Microstructural modifications in tungsten induced by high flux plasma exposure : TEM examination

We have performed microstructural characterization using transmission electron microscopy (TEM) techniques to reveal nanometric features in the sub-surface region of tungsten samples exposed to high flux, low energy deuterium plasma. TEM examination revealed formation of a dense dislocation network and dislocation tangles, overall resulting in a strong increase in the dislocation density by at least one order of magnitude as compared to the initial one. Plasma-induced dislocation microstructure vanishes beyond a depth of about 10 mu m from the top of the exposed surface where the dislocation density and its morphology becomes comparable to the reference microstructure. Interstitial edge dislocation loops with Burgers vector a(0)/2 and a(0) were regularly observed within 6 mu m of the sub-surface region of the exposed samples, but absent in the reference material. The presence of these loops points to a co-existence of nanometric D bubbles, growing by loop punching mechanism, and sub-micron deuterium flakes, resulting in the formation of surface blisters, also observed here by scanning electron microscopy

The formation of a nanohybrid shish-kebab (NHSK) structure in melt-processed composites of poly (ethylene terephthalate) (PET) and multi-walled carbon nanotubes (MWCNTs)

The combination of synchrotron Small- and Wide-Angle X-ray scattering (SAXS/WAXS), and thermal analysis was used to follow the evolution of crystalline morphology and crystallization kinetics in a series of melt-processed composites of poly(ethylene terephthalate) (PET) and multiwall carbon nanotubes (MWCNT). The as-extruded PET-MWCNT composites underwent both hot and cold isothermal crystallizations where a final oriented nanohybrid shish-kebab (NHSK) crystalline structure was observed. An oriented NHSK structure was seen to persist even after melting and recrystallization of the composites. From the scattering data, we propose a model whereby the oriented MWCNTs act as heterogeneous nucleation surfaces (shish) and the polymer chains wrap around them and the crystallites (kebabs) grow epitaxially outwards during crystallization. However, depending on crystallization temperature, unoriented crystallites also grow in the polymer matrix, resulting in a combination of a NHSK and lamellar morphology. In contrast, the neat PET homopolymer showed the sporadic nucleation of a classic unoriented lamellar structure under the same isothermal crystallization conditions. These results provide a valuable insight into the distinctive modification of the crystalline morphology of melt-processed polymer-MWCNT composites prior to any secondary processing, having a significant impact on the use of MWCNTs as fillers in the processing and modification of the physical and mechanical properties of engineering polymers

Morfología polínica de las especies de cítricos cultivadas en Andalucía occidental (España)

. Morfología polínica de las especies de cítricos cultivadas en Andalucía occidental (España). Se estudia la morfología polínica de seis especies de cítricos de los géneros Citrus (C. aurantium, C. deliciosa, C. grandis, C. limon y C. sinensis) y Fortunella (F. margarita), con los microscopios óptico y electrónico de barrido. Por los caracteres estudiados (polaridad, simetría, contorno (en visión ecuatorial y corte óptico meridiano y visión polar y corte ecuatorial), tamaño, número, tipo y dimensiones de las aberturas, grosor de la exina y ornamentación) se describe la morfología del polen y se discuten los resultados obtenidos.No es posible la separación de los dos géneros, pero se pueden diferenciar parte de las especies del género Citrus

Impact of minority concentration on fundamental (H)D ICRF heating performance in JET-ILW

ITER will start its operation with non-activated hydrogen and helium plasmas at a reduced magnetic field of B-0 = 2.65 T. In hydrogen plasmas, the two ion cyclotron resonance frequency (ICRF) heating schemes available for central plasma heating (fundamental H majority and 2nd harmonic He-3 minority ICRF heating) are likely to suffer from relatively low RF wave absorption, as suggested by numerical modelling and confirmed by previous JET experiments conducted in conditions similar to those expected in ITER's initial phase. With He-4 plasmas, the commonly adopted fundamental H minority heating scheme will be used and its performance is expected to be much better. However, one important question that remains to be answered is whether increased levels of hydrogen (due to e. g. H pellet injection) jeopardize the high performance usually observed with this heating scheme, in particular in a full-metal environment. Recent JET experiments performed with the ITER-likewall shed some light onto this question and the main results concerning ICRF heating performance in L-mode discharges are summarized here

Una aproximación al estudio de la concentración industrial

Not available.En este trabajo se lleva a cabo una revisión de la concentración industrial desde el punto de vista de su medición y de la problemática que ello plantea. Este concepto así como su cuantificación es im tema con importantes aplicaciones en diferentes campos de investigación entre los que se encuentra la Geografía Industrial

SROS2: Usable Cyber Security Tools for ROS 2

ROS 2 is rapidly becoming a standard in the robotics industry. Built upon DDS as its default communication middleware and used in safety-critical scenarios, adding security to robots and ROS computational graphs is increasingly becoming a concern. The present work introduces SROS2, a series of developer tools and libraries that facilitate adding security to ROS 2 graphs. Focusing on a usability-centric approach in SROS2, we present a methodology for securing graphs systematically while following the DevSecOps model. We also demonstrate the use of our security tools by presenting an application case study that considers securing a graph using the popular Navigation2 and SLAM Toolbox stacks applied in a TurtleBot3 robot. We analyse the current capabilities of SROS2 and discuss the shortcomings, which provides insights for future contributions and extensions. Ultimately, we present SROS2 as usable security tools for ROS 2 and argue that without usability, security in robotics will be greatly impaired

ESTELAS DISCOIDEAS DE LA RIOJA

This study gathers together all the discoid commemorative monuments (high crosses) that the authors know of in La Rioja. Fifty four are added here to the twelve that have already been published. Also included are some sculptured stones that could be related, at least typologically, and some other elements that could present eventual parallelisms.El trabajo recoge todas las estelas discoideas conocidas por los autores en la geografía riojana. Frente a las doce publicadas anteriormente, aquí se presentan cincuenta y cuatro. Se añaden algunas piedras talladas que pueden tener alguna relación al menos tipológica y algunos otros elementos para plantear eventuales paralelismos

Sedimentary evolution and provenance of the Last Fluvial episodes of the Cameros Basin (Lower Cretaceous, North Spain)

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Seismic Microzonation of the Texcoco Lake Area, Mexico

This paper presents some of the most relevant results obtained from field, laboratory and analytical investigations aimed at characterizing the seismic environment prevailing at the Texcoco lake region, in the Valley of Mexico, with the goal of developing a microzonation. In particular, this study focuses on an area of 19.0 by 5.5 km2, which has been instrumented with four seismological stations: TXSO, TXS1, TXS2 and TXCH that have recorded ground motions for at least 15 years. Field investigations were conducted to define the subsoil conditions underneath each station. Dynamic testing in these high plasticity clays was carried out to establish the variation of shear stiffness and damping with strain level. Ground motion definition was achieved through empirically derived response spectra obtained from sets of earthquake ground motions recorded at a nearby station located in soft soil, which were deconvolved to the base rock. An statistical analysis using random shear wave velocity profiles and an stochastic site response analysis was used to developed sets of response spectra to reduce uncertainties associated with soil properties determination and seismic environment characterization. The final proposed response spectra for each studied point were developed from the envelope plus one standard deviation computed at each ground motion station. These spectra show good agreement both in frequency content and spectral ordinates with those obtained directly from measurements taken at these seismological stations. Finally equations to construct the proposed response spectra were proposed