Escola Politècnica Superior d'Alcoi

In this paper we present the results of new experiments on ion irradiation of water ice performed on thin films to study the synthesis of the hydrogen peroxide molecule and discuss the possibility of detecting it in icy mantles on interstellar grains. The used experimental technique has been in situ infrared spectroscopy. We have irradiated thin films (i.e. the ice thickness was smaller than the penetration depth of the used ion) with three different ions, namely 200 keV of H+ and He+ and 400 keV of Ar++. The experiments were carried out at temperatures of 16 and 77 K. We have found that hydrogen peroxide is produced by all of the different ions at both temperatures. The detection of such a molecule has been possible from the study of its infrared feature centered at about 2850 cm-1 (3.5 μm). The obtained results also show that the produced H2O2/H2O(%) ratio is greater for the heaviest ion (~6% for the case of Ar++) and that H+ is the ion that produces the smallest quantity (~1%). These upper limits in the production of hydrogen peroxide constrain the quantity of H2O2 that can be formed after bombardment by cosmic particles on icy mantles of grains in the interstellar medium.

An ongoing stream in financial analysis proposes mean‐semivariance in place of mean‐variance as an alternative approach to portfolio selection, since segments of investors are more averse to returns below the mean value than to deviations above and below the mean value. Accordingly, this paper searches for a stochastic programming model in which the portfolio semivariance is the objective function to be minimized subject to standard parametric constraints, which leads to the mean‐semivariance efficient frontier. The proposed model relies on an empirically tested basis, say, portfolio diversification and the empirical validity of Sharpe's beta regression equation relating each asset return to the market. From this basis, the portfolio semivariance matrix form is strictly mathematically derived, thus an operational quadratic objective function is obtained without resorting to heuristics. Ease of computation is highlighted by a numerical example, which allows one to compare the results from the proposed mean‐semivariance approach with those derived from the traditional mean‐variance model.

As a contribution to portfolio selection analysis, we develop a compromise programming approach to the investor's utility optimum on the Madrid Online Market. This approach derives from linkages between utility functions under incomplete information, Yu's compromise set, and certain biased sets of portfolios on the efficient frontier. These linkages rely on recent theorems in multi–criteria literature, which allow us to approximate the investor's utility optimum between bounds which are determined either by linear programming models or graphic techniques. Returns on 104 stocks are computed from capital gains and cash–flows, including dividends and rights offerings, over the period 1992–1997. The first step consists in normalizing the mean–variance efficient frontier, which is defined in terms of two indexes, profitability and safety. In the second step, interactive dialogues to elicit the investor's preferences for profitability and safety are described. In the third step, the utility optimum for each particular investor who pursues a buy–&–hold policy is bounded on the efficient frontier. From this step, a number of portfolios close to the investor's utility optimum are obtained. In the fourth step, compromise programming is used again to select one ‘satisficing’ portfolio from the set already bounded for each investor. This step is new with respect to previous papers in which compromise/utility models are employed. Computing processes are detailed in tables and figures which also display the numerical results. Extensions to active management policies are suggested.

Using relatively approximated methods, physisorption of molecular hydrogen on single-walled carbon nanotubes (SWCNTs) as a mechanism to develop hydrogen storage systems has been only partially investigated in literature. Here, we use ab initio molecular-orbital theory, at benchmark quality level, to provide a more complete description about the mentioned mechanism. Physisorption inside and outside achiral-armchair and zigzag-SWCNTs, in the range of diameters from about 6 A-chiral vectors (5,5) and (8,0)-to more than 30 A-chiral vectors (30,30) and (40,0)-was examined. Perpendicular, longitudinal, and transversal configurations, with the hydrogen molecule centered on an aromatic ring, were taken into account. SWCNTs were modeled as curved coronenelike (C24H12) graphene sheets. Local modeling strategies, using more complete basis sets for the adsorbate and for the nearest atoms to the adsorbate than for the lion's share of the substrate, at the Moller-Plesset second-order correlation level, were selected for numerical treatment. Basis-set superposition errors were corrected by means of the counterpoise method of Bois and Bernardi. It was found that physisorption of molecular hydrogen on SWCNTs would depend mainly on the diameter being virtually independent of the chirality. Lowest physisorption energies, up to 20% less than that on planar graphene, would be reached outside nanotubes in the range of diameters of 6-10 A. For hydrogen storage purposes, highest physisorption energies, up to 40% greater than that on planar graphene, but not more, would be reached inside nanotubes in the relatively narrow range of diameters of 10-20 A. Finally, for diameters from 20 A onwards physisorption of molecular hydrogen on SWCNTs would be in the range of +/-10% of that on planar graphene. To our knowledge, this would be the most complete and realistic theoretical investigation of the target physisorption mechanism to date.

We deal with the buy-and-hold choice of fund portfolios by considering multiple states of nature (future market scenarios). These states are associated with goals in the sense that the investor pursues to optimize a classical financial objective function as much as possible whatever the states of nature. As this classical function is very cumbersome for handling, a satisficing proxy is used. This proxy is Stochastic Goal Programming (SGP), a recent uncertainty multiobjective model characterized as follows: (a) it relies on Von Neumann and Morgenstern's-Arrow's Eu(R) principles in a framework of bounded rationality; (b) its moderate computational burden allows easy application to large scale problems. In SGP, the variability matrices of goals are aggregated by Arrow's risk aversion coefficients. Concerning the case study, the states of nature are Eurostoxx market index scenarios defined from time series. As an opportunity set of assets, we use a large set of funds managed by an international consultancy. Potential returns on each fund are related to each scenario by using betas. As eliciting betas can be made from different samples leading to different results, we use fuzzy logic to decide among these different results in a framework of imprecision/uncertainty. Our approach is new as it combines SGP and fuzzy tools.

ABSTRACT We present a spectroscopic study of methane–ethane ice mixtures. We have grown CH 4 :C 2 H 6 mixtures with ratios 3:1, 1:1, and 1:3 at 18 and 30 K, plus pure methane and ethane ices, and have studied them in the near-infrared (NIR) and mid-infrared (MIR) ranges. We have determined densities of all species mentioned above. For amorphous ethane grown at 18 and 30 K we have obtained a density of 0.41 and 0.54 g cm −3 , respectively, lower than a previous measurement of the density of the crystalline species, 0.719 g cm −3 . As far as we know this is the first determination of the density of amorphous ethane ice. We have measured band shifts of the main NIR methane and ethane features in the mixtures with respect to the corresponding values in the pure ices. We have estimated band strengths of these bands in the NIR and MIR ranges. In general, intensity decay in methane modes was detected in the mixtures, whereas for ethane no clear tendency was observed. Optical constants of the mixtures at 30 and 18 K have also been evaluated. These values can be used to trace the presence of these species in the surface of trans-Neptunian objects. Furthermore, we have carried out a theoretical calculation of these ice mixtures. Simulation cells for the amorphous solids have been constructed using a Metropolis Monte Carlo procedure. Relaxation of the cells and prediction of infrared spectra have been carried out at density functional theory level.

The suitable choice of a benchmark portfolio is a critical problem prior to using the information ratio, as the performance ranking of funds depends on this choice. In this paper, a method to optimize benchmark selection taking account of the investor's preferences is proposed and applied to a case study of performance for 29 market indicators on stock exchanges throughout the world. The method that relies on recent results in optimization theory requires defining the opportunity set to select the benchmarks, this set being Footsie in the case study. The computational process and numerical results are presented through tables and figures, the accuracy of the method being also numerically tested.

The characterisation of an elastomer prepared from ground tyre rubber has been carried out in terms of both morphological and granulometric studies. A large number of waste tyres are discarded every year. These residuals represent a crucial environmental problem. Thus, the redemption and recycling of waste tyres constitute a research field of great interest nowadays. In this connection, the study of the size distribution of particulates is of the utmost importance. In the present work, the morphological study of a ground tyre rubber previously prepared has been carried out. The use of SEM techniques indicates that the powder is not completely uniform. The granulometric study of the powder was carried out by applying the Rosin–Rammler and Gates–Gaudin–Schuhmann models. The particle size distribution of the sample here studied satisfactorily fits the Rosin–Rammler model, especially for mesh sizes above 0·250 mm. According to the results of this study, a homogeneous behaviour of the sinterised product during the thermocompression process is expected.

Textile manufacturing companies are interested in selecting the best fibers and fabrics from their marketing properties and production characteristics. Many firms often face scenarios where the relative significance of each fabric characteristic can be hardly measured, and then the managers' decisions on fabric choice are made under uncertainty. To help determine a ranking of products intended for selection, an uncertainty model for cautious managers is proposed. A case study is developed dealing with seven fabric properties (tensile strength, shrinkage, pilling, density, fastness to light, fabric weight, and flame retardance) and four production characteristics (market price of materials, period of delivery, density, and required manufacturing processes), the opportunity set consisting of 132 fabrics.

An important issue in any academic degree is to develop a high level of vertical/horizontal coordination between the different subjects taught along the four courses. This activity takes into account the coordination of the contents and methodologies that the teachers teach and the students acquire, the timing when the students learn them and the homework/exams that they do. As a result, both teachers and students gain an overall view of the degree and the teaching-learning process improves.

Traditional accounting is based on financial indicators; the balanced scorecard divides management into different perspectives, some authors suggesting no more than four or five for each company. To measure each perspective some indicators should be defined. The aim of this work is to propose some indicators that fit each perspective for some textile companies that work in weaving fabrics. These indicators are specific for them, and very useful to help companies' management in the current circumstances of globalisation. Businesses must strive to increase their competitive advantage, which will increasingly depend on the parameters of innovation, development of new products, versatility, quality, costs, etc., and indicators will measure it.

A proposal to achieve a dynamic analysis of decision systems in enterprises is presented. Starting from the Decision System GRAI modeling (G. Doumeingts, 1984), the consideration of the use of the human resources in decision making and the characterization of the decision system by means of parameters of quality is proposed. The objective of the Dynamic GRAI Model is its simulation for the analysis of the dynamic behavior of the system regarding its temporary parameters (horizons and periods of planning) and the pursuit of the evolution of the total quality of the decision system. An information system for the storage of the necessary information (DGRAIS) and a simulator (DGRAISIM) are presented, unified in a re-design tool (DGRAI).

[EN] The bullwhip effect refers to the scenario in which orders to suppliers tend to present larger fluctuations than sales to buyers, and the resulting distortion increasingly amplifies upstream in a supply chain.We propose a transformation of the known formulation by Chen et al. (2000) to calculate the bullwhip effect in a supply chain for the purpose of being easily applied with spreadsheets without usingVBA macros.We present this formulation modeled by Ms Excel using a numerical example.

El efecto bullwhip se refiere al escenario en el que los pedidos al proveedor tienden a presentar mayores fluctuaciones que las ventas a los compradores, y la distorsión resultante se amplifica crecientemente aguas arriba en una cadena de suministro. Se propone una modificación de la conocida fórmula de Chen et al. (2000) para calcular el efecto bullwhip en una cadena de suministro con el objetivo de que sea aplicada fácilmente a través de hojas de cálculo sin usar macros VBA. Se presenta esta formulación con Ms Excel© usando un ejemplo numérico.

If we analyse some of the specific skills of Chemical Engineering degree, and it would not be very different in other disciplines of engineering, the verbs design, analyse or simulate stand out above all. In essence, calculating is an intrinsic activity for the engineer and, therefore, for engineering students.

Establishing collaborative relationships among the enterprises belonging to a network encourages them to jointly work in order to achieve common objectives that cannot be achieved if they work in isolation. The participation in collaborative networks involves enterprises to define their own objectives and subsequently, to identify the strategies whose activation promotes positive influences in all the objectives defined by all the networked partners. Nevertheless, in real networks, contradictions among the objectives defined by the enterprises may appear due to the heterogeneity that characterises its members. Accordingly, a model that supports the identification of compatible strategies is developed, based on the system dynamics method. The model takes into account that the strategies designed in one enterprise should promote the achievement of the objectives defined by other enterprises of the network. The identification of compatible strategies will allow the attainment of the objectives and consequently increase the levels of the network performance.

This paper proposes an operational approach (based on marginal actions) to specify multiattribute utility functions, which allows us to easily rank alternatives from criteria relevant to the manager, the customer or any other decision maker without heuristic remedies, imprecision or loss of generality. Marginal actions are fictitious alternatives which play a key role in preference analyses as a tool recently introduced for the ranking treatment of decision tables. As usual in multi-attribute value theory, preferential independence is assumed. A practical large-scale case in the textile industry to rank commercial fabrics -characterized by seven quality factors- is developed.

A mis compaeros del Grupo de Procesos de Oxidacin

Este libro presenta las experiencias y los resultados en el ámbito de la innovación y mejora educativa que se han llevado a cabo en la Escuela Politécnica Superior de Alcoy (EPSA) de la Universitat Politècnica de València (UPV) a lo largo de los cursos académicos 2014-2018.Las innovaciones y mejoras educativas abordadas se han centrado, principalmente,en:las metodologías activas en los procesos de enseñanza-aprendizaje, tales como, la gamificación en el aula y la docencia inversa; el aprendizaje basado en proyectos; la adquisición de competencias transversales y los procesos de evaluación. Este libro pretende servir de ejemplo para otras propuestas de innovación docente además de mostrar la fuerte implicación tanto de la EPSA como de la UPV en la mejora continua de la docencia impartida.

Information about the paper titled "ASSESSMENT OF STUDENTS IN THE USE OF MATLAB GUIDE TEMPLATES FOR SOLVING MATERIAL BALANCES. A TEACHING EXPERIENCE IN CHEMICAL ENGINEERING DEGREE" at IATED Digital Library