2,903 research outputs found

    Suitable Approximations for the Self-Accelerating Parameters in Iterative Methods With Memory

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    This research was supported by PGC2018-095896-B-C22 (MCIU/AEI/FEDER, UE).Chicharro, FI.; Garrido, N.; Cordero Barbero, A.; Torregrosa Sánchez, JR. (2020). Suitable Approximations for the Self-Accelerating Parameters in Iterative Methods With Memory. 42-47. http://hdl.handle.net/10251/179836424

    Study of the dynamics of third-order iterative methods on quadratic polynomials

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    In this paper, we analyse the dynamical behaviour of the operators associated with multi-point interpolation iterative methods and frozen derivative methods, for solving nonlinear equations, applied on second-degree complex polynomials. We obtain that, in both cases, the Julia set is connected and separates the basins of attraction of the roots of the polynomial. Moreover, the Julia set of the operator associated with multi-point interpolation methods is the same as the Newton operator, although it is more complicated for the frozen derivative operator. We explain these differences by obtaining the conjugacy function of each method and by showing that the operators associated with Newton's method and multi-point interpolation methods are both conjugate to powers of z.The authors thank Professors X. Jarque and A. Garijo for their help. The authors also thank the referees for their valuable comments and suggestions that have improved the content of this paper. This research was supported by Ministerio de Ciencia y Tecnologia MTM2011-28636-C02-02 and by Vicerrectorado de Invetigacion, Universitat Politecnica de Valencia, PAID-06-2010-2285Cordero Barbero, A.; Torregrosa Sánchez, JR.; Vindel Cañas, P. (2012). Study of the dynamics of third-order iterative methods on quadratic polynomials. International Journal of Computer Mathematics. 89(13):1826-1836. https://doi.org/10.1080/00207160.2012.687446S182618368913Amat, S., Busquier, S., & Plaza, S. (2006). A construction of attracting periodic orbits for some classical third-order iterative methods. Journal of Computational and Applied Mathematics, 189(1-2), 22-33. doi:10.1016/j.cam.2005.03.049Amat, S., Bermúdez, C., Busquier, S., & Plaza, S. (2008). On the dynamics of the Euler iterative function. Applied Mathematics and Computation, 197(2), 725-732. doi:10.1016/j.amc.2007.08.086Amat, S., Busquier, S., & Plaza, S. (2010). Chaotic dynamics of a third-order Newton-type method. Journal of Mathematical Analysis and Applications, 366(1), 24-32. doi:10.1016/j.jmaa.2010.01.047Blanchard, P. (1995). The dynamics of Newton’s method. Proceedings of Symposia in Applied Mathematics, 139-154. doi:10.1090/psapm/049/1315536Cordero, A., & Torregrosa, J. R. (2010). On interpolation variants of Newton’s method for functions of several variables. Journal of Computational and Applied Mathematics, 234(1), 34-43. doi:10.1016/j.cam.2009.12.002Cordero, A., Hueso, J. L., Martínez, E., & Torregrosa, J. R. (2009). Multi-Point Iterative Methods for Systems of Nonlinear Equations. Lecture Notes in Control and Information Sciences, 259-267. doi:10.1007/978-3-642-02894-6_25Cordero, A., Hueso, J. L., Martínez, E., & Torregrosa, J. R. (2010). Iterative methods for use with nonlinear discrete algebraic models. Mathematical and Computer Modelling, 52(7-8), 1251-1257. doi:10.1016/j.mcm.2010.02.028Curry, J. H., Garnett, L., & Sullivan, D. (1983). On the iteration of a rational function: Computer experiments with Newton’s method. Communications in Mathematical Physics, 91(2), 267-277. doi:10.1007/bf01211162Douady, A., & Hubbard, J. H. (1985). On the dynamics of polynomial-like mappings. Annales scientifiques de l’École normale supérieure, 18(2), 287-343. doi:10.24033/asens.1491Frontini, M., & Sormani, E. (2003). Some variant of Newton’s method with third-order convergence. Applied Mathematics and Computation, 140(2-3), 419-426. doi:10.1016/s0096-3003(02)00238-2Gutiérrez, J. M., Hernández, M. A., & Romero, N. (2010). Dynamics of a new family of iterative processes for quadratic polynomials. Journal of Computational and Applied Mathematics, 233(10), 2688-2695. doi:10.1016/j.cam.2009.11.017Özban, A. . (2004). Some new variants of Newton’s method. Applied Mathematics Letters, 17(6), 677-682. doi:10.1016/s0893-9659(04)90104-8PLAZA, S. (2001). CONJUGACIES CLASSES OF SOME NUMERICAL METHODS. Proyecciones (Antofagasta), 20(1). doi:10.4067/s0716-09172001000100001Plaza, S., & Romero, N. (2011). Attracting cycles for the relaxed Newton’s method. Journal of Computational and Applied Mathematics, 235(10), 3238-3244. doi:10.1016/j.cam.2011.01.010F.A. Potra and V. Pták,Nondiscrete Introduction and Iterative Processes, Research Notes in Mathematics Vol. 103, Pitman, Boston, MA, 1984

    Large-scale production of somatic embryos as a source of hypocotyl explants for Vitis vinifera micrografting

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    To the standard methods currently used to make grapevine virus-free, apex micrografting on hypocotyls of somatic embryos is proposed as an alternative procedure. The study defines optimal conditions to produce hypocotyl fragments suitable for micrografting. Interruption of the process by storage of tissues or embryos at low temperature (+ 4 °C) was assessed at different stages and for durations up to 6 months. Best procedure to produce somatic embryos were: long-term maintenance of embryogenic cultures on C1 medium (5 μM 2.4-D + 1 μM BAP, solidified with 4 g·l-1 agar and 4 g·l-1 Phytagel) ; differentiation of embryogenic callus for 2 months on C2 medium (5 μM NOA + 1 μM BAP, gelling agents same as above) ; transfer of single embryos on plant growth regulator-free medium for 2-3 weeks for germination. At different steps of the process, embryogenic tissues or differentiated embryos can be stored for up to 180 d for some cultivars. Micrografting assays were performed with various types of embryo and with apices from several V. vinifera cultivars. White to slightly coloured hypocotyls, excised from embryos germinated in darkness, gave best results for micrografting, while hypocotyl shape had little influence. For all genotypes tested the success rate ranged from 18 to 30 %.

    Application of Global Positioning System and questionnaires data for the study of driver behavior on two-lane rural roads

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    This paper is a preprint of a paper accepted by IET Intelligent Transport Systems and is subject to Institution of Engineering and Technology Copyright. When the final version is published, the copy of record will be available at IET Digital LibraryMethodologies based on naturalistic observation provide the most accurate data for studying drivers' behaviour. This study presents a new methodology to obtain naturalistic data related to drivers' behaviour in a road segment. It is based on the combination of using global positioning system data and drivers' questionnaires. The continuous speed profiles along a road segment and the characteristics of drivers, of their trips and the type of their vehicles can be obtained for a great amount of drivers. It has already been successfully used for several studies, such as the development of models to estimate operating speed profile in two-lane rural road segments; or the characterisation of driving styles. These operating speed models have been the key for the development of a new geometric design consistency model, allowing an easier road safety evaluation. Besides, knowledge on the human factors that influence speed choice may be useful for road safety media campaigns and education programs designers, and also for the improvement of intelligent driver assistance systems.The authors thank 'Centre for Studies and Experimentation of Public Works (CEDEX)' of the 'Spanish Ministry of Public Works' that partially subsidizes the research. We also wish to thank to the 'General Directorate of Public Works, Urban Projects and Housing' of the 'Infrastructure, Territory and Environment Department' of the 'Valencian Government', to the 'Valencian Provincial Council' and to the 'General Directorate of Traffic' of the 'Ministry of the Interior' for their cooperation in field data gathering.Pérez Zuriaga, AM.; Camacho Torregrosa, FJ.; Campoy Ungria, JM.; García García, A. (2013). Application of Global Positioning System and questionnaires data for the study of driver behavior on two-lane rural roads. IET Intelligent Transport Systems. 7(2):182-189. doi:10.1049/iet-its.2012.0151S18218972Fourie, M., Walton, D., & Thomas, J. A. (2011). Naturalistic observation of drivers’ hands, speed and headway. Transportation Research Part F: Traffic Psychology and Behaviour, 14(5), 413-421. doi:10.1016/j.trf.2011.04.009Gibreel, G. M., Easa, S. M., & El-Dimeery, I. A. (2001). Prediction of Operating Speed on Three-Dimensional Highway Alignments. Journal of Transportation Engineering, 127(1), 21-30. doi:10.1061/(asce)0733-947x(2001)127:1(21)Fitzpatrick, K., & Collins, J. M. (2000). Speed-Profile Model for Two-Lane Rural Highways. Transportation Research Record: Journal of the Transportation Research Board, 1737(1), 42-49. doi:10.3141/1737-06Bella, F. (2008). Driving simulator for speed research on two-lane rural roads. Accident Analysis & Prevention, 40(3), 1078-1087. doi:10.1016/j.aap.2007.10.015Van Nes, N., Houtenbos, M., & Van Schagen, I. (2008). Improving speed behaviour: the potential of in-car speed assistance and speed limit credibility. IET Intelligent Transport Systems, 2(4), 323. doi:10.1049/iet-its:20080036Warner, H. W., & Åberg, L. (2006). Drivers’ decision to speed: A study inspired by the theory of planned behavior. Transportation Research Part F: Traffic Psychology and Behaviour, 9(6), 427-433. doi:10.1016/j.trf.2006.03.004Goldenbeld, C., & van Schagen, I. (2007). The credibility of speed limits on 80km/h rural roads: The effects of road and person(ality) characteristics. Accident Analysis & Prevention, 39(6), 1121-1130. doi:10.1016/j.aap.2007.02.012Zuriaga, A. M. P., García, A. G., Torregrosa, F. J. C., & D’Attoma, P. (2010). Modeling Operating Speed and Deceleration on Two-Lane Rural Roads with Global Positioning System Data. Transportation Research Record: Journal of the Transportation Research Board, 2171(1), 11-20. doi:10.3141/2171-02Ottesen, J. L., & Krammes, R. A. (2000). Speed-Profile Model for a Design-Consistency Evaluation Procedure in the United States. Transportation Research Record: Journal of the Transportation Research Board, 1701(1), 76-85. doi:10.3141/1701-10Park, P. Y., Miranda-Moreno, L. F., & Saccomanno, F. F. (2010). Estimation of speed differentials on rural highways using hierarchical linear regression models. Canadian Journal of Civil Engineering, 37(4), 624-637. doi:10.1139/l10-002Wasielewski, P. (1984). Speed as a measure of driver risk: Observed speeds versus driver and vehicle characteristics. Accident Analysis & Prevention, 16(2), 89-103. doi:10.1016/0001-4575(84)90034-4Williams, A. F., Kyrychenko, S. Y., & Retting, R. A. (2006). Characteristics of speeders. Journal of Safety Research, 37(3), 227-232. doi:10.1016/j.jsr.2006.04.001Lajunen, T., Karola, J., & Summala, H. (1997). Speed and Acceleration as Measures of Driving Style in Young Male Drivers. Perceptual and Motor Skills, 85(1), 3-16. doi:10.2466/pms.1997.85.1.3Af Wåhlberg, A. E. (2006). Speed choice versus celeration behavior as traffic accident predictor. Journal of Safety Research, 37(1), 43-51. doi:10.1016/j.jsr.2005.10.01

    Analysis of the detachment of citrus fruits by vibration using artificial vision

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    The vibratory behaviour of citrus fruits is studied using slow-motion cameras in order to gain a better understanding of the parameters involved in fruit detachment when mechanical harvesting is done using shakers. Single citrus fruits with a small portion of stem were vibrated using strokes from 60 mm to 180 mm and frequencies from 3 Hz to 18 Hz. The movement was recorded at 300 fps and the main parameters considered for fruit detachment were determined through the analysis of the video sequences. Image-processing algorithms created for this purpose were applied to the automated estimation of the centroid of the fruit, the angle of the stem pistil axis, and the position of some selected points in the fruit in each frame of the video sequences to obtain dynamic parameters such as the position, speed and acceleration of the fruit during the movement until it is detached. The signals obtained from the image processing were filtered, providing results in accordance with the calibration systems. In general, results suggest that the inertial forces transmitted to the fruit were lower than the tensile forces required to detach the fruit by pulling it in the stem pistil direction. The largest peaks were observed using long strokes that required fewer cycles for detachment. On the other hand, short strokes combined with high frequencies needed more cycles, and thus a fatigue phenomenon was present. Short strokes and low frequencies were unable to detach some fruit. (C) 2014 IAgrE. Published by Elsevier Ltd. All rights reserved.This work was founded by the Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA) through the projects RTA2009-00118-C02-01 and RTA2009-00118-C02-02, and co-founded by European FEDER founds.Torregrosa Mira, A.; Albert Gil, FE.; Aleixos Borrás, MN.; Ortiz Sánchez, MC.; Blasco Ivars, J. (2014). Analysis of the detachment of citrus fruits by vibration using artificial vision. Biosystems Engineering. 119:1-12. https://doi.org/10.1016/j.biosystemseng.2013.12.010S11211

    Dynamical Techniques for Analyzing Iterative Schemes with Memory

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    [EN] We construct a new biparametric three-point method with memory to highly improve the computational efficiency of its original partner, without adding functional evaluations. In this way, through different estimations of self-accelerating parameters, we have modified an existing seventh-order method. The parameters have been defined by Hermite interpolating polynomial that allows the accelerating effect. In particular, the R-order of the proposed iterative method with memory is increased from seven to ten. A real multidimensional analysis of the stability of this method with memory is made, in order to study its dependence on the initial estimations. Taking into account that usually iterative methods with memory are more stable than their derivative-free partners and the obtained results in this study, the behavior of this scheme shows to be excellent, but for a small domain. Numerical examples and comparison are also provided, confirming the theoretical results.This research has been partially supported by grants from Spanish Ministerio de Economia y Competitividad (MTM2014-52016-C2-2-P) and by Generalitat Valenciana (PROMETEO/2016/089).Choubey, N.; Cordero Barbero, A.; Jaiswal, J.; Torregrosa Sánchez, JR. (2018). Dynamical Techniques for Analyzing Iterative Schemes with Memory. Complexity. https://doi.org/10.1155/2018/1232341

    Semilocal convergence by using recurrence relations for fifth-order method in Banach spaces

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    In this paper, a semilocal convergence result in Banach spaces of an efficient fifth-order method is analyzed. Recurrence relations are used in order to prove this convergence, and some a priori error bounds are found. This scheme is finally used to estimate the solution of an integral equation and so, the theoretical results are numerically checked. We use this example to show the better efficiency of the current method compared with other existing ones, including Newton's scheme.This research was supported by Ministerio de Ciencia y Tecnologia MTM2011-28636-C02-{01,02}.Cordero Barbero, A.; Hernandez-Veron, MA.; Romero, N.; Torregrosa Sánchez, JR. (2015). Semilocal convergence by using recurrence relations for fifth-order method in Banach spaces. Journal of Computational and Applied Mathematics. 273:205-213. https://doi.org/10.1016/j.cam.2014.06.008S20521327

    Neurofilament Light Regulates Axon Caliber, Synaptic Activity, and Organelle Trafficking in Cultured Human Motor Neurons

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    Neurofilament light (NFL) is one of the proteins forming multimeric neuron-specific intermediate filaments, neurofilaments, which fill the axonal cytoplasm, establish caliber growth, and provide structural support. Dominant missense mutations and recessive nonsense mutations in the neurofilament light gene (NEFL) are among the causes of Charcot–Marie–Tooth (CMT) neuropathy, which affects the peripheral nerves with the longest axons. We previously demonstrated that a neuropathy-causing homozygous nonsense mutation in NEFL led to the absence of NFL in patient-specific neurons. To understand the disease-causing mechanisms, we investigate here the functional effects of NFL loss in human motor neurons differentiated from induced pluripotent stem cells (iPSC). We used genome editing to generate NEFL knockouts and compared them to patient-specific nonsense mutants and isogenic controls. iPSC lacking NFL differentiated efficiently into motor neurons with normal axon growth and regrowth after mechanical axotomy and contained neurofilaments. Electrophysiological analysis revealed that motor neurons without NFL fired spontaneous and evoked action potentials with similar characteristics as controls. However, we found that, in the absence of NFL, human motor neurons 1) had reduced axonal caliber, 2) the amplitude of miniature excitatory postsynaptic currents (mEPSC) was decreased, 3) neurofilament heavy (NFH) levels were reduced and no compensatory increases in other filament subunits were observed, and 4) the movement of mitochondria and to a lesser extent lysosomes was increased. Our findings elaborate the functional roles of NFL in human motor neurons. NFL is not only a structural protein forming neurofilaments and filling the axonal cytoplasm, but our study supports the role of NFL in the regulation of synaptic transmission and organelle trafficking. To rescue the NFL deficiency in the patient-specific nonsense mutant motor neurons, we used three drugs, amlexanox, ataluren (PTC-124), and gentamicin to induce translational read-through or inhibit nonsense-mediated decay. However, the drugs failed to increase the amount of NFL protein to detectable levels and were toxic to iPSC-derived motor neurons

    Vitamin-V: Virtual Environment and Tool-boxing for Trustworthy Development of RISC-V based Cloud Services

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    Vitamin-V is a 2023-2025 Horizon Europe project that aims to develop a complete RISC-V open-source software stack for cloud services with comparable performance to the cloud-dominant x86 counterpart and a powerful virtual execution environment for software development, validation, verification, and test that considers the relevant RISC-V ISA extensions for cloud deployment

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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