Glory revealed in disk-integrated photometry of Venus

Context. Reflected light from a spatially unresolved planet yields unique insight into the overall optical properties of the planet cover. Glories are optical phenomena caused by light that is backscattered within spherical droplets following a narrow distribution of sizes; they are well known on Earth as localised features above liquid clouds. Aims. Here we report the first evidence for a glory in the disk-integrated photometry of Venus and, in turn, of any planet. Methods. We used previously published phase curves of the planet that were reproduced over the full range of phase angles with model predictions based on a realistic description of the Venus atmosphere. We assumed that the optical properties of the planet as a whole can be described by a uniform and stable cloud cover, an assumption that agrees well with observational evidence. Results. We specifically show that the measured phase curves mimic the scattering properties of the Venus upper-cloud micron-sized aerosols, also at the small phase angles at which the glory occurs, and that the glory contrast is consistent with what is expected after multiple scattering of photons. In the optical, the planet appears to be brighter at phase angles of 11-13 deg than at full illumination; it undergoes a maximum dimming of up to 10 percent at phases in between. Conclusions. Glories might potentially indicate spherical droplets and, thus, extant liquid clouds in the atmospheres of exoplanets. A prospective detection will require exquisite photometry at the small planet-star separations of the glory phase angles.Comment: In press. Astronomy & Astrophysics. Letter to the Editor; 201

Limb imaging of the Venus O2 visible nightglow with the Venus Monitoring Camera

We investigated the Venus O2 visible nightglow with imagery from the Venus Monitoring Camera on Venus Express. Drawing from data collected between April 2007 and January 2011, we study the global distribution of this emission, discovered in the late 70s by the Venera 9 and 10 missions. The inferred limb-viewing intensities are on the order of 150 kiloRayleighs at the lower latitudes and seem to drop somewhat towards the poles. The emission is generally stable, although there are episodes when the intensities rise up to 500 kR. We compare a set of Venus Monitoring Camera observations with coincident measurements of the O2 nightglow at 1.27 {\mu}m made with the Visible and Infrared Thermal Imaging Spectrometer, also on Venus Express. From the evidence gathered in this and past works, we suggest a direct correlation between the instantaneous emissions from the two O2 nightglow systems. Possible implications regarding the uncertain origin of the atomic oxygen green line at 557.7 nm are noted.Comment: 7 pages, 3 figure

Analysis of the Machinability of Carbon Fiber Composite Materials in Function of Tool Wear and Cutting Parameters Using the Artificial Neural Network Approach

[EN] Local delamination is the most undesirable damage associated with drilling carbon fiber reinforced composite materials (CFRPs). This defect reduces the structural integrity of the material, which affects the residual strength of the assembled components. A positive correlation between delamination extension and thrust force during the drilling process is reported in literature. The abrasive effect of the carbon fibers modifies the geometry of the fresh tool, which increases the thrust force and, in consequence, the induced damage in the workpiece. Using a control system based on an artificial neural network (ANN), an analysis of the influence of the tool wear in the thrust force during the drilling of CFRP laminate to reduce the damage is developed. The spindle speed, feed rate, and drill point angle are also included as input parameters of the study. The training and testing of the ANN model are carried out with experimental drilling tests using uncoated carbide helicoidal tools. The data were trained using error-back propagation-training algorithm (EBPTA). The use of the neural network rapidly provides results of the thrust force evolution in function of the tool wear and cutting parameters. The obtained results can be used by the industry as a guide to control the impact of the wear of the tool in the quality of the finished workpiece.The Ministry of Economy and Competitiveness of Spain, projects DPI2017-89197-C2-1-R and DPI2017-89197-C2-2-R] and the Ministry of Science, Innovation and Universities, grant number [FJCI-2017-34910], funded this research.Feito-Sánchez, N.; Muñoz-Sánchez, A.; Diaz-Alvarez, A.; Loya, J. (2019). Analysis of the Machinability of Carbon Fiber Composite Materials in Function of Tool Wear and Cutting Parameters Using the Artificial Neural Network Approach. Materials. 12(17):1-13. https://doi.org/10.3390/ma12172747S1131217Huang, X. (2009). Fabrication and Properties of Carbon Fibers. Materials, 2(4), 2369-2403. doi:10.3390/ma2042369Yang, Y., Jiang, Y., Liang, H., Yin, X., & Huang, Y. (2019). Study on Tensile Properties of CFRP Plates under Elevated Temperature Exposure. Materials, 12(12), 1995. doi:10.3390/ma12121995Liu, D., Tang, Y., & Cong, W. L. (2012). A review of mechanical drilling for composite laminates. Composite Structures, 94(4), 1265-1279. doi:10.1016/j.compstruct.2011.11.024Hocheng, H., & Tsao, C. . (2003). Comprehensive analysis of delamination in drilling of composite materials with various drill bits. Journal of Materials Processing Technology, 140(1-3), 335-339. doi:10.1016/s0924-0136(03)00749-0Hocheng, H., & Tsao, C. C. (2006). Effects of special drill bits on drilling-induced delamination of composite materials. International Journal of Machine Tools and Manufacture, 46(12-13), 1403-1416. doi:10.1016/j.ijmachtools.2005.10.004Hocheng, H., & Tsao, C. C. (2005). The path towards delamination-free drilling of composite materials. Journal of Materials Processing Technology, 167(2-3), 251-264. doi:10.1016/j.jmatprotec.2005.06.039Davim, J. ., & Reis, P. (2003). Study of delamination in drilling carbon fiber reinforced plastics (CFRP) using design experiments. Composite Structures, 59(4), 481-487. doi:10.1016/s0263-8223(02)00257-xSardiñas, R. Q., Reis, P., & Davim, J. P. (2006). Multi-objective optimization of cutting parameters for drilling laminate composite materials by using genetic algorithms. Composites Science and Technology, 66(15), 3083-3088. doi:10.1016/j.compscitech.2006.05.003Fernandes, M., & Cook, C. (2006). Drilling of carbon composites using a one shot drill bit. Part I: Five stage representation of drilling and factors affecting maximum force and torque. International Journal of Machine Tools and Manufacture, 46(1), 70-75. doi:10.1016/j.ijmachtools.2005.03.015Fernandes, M., & Cook, C. (2006). Drilling of carbon composites using a one shot drill bit. Part II: empirical modeling of maximum thrust force. International Journal of Machine Tools and Manufacture, 46(1), 76-79. doi:10.1016/j.ijmachtools.2005.03.016Feito, N., Diaz-Álvarez, A., Cantero, J. L., Rodríguez-Millán, M., & Miguélez, H. (2015). Experimental analysis of special tool geometries when drilling woven and multidirectional CFRPs. Journal of Reinforced Plastics and Composites, 35(1), 33-55. doi:10.1177/0731684415612931Feito, N., Díaz-Álvarez, J., Díaz-Álvarez, A., Cantero, J., & Miguélez, M. (2014). Experimental Analysis of the Influence of Drill Point Angle and Wear on the Drilling of Woven CFRPs. Materials, 7(6), 4258-4271. doi:10.3390/ma7064258Iliescu, D., Gehin, D., Gutierrez, M. E., & Girot, F. (2010). Modeling and tool wear in drilling of CFRP. International Journal of Machine Tools and Manufacture, 50(2), 204-213. doi:10.1016/j.ijmachtools.2009.10.004Abrão, A. M., Rubio, J. C. C., Faria, P. E., & Davim, J. P. (2008). The effect of cutting tool geometry on thrust force and delamination when drilling glass fibre reinforced plastic composite. Materials & Design, 29(2), 508-513. doi:10.1016/j.matdes.2007.01.016Rawat, S., & Attia, H. (2009). Wear mechanisms and tool life management of WC–Co drills during dry high speed drilling of woven carbon fibre composites. Wear, 267(5-8), 1022-1030. doi:10.1016/j.wear.2009.01.031Fernández-Pérez, J., Cantero, J. L., Díaz-Álvarez, J., & Miguélez, M. H. (2017). Influence of cutting parameters on tool wear and hole quality in composite aerospace components drilling. Composite Structures, 178, 157-161. doi:10.1016/j.compstruct.2017.06.043Tsao, C. C., & Hocheng, H. (2007). Effect of tool wear on delamination in drilling composite materials. International Journal of Mechanical Sciences, 49(8), 983-988. doi:10.1016/j.ijmecsci.2007.01.001Chen, W.-C. (1997). Some experimental investigations in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates. International Journal of Machine Tools and Manufacture, 37(8), 1097-1108. doi:10.1016/s0890-6955(96)00095-8Murphy, C., Byrne, G., & Gilchrist, M. D. (2002). The performance of coated tungsten carbide drills when machining carbon fibre-reinforced epoxy composite materials. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 216(2), 143-152. doi:10.1243/0954405021519735Fernández-Pérez, J., Cantero, J., Díaz-Álvarez, J., & Miguélez, M. (2019). Hybrid Composite-Metal Stack Drilling with Different Minimum Quantity Lubrication Levels. Materials, 12(3), 448. doi:10.3390/ma12030448Tsao, C. ., & Hocheng, H. (2004). Taguchi analysis of delamination associated with various drill bits in drilling of composite material. International Journal of Machine Tools and Manufacture, 44(10), 1085-1090. doi:10.1016/j.ijmachtools.2004.02.019Palanikumar, K., Prakash, S., & Shanmugam, K. (2008). Evaluation of Delamination in Drilling GFRP Composites. Materials and Manufacturing Processes, 23(8), 858-864. doi:10.1080/10426910802385026Mohan, N. S., Kulkarni, S. M., & Ramachandra, A. (2007). Delamination analysis in drilling process of glass fiber reinforced plastic (GFRP) composite materials. Journal of Materials Processing Technology, 186(1-3), 265-271. doi:10.1016/j.jmatprotec.2006.12.043Srinivasa Rao, B., Rudramoorthy, R., Srinivas, S., & Nageswara Rao, B. (2008). Effect of drilling induced damage on notched tensile and pin bearing strengths of woven GFR-epoxy composites. Materials Science and Engineering: A, 472(1-2), 347-352. doi:10.1016/j.msea.2007.03.023Enemuoh, E. U., El-Gizawy, A. S., & Chukwujekwu Okafor, A. (2001). An approach for development of damage-free drilling of carbon fiber reinforced thermosets. International Journal of Machine Tools and Manufacture, 41(12), 1795-1814. doi:10.1016/s0890-6955(01)00035-9Saravanan, M., Ramalingam, D., Manikandan, G., & Kaarthikeyen, R. R. (2012). Multi Objective Optimization of Drilling Parameters Using Genetic Algorithm. Procedia Engineering, 38, 197-207. doi:10.1016/j.proeng.2012.06.027Feito, N., Milani, A. S., & Muñoz-Sánchez, A. (2015). Drilling optimization of woven CFRP laminates under different tool wear conditions: a multi-objective design of experiments approach. Structural and Multidisciplinary Optimization, 53(2), 239-251. doi:10.1007/s00158-015-1324-yKrishnaraj, V., Prabukarthi, A., Ramanathan, A., Elanghovan, N., Senthil Kumar, M., Zitoune, R., & Davim, J. P. (2012). Optimization of machining parameters at high speed drilling of carbon fiber reinforced plastic (CFRP) laminates. Composites Part B: Engineering, 43(4), 1791-1799. doi:10.1016/j.compositesb.2012.01.007Krishnamoorthy, A., Rajendra Boopathy, S., Palanikumar, K., & Paulo Davim, J. (2012). Application of grey fuzzy logic for the optimization of drilling parameters for CFRP composites with multiple performance characteristics. Measurement, 45(5), 1286-1296. doi:10.1016/j.measurement.2012.01.008Abhishek, K., Datta, S., & Mahapatra, S. S. (2014). Optimization of thrust, torque, entry, and exist delamination factor during drilling of CFRP composites. The International Journal of Advanced Manufacturing Technology, 76(1-4), 401-416. doi:10.1007/s00170-014-6199-3El Kadi, H. (2006). Modeling the mechanical behavior of fiber-reinforced polymeric composite materials using artificial neural networks—A review. Composite Structures, 73(1), 1-23. doi:10.1016/j.compstruct.2005.01.020Altinkok, N., & Koker, R. (2004). Neural network approach to prediction of bending strength and hardening behaviour of particulate reinforced (Al–Si–Mg)-aluminium matrix composites. Materials & Design, 25(7), 595-602. doi:10.1016/j.matdes.2004.02.014Karnik, S. R., Gaitonde, V. N., Rubio, J. C., Correia, A. E., Abrão, A. M., & Davim, J. P. (2008). Delamination analysis in high speed drilling of carbon fiber reinforced plastics (CFRP) using artificial neural network model. Materials & Design, 29(9), 1768-1776. doi:10.1016/j.matdes.2008.03.014Altinkok, N., & Koker, R. (2006). Modelling of the prediction of tensile and density properties in particle reinforced metal matrix composites by using neural networks. Materials & Design, 27(8), 625-631. doi:10.1016/j.matdes.2005.01.005Stone, R., & Krishnamurthy, K. (1996). A neural network thrust force controller to minimize delamination during drilling of graphite-epoxy laminates. International Journal of Machine Tools and Manufacture, 36(9), 985-1003. doi:10.1016/0890-6955(96)00013-2Kuo, C.-F. J., Chang, C.-D., Su, T.-L., & Fu, C.-T. (2008). Optimization of the Dyeing Process and Prediction of Quality Characteristics on Elastic Fiber Blending Fabrics. Polymer-Plastics Technology and Engineering, 47(7), 678-687. doi:10.1080/03602550802129569Chen, W.-C., Fu, G.-L., Tai, P.-H., & Deng, W.-J. (2009). Process parameter optimization for MIMO plastic injection molding via soft computing. Expert Systems with Applications, 36(2), 1114-1122. doi:10.1016/j.eswa.2007.10.020Ko, Y.-D., Moon, P., Kim, C. E., Ham, M.-H., Myoung, J.-M., & Yun, I. (2009). Modeling and optimization of the growth rate for ZnO thin films using neural networks and genetic algorithms. Expert Systems with Applications, 36(2), 4061-4066. doi:10.1016/j.eswa.2008.03.010Faraz, A., Biermann, D., & Weinert, K. (2009). Cutting edge rounding: An innovative tool wear criterion in drilling CFRP composite laminates. International Journal of Machine Tools and Manufacture, 49(15), 1185-1196. doi:10.1016/j.ijmachtools.2009.08.002Ashrafi, H. R., Jalal, M., & Garmsiri, K. (2010). Prediction of load–displacement curve of concrete reinforced by composite fibers (steel and polymeric) using artificial neural network. Expert Systems with Applications, 37(12), 7663-7668. doi:10.1016/j.eswa.2010.04.076Levenberg, K. (1944). A method for the solution of certain non-linear problems in least squares. Quarterly of Applied Mathematics, 2(2), 164-168. doi:10.1090/qam/10666Khashaba, U. A., El-Sonbaty, I. A., Selmy, A. I., & Megahed, A. A. (2010). Machinability analysis in drilling woven GFR/epoxy composites: Part II – Effect of drill wear. Composites Part A: Applied Science and Manufacturing, 41(9), 1130-1137. doi:10.1016/j.compositesa.2010.04.011Heisel, U., & Pfeifroth, T. (2012). 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Multilayer hazes over Saturn’s hexagon from Cassini ISS limb images

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Aprendizaje y educación afectivo-sexual: una revisión de los planteamientos iniciales del aprendizaje de las cuestiones sexuales

[Resumen] La importancia de analizar cómo se produce el aprendizaje sexual así como las fuentes más utilizadas para el mismo, resulta de gran interés para progresar en el desarrollo de la educación afectivo - sexual y para que las instituciones educativas participen y se responsabilicen en el desarrollo de un currículum comprensivo de la misma. En este trabajo realizamos unas revisión acerca de cómo se ha desarrollado, en los inicios de la educación sexual, el aprendizaje de contenidos vinculados a la sexualidad, las fuentes de información más usadas en el ámbito de la sexualidad, así como las técnicas de trabajo que han favorecido la implantación de la educación afectivo sexual en las escuelas

Full control of the spin-wave damping in a magnetic insulator using spin-orbit torque

Hamadeh, A. et al.© 2014 American Physical Society. It is demonstrated that the threshold current for damping compensation can be reached in a 5  μm diameter YIG(20  nm)|Pt(7  nm) disk. The demonstration rests upon the measurement of the ferromagnetic resonance linewidth as a function of Idc using a magnetic resonance force microscope (MRFM). It is shown that the magnetic losses of spin-wave modes existing in the magnetic insulator can be reduced or enhanced by at least a factor of 5 depending on the polarity and intensity of an in-plane dc current Idc flowing through the adjacent normal metal with strong spin-orbit interaction. Complete compensation of the damping of the fundamental mode by spin-orbit torque is reached for a current density of ∼3×1011  A⋅m−2, in agreement with theoretical predictions. At this critical threshold the MRFM detects a small change of static magnetization, a behavior consistent with the onset of an auto-oscillation regime.This research was supported by the French Grants Trinidad (ASTRID 2012 program), by the RTRA Triangle de la Physique grant Spinoscopy, and by the Deutsche Forschungsgemeinschaft. S. O. D. and V. V. N. acknowledges respectively support from the Russian programs Megagrant No. 2013-220-04-329 and competitive growth of KFU.Peer Reviewe

Numerical Modelling of Ballistic Impact Response at Low Velocity in Aramid Fabrics

[EN] In this study, the effect of the impact angle of a projectile during low-velocity impact on Kevlar fabrics has been investigated using a simplified numerical model. The implementation of mesoscale models is complex and usually involves long computation time, in contrast to the practical industry needs to obtain accurate results rapidly. In addition, when the simulation includes more than one layer of composite ply, the computational time increases even in the case of hybrid models. With the goal of providing useful and rapid prediction tools to the industry, a simplified model has been developed in this work. The model offers an advantage in the reduced computational time compared to a full 3D model (around a 90% faster). The proposed model has been validated against equivalent experimental and numerical results reported in the literature with acceptable deviations and accuracies for design requirements. The proposed numerical model allows the study of the influence of the geometry on the impact response of the composite. Finally, after a parametric study related to the number of layers and angle of impact, using a response surface methodology, a mechanistic model and a surface diagram have been presented in order to help with the calculation of the ballistic limit.This research was funded by the Ministry of Economy and Competitiveness from Spain, grant number BES-2012-055162 and the international collaborations subprogram under the reference EEBB-I-2016-11586.Feito-Sánchez, N.; Loya, J.; Muñoz-Sánchez, A.; Das, R. (2019). Numerical Modelling of Ballistic Impact Response at Low Velocity in Aramid Fabrics. Materials. 12(13):1-15. https://doi.org/10.3390/ma121320871151213Tabiei, A., & Nilakantan, G. (2008). Ballistic Impact of Dry Woven Fabric Composites: A Review. Applied Mechanics Reviews, 61(1). doi:10.1115/1.2821711Lim, C. ., Tan, V. B. ., & Cheong, C. . (2002). Perforation of high-strength double-ply fabric system by varying shaped projectiles. International Journal of Impact Engineering, 27(6), 577-591. doi:10.1016/s0734-743x(02)00004-0Tan, V. B. ., Lim, C. ., & Cheong, C. . (2003). Perforation of high-strength fabric by projectiles of different geometry. International Journal of Impact Engineering, 28(2), 207-222. doi:10.1016/s0734-743x(02)00055-6Shim, V. P. W., Tan, V. B. C., & Tay, T. E. (1995). Modelling deformation and damage characteristics of woven fabric under small projectile impact. International Journal of Impact Engineering, 16(4), 585-605. doi:10.1016/0734-743x(94)00063-3Park, Y., Kim, Y., Baluch, A. H., & Kim, C.-G. (2014). Empirical study of the high velocity impact energy absorption characteristics of shear thickening fluid (STF) impregnated Kevlar fabric. International Journal of Impact Engineering, 72, 67-74. doi:10.1016/j.ijimpeng.2014.05.007Taraghi, I., Fereidoon, A., & Taheri-Behrooz, F. (2014). Low-velocity impact response of woven Kevlar/epoxy laminated composites reinforced with multi-walled carbon nanotubes at ambient and low temperatures. Materials & Design, 53, 152-158. doi:10.1016/j.matdes.2013.06.051Nilakantan, G., Merrill, R. L., Keefe, M., Gillespie, J. W., & Wetzel, E. D. (2015). Experimental investigation of the role of frictional yarn pull-out and windowing on the probabilistic impact response of kevlar fabrics. Composites Part B: Engineering, 68, 215-229. doi:10.1016/j.compositesb.2014.08.033López-Gálvez, H., Rodriguez-Millán, M., Feito, N., & Miguelez, H. (2016). A method for inter-yarn friction coefficient calculation for plain wave of aramid fibers. Mechanics Research Communications, 74, 52-56. doi:10.1016/j.mechrescom.2016.04.004Duan, Y., Keefe, M., Bogetti, T. A., Cheeseman, B. A., & Powers, B. (2006). A numerical investigation of the influence of friction on energy absorption by a high-strength fabric subjected to ballistic impact. International Journal of Impact Engineering, 32(8), 1299-1312. doi:10.1016/j.ijimpeng.2004.11.005Cunniff, P. M. (1992). An Analysis of the System Effects in Woven Fabrics under Ballistic Impact. Textile Research Journal, 62(9), 495-509. doi:10.1177/004051759206200902Pan, N., Lin, Y., Wang, X., & Postle, R. (2000). An Oblique Fiber Bundle Test and Analysis. Textile Research Journal, 70(8), 671-674. doi:10.1177/004051750007000803Ha-Minh, C., Imad, A., Boussu, F., & Kanit, T. (2016). Experimental and numerical investigation of a 3D woven fabric subjected to a ballistic impact. International Journal of Impact Engineering, 88, 91-101. doi:10.1016/j.ijimpeng.2015.08.011Chocron Benloulo, I. S., Rodríguez, J., Martínez, M. A., & Sánchez Gálvez, V. (1997). Dynamic tensile testing of aramid and polyethylene fiber composites. International Journal of Impact Engineering, 19(2), 135-146. doi:10.1016/s0734-743x(96)00017-6Cheeseman, B. A., & Bogetti, T. A. (2003). Ballistic impact into fabric and compliant composite laminates. Composite Structures, 61(1-2), 161-173. doi:10.1016/s0263-8223(03)00029-1Rodriguez, J., Chocron, I. S., Martinez, M. A., & Sánchez-Gálvez, V. (1996). High strain rate properties of aramid and polyethylene woven fabric composites. Composites Part B: Engineering, 27(2), 147-154. doi:10.1016/1359-8368(95)00036-4Garcia, C., Trendafilova, I., & Zucchelli, A. (2018). The Effect of Polycaprolactone Nanofibers on the Dynamic and Impact Behavior of Glass Fibre Reinforced Polymer Composites. Journal of Composites Science, 2(3), 43. doi:10.3390/jcs2030043Garcia, C., & Trendafilova, I. (2019). Triboelectric sensor as a dual system for impact monitoring and prediction of the damage in composite structures. Nano Energy, 60, 527-535. doi:10.1016/j.nanoen.2019.03.070ARUNIIT, A., KERS, J., GOLJANDIN, D., SAARNA, M., TALL, K., MAJAK, J., & HERRANEN, H. (2011). Particulate Filled Composite Plastic Materials from Recycled Glass Fibre Reinforced Plastics. Materials Science, 17(3). doi:10.5755/j01.ms.17.3.593Ramaiah, G. B., Chennaiah, R. Y., & Satyanarayanarao, G. K. (2010). Investigation and modeling on protective textiles using artificial neural networks for defense applications. Materials Science and Engineering: B, 168(1-3), 100-105. doi:10.1016/j.mseb.2009.12.029Lopes, C. S., Seresta, O., Coquet, Y., Gürdal, Z., Camanho, P. P., & Thuis, B. (2009). Low-velocity impact damage on dispersed stacking sequence laminates. Part I: Experiments. Composites Science and Technology, 69(7-8), 926-936. doi:10.1016/j.compscitech.2009.02.009Duan, Y., Keefe, M., Bogetti, T. A., & Cheeseman, B. A. (2005). Modeling the role of friction during ballistic impact of a high-strength plain-weave fabric. Composite Structures, 68(3), 331-337. doi:10.1016/j.compstruct.2004.03.026Rao, M. P., Duan, Y., Keefe, M., Powers, B. M., & Bogetti, T. A. (2009). Modeling the effects of yarn material properties and friction on the ballistic impact of a plain-weave fabric. Composite Structures, 89(4), 556-566. doi:10.1016/j.compstruct.2008.11.012Nilakantan, G., Keefe, M., Wetzel, E. D., Bogetti, T. A., & Gillespie, J. W. (2011). Computational modeling of the probabilistic impact response of flexible fabrics. Composite Structures, 93(12), 3163-3174. doi:10.1016/j.compstruct.2011.06.013Nilakantan, G., & Gillespie, J. W. (2012). Ballistic impact modeling of woven fabrics considering yarn strength, friction, projectile impact location, and fabric boundary condition effects. Composite Structures, 94(12), 3624-3634. doi:10.1016/j.compstruct.2012.05.030Nilakantan, G., Wetzel, E. D., Bogetti, T. A., & Gillespie, J. W. (2012). Finite element analysis of projectile size and shape effects on the probabilistic penetration response of high strength fabrics. Composite Structures, 94(5), 1846-1854. doi:10.1016/j.compstruct.2011.12.028Nilakantan, G., Wetzel, E. D., Bogetti, T. A., & Gillespie, J. W. (2013). A deterministic finite element analysis of the effects of projectile characteristics on the impact response of fully clamped flexible woven fabrics. Composite Structures, 95, 191-201. doi:10.1016/j.compstruct.2012.07.023Nilakantan, G., & Nutt, S. (2014). Effects of fabric target shape and size on the V50 ballistic impact response of soft body armor. Composite Structures, 116, 661-669. doi:10.1016/j.compstruct.2014.06.002Grujicic, M., Bell, W. C., Arakere, G., He, T., & Cheeseman, B. A. (2009). A meso-scale unit-cell based material model for the single-ply flexible-fabric armor. Materials & Design, 30(9), 3690-3704. doi:10.1016/j.matdes.2009.02.008Grujicic, M., Arakere, G., He, T., Bell, W. C., Glomski, P. S., & Cheeseman, B. A. (2009). Multi-scale ballistic material modeling of cross-plied compliant composites. 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Identification of the optical and near-infrared counterpart of GRS 1758-258

Context. Understood to be a microquasar in the Galactic center region, GRS 1758-258 has not yet been unambiguously identified to have an optical/near-infrared counterpart, mainly because of the high absorption and the historic lack of suitable astrometric stars, which led to the use of secondary astrometric solutions. Although it is considered with 1E 1740.7-2942 as the prototypical microquasar in the Galactic center region, the Galactic origin of both sources has not yet been confirmed. Aims. We attempt to improve previous astrometry to identify a candidate counterpart to GRS 1758-258. We present observations with the Gran Telescopio de Canarias (GTC), in which we try to detect any powerful emission lines that would infer an extragalactic origin of this source. Methods. We use modern star catalogues to reanalyze archival images of the GRS 1758-258 field in the optical and near-infrared wavelengths, and compute a new astrometric solution. We also reanalyzed archival radio data of GRS 1758-258 to determine a new and more accurate radio position. Results. Our improved astrometric solution for the GRS 1758-258 field represents a significant advancement on previous works and allows us to identify a single optical/near-infrared source, which we propose as the counterpart of GRS 1758-258. The GTC spectrum of this source is however of low signal-to-noise ratio and does not rule out a Galactic origin. Hence, new spectral observations are required to confirm or discard a Galactic nature.Comment: 4 pages, 3 figures, accepted by Astronomy and Astrophysic