Effect of Sn-doping on the sintering process of MgB<Subscript>2</Subscript> and its superconductive properties

Bulk (Mg_1.02B₂)_1−x Sn _x samples (x = 0.0, 0.01, 0.03 and 0.05) were synthesized by in situ sintering at 850 °C for one hour. Based on the phase identification and microstructure observation, the Mg₂Sn and Sn impurities are found as the main impurities in Sn-doped samples. According to the magnetization measurements, the low doping level of Sn was observed to have small influence on the grain connectivity, and thus a high critical current density was maintained at low field. However, the values of the critical current density at high field in the Sn-doped samples show a little decrease.     

Interfacial assembly of sandwich mixed (Phthalocyaninato)(Porphyrinato) rare earth triple-decker complexes: Effect of in situ coordination

Interfacial assembly of sandwich mixed (phthalocyaninato)(porphyrinato) rare earth triple-decker complexes [(Pc)Eu(Pc)Eu(TPyP)] (1) and [(TPyP)Sm(Pc)Sm(TPyP)] (2) (Pc = phthalocyaninate, TPyP = meso-tetrakis(4-pyridyl)porphyrinate) has been comparatively studied at the air/pure water and the air/CdCl₂ aqueous solution subphase interfaces. Surface pressure-area isotherms revealed the remarkable increase of limiting mean molecular area of the triple-deckers with the presence of Cd²⁺, suggesting the occurrence of in situ interfacial coordination. The formation of coordination bonds between the pyridyl groups of TPyP macrocycles in the triple-deckers and Cd²⁺ ions from the subphase was further supported by FT-IR spectroscopic data. Electronic absorption measurements showed the formation of J-aggregates of the triple-decker molecules in the interfacial assembled films.     

On the equivalence of linear codes

Certain equivalent conditions are given for the equivalence of linear codes using the properties of the relative subcodes derived from the relative generalized Hamming weight.     

Computational uncertainty analysis in multiresolution materials via stochastic constitutive theory

A stochastic constitutive theory is proposed in this work to propagate microstructure uncertainties in computational multiscale continuum models to bulk multiresolution material behavior. Ubiquitous fine resolution uncertainty sources influencing prediction of material properties based on their structures are categorized in detail, and this research transmits these uncertainties to coarser material resolutions by introducing a stochastic constitutive theory deduced from volume element simulations. To implement the stochastic upscaling process, two advanced uncertainty quantification methods are examined: statistical copula functions and random process polynomial chaos expansion. Both methods confront the mathematical difficulty in randomizing constitutive laws by capturing the marked correlation among constitutive parameters seen in complex materials, thus the results proffer a more accurate probabilistic estimation of constitutive material behavior. The contribution of this work is twofold: uncertainty is propagated from heterogeneous material “structure” to material “property” via the stochastic constitutive theory, and rigorous, data-driven mathematics are formalized to represent complicated dependence structures in multivariate statistical distributions. To the authors’ knowledge, this is the first work in multiresolution mechanics that presents an approach to computationally derive correlation functions from numerical experiments, as opposed, for instance, to assuming one a priori. The method put forth in this research, though quite general, is applied to a mathematical example and plastic, high strength steel alloy for demonstration. Results include stochastic constitutive curve confidence intervals for the material stress–strain response and qualitative comparisons of the two stochastic methods detailed herein.     

厚度方向性能Q345EZ35中厚板的开发

介绍了厚度方向性能Q345EZ35中厚板开发的主要技术和关键环节,该中厚板的实物质量符合国家标准要求。     

Effects of High Magnetic Fields on the Distribution and Alignment of Primary Phases in an Al-12Si-11.8Mg-6.5Ti Alloy

Al-12Si-11.8Mg-6.5Ti alloy samples were solidified in high magnetic fields with various magnetic field gradients. The effects of high magnetic fields on the distribution and alignment of primary phases in the alloys were investigated. It was found that the uniform magnetic field could improve the homogeneity of the primary Mg₂Si, whereas the magnetic field gradient caused the two-layer core grains ((Al,Si)₃Ti and Ti₅Si₄) to segregate at certain regions of the samples depending on the magnetic field gradient direction. The primary (Al,Si)₃Ti strips were oriented with their c axes perpendicular to the magnetic field direction and aligned with their long axes along the magnetic field direction. The changes in the distribution of the primary Mg₂Si and two-layer core grains were caused by the Lorentz force and magnetic force, which could counteract and cause the migration of these phases, respectively. The alignment of the primary (Al,Si)₃Ti could be attributed to the combination of the magnetic orientation and solute redistribution.     

Effect of Compression on the Crystallization Behavior and Corrosion Resistance of Al86Ni9La5 Amorphous Alloy

The effect of compression on the crystallization behavior and corrosion resistance of Al(86)Ni9La5 amorphous ribbons was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning elec-tron microscopy (SEM) and electrochemistry test. The XRD and TEM results reveal that the compressed Al(86)Ni9La5 ribbons spun with the circumferential speed (R) of 29.3 m/s are in fully amorphous state; however, the compressed ribbons spun with R=14.7 m/s have crystalline phases embedded in the amorphous matrix. The SEM images indicate that after compression, the toughness of the ribbons increases. Electrochemical results show that the compression decreases the stability of the passive film of the Al(86)Ni9La5 amorphous ribbons, because of the compression-introduced free volume, shear bands and crystalline phases; meanwhile, with R=14.7 m/s, the compression-induced crystalline phases in the Al(86)Ni9La5 ribbons increase the corrosion potential.     

A Lie-group adaptive differential quadrature method to identify an unknown force in an Euler–Bernoulli beam equation

We recover an unknown space–time-dependent force in an Euler–Bernoulli beam vibration equation by an effective combination of the Lie-group adaptive method (LGAM) and the differential quadrature method (DQM). The layer-stripping technique is used to simplify this identification problem. The DQM is a feasible tool to semi-discretize the Euler–Bernoulli beam equation into a system of ordinary differential equations (ODEs) in time. Then, we can develop a two-point Lie-group equation to recover the unknown force through a few iterations. The success of the present method hinges on a rationale that the local in time ODEs and the global in time algebraic Lie-group equation have to be self-adapted during the iteration processes. The feasibility, accuracy and efficiency of the present method are assessed by comparing the estimated results with some exact solutions.