Papers by Keyword: Inhomogeneity

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Authors: Jia Tai Gang, Peng Yan Shi, San Shan Gang
Abstract: A cellular automata model with inhomogeneity and mobility was presented. The inhomogeneity in individuals’ behaviors was considered by assigning the distance on their neighbors, varying levels of infectivity and susceptibility. The individual mobility was reflected by random walk cellular automata. The proposed model can serve as a basis to simulate influenza A (H1N1) based on real data. We studied the effect of two population movement parameters on the epidemic propagation: the percentage and the max-distance of population movement. The results show that the epidemic spreading is more sensitive to the former. The infected individuals are positive growth while the percentage of population movement increases. And the number of infected individual eventually stabilizes in the case of plotting the relation of the max-distance against the infected.
Authors: D.J. Ewing, Qamar-ul Wahab, Sergey P. Tumakha, Leonard J. Brillson, X.Y. Ma, Tangali S. Sudarshan, L.M. Porter
Abstract: In this study, we performed a statistical analysis of 500 Ni Schottky diodes distributed across a 2-inch, n-type 4H-SiC wafer with an epilayer grown by chemical vapor deposition. A majority of the diodes displayed ideal thermionic emission when under forward bias, whereas some diodes showed ‘double-barrier’ characteristics with a ‘knee’ in the low-voltage log I vs. V plot. X-ray topography (XRT) and polarized light microscopy (PLM) revealed no correlations between screw dislocations and micropipes and the presence of double-barrier diodes. Depth resolved cathodoluminescence (DRCLS) indicated that certain deep-level states are associated with the observed electrical variations.
Authors: Vladimir I. Andreev
Abstract: It is generally considered within analysis the residual stresses that unloading occurs on elastic law. For large initial loads, some plasticity theories believe that during unloading secondary plastic deformation can occur. The distinctive work provides a new theorem of unloading, which takes into account irreversible changes in the mechanical characteristics of the material under load. There is an example of the analysis of residual stresses corresponding to the given theorem.
Authors: Shu Hong Wang, Heek Wang Lee, Xing Dong Zhao, Ahmad Bashir
Abstract: When a tunnel or an underground structure is excavated in rock mass, rock disturbed or damaged zone (EDZ) is formed around the excavation due to the stress concentration resulting from stress redistribution. Recent studies on the rock EDZ revealed it’s important to structural stability around underground opening. In this study, the fracture and damage mechanisms of rock induced by the accumulation of microcracks were investigated by AE tests. The results of the experiments showed that tensile failure was the major microscopic failure mechanism of rock in excavation damaged and disturbed zone. The expression of the damage magnitudes in each AE source leads to accurate prediction of macroscopic failure mechanisms. In addition, the orientation of the macroscopic failure plane could be estimated by the orientational distribution of microcracks.
Authors: Zhe Jiang Li, Jia Shun Hu, Lin Qing Li, Liang De He
Abstract: Finite element procedure was used to build a spatial model of a perforated caisson, the result was compared with the one that was calculated according to the current standard. It is pointed out that simplifying assumption of the standard is different from the actual structure, the side walls can’t act as fixed constraints for the front wall. The calculated mid-span moment in the middle span is close to the ANSYS result, while that in the side span is much smaller than the ANSYS result. It is recommended that the result is multiplied by a expansion coefficient.
Authors: Zhi Ying Ou, Dong Xia Lei
Abstract: The residual stresses induced in functionally graded medium (FGM) with inhomogeneity cooling down from the processing temperature are determined with concentric cylinder model and analytical solutions of the inhomogeneous governing equations for displacement components. The analytical solutions derived here are general for power-law variations of the elastic moduli of the FGM. With a power exponent, analytical expressions for the residual stresses of FGM with inhomogeneity can be obtained. By changing the power exponent and the coefficient of the power terms, the solutions obtained here could be applied to different properties of FGM with inhomogeneity. The results show that the huge difference exists between FGM with inhomogeneity and homogeneous medium with inhomogeneity. The variations of FGM and inhomogeneity size have a great deal of effect on the residual stresses in FGM.
Authors: Zuzana Hutyrová, Imrich Orlovský
Abstract: This paper present problem of the examination of the parameters of cutting process on the micro-geometric and macro-geometric parameters after the turning of composite material with natural reinforcement (material is combination of two different phases the plastic matrix and wood flour). The article deals with effect of feed rate and cutting speed to roundness deviation and maximum roughness depth. The results were analyzed using device of surface roughness, roundness/cylindricity and digital microscopic camera. From the result, the surface roughness are mostly influenced by feed rate.
Authors: Tsuyoshi Yukimoto, Hiroshi Utsunomiya, Tetsuo Sakai
Abstract: 1050 aluminum sheet was cold-rolled by 50% with mineral oil. Hardness was measured on longitudinal section through the thickness of the rolled sheet. The overall hardness statistics of the as-rolled sheet followed the normal (Gaussian) distribution. Though the sheet was rolled under good lubrication, considerable redundant shear deformation was introduced beneath the surfaces by friction. The layers beneath the surfaces showed higher hardness than the center. The hardness subset statistics in one layer in the thickness also followed normal distribution. Isothermal changes in Vickers hardness statistics and in tensile properties during annealing at 548K were investigated. Beneath the surfaces, the recrystallization initiated and completed earlier than the center. The fully recrystallized sheet also shows the normal distribution of hardness, however the standard deviation is much smaller than that before annealing. The layers beneath the surfaces show lower hardness than the center after recrystallization. The partially recrystallized sheet shows bi-modal distribution of hardness. The partially recrysrallized sheet shows slightly better tensile-elongation balance than both the as-rolled sheet and the sheet-fully recrystallized.
Authors: V.A. Ignatchenko, D.S. Tsikalov
Abstract: The dynamic susceptibility and the one-dimensional density of states (DOS) of an initially sinusoidal superlattice (SL) with simultaneous presence of two-dimensional (2D) phase inhomogeneities that simulate the deformations of the interfaces between the SL’s layers and three-dimensional (3D) amplitude inhomogeneities of the layer material of the SL were investigated. An analytical expression for the averaged Green’s function of the sinusoidal SL with 2D phase inhomogeneities was obtained in the Bourret approximation. It was shown that the effect of increasing asymmetry of heights of the dynamic susceptibility peaks at the edge of the Brillouin zone of the SL, which was found in [6] at increasing the rms fluctuations of 2D inhomogeneities, also takes place at increasing the correlation wave number of such inhomogeneities. It was also shown that the increase of the rms fluctuations of 3D amplitude inhomogeneities in the superlattice with 2D phase inhomogeneities leads to the suppression of the asymmetry effect and to the decrease of the depth of the DOS gap.
Authors: V. Kažukauskas, E. Kuprusevičius, Juozas Vidmantis Vaitkus, Kenway M. Smith
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