Papers by Keyword: Local Structure

Abstract: The static element in static deformation analysis was used to simulate the boundary condition of local structure when studying the modality of local structure. Using this method, the vibration modality of a beam system and the main engine lubricating oil tank were researched. The results show that the usage of static element in dynamic analysis can solve the vibration modality of local structure accurately, the difference ratio of first order frequency is less than 1/10000 in the beam model analysis, and the modal analysis of main engine lubrication oil tank has a good performance, which is a helpful base for the coupling vibration research in ship structure.

Abstract: For the first time the rearrangement of cerium local environment in Ce2Fe17-xMnx(x = 0; 1; 2) intermetallics vs. Mn concentration and temperature was investigated by thespectroscopy of extended X-ray absorption fine structure (EXAFS) above K-Ce absorptionedge. At the same time under similar conditions by the spectroscopy of X-ray absorption near-edge structure (XANES) above L3-Ce absorption edge the valence state of Ce was studied. Thecorrelation is found between changes in local electronic and crystalline structure observed inCe2Fe17-xMnx and the types of magnetic states in these compounds.

Abstract: Abstract. The valence state of Ce and Eu was investigated by X-ray absorption near-edge structure (XANES) spectroscopy above L3-Ce and L3-Eu absorption edges in series of RCo₂P₂ (R = La, Ce, Pr, Eu) magnetic intermetallics. At the same time under similar conditions the rearrangement of Co and Pr local environment vs. temperature was studied by extended X-ray absorption ¯ne structure (EXAFS) spectroscopy above K-Co and L3-Pr absorption edges.

Abstract: A GST-driven spatially adaptive filter is developed in this paper based on the framework of non-local means (NLM) avoiding explicit motion estimation. Gradient Structure Tensor (GST) is introduced to express the underlying local image structural patterns, which drives the window function to yield adaptive scale and shape fitting for the local structure. This leads to patches with more similar gray-level and local structures being gathered for super-resolution estimation of image. Results on several test video sequences show that the proposed method is effective in providing super-resolution on general sequences and achieves improvement of performance on the compared method.

Abstract: The electron density distribution and the local structure of aluminum oxide (Al2O3), chromium doped aluminum oxide (Cr:Al2O3) and vanadium doped aluminum oxide (V:Al2O3) have been studied. Powder X-ray data set of Al2O3 , Cr:Al2O3 and V:Al2O3 is analyzed in terms of cell parameters, thermal vibration parameters, 1D, 2D and 3 Dimensional electron density distributions. The bonding between the atoms using the maximum entropy method (MEM) and bond length distribution using pair distribution function (PDF) has been analyzed. The particle size of Al2O3 , Cr:Al2O3 and V:Al2O3 is also analyzed using XRD and SEM.

Abstract: The insufficient filling and shrinkage are often produced in the process of injection molding. These defects cause the production efficiency to reduce and production cost to rise. In this paper, the forming process of Dn40-type control valve is analyzed to find the main reason for such forming defects by using CAE tools and comparing with the good forming process of a Dn50-type control valve. Results show that big difference between wall thicknesses and bad exhaust system in injection mold is the main reasons for insufficient filling. In the meantime, measures to prevent defects are investigated. Modifying the local structure of the injection mold is provided to avoid the defects. Using reasonable parameters in the injecting process and modified injection mold, the injection product have a smooth surface and good forming. The experiment verified the feasibility of the measure for prevention of defects.

Abstract: Local structures of indium oxynitride (InON) nano-crystal prepared by reactive gas-timing RF magnetron sputtering technique are under investigation. Since the optical properties of these InON thin films depend on gas-timing ratio, the local structure analysis is needed in order to determine the relation between the gas timing ratio and its optical properties. In this work, InON thinfilm with 30:0 seconds (N2:O2) gas-timings ratio was analyzed for its local structure using X-ray absorption fine structure (XAFS) technique in conjunction with first principle calculation. The results indicate that the crystal structure of the film is wurtzite structure which is a typical structure of InN. However from the results of Auger Electron Spectroscopy (AES), there are oxygen contents in the film. Since XAFS analysis confirmed the 4-fold local structure of Indium atom, these oxygen atoms must be substituted in nitrogen sites with slightly changing the local structure of Indium atom. The best fit of XAFS data indicated that there is an oxygen atom substituted in nitrogen site of the 4-fold indium.

Abstract: Oxygen/nitrogen (O/N) configuration in RE-J-phase, RE4Si2O7N2 (RE = rare earth element), was simulated by the Monte Carlo method applied to O/N distribution models. Proportion of local structures of Si2(O,N)7 ditetrahedra and Si(O,N)4 tetrahedra in the J-phase was quantitatively assessed. For the Lu-J-phase model with the bridging site between two Si atoms being occupied by nitrogen atom, the Si2(O,N)7 ditetrahedra composed of O3≡Si–N–Si≡O2N (> 40 %), O3≡Si–N–Si≡O3 (c.a. 30 %), and O2N≡Si–N–Si≡O2N(c.a. 15 %). Tetrahedra of SiO3N and SiO2N2 were dominant and small amount of SiON3 tetrahedra coexisted. For La-J-phase model with the O/N occupancy of 0.1/0.9 at the bridging site, configurations of O3≡Si–O–Si≡O2N (c.a. 5%), O3≡Si–O–Si≡O3 (c.a. 3%), and O2N≡Si–O–Si≡O2N (c.a. 2%) were demonstrated in addition to the three configurations of ditretrahedra recognized in the Lu-J-phase. In La-J-phase coexistence of SiO4 tetrahedra was presented.

Abstract: The electronic structure and phase stability of the Zr-Ni-Al ternary glassy alloys, have been systematically investigated experimentally and theoretically. Thermal stability and crystallization process have been clarified by the DSC and XRD measurements. Composition dependence of the stability parameter; Tg/Tl has been clarified. The electronic structure around the Fermi level has been investigated by using the high resolution UPS. It is found that there is a sizable pseudogap at the Fermi level of the electronic structure of the Zr65Ni20Al15 glassy alloy. The DVXα calculations for the charateristic clusters in the Zr-Ni-Al glassy alloy having high glass forming ability have been also performed. It is found that these clusters formation reduces the internal energy and can contribute to the phase stability. The LMTO-ASA band calculations for the Zr6NiAl2 compound which is the most relevant compound to the Zr60Ni25Al15 glassy alloy have been also performed. It is found that there is a sizable pseudogap at the Fermi level in its electronic structure, suggesting exiting of the pseudogap of the glassy alloy.

Abstract: CuxZr1-x (x=0.30~0.85) binary amorphous alloy models were constructed using molecular dynamics simulations. In order to characterize the short-ranged local structures and the free volume of the whole cell, Voronoi polyhedral analyses were performed for their initial states and also for the deformed states. Both geometrical and physical factors are intimately related to each other and exhibit a large influence on mechanical properties. The elastic properties of shear modulus and bulk modulus tend to increase as the free volume decreases. The Poisson’s ratio, which is related to the glass fragility, increases as the free volume. However, the relation among three elastic properties obtained from the continuous mechanics of the isotropic body does not hold. Also, the maximum stress in the finite deformation drastically decreases with increasing free volume content.