An Analytical Prediction of the Bifurcation Scheme of a Clarinet-Like Instrument: Effects of Resonator Losses

The understanding of the relationship between excitation parameters andoscillation regimes is a classical topic concerning bowed stringinstruments. The paper aims to study the case of reed woodwinds and attemptsto find consequences on the ease of playing.In the minimum model of clarinet-like instruments, three parameters areconsidered: i) the mouth pressure, ii) the reed opening at rest, iii) thelength of the resonator \ assumed to be cylindrical. Recently asupplementary parameter was added: the loss parameter of the resonator(using the \textquotedblleft Raman model\textquotedblright, that considersresonator losses to be independent of frequency). This allowed explainingthe extinction of sound when the mouth pressure becomes very large. Thepresent paper presents an extension of the paper by Dalmont et al (JASA,2005), searching for a diagram of oscillation regimes with respect to thereed opening and the loss parameter. An alternative method is used, whichallows easier generalization and simplifies the calculation. The emphasis is done on the emergencebifurcation: for very strong losses, it can be inverse, similarly to theextinction one for weak losses. The main part of the calculations areanalytical, giving clear dependence of the parameters. An attempt to deducemusical consequences for the player is given

Statistical Estimation of Mechanical Parameters of Clarinet Reeds Using Experimental and Numerical Approaches

A set of 55 clarinet reeds is observed by holography, collecting 2 series of measurements made under 2 different moisture contents, from which the resonance frequencies of the 15 first modes are deduced. A statistical analysis of the results reveals good correlations, but also significant differences between both series. Within a given series, flexural modes are not strongly correlated. A Principal Component Analysis (PCA) shows that the measurements of each series can be described with 3 factors capturing more than $90\%$ of the variance: the first is linked with transverse modes, the second with flexural modes of high order and the third with the first flexural mode. A forth factor is necessary to take into account the individual sensitivity to moisture content. Numerical 3D simulations are conducted by Finite Element Method, based on a given reed shape and an orthotropic model. A sensitivity analysis revels that, besides the density, the theoretical frequencies depend mainly on 2 parameters: $E_L$ and $G_{LT}$. An approximate analytical formula is proposed to calculate the resonance frequencies as a function of these 2 parameters. The discrepancy between the observed frequencies and those calculated with the analytical formula suggests that the elastic moduli of the measured reeds are frequency dependent. A viscoelastic model is then developed, whose parameters are computed as a linear combination from 4 orthogonal components, using a standard least squares fitting procedure and leading to an objective characterization of the material properties of the cane \textit{Arundo donax}

Improvements and comparison of heuristics for solving the uncapacitated multisource Weber problem

Copyright @ 2000 INFORMSThe multisource Weber problem is to locate simultaneously m facilities in the Euclidean plane to minimize the total transportation cost for satisfying the demand of n fixed users, each supplied from its closest facility. Many heuristics have been proposed for this problem, as well as a few exact algorithms. Heuristics are needed to solve quickly large problems and to provide good initial solutions for exact algorithms. We compare various heuristics, i.e., alternative location-allocation (Cooper 1964), projection (Bongartz et al. 1994), Tabu search (Brimberg and Mladenovic 1996a), p-Median plus Weber (Hansen ct al. 1996), Genetic search and several versions of Variable Neighbourhood search. Based on empirical tests that are reported, it is found that most traditional and some recent heuristics give poor results when the number of facilities to locate is large and that Variable Neighbourhood search gives consistently best results, on average, in moderate computing time.This study was supported by the Department of National Defence (Canada) Academic Research; Office of Naval Research Grant N00014-92-J-1194, Natural Sciences and Engineering Research Council of Canada Grant GPO 105574 and Fonds pour la Formation des Chercheurs et l’Aide a la Recherche Grant 32EQ 1048; and by an International Postdoctoral Fellowship of the Natural Sciences and Engineering Research Council of Canada, Grant OGPOO 39682

Phase transformation yield surface of anisotropic shape memory alloys

International audienceTwo theoretical investigations, i.e. a phenomenological macroscopic model and a "micro-macro" model are developed for modelling the experimental surfaces of initiation of phase transformation in shape memory alloys. A possible initial anisotropy of the materials is taken into account

Multi-objective local search for mining Pittsburgh classification rules

International audienceThis abstract presents a modeling of the classification rule mining problem as a dominance-based multi-objective local search, with Pittsburgh solution encoding, using accuracy and the number of terms as objectives. This solution is then compared to results from literature of 22 rule mining classification algorithms

Relation between the martensite volume fraction and the equivalent transformation strain in shape memory alloys

International audienceThis study concerns the pseudoelasticity of shape memory alloys. A series of tests under multiaxial loadings and a micro-macro model are used to show the validity of a conjecture concerning the relation between the volume fraction of martensite and the equivalent transformation strain

Principles of ‘Newspeak’ in Polish Translations of British and American Press Articles under Communist Rule

The paper analyses selected Polish translations of British and American press articles published in the magazine Forum in the years 1965 - 1989. In communist Poland, all such texts were censored before publication, which forced the translators to avoid content and language that could be banned by censors and to adopt a specific style of expression known as Newspeak. The paper lists the linguistic phenomena in the target language that represent features typical of Newspeak and identifies manipulative procedures which led to their occurrence, using a corpus of 25 English texts and their Polish translations

On the Neutrality of Flowshop Scheduling Fitness Landscapes

Solving efficiently complex problems using metaheuristics, and in particular local searches, requires incorporating knowledge about the problem to solve. In this paper, the permutation flowshop problem is studied. It is well known that in such problems, several solutions may have the same fitness value. As this neutrality property is an important one, it should be taken into account during the design of optimization methods. Then in the context of the permutation flowshop, a deep landscape analysis focused on the neutrality property is driven and propositions on the way to use this neutrality to guide efficiently the search are given.Comment: Learning and Intelligent OptimizatioN Conference (LION 5), Rome : Italy (2011

Equivalent transformation strain and its relation with martensite volume fraction for isotropic and anisotropic shape memory alloys.

International audienceThe present paper deals with the superelastic behavior of both isotropic and anisotropic shape memory alloys (SMA). Recently, a macroscopic model, which permits to simulate the superelasticity of SMA under complex multi-axial loading, has been proposed by Bouvet et al. [Bouvet, C., Calloch, S., Lexcellent, C., 2004. A phenomenological model for pseudoelasticity of shape memory alloys under multi-axial proportional and non-proportional loadings. Eur. J. Mech. A Solids 23, 37-61]. In this model, a conjecture concerning the proportionality of the equivalent transformation strain with the martensite volume fraction has been adopted. The main goal of this study is to show the validity of this conjecture when the stress state is multi-axial. In a first part, the case of isotropic SMA is considered. An equivalent stress and an equivalent transformation strain are introduced. In the second section, the case of anisotropic SMA is considered. The previous equivalent stress and equivalent transformation strain are generalized to take into account the anisotropy of the material. The relation between the equivalent transformation strain and the martensite volume fraction is discussed by using, on one hand, experimental results under proportional tension-torsion loadings and, on the other hand, a polycrystalline model