New nonlinear approaches for the adjustment and updating of a SAM

We believe that any adjustment and updating process (AUP) should try to minimize the relative deviation of the new coefficients from the intial ones in a homogeneus way. This homogenity would mean that the magnitude of this relative deviation is similar among the elements of each row or column, therefor avoiding the concentration of the changes in particular cells of the SAM. In this work, we propose some new adjustment criteria in order to obtain a homogeneus relative adjustment of the sructural coefficients. We also test the usefulness of this proposal by comparing its results with the ones obtained with more standard approaches.nonlinear approaches SAM

Green process for adipic acid synthesis: oxidation by hydrogen peroxide in water micromelusions using Benzalkonium Chloride C12-14 surfactant

Adipic acid was synthesized by the oxidation of cyclohexene using 30% hydrogen peroxide in a microemulsion in the presence of sodium tungstate as catalyst. The proposed green process is environmentally friendly since catalyst and surfactant are recycled and pure adipic acid is produced in high yield (70% to 79%). Microemulsions are used as a “green solvent” and give a better contact between the phases. Alkyldimethylbenzylammonium chloride (C12-C14) was used as a surfactant for the generation of the microemulsion since it enables the use of harmful organic solvents and phase-transfer catalysts to be avoided. Optimised operating conditions (temperature, reaction time, separation process) have been defined and applied to evaluate the industrial practicability. The main interest of the present work is the easy recovery of pure adipic acid and the reuse of the reaction media (surfactant and catalyst). This shows promise for developing a future green industrial process that will enable greenhouse gas emissions (N2O), among others, to be reduced

Clean synthesis of adipic acid from cyclohexene in microemulsions with stearyl dimethyl benzyl ammonium chloride as surfactant: From the laboratory to bench scale

Adipic acid, HOOC(CH2)4COOH, is a white crystalline solid used primarily in the manufacture of nylon-6,6 polyamide. In industry, adipic acid is mainly produced by oxidation of cyclohexane with air and nitric acidfollowing a homogeneous two-step route. However, this process leads to the formation of nitrous oxide, a greenhouse gas that has to be decomposed. The aim of this study was the development of a clean technology at pilot scale in order to obtain and recover pure adipic acid, and the evaluation of its industrial practicability. Adipic acid was synthesized from cyclohexene and hydrogen peroxide in microemulsions with stearyl dimethyl benzyl ammonium chloride as surfactant. The non-polluting catalyst sodium tungstate, which contains no heavy metal, was used and the reaction conducted under mild conditions (85 C, 8 h). Yields of up to 81% were reached at the 0.14 L scale. However at the end of the reaction the catalyst and the surfactant must be separated and recycled for subsequent cycles. The reuse of the reaction media enabled the conversion to be increased up to 92% but a loss of surfactant and/or catalyst through the cycles progressively reduced the yields. Yields at the bench scale (1.4 L) increased during the two first cycles and then decreased to conversions of between 60% and 70%. Globally the yield is a little lower at bench scale. The results obtained show that the synthesis of adipic acid by a heterogeneous one-step oxidation of cyclohexene in the presence of hydrogen peroxide is an attractive route for developing a future green industrial process

Para una historia del relato de viaje hispánico (siglos XIX-XXI): noticia de una investigación en marcha

El autor del ensayo empieza destacando la extraordinaria presencia de la narrativa de viaje en la literatura occidental y sus conexiones con  otras disciplinas literarias y humanísticas (autobiografía, autoficción, etnografía, etc.). A continuación, tras abordar el estado de la cuestión en torno al relato factual de los dos últimos siglos, se refiere a sus propias investigaciones en este campo insistiendo en la metodología del análisis textual y en la función peculiar de elementos discursivos como la ficcionalidad, la descripción y la digresión. Finalmente, presenta una etapa capital en la historia de la narrativa viática española, la del siglo xix, ilustrándola con  las variantes del relato africanista, tan escasamente conocido hasta hoy

Inner-witnessing as a spatial everyday practice in Ann Petry’s The Street

Some scholars approach Ann Petry’s portrayal of Lutie Johnson’s fate in the hostile background of The Street (1946) through a naturalistic and deterministic lens: the protagonist, a single black mother, dreams of improving her lifestyle by reproducing a white uppermiddle class model. Given Lutie’s gender and race her dreams are, following this critical method, condemned as impossible. This approach to Petry’s novel does not take into account the deep geographical analysis that the author provides of Lutie’s struggle. Employing a spatial paradigm, this essay aims to offer an interpretation of Petry’s novel that challenges traditional geographic patterns evident in the street’s urban description. Such opposition reflects Katherine McKittrick’s approach to the definition of ‘Black women’s geographies’ as sites of struggle. Analyzing the novel’s employment of everyday practices, such as communicative expressions, and Kelly Oliver’s notion of inner-witnessing as one of them, proves how Lutie Johnson’s subjective mapping constitutes an everyday practice within the novel. As such, Petry’s portrayal of Lutie’s creation of space through these everyday practices illustrates how in her interactions with the street’s dynamics Lutie provides a witnessing cartography of struggle that opposes traditional geographic interpretations

Choosing a speaking test in English as a foreign language for the university entrance exam

En la investigación que aquí presentamos, se estableció como objetivo desarrollar y analizar diferentes formatos de evaluación de la expresión oral en la lengua extranjera (inglés) para la prueba de acceso a la universidad. Para dicho fin se estudiaron y diseñaron tres tipos de tests combinando diferentes formatos y recursos: entrevista individual a partir de una foto, entrevista individual a partir de una tira cómica y diálogo en parejas. Tras pilotar dos pruebas para cada tipo de test, se eligió la más adecuada para cada uno de ellos utilizando para tal fin el nivel de dificultad y de discriminación de cada ítem. Las tres pruebas seleccionadas fueron utilizadas para evaluar una muestra estadísticamente representativa (603 sujetos) del conjunto de la población de estudiantes en su último año de bachillerato en Canarias. Con el programa estadístico Testfact 4.0 se analizó la fiabilidad y nivel de dificultad global de cada prueba, además del nivel de dificultad y de discriminación de cada ítem. Este estudio nos permitió establecer las debilidades y fortalezas de los diferentes tipos de tareas utilizadas.Dans l’étude que nous présentons, l’objectif était de développer et d’analyser les différents formats d’évaluation de l’expression orale en langue étrangère (anglais) pour l’épreuve d’accès à l’université. Pour y arriver, nous avons examiné et élaboré trois types de tests combinant des formats et des supports différents : l’entretien professeur/élève à partir d’une photo, l’entretien à partir d’une bande dessinée, et le dialogue par paires sur consignes spécifiques. Nous avons mené une expérience pilote avec deux modèles d’épreuves pour chaque type de test ; après cette application, nous avons choisi la plus adaptée pour chaque test, en nous appuyant sur le niveau de difficulté et de discrimination de chaque item. Les trois épreuves calibrées ont été employées pour évaluer un échantillon représentatif (603 sujets) de la totalité d’étudiants de la dernière année du baccalauréat aux îles Canaries. Nous avons vérifié avec le logiciel Testfact 4.0 la fiabilité et le degré de difficulté global de chaque épreuve et, en outre, le niveau de difficulté et de discrimination de chaque item. L’analyse nous a permis d’établir les faiblesses et les points forts des différents types de tâches présentées.Language assessments are valuable tools to provide information such as whether individual students are ready to move on to another unit of instruction, in this case the university. In the research outlined in this article, our main aim was to develop a suitable speaking exam. We began by studying and designing three different types of tests, combining different formats and resources: one-to-one interview based on a photo, one-to-one interview based on a comic strip and a dialogue in pairs. After piloting two examples for each type of test, we chose the most suitable using the level of difficulty and discrimination power of each item. Then we implemented the three types of test to a statistical significant sample (603 subjects) of the population of students in their final year of secondary education in the Canary Islands. Finally we used the Testfact 4.0 program to analyze the reliability and level of difficulty of each test, as well as the level of difficulty and discrimination power of each item. This study allowed us to establish the strengths and weaknesses of the different types of tasks used