Showing papers by "Shanghai Jiao Tong University published in 2003"

Beyond Perturbation: Introduction to the Homotopy Analysis Method

Abstract: PART I BASIC IDEAS Introduction Illustrative Description Systematic Description Relations to Some Previous Analytic Methods Advantages, Limitations, and Open Questions PART II APPLICATIONS Simple Bifurcation of a Nonlinear Problem Multiple Solutions of a Nonlinear Problem Nonlinear Eigenvalue Problem Thomas-Fermi Atom Model Volterra's Population Model Free Oscillation Systems with Odd Nonlinearity Free Oscillation Systems with Quadratic Nonlinearity Limit Cycle in a Multidimensional System Blasius' viscous Flow Boundary-layer Flow with Exponential Property Boundary-layer Flow with Algebraic Property Von Karman Swirling Flow Nonlinear Progressive Waves in Deep Water BIBLIOGRAPHY INDEX

Complex networks: small-world, scale-free and beyond

Abstract: In the past few years, the discovery of small-world and scale-free properties of many natural and artificial complex networks has stimulated a great deal of interest in studying the underlying organizing principles of various complex networks, which has led to dramatic advances in this emerging and active field of research. The present article reviews some basic concepts, important progress, and significant results in the current studies of various complex networks, with emphasis on the relationship between the topology and the dynamics of such complex networks. Some fundamental properties and typical complex network models are described; and, as an example, epidemic dynamics are analyzed and discussed in some detail. Finally, the important issue of robustness versus fragility of dynamical synchronization in complex networks is introduced and discussed.

On the analytic solution of magnetohydrodynamic flows of non-Newtonian fluids over a stretching sheet

Abstract: A powerful, easy-to-use analytic technique for nonlinear problems, the homotopy analysis method, is employed to give analytic solutions of magnetohydrodynamic viscous flows of non-Newtonian fluids over a stretching sheet. For the so-called second-order and third-order power-law fluids, the explicit analytic solutions are given by recursive formulas with constant coefficients. Also, for real power-law index and magnetic field parameter in a quite large range, an analytic approach is proposed. All of our analytic results agree well with numerical ones. In particular, a simple analytic formula of the dimensionless velocity gradient at the wall is found, which is accurate for all real power-law indices and magnetic field parameters. This analytic formula can give sufficiently accurate results for the skin friction on the moving sheet that it would find wide application in industries. Physically, they indicate that the magnetic field tends to increase the skin friction, and that this effect is more pronounced for shear-thinning than for shear-thickening fluids.

A novel anionic surfactant templating route for synthesizing mesoporous silica with unique structure

Abstract: A novel anionic surfactant templating route for synthesizing mesoporous silica with unique structure

A local-world evolving network model

Abstract: We propose and study a novel evolving network model with the new concept of local-world connectivity, which exists in many physical complex networks. The local-world evolving network model represents a transition between power-law and exponential scaling, while the Barabasi–Albert scale-free model is only one of its special (limiting) cases. We found that this local-world evolving network model can maintain the robustness of scale-free networks and can improve the network reliance against intentional attacks, which is the inherent fragility of most scale-free networks.

Novel as1 and as2 defects in leaf adaxial-abaxial polarity reveal the requirement for ASYMMETRIC LEAVES1 and 2 and ERECTA functions in specifying leaf adaxial identity.

Abstract: The shoot apical meristem (SAM) of seed plants is the site at which lateral organs are formed. Once organ primordia initiate from the SAM, they establish polarity along the adaxial-abaxial, proximodistal and mediolateral axes. Among these three axes, the adaxial-abaxial polarity is of primary importance in leaf patterning. In leaf development, once the adaxial-abaxial axis is established within leaf primordia, it provides cues for proper lamina growth and asymmetric development. It was reported previously that the Arabidopsis ASYMMETRIC LEAVES1 (AS1) and ASYMMETRIC LEAVES2 (AS2) genes are two key regulators of leaf polarity. In this work, we demonstrate a new function of the AS1 and AS2 genes in the establishment of adaxial-abaxial polarity by analyzing as1 and as2 alleles in the Landsberg erecta (Ler) genetic background. We provide genetic evidence that the Arabidopsis ERECTA (ER) gene is involved in the AS1-AS2 pathway to promote leaf adaxial fate. In addition, we show that AS1 and AS2 bind to each other, suggesting that AS1 and AS2 may form a complex that regulates the establishment of leaf polarity. We also report the effects on leaf polarity of overexpression of the AS1 or AS2 genes under the control of the cauliflower mosaic virus (CAMV) 35S promoter. Although plants with as1 and as2 mutations have very similar phenotypes, 35S::AS1/Ler and 35S::AS2/Ler transgenic plants showed dramatically different morphologies. A possible model of the AS1, AS2 and ER action in leaf polarity formation is discussed.

Transcription Factor Sp1 Expression Is a Significant Predictor of Survival in Human Gastric Cancer

Abstract: The transcription factor Sp1 regulates the expression of multiple genes. However, its expression and role in human tumor development and progression remain unclear. Using immunohistochemistry, we investigated Sp1 expression patterns in 86 cases of human gastric cancer having various clinicopathologic characteristics, 57 normal gastric tissue specimens, and 53 lymph node metastases. We found that Sp1 protein was expressed predominantly in the nuclei of cells located in the mucous neck region, whereas Sp1 expression was not detected either in the cells located toward the gastric pit (foveolar differentiation) or cells of the glandular epithelium (glandular differentiation). In sharp contrast, strong Sp1 expression was detected in tumor cells, whereas no or very weak Sp1 expression was detected in stromal cells and normal glandular cells surrounding or within the tumors. We also evaluated the effect of Sp1 expression on the survival of patients who have undergone surgical resection. The median survival duration in patients who had a tumor with negative, weak, and strong Sp1 expression was 43, 37, and 8 months, respectively (P = 0.0075). Next, Sp1 expression, stage, completeness of resection, age, and sex were entered into a Cox proportional hazard model. In multivariate analysis, Sp1 (P = 0.003) and stage (P < 0.001) were independently prognostic of survival. Therefore, normal and malignant gastric tissues have unique Sp1 expression patterns. Given the importance of Sp1 in the expression of multiple molecules key to tumor cell survival, growth, and angiogenesis, its disregulated expression and activation may play important roles in gastric cancer development and progression.

Tribological Behavior of Carbon-Nanotube-Filled PTFE Composites

Abstract: Carbon nanotube/polytetrafluoroethylene (CNT/PTFE) composites with different volume fractions were prepared and their friction and wear properties were investigated using a ring-on-block under dry conditions. It was found that CNTs signifi-cantly increased the wear resistance of PTFE composites and decreased their coefficient of friction. PTFE composites with 15–20 vol.% CNTs exhibited very high wear resistance. The significant improvements in the tribological properties of CNT/PTFE composites are attributed to the super-strong mechanical properties and the very high aspect ratio of CNTs. The CNTs greatly reinforce the structure of the PTFE-based composites and thereby greatly reduce the adhesive and plough wear of CNT/PTFE composites. The CNTs are released from the composite during sliding and transferred to the interface of the friction couples. They thus serve as spacers, preventing direct contact between the mating surfaces and thereby reducing both wear rate and friction coefficient.

Homotopy analysis of nonlinear progressive waves in deep water

Abstract: This paper describes the application of a recently developed analytic approach known as the homotopy analysis method to derive a solution for the classical problem of nonlinear progressive waves in deep water. The method is based on a continuous variation from an initial trial to the exact solution. A Maclaurin series expansion provides a successive approximation of the solution through repeated application of a differential operator with the initial trial as the first term. This approach does not require the use of perturbation parameters and the solution series converges rapidly with the number of terms. In the framework of this approach, a new technique to apply the Pade expansion is implemented to further improve the convergence. As a result, the calculated phase speed at the 20th-order approximation of the solution agrees well with previous perturbation solutions of much higher orders and reproduces the well-known characteristics of being a non-monotonic function of wave steepness near the limiting condition.

Controlling and synchronizing chaotic Genesio system via nonlinear feedback control

Abstract: In this paper, a new method to control and synchronize chaotic Genesio system is proposed. We can design a nonlinear feedback controller to make the controlled system be stabilized at origin and two Genesio systems be synchronized. The stability analysis of controlled system becomes simple Hurwitz stability analysis provided that a parameter is chosen suitably. Numerical simulations verify the effectiveness of this method.

Antidiabetic herbal drugs officially approved in China.

Abstract: Over the centuries, Chinese herbal drugs have served as a major source of medicines for the prevention and treatment of diseases including diabetes mellitus (known as 'Xiao-ke'). It is estimated that more than 200 species of plants exhibit hypoglycaemic properties, including many common plants, such as pumpkin, wheat, celery, wax guard, lotus root and bitter melon. To date, hundreds of herbs and traditional Chinese medicine formulas have been reported to have been used for the treatment of diabetes mellitus. This paper provides a brief review of the antidiabetic drugs of plant origin that have been approved by the Chinese health regulatory agency for commercial use in China. It was believed, through pharmacological studies, that medicinal herbs were meticulously organized in these antidiabetic drug formulas such that polysaccharide containing herbs restore the functions of pancreatic tissues and cause an increase in insulin output by the functional beta cells, while other ingredients enhance the microcirculation, increase the availability of insulin and facilitate the metabolism in insulin-dependent processes. Pharmacological and clinical evaluations indicated that these drugs had a mild, but significant, blood glucose lowering effect and that the long-term use of these agents may be advantageous over chemical drugs in alleviating some of the chronic diseases and complications caused by diabetes. Additionally, the use of these natural agents in conjunction with conventional drug treatments, such as a chemical agent or insulin, permits the use of lower doses of the drug and/or decreased frequency of administration which decreases the side effects most commonly observed.

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays.

Abstract: We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

A novel video key-frame-extraction algorithm based on perceived motion energy model

Abstract: The key frame is a simple yet effective form of summarizing a long video sequence. The number of key frames used to abstract a shot should be compliant to visual content complexity within the shot and the placement of key frames should represent most salient visual content. Motion is the more salient feature in presenting actions or events in video and, thus, should be the feature to determine key frames. We propose a triangle model of perceived motion energy (PME) to model motion patterns in video and a scheme to extract key frames based on this model. The frames at the turning point of the motion acceleration and motion deceleration are selected as key frames. The key-frame selection process is threshold free and fast and the extracted key frames are representative.

Complexity and synchronization of the World trade Web

Abstract: The complex topology of a network determines its dynamics. The world economy is now internationally connected through a globalization process of trading. The complex dynamical behaviors of the world economy have been studied as a dynamical system, but there does not seem to be any consideration of the effect of dynamics on the world trade network. In this paper, we attempt such a study and present the scale-free features of the degree distribution, as well as wealth and resource distributions on the World Trade Web (WTW). Moreover, the synchronization phenomenon of economic cycles on the WTW due to its scale-free features is discussed in detail.

Non-linear analysis of functionally graded plates under transverse and in-plane loads

Abstract: Large deflection and postbuckling responses of functionally graded rectangular plates under transverse and in-plane loads are investigated by using a semi-analytical approach. Material properties are assumed to be temperature-dependent, and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The plate is assumed to be clamped on two opposite edges and the remaining two edges may be simply supported or clamped or may have elastic rotational edge constraints. The formulations are based on the classical plate theory, accounting for the plate-foundation interaction effects by a two-parameter model (Pasternak-type), from which Winkler elastic foundation can be treated as a limiting case. A perturbation technique in conjunction with one-dimensional differential quadrature approximation and Galerkin procedure are employed in the present analysis. The numerical illustrations concern the large deflection and postbuckling behavior of functional graded plates with two pairs of constituent materials. Effects played by volume fraction, the character of boundary conditions, plate aspect ratio, foundation stiffness, initial compressive stress as well as initial transverse pressure are studied.

Radiation-induced magnetoresistance oscillation in a two-dimensional electron gas in Faraday geometry.

Abstract: Microwave-radiation induced giant magnetoresistance oscillations recently discovered in high-mobility two-dimensional electron systems are analyzed theoretically. Multiphoton-assisted impurity scatterings are shown to be the primary origin of the oscillation. Based on a theory which considers the interaction of electrons with electromagnetic fields and the effect of the cyclotron resonance in Faraday geometry, we are able not only to reproduce the correct period, phase, and the negative resistivity of the main oscillation, but also to predict the secondary peaks and additional maxima and minima observed in the experiments. These peak-valley structures are identified to relate, respectively, to single-, double-, and triple-photon processes.

Synthesis of force-closure grasps on 3-D objects based on the Q distance

Abstract: The synthesis of force-closure grasps on three-dimensional (3-D) objects is a fundamental issue in robotic grasping and dextrous manipulation. In this paper, a numerical force-closure test is developed based on the concept of Q distance. With some mild and realistic assumptions, the proposed test criterion is differentiable almost everywhere and its derivative can be calculated exactly. On this basis, we present an algorithm for planning force-closure grasps, which is implemented by applying descent search to the proposed numerical test in the grasp configuration space. The algorithm is generally applicable to planning optimal force-closure grasps on 3-D objects with curved surfaces and with arbitrary number of contact points. The effectiveness and efficiency of the algorithm are demonstrated by using simulation examples.

Nonlinear bending analysis of shear deformable functionally graded plates subjected to thermo-mechanical loads under various boundary conditions

Abstract: Nonlinear bending analysis of shear deformable functionally graded plates subjected to thermo-mechanical loads and under various boundary conditions is presented. Theoretical formulations are based on Reddy's higher order shear deformation plate theory and include the thermal effects due to temperature rise. Material properties are assumed to be temperature-dependent and graded in the thickness direction according to a power law distribution in terms of the volume fractions of the constituents. The temperature field considered is assumed to be uniform in the XY plane and through the plate thickness. The plate may be clamped or simply supported on two opposite edges with the remaining others being either free, simply supported or clamped. A semi-numerical approach, which makes use of multi-parameter perturbation technique, one-dimensional differential quadrature approximation and Galerkin method, is employed to calculate the nonlinear bending of the plates. Numerical results for silicon nitride/stainless steel rectangular plates are given in dimensionless graphical forms. The roles played by the constituent volume fraction index, temperature rise, character of out-of-plane boundary conditions and in-plane constraints, width-to-thickness ratio as well as plate aspect ratio are studied.

Fuzzy reasoning Petri nets

Abstract: This paper presents a fuzzy reasoning Petri net (FRPN) model to represent a fuzzy production rule-based system. The issues of how to represent and reason about rules containing negative literals are addressed in the proposed PN model. The execution rules based on the model are defined formally using the operators in max-algebra. Then, a fuzzy reasoning algorithm is proposed to perform fuzzy reasoning automatically. The algorithm is consistent with the matrix equation expression method in the traditional PNs and allows one to exploit the maximum parallel reasoning potential embedded in the model. The legitimacy and feasibility of the proposed approach are proved and validated through a turbine fault diagnosis expert system.