Effect of the Matrix and Matrix Bonding on the Creep Behavior of a Unidirectional Carbon–Carbon Composite

Creep tests were performed on single-bundle carbon–carbon specimens at high temperatures (>2310°C) and at high stress levels (>770 MPa). It was found that the creep was very strongly dependent on the filament–matrix interfacial bond. When the bond was good, the typical creep was 3.6% after 5.9 h with the primary creep a high percentage of the total deformation. When the bond was absent (dry bundle), rupture with strain was approximately 140%, and it occurred after only 0.39 h. The marked improvement in creep resistance is attributed to the ability of the matrix to distribute loads evenly and to produce a plastic flow inhibiting triaxial stress state among the filaments.     

Intelligent temporal subsampling of American Sign Language using event boundaries.

How well can a sequence of frames be represented by a subset of the frames? Video sequences of American Sign Language (ASL) were investigated in two modes: dynamic (ordinary video) and static (frames printed side by side on the display). An activity index was used to choose critical frames at event boundaries, times when the difference between successive frames is at a local minimum. Sign intelligibility was measured for 32 experienced ASL signers who viewed individual signs. For full gray-scale dynamic signs activity-index subsampling yielded sequences that were significantly more intelligible than when every mth frame was chosen. This result was even more pronounced for static images. For binary images, the relative advantage of activity subsampling was smaller. We conclude that event boundaries can be defined computationally and that subsampling from event boundaries is better than choosing at regular intervals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tables of the Inverse Laplace Transform of the Function [... formula ...]

The inverse transform, g(t) = ?^?1(e^?sβ), 0 < β < 1, is a stable law that arises in a number of different applications in chemical physics, polymer physics, solid-state physics, and applied mathematics. Because of its important applications, a number of investigators have suggested approximations to g(t). However, there have so far been no accurately calculated values available for checking or other purposes. We present here tables, accurate to six figures, of g(t) for a number of values of β between 0.25 and 0.999. In addition, since g(t), regarded as a function of β, is uni-modal with a peak occurring at t = t_max we both tabulate and graph t_max and 1/g(t_max) as a function of β, as well as giving polynomial approximations to 1/g(t_max).     

A simplified nonlinear stability analysis of an imperfect rectangular two-bar frame

A simplified nonlinear stability analysis for moderately large rotations and small strains is performed on a rectangular two-bar frame subjected to a concentrated eccentrically applied joint load. Such a simplification consisting of adopting linear kinematic relations leads to very reliable results for the initial postbuckling path in the vicinity of the critical point of the above imperfect frame. The existence of an asymmetric bifurcation point is thoroughly discussed and a direct evaluation of the bifurcational load is readily obtained. Using this technique the effect of imperfection sensitivity is also addressed. A qualitative analysis associated with the physical phenomenon yields a substantial reduction of the computational work. The efficiency and reliability of this approximate nonlinear stability analysis proposed herein is illustrated by means of several examples for which a lot of numerical results based on a more accurate nonlinear analysis are available.     

Tidal turbines harness the power of the sea

Just as there were once 10?000 windmills across Europe, countless water mills helped power the rural economy and then the industrial revolution. And, just as reinforced plastics have supported the 21st century reincarnation of windmills as wind turbines, so they are beginning to contribute to the next likely large-scale commercial renewable energy source - water current power. George Marsh reports.     

Supplementation of the diet with the functional fiber PolyGlycoplex? is well tolerated by healthy subjects in a clinical trial

Background  

The relationship of dietary fiber to overall health is of great importance, as beneficial effects have been demonstrated with the use of fiber from diverse sources, some traditional, other novel. PolyGlycopleX^? (PGX^?) is a unique proprietary product composed of three water-soluble polysaccharides, that when processed using novel technology give rise to a final product – a soluble, highly viscous functional fiber.     

Adaptive mental mechanisms: Their role in a positive psychology.

Psychology needs a metric for positive mental health that would be analogous to the IQ tests that measure above average intelligence. The Defensive Function Scale of the DSM-IV offers a possible such metric. In the present article the author links the transformational qualities of defenses at the mature end of the Defensive Function Scale (altruism, suppression, humor, anticipation, and sublimation) to positive psychology. First, the methodological problems involved in the reliable assessment of defenses are acknowledged. Next, the use of prospective longitudinal study to overcome such difficulties and to provide more reliable definition and measurement of defenses is outlined. Evidence is also offered that, unlike many psychological measures, the maturity of defenses is quite independent of social class, education, and IQ. Last, evidence is offered to illustrate the validity of mature defenses and their contribution to positive psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)