The purpose of the present paper is to clarify the effects of unsteady glottal flow on phonation. We perform numerical experiments with respect to vocal cord vibrations in order to verify the validity of the proposed ...
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The purpose of the present paper is to clarify the effects of unsteady glottal flow on phonation. We perform numerical experiments with respect to vocal cord vibrations in order to verify the validity of the proposed model for a glottal sound source. In addition, the prediction of pressure waves induced by unsteady glottal jets is attempted. Good agreement between the numerical results and the measured data of the properties of the glottal source indicates that the proposed model is a good tool for the analysis of speech production. Simulated pulsatile glottal jets show the generation of high-frequency noises in a pressure wave at the glottis and the unsteady and asymmetric motion of vortices. These vortices cause amplitude fluctuations in the pressure wave downstream near the glottis, although pressure waves far from the glottis are not greatly affected. In conclusion, the unsteady glottal flow affects only the area near the glottis and does not greatly affect speech waves radiating from the mouth.
In this paper,modeling and control of manipulator handling a flexible payload is considered under the parameter uncertainty and the unknown disturbance.A new sliding mode controller is proposed for manipulator handlin...
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In this paper,modeling and control of manipulator handling a flexible payload is considered under the parameter uncertainty and the unknown disturbance.A new sliding mode controller is proposed for manipulator handling a flexible payload based on a distributed-parameter dynamic model and hence is free from the so-called spillover instability,then extended to an adaptive scheme to cope with the upper bounds of the uncertainties were *** controllers are designed to realize system trajectory tracking performance and suppress the elastic *** sliding surface is designed as coupling the joint angle and angular velocity of link,as well as root strain and shear force of flexible *** of the system is proved by using Lyapunov *** simulations result provided to verify the effectiveness of the approach presented.
In this paper, the coupled dynamics and control of the vessel, crane, flexible cable and payload under environmental disturbances with attached thrusters for subsea installation operations is investigated. For the pra...
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In this paper, the coupled dynamics and control of the vessel, crane, flexible cable and payload under environmental disturbances with attached thrusters for subsea installation operations is investigated. For the practical system with physical constraints, we employ Barrier Lyapunov Function in the design of positioning control for the flexible crane-cable-payload subsystem to ensure that the constraints are not violated. Uniform stability of the flexible subsystem is shown and asymptotic positioning of the boundaries is achieved. Next, we tackle the scenario where non-uniformity of the cable, uncertainties and environmental disturbances are considered. Boundary controls are formulated using the nonlinear partial differential equation of the cable. Numerical simulations are provided to illustrate the performance of the proposed controls.
Transmission line parameters are essential inputs to various power system analysis programs and applications such as protective relaying algorithms, and precision of line parameters is thus significant in ensuring the...
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Transmission line parameters are essential inputs to various power system analysis programs and applications such as protective relaying algorithms, and precision of line parameters is thus significant in ensuring the analysis accuracy and algorithm reliability. This paper proposes methods for estimating positive sequence parameters of a series compensated transmission line. The methods are based on distributedparameter line model and utilize voltages and currents from both terminals of the line during normal operations. In particular, based on nonlinear estimation theory, an optimal estimator is designed for deriving positive sequence line parameters. The algorithm is capable of detecting and identifying bad measurement data, and thus improving the estimation accuracy. The proposed method is independent of the operation status of the compensation device.
The mechanism of fluid flow and heat transfer in the heat exchangers was investigated in this paper. Using R22 as the working fluid, the steady distributed parameter models of condenser and evaporator in a residential...
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ISBN:
(纸本)9783037851272
The mechanism of fluid flow and heat transfer in the heat exchangers was investigated in this paper. Using R22 as the working fluid, the steady distributed parameter models of condenser and evaporator in a residential split air-conditioner were established based on thermophysical laws such as mass, momentum and energy conservation equations. The regions of two-phase fluid and superheated gas in evaporator and the regions of superheated gas, two-phase fluid and subcooled liquid in condenser were respectively simulated under designed conditions of air-conditioning system. Based on the calculated results, the flow and heat transfer performances of heat exchangers were analyzed. The results show that the two-phase fluid regions in both evaporator and condenser have great influence on the fluid flow and heat transfer performances in it.
This paper presents a method for locating faults on HVDC transmission lines using two terminal data. Different from those based on the traveling wave principle, the new fault-location algorithm can use any section of ...
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This paper presents a method for locating faults on HVDC transmission lines using two terminal data. Different from those based on the traveling wave principle, the new fault-location algorithm can use any section of the postfault data to locate faults. The proposed method is developed based on the distributedparameter line model in which the voltage distribution over the line can be obtained from the voltage and current measurements at both terminals and point where fault occurs can be identified from the calculated voltage distribution. The fault-location algorithm is performed in time domain and thus a short data window is sufficient for it to achieve satisfactory accuracy in practice. The proposed algorithm is simulated using data of the frequency-dependent line model in EMTDC and data of an existing HVDC line as well. The simulations have shown that this method is valid and is capable of locating the faults occurring on HVDC transmission lines quickly and accurately.
A recuperator is a key component and plays an important role in the high-temperature gas-cooled reactor combined with gas turbine (HTGR-GT) system. A distributed parameter model was proposed to study the dynamic chara...
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A recuperator is a key component and plays an important role in the high-temperature gas-cooled reactor combined with gas turbine (HTGR-GT) system. A distributed parameter model was proposed to study the dynamic characteristics of the recuperator of the HTGR-GT cycle, and this model was solved using an implicit arithmetic. Basic characteristics of the recuperator were analyzed using responses of the recuperator to step disturbances of temperature and mass flow. The response of the recuperator to the temperature disturbances has two different characteristic times tau(1) and tau(2) depending on the relation between the response and the disturbance. The response of the recuperator to mass flow disturbance has a characteristic time tau(4) that is between tau(1) and tau(2). An example of coupled disturbance of temperature and mass flow was simulated by the distributed parameter model. This example shows the influence of the three characteristic times to the dynamic characteristics of the recuperator. When the system power of HTGR-GT is regulated slowly, the core temperature distribution of the recuperator hardly varies. However, when the electric load of the system is rejected from full power, the core temperature, especially in the front of the recuperator, suffers from a drastic change in temperature.
In this paper a collaborative simulation platform for proton exchange membrane fuel cell (PEMFC) power systems is presented, where the stack is simulated by a two-phase distributed parameter model and the auxiliary un...
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In this paper a collaborative simulation platform for proton exchange membrane fuel cell (PEMFC) power systems is presented, where the stack is simulated by a two-phase distributed parameter model and the auxiliary units by lumped parametermodels. By exchanging the dynamic data between the external load/auxiliary units and PEMFC stack, dynamic simulation of PEMFC stack has been carried out during the load changes for various states associated with different characteristic variables. The internal states of the stack can be observed due to variation of external load/auxiliary units. Numerical experiments are provided for a special case with multiple cycles of load changes derived from an acceleration mode of a fuel cell vehicle. The numerical results demonstrate that the "undershoot" of output voltage is due to the response lag of the auxiliary units and liquid water accumulation in the fuel cell stack. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
Superfluid helium is used in the cryogenic circuit that cools down and stabilizes temperature of more than 1600 high performance, main superconducting magnets of the Large Hadron Collider (LHC) - the new particle acce...
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ISBN:
(纸本)9781424453634
Superfluid helium is used in the cryogenic circuit that cools down and stabilizes temperature of more than 1600 high performance, main superconducting magnets of the Large Hadron Collider (LHC) - the new particle accelerator at European Organization for Nuclear Research (CERN). This paper presents a simulation study of the application of Nonlinear model Predictive Control (NMPC) to the Superfluid Helium Cryogenic Circuit. First, the new first principles, distributed parameter model of the circuit to be used in online optimization is reviewed. Then stabilization of the superconducting magnets temperature using NMPC based on the model and Continuation/Generalized Minimum Residual (C/GMRES) algorithm is described. Finally the small computational cost of C/GMRES solution/approximation method and resulting real-time feasibility are highlighted.
An accurate fault location algorithm for parallel transmission lines, using fundamental frequency components of post-fault voltage and current measured at one terminal, is described in this paper. Parallel transmissio...
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An accurate fault location algorithm for parallel transmission lines, using fundamental frequency components of post-fault voltage and current measured at one terminal, is described in this paper. Parallel transmission lines can be decoupled into the common component net and differential component net. In differential component net, the current distributing coefficient is a function of fault distance, and the differential component current at the fault point can be expressed in terms of the current at the local terminal. Therefore, for asymmetrical faults, the phase fault current can also be expressed as a function of local terminal current and fault distance. With the fault boundary conditions for a given fault type. the fault location equations can then be derived. Based on distributedparameter line model, the proposed algorithm achieves superior locating accuracy, with mutual coupling between circuits, source impedance and fault resistance having very little influence on the locating accuracy. The performance of new algorithm is verified by computer simulation results for transposed and non-transposed lines. (c) 2008 Elsevier Ltd. All rights reserved.
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