332 research outputs found

    A new measurement of zinc metallicity in a DLA at z=3.35

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    We present chemical abundance measurements in the z_abs=3.35045 Damped Lyman-alpha (DLA) system observed in the UVES spectrum of the BAL quasar BR 1117-1329. We measure a neutral hydrogen column density N(HI)=6.9+/-1.7*10^{20} atoms/cm2 and derive mean abundances relative to solar: [Si/H] = -1.26+/-0.13, [Fe/H]=-1.51+/-0.13, [Ni/H]=-1.57+/-0.13, [Cr/H]=-1.36+/-0.13, [Zn/H]=-1.18+/-0.13, [Al/H]>-1.25, [O/H]>-1.25 and [N/H]3. The iron to zinc and chromium to zinc ratios, [Fe/Zn]=-0.33+/-0.05 and [Cr/Zn]=-0.18+/-0.05 demonstrate that the absorber has a low dust content. The nitrogen ratio [N/Si]<-0.98 suggests that the ``secondary'' N production process is taking place in this DLA. Finally, this absorber does not seem to present a convincing alpha-enhancement as shown by the alpha over Fe-peak element ratios: [Si/Fe]=0.25+/-0.06, [Si/Cr]=0.10+/-0.06 and [Si/Zn]=-0.08+/-0.06

    An Implemented of a Real-Time Experimental Setup for Robotic Teleoperation System

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    The development of this work presents the implementation of an experimental platform, which will permit to investigate on a methodology for the design and analysis of a teleoperated system, considering the delay in the communication channel. The project has been developed in partnership with the laboratory of Automatic and Robotics of the Universidad PolitĂ©cnica de Madrid and the Laboratory at the Centro de TecnologĂ­as Avanzadas de Manufactura at the Pontificia Universidad CatĂłlica del PerĂș. The mechanical structure of the arm that is located in the remote side has been built and the electric servomechanism has been mounted to control their movement. The experimental test of the Teleoperation system has been developed. The PC104 card commands the power interface and sensors of the DC motor of each articulation of the arm. Has developed the drives for the management of the operations of the master and the slave: send/reception of position, speed, acceleration and current data through a CAN network. The programs for the interconnection through a LAN network, between the Windows Operating System and the Real-time Operating System (QNX), has been developed. The utility of the developed platform (hardware and software) has been demonstrated

    Explanatory Supplement of the ISOGAL-DENIS Point Source Catalogue

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    We present version 1.0 of the ISOGAL-DENIS Point Source Catalogue (PSC), containing more than 100,000 point sources detected at 7 and/or 15 micron in the ISOGAL survey of the inner Galaxy with the ISOCAM instrument on board the Infrared Space Observatory (ISO). These sources are cross-identified, wherever possible, with near-infrared (0.8-2.2 micron) data from the DENIS survey. The overall surface covered by the ISOGAL survey is about 16 square degrees, mostly (95%) distributed near the Galactic plane (|b| < 1 deg), where the source extraction can become confusion limited and perturbed by the high background emission. Therefore, special care has been taken aimed at limiting the photometric error to ~0.2 magnitude down to a sensitivity limit of typically 10 mJy. The present paper gives a complete description of the entries and the information which can be found in this catalogue, as well as a detailed discussion of the data processing and the quality checks which have been completed. The catalogue is available via the VizieR Service at the Centre de Donn\'ees Astronomiques de Strasbourg (CDS, http://vizier.u-strasbg.fr/viz-bin/VizieR/) and also via the server at the Institut d'Astrophysique de Paris (http://www-isogal.iap.fr/). A more complete version of this paper, including a detailed description of the data processing, is available in electronic form through the ADS service.Comment: 21 pages, 7 figures. A&A in press. Full length version with 32 figures and detailed description of the data processing is available here: http://www-isogal.iap.fr/Publications/ExplSupplFull.ps.g

    The correlation of the Lyman-alpha forest in close pairs and groups of high-redshift quasars: clustering of matter on scales 1-5 Mpc

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    We study the clustering of matter in the intergalactic medium from the Lyman-alpha forests seen in the spectra of pairs or groups of z ~ 2 quasars observed with FORS2 and UVES at the VLT-UT2 Kueyen ESO telescope. The sample consists of five pairs with separations 0.6, 1, 2.1, 2.6 and 4.4 arcmin and a group of four quasars with separations from 2 up to 10 arcmin. This unprecedented data set allows us to measure the transverse flux correlation function for a range of angular scales. Correlations are clearly detectable at separations smaller than 3 arcmin. The shape and correlation length of the transverse correlation function on these scales is in good agreement with those expected from absorption by the photoionized warm intergalactic medium associated with the filamentary and sheet-like structures predicted in CDM-like models for structure formation. At larger separation no significant correlation is detected. Assuming that the absorbing structures are randomly orientated with respect to the line of sight, the comparison of transverse and longitudinal correlation lengths constrains the cosmological parameters (as a modified version of the Alcock & Paczy\'nski test). The present sample is too small to get significant constraints. Using N-body simulations, we investigate the possibility to constrain Ol from future larger samples of QSO pairs with similar separations. The observation of a sample of 30 pairs at 2, 4.5 and 7.5 arcmin should constrain the value of Ol at +- 15 % (2 sigma level). We further use the observed spectra of the group of four quasars, to search for underdense regions in the intergalactic medium. We find a quasi-spherical structure of reduced absorption with radius 12.5 h^{-1} Mpc which we identify as an underdense region.Comment: 11 pages, 10 figures, accepted for publication in MNRA

    Accurate long-term air temperature prediction with Machine Learning models and data reduction techniques

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    In this paper, three customised Artificial Intelligence (AI) frameworks, considering Deep Learning, Machine Learning (ML) algorithms and data reduction techniques, are proposed for a problem of long-term summer air temperature prediction. Specifically, the prediction of the average air temperature in the first and second August fortnights, using input data from previous months, at two different locations (Paris, France) and (Córdoba, Spain), is considered. The target variable, mainly in the first August fortnight, can contain signals of extreme events such as heatwaves, like the heatwave of 2003, which affected France and the Iberian Peninsula. Three different computational frameworks for air temperature prediction are proposed: a Convolutional Neural Network (CNN), with video-to-image translation, several ML approaches including Lasso regression, Decision Trees and Random Forest, and finally a CNN with pre-processing step using Recurrence Plots, which convert time series into images. Using these frameworks, a very good prediction skill has been obtained in both Paris and Córdoba regions, showing that the proposed approaches can be an excellent option for seasonal climate prediction problems.This research has been partially supported by the European Union, through H2020 Project “CLIMATE INTELLIGENCE Extreme events detection, attribution and adaptation design using machine learning (CLINT)”, Ref: 101003876-CLINT. This research has also been partially supported by the project PID2020-115454GB-C21 of the Spanish Ministry of Science and Innovation (MICINN)

    Energy Utilization Analysis and Optimization of Corrective Insoles Manufactured by 3D Printing

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    The foot orthotic insole market is forecast to surpass a value of 3.6 billion USD by 2021. This vast industry continues to rely on foam milling and other subtractive methods of manufacturing, which have proven to be wasteful and inefficient. Leaps in digital manufacturing have enabled the technology to enter a plethora of industries, with the promise of increased customization accompanied with reduced waste generation. Despite boasting these valuable traits, the explosive proliferation of 3D printing in conjunction with mounting pressure to incorporate sustainable practices, means that research must be focused on maximizing the material and energy efficiency of the technology. This paper employs a Design of Experiments (DoE) approach for the optimization of two prefabricated insoles, adjusting percentage infill and layer height to obtain data regarding the effects of these parameters on print time, filament usage volume, and energy consumption. Key conclusions formed from the study were that infill density is the dominant factor effecting material consumption and power usage, whereas layer height has the greatest influence on production time. The data presented in this study has the potential to aid not only in the development of mass producible additive manufactured (AM) insoles, but also to advance the understanding of the environmental impact of AM technologies

    Composite Eco-Friendly Sound Absorbing Materials Made of Recycled Textile Waste and Biopolymers

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    [EN] In recent years, the interest in reusing recycled fibers as building materials has been growing as a consequence of their ability to reduce the production of waste and the use of virgin resources, taking advantage of the potential that fibrous materials may offer to improve thermal and acoustic comfort. Composite panels, made of 100% wool waste fibers and bound by means of either a chitosan solution and a gum Arabic solution, were tested and characterized in terms of acoustic and non-acoustic properties. Samples with a 5 cm thickness and different density values were made to investigate the influence of flow resistivity on the final performance. Experimental results demonstrated that the samples had thermal conductivity ranging between 0.049 and 0.060 W/(m K), well comparable to conventional building materials. Similarly, acoustic results were very promising, showing absorption coefficients that, for the given thickness, were generally higher than 0.5 from 500 Hz on, and higher than 0.9 from 1 kHz on. Finally, the effects of the non-acoustic properties and of the air gap behind the samples on the acoustic behavior were also analyzed, proving that the agreement with absorption values predicted by empirical models was also very good.C.R. scholarship has been funded by the Italian Ministry of Education, University and Research (MIUR), within the National Research Program "PON Ricerca e Innovazione 2014-2020" (grant DOT1748713 N.5).Rubino, C.; Bonet-Aracil, M.; Gisbert Paya, J.; Liuzzi, S.; Stefanizzi, P.; Zamorano CantĂł, M.; Martellotta, F. (2019). Composite Eco-Friendly Sound Absorbing Materials Made of Recycled Textile Waste and Biopolymers. Materials. 12(23):1-18. https://doi.org/10.3390/ma12234020S1181223Joshi, S. ., Drzal, L. ., Mohanty, A. ., & Arora, S. (2004). Are natural fiber composites environmentally superior to glass fiber reinforced composites? Composites Part A: Applied Science and Manufacturing, 35(3), 371-376. doi:10.1016/j.compositesa.2003.09.016Hesterberg, T. W., & Hart, G. A. (2001). Synthetic Vitreous Fibers: A Review of Toxicology Research and Its Impact on Hazard Classification. Critical Reviews in Toxicology, 31(1), 1-53. doi:10.1080/20014091111668Bakatovich, A., Davydenko, N., & Gaspar, F. (2018). Thermal insulating plates produced on the basis of vegetable agricultural waste. Energy and Buildings, 180, 72-82. doi:10.1016/j.enbuild.2018.09.032Martellotta, F., Cannavale, A., De Matteis, V., & Ayr, U. (2018). Sustainable sound absorbers obtained from olive pruning wastes and chitosan binder. Applied Acoustics, 141, 71-78. doi:10.1016/j.apacoust.2018.06.022KymĂ€lĂ€inen, H.-R., & Sjöberg, A.-M. (2008). Flax and hemp fibres as raw materials for thermal insulations. Building and Environment, 43(7), 1261-1269. doi:10.1016/j.buildenv.2007.03.006Zhou, X., Zheng, F., Li, H., & Lu, C. (2010). An environment-friendly thermal insulation material from cotton stalk fibers. Energy and Buildings, 42(7), 1070-1074. doi:10.1016/j.enbuild.2010.01.020Ashour, T., Georg, H., & Wu, W. (2011). Performance of straw bale wall: A case of study. Energy and Buildings, 43(8), 1960-1967. doi:10.1016/j.enbuild.2011.04.001Lim, Z. Y., Putra, A., Nor, M. J. M., & Yaakob, M. Y. (2018). Sound absorption performance of natural kenaf fibres. Applied Acoustics, 130, 107-114. doi:10.1016/j.apacoust.2017.09.012Hosseini Fouladi, M., Ayub, M., & Jailani Mohd Nor, M. (2011). Analysis of coir fiber acoustical characteristics. Applied Acoustics, 72(1), 35-42. doi:10.1016/j.apacoust.2010.09.007Wei, K., Lv, C., Chen, M., Zhou, X., Dai, Z., & Shen, D. (2015). Development and performance evaluation of a new thermal insulation material from rice straw using high frequency hot-pressing. Energy and Buildings, 87, 116-122. doi:10.1016/j.enbuild.2014.11.026Berardi, U., & Iannace, G. (2015). Acoustic characterization of natural fibers for sound absorption applications. Building and Environment, 94, 840-852. doi:10.1016/j.buildenv.2015.05.029Rubino, C., Liuzzi, S., Martellotta, F., & Stefanizzi, P. (2018). Textile wastes in building sector: A review. Modelling, Measurement and Control B, 87(3), 172-179. doi:10.18280/mmc_b.870309Ricciardi, P., Belloni, E., & Cotana, F. (2014). Innovative panels with recycled materials: Thermal and acoustic performance and Life Cycle Assessment. Applied Energy, 134, 150-162. doi:10.1016/j.apenergy.2014.07.112Barbero-Barrera, M. del M., Pombo, O., & Navacerrada, M. de los Á. (2016). Textile fibre waste bindered with natural hydraulic lime. Composites Part B: Engineering, 94, 26-33. doi:10.1016/j.compositesb.2016.03.013Echeverria, C. A., Pahlevani, F., Handoko, W., Jiang, C., Doolan, C., & Sahajwalla, V. (2019). Engineered hybrid fibre reinforced composites for sound absorption building applications. Resources, Conservation and Recycling, 143, 1-14. doi:10.1016/j.resconrec.2018.12.014Leal Filho, W., Ellams, D., Han, S., Tyler, D., Boiten, V. J., Paço, A., 
 Balogun, A.-L. (2019). A review of the socio-economic advantages of textile recycling. Journal of Cleaner Production, 218, 10-20. doi:10.1016/j.jclepro.2019.01.210Muñoz, I., RodrĂ­guez, C., Gillet, D., & M. Moerschbacher, B. (2017). Life cycle assessment of chitosan production in India and Europe. The International Journal of Life Cycle Assessment, 23(5), 1151-1160. doi:10.1007/s11367-017-1290-2Mati-Baouche, N., De Baynast, H., Lebert, A., Sun, S., Lopez-Mingo, C. J. S., Leclaire, P., & Michaud, P. (2014). Mechanical, thermal and acoustical characterizations of an insulating bio-based composite made from sunflower stalks particles and chitosan. Industrial Crops and Products, 58, 244-250. doi:10.1016/j.indcrop.2014.04.022El Hage, R., Khalaf, Y., Lacoste, C., Nakhl, M., Lacroix, P., & Bergeret, A. (2018). A flame retarded chitosan binder for insulating miscanthus/recycled textile fibers reinforced biocomposites. Journal of Applied Polymer Science, 136(13), 47306. doi:10.1002/app.47306Mati-Baouche, N., de Baynast, H., Michaud, P., Dupont, T., & Leclaire, P. (2016). Sound absorption properties of a sunflower composite made from crushed stem particles and from chitosan bio-binder. Applied Acoustics, 111, 179-187. doi:10.1016/j.apacoust.2016.04.021Abuarra, A., Hashim, R., Bauk, S., Kandaiya, S., & Tousi, E. T. (2014). Fabrication and characterization of gum Arabic bonded Rhizophora spp. particleboards. Materials & Design, 60, 108-115. doi:10.1016/j.matdes.2014.03.032Elinwa, A. U., Abdulbasir, G., & Abdulkadir, G. (2018). Gum Arabic as an admixture for cement concrete production. Construction and Building Materials, 176, 201-212. doi:10.1016/j.conbuildmat.2018.04.160Delany, M. E., & Bazley, E. N. (1970). Acoustical properties of fibrous absorbent materials. Applied Acoustics, 3(2), 105-116. doi:10.1016/0003-682x(70)90031-9Johnson, D. L., Koplik, J., & Dashen, R. (1987). Theory of dynamic permeability and tortuosity in fluid-saturated porous media. Journal of Fluid Mechanics, 176(-1), 379. doi:10.1017/s0022112087000727Allard, J., & Champoux, Y. (1992). New empirical equations for sound propagation in rigid frame fibrous materials. The Journal of the Acoustical Society of America, 91(6), 3346-3353. doi:10.1121/1.402824Patnaik, A., Mvubu, M., Muniyasamy, S., Botha, A., & Anandjiwala, R. D. (2015). Thermal and sound insulation materials from waste wool and recycled polyester fibers and their biodegradation studies. Energy and Buildings, 92, 161-169. doi:10.1016/j.enbuild.2015.01.056Brown, R. J. S. (1980). Connection between formation factor for electrical resistivity and fluid‐solid coupling factor in Biot’s equations for acoustic waves in fluid‐filled porous media. GEOPHYSICS, 45(8), 1269-1275. doi:10.1190/1.1441123Pfretzschner, J., & MÂȘ. Rodriguez, R. (1999). Acoustic properties of rubber crumbs. Polymer Testing, 18(2), 81-92. doi:10.1016/s0142-9418(98)00009-9Berryman, J. G. (1980). Confirmation of Biot’s theory. Applied Physics Letters, 37(4), 382-384. doi:10.1063/1.91951Ingard, K. U., & Dear, T. A. (1985). Measurement of acoustic flow resistance. Journal of Sound and Vibration, 103(4), 567-572. doi:10.1016/s0022-460x(85)80024-9Rey, R. del, Alba, J., Arenas, J. P., & Ramis, J. (2013). Technical Notes: Evaluation of Two Alternative Procedures for Measuring Airflow Resistance of Sound Absorbing Materials. Archives of Acoustics, 38(4), 547-554. doi:10.2478/aoa-2013-0064Jerman, M., & ČernĂœ, R. (2012). Effect of moisture content on heat and moisture transport and storage properties of thermal insulation materials. Energy and Buildings, 53, 39-46. doi:10.1016/j.enbuild.2012.07.002Jerman, M., Palomar, I., Kočí, V., & ČernĂœ, R. (2019). Thermal and hygric properties of biomaterials suitable for interior thermal insulation systems in historical and traditional buildings. Building and Environment, 154, 81-88. doi:10.1016/j.buildenv.2019.03.020Gustafsson, S. E. (1991). Transient plane source techniques for thermal conductivity and thermal diffusivity measurements of solid materials. Review of Scientific Instruments, 62(3), 797-804. doi:10.1063/1.1142087Del Rey, R., Berto, L., Alba, J., & Arenas, J. P. (2015). Acoustic characterization of recycled textile materials used as core elements in noise barriers. Noise Control Engineering Journal, 63(5), 439-447. doi:10.3397/1/376339PiĂ©gay, C., GlĂ©, P., Gourdon, E., Gourlay, E., & Marceau, S. (2018). Acoustical model of vegetal wools including two types of fibers. Applied Acoustics, 129, 36-46. doi:10.1016/j.apacoust.2017.06.021Carosio, F., & Alongi, J. (2018). Flame Retardant Multilayered Coatings on Acrylic Fabrics Prepared by One-Step Deposition of Chitosan/Montmorillonite Complexes. Fibers, 6(2), 36. doi:10.3390/fib6020036No, H. K., Meyers, S. P., Prinyawiwatkul, W., & Xu, Z. (2007). Applications of Chitosan for Improvement of Quality and Shelf Life of Foods: A Review. Journal of Food Science, 72(5), R87-R100. doi:10.1111/j.1750-3841.2007.00383.

    Fast pyrolysis of halogenated plastics recovered from waste computers

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    The disposal of waste computers is an issue that is gaining increasing interest around the world. In this paper, results from the fast pyrolysis in a fluidized bed reactor of three different waste computer monitor casings composed of mainly acrylonitrile-butadiene-styrene (ABS) copolymer and two different waste computer body casings composed of mostly poly(vinyl chloride) (PVC) type polymers are presented. Preliminary characterization of the waste plastics was investigated using coupled thermogravimetric analysis-Fourier transform infrared spectrometry (TGA-FT-IR). The results showed that the plastics decomposed in two stages. For the ABS-containing monitor casings, aromatic and aliphatic material were released in the first and second stages. The PVC-containing computer body casing samples showed a first-stage evolution of HCl and a second stage evolution of aromatic and aliphatic material and further HCl. In addition, each of the five plastics was fast-pyrolyzed in a laboratory-scale fluidized bed reactor at 500 °C. The fluidized bed pyrolysis led to the conversion of most of the plastics to pyrolysis oil, although the two PVC computer body cases produced large quantities of HCl. The pyrolysis oils were characterized by GC-MS and it was found that they were chemically very heterogeneous and contained a wide range of aliphatic, aromatic, halogenated, oxygenated, and nitrogenated compounds
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