Self-equilibrium and super-stability of truncated regular hexahedral and octahedral tensegrity structures

This paper presents conditions for self-equilibrium as well as super-stability of the truncated regular hexahedral and octahedral tensegrity structures. Their symmetry can be described by octahedral group in group representation theory, and furthermore, their force density matrix is analytically rewritten in the symmetry-adapted form. The condition for self-equilibrium, in terms of force densities, is found by satisfying the non-degeneracy condition for a tensegrity structure. The condition for super-stability, also in terms of force densities, is further presented by guaranteeing positive semi-definiteness of the force density matrix

Magneto-Fluid Coupling - Eruptive Events in the Solar Corona

By modelling the coronal structures by "slowly" evolving Double-Beltrami two-fluid equilibria (created by the interaction of the magnetic and velocity fields), the conditions for catastrophic transformations of the original state are derived. It is shown that, at the transition, much of the magnetic energy of the original state is converted to the the flow kinetic energy.Comment: 4 pages of two-column text (Latex) plus 3 pages of figures, submitted to The Astrophysical Journal Letter

Optimization of Link Member of Eccentrically Braced Frames for Maximum Energy Dissipation

An optimization method is presented for design of an eccentrically braced frame (EBF), which is used as a passive control device for seismic design of building frames. The link member between the connections of beams and braces of EBF is reinforced with stiffeners in order to improve its stiffness and plastic deformation capacity. We present a method for optimizing the locations and thicknesses of the stiffeners of the link member. The optimal solutions are found using a heuristic approach called tabu search. The objective function is the plastic dissipated energy before failure. The deformation of the link member under static cyclic loads is simulated using a finite element analysis software package. It is demonstrated in the numerical examples that the dissipated energy can be increased through optimization within small number of analyses.This work is partially supported by the Kajima Foundation’s Research Grant and a Grant-in-Aid for Scientific Research from JSPS, Japan

Comparison of formaldehyde and methanol fixatives used in the detection of ion channel proteins in isolated rat ventricular myocytes by immunofluorescence labelling and confocal microscopy

In this study, a fixation protocol using a 10% neutral buffered formalin (FA) solution and another protocol using a methanol (MeOH) solution were compared for detection of ion channels, Kv1.5, Kv4.2, Cav1.2, Kir6.2, Nav1.5 and Nav1.1 in rat myocytes by immunolabelling. Kv1.5 and Kv4.2 at intercalated discs and Cav1.2 at transverse tubules were not detected by FA but were detected by MeOH. Kir6.2 at transverse tubules and Nav1.5 at sarcolemma were detected by FA but not by MeOH. It is suggested that both FA and MeOH fixation protocols should be used for the detection of cardiac ion channels by immunolabellin

Low-Cost Double Curvature: Geometrical and Structural Potentials of Rectangular, Cold-Bent Glass Construction

The realization of doubly curved façades often requires large investments in fabrication equipment and produces additional waste through subtractive fabrication processes and non-reusable molds. In glass construction, elastic bending techniques can be used for small curvatures. This paper continues previous research of the authors on bending rectangular glass elements into irregularly curved panels. First, we analyze the stresses occurring in cold bent glass during assembly, thus defining a particlespring model which is able to compute approximate stresses in real-time during the bending procedure. In a second step, we compare the structural performance of the bent glass with that of flat panels using FE-analysis. Finally, we illustrate the implementations on multi-panel façade layouts. We analyze the dependencies between curvature, gap-tolerance and panelization. We present a method to minimize gap-tolerances by optimizing the distribution of surface curvature. Our results highlight the structural and geometrical potentials and possible applications for curved glass construction