smoothness of an equation for the glottal flow rate versus the glottal area this letter proposes a correction to an equation by titze j acoust soc am 75 570 580 1984 for the volume velocity of the glottal air flow given the glottal area and other laryngeal parameters it shows that the equation produces non differentiable waveforms at the instants of glottal closure and opening if the glottal area is also not differentiable at those instants by adding an air viscosity term to the equation twice differentiability is obtained also the letter corrects a sign error in the original formulation

direct numerical simulation of the glottal jet and vocal fold dynamics in a three dimensional laryngeal model an immersed boundary method based flow solver coupled with a finite element solid dynamics solver is employed in order to conduct direct numerical simulations of phonatory dynamics in a three dimensional model of the human larynx the computed features of the glottal flow including mean and peak flow rates and the open and skewness quotients are found to be within the normal physiological range the flow induced vibration pattern shows the classical convergent divergent glottal shape and the vibration amplitude is also found to be typical for human phonation the vocal fold motion is analyzed through the method of empirical eigenfunctions and this analysis indicates a 1 1 modal entrainment between the adduction abduction mode and the mucosal wave mode the glottal jet is found to exhibit noticeable cycle to cycle asymmetric deflections and the mechanism underlying this phenomenon is examined

bifurcations in an asymmetric vocal fold model a two mass model of vocal fold vibrations is analyzed with methods from nonlinear dynamics bifurcations are located in parameter planes of physiological interest subglottal pressure stiffness of the folds it is shown that a sufficiently large tension imbalance of the left and right vocal fold induces bifurcations to subharmonic regimes toroidal oscillations and chaos the corresponding attractors are characterized by phase portraits spectra and next maximum maps the relevance of these simulations for voice disorders such as laryngeal paralysis is discussed

chaotic component obscured by strong periodicity in voice production system the effect of glottal aerodynamics in producing the nonlinear characteristics of voice is investigated by comparing the outputs of the asymmetric composite model and the two mass model the two mass model assumes the glottal airflow to be laminar nonviscous and incompressible in this model when the asymmetric factor is decreased from 0 65 to 0 35 only 1 1 and 1 2 modes are detectable however with the same parameters four vibratory modes 1 1 1 2 2 4 2 6 are found in the asymmetric composite model using the navier stokes equations to describe the complex aerodynamics in the glottis moreover the amplitude of the waveform is modulated by a small amplitude noiselike series the nonlinear detection method reveals that this noiselike modulation is not random but rather it is deterministic chaos this result agrees with the phenomenon often seen in voice in which the voice signal is strongly periodic but modulated by a small amplitude chaotic component the only difference between the two mass model and the composite model is in their descriptions of glottal airflow therefore the complex aerodynamic characteristics of glottal airflow could be important in generating the nonlinear dynamic behavior of voice production including bifurcation and a small amplitude chaotic component obscured by strong periodicity

an efficient hybrid multi objective particle swarm optimization with a multi objective dichotomy line search recently more research works are focused on multi objective particle swarm optimization algorithm mopso due to its ability of global and local search for solving multi objective optimization problems moops however most of existing mopsos cannot achieve satisfactory results in solution quality this paper proposes an efficient hybrid multi objective particle swarm optimization with a multi objective dichotomy line search mols named mols mopso to deal with such problem mols mopso combines an effective particle updating strategy with the local search of mols the effective particle updating strategy is used for global search to deal with premature convergence and diversity maintenance within the swarm the mols is periodically activated for fast local search to converge toward the pareto front the exploratory capabilities are enhanced more efficiently by keeping a desirable balance between global search and local search so as to ensure sufficient diversity and well distribution amongst the solutions of the non dominated fronts while retaining at the same time the convergence to the pareto optimal front comparing mols mopso with various state of the art multi objective optimization algorithms developed recently the comparative study shows the effectiveness of mols mopso which not only assures a better convergence to the pareto frontier but also illustrates a good diversity and distribution of solutions

experimental validation of a three dimensional reduced order continuum model of phonation due to the complex nature of the phonation process a one dimensional 1d glottal flow description is often used in current phonation models although widely used in voice research these 1d flow based phonation models have not been rigorously validated against experiments in this study a 1d glottal flow model is coupled with a three dimensional nonlinear continuum model of the vocal fold and its predictions are compared to physical model experiments the results show that the 1d flow based model is able to predict the phonation threshold pressure and onset frequency within reasonable accuracy and to reproduce major vibratory features observed in the experiments

testing the assumptions of linear prediction analysis in normal vowels in this paper we develop an improved surrogate data test to show experimental evidence for all the simple vowels of u s english for both male and female speakers that gaussian linear prediction analysis a ubiquitous technique in current speech technologies cannot be used to extract all the dynamical structure of real speech time series the test provides robust evidence undermining the validity of these linear techniques supporting the assumptions of either dynamical nonlinearity and or non gaussianity common to more recent complex efforts at dynamical modeling speech time series however an additional finding is that the classical assumptions cannot be ruled out entirely and plausible evidence is given to explain the success of the linear gaussian theory as a weak approximation to the true nonlinear non gaussian dynamics this supports the use of appropriate hybrid linear nonlinear non gaussian modeling with a calibrated calculation of statistic and particular choice of experimental protocol some of the known systematic problems of the method of surrogate data testing are circumvented to obtain results to support the conclusions to a high level of significance

ergodic complex structures on hyperkahler manifolds let m be a compact complex manifold the corresponding teichmuller space teich is the space of all complex structures on m up to the action of the group rm diff 0 m of isotopies the mapping class group gamma rm diff m rm diff 0 m acts on teich in a natural way an ergodic complex structure is a complex structure with a gamma orbit dense in teich let m be a complex torus of complex dimension ge 2 or a hyperkahler manifold with b 2 3 we prove that m is ergodic unless m has maximal picard rank there are countably many such m this is used to show that all hyperkahler manifolds are kobayashi non hyperbolic

an adaptive parameter tuning of particle swarm optimization algorithm an adaptive parameter tuning of particle swarm optimization based on velocity information apso vi algorithm is proposed in this paper the velocity convergence of particles is first analyzed and the relationship between the velocity of particle and the search failures is pointed out which reveals the reasons why pso has relative poor global searching ability then this algorithm introduces the velocity information which is defined as the average absolute value of velocity of all the particles a new strategy is presented that the inertia weight is dynamically adjusted according to average absolute value of velocity which follows a given nonlinear ideal velocity by feedback control which can avoid the velocity closed to zero at the early stage under the guide of the nonlinear ideal velocity apso vi can maintain appropriate swarm diversity and alleviate the premature convergence validly numerical experiments are conducted to compare the proposed algorithm with different variants of pso on some benchmark functions experimental results show that the proposed algorithm remarkably improves the ability of pso to jump out of the local optima and significantly enhance the convergence speed and precision

finite element approximation of flow induced vibrations of human vocal folds model effects of inflow boundary conditions and the length of subglottal and supraglottal channel on phonation onset abstract the paper presents the numerical analysis of interaction of the vibrating simplified human vocal folds model with the incompressible viscous airflow in a channel modeling simplified subglottal and supraglottal spaces the flow in the considered 2d computational fluid domain is governed by the navier stokes equations written in the arbitrary lagrangian eulerian form the stabilized finite element method is applied for numerical approximation and the choice of boundary conditions and their implementation is discussed for the considered model problem the prescribed inlet velocity and prescribed pressure difference formulations were numerically analyzed the prescribed inlet velocity formulation was successful in predicting of the flutter velocity value whereas the prescribed pressure difference gave nonphysical results finally a modified inlet boundary condition motivated by the penalization approach is suggested it is shown that this approach gives possibilities to optimize the inlet boundary condition related to a physical reality by changing smoothly the penalty parameter in the interval between the two extremes and to treat the complete closures of the channel

interval dynamic response analysis of vehicle bridge interaction system with uncertainty abstract interval dynamic response analysis of vehicle bridge interaction system with uncertain parameters is studied in this paper the bridge s and vehicle s parameters are considered as interval variables a half car model is used to represent a moving vehicle and the bridge is assumed as a simply supported euler bernoulli beam by introducing the interval algorithm into the dynamic analysis of vehicle bridge interaction system the expressions of the midpoint value interval width lower and upper bounds of interval bridge dynamic response are developed the lower and upper bounds are respectively the minimum and maximum values of bridge dynamic response which can also be determined by optimization approaches a heuristic optimization method a new particle swarm optimization method with low discrepancy sequence initialized particles and high order nonlinear time varying inertia weight and constant acceleration coefficients lhnpso is then developed to find the bounds of bridge displacement examples are used to illustrate the effectiveness of the presented methods and monte carlo simulations are implemented to validate the computational results the effects of individual system parameters on bridge response are also investigated

the effect of exit radii on intraglottal pressure distributions in the convergent glottis phonation depends upon the dynamic distribution of glottal air pressures that act upon the vocal folds as well as tissue properties of the vocal folds the glottal wall pressures depend upon the shape size and diameter of the glottis for a given flow this study examined how the radius of curvature of the glottal exit in the converging glottis affects the wall pressures in the glottis the following exit radii were used 0 0908 cm 0 0454 cm and 0 0050 cm for the 10 case and 0 0841 cm 0 021 025 cm and 0 0050 cm for the 20 case minimal glottal diameter and flow were held constant at 0 02 cm and 73 2 cm3 s respectively the computational fluid dynamics code fluent was used to obtain the pressure profiles both the transglottal and intraglottal pressures increased as the exit radius decreased resulting in an increase in flow resistance and an increase in the outward pressure forces on the vocal folds the results suggest that the glottal exit curvature should be well specified when building computational or physical models of the vocal folds

theoretical and experimental study of quasisteady flow separation within the glottis during phonation application to a modified two mass model most flow models used in numerical simulation of voiced sound production rely for the sake of simplicity upon a certain number of assumptions while most of these assumptions constitute reasonable first approximations others appear more doubtful in particular it is implicitly assumed that the air flow through the glottal channel separates from the walls at a fixed point since this assumption appears quite unrealistic and considering that the position of the separation point is an important parameter in phonation models in this paper a revised fluid mechanical description of the air flow through the glottis is proposed in which the separation point is allowed to move this theoretical model as well as the assumptions made are validated using steady and unsteady flow measurements combined with flow visualizations in order to evaluate the effective impact of the revised theory we then present an application to a simple mechanical model of the vocal cords derived from the classical two mass model as expected implementation of a moving separation point appears to be of great importance for the modeling of glottal signals it is further shown that the numerical model coupled with a more realistic description of the vocal cord collision can lead to signals surprisingly close to those observed in real speech by inverse filtering

topological invariants of o grady s six dimensional irreducible symplectic variety we study o grady examples of irreducible symplectic varieties we establish that both of them can be deformed into lagrangian fibrations we analyze in detail the topology of the six dimensional example in particular we compute its euler characteristic and determine its beauville form

determination of parameters for lumped parameter models of the vocal folds using a finite element method approach to study the mechanical behavior of the vocal folds lumped parameter models of the vocal folds have been developed in the past coupling with a model of the aerodynamics in the glottis provides the possibility of simulating glottal waves a new method is presented to obtain values for the masses and springs of the lumped parameter models by using a finite element method model of the vocal folds this finite element method model is based on geometry and material data from the literature resulting in a model that describes the vocal fold in a realistic way requiring the dynamic behavior of the lumped parameter model of the vocal fold to be equal to the dynamic behavior of the finite element method model of the vocal fold parameter values are obtained that are purely based on dynamic considerations therefore the behavior of the vocal folds is described in a realistic way by these parameters these values are compared with the values used by previous authors and are implemented in lumped parameter models self sustained oscillation is achieved with the new values for masses and springs

genls co evolutionary algorithm for nonlinear system of equations abstract in this paper we present a new optimization system genls for nonlinear system of equations our approach has two characteristic features firstly nonlinear system of equations is transformed into a nonlinear programming problem nlp with additional parameter e to define initial precision of the system that is the objective is to reduce the violation of the constraints to an acceptable level desired precision e by minimizing a function that measures the maximum violation of the constraints secondly efficient co evolutionary algorithm is implemented for solving the resulting nlp which combines concept of co evolution repairing procedure and elitist strategy finally we report numerical results in order to establish the actual computational burden of the proposed method and to assess its performances with respect to classical approaches for solving nonlinear system of equations

on the application of the lattice boltzmann method to the investigation of glottal flow the production of voice is directly related to the vibration of the vocal folds which is generated by the interaction between the glottal flow and the tissue of the vocal folds in the current study the aerodynamics of the symmetric glottis is investigated numerically for a number of static configurations the numerical investigation is based on the lattice boltzmann method lbm which is an alternative approach within computational fluid dynamics compared to the traditional navier stokes computational fluid dynamics methods the lbm is relatively easy to implement and can deal with complex geometries without requiring a dedicated grid generator the multiple relaxation time model was used to improve the numerical stability the results obtained with lbm were compared to the results provided by a traditional navier stokes solver and experimental data it was shown that lbm results are satisfactory for all the investigated cases

pressure flow relationships in two models of the larynx having rectangular glottal shapes the pressure flow equations used in computer simulation studies of phonation lack experimental validation two polyester resin models of the laryngeal airway with rectangular glottal ducts were constructed in order to obtain the relationships between translaryngeal pressure drop and volume flow through the airway the results are in disagreement with the early estimates of wegel bell syst tech j 9 207 227 1930 but match the predictions given by ishizaka and matsudaira scrl monograph no 8 1972 to within approximately 10 for typical translaryngeal pressures for speech with larger discrepancies being found for the model with the larger glottal diameter the equation given by van den berg et al j acoust soc am 29 626 631 1957 may not be properly compared because their supraglottal pressure hole location may have been different from that used in the present study the data from the two models also are compared to recent empirical studies using an enlarged model of the larynx j gauffin et al conference on vocal fold physiology madison 1981

a theoretical study of the hysteresis phenomenon at vocal fold oscillation onset offset this paper presents a theoretical study on the differences in the biomechanical parameters of the vocal folds between oscillation onset and offset the dynamics of the oscillation is analyzed from the perspective of the theory of nonlinear dynamical systems using a mucosal wave model of the vocal folds with the subglottal pressure and the vocal fold half width as control parameters it is shown that the oscillation onset occurs through a hopf bifurcation of the subcritical type at which an unstable limit cycle is generated also the oscillation offset occurs at a cyclic fold bifurcation at which the unstable limit cycle and a stable limit cycle the actual vocal fold oscillation coalesce and cancel each other both bifurcations combine to form an oscillation hysteresis phenomenon common in cases of flow induced oscillations an analytical expression for the onset offset ratio of parameters is derived the onset offset ratio is in the range of 0 5 1 in agreement with the experimental evidence this value depends on the phase delay in motion of the upper edge of the vocal folds versus the lower edge and on the particular model adopted for airflow separation within the glottis

geometry of human vocal folds and glottal channel for mathematical and biomechanical modeling of voice production current models of the vocal folds derive their shape from approximate information rather than from exactly measured data the objective of this study was to obtain detailed measurements on the geometry of human vocal folds and the glottal channel in phonatory position a non destructive casting methodology was developed to capture the vocal fold shape from excised human larynges on both medial and superior surfaces two female larynges each in two different phonatory configurations corresponding to low and high fundamental frequency of the vocal fold vibrations were measured a coordinate measuring machine was used to digitize the casts yielding 3d computer models of the vocal fold shape the coronal sections were located in the models extracted and fitted by piecewise defined cubic functions allowing a mathematical expression of the 2d shape of the glottal channel left right differences between the cross sectional shapes of the vocal folds were found in both the larynges

the optimal control of the linear wave equation we consider in this paper the existence and numerical estimation of an optimal boundary control for the linear wave equation the problem is modified into one consisting of the minimization of a linear functional over a set of radon measures the optimal measure is then approximated by a finite combination of atomic measures and the problem converted to a finite dimensional linear programming problem the solution to this problem is used to construct a piecewise constant control some numerical examples are considered to illustrate the procedure

it cemop an iterative co evolutionary algorithm for multiobjective optimization problem with nonlinear constraints over the past few years researchers have developed a number of multiobjective evolutionary algorithms moeas although most studies concentrate on solving unconstrained optimization problems there exit a few studies where moeas have been extended to solve constrained optimization problems most of them were based on penalty functions for handling nonlinear constraints by genetic algorithms however the performance of these methods is highly problem dependent many methods require additional tuning of several parameters in this paper we present a new optimization algorithm which is based on concept of co evolution and repair algorithm for handling nonlinear constraints the algorithm maintains a finite sized archive of nondominated solutions which gets iteratively updated in the presence of new solutions based on the concept of e dominance the use of e dominance also makes the algorithms practical by allowing a decision maker to control the resolution of the pareto set approximation by choosing an appropriate e value which guarantees convergence and diversity the results provided by the proposed algorithm for six benchmark problems are promising when compared with exiting well known algorithms also our results suggest that our algorithm is better applicable for solving real world application problems

an in vitro setup to test the relevance and the accuracy of low order vocal folds models an experimental setup and human vocal folds replica able to produce self sustained oscillations are presented the aim of the setup is to assess the relevance and the accuracy of theoretical vocal folds models the applied reduced mechanical models are a variation of the classical two mass model and a simplification inspired on the delayed mass model for which the coupling between the masses is expressed as a fixed time delay the airflow is described as a laminar flow with flow separation the influence of a downstream resonator is taken into account the oscillation pressure threshold and fundamental frequency are predicted by applying a stability analysis to the mechanical models the measured frequency response of the mechanical replica together with the initial rest area allows us to determine the model parameters spring stiffness damping geometry masses validation of theoretical model predictions to experimental data shows the relevance of low order models in gaining a qualitative understanding of phonation however quantitative discrepancies remain large due to an inaccurate estimation of the model parameters and the crudeness in either flow or mechanical model description as an illustration it is shown that significant improvements can be made by accounting for viscous flow effects

modeling of chaotic vibrations in symmetric vocal folds the chaos mechanism of above range phonation was examined in symmetrically modeled vocal folds by using the traditional two mass model assumption the poincare map technique was used to display chaotic attractors this method provided an effective description of irregular vocal fold movements the power spectrum lyapunov exponent and kaplan yorke dimension were employed to describe chaotic vibrations in the vocal fold model these nonlinear dynamic analyses suggested that for the positive lyapunov exponent chaotic attractors contribute to irregular vocal fold vibrations descriptions of complicated irregular vibrations of the vocal fold yielded evidence of chaos to investigate the effects of independent parameters such as subglottal pressure coupling stiffness and phonation neutral area bifurcation diagrams based on the poincare map were discussed the results confirmed that the dynamics of the two mass model was strongly influenced by independent parameters nonlinear dynamic methods were expecte

phonation threshold pressure and the elastic shear modulus comparison of two mass model calculations with experiments ishizaka and flanagan s classic two mass model of vocal fold motion is applied to small oscillations where the equations become linear and the aerodynamic driving force is described by an effective stiffness the solution of these equations includes an analytic formula for the two eigenfrequencies this shows that conjugate imaginary parts of the frequencies emerge beyond eigenvalue synchronization and that one of the imaginary parts becomes zero at a pressure signaling the instability associated with the onset of threshold using recent measurements by fulcher et al of intraglottal pressure distributions j acoust soc am 129 1548 1553 2011 to inform the behavior of the entrance loss coefficients an analytic formula for threshold pressure is derived it fits most of the measurements chan and titze reported for their 2006 physical model of the vocal fold mucosa two sectors of the mass stiffness parameter space are used to produce these fits one is based on a rescaling of the typical glottal parameters of the original ishizaka and flanagan work the second requires setting two of the spring constants equal and should be closer to the experimental conditions in both cases values of the elastic shear modulus are calculated from the spring constants

a new method for solving a system of the nonlinear equations in this paper we use measure theory in the discrete case to solve a wide range of the nonlinear equations systems first by defining an error function we transform the problem to an optimal control problem in discrete case the new problem is modified into one consisting of the minimization of a linear functional over a set of radon measures the optimal measure then is approximated by a finite combination of atomic measures and the problem converted approximately to a finite dimensional nonlinear programming finally we obtain an approximate solution for the original problem furthermore we obtain the path from the initial point up to the approximate solution

reducing the number of vocal fold mechanical tissue properties evaluation of the incompressibility and planar displacement assumptions the incompressibility and planar displacement assumptions were used to reduce the number of independent tissue parameters required for the characterization of a structural model of the vocal folds the influence of these simplifying assumptions on the vibratory properties of the model was investigated the purpose was to provide estimates of the error introduced by these assumptions the variability in human tissue properties was accounted for through systematic variation of several material parameters the modal properties of a vocal fold structural model were computed with each assumption and in turn were relaxed to determine their respective effects the results indicated that the incompressibility assumption introduces little error errors introduced by the planar displacement assumption were found to depend on the ratio of the longitudinal stiffness and the transverse stiffness criteria for determining the compatibility of tissue property values from independent studies are also presented

the effect of glottal angle on intraglottal pressure intraglottal pressure distributions depend upon glottal shape size and diameter this study reports the effects of varying glottal angle on intraglottal and transglottal pressures using a three dimensional plexiglas model with a glottis having nine symmetric glottal angles and a constant minimal glottal diameter of 0 06cm the empirical data were supported by computational results using fluent the results suggested that 1 the greater the convergent glottal angle the greater outward driving forces higher intraglottal pressures on the vocal folds 2 flow resistance was greatest for the uniform glottis and least for the 10 divergent glottis 3 the greatest negative pressure in the glottis and therefore the greatest pressure recovery for diverging glottal shapes occurred for an angle of 10 4 the smaller the convergent angle the greater the flow resistance 5 fluent was highly accurate in predicting the empirical pressures of this model 6 flow separation locations given by fluent for

integrating particle swarm optimization with genetic algorithms for solving nonlinear optimization problems heuristic optimization provides a robust and efficient approach for solving complex real world problems the aim of this paper is to introduce a hybrid approach combining two heuristic optimization techniques particle swarm optimization pso and genetic algorithms ga our approach integrates the merits of both ga and pso and it has two characteristic features firstly the algorithm is initialized by a set of random particles which travel through the search space during this travel an evolution of these particles is performed by integrating pso and ga secondly to restrict velocity of the particles and control it we introduce a modified constriction factor finally the results of various experimental studies using a suite of multimodal test functions taken from the literature have demonstrated the superiority of the proposed approach to finding the global optimal solution

searching globally optimal parameter sequence for defeating runge phenomenon by immunity genetic algorithm data interpolation is a fundamental data processing tool in scientific studies and engineering applications however when interpolating data points on an equidistant grid using polynomials the so called runge phenomenon may occur making polynomial interpolation unreliable although there are some methods proposed to defeat the runge phenomenon it is still an open problem which parameter sequence is the globally optimal for overcoming the runge phenomenon in this paper we develop an immunity genetic algorithm based method to solve this problem specifically we first model the runge phenomenon defeating problem as an optimization in which the objective function is the energy of the parametric curve an immunity genetic algorithm is then devised to determine the best iga parameter sequence which minimizes the objective function the resulting parametric curve overcomes the runge phenomenon by performing the proposed immunity genetic searching algorithm starting with some groups of randomly generated parameter sequences the resulted parameter sequences closely oscillate around the chebyshev parameter sequence therefore the chebyshev parameter sequence is most likely the globally optimal sequence conquering the runge phenomenon

numerical characterization of the kahler cone of a compact kahler manifold the goal of this work is to give a precise numerical description of the kahler cone of a compact kahler manifold our main result states that the kahler cone depends only on the intersection form of the cohomology ring the hodge structure and the homology classes of analytic cycles if x is a compact kahler manifold the kahler cone k of x is one of the connected components of the set p of real 1 1 cohomology classes which are numerically positive on analytic cycles i e y p 0 for every irreducible analytic set y in x p dim y this result is new even in the case of projective manifolds where it can be seen as a generalization of the well known nakai moishezon criterion and it also extends previous results by campana peternell and eyssidieux the principal technical step is to show that every nef class which has positive highest self intersection numberx n 0 contains a kahler current this is done by using the calabi yau theorem and a mass concentration technique for monge ampere equations the main result admits a number of variants and corollaries including a description of the cone of numerically effective 1 1 classes and their dual cone another important consequence is the fact that for an arbitrary deformation x s of compact kahler manifolds the kahler cone of a very general fibre xt is independent of t i e invariant by parallel transport under the 1 1 component of the gauss manin connection

numerical simulation of self sustained oscillation of a voice producing element based on navier stokes equations and the finite element method surgical removal of the larynx results in radically reduced production of voice and speech to improve voice quality a voice producing element vpe is developed based on the lip principle called after the lips of a musician while playing a brass instrument to optimize the vpe a numerical model is developed in this model the finite element method is used to describe the mechanical behavior of the vpe the flow is described by two dimensional incompressible navier stokes equations the interaction between vpe and airflow is modeled by placing the grid of the vpe model in the grid of the aerodynamical model and requiring continuity of forces and velocities by applying and increasing pressure to the numerical model pulses comparable to glottal volume velocity waveforms are obtained by variation of geometric parameters their influence can be determined to validate this numerical model an in vitro test with a prototype of the vpe is performed experimental and numerical results show an acceptable agreement

higher direct images of dualizing sheaves of lagrangian fibrations let f x s be a lagrangian fibration between projective varieties we prove that inline graphic xmlns xlink http www w3 org 1999 xlink xlink href 01i i s if s is smooth suppose that x is an irreducible symplectic manifold or a certain moduli space of semistable torsion free sheaves on a k 3 surface the hodge numbers satisfy h p q s h p q inline graphic xmlns xlink http www w3 org 1999 xlink xlink href 02i where n dim s if s inline graphic xmlns xlink http www w3 org 1999 xlink xlink href 03i and x is an irreducible symplectic manifold there exists a hypersurface m f of the kuranishi space of x such that every member of the kuranishi family over m f admits a lagrangian fibration over inline graphic xmlns xlink http www w3 org 1999 xlink xlink href 04i

an effective genetic algorithm approach to large scale mixed integer programming problems abstract to effectively reduce the search space of gas on large scale mip problems this paper proposed a new variable grouping method based on structure properties of a problem taking the capacity expansion and technology selection problem as a typical example this method groups problem s decision variables over time period and machine line based on this new variable grouping method we developed a variable grouping based genetic algorithm according to problem s structure properties vgga s we tested the performance of vgga s by applying it on the capacity expansion and technology selection problem numerical experiments suggested that vgga s outperforms the standard ga and variable grouping based gas without considering problem s structure properties both on computation time and solution quality although vgga s is proposed based on structure properties of a specific mip problem it is a general optimization algorithm and theoretically applicable to other large scale mip problems

experimental validation of a quasi steady theory for the flow through the glottis in this paper a theoretical description of the flow through the glottis based on a quasi steady boundary layer theory is presented the thwaites method is used to solve the von karman equations within the boundary layers in practice this makes the theory much easier to use compared to pohlhausen s polynomial approximations this theoretical description is evaluated on the basis of systematic comparison with experimental data obtained under steady flow or unsteady oscillating flow without and with moving vocal folds results tend to show that the theory reasonably explains the measured data except when unsteady or viscous terms become predominant this happens particularly during the collision of the vocal folds

numerical simulations of fluid structure interactions in single reed mouthpieces most single reed woodwind instrument models rely on a quasistationary approximation to describe the relationship between the volume flow and the pressure difference across the reed channel semiempirical models based on the quasistationary approximation are very useful in explaining the fundamental characteristics of this family of instruments such as self sustained oscillations and threshold of blowing pressure however they fail at explaining more complex phenomena associated with the fluid structure interaction during dynamic flow regimes such as the transient and steady state behavior of the system as a function of the mouthpiece geometry previous studies have discussed the accuracy of the quasistationary approximation but the amount of literature on the subject is sparse mainly due to the difficulties involved in the measurement of dynamic flows in channels with an oscillating reed in this paper a numerical technique based on the lattice boltzmann method and a finite difference scheme is proposed in order to investigate the characteristics of fully coupled fluid structure interaction in single reed mouthpieces with different channel configurations results obtained for a stationary simulation with a static reed agree very well with those predicted by the literature based on the quasistationary approximation however simulations carried out for a dynamic regime with an oscillating reed show that the phenomenon associated with flow detachment and reattachment diverges considerably from the theoretical assumptions furthermore in the case of long reed channels the results obtained for the vena contracta factor are in significant disagreement with those predicted by theory for short channels the assumption of constant vena contracta was found to be valid for only 40 of the duty cycle

source tract interaction with prescribed vocal fold motion an equation describing the time evolution of glottal volume velocity with specified vocal fold motion is derived when the sub and supra glottal vocal tracts are present the derivation of this fant equation employs a property explicated in howe and mcgowan 2011 j fluid mech 672 428 450 that the fant equation is the adjoint to the equation characterizing the matching conditions of sub and supra glottal green s functions segments with the glottal segment the present aeroacoustic development shows that measurable quantities such as input impedances at the glottis provide the coefficients for the fant equation when source tract interaction is included in the development explicit expressions for the green s function are not required with the poles and zeros of the input impedance functions specified the fant equation can be solved after the general derivation of the fant equation the specific cases where plane wave acoustic propagation is described either by a sturm liouville problem or concatenated cylindrical tubes is considered simulations show the expected skewing of the glottal volume velocity pulses depending on whether the fundamental frequency is below or above a sub or supra glottal formant more complex glottal wave forms result when both the first supra glottal fundamental frequencies are high and close to the first sub glottal formant

a solution to the optimal power flow using genetic algorithm optimal power flow opf is one of the main functions of power generation operation and control it determines the optimal setting of generating units it is therefore of great importance to solve this problem as quickly and accurately as possible this paper presents the solution of the opf using genetic algorithm technique this paper proposes a new methodology for solving opf this methodology is divided into two parts the first part employs the genetic algorithm ga to obtain a feasible solution subject to desired load convergence while the other part employs ga to obtain the optimal solution the main goal of this paper is to verify the viability of using genetic algorithm to solve the opf problem simultaneously composed by the load flow and the economic dispatch problem six buses system are used to highlight the goodness of this solution technique

glottal flow through a two mass model comparison of navier stokes solutions with simplified models a new numerical model of the vocal folds is presented based on the well known two mass models of the vocal folds the two mass model is coupled to a model of glottal airflow based on the incompressible navier stokes equations glottal waves are produced using different initial glottal gaps and different subglottal pressures fundamental frequency glottal peak flow and closed phase of the glottal waves have been compared with values known from the literature the phonation threshold pressure was determined for different initial glottal gaps the phonation threshold pressure obtained using the flow model with navier stokes equations corresponds better to values determined in normal phonation than the phonation threshold pressure obtained using the flow model based on the bernoulli equation using the navier stokes equations an increase of the subglottal pressure causes the fundamental frequency and the glottal peak flow to increase whereas the fundamental frequency in the bernoulli based model does not change with increasing pressure

increasing the complexity of glottal flow models in vitro validation for steady flow conditions quasi one dimensional glottal flow descriptions predict vocal folds oscillations characteristics which are qualitatively relevant to in vitro and in vivo experimental data the current paper considers the resolution of the 2d navier stokes equations in order to obtain a refined description of the flow phenomena adapted to more realistic glottal geometry the pressure and flow rate predictions obtained from quasi one dimensional flow models and the resolution of the 2d navier stokes equations are examined for steady flows within a rigid glottis the models predictions are validated against in vitro measurements performed on rigid constriction replicas comparable to the geometrical conditions of the glottis and mounted in a suitable set up the confrontation between the experimental and computed data tends to show that the accuracy of the estimated pressures increases with the complexity of the flow model whereas the inverse tendency can be observed for the estimated flow rates a focus is made on the flow

low dimensional models of the glottal flow incorporating viscous inviscid interaction the behavior of glottal flow can to a large extent be characterized by development and separation of the boundary layer the point of flow separation is known to vary during the phonatory cycle due to change in channel configuration to take the movable nature of the separation point into account the boundary layer equation is solved numerically and the values of the characteristic quantities are determined as well as the point of separation development of the boundary layer in general reduces the effective size of the channel and therefore increases the core flow velocity which in turn provides the boundary condition of the boundary layer equation the interaction between the viscous boundary layer and inviscid core flow parts of the glottal flow is therefore strongly indicated to apply this viscous inviscid interaction the expression of the core flow is derived for a two dimensional flow field and is solved jointly with the boundary layer equation numerical results are shown to examine the effect of the reynolds number and glottal configuration with special emphasis on the comparison of flow models developed for one and two dimensional flow fields numerical results are also quantitatively compared with data obtained from flow measurement experiments

intraglottal pressure profiles for a symmetric and oblique glottis with a divergence angle of 10 degrees human phonation does not always involve symmetric motions of the two vocal folds asymmetric motions can create slanted or oblique glottal angles this study reports intraglottal pressure profiles for a plexiglas model of the larynx with a glottis having a 10 degree divergence angle and either a symmetric orientation or an oblique angle of 15 degrees for the oblique glottis one side was divergent and the other convergent the vocal fold surfaces had 14 pressure taps the minimal glottal diameter was held constant at 0 04 cm results indicated that for either the symmetric or oblique case the pressure profiles were different on the two sides of the glottis except for the symmetric geometry for a transglottal pressure of 3 cm h2o for the symmetric case flow separation created lower pressures on the side where the flow stayed attached to the wall and the largest pressure differences between the two sides of the channel were 5 6 of the transglottal pressure for the oblique case pressures were lower

aeroacoustic source characterization in a physical model of phonation this paper presents measurements conducted in a physical model of the adult human airway the goals of this work are to 1 benchmark the physical model to excised larynx models in the literature and 2 empirically demonstrate the relationship between vocal fold drag and sound production results from the airway model are first benchmarked to published time averaged behavior of excised larynx models the airway model in this work exhibited higher glottal volume flow lower glottal resistance and less fundamental frequency variation than excised larynx models next concurrent measurements of source behavior and radiated sound were compared unsteady transglottal pressure a surrogate measure for vocal fold drag and radiated sound measured at the mouth showed good correlation in particular the standard deviation and the ratio of the power of the first and second harmonics of the transglottal and mouth pressures were strongly correlated this empirical result supports the assertion that vocal fold drag is the principal source of sound in phonation

unsteady behavior of flow in a scaled up vocal folds model measurements of the fluid flow through a scaled up model of the human glottis are presented to determine whether glottal flow may be approximated as unsteady time and space resolved velocity vector fields from digital particle image velocimetry dpiv measurements of the flow through the gap between two moving rigid walls are presented in four cases over a range of strouhal numbers 0 010 0 018 0 035 0 040 corresponding to life scale f0 of 30 58 109 and 126hz respectively at a reynolds number of 8000 it is observed that 1 glottal flow onset is delayed after glottal opening and 2 glottal flow shutoff occurs prior to closure a comparison between flow through a fully open nonmoving glottis and that through the moving vocal folds shows a marked difference in spatial structure of the glottal jet the following features of the flow are seen to exhibit strong dependence on cycle frequency a glottal exit plane velocity b volume flow c vortex shedding rates and d vortex amplitude v

families of lagrangian fibrations on hyperkahler manifolds abstract a holomorphic lagrangian fibration on a holomorphically symplectic manifold is a holomorphic map with lagrangian fibers it is known due to huybrechts that a given compact manifold admits only finitely many holomorphic symplectic structures up to deformation we prove that a given compact simple hyperkahler manifold with b 2 7 admits only finitely many deformation types of holomorphic lagrangian fibrations we also prove that all known hyperkahler manifolds are never kobayashi hyperbolic

influence of collision on the flow through in vitro rigid models of the vocal folds measurements of pressure in oscillating rigid replicas of vocal folds are presented the pressure upstream of the replica is used as input to various theoretical approximations to predict the pressure within the glottis as the vocal folds collide the classical quasisteady boundary layer theory fails it appears however that for physiologically reasonable shapes of the replicas viscous effects are more important than the influence of the flow unsteadiness due to the wall movement a simple model based on a quasisteady bernoulli equation corrected for viscous effect combined with a simple boundary layer separation model does globally predict the observed pressure behavior

viscous effects in a static physical model of the uniform glottis the classic work on laryngeal flow resistance by van den berg et al j acoust soc am 29 626 631 1957 is revisited these authors used a formula to summarize their measurements and thus they separated the effects of entrance loss and pressure recovery from those of viscosity within the glottis analysis of intraglottal pressure distributions obtained from the physical model m5 r scherer et al j acoust soc am 109 1616 1630 2001 reveals substantial regions within the glottis where the pressure gradient is almost constant for glottal diameters from 0 005 to 0 16 cm as expected when viscous effects dominate the flow resistance of a narrow channel for this set of glottal diameters the part of the pressure gradient that has a linear dependence on the glottal volume velocity is isolated the inverse cube diameter of the poiseuille expression for glottal flows is examined with the data set provided by the m5 intraglottal pressure distributions the poiseuille effect is found to give a reasonable account of viscous effects in the diameter interval from 0 0075 to 0 02 cm but an inverse 2 59 power law gives a closer fit across all diameters

influence of glottal cross section shape on phonation onset phonation models commonly rely on the assumption of a two dimensional glottal geometry to assess kinetic and viscous flow losses in this paper the glottal cross section shape is taken into account in the flow model in order to capture its influence on vocal folds oscillation for the assessed cross section shapes rectangular elliptical or circular segment the minimum pressure threshold enabling to sustain vocal folds oscillation is altered for constriction degrees smaller than 75 the discrepancy between cross section shapes increases as the constriction degree decreases

a modified particle swarm optimizer with dynamic adaptation this paper proposes a modified particle swarm optimization algorithm with dynamic adaptation in this algorithm a modified velocity updating formula of the particle is used where the randomness in the course of updating particle velocity is relatively decreased and the inertia weight of each particle is different moreover this algorithm introduces two parameter describing the evolving state of the algorithm the evolution speed factor and aggregation degree factor by analyzing the influence of two parameters on the pso search ability a new strategy is presented that the inertia weight dynamically changes based on the run and evolution state in the strategy the inertia weight is given by a function of evolution speed factor and aggregation degree factor and the value of inertia weight is dynamically adjusted according to the evolution speed and aggregation degree the feature of the proposed algorithm is analyzed and several testing functions are performed in simulation study experimental results show that the proposed algorithm remarkably improves the ability of pso to jump out of the local optima and significantly enhance the convergence precision

ranking vocal fold model parameters by their influence on modal frequencies the purpose of this study was to identify using computational models the vocal fold parameters which are most influential in determining the vibratory characteristics of the vocal folds the sensitivities of vocal folds modal frequencies to variations model parameters were used to determine the most influential parameters a detailed finite element model of the human vocal fold was created the model was defined by eight geometric and six material parameters the model included transitional boundary regions to idealize the complex physiological structure of real human subjects parameters were simultaneously varied over ranges representative of actual human vocal folds three separate statistical analysis techniques were used to identify the most and least sensitive model parameters with respect to modal frequency the results from all three methods consistently suggest that a set of five parameters are most influential in determining the vibratory characteristics of the vocal folds

an effective genetic algorithm approach to multiobjective resource allocation problems moraps dynamic programming dp is a mathematical procedure designed primarily to improve the computational efficiency of solving select mathematical programming problems by decomposing them into smaller and hence computationally simpler subproblems in solving multiple objectives dynamic programming problem modp classical approaches reduce the multiple objectives into a single objective of minimizing a weighted sum of objectives the determination of these weights indicate the relative importance of the various objective also if the problem scale increases it become difficult to be dealt with even in the case of single objective because of the rapid expansion of the number of states to be considered in this paper we investigated the possibility of using genetic algorithms gas to solve multiobjective resource allocation problems moraps this procedure eliminates the need of any user defined weight factor for each objective also the proposed approach is developed to deal with the problems with both single or multiple objectives the simulation results for multiobjective resource allocation problems morap shows that genetic algorithms gas may hopefully be a new approach for such kinds of problems

irregular vocal fold vibration high speed observation and modeling direct observations of nonstationary asymmetric vocal fold oscillations are reported complex time series of the left and the right vocal fold vibrations are extracted from digital high speed image sequences separately the dynamics of the corresponding high speed glottograms reveals transitions between low dimensional attractors such as subharmonic and quasiperiodic oscillations the spectral components of either oscillation are given by positive linear combinations of two fundamental frequencies their ratio is determined from the high speed sequences and is used as a parameter of laryngeal asymmetry in model calculations the parameters of a simplified asymmetric two mass model of the larynx are preset by using experimental data its bifurcation structure is explored in order to fit simulations to the observed time series appropriate parameter settings allow the reproduction of time series and differentiated amplitude contours with quantitative agreement in particular several phase locked episodes ranging from 4 5 to 2 3 rhythms are generated realistically with the model

on the generalised fant equation abstract an analysis is made of the fluid structure interactions involved in the production of voiced speech it is usual to avoid time consuming numerical simulations of the aeroacoustics of the vocal tract and glottis by the introduction of fant s reduced complexity equation for the glottis volume velocity q g fant acoustic theory of speech production mouton the hague 1960 a systematic derivation is given of fant s equation based on the nominally exact equations of aerodynamic sound this can be done with a degree of approximation that depends only on the accuracy with which the time varying flow geometry and surface acoustic boundary conditions can be specified and replaces fant s original lumped element heuristic approach the method determines all of the effective source terms governing q it is illustrated by consideration of a simplified model of the vocal system involving a self sustaining single mass model of the vocal folds that uses free streamline theory to account for surface friction and flow separation within the glottis identification is made of a new source term associated with the unsteady vocal fold drag produced by their oscillatory motion transverse to the mean flow

iterated tabu search for the maximum diversity problem in this paper we deal with the maximum diversity problem mdp which asks to select a specified number of elements from a given set so that the sum of distances between the selected elements is as large as possible we develop an iterated tabu search its algorithm for solving this problem we also present a steepest ascent algorithm which is well suited in application settings where solutions of satisfactory quality are required to be provided very quickly computational results for problem instances involving up to 5000 elements show that the its algorithm is a very attractive alternative to the existing approaches in particular we demonstrate the outstanding performance of its on the mdp instances taken from the literature for 69 such instances new best solutions were found

identification of geometric parameters influencing the flow induced vibration of a two layer self oscillating computational vocal fold model simplified models have been used to simulate and study the flow induced vibrations of the human vocal folds while it is clear that the models responses are sensitive to geometry it is not clear how and to what extent specific geometric features influence model motion in this study geometric features that played significant roles in governing the motion of a two layer body cover two dimensional finite element vocal fold model were identified the model was defined using a flow solver based on the viscous unsteady navier stokes equations and a solid solver that allowed for large strain and deformation a screening type design of experiments approach was used to identify the relative importance of 13 geometric parameters five output measures were analyzed to assess the magnitude of each geometric parameter s effect on the model s motion the measures related to frequency glottal width flow rate intraglottal angle and intraglottal phase delay the most significant geometric parameters were thos

approximating multiobjective knapsack problems for multiobjective optimization problems it is meaningful to compute a set of solutions covering all possible trade offs between the different objectives the multiobjective knapsack problem is a generalization of the classical knapsack problem in which each item has several profit values for this problem efficient algorithms for computing a provably good approximation to the set of all nondominated feasible solutions the pareto frontier are studied for the multiobjective one dimensional knapsack problem a practical fully polynomial time approximation scheme fptas is derived it is based on a new approach to the single objective knapsack problem using a partition of the profit space into intervals of exponentially increasing length for the multiobjectivem dimensional knapsack problem the first known polynomial time approximation scheme ptas based on linear programming is presented

a new approach based on the genetic algorithm for finding a good shape parameter in solving partial differential equations by kansa s method many radial basis function rbf methods contain a free shape parameter that plays an important role for the accuracy of the method in most papers the authors end up choosing this shape parameter by trial and error or some other ad hoc means in this paper we propose applying the genetic algorithm to determine a good shape parameter of radial basis functions for the solution of partial differential equations we use meshless collocation method based on the radial basis function kansa s method to solve partial differential equations due to the severely ill conditioned matrix arising from using rbf we also consider the truncated singular value decomposition method tsvd for solving system of linear equations which is obtained from kansa s method numerical results show that the proposed algorithm based on the genetic optimization is effective and provides a reasonable shape parameter along with acceptable accuracy of the solution

dynamics of the two mass model of the vocal folds equilibria bifurcations and oscillation region the dynamics of the large amplitude oscillation of the vocal folds is analyzed using the two mass model first the equilibrium positions are determined in the case of a rectangular prephonatory glottis and the existence of two equilibrium positions besides the rest position is shown their stability is examined and a bifurcation diagram is derived with a normalized subglottal pressure and a coupling coefficient as control parameters phase plane plots are shown to illustrate the results the cases of convergent and divergent prephonatory glottis are then briefly considered the main results are finally discussed relative to previous analytical works it is shown that they disprove the previous oscillation theory based on the existence of a glottal negative differential resistance

the influence of glottal cross section shape on theoretical flow models physical and mathematical phonation models commonly rely on a quasi one dimensional flow model the assumption of quasi one dimensional flow through a glottis with fixed length is analyzed for different cross section shapes circle rectangle ellipse and circular segment a simplified flow model is formulated which accounts for kinetic losses viscosity and cross section shape it is seen that the cross section shape cannot be neglected since it alters boundary layer development and hence the viscous contribution to the pressure drop across the glottis the commonly applied quasi one dimensional flow model is shown to be inaccurate indicating the potential benefit of taking into account the cross section shape