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The effect of three-dimensional glottal geometry on intraglottal quasi-steady flow distributions and their relationship with phonation

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Science China(Life Sciences) 2006年第1期49卷 82-88页

作者： SCHERER Ronald C. Department of Communication Disorders Bowling Green State University 200 Health Center Bowling Green Ohio 43402 USA

Vocal fold geometry plays an important role in human phonation. The intraglottal quasi- steady pressure and velocity distributions depend upon the shape, size, and diameter of the glottis. This study reports the effects of the variation of glottal shapes on intraglottal pressures and velocities using a Plexiglas model with a glottis having nine symmetric glottal angles (uniform, as well as con-vergent and divergent 5°, 10°, 20° and 40°), while the minimal glottal diameter was held constant at 0.06 cm. The empirical data were supported by penalty finite element computational results. The re-sults suggest that larger convergent glottal angles correspond to increased pressures and decreased velocities in the glottis upstream of the minimum glottal location, with a reversal of this pattern at the minimal glottal diameter location. The pressure dip near the glottal entrance for divergent glottal an-gles was greatest for the 10° divergence angle condition, and was sequentially less for 5°, 20°, and 40°. Flow resistance was greater for a convergent angle than a divergent angle of the same value, and least for the 10° divergent condition. Pressure recovery in the glottis suggested that the optimal glottal diffuser angle was near 10°. Results suggest that the glottal geometry has a critical relationship with phonation (especially for vocal efficiency), and therefore important significance to understanding artistic voice and clinical voice management.

关键词： vocal fold geometry, laryngeal aerodynamics modeling, phonation, quasi-steady flow.

Weather induced subtidal flows through multiple inlets of an arctic microtidal lagoon

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Acta Oceanologica Sinica 2019年第3期38卷 1-16页

作者： Chunyan Li Kevin M.Boswell Nazanin Chaichitehrani Wei Huang Renhao Wu Department of Oceanography and Coastal Sciences College of the Coast and Environment Louisiana State University Department of Biological Sciences Florida International University Horn Point Laboratory Center for Environmental Science University of Maryland College of Marine Sciences and Technology Zhejiang Ocean University

Estuarine processes in the arctic lagoons are among the least studied but important subjects, especially considering the rapid warming of arctic water which may change the length of ice-free period in the summer. In this paper, wind-driven exchange flows in the micro-tidal Elson Lagoon of northern Alaska with multiple inlets of contrasting widths and depths are studied with in situ observations, statistical analysis, numerical experiments, a regression model on the basis of dynamics, and remote sensing data. Water velocity profiles were obtained from a bottom deployed acoustic Doppler current profiler(ADCP) in the northwestern Eluitkak Pass connecting the Beaufort Sea to the Elson Lagoon during a 4.9 day ice-free period in the summer of 2013. The subtidal flow is found correlated with wind(R^2 value ～96%). Frequently occurring east, northeast and north winds from the arctic atmospheric high-and low-pressure systems push water from the Beaufort Sea into the lagoon through the wide inlets on the eastern side of the lagoon, resulting in an outward flow against the wind at the narrow northwestern inlet. The counter-wind flow is a result of an uneven wind forcing acting through the asymmetric inlets and depth,an effect of "torque" or vorticity. Under northwest wind, the exchange flow at the northwestern inlet reverses its direction, with inward flows through the upwind northwestern inlet and outward flows through the downwind eastern inlets. A regression model is established based on the momentum equations and Taylor series expansions. The model is used to predict flows in July and August of 2015 and July of 2017, supported by available Landsat satellite images. About 73%–80% of the time the flows at Eluitkak Pass are out of Elson Lagoon for the summer of 2015 and 2017. Numerical experiments are conducted to corroborate the findings and illustrate the effects under various wind conditions. A quasi-steady state balance between wind force and surface pressure gradient is c

关键词： wind-driven flows multiple inlets micro-tidal numerical model experiments counter-wind flows quasi-steady state

Nonlinear flutter analysis of stiffened composite panels in super-sonic flow

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Science China(Physics,Mechanics & Astronomy) 2010年第2期53卷 336-344页

作者： YUAN KaiHua & QIU ZhiPing School of Aeronautic Science and Engineering,Beijing University of Aeronautics and Astronautics,Beijing 100191,China School of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics Beijing China

The flutter instability of stiffened composite panels subjected to aerodynamic forces in the supersonic flow is investigated. Based on Hamilton's principle,the aeroelastic model of the composite panel is established by using the von Karman large deflection plate theory,piston theory aerodynamics and the quasi-steady thermal stress theory. Then,using the finite element method along with Bogner-Fox-Schmit elements and three-dimensional beam elements,the nonlinear equations of motion are derived. The effect of stiffening scheme on the flutter critical dynamic pressure is demonstrated through the numerical example,and the nonlinear flutter characteristics of stiffened composite panels are also analyzed in the time domain. This will lay the foundation for design of panel structures employed in aerospace vehicles.

关键词： panel flutter piston theory finite element method quasi-steady thermal stress critical dynamic pressure stiffened composite panel

A probabilistic power flow calculation method considering the uncertainty of the static frequency characteristic

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Global Energy Interconnection 2019年第1期2卷 45-53页

作者： Yi Wang Xiufen Shen Zemei Dai NARI Group Corporation (State Grid Electric Power Research Institute) NARI Technology Co.Ltd

In a power system, power generation and load have frequency response characteristics, which randomly fluctuate with changes in operating status. This study investigates a probabilistic power flow method that considers the unit and load uncertainty of the static frequency characteristic. Firstly, a calculation model is established on the basis of the characteristics of the frequency modulation performance of the unit and load. Then a calculation method is developed using the concept of dynamic power flow in order to determine the probability distribution of the active power flow of each line under the occurrence of a fault in the system. In the method, Monte Carlo sampling with the semi-invariant method is applied for analysis and calculation. The IEEE-30-buses system is taken as an example to analyze the impact of different responses of units on the power flow distribution of various branches. The method discussed herein is compared with the Monte Carlo simulation method to verify its effectiveness.

关键词： Uncertainty of frequency characteristics Probabilistic power flow Cumulant method quasi-steady state sen sitivity formatting

Iterative approximate solutions of kinetic equations for reversible enzyme reactions

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Natural Science 2013年第6期5卷 740-755页

作者： Sarbaz H. A. Khoshnaw Department of Mathematics University of Leicester Leicester UK

We study kinetic models of reversible enzyme reactions and compare two techniques for analytic approximate solutions of the model. Analytic approximate solutions of non-linear reaction equations for reversible enzyme reactions are calculated using the Homotopy Perturbation Method (HPM) and the Simple Iteration Method (SIM). The results of the approximations are similar. The Matlab programs are included in appendices.

关键词： Enzyme Kinetics Homotopy Perturbation Method Iteration Method Michaelis-Menten Kinetics quasi-steady State Approximation

The Aerodynamics and Compact Dynamic Model of a Flapping Wing Vehicle

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The Aerodynamics and Compact Dynamic Model of a Flapping Win...