Showing papers by "Donghua University published in 2005"
TL;DR: In this article, the homotopy perturbation method is applied to the search for traveling wave solutions of nonlinear wave equations and some examples are given to illustrate the determination of the periodic solutions or the bifurcation curves of the nonlinear Wave equations.
Abstract: The homotopy perturbation method is applied to the search for traveling wave solutions of nonlinear wave equations. Some examples are given to illustrate the determination of the periodic solutions or the bifurcation curves of the nonlinear wave equations.
1,202 citations
TL;DR: In this paper, a simple but effective iteration method is proposed to search for limit cycles or bifurcation curves of nonlinear equations, and some examples are given to illustrate its convenience and effectiveness.
Abstract: In this paper a simple but effective iteration method is proposed to search for limit cycles or bifurcation curves of nonlinear equations. Some examples are given to illustrate its convenience and effectiveness.
315 citations
TL;DR: Theoretical analysis in the literature predicted three types of instabilities for an electrically driven jet: the axisymmetric Rayleigh instability, the electric field-induced axymmetric, and whipping instability as discussed by the authors.
Abstract: Ultrafine fibers produced by electrospinning often exhibit bead-on-string structures, which have generally been considered to be undesirable “by-products” or defects. Theoretical analysis in the literature predicted three types of instabilities for an electrically driven jet: the axisymmetric Rayleigh instability, the electric field-induced axisymmetric, and whipping instability. The process of bead formation revealed that the formation of a beaded structure resulted from axisymmetric deformation and flow of the jet. Applied voltage, solution surface tension, and conductivity (or jet charge density carried by the moving jet) were theoretically demonstrated to be important for jet axisymmetric instabilities. Experimental results revealed that these parameters influenced the formation of beaded fibers in the same manner as they did for the axisymmetric instabilities. As a result, the axisymmetric instabilities were considered to be the most likely mechanism of beaded fibers formation during electrospinning. POLYM. ENG. SCI., 45:704–709, 2005. © 2005 Society of Plastics Engineers
312 citations
Posted Content•
TL;DR: In this article, a total of 378 executives from 105 organizations in China completed measures of conflict management (cooperative, competitive, and avoiding) and productive conflict (an outcome of conflict), and 105 CEOs from these firms indicated their team's effectiveness and their organization's innovativeness.
Abstract: Top management teams may be critical for developing organizations that can keep abreast of marketplace changes and innovate. Several streams of strategy research have argued that conflict and diversity promote top management team effectiveness. This study proposes that how top management teams manage conflict can greatly contribute to their effective leadership of organizational innovation. A total of 378 executives from 105 organizations in China completed measures of conflict management (cooperative, competitive, and avoiding) and productive conflict (an outcome of conflict). Separately, 105 CEOs from these firms indicated their team's effectiveness and their organization's innovativeness. Results support the theory that conflict management can contribute to making top management teams effective. Structural equation analysis suggests that cooperative conflict management promotes productive conflict and top management team effectiveness that in turn result in organizational innovation. These results, coupled with previous research, were interpreted as suggesting that cooperative conflict management is an important contributor to effective top management teams even in the collectivist culture of China.
275 citations
TL;DR: This letter considers the robust finite-horizon filtering problem for a class of discrete time-varying systems with missing measurements and norm-bounded parameter uncertainties, and shows that the desired filter can be obtained in terms of the solutions to two discrete Riccati difference equations.
Abstract: In this letter, we consider the robust finite-horizon filtering problem for a class of discrete time-varying systems with missing measurements and norm-bounded parameter uncertainties. The missing measurements are described by a binary switching sequence satisfying a conditional probability distribution. An upper bound for the state estimation error variance is first derived for all possible missing observations and all admissible parameter uncertainties. Then, a robust filter is designed, guaranteeing that the variance of the state estimation error is not more than the prescribed upper bound. It is shown that the desired filter can be obtained in terms of the solutions to two discrete Riccati difference equations, which are of a form suitable for recursive computation in online applications. A simulation example is presented to show the effectiveness of the proposed approach by comparing to the traditional Kalman filtering method.
189 citations
TL;DR: In this article, a simple but effective iteration method is proposed to search for limit cycles or bifurcation curves of delay-differential equations, and an example is given to illustrate its convenience and effectiveness.
146 citations
TL;DR: In this paper, a method to measure the Young's modulus of a single electrospun polyacrylonitrile (PAN) fiber is reported. But the method is based on the bending of the fiber attached to an atomic force microscopy (AFM) cantilever.
Abstract: A method to measure the Young's modulus of a single electrospun polyacrylonitrile (PAN) fiber is reported. The Young's modulus can be calculated from the force-displacement curves obtained by the bending of a single fiber attached to an atomic force microscopy (AFM) cantilever. It is suggested that the high modulus of electrospun fibers is caused by the orientation of molecular chains, which is confirmed by wide-angle X-ray diffraction (WAXD) measurements. The communication will provide a basic understanding of the relationship between mechanical properties and structures of electrospun fibers.
137 citations
TL;DR: In this paper, the effects from the preparation of glyoxal solution, e.g., concentration and pH, and the reaction condition, such as time and temperature, were studied.
135 citations
TL;DR: In this article, a polyacrylonitrile (PAN) nanofibers with diameters in the range of 130-280nm were obtained by electrospinning of PAN/DMF solution, and PAN precursors were investigated by scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), infrared spectrometer (IR) and differential scanning calorimeter (DSC).
132 citations
TL;DR: Three pseudo amino acid components are introduced via Lyapunov index, Bessel function, Chebyshev filter that can be more efficiently used to deal with the chaos and complexity in protein sequences, leading to a higher success rate in predicting protein subcellular location.
Abstract: With the avalanche of new protein sequences we are facing in the post-genomic era, it is vitally important to develop an automated method for fast and accurately determining the subcellular location of uncharacterized proteins. In this article, based on the concept of pseudo amino acid composition (Chou, K.C. Proteins: Structure, Function, and Genetics, 2001, 43: 246–255), three pseudo amino acid components are introduced via Lyapunov index, Bessel function, Chebyshev filter that can be more efficiently used to deal with the chaos and complexity in protein sequences, leading to a higher success rate in predicting protein subcellular location.
131 citations
TL;DR: In this paper, the modified Lindstedt-Poincare method is applied to the nonlinear oscillators with discontinuities and only one iteration leads to high accuracy of the solution.
Abstract: In the paper, J.H. He's modified Lindstedt–Poincare method is applied to the nonlinear oscillators with discontinuities. Only one iteration leads to high accuracy of the solution.
TL;DR: In this article, the well-known Chauchy's inequality is applied to prediction of critical length of the straight jet in electrospinning, and a critical relationship between radius r of jet and the axial distance z from nozzle is obtained.
TL;DR: With biological sequences entering into databanks rapidly increasing in the post-genomic era, it is anticipated that the cellular automata image will become a very useful vehicle for investigation into their key features, identification of their function, as well as revelation of their “fingerprint”.
Abstract: A novel approach to visualize biological sequences is developed based on cellular automata (Wolfram, S. Nature 1984, 311, 419–424), a set of discrete dynamical systems in which space and time are discrete. By transforming the symbolic sequence codes into the digital codes, and using some optimal space-time evolvement rules of cellular automata, a biological sequence can be represented by a unique image, the so-called cellular automata image. Many important features, which are originally hidden in a long and complicated biological sequence, can be clearly revealed thru its cellular automata image. With biological sequences entering into databanks rapidly increasing in the post-genomic era, it is anticipated that the cellular automata image will become a very useful vehicle for investigation into their key features, identification of their function, as well as revelation of their “fingerprint”. It is anticipated that by using the concept of the pseudo amino acid composition (Chou, K.C. Proteins: Structure, Function, and Genetics, 2001, 43, 246–255), the cellular automata image approach can also be used to improve the quality of predicting protein attributes, such as structural class and subcellular location.
TL;DR: On the basis of combination of recurrent BP networks and wavelet analysis, a model is developed for more accurate forecasts of solar irradiance and the accuracy of the method is more satisfactory than that of the methods reported before.
TL;DR: Some generalized variational principles for ion-acoustic plasma waves were obtained by He's semi-inverse method as discussed by the authors, which has profound implications in physical understandings, explaining the interaction between various variables in an energy view and the existence of conservation law.
Abstract: Some generalized variational principles are obtained for ion-acoustic plasma waves by He's semi-inverse method. The obtained variational principle has profound implications in physical understandings, explaining the interaction between various variables in an energy view and the existence of conservation law.
TL;DR: In this paper, a variational model for (2 + 1 ) -dimensional Broer-Kaup equations was established by the semi-inverse method, and the model was used for (1 + 2 )-dimensional turbo jet engines.
TL;DR: In this paper, the authors obtained a sufficient condition for the existence of the solutions of the fractional differential equation D α x = f ( t, x ), where α ∈ ( 0, 1 ) and f( t, x ) is a given function.
TL;DR: In this paper, the ultra-high molecular weight polyethylene (UHMWPE)-carbon nanotubes (CNTs) composite fibers were prepared by gel spinning and the results showed that there was no obvious agglomerating of CNTs in obtained composite fibers and consequently a good interaction between CNT and UHMW PE matrix was also established.
TL;DR: Based on the power of cellular automata in treating complex systems with simple rules, a novel method to present HBV gene image has been introduced and the results show that the images obtained can very efficiently simulate the effects of the gene missense mutation on the virus replication.
TL;DR: In this article, the polymerization of NIPAM and crosslinker methylene bisacrylamide around the surface of PCL nanoparticles is localized and converted to hollow PNIPAM spheres by degrading the PCL core with an enzyme.
Abstract: Poly(e-caprolactone)/poly(N-isopropylacrylamide) (PCL/PNIPAM) core–shell particles are obtained by localizing the polymerization of NIPAM and crosslinker methylene bisacrylamide around the surface of PCL nanoparticles. The resultant particles are converted to hollow PNIPAM spheres by simply degrading the PCL core with an enzyme. The hollow spheres are thermosensitive and display a reversible swelling and de-swelling at ∼ 32 °C.
TL;DR: In this paper, the electrical properties of the composites were characterized by means of electrical conductivity measurements and the phase structures were investigated via scanning electron microscopy (SEM), X-ray diffraction (XRD), FT-IR spectroscopy, differential scanning calorimetry (DSC), and dynamical mechanical analysis (DMA).
TL;DR: The resultant hollow spheres are pH- and salt-responsive: there is a substantial volume increase when pH changes from acid to base, and vice versa, and this volume-pH-dependence is found to be completely reversible provided the effect of ionic strength is excluded.
Abstract: According to our "block-copolymer-free" strategy for self-assembly of polymers, noncovalently connected micelles (NCCM) with poly(epsilon-caprolactone) (PCL) as the core and poly(acrylic acid) (PAA) as the shell in aqueous solutions were attained due to specific interactions between the component polymers. The micellar structure was then locked in by the reaction of PAA with diamine. Afterward, hollow spheres based on PAA network were obtained by either core degradation with lipase or core dissolution with dimethylformamide of the cross-linked micelles. The cavitation process was monitored by dynamic light scattering, which indicated a mass decrease and size expansion. The hollow structure is confirmed by transmission electron microscopy observations. The resultant hollow spheres are pH- and salt-responsive: there is a substantial volume increase when pH changes from acid to base, and vice versa. The volume change takes place dramatically over the pH-range from 5.8 to 7.5. Furthermore, this volume-pH-dependence is found to be completely reversible provided the effect of ionic strength is excluded. The volume change can be adjusted by changing the shell thickness and the cross-linking degree of the hollow spheres. The salt effect on the hollow sphere size depends on pH: with increasing salt concentration the size shows an increase, a decrease, and a little change in acidic, basic, and neutral media, respectively.
TL;DR: In this article, a functional textile with the "guest-host" effect may be achieved by anchoring the inclusion compound in order to improve the physicochemical properties of the textile.
Abstract: Fragrance compounds and essential oils are chosen carefully taking advantage of research works in aromatherapy. Considering their volatile nature, the fragrance molecules have to be formed as inclusion compounds with cyclodextrin molecules in order to retain fragrances for a long time. To prepare aromatherapeutic textiles, β-cyclodextrin is the first choice as the host molecule, because β-cyclodextrin molecules are capable of forming inclusion compounds with organic compounds that fit into their own cone-shaped hydrophobic cavities. As a result of the inclusion, the physicochemical properties of the compounds are changed; for example, the vapor pressure of the volatile substance is reduced and the stabilities against light and air are enhanced. The functional textile with the “guest-host” effect may be achieved by anchoring the inclusion compound. The sedative effects for emotion and the pharmaceutical effects of essential oils are shown in detail. X-ray powder diffraction spectrum shows that lavender oil...
TL;DR: In this paper, three criterions for determining suitable kernels for smoothed particle hydrodynamics (SPH) particle approximation equations for functions and their derivatives are proposed to evaluate the accuracy of computation.
TL;DR: In this article, a modified equation for charge conservation in electrospinning is suggested, and a nonlinear relation between the electric current of charged jet and the solution flow rate is obtained.
TL;DR: In this article, pH and temperature-responsive hydrogels based on linear sodium alginate and crosslinked poly(N-isopropylacrylamide) (PNIPAAm) were prepared by semi-interpenetrating network (semi-IPN) technique.
Abstract: In this study, pH- and temperature-responsive hydrogels based on linear sodium alginate (SA) and crosslinked poly(N-isopropylacrylamide) (PNIPAAm) were prepared by semi-interpenetrating network (semi-IPN) technique. The dually responsive hydrogels were characterized by FTIR, DSC, and SEM, and their temperature- and pH-responsive behaviors were investigated by measuring equilibrium swelling ratios and pulsatile swelling experiments. The results showed that these hydrogels underwent volume phase transition at around 33°C irrespective of the pH value of the medium, but their pH sensitivity was evident only below their volume phase transition temperature. Under basic conditions, the swelling ratios of SA/PNIPAAm semi-IPN hydrogels were greater than that of pure PNIPAAm hydrogel and increased with increasing SA content incorporated into the hydrogels, but the case was inverse under acidic conditions. The pulsatile swelling experiments indicated that the higher the SA content in SA/PNIPAAm semi-IPN hydrogels, the faster the response rate to both pH and temperature change. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1931–1940, 2005
TL;DR: In this article, the uniaxial tensile properties of 4-step 3D braided E-Glass/epoxy composites at quasi-static (0.001/s) and high strain rates (up to 2800/s), respectively, were tested with MTS and split Hopkinson tension bar (SHTB), respectively.
Abstract: The uniaxial tensile properties of 4-step 3D braided E-Glass/epoxy composites at quasi-static (0.001/s) and high strain rates (up to 2800/s) were tested with MTS and split Hopkinson tension bar (SHTB), respectively. From the stress–strain curves of the composites at various strain rates, it is shown that the 3D braided composite is a kind of the rate-sensitive material. The uniaxial tensile stiffness and failure stress increase with the increase of the strain rate, while the failure strain decreases. The fractograph of 3D braided composites depicts the 3D braided composites fail in a more brittle mode in tension at high strain rates. More experiments should be conducted to establish the constitutive equation of 3D braided composites at various strain rates.
TL;DR: By using electrospinning technique, beaded, cylinder shaped and ribbon like ultra-fine silk fibroin (SF) fibers were obtained from its concentrated aqueous solution under different processing conditions.
Abstract: By using electrospinning technique, beaded, cylinder shaped and ribbon like ultra-fine silk fibroin (SF) fibers were obtained from its concentrated aqueous solution under different processing conditions. These fibers had an average diameter of 700 nm and were characterized by scanning electron microscopy (SEM), Wide-angle X-ray diffraction (WAXD) and Raman spectroscopy. It was found that the morphology and the secondary structure of the as-spun SF fibers were strongly influenced by the solution concentration, as well as the processing voltage. By adjusting these technological parameters, β-sheet conformation and silk II crystal structure of the SF fibers can be formed without any post-treatment.
Journal Article•
TL;DR: In this paper, a research attempt at obtaining aromatherapic textiles using the fragrance with β-cyclodextrin inclusion compounds was carried out, together with the broad background of research into aromachology investigation.
Abstract: A research attempt at obtaining aromatherapic textiles which we carried out is presented, together with the broad background of research into aromachology investigation. We developed aromatherapic textiles using the fragrance with β-cyclodextrin inclusion compounds. The sedative effects for emotion and the pharmaceutical effects of essential oils are presented in detail, on the basis of the achievements of aromachology and aromatherapy. Research shows that the effects of fragrance on humans are based on a great deal of medical experience. β-cyclodextrin was chosen for the aromatherapic textile as host molecule, because it exhibits qualities which are beneficial for the human body. β-cyclodextrins mol ecules are capable of forming inclusion compounds with fragrances that fit into the coneshaped hydrophobic cavity. As a result, the release-fragrance rates are greatly decreased. The fragrance inclusion compounds are fixed onto cotton with a low temperature binder by the conventional pad-thermofixed method. The fragrance-release rates are related to the nature of the fragrance oils themselves. The results of sensorial evaluations show that the perfume of fabric is sensed for over 30 days. An aromatherapic textile could be achieved by means of the fragrance with β-cyclodextrin inclusion compounds in this way.
01 Sep 2005
TL;DR: The purpose of this problem is to design an output feedback controller such that, for all admissible parameter uncertainties and all possible incomplete observations, the system state of the closed-loop system is mean square bounded, and the steady-state variance of each state is not more than the individual prescribed upper bound.
Abstract: In this paper, we are concerned with a new control problem for uncertain discrete-time stochastic systems with missing measurements. The parameter uncertainties are allowed to be norm-bounded and enter into the state matrix. The system measurements may be unavailable (i.e., missing data) at any sample time, and the probability of the occurrence of missing data is assumed to be known. The purpose of this problem is to design an output feedback controller such that, for all admissible parameter uncertainties and all possible incomplete observations, the system state of the closed-loop system is mean square bounded, and the steady-state variance of each state is not more than the individual prescribed upper bound. We show that the addressed problem can be solved by means of algebraic matrix inequalities. The explicit expression of the desired robust controllers is derived in terms of some free parameters, which may be exploited to achieve further performance requirements. An illustrative numerical example is provided to demonstrate the usefulness and flexibility of the proposed design approach.