Mechanical behavior of masonry materials at high temperatures

An experimental campaign is presented to determine the effects of high temperatures on the mechanical properties of several materials for masonry walls (blocks and mortars), testing a series of cylindrical specimens (diameter of 100 mm and height of 200 mm). After compression tests at 20 °C, an experimental procedure was designed for high‐temperature testing. The cylindrical samples were heated in a muffle furnace, then were inserted into a specific apparatus (called ‘thermos’) for maintaining the prescribed temperature, and finally were subjected to a mechanical compression test. The results obtained by applying this procedure show a common variation of the strength, reduction of modulus of elasticity, and corresponding increments of the ultimate strain with temperature enhancement. Specific diagrams and discussion on the results are performed for each material. Copyright © 2014 John Wiley & Sons, Ltd.     

Boosting the electrocatalytic activity of Desulfovibrio paquesii biocathodes with magnetite nanoparticles

The production of reduced value-added chemicals and fuels using microorganisms as cheap cathodic electrocatalysts is recently attracting considerable attention. A robust and sustainable production is, however, still greatly hampered by a poor understanding of electron transfer mechanisms to microorganisms and the lack of strategies to improve and manipulate thereof. Here, we investigated the use of electrically-conductive magnetite (Fe₃O₄) nanoparticles to improve the electrocatalytic activity of a H₂-producing Desulfovibrio paquesii biocathode. Microbial biocathodes supplemented with a suspension of nanoparticles displayed increased H₂ production rates and enhanced stability compared to unamended ones. Cyclic voltammetry confirmed that Faradaic currents involved in microbially-catalyzed H₂ evolution were enhanced by the addition of the nanoparticles. Possibly, nanoparticles improve the extracellular electron path to the microorganisms by creating composite networks comprising of mineral particles and microbial cells.     

Spatial assessment of two widely used land-cover datasets over the continental U.S

Satellite-based land-cover datasets are required for various environmental studies. Two of the most widely used land-cover datasets for the U.S. are the National Land-Cover Data (NLCD) at 30-m resolution and the Global Land-Cover Characteristics (GLCC) at 1-km nominal resolution. Both datasets were produced around 1992 and were expected to contribute similar land-cover information. This study investigated the NLCD distribution within each of 11 GLCC classes at 1-km unit in ten U.S. states. Our analyses showed that the NLCD had similar spatial distribution as the GLCC for the classes of grassland, shrubland, as well as deciduous and evergreen forests. Meanwhile, the GLCC class of cropland and pasture was highly correlated to the NLCD classes of row crops and pasture/hay. The GLCC savanna was appropriately related to the NLCD grassland, pasture/hay, and deciduous forest. The NLCD classes of row crops, pasture, and deciduous forest mainly dominated the GLCC class of cropland/woodland mosaic. Spatial similarity was lower for the GLCC classes of mixed forest, wooded wetland, and cropland/grassland mosaic. In addition to the NLCD urban areas, the GLCC urban and built-up lands were consistently related to the NLCD vegetated areas due to the common mixture of urban and vegetated lands. A set of subclass land-cover information provided through this study is valuable to understand the degrees of spatial similarity for the global vegetated and urban-related classes in selected study areas. The results of this study provide great reference for interchanging less-detailed global land-cover datasets for detailed NLCD to support environmental studies.     

Bayesian techniques to reduce the sample size in automotive electronics attribute testing

This paper discusses the application of Bayesian techniques to the determination of sample sizes required for an attribute test of a product in order to demonstrate a target reliability with a specified confidence. The method is based on analyzing statistical data on similar products and incorporating them into a Bayesian prior distribution for the unknown reliability. A mixture prior obtained by combining a beta prior with the uniform rectangular prior (representing the unknown content of the new product design) is discussed. The suggested method can significantly lower sample sizes for attribute tests and thus reduce cost, time, and resources currently being spent on reliability demonstration testing. A numerical example at the end of the paper illustrates the method.     

A short-range, high-resolution millimeter-wave surface movement radar

Today’s Air (and Airport traffic) management needs an advanced surveillance function for the airport’s surface. Among the different sensors to be integrated for this function just the surface movement radar is able to detect the presence, and determine the position, of non co-operating targets. Present-day smr’s are considered aged and inadequate. In this paper we propose a novel short range radar, operating at frequencies around 95 GHz, to be used in a distributed surface surveillance system. Its main characteristics and the trade-off considerations involved in its design are discussed.     

Obtaining hydrocarbons from ethanol over iron-modified ZSM-5 zeolites

The search for new energy sources has impulsed hydrocarbon production from methanol and ethanol over ZSM-5 zeolites. Iron incorporation by different methods has led to a variety of chemical applications. Thus, hydrocarbon production from ethanol was studied over a ZSM-5 zeolite modified by ion exchange and impregnation with iron. XRD, FTIR, TPR, nitrogen adsorption, Mössbauer and photoacoustic spectroscopies were used for the samples characterization. The highest yield of liquid hydrocarbons was obtained with the low iron-exchanged zeolite, especially co-feeding hydrogen. The calcination procedure led to a migration of the iron species, probably forming iron oxide particles.     

On complete stability of linear and quadratic programming neural networks

The paper addresses complete stability (CS) of the important class of neural networks to solve linear and quadratic programming problems introduced by Kennedy and Chua (IEEE Trans. Circuits Syst., 1988; 35 : 554). By CS it is meant that each trajectory converges to a stationary state, i.e. an equilibrium point of the neural network. It is shown that the neural networks in (IEEE Trans. Circuits Syst., 1988; 35 : 554) enjoy the property of CS even in the most general case where there are infinite non‐isolated equilibrium points. This result, which is proved by exploiting a new method to analyse CS (Int. J. Bifurcation Chaos 2001; 11 : 655), extends the stability analysis by Kennedy and Chua (IEEE Trans. Circuits Syst., 1988; 35 : 554) to situations of interest where the optimization problems have infinite solutions. Copyright © 2002 John Wiley & Sons, Ltd.     

Design Criteria for the Optimization of Series Inductors in AC?DC Thyristor Converters

An analysis is made of the functions of the series inductances in the ac-dc thyristor converting units, and the results of a theoretical study of their rating criteria are summarized. Such work was made as part of the recent redesign of ac-dc converters.