Two-dimensional modelling of solid-fluid composites

The purpose of this paper is to apply biomimetic-designed composites to artificial structures. From the results of numeric modelling analysis in biomechanics, we have learned the bone structures optimized to lighten weight and understood that the solid-fluid composite structure of the cancellous bone at the joint part works to distribute the joint load perfectly. In this paper, the two-dimensional honeycomb structure filled with fluid was investigated by way of a simplified solid-fluid composite material model of the cancellous bone. Hybrid finite element analyses illustrated that the solid-fluid phase interaction is effective in dispersing compressive load. In-plane indentation tests were carried out and in-plane deformation distributions of the solid-fluid composite specimens were measured. Consequently, as for the solid-fluid composite specimens whose cells were filled up with glycerine, a good enough cell deformation mode was obtained.     

Mechanical properties of acid-cured epoxide resins with different network structures

Static and dynamic mechanical properties of cured epoxide resins based on ester bonds, ether bonds, or a mixture of ester and ether bonds were investigated. Their network structures were estimated from the results of gel content before and after saponification, and conversion of functional groups. It was found that cured epoxide resins based on a mixture of ester and ether bonds indicate intermediate properties between the resins based on ester bonds and the resins based on ether bonds. Both dynamic and static mechanical properties were strongly affected by their network density and their segmental structures suggested in this paper.     

Nonlinear constitutive equations for transient creep of viscoelastic polymers including the effect of hydrostatic pressure

The behaviour of polymers is known to be significantly influenced by the hydrostatic pressure in creep deformation or elastic-plastic deformation. The effect of the third stress invariant on the nonlinear viscoelastic deformation is much smaller than that of the hydrostatic pressure. In this paper, a constitutive equation for transient creep is proposed, which includes the effect of the hydrostatic pressure on the yield function. The creep and plastic strains or the creep strain rate converge to zero with increasing hydrostatic pressure. The proposed constitutive equation is in good agreement with the actual creep data of cellulose nitrate and cellulose acetate, under various combinations of superimposed tensile and hydrostatic loadings.     

A single-chip 16-bit 25-ns real-time video/image signal processor

A single-chip 16-b microprogrammable real-time video/image signal processor (VISP) has been developed for use in real-time motion picture encoding during low-bit-rate transmission for TV conference systems. In addition to stand-alone microprocessor functional units, the VISP integrates a high-speed variable seven-stage pipeline arithmetic circuit for video/image data processing and various controllers for easy I/O (input/output) and multiple-chip connections A 25-ns instruction cycle time is attained by using complementary reduced-swing CMOS logic circuits. The chip (14 mm×13.4 mm) was fabricated using a double-metal-layer 1.2-μm CMOS process technology and contains 220000 transistors     

Comparison of the effects of hydrostatic pressure and the third invariant of deviatoric stress tensor on non-linear viscoelastic deformation in cellulose nitrate

The behaviour of polymers is qualitatively known to be remarkably influenced by the hydrostatic pressure on the general plastic deformation, unlike most metals. However, as polymers behave differently in simple tension and compression, they may be influenced by the effect of the third invariant of deviatoric stress tensor as well as hydrostatic pressure. In this paper, a comparison of the effects of the hydrostatic pressure and the third invariant of deviatoric stress tensor on the non-linear viscoelastic deformation of cellulose nitrate are discussed quantitatively, following experiments of torsion of tubular specimens and simple tension of uniaxial specimens. As the result, the effect of the third invariant of deviatoric stress tensor on the non-linear viscoelastic deformation in cellulose nitrate was found to be much smaller than that of the hydrostatic pressure.     

The firing squad synchronization problem for graphs

In this paper, we give a solution of the Firing Squad Synchronization Problem for graphs. The synchronization times of solutions which have been obtained are proportional to the number of nodes of a graph. The synchronization time of our solution is proportional to the radius r_G of a graph (G (3r_G + 1 or 3r_G time units, where r_G, is the longest distance between the general and any other node of G. This synchronization time is minimum for an infinite number of graphs.     

Substrate effect of STM-induced luminescence from porphyrin molecules

We investigated scanning tunneling microscope (STM)-induced luminescence from Meso-tetrakis (3,5-di-tertiarybutyl-phenyl) porphyrin (H₂TBPP) thin films on various metal substrates (copper, platinum and silver) under ambient conditions. Molecular fluorescence similar to the corresponding photoluminescence was observed from the H₂TBPP/Ag and H₂TBPP/Pt, but not H₂TBPP/Cu, depending on the spectra of the surface plasmons of the substrates. The results support the mechanism that intense molecular fluorescence from porphyrin film on the noble metals is a result of enhancement of molecular excitation by substrate surface plasmons.     

Temperature-dependent mechanical properties and constitutive equation of cellulose nitrate

The strain-time response under tensile loading (creep tests) and the stress strain response under constant tensile stress rate (proportional loading tests) have been evaluated at 4 temperatures 20, 45, 55, and 65°C, for samples of cellulose nitrate. A time-dependent constitutive equation (or stress-strain relation) for the nonlinear visco-elastic material is deduced from invariant theory with a hypothesis of a creep potential. The procedure for determining the seven material constants involved in the deduced constitutive equation is described for the creep and proportional loading tests and the variation of these constants with temperature is presented. The deduced constitutive equation gives good agreement with the actual observations for the creep and proportional loading tests, independent of the values of temperature, creep stress, or stress rate.