Reconstruction subgrid models for nonpremixed combustion

Large-eddy simulation of combustion problems involves highly nonlinear terms that, when filtered, result in a contribution from subgrid fluctuations of scalars, Z, to the dynamics of the filtered value. This subgrid contribution requires modeling. Reconstruction models try to recover as much information as possible from the resolved field Z, based on a deconvolution procedure to obtain an intermediate field ZM. The approximate reconstruction using moments (ARM) method combines approximate reconstruction, a purely mathematical procedure, with additional physics-based information required to match specific scalar moments, in the simplest case, the Reynolds-averaged value of the subgrid variance. Here, results from the analysis of the ARM model in the case of a spatially evolving turbulent plane jet are presented. A priori and a posteriori evaluations using data from direct numerical simulation are carried out. The nonlinearities considered are representative of reacting flows: power functions, the dependence of the density on the mixture fraction (relevant for conserved scalar approaches) and the Arrhenius nonlinearity (very localized in Z space). Comparisons are made against the more popular beta probability density function (PDF) approach in the a priori analysis, trying to define ranges of validity for each approach. The results show that the ARM model is able to capture the subgrid part of the variance accurately over a wide range of filter sizes and performs well for the different nonlinearities, giving uniformly better predictions than the beta PDF for the polynomial case. In the case of the density and Arrhenius nonlinearities, the relative performance of the ARM and traditional PDF approaches depends on the size of the subgrid variance with respect to a characteristic scale of each function. Furthermore, the sources of error associated with the ARM method are considered and analytical bounds on that error are obtained

A comparative study of the electrochemical properties of vitamin B-6 related compounds at physiological pH

A comparative study of vitamin B6 group and related compounds in buffered solutions using electrochemical techniques has been performed at neutral pH. Irreversible bi- or tetra-electronic processes are observed for these substances, and the electron transfer coefficient (αn) calculated. It was concluded that either the first or second electron transfer were the rate determining step of the electrode process. The diffusion coefficient of these substances was calculated and the values given follow an inverse tendency to the molecular size. For aldehydes the values obtained were corrected of the hydration reaction. It is important to remark that catalytic waves were reported for the first time for these compounds. Using a model involving the nitrogen of the basic structure the kinetic constants were calculated for most of them

Edad, crecimiento y reproducción de Gobio gobio L. (Pisces, Cyprinidae) en un tramo regulado del río Segura (SE de España)

The age, growth and reproduction of Gobio gobio, were studied during a period of two years in a section of the Segura River regulated by the effect of a small upstream hydroelectric power station. A total of 254 specimens were caught monthly by electrofishing. The studied population showed a maximum of six age classes in females (0+–5+) and five in males (1+–5+). All females were mature at 2+ age class, whereas only 62.5% 2+ males showed mature gonads. During the studied period, both sexes showed maximum values of Gonadosomatic Index in May and spawn was different between the two studied periods. Compared with other populations, the studied population from a regulated locality is characterized by a non–seasonal body condition cycle and low captures of juvenile fish (0+, 1+) probably due to the effect of washing produced by drastic and unpredictable flow changes.La edad, crecimiento y reproducción de Gobio gobio, ha sido estudiada a lo largo de dos años en un tramo del río Segura regulado por una pequeña central hidroeléctrica. Mediante pesca eléctrica fueron capturados, mensualmente, un total de 254 ejemplares. Las hembras presentaron seis clases de edad (0+–5+) mientras que los machos presentaron cinco clases (1+–5+). Todas las hembras de clase de edad 2+ resultaron maduras mientras que los machos 2+ resultaron maduros en un 62,5% de los casos. Durante el periodo de estudio, ambos sexos presentaron los máximos valores del Índice Gonadosomático durante los meses de mayo aunque el desove resultó diferente entre los dos periodos estudiados. En comparación con otras poblaciones, la población estudiada en un tramo regulado del río se caracteriza por no presentar un ciclo estacional en la condición somática y bajas capturas de ejemplares juveniles (0+, 1+) debido, probablemente, al efecto de lavado provocado por los drásticos e impredecibles cambios en el caudal

Wrinkling of a bilayer membrane

The buckling of elastic bodies is a common phenomenon in the mechanics of solids. Wrinkling of membranes can often be interpreted as buckling under constraints that prohibit large amplitude deformation. We present a combination of analytic calculations, experiments, and simulations to understand wrinkling patterns generated in a bilayer membrane. The model membrane is composed of a flexible spherical shell that is under tension and that is circumscribed by a stiff, essentially incompressible strip with bending modulus B. When the tension is reduced sufficiently to a value \sigma, the strip forms wrinkles with a uniform wavelength found theoretically and experimentally to be \lambda = 2\pi(B/\sigma)^{1/3}. Defects in this pattern appear for rapid changes in tension. Comparison between experiment and simulation further shows that, with larger reduction of tension, a second generation of wrinkles with longer wavelength appears only when B is sufficiently small.Comment: 9 pages, 5 color figure

Classical Topological Order in Kagome Ice

We examine the onset of classical topological order in a nearest-neighbor kagome ice model. Using Monte Carlo simulations, we characterize the topological sectors of the groundstate using a non-local cut measure which circumscribes the toroidal geometry of the simulation cell. We demonstrate that simulations which employ global loop updates that are allowed to wind around the periodic boundaries cause the topological sector to fluctuate, while restricted local loop updates freeze the simulation into one topological sector. The freezing into one topological sector can also be observed in the susceptibility of the real magnetic spin vectors projected onto the kagome plane. The ability of the susceptibility to distinguish between fluctuating and non-fluctuating topological sectors should motivate its use as a local probe of topological order in a variety of related model and experimental systems.Comment: 17 pages, 9 figure

UDP: an integral management system of embedded scripts implemented into the IMaX instrument of the Sunrise mission

The UDP (User Defined Program) system is a scripting framework for controlling and extending instrumentation software. It has been specially designed for air- and space-borne instruments with flexibility, error control, reuse, automation, traceability and ease of development as its main objectives. All the system applications are connected through a database containing the valid script commands including descriptive information and source code. The system can be adapted to different projects without changes in the framework tools, thus achieving great level of flexibility and reusability. The UDP system comprises: an embedded system for the execution of scripts by the instrument software; automatic tools for aiding in the creation, modification, documentation and tracing of new scripting language commands; and interfaces for the creation of scripts and execution control.Comment: This paper has been presented in the SPIE 2008, Marselle, Franc

Outstanding aspects on the use of spent FCC catalyst in binders

4 pages, 3 fiures, 7 tables.-- En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.FCC is a waste material from petrochemical plants which has interesting properties for preparing binders. FCC is lightly grey in color, and white FCC-portland cements with L*≥85 can be prepared. FCC reactivity is enhanced by grinding and it is attributed to pozzolanic reaction towards lime. Stratlingite is the main hydrated product from pozzolanic reaction, and CSH and CAH are also formed. Reactivity of FCC is high, and low curing temperature does not affect this contribution to strength in hardened mixtures. Additionally, high strength concrete can be easily prepared, and compressive strength greater 100MPa can be reached. Mixtures with low w/b ratio showed good behaviour in carbonation tests.Authors thank to Ministerio de Ciencia y Tecnología of Spain and FEDER the financial support of MAT 2001-2694 and BIA 2004-0052 projects.Peer reviewe

Tratamiento quirúrgico de la fractura de acetábulo con luxación posterior de cadera: análisis retrospectivo de 20 casos

Entre 1985 y 1990 fueron intervenidos en nuestro servicio 20 pacientes con fractura acetabular y luxación posterior de cadera, con edades desde 22 a 53 años, 18 (90%) eran varones. Los accidentes de tráfico fueron la causa de 18 (90%) de las lesiones. Diez (50%) presentaron lesiones asociadas de importancia. Se estudió su evolución con un seguimiento medio de 5 años (rango de 3.5 a 8.1). La fractura de pared posterior ha sido la que con mayor frecuencia se ha asociado a la luxación (50%), seguida de la transversa y de pared posterior (30%). Hemos obtenido 14 (70%) resultados satisfactorios; 2 pacientes precisaron artroplastia total a los 3 años. No se observó peor evolución en los casos de mayor edad, pero sí en aquéllos que fueron intervenidos pasadas las 3 semanas del accidente. Se comentan aspectos de la evaluación preoperatoria.Between 1985 and 1990, 20 patients aged from 22 to 53 years with fracture of the acetabulum and posterior dislocation of the femoral head were treated surgically. Eighteen (90%) were male. Eighteen (90%) of the fractures were sustained in a motor-vehicle accident. Ten (50%) patients had multiple associated injuries. The average duration of the follow-up period was 5 years (range from 3.5 to 8.1). Ten (50%) of the dislocations were associated with posterior wall fracture. We observed 14 (70%) satisfactory results; 2 patients needed a THA 3 years later. Best results were achieved with early treatment. Aspects of the preoperative evaluation are commented

Diseño y análisis de dos tipologías estructurales para su utilización como estructuras auxiliares en el diseño de jardines

In gardening and more particularly in the design of gardens and urban parks, nowadays exits the necessity to introduce useful auxiliary structures for the shelter of the users to the solar radiation, at certain moments of the day. During long time, joints of classic roof garden have reproduced in all our landscaped zones, that otherwise have been revealed like excessively expensive and not very functional elements. In the present article we are tried to expose the possibility of executing modern and functional sets with a minimum cost and a very brief period of execution. We are analyzed a set of roof garden designed to be constructed within the Campus of the University of Almeria, with the intention to demonstrate that respecting the norm on construction, novel solutions in which diverse uses are integrated, often noncompatible under other conceptions, can be obtained, with a contained cost. Inside this group two modules are distinguished, one more classic, rectangular, with a confi guration that allows a structural operation balanced that are translated in the use of metallic profi les of little size, and other more novel, octogonal, but that under the same previous premises, it has been solved through a deep analysis to establish the most suitable geometry, to determine its behavior, calculation, determine the proportions and resolution of the problems of execution and assembly.En jardinería en general y más en particular en el diseño de jardines y parques urbanos, se plantea la necesidad de introducir estructuras auxiliares útiles para el cobijo de sus usuarios frente a la radiación solar en determinados momentos del día. Durante mucho tiempo, se han reproducido conjuntos apergolados clásicos en todas nuestras zonas ajardinadas, que en caso contrario se han revelado como elementos excesivamente caros y poco funcionales. En el presente artículo se pretende exponer la posibilidad de ejecutar conjuntos vanguardistas y funcionales con un coste mínimo y un periodo de ejecución breve. Se ha analizado un conjunto de pérgolas diseñado para ser construido dentro del Campus de la Universidad de Almería, con la intención de demostrar que respetando la normativa sobre edifi cación se pueden conseguir soluciones novedosas en las que se integren usos diversos, a menudo no compatibles bajo otras concepciones, con un coste contenido. Dentro de este conjunto se distinguen dos módulos, uno, de corte más clásico, rectangular, con una confi guración que permite un funcionamiento estructural equilibrado que se traduce en la utilización de perfi les metálicos de no mucha envergadura; y otro, más novedoso, octogonal, pero que bajo las mismas premisas anteriores, se ha resuelto a través de un profundo análisis para establecer la geometría más adecuada, determinar su comportamiento, cálculo, dimensionado y resolución de los problemas de ejecución y montaje