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The height limit gantry of urban viaducts has being playing an important role in the information management and traffic dispatch. However, it also limits special vehicles. This paper discusses and analyses three kinds of short-range wireless communication methods in detail (including ZigBee, Bluetooth and Radio Frequency Identification (RFID)), establishes a transmission distance estimation model, analyses some information interferences of vehicles with different roads, designs to an implement quickly channel connection and an identify information for main slave communication modules. The communication slave module is assembled in special vehicles, which is connected with the communication main module in the height limit gantry. A main controller completes the feature recognition and the rise and fall of height limit gantry. The device improves the efficiency of emergency vehicles, with the rapidity, reliability and practicality.

The structural and optical properties of lead-free Barium strontium titanate Ba0.5Sr0.5TiO3 with oxygen vacancies (BST-O) were investigated by first-principles calculations of density functional theory. The results show that the O vacancy has significant influence on the electronic structure and optical performance of the materials. The structures generate a phase transition from cubic to tetragonal phase, when an O atom has removed from the pure Ba0.5Sr0.5TiO3 (BST). The electron density conformation is distributed, which induce conspicuous distortion of the oxygen octahedron. The calculated optical properties, complex dielectric function, refractive index, absorption coefficient, show that the absorption spectra of the BST-O have multimodality and smaller amplitude by comparing with ideal BST. And the oxygen vacancy lead the increase of refractive index and the decrease of absorption coefficient in visible light frequency region (1.59~3.11 eV), the optical anisotropism is also found in the BST-O. Introduction Barium strontium titanate is one of the well known perovskite materials with its excellent ferroelectric and dielectric performance, which is considered as a candidate to replace lead based materials due to the environment issue. Its desirable high dielectric constant, low dielectric losses, strong remnant polarization and low current leakage has been attractive for its fundamental research, and the material could be used for various applications such as dynamic random, access memory, ceramic capacitors, pyroelectric sensors, infrared detectors, chemical sensor, biosensor, microwave devices and optoelectronic applications in recent years . With the intensive study on BST material, a large quantity of tentative exploration on ceramic, film, composite and doping vario-property of BST have been completed . However, most of the experiments of BST focused on the properties in electrical and microwave frequency . The optical response of BST is not very clear. The first principle method is an effective and efficient method for material research, which is applied to the study of perovskite type materials in the last decades . Many typical perovskite materials were studied by this method, such as tantalum niobate (KTN), strontium titanate (SrTiO3) and lead zirconate titanate (PZT) , which has succeed in predicting electronic properties, band structure and optical properties of perovskite materials. The related properties of ideal BST are also investigated though first principle method, but defect state of BST is scarcely researched [12, . As is well known, the oxygen defects are unavoidable during experimental process, F. M. Pontes et al verified that the postannealing temperature and oxygen atmosphere have important influence on the dielectric properties of BST . In this paper, the possible defects in the process of the experiment were considered. The two models of the ideal bulk of BST and BST with O vacancy were designed and the effect of oxygen vacancy on structures and optical properties of the lead-free Ba0.5Sr0.5TiO3 were investigated by first-principles in detail. 5th International Conference on Information Engineering for Mechanics and Materials (ICIMM 2015) © 2015. The authors Published by Atlantis Press 830 Calculation details The structures and optical properties of the lead-free oxygen vacancy Ba0.5Sr0.5TiO3 were calculated by a widely used plane-wave pseudopotential total energy program CASTEP [15] in the framework DFT. The local density approximation (LDA-CAPZ) is used to describe the electronic-correlation function, which have be seen as a typical and accurate mode for the perovskite materials [16, . The Broyden–Fletcher–Goldfarb–Shannon (BFGS) algorithm and Vanderbilt-type ultrasoft pseudopotential (USP) were utilized for geometry optimization. In geometry optimization and optical properties computing, the energy cutoff was set as 380 eV and a 3×3×3 k-point Monkhorst-Park mesh in the Brillouin zone was used. All atoms were not fixed and were relaxed until the total energy variation of each atom was below 5.0×10 eV/atom and the displacement of each atom was below 5.0×10 A. Ba (5s2, 5p6, 6s2), Sr (4s2, 4p6, 5s2), Ti (3s2, 3p6, 3d2, 4s2) and O (2s2, 2p4) were considered as valence electrons configurations. The number of k-point and the cut-off energy were tested by the plane wave energy convergence. The cubic phase Ba0.5Sr0.5TiO3 is a structure with the space group of PM-3M. The experimental lattice parameter of BST is a=b=c=3.930 A , so empirical value 4.0 A is chosen as a initial lattice length. A 2×2×2 supercell of pure BST and a 2×2×2 supercell of BST with oxygen vacancy were designed as computational models, respectively, which were showed in Fig. 1. The calculations of electronic structure and optical properties were based on the previously optimized models. Fig. 1 Supercells of pure BST and BST with oxygen vacancy Geometry and electrons structures of the BST-O The structure properties of materials are very important and fundamental for practical applications. In our calculations, the stable ground states of pure BST and BST-O were found after geometry optimization. Computational structure parameters are presented in Table 1. The lattice parameters of pure BST are a=b=c=7.8036 A, α=β=γ=90° and the cell volume is 475.217 A, which is consistent with the experimental data and testifies the structure is classified as cubic phase, PM-3M group . In contrast, when an O atom point defect is introduced into the system, the lattice parameters are a=7.8202 A, b=7.8107 A, c=7.8101 A and the volume of BST-O is 477.053 A. The whole calculated lattice parameters almost approach to experimental values (error less than 1%). From these data, the phase structure of BST-O belong to tetragonal phase which is different from that of BST. The BST-O’ s cell volume is slight larger than that of pure BST, which suggests that O defect lead to the structure distortion of BST and this result is also in accordance with the previous experiment . Surprisingly, the comparison of bulk modulus for pure BST and BST-O calculated by LDA indicates the pure BST’ s bulk modulus is much larger than the BST-O’ s, from the Table 1, the difference between two models’ bulk modulus is 155.49798 GPa, therefore it can be inferred that O vacancy play an important role on mechanical character of BST.

Polyimide (PI) and the functional graphene modified with nano-composite models of hydroxyl,carboxyl and amino groups are realized by a multi-scale modeling method.The influences of the functional graphenes with different functional groups on the microstructure,mechanical and thermodynamic performances of polyimide-based composite models are investigated by the molecular dynamics simulation.The cell parameters,solubility parameters,elastic coefficients, Young's moduli,shear moduli,and the values of glass-transition temperature (Tg) of polyimide-based composite models are calculated with the COMPASS force field.Moreover,the interaction energies and hydrogen bonds of composites are analyzed to explore the internal mechanisms for improving mechanical and thermodynamic properties.The results demonstrate that the density of PI matrix is 1.312 g·cm-3 and the solubility parameter of PI matrix is 21.84 J1/2·cm-3/2, which are in accord with the actual PI parameters.The Young's moduli of the composites increase obviously with the increase of the interaction energy between the PI matrix and the functional graphenes with hydroxyl,carboxyl and amino groups at 298 K and 1 atm.The Young's moduli of PI and PI/graphene with carboxyl groups are respectively 3.174 GPa and 4.946 GPa and the shear moduli are respectively 1.139 GPa and 1.816 GPa.Comparing with pure PI/graphene composite,the average hydrogen bonds increase obviously after graphene has been functionalized.Because the interaction between the functional graphene and PI matrix increases,the movement of PI molecular chain needs more energy,and the rigidity of the composite is enhanced.The Tg of the composite also relates to the interaction energy.It is also found that the Tg of the nano-composite effectively decreases by the hybrid functional graphene.The Tg of pure PI is 663.57 K,while the Tg values of PI/graphene and PI/graphene with carboxyl groups nanocomposites are 559.30 K and 601.61 K,respectively.Moreover,the density and interaction energy of hydrogen bonds of the PGCOOH are 784.81 kcal/mol and 1.396 g/cm3,respectively,which are the largest among their counterparts of the composite systems.The elastic coefficients show that the PGCOOH is more uniform than that other composites.All of these indicate that the graphene with carboxyl group can greatly enhance the interaction between graphene and PI,improve the mechanical properties and adjust the Tg value of the PI matrix.The chemical modification of interaction energy in matrix is deemed to be of benefit to the improvement in composite performance,and the interaction energy calculation is considered to be an effective method of predicting the structures and performances of new composites.

The poly(ethylene terephthalate)-PET is widely used in dielectric insulation, so the study on its luminescence characters is valuable. The Photoluminescence-PL intensity and spectra of PET films were detected by the home-made set-up. Experiment shows: The PL intensity with exponential decay along with the time. There are emitting peaks about 300–400nm, 500–600nm and nearby 700nm in the PL accumulative spectra, and the peak region nearby 700nm is a little higher. The absorption spectra were tested by TU-1901 double beam UV-Vis spectrophotometer. The calculation shows that energy gap of PET films is about 3.96eV according to the absorption edge of the spectra. The results we obtained from the PL measurement indicate that this method will contribute to understanding the trap distribution and luminescent micro-mechanism of Insulation Polymers.

The polyimide/potassium tantalite niobate (PI/KTa0.5Nb0.5O3) nanoparticle composite model is established by a multi-scale modeling method. The influences of KTa0.5Nb0.5O3 nanoparticles with different sizes (5.5, 8.0, 9.4, 10.5, 11.5 Å) on the structure, elastic modulus and interaction energy of the polyimidebased nanocomposites are investigated by the molecular dynamics simulation. The cell parameters, cohesive energy density, solubility parameter, Young’s modulus and Poisson’s ratio are calculated. Moreover, the bond energy and the number of atoms per unit surface area of the nanoparticles are analyzed to explore the internal mechanism of mechanical property improvement. The results demonstrate that the density of PI matrix is 1.24-1.35 g/cm3, the cohesive energy density of PI matrix is 2.025×108 J/m3, and the solubility parameter of PI matrix is 1.422×104 (J/m3)1/2, which are consist with the actual PI parameters. Meanwhile, the Young’s moduli of the PI and PI/KTa0.5Nb0.5O3 composites are respectively 2.914 GPa and 3.169 GPa, and the Poisson’s ratios are respectively 0.370 and 0.353, which illustrate that the mechanical properties of the PI could be significantly improved by introducing the KTa0.5Nb0.5O3 nanoparticles. At the same pressure, the increases of Young’s modulus with temperature are basically the same without and with doping the KTa0.5Nb0.5O3 nanoparticles into the PI matrix; and when the temperatures are different, the standard deviations of elastic moduli of the PI matrix and PI/KTa0.5Nb0.5O3 composite are almost the same. No matter what the pressures and the temperature are, the Young’s modulus of PI/KTa0.5Nb0.5O3 composite is always larger than that of PI matrix. These all indicate that the effect of KTa0.5Nb0.5O3 nanoparticle on elastic modulus has a similar variation rule under the selected pressure and temperature conditions. In addition, the bond energies of particle surface atoms are 8.62-54.37 kJ·mol-1, which shows that the binding force between particles and the matrix is mainly van der Waals force, and hydrogen bonds exist at the same time. When the doping concentration is fixed, the proportion of nanoparticles surface atoms increases significantly as the size decreases, the interaction between particles and the matrix becomes stronger, the Young’s modulus increases obviously and the size effect is more significant. Therefore, it is confirmed that the doping small size KTa0.5Nb0.5O3 nanoparticles into the polyimide matrix is an effective way to improve the mechanical properties of the composite.

Tested electroluminescence (EL) of both original and inorganic nano particle doped polyimide films under dc field by experimental set-up made-home. The results showed that the luminescence of both polyimide films increased along with the electric field. Their pre-breakdown fields obtained by measuring EL were much similar. The pre-breakdown field of nano particle doped polyimide film was higher than the original's, But, under the same field, the EL of the former was less than the latter's. The EL of nano particle doped polyimide films had peak value whose width was about 60s after 430s, and the EL was higher than initial value throughout the descending region.

This paper obtains the discharge graph and fractal dimension by calculation of electric field distribution in a system of needle-plate electrodes by the finite element method, and in consideration of the stochastic dependence discharge growth probability on the local electric field. The results agree with those of Barclay (1990), and confirm that as /spl eta/ becomes larger, the discharge graph becomes more linear.

In this paper，the recombination rate of charges in low density polyethylene （LDPE） film was obtained by measuring the number of photons released from the film when the film was short-circuit discharged after being set to high voltage of direct current （HVDC）. Under different designed conditions, including changing the polarity of HVDC and the value of applied field and the time duration of applied field，the amount of photons was measured to calculate the charges’ combination rate. The result showed that the measured number of photons （recombination rate） was sensitive to the applied field but insensitive to the applying duration. When the field was higher than 80 MV/m，the number of released photon increased slowly with increasing voltage. Using the date obtained in our experiment as well as those in other papers，the luminous efficiency of LDPE film was calculated to be 5.9×10-6，and the charges’ recombination rate during first 0.2 second at the beginning stage of short-circuit is around 2.8%.