Correlation between hydrogen storage properties and textures induced in magnesium through ECAP and cold rolling

It is feasible to obtain a significant enhancement of the hydrogen storage capability in magnesium by selecting an appropriate sequence of mechanical processing. The Mg metal may be produced with different textures which will then give significant differences in the absorption/desorption kinetics and in the incubation times for hydrogenation. Using processing by equal-channel angular pressing (ECAP), different textures may be produced by changing both the numbers of passes through the ECAP die and the ram speed. Significant grain refinement is easily avoided by using commercial coarse-grained magnesium as the starting material. The use of cold rolling after ECAP further increases the preferential texture for hydrogenation. The results show that the hydriding properties are enhanced with a (002) texture where the improved kinetics lie mainly in the initial stages of hydrogenation. An incubation time is associated with the presence of a (101) texture and this is probably due to the magnesium oxide stability in this direction.     

Adhesion and Wetting Hysteresis of a Metal (Mercury) on an Oxide Glass in Air and Nitrogen

In general, oxygen can considerably change the wetting behavior of oxides by molten metals. This work is a basic illustration of the oxidation effect on the wetting behavior of glass by a liquid metal. Taking mercury as a model of a metal, the importance of the metal oxidation in the glass/metal interaction has been observed by measuring wetting contact angles of mercury on glass and the ability of calibrated mercury drops to slide down, under gravitation, on an inclined glass plate in air or in nitrogen. It is believed that the highest force of detachment by sliding of the mercury drop in air results from the metal oxidation which can be interpreted by a higher contact angle hysteresis when the metal is exposed to air.     

Peeling of Elastic Tapes: Effects of Large Deformations,Pre-Straining,and of a Peel-Zone Model

A peel model for non-linear elastic tapes is presented which accounts for large deformations and for pre-straining. The large deformation setting is a new feature of modelling, which would be of interest for applications related to soft polymers and tissues. The conditions for having quasistatic-steady debonding or dynamic catastrophic debonding are determined in terms of the loading variables (peel angle and peeling force). The decohesion energy associated with a given process-zone model is included in the formulation of the peeling model. The predictions of various decohesion laws are discussed with respect to experimental results in the literature. Finally, the adhesion of a gecko is analysed and the maximum adhesion force of a single spatula is evaluated. The result correlates well with the maximum experimental pulling force reported in the literature for a gecko's seta.     

Efficiency of pulse pressure treatment for inactivation of <Emphasis Type="Italic">Escherichia coli</Emphasis> and <Emphasis Type="Italic">Listeria innocua</Emphasis> in whole milk

Escherichia coli ATCC 11775 and Listeria innocua ATCC 33090 in whole milk were inactivated by single- and multi-pulsed (up to 10 pulses) high hydrostatic pressure (HHP) treatments. Both bacteria showed similar resistance to single- and multi-pulsed HHP. The efficiency of pulsed pressure treatment depends on the combination of holding time of each pulse and number of pulses. It was observed that multi-pulsed pressure treatment instead of traditional single-pulsed HHP could be used to pasteurize milk at a lower pressure level. Nevertheless, an optimization is necessary between the pulse holding time, number of pulses, and pressure levels to reach the desirable log-reduction of microorganisms compatible with industrial application. This study was partly presented in Joint 21st AIRAPT and 45th EHPRG International Conference on High Pressure Science and Technology held September 17–21, 2007 in Catania (Italy).     

Trackball开关使手持设备具有PC鼠标功能

引言 新一代的手持设备正变得越来越小巧精致,最终用户的软件接口也变得越来越复杂.随着基于软件的电子设备集成度不断提高,手机、个人数字助理(PDA)、手表和全球定位系统等设备越来越象计算机,都使用图标菜单进行操作.     

Influence of the amount of steaming during baking on the kinetic of heating and on selected quality attributes of bread

The effect of the amount of steam injection on selected bread characteristics were investigated using a deck oven (1 m² internal surface). Baking was done at 200 °C for 20 min with steaming of 100, 200, 300, 400 and 500 ml. The temperature at center of the bread and the CO₂ concentration in the oven have been measured during baking. Specific volume, moisture loss and crust crumb ratio were measured after baking.The heating rate between 35 and 55 °C was considered to compare the steaming conditions. For low steaming (100 and 200 ml), the heating rate was significantly higher (p < 0.05) than those at higher steaming (400-500 ml). The heating rate at 300 ml was between the 100-200 and 400-500 ml groups. This difference was attributed to the condensation of steam on the loaf for higher steaming, which in turns slows down the heating rate. The largest bread volume was obtained either for low or high steaming. However, tearing of the crust was observed for low steaming. The crust-crumb ratio was increasing with decreasing amount of steaming. The amount of CO₂ released during baking was higher for the highest amount of steaming; however, this result was not statistically different except between 100 and 500 ml. This could be attributed to a slower heating rate which in turns favors the secondary production of CO₂ during baking until thermal inactivation of CO₂.     

Effect of tool setting error on the topography of surfaces machined by peripheral milling

In peripheral milling operations, errors in the tool setting on the spindle create roughness heterogeneity bands on the milled surfaces. This represents a defect in the appearance of the surfaces that cannot be ignored when surfaces have to meet high aesthetic requirements. Although the existence of these bands has been reported long ago, a quantitative evaluation has not been made so far.This paper presents a new model that allows the prediction of bands generated on surfaces machined by peripheral milling. This model accounts for tool setting errors: cutter parallel axis offset and cutter axis tilt. Through the proposed model, the effects of tool setting error, cutter geometry and feed, on band position, width and roughness are evaluated. Cutting tests were carried out to validate the model predictions and it was found that model predictions on band position and width agreed reasonably well with experimental results.     

Cox–Ingersoll–Ross model for wind speed modeling and forecasting

We propose a dynamic model for the squared norm of the wind speed which is a Markov diffusion process. It presents several advantages. Since the transition probability densities are in closed form, it can be calibrated with the maximum likelihood method. It presents nice modeling features both in terms of marginal probability density function and temporal correlation. We have tested the model with real wind speed data set provided by the National Renewable Energy Laboratory. The model fits very well with the data. Besides, we obtained a very good performance in forecasting wind speed at short term. This is an interesting perspective for operational use in industry. Copyright © 2015 John Wiley & Sons, Ltd.     

Room-temperature optical detection of hydrogen gas using palladium nano-islands

Palladium thin films of different thicknesses have been processed by oxidation and subsequent reduction in hydrogen atmosphere. Hydrogen optical sensing properties of as-deposited (Pd) and processed (r-Pd) samples have been experimentally tested with a H₂ concentration of 5% and 1%, discovering that the reduced films show improved performances in term of response/recovery time. As reveled by SEM images, the oxidation/reduction process modifies the surface appearance, which assumes a nano-islands structured morphology. The porosity of the processed films may explain the reduction of the response/recovery time, while the larger effective sensing surface in thinner samples justifies the responsivity performances.     

Laser Polymer Tattooing: A Versatile Method for Permanent Marking on Polymer Surfaces

A versatile and efficient method for the permanent marking of polymer surfaces that combines inkjet deposition and near‐infrared (NIR) laser curing is investigated. The NIR laser treatment forces the ink particles to migrate into the upper layers of the polymer. This results in the fixation of a permanent grayscale image that can be applied to various polymers, such as polypropylene, which is widely used in industry but still difficult to mark. The physiochemical processes induced by laser curing are investigated by electronic and optical microscopy. The dependence of the thickness of the deposited ink and the laser power on the contrast of marking are also studied. A mechanism implying fast laser‐induced melting of the polymer surface followed by displacement of carbon nanoparticles by convection is proposed. Finally, a comparison of the aging properties of samples prepared by this process and standard UV ink is proposed to illustrate the interesting nature of this new polymer marking process. Integrating the ink under the surface of the polymer, as in a skin tattooing procedure, by laser curing is an efficient way to generate permanent images on polymer surfaces.