537 research outputs found
Nematic Films and Radially Anisotropic Delaunay Surfaces
We develop a theory of axisymmetric surfaces minimizing a combination of
surface tension and nematic elastic energies which may be suitable for
describing simple film and bubble shapes. As a function of the elastic constant
and the applied tension on the bubbles, we find the analogues of the unduloid,
sphere, and nodoid in addition to other new surfaces.Comment: 15 pages, 18 figure
Nonlinear characteristics identification of an impact oscillator with a one-sided elastic constraint
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record Data availability:
Data will be made available on request.Impacting systems are widely used in many engineering applications, such as self-propelled robots, energy
harvesting and percussive drilling, which exhibit rich and complex nonlinear phenomena. Among these
applications, predicting nonlinearities and estimating system parameters are of great interest of nonlinear dynamics research community. Backbone curve is an analytical tool that captures the frequencyamplitude dependence of nonlinear systems. In this paper, we estimate the impacting stiffness of a
single-degree-of-freedom non-smooth dynamical system qualitatively by using the backbone curve. It was
found that an increase of the impacting stiffness may lead to lowering the backbone curve. An adaptive
differential evolution algorithm with the Metropolis criterion is proposed to identify the parameters of
the impacting system quantitatively using experimental data, which are consistent with our theoretical
predictions. Finally, the identified parameters are verified, and the limitations of the backbone curve
are drawn. The nonlinear characteristics identification method studied in this paper could be extended
to other vibro-impact systems and is potentially applicable to structural health monitoring and robotic
sensing.European Union’s Horizon 202
Caracterización de aceros dual-phase obtenidos por laminación en caliente
RESUMEN
Se tomaron muestras de acero al C-Mn-Si disponible en el mercado y mediante un proceso de laminación en caliente y bobinado, se obtuvo acero Dual Phase con microestructura y propiedades mecánicas dentro del rango teórico esperado de este material. El proceso termomecánico consistió en producir una fuerte reducción a temperaturas mayores a Ar3, mediante pasadas de laminación sucesivas, para posteriormente enfriar el acero durante aproximadamente 5 s, (a una velocidad de 20 °C/s) en el rango de equilibrio α+γ. La temperatura Ar3, medida mediante calorimetrÃa diferencial de barrido, fue de 890 °C. A continuación se realizó un temple en el rango de temperaturas de bobinado (550-675 °C), enfriando posteriormente las muestras de acuerdo a una curva pre establecida, que corresponde a la curva de enfriamiento real de una bobina. La caracterización microestructural de las muestras obtenidas, se realizó mediante microscopÃa óptica, microscopÃa electrónica de barrido y microscopÃa de fuerza atómica. Adicionalmente se realizó una medición de texturas mediante difracción de rayos X, para el estudio de las orientaciones resultantes, producto de la variación de la temperatura de término de laminación (TTL) y la temperatura de bobinado (TB), determinándose cómo afectan estas variables a las distintas componentes de texturas. Se complementó la información microestructural con los valores de los Ãndices de anisotropÃa normal y planar, medidos de acuerdo a la norma ASTM E-517. Se correlacionaron las intensidades de las componentes de texturas encontradas con los valores de los Ãndices de anisotropÃa, encontrándose que sólo es posible producir leves mejoras en el Ãndice de anisotropÃa normal, a través de una combinación apropiada de las temperaturas de término de laminación y de bobinado.
ABSTRAC
Samples were obtained from C-Mn-Si steel available in the market. Through a hot rolling and coiling process, it was possible to obtain Dual-Phase steel with microstructural and mechanical properties in the theoretical range typical of this material. The thermomechanical process consisted of a strong reduction by multiples pass of hot rolling at temperatures above Ar3, controlled-cooling the sheets during 5 s (at a rate of 20 °C/s in the equilibrium range α+γ. Temperature Ar3 measured by differential scanning calorimetry was 890 °C. Quenching was then carried out in the coiling temperatures range (500-675 °C), cooling the samples in accordance to an established curve that corresponds to the actual cooling curve of a coil. The microstructural characterization of the samples obtained was carried out by optical microscopy, scanning electron microscopy and atomic force microscopy. Additionally, texture measurements were carried out by X-ray diffraction in order to study the resulting orientations due to the finishing rolling temperature and coiling temperature, determining the influence on these parameters of the different texture components. The microstructural results were complemented with the normal and planar anisotropy indexes measured in according to the ASTM E-517 standard. The intensities of the different texture components were correlated with the values of anisotropy indexes, finding that it is possible to obtain only a slightly enhancement in the normal anisotropy index through an appropriate combination of finish rolling and coiling temperatures
Determinación de la tensión de laminación en caliente a partir de ensayos de tracción
RESUMEN
La predicción del comportamiento mecánico de aceros laminados en caliente es un aspecto importante durante el procesamiento industrial. En el presente trabajo, las tensiones necesarias para el proceso de laminado, fueron estimadas usando tres métodos, el primero de los cuales se basa en la aplicación del modelo de Sellars, que toma en cuenta el coeficiente de fricción y el lÃmite elástico. El segundo método, estima la tensión de laminado a partir de la tensión promedio obtenida durante los ensayos de tracción. El tercer método, estima la tensión de laminado a partir de los datos de potencia consumida por el equipo de laminación. Esta metodologÃa fue aplicada en este estudio a un acero al carbono. La conclusión de este trabajo es que los resultados obtenidos por los métodos basados en el modelo de Sellars y de la potencia consumida, son coincidentes, en tanto que el método basado en la tensión de tracción, presenta valores ligeramente menores a los predichos por los otros modelos.
ABSTRACT
Prediction of mechanical behavior of hot rolled steels is an important aspect during industrial processing. The rolling stress needed to the process were estimated using three methods, the first of which is related to the Sellars`s model that takes into account the friction coefficient and the yield stress. The second method estimates the rolling stress as the average stress obtained during the tensile tests. The third method, estimates the rolling stress from the data of power consumed by the rolling equipment. This methodology was applied in this study to a carbon steel. The conclusion of the work is that results obtained by Sellars`s and consumed power, are coincident. The method based on the average tensile stress predicts stresses lower than those obtained with other two methods
Serenata alegorica para solemnizar la possession, que por el serenissimo señor infante cardenal don Luis Jayme de Borbon, tomò de el arzobispado de Sevilla su coad-ministrador el ilustrissimo señor D. Gabriel Torres de Navarra, arzediano titular, y canonigo de esta Santa Patriarchal Iglesia, y Arzobispo electo de Milytene
Pie de imp. tomado del colofónSign.: []4, B4, C2Port. y texto orladosH HAZ/0766(2
The QUIET Instrument
The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the
Cosmic Microwave Background, targeting the imprint of inflationary
gravitational waves at large angular scales (~ 1 degree). Between 2008 October
and 2010 December, two independent receiver arrays were deployed sequentially
on a 1.4 m side-fed Dragonian telescope. The polarimeters which form the focal
planes use a highly compact design based on High Electron Mobility Transistors
(HEMTs) that provides simultaneous measurements of the Stokes parameters Q, U,
and I in a single module. The 17-element Q-band polarimeter array, with a
central frequency of 43.1 GHz, has the best sensitivity (69 uK sqrt(s)) and the
lowest instrumental systematic errors ever achieved in this band, contributing
to the tensor-to-scalar ratio at r < 0.1. The 84-element W-band polarimeter
array has a sensitivity of 87 uK sqrt(s) at a central frequency of 94.5 GHz. It
has the lowest systematic errors to date, contributing at r < 0.01. The two
arrays together cover multipoles in the range l= 25-975. These are the largest
HEMT-based arrays deployed to date. This article describes the design,
calibration, performance of, and sources of systematic error for the
instrument
Effectiveness and safety of once-weekly semaglutide: findings from the SEMACOL-REAL retrospective multicentric observational study in Colombia
IntroductionDiabetes stands as one of the leading causes of death worldwide. Glucagon-like peptide-1 receptor agonists rank among the most effective medications for lowering blood glucose and body weight, as well as reducing cardiovascular risk in individuals with diabetes. Observational studies complement experimental evidence in new settings, different populations, and real-world healthcare practices.MethodsA multicentric observational study of adults with type 2 diabetes treated with once-weekly subcutaneous semaglutide in four health centers in Colombia was conducted. The protocol for the present study was not pre-registered.ResultsData from 186 patients were included. Most patients were women (57%) with a mean age of 62.8 ± 12.1 years. One year of once-weekly semaglutide usage was associated with a mean reduction in HbA1C of −1.47% (95% CI −1.76, −1.17), weight loss of −4.23 kg (95% CI −5.34, −3.12), and albumin/creatinine ratio of −18.6 mg/g (95% CI −60.2, −5.9). Approximately half the treated patients achieved a level of HbA1c ≤7% by the end of follow-up. Adverse events were rare and consistent with clinical trial safety profiles.ConclusionIn Colombia, administering semaglutide subcutaneously once a week over a 1-year period led to an average weight loss of 4.2 kg and a decrease of 1.4% in HbA1c
Oracion panegyrica-funeral, que en las honras, que a la buena memoria del ilustrissimo Señor Don Gabriel Torres de Navarra, y Monsalve, ... celebró el venerable Clero de la Santa Iglesia de Santa Maria de la Villa de Lebrija, el dia 28 del mes de Agosto, de 1757
Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 2007Fecha tomada de las licenciasSegún Gutiérrez del Caño, José Padrino imprime en Sevilla ca. 1748-1775Sign. : [calderón]-2[calderón]4, A-E4, F
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