5 research outputs found
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Active control applied to wind instruments
Musicians have always been interested in the evolution of their instruments. This evolution might be done either to adapt an instrument’s quality to musicians’ and composers’ needs, or to enable it to produce new sounds. In this study, we want to control the sound quality and playability of wind instruments, using modal active control. The modal active control makes it possible to modify the input impedance (frequency, gain and damping) of these instruments and to modify the instrument’s quality. The simulations for a first experiment are presented here. We simulate a control of the modes (frequency, damping) of a cylinder, which is considered as a simple ”wind instrument”. We consider the use of a microphone, a speaker, an observer and a controller to modify theses modes, then we look at the modifications on the sound and playability using Modalys. Our next goal will be to apply the control to a real cylinder, and to evaluate it in a musical context with a musician
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Simulations of modal active control applied to the self-sustained oscillations of the clarinet.
This paper reports a new approach to modifying the sound produced by a wind instrument. The approach is based on modal active control, which enables adjustment of the damping and the frequencies of the different resonances of a system. A self-sustained oscillating wind instrument can be modeled as an excitation source coupled to a resonator via a non-linear coupling. The aim of this study is to present simulations of modal active control applied to a modeled self-sustained oscillating wind instrument in order to modify its playing properties. The modeled instrument comprises a cylindrical tube coupled to a reed and incorporates a collocated loudspeaker and microphone; it can thus be considered to approximate a simplified clarinet. Modifications of the pitch, the strength of the harmonics of the sound produced by the instrument, and of the oscillation threshold are obtained while controlling the first two resonances of the modeled instrument
The Tomato Sequencing Project, the First Cornerstone of the International Solanaceae Project (SOL)
The genome of tomato (Solanum lycopersicum) is being sequenced by an international
consortium of 10 countries (Korea, China, the United Kingdom, India, The
Netherlands, France, Japan, Spain, Italy and the United States) as part of a larger initiative
called the ‘International Solanaceae Genome Project (SOL): Systems Approach
to Diversity and Adaptation’. The goal of this grassroots initiative, launched in
November 2003, is to establish a network of information, resources and scientists
to ultimately tackle two of the most significant questions in plant biology and agriculture:
(1) How can a common set of genes/proteins give rise to a wide range of
morphologically and ecologically distinct organisms that occupy our planet? (2) How
can a deeper understanding of the genetic basis of plant diversity be harnessed to
better meet the needs of society in an environmentally friendly and sustainable manner?
The Solanaceae and closely related species such as coffee, which are included
in the scope of the SOL project, are ideally suited to address both of these questions.
The first step of the SOL project is to use an ordered BAC approach to generate a
high quality sequence for the euchromatic portions of the tomato as a reference for
the Solanaceae. Due to the high level of macro and micro-synteny in the Solanaceae
the BAC-by-BAC tomato sequence will form the framework for shotgun sequencing
of other species. The starting point for sequencing the genome is BACs anchored
to the genetic map by overgo hybridization and AFLP technology. The overgos are
derived from approximately 1500 markers from the tomato high density F2-2000
genetic map (http://sgn.cornell.edu/). These seed BACs will be used as anchors from
which to radiate the tiling path using BAC end sequence data. Annotation will be
performed according to SOL project guidelines. All the information generated under
the SOL umbrella will be made available in a comprehensive website. The information
will be interlinked with the ultimate goal that the comparative biology of the
Solanaceae—and beyond—achieves a context that will facilitate a systems biology
approach
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Experimental demonstration of the modification of the resonances of a simplified self-sustained wind instrument through modal active control.
This paper reports the experimental results of modifying the resonances of wind instruments using modal active control. Resonances of a simplified bass clarinet without holes (a cylindrical tube coupled to a bass clarinet mouthpiece including a reed) are adjusted either in frequency or in damping in order to modify its playing properties (pitch, strength of the harmonics of the sound, transient behaviour). This is achieved using a control setup consisting of a co-located loudspeaker and microphone linked to a computer with data acquisition capabilities. Software on the computer implements an observer (which contains a model of the system) and a controller. Measuring and adjusting the transfer function between the speaker and microphone of the control setup enables modifications of the input impedance and the radiated sound of the instrument