Stabilized continuous and discontinuous Galerkin techniques for Darcy flow

We design stabilized methods based on the variational multiscale decomposition of Darcy's problem. A model for the subscales is designed by using a heuristic Fourier analysis. This model involves a characteristic length scale, that can go from the element size to the diameter of the domain, leading to stabilized methods with different stability and convergence properties. These stabilized methods mimic different possible functional settings of the continuous problem. The optimal method depends on the velocity and pressure approximation order. They also involve a subgrid projector that can be either the identity (when applied to finite element residuals) or can have an image orthogonal to the finite element space. In particular, we have designed a new stabilized method that allows the use of piecewise constant pressures. We consider a general setting in which velocity and pressure can be approximated by either continuous or discontinuous approximations. All these methods have been analyzed, proving stability and convergence results. In some cases, duality arguments have been used to obtain error bounds in the L²-norm.     

Designing a system to extract and interpret timed causal sentences in medical reports

Causal sentences are a main part of the medical explanations, providing the causes of diseases or showing the effects of medical treatments. In medicine, causal association is frequently related to time restrictions. So, some drugs must be taken before or after meals, being ‘after’ and ‘before’ temporary constraints. Thus, we conjecture that medical papers include a lot of time causal sentences. Causality involves a transfer of qualities from the cause to the effect, denoted by a directed arrow. An arrow connecting the node cause with the node effect is a causal graph. Causal graphs are an imagery way to show the causal dependencies that a sentence shows using plain text. In this article, we provide several programs to extract time causal sentences from medical Internet resources and to convert the obtained sentences in their equivalent causal graphs, providing an enlightening image of the relations that a text describes, showing the cause-effect links and the temporary constraints affecting their interpretation.     

A path-relinking approach for a bi-criteria disassembly sequencing problem

The first crucial step of product recovery is disassembly. Some product disassembly is almost always needed in remanufacturing, recycling, and disposal. Since disassembly tends to be expensive, disassembly sequence planning becomes important in minimizing resources (time and money) invested in disassembly and maximizing the level of automation. A disassembly sequence plan (DSP) is a sequence of disassembly tasks, which begins with a product to be disassembled and terminates in a state where all of the parts of interest are separated. The decision version of the problem of finding the optimal DSP is an NP-complete problem and therefore complex and challenging to solve. Often one has to resort to heuristic and metaheuristic techniques for solving such problems. In this paper, we seek a DSP that addresses two criteria in order. First, we look for a sequence, the cost of which is close to our cost aspiration. Second, we look for a sequence that prioritizes some selected parts to be disassembled as early as possible. We propose a greedy randomized adaptive search procedure (GRASP) and path-relinking-based heuristic methodology specifically developed to solve such bi-criteria type of disassembly problem. An example is considered to illustrate the implementation of the methodology. Conclusions drawn include the consistent generation of near-optimal solutions, the ability to preserve precedence, the superior speed of the metaheuristic, and its practicality due to its ease of implementation.     

Guidelines for the development of e-learning systems by means of proactive questions

The current development approaches for e-learning systems fail to explain in a clear and consistent way the pedagogical principles that support them. Moreover, decisions with regard to the structuration of each component proposed by these approaches are mainly taken by the designer/developer. As a result, the ensuing e-learning systems reflect “common sense” rather than a theoretically informed and systematic design.The present paper proposes a global architecture model for any e-learning system whose blocks are extracted from the analysis of the main approaches that currently guide the development of these kinds of systems. We use Kipling’s famous questions to define and structure the blocks of the proposed model, and we base the answers to these questions on two disciplines that are closed to e-learning: presential education (i.e., its pedagogical theories) and knowledge management.     

Microhardness of styrene/butadiene block copolymer systems: Influence of molecular architecture

The influence of molecular architecture on the mechanical properties of styrene/butadiene block copolymers was investigated by means of the microhardness technique. It was found that the microhardness of the styrene/butadiene block copolymers is dictated by the nature of microphase separated morphology. In contrast to polymer blends and random copolymers, in which the microhardness generally follows the additivity rule, the behavior of the investigated block copolymers was found to significantly deviate depending on their molecular architecture. The glass‐transition temperature of the polystyrene phase (T_g‐PS), which practically remained constant and that of the polybutadiene phase (T_g‐PB), which varied with the change in the block copolymer architecture, apparently do not influence the microhardness values of the block copolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1670–1677, 2003     

Influence of wool bleaching with hydrogen peroxide on dyeing with CI Acid Blue 80

This study investigates the influence of wool bleaching with hydrogen peroxide on the kinetics of wool dyeing, using a milling dye CI Acid Blue 80. The dyeing kinetics were studied at different temperatures on both unbleached and bleached wool [15 and 30 ml hydrogen peroxide (35% w/w)] and the following parameters determined: kinetics of adsorption, diffusion coefficient and apparent activation energies of the dyeing system for each type of wool. The results show that the values of these parameters are greater for the unbleached wools than for the bleached ones and that the values decrease as the bleaching intensity increases.     

Changes in body composition in lactating adolescent mothers

We assessed changes in body composition in lactating adolescent mothers living under unfavorable socioeconomic and sanitary conditions. A total of 17 healthy primiparous adolescents under 17 years of age attending the Maternity Hospital of the city of La Plata, Argentina, were followed at 4 time points (15 days and 3, 6 and 12 months postpartum) to assess, a) dietary intake, b) practice of physical activity, c) nutritional condition (weight, height, body mass index [BMI] according to age, and body composition by the sum of skinfold measurements), d) characteristics of lactation, and e) growth parameters of the child. The mean age of adolescents was 15.06 +/- 0.66 years (mean menarchal age, 11.59 +/- 0.80 years). All adolescents breastfed up to 12 months postpartum, and maternal milk covered above 80% the baby intake (mean 7.06 +/- 2.54 breast feeds/day). While the daily intake of nutrients by adolescent mothers was constant up to 6 months postpartum, there was a modest decrease in that of proteins, carbohydrates and lipids 15 days and 12 months postpartum. The decrease in energetic intake during the same period was significant (p < 0.05). The practice of physical activity was classified as moderate during the follow-up period. Whereas mean basal percent of fat body mass (FBM) was 29.85 +/- 2.87, and decreased significantly at 6 (27.2% +/- 3.9%; p = 0.02) and 12 (26.1% +/- 3.9%; p = 0.002) months postpartum, changes in lean body mass (LBM) were not significant. In conclusion, lactating adolescents maintained LBM, whereas weight, FBM and BMI decreased markedly from 3 months postpartum.     

Kinetic aspects of dye addition in continuous integration dyeing

Following on from previous papers by the authors concerning the integration dyeing method, this paper studies the kinetic behaviour of the dye when integrated continuously in an isothermal solution over a period of 60 min. The dyeing systems selected were acid dyes on wool and cationic dyes on Leacril 16 fibre. Curves of the kinetics of dye absorption by the fibres were similar to those of the addition of dye to the dyebath. At low exhaustion the systems followed an Arrhenius law, contrary to the behaviour at high exhaustion where the dye absorption was almost independent from temperature. A mathematical method is described to assess the total amount of the dye to be added in relation with the desired temperature and exhaustion.     

13C nuclear magnetic resonance monitoring of free fatty acid release after fish thermal processing

¹³C Nuclear magnetic resonance spectroscopy was applied to the study of lipid hydrolysis occurring during industrial canning of tuna (Thunnus alalunga). An increase in the free fatty acid (FFA) level was observed after cooking and sterilization, and a different FFA pattern was found when storage of the frozen raw material and thermal steps (cooking and can sterilization) were compared. Lipolysis in raw muscle occurs preferentially in thesn-1 andsn-3 acyl positions of triacylglycerols, with a consequent cleavage of saturated and monounsaturated fatty acids. After thermal processing, an increase of docosahexaenoic acid (DHA) was found in the FFA fraction, as well as a relative decrease of the peak intensity of DHA in thesn-2 position of triacylglycerols. This finding indicates a different mechanism of FFA release during the frozen storage and thermal processing of raw fish.     

Learning collaboration strategies for committees of learning agents

A main issue in cooperation in multi-agent systems is how an agent decides in which situations is better to cooperate with other agents, and with which agents does the agent cooperate. Specifically in this paper we focus on multi-agent systems composed of learning agents, where the goal of the agents is to achieve a high accuracy on predicting the correct solution of the problems they encounter. For that purpose, when encountering a new problem each agent has to decide whether to solve it individually or to ask other agents for collaboration. We will see that learning agents can collaborate forming committees in order to improve performance. Moreover, in this paper we will present a proactive learning approach that will allow the agents to learn when to convene a committee and with which agents to invite to join the committee. Our experiments show that learning results in smaller committees while maintaining (and sometimes improving) the problem solving accuracy than forming committees composed of all agents.