Integrated Computational Life Cycle Engineering — Application to the case of electric vehicles

Modelling and analysing lifecycle environmental impacts of product systems demands often specialized knowledge and is time-demanding. Product systems are typically defined by complex technical foreground systems and immersed in highly diverse contexts and background systems. Available software tools fail to streamline the modelling and analysis of this complexity, leading to extensive iterations or rough simplifications. The approach introduced in this paper supports the modelling of complex systems and their interactions with diverse backgrounds. This enables developing flexible and comprehensive environmental assessment tools. The applicability and advantages of the approach developed is demonstrated through its application for the environmental assessment of electric vehicles.     

Efficient code development for improving execution performance in high-performance computing centers

The Journal of Supercomputing - Thanks to high-performance computing (HPC), it is possible to solve all kinds of highly complex projects from multiple scientific disciplines that require...     

Unconditional performance of the X¯ chart: Comparison among five standard deviation estimators

To design the $\overline{X}$ control chart, the in-control process mean and standard deviation must be estimated from historical samples, negatively affecting the chart's performance. The grand mean of a sample is the well-established estimator for the process mean. However, regarding the standard deviation, the chart's user has at least five different estimators available in the literature to choose from. In this paper, using intensive simulations, we study and compare the performance of the $\overline{X}$ chart (under normality assumption and three-sigma limits) among the most five used standard deviation estimators. The unconditional in-control run length (RL₀) is the most commonly used performance measure of a control chart, and many authors base their comparisons on the expectation of the RL₀ or on the mean square error of the estimators. In contrast, we based our comparison on the proportions of the RL₀ concentrated at some intervals that are usually considered undesired by the practitioner due to the high incidence of false alarms during the process monitoring (e.g., RL₀ between 1 and 200), occurring earlier than expected when compared with known parameter situations. From our results, all the studied standard deviation estimators generate similar performances. However, even with this similarity, we showed that one of the most recommended standard deviation estimators in the literature in control charts with estimated parameters may be the most inappropriate choice based on the undesired RL₀ proportions.     

Improving thermo-responsive hydrogel films by gamma rays and loading of Cu and Ag nanoparticles

This paper presents two modified copolymeric hydrogel films with thermo-responsiveness. The final films are hydrogels containing N-isopropylacrylamide, N-N-dimethylacrylamide, methyl methacrylate, and ethoxyethyl methacrylate. The incorporation of Ag and Cu in the smart hydrogel films endowed them with specific properties that could be useful in developing biological sensors, smart membranes, or flexible electronic components, which are proper for design and improvement on technology and biomedical applications. The films were synthesized in solution by gamma radiation at a dose rate of 10 kGy h⁻¹, and an absorbed dose of 50 kGy. The characterization was realized by different spectroscopic and microscopic techniques as FTIR-ATR, atomic force microscopy, SEM–EDX, TGA, and DSC. The hydrogel films were grafted with glycidyl methacrylate showing high resistance, biocompatibility, adequate adaptability, flexibility, in addition to the capacity of metal doping with silver and copper.     

Hybrid palladium-ceria nanorod electrocatalysts applications in oxygen reduction and ethanol oxidation reactions in alkaline media

Fossil fuel alternatives are being increasingly studied, and alkaline direct ethanol fuel cells (ADEFC) have acquired importance, as to ethanol is a renewable fuel. In this context, the aims of the present study were to synthesize, characterize and evaluate electrocatalytic activity in oxygen reduction reaction (ORR) and ethanol oxidation reaction (EOR) using hybrid electrocatalysts based on Pd nanoparticles and CeO₂ nanorods supported on carbon black for application in ADEFC. The highest OCV, maximum current and power densities obtained using Pd₁₅(CeO₂ NR)₁₀(Vn)₇₅ as the cathode and Pd₁₀(CeO₂ NR)₂₀(Vn)₇₀ as the anode were 1270 mV, 190 mA cm^?2 and 65 mW cm^?2, respectively. These interesting results are justified by the highest I_D/I_G ratio and ECSA, which suggest a high number of oxygenated species, defects and vacancies in these electrocatalysts and by the synergistic effect between CeO₂ NR and Pd nanoparticles. Therefore, these hybrid electrocatalysts are promising for ADEFC applications.     

Phase evolution in plasma sprayed Nb2O5 coatings

Nb₂O₅ polymorphism and defect chemistry depend on the temperature, pressure, atmosphere composition and the initial crystallography. Plasma spray of Nb₂O₅ is a pathway to form coatings with in-situ metastable and nonstoichiometric phases, however so far unexplored. This study aimed to understand the phase evolution of plasma sprayed Nb₂O₅ coatings, and its effect on their morphology and properties. Phase evolution from H-Nb₂O₅ in the feedstock, to T-Nb₂O₅, TT-Nb₂O₅, N-Nb₂O₅, H-Nb₂O₅, Nb₁₂O₂₉ and NbO₂ in the coatings depends on the plasma Ar/H₂ ratio and its related enthalpy. The microstructure shows a layered distribution of nonstoichiometric phases at the splat boundaries and splat cores composed of T-Nb₂O₅ or TT-Nb₂O₅. The presence and distribution of these phases are related to the thermomechanical and electrical properties. The mechanisms driving the formation of these coatings are based on the Nb₂O₅ incongruent vaporization which promote retention of nonstoichiometric phases and the rapid solidification of metastable phases.     

An Algorithm for Pseudocompound Delumping and Lumping into Homologous Groups

An algorithm for pseudocompound delumping and lumping into homologous groups is developed. This algorithm is useful for modeling refineries when using commercial simulators and detailed reactor models. Generally, commercial simulators represent petroleum fractions using pseudocompounds; however, reactor models and their kinetics are based on known compounds. This algorithm delumps the pseudocompounds into homologous groups that are represented by model compounds, which are then used by a detailed reactor model. After the reaction, the outlet stream is lumped again to pseudocompounds that are used in the remaining operations of the commercial simulator. The lumping operations are based on mass balance principles and fundamental properties of the hydrocarbon mixture. This algorithm is applied to the modeling of a hydrotreatment unit that belongs to the Mexican System of Refineries which uses a detailed three phase trickle bed reactor. The problem is to delump and lump the pseudocompounds, which represent light gas oil, into paraffins, naphthenes, and mono and polyaromatics. Results show a good agreement with industrial data.     

Determination of the in vitro susceptibility of 220 Mycobacterium fortuitum isolates to ten antimicrobial agents

The authors investigated the in vitro susceptibility to antimicrobial agents of 220 Mycobacterium fortuitum isolates originating from clinical samples (14) of patients attending the Hospital Universitario de Canarias and Hospital del Tórax, and from environmental sources (206): 3 from sea water, 10 from the water supply and 193 from sewage. The Minimum Inhibitory Concentration (MIC) was calculated using the broth microdilution method with Mueller-Hinton Broth without supplement. Amikacin was the most efficacious antimicrobial agent against all the isolates of M. fortuitum with an MIC which was considerably lower than its critical concentration. The good results achieved with amikacin in vitro are confirmed by those obtained in vivo, with patients infected with M. fortuitum. No significant difference was found in the efficacy of amikacin and ofloxacin against all the isolates assayed.