Showing papers by "Dalian University of Technology published in 2003"
TL;DR: A new approach to structural topology optimization that represents the structural boundary by a level set model that is embedded in a scalar function of a higher dimension that demonstrates outstanding flexibility of handling topological changes, fidelity of boundary representation and degree of automation.
2,404 citations
TL;DR: In this paper, a brief summary of the texture in hexagonal structural materials is carried out, mainly dealing with the deformation and recrystallization texture as well as the anisotropy of textured hexagonal materials.
641 citations
TL;DR: In this paper, X-ray diffraction and atomic force microscopy were used to study the forming process and surface morphology of the TiO2 thin film on NiTi surgical alloy by sol-gel method.
266 citations
TL;DR: In this paper, the thermal entanglement in the two-qubit Heisenberg chain was investigated in the presence of an external magnetic field B and the interaction of the z component of two neighboring spins.
Abstract: The thermal entanglement in the Heisenberg $\mathrm{XYZ}$ chain is investigated in the presence of an external magnetic field B. In the two-qubit system, the critical magnetic field ${B}_{c}$ is increased by introducing the interaction of the z component of two neighboring spins ${J}_{z}.$ This interaction not only improves the critical temperature ${T}_{c},$ but also enhances the entanglement for a particular fixed B. We also analyze the pairwise entanglement between nearest neighbors in three qubits. The pairwise entanglement, for a fixed T, can become strong by controlling B and ${J}_{z}.$
195 citations
TL;DR: In this article, a new method for the growth of high-quality ZnO nanoparticles is presented, which is a novel, low-cost, and easy operation, using solid-state heat decomposition at low temperature.
Abstract: A new method for the growth of high-quality ZnO nanoparticles is presented here; it is a novel, low-cost, and easy operation. This approach, using solid-state heat decomposition at low temperature, allows one to produce ZnO nanoparticles with relatively high dispersivity. The optical properties of the ZnO nanoparticles have been investigated. It is demonstrated that ZnO nanoparticles show strong ultraviolet emission, while the low-energy visible emission is nearly fully quenched at room temperature. This is a result of the high quality of the ZnO. X-ray diffraction patterns reveal that the ZnO nanoparticles have polycrystalline hexagonal wurtzite structure. The Raman spectrum shows a typical resonant multi-phonon form for the ZnO nanoparticles. Similar synthesis routes for other metal oxide nanoparticles may be possible.
185 citations
TL;DR: The definition of a fuzzy subgroups with thresholds is given, which is a generalization of Rosenfeld's fuzzy subgroup and Bhakat and Das's fuzzy group and discusses relations between two fuzzy sub groups.
169 citations
TL;DR: In this article, nine symmetrical and asymmetric 2,5-disubstituted 1,3,4-oxadiazoles have been synthesized by a facile and mild method with high yield.
165 citations
TL;DR: In this article, a series of pure Al and mold steels were studied and a strong enhanced diffusion effect was revealed: the surface elements diffuse approximately several micrometers in depth into the substrate only after several bombardments.
Abstract: Electron beams are becoming an increased subject of interest for materials processing. While continuous electron beams have already found wide applications in drilling, hardening, cutting and welding, the advantage of a pulsed electron beam has just emerged. It generates a high power density up to 108–109 W/cm2 at the target surface. Such a high energy is deposited only in a very thin layer within a short time, and causes superfast processes such as heating, melting and evaporation. A dynamic stress field induced in these processes leads to significant modification effects in the material. The combination of these processes provides the material with improved physicochemical and mechanical properties unattainable with ordinary surface treatment techniques. The present paper reports our recent research work on surface treatment by high-current pulsed electron beam (HCPEB). HCPEB is produced on system ‘Nadezhda-2’ with an energy range of 20–40 kV. A series of pure Al and mold steels were studied. Some of them were pre-coated with C, Cr, Ti or TiN powders. A strong enhanced diffusion effect was revealed: the surface elements diffuse approximately several micrometers in depth into the substrate only after several bombardments. Tribological behaviors of these samples were characterized and significant improvement in wear resistance was found. Finally, TEM analysis reveals the presence of stress waves generated by the coupling of thermal and stress fields, which constitutes the main cause of the enhanced diffusion.
158 citations
TL;DR: The experimental results of batch fermentation showed that the final concentration and yield of 1,3-PD on glycerol under micro-aerobic conditions approached values achieved under an aerobic conditions, however, less ethanol was produced under microaerobic than anaerobic Conditions at the end of fermentation.
Abstract: The microbial production of 1,3-propanediol (1,3-PD) by Klebsiella pneumoniae under micro-aerobic conditions was investigated in this study. The experimental results of batch fermentation showed that the final concentration and yield of 1,3-PD on glycerol under micro-aerobic conditions approached values achieved under anaerobic conditions. However, less ethanol was produced under microaerobic than anaerobic conditions at the end of fermentation. The batch micro-aerobic fermentation time was markedly shorter than that of anaerobic fermentation. This led to an increment of productivity of 1,3-PD. For instance, the concentration, molar yield, and productivity of 1,3-PD of batch micro-aerobic fermentation by K. pneumoniae DSM 2026 were 17.65 g/l, 56.13%, and 2.94 g l−1 h−1, respectively, with a fermentation time of 6 h and an initial glycerol concentration of 40 g/l. Compared with DSM 2026, the microbial growth of K. pneumoniae AS 1.1736 was slow and the concentration of 1,3-PD was low under the same conditions. Furthermore, the microbial growth in fed-batch fermentation by K. pneumoniae DSM 2026 was faster under micro-aerobic than anaerobic conditions. The concentration, molar yield, and productivity of 1,3-PD in fed-batch fermentation under micro-aerobic conditions were 59.50 g/l, 51.75%, and 1.57 g l−1 h−1, respectively. The volumetric productivity of 1,3-PD under microaerobic conditions was almost twice that of anaerobic fed-batch fermentation, at 1.57 and 0.80 g l−1 h−1, respectively.
144 citations
TL;DR: In this article, the generalized transformation in homogeneous balance method (HBM) was used to obtain explicit exact solutions for (2+1)-dimensional Boussinesq equation and (3+1-dimensional KP equation.
126 citations
TL;DR: In this paper, the structure, physical characteristics and selective photocatalytic oxidation properties of quantum confined nanosize iron doped TiO2(Q-TiO2/Fe3+) particles were studied by TG-DSC, XRD, DRS, EPR and Selective Oxidation Photocatalysis Measurements.
Abstract: The structure, physical characteristics and selective photocatalytic oxidation properties of quantum confined nanosize iron doped TiO2
(Q-TiO2/Fe3+) particles were studied by TG-DSC, XRD, DRS, EPR and Selective Oxidation Photocatalytic Measurements It is shown that the solubility of iron in the obtained Q-TiO2/Fe3+ nanoparticles is 10 atom% and the iron doping level has a great influence on the transformation of anatase to rutile (A-R) The quantum confined effect was observed for Q-TiO2/Fe3+ nanoparticles All of the samples have EPR Bulk-Fe3+ and Surf-Fe3+ signals, which are located in the bulk and surface of TiO2 nanoparticles respectively Quantitative EPR results indicate that the relative EPR intensity of these paramagnetic centers shows regular change with varying corresponding iron modification level In situ EPR indicates that the photo-generated charge carrier (h+, e−) could be trapped by different Fe3+ sites simultaneously, ie, trapping of h+ is due to Surf-Fe3+ sites at g = 430, whereas that of e− is attributed to Bulk-Fe3+ sites at g = 199 Selective photocatalytic oxidation of cyclohexane into cyclohexanol with higher selectivity has been obtained by molecular oxygen activation over Q-TiO2/Fe3+ nanoparticles under mild conditions It is thought that the optical surface state of Q-TiO2/Fe3+ nanoparticles play a key role in the selective photocatalytic oxidations
TL;DR: In this paper, the authors report the test results of the first industrial-scale absorption heat transformer (AHT) equipment in China, to recover the waste heat released from mixture of steam and organic vapor at 98 °C in coacervation section, synthetic rubber plant of Yanshan Petrochemical Corporation, Beijing, China.
TL;DR: In this article, the process of hot dipping pure aluminum on a steel substrate followed by oxidation was studied to form a surface layer of aluminum oxide resistant to the corrosion of aluminum melt.
TL;DR: In this paper, sulfonated poly(phthalazinones) (SPPESs) were used for proton exchange membrane (PEM) materials for use in fuel cells.
TL;DR: In this paper, a series of new Zr-Al-Ni-Cu amorphous alloys with a constant e/a ratio of 1.4 and an average atomic size of 0.1496 nm was designed.
TL;DR: In this paper, rare earth (RE) elements with concentrations of 0.05 wt.% and 0.1 wt% of primarily Ce and La were added to the Sn-9Zn eutectic alloy to produce Sn-Zn-RE alloys.
Abstract: Rare earth (RE) elements with concentrations of 0.05 wt.% and 0.1 wt.% of primarily Ce and La were added to the Sn-9Zn eutectic alloy to produce Sn-9Zn-RE alloys. A small amount of rodlike Zn-rich phases, which decreases in amount as the RE content increases, is distributed in the Sn matrix under slow cooling. The microstructure is refined with RE additions, and particulate-shaped Sn-RE compounds begin to appear when the RE content reaches 0.1 wt.%. There is no change in the liquidus temperature after RE additions. Of the rosin-activated (RA), rosin mildly activated (RMA), rosin-nonactivated (R), and volatile organic compounds (VOC)-free types of fluxes used for the wetting balance tests in ambient air at 245°C, 260°C, and 290°C, only the RA flux can provide wetting. The addition of RE elements or the increase in soldering temperature reduces the wetting angle and increases the wetting force. The microhardness of the Sn-Zn-RE alloy system was found to be higher than that of Sn-9Zn.
TL;DR: In this article, sulfonated poly(phthalazinone ether ketone)s (SPPEKs) were obtained with a degree of sulfonation (DS) in the desired range of 0.6-1.2.
Abstract: As a novel class of proton exchange membrane materials for use in fuel cells, sulfonated poly(phthalazinone ether ketone)s (SPPEKs) were prepared by the modification of poly(phthalazinone ether ketone). Sulfonation reactions were conducted at room temperature with mixtures of 95–98% concentrated sulfuric acid and 27–33% fuming sulfuric acid with different acid ratios, and SPPEK was obtained with a degree of sulfonation (DS) in the desired range of 0.6–1.2. The presence of sulfonic acid groups in SPPEK was confirmed by Fourier transform infrared analysis, and the DS and structures were characterized by NMR. The introduction of sulfonic groups into the polymer chains increased the glass-transition temperature above the decomposition temperature and also led to an overall decrease in the decomposition temperature. Membrane films were cast from SPPEK solutions in N,N-dimethylacetamide. Water uptakes and swelling ratios of SPPEK membrane films increased with DS, and SPPEKs with DS > 1.23 were water-soluble at 80 °C. Proton conductivity increased with DS and temperature up to 95 °C, reaching 10−2S/cm. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 497–507, 2003
TL;DR: In this paper, a model of Hopfield neural networks with continuously distributed delays is considered and a sufficient condition which guarantees global exponential stability (GES) of an equilibrium point is given based on the method of variation parameter and inequality technique.
TL;DR: In this article, the generalized compound KdV-type and compound kdV -Burgers-type equations with nonlinear terms of any order were considered, and many explicit exact exact solutions were obtained.
Abstract: In this paper, we improved a method presented previously (Phys. Lett. A 285 (2001) 355) by means of a proper transformation. Applying the improved method, we consider the generalized compound KdV-type and compound KdV–Burgers-type equations with nonlinear terms of any order. As a result, many explicit exact solutions, which contain new solitary wave solutions, periodic wave solutions and the combined formal solitary wave solutions, are obtained.
TL;DR: In this article, an optimal freezing temperature was found to be around the point where water droplets were all frozen, about −40°C in this case, and the best thawing conditions were either in ambient air or in water bath at a temperature below 20°C.
TL;DR: In this article, a novel form of ball-like carbon material with its size in micrometer range was prepared from coal with nickel as catalyst by arc plasma method, and the carbon material has been systematically studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and ultraviolet laser Raman spectrographs.
TL;DR: In this article, the basic photophysical characteristics of two fluorophores: monomeric N,N-dimethylaminoethylene-N-allyl-1,8-naphthalimide and methylmethacrylate based copolymer are described both in the absence and presence of Fe2+, Pb2+, Zn2+ and Ni2+ cations.
Abstract: The basic photophysical characteristics of two fluorophores: monomeric N,N-dimethylaminoethylene-N-allyl-1,8-naphthalimide and methylmethacrylate based copolymer including N,N-dimethylaminoethylene-N-allyl-1,8-naphthalimide are described both in the absence and presence of Fe2+, Pb2+, Zn2+ and Ni2+ cations. It is shown that both the fluorophores can be used as homogeneous photo-induced electron transfer fluorescent sensors exhibiting fluorescence enhancement induced by metal ions. The copolymer is more responsive to the Fe2+ cations than to other cations under study.
TL;DR: In this article, the effect of some metal ions (Fe2+, Ni2+, Zn2+, Pb2+) upon the fluorescent intensity of a first generation polyamidoamine dendrimer with a peripheral 4-dimethylaminoethylamine-1,8-naphthalimide group was investigated.
Abstract: The effect of some metal ions (Fe2+, Ni2+, Zn2+, Pb2+) upon the fluorescent intensity of a first generation polyamidoamine dendrimer with a peripheral 4-dimethylaminoethylamine-1,8-naphthalimide group was investigated. The presence of metal ions was found to evoke a photoinduced electron transfer leading to an enhancement in the fluorescence. The results obtained reveal the capacities of these systems to act as sensitive detectors of environment pollution by metal ions. The metal ions inhibit the photodegradation of the dendrimer molecule which exhibits PET properties.
TL;DR: In this article, three isomers of o-, m-, and p-phthalate are used to link together Mn centres, resulting in [Mn(phth)(H2O)x]n moieties with single-chain, double-chain and sheet structures, respectively.
Abstract: Three isomers of o-, m-, and p-phthalate are used to link together Mn centres, resulting in [Mn(phth)(H2O)x]n moieties (phth = phthalate dianion) with single-chain, double-chain and sheet structures, respectively, which predetermine the extended structures derived from the crosslinkage of 4,4′-bipyridine, and show the influence of isomerism of the phthalate on topological changes of the final polymers from two dimensional (2D) single-layer, double-layer to 3D network architectures. These structural changes in topology are correlated with the differences in the magnetic and optical properties of the polymers.
TL;DR: In this paper, the glycerol metabolism by Klebsiella pneumoniae is stoichiometrically analyzed according to energy (ATP), reducing equivalent and product balances, and the theoretical analysis reveals that a microaerobic condition is more perfect for the production of 1,3-propanediol (1,3PD) from glycerols by K. pneumoniae than anaerobic and aerobic conditions.
TL;DR: Investigation of photolysis of polycyclic aromatic hydrocarbons sorbed on surfaces of spruce needles under sunlight irradiation found some PAHs may play an important role on the fate ofPAHs in the environment.
TL;DR: In this article, a composite material made of nanocrystalline BaTiO3 and polymer polystrene sulfonic sodium (PSS) is spincoated onto a ceramics substrate to fabricate humidity sensor.
TL;DR: In this paper, the exact travelling wave solutions for a generalized Zakharov-Kuznetsov (GZK) equation by using the extended-tanh method and direct assumption method were obtained.
TL;DR: In this paper, a feasibility study of lactic acid production integrated with are treatment of wastewater from an industrial starch plant was described. And the optimal conditions, in terms of pH, temperature and starch concentration, were determined.
Abstract: This paper describes a feasibility study of a for lactic acid production integrated with are treatment of wastewater from an industrial starch plant. Rhizopus oryzae two strains, Rhizopus arrhizus and Rhizopus oligosporus were tested with respect to their capability to carry out simultaneous saccharification and fermentation to lactic acid using potato wastewater. Rhizopus arrhizus DAR 36017 was identified as a suitable strain that demonstrated a high capacity for starch saccharification and lactic acid synthesis. The optimal conditions, in terms of pH, temperature and starch concentration, for lactic acid production were determined. The selected fungal strain grew well in a pH range from 3.0 to 7.0. The addition of CaCO(3)10 g dm(-3) maintained the pH at 5.0-6.0 and significantly enhanced lactic acid production. Kinetic study revealed that almost complete starch saccharification and a lactic acid yield of 450g kg(-1) could be achieved in 20 h and 28 h cultivation, respectively. The maximum lactic acid production 21 g dm(-3) and mycelial biomass (1.7 g dm(-3)) were obtained at 30degreesC. Besides the multiple bioproducts, total removal of suspended solids and 90% reduction of COD were achieved in a single no-aseptic operation. (C) 2003 Society of Chemical Industry.