405 research outputs found

    P-wave and surface wave survey for permafrost analysis in alpine regions

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    We discuss the results of seismic survey to delineate temporal and spatial changes of frozen layer in Alpine environments. The seismic characterization allows us to detect changes of soil deformability properties related to the temperature effect on subsoi

    A new electric streamer for the characterization of river embankments

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    River embankments are linear earth structures, worldwide diffused, commonly used for flood protection. Their integrity and stability are fundamental prerequisites for the protection efficiency they can offer to the increasing frequency and magnitude of extreme flood events associated to changes in climate. Proper characterization and monitoring are essential to verify the construction requirements of newly built structures and to evaluate the durability of aged ones. Considering their linear extent, the characterization requires not only local geotechnical investigations but also the application of efficient and economically affordable methods. This is even more essential when the investigations are performed after, or in foresee of, significant flood events, when these structures get stressed and timing of the surveys is crucial. In these conditions, new survey methodologies, with the use of mobile systems, are a main research topic. In this paper the application of a new electric streamer, specifically designed for these aims, is presented. The technical solutions adopted for its construction are described and its application to the characterization of three different river embankments is presented. These case studies were chosen in accordance with the Po River Interregional Agency (AIPO), which is the authority deputed to the safety of flood protection structures in North-West Italy, along the hydrographic network of the Po River. The selected embankments are all earth structures, constructed above the natural alluvial soils, but are characterized by different conditions and challenges. The results obtained with the new system were comparable to standard Electric Resistivity Tomography (ERT) methods. The new system has significant advantages in terms of reducing the survey time, improving the efficiency of the surveys and increasing the data coverage. This resulted in a better definition of potentially dangerous anomalies

    Thermo-oxidative characterisation of the residues from persimmon harvest for its use in energy recovery processes

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    [EN] The residues from the harvest of persimmon fruit will be thermally valorised by means of high temperature reactions within a spouted bed reactor. With the aim to obtain valuable information for the design of the device, the thermo-chemical processes were simulated by multi-rate linear non-isothermal Thermogravimetric Analysis (TGA) using O-2 as carrier gas. In addition, a set of analyses were carried out using Ar as carrier gas in order to evaluate the influence of the atmosphere (oxidative or inert conditions) on the decomposition of the samples evaluating the reactions of pyrolysis. The release of gases was monitored by Evolved Gas Analysis (EGA) with in-line Fourier Transformed Infrared (FT-IR) analysis. The thermochemical reaction was mathematically described through the definition of the main kinetic parameters: activation energy (Ea), pre-exponential factor (In A) and model and order of reaction (n). The so-called kinetic triplet was calculated through the application of a methodology based on complementary isoconversional methods. These results will be the initial parameters that will help design the Spouted Bed Reactor and it is envisaged that they will be used in computer simulation software to achieve a better understanding of the process to obtain the optimum operational parameters. (C) 2016 Published by Elsevier B.V.Moliner, C.; Aguilar, A.; Bosio, B.; Arato, E.; Ribes-Greus, A. (2016). Thermo-oxidative characterisation of the residues from persimmon harvest for its use in energy recovery processes. Fuel Processing Technology. 152:421-429. https://doi.org/10.1016/j.fuproc.2016.07.008S42142915

    Performance of Computer Systems; Proceedings of the 4th International Symposium on Modelling and Performance Evaluation of Computer Systems, Vienna, Austria, February 6-8, 1979

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    These proceedings are a collection of contributions to computer system performance, selected by the usual refereeing process from papers submitted to the symposium, as well as a few invited papers representing significant novel contributions made during the last year. They represent the thrust and vitality of the subject as well as its capacity to identify important basic problems and major application areas. The main methodological problems appear in the underlying queueing theoretic aspects, in the deterministic analysis of waiting time phenomena, in workload characterization and representation, in the algorithmic aspects of model processing, and in the analysis of measurement data. Major areas for applications are computer architectures, data bases, computer networks, and capacity planning. The international importance of the area of computer system performance was well reflected at the symposium by participants from 19 countries. The mixture of participants was also evident in the institutions which they represented: 35% from universities, 25% from governmental research organizations, but also 30% from industry and 10% from non-research government bodies. This proves that the area is reaching a stage of maturity where it can contribute directly to progress in practical problems

    Sensitivity Analysis and Validation of a Two Fluid Method (TFM) model for a Spouted Bed

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    This work was funded through the LIFE LIBERNITRATE project (LIFE16 ENV/ES/000419) in the framework of the LIFE+ funding programme. EA and AMF acknowledge the traineeship Erasmus+ grant for Laura Ong.Peer reviewedPostprin

    Evaluation of Chloride Diffusion and Corrosion Resistance in Reinforced Concrete Using Internal Curing and Shrinkage Reducing Admixtures

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    The properties of high-performance concretes obtained by the internal curing technique were studied in the fresh and hardened states. In some of the concrete mixtures, fine normal weight aggregates were replaced with lightweight aggregates (LWA) at 20 % vol. and ordinary portland cement was replaced by pulverized class F fly ash at 20 % by mass. Additionally, some mixtures were prepared including a shrinkage-reducing admixture, either as part of the mixing water or pre-soaked into the lightweight fine aggregates. The prepared concretes were subjected to degradation tests, such as accelerated carbonation and chloride ion deterioration. In addition, the reinforced concretes were analyzed through electrochemical corrosion tests with the linear polarization resistance technique. It was found that the internally cured concretes presented a mechanical resistance similar to those reported for the reference concretes (conventional concretes), but provided a higher resistance to carbonation, rapid penetration of chloride ions, and a lower chloride ion diffusion coefficient. The reinforcing steel structure in the internally cured concretes showed lower corrosion currents (Icorr) and corrosion potentials (Ecorr) in comparison to the reference concretes. Therefore, the use of the internal curing technique in concretes with pre-soaking in either water or a solution of shrinkage-reducing admixture can be considered as a viable alternative to extend the service life of concrete structures in contact with harmful environments
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