Arte pastoril de la provincia de Ávila

En número dedicado a: La provincia de Ávil

Impact of Gamma Radiation on Dynamic RDSON Characteristics in AlGaN/GaN Power HEMTs

GaN high-electron-mobility transistors (HEMTs) are promising next-generation devices in the power electronics field which can coexist with silicon semiconductors, mainly in some radiation-intensive environments, such as power space converters, where high frequencies and voltages are also needed. Its wide band gap (WBG), large breakdown electric field, and thermal stability improve actual silicon performances. However, at the moment, GaN HEMT technology suffers from some reliability issues, one of the more relevant of which is the dynamic on-state resistance (RON_dyn) regarding power switching converter applications. In this study, we focused on the drain-to-source on-resistance (RDSON) characteristics under 60Co gamma radiation of two different commercial power GaN HEMT structures. Different bias conditions were applied to both structures during irradiation and some static measurements, such as threshold voltage and leakage currents, were performed. Additionally, dynamic resistance was measured to obtain practical information about device trapping under radiation during switching mode, and how trapping in the device is affected by gamma radiation. The experimental results showed a high dependence on the HEMT structure and the bias condition applied during irradiation. Specifically, a free current collapse structure showed great stability until 3.7 Mrad(Si), unlike the other structure tested, which showed high degradation of the parameters measured. The changes were demonstrated to be due to trapping effects generated or enhanced by gamma radiation. These new results obtained about RON_dyn will help elucidate trap behaviors in switching transistors

Caracterización granulométrica del lecho móvil de un río de gravas efímero: Aplicación a un tramo de la riera de Les Arenes

Durante una campaña granulométrica en la riera de Les Arenes se extrajeron más de 676 kilogramos de material aluvial de su lecho de grava efímero. La toma de muestras granulométricas se realizó distinguiendo entre la superficie y el material subyacente o subsuperficie en un tramo del lecho fluvial. Se utilizaron técnicas diferentes para el muestreo de la superficie (pintando un área) y de la subsuperficie (muestreo volumétrico después de extraer la capa superficial). Para comparar las dos muestras se utilizó el factor de conve rsión de Kellerhals y Bray (1971). Los resultados obtenidos, después de la conversión y con un corte inferior de 8 mm en ambas distribuciones, permiten clasificar a la riera de Les Arenes como un río de gr avas gruesas con un tamaño medio superficial (D50sup) de 13 mm y uno en subsuperficie (D50sub) de 17 mm. La campaña granulométrica ha permitido constatar la ausencia de una superficie o coraza más gruesa que el sedimento subyacente en el lecho de la riera. Como consecuencia de este hecho las crecidas anuales permiten el transporte de los tamaños medios del lecho, al contrario de lo que sucede en los ríos perennes con lecho de gr ava. En el artículo se dan las pautas a seguir para realizar una campaña granulométrica, con una toma de muestras correcta y se demuestra la utilidad de las tomas granulométricas, en un solo tramo, cuando el objetivo es el estudio de los procesos fluviales actuales.More than 676 kg were collected during a sediment survey campaign in the ephemeral gravel-bed stream of Les Arenes, NE Spain. Samples were taken in a selected reach distinguishing bed surface and the material beneath it or subsurface. Two different methods were used for sampling the surface (areal sample), and the subsurface (volumetric sample after clear the surface). Both samples were compared using the formal conversion of Kellerhals and Bray (1971). The results obtained, after applied the formal conversion and a lower truncation of 8 mm, permits to classify Les Arenes as a gravel-bed stream with a median surface diameter (D 50 sup) of 13 mm and a median subsurface diameter of 17 mm. The sediment survey campaign has allowed to demonstrate the lack of a surface or armouring layer coarser than the material underneath it. As a consequence of this, annual floods can move easily the median size of the bed, as opposite to what happen in perennial streams with a gravel-bed. In this paper, some practices are recommended to get representative samples of satisfactory precision for sampling a gravel-bed stream. And it shows how useful could be a correct sampling, in a selected reach, when the objective is the study of present fluvial processes

Las fiestas populares en España. Siglos XVI-XVIII

Comunicación presentada en el Congreso "Il tempo libero. Economia e società. Secc. XIII-XVIII" celebrado en Prato (Italia) del 18 al 23 de abril de 1994.Publicad

Arbitrios locales sobre la propiedad semoviente en Castilla durante los siglos XIV y XV.

Sin resume

Don Juan Huarte de San Juan: The doctor who anticipated Don Quixote’s Melancholy

Retrospectivas[ES] El estado de enajenación del ingenioso hidalgo don Quijote lo había aprendido Cervantes a través del doctor Juan Huarte San Juan, autor del famoso ensayo Examen de ingenios, donde formula la teoría de los humores para explicar el cuerpo y el carácter del hombre. En este artículo, pues, repasaremos la biografía de este personaje, analizaremos la formación de los médicos en las universidades de la España del Siglo de Oro, la influencia del Examen en la Europa de su tiempo y en la obra cervantina a través de la melancolía de don Quijote y de la locura del Licenciado Vidriera. Para terminar con la aplicación literaria de las tesis sobre ingenios que definiera nuestro dilecto médico de resonancia mundial. [EN] Cervantes learned about Don Quixote’s derangement through Juan Huarte de San Juan’s famous treatise Examen de ingenios, where he deployed the humoral theory to explain human body and character. In this article Huarte’s biography will be summarized, analyzing the academic background of golden age Spanish doctors, and the impact of Examen in Early Modern Europe and in Cervante’s work by examining Don Quixote’s melancholy and Licenciado Vidriera’s madness. Finally, I will show how the internationally famous Spanish doctor’s thesis was used in literature.N