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Based on the nonlocal Kirchhoff plate theory, the thermo-electro-mechanical vibration responses are studied for a rectangular piezoelectric nanoplate resting on viscoelastic foundation with various boundary conditions. In doing this, the governing equations of motion are first derived for vibration analysis, where thermo-electro-mechanical loadings, nonlocal effect, piezoelectric effect and viscoelastic foundation have been taken into consideration. Subsequently, the Galerkin strip distributed transfer function method is proposed to solve the governing equations, which enables one to obtain the semi-analytical solutions of natural frequencies for piezoelectric nanoplates with arbitrary boundary conditions. Here, the developed mechanics model is first validated by comparing the obtained results with those available in the literature. Also, the effects of nonlocal parameter, boundary conditions, viscoelastic foundation, external electric voltage, increment temperature, biaxial force and geometric dimensions on the vibration behaviors are carefully examined for the piezoelectric nanoplate. The results demonstrate the efficiency and robustness of the developed model for vibration analysis of a complicated multi-physics system comprising piezoelectric nanoplates, viscoelastic foundation and thermo-electro-mechanical loadings. [ABSTRACT FROM AUTHOR]

Based on nonlocal Euler-Bernoulli beam theory, vibration characteristics are investigated for a horn-shaped single-walled carbon nanotube (SWCNT) which is embedded in a viscoelastic medium and subjected to a longitudinal magnetic field. Governing equations of motion are derived for vibration analysis of horn-shaped SWCNTs, where the Lorentz magnetic force, the surrounding viscoelastic medium and variable cross-section have been taken into consideration. Subsequently, perturbation method (PM) and transfer function method (TFM) are employed to compute the natural frequencies and the corresponding mode shapes for horn-shaped SWCNTs with arbitrary boundary conditions. The obtained results are first compared with the results available in the literature, where good agreement is achieved. The validation of the model is followed by a detailed parametric study of the effects of nonlocal parameter, taper parameter and longitudinal magnetic field on the vibration of horn-shaped SWCNTs. The results demonstrate the efficiency of the developed model for vibration analysis of a complicated multi-physics system comprising horn-shaped SWCNTs, viscoelastic medium and a magnetic field in longitudinal direction. [ABSTRACT FROM AUTHOR]

Abstract: The microstructure and texture evolution of Mg98.5Y1Zn0.5 and Mg92.5Y5Zn2.5 (atomic percent) alloys during hot extrusion were systematically investigated. The coarse LPSO phases with higher volume fraction (~57%) suppressed the twinning generation in the initial stage of extrusion, and accelerated the dynamic recrystallization through the particle deformation zones. Therefore, the volume fraction of DRXed grains in as-extruded Mg92.5Y5Zn2.5 alloy was much higher than that of Mg98.5Y1Zn0.5 alloy. The intensive recrystallization process resulted in the conventional basal texture weakening, although the texture evolution was mainly dominated by flow behavior. The dynamic recrystallization behavior in Mg92.5Y5Zn2.5 alloy restricted the formation of deformation texture, and thus the more random texture was observed during the whole extrusion process. [Copyright &y& Elsevier]

Tensile yield strength of extruded Mg–5.3Zn–0.5Ca–0.5Ce/La (weight percent) alloy is remarkably increased to 316 MPa from 163 MPa, via the warm rolling process. The tension twinning can be activated after low-strain (5–21%) rolling, and the dynamic recrystallization occurs with increasing rolling reduction. The dislocations are gradually accumulated within the original grains during the rolling, and the number fraction of low angle grain boundary is increased. The coarse secondary phases are gradually broken into small pieces, due to the increased rolling deformation. The weak fiber texture with 10 1 ̅ 0 parallel to extrusion direction in the extruded alloy is modified to the typical 0002 10 1 ̅ 0 texture after rolling, and the yield strength is notably improved, because of the multiple strengthening effects (grain refinement, work hardening, dispersion and texture). A good balance between strength (> 310 MPa) and ductility (~ 9.5%), has been achieved through the warm rolling. [ABSTRACT FROM AUTHOR]

As-cast Mg–5.3Zn–0.6Ca (weight percent) alloy was indirectly extruded at 300 °C with different deformation rates (ram speeds of 0.1, 0.3, 0.5 mms − 1 ), and the microstructure, texture and mechanical properties of the as-extruded alloys were investigated in the current study. With the increase of deformation rates, the average size and volume fraction of dynamic recrystallized grains were remarkably increased. The basal fiber texture became weak in the as-extruded alloy with higher volume fraction of recrystallized grains, because most of the basal planes in these grains were tilted to extrusion direction about 30–40°. The higher deformation rate decreased the tensile yield stress due to the grain coarsening and basal texture weakening, while the elongation was improved, which was resulted from the enhanced work hardening rate. [ABSTRACT FROM AUTHOR]

Abstract: Atmospheric particulate matter with aerodynamic diameter <2.5 μm (PM2.5) was collected at Xujiahui and Baoshan in Shanghai, China in 2010 when the World Expo took place. Eight nitrated polycyclic aromatic hydrocarbons (NPAHs) were analyzed. Significant reductions in individual NPAH (69–324%) and the mean ΣNPAH (about 140%) concentrations were measured during the Expo period. In order to minimize the influence from the meteorological condition, individual NPAH concentrations of 2010 Expo period were compared with those in the same time period from 2008. Significant effects from the source control measures were revealed, i.e., the individual NPAH concentration reductions ranged between 31% and 477% at the mixed residential and industrial Baoshan site, and only 0–88% at the urban Xujiahui site. The relatively high 2-nitrofluoranthene/1-nitropyrene ratio values (11–31) suggested a predominance of photochemical formation of NPAHs in the atmosphere during the Expo period. It could be concluded that the air quality during the Shanghai World Expo 2010 was benefited from the following three factors; (1) source control measures during the Expo period, i.e., prohibition of open field biomass burning in surrounding areas, (2) the three-year plan implemented from October 1, 2009, including construction sites shut-down, flue-gas desulfurization/denitrification and the vehicle upgradation and (3) the Asian monsoon which brings in clean air from the ocean during spring and summer into Shanghai. [Copyright &y& Elsevier]