Structures revealed in zone refined aluminum by tritium decoration

A method is described for decorating structures in solid aluminum by precipitation of hydrogen onto them. Radioactive hydrogen is employed so that the deposition sites can be revealed by the use of autoradiographic techniques. The study was conducted with zone refined aluminum, and the primary structure that was revealed was that remaining after directional solidification during the last zone pass. The tritium was added to the specimen at 600°C and its precipitation was brought about by quenching the sample. As little as 0.05 ppm of tritium was sufficient to reveal complex structures in the cast metal that are attributed to association of unidentified residual impurity atoms with low angle subgrain boundaries that are thought to have resulted from polygonization occurring immediately behind the advancing solid-liquid interface. Wide-angle grain boundaries were also decorated. New structures were introduced by various levels of strain that accompanied different upsetting operations. Grain and subgrain boundaries that developed during strain anneals were “antisites” for hydrogen deposition. This opposite behavior is attributed to the absence of impurity atoms in these “new” boundaries. An explanation for the behavior of hydrogen in aluminum is given in terms of the condensation of vacancies vs their loss to vacancy sinks. These phenomena are shown to be involved in the enlargement of hydrogen-filled pores in aluminum.     

Analysis of a new type of high pressure homogeniser. Part B. study of droplet break-up and recoalescence phenomena

Calculation of the flow pattern in a new small homogenising valve design (Stansted, U.K.), able to reach operating pressure as high as , was investigated in the first part of this paper using a Computational Fluid Dynamics method. Numerical simulation results are used in the present paper to better understand the emulsification process in the Stansted high-pressure homogeniser.Deformation of drops is supposed to occur in the intense elongational flow caused by the restriction between the piston and the seat of the valve. Deformation may be mainly followed by drop disruption in the narrow valve gap. Break-up probably also occurred in the highly turbulent region, located just at the exit of the gap, and underlined by the numerical investigation. Cavitation and the rate of recoalescence, first assumed from numerical results, are determined thank to experimental methods. Intensities of both phenomena strongly increase with homogenising pressure. Final droplet size of model oil-in-water emulsions is then the result of equilibrium between droplet break-up and recoalescence, which strongly depends on operating pressure.     

The equivalence of measures and the correction for attenuation.

In literature reviews and critiques, measures are often evaluated in regard to their conceptual equivalence. In making this evaluation, the empirical correlation between the 2 measures being compared should be corrected for attenuation at least approximately. Unless this correction is applied, alternative measures may be presumed to be importantly different when giving due weight to the unreliabilities present, it may be seen that the identical underlying dimension is being reflected. In psychology, where enough discrepancies already characterize our findings, this interpretive error should not deny us the occasional equivalences that come along. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Locating emergency medical rescue vehicles under conditions of urgency

This article describes how a fire department's information system was utilized to solve a pressing emergency medical rescue vehicle location problem. The existing information system was augmented by a manual data system to provide the needed information in a very short time. The result of the problem analysis further provided feedback regarding the deficiencies of the information system for emergency medical rescue purposes.     

Leaching of vanadium and other metals from Athabasca Oil Sands coke and coke ash

Flexicoker coke derived from Athabasca Oil Sands bitumen contains a number of heavy metals, including vanadium, nickel, iron and titanium, which are susceptible to extraction by hydrometallurgical procedures. The leaching behaviour has been studied as a function of pH, temperature and the presence of salts and redox agents. Greater than 50% extraction of the vanadium, iron and nickel can be achieved by acid leaches, but only about 20% of the titanium can be extracted. Weakly acidic leaches extract about 30% of the nickel content but no significant amounts of the other metals. If cokes derived from Athabasca Oil Sands bitumen by the flexicoking process or the conventional delayed-coker coking process are combusted at temperatures below 500 °C, the vanadium and nickel values in the residual ash are readily susceptible to acid leaching.