8,327 research outputs found
Regime change thresholds in flute-like instruments: influence of the mouth pressure dynamics
Since they correspond to a jump from a given note to another one, the mouth
pressure thresholds leading to regime changes are particularly important
quantities in flute-like instruments. In this paper, a comparison of such
thresholds between an artificial mouth, an experienced flutist and a non player
is provided. It highlights the ability of the experienced player to
considerabily shift regime change thresholds, and thus to enlarge its control
in terms of nuances and spectrum. Based on recent works on other wind
instruments and on the theory of dynamic bifurcations, the hypothe- sis is
tested experimentally and numerically that the dynamics of the blowing pressure
influences regime change thresholds. The results highlight the strong influence
of this parameter on thresholds, suggesting its wide use by experienced
musicians. Starting from these observations and from an analysis of a physical
model of flute-like instruments, involving numerical continuation methods and
Floquet stability analysis, a phenomenological modelling of regime change is
proposed and validated. It allows to predict the regime change thresholds in
the dynamic case, in which time variations of the blowing pressure are taken
into account
Integrated Application of Active Controls (IAAC) technology to an advanced subsonic transport project: Current and advanced act control system definition study. Volume 2: Appendices
The current status of the Active Controls Technology (ACT) for the advanced subsonic transport project is investigated through analysis of the systems technical data. Control systems technologies under examination include computerized reliability analysis, pitch axis fly by wire actuator, flaperon actuation system design trade study, control law synthesis and analysis, flutter mode control and gust load alleviation analysis, and implementation of alternative ACT systems. Extensive analysis of the computer techniques involved in each system is included
Nonlinear Analysis and Control of Interleaved Boost Converter Using Real-Time Cycle to Cycle Variable Slope Compensation
Switched-mode power converters are inherently nonlinear and piecewise smooth systems that may exhibit a series of undesirable operations that can greatly reduce the converter's efficiency and lifetime. This paper presents a nonlinear analysis technique to investigate the influence of system parameters on the stability of interleaved boost converters. In this approach, Monodromy matrix that contains all the comprehensive information of converter parameters and control loop can be employed to fully reveal and understand the inherent nonlinear dynamics of interleaved boost converters, including the interaction effect of switching operation. Thereby not only the boundary conditions but also the relationship between stability margin and the parameters given can be intuitively studied by the eigenvalues of this matrix. Furthermore, by employing the knowledge gained from this analysis, a real-Time cycle to cycle variable slope compensation method is proposed to guarantee a satisfactory performance of the converter with an extended range of stable operation. Outcomes show that systems can regain stability by applying the proposed method within a few time periods of switching cycles. The numerical and analytical results validate the theoretical analysis, and experimental results verify the effectiveness of the proposed approach
Analog Neural Programmable Optimizers in CMOS VLSI Technologies
A 3-μm CMOS IC is presented demonstrating the concept of an analog neural system for constrained optimization. A serial time-multiplexed general-purpose architecture is introduced for the real-time solution of this kind of problem in MOS VLSI. This architecture is a fully programmable and reconfigurable one exploiting SC techniques for the analog part and making extensive use of digital techniques for programmability
Neurophysiology
Contains reports on three research projects.National Institutes of Health (Grant 5 ROl NB-04985-04)U. S. Air Force (Aerospace Medical Division) under Contract AF33(615)-3885Bioscience Division of National Aeronautics and Space Administration through Contract NSR 22-009-13
Design strategies for the creation of aperiodic nonchaotic attractors
Parametric modulation in nonlinear dynamical systems can give rise to
attractors on which the dynamics is aperiodic and nonchaotic, namely with
largest Lyapunov exponent being nonpositive. We describe a procedure for
creating such attractors by using random modulation or pseudo-random binary
sequences with arbitrarily long recurrence times. As a consequence the
attractors are geometrically fractal and the motion is aperiodic on
experimentally accessible timescales. A practical realization of such
attractors is demonstrated in an experiment using electronic circuits.Comment: 9 pages. CHAOS, In Press, (2009
Neurophysiology
Contains reports on two research projects.National Institutes of Health (Grant 5 ROl NB-04985-04)U. S. Air Force (Aerospace Medical Division) under Contract AF33(615)-3885DSR Project 55-257Bioscience Division of National Aeronautics and Space Administration through Contract NSR 22-009-13
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