animals were killed 41 d after being grafted The effect of therapy was assessed by two ways: (1) tumor size was periodically measured during the life of the animals; (2) tumor weight was determined by a electron balance immediately after the animals killed For detection of apoptotic cells, apoptotic indices (AI) were examined by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate fluorescence nick end labeling (TUNEL) method Morphological alterations were observed with electron microscopy S-P immunohistochemical method was used to detect the expression of Ki-67 in xenografts Expression of bcl-2 and p53 was semiquantitatively detected using a reverse transcriptase-polymerase chain reaction (RT-PCR) technique
RESULTS: When compared with controls, tumor growth (size and weight) was significantly inhibited by treatment with the Sijunzi decoction (P < 005) or SRRS (P < 001) The tumor inhibitory rate in the Sijunzi decoction group was 3433% and SRRS group 4653% AI of human gastric cancer xenografts in nude mice was significantly increased to 1624% ± 321% using TUNEL method and 1138% ± 646% by FACScan in the Sijunzi decoction group compared with the controls (TUNEL: 263% ± 103%, P < 001; FACScan: 715% ± 132%, P < 005) SRRS group was also found a significantly increased AI by using TUNEL method and flow cytometry analysis compared with the controls (TUNEL: 1318% ± 305%, P < 005; FACScan: 1158% ± 571% (P < 005) Under electron microscope, cell shrinkage, nuclear chromatin condensation, formation of membrane blebs and apoptotic bodies were frequently observed in Sijunzi decoction group and SRRS group The average labeling index (LI) for Ki-67 in SRRS group was significantly decreased to 843% ± 222% compared with the control group (1037% ± 491%) (P < 005) The average labeling index for Ki-67 in sijunzi decoction group was 795% ± 254% which was lower than that of the control group, but showed no significance (P = 007) The expression level of p53 mRNA was lower in both Sijunzi decoction group and SRRS group than that in control group (P < 005; P < 001) The expression of bcl-2 mRNA was also decreased in SRRS group compared with the control (P < 001)
CONCLUSION: The inhibition of gastric cancer cell growth in vivo by Chinese Jianpi herbs and SRRS is related to induction of the cell apoptosis which may be involved in aberrant expression of p53 and bcl-2 genes
TL;DR: In this article, the equations of motion governing the quasi-static and dynamical behavior of a viscoelastic Timoshenko beam are derived and the effect of both transverse shear and rotational inertia on the vibration of the beam is discussed.
Abstract: The equations of motion governing the quasi-static and dynamical behavior of a viscoelastic Timoshenko beam are derived. The viscoelastic material is assumed to obey a three-dimensional fractional derivative constitutive relation. The quasi-static behavior of the viscoelastic Timoshenko beam under step loading is analyzed and the analytical solution is obtained. The influence of material parameters on the deflection is investigated. The dynamical response of the viscoelastic Timoshenko beam subjected to a periodic excitation is studied by means of mode shape functions. And the effect of both transverse shear and rotational inertia on the vibration of the beam is discussed.
TL;DR: In this article, the effect of Pb(Mn1/3Nb2/3)O3 additives on dielectric and piezoelectric properties of quaternary ceramics was investigated.
TL;DR: A new necessary condition is derived for optimal redundancy assignments in the branch and bound method that may result in a significant reduction of computational efforts, as evidenced in the numerical calculation for linearly constrained redundancy optimization problems.
Abstract: This paper considers the constrained redundancy optimization problem in series systems. This problem can be formulated as a nonlinear integer programming problem of maximizing the overall systems reliability under limited resource constraints. By exploiting special features of the problem, we derive a new necessary condition for optimal redundancy assignments. This condition leads to a new fathoming condition in the branch and bound method that may result in a significant reduction of computational efforts, as evidenced in our numerical calculation for linearly constrained redundancy optimization problems.