Frequency-domain Modeling Technique Research Articles

Modeling of second-order nonlinear metasurfaces

We present a frequency-domain modeling technique for second-order nonlinear metasurfaces. The technique is derived from the generalized sheet transition conditions (GSTCs), which have been so far mostly used for modeling linear metasurfaces. In this work, we extend the GSTCs to include effective nonlinear polarizations. This allows retrieving the effective nonlinear susceptibilities of a given metasurface and predict its nonlinear scattering responses under arbitrary illumination conditions. We apply this modeling technique to the case of metasurfaces made of a periodic arrangement of T-shaped gold nanoparticles. For verification, several metasurfaces are fabricated and a fair agreement is found when comparing simulated data and experimental results. The proposed model may thus serve as a design platform to implement complex nonlinear metasurface based applications.

Small Signal Modeling and Decoupled Controller Design for a Triple Active Bridge Multiport DC–DC Converter

This article proposes modeling and two controller design techniques for a triple active bridge (TAB) three-port dc-dc converter comprising of fuel cell, battery, and load. The sources are integrated, employing boost interleaved full-bridge converters in order to get smoother source current profile. The converter is a nonlinear multi-input multi-output (MIMO) system with a large number of control variables. Moreover, a high degree of coupling among the control variables makes its modeling and control system design quite cumbersome and complex. To overcome the complexity of analysis in a higher order system like TAB, a generalized frequency-domain modeling technique is introduced in this article. A new decoupling matrix-based proportional-integral controller design method is also proposed. It reduces the design complexity and improves the system dynamic performance (lower settling time, overshoot/undershoot in the controlled variables) in comparison to similar three-port converters reported in the literature. Further, the performance of the proposed controller is compared by simulation with another popular MIMO system controller design technique, namely the state feedback control. A 1-kW laboratory prototype is built and tested to verify the system performance during dynamic load changes, source current variation, and battery charging/discharging operation.

A Rigorous Analysis of Least Squares Sine Fitting Using Quantized Data: The Random Phase Case

This paper considers least square (LS) based estimation of the amplitude and square amplitude of a quantized sine wave, done by considering random initial record phase. Using amplitude- and frequency-domain modeling techniques, it is shown that the estimator is inconsistent, biased, and has a variance that may be underestimated if the simple model of quantization is applied. The effects of both sine wave offset values and additive Gaussian noise are considered. General estimator properties are derived, without making simplifying assumptions on the role of the quantization process, to allow assessment of measurement uncertainty, when this LS procedure is used.

비례 솔레노이드 밸브의 운동해석 및 LQG/LTR 제어

In this study, dynamic analysis of a proportional solenoid valve is performed, and an LQG/LTR controller with an integrator is designed to control the proportional solenoid valve. The dynamic characteristic of a valve is identified using experimental data by employing the frequency-domain modeling technique. The purpose of LQG/LTR control with an integrator is to enhance the system response and to improve the tracking accuracy for a complex input signal. Experimental tests are performed to verify the performance of the controller, and the results prove the high performance of the controller.

Sliding mode control of the inchworm displacement with hysteresis compensation

This paper proposes a new modeling scheme to describe the hysteresis and the preload characteristics of piezoelectric stack actuators in the inchworm. From the analysis of piezoelectric stack actuator behavior, the hysteresis can be described by the functions of a maximum input voltage and the preload. The dynamic characteristics are also identified by the frequency domain modeling technique based on the experimental data. The hysteresis is compensated by the inverse hysteresis model for precise control of inchworm displacement. Since the dynamic stiffness of an inchworm is generally low compared to its driving condition, the mechanical vibration may degrade accuracy of the inchworm. Therefore, the SMC (Sliding Mode Control) and the Kalman filter are developed for the motion control of the inchworm. The feasibility of the proposed modeling scheme and the control algorithm is tested and verified experimentally.

이송자벌레를 위한 압전소자의 모델링 및 운동제어 : 2. 슬라이딩 모드법에 의한 이송자벌레의 운동제어

This paper presents an algorithm for the precision motion control based on the dynamic characteristics of piezoelectric actuators in the inchworm. The dynamic characteristics are identified by the frequency domain modeling technique using the experimental data. For the motion control, the hysteresis behavior is compensated by the inverse hysteresis model. The dynamic stiffness of an inchworm is generally low compared to its driving condition, so mechanical vibration may degenerate the motion accuracy of the inchworm. The Sliding mode controller and the Kalman filter are designed for motion control of the inch-worm.

소형 재료시험기의 모델링 및 진동 제어

This paper proposes the modeling scheme of the Miniature Universal Testing Machine (MUTM) composed of 36 thin-beam-type bimorph PZTs and the control algorithm to minimize the residual vibration of the MUTM in the dynamic testing of specimens. In the operation of the MUTM, hysteresis, residual displacement and vibration of it are major issues. From the analysis of the MUTM behaviors, the hysteresis is described by the curving fitting scheme with the function of an input voltage. The dynamic characteristics of the MUTM are identified by the frequency domain modeling technique based on the experimental data. The interested bandwidth is focused on 125-315HZ for effective modeling and control. For the robust vibration control of the MUTM, the sliding mode control and the Kalman filter as observer are proposed. The paper also proposes the best input signal type to operate the MUTM effectively. The feasibility of the proposed modeling scheme and control algorithm are tested and verified experimentally.

Synthesis of the sound pressure radiated by a guitar using a mixed time- and frequency-domain modeling technique

A general method has been previously developed by O. Beslin etal. [J. Acoust. Soc. Am. 89, 1868 (A) (1991)], using a variational method to describe the motion of a perforated plate, and a integral formulation for the modeling of the consecutive radiated sound pressure. This model is now adapted to the particular case of a guitar, whose top plate is represented by a rectangular orthotropic plate with hole and back cavity. The sound pressure computation is carried out in the frequency domain, for a point force acting at the bridge. This yields the pressure versus force transfer function H(ω), from which the corresponding impulse response h(t) can be derived by means of inverse Fourier transforms. Finally, the guitar tones are obtained by convolving h(t) with a time-domain formulation of the force F(t) imparted to the bridge by a guitar string, using a finite difference method previously developed by A. Chaigne [J. Acoust. 5(2), 181–211 (1992)]. This model is used for investigating the influence of various plate parameters on timbre and sound quality of the instrument.