A bill of materials-based approach for end-of-life decision making in design for the environment

Re-use, recycling or remanufacturing of products and components are good alternatives for reducing the environmental problems resulting from the huge amounts of waste currently arriving at landfills. A new approach is proposed in this paper for enhancing these alternatives from the earliest stages of product design. Given the product structure (obtained from its bill of materials (BOM)) and the joining and geometrical relationships among the components (obtained from the three-dimensional, computer-aided design representation), a model is proposed that will determine the EOL (EOL) strategy, i.e. the depth of disassembly inside the structure and the final end (re-use, recycle, remanufacture or disposal) for each disassembled part leading to the highest profit. A scatter search (SS) metaheuristic is used to determine the disassembly cost at each level of the BOM. The model presents a number of major improvements with respect to previous research. It addresses the problems of simultaneously determining both the best EOL strategy and the disassembly sequence, as well as allowing removal of components not only over the two or three Cartesian axes and affording the possibility of modifying the encountered strategy in a further step so as to fulfil other business criteria (such as disassembly time, resources availability or maximum waste generation rate).     

Evaluation of decay photocurrent measurements in dye‐sensitized solar cells: Application to laser beam‐induced current technique

The use of the laser beam‐induced current (LBIC) technique in photovoltaic devices is widespread, but its use in photoelectrochemical cells, such as dye‐sensitized solar cells (DSSCs), is limited due to the configuration of these devices. The main reason is the very slow response time of DSSCs in the decay process, and therefore LBIC scans take too long to perform. We have designed a procedure published in the literature to correct the photocurrent values obtained by the LBIC technique, based on an algorithm that uses a decreasing mono‐exponential model. This work presents a study of the decay measurements in DSSCs using several functions, in order to improve the algorithm designed. It concludes that functions such as a decreasing bi‐exponential or Becquerel function generate better fits to experimental data. Copyright © 2010 John Wiley & Sons, Ltd.     

Application of digital image correlation at the microscale in fiber-reinforced composites

Digital image correlation (DIC) is applied to analyzing the deformation mechanisms under transverse compression in a fiber-reinforced composite. To this end, compression tests in a direction perpendicular to the fibers were carried out inside a scanning electron microscope and secondary electron images obtained at different magnifications during the test. Optimum DIC parameters to resolve the displacement and strain field were computed from numerical simulations of a model composite and they were applied to micrographs obtained at different magnifications (250×, 2000×, and 6000×). It is shown that DIC of low-magnification micrographs was able to capture the long range fluctuations in strain due to the presence of matrix-rich and fiber-rich zones, responsible for the onset of damage. At higher magnification, the strain fields obtained with DIC qualitatively reproduce the non-homogeneous deformation pattern due to the presence of stiff fibers dispersed in a compliant matrix and provide accurate results of the average composite strain. However, comparison with finite element simulations revealed that DIC was not able to accurately capture the average strain in each phase.     

An optimization algorithm inspired by the States of Matter that improves the balance between exploration and exploitation

The ability of an Evolutionary Algorithm (EA) to find a global optimal solution depends on its capacity to find a good rate between exploitation of found-so-far elements and exploration of the search space. Inspired by natural phenomena, researchers have developed many successful evolutionary algorithms which, at original versions, define operators that mimic the way nature solves complex problems, with no actual consideration of the exploration-exploitation balance. In this paper, a novel nature-inspired algorithm called the States of Matter Search (SMS) is introduced. The SMS algorithm is based on the simulation of the states of matter phenomenon. In SMS, individuals emulate molecules which interact to each other by using evolutionary operations which are based on the physical principles of the thermal-energy motion mechanism. The algorithm is devised by considering each state of matter at one different exploration–exploitation ratio. The evolutionary process is divided into three phases which emulate the three states of matter: gas, liquid and solid. In each state, molecules (individuals) exhibit different movement capacities. Beginning from the gas state (pure exploration), the algorithm modifies the intensities of exploration and exploitation until the solid state (pure exploitation) is reached. As a result, the approach can substantially improve the balance between exploration–exploitation, yet preserving the good search capabilities of an evolutionary approach. To illustrate the proficiency and robustness of the proposed algorithm, it is compared to other well-known evolutionary methods including novel variants that incorporate diversity preservation schemes. The comparison examines several standard benchmark functions which are commonly considered within the EA field. Experimental results show that the proposed method achieves a good performance in comparison to its counterparts as a consequence of its better exploration–exploitation balance.     

Forecasting Financial Failure of Firms via Genetic Algorithms

Given a wide amount of possible ratios available for constructing a LOGIT model for forecasting bankruptcy, this paper provides a computational search methodology, only guided by data, for selecting the financial ratios employed in the model. This procedure is based on genetic algorithms which are used to explore the universe of models made available by all possible existing financial ratios (with very redundant information). This search process of the correct model is guided by the Schwarz information criterion. As an empirical illustration, the methodology is applied to forecasting the failure of firms in the Spanish building industry using annual public accounting information.     

Effect of Thermal Treatment and Storage Conditions on the Physical and Sensory Properties of Grapefruit Juice

Physical parameters, such as particle size distribution, flow behavior, density, turbidity, and color, were measured and sensory evaluation was carried out to compare the properties of freshly squeezed grapefruit juice with those of juice that has been pasteurized by microwave or by following a conventional heating method. Samples were either frozen-stored or refrigerated. In general, the physical parameters of grapefruit juice were significantly affected by heat treatment, especially in the case of the conventional process. However, from a sensory point of view, pasteurized samples were similar to fresh ones. When frozen, turbidity, particle size distribution, density, flow behavior, and color were stable throughout the studied period, regardless of the pasteurization treatment. During refrigerated storage, the turbidity, particle size distribution, and consistency index decrease. This occurs in a more pronounced way in the case of juice which has not been submitted to a heating treatment, probably due to residual pectin methyl esterase activity. Furthermore, the association between the carboxyl groups of pectin chains and Ca²⁺ could be responsible for both the subsequent increase in the turbidity of the juice and also the decrease in its density. Throughout the period under study, the smallest color change was experienced by microwave-pasteurized juice. For these reasons, and also due to the reduction in the process time, microwave treatment can be recommended as a method for the pasteurization of grapefruit juice.     

UHPLC as a suitable methodology for the analysis of carotenoids in food matrix

The purpose of this paper was to optimize an ultra-high performance liquid chromatography (UHPLC) method for the determination and quantification of carotenoid pigments in food products and compare it with a HPLC method in terms of resolution, selectivity, sensitivity, time and reagent saving. Less analysis times, solvent consumption and better peak resolution were achieved when the UHPLC methodology was used. Ultra-high performance liquid chromatography analysis was performed on Zorbax Eclipse Plus C18 column (2.1?×?50?mm; 1.8?μm) using a gradient solvent system and diode array detector. A total of seven carotenoids were separated and quantified in <8.5?min. For all components, the resolution was higher than 1.5 and LOD was below 1.0?μg?mL^?1. To determine the intraday and reproducibility, assays were conducted in 10 continuous days for method validation achieving recuperation rates ranging between 85 and 100?% and no significant differences among the results obtained in same and different days. The proposed methodology was applied for the determination of the carotenoid contents in honeybee pollen samples, pumpkin and nectarine flesh with satisfactory recovery.     

Geographical Authentication of Tequila According to its Mineral Content by Means of Support Vector Machines

The elemental profile of tequila samples from the three main production areas of the State of Jalisco, namely Amatitlan, Guadalajara, and Tequila, was used to carry out their geographical characterization. With this aim, the concentration of Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, S, Sr, and Zn was determined by inductively coupled plasma atomic emission spectroscopy. Principal component analysis was addressed to visualize data trends. The number of input variables was reduced by means of backward stepwise linear discriminant analysis and support vector machines were used to construct an adequate classification model. The best classification performance was obtained by a linear support vector machine model with 100% of prediction ability.     

The effect of neighbourhood on rodent communities: an example from Pampean agroecosystems

Pampean region agroecosystems are devoted to agricultural and farming activities, but in the crop field matrix there are relicts of remnant natural habitats. Poultry farms mainly harbour commensal species as house mice and rats, which are rarely present in surrounding habitats. We assessed if neighbourhood to poultry farms affect the presence of Mus musculus in crop fields and their borders, and if rodent community in poultry farms is influenced by the species present in surrounding crop fields and borders. We found that habitat had a significant effect on the abundance of M. musculus. This species showed higher abundance in poultry farms than in crop field borders. Calomys laucha was the unique native species that was captured in farm sheds. We found higher abundance of native species in crop field borders than in crop fields independent of the proximity to the poultry farms. We conclude that rodent communities in poultry farms are little influenced by the surroundings, and show a dominance of M. musculus independently of the presence of native rodent species in neighbour habitats. On the other hand, farms do not export M. musculus to surrounding habitats, and borders only function as corridors for dispersal among farms, while crop fields are rarely used.