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• Industrial-scale continuous PAN fibers to carbon fibers were prepared. • Stabilization behaviors of PAN fibers under different atmosphere are investigated. • Graphite layers are associated with cross-linking structures of PAN oxidative fibers. • Low-oxygen has negative influence on tensile modulus of carbon fibers. Understanding and regulating the oxidative stabilization behavior of polyacrylonitrile (PAN) precursor fibers are critical subjects of high-performance carbon fiber production technologies. Here, we performed continuous stabilization and carbonization of PAN fibers at industrial carbon fiber production lines in different locales (different oxygen partial pressure in atmosphere), and investigated the microstructural evolution of the fibers with a systematically analysis at different stages. Influence of oxygen partial pressure in oxidative stabilization atmosphere on tensile modulus of the obtained carbon fibers was obvious. Oxygen diffused into PAN fibers during oxidative stabilization, more homogeneous and crosslinked structures generated under higher oxygen partial pressure atmosphere, and gave the stabilized fibers lower skin-core ratio. The graphite layers gradually generated in the subsequent carbonization stages, and the gathered graphite layers transformed into graphite microcrystalline, the wide-angle x-ray diffraction (WAXD) demonstrated that higher oxygen partial pressure conditions contributed to the generation of higher crystallite preferred orientation and bigger crystallite size, Raman spectroscopy also confirmed the obtained carbon fibers with higher oxygen partial pressure conditions possessed more ordered graphite structures. Thus, relatively higher oxygen partial pressure in air gave the stabilized fibers more crosslinked structures, and contributed to the formation of high-performance carbon fibers. [ABSTRACT FROM AUTHOR]

In this paper, a new limiter using weighted essentially non-oscillatory (WENO) methodology is investigated for the Runge–Kutta discontinuous Galerkin (RKDG) methods for solving hyperbolic conservation laws. The idea is to use the high-order DG solution polynomial itself in the target cell and the linear polynomials which are reconstructed by the cell averages of solution in the target cell and its neighboring cells to reconstruct a new high-order polynomial in a manner of WENO methodology. Since only the linear polynomials need to be prepared for reconstruction, this limiter is very simple and compact with a stencil including only the target cell and its immediate neighboring cells. Numerical examples of various problems show that the new limiting procedure can simultaneously achieve uniform high-order accuracy and sharp, non-oscillatory shock transitions. [ABSTRACT FROM AUTHOR]

This paper examines the phrase #bindersfullofwomen as an example of searchable talk in the microblogging sphere of Twitter. The data were collected and sampled in terms of its temporal development on Twitter. Drawing on the content analysis combined with descriptive statistics, the paper identified and compared the Twitter users as Journalist users and Ordinary users who are engaged with Twitter communication. It shows that Journalists tend to initiate the topic at the early stage of communication. Soon afterwards, the Ordinary participants dominate the Twitter communication. The tweets are textually characterized into three different categories on the formal grounds: Hashtags, Hashtags plus texts and anything with a link" or "a retweet", in the heteroglossic context of micro-blogging sphere. The categorization of tweets contributes as a methodology to distinguish the discourse practice performed by different Twitter users. The results show that both Journalist and Ordinary favor to post the informative tweets throughout the sampled period. The quantity of interactive tweets is becoming less favorable; however, in contrast, the tweets on the indeterminate plane gain high popularity from the early phase of the period. Our comparison indicates that the boundary between Journalist and Ordinary seems to be indistinct in terms of their contents. [ABSTRACT FROM AUTHOR]

Abstract: Microstructure, second-phase particles and mechanical properties of the joint along the thickness of plate during friction stir welded 2219 aluminum alloy thick plate using different shapes pin were investigated in this paper. The top presented larger equiaxed recrystallized grain structure and finer second-phase particles compared to the middle and bottom. Thermo-mechanically affected zone and boundary were more optically distinct on the advancing side in comparison with the retreating side. Grain size and particles were much finer and dispersed using the first tool with three spiral flute or at the lower rotational speed of 300rpm. The strength and ductility in top slices was slightly higher than that in middle and bottom, increased with increasing traverse speed from 60 to 100mm/min or the decrease of rotational speed from 500 to 300rpm using the first tool. The mechanical properties using the second tool was lower than that of first tool, which was consistent with the hardness curves. [Copyright &y& Elsevier]

Abstract: Plates of aluminum alloys 2219-T62 were joined in a butt joint by friction stir welding. The residual stresses on the top and bottom surfaces were measured using the hole-drilling strain-gauge method. In the test specimen, it was found that the residual stresses on the top surface peaked at about 171MPa, while the value reached 243MPa for the weld with tunnel defect and had the conventional “M” profile with tensile stress peaks in the heat-affected zone. Those attached on the bottom surface had the inverted “V” profile with tensile stress peaks in the weld centre and the corresponding value was 99.4MPa. Meanwhile, with the increase of rotary speed, the longitudinal residual stress decreased on the top surface, but increased on the bottom surface. [Copyright &y& Elsevier]

Abstract: The pitting corrosion of different positions (Top, Middle and Bottom) of weld nugget zone (WNZ) along thickness plate in friction stir welded 2219-O aluminum alloy in alkaline chloride solution was investigated by using open circuit potential, cyclic polarization, scanning electron microscopy and atomic force microscope. The results indicate that the material presents significant passivation, the top has highest corrosion potential, pitting potential and re-passivation potential compared with the bottom and base material. With the increase of traverse speed from 60 to 100mm/min or rotary speed from 500 to 600rpm, the corrosion resistance decreases. [Copyright &y& Elsevier]

In some complex viscoelastic mediums, it is ubiquitous that absorbing and desorbing surrounding Brownian particles randomly occur in coupled systems. The conventional method is to model a variable-mass system driven by both multiplicative and additive noises. In this paper, an improved mathematical model is created based on generalized Langevin equations (GLE) to characterize the random interaction with locally fluctuating number of coupled particles in the elastically coupled factional Brownian motors (FBM). By the numerical simulations, the effect of fluctuating interactions on collective transport behaviors is investigated, and some abnormal phenomena, such as cooperative behaviors, stochastic resonance (SR) and anomalous transport, are observed in the regime of sub-diffusion. [ABSTRACT FROM AUTHOR]