Structure and Dielectric Properties of Cerium Doped Lead Titanate Ceramics

Sintered ceramic powders of cerium-doped lead titanate (Pbx/2+1CexTi1-xO3) ceramics with different Ce dopant concentration in the range (x=0-0.1) have been prepared using a sol-gel chemical route. The sol-gel technique is known to offer better purity and homogeneity, and can yield stoichiometric powders with improved properties at relatively lower processing temperature in comparison to conventional solid-state reaction. X-ray diffraction (XRD) scanning electronic microscope (SEM) and Raman spectroscopy studies have been carried out to identify the crystallographic structure and phase formation. The refinement of the structural parameters was carried out by the Rietveld method. PCT exhibit tetragonal symmetry with the perovskite structure. The dielectric properties as a function of frequency, and phase transition studies on sintered ceramics Pbx/2+1CexTi1-xO3 (x=0.03) has been investigated in detail over a wide temperature range 30-500°C and the results are discussed. Keywords:  A. ceramics; B. x-ray diffraction; C. Raman spectroscopy; D. dielectric; C. properties; E. Ce-modified

Étude de l’évolution du littoral de la baie d’El Jadida (Maroc) par photo-interprétation

La baie d’El Jadida se situe sur la façade atlantique du Maroc (entre 33° 15’ 00’’ et 33° 21’ 40’’ de latitude Nord, 8° 18’ 00’’ et 8° 30’ 00’’ de longitude Ouest). Elle constitue un grand système sableux fortement marqué par la dynamique littorale. L’utilisation des photographies aériennes permet de déterminer d’une part, l’évolution du trait de côte à l’embouchure de l’Oum Rbia à long terme (de 1949 à 1996) et d’autre part.de mesurer l’évolution de l’ensemble du littoral de la baie El Jadida à moyen terme (de 1988 à 1997). Les résultats de l’étude diachronique confirment la variabilité spatio-temporelle et l’évolution du littoral de la baie d’El Jadida avec des zones en érosion et d’autres en accumulation. L’analyse des variations des traits de côte, à moyen terme, ne montre pas des modifications importantes. Les seuls changements ont été enregistrés au niveau des unités morphologiques composant ce littoral (plage aérienne, dunes,…). L’évolution du trait de côte à long terme se caractérise par une forte variabilité dans le secteur de l’estuaire de l’Oum Rbia. La période d’érosion la plus importante se situe entre 1949 et 1996 avec un taux de recul de 45 m (1,28 m/an). Durant cette même période, on distingue aussi une variabilité spatiale qui se traduit par l’existence de deux secteurs très différents : le premier est caractérisé par une forte érosion (plage de la rive droite) et le deuxième est favorisé par des accumulations importantes (flèche sableuse de la rive gauche).Mots-clés : baie d’El Jadida, plage, estuaire, trait de côte, évolution morphologique, évolution diachronique, flèche sableuse, Maroc. Study of coastline evolution of the El Jadida bay (Morocco) by photo-interpretationEl Jadida bay, is located on the middle of the Atlantic coast of Morocco (between 33° 15’ 00’’ and 33° 21’ 40’’ North and between 8° 18’ 00’’ and 8° 30’ 00’’ West), constitute a large sandy stock strongly marked by the littoral dynamic. The use of the aerial photographs permit to identify the coast evolution to the Oum Rbia estuary (of 1949 to 1996) and to measure the littoral of the bay El Jadida evolution in medium-term. The results of this diachronic study confirm space and time variability in the littoral of bay evolution with deepening reach’s and others of sedimentation. The coastline variation analysis in medium-term doesn’t give satisfactory results. The only changes were registered at the morphological units of the coast (aerial beach, dunes, ... ). The coastline evolution in the long-term coast is characterized by a strong variability in the Oum Rbia estuary. The period of the most important erosion ranges between 1949 and 1996 with a rate of retreat of 45 m (1.28 m/an). During this period, we can also notice a space variability which results in the existence of two very different sectors: the first is characterized by strong erosion (beach of Right Bank) and the second is characterized by accumulations (sandy arrow of left bank).Keywords : El Jadida bay, estuary, coastline, morphologic evolution, diachronic evolution, sandy arrow, Morocco

Reflections on a degree initiative: the UK's Birmingham Royal Ballet dancers enter the University of Birmingham

This paper provides an opportunity to share experiences and perceptions of the first 5 years of a degree programme for professional dancers. A partnership developed in the mid-1990s between the UK's Birmingham Royal Ballet and the University of Birmingham, Westhill (now School of Education), to provide a part-time, post-experience, flexible study programme for full-time Company dancers. This is the first 'company customised' higher education programme to dovetail studies around rehearsal, performance and touring schedules. Methodology is based on a narrative by the author, informed by ongoing internal and external evaluations, in-depth interviews with dancers and Company managers, documentation and secondary sources. Outcomes indicate that the programme has made a positive difference to the Company, to the dancers and to the wider education and dance/arts world

Diferencias en el desempeno en pruebas de software visual en función del género. Un estudio con jugadores y jugadoras de baloncesto de 13 anos

The paper presents a study based on a sample of thirteen-year-old boys and girls from the Spanish Basketball Federations team of talented young players. The aim was to try and evaluate the influence of gender in reactions to visual software tests, measured in response times and an awareness of anticipatory action in one-to-one situations in basketball. The participants took part in two tests, using the Reflex programme and Pantallex system, which had been designed and developed by the authors of this study. The number of correct answers and mistakes were measured, together with the response time in milliseconds. The results show that the female players got a higher number of correct answers when their capacity for perceptual anticipation and awareness of anticipatory action was tested with the Reflex programme. Likewise, their response time was better in both tests, with significant differences between both groups in the number of correctanswers with the Reflex programme and in the three perceptual anticipation indexes (one for each test and a third mean index of both the latter)

Una orientación propedéutica al másigt hablado en Melilla

Este artículo recoge uno de los muchos esquemas posibles para la iniciación en el conocimiento del másigt hablado en Melilla, un idioma que constituye una de las entidades culturales fundamentales de nuestra ciudad. Este esquema adopta un objetivo meramente propedéutico en dos sentidos: a) su ciclicidad, esto es, partiendo de unos presupuestos gramaticales y de un vocabulario mínimo se sientan unas bases (lo más adaptadas posibles al español en cuanto a escritura) para ampliarse cuantitativamente y cualitativamente; b) su orientación fundamental que alude a la ciclicidad pretendida en función de la oralidad y la reflexión a realizar por el lector

USING GIS AND PHOTOGRAMMETRY FOR ASSESSING SOLAR PHOTOVOLTAIC POTENTIAL ON FLAT ROOFS IN URBAN AREA CASE OF THE CITY OF BEN GUERIR / MOROCCO

Renewable energy sources are at the forefront of political discussions around the world because of the scarcity of fossil fuels and climate change caused by the accumulation of greenhouse gases. By 2030, Morocco will cover 52% of these energy needs through renewable energies, in order to preserve the environment (COP 22). This paper aims to estimate the potential of photovoltaic solar energy from flat roofs in the city of Ben Guerir, Morocco using remote sensing and GIS data. To achieve this goal, vector orthophoto resulting from the photogrammetric restitution acquired in 2015 were used to generate a 3D model (DSM). The annual solar irradiation is calculated by the analyser of the solar tool. Each roof is calculated based on algorithms for the most common solar panel technologies (mono-si and poly-si). The applicability of this methodology has been demonstrated in the urban area of Benguerir, Morocco, and can be widespread in any other region of the world. The results obtained for a total roofing surface of 135 Ha, i.e. more than 345 Gwh of electricity annually generate. For an average roof of 60 m2 that could supply 5 to 6 households; A planned investment between 118,218 and 167,296 DH, and an annual maintenance charge of 2%. This study may be an initial assessment of solar potential in the city, which can be used to support the management decision regarding investment in the urban solar system

Effets des tempêtes sur une plage aménagée et à forte protection côtière : la plage des Éloux (côte de Noirmoutier, Vendée, France)

 L’analyse diachronique des données disponibles sur le long terme montre que l’érosion de la plage des Éloux dans l’île de Noirmoutier (France) s’est produite entre 1832 et 2008 à des vitesses variables avec un taux moyen de recul du trait de côte de 0,7 m/an. La période 1999-2008 enregistre un fort recul du trait de côte avec un taux moyen de 1,9 m/an. Dans ce contexte, une forte tempête comme celle du 10 mars 2008, si elle contribue à la tendance érosive générale, n’a pas entraîné de conséquences morphogéniques très importantes sur l’île de Noirmoutier. Cet article cherche à estimer cet impact sur la plage des Éloux et à mettre en lumière le fait que l’effet minime de cette tempête importante est imputable à divers facteurs qui sont discutés (dérive inversée, stock sédimentaire disponible sur l’avant plage, défenses côtières).The diachronic analysis of available data shows that the erosion of the Éloux beach along Noirmoutier Island occurred at variable rates between 1832 and 2008 with a mean rate of 0,7 m/year. The period between 1997-2008 shows generalized erosion with a mean rate of 1,9 m/year. The impact of the 10 Marsh 2008 storm on the coastline of Noirmoutier Island appears moderate compared to these rates. This paper aims at assessing the impact of this storm on Les Éloux Beach. It is believed that the relatively low impact of this storm is mainly due to three factors : reversed littoral drift, intertidal sand bank source, and coastal defence

Ecology and extent of freshwater browning-What we know and what should be studied next in the context of global change

Water browning or brownification refers to increasing water color, often related to increasing dissolved organic matter (DOM) and carbon (DOC) content in freshwaters. Browning has been recognized as a significant physicochemical phe-nomenon altering boreal lakes, but our understanding of its ecological consequences in different freshwater habitats and regions is limited. Here, we review the consequences of browning on different freshwater habitats, food webs and aquatic-terrestrial habitat coupling. We examine global trends of browning and DOM/DOC, and the use of remote sensing as a tool to investigate browning from local to global scales. Studies have focused on lakes and rivers while sel-dom addressing effects at the catchment scale. Other freshwater habitats such as small and temporary waterbodies have been overlooked, making the study of the entire network of the catchment incomplete. While past research inves-tigated the response of primary producers, aquatic invertebrates and fishes, the effects of browning on macrophytes, invasive species, and food webs have been understudied. Research has focused on freshwater habitats without consid-ering the fluxes between aquatic and terrestrial habitats. We highlight the importance of understanding how the changes in one habitat may cascade to another. Browning is a broader phenomenon than the heretofore concentration on the boreal region. Overall, we propose that future studies improve the ecological understanding of browning through the following research actions: 1) increasing our knowledge of ecological processes of browning in other wetland types than lakes and rivers, 2) assessing the impact of browning on aquatic food webs at multiple scales, 3) examining the effects of browning on aquatic-terrestrial habitat coupling, 4) expanding our knowledge of browning from the local to global scale, and 5) using remote sensing to examine browning and its ecological consequences.Peer reviewe