Showing papers by "Shanghai Jiao Tong University published in 2002"

Synchronization in scale-free dynamical networks: robustness and fragility

Abstract: Recently, it has been demonstrated that many large complex networks display a scale-free feature, that is, their connectivity distributions are in the power-law form. In this paper, we investigate the synchronization phenomenon in scale-free dynamical networks. We show that if the coupling strength of a scale-free dynamical network is greater than a positive threshold, then the network will synchronize no matter how large it is. We show that the synchronizability of a scale-free dynamical network is robust against random removal of nodes, but is fragile to specific removal of the most highly connected nodes.

Pinning control of scale-free dynamical networks

Abstract: Recently, it has been demonstrated that many large complex networks display a scale-free feature, that is, their connectivity distributions have the power-law form. In the present work, control of a scale-free dynamical network by applying local feedback injections to a fraction of network nodes is investigated. The specifically and randomly pinning schemes are considered. The specifically pinning of the most highly connected nodes is shown to require a significantly smaller number of local controllers as compared to the randomly pinning scheme. The method is applied to an array of Chua's oscillators as an example.

Synchronization in small-world dynamical networks

Abstract: We investigate synchronization in a network of continuous-time dynamical systems with smallworld connections. The small-world network is obtained by randomly adding a small fraction of connection in an originally nearest-neighbor coupled network. We show that, for any given coupling strength and a suciently large number of cells, the small-world dynamical network will synchronize, even if the original nearest-neighbor coupled network cannot achieve synchronization under the same condition.

Complex networks: topology, dynamics and synchronization

Abstract: Dramatic advances in the field of complex networks have been witnessed in the past few years. This paper reviews some important results in this direction of rapidly evolving research, with emphasis...

Localized excitations in (2+1)-dimensional systems.

Abstract: By means of a special variable separation approach, a common formula with some arbitrary functions has been obtained for some suitable physical quantities of various (2+1)-dimensional models such as the Davey-Stewartson (DS) model, the Nizhnik-Novikov-Veselov (NNV) system, asymmetric NNV equation, asymmetric DS equation, dispersive long wave equation, Broer-Kaup-Kupershmidt system, long wave-short wave interaction model, Maccari system, and a general (N+M)-component Ablowitz-Kaup-Newell-Segur (AKNS) system. Selecting the arbitrary functions appropriately, one may obtain abundant stable localized interesting excitations such as the multidromions, lumps, ring soliton solutions, breathers, instantons, etc. It is shown that some types of lower dimensional chaotic patterns such as the chaotic-chaotic patterns, periodic-chaotic patterns, chaotic line soliton patterns, chaotic dromion patterns, fractal lump patterns, and fractal dromion patterns may be found in higher dimensional soliton systems. The interactions between the traveling ring type soliton solutions are completely elastic. The traveling ring solitons pass through each other and preserve their shapes, velocities, and phases. Some types of localized weak solutions, peakons, are also discussed. Especially, the interactions between two peakons are not completely elastic. After the interactions, the traveling peakons also pass through each other and preserve their velocities and phases, however, they completely exchange their shapes.

A new Boussinesq method for fully nonlinear waves from shallow to deep water

Abstract: A new method valid for highly dispersive and highly nonlinear water waves is presented. It combines a time-stepping of the exact surface boundary conditions with an approximate series expansion solution to the Laplace equation in the interior domain. The starting point is an exact solution to the Laplace equation given in terms of infinite series expansions from an arbitrary z-level. We replace the infinite series operators by finite series (Boussinesq-type) approximations involving up to fifth-derivative operators. The finite series are manipulated to incorporate Pade approximants providing the highest possible accuracy for a given number of terms. As a result, linear and nonlinear wave characteristics become very accurate up to wavenumbers as high as kh = 40, while the vertical variation of the velocity field becomes applicable for kh up to 12. These results represent a major improvement over existing Boussinesq-type formulations in the literature. A numerical model is developed in a single horizontal dimension and it is used to study phenomena such as solitary waves and their impact on vertical walls, modulational instability in deep water involving recurrence or frequency downshift, and shoaling of regular waves up to breaking in shallow water.

Preparation of polychrome silver nanoparticles in different solvents

Abstract: Polychrome silver nanoparticles have been prepared by a soft solution approach under microwave irradiation from a solution of silver nitrate (AgNO3) in the presence of poly(N-vinyl-2-pyrrolidone) without any other reducing agent. Different morphologies of silver colloids with charming colors could be obtained using different solvents as the reaction medium. The structures of the silver colloids were determined by X-ray powder diffraction. UV-Vis spectroscopy was used to follow the reaction process and to characterize the optical properties of the resultant silver colloids. The influence of the solvent on the morphology of silver was investigated.

Analytic solutions of the temperature distribution in Blasius viscous flow problems

Abstract: We apply a new analytic technique, namely the homotopy analysis method, to give an analytic approximation of temperature distributions for a laminar viscous flow over a semi-infinite plate. An explicit analytic solution of the temperature distributions is obtained in general cases and recurrence formulae of the corresponding constant coefficients are given. In the cases of constant plate temperature distribution and constant plate heat flux, the first-order derivative of the temperature on the plate at the 30th order of approximation is given. The convergence regions of these two formulae are greatly enlarged by the Pade technique. They agree well with numerical results in a very large region of Prandtl number 1[les ]Pr[les ]50 and therefore can be applied without interpolations.

Conceptual Graph Matching for Semantic Search

Abstract: Semantic search becomes a research hotspot. The combined use of linguistic ontologies and structured semantic matching is one of the promising ways to improve both recall and precision. In this paper, we propose an approach for semantic search by matching conceptual graphs. The detailed definitions of semantic similarities between concepts, relations and conceptual graphs are given. According to these definitions of semantic similarity, we propose our conceptual graph matching algorithm that calculates the semantic similarity. The computation complexity of this algorithm is constrained to be polynomial. A prototype of our approach is currently under development with IBM China Research Lab.

A note on observers for Lipschitz nonlinear systems

Abstract: This note deals with the design of reduced-order observers for Lipschitz nonlinear systems. It shows that the conditions under which a full-order observer exists also guarantee the existence of a reduced-order observer. A design method of the reduced-order observer that is dependent on the solution of the Riccati equation is then presented and an example is given to illustrate effects of the design method.

Measurements of the cross section for e(+)e(-) --> hadrons at center-of-mass energies from 2 to 5 GeV.

Abstract: We report values of $R\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\mathrm{hadrons})/\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})$ for 85 center-of-mass energies between 2 and $5\mathrm{GeV}$ measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider.

Photocatalytic Hydrogen Evolution from Water on Nanocomposites Incorporating Cadmium Sulfide into the Interlayer

Abstract: An efficient hydrogen evolution was achieved on layered metal oxides incorporating CdS in the interlayer, which were prepared by direct cation exchange reaction and a sulfurization process. The photocatalytic activity of the composites intercalating CdS was superior to those of neat CdS and the physical mixture of CdS and metal oxides. The photocatalytic activities strongly depend on the structure of the layered metal oxides and the solutions containing S2- ions as hole scavengers. The substitution of Nb for partial Ti in the layered composite of K2Ti4O9 gave rise to the increase in the content of CdS incorporated in the interlayer, and the quick transference of the electrons in a CdS nano-pillar through the layer into the surface of photocatalysts. Thus the photocatalytic activity was enhanced. Addition of sulfite ions, which efficiently suppress the disulfide formation, allowed hydrogen to evolve at a higher rate. As a hole scavenger, Na2S was superior to Na2SO3 with respect to increasing the hydrogen e...

A state-of-the-art review on fatigue life prediction methods for metal structures

Abstract: Metals are the most widely used materials in engineering structures, and one of the most common failure modes of metal structures is fatigue failure. Although metal fatigue has been studied for more than 160 years, many problems still remain unsolved. In this article, a state-of-the-art review of metal fatigue is carried out, with particular emphasis on the latest developments in fatigue life prediction methods. All factors which affect the fatigue life of metal structures are grouped into four categories: material, structure, loading, and environment. The effects of these factors on fatigue behavior are also addressed. Finally, potential problems to be resolved in the near future are pointed out.

CLOPE: a fast and effective clustering algorithm for transactional data

Abstract: This paper studies the problem of categorical data clustering, especially for transactional data characterized by high dimensionality and large volume. Starting from a heuristic method of increasing the height-to-width ratio of the cluster histogram, we develop a novel algorithm -- CLOPE, which is very fast and scalable, while being quite effective. We demonstrate the performance of our algorithm on two real world datasets, and compare CLOPE with the state-of-art algorithms.

High-Resolution Observations of the Elliptical Galaxy NGC 4636 with the Reflection Grating Spectrometer on Board XMM-Newton

Abstract: We present the first high spectral resolution X-ray observation of the giant elliptical galaxy NGC 4636, obtained with the reflection grating spectrometer on board the XMM-Newton Observatory. The resulting spectrum contains a wealth of emission lines from various charge states of oxygen, neon, magnesium, and iron. Examination of the cross-dispersion profiles of several of these lines provides clear, unambiguous evidence of resonance scattering by the highest oscillator strength lines, as well as a weak temperature gradient in the inner regions of the interstellar medium. We invoke a sophisticated new Monte Carlo technique that allows us to properly account for these effects in performing quantitative fits to the spectrum. Our spectral fits are not subject to many of the systematics that have plagued earlier investigations. The derived metal abundances are higher than have usually been inferred from prior, lower spectral resolution observations of this source, but are still incompatible with conventional chemical-enrichment models of elliptical galaxies. In addition, our data are incompatible with standard cooling-flow models for this system; our derived upper limit to the mass deposition rate is below the predicted value by a factor of 3-5.

Compatibility of soluble polyimide/silica hybrids induced by a coupling agent

Abstract: In this paper, a new type of soluble polyimide/silica (PI/SiO2) hybrid was prepared by the sol−gel process. The coupling agent γ-glycidyloxypropyltrimethoxysilane (GOTMS) was chosen to enhance the compatibility between the polyimide (PI) and silica (SiO2). Furthermore, the effects of the coupling agent on the morphologies and properties of the PI/SiO2 hybrids were investigated using UV−vis and FTIR spectroscopies and SEM. The densities and solubilities of the PI/SiO2 hybrids were also measured. The results show that the size of the silica particle was markedly reduced by the introduction of the coupling agent, which made the PI/SiO2 hybrid films become transparent. The solubility of the PI/SiO2 hybrid was also improved by the coupling agent. In addition, all of these effects became even more pronounced with increased amounts of the coupling agent. The thermal properties of the compatibilized PI/SiO2 hybrids were investigated by DSC and TGA. Moreover, their mechanical properties were also characterized. Th...

Detection of aberrant p16 methylation in the serum of colorectal cancer patients.

Abstract: Purpose : This study was designed to detect aberrant p16 promoter methylation in the serum of patients with colorectal cancer (CRC) and to explore the possibility of using this assay in early detection or as a prognostic marker of CRC patients. Experimental Design : Methylation-specific PCR was used to detect p16 methylation in DNA extracted from 52 CRCs and matching serum samples and control serum samples from 34 patients with adenomatous polyps and 10 healthy individuals. The association of p16 hypermethylation in serum DNA of CRC patients with clinicopathological characteristics was then analyzed. Results : P16 hypermethylation was found in 20 of 52 (38%) CRCs. Among the 20 cases with aberrant methylation in the tumor tissues, similar changes were also detected in the serum of 14 (70%) cases. No methylated p16 sequences were detected in the peripheral serum of the other 32 CRC cases without these changes in the tumor, in 34 patients with adenomatous polyps, or in 10 healthy control subjects. Clinicopathological analysis revealed that p16 methylation in serum was significantly associated with later Dukes’ stage ( P = 0.03). Conclusions : This assay offers a potential means for the serum-based detection and/or monitoring of CRC patients.

Detection of aberrant p16 methylation in the serum of colorectal cancer patients.

Abstract: OBJECTIVES To detect aberrant p16 promoter methylation in serum of patients with colorectal cancer (CRC), and to explore the possibility of using this assay in early detection or as a prognostic marker. METHODS Methylation-specific PCR was used to detect p16 methylation in DNA extracted from 52 CRCs and corresponding serum samples. Serum samples from 34 patients with adenomatous polyps and 10 healthy individuals were used as controls. The association of p16 hypermethylation in serum DNA of CRC patients with clinicopathological characteristics was analyzed. RESULTS p16 methylation was found in 38% (20 of 52) of CRC tissues. Among the 20 patients with aberrant methylation in the tumor tissues, similar changes were also detected in the serum of 14 (70%) patients. No methylated p16 sequences were detected in the peripheral serum of the 32 CRC patients without these changes in the tumor, in 34 paitents with adenomatous polyps, or in 10 healthy controls. Clinicopathological analysis revealed that p16 methylation in serum was significantly associated with later Dukes' stage (chi(2) = 5.7, P = 0.03). CONCLUSION This assay offers a potential means for the serum-based detection and/or monitoring of CRC patients.

Optimum multiple tuned mass dampers for structures under the ground acceleration based on ddmf and admf

Abstract: Multiple tuned mass dampers (MTMD) consisting of many tuned mass dampers (TMDs) with a uniform distribution of natural frequencies are taken into consideration for attenuating undesirable vibration of a structure under the ground acceleration. A study is conducted to search for the preferable MTMD which performs better and is easily manufactured from the five available models (i.e. MTMD-1 -MTMD-5), which comprise various combinations of the stiffness, mass, damping coefficient and damping ratio in the MTMD. The major objective of the present study then is to evaluate and compare the control performance of these five models. The structure is represented by its mode-generalized system in the specific vibration mode being controlled by adopting the mode reduced-order approach. The optimum parameters of the MTMD-1 - MTMD-5 are investigated to reveal the influence of the important parameters on their effectiveness and robustness using a numerical searching technique. The parameters include the frequency spacing, average damping ratio, tuning frequency ratio, mass ratio and total number. The criteria selected for the optimum searching are the minimization of the maximum value of the displacement dynamic magnification factor (DDMF) and that of the acceleration dynamic magnification factor (ADMF) of the structure with the MTMD-1 - MTMD-5 (i.e. Min.Max.DDMF and Min.Max.ADMF). It is demonstrated that the optimum MTMD-1 and MTMD-4 yield approximately the same control performance, and offer higher effectiveness and robustness than the optimum MTMD-2, MTMD-3, and MTMD-5 in reducing the displacement and acceleration responses of structures. It is further demonstrated that for both the best effectiveness and robustness and the simplest manufacturing, it is preferable to select the optimum MTMD-1.

Rapid synthesis of dense Ti3SiC2 by spark plasma sintering

Abstract: Ti3SiC2 was rapidly synthesized and simultaneously consolidated from the starting mixture of Ti/Si/2TiC by spark plasma sintering (SPS) An intensive reaction leading to the formation of Ti3SiC2 occurred at the measured temperature of around 1200 °C, which is several hundreds degrees lower than that of conventional reactive hot pressing The phase composition of the product could be tailored by adjusting the process parameters An axisymmetric preferred orientation of the Ti3SiC2 grains with well-developed (008) planes was formed, resulting in an anisotropic hardness in respect to the textured product

'Streptomyces nanchangensis', a producer of the insecticidal polyether antibiotic nanchangmycin and the antiparasitic macrolide meilingmycin, contains multiple polyketide gene clusters.

Abstract: Several independent gene clusters containing varying lengths of type I polyketide synthase genes were isolated from 'Streptomyces nanchangensis' NS3226, a producer of nanchangmycin and meilingmycin. The former is a polyether compound similar to dianemycin and the latter is a macrolide compound similar to milbemycin, which shares the same macrolide ring as avermectin but has different side groups. Clusters A-H spanned about 133, 132, 104, 174, 122, 54, 37 and 59 kb, respectively. Two systems were developed for functional analysis of the gene clusters by gene disruption or replacement. (1) Streptomyces phage phiC31 and its derived vectors can infect and lysogenize this strain. (2) pSET152, an Escherichia coli plasmid with phiC31 attP site, and pHZ1358, a Streptomyces-Escherichia coli shuttle cosmid vector, both carrying oriT from RP4, can be mobilized from E. coli into NS3226 by conjugation. pHZ1358 was shown to be generally useful for generating mutant strains by gene disruption and replacement in NS3226 as well as in several other Streptomyces strains. A region in cluster A (approximately 133 kb) seemed to be involved in nanchangmycin production because replacement of several DNA fragments in this region by an apramycin resistance gene [aac3(IV)] gave rise to nanchangmycin non-producing mutants.

An analytic approximation of the drag coefficient for the viscous flow past a sphere

Abstract: We give an analytic solution at the 10th order of approximation for the steady-state laminar viscous #ows past a sphere in a uniform stream governed by the exact, fully non-linear Navier}Stokes equations. A new kind of analytic technique, namely the homotopy analysis method, is applied, by means of which Whitehead's paradox can be easily avoided and reasonably explained. Di!erent from all previous perturbation approximations, our analytic approximations are valid in the whole "eld of #ow, because we use the same approximations to express the #ows near and far from the sphere. Our drag coe$cient formula at the 10th order of approximation agrees better with experimental data in a region of Reynolds number R (30, which is considerably larger than that (R (5) of all previous theoretical ones. 2001 Elsevier Science Ltd. All rights reserved.