Local field factors in a polarized two-dimensional electron gas

We derive approximate expressions for the static local field factors of a spin polarized two-dimensional electron gas which smoothly interpolate between their small- and large-wavevector asymptotic limits. For the unpolarized electron gas, the proposed analytical expressions reproduce recent diffusion Monte Carlo data. We find that the degree of spin polarization produces important modifications to the local factors of the minority spins, while the local field functions of the majority spins are less affected.Comment: 8 pages, 10 figure

FE parametric study of RWS/WUF-B moment connections with elliptically-based beam web openings under monotonic and cyclic loading

This paper provides numerical results investigating the behaviour of steel web-perforated beams with different shaped single openings located close to beam-to-column connections under monotonic and cyclic loading. In particular, the beams considered feature circular and patented elliptically-based perforations. Non-standard elliptically-based perforations have been proposed previously and are optimally designed to maximise resistance against Vierendeel moments and web-post buckling under static loads at the ultimate limit state. Comprehensive parametric nonlinear finite element analyses using the commercial FE package ANSYS were conducted. Initially, a FE model of the beam-to-column WUF-B moment connection was developed and calibrated against pertinent experimental results found in the literature. Next, parametric analyses were undertaken to assess the RWS/WUF-B connection regarding strength (moment), deformation (rotation) and column web shear panel zone deformation for different shapes of beam web perforations, hole sizes, and their locations. The study concludes that larger web openings are capable of moving the plastic hinge away from the column face and the CJP weld. Also, interstory drifts can be controlled with the wise use of the beam web opening size, shape, and distance from the face of the column, as suggested in the paper. Following, a step-by-step design process for RWS/WUF-B connection is presented

Optical and magneto-optical properties of Fe 4−x Co x (x=1–3)

We report a systematic study of the electronic, optical, and magneto-optical properties of the Fe4-xCox (x = 1–3) compounds using the full-potential linearized augmented plane waves (FPLAPW) method within the local spin density approximation (LSDA). Pure Fe (x = 0) and Co (x = 4) have also been studied, the latter in hcp as well as bcc structure, to offer a better comparison. A good agreement is obtained between calculated optical conductivity spectra and experimental data. We note that the magneto-optical properties of these compounds are found to be more akin to those of bcc Co (which has MOKE very similar to that of bcc Fe) than to those of hcp Co. This shows strong impact of the environment on the MOKE of these compounds. With respect to the elemental values, the magnetic moments at Fe sites are found to be larger in general, while those at Co sites are almost the same. However, interestingly, despite their larger magnetic moment, the Kerr rotation remains comparable to that of bcc Fe for most of the energy range. The origin of Kerr spectra has been explained in terms of optical transitions