Hydrothermal synthesis of lead titanate and lead zirconate titanate electroceramic particles

Hydrothermal synthesis of two lead-based perovskite powder systems, lead titanate and lead zirconate titanate, was investigated. Phase-pure perovskite lead titanate and lead zirconate titanate with various morphologies have been synthesized by hydrothermal methods at 150° and 175°C, respectively. Solution pH should be greater than 14 to obtain the phase-pure perovskite phases in a reasonable time. In addition, the KOH concentration and the stirring rate significantly influence particle morphology of the hydrothermally derived PT and PZT. Therefore, these parameters can be used to tailor particle size and morphology.     

Enhancement of the efficiency of countercurrent near-critical fluid extraction by pressure pulsation

The effect of pressure pulsation on the separation of a mixture of glycerides of oleic acid by means of near-critical fluid extraction was investigated. A mixture of carbon dioxide and propane was used as the supercritical extracting agent. The efficiency of a Sulzer wire mesh packing type CY was enhanced by a factor of about three using a pressure amplitude of 14 bar and a pulsation frequency of 32 strokes/min. The influence of the pulsation frequency on the column efficiency is more pronounced than that of the pulsation amplitude.     

Effect of crude oil type and heating rate on combustion of crude oil-lignite mixtures

Research was conducted to investigate the possibility of upgrading low-quality lignites by mixing them with heavy crude oils. Three crude oil samples with API gravities of 12.9, 18.7 and 26.7 were mixed with lignite to form mixtures of 10 and 20% oil content. Thermal analysis experiments were conducted at non-isothermal heating conditions at heating rates of 5–100 K min⁻¹. Differential thermogravimetric data were analysed using an Arrhenius-type reaction model assuming a first-order reaction. The results indicate that the combustion of mixtures as observed on thermograms is very similar to that of lignite. However, the activation energy and reaction peak temperatures increased as the oil content in the mixture increased.     

Dominant Factor in the Collapse of WTC-1

The behavior of the World Trade Center Tower 1 on September 11, 2001 is studied in light of experimental data on the effect of elevated temperature on mechanical properties of structural steel. It is concluded that the damage inflicted by aircraft impact on the insulation of the core framing was the dominant factor in the collapse of the structure.     

Co-liquefaction of Yatağan lignite and waste tire under catalytic conditions. Part 1. Effect of fresh tetraline and recycled tetraline on the conversion

In this study, the effect of solvent type and the solvent/solid ratio on the liquefaction of Mu?la-Yatagan lignite (YL) combined with waste tire (WT) under catalytic conditions investigated. Liquefaction experiments carried out the following conditions, a reaction temperature of 400°C, a catalyst concentration of 3%, solvent/solid ratio from 1/1 to 9/1, reaction time of 90 min, lignite/waste ratio of 1/1. In addition, mixing speed was 400 rpm, and the nitrogen gas pressure fixed at 30 bar. After the each of liquefaction experiments finished, the soluble products (SP) classified as preasphaltene (PAS), asphaltene (AS) and oil+gas (OG), by solvent extraction. Due to the optimum total conversion determined, fresh tetraline obtained as the most favorable solvent with 71.71%, for the liquefaction of YL with WT. However, the total conversion for recycling tetraline is 68.6%. According to the results, co-liquefaction of YL combined with WT using recycle solvent is the one way to offer, alternatively of using crude oil, producing SP for not crude oil, producing SP for not only fuel-oil production but also prefer chemical raw materials. With respect to the optimum oil+gas yield results, the most convenient solvent type and the solvent/solid ratio are the recycled solvent and its 3/1 ratio.     

Corrosion resistance characteristics of stamped and hydroformed proton exchange membrane fuel cell metallic bipolar plates

Metallic bipolar plates have several advantages over bipolar plates made from graphite and composites due to their high conductivity, low material and production costs. Moreover, thin bipolar plates are possible with metallic alloys, and hence low fuel cell stack volume and mass are. Among existing fabrication methods for metallic bipolar plates, stamping and hydroforming are seen as prominent approaches for mass production scales. In this study, the effects of important process parameters of these manufacturing processes on the corrosion resistance of metallic bipolar plates made of SS304 were investigated. Specifically, the effects of punch speed, pressure rate, stamping force and hydroforming pressure were studied as they were considered to inevitably affect the bipolar plate micro-channel dimensions, surface topography, and hence the corrosion resistance. Corrosion resistance under real fuel cell conditions was examined using both potentiodynamic and potentiostatic experiments. The majority of the results exhibited a reduction in the corrosion resistance for both stamped and hydroformed plates when compared with non-deformed blank plates of SS304. In addition, it was observed that there exist an optimal process window for punch speed in stamping and the pressure rate in hydroforming to achieve improved corrosion resistance at a faster production rate.     

Laminar forced convection slip-flow in a micro-annulus between two concentric cylinders

Forced convection heat transfer in hydrodynamically and thermally fully developed flows of viscous dissipating gases in annular microducts between two concentric micro cylinders is analyzed analytically. The viscous dissipation effect, the velocity slip and the temperature jump at the wall are taken into consideration. Two different cases of the thermal boundary conditions are considered: uniform heat flux at the outer wall and adiabatic inner wall (Case A) and uniform heat flux at the inner wall and adiabatic outer wall (Case B). Solutions for the velocity and temperature distributions and the Nusselt number are obtained for different values of the aspect ratio, the Knudsen number and the Brinkman number. The analytical results obtained are compared with those available in the literature and an excellent agreement is observed.     

Effects of dietary olive and linseed oil on lipid composition, meat quality, sensory characteristics and muscle structure in pigs

The aim of this study was to alter the fatty acid composition of porcine tissue by accumulating essential fatty acids without adversely affecting carcass composition, muscle structure or meat eating quality. A total of 13 female and 12 castrated Pietrain×German Landrace pigs were fed a basal concentrate diet supplemented with 5% olive oil or 5% linseed oil during the growing-finishing period. Carcass composition and meat quality were not affected by the diet. Feeding linseed oil to pigs significantly increased the relative content of linolenic acid and long chain n-3 fatty acids in lipids of muscle, backfat and heart at the expense of arachidonic acid. Oleic acid was accumulated in muscle, backfat and heart lipids by feeding olive oil. The overall flavour of combined meat/backfat samples from castrates was negatively influenced by linseed oil supplementation compared to supplementation with olive oil. The oxidative stability of muscle lipids was lower in linseed oil-fed pigs compared to olive oil fed pigs. The greater cross section areas of the longissimus muscle of females were caused by an increased diameter of red, intermediate and white fibres.     

Path enumeration and hot-potato routeing analysis in multihop networks

Using a labelling of the edges of the network graph for a multihop network and a Taylor series expansion of the transfer function of the resulting signal flow graph, we calculate the number of paths of a given length in the multihop network. The derivative of the transfer function and a fixed point algorithm yield the average delay as a function of the packet arrival rate.