Potential of Ozonated Water at Different Temperatures to Improve Safety and Shelf-Life of Fresh Cut Lettuce

The present study was carried out to determine the effect of ozonated water (2 mg L^?1) at different temperatures (4 °C and 15 °C) on the microbiological, color and sensory properties of lettuce. Cold ozone treatment (4 °C) significantly reduced the natural background microflora of lettuce. Salmonella Typhimurium and Escherichia coli inoculated on lettuce samples were insignificantly influenced by the temperature of water. During storage period at +4 °C for 14 days, the highest quality was observed from the samples treated with cold ozonated water. Ozone treatments did not affect the color properties and sensory quality of lettuce samples.     

Automatic Contrast Enhancement by Transfer Function Modification

In this study, we propose an automatic contrast enhancement method based on transfer function modification (TFM) by histogram equalization. Previous histogram‐based global contrast enhancement techniques employ histogram modification, whereas we propose a direct TFM technique that considers the mean brightness of an image during contrast enhancement. The mean point shifting method using a transfer function is proposed to preserve the mean brightness of an image. In addition, the linearization of transfer function technique, which has a histogram flattening effect, is designed to reduce visual artifacts. An attenuation factor is automatically determined using the maximum value of the probability density function in an image to control its rate of contrast. A new quantitative measurement method called sparsity of a histogram is proposed to obtain a better objective comparison relative to previous global contrast enhancement methods. According to our experimental results, we demonstrated the performance of our proposed method based on generalized measures and the newly proposed measurement.     

Thermal fatigue testing of CuCrZr alloy for high temperature tooling applications

CuCrZr alloy offers good mechanical and thermal properties and was investigated in the present work for its potential as tooling material in thixoforming of steels. Samples of CuCrZr alloy were cycled thermally between 450 and 750 °C, every 60 s. The thermal conductivity of the CuCrZr alloy, nearly an order of magnitude higher with respect to that of the conventional hot work tool steel, proved to be very beneficial in terms of thermal stresses generated at the surface upon thermal cycling. The maximum compressive and tensile stresses produced at the front face of the CuCrZr alloy were estimated to be approximately 30 and 10 MPa, respectively, much smaller than those endured by the conventional hot work tool steel. The very favourable thermal stress state in the CuCrZr alloy die was largely negated, however, due to its inferior resistance to high temperature oxidation.     

The Effect of Reduction Parameters on Iron Nugget Production From Composite Pellets

Composite pellets which contain a reducing agent and are produced only by cold bonding process are improved instead of traditionally hardened pellets by sintering. The new ironmaking technologies that are able to utilize these pellets have been developed from pilot plant to commercial scale. Iron nuggets which have a similar composition to pig iron can be produced by using composite pellets at high temperatures (1350–1400°C) and in a short reduction time (15–20 min) by smelting reduction process. In this study, the effect of reduction parameters and basicity of composite pellets on the reduction properties and product quality are investigated. Composite pellets containing magnetite concentrate with a reducing agent (coke) and a flux are processed at different temperature and at times by smelting reduction process. The increasing temperature and time has a positive effect on reduction and melting of the pellets. Excessive carbon prevents the metal droplets from coalescing. The iron nugget that is produced from the sample with the basicity (CaO/SiO₂) of 0.68 has the optimal physical and chemical properties. It is also determined that a decrease or increase of basicity has a negative effect on the properties of the iron nuggets.     

铝含量对AZ系列镁合金机械加工性能的影响

研究铝含量对AZ系列铸造铝合金机械加工性能的影响。为评价该合金的机械加工性能,测量切削操作过程中的切削力以及表面粗糙度,以及研究显微组织和拉伸性能。结果表明：添加2%铝含量的镁合金具有最佳的拉伸性能。随着铝含量增加到2%以上,由于晶界上析出金属间化合物β-Mg17Al12,切削力会随延展性的降低而降低。切削力也会随着切削速度的增加而增大,这是由于在加工过程中切削工具的尖端有侧面生成。     

Effect of Welding Parameters on the Microstructure and Strength of Friction Stir Weld Joints in Twin Roll Cast EN AW Al-Mn1Cu Plates

Twin roll cast EN AW Al-Mn1Cu plates were butt welded with the friction stir welding process which employed a non-consumable tool, tilted by 1.5° and 3° with respect to the plate normal, rotated in a clockwise direction at 400 and 800 rpm, while traversing at a fixed rate of 80 mm/min along the weld line. Microstructural observations and microhardness tests were performed on sections perpendicular to the tool traverse direction. Tensile tests were carried out at room temperature on samples cut perpendicular to the weld line. The ultimate tensile strength of the welded EN AW Al-Mn1Cu plates improved with increasing tool rotation speed and decreasing tool tilt angle. This marked improvement in ultimate tensile strength is attributed to the increase in the heat input owing to an increased frictional heat generation. There appears to be a perfect correlation between the ultimate tensile strength and the size of the weld zone. The fracture surfaces of the base plate and the welded plates are distinctly different. The former is dominated by dimples typical of ductile fractures. A vast majority of the intermetallic particles inside the weld zones are too small to generate dimples during a tensile test. The fracture surface of the welded plates is thus characterized by occasional dimples that are elongated in the same direction suggesting a tensile tearing mechanism.     

Towards monitoring electrostatics in gas–solid fluidized beds

The electrostatic charge distribution in a lab‐scale 2‐D fluidized bed of 900 µm glass beads was determined using arrays of induction probes, and the influence of relative humidity and superficial gas velocity was examined. The bubble presence, relative humidity, and superficial gas velocity were found to influence charge separation. Bipolar charging was observed; the net charge build‐up was found to be negligible. Moreover, the system was monitored by applying the attractor comparison method to the electrostatic charge signals from an induction probe. It was concluded that this approach can indeed be used to monitor changes in the electrostatic behaviour.     

A novel Al–Ti–B alloy for grain refining Al–Si foundry alloys

Al–Ti–B refiners with excess-Ti (Ti:B > 2.2) perform adequately for wrought aluminium alloys but they are not as efficient in the case of foundry alloys. Silicon, which is abundant in the latter, forms silicides with Ti and severely impairs the potency of TiB₂ and Al₃Ti particles. Hence, Al–Ti–B alloys with excess-B (Ti:B < 2.2) and binary Al–B alloys are favored to grain refine hypoeutectic Al–Si alloys. These grain refiners rely on the insoluble (Al,Ti)B₂ or AlB₂ particles for grain refinement, and thus do not enjoy the growth restriction provided by solute Ti. It would be very attractive to produce excess-B Al–Ti–B alloys which additionally contain Al₃Ti particles to maximize their grain refining efficiency for aluminium foundry alloys. A powder metallurgy process was employed to produce an experimental Al–3Ti–3B grain refiner which contains both the insoluble AlB₂ and the soluble Al₃Ti particles. Inoculation of a hypoeutectic Al–Si foundry alloy with this grain refiner has produced a fine equiaxed grain structure across the entire section of the test sample which was more or less retained for holding times up to 15 min.     

Spatiotemporal distribution of facilitation and inhibition of return arising from the reflexive orienting of covert attention.

Currently, there is debate regarding both the spatial and temporal relationship between facilitation and inhibition of return (IOR) components of attention, as observed on the covert orienting of visual attention task (COVAT). These issues were addressed in a series of experiments where the spatial and temporal relationships between cue and target were manipulated. Facilitation occurred only when the stimulus onset asynchrony (SOA) was short and there was temporal overlap between cue and target. IOR occurred only when SOA was long and there was no temporal overlap between cue and target. Facilitation encompassed the cued location and all locations between the cue and fixation, whereas IOR arose for the entire cued hemifield. These findings suggest that the facilitation and IOR found on COVATs that use noninformative peripheral cues are separable and stimulus-driven processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)