Thermodynamic properties of the NdBr3–MBr binary systems (M = Na,K)

Thixoforming involves heating different types of alloys to the semisolid state at high heating rates and forming in die-casting machines or conventional presses. At temperatures higher than the solidus and lower than the liquidus, the mush metal behaves like a high-viscosity thixotropic material. Therefore, determining the thermodynamic behavior of the solid-to-liquid transition is paramount to control thixoforming processes. This article describes a simple, novel experimental setup based on differential thermal analysis (DTA) for analyzing the phase transitions in an alloy heated using high heating rates typical of industrial applications. A365 alloy was chosen to demonstrate the effectiveness of the method as the phase transformations for this alloy in semisolid materials (SSM) processing are well understood. Samples were heated to 750 °C using constant linear heating rates of 5, 10, 15, 20, 25, 50, 75, 100 and 125 °C min in a Norax 25 kW 8 kHz induction furnace with an Omron E5CK temperature controller. AISI 316 austenitic stainless steel was used as the inert reference. Comparison of the results of DTA using the proposed method and the results of simulation with Thermo-Calc^® indicates that the proposed in situ DTA device and its method is suitable for analyzing phase transitions when high heating rates are used.     

A soft multi-criteria decision analysis model with application to the European Union enlargement

This paper proposes a new multi-criteria decision analysis (MCDA) model that uses a series of existing intuitive and analytical methods to systematically capture both objective and subjective beliefs and preferences from a group of decision makers (DMs). A defuzzification method that combines entropy and the theory of displaced ideal synthesizes crisp values from the DMs’ subjective judgments. This approach assists the DMs in their selection process by plotting alternatives in a four quadrant graph and considering their Euclidean distance from the “ideal” choice. A pilot study illustrates the details of the proposed method. The DMs were a group of graduate students from the University of Paderborn in Germany. The pilot study concerned the addition of new members into the European Union (EU), a decision that has profound economic and political effects on both the entering and existing members of the Union. The DMs were required to consider a large number of internal strengths and weaknesses and external opportunities and threats in assessing the decision to enlarge the EU. Although the pilot study was not performed by actual DMs from the EU, it was an excellent platform for testing the proposed model.     

The emission of electrons from hot silicon surfaces

The emission of electrons from hot silicon surfaces is reviewed in an effort to present a summary of the state of research in this field. The theoretical aspect of the problem is outlined briefly, and experimental results covering the temperature and field dependence of the saturation current density, as well as the anisotropy and the energy distribution of the emission are presented.     

Polyamine-substituted epoxy-grafted silica for aqueous metal recovery

Glycidoxypropyltriethoxysilane (GPS) was used as a reactive silane to graft metal- complexing ligands onto silica gel in aqueous media under mild conditions. The synthesis entailed the reaction of GPS with silica gel, followed by grafting polyamine onto the epoxy functional group. GPS was added to silica gel in ethanol with 5 vol. % water and the mixture was air-dried for 24 h. Subsequently, excess amounts of polyamines: triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine were individually added to the silanised silica, followed by solvent evaporation and ovendrying at 60°C. The ligand-grafted silica gel particles showed a rapid heavy metal uptake in batch or flow-through experiments with capacities reaching 0.1 mmol g⁻¹ for copper, zinc, cadmium, or lead ions. Columns packed with the modified particles could be readily regenerated by acid-washing with only a small decrease in activity. The particles could be used for the colourimetric detection of heavy metal pollution or for pre-concentration for analytical purposes. Competition between Cu²⁺, Zn²⁺, Pb²⁺, and Cd²⁺ ions for the three synthesised silica showed that Cu²⁺ ions were adsorbed more strongly than the other metal ions. The general method developed can be applied to graft other molecules with terminal amino groups for other purposes.     

Primary Break‐up of a Viscous Liquid Jet in a Cross Airflow

This article presents an experimental study of the primary break‐up of a viscous liquid jet interacting with a cross airflow. This experiment was carried out in an open circuit wind tunnel. The measurement test section was made of clear acrylic resin to allow optical access for visualizing and imaging the jet break‐up in the cross airflow. The working liquid used in the present experiment was the aero‐engine lubrication oil, which was injected at 90° into the airflow, via a nozzle from the top wall of the test‐section. The effects of liquid viscosity, and the jet and cross airflow velocities on the primary break‐up mechanisms of the jet were studied. The main results showed that different break‐up regimes were identified; column break‐up and bag break‐up separated by a transition zone, and new correlations have been proposed for predicting the jet transverse and streamwise penetrations before break‐up.     

Bayesian filtering of speckled images

Speckle noise arises in imaging systems that use coherent or partially coherent illumination. We demonstrate that such noise may be reduced by use of bayesian filters. The usual assumption that speckle noise is approximately equivalent to multiplicative image noise is replaced with an exact analysis.