Recovery of metals and other beneficial products from coal fly ash: a sustainable approach for fly ash management

International Journal of Coal Science & Technology - Increasing production and disposal of coal fly ash (CFA) is a matter of serious environment concern. However, CFA contains various...     

Physical Effects of Variable Thermophysical Fluid Properties on Flow and Thermal Development in Micro-Channel

Micro-scale cooling is an efficient and effective cooling technique to achieve the goal of higher heat removal capabilities. The present research focuses to find the physical effects of fluid property variations on flow and thermal development in micro-channel. The effects of temperature-dependent density, viscosity, and thermal conductivity variations on single-phase laminar forced convection are numerically investigated. The problem is especially simulated for hydrodynamically and thermally developing water flow in micro-channel with no-slip, no-temperature jump, and constant wall heat flux boundary conditions. It is observed that the density variation induces radially inward flow due to continuity, which sharpens the axial velocity profile and decreases Nusselt number compared to constant property solution. The axial velocity profile significantly alters due to viscosity variation. This alteration varies along the micro-flow and it induces radially flow due to flow continuity. The reducing rate of Nusselt number for viscosity variation is substantially lower than constant property solution due to a significant flattening effect of the axial velocity profile, which augments the Nusselt number. Thermal-conductivity variation across the flow induces radial conduction, which enhances convection compared to constant property solution. Additionally, the effects of thermophysical fluid property variations on static gauge pressure drop are also investigated.     

In vitro ageing and wear behaviour of ceria stabilized zirconia toughened alumina (CSZ-TA) bio-ceramic

15–25 wt% zirconia (stabilized with 14 mol% ceria) toughened alumina was synthesized by co-precipitation technique. The synthesized powders were calcined at different temperatures, compacted and conventionally sintered following two steps sintering process. Uniformly distributed submicron sized grains with Vickers' hardness value up to 1730±6HV20 were achieved after conventional sintering. In order to assess the ageing behaviour, samples were hydrothermally treated (in vitro) at 134 °C under 0.2 MPa in presence of simulated body fluid. Rietveld refinement of the X-ray diffraction patterns was carried out to estimate the phase content after calcination, sintering and after different stages of hydrothermal treatment. No significant phase change (only ∼3%) was observed even after 100 h of hydrothermal treatment. Very few bulged grains (resulted from the tetragonal to monoclinic phase transformation) on the surface and slight decrease in hardness value were observed after hydrothermal treatment. Fretting wear in dry condition was carried out taking ball on flat geometry for 10⁵ cycles at different loads before and after hydrothermal treatment. Wear volumes were directly estimated from the surface scanning of the wear scar using profilometer. Transition of wear and its related mechanisms at different loads along with the effect of ageing on wear were discussed.     

Design and optimization of thermo-electrochemical cells

Thermo-electrochemical cells (or thermocells) convert thermal energy to electricity in continuous operation based on a balance of ion conduction and redox reactions at hot and cold electrodes. In this study, the fundamental governing equations for mass and heat transfer, fluid dynamics, and electrokinetics in thermocells are presented and solved numerically using COMSOL. A parametric study is performed to explore the limitations and optimal cell dimensions for maximum energy conversion efficiency in thermocells. Series-stacking designs are demonstrated to have the potential to increase conversion efficiency by 100 % compared to a single cell configuration. Natural convection is shown to significantly increase the conversion efficiency of thermocells with conventional aqueous electrolyte (0.4 M potassium ferri/ferrocyanide), by compressing the diffusive boundary layers. A flow cell thermocell design is also considered. Results reveal that the ohmic resistance of the electrolyte limits the energy conversion efficiency of this design.     

Efficient fog removal from video

In this paper, a framework of real-time video processing for fog removal using uncalibrated single camera system is proposed. Intelligent use of temporal redundancy present in video frames paves the way for real-time implementation. Any fog removal algorithm for images acquired with uncalibrated single camera system can be extended to video using the proposed framework. For the purpose of real-time implementation, several fog removal algorithms for images are investigated and few top ranking algorithms in speed and quality are chosen. Simulation results confirm that proposed framework reduces the computation per frame significantly. Proposed fog removal framework has a wide application in navigation, transportation, and other industries.     

INDEX: An INDustrial Building Design EXpert

This paper presents an account of a research project concerned with the application of artificial intelligence techniques to structural design in civil engineering. INDEX is a rule-based system for the design of industrial buildings that is being developed at the University of Edinburgh. It has a blackboard architecture and its knowledge base is organized into a hierarchy of two levels. The main focus of this paper is to summarize the implementation aspects of one of its knowledge modules, ALTSEL which is responsible for the preliminary design. The organization of knowledge inside the ALTSEL module is briefly outlined using a number of representative rules from its sub-modules. The use of the Edinburgh PROLOG Blackboard Shell in the development of INDEX is also described briefly.