Characterization Campaign Research Articles

Certification for trace elements and methyl mercury mass fractions in IAEA-456 marine sediment sample

Marine sediment certified reference material (CRM), IAEA-456 was recently produced by the Environment Laboratories of the International Atomic Energy Agency (IAEA) and certified for trace elements and methyl mercury (CH3Hg). This paper presents the sample preparation methodology, material homogeneity and stability studies, evaluation of results from the characterisation campaign, the assignment of property values and their associated uncertainty. The reference values and associated expanded uncertainty for nine trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn) and CH3Hg in marine sediment sample are established. The new CRM can be used for the development and validation of analytical methods, for the determination of trace elements and methyl mercury in sediments and also for quality assurance/quality control purposes.

Estimation of uniaxial compressive strength of North Algeria sedimentary rocks using density, porosity, and Schmidt hardness

This study aims to establish new correlations to assess uniaxial compressive strength (UCS) of northern Algeria sedimentary rocks. This estimation is based on the measurements of density, porosity, and Schmidt hammer hardness. To achieve this goal, a geological and geotechnical characterization campaign was conducted on 19 types of sandstone and carbonate rocks which have been collected from different geological areas of the Maghrebides chain. Petrographic analyses were conducted to identify the geological characteristics of each kind of rock. Subsequently, physico-mechanical tests (i.e., density, porosity, hardness, and uniaxial compressive strength) were carried out for all the sampled rocks. The results were then used to develop correlations between UCS values and the other parameter values determined. Finally, the UCS predictive equations which have the best predictive powers (coefficient of determination R 2 of 0.75 to 0.94) were discussed taking into account the geological specificities of the rocks, and then compared to similar studies developed by other authors in different areas of the world.

A new management strategy based on the reallocation of ads-/desorption times: Experimental operation of a full-scale 3 beds adsorption chiller

In this paper, a wide experimental characterization campaign aimed at measuring the performance of an innovative 3-beds adsorptive chiller prototype is reported.The prototype was designed to employ a new management strategy, based on different durations of adsorption and desorption isobaric steps of a basic temperature driven adsorptive cooling cycle and aimed at achieving high cooling power density.The performance were measured, in terms of Average Cooling Power (ACP), cooling COP and Volumetric Cooling Power (VCP), using a test bench suitable for the characterization of thermally driven cooling/heating machines, under typical boundary conditions of air conditioning applications. A sensitive analysis was carried out to assess the effect of several parameters (e.g. the temperature lift TM−TL, driving temperature TH and cycle time). on the operation of the chiller. The results of the experimental activity depict a complete performance map for the tested chiller and demonstrate the potential of the new cycle management strategy.At nominal boundary conditions (i.e. TH∼90°C, TL∼18°C and TM∼25°C), the cooling machine was able to deliver an ACP of 4.4kW and an overall VCP of 9.4kW/m3, with a COP of 0.35 while the VCP referred to the volume of the only adsorber was ∼275kW/m3.

Analysis of ITER NbTi and Nb3Sn CICCs experimental minimum quench energy with JackPot, MCM and THEA models

Cable-in-conduit conductors (CICCs) for ITER magnets are subjected to fast changing magnetic fields during the plasma-operating scenario. In order to anticipate the limitations of conductors under the foreseen operating conditions, it is essential to have a better understanding of the stability margin of magnets. In the last decade ITER has launched a campaign for characterization of several types of NbTi and Nb3Sn CICCs comprising quench tests with a singular sine wave fast magnetic field pulse and relatively small amplitude. The stability tests, performed in the SULTAN facility, were reproduced and analyzed using two codes: JackPot-AC/DC, an electromagnetic-thermal numerical model for CICCs, developed at the University of Twente (van Lanen and Nijhuis 2010 Cryogenics 50 139–148) and multi-constant-model (MCM) (Turck and Zani 2010 Cryogenics 50 443–9), an analytical model for CICCs coupling losses. The outputs of both codes were combined with thermal, hydraulic and electric analysis of superconducting cables to predict the minimum quench energy (MQE) (Bottura et al 2000 Cryogenics 40 617–26). The experimental AC loss results were used to calibrate the JackPot and MCM models and to reproduce the energy deposited in the cable during an MQE test. The agreement between experiments and models confirm a good comprehension of the various CICCs thermal and electromagnetic phenomena. The differences between the analytical MCM and numerical JackPot approaches are discussed. The results provide a good basis for further investigation of CICC stability under plasma scenario conditions using magnetic field pulses with lower ramp rate and higher amplitude.

Parametric Characterization of TES Detectors Under DC Bias

The X-ray integrated field unit (X-IFU) in European Space Agency's (ESA's) Athena mission will be the first high-resolution X-ray spectrometer in space using a large-format transition-edge sensor microcalorimeter array. Motivated by optimization of detector performance for X-IFU, we have conducted an extensive campaign of parametric characterization on transition-edge sensor (TES) detectors with nominal geometries and physical properties in order to establish sensitivity trends relative to magnetic field, dc bias on detectors, operating temperature, and to improve our understanding of detector behavior relative to its fundamental properties such as thermal conductivity, heat capacity, and transition temperature. These results were used for validation of a simple linear detector model in which a small perturbation can be introduced to one or multiple parameters to estimate the error budget for X-IFU. We will show here results of our parametric characterization of TES detectors and briefly discuss the comparison with the TES model.

Structural monitoring of “Himera” viaduct by low-cost MEMS sensors: characterization and preliminary results

The term structural health monitoring (SHM) usually refers to the process of implementing a damage detection strategy for aerospace, civil or mechanical engineering infrastructures. Under an extreme event, such as an earthquake or unanticipated blast loading, SHM could be used for rapid condition screening, to provide, in near real time, reliable information about the performance of a structural system during the event and about the subsequent integrity of the system itself. On the other hand, owners of buildings and civil infrastructures need information on the actual state of the structures in order to realize effective life-cycle management plans and reduce the economic and social impact of maintenance. In fact, inspections and repairs entail huge direct and social costs due to the interruption or reduction of the structure serviceability. Such information can be collected and elaborated by means of adequate monitoring systems but their diffusion is still limited by the high cost of sensors and devices needed. In this work, the realization of a monitoring system on some bridge piers of the “Himera” viaduct, located in Italian A19 Palermo–Catania highway and recently damaged by a landslide, is presented. The proposed monitoring system aims to observe the global stability of the un-collapsed side of the viaduct during the demolition works of the other side and it is intended as a quasi-real-time alert tool able to send data and warning messages to an operations center. In order to contain costs, low-cost micro electronic mechanical system sensors have been used for the monitoring. The architecture and main features of the developed monitoring system are described in detail and the preliminary results, recorded during the first months of the campaign, are reported and discussed. Since the proposed monitoring system is still a prototype, it has been necessary to provide a metrological characterization campaign in laboratory conditions in order to define a calibration law to correct the acquired data and to estimate the sensitivity and the accuracy of the measurements. The results proved that the proposed system can be used for the monitoring of civil structures and infrastructures.

A consistent experimental protocol for the strain rate characterization of thermoplastic fabrics

AbstractThis paper introduces an experimental procedure aiming at performing a consistent mechanical characterization of textile composites behavior, under static and dynamic loadings, and particularly their macroscopic strain rate‐dependent mechanisms. The procedure includes the design and validation of a reduced specimen adapted to dynamic testing, which guarantees the consistency of the identified macroscopic properties under a wide range of strain rates. An interrupted high speed tensile apparatus was also developed to investigate the strain rate sensitivity of the nonlinear constitutive behavior from = 10 − 4 s − 1 to 102 s − 1. The originality of this experimental device lies in its ability to stop high speed loadings before ultimate failure, at adjustable, accurate strain levels. Finally, an extensive characterization campaign was performed. Results reveal a high strain rate dependency of the linear and nonlinear behavior. The procedure therefore generates consistent characterization data that may trustworthily be used for modeling purposes.

Drawing down the remaining copper inventory in a leach pad by way of subsurface leaching

A significant amount of metal inventory can reside in a leach pad due to unfavorable metallurgical and hydraulic conditions. Continued leaching using surface irrigation will likely be unsuccessful at recovery in any reasonable time frame. In this work, we investigate how subsurface leaching (SSL), using wells to facilitate the delivery of barren solution, could potentially increase recovery and drawdown the inventory in a shorter period of time. An initial characterization campaign of the leach pad using drilling and assaying along with geophysical methods showed that inventory was high because the ore remained dry from compaction. Other areas were also shown to have preferential flow paths as a means to drain solution out of the leach pad. Assaying results taken from sonic coring and auger cuttings, and extrapolated across the leach pad, revealed a potential of 37×106kg of acid soluble copper.Our investigation covers the first 1000days of SSL, with 110 PVC wells distributed across five main areas. During this time, we estimate production at 2.26×106kg of copper based on the amount of solution introduced through the wells multiplied by the average copper grade from a number of sources, including monitoring wells and newly formed side slope seeps. Some areas performed better than others, especially where assays revealed that acid soluble copper was greater than 50% of total copper. The SSL program is expected to continue for at least another 1000days, and we expect an additional 7×106 to 15×106kg will be withdrawn from inventory.

Air pollution, PM2.5 composition, source factors, and respiratory symptoms in asthmatic and nonasthmatic children in Santiago, Chile

The objective of this study was to determine the association of respiratory symptoms and medication use and exposure to various air pollutants, PM2.5 components, and source factors in a panel of asthmatic and nonasthmatic children in Santiago, Chile. To this end, 174 children (90 asthmatics and 84 nonasthmatics) were followed throughout the winter months of 2010 and 2011. During the study period, children filled out daily diaries to record respiratory symptoms and medication use. Air pollution data were obtained from government central site measurements and a PM2.5 characterization campaign. PM2.5 source factors were obtained using positive matrix factorization (PMF). Associations of symptoms and exposure to pollutants and source-factor daily scores were modeled separately for asthmatic and nonasthmatic children using mixed logistic regression models with random intercepts, controlling for weather, day of the week, year, and viral outbreaks.Overall, high concentrations of air pollutants and PM2.5 components were observed. Six source factors were identified by PMF (motor vehicles, marine aerosol, copper smelter, secondary sulfates, wood burning, and soil dust). Overall, single pollutant models showed significant and strong associations between 7-day exposures for several criteria pollutants (PM2.5, NO2, O3), PM2.5 components (OC, K, S, Se, V), and source factors (secondary sulfate) and coughing, wheezing and three other respiratory symptoms in both in asthmatic and nonasthmatic children. No associations were found for use of rescue inhalers in asthmatics. Two-pollutant models showed that several associations remained significant after including PM2.5, and other criteria pollutants, in the models, particularly components and source factors associated with industrial sources.In conclusion, exposure to air pollutants, especially PM2.5, NO2, and O3, were found to exacerbate respiratory symptoms in both asthmatic and nonasthmatic children. Some of the results suggest that PM2.5 components associated with a secondary sulfate source may have a greater impact on some symptoms than PM2.5. In general, the results of this study show important associations at concentrations close or below current air quality standards.

Structural Snapshots of an Engineered Cystathionine-γ-lyase Reveal the Critical Role of Electrostatic Interactions in the Active Site.

Enzyme therapeutics that can degrade l-methionine (l-Met) are of great interest as numerous malignancies are exquisitely sensitive to l-Met depletion. To exhaust the pool of methionine in human serum, we previously engineered an l-Met-degrading enzyme based on the human cystathionine-γ-lyase scaffold (hCGL-NLV) to circumvent immunogenicity and stability issues observed in the preclinical application of bacterially derived methionine-γ-lyases. To gain further insights into the structure-activity relationships governing the chemistry of the hCGL-NLV lead molecule, we undertook a biophysical characterization campaign that captured crystal structures (2.2 Å) of hCGL-NLV with distinct reaction intermediates, including internal aldimine, substrate-bound, gem-diamine, and external aldimine forms. Curiously, an alternate form of hCGL-NLV that crystallized under higher-salt conditions revealed a locally unfolded active site, correlating with inhibition of activity as a function of ionic strength. Subsequent mutational and kinetic experiments pinpointed that a salt bridge between the phosphate of the essential cofactor pyridoxal 5'-phosphate (PLP) and residue R62 plays an important role in catalyzing β- and γ-eliminations. Our study suggests that solvent ions such as NaCl disrupt electrostatic interactions between R62 and PLP, decreasing catalytic efficiency.

Si-rich Silicon Nitride for Nonlinear Signal Processing Applications

Nonlinear silicon photonic devices have attracted considerable attention thanks to their ability to show large third-order nonlinear effects at moderate power levels allowing for all-optical signal processing functionalities in miniaturized components. Although significant efforts have been made and many nonlinear optical functions have already been demonstrated in this platform, the performance of nonlinear silicon photonic devices remains fundamentally limited at the telecom wavelength region due to the two photon absorption (TPA) and related effects. In this work, we propose an alternative CMOS-compatible platform, based on silicon-rich silicon nitride that can overcome this limitation. By carefully selecting the material deposition parameters, we show that both of the device linear and nonlinear properties can be tuned in order to exhibit the desired behaviour at the selected wavelength region. A rigorous and systematic fabrication and characterization campaign of different material compositions is presented, enabling us to demonstrate TPA-free CMOS-compatible waveguides with low linear loss (~1.5 dB/cm) and enhanced Kerr nonlinear response (Re{γ} = 16 Wm−1). Thanks to these properties, our nonlinear waveguides are able to produce a π nonlinear phase shift, paving the way for the development of practical devices for future optical communication applications.

Undrained behaviour of granular soils conditioned for EPB tunnelling – A new experimental procedure

AbstractThis paper presents a characterisation campaign carried out on granular soils conditioned for EPB tunnelling using a modified direct shear box. The main objective of soil conditioning is the reduction of its shear strength to control the counterpressure inside the bulk chamber. In order to preserve the pseudo‐fluid characteristics of the conditioned soil mass, the main concerning para meters are their undrained properties. To characterise the un drained behaviour an adopted watertight direct shear apparatus was used. The purpose of this research is to define a simplified testing procedure for conditioned soil, analysing its feasibility and reliability with resources that can be found at any laboratory or job site. A comparison between the results obtained under dry and conditioned conditions is presented for three different cohesionless soils. The choice of the materials studied has been made in order to cover a wide range within sands grain size.

Bond behavior of self consolidating concrete

The new generation of innovative projects has led to the use of greater amounts of reinforcement and the development of concrete with specific characteristics. It is necessary to use a material that ensures the uniformity of the cross section, as well as the adherence of the existing reinforcement, and due to this, the self-consolidating concrete becomes an technique alternative has great potential to achieve these properties. The aim of this paper is to analyze the bond behavior of self-consolidating concrete that was obtained by means of the Beam Test performed within a large experimental campaign of characterization. Four types of SCC were studied with two strength levels (40 MPa and 60MPa) and two different types of granular skeletons, using two specimens at each age (3, 7, and 28 days). All specimens were tested with a corrugated steel bar 10 mm in diameter. The results show that the adhesion tension independently of resistance presents a rapidly evolving at 7 days reached 95% of the total adhesion by 28 days.

Application of stability indicators for the assessment of the degradation of residual household waste before landfilling.

In France, domestic waste production is estimated at c 350 kg year-1 per person and landfilling still represents a predominant way of municipal solid waste management, with 39% of waste dumped in 2007. Waste characterization campaigns were conducted at different stages of a mechanical-biological treatment process in order to evaluate its efficiency. Waste samples were sorted by size (>100 mm, <100-20 mm and <20 mm) in order to assess the opportunity for mechanical and aerobic degradation and to reduce the volume of waste landfilled. The monitoring of parameter characteristics of waste stabilization highlighted a decrease in both organic matter and oxidizable organic matter, and an increase in fine particles <20 mm. The respirometric index after 4 days performed on waste samples from the pre-treatment stage showed a decrease in the biological activity compared with the samples taken upstream in the process. The biochemical methane potential of the waste is above the German limit of acceptance in landfills. This intermediate phase of stabilization is confirmed by the results of the leaching tests and hydrophobic fractionation.

From field experiments to salinity products: a tribute to the contributions of Jordi Font to the SMOS mission

This article summarizes some of the activities in which Jordi Font, research professor and head of the Department of Physical and Technological Oceanography, Institut de Ciencies del Mar (CSIC, Spanish National Research Council) in Barcelona, has been involved as co-Principal Investigator for Ocean Salinity of the European Space Agency Soil Moisture and Ocean Salinity (SMOS) Earth Explorer Mission from the perspective of the Remote Sensing Lab at the Universitat Politecnica de Catalunya. We have probably left out some of his many contributions to salinity remote sensing, but we hope that this review will give an idea of the importance of his work. We focus on the following issues: 1) the new accurate measurements of the sea water dielectric constant, 2) the WISE and EuroSTARRS field experiments that helped to define the geophysical model function relating brightness temperature to sea state, 3) the FROG 2003 field experiment that helped to understand the emission of sea foam, 4) GNSS-R techniques for improving sea surface salinity retrieval, 5) instrument characterization campaigns, and 6) the operational implementation of the Processing Centre of Levels 3 and 4 at the SMOS Barcelona Expert Centre.

Mechanical properties of basalt fiber reinforced composites manufactured with different vacuum assisted impregnation techniques

Abstract This work describes an experimental mechanical characterisation campaign on composites made out of a quasi-unidirectional basalt fabric. In order to evaluate the ability of commercial basalt fabrics and their composites to meet the potentials of basalt fibers, the work has used raw materials from commercial catalogs with no further modification. Two common manufacturing techniques for medium performance composites have been adopted: vacuum assisted resin infusion, and hand-impregnated vacuum bagging. Two panels, one for each technique, have been fabricated, able to provide a sufficient number of samples for a comprehensive stiffness and strength characterization through Tensile, Flexural, In-Plane Shear, Short Beam Shear, Double Cantilever Beam and End-Notched Flexural tests. Results revealed a significant dependence of the mechanical properties on the manufacturing processes, due to their different ability to fully impregnate the dry fabric assembly, and on the quality of fiber/matrix adhesion. In general, hand-impregnation followed by vacuum bag curing was able to guarantee a better impregnation, which in particular yielded superior Interlaminar Shear Strength and Interlaminar Fracture Toughness performances.

Modelling and Simulation of the Santa Rita Mine Milling Circuit

The Santa Rita Mine, located in the State of Bahia, was the first Mirabela Mineracao operation in Brazil. Started in 2009, the nickel sulphide processing plant has undergone constant modifications, aiming to adapt to the changes in the ore. Main modifications included autogenous grinding converted to semi-autogenous, as well as the installation of a desliming stage aiming to remove ultrafine minerals which reduced the nickel recovery in flotation. A full survey and ore characterization campaign was carried out to assess alternatives for increasing grinding circuit capacity. Experimental data were balanced and used to calibrate mathematical models which were the basis for simulation exercises. This paper describes the main aspects related to circuit modeling and simulation, as well as assessing alternatives for increasing the grinding circuit capacity.

Classification of Refuse Derived Fuel (RDF) and Model Development of a Novel Thermal Utilization Concept Through Air-Gasification

The need for refuse derived fuels (RDF) standardization gets rapidly essential in the EU-member states and especially in regions where a specific market for such fuels is currently under development. The promotion of standardization practices facilitates public acceptance, supports the development of quality assurance mechanisms and enhances the marketability of selected waste streams as fuels with high biogenic content. In the present work the results of an extensive RDF sampling and characterization campaign are reported, along with the results of process calculations for the potential energy utilization of this fuel in an air blown gasifier. The studied materials recovery facility produces ~15,000 t RDF/y, derived from packaging waste, and is mainly composed of plastic and paper. Given that the produced material is not currently thermally utilized for commercial purposes, it is believed that such standardization will drastically enhance fuel marketability and public acceptance. The current work classified the aforementioned RDF as 4, 2, 1 according to the European Standard EN 15359:2011. Moreover, thermodynamic calculations on the gasification process found that the optimum operational temperature for any air gasification process that utilizes the studied RDF, in terms of carbon conversion rate and gasification efficiency, lies between 850 and 900 °C. The extended sampling average fuel composition determined the operating conditions for autothermal operation; the process simulations reveal that the ER may range from 0.27 to 0.42.

Estimation of road profile variability from measured vehicle responses

ABSTRACTWhen assessing the statistical variability of fatigue loads acting throughout the life of a vehicle, the question of the variability of road roughness naturally arises, as both quantities are strongly related. For car manufacturers, gathering information on the environment in which vehicles evolve is a long and costly but necessary process to adapt their products to durability requirements. In the present paper, a data processing algorithm is proposed in order to estimate the road profiles covered by a given vehicle, from the dynamic responses measured on this vehicle. The algorithm based on Kalman filtering theory aims at solving a so-called inverse problem, in a stochastic framework. It is validated using experimental data obtained from simulations and real measurements. The proposed method is subsequently applied to extract valuable statistical information on road roughness from an existing load characterisation campaign carried out by Renault within one of its markets.

Cyclic elastoplastic behaviour, hardness and microstructural properties of Ti-6Al-4V manufactured through selective laser melting

Additive manufacturing methods have been increasingly attracting the attention of researchers and engineers due to offered advantages in this regard. Selective laser melting (SLM) is an additive manufacturing process which is used to produce complex shaped parts. Limited research has been reported so far on the cyclic elastoplastic response of SLM Ti-6Al-4V, a technologically significant phenomenon affecting the low and high cycle fatigue performance of the fabricated parts. This research presents preliminary results obtained from an in-progress mechanical characterisation campaign conducted on SLM Ti-6Al-4V specimens. Experimental data from uniaxial strain controlled tests are presented in conjunction with surface hardness measurements and an examination of the microstructural characteristics of the materials. Wrought material data, obtained from testing and the literature are utilised for comparison. Preliminary findings of ongoing research provide an insight in the elastoplastic behaviour anticipated for this class of metals.