Time-domain Transient Response Research Articles

3.76-Gbps yellow-light visible light communication system over 1.2 m free space transmission utilizing a Si-substrate LED and a cascaded pre-equalizer network.

Recently, visible light communication (VLC) has emerged as a promising communication method in 6G. To achieve 6G high-speed transmission, wavelength division multiplexing (WDM) based VLC systems are a highly promising candidate. However, the "yellow and green gap" greatly limits the yellow light efficiency of InGaN-based LEDs and also restricts the transmission rate of yellow LEDs. In addition, pre-equalization and post-equalization also have an important impact on high-speed communication. In this paper, we propose to employ a vertical InGaN-based Si-substrate yellow LED with bit-power loading discrete multitone (DMT) modulation and a novel cascaded pre-equalizer network to achieve a high-speed yellow-light VLC system. The proposed cascaded pre-equalizer network is based on a digital Zobel network and a partial nonlinear pre-equalizer (DZNPN). The microscopic time-domain transient response of the high-speed and large-amplitude signal is also investigated to show a severe impairment. Utilizing the DZNPN cascaded pre-equalizer network based on the third-order Volterra series, a record-breaking data rate of 3.764Gbps over 1.2 m free space and 3.808Gbps over 0.7 m are experimentally demonstrated under the hard decision-forward error correction (HD-FEC) threshold of 3.8 × 10-3. The rate can be improved from 2.818Gbps to 3.764Gbps with 650Mbaud compared to the un-preprocessed signal. This is the highest data rate ever reported for yellow-light VLC systems based on a single LED to the best of our knowledge.

A New Induced GNSS Spoofing Detection Method Based on Weighted Second-Order Central Moment

Global navigation satellite system (GNSS) spoofing causes the victim receiver to deduce false positioning and timing data; this notably threatens navigational safety. Thus, anti-spoofing techniques that improve the reliability of GNSS systems, for which interference detection is critical, are essential. Based on the distortion of tracking loop correlation function symmetry of the target receiver caused by gradual adjustment of induced spoofing signals, we proposed a new induced spoofing detection method that uses the weighted second-order central moment (WSCM) difference in the time-domain transient response of multiple correlators of the left and right peaks to obtain the test statistic, theoretically proving that the test statistic follows Gaussian distribution. The Neyman-Pearson hypothesis test method is used to determine the optimal test threshold and determine whether the receiver is being spoofed. The proposed WSCM-based method for spoofing detection was compared with three conventional methods in Scenarios 4 and 7 of the Texas Spoofing Test Battery database, showing that the detection probability of the proposed method is at least 24.15% higher at a false alarm rate of 10% and is more advantageous at lower false alarm rates and the alert time is shortened by at least 30 seconds, enabling at least a 20% faster detection efficiency. The proposed method overcomes the problem of existing methods, which are associated with difficulties in capturing the subtle time-varying effects of the relative carrier phase between the spoofing and authentic signals; thus, it provides excellent detection accuracy and effectiveness, showing broad potential applicability in GNSS spoofing detection.

Time Domain Response Analyses of Multiconductor Transmission Lines Using L-Stable Single Step Multistage Block Method

In order to solve the non-physical oscillation problem of the traditional finite difference time domain(FDTD) scheme at the discontinuous solution, the L-stable single step multistage block method is proposed to analyze the time domain transient response of multiconductor transmission lines. In order to avoid the repeated inversion of the coefficient matrix of the system state equation when the boundary conditions are imposed, the more general Sherman-Morrison formula is used to solve the inverse matrix of the coefficient matrix after the boundary conditions are applied. This method is used to simulate uniform lossless multiconductor transmission lines (MTLs) and non-uniform lossy MTLs, and its simulation result is compared with the results given by FDTD algorithm. The results showed that the single step multistage block method can effectively suppress the numerical oscillation and is not limited by step size of simulation in time domain.

Extended Fractional-Order Jeffreys Model of Viscoelastic Hydraulic Cylinder

Abstract A novel modeling approach for viscoelastic hydraulic cylinders, with negligible inertial forces, is proposed, based on the extended fractional-order Jeffreys model. Analysis and physical reasoning for the parameter constraints and order of the fractional derivatives are provided. Comparison between the measured and computed frequency response functions and time domain transient response argues in favor of the proposed four-parameter fractional-order model.

Positioning Control of DC Servomotor-Based Antenna Using PID Tuned Compensator

Direct current (DC) servomotor-based parabolic antenna is automatically positioned using control technique to track satellite by maintaining the desired line of sight for quality transmission and reception of electromagnetic wave signals in telecommunication and broadcast applications. With several techniques proposed in the literature for parabolic antenna position control, there is still a need to improve the tracking error and robustness of the control system in the presence of disturbance. This paper has presented positioning control of DC servomotor-based antenna using proportional-integral-derivative (PID) tuned compensator (TC). The compensator was designed using the control and estimation tool manager (CETM) of MATLAB based on the PID tuning design method using robust response time tuning technique with interactive (adjustable performance and robustness) design mode at a bandwidth of 40.3 rad/s. The compensator was added to the position control loop of the DC servomotor–based satellite antenna system. Simulations were carried out in a MATLAB environment for four separate cases by applying unit forced input to examine the various step responses. In the first and second cases, simulations were conducted without the compensator (PID TC) in the control loop assuming zero input disturbance and unit input disturbance. The results obtained in terms of time-domain response parameters showed that with the introduction of unit disturbance, the rise time improved by 36 % (0.525–0.336 s) while the peak time, peak percentage overshoot, and settling time deteriorate by 16.3 % (1.29–1.50 s), 43.5 % (34.7–49.8 %), and 7.6 % (4.35–4.68 s), respectively. With the introduction of the PIDTC for the third case, there was an improvement in the system’s overall transient response performance parameters. Thus to provide further information on the improved performance offered by the compensator, the analysis was done in percentage improvement. Considering the compensated system assuming zero disturbance, the time-domain response performance parameters of the system improved by 94.1, 94.7, 73.1, and 97.1 % in terms of rising time (525–30.8 ms), peak time (1,290–67.9 ms), peak percentage overshoot (34.7–9.35 %), and settling time (4.35–0.124 s), respectively. In the fourth case, the compensator’s ability to provide robust performance in the presence of disturbance was examined by comparing the step response performance parameters of the uncompensated system with unit input disturbance to the step response performance parameters of the compensated system tagged: with PID TC + unit disturbance. The result shows that PID TC provided improved time-domain transient response performance of the disturbance handling of the system by 91.0, 95.4, 80.0, and 93.1 % in terms of rising time (336–30.5 ms), peak time (1500–69.1 ms), peak percentage overshoot (34.7–10.0), and settling time (4.68–0.325 s), respectively. The designed compensator provided improved robust and tracking performance while meeting the specified time-domain performance parameters in the presence of disturbance.

Failure-analysis method of soldering interfaces in light-emitting diode packages based on time-domain transient thermal response

New soldering-interface failure-analysis method based on the transient thermal response of the LED packages proposed. This method is based on the physical properties that the operating voltage of the LED packages is inversely proportional to the junction temperature and the change of the junction temperature, which is monitored by voltage, represents the change of thermal gradient in the LED packages. Fast time-domain algorithm for failure-sensitivity enhancement was developed. And the feasibility of this algorithm was verified using a two-point measurement method during a thermal shock test.

Theoretical analysis and experimental measurement of coupling dynamic characteristics for transversely isotropic rectangular plate based on modified FSDT assumption

The theoretical analysis of thick plate vibration behavior has been investigated in the literature, but most of the studies were focused on flexural dynamic characteristics and lack experimental verification. In this study, the analytical solutions based on the superposition method for both the flexural and extensional vibrations are presented to obtain resonant frequencies and associated mode shapes for a transversely isotropic thick rectangular plate. The displacement equilibrium equations and boundary conditions of the modified first-order shear deformation theory (FSDT) are derived by utilizing Hamilton’s principle and the variation method. To verify the validity of the theoretical model, the finite-element method (FEM) and impact experiment results for thick plates are employed in this work. Excellent agreement of resonant frequencies and associated mode shapes is obtained for FEM calculation and theoretical analysis. To excite vibrations of a thick rectangular plate, a steel ball controlled by an electromagnet is utilized. A steel ball is dropped freely from a height of 231 mm on the top of the plate surface, and a transient wave will be generated after the ball impact on the specimen. The frequency spectrum of the thick rectangular plate is constructed by using the fast Fourier transform of the time-domain transient response. The excited resonant frequencies obtained from experimental measurement are compared with theoretical results. The comparisons show that the modified FSDT provides an excellent prediction of the resonant frequencies and mode shapes for the dynamic characteristics of thick rectangular plates.

Transient Response and Charge Transport in Organic and Polymer Thin-Film Transistors

Organic thin-film transistors (TFTs) are very promising for several large-area applications particularly when mechanical flexibility is important. A detailed model that directly correlates the TFT time-domain transient response with charge transport and material properties is very desirable for circuit applications. Temperature-dependent measurements of the field effect transistor (FET) mobility have provided numerous insights on the characteristics of the charge carriers and nature of transport phenomena. However, in disordered semiconductors such as organics and polymers, the FET mobility μFET is very different from the trap-free mobility μ as most of the carriers remain trapped in the band-tail states. In such systems, determining the drift mobility becomes very important. To study this drift mobility, we analyze the time-domain response of the transistor. The time-domain response of transistors can be obtained through channel formation time measurements. In such measurements, carriers are injected at the source of the transistor using a voltage pulse and extracted at the drain. A large-signal time domain analysis of these electronic time-of-flight measurements was first done by J.R. Burns [1] nearly 50 years ago for metal-oxide-semiconductor (MOS) transistors and was later extended to organic thin-film transistors by D. Basu et al. [2]. However, the mathematical models used in both works assumed that mobility is insensitive to the variance in carrier density and temperature. Therefore, these models cannot accurately predict complex time-domain response in organic and polymer FETs, hence there exists the need for more comprehensive models that account for mobility dependence on carrier concentration and temperature. Indeed, the main mechanisms of charge transport in organic and polymer semiconductors are commonly accepted to be variable-range hopping (VRH) and multiple-trap and release (MTR). In MTR, trapped carriers are thermally excited into the band, where charge transport takes place. Both charge transport models predict a mobility that depends on the trap density of states of the material, carrier density, and lattice temperature and, thus a complete model must account for these parameters. This paper presents an extension to the work of Burns and Basu et al. that considers the effect of the multiple trap and release charge transport model on mobility. With the underlying assumption that the trap density of states in most high-mobility organic and polymer transistors can be modeled by a single exponential function, we can write a closed form non-linear partial differential equation that describes the time and spatial evolution of current and voltage in an organic or polymer FET. In this way, we account for relevant material and device operation parameters such as trap density of states, carrier density, and temperature and therefore present a much more complete model of the time-domain response of organic and polymer thin-film transistors while retaining ease of use. Given sufficient knowledge of material parameters, we are able to accurately model electronic time-of-flight measurements in organic and polymer thin film transistors across different device operation regimes and temperatures. This model can also be used to extract material parameters from channel formation measurements. We apply this more complete time-domain dynamic response model to experimental data from high-mobility donor-acceptor polymer based thin-film transistors measured in our group. [1] J. R. Burns, RCA Review, 30, 15, 1969. [2] Basu, Debarshi & Dodabalapur, Ananth. (1970). Drift Velocity and Drift Mobility Measurement in Organic Semiconductors Using Pulse Voltage. 10.1007/12_2009_4. Figure 1

Diagnostic of transformer winding deformation fault types using continuous wavelet transform of pulse response

Impulse Frequency Response Analysis (IFRA) provides an alternative technique for detection of mechanical type faults in power transformers among researchers. However, the conventional frequency response curve obtained from the time domain transient response only contains the frequency domain information of signal, and the time domain information is neglected. Furthermore, the traditional approach of using the fast Fourier transform (FFT) in processing the non-stationary signal could result in lack of useful information. This paper proposes a novel winding deformation fault diagnostic technique which is modified from IFRA, the detected transient signals of pulse response are processed based on the continuous wavelet transform (CWT) algorithm, and the wavelet time-frequency diagram are plotted and analyzed. The simulation of a simple transformer high frequency model and experiment analysis show that the various types of winding deformation can be distinguished by the proposed technique. The data processing result by the wavelet transform conforms with the variation pattern of frequency response to different winding fault types. Besides, the verification result of experiment indicates that the wavelet time-frequency diagram obtained by the proposed technique shows better performance than the frequency response curves obtained by the conventional FFT on processing the transient signals.

Adaptive Interpolated PI Gain Scheduling for Voltage Regulator in Solar Charge Controller Applications

Buck-boost converter is one of the dc-dc convert0.er that can both increase and decrease the value of output voltage. Due to its wide output range, this converter is very appropriate for using in solar-based electric generation systems. To control the stable expected output voltage, this converter is usually integrated with feedback control. One of the old and widely used control techniques is PID control. However, conventional PID controls still have deficiencies, because the parameters of PID parameters are static so that for wide ranges of input or load will provide different transient responses. This paper will present a new PI control with an adaptive interpolated PI gain scheduling technique. The proposed control algorithm has been embedded and implemented in real microcontroller hardware and its performance has been tested under load change conditions, and the input voltage changes within the range of 8-22 V. Testing results show that PI control with gain scheduling technique produces better transient response compared to the traditional fixed PI controller. The time domain transient response measurements, under load changes within the range of 20-1000 Ohm, present that the proposed control algorithm give settling time value below 1.0 second, rise-time below 0.436 second, maximum overshoot below 0.5%, and the steady-state error below 0.3 V.

A New Analytic Method to Tune a Fractional Order PID Controller

This paper proposes a new method to tune a fractional order PID controller. This method utilizes both the analytic and numeric approach to determine the controller parameters. The control design specifications that must be achieved by the control system are gain crossover frequency, phase margin, and peak magnitude at the resonant frequency, where the latter is a new design specification suggested by this paper. These specifications results in three equations in five unknown variables. Assuming that certain relations exist between two variables and discretizing one of them, a performance index can be evaluated and the optimal controller parameters that minimize this performance index are selected. As a case study, a third order linear time invariant system is taken as a process to be controlled and the proposed method is applied to design the controller. The resultant control system exactly fulfills the control design specification, a feature that is laked in numerical design methods. Through matlab simulation, the step response of the closed loop system with the proposed controller and a conventional PID controller demonstrate the performance of the system in terms of time domain transient response specifications (rise time, overshoot, and settling time).

Analytical Solutions for Distributed Interconnect Models—Part II: Arbitrary Input Response and Multicoupled Lines

In this paper, a new method is presented to calculate the exact analytical solution of distributed RC , LC , and RLC interconnects with a random input at an arbitrary point through the line. The proposed method, based on a modified Duhamel theorem, is used to calculate the time-domain transient response of the initially conditioned interconnects. This method is applied to a line driven by ramp and exponential inputs. The new analytical solutions are expressed as an infinite summation of sinusoidal terms. However, a negligible worst case error of <1% is observed for the expressions compared with HSPICE simulations for Fourier series with tens of terms. In addition, from these results a new model for transient response of a line considering the driver output resistance and capacitance is presented. Good accuracy is observed between the model and HSPICE simulations for various distributed interconnects and drivers. Furthermore, the developed solution is extended to include signal transient and crosstalk noise in multicoupled inductive-effect-prominent lines. In addition, arbitrary switching patterns for identical and nonidentical lines are investigated employing the new method and evaluated with HSPICE simulations.

Simulation of three-phase transformer inrush currents by using backward and numerical differentiation formulae

This paper presents a simplified model of a three-phase transformer developed in the state-space form using the linear graph theory. The algorithm for generating the coefficient matrixes of the state-space equation is described. Stiff detection procedures of differential equation systems that describe the three-phase transformer inrush current transients are explained. It is shown that the time-domain transient response of three-phase transformers mathematically describes extremely stiff systems. The numerical integration methods based on strong stable (A and L) backward differentiation formulae are used to solve extremely stiff differential equation systems arising from the state-space formulation of the transformer inrush current transient equations. A comparison of the measured and simulated three-phase transformer inrush currents showed very good agreement. The proposed procedure of modeling and the simulation method are useful tools that can be applied to other electrical transients where extremely stiff systems appear.

A Contribution to the Frequency Analysis and Transient Response of Power Transformer Windings

—This article proposes a new approach to study the frequency response and the transient analysis of power transformer windings. For improved accuracy, the suggested model includes, among other equivalent circuit elements, the mutual magnetic couplings between any winding turn and all others. This implies that the equivalent inductance of any considered turn will be a location-dependent parameter. Accordingly, the winding will be analyzed as a non-uniform transmission line. Through the application of a recursive circuit reduction technique, a closed-form Laplace s-domain analytical expression for the winding's input impedance can be obtained for any neutral treatment. The resulting expression can be used to determine the winding's series and parallel resonance frequencies. The s-domain expression for the input impedance, in connection with the numerical inverse Laplace transform, will be utilized for determination of the winding's time-domain transient response for any input voltage or current time waveform. Accuracy increases with the assumed number of winding sections, which can be even increased to the actual number of turns, limited only by the available computation resources. The results of case studies are in good agreement with those available in the literature using the time-domain solution of the simultaneous differential equations in the state variables.

Radio Propagation Path Loss Characteristics using the Time Domain Transient Response of Half-wavelength Dipole Antenna

본 논문에서는 시간영역에서 완전도체를 가정한 접지평면 위에 놓인 수직 반파장 다이폴에서 방사되는 전자기 과도응답해석을 통해 전파의 거리에 따른 전파경로손실을 해석하였다. 시간영역에서의 다이폴 안테나에 의한 방사특성을 구하기 위하여 주파수영역에서 방사되는 전기장을 유도하고 시간영역으로 변환하였다. 시간영역에서 거리와 송신 안테나의 높이에 따른 전기장의 과도응답특성을 계산하였으며, 유도된 식으로부터 거리에 따라 전파경로손실을 계산하였다. 본 논문의 결과는 시간영역에서의 전파채널특성 및 지표면 레이더 등에 응용될 수 있을 것이다.

Diagnostics of Analog Circuits Based on LS-SVM Using Time-Domain Features

Most researchers use wavelet transforms to extract features from a time-domain transient response from analog circuits to train classifiers such as neural networks (NNs) and support vector machines (SVMs) for analog circuit diagnostics. In this paper, we have proposed some new feature selection methods from a time-domain transient response, and compared the diagnostic results based on a least squares SVM (LS-SVM) using different time-domain feature vectors. First, we have improved two traditional feature selection methods: (a) using the mean and standard deviation in wavelet transform features, and (b) using the mean, standard deviation, skewness, kurtosis, and entropy in statistical property features. Then, a conventional time-domain feature vector based on the impulse response properties of a control system has been proposed. The simulation experiments for a leapfrog filter and a nonlinear rectifier show that: (1) the two improved methods have better accuracy than the traditional methods; (2) the proposed conventional time-domain feature vector is effective in the diagnostics of analog circuits—over 99 % for both of the two example circuits; (3) the proposed diagnostic method can diagnose soft faults, hard faults, and multi-faults, regardless of component tolerances and nonlinearity effects.

$A$-Stable and $L$-Stable High-Order Integration Methods for Solving Stiff Differential Equations

This paper describes a new A- and L-stable integration method for simulating the time-domain transient response of nonlinear circuits. The proposed method, which is based on the Obreshkov formula, can be made of arbitrary high order while maintaining the A-stability property. The new method allows for the adoption of higher order integration methods for the transient analysis of electronic circuits while enabling them to take larger step sizes without violating the stability, leading to faster simulations. The method can be run in an L-stable mode to handle circuits with extremely stiff equations. Necessary theoretical foundations, implementation details, error-control mechanisms, and computational results are presented.

Fourier transform ion cyclotron resonance spectroscopy

An ion cyclotron resonance (ICR) absorption spectrum has been obtained by exciting an ICR spectral segment with a fixed-frequency electric field pulse, followed by broad-band detection, digitization of the (time-domain) transient response, and digital Fourier transformation to produce the (frequency-domain) absorption spectrum. For a given signal-to-noise ratio and resolution, the FT-ICR method generates a spectrum in a time which is two orders of magnitude shorter than that required in conventional slow-sweep ICR detection. In the present example, a signal-to-noise ratio of 8 :1 and a mass resolution of about 0.005 amu for CH 4 + (from CH 4 at a pressure of 8 X 10 -7 torr) have been achieved, using a single data acquisition period of 25.6 msec.

Overshoot control for two coupled RLC interconnections

An algorithm is introduced to upgrade package performance for two coupled lines. A compromise between fast response and limited undershoot is based upon a 4% overshoot control condition. It is easy to use this time domain requirement because it can be applied to the transfer function in the frequency domain. In the frequency domain, it is known that a low-frequency approximation to the transfer function provides a simple and accurate trade-off requirement for single-mode overshoot control. For mixed mode, i.e. for the case of one driven line and one quiet line, it is shown here that the same approximation can be used to control the overshoot in the weak coupling case. A closed-form relationship among electrical line and termination parameters results. However, for strong coupling (small line spacing), the time domain transient response with parameters based on the closed-form relationship is inaccurate. For strong coupling it is shown here an average-transfer-function (ATF) method can be used for calculating trade-offs when multiple modes are excited.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Transient analysis of coupled, tapered transmission lines with arbitrary nonlinear terminations

A fast and efficient method of simulating the time-domain transient response of coupled, tapered transmission lines is presented. A time-domain scattering parameter formulation is used to derive the simple closed-form expression for the voltage variables for uniform lossless lines; this expression is applied to tapered lines by dividing the lines into many uniform section. Computational efficiency and stability are achieved using recursive time-domain algorithms. When a quasi-TEM propagation mode is assumed, the method is applicable to nonlinear terminations and inhomogeneous dielectric media. Memory requirements are minimized and are independent of the number of time steps. Simulation results showed good agreement with experimental results. >