Homogenized finite element analysis on effective elastoplastic mechanical behaviors of composite with imperfect interfaces

A three-dimensional (3D) representative volume element (RVE) model was developed for analyzing effective mechanical behavior of fiber-reinforced ceramic matrix composites with imperfect interfaces. In the model, the fiber is assumed to be perfectly elastic until its tensile strength, and the ceramic material is modeled by an elasto-plastic Drucker-Prager constitutive law. The RVE model is then used to study the elastic properties and the tensile strength of composites with imperfect interfaces and validated through experiments. The imperfect interfaces between the fiber and the matrix are taken into account by introducing some cohesive contact surfaces. The influences of the interface on the elastic constants and the tensile strengths are examined through these interface models

Records of volcanic events since AD 1800 in the East Rongbuk ice core from Mt. Qomolangma

Continuous Bi profile of the East Rongbuk (ER) ice core near Mt. Qomolangma reveals nine major volcanic events since AD 1800. Compared with Volcanic Explosivity Index (VEI), it shows that the concentrations of Bi in the ER ice core can reflect the major volcanic events within the key areas. This provides a good horizon layer for ice core dating, as well as a basis for reconstructing a long sequence of volcanic records from the Qinghai-Xizang (Tibet) Plateau ice cores

Transformerless topologies for grid-connected single-phase photovoltaic inverters

NOTICE: this is the author’s version of a work that was accepted for publication in . Changes resulting from the publishing process, such as peer review, editing, corrections,structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in RENEWABLE AND SUSTAINABLE ENERGY REVIEWS, [VOL 15 , ISSUE 7, (07/2011)] DOI 10.1016/j.rser.2011.03.034[EN] In order to improve the efficiency and reduce the cost of a photovoltaic system, the use of transformerless photovoltaic inverters is an alternative of increasing interest. However, this topology needs to be studied in detail, as it presents some problems related to the galvanic connection between the grid and the photovoltaic generator (e.g. efficiency degradation and safety problems). In this paper, a review of grid-connected single-phase photovoltaic inverters based on transformerless topologies has been carried out. On the one hand, some alternatives based on classical topologies have been presented. On the other hand, alternatives based on multi-level inverter topologies have been studied, showing up that no leakage current is generated in comparison to classical topologies. © 2011 Elsevier Ltd All rights reserved.This work is supported by the Spanish Ministry of Science and Innovation under grant ENE2009-13998-C02-02.Patrao Herrero, I.; Figueres Amorós, E.; González Espín, FJ.; Garcerá Sanfeliú, G. (2011). Transformerless topologies for grid-connected single-phase photovoltaic inverters. Renewable and Sustainable Energy Reviews. 15(7):3423-3431. https://doi.org/10.1016/j.rser.2011.03.034S3423343115

Synthetic strategies to nanostructured photocatalysts for CO2 reduction to solar fuels and chemicals

Artificial photosynthesis represents one of the great scientific challenges of the 21st century, offering the possibility of clean energy through water photolysis and renewable chemicals through CO2 utilisation as a sustainable feedstock. Catalysis will undoubtedly play a key role in delivering technologies able to meet these goals, mediating solar energy via excited generate charge carriers to selectively activate molecular bonds under ambient conditions. This review describes recent synthetic approaches adopted to engineer nanostructured photocatalytic materials for efficient light harnessing, charge separation and the photoreduction of CO2 to higher hydrocarbons such as methane, methanol and even olefins