Minimum volume stability limits for axisymmetric liquid bridges subject to steady axial acceleration

In this paper the influence of an axial microgravity on the minimum volume stability limit of axisymmetric liquid bridges between unequal disks is analyzed both theoretically and experimentally. The results here presented extend the knowledge of the static behaviour of liquid bridges to fluid configurations different from those studied up to now (almost equal disks). Experimental results, obtained by simulating microgravity conditions by the neutral buoyancy technique, are also presented and are shown to be in complete agreement with theoretical ones

Estimación de la Reflectividad del Multitrayecto en Entornos Urbanos en Radares de Apertura Sintética

Synthetic Aperture Radar (SAR) images a target region reflectivity function in the multi-dimensional spatial domain of range and cross-range. SAR synthesizes a large aperture radar in order to achieve finer azimuth resolution than the one provided by any on-board real antenna. Conventional SAR techniques assume a single reflection of transmitted waveforms from targets. Nevertheless, today¿s new scenes force SAR systems to work in urban environments. Consequently, multiple-bounce returns are added to direct-scatter echoes. We refer to these as ghost images, since they obscure true target image and lead to poor resolution. By analyzing the quadratic phase error (QPE), this paper demonstrates that Earth¿s curvature influences the defocusing degree of multipath returns. In addition to the QPE, other parameters such as integrated sidelobe ratio (ISLR), peak sidelobe ratio (PSLR), contrast and entropy provide us with the tools to identify direct-scatter echoes in images containing undesired returns coming from multipath

Técnica de Inversión Temporal para la Mejora del Enfocado de Imágenes SAR en Entornos Urbanos

Conventional SAR (Synthetic Aperture Radar) techniques only consider a single reflection of transmitted waveforms from targets. Nevertheless, today?s new applications force SAR systems to work in much more complex scenes such as urban environments. As a result, multiple-bounce returns are additionally superposed to direct echoes. We refer to these as ghost images, since they obscure true target image and lead to poor resolution. By applying Time Reversal concept to SAR imaging (TR-SAR), it is possible to reduce considerably ?or almost mitigate? ghosting artifacts, recovering the lost resolution due to multipath effects. Furthermore, some focusing indicators such as entropy (E), contrast (C) and Rényi entropy (RE) provide us a good focusing criterion when using TR-SAR

The impact of respiration and oxidative stress response on recombinant ?-amylase production by Saccharomyces cerevisiae

Studying protein production is important for fundamental research on cell biology and applied research for biotechnology. Yeast Saccharomyces cerevisiae is an attractive workhorse for production of recombinant proteins as it does not secrete many endogenous proteins and it is therefore easy to purify a secreted product. However, recombinant production at high rates represents a significant metabolic burden for the yeast cells, which results in oxidative stress and ultimately affects the protein production capacity. Here we describe a method to reduce the overall oxidative stress by overexpressing the endogenous HAP1 gene in a S. cerevisiae strain overproducing recombinant α-amylase. We demonstrate how Hap1p can activate a set of oxidative stress response genes and meanwhile contribute to increase the metabolic rate of the yeast strains, therefore mitigating the negative effect of the ROS accumulation associated to protein folding and hence increasing the production capacity during batch fermentations

Model of the expansion process for R245fa in an Organic Rankine Cycle (ORC)

An Organic Rankine Cycle (ORC) is considered as one of the most environmental-friendly ways to convert different kinds of low temperature energies, i.e. solar, geothermal, biomass and thermal energy of exhaust gases into electrical energy. Two important facts about the ORC must be considered: An organic fluid is selected as the working fluid and a high expansion ratio is usually presented in the machinery due to thermodynamic and efficiency factors. In the past, the pre-design of turbomachinery has been based on the usage of ideal fluid laws, but the real gas effects have a significant influence in the ORC working condition, due to its proximity to the saturation vapor line. In this article, the Equations of State (EoS) (Ideal gas, Redlich-Kwong-Soave and Peng-Robinson) have been evaluated in a typical ORC expansion in order to observe the inaccuracies of the ideal gas model with different thermodynamic variables. Finally an isothermal process followed by an isochoric process is proposed to reproduce the thermodynamic process of the organic fluid expansion by means of simpler equations. In the last point of this paper, several examples of this expansion process have been calculated, in order to analyze the proposed methodologies. It has been concluded that in typical expansion process of ORC (2.5 MPa-0.1 MPa and 1.6MPa-0.1MPa), the PR and RKS equations show deviations between 6% and 8% in specific energy. These deviations are very low compared with the ideal gas equation whose deviations are above 100 %.This work was partially funded by the "Programa de Formacion de Profesorado Universitario (F.P.U)", "Programa de Apoyo a la Investigacion y Desarrollo de la Universidad Politecnica de Valencia 2010", "Proyectos I+D para grupos de investigacion emergentes 2011" and "Programa de apoyo a la investigacion y desarrollo de la U.P.V (PAID-06-09)". The authors thanks to R. Gatzweiler for his help to improve the English grammar.Lujan Martinez, JM.; Serrano Cruz, JR.; Dolz Ruiz, V.; Sánchez Serrano, J. (2012). Model of the expansion process for R245fa in an Organic Rankine Cycle (ORC). Applied Thermal Engineering. 40:248-257. https://doi.org/10.1016/j.applthermaleng.2012.02.020S2482574

César Vallejo en la poesía de Joaquín Vásquez Aguilar

Artículo número 6 de la Sección Variaciones. 12 páginas. tyvlliiiTras ser ignorado por la crítica, en 2010 Joaquín Vásquez Aguilar es rescatado por la Universidad Autónoma de Chiapas y el coneculta, con la publicación de El pico de la garza más blanca. Obra reunida y Poesía reunida. En este ensayo se reflexiona sobre las características de su poesía, la cual abreva de su infancia en la costa chiapaneca. En algunos poemas usa un lenguaje coloquial; en otros, los de clara influencia de César Vallejo, apuesta por la desautomatización del lenguaje y la experimentación formal. Sus temáticas siempre buscan la belleza de las cosas simples, elementales.After being ignored by critics, in 2010 Joaquín Vásquez Aguilar is rescued by the Autonomous University of Chiapas and coneculta, with the publication of El pico de la garza más blanca. Obra reunida and Poesía reunida. This article reflects on the characteristics of his poetry, which always refers to his childhood on the coast of Chiapas. In some poems he uses a colloquial language; in others, those of clear influence of César Vallejo, bet on the deautomatization of language and formal experimentation. His themes always look for the beauty of simple and elementary things

Linum flos-carmini (Linaceae), a new species from northern Morocco

Linum bicolor is a problematic North African taxon associated with L. setaceum. A consensus on the taxonomic status of a putative form (L. setaceum var. bicolor f. robusta) has not been achieved yet. We conducted a morphological study based on herbarium and field collections, combined with nuclear (ITS) and plastid (ndhF5-8 and trnL-F) phylogenies to clarify its status. The phylogenetic analysis did not reveal molecular divergence, but a comparative morphological study revealed substantial differences in traits previously used to distinguish the two taxa (stems, leaves, corolla and calyx size). In addition, we found that the indumentum of sepals, petal colour, and the arrangement of anthers and stigmas differed so clearly between the form robusta and L. setaceum s. stricto, that recognizing the former taxon as an independent species was justified. We provide an identification key to the yellow- and white-flowered Linum species in NW Africa. We also revised the unplaced name L. bicolor Schoubs. ex DC. and lectotypified it to avoid nomenclatural problems

Methodology to design a bottoming Rankine cycle, as a waste energy recovering system in vehicles. Study in a HDD engine

This article describes a methodology for the optimization of a bottoming cycle as a waste heat recovering system in vehicles. The methodology is applied to two particular cases in order to evaluate the preliminary energetic and technical feasibility of the implementation of a bottoming cycle in a heavy duty diesel (HDD) engine considering two different criteria. Initially, a study of the different waste heat sources of the engine is described. In this study, the power and exergy of each heat source is quantified, in order to evaluate which sources are suitable to be used in the bottoming cycle. The optimum working fluids to run the cycles are selected (water and R245fa). Then, the ideal Rankine cycle is optimized for the two different working fluids and different sets of heat sources (all the available heat sources and the sources with high exergy respectively) throughout the engine operating range, reaching a maximum improvement of 15% of the fuel consumption of the engine. Later, a study of the minimum temperature difference between the hot and cold flow of the heat exchangers is described. The improvements in fuel consumption and the size of the installed heat exchanger are related to this temperature difference. Finally, the non-ideal behavior of the machines (pump and expander) is analyzed, obtaining a maximum improvement of 10% in brake specific fuel consumption (bsfc).This work was partially funded by the "Programa de Formacion de Profesorado Universitario (FPU)", "Programa de Apoyo a la Investigacion y Desarrollo de la Universidad Politecnica de Valencia 2010", "Proyectos I + D para grupos de investigacion emergentes 2011" and "Programa de apoyo a la investigacion y desarrollo de la U.P.V (PAID-06-09)". The authors thank J. Dahlqvist for his help in improving the English grammar.Macian Martinez, V.; Serrano Cruz, JR.; Dolz Ruiz, V.; Sánchez Serrano, J. (2013). Methodology to design a bottoming Rankine cycle, as a waste energy recovering system in vehicles. Study in a HDD engine. Applied Energy. 104:758-771. https://doi.org/10.1016/j.apenergy.2012.11.075S75877110