Effects of Thermal Variations on the Tensile Behavior of FRCM Strengthening Systems

Use of fabric-reinforced cementitious matrices (FRCM) is a very efficient strengthening solution for improving the structural behavior of existing masonry elements. FRCM are capable of improving the load-bearing capacity of masonry panels, at the same time providing more ductile behavior. However, the mechanical performances of these materials could be significantly affected by environmental conditions, such as exposure to thermal variations. This aspect should be properly assessed by guidelines and standards devoted to the design of strengthening interventions. Within this framework, the objective of the present research was to evaluate the effect of a temperature increase on the tensile behavior of various FRCM systems, composed of steel, basalt, or aramid-glass fibers and lime-based or cement-based mortar matrices. Tensile tests were performed for each system under different thermal conditioning protocols, comprising different target temperatures, exposure periods, test conditions, and adopted heating sources. The test results showed that the effect of temperature is more evident in the first phases of the tensile tests, that is, during the uncracked phase and the mortar matrix cracking phase, whereas it is less significant in the final phase, which was more related to fiber behavior. Comparisons between the different thermal conditioning procedures are critically discussed within the paper and, in light of the results obtained, recommendations are included to optimize the testing procedures for future research and qualification procedures

The Geant4-DNA project

The Geant4-DNA project proposes to develop an open-source simulation software based and fully included in the general-purpose Geant4 Monte Carlo simulation toolkit. The main objective of this software is to simulate biological damages induced by ionising radiation at the cellular and sub-cellular scale. This project was originally initiated by the European Space Agency for the prediction of deleterious effects of radiation that may affect astronauts during future long duration space exploration missions. In this paper, the Geant4-DNA collaboration presents an overview of the whole ongoing project, including its most recent developments already available in the last Geant4 public release (9.3 BETA), as well as an illustration example simulating the direct irradiation of a chromatin fibre. Expected extensions involving several research domains, such as particle physics, chemistry and cellular and molecular biology, within a fully interdiciplinary activity of the Geant4 collaboration are also discussed.Comment: presented by S. Incerti at the ASIA SIMULATION CONFERENCE 2009, October 7-9, 2009, Ritsumeikan University, Shiga, Japa

Simulation of cellular irradiation with the CENBG microbeam line using GEANT4

Light-ion microbeams provide a unique opportunity to irradiate biological samples at the cellular level and to investigate radiobiological effects at low doses of high LET ionising radiation. Since 1998 a single-ion irradiation facility has been developed on the focused horizontal microbeam line of the CENBG 3.5 MV Van de Graaff accelerator. This setup delivers in air single protons and alpha particles of a few MeV onto cultured cells, with a spatial resolution of a few microns, allowing subcellular targeting. In this paper, we present results from the use of the GEANT4 toolkit to simulate cellular irradiation with the CENBG microbeam line, from the entrance to the microprobe up to the cellular medium.Comment: 6 pages, 8 figures, presented at the 2003 IEEE-NSS conference, Portland, OR, USA, October 20-24, 200

Technical developments for computed tomography on the CENBG nanobeam line

The use of ion microbeams as probes for computedtomography has proven to be a powerful tool for the three-dimensional characterization of specimens a few tens of micrometers in size. Compared to other types of probes, the main advantage is that quantitative information about mass density and composition can be obtained directly, using specific reconstruction codes. At the Centre d’Etudes Nucléaires de Bordeaux Gradignan (CENBG), this technique was initially developed for applications in cellular biology. However, the observation of the cell ultrastructure requires a sub-micron resolution. The construction of the nanobeamline at the Applications Interdisciplinaires des Faisceaux d’Ions en Region Aquitaine (AIFIRA) irradiation facility has opened new perspectives for such applications. The implementation of computedtomography on the nanobeamline of CENBG has required a careful design of the analysis chamber, especially microscopes for precise sample visualization, and detectors for scanning transmission ion microscopy (STIM) and for particle induced X-ray emission (PIXE). The sample can be precisely positioned in the three directions X, Y, Z and a stepper motor coupled to a goniometer ensures the rotational motion. First images of 3D tomography were obtained on a reference sample containing microspheres of certified diameter, showing the good stability of the beam and the sample stage, and the precision of the motion

Aislamiento de microorganismos halófilos procedentes de ríos, pantanos y aguas residuales de la provincia de Granada

The purpose of this study was the isolation of halophilic micro-organisms from atipically satine environments located in different areas of Granada, Spain; we tried al so to know the number of viable cells per mL in these tested water samples. A total of 130 halophilic microorganisms was examined: 37.7% strains selected were halotolerant rods and they were isolated from rivers; 60.8% of isolated strains was classified as halophilic microorganisms and, in contrast of the majority ecologic stl.ldies conceming moderately halophilic bacteria, strains studied are grouped as Gram-positive.El presente trabajo se planteó con el objetivo de aislar microorganismos halófilos a partir de hábitats atípicamente salinos, tales como ríos, pantanos y aguas residuales de la provincia de Granada, realizando además una detenninación del número de aerobios totales mediante recuento de heterótrofos. Tras seleccionar 130 cepas al azar, el espectro salino nos confinnó que el número de bacterias halotolerantes era notable, el 37.7% y se aislaron principalmente de ríos. Los microorganismos halófilos hallados se clasificaron generalmente como moderados constituyendo el 60.8% de las cepas estudiadas, por lo que se confinna su presencia en dichos ecosistemas. Es importante señalar que el 69.2% del total son bacilos y cocos Gram positivos, el 11.5% presentaron un Gram variable y el 19.3% resultaron ser bacilos Gram negativos, distribución totalmente distinta a la descrita por numerosos autores al realizar estudios ecológicos de la microbiota halófila en medios hipersalinos

Linking organic matter chemistry with soil aggregate stability: Insight from 13C NMR spectroscopy

Soil aggregation is considered as a crucial process in agro-system sustainability due to the role in soil physical, chemical and biological dynamics. Here we tested the hypothesis that the initial chemical traits of organic matter (OM) may help to explain the variability of soil aggregation dynamics after organic amendment. We characterized ten OM types (alfalfa litter, biochar, cellulose, glucose, green compost, maize litter, manure compost, meat powder, sawdust, and solid digestate) by 13C-CPMAS NMR and elemental chemical features to investigate the effects of amendment quality on soil aggregation. In a manipulative factorial experiment, dry samples (200 g) of three soil types (S1, S2 and S3) with different texture, high pH (7\u20139), and similar OM content, were incorporated with 4 g (2% w/w) of dry, 2 mm-grounded OM, incubated in mesocosms for 300 days under controlled temperature (18 \ub1 2 \ub0C night and 24 \ub1 2 \ub0C day), and sampled at 4 dates for measuring aggregation index (AI), based on water stability of soil aggregates (WSA). We found that meat powder and alfalfa litter induced a rapid initial increase of AI, exceeding that of the controls by one to two orders of magnitude, likely acting as a C source for microbes. Biochar incorporation in soil barely affected AI, with intermediate effects with other OM types. Considering C bond types corresponding to OM 13C-CPMAS NMR spectral regions, carbonyl C was only correlated to early AI, possibly due to overlapping signals of amide structures; O-alkyl C and di-O-alkyl C (carbohydrate fraction) were positively associated to AI, indicating a promoting effect on soil structure, while aromatic C fractions showed an opposite pattern, possibly related to aggregate protection by coatings associated to water repellency, or to direct aggregate internal binding. This study demonstrates that OM chemical quality plays an important role in soil aggregation process, with the molecular composition defined by 13C-CPMAS NMR spectroscopy being more predictive of aggregation dynamics compared to classical elemental features. As such, this study provides a significant novel contribution to clarify the relationships between OM chemistry and soil aggregation

Linking organic matter chemistry with soil aggregate stability: Insight from 13C NMR spectroscopy

Soil aggregation is considered as a crucial process in agro-system sustainability due to the role in soil physical, chemical and biological dynamics. Here we tested the hypothesis that the initial chemical traits of organic matter (OM) may help to explain the variability of soil aggregation dynamics after organic amendment. We characterized ten OM types (alfalfa litter, biochar, cellulose, glucose, green compost, maize litter, manure compost, meat powder, sawdust, and solid digestate) by 13C-CPMAS NMR and elemental chemical features to investigate the effects of amendment quality on soil aggregation. In a manipulative factorial experiment, dry samples (200 g) of three soil types (S1, S2 and S3) with different texture, high pH (7\u20139), and similar OM content, were incorporated with 4 g (2% w/w) of dry, 2 mm-grounded OM, incubated in mesocosms for 300 days under controlled temperature (18 \ub1 2 \ub0C night and 24 \ub1 2 \ub0C day), and sampled at 4 dates for measuring aggregation index (AI), based on water stability of soil aggregates (WSA). We found that meat powder and alfalfa litter induced a rapid initial increase of AI, exceeding that of the controls by one to two orders of magnitude, likely acting as a C source for microbes. Biochar incorporation in soil barely affected AI, with intermediate effects with other OM types. Considering C bond types corresponding to OM 13C-CPMAS NMR spectral regions, carbonyl C was only correlated to early AI, possibly due to overlapping signals of amide structures; O-alkyl C and di-O-alkyl C (carbohydrate fraction) were positively associated to AI, indicating a promoting effect on soil structure, while aromatic C fractions showed an opposite pattern, possibly related to aggregate protection by coatings associated to water repellency, or to direct aggregate internal binding. This study demonstrates that OM chemical quality plays an important role in soil aggregation process, with the molecular composition defined by 13C-CPMAS NMR spectroscopy being more predictive of aggregation dynamics compared to classical elemental features. As such, this study provides a significant novel contribution to clarify the relationships between OM chemistry and soil aggregation

Experimental Study on the Shear Behavior of FRCM Strengthened Masonry Panels

nnovative strengthening solutions, such as Fiber Reinforced Cementitious Matrix (FRCM), are becoming increasingly diffused for the retrofitting of existing masonry structures with the aim of reducing the seismic vulnerability of these construction typologies. In recent years, many studies have demonstrated the suitability of these materials in enhancing the shear capacity of masonry walls and improve the overall structural behavior, avoiding fragile collapse mechanisms. In the present work, six diagonal compression tests were performed on unstrengthened and FRCM strengthened masonry panels to evaluate the improvements attributable to the presence of the FRCM systems. Two different bidirectional basalt grids were applied to the masonry samples, with and without mechanical anchorages. The tensile and bond properties of the chosen FRCM systems were investigated through laboratory tests. The objective was, indeed, to compare the performances of two textiles, characterized by different densities, and to investigate the role of mechanical anchorages. The experimental results confirmed the efficiency of the FRCM strengthening systems in improving the shear behavior of masonry panels. The FRCM strengthened samples experienced a considerable strength increase and less brittle failure mechanisms. The roles of both the mortar matrix, the fiber grids and the mechanical anchorages were highlighted by analyzing the onset of cracking and the failure propagation within the samples

Out-of-Plane Behaviour of Tuff and Brick Masonry Walls Strengthened with FRCM Composite Materials

Strengthening with composite materials is becoming more and more an effective solution for increasing the structural safety of masonry buildings, often subjected to severe degradation or potentially vulnerable to seismic events. Structural retrofitting can be performed according to different techniques, based on Fiber Reinforced Polymer (FRP) or Fiber Reinforced Cementitious Matrix (FRCM) strengthening systems. The second group of composite systems is usually preferred nowadays thanks to some important advantages such as better compatibility with the substrate, applicability on wet surfaces, fire resistance, permeability and reversibility. Several experimental and numerical studies can be found in literature concerning masonry panels strengthened with FRP and FRCM systems. The knowledge about the use of the latter, nevertheless, is still partially limited, in particular if the out-of-plane behaviour of walls is taken into account, with the experimental and numerical database available resulting mainly restricted to monotonic cases. In this framework, results of an experimental campaign devoted to the study of the out-of-plane behaviour of tuff and brick masonry walls strengthened with different types of FRCM systems will be presented and discussed in this paper, performing also a comparison with available predictive formulas. Experimental results showed, in general, good performance of FRCM composite materials, with a proper exploitation of their tensile capacity, proving their effectiveness for the out-of-plane strengthening of historical masonry walls

Transience analysis of bursty traffic with erbium doped fiber amplifiers

Copyright © [2009] IEEE. Reprinted from ICTON 2009. ISBN 978-1-4244-4826-5. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.In this paper, we investigate experimentally the impact of optical amplifiers, namely Erbium Doped Fiber Amplifiers (EDFA) on Optical Burst Switching (OBS) networks, operating at 2.5 Gb/s (typical bit rate for current passive optical networks - PON). Bursts with 212 – 1 and 216 – 1 pseudo random binary sequence (PRBS) were studied, with different idle times. The use of traffic with variable idle time was assessed in order to evaluate the effect on the burst initial amplitude. We also analyzed the performance of the packet based system by measuring the Q factor at the receiver and concluded that the performance is not affected by the type of traffic (variable or fixed idle times)