Search results for " conductor"
showing 9 items of 169 documents
Dopants and defects in proton-conducting perovskites
2008
Many doped perovskites show high proton conductivity at intermediate to high temperatures (500- 900 °C), which has opened possibilities for many prospected applications in energy conversion (fuel cells), and electrochemical devices. In a doped perovskite, e.g. BaCe1-xYxO3-y, oxygen vacancies are created by charge compensation, and can eventually react with air moisture to form structural protonic defects. The sluggish nature of the proton, which is practically invisible to most structural analyses, and poses enormous problems to quantum chemistry, has surely contributed to slow down the progress in the understanding of these materials: in fact, the conduction dynamics and its interplay with…
Functionalization of a layered oxide with organic moieties: towards hybrid proton conductors
2014
The design of innovative proton conductors for intermediate-temperature fuel cells, closing the gap between PEMFC and SOFC, is a forefront research theme in materials chemistry. [1] Layered perovskites with the Dion-Jacobson structure (ALaNb2O7) have bidimensional lanthanum niobate sheets, separated by a layer of A+ cations. These can be substituted by a variety of molecules with soft chemistry, to yield inorganic-organic hybrids. In particular, the intercalation of amines, alcohols, carboxylic or phosphonic acids, and their covalent binding to the sheets has been demonstrated recently. [2-4]We present preliminary results on the intercalation and covalent bonding of different organic molecu…
On the distribution of lightning current among interconnected grounding systems in medium voltage grids
2018
This paper presents the results of a first investigation on the effects of lightning stroke on medium voltage installations' grounding systems, interconnected with the metal shields of the Medium Voltage (MV) distribution grid cables or with bare buried copper ropes. The study enables us to evaluate the distribution of the lightning current among interconnected ground electrodes in order to estimate if the interconnection, usually created to reduce ground potential rise during a single-line-to-ground fault, can give place to dangerous situations far from the installation hit by the lightning stroke. Four different case studies of direct lightning stroke are presented and discussed: (1) two …
A new approach to calibrate the thermal conditions in space charge measurements on HVDC mini-cables
2019
The PEA method is currently widespread used for space charge measurements in mini-cables in order to qualify the behavior of semicon-dielectric-semicon compound under electric and thermal stress. The main goal of this research is to quantitatively evaluate the relationship between the thermal boundary conditions applied to cables or mini-cables and the maximum local electric field due to the accumulated space charge. Hitherto, several research groups have obtained thermal gradients over the dielectric's radius heating the conductor by Joule effect due to an induced current. In this paper, a numerical approach is offered to calibrate the heat exchange boundary conditions to apply to a sample…
Polymorphism and Metallic Behavior in BEDT-TTF Radical Salts with Polycyano Anions
2012
Up to five different crystalline radical salts have been prepared with the organic donor BEDT-TTF and three different polynitrile anions. With the polynitrile dianion tcpd2− (=C[C(CN)2]32−), two closely related radical salts: α'-(ET)4tcpd·THF (1) (THF = tetrahydrofurane) and α'-(ET)4tcpd·H2O (2) have been prepared, depending on the solvent used in the synthesis. With the mono-anion tcnoetOH− (=[(NC)2CC(OCH2CH2OH)C(CN)2]−) two polymorphs with similar physical properties but different crystal packings have been synthesized: θ-(ET)2(tcnoetOH) (3) and β''-(ET)2(tcnoetOH) (4). Finally, with the mono-anion tcnoprOH− (=[(NC)2CC(OCH2CH2CH2OH)C(CN)2]−) we have prepared a metallic…
Los infractores reincidentes en el tráfico: análisis de variables sociodemográficas, personalidad y consumo de alcohol de los asistentes a los cursos…
2015
INTRODUCCIÓN Las intervenciones que se pueden realizar ante el problema de la seguridad vial son muy diversas. Pero entre todas las medidas adoptadas en los últimos años, concretamente a raíz de la puesta en marcha del Plan Estratégico de Seguridad Vial 2005-2008 de la Dirección General de Tráfico, destaca, por su repercusión social y legislativa, la puesta en marcha del Sistema de Permiso por Puntos (SPP). El objetivo principal del SPP es mejorar la seguridad vial a través de la reducción de la reincidencia en la comisión de infracciones, promoviendo un cambio de actitudes y comportamientos en las vías públicas. No obstante, aunque el efecto principal del SPP es disuadir a los conductores …
On the use of the EMI for the health monitoring of bonded elements
2014
The low weight, robustness and fatigue resistance of adhesive joints make them suitable for structural joints. A fully developed nondestructive evaluation technique however is needed to monitor and assess the quality of bonded joints. In the present paper the application of the electromechanical impedance (EMI) technique is proposed. In the EMI method a piezoelectric transducer (PZT) is attached to the structure of interest. The high sensitivity and low power consumption make the EMI method feasible for real time structural health monitoring. In this study we investigated the sensitivity of the electromechanical response of a PZT to the curing and the quality of the adhesive used for bonded…
Salud vial: ¿el conductor a terapia?
2009
El Instituto Universitario de Investigación en Tráfico y Seguridad Vial (INTRAS) y Attitudes (programa social de Audi), tras la publicación de los libros "Salud vial: Teoría y prácticas de los trastornos físicos y psíquicos en la conducción." y "Salud vial: Diagnóstico de los conductores españoles.", se plantearon como actividad complementaria la realización de unas jornadas que cumplieran los siguientes objetivos: • Permitir avanzar en el conocimiento y la implementación de medidas que contribuyan a una mejora de la seguridad vial. • Servir como foro de expresión para científicos y profesionales con un tono constructivo, plural e integrador. • Tener un componente de difusión tanto al públi…
Thermoelectric devices and supercapacitors based on nanostructured semiconducting polymers for energy production and storage
2017
Más de dos terceras partes de la energía generada por las fuentes convencionales se pierden como calor. Recuperar esas pérdidas de energía puede ayudar a crear una forma más eficiente de producir energía para el desarrollo sostenible de nuestra sociedad. Mediante el uso de generadores termoeléctricos es posible producir energía a partir de gradientes de temperatura de tal manera que la termoelectricidad puede ser una buena estrategia para la recolección y recuperación de energía. La eficiencia termoeléctrica suele ser dada por la figura adimensional de mérito, ZT. Actualmente, los materiales inorgánicos se usan comúnmente en aplicaciones termoeléctricas, sin embargo presentan varias desvent…