252 research outputs found
Implementation of intelligent manufacturing algorithms in agile architectures for production: world models for systems incorporating binary and continuous variables
Agile Manufacturing, Intelligent systems, AlgorithmsBuilding in previous works of the authors, the present paper focuses on the extension of the
Algorithms described for the specific case study of binary systems (systems in which each variable
can take one out of two values), to cases that also incorporate continuous variables (those which can
take any continuous value within a range). This extension of the Algorithms makes possible the
incorporation of new possibilities and functionalities for the treatment of the information received by
the sensors of the manufacturing systems and in particular reduce the number of variables in which to
monitor the states and costs of execution. The Construction of World Models based on this logical
theory -that incorporates the knowledge derived from the results of a set of experiments conducted by
the system utilizing a set of different algorithms- is applicable to a wide range of production systems
topologies, which is also visited in the present work.Postprint (published version
Acylation of Chiral Alcohols: A Simple Procedure for Chiral GC Analysis
The use of iodine as a catalyst and either acetic or trifluoroacetic acid as a derivatizing reagent for determining the enantiomeric composition of acyclic and cyclic aliphatic chiral alcohols was investigated. Optimal conditions were selected according to the molar ratio of alcohol to acid, the reaction time, and the reaction temperature. Afterwards, chiral stability of chiral carbons was studied. Although no isomerization was observed when acetic acid was used, partial isomerization was detected with the trifluoroacetic acid. A series of chiral alcohols of a widely varying structural type were then derivatized with acetic acid using the optimal conditions. The resolution of the enantiomeric esters and the free chiral alcohols was measured using a capillary gas chromatograph equipped with a CP Chirasil-DEX CB column. The best resolutions were obtained with 2-pentyl acetates (α = 3.00) and 2-hexyl acetates (α = 1.95). This method provides a very simple and efficient experimental workup procedure for analyzing chiral alcohols by chiral-phase GC
Algorithms for Spectral Analysis of Irregularly Sampled Time Series
In this paper, we present a spectral analysis method based upon least square approximation. Our method deals with nonuniform sampling. It provides meaningful phase information that varies in a predictable way as the samples are shifted in time. We compare least square approximations of real and complex series, analyze their properties for sample count towards infinity as well as estimator behaviour, and show the equivalence to the discrete Fourier transform applied onto uniformly sampled data as a special case. We propose a way to deal with the undesirable side effects of nonuniform sampling in the presence of constant offsets. By using weighted least square approximation, we introduce an analogue to the Morlet wavelet transform for nonuniformly sampled data. Asymptotically fast divide-and-conquer schemes for the computation of the variants of the proposed method are presented. The usefulness is demonstrated in some relevant applications.
Preparation and uses of chlorinated glycerol derivatives
Crude glycerol (C3H8O3) is a major by-product of biodiesel production from vegetable oils and animal fats. The increased biodiesel production in the last two decades has forced glycerol production up and prices down. However, crude glycerol from biodiesel production is not of adequate purity for industrial uses, including food, cosmetics and pharmaceuticals. The purification process of crude glycerol to reach the quality standards required by industry is expensive and dificult. Novel uses for crude glycerol can reduce the price of biodiesel and make it an economical alternative to diesel. Moreover, novel uses may improve environmental impact, since crude glycerol disposal is expensive and dificult. Glycerol is a versatile molecule with many potential applications in fermentation processes and synthetic chemistry. It serves as a glucose substitute in microbial growth media and as a precursor in the synthesis of a number of commercial intermediates or fine chemicals. Chlorinated derivatives of glycerol are an important class of such chemicals. The main focus of this review is the conversion of glycerol to chlorinated derivatives, such as epichlorohydrin and chlorohydrins, and their further use in the synthesis of additional downstream products. Downstream products include non-cyclic compounds with allyl, nitrile, azide and other functional groups, as well as oxazolidinones and triazoles, which are cyclic compounds derived from ephichlorohydrin and chlorohydrins. The polymers and ionic liquids, which use glycerol as an initial building block, are highlighted, as well.This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (grants: MINECO/FEDER CTQ2015-70982-C3-1-R) and by the Generalitat de Catalunya, Grant 2017 SGR 828, to the Agricultural Biotechnology and Bioeconomy Unit (ABBU)
Synthesis and Thermophysical Characterization of Fatty Amides for Thermal Energy Storage
Nine monoamides were synthesized from carboxylic acids (C8-C18) and crude glycerol. The final monoamides were the result of a rearrangement of the acyl chain during the final hydrogenation process. The purity of the final compounds was determined by spectroscopic and mass spectrometry (MS) techniques. The thermophysical properties of solid monoamides were investigated to determine their capability to act as phase change materials (PCM) in thermal energy storage. Thermophysical properties were determined with a di erential scanning calorimeter (DSC). The melting temperatures of the analyzed material ranged from 62.2 C to 116.4 C. The analyzed enthalpy of these monoamides ranged from 25.8 kJ/kg to 149.7 kJ/kg. Enthalpy values are analyzed considering the carbon chain and the formation of hydrogen bonds.This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (grants: MINECO/FEDER CTQ2015-70982-C3-1-R and MINECO/FEDER RTI2018-093849-B-C31). This work is partially supported by ICREA under the ICREA Academia programme. Acknowledgments: R.C.-G. and L.F.C. would like to thank the Catalan Government for the quality accreditation given to their research groups (grants 2017 SGR 828 and GREiA 2017 SGR 1537, respectively). DBA and GREiA are certified agent TECNIO in the category of technology developers from the Government of Catalonia
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