Topological derivation of shape exponents for stretched exponential relaxation

In homogeneous glasses, values of the important dimensionless stretched-exponential shape parameter beta are shown to be determined by magic (not adjusted) simple fractions derived from fractal configuration spaces of effective dimension d* by applying different topological axioms (rules) in the presence (absence) of a forcing electric field. The rules are based on a new central principle for defining glassy states: equal a priori distributions of fractal residual configurational entropy. Our approach and its beta estimates are fully supported by the results of relaxation measurements involving many different glassy materials and probe methods. The present unique topological predictions for beta typically agree with observed values to ~ 1% and indicate that for field-forced conditions beta should be constant for appreciable ranges of such exogenous variables as temperature and ionic concentration, as indeed observed using appropriate data analysis. The present approach can also be inverted and used to test sample homogeneity and quality.Comment: Original 13 pages lengthened to 21 pages (longer introduction, added references and discussion of new experimental data published since original submission

Air data measurement system for space shuttle

It is concluded that air data measurements of angle of attack and sideslip are needed to control the space shuttle vehicles. The basis for this conclusion, along with recommended sensor design and implementation, are described

Determination of solid mass fraction in partially frozen hydrocarbon fuels

Filtration procedures alone are insufficient to determine the amounts of crystalline solid in a partially frozen hydrocarbon distillate fraction. This is due to the nature of the solidification process by which a large amount of liquid becomes entrapped within an interconnected crystalline structure. A technique has been developed to supplement filtration methods with an independent determination of the amount of liquid in the precipitate thereby revealing the actual value of mass percent crystalline solid, %S. A non-crystallizing dye is injected into the fuel and used as a tracer during the filtration. The relative concentrations of the dye in the filtrate and precipitate fractions is subsequently detected by a spectrophotometric comparison. The filtration apparatus was assembled so that the temperature of the sample is recorded immediately above the filter. Also, a second method of calculation has been established which allows significant reduction in test time while retaining acceptable accuracy of results. Data have been obtained for eight different kerosene range hydrocarbon fuels

Viability and performance of demountable composite connectors

AbstractMaterial production, and associated carbon emissions, could be reduced by reusing products instead of landfilling or recycling them. Steel beams are well suited to reuse, but are difficult to reuse when connected compositely to concrete slabs using welded studs. A demountable connection would allow composite performance but also permit reuse of both components at end-of-life. Three composite beams, of 2m, 10m and 5m length, are constructed using M20 bolts as demountable shear connectors. The beams are tested in three-, six- and four-point bending, respectively. The former two are loaded to service, unloaded, demounted and reassembled; all three are tested to failure. The results show that all three have higher strengths than predicted using Eurocode 4. The longer specimens have performance similar to previously published comparable welded-connector composite beam results. This suggests that demountable composite beams can be safely used and practically reused, thus reducing carbon emissions

Temperature in nonequilibrium systems with conserved energy

We study a class of nonequilibrium lattice models which describe local redistributions of a globally conserved energy. A particular subclass can be solved analytically, allowing to define a temperature T_{th} along the same lines as in the equilibrium microcanonical ensemble. The fluctuation-dissipation relation is explicitely found to be linear, but its slope differs from the inverse temperature T_{th}^{-1}. A numerical renormalization group procedure suggests that, at a coarse-grained level, all models behave similarly, leading to a two-parameter description of their macroscopic properties.Comment: 4 pages, 1 figure, final versio

Sources of total, non-milk extrinsic, and intrinsic and milk sugars in the diets of older adults living in sheltered accommodation

The WHO recommends limiting non-milk extrinsic sugars (NMES) consumption to ≤ 10 % energy to reduce the risk of unhealthy weight gain and dental caries, and to restrict frequency of intake to ≤ 4 times/d to reduce risk of dental caries. Older adults, especially those from low-income backgrounds, are at increased risk of dental caries, yet there is little information on sugars intake (frequency of intake and food sources) in this age group. The aim of this report is to present baseline data from a community-based dietary intervention study of older adults from socially deprived areas of North East England, on the quantity and sources of total sugars, NMES, and intrinsic and milk sugars, and on frequency of NMES intake. Dietary intake was assessed using two 3-d estimated food diaries, completed by 201 participants (170 female, thirty-one male) aged 65–85 years (mean 76·7 (sd 5·5) years) recruited from sheltered housing schemes. Total sugars represented 19·6 %, NMES 9·3 %, and intrinsic and milk sugars 10·3 % of daily energy intake. Eighty-one (40·3 %) exceeded the NMES intake recommendation. Mean frequency of NMES intake was 3·4 times/d. The fifty-three participants (26·4 %) who exceeded the frequency recommendation ( ≤ 4 times/d) obtained a significantly greater percentage of energy from NMES compared with those participants who met the recommendation. The food groups ‘biscuits and cakes’ (18·9 %), ‘soft drinks’ (13·1 %) and ‘table sugar’ (11·1 %) made the greatest contributions to intakes of NMES. Interventions to reduce NMES intake should focus on limiting quantity and frequency of intake of these food groups

Is there a "native" band gap in ion conducting glasses?

It is suggested that the spectrum of ion site energies in glasses exhibits a band gap, establishing an analogy between ion conducting glasses and intrinsic semiconductors. This implies that ion conduction in glasses takes place via vacancies and interstitial ions (as in crystals).Comment: 3 page

Heat capacity at the glass transition

A fundamental problem of glass transition is to explain the jump of heat capacity at the glass transition temperature $T_g$ without asserting the existence of a distinct solid glass phase. This problem is also common to other disordered systems, including spin glasses. We propose that if $T_g$ is defined as the temperature at which the liquid stops relaxing at the experimental time scale, the jump of heat capacity at $T_g$ follows as a necessary consequence due to the change of system's elastic, vibrational and thermal properties. In this picture, we discuss time-dependent effects of glass transition, and identify three distinct regimes of relaxation. Our approach explains widely observed logarithmic increase of $T_g$ with the quench rate and the correlation of heat capacity jump with liquid fragility