Optimization of copper chloride based catalysts for ethylene oxyhydrochlorination

In this work we have studied the effect of adding Li, Na or K chloride to CuCl₂ supported on α-Al₂O₃, on its catalytic activity for the oxyhydrochlorination of ethylene to dichloroethane in a fixed bed reactor, at 573 K and atmospheric pressure. Both NaCl and KCl show a strong promoting effect. For the case of KCl, this effect has been further examined for a wide range of concentrations and a fixed amount of CuCl₂ supported on either α-Al₂O₃, γ-Al₂O₃ or SiO₂ gel. The catalytic and thermogravimetric results obtained indicate that KCl is very effective on the overall rate, even at low concentrations, particularly because it increases considerably the rate of reoxidation of the reduced form of the catalyst. In the case of the γ-Al₂O₃ series, the promoting effect is only moderate. Ethylene oxyhydrochlorination data for a series of α-Al₂O₃ supported catalysts containing a constant K⁺/Cu²⁺ atomic ratio and increasing total amount of KCl + CuCl₂ are shown. The activity curve shows a maximum for about 18 wt % total active phase. Finally, the influence of Ce, Nd and Pr chlorides on the activity of CuCl₂ + KCl supported on α-Al₂O₃ is also shown. In the case of Pr, the entire range of Pr³⁺/Cu²⁺ atomic ratios has been examined. The results indicate that the rare earths, especially praseodymium, also have an additional positive effect on activity.     

Flame retardant epoxy resins based on diglycidyl ether of isobutyl bis(hydroxypropyl)phosphine oxide

Phosphorous‐containing epoxy resins were prepared from diglycidyl ether of isobutyl bis(hydroxypropyl)phosphine oxide (IHPOGly) and diglycidyl ether of bisphenol A (DGEBA) by crosslinking with 2,4‐diaminotoluene. Several IHPOGly/DGEBA molar ratios were used to obtain materials with different phosphorous content. Thermal, dynamomechanical, and flame retardant properties were evaluated and related with the phosphorous content. The weight loss rate of phosphorous‐containing resins is lower than that of the phosphorous‐free resin for the thermoxidative degradation. Char yields under nitrogen do not show significant differences among the phosphorous‐containing resins and the phosphorous‐free resin, while under air char yields increase with the phosphorous content. The presence of phosphorous increases the limiting oxygen index (LOI) values even when the phosphorous content is low, and no significant differences with the phosphorous content are observed. V‐0 materials were obtained when the resins were tested for ignition resistance with the UL‐94 test. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1367–1373, 2006     

Variable neighborhood search to solve the generalized orienteering problem

This paper presents a variable neighborhood search (VNS) algorithm to solve the extension of the orienteering problem known as the generalized orienteering problem (GOP). Our algorithm aims to use a reduced number of neighborhoods without compromising the quality of the results. This reduced number of neighborhoods, together with the precalculation of scores associated with points of interest, allows us, in most cases, to outperform all previous metaheuristics proposed for this problem. This is the first time a VNS is being applied to the GOP, and it provides promising computational results. In particular, in the case studies considered in the paper, we were able to find 35 new best solutions, all of which were found using a shorter computational time. Furthermore, the information regarding other best‐known solutions provided in the literature has also been improved, with corrections to some previously published errors regarding scores and distances. In addition, the benchmark has been extended with the incorporation of new case studies based on real data from three of the most popular tourist cities in Spain.     

Markov games with unknown random state‐actions‐dependent discount factors: Empirical estimation

The work deals with a class of discrete‐time zero‐sum Markov games under a discounted optimality criterion with random state‐action‐dependent discount factors of the form , where x_n,a_n,b_n, and ξ_n+1 are the state, the actions of players, and a random disturbance at time n, respectively, taking values in Borel spaces. The one‐stage payoff is assumed to be possibly unbounded. In addition, the process {ξ_n} is formed by observable, independent, and identically distributed random variables with common distribution θ, which is unknown to players. By using the empirical distribution to estimate θ, we introduce a procedure to approximate the value V^? of the game; such a procedure yields construction schemes of stationary optimal strategies and asymptotically optimal Markov strategies.     

Using the Big Data generated by the Smart Home to improve energy efficiency management

A Smart Home is able to generate energy-related values such as electricity consumption, temperature, or luminosity without higher infrastructure requirements. The main aim of this research is to extract information from that raw data that could contribute to improving the energy efficiency management. This paper presents a system which, using different Machine Learning approaches to learn about the users’ consumption habits, is able to generate collaborative recommendations and consumption predictions that help the user to consume better, which will in turn improve the demand curve. Moreover, from consumption values, the system learns to identify devices, enabling the demand to be anticipated. Taking into account the fact that the amount of energy data is increasing in real-time, the use of Big Data techniques will be the key to handling all the operations and one of the more innovative features of the system.     

Lithium aluminosilicate reinforced with carbon nanofiber and alumina for controlled-thermal-expansion materials

Materials with a very low or tailored thermal expansion have many applications ranging from cookware to the aerospace industry. Among others, lithium aluminosilicates (LAS) are the most studied family with low and negative thermal expansion coefficients. However, LAS materials are electrical insulators and have poor mechanical properties. Nanocomposites using LAS as a matrix are promising in many applications where special properties are achieved by the addition of one or two more phases. The main scope of this work is to study the sinterability of carbon nanofiber (CNFs)/LAS and CNFs/alumina/LAS nanocomposites, and to adjust the ratio among components for obtaining a near-zero or tailored thermal expansion. Spark plasma sintering of nanocomposites, consisting of commercial CNFs and alumina powders and an ad hoc synthesized β-eucryptite phase, is proposed as a solution to improving mechanical and electrical properties compared with the LAS ceramics obtained under the same conditions. X-ray diffraction results on phase compositions and microstructure are discussed together with dilatometry data obtained in a wide temperature range (−150 to 450 °C). The use of a ceramic LAS phase makes it possible to design a nanocomposite with a very low or tailored thermal expansion coefficient and exceptional electrical and mechanical properties.     

CFD studies on the phenomena around counter-current flow limitations of gas/liquid two-phase flow in a model of a PWR hot leg

In order to improve the understanding of counter-current two-phase flow and to validate new physical models, CFD simulations of a 1/3rd scale model of the hot leg of a German Konvoi pressurized water reactor (PWR) with rectangular cross section were performed. Selected counter-current flow limitation (CCFL) experiments conducted at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) were calculated with ANSYS CFX using the multi-fluid Euler–Euler modelling approach. The transient calculations were carried out using a gas/liquid inhomogeneous multiphase flow model coupled with a shear stress transport (SST) turbulence model.In the simulation, the drag law was approached by a newly developed correlation of the drag coefficient (Höhne and Vallée, 2010) in the Algebraic Interfacial Area Density (AIAD) model. The model can distinguish the bubbles, droplets and the free surface using the local liquid phase volume fraction value. A comparison with the high-speed video observations shows a good qualitative agreement. The results indicate also a quantitative agreement between calculations and experimental data for the CCFL characteristics and the water level inside the hot leg channel.     

Radiation protection issues for laser-based accelerators

Radiation particles, besides their application to fundamental research, are widely applied in all fields of science (medicine, material science, chemistry, etc.). Up to today the radiations were produced by radiation sources such as accelerators, X-ray tubes, radioactive sources with the well-known problems of costs, parameters and safety. For the last few years, following the development of lasers able to focus ultra-short high-intensity pulses onto targets, the generation of ionising radiation by intense lasers has become possible. The paper will focus on some radiological protection aspects around the Frascati Laser for Acceleration and Multidisciplinary Experiments, 300 TW laser being commissioned at National Laboratories of Frascati.