THERMAL STRESS ANALYSIS OF THERMOVISCOELASTIC HOLLOW CYLINDER WITH TEMPERATURE-DEPENDENT THERMAL PROPERTIES

ABSTRACT

We analyzed the thermal stress on a thermoviscoelastic hollow cylinder with temperature-dependent thermal properties with the finite difference method. It was gradually heated at the inner surface and the outer surface was kept at the initial temperature. The cylinder material was thermorheologically simple and had a temperature-dependent coefficient of linear thermal expansion, thermal conductivity, and thermal diffusivity (and/or specific heat). A bisphenol A–type epoxy resin was chosen as the thermoviscoelastic material of the cylinder for numerical analysis. Based on these results, we discuss the effects of thermoviscoelasticity and temperature-dependent thermal properties on the stress field.     

Redistribution of phosphatidylethanolamine at the cleavage furrow of dividing cells during cytokinesis

Ro09-0198 is a tetracyclic polypeptide of 19 amino acids that recognizes strictly the structure of phosphatidylethanolamine (PE) and forms a tight equimolar complex with PE on biological membranes. Using the cyclic peptide coupled with fluorescence-labeled streptavidin, we have analyzed the cell surface localization of PE in dividing Chinese hamster ovary cells. We found that PE was exposed on the cell surface specifically at the cleavage furrow during the late telophase of cytokinesis. PE was exposed on the cell surface only during the late telophase and no alteration in the distribution of the plasma membrane-bound cyclic peptide was observed during the cytokinesis, suggesting that the surface exposure of PE reflects the enhanced scrambling of PE at the cleavage furrow. Furthermore, cell surface immobilization of PE induced by adding the cyclic peptide coupled with streptavidin to prometaphase cells effectively blocked the cytokinesis at late telophase. The peptide-streptavidin complex treatment had no effect on furrowing, rearrangement of microtubules, and nuclear reconstitution, but specifically inhibited both actin filament disassembly at the cleavage furrow and subsequent membrane fusion. These results suggest that the redistribution of the plasma membrane phospholipids is a crucial step for cytokinesis and the cell surface PE may play a pivotal role in mediating a coordinate movement between the contractile ring and plasma membrane to achieve successful cell division.     

Determination of elastic moduli for a spherical specimen by resonant ultrasound spectroscopy

Resonant ultrasound spectroscopy (RUS) is based on the principle that mechanical resonant response of solids depends on its elastic moduli, shape and density. Elastic moduli or the other properties can be identified from resonant frequencies as inverse problem. In this study, the method to determine elastic moduli of a spherical specimen without information of resonant mode was described. We confirmed that resonant frequencies have to be measured under condition of free surface, and adequate number of resonant frequencies used in calculation needs enough number to include the sensitive mode to Poisson's ratio. By this method, we determined elastic moduli of BK-7 glass. The calculated frequencies from the elastic moduli determined by this technique had good agreement with the measured, the absolute accuracies for the Δf was less than 0.4%.     

Two Domains of the Parameter Space of the 2D Hubbard Model for High-Tc Superconductors

High-T _c superconducting cuprates have two types of Fermi surfaces: simple-2D-tight-binding-band type (LSCO type) and the much deformed one (Bi2212 type). The difference is attributed to that of band parameter values, i.e., t′ ∼ −0.1 and t″ ∼ 0 versus t′ ∼ −0.3 and t″ ∼ 0.2 in terms of the second- and third-neighbor transfer energies t′ and t″, respectively (energy unit is the nearest-neighbor transfer energy t). Assuming a moderate value of on-site Coulomb energy U ∼ 6 and performing the variational Monte Carlo computation, we found that the two superconducting parameter domains exist in fact around these parameter sets, respectively, in which superconductivity predominates over spin density wave (SDW) due to the latter being at the brink of vanishing. Stripes were obtained in the first domain but tend to disappear in the second. In the latter domain there seems to exist parameter sets for which superconductivity appears without doping.     

Time–temperature dependency of mode II fracture toughness for bisphenol A type epoxy resin

We investigated the mode II fracture toughness (K_IIc) with time and temperature dependence of the bisphenol A type of epoxy resin. We performed an asymmetric four‐point bending test under various conditions of temperature and displacement rate. We found that K_IIc strongly depended on the displacement rate and the temperature, even at room temperature. Moreover, it was governed by the time–temperature equivalence principle in regard to the fracture time. The time–temperature dependency of K_IIc was similar to that of the loss modulus (E″), and the transition of brittle to ductile fractures occurred nearly simultaneously when E″ peaked. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 51–55, 2005     

Development of insulation structure and enhancement of insulationreliability of 500 kV DC GIS

The paper describes the development of insulation structure and enhancement of insulation reliability of 500 kV DC GIS (gas insulated switchgear). Considering problems of metallic particles and charge accumulation on spacers, the developed insulation structure of GIS consisted of three regions, i.e. the spacer, particle scavenging and nonlevitating regions. Particles could be efficiently scavenged, and the developed GIS withstood all insulation specifications with sufficient margins under the clean and particle-contaminated condition. Now, a long-term site test for one year of the 500 kV DC GIS has been continued since October in 1995