Rapid simulation models for aluminium furnaces design

The minimisation of energy consumption in aluminium metal casting industries requires an appropriate design of the furnaces to reduce as possible the heat losses through the walls. Detailed simulation models have been developed that allow the in-depth study of furnace behaviour, but these models are too complex and slow for some industrial necessities. To make possible a fast evaluation during preliminary phases more agile models are needed. This agility may be achieved by simplified models, but the results could be affected by a lack of accuracy. The work presented hereafter shows how the steady state analysis of the furnace walls with simplified models of finite elements may give sufficiently accurate and fast results. The simulation models have been validated against experimental results, thus confirming their ability to adequately reproduce the thermal behaviour of the walls of several furnaces regardless of their composition or heating system.     

Analytical assessment of multi-user vs. spatial diversity trade-offs with delayed channel state information

In this letter, we explore the combined use of spatial and multi-user diversity in a cellular system where channel state information is subject to delays in the feedback channel. First, we analytically derive the probability and cumulative density functions of the post-scheduling signal-to-noise ratio (SNR) for both a single-input single-output (SISO) and an orthogonal space-time block coding (OSTBC) transmission schemes. Then, we obtain the closed-form expressions of the corresponding average system capacities. By evaluating those expressions, we analytically show that the OSTBC scheme is far less sensitive to delays in the feedback channel.     

Study of chimerism in long-term survivors after bone marrow transplantation for severe acquired aplastic anemia

Chimerism studies employing PCR and Southern techniques targeting VNTR loci were performed in 17 severe acquired aplastic anemia patients who were long-term survivors after BMT. They were studied a median of 4 years after BMT (1-12). All patients had normal blood counts. All patients conditioned with radiation-based schemes showed a full donor pattern of hemopoiesis. Conversely, out of five patients who received only cyclophosphamide as conditioning therapy, two of them had a late graft failure (2.4 and 3 years after BMT). One of these relapsing patients had a durable mixed chimerism, which was first detected 1 month after BMT. Our results seem to suggest that durable mixed chimerism can antecede graft failure in some patients conditioned only with cyclophosphamide, and that a more stringent monitoring can be clinically rewarding in this group of patients.     

Chromatic evolution of virgin olive oils submitted to an accelerated oxidation test

Six samples of virgin olive oil obtained from several varieties of olive fruits (Picual, Manzanilla, Lechín, and Arbequina) were submitted to an accelerated oxidation process during a 63-h period under the conditions of the oil stability index (OSI), as measured by a Rancimat (100°C) apparatus. Spectra were measured every 3 h, and chlorophyll and carotenoid indexes and CIFLAB color ordinates were calculated. As oxidation time increased, remarkable changes in the spectral characteristics and color ordinates were observed. Oxidation provoked less vivid colors (lower values for chroma, C _* ^ab ) in all the samples; however, only some varieties became darker (lower values for lightness, L^*). The pigment loss calculated for oxidized oils was 67% for the carotenoid index and 58% for the chlorophyll index. Mathematical models are offered to predict color changes with time of storage at 20°C.     

Nutritional importance of carotenoid pigments

Carotenoids are responsible for the colour of a great number of both vegetable and animal foods, such as carrots, orange juice, tomato, salmon and egg yolk. It has been known for many years that some of these compounds, such as alpha and beta-carotene, as well as beta-cryptoxanthin, are provitamins A. However, recent studies have shown the antioxidant properties of these compounds and their efficiency in the prevention of certain human diseases, such as atherosclerosis or cancer. Because of all this, the interest in these compounds has increased substantially from a nutritional point of view.     

Modelling Spatial Relationships between Colour Clusters

Modelling of image content based on chromatic arrangement requires suitable techniques for the representation of the spatial relationship between complex sets of pixels. We propose a model of spatial relationship between extended sets, which can be computed with the same computational complexity involved in conventional representations based on centroids, but which improves effectiveness by accounting for the overall sets of pixels involved in the relationship. The effectiveness of the proposed model is compared against the orientation between centroids in a user-based evaluation.     

Towards high-power single-cycle THz laser for initiating high-field-sensitive phenomena

Powerful THz radiation confined in one field period or less is an adequate tool for triggering nonlinear actions. We show results towards the realization of a tunable high-power THz source based on a laser-driven frequency conversion scheme in plasma and nonlinear crystals. A powerful THz source in combination with the future X-ray Free Electron Laser facility in Switzerland (SwissFEL) holds promise for exciting experiments in a variety of different research areas.     

Using Conveniently Designed α‐Amino Ketones in Michael Reactions under Iminium Catalysis: Enantioselective Synthesis of γ‐Lactams and γ‐Amino‐δ‐keto Esters

The behaviour of aminoacetophenones as Michael donors in catalytic enantioselective Michael reactions with α,β‐unsaturated aldehydes under iminium activation has been studied. These compounds react with each other in the presence of catalytic amounts of a chiral secondary amine through a Michael/hemiaminal formation cascade process which proceeds with high yields and enantiocontrol. Elaboration of these adducts by oxidation allows the easy access to chiral disubstituted γ‐lactams and other synthetically useful chiral building blocks such as γ‐amino‐δ‐keto esters or β‐substituted δ‐oxoamides are accessible from the obtained adducts by simple transformations.     

Digital Image Analysis and Visual Evaluation of Orange Juice: Influence of Different Measurements' Conditions

This study assesses the effect of background, surrounding, thickness and dilutions on the colour specifications of orange juice (OJ) analyzed by digital image and visual evaluation. A commercial OJ was diluted with distilled water to give ten levels of concentration (100, 90, 80, 70, 60, 50, 40, 30, 20 and 10 % of juice). These samples were evaluated instrumentally by digital image analysis using nine combinations of surroundings and backgrounds (black, grey and white) and three different thicknesses. Visual evaluation was also carried out on black, grey and white backgrounds. A grey surrounding, a white background and a fixed thickness are suggested to be used in future measurements of OJ colour by digital image analysis. Results of visual evaluation indicated that panellists were able to order correctly the OJ samples according to the dilution level, independently of the background chosen. The correlations between the instrumental and the visual analysis were significant (p?<?0.05) in all the backgrounds explored.