Rolling of cast Al‐SiCp particulate metal matrix composites and strip mechanical properties

Thermomechanical physical simulation is applied to get the optimum hot rolling parameters of aluminium silicon carbide composites. Wrought Al 6061 and 6082 – Silicon carbide particulate (SiCp) metal matrix composite strips are prepared by stir‐casting followed by sequential rolling assisted with intermediate heat treatment to allow crystallization recovery and further processing. SiCp are used in two microgrit grades; namely F500 and F800. The reinforcing particulates are used after surface oxidation and 0.3% Mg is added during melting and stirring for loss substitution. With the pre‐treatments applied, SiCp are successfully inserted in the Al matrix, better wetting between particles and matrix, better particles distribution, less agglomeration and minimized reactions between SiC particles. Thermo‐mechanical simulation as a tool for physical simulation indicates that rolling at 450°C using a rate of 1 s^–1 rate represent suitable rolling conditions. Successive hot rolling resulted in decreasing void percent and SiCp agglomeration. Hence, enhanced mechanical properties are achieved.     

Irradiation effect on PET surface using low energy argon ion beam

A study of various physical properties of a PET film irradiated with an Ar beam is reported. SEM images and UV–VIS and FTIR spectra were obtained for a number of ionic fluxes and three irradiation times. Small changes in the energy gap of degradated samples were found, and the SEM images indicate that the optimum homogeneity and roughness are reached after 30 min of irradiation. These results may well be of practical interest. A modified saddle field ion source was used as a preparation tool of the surface of polyethylene terephthalate PET polymer substrate to be ready for coating or thin film deposition. Argon ion beam was used for this purpose, where the scanning electron microscope (SEM) shows that, the best sample is the one which was irradiated to 30 min, where this sample is more homogenous and roughness than other irradiated samples. Also the (UV–VIS) spectrum tells us that, there is small change on energy gap and this is meaning that, the change on electric properties is small also. In this case the sample is more homogenous and of higher roughness than other irradiated samples.     

Effect of drying conditions on autogenous shrinkage in ultra-high performance concrete at early-age

This experimental study investigated the effects of drying conditions on the autogenous shrinkage of ultra-high performance concrete (UHPC) at early-ages. UHPC specimens were exposed to different temperatures, namely, 10, 20 and 40°C under a relative humidity (RH) ranging from 40 to 80%. The effects of using a shrinkage-reducing admixture (SRA) and a superabsorbent polymer (SAP) as shrinkage mitigation methods were also investigated. The results show that autogenous and drying shrinkage are dependent phenomena. Assuming the validity of the conventional superposition principle between drying and autogenous shrinkage led to overestimating the actual autogenous shrinkage under drying conditions; the level of overestimation increased with decreasing RH. Both SRA and SAP were very effective in reducing autogenous shrinkage under sealed conditions. However, SRA was efficient in reducing drying shrinkage under drying conditions, while SAP was found to increase drying shrinkage. Generally, results indicate that adequate curing is essential for reducing shrinkage in UHPC even when different shrinkage mitigation methods are applied.     

Generation and classification of CCII and ICCII based negative impedance converter circuits using NAM expansion

A new simplified generation method of negative impedance converter circuits (NIC) is introduced. The generation method is based on nodal admittance matrix expansion starting from the input admittance of the NIC circuit terminated by a load rather than treating the NIC as a two‐port network element. The four pathological elements, namely nullator, norator, voltage mirror and current mirror, are used in the generation procedure. Two classes of the NIC pathological circuits are defined; each class includes two types. Eight pathological NIC circuits are generated for each class. Two alternative current conveyor and inverting current conveyor‐based realizations for each pathological circuit based on alternative pairing of the pathological elements are defined resulting in a total of 16 NIC circuit for each class and a total of 32 NIC circuits. A new NIC‐based circuits realizing floating negative impedances are also introduced. Copyright © 2010 John Wiley & Sons, Ltd.     

Pathological representation of the two‐output CCII and ICCII family and application

The pathological mirror and nullor representation of the two‐output current conveyor family is given. New pathological mirror and nullor representations of the two‐output current conveyor family are given and compared with the corresponding nullator norator resistors' realizations. Simplified representations of the two‐output current conveyors based on using two single‐output current conveyors are given. Two examples are given, the first example demonstrates the importance of the pathological representation in the generation of a family of 16 oscillators from a two‐output current conveyor‐based current mode oscillator. A second example of a current mode low‐pass filter using two single‐output inverting current conveyors is considered. Its simplified modeling using a single balanced output inverting current conveyor is compared with the original current mode filter and the simulation results are given. Copyright © 2010 John Wiley & Sons, Ltd.     

Fully coupled solution of a two-phase model for laminar film condensation of vapor-gas mixtures in horizontal channels

Detailed results are presented for laminar film condensation of vapor-gas mixtures in horizontal flat-plate channels using a fully coupled implicit numerical approach that achieves excellent convergence behavior. These results correspond to steam-air and R134a-air mixtures over wide ranges of the independent parameters, and they include velocity, temperature, and gas concentration profiles, as well as axial variations of film thickness, pressure gradient and Nusselt number. Effects of the four independent variables (inlet values of gas concentration, Reynolds number and pressure, and the inlet-to-wall temperature difference) on the film thickness, pressure gradient, and the local and average Nusselt numbers are carefully examined. It was found that the condensation of R134a-air corresponds to thicker liquid films, lower heat transfer rates, and lower algebraic values of the pressure gradient when compared with steam-air at the same operating conditions.     

Detection of food fraud of meat products from the different brands by application of histological methods

In Sohag City, 400 samples were collected from different food markets of different meat products from two companies with high and low prices (e.g., minced meat, kofta sausage, beef burger, and luncheon meat) for determining food fraud. Light, fluorescence, and scanning electron microscopy (SEM) were used to examine the samples. “Special histochemical stains” permit the microscopic examination of different cell types, structures, and/or microorganisms. Histological examination revealed variant tissue types, besides skeletal muscles. Nuchal ligaments, bones, hyaline cartilages, white fibrocartilages, large and medium arteries, cardiac muscles, tendons, and collagenous connective tissues comprised the capsule of a parenchymatous organ. Additionally, a crystal of food additives was recognized using light microscopy and SEM. SEM allows the visualization of bacterial contamination. Using different microscopic anatomy techniques is an efficient methodology for qualitative evaluations of various meat products. No difference in quality was observed between low- and high-priced meat products.     

Fiber single crystal growth by LHPG technique and optical characterization of Ce-doped Lu2SiO5

The laser heated pedestal growth (LHPG) technique has been applied to grow undoped and doped Lu₂SiO₅:Ce³⁺ (LSO:Ce) single crystals fibers with stable diameter. The starting cerium concentration in the melt was [0.05–1] at.%. The thermal and growth conditions allowing pulling transparent single crystals fiber’s were optimised. The fibers have been grown under N₂ + 1% O₂ atmosphere (1 bar). The Ce³⁺ segregation coefficient is 0.28 greater than the crystal grown by Czochralski technique. The as grown fibers demonstrated scintillating properties.