The formation and breakup of molten oxide jets under periodic excitation

The experiments on the capillary breakup of slag jets at high temperatures are presented in this article. The impact of external excitations on the disintegration process was investigated in a furnace with optical access filmed at frame rates up to 10,000 fps. A synthetic calcia‐alumina slag was used to form jets at different temperatures (1570–1660°C) and jet velocities (0.6–1.4 ms^?1). The impact of external vibration on the breakup was evident: for low jet velocities, the jet length decreased, the droplet size increased, satellite droplet formation was hindered, and a distinct “pumping mechanism” was observed. For jets with higher velocity, the jet length decreased by 30%, the droplet generation frequency increased from 20 to 250 droplets per second, the drop sizes were uniform, and satellite formation was also suppressed. In this case, the ideal case in which the volume of one wave instability forms one droplet was achieved. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3350–3361, 2014     

Flood boundary delineation from Synthetic Aperture Radar imagery using a statistical active contour model

Flood extent maps derived from remotely sensed data can provide distributed validation data for hydraulic models of fluvial flow, and can be used for flood relief management and to develop spatially accurate hazard maps. A statistical active contour model is used to delineate a flood from the first European Remote Sensing satellite Synthetic Aperture Radar (ERS-1 SAR) imagery as a region of homogeneous speckle statistics. The segmentation uses both local tone and texture measures and is capable of accurate feature boundary representation. The results are assessed by comparison with simultaneous aerial photography, the SAR segmentation scheme classifying 75% by area of the shoreline region correctly. Seventy per cent of the shoreline coincides with the ground data to within 20 m. The main error is due to unflooded vegetation giving similar radar returns to open water.     

An effect of chemisorbing surface reaction poisons on the transition from internal to external oxidation

We consider the effect of a chemisorbing surface reaction poison on the transition from internal to external oxidation for a model binary alloy subject to selective oxidation. We solve the diffusion equations for internal oxidation, using the rate of a surface reaction as a boundary condition. The gas-phase concentration of a strongly chemisorbing poison appears in the analysis through its retarding effect on that surface reaction. It is shown that the slow surface reaction can promote the formation of a protective oxide scale by slowing down the initial uptake of oxygen and allowing metal atoms with the highest oxygen affinity sufficient time to diffuse to the surface. As a result, a larger volume fraction of oxide forms near to the surface (with that volume fraction initially inversely proportional to the rate of the surface reaction), and the critical volume fraction required for the transition to an external scale is more easily exceeded. Formerly with Exxon Research and Engineering Company     

Efficient Bifunctional Catalytic Electrodes with Uniformly Distributed NiN2 Active Sites and Channels for Long‐Lasting Rechargeable Zinc–Air Batteries

Freestanding bifunctional electrodes with outstanding oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) properties are of great significance for zinc–air batteries, attributed to the avoided use of organic binder and strong adhesion with substrates. Herein, a strategy is developed to fabricate freestanding bifunctional electrodes from the predeposited nickel nanoparticles (Ni‐NCNT) on carbon fiber paper. The steric effect of monodispersed SiO₂ nanospheres limits the configuration of carbon atoms forming 3D interconnected nanotubes with uniformly distributed NiN₂ active sites. The bifunctional electrodes (Ni‐NCNT) demonstrate ideal ORR and OER properties. The zinc–air batteries assembled with Ni‐NCNT directly exhibit extremely outstanding long term stability (2250 cycles with 10 mA cm^?2 charge/discharge current density) along with high power density of 120 mV cm^?2 and specific capacity of 834.1 mA h g^?1. This work provides a new view to optimize the distribution of active sites and the electrode structure.     

Density Measurements of Low Silica CaO-SiO<Subscript>2</Subscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Slags

Density measurements of a low-silica CaO-SiO₂-Al₂O₃ system were carried out using the Archimedes principle. A Pt 30 pct Rh bob and wire arrangement was used for this purpose. The results obtained were in good agreement with those obtained from the model developed in the current group as well as with other results reported earlier. The density for the CaO-SiO₂ and the CaO-Al₂O₃ binary slag systems also was estimated from the ternary values. The extrapolation of density values for high-silica systems also showed good agreement with previous works. An estimation for the density value of CaO was made from the current experimental data. The density decrease at high temperatures was interpreted based on the silicate structure. As the mole percent of SiO₂ was below the 33 pct required for the orthosilicate composition, discrete \textSiO₄^{4 -} {\text{SiO}}_{4}^{4 - } tetrahedral units in the silicate melt would exist along with O^2– ions. The change in melt expansivity may be attributed to the ionic expansions in the order of

Some Investigations into the Dynamic Mass Transfer at the Slag–Metal Interface Using Sulfur: Concept of Interfacial Velocity

In the current work, dynamic studies of mass transfer of sulfur from the gas phase to the metal phase of pure iron through CaO-SiO₂-Al₂O₃-FeO quaternary slag were carried out. X-ray videos were taken that were later processed to identify the oscillation of the metal drop occurring during the mass transfer. It was observed that the metal drop had hybrid oscillations. Each of these oscillations could be identified as composed of a symmetric and an asymmetric element, which was attributed to the changes in the shape of the droplet. The latter (asymmetric part) could be identified by the deviation of the left and right contact angles from the stable configuration. The symmetric oscillations were traced to the surface movement of sulfur at the interface, which created an instantaneous area change at the slag–metal interface. This area change was due to the combined effect of Marangoni flow and interface dilatation. The velocity of sulfur at the interface was calculated from the area change and had a maximum order of magnitude as 10⁻⁴ m/s. It was also observed that the interfacial velocity increased with increase in temperature.     

An Assessment of the Benefits Afforded by the Continuous Versus Intermittent Operation of Ozone for Drinking Water Treatment

Stricter regulation by OFWAT has encouraged water companies to optimize all stages of the water treatment process. This work reviews the ozonation process, in order to evaluate the benefits and disadvantages of continuous versus intermittent ozone operation. Two Advanced Water Treatment Works (AWTW) were surveyed, Farmoor AWTW, Which involves traditional (chemical) treatment processes, and Kempton Park AWTW, which incorporates slow sand filter sandwich? beds. Both reviews indicated that continuous ozone operation would result in an optimized solution based on dependability of ozone plant, reliability of water quality and cost efficiency.     

Sulfur Transfer at Slag/Metal Interface—Impact of Oxygen Potential

In the present work, the interfacial movement resulting from sulfur mass transfer at the slag/metal interface was monitored by X-ray sessile drop method in dynamic mode at temperature 1873 K (1600 °C) under nonequilibrium conditions. The experiments were carried out with pure iron and CaO-SiO₂-Al₂O₃-FeO slag (alumina saturated at the experimental temperature) contained in alumina crucibles with well-controlled partial pressures of oxygen and sulfur. The impact of oxygen potential on the droplet oscillation as sulfur from the gas phase reaches the metal drop through the intermediate slag phase was monitored. The interfacial velocity was investigated. It was found that the increases of interfacial velocity and the maximum oscillation time were mainly attributed to the partial pressure of oxygen increases. The experiment results were explained by previous ab initio calculations. The thermo-physical and thermo-chemical properties of slag were also found to influence interfacial velocity.     

Classification of forest volume resources using ERS tandem coherence and JERS backscatter data

Considering recent progress in the development of techniques and methods to achieve biomass estimates and full carbon accounting, remote sensing research of forested ecosystems needs to be aimed towards the retrieval of information at global scales. In this paper, an algorithm for the estimation of growing stock volume, an important parameter for the commercial forest community and a proxy for woody biomass density, from ERS and JERS synthetic aperture radar (SAR) data is described. The algorithm is based on the information content of both ERS tandem coherence and JERS backscatter images and was developed using ground data, made available by the Russian Forestry Services. It is tested on SAR datasets of boreal forests in Siberia, a managed, temperate forest plantation in the United Kingdom and a semi-natural boreal forest at Siggefora in Sweden. Comparisons of the classified products, comprising three growing stock interval classes and one non-forest class are made with ground data. The results of this accuracy assessment exercise show that the algorithm yields, in all cases, overall classification accuracies of greater than 70%. A visual comparison is made of the algorithm performance over a tropical forest region of Brazil. The results indicate that the algorithm has the potential to retrieve growing stock volume estimates in forest ecosystems throughout the globe.