Showing papers by "Jiangxi University of Science and Technology published in 2012"

M2M Communications for Smart City: An Event-Based Architecture

Abstract: Machine to machine (M2M) communications will lead to dramatic changes in the applications and services offered to citizens, allowing smart city to become a reality. In this article, we first introduce the new tendency in M2M development and analyze the construction frame of application systems in smart city. Then, an event-based architecture depending on SOFIA project is built to allow the management and cooperation among M2M components by mean of event manager. Based on this architecture, we conduct a case study in a vehicular context. M2M network architecture is introduced for vehicular networks. Finally, an event processing flow of vehicle maintenance services is designed to manage the mission-critical wireless messages.

Synthesis, properties and application research of atrazine Fe3O4@SiO2 magnetic molecularly imprinted polymer

Abstract: Magnetic Fe3O4 nanoparticles were prepared by coprecipitation and then were coated with SiO2 on the surface Fe3O4@SiO2 composite microspheres were modified by KH570 Using molecular imprinting technology, atrazine magnetic molecularly imprinted polymer was prepared by using atrazine as template molecule, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linkers The morphology, composition and magnetic properties of magnetic nanoparticles were characterized The recognition selectivity of polymer was studied for template molecule and simulation by UV spectrophotometry The adsorption properties and selectivity ability were analyzed by Scatchard analysis Scatchard linear regression analysis indicated that there are two binding sites of the target molecules The magnetic molecularly imprinted polymer has been applied to the analysis of atrazine in real samples The results show that: the recovery rates and the relative standard deviation were 940∼987% and 21∼40% in corn, the recovery rates and the relative standard deviation were 887∼935% and 28∼72% in water

Preparation,characterization and photocatalytic performance of Mo-doped ZnO photocatalysts

Abstract: A series of Mo-doped ZnO photocatalysts with different Mo-dopant concentrations have been prepared by a grinding-calcination method. The structure of these photocatalysts was characterized by a variety of methods, including N2 physical adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, photoluminescence (PL) emission spectroscopy, and UV-vis diffuse reflectance spectroscopy (DRS). It was found that Mo6+ could enter into the crystal lattice of ZnO due to the radius of Mo6+ (0.065 nm) being smaller than that of Zn2+ (0.083 nm). XRD results indicated that Mo6+ suppressed the growth of ZnO crystals. The FT-IR spectroscopy results showed that the ZnO with 2 wt.% Mo-doping has a higher level of surface hydroxyl groups than pure ZnO. PL spectroscopy indicated that ZnO with 2 wt.% Mo-doping also exhibited the largest reduction in the intensity of the emission peak at 390 nm caused by the recombination of photogenerated hole-electron pairs. The activities of the Mo-doped ZnO photocatalysts were investigated in the photocatalytic degradation of acid orange II under UV light (λ = 365 nm) irradiation. It was found that ZnO with 2 wt.% Mo-doping showed much higher photocatalytic activity and stability than pure ZnO. The high photocatalytic performance of the Mo-doped ZnO can be attributed to a great improvement in the surface properties of ZnO, higher crystallinity and lower recombination rate of photogenerated hole-electron (e−/h+) pairs. Moreover, the undoped Mo species may exist in the form of MoO3 and form MoO3/ZnO heterojunctions which further favors the separation of e−/h+ pairs.

Spin-orbit-coupling-induced half-skyrmion excitations in rotating and rapidly quenched spin-1 Bose-Einstein condensates

Abstract: We investigate the half-skyrmion excitations induced by spin-orbit coupling in the rotating and rapidly quenched spin-1 Bose-Einstein condensates. We give three expressions of the corresponding spin vectors to describe the half-skyrmion. Our results show that the half-skyrmion excitation depends on the combination of spin-orbit coupling and rotation, and it originates from a dipole structure of spin which is always embedded in three vortices constructed by each condensate component respectively. When both the strength of spin-orbit coupling and the rotation frequency are larger than some critical values, the half-skyrmions encircle the center with one or several circles to form a radial lattice, which occurs even in the strong ferromagnetic/antiferromagnetic condensates. We can use both the spin-orbit coupling and the rotation to adjust the radial lattice. The realization and the detection of the half-skyrmions are compatible with current experimental technology.

Thermal stability, microstructure and photocatalytic activity of the bismuth oxybromide photocatalyst

Abstract: Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate-like Bi24O31Br11at around 750°C and the formed Bi24O31Br11 can further convert to rod-like α-Bi2O3 at around 850°C. The prepared compounds were characterized with X-ray diffraction (XRD), N2 physical adsorption, scanning electron microscopy (SEM), and UV-Vis diffuse reflectance spectra (DRS), respectively. The photocatalytic activity of the produced bismuth oxybromides was evaluated by photocatalytic decomposition of acid orange II under both visible light (λ>420 nm) and UV light (λ=365 nm) irradiation. Results show that these compounds have different band gaps and different photocatalytic properties. The band gap energies of the as-prepared samples were found to be 2.82, 2.79, 2.60 and 3.15 eV for BiOBr, BiOBr/Bi24O31Br, Bi24O31Br, and α-Bi2O3, respectively. Under both UV light and visible light irradiation, the photocatalytic activity follows the order: BiOBr/Bi24O31Br mixture>BiOBr>Bi24O31Br>α-Bi2O3. The change in photocatalytic activity could be attributed to the different light absorption ability and microstructures of the photocatalysts.

Circular-hyperbolic skyrmion in rotating pseudo-spin-1/2 Bose-Einstein condensates with spin-orbit coupling

Abstract: By exploring the spin-orbit-coupled rotating pseudo-spin-1/2 Bose-Einstein condensates with the stochastic projected Gross-Pitaevskii equations, we prove the existence of the circular-hyperbolic skyrmion, which possesses two extreme values of ${S}_{z}$. The nonequal intraspecies interactions and interspecies interactions cause the two components to be wholly disproportionate when the system reaches the equilibrium state. The circular-hyperbolic skyrmion results from the vortex-dipole structure. For the miscible condensates, the increase of spin-orbit coupling enhances the creation of the circular-hyperbolic skyrmion, and makes them link one after another locally. In particular, the circular-hyperbolic skyrmion even can form a chain when the spin-orbit coupling is only in one direction. For the immiscible condensates, the hyperbolic skyrmion occurs at the center, while the circular-hyperbolic skyrmion occurs at the outskirts of the condensates. The increase of the spin-orbit coupling restricts the creation of the hyperbolic skyrmion and enhances the creation of the circular-hyperbolic skyrmion.

Cloning and expression of the first gene for biodegrading microcystin LR by Sphingopyxis sp. USTB-05.

Abstract: Harmful cyanobacterial blooms are a growing environmental problem worldwide in natural waters, the biodegradation is found to be the most efficient method for removing microcystins (MCs) produced by harmful cyanobacteria. Based on the isolation of a promising bacterial strain of Sphingopyxis sp. USTB-05 for biodegrading MCs, we for the first time cloned and expressed a gene USTB-05-A (HM245411) that is responsible for the first step in the biodegradation of microcystin LR (MC-LR) in E. coli DH5alpha, with a cloning vector of pGEM-T easy and an expression vector of pGEX-4T-1, respectively. The cell-free extracts (CE) of recombinant E. coli DH5alpha containing USTB-05-A had high activity for biodegrading MC-LR. The initial MC-LR concentration of 40 mg/L was completely biodegraded within 1 hr in the presence of CE with a protein concentration of 0.35 mg/mL. Based on an analysis of the liquid chromatogram-mass spectrum (LC-MS), the enzyme encoded by gene USTB-OS-A was found to be active in cleaving the target peptide bond between 3-amino-9-methoxy-2,6, 8-trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda) and arginine of MC-LR, and converting cyclic MC-LR to linear MC-LR as a first product that is much less toxic than parent MC-LR, which offered direct evidence for the first step on the pathway of MC-LR biodegradation by Sphingopyxis sp. USTB-05.

Influence of explosion parameters on wavelet packet frequency band energy distribution of blast vibration

Abstract: Blast vibration analysis is one of the important foundations for studying the control technology of blast vibration damage. According to blast vibration live data that have been collected and the characteristics of short-time non-stationary random signals, the wavelet packet energy spectrum analysis for blast vibration signal has made by wavelet packet analysis technology and the signals were measured under different explosion parameters (the maximal section dose, the distance of blast source to measuring point and the section number of millisecond detonator). The results show that more than 95% frequency band energy of the signals s1–s8 concentrates at 0–200 Hz and the main vibration frequency bands of the signals s1–s8 are 70.313–125, 46.875–93.75, 15.625–93.75, 0–62.5, 42.969–125, 15.625–82.031, 7.813–62.5 and 0–62.5 Hz. Energy distributions for different frequency bands of blast vibration signal are obtained and the characteristics of energy distributions for blast vibration signal measured under different explosion parameters are analyzed. From blast vibration signal energy, the decreasing law of blast seismic waves measured under different explosion parameters was studied and the wavelet packet analysis is an effective means for studying seismic effect induced by blast.

Codeposition of Co and Al on nickel base superalloys by pack cementation process

Abstract: To seek favorable conditions for the codeposition of Co and Al to form diffusion coatings on nickel base superalloys, the thermochemical analyses were adopted for a series of pack powder mixtures containing Co, Al, halide salts and Al2O3. The halide salts studied were AlF3 and NH4Cl. On the basis of the thermochemical calculations, the pack powder mixture of 7.6Al–20Co–4NH4Cl–68.4Al2O3 (wt.%) activated by NH4Cl was formulated. The coatings had a two-layer structure, of which the outer layer was mainly composed of Al0.9Ni1.1 where a part of Ni was replaced by Co. Once this was achieved, a series of further experiments was undertaken to investigate the effects of deposition duration and temperature on the kinetics of coating growth process. It was observed that these parameters only affected the coating thickness. The parabolic relationship between the coating thickness and the deposition duration confirms that the process was mainly diffusion-controlled. The experimental results of the oxidation showed that the coating can prevent efficiently substrate from oxidizing. The excellent oxidation resistance was attributed to a continuous and compact α-Al2O3 film formed on the surface of sample.

The up-conversion properties of Yb3+ and Er3+ doped Y4Al2O9 phosphors

Abstract: Er3+ doped and Yb3+/Er3+ co-doped Y4Al2O9 phosphors are prepared by the sol–gel method. The effect of dopant concentration on the structure and up-conversion properties is investigated by X-ray diffraction (XRD) and photoluminescence, respectively. XRD pattern indicates that the sample structure belongs to monoclinic. Under 980 nm excitation, the green and red up-conversion emissions are observed and the emission intensities depended on the Yb3+ ion concentration. The green up-conversion emissions decrease with the increase of Yb3+ concentration, while red emission increases as Yb3+ concentration increases from 0 to 8 at% and then decreases at high Yb3+ concentration. The mechanisms of the up-conversion emissions are discussed and results shows that in Er3+ and Yb3+/Er3+ co-doped system, cross-relaxation (CR) and energy transfer (ET) processes play an important role for the green and red up-conversion emissions.

A sonochemical route to fabricate the novel porous F, Ce-codoped TiO2 photocatalyst with efficient photocatalytic performance

Abstract: A novel F, Ce-codoped TiO2 photocatalyst with mesoporous structure was successfully fabricated by ultrasound irradiation. The obtained catalysts were characterized by X-ray diffraction, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, photoluminescence spectroscopy, and N2 adsorption. The photocatalytic activity of the samples was evaluated by degradation of acid orange II under UV light irradiation. Results showed that F and Ce can be successfully doped into TiO2 under ultrasonic irradiation conditions. All the single F or Ce-doped TiO2 and F, Ce-codoped TiO2 have shown good mesoporous structures, and this can be contributed to the ultrasound-induced aggregation effect. The F, Ce-codoped TiO2 photocatalyst exhibits much higher photocatalytic activity than that of pure, single F or Ce-doped TiO2, which could be attributed to that F, Ce-codoping increases its surface hydroxyl groups and effectively reduces the photo-generated electron/hole pair recombination rate.

Critical failure characteristics of high stress rock induced by impact disturbance under confining pressure unloading

Abstract: The critical failure characteristics of sandstone experiencing change stresses from three-dimensional loading to confining stress unloading and to axial impact,are investigated by the improved split Hopkinson pressure bar(SHPB) with axial static pressure and confining pressure.The results show that:(1) The critical failure characteristics of sandstone under external impact is influenced obviously by axial static pressure;and the impact strength first increases and then decreases as the axial static pressure increases.(2) The stress-strain curve of sample under coupled static and dynamic loading is a typical class Ⅰ curve when without axial static pressure and the axial static pressure is 20% of uniaxial compressive strength.(3) With the increase of axial static pressure,the stress-strain curve changes to the typical class Ⅱ curve gradually.In the failure process of sample,the energy change law is from disturbed energy absorption to elastic stored energy release,which can reflect the mechanism of interactions between high static stress and dynamic disturbance in the process of rockburst.The results can provide a test support for the further research of rockburst mechanism.The surface displacement field is monitored by digital speckle correlation method(DSCM).The surface displacement field results show that the samples present whole expansion characteristics under conventional impact loading;but under the axial static pressure of 72 MPa,the samples present the interaction of tension-shear failure and expansion failure,which reflects the effect of axial static pressure on the fracture mode of dynamic failure surface of sample.

Inhomogeneous stationary and oscillatory regimes in coupled chaotic oscillators

Abstract: The dynamics of linearly coupled identical Lorenz and Pikovsky-Rabinovich oscillators are explored numerically and theoretically. We concentrate on the study of inhomogeneous stable steady states (“oscillation death (OD)” phenomenon) and accompanying periodic and chaotic regimes that emerge at an appropriate choice of the coupling matrix. The parameters, for which OD occurs, are determined by stability analysis of the chosen steady state. Three model-specific types of transitions to and from OD are observed: (1) a sharp transition to OD from a nonsymmetric chaotic attractor containing random intervals of synchronous chaos; (2) transition to OD from the symmetry-breaking chaotic regime created by negative coupling; (3) supercritical bifurcation of OD into inhomogeneous limit cycles and further evolution of the system to inhomogeneous chaotic regimes that coexist with complete synchronous chaos. These results may fill a gap in the understanding of the mechanism of OD in coupled chaotic systems.

Effects of spatial frequency distributions on amplitude death in an array of coupled Landau-Stuart oscillators

Abstract: The influences of spatial frequency distributions on complete amplitude death are explored by studying an array of diffusively coupled oscillators. We found that with all possible sets of spatial frequency distributions, the

Study of Car-following Model Based on Minimum Safety Distance

Abstract: On the basis of the research of two traditional safety distance models which based on headway and braking process, In connection with the leading vehicle in static, uniform speed, and uniform deceleration driving states, a model of minimum safety distance for collision avoidance between the following and the leading vehicles was established considering the vehicle gradual deceleration in braking process for avoiding deceleration mutation in the old models. At last, the simulations for the improved model and the traditional one were performed with Matlab under the same condition. The simulation data shows that the improved model could resolve the inaccurate defects in computing safety distance by the tradition models and provide a reference for the future research of car-following model.

Anion and pH induced spontaneous resolution of Δ- and Λ-[M(H2Biim)3]SO4 (M = Ru2+, Co2+, Ni2+, Mn2+, Fe2+, and Zn2+) enantiomers

Abstract: The homochiral self-assembly of [M(H2biim)3]SO4 (M2+ = Ru, 1; Co, 2; Ni, 3; Mn, 4; Fe, 5; and Zn, 6; H2biim = 2,2′-biimidazole) complexes have been systematically observed. For complexes 1 and 2, the spontaneous resolution processes not only depend on the counter anion but are also impacted by the pH value of the reaction solution. The enantiomers Δ-1 and Λ-1, and Δ-2 and Λ-2 were isolated in acidic conditions, while rac-1 and rac-2·5H2O were obtained in neutral conditions, respectively. For complexes 3–6, however, the spontaneous resolution processes are independent on the pH value of the reaction solution. Single crystal X-ray diffraction analysis reveals the enantiomers Δ and Λ are homochiral (10,3)-b three-dimensional networks constructed by the hydrogen bonds between the sulfate and H2biim ligand, whereas rac-1 assembles into (6,3) two-dimensional layers (see CrystEngComm, 2009, 11, 1114–1121) and rac-2 into one-dimensional chains. The data observed here seem to suggest that the hydrogen bonding modes between the sulfate and H2biim ligand play a crucial role in spontaneous resolution of the enantiomers. Furthermore, the solid state CD spectra and powder XRD patterns were also used to diagnose the obtained complexes.

A Distributed Parallel Genetic Algorithm oriented adaptive migration strategy

Abstract: Distributed Parallel Genetic Algorithm is the most widely a parallel genetic algorithm. It has natural parallelism and has high performance in solving complex, large-scale, non-linear, non-differentiable optimization problems. This paper analyzes the traditional limitations of distributed parallel genetic algorithms, for its migration fixed blindness and other disadvantages. A Distributed Parallel Genetic Algorithm oriented adaptive migration strategy (AMDPGA) was proposed in this paper, which was suitable for running on the current parallel computers. This Implementation combines the Distributed Parallel Genetic Algorithm and current computer architecture, which makes the Distributed Parallel Genetic Algorithm execute on the mainstream computer concurrently and improve the convergent speed. The experiments showed that this algorithm has not only faster convergent speed but also has more accurate precision and overcome more faults as well as higher parallel efficiency.