Identification of mode couplings in nonlinear vibrations of the steelpan

The authors are grateful to Bertrand David (Telecom-ParisTech) for computing the code allowing the STFT filtering procedure used in Section 5.1. The filter has been designed in the framework of the PAFI project (Plateforme d’Aide la facture Instrumentale, www.pafi.fr) which is also thanked.The vibrations and sounds produced by two notes of a double second steelpan are investigated, the main objective being to quantify the nonlinear energy exchanges occurring between vibration modes that are responsible of the peculiar sound of the instrument. A modal analysis first reveals the particular tuning of the modes and the systematic occurence of degenerate modes, from the second one, this feature being a consequence of the tuning and the mode localization. Forced vibrations experiments are then performed to follow precisely the energy exchange between harmonics of the vibration and thus quantify properly the mode couplings. In particular, it is found that energy exchanges are numerous, resulting in complicated frequency response curves even for very small levels of vibration amplitude. Simple models displaying 1:2:2 and 1:2:4 internal resonance are then fitted to the measurements, allowing to identify the values of the nonlinear quadratic coupling coefficients resulting from the geometric nonlinearity. The identified 1:2:4 model is finally used to recover the time domain variations of an impacted note in normal playing condition, resulting in an excellent agreement for the temporal behaviour of the first four harmonics

Shõmei Tõmatsu : la mémoire des ruines

Cette analyse se penche sur l’ouvrage de Shõmei Tõmatsu 11 ji 02 fun(11 : 02 Nagasaki), au sein duquel il travaille la ruine comme un motif particulier s’insérant au coeur d’un récit visuel. L’auteur examine également comment ce photographe transforme la ruine en un élément narratif pour expérimenter une nouvelle approche de la photographie afin de s’éloigner des conventions de la photographie réaliste de l’après-guerre japonais.This article intends to trace the historical transformation of the ruins. It starts with the work of Shõmei Tõmatsu 11 ji 02 fun (11 : 02 Nagasaki), in which the artist uses ruins as a “motif” fitting into a narrative visual fiction. This essay also examine how this photographer transforms ruins into a narrative element to try out a new approach of photography, moving away from the Japanese post-war period conventions of realistic photography

Supersymmetric Field Theories on Three-Manifolds

We construct supersymmetric field theories on Riemannian three-manifolds M, focusing on N=2 theories with a U(1)_R symmetry. Our approach is based on the rigid limit of new minimal supergravity in three dimensions, which couples to the flat-space supermultiplet containing the R-current and the energy-momentum tensor. The field theory on M possesses a single supercharge, if and only if M admits an almost contact metric structure that satisfies a certain integrability condition. This may lead to global restrictions on M, even though we can always construct one supercharge on any given patch. We also analyze the conditions for the presence of additional supercharges. In particular, two supercharges of opposite R-charge exist on every Seifert manifold. We present general supersymmetric Lagrangians on M and discuss their flat-space limit, which can be analyzed using the R-current supermultiplet. As an application, we show how the flat-space two-point function of the energy-momentum tensor in N=2 superconformal theories can be calculated using localization on a squashed sphere.Comment: 53 pages; minor change

From Rigid Supersymmetry to Twisted Holomorphic Theories

We study N=1 field theories with a U(1)_R symmetry on compact four-manifolds M. Supersymmetry requires M to be a complex manifold. The supersymmetric theory on M can be described in terms of conventional fields coupled to background supergravity, or in terms of twisted fields adapted to the complex geometry of M. Many properties of the theory that are difficult to see in one formulation are simpler in the other one. We use the twisted description to study the dependence of the partition function Z_M on the geometry of M, as well as coupling constants and background gauge fields, recovering and extending previous results. We also indicate how to generalize our analysis to three-dimensional N=2 theories with a U(1)_R symmetry. In this case supersymmetry requires M to carry a transversely holomorphic foliation, which endows it with a near-perfect analogue of complex geometry. Finally, we present new explicit formulas for the dependence of Z_M on the choice of U(1)_R symmetry in four and three dimensions, and illustrate them for complex manifolds diffeomorphic to S^3 x S^1, as well as general squashed three-spheres.Comment: 55 pages; minor change

Idiophones à plaques et coques. Partie II. Instruments fortement non linéaires : cymbales, tam-tams et plaques tonnerre

International audienceDans cet article nous nous intéressons aux idio-phones à plaques et coques dont le comportement est fortement non linéaire. Nous traiterons du cas des cymbales, des gongs – et plus particulièrement des tam-tams – ainsi que de la plaque tonnerre. Ces instruments sont distingués des précédents, dits « à faible non-linéarité », car la physique vibratoire mise en jeu est radicalement différente, beaucoup plus complexe et très fortement non linéaire. Au niveau perceptif, cette distinction est immédiatement notable à l'oreille car les instruments que nous considérons dans cet article n'ont pas de hauteur définie. Leur son caractéristique est décrit comme très brillant : le contenu fréquentiel est tellement riche qu'on ne peut leur attribuer une hauteur précise, on observe plutôt un continuum de fréquences

Physiology of exercise in health and disease, with special reference to effort intolerance, training and thermoregulation in man

1. Davies, C.T.M., (1968) Limitdtions to the prediction of maximum oxygen intake from cardiac frequency measurements. J. Appl. Physiol. 24, 700 -706 || 2. Cotes, J.E., Davies, C.T.M., Edholm, G G., Healy, M.J.R., and Tanner, J.M., (1969). Factors relating to the aerobic capacity of 46 healthy British males and females, ages 18 -28 years. Proc. Roy. Soc. Lond. B 174, 91 -114 || 3. Davies, C.T.M., Tuxworth, W., and Young, J.M., (1970). Physiological effects of repeated exercise. Clin. Sci. 39, 247 -258 || 4. Di Prampero, P.E., Davies, C.T.M., Cerretelli, P., and Margaria R., (1970) An analysis of 02 debt contracted in submaximal exercise. J. Appl. Physiol. 29, 547 -551 || 5. Godfrey, S., and Davies, C.T.M., (1970) Estimates of arterial PCO2 and their effect on the calculated values of cardiac output and deadspace in exercise tests. Clin. Sci. 39, 529 -537 || 6. Davies, C.T.M., Kitchin, A.H., Knibbs, A.V., and Neilson, J.M., (1971) Computer Quantitation of ST segment response to graded exercise in untrained and trained normal subjects. Cardiovascular Research, 5, 201 -209 || 7. Godfrey, S., Davies, C.T.M., Wozniak, E., and Barnes, Carolyn A., (1971) Cardio -respiratory response to exercise in normal children. Clin. Sci. 40, 419 -431 || 8. Davies, C.T.M., (1972). The oxygen transporting system in relation to age. Clin. Sci. 42, 1 -13 || 9. Davies, C.T.M., Di Prampero, P.E., and Ceretelli, P., (1972) Kinetics of cardiac output and respiratory gas exchange during exercise and recovery. J. Appl. Physiol. 32, 618 -625 || 10. Edwards, R.H.T., Denison, D.M., Jones, G., Davies, C.T.M., and Campbell, E.J.M., (1972) Changes in mixed venous gas tensions at the start of exercise in man. J. Appl. Physiol. 32, 165 -169 || 11. Davies, C.T.M., and Barnes, Carolyn A., (1972) Plasma FFA in relation to maximum power output in man. Int. Z. Angew Physiol. 30, 247-257 || 12. Davies, C.T.M., Barnes Carolyn A., Fox, R.H., Ojikutu, R., Ola and Samueloff A.S., (1972). Ethnic difference in physical work capacity. J. Appl. Physiol. 33, 726 -732 || 13. Davies, C.T.M., (1973) Relationship of maximum aerobic power output to productivity and absenteeism of East African sugar cane workers. Brit. J. Ind. Med. 30, 146 -154 || 14. Davies, C.T.M., Chukweumeka, A.C., and Van Haaren, J.P.M., (1973) Iron deficiency anaemia: its effect on maximum aerobic power and responses to exercise in African males, aged 17 -40 years. Clin. Sci. 44, 555 -566 || 15. Cotes, J.E., Berry, G., Burkinshaw, L., Davies, C.T.M., Hall, A.M., Jones, P.R.M., and Knibbs, A.V., (1973). Cardiac frequency during submaximal exercise in young adults: relation to lean body mass, total body potassium and amount of leg muscle. Q.J.Expl.Physiol. 58, 239 -250 || 16. Davies, C.T.M., and Van Haaren, J.P.M., (1973) The effect of treatment the physiological responses to exercise in East African Industrial workers with iron deficiency anaemia. Brit. J. Ind. Med. 30, 335 -340. || 17. Sargeant, A.J., and Davies, C.T.M., (1973). Perceived exertion during rhythmic exercise involving different muscle masses. Human Ergology, 2, 3 -11 || 18. Davies, C.T.M., Sargeant, A.J., and Smith, B., (1974). The physiological responses to running downhill. Europ. J. Appl. Physiol. 32, 187 -194 || 19. Davies, C.T.M., and Sargeant, A.J., (1974) Physiological responses to standardised arm work. Ergonomics 17, 41 -49 || 20. Davies, C.T.M., and Sargeant, A.J., (1974). Exercise performance with one and two -legs breathing air and 45% oxygen. J. Appl. Physiol. 36, 142 -148 || 21. Davies, C.T.M., Few J.D., Foster, K.G., and Sargeant, A.J., (1974). Plasma catecholamine concentration during dynamic exercise involving different muscle groups. Eur. J. Appl. Physiol. 32, 195 -206 || 22. Davies, C.T.M., and Sargeant, A.J., (1974). Indirect determination of maximal aerobic power during work with one or two limbs. Europ. J. Appl. Physiol. 32, 207 -215 || 23. Davies, C.T.M., and Sargeant, A.J., (1974). Effects of hypoxic training on normoxic maximal aerobic power output. Europ. J. Appl. Physiol. 33, 227 -236 || 24. Davies, C.T.M., and Sargeant, A.J., (1975) Changes in physiological performance of the lower limb after fracture and subsequent rehabilitation Clin. Sci. & Mol. Med. 48, 107 -114 || 25. Davies, C.T.M., and Sargeant, A.J., (1975) physiological responses to 1 and 2 leg 377 -381 || 26. Davies, C.T.M., and Sargeant, A.J., (1975). exercise in patients following fracture J. Rehab. Med. 7, 45 -50. Effects of training on the work. J. Appl. Physiol. 38, Physiological responses to of the lower limb. Scand. || 27. Davies, C.T.M., Godfrey, S., Light, M., Sargeant, A.J., and Zeidifard, E.,. (1975) Cardiopulmonary responses to exercise in obese girls and young women. J. Appl. Physiol. 38, 373 -376 || 28. Davies, C.T.M., and Sargeant, A.J., (1975) Circadian variation in physiological responses to exercise on a stationary bicycle ergometer Brit. J. Ind. Med. 32, 110 -114 || 29. Collins, K.J. Brotherhood, J.R., Davies, C.T.M., Dore, Caroline, Hackett, J., Imms, F.J., Musgrove, J., Weiner, J.S., Amin, M.A., El Karim, M., Ismail, H11.M., Omer A.J.S., and Sukkar, M.Y., (1976). Physiological performance and work capacity of Sudanese can cutters with Schistosoma mansoni infection. Amer. J. Trop. Med. & Hyg. 25, 401,421 || 30. Nielsen, B., and Davies, C.T.M., (1976). Temperature regulation during exercise in water and air. Acta Physiol. Scand. 98, 500 -508 || 31. Davies, C.T.M., Brotherhood, J.R., Few,J.D., and Zeidifard, E., (1976) Effects of ß blockade and atropinisation on plasma catecholamine concentration during exercise. Eur. J. Appl. Physiol. 36, 49 -56 || 32. Davies, C.T.M., Brotherhood, J.R., and Zeidifard, E., (1976). Temperature regulation during severe exercise with some observations on the effects of skin wetting. J. Appl. Physiol. 41, 772 -776 || 33. Sargeant, A.J., Davies, C.T.M., Edwards, R.H.T., Maunder, C., and Young A., (1977). Functional and structural changes after disuse of human muscle. Clin. Sci. & Mol. Med. 52,337 -342 || 34. Sargeant, A.J., and Davies, C.T.M., (1977). Forces applied to cranks of a bicycle ergometer during one and two leg cycling. J. Appl. Physiol. 42, 514 -518 || 35. Sargeant, A.J., & Davies, C.T.M., (1977). The effect of disuse muscular atrophy on the forces generated in dynamic exercise. Clin. Sci. & Mol. Med. 53, 182 -188 || 36. Fohlin, L., Freyschuss, E., Bjarke, B., Davies, C.T.M., and Thoren, C., (1978). Function and Dimensions of the circulatory system in anorexia nervosa. Acta. Paed. Scand. 67, 11 -16 || 37. Davies, C.T.M., Von Dobeln, W. Fohlin, L., Freyschuss u., and Thoren, C., (1978). Total body potassium, fat free weight and maximal aerobic power in children with Anorexia Nervosa. Acta. Pediatr. Scand. 67, 229 -334 || 38. Davies, C.T.M., Brotherhood, J.P., and ZeidiFard, E., (1978). Effects of Atropine and (3-Blockade on Temperature Regulation and Performance during Prolonged Exercise. Europ. J. Appl. Physiol. 38, 225 -232 || 39. Zeidifard, E., and Davies, C.T.M., (1978). An Assessment of a N20 Rebreathing Method for the Estimation of Cardiac Output During Severe Exercise. Ergonomics, 21, 567 -572 || 40. Sargeant,A.J., Crawley, M.A., and Davies, C.T.M., (1979). Physiological Responses to Exercise in Myocardial Infarction Patients Following Residential Rehabilitation. Arch. Phys. Med. Rehabil. 60, 121 -125 || 41. Davies, C.T.M., (1979). The effects of different levels of heat production induced by diathermy and eccentric work on thermoregulation during exercise at a given skin temperature. Eur. J. Appl. Physiol. 40, 171 -180 || 42. Davies, C.T.M., and Thompson, M.W., (1979). Aerobic Performance of Female Marathon and Male Ultra- marathon Athletes. Eur. J. Appl. Physiol. 41, 233 -245 || 43. Davies, C.T.M., (1979). Thermoregulation during exercise in relation to sex and age. Eur. J. Appl. Physiol. 42, 71 -79 || 44. Davies, C.T.M., (1979). Influence of skin temperature on sweating and aerobic performance during severe work. J. Appl. Physiol. 47, 770 -777 || 45. Davies, C.T.M., and Sargeant, A.J., (1979). The effects of atropine and Practolol on the perception of exertion during treadmill exercise. Ergonomics 22, 1141 -1146 || 46. C.T.M., Fohlen L., and Temperature regulation in Anorexia nervosa patients during prolonged exercise. Acta. Med. Scand. 205, 257 -262 || 47. Davies, C.T.M., (1980) Influence of air flow and skin temperature on sweating during and following exercise. Ergonomics. 23, 559 -569 || 48. Davies, C.T.M., Fohlen L., and Thoren C., (1979) The effects of wind resistance on the forward motion of a runner. J. Appl. Physiol. 48, 702 -709 || 49. Davies, C.T.M., (1980) Metabolic cost of exercise and physical performance in children with some observations on external loading. Eur. J. Appl. 45, 95 -102 || 50. Davies, C.T.M., (1980) Effect of air resistance on the metabolic cost and performance of cycling. Eur. J. Appl. Physiol. 45, 245 -254

Nonlinear vibrations of steelpans: analysis of mode coupling in view of modal sound synthesis.

Steelpans are musical percussions made from steel barrels. During the manufacturing, the metal is stretched and bended, to produce a set of thin shells that are the differents notes of the instrument. In normal playing, each note is struck, and the sound reveals some nonlinear characteristics which give its peculiar tone to the instrument. In this paper, an experimental approach is first presented in order to show the complex dynamics existing in steelpan’s vibrations. Then two models, based on typical modal interactions, are proposed to quantify these nonlinearities. Finally, one of them is observed in free oscillations simulations, in order to compare the internal resonance model to the steelpan vibrations behaviour in normal playing. The aim is to identify the important modes participating in the vibrations in view of building reduced-order models for modal sound synthesis