Showing papers by "Tongji University published in 2001"
TL;DR: In this article, the preparation, characterization, properties and applications of polypyrrole (PPY) are reviewed in detail according to the synthetic methods and their applications, and effects of various parameters such as doping anions, additives, and oxidant, on the PPY properties are also concerned.
Abstract: Polypyrrole (PPY) is one of the most promising materials for multifunctionalized applications. Preparation, characterization, properties and applications of PPYs are reviewed in this paper. In addition, the PPY composites are described in detail according to the synthetic methods and their applications. At the same time, effects of various parameters such as doping anions, additives, and oxidant, on the PPY properties are also concerned. The PPY films and membranes used for ion exchange, pervaporation, and gas separation are mentioned. In this review, ion exchange membranes are highlighted. Moreover, the further investigation of PPY composite membranes for oxygen enrichment is predicted. A total of 117 references are cited.
469 citations
TL;DR: In this article, an improved ZnCl 2 -chemical activation method was proposed to produce highly porous activated carbons from lignocellulosic materials, such as coconut shells and palm seeds.
319 citations
TL;DR: The potentiality of improving activated sludge mechanical dewaterability by the use of sulfuric acid to control its pH at 2.5 or together with a surfactant is suggested.
293 citations
TL;DR: Experimental results have shown that lower pH and higher concentration of dissolved oxygen favor the phenol degradation and that the presence of Fe2+ enhanced TOC removal of phenol solutions.
269 citations
TL;DR: In this paper, a simplified method for computing the rate of consolidation is presented by assuming that stone columns; (1) are free draining; (2) have higher drained elastic modulus than soft clay; and (3) are deformed 1D.
Abstract: Field observations and numerical studies demonstrated that stone columns could accelerate the rate of consolidation of soft clays. A simplified method for computing the rate of consolidation is presented in this paper by assuming that stone columns; (1) are free draining; (2) have higher drained elastic modulus than soft clay; and (3) are deformed 1D. The formats of the final solutions in vertical and radial flows are similar to those of the Terzaghi 1D solution and the Barron solution for drain wells in fine-grained soils, respectively. Modified coefficients of consolidation are introduced to account for effects of the stone column-soil modular ratio. The new solutions demonstrate stress transfer from the soil to stone columns and dissipation of excess pore water pressures due to drainage and vertical stress reduction during the consolidation. Comparisons between the results from this simplified method and the numerical study by Balaam and Booker in 1981 exhibit reasonable agreement, when the stress concentration ratio is in the practical range (2-6). The discrepancies in the results from these two methods are discussed. This paper also includes design charts and a design example.
262 citations
TL;DR: By the incorporation of methyl groups on the ancillary ligand of phen and bpy, different DNA-binding behaviors of complexes 1 and 2 were characterized.
Abstract: By the incorporation of methyl groups on the ancillary ligand of phen and bpy, different DNA-binding behaviors of complexes 1 and 2 were characterized. Different binding rates of the isomers of 2 with CT-DNA via CD spectra were observed through dialysis experiments but not with complex 1.
257 citations
TL;DR: In this paper, the Changjiang (Yangtze) River has formed a broad tide-dominated delta at its mouth during the Holocene sea-level highstand, and three boreholes (CM97, JS98, and HQ98) were obtained from Changjiang delta plain in 1997-1998 to clarify the characteristics of tidedominated delta sediments and architecture.
251 citations
TL;DR: In this paper, the authors presented the sedimentary facies and architecture of the estuary fill, based on the analysis of three sediment cores (CM97, JS98, and HQ98) obtained from the Changjiang delta plain.
235 citations
TL;DR: In this paper, the mesopore capacity and porosity were investigated by adsorption experiments using adsorbates with different molecular sizes (viz., phenol, methylene blue and erythrosine red).
233 citations
TL;DR: In this article, the effect of coarse aggregate type on the compressive strength, splitting tensile strength, fracture energy, characteristic length, and elastic modulus of concrete produced at different strength levels with 28-day target compressive strengths of 30, 60, and 90 MPa, respectively.
229 citations
TL;DR: In this paper, an analytical solution for the prediction of internal forces and displacements of a jointed segmental precast circular tunnel lining is presented, where the effects of joint stiffness on the performance of the tunnel lining are discussed.
Abstract: This paper presents an analytical solution for the prediction of internal forces and displacements of a jointed segmental precast circular tunnel lining. The effects of joint stiffness on the performance of the tunnel lining are discussed. The ‘force method’ is used to determine the internal forces and displacements of jointed tunnel lining. Five shield-driven tunnel cases are adopted to study the effects of joint stiffness, soil resistance, joint distribution and joint number on the internal forces and displacements of circular tunnels. Laboratory model tests are conducted to verify the proposed analytical solution. Copyright © 2001 John Wiley & Sons, Ltd.
TL;DR: In this paper, an analysis of over 6600 km of reflection seismic profiles on the northern continental margin of the South China Sea permit the recognition of four Quaternary high-frequency type 1 sequences of the 4th order, deposited during the past ca. 690kyr.
TL;DR: In this paper, an improved spectral representation method was proposed for digital simulation of the stochastic wind velocity field on long-span bridges, when the cross-spectral density matrix of the field is given.
Abstract: An improved algorithm is introduced in this paper for digital simulation of the stochastic wind velocity field on long-span bridges, when the cross-spectral density matrix of the field is given. The target wind velocity field is assumed to be a one-dimensional, multivariate, homogeneous stochastic process. The basic method of simulation used is the spectral representation method. It is improved by explicitly expressing Cholesky's decomposition of the cross-spectral density matrix in the form of algebraic formulas, then cutting off as many as possible of the cosine terms, so long as the accuracy of results is not affected. The fast Fourier transform technique is used to enhance the efficiency of computation. A numerical example of simulation for buffeting analysis is included in this paper to illustrate the improved method introduced. It is demonstrated that deviations between the simulated correlation functions and the target are sufficiently small and that the simulated power spectra are close to the target.
07 Oct 2001
TL;DR: The EM ofGM can be regarded as a special EM of HMM and the EM algorithm of GMM based on symbols is faster in implementation than the EM algorithms based on samples (or on observation) traditionally.
Abstract: The HMM (hidden Markov model) is a probabilistic model of the joint probability of a collection of random variables with both observations and states. The GMM (Gaussian mixture model) is a finite mixture probability distribution model. Although the two models have a close relationship, they are always discussed independently and separately. The EM (expectation-maximum) algorithm is a general method to improve the descent algorithm for finding the maximum likelihood estimation. The EM of HMM and the EM of GMM have similar formulae. Two points are proposed in this paper. One is that the EM of GMM can be regarded as a special EM of HMM. The other is that the EM algorithm of GMM based on symbols is faster in implementation than the EM algorithm of GMM based on samples (or on observation) traditionally.
TL;DR: Foraminifera from two cores off eastern Vietnam and the northwestern Philippines, where modern summer and winter monsoon-driven upwelling occurs in the South China Sea, respectively, were analyzed to evaluate the changes in paleoproductivity and upper water structure over the last 220,000 yr.
TL;DR: In this paper, the Kap Shui Mun Bridge is updated based on the field measured dynamic properties, and a comprehensive sensitivity study to demonstrate the effects of various structural parameters (including the connections and boundary conditions) on the modes of concern is first performed, according to which a set of structural parameters are then selected for adjustment.
Abstract: This paper presents the implementation of the finite-element model updating for the Kap Shui Mun Bridge, a 430 m main span double-deck cable-stayed bridge in Hong Kong. The dynamic characteristics of the bridge have been studied through both three-dimensional finite-element prediction and field vibration measurement previously. In this paper, the developed finite-element model is updated based on the field measured dynamic properties. A comprehensive sensitivity study to demonstrate the effects of various structural parameters (including the connections and boundary conditions) on the modes of concern is first performed, according to which a set of structural parameters are then selected for adjustment. The finite-element model is updated in an iterative fashion so as to minimize the differences between the predicted and the measured natural frequencies. The final updated finite-element model for the Kap Shui Mun Bridge is able to produce natural frequencies in good agreement with the measured ones, and can be helpful for a more precise dynamic response prediction.
TL;DR: In this article, a radial tidal sand ridge system (RTSRS) is deduced to be an ancient RTSRS that was formed during the Holocene regression, and gradually exposed and changed into land as the Changjiang and Huanghe deltas prograded.
TL;DR: In this article, an optimal control framework is used to determine implied volatility and make a rigorous mathematical analysis of this inverse problem. But the problem is to identify the coefficient of the second-order partial derivative in the equation with the PDE being non-divergent.
Abstract: In this paper, we use an optimal control framework to determine implied volatility and make a rigorous mathematical analysis of this inverse problem We also prove the approximate optimal solutions converge to the appropriate solutions for the original problem Being different from ordinary parameter identification problems, our problem is to identify the coefficient of the second-order partial derivative in the equation with the PDE being non-divergent
TL;DR: In this article, a batch of experiments were conducted to investigate anoxic biodegradation of five refractory nitrogeneous heterocyclic compounds, i.e., pyridine, indole, quinoline, isoquinoline, 2-methyl quinol, in coke plant wastewater.
TL;DR: In this article, the dynamic characteristics of a fairly long cable-stayed bridge in Hong Kong are studied using finite-element analysis and ambient vibration measurements, and the results show that, for the most part, a total of 31 modes can be correlated with a reasonable agreement, but frequency differences of the higher modes can range between 15 and 30%.
Abstract: The investigation of dynamic response for long-span cable-stayed bridges largely depends on a detailed understanding of their dynamic characteristics, such as the natural frequencies, mode shapes, and modal damping ratios. In this paper, the dynamic characteristics of a fairly long cable-stayed bridge in Hong Kong are studied using finite-element analysis and ambient vibration measurements. A three-dimensional finite-element model is first established for the bridge based on design drawings. The dynamic characteristics are then analyzed from the statically deformed configuration. Ambient vibration measurements are also conducted to obtain the dynamic characteristics of the bridge. Comparison between these two results shows that, for the most part, a total of 31 modes can be correlated with a reasonable agreement. However, the frequency differences of the higher modes can range between 15 and 30%. This implies that, if the measurement is more reliable, a finite-element model updating is necessary in order to achieve better correlation between these two results.
TL;DR: In this paper, a solution casting technique with chloroform as solvent has been used to produce poly(4-vinylpyridine) (PVP) with ethylcellulose (EC) membranes.
TL;DR: Both complexes have been found to promote the photocleavage of plasmid pBR 322 DNA, the hydroxyl radical (OH*) is suggested to be the reactive species responsible for the cleavage.
TL;DR: Foraminifers in intertidal sediments have distinctly different assemblages in the uppermost, mid-tidal (mangrove), lower, and subtidal zones.
TL;DR: In this paper, ammonium persulfate was used as an oxidant in boiling glacial acetic acid for chemically oxidative polymerization of o-phenylenediamine and 2,3-xylidine.
TL;DR: In this paper, a study on buffeting control of the Yangpu Bridge using a multiple tuned mass damper (MTMD) system is performed, which consists of a set of TMDs which are attached to the center region of the bridge's main span and are symmetrical about the center of the main span as well as about the central line along the bridge span.
TL;DR: A sedimentary succession more than 5800m thick, including the Lower Eocene to Lower Oligocene Fenghuoshan Group, Yaxicuo Group, and Wudaoliang Group, is widely distributed in the Hoh Xil piggyback basin, the largest Cenozoic sedimentary basin in the hinterland of the Tibetan plateau.
TL;DR: It is demonstrated that NF-kappaB activation is the underlying molecular mechanism for constitutive expression of E-selectin, VCAM-1, and ICam-1 on human B lymphocytes and plasma cells.
TL;DR: In this paper, the acoustic emission (AE) characteristics of concrete with different aggregate size distributions under uniaxial compression and three-point-bending were studied and parameters such as maximum aggregate size, compressive strain and fracture energies of different concretes were also measured and discussed.
TL;DR: In this paper, the surface residual stresses in steel rods made of the same material but with different heat treatments have been studied from Rayleigh wave velocity measurements using the laser ultrasonics technique and piezoelectric transducers.
Abstract: The surface residual stresses in steel rods made of the same material but with different heat treatments have been studied from Rayleigh wave velocity measurements using the laser ultrasonics technique and piezoelectric transducers. The Rayleigh wave velocities, both along the circumference and in the axis direction on the cylindrical surface of every rod, are measured and compared with one another in order to evaluate qualitatively the surface stress state for each rod. The experimental results clearly show that the Rayleigh wave velocities on the cylindrical surfaces of these rods are different, and the results obtained by laser ultrasound are in good agreement with those measured with piezoelectric transducers. From the measured velocities, different stress states have been identified for these rods according to the heat treatments they have undergone.
TL;DR: In this article, the stochastic orthogonal polynomial expansion method is extended with the pseudo-excitation method in order to obtain probabilistic information of structural response, such as the power spectral density, standard deviation function, etc.
Abstract: The stochastic orthogonal polynomial expansion method is extended with the pseudo-excitation method in this paper. This extension enables the stochastic orthogonal polynomial method to be readily used in the analysis of stochastic parameter structures under non-stationary random excitation. The probabilistic information of structural response, such as the power spectral density, standard deviation function, etc. can be obtained directly with this method. A dynamic condensation algorithm for order-expanded equation resulting from the orthogonal polynomial expansion method is also presented in this paper. The applicability of the proposed methodology is demonstrated by numerical examples.