Advanced Materials Research Vols. 403-408

Abstract: Molecular interaction between zinc phthalocyanine (ZnPc) thin films and various oxidizing gas molecules was examined by measuring sensor response of chemiresistor structures. The different response types can be obtained from the interactions to gas molecules of nitrogen dioxide (NO2), sulfur dioxide (SO2) and carbon monoxide (CO). For NO2 interaction, the response current of thermal evaporated ZnPc thin film with metal inter-digitaged pattern electrodes was proportionally increase to the concentration of NO2 gas. For measurement cycle, the NO2 gas at desired concentration was flowed into the measuring chamber for 20 minutes then the nitrogen gas was flowed for 20 minutes to recovering the interaction. The current response exhibited the step up and down during this measuring cycle and the heights of response step were proportional to the NO2 concentration. For SO2 measuring cycle, the response step increased at the beginning cycle then the response of ZnPc thin film seemed to be saturate and remained the same response step height even increasing the SO2 concentration. It was found that if the SO2 concentration was maintained at the same value for each measuring period, the response current was increase for the first few cycles after that the response step height decreased and became almost constant at lower value after passing more than ten measuring cycles. However this phenomenon can recover if the ZnPc surface was leaved in air for a few days. Therefore the interaction between ZnPc and SO2 molecules can modify the ZnPc surface and change the gas response. With the same measurement setup, it cannot found any significant change in the response current of the ZnPc film under the CO gas exposure up to concentration of 250 ppm. This result indicated that no interaction between ZnPc and CO molecules can be observed and these different responses on various gas molecules can demonstrate the selectivity of using ZnPc as a gas sensor.

Abstract: In this paper, charge control mechanism and carrier features have been precisely investigated in InxGa1-xN/InN/InxGa1-xN based quantum-well double heterostructure high electron mobility transistors (QW-DHEMTs). A study of charge control in the InxGa1-xN/InN/InxGa1-xN structure is performed by self-consistently solving Schrödinger equation in conjunction with Poisson’s equation taking into account the spontaneous and piezoelectric polarization effects. The potential profile and the distribution of electron density in the channel as a function of gate voltage are investigated here. A large conduction band offset of about 2.2eV is obtained for the proposed device for In content x=0.05, which ensure better carrier confinement and higher sheet charge density. The influence of In composition(x) and doping concentration of InxGa1-xN upper barrier on sheet charge density and carrier distributions in channel is also presented. This analysis provides a platform to investigate the InN based QW-DHEMTs and to optimized their design.

Abstract: Proposed technique of hyperspectral unmixing is apparent to implement and compute the results in a very fast and efficient manner. To reducing the computational complexity and to estimation of hyperspectral data we adopted a statistical method of median absolute deviation about median. Number of end-members is enumerating by self iterative subspace projection method which depends on Pearson correlation. The mixing matrix is inferred by using Q function projections. A set of tests with real hyperspectral data evaluates the performance and illustrates the effectiveness of the proposed method. For the evaluation of proposed method, the results are compared with the results of vertex component analysis. The experimental results show the effectiveness of proposed method on hyperspectral unmixing. targets Alunite, Buddingtonite, Calcite, Kaolinite, and Muscovite are detected well and have high spectral similarities. Hyperspectral remote sensing is used in a large array of real life applications e.g. Surveillance, Mineralogy, Physics, and Agriculture. The complete work is prepared by using MATLAB.

Abstract: As a promising candidate for future high speed devices InN-based heterojunction field effect transistor (HFET) has gained a lot of attention in recent years. However, InN-based devices are still a less studied compared with other III-nitride based devices. This work investigates theoretically, the electron transport properties of insulated gate AlInN/InN Heterojunction Field Effect Transistor. A self-consistent charge control model based on one-dimensional Schrodinger-Poisson equations is developed. The transport properties of the device are calculated using an ensemble Monte Carlo simulation. The device model incorporates an analytical 3-valley band structure with non-parabolicity for all nitride materials. The scattering mechanisms considered are dislocations scattering, impurity scattering, interface roughness, alloy disorder scattering and phonon scattering. The model also takes into account the highly dominant spontaneous and piezoelectric polarization effects to predict the 2DEG sheet charge density more accurately at the heterointerface. The results obtained are agreed well with the literature.

Abstract: _{Subscript text}Viscosity, coefficient of thermal expansion, glass transition temperature and dilatometric softening temperature of soda-lime-silicate glass doped with Li₂O were investigated by the rotating crucible viscometer and dilatometry, the melting temperature and activation energy for viscous flow of the studied melt were derived on the basis of Arrhenius Equation, in order to reveal the effects of Li₂O on the properties of soda-lime-silicate glass. The results showed that the viscosity of soda-lime-silicate glass was effectively decreased and the melting temperature decreased from 1457°C to 1420°C with the increase of Li₂O from 0 to 1.0wt%, furthermore, the T_g and T_s reduced 30~40°C. The ΔT responded to the range of viscosity of glass formation (η=10³-10⁷Pa•s) increased from 309.84°C to 313.45°C, and the activation energy for viscous flow decreased form 178.47 kJ•mol^-1 to 168.34 kJ•mol^-1. The CTE α _{(25～400°C)} of specimen doped with 0.4% Li2O was 92.048×10^-6°C^-1 and the lowest of the samples.

Abstract: The objective of this research is to present an identification method for elastic moduli of ground rock, through the first-order adjoint equation method using the measurements of the blasting vibration in tunnel excavation. Parameter identification is a minimization problem of the square sum of discrepancy between the computed and observed velocities. For the identification of these parameters, the magnitudes of the blasting force should be identified beforehand. In this study, propagation of an elastic wave is assumed because the amplitude of such a wave is infinitesimal. After the identification of the blasting force, the elastic moduli of three layers are identified simultaneously. We assume that the damping of vibration is linear. By applying the identification technique at the Ohyorogi tunnel site, we verify that the method is useful for tunnel excavation. Using measured data from actual tunnel excavation sites, the numerical identification method presented in this paper is shown to be useful for practical tunnel excavation.

Abstract: The use of starch on polyvinyl acetate emulsion blend modified in order to achieve improved film toughness, which aims to improve water resistance and film-forming emulsion adhesive performance. Dynamic mechanical properties (DMA), scanning electron microscopy (SEM) method was used to analyze the dynamics of film emulsion blend composite mechanics, the distribution of latex particles and glass transition temperature. The results show that: with pure polyvinyl acetate (PVAc) compared to starch-modified film-forming emulsion film distribution, glass transition temperature of the homopolymer emulsion up to 30°C.

Abstract: A first-principles plane wave method with the ultrasoft pseudopotential scheme in the frame of the density functional theory (DFT) is performed to calculate the structural and lattice parameters, the bulk modulus B0 and its pressure derivative B0' of the zinc-blende AlAs, rocksalt AlAs and NiAs-AlAs. The elastic parameters of the zinc-blende AlAs, rocksalt AlAs and NiAs- AlAs were calculated. We also calculate the phase transition pressures between different phases. Our results are satisfactory. Our results are consistent with other results.

Abstract: Based on explicit finite difference algorithm, finite element model of steel plate with transverse surface crack in rough rolling was found. The evolution regularity of transverse surface crack in rolling process was calculated with the model, and effect of different crack sizes, different friction coefficients and different roll diameters on crack evolution were studied. The research indicated that, in rolling direction, the crack tip stress changed from tensile stress to compression stress and then tensile stress again; length and depth of crack both had effect on the healing and propagation of the crack, and mostly in the way of influencing displacement of freedom surface of the crack; different friction coefficients showed no effect on crack tip propagation, but low friction coefficient would be in favor of crack healing at crack bottom; small roll diameter would lead to high crack tip tensile stress and more propagation at crack tip.

Abstract: Effect of the amount of Channel Black on underwater property of PU material is researched by adding Channel Black into PU material. The results show that the amount of Channel Black has most effect on underwater property of PU material. In one atmospheric pressure, the underwater property of PU material is worst when the amount of Channel Black is 60, while the underwater properties are not evident when the amount of channel is 30 and 45. In lower underwater pressure, effect of the amount of Channel Black on underwater property of PU material is almost difference. In higher underwater pressure, the underwater property of PU material is best when the amount of Channel Black is 45, while 30 is second, and 60 is lowest.