Nonlinear RC Research Articles

A smart component model replacement approach for refined simulation of large nonlinear RC structures

This paper proposes a novel smart component model replacement (SCMR) approach that is not only efficient for large-scale nonlinear structural analysis, but also accurate in the refined simulation of components of interest. The method creates a FE model with a relatively coarse mesh to simulate the entire structure. During analysis, when a component is identified to predefined criteria defined by the users, its model will be replaced by another more refined “substructure” model that can simulate the damage and failure more accurately. A few “replacement” strategies are presented for smoothly transiting between different models: (1) A gradually transiting strategy is presented to avoid the possible jumps of responses due to the model differences to guarantee numerical stability; (2) The historical boundary conditions are applied to the substructure model to address the historical dependence of responses; (3) The boundary connection between main and substructure is considered by using a flexible client/server technology, to simplify the replacement. The SCMR approach is verified by three application examples. The results demonstrate that the proposed modeling approach can efficiently perform large-scale nonlinear structural analysis, while capturing the failure mechanism in RC structures well.

DINAMIC FORCES IN THE ECCENTRICALLY COMPRESSED MEMBERS OF REINFORCED CONCRETE FRAMES UNDER ACCIDENTAL IMPACTS

Interest to solving scientific problems related to the evaluation of facilities' resistance and its protection against progressive collapse increases and attracts more and more attention of specialists in the field of structural analysis and design. Therefore, the article presents the results of a computational analysis of dynamic forces in eccentrically compressed reinforced concrete members of structures under accidental impact such as sudden removal of a load bearing member. Using relations for specific deformation energy and integrating it through the cross-section area, the analytical expressions for dynamic strains and curvatures have been obtained for physically and structurally nonlinear RC frame members under eccentric compression. These expressions in some cases allow symbolic solution, for example, in MathCAD software. In contrary, it can be solved with the approximate iterative method. To assess the reliability and effectiveness of the proposed quasi-static method, the analysis of the cast-in-situ reinforced concrete frame resistance to progressive collapse has been performed. The article also provides comparison of the simulation results of the nonlinear quasi-static analysis and the nonlinear dynamic time-history analysis.

A fully integrated chaos generator based on voltage controlled oscillator

A new integrated chaos generator based on Voltage-Controlled-Oscillators (VCO) is proposed in this paper. The proposed generator consists of a nonlinear resistor and RC coupling circuit integrated with VCO. It is fully integrated instead of using discrete components compared with the traditional chaotic circuits. The proposed circuit exhibits excellent performances in the stable power supply, low power consumption, and small chip area cost. This chaotic circuit is fabricated in SMIC 180 nm CMOS process and it occupies a chip area of 0.039 mm2. The simulation results show that the proposed circuit could work in the frequency range from 11 MHz to 36 MHz with the maximum 2.0892 mW power consumption with a 1.8 V power supply. The range of the Lyapunov exponent is from 0.5628 to 2.2136. It shows potential application values of the designed fully integrated chaotic circuit.

Robustness of Model-Predictive and Passivity-Based Control in the Three-Phase DC/AC Converter Application

In modern controller design, various solutions for controlling power converter systems can be found depending on their applications, speed of working, pulse width modulation (PWM) techniques, switching frequencies—fc, and different load types. The need to manipulate control parameters can be often observed in classical structures, e.g., well-known PID, repetitive, or deadbeat control particularly sensitive to distinct parameters uncertainties. The purpose of this paper is to present an improved version of controllers designated for a UPS that will be considerably resistant to model changes. Proposed control techniques are independent of unexpected output filter changes: Lf—filter coil inductance and Cf—filter capacitor conductance. The second aspect of this paper is to compare effectiveness of modified predictive MPC (model-predictive control) and feedback PBC (passivity-based control) controllers in reducing output voltage total harmonic distortion (THD) for various load values. The biggest distortions of output voltage were observed during experiments with nonlinear RC load. Both simulation and experimental verification of mismatching parameters were performed and examined. Thanks to the proposed solution, the output voltage THDv quality factor was reduced below 8% in an efficient way for all the applied loads and stayed at the level of 1% when well-matched filter parameters were provided.

Technical Limits of Passivity-Based Control Gains for a Single-Phase Voltage Source Inverter

Passivity-based control (PBC) seems to be predicted for the control algorithms in the voltage source inverters (VSI) for voltage backup systems. This paper presents limitations of the improved (IPBC) version of the PBC (directly measuring the output voltage) maximum voltage and current gains. In a microprocessor-controlled inverter, these depend on the PWM modulator dynamic properties, the switching frequency, the modulation index value (avoiding modulator saturation and enabling the rapid increase of the filter inductor current), and the parameters of the VSI output filter. A single switching period delay of the digital PWM modulator was considered in the theoretical calculations based on a discrete inverter model. The simulations for the standard nonlinear rectifier RC load enabled the initial adjustment of the IPBC border gains, which depended on the switching frequency. Some small harmonics oscillations of the output voltage were acceptable for the test rectifier RC load or dynamic load. However, oscillations of the inductor current increased the power losses in the coil core. Experimental verification of the simulation results using a laboratory VSI model is also presented.

Splitting model reduction for bilinear control systems

AbstractIn this paper, based on low‐rank balanced truncation (BT), we present a splitting model reduction method for bilinear control systems with nonzero initial conditions. By analyzing Volterra series, the original bilinear control system is split up into two systems: one is a bilinear control system with zero initial condition, and the other is our constructed control system. Specifically, we prove that the Volterra series containing initial condition of the original system converges to the output of our constructed control system. Thus, we develop a new splitting model reduction method that involves reducing two systems independently by low‐rank BT method and then combining the reduced outputs into an aggregate output. A nonlinear RC circuit and a heat transfer model are taken as numerical examples to illustrate the effectiveness of our proposed method.

Nonlinear reflection coefficient of finite amplitude waves

Ultrasonic waves incident at the interface between two linear media will be reflected based on the linear reflection coefficient, which depends on the linear acoustic impedances of the media. However, propagation of ultrasonic waves in quadratically nonlinear media can lead to nonlinear reflection coefficients which are dependent on the frequency, source amplitude, and nonlinearity of the two mediums. The objective of this work is to explore the existence of a nonlinear reflection coefficient between two mediums using analytical, numerical, and experimental methods. For simplicity and consistency, a water-solid interface was chosen and finite amplitude ultrasonic waves between 2.25 MHz and 25 MHz were used to study the interfacial response. The analytical results show the existence of a nonlinear RC, but whose effect is very minimal. Experimental and numerical results show that the transfer of energy in harmonic generation affects the RC more than other factors. The influence of several factors like interaction zone, shock generation, etc. will be discussed.

Different Features of Control Systems for Single-Phase Voltage Source Inverters

The aim of this paper is to determine which type of control loop is better for each particular type of standard voltage source inverter (VSI) load (static, dynamic, nonlinear rectifier resistive-capacitive RC load). A comparison of three different types of controllers for single-phase VSIs is presented. The first two are of the single input single output (SISO)/proportional-integral-derivative controller (PID) and coefficient diagram method (CDM) types, and the third is of the multi-input single output (MISO)/passivity-based control (PBC) type. The selections of the gains for SISO and MISO controllers are presented, including the problem in the choice of PBC controller gains caused by the imperfection of the pulse width modulation (PWM) modulator. For a standard nonlinear rectifier RC load, the new control quality factor (CQF) is defined to distinguish the properties of the controllers. The results show the superiority of the MISO-PBC controller for the RC load; however, for a linear dynamic load, the MISO-PBC performed worse than the SISO-PID or CDM. Therefore, the choice between either a simple and inexpensive SISO with one measurement trace or an expensive MISO with three measurement traces depends on the purpose of the VSI. The initial simulations and measurements of the experimental models are presented and discussed.

Debonding evolution in nonlinear FRP-retrofitted RC beams with cohesive interface

A novel semi-analytical formulation of the governing equations of an FRP retrofitted reinforced concrete beam under bending, based on the concept of moment-curvature, is presented and it is applied to compute the complete nonlinear load-deflection curve, FRP-concrete interfacial shear stress, the FRP laminate strain and the debonding load of statically determinate RC beams retrofitted by an adhesively bonded FRP laminate. The beam may be subjected to any loading, including uniformly distributed or discrete point load(s). The governing equations satisfy the equilibrium and strain compatibility requirements of the beam but slip at the FRP-concrete interface is permitted. A novel procedure for constructing the full nonlinear moment-curvature relationship of beams undergoing interfacial slip is presented in detail, but it is shown that practically a trilinear relationship is satisfactory for obtaining an accurate estimate of the beam deflection and stresses. The robustness and accuracy of the method are demonstrated by analyzing several beams tested by other researchers under uniformly distributed load or four-point bending, with remarkably close agreement between the experimental and corresponding computed values.

A Neural Network Based Approach to Simulate Electrothermal Device Interaction in SPICE Environment

An innovative modeling methodology for the simulation of electrothermal interaction in power devices, based on neural networks (NNs), is shown. The suitability of NNs in modeling the complicated nonlinear, temperature dependent characteristic that power electronics devices feature is shown. The proposed methodology is particularly suited to be implemented in electrical simulators. The approach can be divided in two parallel steps: first, NNs are used to describe the complex, highly nonlinear electrothermal characteristic of the considered device; and second, a nonlinear RC -based thermal model is generated, with a method published in a previous work. These two subsystems are coupled together in order to achieve a self-consistent electrothermal model. The modeling results are validated against experiments with very satisfactory results. The technique is explained in detail; advantages and limitations of the method are then discussed.

Application of fiber model considering the shear effect in the analysis of nonlinear RC shear wall

Because of the good performance of the fiber model in the simulation of axial and bending coupling, the new fiber model considering the axial, bending and shear effects is established to analysis the nonlinear properties of RC shear wall. The way of the shear fiber distribution in the cross section consistent with the axial fiber and each shear fiber current state of stiffness get from the independent shear hysteretic rules, then establish tangent element stiffness matrix containing the axial, bending and shear deformation under complex loading paths. Two different cross-section fiber models is compared. Compiling corresponding calculation program to simulate a shear wall’s nonlinear performance under monotonic load and compare with the laboratory RC shear wall test results to verify the validity of the model.

Some Aspects of Voltage Source Inverter Control

The model of a voltage source inverter depends on its output filter. The parameters of this filter can differ significantly from their nominal values due to power losses in the core of the output coil and changes in its inductance. Only Multi-Input-Single-Output control systems can effectively reduce inverter output voltage distortions for a standard nonlinear rectifier RC load. However, their design requires knowledge of the actual values of the inverter parameters. The novelty of the paper is that it connects the designs of two MISO control systems with a method of the automated measurements of the voltage source inverter parameters. The breadboard verification is also included.DOI: http://dx.doi.org/10.5755/j01.eie.23.2.17995

Nonlinear Equivalent-Circuit Modeling of a Fast Photodiode

A new nonlinear equivalent circuit model of a photodiode is proposed to describe the conversion of the laser relative intensity noise to microwave phase noise. This conversion is realized through a nonlinear RC circuit. The validity of this model has been confirmed by the good agreement between simulation and experimental results at different microwave frequencies. These simulations have been performed using commercially available harmonic balance simulation software.

Optimal performance-based design of non-linear stochastic dynamical RC structures subject to stationary wind excitation

Performance-based design, or performance-based engineering (PBE), is currently well accepted as a proper methodology for assessing risk and designing facilities which can be subject to continuous levels of damage caused by extreme responses under various hazards of varying magnitudes. However, the difficulties in assessing probabilities associated with different hazard and performance levels, especially when nonlinearity is considered in dynamically excited structural systems, have been a limiting factor for incorporating PBE into design optimization. This paper advances the state-of-the-art by incorporating PBE into the optimal design of non-linear/hysteretic stochastic dynamical systems. The approach combines a statistical linearization technique with time-variant reliability analysis concepts, in order to formulate a total expected life-cycle cost optimization problem. As a numerical example, reinforced concrete buildings modeled as MDOF Bouc–Wen hysteretic systems subjected to wind excitation are studied. Optimal transversal stiffness of the buildings columns are obtained both for the linear and the nonlinear cases, as well as for various design life values. Optimal stiffness values determined herein consider the initial costs but also expected losses over the lifetime of the structure, for several wind hazard magnitudes and displacement response levels of the structure.

Application of Volterra-Wiener spline series for the analysis of nonlinear electric circuits

The functional atlas of the initial system of nonlinear differential equations is split into local charts with the help of a multidimensional Taylor series expansion. In each chart, the approximation with a weakly nonlinear Volterra-Wiener series up to the fourth order is used, where a chart is changed when its boundaries are crossed. It is established that the obtained approach allows one to increase the accuracy and reliability of the calculated output response of the nonlinear system as compared to the classical Volterra-Wiener series approach. The results of the numerical simulation of a nonlinear RC circuit are presented and the efficiency of the proposed method is shown.

Model Reduction of Bilinear System using Genetic Algorithm

In designing control system, it is important to minimize the order of controller since the high order controller is impractical. In this paper we propose a method to obtain the minimum order of bilinear system by using the genetic algorithm. The process of optimization is to minimize the 2 H -norm from the transfer function from input to output which implies suppressing the magnitude peaks of the frequency response. This problem is solved by using the genetic algorithm. To verify the proposed method, the simulation and numerical calculations is carried out on a nonlinear RC circuit and the results show that proposed method can able to approximate a high order bilinear model from 200 th order to the 1 st order better than the existing method.

Control Systems of Single-Phase Voltage Source Inverters for a UPS

This article presents considerations of the effectiveness of suppressing output voltage distortions of low power single-phase voltage source inverters (VSI) dedicated for UPS systems working with the nonlinear rectifier RC load defined in the EN 62040-3 standard. Various types of control systems were tested – PID/CDM and deadbeat instantaneous controllers designed using the author's discrete model (including the design of the output filter) of VSI and the fuzzy controller. It was shown that the additional control loop with the repetitive controller or additional input variables (currents) of the controller should be used for lowering the THD of the output voltage for the nonlinear load. The results of the experimental verification are shown.

Study of the inertial effect and the nonlinearities of the CRONE suspension based on the hydropneumatic technology

In this paper, we emphasize two main effects involved in the CRONE car suspension technology (CRONE: French acronym for Commande Robuste d’Ordre Non Entier). In a first time, we present the influence of the inductive or inertial effect of the pipes that links the different cells of the hydropneumatic car suspension. These components are mainly resistive and capacitive devices. Then, we analyze the nonlinear relations that link the hydraulic power variables (the flow and the pressure) of the hydraulic resistors and the hydropneumatic accumulators and we study the effect of the nonlinear terms on the car suspension response. Our study is based on the gamma RC arrangement developed in Altet et al. (In: Analysis and design of hybrid systems—proceedings of ADHS03, pp. 63–68. Elsevier, Amsterdam, 2003) and Serrier et al. (In: Proceedings of IDETC/CIE 2005: ASME 2005 international design engineering technical conferences and computers and information in engineering conference, Long Beach, CA, USA, 24–28 September 2005). In a second time, we focus only on the gamma RLC arrangement, introduced in Abi Zeid Daou et al. (Int. J. Electron. 96(12):1207–1223, 2009). We show whether the parasite effect due to the pipes or the nonlinear RC components affect the system’s response. The simulation results show that neither the inertial effect caused by these parasite pipes of one meter length nor the use of the nonlinear resistors or the accumulators modifies the response of the gamma RC arrangement.

직접변위기반설계법에 의한 철근콘크리트 기둥의 FRP 피복보강 내진성능설계법의 개발

본 연구에서는, 기존 철근 콘크리트 구조물에 적용된 직접 변위-기반 설계법을 적용 FRP 피복 보강된 성능개선 콘크리트 부재에 대한 정밀 비선형 휨 해석 및 내진성능설계의 구체적 알고리즘을 제시하였다. 비선형 휨 해석의 정밀 예측을 위하여 콘크리트 및 FRP 복합재료의 다축 구성관계를 고려하였으며, Chopra 등 (1999)이 제안한 직접 변위-기반 설계법(DDM)을 개선하여 철근콘크리트 기둥에 대한 성능개선을 위한 FRP 피복 보강을 위한 성능설계 알고리즘을 제시하였다. 제시된 직접 변위-기반 설계법은, 변위계수법과 비교하여, 비선형 거동이 큰 경우에도 목표 변위 성능 값에 대한 정확한 추정을 해준다. 이는 변위계수법이 항복 이전의 유효탄성계수를 사용하는 반면, 직접 변위-기반 설계법은 유효탄할선탄성계수를 고려하고 있어, 목표 변위에 따른 성능설계 평가에 있어서 보다 높은 연성비의 거동을 반영하고 있기 때문인 것으로 평가된다. In the current research, an algorithm of performance-based seismic retrofit design of reinforced concrete columns using FRP jacket has been proposed. For exact prediction of the nonlinear flexural analysis or FRP composite RC members, multiaxial constitutive laws of concrete and composite materials have been presented. For seismic retrofit design, an algorithm of direct displacement-based design method (DDM) proposed by Chopra and Goel (2001) has been newly applied to determine the design thickness of FRP jacket in seismic retrofit of reinforced concrete columns. To compare with the displacement coefficient method (DCM), the DDM gives an accurate prediction of the target displacement in highly nonlinear region, since the DCM uses the elastic stiffness before reaching the yield load as the effective stiffness but the DDM uses the secant stiffness.

Theoretical investigation of dielectric corona pre-ionization TEA nitrogen laser based on transmission line method

This paper models the dielectric corona pre-ionization, capacitor transfer type of flat-plane transmission line traveling wave transverse excited atmospheric pressure nitrogen laser by a non-linear lumped RLC electric circuit. The flat-plane transmission line and the pre-ionizer dielectric are modeled by a lumped linear RLC and time-dependent non-linear RC circuit, respectively. The main discharge region is considered as a time-dependent non-linear RLC circuit where its resistance value is also depends on the radiated pre-ionization ultra violet (UV) intensity. The UV radiation is radiated by the resistance due to the surface plasma on the pre-ionizer dielectric. The theoretical predictions are in a very good agreement with the experimental observations. The electric circuit equations (including the ionization rate equations), the equations of laser levels population densities and propagation equation of laser intensities, are solved numerically. As a result, the effects of pre-ionizer dielectric parameters on the electrical behavior and output laser intensity are obtained.