Forming processes control by means of artificial intelligence techniques

Forming processes are manufacturing processes that use force and pressure in order to modify the shape of a material part until obtaining the final product. The wide range of non-linear factors that drive this sort of processes make them very complex and extremely difficult to be controlled. Traditional control techniques, like PID controllers, have not offered a reliable solution when global control has been pursued and the figure of the operator still remains present in most of the forming facilities. On the other hand, although operators have demonstrated to be a very successful strategy when controlling this type of processes, the actual market evolution towards the fabrication of more complex parts, made of lower formability materials at higher production rates, is decreasing their capacity of reaction when solving the daily problems. Thus, the development of new global control systems based not on traditional control techniques and mathematical models but on the control strategy that has been used successfully for many years, the control through the experience and knowledge is now even more necessary. In the present work, an intelligent control system based on one of the main techniques within the artificial intelligence, expert systems, has been developed. The main purpose of this intelligent control system is to emulate the decisions that expert operators take but in a quicker and more reliable way. The developed intelligent control system has been installed in a blanking facility and very good results have been achieved.     

Detection of IgM against the dengue++ virus in whole blood absorbed on filter paper]

Thirty-four sheep were submitted to surgery substituting the native ACL with the central third of the patellar tendon, ten enter this study. The purpose was to find a possible relationship between tissue pO2 and healing processes considering also the biomechanical and histomorphological aspects of the grafts. Four of them were sacrificed under general anaesthesia after 6 months, and six after 1 year in order to perform tissue pO2 measurement and an analysis of microvessel density on specimens of the normal ACL and the graft. Our data showed higher pO2 values of the autografts after 6 months. After 1 year the data was comparable to those of native ACL. This was confirmed by a microvessel count of the histological specimens and the data was in relationship to biomechanical and histomorphological analysis. Tissue pO2 can be observed and recorded in "in vivo" ACL, and patellar tendon used as graft, with no injury to their integrity. The monitoring system might be considered as an experimental tool for indirect controls of the anterior cruciate substitutes.     

Quadratic cost functional for wave-front reconstruction

A quadratic cost functional for reconstruction of a high-resolution wave front from a coarse wave front is presented. The functional uses as data the position and the direction of the coarse wave front that had previously been computed with a ray-tracing method. This functional uses an optical relationship between the ray information and the wave front's shape to reconstruct a high-density wave front. The performance of the proposed functional is illustrated by reconstruction of complicated wave fronts for which this functional has an accuracy that is superior to that of conventional interpolation methods.     

3D sound interactive environments for blind children problem solving skills

Audio-based virtual environments have been increasingly used to foster cognitive and learning skills. A number of studies have also highlighted that the use of technology can help learners to develop effective skills such as motivation and self-esteem. This study presents the design and usability of 3D interactive environments for children with visual disabilities to help them solve problems in Chilean geography and culture. We introduce AudioChile, a virtual environment that can be navigated through 3D sound to enhance spatiality and immersion throughout the environment. 3D sound is used to orientate, avoid obstacles, and identify the positions of various characters and objects within the environment. We have found during the usability evaluation that sound can be fundamental for attention and motivation purposes during interaction. Learners identified and clearly discriminated environmental sounds to solve everyday problems, spatial orientation, and laterality.     

Effect of pH on the precipitation of hydroxyapatite on silica gels

Silica-HAp composites have been produced with particle size ranging from several nm to few μm, through control of the pH of the solution, which also controls morphology. A calcium ions reservoir has been made available as a Ca/EDTA soluble complex allowing the production of HAp at low temperature and short periods of time (hours). The presence of silica seems to promote the formation of HAp under these conditions. Electronic Publication     

Determination of hydrogen absorption in Pd coated Al thin films

Al films, 80–85 nm in thickness and 10–30 μΩ cm in resistivity, are coated with Pd (8–40 nm). The bilayer is exposed to a hydrogen atmosphere of up to 4.0 kPa. The hydrogen concentration is calculated from the frequency change in a quartz crystal microbalance and the electrical resistance of the Pd film, the Al film and the bilayer is measured as function of hydrogen pressure. Concentration and resistance measurements indicate that the Pd coating enables the Al films to absorb hydrogen from the gas phase.     

A multispectral imaging technique to determine concentration profiles of myoglobin derivatives during meat oxygenation

We have designed a multispectral imaging acquisition system to measure the relative concentration values of myoglobin forms inside meat during oxygenation. Images at 474, 525, 572 and 610 nm are used to compute the concentration of reduced myoglobin, oxymyoglobin and metmyoglobin with a spatial resolution of 0.0125 mm/pixel. From these images, pigment concentration profiles as a function of oxygenation time and depth beneath the surface were obtained. A model describing the diffusion of oxygen and the consumption of reduced myoglobin is numerically tested versus the measured concentration profiles. The model accurately fits the data with a Mean Root Squared Error equal to 0.253%. Precise definitions for position and width of pigment layers based in concentration profiles are given. The results suggest that multispectral imaging techniques combined with precise control and measurement of sample temperature and oxygen partial pressure will permit detailed studies of the myoglobin chemistry during oxygenation.     

Antimicrobial activity of nisin against Oenococcus oeni and other wine bacteria

Nisin is a bacteriocin used against food spoilage bacteria. Sulphur dioxide is a potent antioxidant as well as an antimicrobial agent widely used in the wine industry. In this study we describe the effect of these important antibacterial agents on the growth of a collection of 64 lactic acid bacteria (23 Oenococcus, 29 Lactobacillus, 3 Leuconostoc and 9 Pediococcus), 23 acetic acid bacteria and 20 yeast isolates, most of them recovered from wine. Minimal inhibitory concentrations (MIC) and minimal bactericide concentrations of nisin, potassium metabisulphite and ethanol were determined. Nisin MIC(50) values for the tested isolates were as follows: 0.024, 12.5, 200 and > or micro for oenococci, lactobacilli-pediococci-leuconostoc, acetic acid bacteria and yeasts, respectively. Synergistic effects on bacterial growth inhibition were observed, and potassium metabisulphite MIC(50) values decreased from one to three orders of dilution when it was combined with subinhibitory concentrations of nisin in the growth media. This effect was observed in all lactic acid bacteria species of our study. Significant differences in nisin sensitivity were observed between Gram-positive and Gram-negative bacteria, and between Oenococcus oeni and other species of lactic acid bacteria. It is concluded that appropriate combinations of nisin and metabisulphite could control the growth of spoilage bacteria in wine and therefore allow a decrease in the levels of sulphur dioxide currently used by the wine industry.