1,215 research outputs found

    The self-stimulated capillary jet

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    Inspired by a Savart’s pioneering work, we study the self-stimulated dynamics of a capillary jet. The feedback loop is realised by extracting surface perturbations from a section of the jet itself via a laser–photodiode pair, whose amplified signal drives an electromechanical actuator which, in turn, produces pressure perturbations at the exit chamber. Under specific conditions, this loop establishes phase-locked stimulation regimes that overcome the otherwise random natural breakup. For each laser position along the jet, the gain of the amplifier acts as a selector across a discrete set of observable frequencies. The main observed features are explained by a linear theory which combines the transfer function of each stage in the loop. Our findings are relevant to continuous inkjet technologies for the production of equally sized droplets

    Analysis of the backward bending modes in damped rotating beams

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    [EN] This article presents a study of the backward bending mode of a simply supported rotating Rayleigh beam with internal damping. The study analyses the natural frequency behaviour of the backward mode according to the internal viscous damping ratio, the slenderness of the beam and its spin speed. To date, the behaviour of the natural frequency of the backward mode is known to be a monotonically decreasing function with spin speed due to gyroscopic effects. In this article, however, it is shown that this behaviour of the natural frequency may not hold for certain damping and slenderness conditions, and reaches a minimum value (concave function) from which it begins to increase. Accordingly, the analytical expression of the spin speed for which the natural frequency of the backward mode attains the minimum value has been obtained. In addition, the internal damping ratio and slenderness intervals associated with such behaviour have been also provided.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors gratefully acknowledge the financial support of Ministerio de Ciencia, Innovacion y Universidades Agencia Estatal de Investigacion and the European Regional Development Fund (project TRA2017-84701-R), as well as Generalitat Valenciana (project Prometeo/2016/007) and European Commission through the project 'RUN2Rail - Innovative RUNning gear soluTiOns for new dependable, sustainable, intelligent and comfortable RAIL vehicles' (Horizon 2020 Shift2Rail JU call 2017, grant number 777564)Martínez Casas, J.; Denia Guzmán, FD.; Fayos Sancho, J.; Nadal, E.; Giner Navarro, J. (2019). Analysis of the backward bending modes in damped rotating beams. Advances in Mechanical Engineering. 11(4):1-13. https://doi.org/10.1177/1687814019840474S113114Zorzi, E. S., & Nelson, H. D. (1977). Finite Element Simulation of Rotor-Bearing Systems With Internal Damping. Journal of Engineering for Power, 99(1), 71-76. doi:10.1115/1.3446254Ku, D.-M. (1998). FINITE ELEMENT ANALYSIS OF WHIRL SPEEDS FOR ROTOR-BEARING SYSTEMS WITH INTERNAL DAMPING. Mechanical Systems and Signal Processing, 12(5), 599-610. doi:10.1006/mssp.1998.0159Dimentberg, M. F. (2005). Vibration of a rotating shaft with randomly varying internal damping. Journal of Sound and Vibration, 285(3), 759-765. doi:10.1016/j.jsv.2004.11.025Vatta, F., & Vigliani, A. (2008). Internal damping in rotating shafts. Mechanism and Machine Theory, 43(11), 1376-1384. doi:10.1016/j.mechmachtheory.2007.12.009Rosales, M. B., & Filipich, C. P. (1993). Dynamic Stability of a Spinning Beam Carrying an Axial Dead Load. Journal of Sound and Vibration, 163(2), 283-294. doi:10.1006/jsvi.1993.1165Mazzei, A. J., & Scott, R. A. (2003). Effects of internal viscous damping on the stability of a rotating shaft driven through a universal joint. Journal of Sound and Vibration, 265(4), 863-885. doi:10.1016/s0022-460x(02)01256-7Ehrich, F. F. (1964). Shaft Whirl Induced by Rotor Internal Damping. Journal of Applied Mechanics, 31(2), 279-282. doi:10.1115/1.3629598Vance, J. M., & Lee, J. (1974). Stability of High Speed Rotors With Internal Friction. Journal of Engineering for Industry, 96(3), 960-968. doi:10.1115/1.3438468Vila, P., Baeza, L., Martínez-Casas, J., & Carballeira, J. (2014). Rail corrugation growth accounting for the flexibility and rotation of the wheel set and the non-Hertzian and non-steady-state effects at contact patch. Vehicle System Dynamics, 52(sup1), 92-108. doi:10.1080/00423114.2014.881513Glocker, C., Cataldi-Spinola, E., & Leine, R. I. (2009). Curve squealing of trains: Measurement, modelling and simulation. Journal of Sound and Vibration, 324(1-2), 365-386. doi:10.1016/j.jsv.2009.01.048Bauer, H. F. (1980). Vibration of a rotating uniform beam, part I: Orientation in the axis of rotation. Journal of Sound and Vibration, 72(2), 177-189. doi:10.1016/0022-460x(80)90651-3Shiau, T. N., & Hwang, J. L. (1993). Generalized Polynomial Expansion Method for the Dynamic Analysis of Rotor-Bearing Systems. Journal of Engineering for Gas Turbines and Power, 115(2), 209-217. doi:10.1115/1.2906696Hili, M. A., Fakhfakh, T., & Haddar, M. (2006). Vibration analysis of a rotating flexible shaft–disk system. Journal of Engineering Mathematics, 57(4), 351-363. doi:10.1007/s10665-006-9060-3Young, T. H., Shiau, T. N., & Kuo, Z. H. (2007). Dynamic stability of rotor-bearing systems subjected to random axial forces. Journal of Sound and Vibration, 305(3), 467-480. doi:10.1016/j.jsv.2007.04.016Wang, J., Hurskainen, V.-V., Matikainen, M. K., Sopanen, J., & Mikkola, A. (2017). On the dynamic analysis of rotating shafts using nonlinear superelement and absolute nodal coordinate formulations. Advances in Mechanical Engineering, 9(11), 168781401773267. doi:10.1177/1687814017732672Lee, C.-W. (1993). Vibration Analysis of Rotors. Solid Mechanics and Its Applications. doi:10.1007/978-94-015-8173-8Genta, G. (1999). Vibration of Structures and Machines. doi:10.1007/978-1-4612-1450-2Cheng, C. C., & Lin, J. K. (2003). Modelling a rotating shaft subjected to a high-speed moving force. Journal of Sound and Vibration, 261(5), 955-965. doi:10.1016/s0022-460x(02)01374-

    Finding smORFs: getting closer

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    Millions of small open reading frames exist in eukaryotes. We do not know how many, or which are translated, but bioinformatics is getting us closer to the answer. See related Research article: http://www.genomebiology.com/2015/16/1/179

    Determination of an optimal response cut-off able to predict progression-free survival in patients with well-differentiated advanced pancreatic neuroendocrine tumours treated with sunitinib: an alternative to the current RECIST-defined response.

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    BACKGROUND: Sunitinib prolongs progression-free survival (PFS) in patients with advanced pancreatic neuroendocrine tumours (pNET). Response Evaluation Criteria in Solid Tumors (RECIST)-defined partial responses (PR; classically defined as ⩾30% size decrease from baseline) are infrequent. METHODS: Individual data of pNET patients from the phase II [NCT00056693] and pivotal phase III [NCT00428597] trials of sunitinib were analysed in this investigator-initiated, post hoc study. The primary objective was to determine the optimal RECIST (v.1.0) response cut-off value to identify patients who were progression-free at 11 months (median PFS in phase III trial); and the most informative time-point (highest area under the curve (AUC) by receiver operating characteristic (ROC) analysis and logistic regression) for prediction of benefit (PFS) from sunitinib. RESULTS: Data for 237 patients (85 placebo; 152 sunitinib (n=66.50 mg \u274-weeks on/2-weeks off\u27 schedule; n=86 \u2737.5 mg continuous daily dosing (CDD)\u27)) and 788 scans were analysed. The median PFS for sunitinib and placebo were 9.3 months (95% CI 7.6-12.2) and 5.4 months (95% CI 3.5-6.01), respectively (hazard ratio (HR) 0.43 (95% CI 0.29-0.62); P CONCLUSIONS: A 10% reduction within marker lesions identifies pNET patients benefiting from sunitinib treatment with implications for maintenance of dose intensity and future trial design

    Program trace optimization with constructive heuristics for combinatorial problems

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    This is the author accepted manuscript. The final version is available from Springer via the DOI in this record.EvoCOP: 19th European Conference on Evolutionary Computation in Combinatorial Optimisation, 24-26 April 2019, Leipzig, GermanyProgram Trace Optimisation (PTO), a highly general optimisation framework, is applied to a range of combinatorial optimisation (COP) problems. It effectively combines \smart" problem-specifi c constructive heuristics and problem-agnostic metaheuristic search, automatically and implicitly designing problem-appropriate search operators. A weakness is identifi ed in PTO's operators when applied in conjunction with smart heuristics on COP problems, and an improved method is introduced to address this. To facilitate the comparison of this new method with the original, across problems, a common format for PTO heuristics (known as generators) is demonstrated, mimicking GRASP. This also facilitates comparison of the degree of greediness (the GRASP alpha parameter) in the heuristics. Experiments across problems show that the novel operators consistently outperform the original without any loss of generality or cost in CPU time; hill-climbing is a sufficient metaheuristic; and intermediate levels of greediness are usually best

    Dioxin Toxicity In Vivo Results from an Increase in the Dioxin-Independent Transcriptional Activity of the Aryl Hydrocarbon Receptor

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    The Aryl hydrocarbon receptor (Ahr) is the nuclear receptor mediating the toxicity of dioxins -widespread and persistent pollutants whose toxic effects include tumor promotion, teratogenesis, wasting syndrome and chloracne. Elimination of Ahr in mice eliminates dioxin toxicity but also produces adverse effects, some seemingly unrelated to dioxin. Thus the relationship between the toxic and dioxin-independent functions of Ahr is not clear, which hampers understanding and treatment of dioxin toxicity. Here we develop a Drosophila model to show that dioxin actually increases the in vivo dioxin-independent activity of Ahr. This hyperactivation resembles the effects caused by an increase in the amount of its dimerisation partner Ahr nuclear translocator (Arnt) and entails an increased transcriptional potency of Ahr, in addition to the previously described effect on nuclear translocation. Thus the two apparently different functions of Ahr, dioxin-mediated and dioxin-independent, are in fact two different levels (hyperactivated and basal, respectively) of a single function

    Aging and Holography

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    Aging phenomena are examples of `non-equilibrium criticality' and can be exemplified by systems with Galilean and scaling symmetries but no time translation invariance. We realize aging holographically using a deformation of a non-relativistic version of gauge/gravity duality. Correlation functions of scalar operators are computed using holographic real-time techniques, and agree with field theory expectations. At least in this setup, general aging phenomena are reproduced holographically by complexifying the bulk space-time geometry, even in Lorentzian signature.Comment: 1 pdf figur

    A characterization of the wave front set defined by the iterates of an operator with constant coefficients

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    [EN] We characterize the wave front set WF*P (u) with respect to the iterates of a linear partial differential operator with constant coefficients of a classical distribution u is an element of D '(Omega), Omega an open subset in R-n. We use recent Paley-Wiener theorems for generalized ultradifferentiable classes in the sense of Braun, Meise and Taylor. We also give several examples and applications to the regularity of operators with variable coefficients and constant strength. Finally, we construct a distribution with prescribed wave front set of this type.The authors were partially supported by FAR2011 (Universita di Ferrara), "Fondi per le necessita di base della ricerca" 2012 and 2013 (Universita di Ferrara) and the INDAM-GNAMPA Project 2014 "Equazioni Differenziali a Derivate Parziali di Evoluzione e Stocastiche" The research of the second author was partially supported by MINECO of Spain, Project MTM2013-43540-P.Boiti, C.; Jornet Casanova, D. (2017). A characterization of the wave front set defined by the iterates of an operator with constant coefficients. Revista de la Real Academia de Ciencias Exactas Físicas y Naturales Serie A Matemáticas. 111(3):891-919. https://doi.org/10.1007/s13398-016-0329-8S8919191113Albanese, A.A., Jornet, D., Oliaro, A.: Quasianalytic wave front sets for solutions of linear partial differential operators. Integr. Equ. Oper. Theory 66, 153–181 (2010)Boiti, C., Jornet, D.: The problem of iterates in some classes of ultradifferentiable functions. In: “Operator Theory: Advances and Applications”. Birkhauser, Basel. 245, 21–32 (2015)Boiti, C., Jornet, D., Juan-Huguet, J.,: Wave front set with respect to the iterates of an operator with constant coefficients. Abstr. Appl. Anal., 1–17 (2014). doi: 10.1155/2014/438716 (Article ID 438716)Bolley, P., Camus, J., Mattera, C.: Analyticité microlocale et itérés d’operateurs hypoelliptiques. In: Séminaire Goulaouic–Schwartz, 1978–79, Exp N.13. École Polytech., PalaiseauBonet, J., Fernández, C., Meise, R.: Characterization of the ω\omega ω -hypoelliptic convolution operators on ultradistributions. Ann. Acad. Sci. Fenn. Math. 25, 261–284 (2000)Bonet, J., Meise, R., Melikhov, S.N.: A comparison of two different ways to define classes of ultradifferentiable functions. Bull. Belg. Math. Soc. Simon Stevin 14, 425–444 (2007)Braun, R.W., Meise, R., Taylor, B.A.: Ultradifferentiable functions and Fourier analysis. Result. Math. 17, 206–237 (1990)Fernández, C., Galbis, A., Jornet, D.: ω\omega ω -hypoelliptic differential operators of constant strength. J. Math. Anal. Appl. 297, 561–576 (2004)Fernández, C., Galbis, A., Jornet, D.: Pseudodifferential operators of Beurling type and the wave front set. J. Math. Anal. Appl. 340, 1153–1170 (2008)Hörmander, L.: On interior regularity of the solutions of partial differential equations. Comm. Pure Appl. Math. XI, 197–218 (1958)Hörmander, L.: Uniqueness theorems and wave front sets for solutions of linear partial differential equations with analytic coefficients. Comm. Pure Appl. Math. 24, 671–704 (1971)Hörmander, L.: The Analysis of Linear Partial Differential Operators I. Springer, Berlin (1990)Hörmander, L.: The Analysis of Linear Partial Differential Operators II. Springer, Berlin (1983)Juan-Huguet, J.: Iterates and hypoellipticity of partial differential operators on non-quasianalytic classes. Integr. Equ. Oper. Theory 68, 263–286 (2010)Juan-Huguet, J.: A Paley–Wiener type theorem for generalized non-quasianalytic classes. Studia Math. 208(1), 31–46 (2012)Komatsu, H.: A characterization of real analytic functions. Proc. Jpn. Acad. 36, 90–93 (1960)Kotake, T., Narasimhan, M.S.: Regularity theorems for fractional powers of a linear elliptic operator. Bull. Soc. Math. France 90, 449–471 (1962)Langenbruch, M.: P-Funktionale und Randwerte zu hypoelliptischen Differentialoperatoren. Math. Ann. 239(1), 55–74 (1979)Langenbruch, M.: Fortsetzung von Randwerten zu hypoelliptischen Differentialoperatoren und partielle Differentialgleichungen. J. Reine Angew. Math. 311/312, 57–79 (1979)Langenbruch, M.: On the functional dimension of solution spaces of hypoelliptic partial differential operators. Math. Ann. 272, 217–229 (1985)Langenbruch, M.: Bases in solution sheaves of systems of partial differential equations. J. Reine Angew. Math. 373, 1–36 (1987)Métivier, G.: Propriété des itérés et ellipticité. Comm. Partial Differ. Equ. 3(9), 827–876 (1978)Newberger, E., Zielezny, Z.: The growth of hypoelliptic polynomials and Gevrey classes. Proc. Amer. Math. Soc. 39(3), 547–552 (1973)Rodino, L.: On the problem of the hypoellipticity of the linear partial differential equations. In: Buttazzo, G. (ed.) Developments in Partial Differential Equations and Applications to Mathematical Physics. Plenum Press, New York (1992)Rodino, L.: Linear partial differential operators in Gevrey spaces. 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    Combining symbiotic simulation systems with enterprise data storage systems for real-time decision-making

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    This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this recordA symbiotic simulation system (S3) enables interactions between a physical system and its computational model representation. To support operational decisions, an S3 uses real-time data from the physical system, which is gathered via sensors and saved in an enterprise data storage system (EDSS). Both real-time and historical data are then used as inputs to the different components of an S3. This paper proposes a generic system architecture for an S3 and discusses its integration within EDSSs. The paper also reviews the literature on S3 and analyses how these systems can be used for real-time decision-making.Erasmus

    Les delices de L' Espagne & du Portugal : [où l'on voit une description exacte des antiquitez, des provinces ... de la religion, des moeurs des habitans ... le tout enrichi de figures en taille douce, dessinées sur les lieux mêmes]

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    Ver h. de lám.Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Posteriormente se publicó bajo el título: "Annales d'Espagne et Portugal"Sign.: 2[asterisco]12, A-R8, S4Antep.Frontispicio pleg. de "J. G. in."Contiene: État de l'ancienne Espagne, les provinces de Biscaye, d'Asturie, de La Galice, Le Royaume de Leon, & de La Castille Vieill
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