A transfer function method of modeling systems with frequency-dependent coefficients

Jefferys, E.R.; Broome, D R; Patel, M.H.

doi:10.2514/3.19883

Cited by 14 publications

(7 citation statements)

References 4 publications

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“…진동 전달 함수는 통상 진동원과 시불변 시스템의 진동 발생 결과 사이 수학적 관계식으로 정의되고 있다 (Jefferys, et al, 1984;Halevi and Wagner-Nachshoni, 2006) …”

Section: 진동 주파수 응답 함수unclassified

Experimental Study of Vibration Characteristics of OKPO 300

황¹

2016

Journal of Ocean Engineering and Technology

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This paper presents experimental results for the vibration characteristics of the small unmanned underwater vehicle (UUV) OPKO 300, which was designed and manufactured by Daewoo ship and Marine Engineering Ltd. The autonomy of UUVs has led to an increase in their use in scientific, military, and commercial areas because their autonomy makes it possible for UUVs to be utilized instead of humans in hazardous missions such as mine countermeasure missions (MCM). Since it is impossible to use devices based on electromagnetic waves to gather information in an underwater environment, only sonar systems, which use sound waves, can be used in underwater environments, and their performance can strongly affect the autonomy of a UUV. Since a thruster system, which combines a motor and propeller in a single structure, is widely used as the propulsion system of a UUV and is mounted on the outside of a UUV's stern, it can generate vibration, which can be transferred throughout the shell of the UUV from its stern to its bow. The transferred vibration can affect the performance of various sonar systems such as side-scan sonar or forward-looking sonar. Therefore, it is necessary to estimate the effect of the transferred vibration of the UUV on the sonar systems. Even if

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Section: 진동 주파수 응답 함수unclassified

Experimental Study of Vibration Characteristics of OKPO 300

황¹

2016

Journal of Ocean Engineering and Technology

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“…25 20 showed experimentally that the LEV circulation is highly sensitive to the Strouhal number in the range 0.3 < St < 0.5, concurrent with an accelerated roll-up of the leading-edge vortex. Choi et al 18 investigated numerically the flow structure and mean fluctuating lift for surging and plunging airfoils at low Reynolds numbers.…”

Section: Introductionmentioning

confidence: 98%

Experimental-Based Unified Unsteady Nonlinear Aerodynamic Modeling For Two-Dimensional Airfoils

Zakaria

Taha

Hajj

et al. 2015

33rd AIAA Applied Aerodynamics Conference

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Unsteady force measurements of a plunging airfoil at different frequencies and mean angles of attack are used to construct frequency response models. The obtained frequency response models are then used to determine the linearized flow dynamics around each mean angle of attack, where an optimization-based linear system identification is performed to minimize the error between the predicted and measured frequency responses. Converting these models to state space form and writing the entries of the matrices as polynomials in the mean angle of attack, a global, unified unsteady model is developed. The developed reduced order model, represented in a state space form, is suitable for characterizing the nonlinear dynamical characteristics of the flow and the associated dynamics and control of a flying object.

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“…Therefore, alternative approaches have been proposed to replace the convolution integrals in the system of motion equations, such as implementing a transfer function of the radiation convolution [15], or state-space formulations [16][17][18].…”

Section: Radiation Forcementioning

confidence: 99%

Wave-to-Wire Modelling of WECs

Alves¹

2016

Ocean Engineering &Amp; Oceanography

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Numerical modelling of wave energy converters (WECs) of the wave activated body type (WAB, see Chap. 2) is based on Newton's second law, which states that the inertial force is balanced by all forces acting on the WEC's captor. These forces are usually split into hydrodynamic and external loads.In general, the hydrodynamic source comprises the (more details in Chap. 6):• Hydrostatic force caused by the variation of the captor submergence due to its oscillatory motion under a hydrostatic pressure distribution, • Excitation loads due to the action of the incident waves on a motionless captor, • Radiation force corresponding to the force experienced by the captor due to the change in the pressure field as result of the fluid displaced by its own oscillatory movement, in the absence of an incident wave field.Depending on the type of WEC, the external source may include the loads induced by the • Power-take-off (PTO) equipment, which converts mechanical energy (captor motions) into electricity (more details in Chap. 8), • Mooring system, responsible for the WEC station-keeping (more details in Chap. 7), • End-stop mechanism, used to decelerate the captor at the end of its stroke in order to dissipate the kinetic energy gently, and therefore avoid mechanical damage to the device.

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A transfer function method of modeling systems with frequency-dependent coefficients

Cited by 14 publications

References 4 publications

Experimental Study of Vibration Characteristics of OKPO 300

Experimental Study of Vibration Characteristics of OKPO 300

Experimental-Based Unified Unsteady Nonlinear Aerodynamic Modeling For Two-Dimensional Airfoils

Wave-to-Wire Modelling of WECs

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