Statistical Analysis of Effects of Nanoparticles on Hydrocarbon Pool Fire

The effects of pool diameters, height, fuel type, and presence of nanoparticles on flame temperature are tested. Nanoparticles were added and mixed with the fuel and its effect on flame spread time over the liquid fuel surface is studied. The results showed that pool diameter has the maximum effect on the increase of flame temperature. Nanoparticles reduce the flame temperature from 10 to 20% while flame spread time is increased 15% to 30% for kerosene and 6% to 26% for diesel oil. Experimental measurement of flame temperature distribution in a pool fire is carried out. Statistical analysis of flame temperature, flame spread time was made using Yates and ANOVA methods.     

Investigation of the Effect of Tungsten Substitution on Microstructure and Abrasive Wear Performance of In Situ VC-Reinforced High-Manganese Austenitic Steel Matrix Composite

Particulate VC-reinforced high-manganese austenitic steel matrix composites with different vanadium and tungsten contents were synthesized by conventional alloying and casting route. Microstructural characterizations showed that the composites processed by in situ precipitation of the reinforcements were composed of V₈C₇ particulates distributed in an austenitic matrix. It was observed that addition of tungsten to austenite increases work-hardening rate of subsurface layer during pin-on disk wear test. The maximum abrasive wear resistance was achieved at tungsten content equal to 2 wt pct. However, excessive addition of tungsten promoted the formation of W₃C phase and reduced the abrasive wear resistance because of decrease in distribution homogeneity and volume fraction of the reinforcing VC particles.     

Determination of Capacity Benefit Margin in Multiarea Power Systems Using Particle Swarm Optimization

Available transfer capability (ATC) is a key index of the remaining capability of a transmission system for future transactions. To calculate the ATC between two areas in an interconnected power system, capacity benefit margin (CBM) is one of the indexes that need to be assessed. CBM ensures security of system operation when the system faces generation deficiency in some areas. In this paper, three new methods are introduced which reflect different objectives for CBM assessment. This provides more flexibility of choices for market participants. In the proposed methods, CBM determination is formulated as an optimization problem and particle swarm optimization (PSO) method is used to solve the problem. The numerical results for modified IEEE reliability test system are presented to demonstrate the effectiveness of the proposed approaches.     

Enhanced selectivity of hydrolytic precipitation of Zn from Zn-Ni sulfate solution via chelation of Ni

The selective precipitation of zinc from zinc–nickel sulfate solution with the Zn/Ni molar ratio of 20:1 was studied. Dropwise addition of 0.5 mol/L NaOH solution into the zinc–nickel sulfate solution containing 0, 0.01, 0.02, 0.03 and 0.04 mol/L ethylene diamine tetraacetate (EDTA) as a chelating agent was done. The equilibrium analysis of precipitation pathway was performed using Visual MINTEQ program. The equilibrium analysis showed that the presence of small amounts of EDTA can prevent nickel precipitation in alkaline conditions without any negative effect on zinc precipitation. On this basis, more than 90% of zinc could be precipitated as a product with about 50% Zn and only 0.11% Ni at pH=9.0 merely as a result of the presence of 0.03 mol/L EDTA in the solution. The stirring time of 120 min after precipitation was found to be essential for more complete separation. The X-ray diffraction studies on the precipitate revealed that the precipitated phase was Zn₄(OH)₆SO₄.4H₂O.     

The Influence of Morphology on Photo-catalytic Activity and Optical Properties of Nanocrystalline ZnO Powder

Nano-Micro Letters - ZnO nano-particles were synthesized via an ammonical ammonium carbonate solution by precipitation method in presence of some additives such as urea, oleic and stearic acid. The...     

Optimum seismic design of concentrically braced steel frames: concepts and design procedures

A methodology is presented for optimization of the dynamic response of concentrically braced steel frames subjected to seismic excitation, based on the concept of uniform distribution of deformation. In order to obtain the optimum distribution of structural properties, an iterative optimization procedure has been adopted. In this approach, the structural properties are modified so that inefficient material is gradually shifted from strong to weak areas of a structure. This process is continued until a state of uniform deformation is achieved. It is shown that the seismic performance of such a structure is optimal, and behaves generally better than those designed by conventional methods. In order to avoid onerous analysis of the frame models, an equivalent procedure is introduced for performing the optimization procedure on the modified reduced shear-building model of the frames, which is shown to be accurate enough for design purposes.