Critical Review of the Thermophysical Properties of Fast-Reactor Fuel

This paper identifies the fuel properties for which more data are needed for fast-reactor safety analysis. In addition, a brief review is given of current research on the vapor pressure over liquid UO₂ and (U, Pu)O_2-x the solid-solid phase transition in actinide oxides, and the thermal conductivity of molten urania.     

Formation and Properties of Calcium Aluminosilicate Glasses

The glass-forming region for calcium aluminosilicate glasses has been determined. A number of properties of these glasses (thermal expansion coefficient, glass transformation and dilatometric softening temperature, and refractive index) have been studied. The results of these measurements suggeq that the structures of these glasses may not as closely resemble those of alkali aluminosilicate glasses as is commonly assumed. Evidence is presented which suggests that the binary calcium aluminate glasses may be phase separated.     

Fractoemission from Lead Zirconate-Titanate

We present measurements of the electron, positive ion, and photon emission accompanying the fracture in vacuum of poly-crystalline 95/5 lead zirconate-titanate. The intensities of the charged-particle components of this fractoemission are shown to depend strongly on the direction (relative to the direction of fracture) and magnitude of polarization. The most intense emission is observed when the fracture surfaces are perpendicular to the polarization direction. The emission intensity increases monotonically with polarization. These results are interpreted in terms of a model involving charge separation on the fracture surfaces leading to a microdischarge during fracture. Implications to the interpretation of triboluminesence effects are discussed.     

Intrinsic Volume Changes of Self-propagating Synthesis

The final product(s) of self-propagating synthesis are shown to be intrinsically denser than the starting reactants. This behavior results in intrinsic decreases in the sample volume that increase with both the heat of reaction and the adiabatic combustion temperature. Forming of liquid product(s) during reaction simply adds another intrinsic source of porosity, i.e. changes in volume on product solidification. Thus, obtaining fully dense bodies from self-propagating synthesis requires a mechanism for reducing porosity, e.g. hot-pressing.     

The function of bleaching earths in the processing of palm,palm kernel and coconut oils

The results presented in the literature, which attempt to elucidate the mechanisms by which triglyceride oils are bleached by earths, are reviewed. The impact of this work and how the mechanistic proposals affect changes in oil properties are considered, with particular emphasis on the needs of the palm oil processor. Important properties include color, metals and phosphorus content and oxidative stability of the oil. Investigations made in our own laboratories have been aimed at elucidating the effect of varying physical and chemical properties of the bleaching earth on the quality of bleached and deodorized oils. Techniques used in this work are pore-size distribution, surface area, scanning and transmission electron microscopy and a variety of chemical and X-ray analysis methods. The ability to vary such parameters in montmorillonite clays by alteration of process conditions to give materials with specific performance characteristics is demonstrated. Comparisons are made between acid-activated montmorillonites and other clay types.     

Effect of water and other dielectrics on subcritical crack growth in portland cement paste

In studying the effect of water and a series of aliphatic alcohols on subcritical crack growth in cement paste, log crack velocity-stress intensity factor curves were obtained by means of a double-torsion technique. The relative position of the curves was found to be dependent on the dielectric constant of the test media. Flexural strength of cement paste saturated in organic fluids is also dependent on the dielectric constant. Stress corrosion processes involving chemical attack of Si---O bonds in cement paste appear to be operative.     

Perturbation techniques for detecting domain errors

Perturbation testing is an approach to software testing which focuses on faults within arithmetic expressions appearing throughout a program. This approach is expanded to permit analysis of individual test points rather than entire paths, and to concentrate on domain errors. Faults are modeled as perturbing functions drawn from a vector space of potential faults and added to the correct form of an arithmetic expression. Sensitivity measures are derived which limit the possible size of those faults that would go undetected after the execution of a given test set. These measures open up an interesting view of testing, in which attempts are made to reduce the volume of possible faults which, were they present in the program being tested, would have escaped detection on all tests performed so far. The combination of these measures with standard optimization techniques yields a novel test-data-generation method called arithmetic fault detection     

Optical networks for local loop applications

Some of the options for optical technology within the local loop environment are examined. In particular, passive shared access networks have been considered in some detail. These networks show great promise for delivering existing telephone services to small to medium business customers (4-30 lines) economically by the early 1990s. Extending fiber to the home will also be possible by virtue of a similar passive network infrastructure for customers requiring new broadband services beyond the single telephone line. For one-line plain old telephone service (POTS) customers, an intermediate approach of terminating the fiber network at the final network distribution point, with copper retained for the final leg, may be used prior to the provision of broadband services. A key feature of the passive optical network architecture is the use of wavelength-division multiplexing (WDM) as an upgrade strategy, allowing graceful upgrading from telephone services to multichannel high-definition television (HDTV) on gigabit/second bearers and full two-way switched broadband services employing wavelength routing across the network     

Long-term transients in a reactor under forced concentration cycling

In the approach to a cycle-invariant state in the forced feed concentration cycling of the CO oxidation over a NiO catalyst, a very long transient has been observed lasting 80 ks or more. This transient appears to be associated only with CO pretreatment of the catalyst and is not a general phenomenon. The slow convergence to the cycle-invariant state reported in certain modelling calculations in the literature appears to have a different cause.     

Comparing word fragment completion and cued recall with letter cues.

Cued recall with word stems as cues and fragment completion rely on different types of letter cues and also differ in the explicit–implicit nature of the retrieval orientation. Despite these differences, variables effective in one task may be effective in the other because both rely on letter cues. Two variables known to affect cued recall were manipulated: Lexical set size (number of words that fit the letter cue) and meaning set size (number of associates generated to the studied words). Across four experiments, subjects in each task were less likely to recover targets from larger lexical sets. However, meaning set size affected cued recall but not fragment completion. These results indicate that fragment completion and letter-cued recall are based on lexical search but that cued recall also involves a semantic search component. Furthermore, type of retrieval cue had a greater effect than type of retrieval orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)