Thermochemical Investigations in the System Cadmium-Praseodymium Relevant for Pyrometallurgical Fuel Reprocessing

Vapor pressure measurements, in terms of a (non-)isothermal isopiestic method, were carried out in the system Cd-Pr between 749 K and 1067 K (476 °C and 794 °C). Thermodynamic activities of cadmium as a function of temperature were obtained directly for the composition ranging from 50.0 to 85.7 at. pct Cd. From these results, partial molar enthalpies of mixing of Cd were derived for the corresponding composition range. The activity values of Cd were converted to an average sample temperature of 823 K (550 °C) by applying an integrated form of the Gibbs–Helmholtz equation. These data indicate that Cd₂Pr and Cd₅₈Pr₁₃ are probably the most stable intermetallic compounds in this system. Using an activity value of Pr from the literature as integration constant, Gibbs–Duhem integration was performed, and integral Gibbs energies are presented at 823 K (550 °C), referred to Cd(l) and α-Pr(s). Gibbs energies of formation at the stoichiometric compositions of the phases Cd₆Pr, Cd₅₈Pr₁₃, Cd₄₅Pr₁₁, Cd₃Pr, and Cd₂Pr were determined to be about ?18.8, ?23.5, ?24.8, ?28.7, and ?33.8 kJ g-atom^?1 at 823 K (550 °C), respectively.     

Unidirectional bubble growth in microchannels with asymmetric surface features

The growth of vapor bubbles is studied numerically in a microchannel with asymmetric surface features. The channel design is chosen such that evaporation results in vapor bubbles growing only along a predefined direction. The principle relies on capillary forces and the pinning/depinning of three-phase contact lines at sharp edges of the wall geometry. Analytical expressions are derived predicting the direction of bubble growth and allowing to assess the robustness of a specific channel geometry in terms of supporting unidirectional bubble growth. From these expressions design rules for microchannels incorporating geometrical parameters and the wall contact angle of the liquid phase can be derived. The numerical calculations are performed based on an extended Volume-of-Fluid method accounting for phase change. The results confirm that under specific conditions, vapor bubbles only expand in one direction, thereby corroborating the analytical model. The presented concept may find applications in designing microchannels for stabilized flow boiling or micropumps/-actuators relying on phase change.     

Controlled Creating of Cracks in Concrete for Non-destructive Testing

The non-destructive assessment of cracks in concrete is a common task for which non-destructive evaluation solutions have been published. Primarily, these tests have been carried out on artificial cracks that have been created by using notches instead of natural cracks. This study evaluates a procedure designed to create reproducible and controlled cracks in concrete. The procedure is based on using expanding mortar in a series of blind holes. This is done in combination with carefully aligned reinforcement to guide the direction of the crack development. The depth of the crack is also controlled by reinforcement. Crack depth varies statistically in the range of the maximum aggregate size (16 mm) used for concrete.     

Weathering the storm: disaster risk and vulnerability assessment of informal settlements in Mwanza city,Tanzania

This study employs participatory disaster risk and vulnerability assessment to analyse vulnerability to disasters in informal settlements in Mwanza city, Tanzania. The results show that a plethora of factors – human, physical, social, economic and natural – interact in complex non-linear ways to shape vulnerability to disaster in informal settlements in Mwanza city. The study shows that coping strategies of some individuals in informal settlements reinforce their risks to disaster. For example, the stones that are positioned on weak roof structures for protection may become projectiles in the event of storm: a kind of disaster by design. This quick-fix coping strategy is unlikely to be sustainable.     

Comments on “School Integration Policies in Northern Cities”

This study develops a research method of assessing people's satisfaction with housing. Instead of the old approaches which consider in fragmented ways the characteristics of the dwelling, or the neighborhood, or the social environment, the author proposes a systems approach in which various interdependent factors are studied in relation to one another. Using the techniques developed, the relative satisfaction of tenants in public housing projects in certain areas of Canada is identified, analyzed, and discussed.     

A Knowledge Transfer Framework: the PFI context

The UK's Private Finance Initiative market is predicted to rise to over £8 billion a year and there are indications of growing opportunities. PFI creates a long‐term income stream and provides valuable opportunities for portfolio diversification. PFI has evolved at a fast pace and the momentum is set to continue. However, there are major challenges facing construction organisations. These include the lack of PFI experts, longer negotiation periods and tight time schedules to deliver large‐scale schemes, high levels of investment and risks involved and limited knowledge transfer between PFI projects. Concerns over the level of knowledge sharing have prompted the development and evaluation of a Knowledge Transfer Framework that encourages construction organisations to transfer PFI knowledge between projects. It achieves this by building on a questionnaire survey of PFI clients and construction companies, case studies of companies involved in PFI, and research workshops to validate the framework developed.